Basic Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Nov 14, 2016; 22(42): 9333-9345
Published online Nov 14, 2016. doi: 10.3748/wjg.v22.i42.9333
Carbon monoxide contributes to the constipating effects of granisetron in rat colon
Carmela Nacci, Margherita Fanelli, Maria Assunta Potenza, Valentina Leo, Monica Montagnani, Maria Antonietta De Salvia
Carmela Nacci, Maria Assunta Potenza, Valentina Leo, Monica Montagnani, Maria Antonietta De Salvia, Department of Biomedical Sciences and Human Oncology - Pharmacology Section, Medical School, University of Bari "Aldo Moro", Piazza G. Cesare, 70124 Bari, Italy.
Margherita Fanelli, Department of Interdisciplinary Medicine, Medical School, University of Bari "Aldo Moro", Piazza G. Cesare, 70124 Bari, Italy.
Author contributions: Nacci C performed the majority of the experiments; Fanelli M analyzed the data; Potenza MA and Leo V participated in animal treatment; De Salvia MA designed and coordinated the research; Montagnani M and De Salvia MA wrote the paper.
Supported by Università degli Studi di Bari, protocol No. 10110 tit-VIII/2.
Institutional review board statement: The study was reviewed and approved by Università degli Studi di Bari with protocol number 10110 tit-VIII/2.
Institutional animal care and use committee statement: All procedures in animals were reviewed and approved by the Italian Government, Ministry of Health, with protocol number 15/12.
Conflict-of-interest statement: To the best of our knowledge, no conflict of interest exists.
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: Maria Antonietta De Salvia, PhD, Assistant Professor, Department of Biomedical Sciences and Human Oncology - Pharmacology section, Medical School, University of Bari "Aldo Moro", Piazza G. Cesare, 70124 Bari, Italy. mariaantonietta.desalvia@uniba.it
Telephone: +39-80-5478425 Fax: +39-80-5478449
Received: June 24, 2016
Peer-review started: June 29, 2016
First decision: August 22, 2016
Revised: September 16, 2016
Accepted: October 19, 2016
Article in press: October 19, 2016
Published online: November 14, 2016
Processing time: 140 Days and 19.6 Hours
Abstract
AIM

To investigate the mechanisms underlying the potential contribution of the heme oxygenase/carbon monoxide (HO/CO) pathway in the constipating effects of granisetron.

METHODS

For in vivo studies, gastrointestinal motility was evaluated in male rats acutely treated with granisetron [25, 50, 75 μg/kg/subcutaneous (sc)], zinc protoporphyrin IX [ZnPPIX, 50 μg/kg/intraperitoneal (ip)] and hemin (50 μmol/L/kg/ip), alone or in combination. For in vitro studies, the contractile neurogenic response to electrical field stimulation (EFS, 3, 5, 10 Hz, 14 V, 1 ms, pulse trains lasting 10 s), as well as the contractile myogenic response to acetylcholine (ACh, 0.1-100 μmol/L) were evaluated on colon specimens incubated with granisetron (3 μmol/L, 15 min), ZnPPIX (10 μmol/L, 60 min) or CO-releasing molecule-3 (CORM-3, 100, 200, 400 μmol/L) alone or in combination. These experiments were performed under co-treatment with or without atropine (3 μmol/L, a muscarinic receptor antagonist) or NG-nitro-L-Arginine (L-NNA, 100 μmol/L, a nitric oxide synthase inhibitor).

RESULTS

Administration of granisetron (50, 75 μg/kg) in vivo significantly increased the time to first defecation (P = 0.045 vs vehicle-treated rats), clearly suggesting a constipating effect of this drug. Although administration of ZnPPIX or hemin alone had no effect on this gastrointestinal motility parameter, ZnPPIX co-administered with granisetron abolished the granisetron-induced constipation. On the other hand, co-administration of hemin and granisetron did not modify the increased constipation observed under granisetron alone. When administered in vitro, granisetron alone (3 μmol/L) did not significantly modify the colon’s contractile response to either EFS or ACh. Incubation with ZnPPIX alone (10 μmol/L) significantly reduced the colon’s contractile response to EFS (P = 0.016) but had no effect on contractile response to ACh. Co-administration of ZnPPIX and atropine (3 μmol/L) abolished the ZnPPIX-mediated decrease in contractile response to EFS. Conversely, incubation with CORM-3 (400 μmol/L) alone increased both the contractile response to EFS at 10 Hz (10 Hz: 71.02 ± 19.16 vs 116.25 ± 53.70, P = 0.01) and the contractile response to ACh (100 μmol/L) (P = 0.012). Co-administration of atropine abolished the CORM-3-mediated effects on the EFS-mediated response. When granisetron was co-incubated in vitro with ZnPPIX, the ZnPPIX-mediated decrease in colon contractile response to EFS was lost. On the other hand, co-incubation of granisetron and CORM-3 (400 μmol/L) further increased the colon’s contractile response to EFS (at 5 Hz: P = 0.007; at 10 Hz: P = 0.001) and to ACh (ACh 10 μmol/L: P = 0.001; ACh 100 μmol/L: P = 0.001) elicited by CORM-3 alone. L-NNA co-administered with granisetron and CORM-3 abolished the potentiating effect of CORM-3 on granisetron on both the EFS-induced and ACh-induced contractile response.

CONCLUSION

Taken together, findings from in vivo and in vitro studies suggest that the HO/CO pathway is involved in the constipating effects of granisetron.

Keywords: Granisetron; Carbon monoxide; Heme oxygenase; Colon; Contraction; Neurogenic response; Myogenic response

Core tip: We studied whether in vivo and in vitro effects of granisetron might be influenced, at least in part, by the heme oxygenase/carbon monoxide (HO/CO) pathway. Our findings demonstrate for the first time that the HO/CO pathway takes part in the contractile colon activity in rats. Interestingly, the constipating effects of granisetron are positively correlated with levels of carbon monoxide, thus suggesting that treatments able to modulate carbon monoxide levels may potentially reduce the constipation mediated by granisetron.