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Hwang SJ, Kwon JG, Beckett EAH, Kim M, Herbert T, Sanders KM, Ward SM. Functional roles of interstitial cells of Cajal in the GI tract of rats. Am J Physiol Gastrointest Liver Physiol 2025; 328:G677-G695. [PMID: 40235202 DOI: 10.1152/ajpgi.00036.2025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2025] [Revised: 03/10/2025] [Accepted: 04/08/2025] [Indexed: 04/17/2025]
Abstract
Interstitial cells of Cajal (ICC) are distributed through the gastrointestinal (GI) tract, but the functional role of these cells comes primarily from studies of mice. Whether the functions of ICC are similar in larger animals is largely speculative. We investigated whether the Kit mutation in Ws/Ws rats had consequences on ICC populations in the stomach, small intestine, and colon and whether loss of ICC resulted in functional defects similar to Kit mutations in mice. Immunohistochemical labeling with c-KIT or ANO1 antibodies revealed loss of intramuscular ICC (ICC-IM) and reduced myenteric ICC (ICC-MY) in the stomachs of Ws/Ws mutants. Disruption of ICC-MY networks but not ICC within the deep muscular plexus (ICC-DMP) was observed in the small intestine. ICC in the proximal colon was reduced, but no population was absent. ICC loss in the stomach caused loss of spontaneous transient depolarizations, reduced pacemaker activity, and reduced responses to cholinergic and nitrergic nerve stimulation. Loss of ICC-MY in the small intestine resulted in abnormal pacemaker activity, but neural responses appeared to be normal. In the proximal colon, tonic inhibition due to ongoing nitrergic neural inputs was reduced, spontaneous spike complexes were less rhythmic, and nitrergic neural responses were reduced. Apamin-sensitive inhibitory neural responses were retained throughout the GI tract. In summary, Ws/Ws rats have lesions in ICC and functional deficits similar to, but not identical to, Kit mutant mice. These larger animals with more robust GI muscles may be useful for investigations into the role of ICC in normal and abnormal GI motility.NEW & NOTEWORTHY The physiological roles of interstitial cells of Cajal (ICC) throughout the gastrointestinal (GI) tract have been derived predominantly from studies of mice. We sought to determine whether reduction in ICC in the rat, a commonly used animal for studies of GI motor functions, leads to functional deficits. Ws/Ws rats display reduced ICC leading to a disruption in pacemaker activity and neuroeffector responses. Our results provide additional evidence for the functions of ICC in the GI tract.
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Affiliation(s)
- Sung Jin Hwang
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States
| | - Joong Goo Kwon
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States
| | - Elizabeth A H Beckett
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States
| | - Minkyung Kim
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States
| | - Tom Herbert
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States
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Athavale ON, Avci R, Clark AR, Di Natale MR, Wang X, Furness JB, Liu Z, Cheng LK, Du P. Neural regulation of slow waves and phasic contractions in the distal stomach: a mathematical model. J Neural Eng 2024; 20:066040. [PMID: 38100816 PMCID: PMC10765034 DOI: 10.1088/1741-2552/ad1610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 11/06/2023] [Accepted: 12/15/2023] [Indexed: 12/17/2023]
Abstract
Objective.Neural regulation of gastric motility occurs partly through the regulation of gastric bioelectrical slow waves (SWs) and phasic contractions. The interaction of the tissues and organs involved in this regulatory process is complex. We sought to infer the relative importance of cellular mechanisms in inhibitory neural regulation of the stomach by enteric neurons and the interaction of inhibitory and excitatory electrical field stimulation.Approach.A novel mathematical model of gastric motility regulation by enteric neurons was developed and scenarios were simulated to determine the mechanisms through which enteric neural influence is exerted. This model was coupled to revised and extended electrophysiological models of gastric SWs and smooth muscle cells (SMCs).Main results.The mathematical model predicted that regulation of contractile apparatus sensitivity to intracellular calcium in the SMC was the major inhibition mechanism of active tension development, and that the effect on SW amplitude depended on the inhibition of non-specific cation currents more than the inhibition of calcium-activated chloride current (kiNSCC= 0.77 vs kiAno1= 0.33). The model predicted that the interaction between inhibitory and excitatory neural regulation, when applied with simultaneous and equal intensity, resulted in an inhibition of contraction amplitude almost equivalent to that of inhibitory stimulation (79% vs 77% decrease), while the effect on frequency was overall excitatory, though less than excitatory stimulation alone (66% vs 47% increase).Significance.The mathematical model predicts the effects of inhibitory and excitatory enteric neural stimulation on gastric motility function, as well as the effects when inhibitory and excitatory enteric neural stimulation interact. Incorporation of the model into organ-level simulations will provide insights regarding pathological mechanisms that underpin gastric functional disorders, and allow forin silicotesting of the effects of clinical neuromodulation protocols for the treatment of these disorders.
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Affiliation(s)
- Omkar N Athavale
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Recep Avci
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Alys R Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Madeleine R Di Natale
- Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
- Department of Anatomy & Physiology, University of Melbourne, Parkville, VIC, Australia
| | - Xiaokai Wang
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
| | - John B Furness
- Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
- Department of Anatomy & Physiology, University of Melbourne, Parkville, VIC, Australia
| | - Zhongming Liu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
| | - Leo K Cheng
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Peng Du
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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Sanders KM, Drumm BT, Cobine CA, Baker SA. Ca 2+ dynamics in interstitial cells: foundational mechanisms for the motor patterns in the gastrointestinal tract. Physiol Rev 2024; 104:329-398. [PMID: 37561138 PMCID: PMC11281822 DOI: 10.1152/physrev.00036.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 06/29/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023] Open
Abstract
The gastrointestinal (GI) tract displays multiple motor patterns that move nutrients and wastes through the body. Smooth muscle cells (SMCs) provide the forces necessary for GI motility, but interstitial cells, electrically coupled to SMCs, tune SMC excitability, transduce inputs from enteric motor neurons, and generate pacemaker activity that underlies major motor patterns, such as peristalsis and segmentation. The interstitial cells regulating SMCs are interstitial cells of Cajal (ICC) and PDGF receptor (PDGFR)α+ cells. Together these cells form the SIP syncytium. ICC and PDGFRα+ cells express signature Ca2+-dependent conductances: ICC express Ca2+-activated Cl- channels, encoded by Ano1, that generate inward current, and PDGFRα+ cells express Ca2+-activated K+ channels, encoded by Kcnn3, that generate outward current. The open probabilities of interstitial cell conductances are controlled by Ca2+ release from the endoplasmic reticulum. The resulting Ca2+ transients occur spontaneously in a stochastic manner. Ca2+ transients in ICC induce spontaneous transient inward currents and spontaneous transient depolarizations (STDs). Neurotransmission increases or decreases Ca2+ transients, and the resulting depolarizing or hyperpolarizing responses conduct to other cells in the SIP syncytium. In pacemaker ICC, STDs activate voltage-dependent Ca2+ influx, which initiates a cluster of Ca2+ transients and sustains activation of ANO1 channels and depolarization during slow waves. Regulation of GI motility has traditionally been described as neurogenic and myogenic. Recent advances in understanding Ca2+ handling mechanisms in interstitial cells and how these mechanisms influence motor patterns of the GI tract suggest that the term "myogenic" should be replaced by the term "SIPgenic," as this review discusses.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
| | - Bernard T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Caroline A Cobine
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Salah A Baker
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
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Meng S, Fan M, Qian J, Zhang J, Xu H, Zheng Y, Zhao W, Shan L, Huang J. An Innovative Model of ISS-Based Multiple Fractures and Gastrointestinal Dysfunction Related to c-Kit Protein Expression on Interstitial Cells of Cajal. Orthop Surg 2023; 15:1325-1332. [PMID: 36919913 PMCID: PMC10157708 DOI: 10.1111/os.13599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 08/01/2022] [Accepted: 10/24/2022] [Indexed: 03/16/2023] Open
Abstract
OBJECTIVE Gastrointestinal dysfunction seriously affects the prognosis and quality of life of patients with multiple fractures. However, experimental evidence of this relationship is lacking. Here we describe a newly developed mouse model of postoperative gastrointestinal dysfunction after multiple fractures. METHODS Trauma severity was assessed using the injury severity score (ISS). Based on the ISS, a multiple fracture model was established in mice as follows: limb fractures with pelvic fractures and multiple rib fractures; limb fractures with multiple rib fractures; closed fracture of both forelegs with pelvic fracture and rib fractures; closed limb fractures; limb fracture with pelvic fracture; spinal fractures; hind leg fractures with pelvic fractures; pelvic fracture with multiple rib fractures; closed fracture of both fore legs with pelvic fracture; and closed fracture of both fore legs with multiple rib fractures. In each model group, gastrointestinal motility was assayed and the histopathology of the small intestine was examined. Western blot and immunohistochemical analyses of jejunal tissue were performed to detect c-kit protein expression, the level of which was compared with that of a control group. The results of ANOVA are expressed as mean ± standard deviation. RESULTS In mice with multiple fractures, food intake was greatly reduced, consistent with histopathological evidence of an injured intestinal epithelium. The jejunal tissue of mice in groups a, c, f, and h was characterized by extensively necrotic and exfoliated intestinal mucosal epithelium and inflammatory cell infiltration in the lamina propria. In the gastrointestinal function assay, gastrointestinal motility was significantly reduced in groups a, b, c, f, and g; these group also had a higher ISS (p < 0.01). The expression of c-kit protein in groups with gastrointestinal dysfunction was significantly up-regulated (p < 0.001) compared with the control group. The close correlation between c-kit expression and the ISS indicated an influence of trauma severity on gastrointestinal motility. CONCLUSION Gastrointestinal dysfunction after multiple fractures was successfully reproduced in a mouse model. In these mice, c-kit expression correlated with gastrointestinal tissue dysfunction and might serve as a therapeutic target.
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Affiliation(s)
- Shi‐Jie Meng
- The First Clinical CollegeZhejiang Chinese Medical UniversityHangzhouChina
| | - Meng‐Qiang Fan
- The First Clinical CollegeZhejiang Chinese Medical UniversityHangzhouChina
- Department of Orthopaedics & TraumatologyThe First Affiliated Hospital of Zhejiang Chinese Medical UniversityHangzhouChina
| | - Jian‐Sheng Qian
- The Third Clinical CollegeZhejiang Chinese Medical UniversityHangzhouChina
| | - Jing‐Wen Zhang
- Research and Development DepartmentCell Resource Bank and Integrated Cell Preparation Center of Xiaoshan DistrictHangzhouChina
| | - Hui‐Hui Xu
- The First Clinical CollegeZhejiang Chinese Medical UniversityHangzhouChina
| | - Yang Zheng
- The First Clinical CollegeZhejiang Chinese Medical UniversityHangzhouChina
- Department of Orthopaedics & TraumatologyThe First Affiliated Hospital of Zhejiang Chinese Medical UniversityHangzhouChina
| | - Wei‐Qiang Zhao
- The First Clinical CollegeZhejiang Chinese Medical UniversityHangzhouChina
- Department of Orthopaedics & TraumatologyThe First Affiliated Hospital of Zhejiang Chinese Medical UniversityHangzhouChina
| | - Le‐Tian Shan
- The First Clinical CollegeZhejiang Chinese Medical UniversityHangzhouChina
- Department of Orthopaedics & TraumatologyThe First Affiliated Hospital of Zhejiang Chinese Medical UniversityHangzhouChina
| | - Jie‐Feng Huang
- The First Clinical CollegeZhejiang Chinese Medical UniversityHangzhouChina
- Department of Orthopaedics & TraumatologyThe First Affiliated Hospital of Zhejiang Chinese Medical UniversityHangzhouChina
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Drumm BT, Hannigan KI, Lee JY, Rembetski BE, Baker SA, Koh SD, Cobine CA, Sanders KM. Ca 2+ signalling in interstitial cells of Cajal contributes to generation and maintenance of tone in mouse and monkey lower esophageal sphincters. J Physiol 2022; 600:2613-2636. [PMID: 35229888 DOI: 10.1113/jp282570] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/15/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The lower esophageal sphincter (LES) generates contractile tone preventing reflux of gastric contents into the esophagus. LES smooth muscle cells (SMCs) display depolarized membrane potentials facilitating activation of L-type Ca2+ channels. Interstitial cells of Cajal (ICC) express Ca2+ -activated Cl- channels encoded by Ano1 in mouse and monkey LES. Ca2+ signaling in ICC activates ANO1 currents in ICC. ICC displayed spontaneous Ca2+ transients in mice from multiple firing sites in each cell and no entrainment of Ca2+ firing between sites or between cells. Inhibition of ANO1 channels with a specific antagonist caused hyperpolarization of mouse LES and inhibition of tone in monkey and mouse LES muscles. Our data suggest a novel mechanism for LES tone in which Ca2+ transient activation of ANO1 channels in ICC generates depolarizing inward currents that conduct to SMCs to activate L-type Ca2+ currents, Ca2+ entry and contractile tone. ABSTRACT The lower esophageal sphincter (LES) generates tone and prevents reflux of gastric contents. LES smooth muscle cells (SMCs) are relatively depolarized, facilitating activation of Cav 1.2 channels to sustain contractile tone. We hypothesised that intramuscular interstitial cells of Cajal (ICC-IM), through activation of Ca2+ -activated-Cl- channels (ANO1), set membrane potentials of SMCs favorable for activation of Cav 1.2 channels. In some gastrointestinal muscles, ANO1 channels in ICC-IM are activated by Ca2+ transients, but no studies have examined Ca2+ dynamics in ICC-IM within the LES. Immunohistochemistry and qPCR were used to determine expression of key proteins and genes in ICC-IM and SMCs. These studies revealed that Ano1 and its gene product, ANO1 are expressed in c-Kit+ cells (ICC-IM) in mouse and monkey LES clasp muscles. Ca2+ signaling was imaged in situ, using mice expressing GCaMP6f specifically in ICC (Kit-KI-GCaMP6f). ICC-IM exhibited spontaneous Ca2+ transients from multiple firing sites. Ca2+ transients were abolished by CPA or caffeine but were unaffected by tetracaine or nifedipine. Maintenance of Ca2+ transients depended on Ca2+ influx and store reloading, as Ca2+ transient frequency was reduced in Ca2+ free solution or by Orai antagonist. Spontaneous tone of LES muscles from mouse and monkey was reduced ∼80% either by Ani9, an ANO1 antagonist or by the Cav 1.2 channel antagonist nifedipine. Membrane hyperpolarisation occurred in the presence of Ani9. These data suggest that intracellular Ca2+ activates ANO1 channels in ICC-IM in the LES. Coupling of ICC-IM to SMCs drives depolarization, activation of Cav 1.2 channels, Ca2+ entry and contractile tone. Abstract figure legend Proposed mechanism for generation of contractile tone in the lower esophageal sphincter (LES). Interstitial cells of Cajal (ICC) in the LES generate spontaneous, stochastic Ca2+ transients via Ca2+ release from the endoplasmic reticulum (ER). The Ca2+ transients activate ANO1 Cl- channels causing Cl- efflux (inward current). ANO1 currents have a depolarizing effect on ICC (+++s inside membrane) and this conducts through gap junctions (GJ) to smooth muscle cells (SMCs). Input from thousands of ICC results in depolarized membrane potentials (-40 to -50 mV) which is within the window current range for L-type Ca2+ channels. Activation of these channels causes Ca2+ influx, activation of contractile elements (CE) and development of tonic contraction. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Bernard T Drumm
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA.,Smooth Muscle Research Centre, Dundalk Institute of Technology, Ireland
| | - Karen I Hannigan
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Ji Yeon Lee
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Benjamin E Rembetski
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Salah A Baker
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Sang Don Koh
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Caroline A Cobine
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Kenton M Sanders
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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Analysis of Regional Variations of the Interstitial Cells of Cajal in the Murine Distal Stomach Informed by Confocal Imaging and Machine Learning Methods. Cell Mol Bioeng 2022; 15:193-205. [PMID: 35401841 PMCID: PMC8938532 DOI: 10.1007/s12195-021-00716-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 11/24/2021] [Indexed: 01/05/2023] Open
Abstract
Introduction The network of Interstitial Cells of Cajal (ICC) plays a plethora of key roles in maintaining, coordinating, and regulating the contractions of the gastrointestinal (GI) smooth muscles. Several GI functional motility disorders have been associated with ICC degradation. This study extended a previously reported 2D morphological analysis and applied it to 3D spatial quantification of three different types of ICC networks in the distal stomach guided by confocal imaging and machine learning methods. The characterization of the complex changes in spatial structure of the ICC network architecture contributes to our understanding of the roles that different types of ICC may play in post-prandial physiology, pathogenesis, and/or amelioration of GI dsymotility- bridging structure and function. Methods A validated classification method using Trainable Weka Segmentation was applied to segment the ICC from a confocal dataset of the gastric antrum of a transgenic mouse, followed by structural analysis of the segmented images. Results The machine learning model performance was compared to manually segmented subfields, achieving an area under the receiver-operating characteristic (AUROC) of 0.973 and 0.995 for myenteric ICC (ICC-MP; n = 6) and intramuscular ICC (ICC-IM; n = 17). The myenteric layer in the distal antrum increased in thickness (from 14.5 to 34 μm) towards the lesser curvature, whereas the thickness decreased towards the lesser curvature in the proximal antrum (17.7 to 9 μm). There was an increase in ICC-MP volume from proximal to distal antrum (406,960 ± 140,040 vs. 559,990 ± 281,000 μm3; p = 0.000145). The % of ICC volume was similar for ICC-LM and for ICC-CM between proximal (3.6 ± 2.3% vs. 3.1 ± 1.2%; p = 0.185) and distal antrum (3.2 ± 3.9% vs. 2.5 ± 2.8%; p = 0.309). The average % volume of ICC-MP was significantly higher than ICC-IM at all points throughout sample (p < 0.0001). Conclusions The segmentation and analysis methods provide a high-throughput framework of investigating the structural changes in extended ICC networks and their associated physiological functions in animal models.
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Electroacupuncture at Zusanli (ST36) Repairs Interstitial Cells of Cajal and Upregulates c-Kit Expression in Rats with SCI-Induced Neurogenic Bowel Dysfunction. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2020; 2020:8896123. [PMID: 33293999 PMCID: PMC7718052 DOI: 10.1155/2020/8896123] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/26/2020] [Accepted: 11/09/2020] [Indexed: 12/13/2022]
Abstract
Background Electroacupuncture (EA) could improve colonic transit activity in rats with neurogenic bowel dysfunction (NBD) caused by spinal cord injury (SCI). The function of interstitial cells of Cajal (ICCs) and c-Kit expression may play essential roles in this process. Material and Methods. Thirty-six Sprague Dawley rats were randomized to the sham group, the SCI group, or the SCI + EA group (bilateral Zusanli, 30 min/day, 14 days). Changes in the ultrastructural morphology of ICCs were observed. The c-Kit expression on different levels was analyzed by immunohistochemistry, Western blotting, and RT-qPCR, respectively. Results Abnormal morphology of ICCs and downregulation of the c-Kit expression occurred after SCI. While the number of ICCs was increased, the ultrastructural morphology was improved significantly in EA rats. They also showed better improvement in c-Kit expression at both protein and gene levels. Conclusion Abnormal ICCs in colon tissues and the downregulated expression of c-Kit could be observed after SCI. EA at Zusanli (ST36) could improve the colon function by repairing the morphology and increasing the number of ICCs and upregulating c-Kit expression.
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Mah SA, Avci R, Cheng LK, Du P. Current applications of mathematical models of the interstitial cells of Cajal in the gastrointestinal tract. WIREs Mech Dis 2020; 13:e1507. [PMID: 33026190 DOI: 10.1002/wsbm.1507] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/31/2020] [Accepted: 09/04/2020] [Indexed: 12/25/2022]
Abstract
The interstitial cells of Cajal (ICC) form interconnected networks throughout the gastrointestinal (GI) tract. ICC act as the pacemaker cells that initiate the rhythmic bioelectrical slow waves and intermediary between the GI musculature and nerves, both of which are critical to GI motility. Disruptions to the number of ICC and the integrity of ICC networks have been identified as a key pathophysiological mechanism in a number of clinically challenging GI disorders. The current analyses of ICC generally rely on either functional recordings taken directly from excised tissue or morphological analysis based on images of labeled ICC, where the structural-functional relationship is investigated in an associative manner rather than mechanistically. On the other hand, computational physiology has played a significant role in facilitating our understanding of a number of physiological systems in both health and disease, and investigations in the GI field are beginning to incorporate several mathematical models of the ICC. The main aim of this review is to present the major modeling advances in GI electrophysiology, in order to introduce a multi-scale framework for mathematically quantifying the functional consequences of ICC degradation at both cellular and tissue scales. The outcomes will inform future investigators utilizing modeling techniques in their studies. This article is categorized under: Metabolic Diseases > Computational Models.
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Affiliation(s)
- Sue Ann Mah
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Recep Avci
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Leo K Cheng
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Peng Du
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.,Department of Engineering Science, University of Auckland, Auckland, New Zealand
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9
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Wang X, Zhang S, Pasricha PJ, Chen JDZ. Ameliorating effects of sacral neuromodulation on gastric and small intestinal dysmotility mediated via a sacral afferent-vagal efferent pathway. Neurogastroenterol Motil 2020; 32:e13837. [PMID: 32189439 DOI: 10.1111/nmo.13837] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/04/2020] [Accepted: 02/18/2020] [Indexed: 02/08/2023]
Abstract
BACKGROUND/AIMS In a recent study of sacral nerve stimulation (SNS) for colonic inflammation, a possible spinal-vagal pathway was implicated. The aim of this study was to provide evidence for such a pathway by investigating the effects of SNS on dysmotility of the stomach and duodenum that are not directly innervated by the sacral efferents. METHODS Twenty-seven rats were chronically implanted with wire electrodes for SNS and gastrointestinal slow waves. SNS was performed in several acute sessions to investigate its effects on gastric/duodenal slow waves and emptying/transit impaired by glucagon and rectal distention (RD). RESULTS (a) SNS increased the percentage of normal gastric slow waves impaired by glucagon (from 53.9% to 77.0%, P < .0001) and RD (from 64% to 78%, P = .037). This improvement was abolished by atropine. (b) Similar effects were observed with SNS on duodenal slow waves, which was also blocked by atropine. (c) SNS normalized delayed gastric emptying induced by glucagon (control: 61.3%, glucagon: 44.3%, glucagon + SNS: 65.8%) and RD (control: 61.3%, RD: 46.7%, RD + SNS: 64.3%). It also normalized small intestinal transit delayed by RD (P = .001, RD + SNS vs RD; P = .9, RD + SNS vs control). (4) Both glucagon and RD induced an increase in the sympathovagal ratio (P = .007, glucagon vs baseline; P < .001, RD vs baseline) and SNS decreased the ratio (P = .006, glucagon + SNS vs glucagon; P = .04, RD + SNS vs RD). CONCLUSIONS Neuromodulation of the sacral nerve improves gastric and small intestinal pacemaking activity and transit impaired by glucagon and RD by normalizing the sympathovagal balance via a retrograde neural pathway from the sacral nerve to vagal efferents.
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Affiliation(s)
- Ximeng Wang
- Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Shengai Zhang
- Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Pankaj J Pasricha
- Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jiande D Z Chen
- Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland
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10
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Hannigan KI, Bossey AP, Foulkes HJL, Drumm BT, Baker SA, Ward SM, Sanders KM, Keef KD, Cobine CA. A novel intramuscular Interstitial Cell of Cajal is a candidate for generating pacemaker activity in the mouse internal anal sphincter. Sci Rep 2020; 10:10378. [PMID: 32587396 PMCID: PMC7316801 DOI: 10.1038/s41598-020-67142-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 06/03/2020] [Indexed: 12/14/2022] Open
Abstract
The internal anal sphincter (IAS) generates phasic contractions and tone. Slow waves (SWs) produced by interstitial cells of Cajal (ICC) underlie phasic contractions in other gastrointestinal regions. SWs are also present in the IAS where only intramuscular ICC (ICC-IM) are found, however the evidence linking ICC-IM to SWs is limited. This study examined the possible relationship between ICC-IM and SWs by recording Ca2+ transients in mice expressing a genetically-encoded Ca2+-indicator in ICC (Kit-Cre-GCaMP6f). A role for L-type Ca2+ channels (CavL) and anoctamin 1 (ANO1) was tested since each is essential for SW and tone generation. Two distinct ICC-IM populations were identified. Type I cells (36% of total) displayed localised asynchronous Ca2+ transients not dependent on CavL or ANO1; properties typical of ICC-IM mediating neural responses in other gastrointestinal regions. A second novel sub-type, i.e., Type II cells (64% of total) generated rhythmic, global Ca2+ transients at the SW frequency that were synchronised with neighbouring Type II cells and were abolished following blockade of either CavL or ANO1. Thus, the spatiotemporal characteristics of Type II cells and their dependence upon CavL and ANO1 all suggest that these cells are viable candidates for the generation of SWs and tone in the IAS.
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Affiliation(s)
- Karen I Hannigan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Aaron P Bossey
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Holly J L Foulkes
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Kathleen D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Caroline A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA.
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11
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Wang Q, Zang J, Huang X, Lu H, Xu W, Chen J. Colonic Dysmotility in Murine Partial Colonic Obstruction Due to Functional Changes in Interstitial Cells. J Neurogastroenterol Motil 2019; 25:589-601. [PMID: 31587550 PMCID: PMC6786438 DOI: 10.5056/jnm19136] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 08/07/2019] [Accepted: 08/27/2019] [Indexed: 12/11/2022] Open
Abstract
Background/Aims Interstitial cells play important roles in gastrointestinal (GI) neuro-smooth muscle transmission. The underlying mechanisms of colonic dysmotility have not been well illustrated. We established a partial colon obstruction (PCO) mouse model to investigate the changes of interstitial cells and the correlation with colonic motility. Methods Western blot technique was employed to observe the protein expressions of Kit, platelet-derived growth factor receptor-α (Pdgfra), Ca2+-activated Cl− (Ano1) channels, and small conductance Ca2+- activated K+ (SK) channels. Colonic migrating motor complexes (CMMCs) and isometric force measurements were employed in control mice and PCO mice. Results PCO mice showed distended abdomen and feces excretion was significantly reduced. Anatomically, the colon above the obstructive silicone ring was obviously dilated. Kit and Ano1 proteins in the colonic smooth muscle layer of the PCO colons were significantly decreased, while the expression of Pdgfra and SK3 proteins were significantly increased. The effects of a nitric oxide synthase inhibitor (L-NAME) and an Ano1 channel inhibitor (NPPB) on CMMC and colonic spontaneous contractions were decreased in the proximal and distal colons of PCO mice. The SK agonist, CyPPA and antagonist, apamin in PCO mice showed more effect to the CMMCs and colonic smooth muscle contractions. Conclusions Colonic transit disorder may be due to the downregulation of the Kit and Ano1 channels and the upregulation of SK3 channels in platelet-derived growth factor receptor-α positive (PDGFRα+) cells. The imbalance between interstitial cells of Cajal-Ano1 and PDGFRα-SK3 distribution might be a potential reason for the colonic dysmotility.
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Affiliation(s)
- Qianqian Wang
- Department of Pediatric Surgery, Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.,Department of Pediatric Surgery, Jiaxing Maternity and Child Health Care Hospital, Jiaxing, China
| | - Jingyu Zang
- Department of Pediatric Surgery, Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.,Department of Pediatric Surgery, Jiaxing Maternity and Child Health Care Hospital, Jiaxing, China
| | - Xu Huang
- Department of Anatomy and Physiology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Hongli Lu
- Department of Anatomy and Physiology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Wenxie Xu
- Department of Pediatric Surgery, Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.,Department of Anatomy and Physiology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Jie Chen
- Department of Pediatric Surgery, Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.,Department of Pediatric Surgery, Jiaxing Maternity and Child Health Care Hospital, Jiaxing, China
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12
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Li L, Zou C, Zhou Z, Wang X, Yu X. Phenotypic changes of interstitial cells of Cajal after intestinal obstruction in rat model. ACTA ACUST UNITED AC 2019; 52:e8343. [PMID: 31618295 PMCID: PMC6799941 DOI: 10.1590/1414-431x20198343] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 08/12/2019] [Indexed: 11/22/2022]
Abstract
The objective was to study the effect of mechanical intestinal obstruction in rats on the phenotype of interstitial cells of Cajal (ICC). Healthy Wistar rats were randomly divided into sham-operation group (C), one day obstruction group (M1), two days obstruction group (M2), and three days obstruction group (M3), with 10 rats in each group. The expression of SCF mRNA and c-Kit protein in intestinal tissue was investigated by RT-PCR and immunohistochemistry. Compared with the sham-operation group, the relative expression of SCF mRNA and the expression of c-Kit protein in intestinal tissue were significantly decreased in both obstruction groups. Levels decreased gradually with the prolongation of obstruction time, and significantly decreased on the 3rd day after obstruction (P<0.05). Immunohistochemical staining of the small intestine showed that the number of ICC in the sham-operation group was the highest, and they were gradually decreased with the extension of obstruction time in the M1 to M3 groups. There was a significant difference between groups (P<0.05). Intestinal obstruction caused a decrease in the concentrations of SCF mRNA and c-Kit protein in ICC. With the prolongation of intestinal obstruction, the number of ICCs gradually decreased.
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Affiliation(s)
- Lin Li
- Department of Gastrointestinal Surgery, Tianjin Nankai Hospital, Tianjin, China.,Tianjin Medical University NanKai Hospital, Tianjin, China
| | - Changlin Zou
- Department of Gastrointestinal Surgery, Tianjin Nankai Hospital, Tianjin, China.,Tianjin Medical University NanKai Hospital, Tianjin, China
| | - Zhenli Zhou
- Department of Gastrointestinal Surgery, Tianjin Nankai Hospital, Tianjin, China.,Tianjin Medical University NanKai Hospital, Tianjin, China
| | - Ximo Wang
- Department of Gastrointestinal Surgery, Tianjin Nankai Hospital, Tianjin, China.,Tianjin Medical University NanKai Hospital, Tianjin, China
| | - Xiangyang Yu
- Department of Gastrointestinal Surgery, Tianjin Nankai Hospital, Tianjin, China.,Tianjin Medical University NanKai Hospital, Tianjin, China
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13
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Abstract
KIT is a receptor tyrosine kinase that after binding to its ligand stem cell factor activates signaling cascades linked to biological processes such as proliferation, differentiation, migration and cell survival. Based on studies performed on SCF and/or KIT mutant animals that presented anemia, sterility, and/or pigmentation disorders, KIT signaling was mainly considered to be involved in the regulation of hematopoiesis, gametogenesis, and melanogenesis. More recently, novel animal models and ameliorated cellular and molecular techniques have led to the discovery of a widen repertoire of tissue compartments and functions that are being modulated by KIT. This is the case for the lung, heart, nervous system, gastrointestinal tract, pancreas, kidney, liver, and bone. For this reason, the tyrosine kinase inhibitors that were originally developed for the treatment of hemato-oncological diseases are being currently investigated for the treatment of non-oncological disorders such as asthma, rheumatoid arthritis, and alzheimer's disease, among others. The beneficial effects of some of these tyrosine kinase inhibitors have been proven to depend on KIT inhibition. This review will focus on KIT expression and regulation in healthy and pathologic conditions other than cancer. Moreover, advances in the development of anti-KIT therapies, including tyrosine kinase inhibitors, and their application will be discussed.
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14
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Veličkov A, Radenković G, Petrović V, Veličkov A. DIABETIC ALTERATIONS OF INTERSTITIAL CELLS OF CAJAL. ACTA MEDICA MEDIANAE 2017. [DOI: 10.5633/amm.2017.0416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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15
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Radenkovic G, Radenkovic D, Velickov A. Development of interstitial cells of Cajal in the human digestive tract as the result of reciprocal induction of mesenchymal and neural crest cells. J Cell Mol Med 2017; 22:778-785. [PMID: 29193736 PMCID: PMC5783873 DOI: 10.1111/jcmm.13375] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 08/08/2017] [Indexed: 01/02/2023] Open
Abstract
Neural crest cells (NCC) can migrate into different parts of the body and express their strong inductive potential. In addition, they are multipotent and are able to differentiate into various cell types with diverse functions. In the primitive gut, NCC induce differentiation of muscular structures and interstitial cells of Cajal (ICC), and they themselves differentiate into the elements of the enteric nervous system (ENS), neurons and glial cells. ICC develop by way of mesenchymal cell differentiation in the outer parts of the primitive gut wall around the myenteric plexus (MP) ganglia, with the exception of colon, where they appear simultaneously also at the submucosal border of the circular muscular layer around the submucosal plexus (SMP) ganglia. However, in a complex process of reciprocal induction of NCC and local mesenchyma, c‐kit positive precursors are the first to differentiate, representing probably the common precursors of ICC and smooth muscle cells (SMC). C‐kit positive precursors could represent a key impact factor regarding the final differentiation of NCC into neurons and glial cells with neurons subsequently excreting stem cell factor (SCF) and other signalling molecules. Under the impact of SCF, a portion of c‐kit positive precursors lying immediately around the ganglia differentiate into ICC, while the rest differentiate into SMC.
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Affiliation(s)
- Goran Radenkovic
- Department of Histology and Embryology, Faculty of Medicine, University of Nis, Nis, Serbia
| | - Dina Radenkovic
- UCL Medical School, University College London (UCL), London, UK
| | - Aleksandra Velickov
- Department of Histology and Embryology, Faculty of Medicine, University of Nis, Nis, Serbia
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16
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Jiménez-Herrera S, Ochando-Pulido JM, Martínez-Ferez A. Comparison between different liquid-liquid and solid phase methods of extraction prior to the identification of the phenolic fraction present in olive oil washing wastewater from the two-phase olive oil extraction system. GRASAS Y ACEITES 2017. [DOI: 10.3989/gya.0225171] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Phenolic compounds from olive mill wastewater (OMW), are characterized by a strong antioxidant activity. At the same time, they represent an environmental problem because they are difficult to degrade. The purpose of this work was to identify these biologically active compounds in the OMW from two-phase olive oil production in order to convert a polluting residue into a source of natural antioxidants. After optimizing the extraction process of phenolic compounds using liquid-liquid extraction (LLE) and solid phase extraction (SPE) methods, it was determined that the most appropriate sequence comprised a previous centrifugation to remove the lipid fraction, followed by liquid extraction with ethyl acetate or SPE. The most important compounds identified in olive oil washing wastewater (OOWW) were tyrosol, hydroxytyrosol and succinic acid; whereas the ones in the wastewater derived from the washing of the olives (OWW) were cresol, catechol, 4-methylcatechol, hydrocinnamic acid and p-hydroxy-hydrocinnamic acid.
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17
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Sanders KM, Kito Y, Hwang SJ, Ward SM. Regulation of Gastrointestinal Smooth Muscle Function by Interstitial Cells. Physiology (Bethesda) 2017; 31:316-26. [PMID: 27488743 DOI: 10.1152/physiol.00006.2016] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Interstitial cells of mesenchymal origin form gap junctions with smooth muscle cells in visceral smooth muscles and provide important regulatory functions. In gastrointestinal (GI) muscles, there are two distinct classes of interstitial cells, c-Kit(+) interstitial cells of Cajal and PDGFRα(+) cells, that regulate motility patterns. Loss of these cells may contribute to symptoms in GI motility disorders.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada; and
| | - Yoshihiko Kito
- Department of Pharmacology, Faculty of Medicine, Saga University, Nabeshima, Japan
| | - Sung Jin Hwang
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada; and
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada; and
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18
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Rodriguez-Tapia ES, Naidoo V, DeVries M, Perez-Medina A, Galligan JJ. R-Type Ca 2+ channels couple to inhibitory neurotransmission to the longitudinal muscle in the guinea-pig ileum. Exp Physiol 2017; 102:299-313. [PMID: 28008669 DOI: 10.1113/ep086027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 12/13/2016] [Indexed: 12/17/2022]
Abstract
NEW FINDINGS What is the central question of this study? Subtypes of enteric neurons are coded by the neurotransmitters they synthesize, but it is not known whether enteric neuron subtypes might also be coded by other proteins, including calcium channel subtypes controlling neurotransmitter release. What is the main finding and its importance? Our data indicate that guinea-pig ileum myenteric neuron subtypes may be coded by calcium channel subtypes. We found that R-type calcium channels are expressed by inhibitory but not excitatory longitudinal muscle motoneurons. R-Type calcium channels are also not expressed by circular muscle inhibitory motoneurons. Calcium channel subtype-selective antagonists could be used to target subtypes of neurons to treat gastrointestinal motility disorders. There is evidence that R-type Ca2+ channels contribute to synaptic transmission in the myenteric plexus. It is unknown whether R-type Ca2+ channels contribute to neuromuscular transmission. We measured the effects of the nitric oxide synthase inhibitor nitro-l-arginine (NLA), Ca2+ channel blockers and apamin (SK channel blocker) on neurogenic relaxations and contractions of the guinea-pig ileum longitudinal muscle-myenteric plexus (LMMP) in vitro. We used intracellular recordings to measure inhibitory junction potentials. Immunohistochemical techniques localized R-type Ca2+ channel protein in the LMMP and circular muscle. Cadmium chloride (pan-Ca2+ channel blocker) blocked and NLA and NiCl2 (R-type Ca2+ channel blocker) reduced neurogenic relaxations in a non-additive manner. Nickel chloride did not alter neurogenic cholinergic contractions, but it potentiated neurogenic non-cholinergic contractions. Relaxations were inhibited by apamin, NiCl2 and NLA and were blocked by combined application of these drugs. Relaxations were reduced by NiCl2 or ω-conotoxin (N-type Ca2+ channel blocker) and were blocked by combined application of these drugs. Longitudinal muscle inhibitory junction potentials were inhibited by NiCl2 but not MRS 2179 (P2Y1 receptor antagonist). Circular muscle inhibitory junction potentials were blocked by apamin, MRS 2179, ω-conotoxin and CdCl2 but not NiCl2 . We conclude that neuronal R-type Ca2+ channels contribute to inhibitory neurotransmission to longitudinal muscle but less so or not all in the circular muscle of the guinea-pig ileum.
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Affiliation(s)
| | - Vinogran Naidoo
- The Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA
| | - Matthew DeVries
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, 48824, USA
| | - Alberto Perez-Medina
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, 48824, USA
| | - James J Galligan
- The Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA.,Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, 48824, USA
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19
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Shaylor LA, Hwang SJ, Sanders KM, Ward SM. Convergence of inhibitory neural inputs regulate motor activity in the murine and monkey stomach. Am J Physiol Gastrointest Liver Physiol 2016; 311:G838-G851. [PMID: 27634009 PMCID: PMC5130542 DOI: 10.1152/ajpgi.00062.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 09/12/2016] [Indexed: 01/31/2023]
Abstract
Inhibitory motor neurons regulate several gastric motility patterns including receptive relaxation, gastric peristaltic motor patterns, and pyloric sphincter opening. Nitric oxide (NO) and purines have been identified as likely candidates that mediate inhibitory neural responses. However, the contribution from each neurotransmitter has received little attention in the distal stomach. The aims of this study were to identify the roles played by NO and purines in inhibitory motor responses in the antrums of mice and monkeys. By using wild-type mice and mutants with genetically deleted neural nitric oxide synthase (Nos1-/-) and P2Y1 receptors (P2ry1-/-) we examined the roles of NO and purines in postjunctional inhibitory responses in the distal stomach and compared these responses to those in primate stomach. Activation of inhibitory motor nerves using electrical field stimulation (EFS) produced frequency-dependent inhibitory junction potentials (IJPs) that produced muscle relaxations in both species. Stimulation of inhibitory nerves during slow waves terminated pacemaker events and associated contractions. In Nos1-/- mice IJPs and relaxations persisted whereas in P2ry1-/- mice IJPs were absent but relaxations persisted. In the gastric antrum of the non-human primate model Macaca fascicularis, similar NO and purine neural components contributed to inhibition of gastric motor activity. These data support a role of convergent inhibitory neural responses in the regulation of gastric motor activity across diverse species.
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Affiliation(s)
- Lara A. Shaylor
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sung Jin Hwang
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Kenton M. Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sean M. Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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20
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Baker SA, Drumm BT, Saur D, Hennig GW, Ward SM, Sanders KM. Spontaneous Ca(2+) transients in interstitial cells of Cajal located within the deep muscular plexus of the murine small intestine. J Physiol 2016; 594:3317-38. [PMID: 26824875 DOI: 10.1113/jp271699] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/24/2016] [Indexed: 01/13/2023] Open
Abstract
KEY POINTS Interstitial cells of Cajal at the level of the deep muscular plexus (ICC-DMP) in the small intestine generate spontaneous Ca(2+) transients that consist of localized Ca(2+) events and limited propagating Ca(2+) waves. Ca(2+) transients in ICC-DMP display variable characteristics: from discrete, highly localized Ca(2+) transients to regionalized Ca(2+) waves with variable rates of occurrence, amplitude, duration and spatial spread. Ca(2+) transients fired stochastically, with no cellular or multicellular rhythmic activity being observed. No correlation was found between the firing sites in adjacent cells. Ca(2+) transients in ICC-DMP are suppressed by the ongoing release of inhibitory neurotransmitter(s). Functional intracellular Ca(2+) stores are essential for spontaneous Ca(2+) transients, and the sarco/endoplasmic reticulum Ca(2+) -ATPase (SERCA) pump is necessary for maintenance of spontaneity. Ca(2+) release mechanisms involve both ryanodine receptors (RyRs) and inositol triphosphate receptors (InsP3 Rs). Release from these channels is interdependent. ICC express transcripts of multiple RyRs and InsP3 Rs, with Itpr1 and Ryr2 subtypes displaying the highest expression. ABSTRACT Interstitial cells of Cajal in the deep muscular plexus of the small intestine (ICC-DMP) are closely associated with varicosities of enteric motor neurons and generate responses contributing to neural regulation of intestinal motility. Responses of ICC-DMP are mediated by activation of Ca(2+) -activated Cl(-) channels; thus, Ca(2+) signalling is central to the behaviours of these cells. Confocal imaging was used to characterize the nature and mechanisms of Ca(2+) transients in ICC-DMP within intact jejunal muscles expressing a genetically encoded Ca(2+) indicator (GCaMP3) selectively in ICC. ICC-DMP displayed spontaneous Ca(2+) transients that ranged from discrete, localized events to waves that propagated over variable distances. The occurrence of Ca(2+) transients was highly variable, and it was determined that firing was stochastic in nature. Ca(2+) transients were tabulated in multiple cells within fields of view, and no correlation was found between the events in adjacent cells. TTX (1 μm) significantly increased the occurrence of Ca(2+) transients, suggesting that ICC-DMP contributes to the tonic inhibition conveyed by ongoing activity of inhibitory motor neurons. Ca(2+) transients were minimally affected after 12 min in Ca(2+) free solution, indicating these events do not depend immediately upon Ca(2+) influx. However, inhibitors of sarco/endoplasmic reticulum Ca(2+) -ATPase (SERCA) pump and blockers of inositol triphosphate receptor (InsP3 R) and ryanodine receptor (RyR) channels blocked ICC Ca(2+) transients. These data suggest an interdependence between RyR and InsP3 R in the generation of Ca(2+) transients. Itpr1 and Ryr2 were the dominant transcripts expressed by ICC. These findings provide the first high-resolution recording of the subcellular Ca(2+) dynamics that control the behaviour of ICC-DMP in situ.
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Affiliation(s)
- Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Dieter Saur
- II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar der TU München, München, Germany
| | - Grant W Hennig
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
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Gallego D, Mañé N, Gil V, Martínez-Cutillas M, Jiménez M. Mechanisms responsible for neuromuscular relaxation in the gastrointestinal tract. REVISTA ESPANOLA DE ENFERMEDADES DIGESTIVAS 2016; 108:721-731. [DOI: 10.17235/reed.2016.4058/2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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22
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Workplace Health Promotion and Wellbeing. ScientificWorldJournal 2015; 2015:606875. [PMID: 26380362 PMCID: PMC4563109 DOI: 10.1155/2015/606875] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 07/13/2015] [Indexed: 12/25/2022] Open
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Effect of da-cheng-qi decoction on the repair of the injured enteric nerve-interstitial cells of cajal-smooth muscle cells network in multiple organ dysfunction syndrome. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2014; 2014:596723. [PMID: 25477993 PMCID: PMC4247919 DOI: 10.1155/2014/596723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 10/18/2014] [Accepted: 10/21/2014] [Indexed: 01/22/2023]
Abstract
Wistar rats were randomly divided into control group, multiple organ dysfunction syndrome (MODS) group, and Da-Cheng-Qi decoction (DCQD) group. The network of enteric nerves-interstitial cells of Cajal- (ICC-) smooth muscle cells (SMC) in small intestine was observed using confocal laser scanning microscopy and transmission electron microscopy. The results showed that the numbers of cholinergic/nitriergic nerves, and the deep muscular plexus of ICC (ICC-DMP) and connexin43 (Cx43) in small intestine with MODS were significantly decreased. The network integrity of enteric nerves-ICC-SMC was disrupted. The ultrastructures of ICC-DMP, enteric nerves, and SMC were severely damaged. After treatment with DCQD, the damages were repaired and the network integrity of enteric nerves ICC-SMC was significantly recovered. In conclusion, the pathogenesis of gastrointestinal motility dysfunction in MODS in part may be due to the damages to enteric nerves-ICC-SMC network and gap junctions. The therapeutic mechanism of DCQD in part may be that it could repair the damages and maintain the integrity of enteric nerves ICC-SMC network.
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24
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Kito Y, Kurahashi M, Mitsui R, Ward SM, Sanders KM. Spontaneous transient hyperpolarizations in the rabbit small intestine. J Physiol 2014; 592:4733-45. [PMID: 25217377 DOI: 10.1113/jphysiol.2014.276337] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Four types of electrical activity were recorded and related to cell structure by intracellular recording and dye injection into impaled cells in muscles of rabbit small intestine. The specific cell types from which recordings were made were longitudinal smooth muscle cells (LSMCs), circular smooth muscle cells (CSMCs), interstitial cells of Cajal distributed in the myenteric region (ICC-MY) and fibroblast-like cells (FLCs). Slow waves (slow wavesSMC) were recorded from LSMCs and CSMCs. Slow waves (slow wavesICC) were of greatest amplitude (>50 mV) and highest maximum rate of rise (>10 V s(-1)) in ICC-MY. The dominant activity in FLCs was spontaneous transient hyperpolarizations (STHs), with maximum amplitudes above 30 mV. STHs were often superimposed upon small amplitude slow waves (slow wavesFLC). STHs displayed a cyclical pattern of discharge irrespective of background slow wave activity. STHs were inhibited by MRS2500 (3 μm), a P2Y1 antagonist, and abolished by apamin (0.3 μm), a blocker of small conductance Ca(2+)-activated K(+) channels. Small amplitude STHs (<15 mV) were detected in smooth muscle layers, whereas STHs were not resolved in cells identified as ICC-MY. Electrical field stimulation evoked purinergic inhibitory junction potentials (IJPs) in CSMCs. Purinergic IJPs were not recorded from ICC-MY. These results suggest that FLCs may regulate smooth muscle excitability in the rabbit small intestine via generation of rhythmic apamin-sensitive STHs. Stimulation of P2Y1 receptors modulates the amplitudes of STHs. Our results also suggest that purinergic inhibitory motor neurons regulate the motility of the rabbit small intestine by causing IJPs in FLCs that conduct to CSMCs.
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Affiliation(s)
- Yoshihiko Kito
- Department of Pharmacology, Faculty of Medicine, Saga University, Nabeshima, Saga, 849-8501, Japan Department of Cell Physiology, Nagoya City University Medical School, Mizuho-ku, Nagoya, 467-8601, Japan
| | - Masaaki Kurahashi
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, 89557, USA
| | - Retsu Mitsui
- Department of Cell Physiology, Nagoya City University Medical School, Mizuho-ku, Nagoya, 467-8601, Japan
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, 89557, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, 89557, USA
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25
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Jiménez M, Clavé P, Accarino A, Gallego D. Purinergic neuromuscular transmission in the gastrointestinal tract; functional basis for future clinical and pharmacological studies. Br J Pharmacol 2014; 171:4360-75. [PMID: 24910216 DOI: 10.1111/bph.12802] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 05/14/2014] [Accepted: 05/24/2014] [Indexed: 12/13/2022] Open
Abstract
Nerve-mediated relaxation is necessary for the correct accomplishment of gastrointestinal (GI) motility. In the GI tract, NO and a purine are probably released by the same inhibitory motor neuron as inhibitory co-transmitters. The P2Y1 receptor has been recently identified as the receptor responsible for purinergic smooth muscle hyperpolarization and relaxation in the human gut. This finding has been confirmed in P2Y1 -deficient mice where purinergic neurotransmission is absent and transit time impaired. However, the mechanisms responsible for nerve-mediated relaxation, including the identification of the purinergic neurotransmitter(s) itself, are still debatable. Possibly different mechanisms of nerve-mediated relaxation are present in the GI tract. Functional demonstration of purinergic neuromuscular transmission has not been correlated with structural studies. Labelling of purinergic neurons is still experimental and is not performed in routine pathology studies from human samples, even when possible neuromuscular impairment is suspected. Accordingly, the contribution of purinergic neurotransmission in neuromuscular diseases affecting GI motility is not known. In this review, we have focused on the physiological mechanisms responsible for nerve-mediated purinergic relaxation providing the functional basis for possible future clinical and pharmacological studies on GI motility targeting purine receptors.
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Affiliation(s)
- Marcel Jiménez
- Department of Cell Biology, Physiology and Immunology, Neurosciences Institute, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain
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Blair PJ, Rhee PL, Sanders KM, Ward SM. The significance of interstitial cells in neurogastroenterology. J Neurogastroenterol Motil 2014; 20:294-317. [PMID: 24948131 PMCID: PMC4102150 DOI: 10.5056/jnm14060] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 06/06/2014] [Accepted: 06/07/2014] [Indexed: 12/21/2022] Open
Abstract
Smooth muscle layers of the gastrointestinal tract consist of a heterogeneous population of cells that include enteric neurons, several classes of interstitial cells of mesenchymal origin, a variety of immune cells and smooth muscle cells (SMCs). Over the last number of years the complexity of the interactions between these cell types has begun to emerge. For example, interstitial cells, consisting of both interstitial cells of Cajal (ICC) and platelet-derived growth factor receptor alpha-positive (PDGFRα(+)) cells generate pacemaker activity throughout the gastrointestinal (GI) tract and also transduce enteric motor nerve signals and mechanosensitivity to adjacent SMCs. ICC and PDGFRα(+) cells are electrically coupled to SMCs possibly via gap junctions forming a multicellular functional syncytium termed the SIP syncytium. Cells that make up the SIP syncytium are highly specialized containing unique receptors, ion channels and intracellular signaling pathways that regulate the excitability of GI muscles. The unique role of these cells in coordinating GI motility is evident by the altered motility patterns in animal models where interstitial cell networks are disrupted. Although considerable advances have been made in recent years on our understanding of the roles of these cells within the SIP syncytium, the full physiological functions of these cells and the consequences of their disruption in GI muscles have not been clearly defined. This review gives a synopsis of the history of interstitial cell discovery and highlights recent advances in structural, molecular expression and functional roles of these cells in the GI tract.
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Affiliation(s)
- Peter J Blair
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA; and
| | - Poong-Lyul Rhee
- Division of Gastroenterology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA; and
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA; and
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Blair PJ, Rhee PL, Sanders KM, Ward SM. The significance of interstitial cells in neurogastroenterology. J Neurogastroenterol Motil 2014. [PMID: 24948131 DOI: 10.5056/jnm140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Smooth muscle layers of the gastrointestinal tract consist of a heterogeneous population of cells that include enteric neurons, several classes of interstitial cells of mesenchymal origin, a variety of immune cells and smooth muscle cells (SMCs). Over the last number of years the complexity of the interactions between these cell types has begun to emerge. For example, interstitial cells, consisting of both interstitial cells of Cajal (ICC) and platelet-derived growth factor receptor alpha-positive (PDGFRα(+)) cells generate pacemaker activity throughout the gastrointestinal (GI) tract and also transduce enteric motor nerve signals and mechanosensitivity to adjacent SMCs. ICC and PDGFRα(+) cells are electrically coupled to SMCs possibly via gap junctions forming a multicellular functional syncytium termed the SIP syncytium. Cells that make up the SIP syncytium are highly specialized containing unique receptors, ion channels and intracellular signaling pathways that regulate the excitability of GI muscles. The unique role of these cells in coordinating GI motility is evident by the altered motility patterns in animal models where interstitial cell networks are disrupted. Although considerable advances have been made in recent years on our understanding of the roles of these cells within the SIP syncytium, the full physiological functions of these cells and the consequences of their disruption in GI muscles have not been clearly defined. This review gives a synopsis of the history of interstitial cell discovery and highlights recent advances in structural, molecular expression and functional roles of these cells in the GI tract.
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Affiliation(s)
- Peter J Blair
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Poong-Lyul Rhee
- Division of Gastroenterology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
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Abstract
Smooth muscles are complex tissues containing a variety of cells in addition to muscle cells. Interstitial cells of mesenchymal origin interact with and form electrical connectivity with smooth muscle cells in many organs, and these cells provide important regulatory functions. For example, in the gastrointestinal tract, interstitial cells of Cajal (ICC) and PDGFRα(+) cells have been described, in detail, and represent distinct classes of cells with unique ultrastructure, molecular phenotypes, and functions. Smooth muscle cells are electrically coupled to ICC and PDGFRα(+) cells, forming an integrated unit called the SIP syncytium. SIP cells express a variety of receptors and ion channels, and conductance changes in any type of SIP cell affect the excitability and responses of the syncytium. SIP cells are known to provide pacemaker activity, propagation pathways for slow waves, transduction of inputs from motor neurons, and mechanosensitivity. Loss of interstitial cells has been associated with motor disorders of the gut. Interstitial cells are also found in a variety of other smooth muscles; however, in most cases, the physiological and pathophysiological roles for these cells have not been clearly defined. This review describes structural, functional, and molecular features of interstitial cells and discusses their contributions in determining the behaviors of smooth muscle tissues.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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Lies B, Gil V, Groneberg D, Seidler B, Saur D, Wischmeyer E, Jiménez M, Friebe A. Interstitial cells of Cajal mediate nitrergic inhibitory neurotransmission in the murine gastrointestinal tract. Am J Physiol Gastrointest Liver Physiol 2014; 307:G98-106. [PMID: 24833707 DOI: 10.1152/ajpgi.00082.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Nitric oxide (NO) is a major inhibitory neurotransmitter in the gastrointestinal (GI) tract. Its main effector, NO-sensitive guanylyl cyclase (NO-GC), is expressed in several GI cell types, including smooth muscle cells (SMC), interstitial cells of Cajal (ICC), and fibroblast-like cells. Up to date, the interplay between neurons and these cells to initiate a nitrergic inhibitory junction potential (IJP) is unclear. Here, we investigate the origin of the nitrergic IJP in murine fundus and colon. IJPs were determined in fundus and colon SMC of mice lacking NO-GC globally (GCKO) and specifically in SMC (SM-GCKO), ICC (ICC-GCKO), and both SMC/ICC (SM/ICC-GCKO). Nitrergic IJP was abolished in ICC-GCKO fundus and reduced in SM-GCKO fundus. In the colon, the amplitude of nitrergic IJP was reduced in ICC-GCKO, whereas nitrergic IJP in SM-GCKO was reduced in duration. These results were corroborated by loss of the nitrergic IJP in global GCKO. In conclusion, our results prove the obligatory role of NO-GC in ICC for the initiation of an IJP. NO-GC in SMC appears to enhance the nitrergic IJP, resulting in a stronger and prolonged hyperpolarization in fundus and colon SMC, respectively. Thus NO-GC in both cell types is mandatory to induce a full nitrergic IJP. Our data from the colon clearly reveal the nitrergic IJP to be biphasic, resulting from individual inputs of ICC and SMC.
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Affiliation(s)
- Barbara Lies
- Physiologisches Institut, Universität Würzburg, Würzburg, Germany
| | - Víctor Gil
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, CIBERehd, Instituto de Salud Carlos III, Barcelona, Spain; and
| | - Dieter Groneberg
- Physiologisches Institut, Universität Würzburg, Würzburg, Germany
| | - Barbara Seidler
- II. Medizinische Klinik und Poliklinik, Technische Universität München, München, Germany
| | - Dieter Saur
- II. Medizinische Klinik und Poliklinik, Technische Universität München, München, Germany
| | | | - Marcel Jiménez
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, CIBERehd, Instituto de Salud Carlos III, Barcelona, Spain; and
| | - Andreas Friebe
- Physiologisches Institut, Universität Würzburg, Würzburg, Germany;
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Lies B, Groneberg D, Friebe A. Toward a better understanding of gastrointestinal nitrergic neuromuscular transmission. Neurogastroenterol Motil 2014; 26:901-12. [PMID: 24827638 DOI: 10.1111/nmo.12367] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 04/21/2014] [Indexed: 12/30/2022]
Abstract
BACKGROUND Nitric oxide (NO) is an important inhibitory neurotransmitter in the gastrointestinal (GI) tract. The majority of nitrergic effects are transduced by NO-sensitive guanylyl cyclase (NO-GC) as the receptor for NO, and, thus, mediated by cGMP-dependent mechanisms. Work carried out during the past years has demonstrated NO to be largely involved in GI smooth muscle relaxation and motility. However, detailed investigation of nitrergic signaling has turned out to be complicated as NO-GC was identified in several different GI cell types such as smooth muscle cells, interstitial cells of Cajal and fibroblast-like cells. With regards to nitrergic neurotransmission, special focus has been placed on the role of interstitial cells of Cajal using mutant mice with reduced populations of ICC. Recently, global and cell-specific knockout mice for enzymes participating in nitrergic signaling have been generated providing a suitable approach to further examine the role of NO-mediated signaling in GI smooth muscle. PURPOSE This review discusses the current knowledge on nitrergic mechanisms in gastrointestinal neuromuscular transmission with a focus on genetic models and outlines possible further investigations to gain better understanding on NO-mediated effects in the GI tract.
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Affiliation(s)
- B Lies
- Physiologisches Institut I, Universität Würzburg, Würzburg, Germany
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Winston JH, Chen J, Shi XZ, Sarna SK. Inflammation induced by mast cell deficiency rather than the loss of interstitial cells of Cajal causes smooth muscle dysfunction in W/W(v) mice. Front Physiol 2014; 5:22. [PMID: 24550836 PMCID: PMC3912454 DOI: 10.3389/fphys.2014.00022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 01/09/2014] [Indexed: 01/19/2023] Open
Abstract
The initial hypothesis suggested that the interstitial cells of Cajal (ICC) played an essential role in mediating enteric neuronal input to smooth muscle cells. Much information for this hypothesis came from studies in W/Wv mice lacking ICC. However, mast cells, which play critical roles in regulating inflammation in their microenvironment, are also absent in W/Wv mice. We tested the hypothesis that the depletion of mast cells in W/Wv mice generates inflammation in fundus muscularis externa (ME) that impairs smooth muscle reactivity to Ach, independent of the depletion of ICC. We performed experiments on the fundus ME from wild type (WT) and W/Wv mice before and after reconstitution of mast cells by bone marrow transplant. We found that mast cell deficiency in W/Wv mice significantly increased COX-2 and iNOS expression and decreased smooth muscle reactivity to Ach. Mast cell reconstitution or concurrent blockade of COX-2 and iNOS restored smooth muscle contractility without affecting the suppression of c-kit in W/Wv mice. The expression of nNOS and ChAT were suppressed in W/Wv mice; mast cell reconstitution did not restore them. We conclude that innate inflammation induced by mast cell deficiency in W/Wv mice impairs smooth muscle contractility independent of ICC deficiency. The impairment of smooth muscle contractility and the suppression of the enzymes regulating the synthesis of Ach and NO in W/Wv mice need to be considered in evaluating the role of ICC in regulating smooth muscle and enteric neuronal function in W/Wv mice.
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Affiliation(s)
- John H Winston
- Division of Gastroenterology, Department of Internal Medicine, Enteric Neuromuscular Disorders and Visceral Pain Center, The University of Texas Medical Branch at Galveston Galveston, TX, USA
| | - Jinghong Chen
- Division of Gastroenterology, Department of Internal Medicine, Enteric Neuromuscular Disorders and Visceral Pain Center, The University of Texas Medical Branch at Galveston Galveston, TX, USA
| | - Xuan-Zheng Shi
- Division of Gastroenterology, Department of Internal Medicine, Enteric Neuromuscular Disorders and Visceral Pain Center, The University of Texas Medical Branch at Galveston Galveston, TX, USA
| | - Sushil K Sarna
- Division of Gastroenterology, Department of Internal Medicine, Enteric Neuromuscular Disorders and Visceral Pain Center, The University of Texas Medical Branch at Galveston Galveston, TX, USA
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Min YW, Hong YS, Ko EJ, Lee JY, Min BH, Sohn TS, Kim JJ, Rhee PL. Impairment of the proximal to distal tonic gradient in the human diabetic stomach. Neurogastroenterol Motil 2014; 26:229-36. [PMID: 24165095 DOI: 10.1111/nmo.12253] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 09/26/2013] [Indexed: 02/06/2023]
Abstract
BACKGROUND Little has been known about the contractile characteristics of diabetic stomach. We investigated spontaneous contractions and responses to acetylcholine in the gastric muscle in diabetic patients and non-diabetic control subjects according to the region of stomach. METHODS Gastric specimens were obtained from 26 diabetics and 55 controls who underwent gastrectomy at Samsung Medical Center between February 2008 and November 2011. Isometric force measurements were performed using circular muscle strips from the different regions of stomach under basal condition and in response to acetylcholine. KEY RESULTS Basal tone of control was higher in the proximal stomach than in the distal (0.63 g vs 0.46 g, p = 0.027). However, in diabetics, basal tone was not significantly different between the proximal and distal stomach (0.75 g vs 0.62 g, p = 0.32). The distal stomach of diabetics had higher basal tone and lower frequency than that of control (0.62 g vs 0.46 g, p = 0.049 and 4.0/min vs 4.9/min, p = 0.049, respectively). After exposure to acetylcholine, dose-dependent increases of basal tone, peak, and area under the curve (AUC) were noticed in both proximal and distal stomach of the two groups. In the proximal stomach, however, the dose-dependent increase of basal tone and AUC was less prominent in diabetics than in control. CONCLUSIONS & INFERENCES On the contrary to control, the proximal to distal tonic gradient was not observed in diabetic stomach. Diabetic stomach also had lower frequency of spontaneous contraction in the distal stomach and less acetylcholine-induced positive inotropic effect in the proximal stomach than control.
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Affiliation(s)
- Y W Min
- Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Baker SA, Hennig GW, Salter AK, Kurahashi M, Ward SM, Sanders KM. Distribution and Ca(2+) signalling of fibroblast-like (PDGFR(+)) cells in the murine gastric fundus. J Physiol 2013; 591:6193-208. [PMID: 24144881 DOI: 10.1113/jphysiol.2013.264747] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Platelet-derived growth factor receptor α positive (PDGFRα(+)) cells are suggested to mediate purinergic inputs in GI muscles, but the responsiveness of these cells to purines in situ has not been evaluated. We developed techniques to label and visualize PDGFRα(+) cells in murine gastric fundus, load cells with Ca(2+) indicators, and follow their activity via digital imaging. Immunolabelling demonstrated a high density of PDGFRα(+) cells in the fundus. Cells were isolated and purified by fluorescence-activated cell sorting (FACS) using endogenous expression of enhanced green fluorescent protein (eGFP) driven off the Pdgfra promoter. Quantitative PCR showed high levels of expression of purinergic P2Y1 receptors and SK3 K(+) channels in PDGFRα(+) cells. Ca(2+) imaging was used to characterize spontaneous Ca(2+) transients and responses to purines in PDGFRα(+) cells in situ. ATP, ADP, UTP and β-NAD elicited robust Ca(2+) transients in PDGFRα(+) cells. Ca(2+) transients were also elicited by the P2Y1-specific agonist (N)-methanocarba-2MeSADP (MRS-2365), and inhibited by MRS-2500, a P2Y1-specific antagonist. Responses to ADP, MRS-2365 and β-NAD were absent in PDGFRα(+) cells from P2ry1((-/-)) mice, but responses to ATP were retained. Purine-evoked Ca(2+) transients were mediated through Ca(2+) release mechanisms. Inhibitors of phospholipase C (U-73122), IP3 (2-APB), ryanodine receptors (Ryanodine) and SERCA pump (cyclopiazonic acid and thapsigargin) abolished Ca(2+) transients elicited by purines. This study provides a link between purine binding to P2Y1 receptors and activation of SK3 channels in PDGFRα(+) cells. Activation of Ca(2+) release is likely to be the signalling mechanism in PDGFRα(+) cells responsible for the transduction of purinergic enteric inhibitory input in gastric fundus muscles.
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Affiliation(s)
- Salah A Baker
- K. M. Sanders: Department of Physiology and Cell Biology, University of Nevada School of Medicine, MS 352, Reno, NV 89557, USA.
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Koh SD, Rhee PL. Ionic Conductance(s) in Response to Post-junctional Potentials. J Neurogastroenterol Motil 2013; 19:426-32. [PMID: 24199003 PMCID: PMC3816177 DOI: 10.5056/jnm.2013.19.4.426] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 08/28/2013] [Accepted: 08/30/2013] [Indexed: 01/29/2023] Open
Abstract
The gastrointestinal motility is regulated by extrinsic and intrinsic neural regulation. Intrinsic neural pathways are controlled by sensory input, inter-neuronal relay and motor output. Enteric motor neurons release many transmitters which affect post-junctional responses. Post-junctional responses can be excitatory and inhibitory depending on neurotransmitters. Excitatory neurotransmitters induce depolarization and contraction. In contrast, inhibitory neurotransmitters hyperpolarize and relaxe the gastrointestinal smooth muscle. Smooth muscle syncytium is composed of smooth muscle cells, interstitial cells of Cajal and platelet-derived growth factor receptor α-positive (PDGFRα(+)) cells (SIP syncytium). Specific expression of receptors and ion channels in these cells can be affected by neurotransmitters. In recent years, molecular reporter expression techniques are able to study the properties of ion channels and receptors in isolated specialized cells. In this review, we will discuss the mechanisms of ion channels to interpret the post-junctional responses in the gastrointestinal smooth muscles.
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Affiliation(s)
- Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada, School of Medicine, Reno, NV, USA
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Xu X, Wang BM, Yu QX, Sun C. Expression of transient receptor potential channels and cholinergic muscarinic acetylcholine receptors in human gastrointestinal stromal tumors. Shijie Huaren Xiaohua Zazhi 2013; 21:845-850. [DOI: 10.11569/wcjd.v21.i10.845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the expression of transient receptor potential channels (TRPCs) and cholinergic muscarinic acetylcholine receptors (CHRMs) in human gastrointestinal stromal tumors (GISTs).
METHODS: Immunohistochemical method was used to detect the expression of TRPC and CHRM in GISTs.
RESULTS: GISTs expressed TRPC1, TRPC3, CHRM2 and CHRM3, and the positive rate was 57.5%, 47.5%, 22.5% and 55.0%, respectively. The expression levels of TRPC and CHRM decreased as the malignant potential grade of biological behaviors GISTs increased.
CONCLUSION: Our finding that GISTs express TRPC1, TRPC3, CHRM2 and CHRM3 provides new evidence for the origination of GIST from interstitial cells of Cajal.
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Gil V, Martínez-Cutillas M, Mañé N, Martín MT, Jiménez M, Gallego D. P2Y(1) knockout mice lack purinergic neuromuscular transmission in the antrum and cecum. Neurogastroenterol Motil 2013; 25:e170-82. [PMID: 23323764 DOI: 10.1111/nmo.12060] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Pharmacological studies using selective P2Y(1) antagonists, such as MRS2500, and studies with P2Y(1)(-/-) knockout mice have demonstrated that purinergic neuromuscular transmission is mediated by P2Y(1) receptors in the colon. The aim of the present study was to test whether P2Y(1) receptors are involved in purinergic neurotransmission in the antrum and cecum. METHODS Microelectrode recordings were performed on strips from the antrum and cecum of wild type animals (WT) and P2Y(1)(-/-) mice. KEY RESULTS In the antrum, no differences in resting membrane potential and slow wave activity were observed between groups. In WT animals, electrical field stimulation elicited a MRS2500-sensitive inhibitory junction potential (IJP). In P2Y(1)(-/-) mice, a nitrergic IJP (N(ω) -nitro-l-arginine-sensitive), but not a purinergic IJP was recorded. This IJP was equivalent to the response obtained in strips from WT animals previously incubated with MRS2500. Similar results were obtained in the cecum: 1- the purinergic IJP (MRS2500-sensitive) recorded in WT animals was absent in P2Y(1)(-/-) mice 2- nitrergic neurotransmission was preserved in both groups. Moreover, 1- spontaneous IJP (MRS2500-sensitive) could be recorded in WT, but not in P2Y(1)(-/-) mice 2- MRS2365 a P2Y(1) agonist caused smooth muscle hyperpolarization in WT, but not in P2Y(1) (-/-) animals, and 3- β-NAD caused smooth muscle hyperpolarization both in WT and P2Y(1)(-/-) animals. CONCLUSIONS & INFERENCES 1- P2Y(1) receptor is the general mechanism of purinergic inhibition in the gastrointestinal tract, 2- P2Y(1)(-/-) mouse is a useful animal model to study selective impairment of purinergic neurotransmission and 3- P2Y(1)(-/-) mouse might help in the identification of purinergic neurotransmitter(s).
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Affiliation(s)
- V Gil
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute, Universitat Autònoma de Barcelona, Bellaterra, Spain
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Won KJ, Sanders KM, Ward SM. Stretch-dependent sensitization of post-junctional neural effectors in colonic muscles. Neurogastroenterol Motil 2013; 25:e101-13. [PMID: 23279087 PMCID: PMC3552106 DOI: 10.1111/nmo.12059] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND The colon undergoes distension-induced changes in motor activity as luminal contents or feces increase wall pressure. Input from enteric motor neurons regulates this motility. Here we examined stretch-dependent responses in circular muscle strips of murine colon. METHODS Length ramps (6-31μm s(-1) ) were applied in the axis of the circular muscle layer in a controlled manner until 5 mN isometric force was reached. KEY RESULTS Length ramps produced transient membrane potential hyperpolarizations and attenuation of action potential (AP) complexes. Responses were reproducible when ramps were applied every 30 s. Stretch-dependent hyperpolarization was blocked by TTX, suggesting AP-dependent release of inhibitory neurotransmitter(s). Atropine did not potentiate stretch-induced hyperpolarizations, but increased compliance of the circular layer. N(ω)-nitro-L-arginine (L-NNA) inhibited stretch-dependent hyperpolarization and decreased muscle compliance, suggesting release of NO mediates stretch-dependent inhibition. Control membrane potential was restored by the NO donor sodium nitorprusside. Stretch-dependent hyperpolarizations were blocked by L-methionine, an inhibitor of stretch-dependent K(+) (SDK) channels in colonic muscles. Loss of interstitial cells of Cajal, elicited by Kit neutralizing antibody, also inhibited responses to stretch. In presence of L-NNA and apamin, stretch responses became excitatory and were characterized by membrane depolarization and increased AP firing. A neurokinin-1 receptor antagonist inhibited this stretch-dependent increase in excitability. CONCLUSIONS AND INFERENCES Our data show that stretch-dependent responses in colonic muscles require tonic firing of enteric inhibitory neurons, but reflex activation of neurons does not appear to be necessary. NO causes activation of SDK channels, and stretch of muscles further activates these channels, explaining the inhibitory response to stretch in colonic muscle strips.
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Affiliation(s)
- Kyung-Jong Won
- Department of Physiology & Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA, (775) 784-6061 or FAX (775) 784-6903,Department of Physiology, College of Medicine, Konkuk University, 322 Danwol-dong, Chungju 380-701, South Korea
| | - Kenton M. Sanders
- Department of Physiology & Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA, (775) 784-6061 or FAX (775) 784-6903
| | - Sean M. Ward
- Department of Physiology & Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA, (775) 784-6061 or FAX (775) 784-6903
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Si X, Huang L, Gong Y, Lu J, Lin L. Role of calcium in activation of hyperpolarization-activated cyclic nucleotide-gated channels caused by cholecystokinin octapeptide in interstitial cells of cajal. Digestion 2012; 85:266-75. [PMID: 22538231 DOI: 10.1159/000337077] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 02/07/2012] [Indexed: 02/04/2023]
Abstract
BACKGROUND Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels regulate pacemaker activity in some cardiac cells and neurons. Little is known about the effects of cholecystokinin octapeptide (CCK-8) on HCN channels and excitability of murine interstitial cells of Cajal (ICCs). METHODS In the present study, the effects and mechanisms of CCK-8 on HCN channels were investigated by measuring mechanical contraction of smooth muscle strips and ionic channels of ICCs in murine gastric antrum. RESULTS Sulfated CCK-8 (CCK-8S) was used, and we found that CCK-8S increased the contraction of smooth muscle strips in the gastric antrum, which could be suppressed by specific HCN channel blockers CsCl and ZD7288. Extracellular calcium could also intensify the contraction. Under the same conditions, when antral strips were exposed to calcium ion (Ca²⁺)-free solution, no significant changes could be recorded with CCK-8S or ZD7288. Isolated ICCs from the murine gastric antrum identified by specific c-Kit antibody primers were chosen for electrophysiological recordings. HCN current (I(h)) of cultured ICCs was studied by whole-cell patch clamp techniques. A spontaneous transient inward current was recorded in ICCs, which could be inhibited by addition of CsCl and ZD7288; the current proved to be I(h). CCK-8S-facilitated I(h) in cultured ICCs could be inhibited by CsCl and ZD7288. When cultured ICCs were exposed to Ca²⁺-free solution, no significant changes could be recorded by application of CCK-8S on I(h), which proved extracellular calcium might have an excitatory effect on HCN channels. CONCLUSION We demonstrate that HCN channels are present in ICCs in the murine gastric antrum; they might be an important regulator of ICC excitability and pacemaker activity and are strongly affected by CCK-8S. Extracellular calcium might be a trigger in the activation of HCN channels caused by CCK-8S in cultured ICCs.
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Affiliation(s)
- Xinmin Si
- Department of Gastroenterology, The First Affiliated Hospital of Nanjing Medical University, Guangzhou Road 300, Nanjing 210029, China.
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Roberts JA, Lukewich MK, Sharkey KA, Furness JB, Mawe GM, Lomax AE. The roles of purinergic signaling during gastrointestinal inflammation. Curr Opin Pharmacol 2012; 12:659-66. [PMID: 23063457 DOI: 10.1016/j.coph.2012.09.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 09/17/2012] [Accepted: 09/19/2012] [Indexed: 02/09/2023]
Abstract
Extracellular purines play important roles as neurotransmitters and paracrine mediators in the gastrointestinal (GI) tract. Inflammation of the GI tract causes marked changes in the release and extracellular catabolism of purines, and can modulate purinoceptor expression and/or signaling. The functional consequences of this include suppression of the purinergic component of inhibitory neuromuscular and neurovascular transmission, increased release of purines from immune and epithelial cells, loss of enteric neurons to damage through P2X(7) purinoceptors, and enhanced activation of pain fibres. The purinergic system represents an important target for drug therapies that may improve GI inflammation and its consequences.
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Affiliation(s)
- Jane A Roberts
- Department of Anatomy and Neurobiology, University of Vermont, Burlington, VT, USA
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Blair PJ, Bayguinov Y, Sanders KM, Ward SM. Relationship between enteric neurons and interstitial cells in the primate gastrointestinal tract. Neurogastroenterol Motil 2012; 24:e437-49. [PMID: 22805588 PMCID: PMC4854185 DOI: 10.1111/j.1365-2982.2012.01975.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Morphological studies have revealed a close anatomical relationship between enteric nerve terminals and intramuscular ICC (ICC-IM) which supports a role for ICC-IM as intermediaries in enteric motor neurotransmission. Recently, a second type of interstitial cell previously described as 'fibroblast-like' but can now be identified by platelet-derived growth factor receptor-α expression, has also been implicated in enteric neurotransmission in rodents. The present study was performed to determine if enteric nerve fibers form close anatomical relationships with ICC and PDGFRα(+) cells throughout the primate GI tract. METHODS Immunohistochemical experiments and confocal microscopy were performed to examine the relationship between excitatory and inhibitory motor neurons, ICC and PDGFRα(+) cells throughout the monkey GI tract. KEY RESULTS The pan neuronal marker. Protein gene product 9.5 (PGP9.5) was used to label all enteric neurons and substance-P (sub-P) and neuronal nitric oxide synthase (nNOS) to label excitatory and inhibitory neurons, respectively. Double labeling with Kit revealed that both classes of nerve fibers were closely apposed with ICC-IM in the stomach, small intestine and colon (taenia and inter-taenia regions), but not with ICC at the level of the myenteric plexus (ICC-MY). Varicose enteric nerve fibers were closely associated with ICC-IM for distances up to 250 μm. Both excitatory and inhibitory nerve fibers were also closely apposed to PDGFRα(+) cells throughout the primate GI tract. CONCLUSIONS & INFERENCES The close anatomical relationship between enteric nerve fibers and ICC-IM and PDGFRα(+) cells throughout the GI tract of the Cynomolgus monkey provides morphological evidence that these two classes of interstitial cells may provide a similar physiological function in primates as has been attributed in rodent animal models.
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Affiliation(s)
- P J Blair
- Department of Physiology & Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
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Carbone SE, Wattchow DA, Spencer NJ, Brookes SJH. Loss of responsiveness of circular smooth muscle cells from the guinea pig ileum is associated with changes in gap junction coupling. Am J Physiol Gastrointest Liver Physiol 2012; 302:G1434-44. [PMID: 22461022 DOI: 10.1152/ajpgi.00376.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Gap junction coupling and neuromuscular transmission to smooth muscle were studied in the first 4 h after preparations were set up in vitro. Intracellular recordings were made from smooth muscle cells of guinea pig ileum. Fast inhibitory junction potentials (IJPs) were small (1.3 ± 1.0 mV) in the first 30 min but increased significantly over the first 120 min to 15.8 ± 0.9 mV (n = 12, P < 0.001). Comparable increases in slow IJPs and excitatory junction potentials were also observed. During the same period, resting membrane potential depolarized from -58.8 ± 1.4 to -47.2 ± 0.4 mV (n = 12, P < 0.001). Input resistance, estimated by intracellular current injection, decreased in parallel (P < 0.05), and dye coupling, measured by intracellular injection of carboxyfluorescein, increased (P < 0.001). Input resistance was higher and dye coupling was less in longitudinal than circular smooth muscle cells. Gap junction blockers [carbenoxolone (100 μM), 18β-glycyrrhetinic acid (10 μM), and 2-aminoethoxydiphenyl borate (50 μM)] hyperpolarized coupled circular smooth muscle cells, reduced the amplitude of fast and slow IJPs and excitatory junction potentials, increased input resistance, and reduced dye coupling. Local application of ATP (10 mM) mimicked IJPs and showed comparable increases in amplitude over the first 120 min; carbenoxolone and 2-aminoethoxydiphenyl borate significantly reduced ATP-evoked hyperpolarizations in coupled cells. In contrast, synaptic transmission between myenteric neurons was not suppressed during the first 30 min. Gap junction coupling between circular smooth muscle cells in isolated preparations was initially disrupted but recovered over the next 120 min to a steady level. This was associated with potent effects on neuromuscular transmission and responses to exogenous ATP.
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Affiliation(s)
- Simona E Carbone
- Discipline of Human Physiology and Centre for Neuroscience, Flinders Medical Science and Technology, Flinders University, Adelaide, South Australia, Australia
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Radenkovic G. Two patterns of development of interstitial cells of Cajal in the human duodenum. J Cell Mol Med 2012; 16:185-92. [PMID: 21352475 PMCID: PMC3823104 DOI: 10.1111/j.1582-4934.2011.01287.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
At the end of the embryonic period of human development, c-kit immunoreactive (c-kit IR) cells identifiable as interstitial cells of Cajal (ICC) are present in the oesophagus and stomach wall. In the small and large bowel, c-kit-IR cells appear later (in the small bowel at 9 weeks, and in the colon at 10-12 weeks), also in the MP region. The object of this study was to determine the timing of appearance and distribution of c-kit IR cells in the human embryonic and foetal duodenum. I used immunohistochemistry to examine the embryonic and foetal duodenum for cells expressing CD117 (Kit), expressed by mature ICC and ICC progenitor cells and CD34 to identify presumed ICC progenitors. Enteric plexuses were examined by way of antineuron-specific enolase and the differentiation of smooth muscle cells was studied using antidesmin antibodies. At the end of the embryonic period of development, c-kit IR cells were solely present in the proximal duodenum in the form of a wide belt of densely packed cells around the inception of the myenteric plexus (MP) ganglia. In the distal duodenum, c-kit IR cells emerged at the beginning of the foetal period in the form of thin rows of pleomorphic cells at the level of the MP. From the beginning of the fourth month, the differences in the distribution of ICC in the different portions of the duodenum were established, and this relationship was still present in later developmental stages. In fact, in the proximal duodenum, ICC of the MP (ICC-MP), ICC of the circular muscle (ICC-CM) and ICC of the septa (ICC-SEP) were present, and in the distal duodenum ICC-MP and ICC-SEP only. In conclusion, in the humans there is a difference in the timing and patterns of development of ICC in the proximal duodenum compared to the distal duodenum.
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Affiliation(s)
- Goran Radenkovic
- Department of Histology and Embryology, University of Nis, Nis, Serbia.
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Bautista-Cruz F, Paterson WG. Evidence for altered circular smooth muscle cell function in lower esophageal sphincter of W/Wv mutant mice. Am J Physiol Gastrointest Liver Physiol 2011; 301:G1059-65. [PMID: 21885685 DOI: 10.1152/ajpgi.00020.2011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Nitrergic neurotransmission to gut smooth muscle is impaired in W/W(v) mutant mice, which lack intramuscular interstitial cells of Cajal (ICC-IM). In addition, these mice have been reported to have smaller amplitude unitary potentials (UPs) and a more negative resting membrane potential (RMP) than control mice. These abnormalities have been attributed to absence of ICC-IM, but it remains possible that they are due to alterations at the level of the smooth muscle itself. Amphotericin-B-perforated patch-clamp recordings and Ca(2+) imaging (fura 2) were compared between freshly isolated single circular smooth muscle cells (CSM) from W/W(v) mutant and control mice lower esophageal sphincter (LES). There was no significant difference in seal resistance, capacitance, or input resistance in response to applied electrotonic current pulses between CSM cells from W/W(v) mutants and controls. Compared with control mice, RMP was more negative and UPs significantly smaller in CSM cells from mutant mice LES. Administration of caffeine induced an inward current in cells from both mutant and control mice, but the current density was significantly larger in cells from W/W(v) mutants. Membrane potential hyperpolarization induced by sodium nitroprusside was larger in cells from control mice vs. W/W(v) mutants. In addition, intracellular Ca(2+) transients induced by caffeine were significantly increased in cells from mutants. These findings indicate that LES CSM is abnormal in W/W(v) mutant mice. Thus some physiological functions attributed to ICC-IM based on experiments in smooth muscle of ICC deficient mice may need to be reconsidered.
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Affiliation(s)
- Francisco Bautista-Cruz
- Gastrointestinal Diseases Research Unit, Kingston General Hospital, Department of Medicine, Queen's University Kingston, Ontario, Canada
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Kito Y. The functional role of intramuscular interstitial cells of Cajal in the stomach. J Smooth Muscle Res 2011; 47:47-53. [PMID: 21757854 DOI: 10.1540/jsmr.47.47] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Intramuscular interstitial cells of Cajal (ICC-IM) are found within the smooth muscle layers of the stomach. ICC-IM are mainly spindle shaped cells with bipolar processes orientated along the long axis of surrounding smooth muscle cells. ICC-IM make close contacts with nerve varicosities and form gap junctions with neighbouring smooth muscle cells, indicating that ICC-IM mediate enteric motor neurotransmission. These morphological properties of ICC-IM are similar throughout the stomach. However, the electrical properties of these cells differ from region to region. In the fundus, ICC-IM generate spontaneous transient depolarizations (STDs), resulting in an ongoing discharge of unitary potentials in the smooth muscle cells. ICC-IM in the corpus generate slow waves and as they fire at the highest frequency they serve as the dominant pacemaker cells in the stomach. On the other hand, ICC-IM in the antrum generate the secondary component of slow waves triggered by the initial component that propagates passively from myenteric ICC (ICC-MY). Thus, the different electrical properties of ICC-IM play a critical role in creating the distinct functions of the proximal and distal regions of the stomach such that the fundus acts as a reservoir of food, the corpus as a dominant pacemaker region, while the antrum acts as a region for mixing and propulsion of food.
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Affiliation(s)
- Yoshihiko Kito
- Department of Physiology, Nagoya City University Medical School, Japan.
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Zhang RX, Wang XY, Chen D, Huizinga JD. Role of interstitial cells of Cajal in the generation and modulation of motor activity induced by cholinergic neurotransmission in the stomach. Neurogastroenterol Motil 2011; 23:e356-71. [PMID: 21781228 DOI: 10.1111/j.1365-2982.2011.01753.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Interstitial cells of Cajal (ICC) are intimately linked to the enteric nervous system and a better understanding of the interactions between the two systems is going to advance our understanding of gut motor control. The objective of the present study was to investigate the role of ICC in the generation of gastric motor activity induced by cholinergic neurotransmission. METHODS Gastric motor activity was evoked through activation of intrinsic cholinergic neural activity, in in vitro muscle strips by electrical field stimulation, in the in vitro whole stomach by distension and in vivo by fluoroscopy after gavaging the stomach with barium sulfate. The cholinergic activity was assessed as that component of the effect of the stimulus that was sensitive to atropine. These experiments were carried out in wild-type and Ws/Ws rats that have few intramuscular ICC (ICC-IM) in the stomach. KEY RESULTS Under all three experimental conditions, cholinergic activity was prominent in both wild-type and W mutant rats providing evidence against the hypothesis that cholinergic neurotransmission to smooth muscle is primarily mediated by ICC-IM. Strong cholinergic activity in Ws/Ws rats was not due to upregulation of muscarinic receptors in ICC but possibly in smooth muscle of the antrum. CONCLUSIONS & INFERENCES Pacemaker ICC play a prominent role in the expression of motor activity induced by cholinergic activity and our data suggest that cholinergic neurotransmission to ICC affects the pacemaker frequency.
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Affiliation(s)
- R-X Zhang
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
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Lees-Green R, Du P, O'Grady G, Beyder A, Farrugia G, Pullan AJ. Biophysically based modeling of the interstitial cells of cajal: current status and future perspectives. Front Physiol 2011; 2:29. [PMID: 21772822 PMCID: PMC3131535 DOI: 10.3389/fphys.2011.00029] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 06/13/2011] [Indexed: 12/29/2022] Open
Abstract
Gastrointestinal motility research is progressing rapidly, leading to significant advances in the last 15 years in understanding the cellular mechanisms underlying motility, following the discovery of the central role played by the interstitial cells of Cajal (ICC). As experimental knowledge of ICC physiology has expanded, biophysically based modeling has become a valuable tool for integrating experimental data, for testing hypotheses on ICC pacemaker mechanisms, and for applications in in silico studies including in multiscale models. This review is focused on the cellular electrophysiology of ICC. Recent evidence from both experimental and modeling domains have called aspects of the existing pacemaker theories into question. Therefore, current experimental knowledge of ICC pacemaker mechanisms is examined in depth, and current theories of ICC pacemaking are evaluated and further developed. Existing biophysically based ICC models and their physiological foundations are then critiqued in light of the recent advances in experimental knowledge, and opportunities to improve these models are identified. The review concludes by examining several potential clinical applications of biophysically based ICC modeling from the subcellular through to the organ level, including ion channelopathies and ICC network degradation.
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Affiliation(s)
- Rachel Lees-Green
- Auckland Bioengineering Institute, The University of Auckland Auckland, New Zealand
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Sinn DH, Min BH, Ko EJ, Lee JY, Kim JJ, Rhee JC, Kim S, Ward SM, Rhee PL. Regional differences of the effects of acetylcholine in the human gastric circular muscle. Am J Physiol Gastrointest Liver Physiol 2010; 299:G1198-203. [PMID: 20798355 DOI: 10.1152/ajpgi.00523.2009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The motor functions of the stomach have traditionally been regarded to have regional differences. However, to date there have been only a few data investigating whether such regional differences in motor function exist in the human stomach. The aims of the present study were to examine the spontaneous activity and responses to acetylcholine in the anatomically defined regions of human stomach. Human gastric circular muscle tissues from fundus, corpus, and antrum were obtained from 25 patients (14 men, 11 women with a mean age of 55.2 yr; 36-74 yr) undergoing gastrectomy for gastric cancers. Isometric force measurements were performed by using muscle strips from the different regions of the human stomach under basal conditions and in response to the exogenous application of acetylcholine. Spontaneous phasic contractions were observed in all human gastric smooth muscles. However, the responses to acetylcholine displayed regional differences. In the gastric antrum, there was a dose-dependent increase in the peak contraction, contractile frequency, and amplitude of contraction after acetylcholine exposure (up to 1 μM). However, there was no significant change in the basal tone. In the corpus and fundus, acetylcholine induced a dose-dependent increase in the peak contraction and basal tone. However, there was no significant change in the contractile frequency or amplitude of contraction. In conclusion, the response of human gastric circular muscle to acetylcholine displayed regional differences between the antrum and the corpus and fundus. This finding suggested the presence of distinct functional regions in human stomach.
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Affiliation(s)
- Dong Hyun Sinn
- Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Radenkovic G, Savic V, Mitic D, Grahovac S, Bjelakovic M, Krstic M. Development of c-kit immunopositive interstitial cells of Cajal in the human stomach. J Cell Mol Med 2010; 14:1125-34. [PMID: 19298525 PMCID: PMC3822749 DOI: 10.1111/j.1582-4934.2009.00725.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Interstitial cells of Cajal (ICC) include several types of specialized cells within the musculature of the gastrointestinal tract (GIT). Some types of ICC act as pacemakers in the GIT musculature, whereas others are implicated in the modulation of enteric neurotransmission. Kit immunohistochemistry reliably identifies the location of these cells and provides information on changes in ICC distribution and density. Human stomach specimens were obtained from 7 embryos and 28 foetuses without gastrointestinal disorders. The specimens were 7-27 weeks of gestational age, and both sexes are represented in the sample. The specimens were exposed to anti-c-kit antibodies to investigate ICC differentiation. Enteric plexuses were immunohistochemically examined by using anti-neuron specific enolase and the differentiation of smooth muscle cells (SMC) was studied with anti-alpha smooth muscle actin and anti-desmin antibodies. By week 7, c-kit-immunopositive precursors formed a layer in the outer stomach wall around myenteric plexus elements. Between 9 and 11 weeks some of these precursors differentiated into ICC. ICC at the myenteric plexus level differentiated first, followed by those within the muscle layer: between SMC, at the circular and longitudinal layers, and within connective tissue septa enveloping muscle bundles. In the fourth month, all subtypes of c-kit-immunoreactivity ICC which are necessary for the generation of slow waves and their transfer to SMC have been developed. These results may help elucidate the origin of ICC and the aetiology and pathogenesis of stomach motility disorders in neonates and young children that are associated with absence or decreased number of these cells.
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Affiliation(s)
- Goran Radenkovic
- Department of Histology and Embryology, Faculty of Medicine, University of Nis, Nis, Serbia.
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Sanders KM, Hwang SJ, Ward SM. Neuroeffector apparatus in gastrointestinal smooth muscle organs. J Physiol 2010; 588:4621-39. [PMID: 20921202 DOI: 10.1113/jphysiol.2010.196030] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Control of gastrointestinal (GI) movements by enteric motoneurons is critical for orderly processing of food, absorption of nutrients and elimination of wastes. Work over the past several years has suggested that motor neurotransmission is more complicated than simple release of transmitter from nerve terminals and binding of receptors on smooth muscle cells. In fact the 'neuro-effector' junction in the tunica muscularis might consist of synaptic-like connectivity with specialized cells, and contributions from multiple cell types in integrated post-junctional responses. Interstitial cells of Cajal (ICC) were proposed as potential mediators in motor neurotransmission based on reduced post-junctional responses observed in W mutants that have reduced populations of ICC. More recent studies on W mutants have contradicted the original findings, and suggested that ICC may not be significant players in motor neurotransmission. This review examines the evidence for and against the role of ICC in motor neurotransmission and outlines areas for additional investigation that would help further resolve this controversy.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA.
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Abstract
Interstitial cells of Cajal (ICC) are important players in the symphony of gut motility. They have a very significant physiological role orchestrating the normal peristaltic activity of the digestive system. They are the pacemaker cells in gastrointestinal (GI) muscles. Absence, reduction in number or altered integrity of the ICC network may have a dramatic effect on GI system motility. More understanding of ICC physiology will foster advances in physiology of gut motility which will help in a future breakthrough in the pharmacological interventions to restore normal motor function of GI tract. This mini review describes what is known about the physiologic function and role of ICCs in GI system motility and in a variety of GI system motility disorders.
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