Basic Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 14, 2017; 23(34): 6220-6230
Published online Sep 14, 2017. doi: 10.3748/wjg.v23.i34.6220
Moxibustion eases chronic inflammatory visceral pain through regulating MEK, ERK and CREB in rats
Zhi-Yuan Li, Yan Huang, Yan-Ting Yang, Dan Zhang, Yan Zhao, Jue Hong, Jie Liu, Li-Jie Wu, Cui-Hong Zhang, Huan-Gan Wu, Ji Zhang, Xiao-Peng Ma
Zhi-Yuan Li, Yan-Ting Yang, Li-Jie Wu, Ji Zhang, Xiao-Peng Ma, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
Yan Huang, Huangpu Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai 200010, China
Dan Zhang, Jue Hong, Jie Liu, Cui-Hong Zhang, Huan-Gan Wu, Xiao-Peng Ma, Shanghai Research Institute of Acupuncture and Meridian, Shanghai 200030, China
Yan Zhao, Yunnan University of Traditional Chinese Medicine, Kunming 650500, Yunnan Province, China
Author contributions: Li ZY, Huang Y, Yang YT and Zhang D contributed equally to this work; Huang Y, Zhang D and Ma XP conceived the study; Li ZY, Huang Y, Yang YT, Zhao Y, Wu LJ and Zhang J established the animal model and participated in the treatment; Yang YT, Hong J, Liu J and Zhang CH collected the data; Li ZY and Huang Y analyzed the data and wrote the manuscript; Li ZY, Huang Y, Yang YT and Ma XP approved the final version of the manuscript; Zhang D, Wu HG and Ma XP coordinated the research.
Supported by National Natural Science Foundation of China, No. 81273843 and No. 81674073; National Key Basic Research Program of China (973 Program), No. 2015CB554501; Project of Shanghai Municipal Commission of Health and Family Planning, No. 20144Y0153 and No. 2017BR047.
Institutional review board statement: The study was reviewed and approved by the Shanghai University of Traditional Chinese Medicine Institutional Review Board.
Institutional animal care and use committee statement: All procedures involving animals were reviewed and approved by the Institutional Animal Care and Use Committee of Shanghai University of Traditional Chinese Medicine.
Conflict-of-interest statement: The authors declare that there is no conflict of interest regarding the publication of this paper.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Xiao-Peng Ma, PhD, Research Fellow, Shanghai Research Institute of Acupuncture and Meridian, No. 650 South Wanping Road, Xuhui District, Shanghai 200030, China. pengpengma@163.com
Telephone: +86-21-64382181
Received: February 22, 2017
Peer-review started: February 28, 2017
First decision: June 22, 2017
Revised: July 7, 2017
Accepted: August 8, 2017
Article in press: August 8, 2017
Published online: September 14, 2017
Abstract
AIM

To investigate the effects of herb-partitioned moxibustion (HPM) on phosphorylation of mitogen-activated extracellular signal-regulated kinase (MEK)1, extracellular signal-regulated kinase (ERK)1/2 and cAMP response element binding protein (CREB) in spinal cord of rats with chronic inflammatory visceral pain (CIVP), and to explore the central mechanism of HPM in treating CIVP.

METHODS

Male Sprague-Dawley rats were randomized into normal, model, HPM, sham-HPM, MEK-inhibitor and dimethyl sulfoxide (DMSO) groups. The CIVP model was established using an enema mixture of trinitrobenzene sulfonic acid and ethanol. HPM was applied at bilateral Tianshu (ST25) and Qihai (CV6) acupoints in the HPM group, while in the sham-HPM group, moxa cones and herb cakes were only placed on the same points but not ignited. The MEK-inhibitor and DMSO groups received L5-L6 intrathecal injection of U0126 and 30% DMSO, respectively. Abdominal withdrawal reflex (AWR), mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were applied for the assessment of pain behavior. The colonic tissue was observed under an optical microscope after hematoxylin-eosin staining. Expression of phosphor (p)MEK1, pERK1/2 and pCREB in rat spinal cord was detected using Western blotting. The levels of MEK, ERK and CREB mRNA in rat spinal cord were detected using real-time polymerase chain reaction.

RESULTS

Compared with the normal group, the AWR scores were increased significantly (P < 0.01) and the MWT and TWL scores were decreased significantly (P < 0.05) in the model, sham-HPM and DMSO groups. Compared with the model group, the AWR scores were decreased significantly (P < 0.01) and the MWT and TWL scores were increased significantly in the HPM and MEK-inhibitor groups (P < 0.05). Compared with the sham-HPM and DMSO groups, the AWR scores were decreased significantly (P < 0.01) and the MWT and TWL scores were increased significantly (P < 0.05) in the HPM and MEK-inhibitor groups. Compared with the normal group, the expression of pMEK1, pERK1/2 and pCREB proteins and the levels of MEK, ERK and CREB mRNA in rat spinal cord were increased significantly in the model, sham-HPM and DMSO groups (P < 0.01 or < 0.05). Compared with the model group, the expression of pMEK1, pERK1/2 and pCREB proteins and the levels of MEK, ERK and CREB mRNA in rat spinal cord were reduced significantly in the HPM and MEK-inhibitor groups (P < 0.01 or < 0.05). Compared with the sham-HPM and DMSO groups, expression of pMEK1, pERK1/2 and pCREB proteins and the levels of MEK, ERK and CREB mRNA in rat spinal cord were reduced significantly in the HPM and MEK-inhibitor groups (P < 0.01 or < 0.05).

CONCLUSION

HPM down-regulates protein phosphorylation of MEK1, ERK1/2 and CREB, and mRNA expression of MEK, ERK and CREB, inhibiting activation of the MEK/ERK/CREB signaling pathway in the spinal cord of CIVP rats, which is possibly a critical central mechanism of the analgesic effect of HPM.

Keywords: Herb-partitioned moxibustion, Chronic inflammatory visceral pain, Pain behavior, Analgesia, MEK, Extracellular signal-regulated kinase, cAMP response element binding protein, Signaling pathway

Core tip: Chronic inflammatory visceral pain (CIVP) (abdominal pain) is one of the major symptoms of inflammatory bowel disease. Herb-partitioned moxibustion (HPM) at bilateral Tianshu (ST25) and Qihai (CV6) acupoints was effective in enhancing the pain threshold and easing pain in CIVP rats. Levels of phosphorylated protein and mRNA expression of mitogen-activated extracellular signal-regulated kinase 1, extracellular signal-regulated kinase and cAMP response element binding protein were abnormally increased in the spinal cord of CIVP rats. HPM effectively down-regulated the abnormally increased expression, which is possibly one of the analgesic mechanisms of HPM.