Review
Copyright ©2011 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Sep 14, 2011; 17(34): 3888-3898
Published online Sep 14, 2011. doi: 10.3748/wjg.v17.i34.3888
Distribution, function and physiological role of melatonin in the lower gut
Chun-Qiu Chen, Jakub Fichna, Mohammad Bashashati, Yong-Yu Li, Martin Storr
Chun-Qiu Chen, Department of Gastrointestinal Surgery, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, 200072 Shanghai, China
Chun-Qiu Chen, Jakub Fichna, Mohammad Bashashati, Martin Storr, Division of Gastroenterology, Department of Medicine, University of Calgary, 3330 Hospital Dr NW, T2N 0N1 Calgary, Alberta, Canada
Yong-Yu Li, Department of Pathophysiology, Tongji University School of Medicine, 200092 Shanghai, China
Martin Storr, Division of Gastroenterology, Department of Medicine, University of Munich, Marchioninistr 15, 81377 Munich, Germany
Author contributions: Storr M designed the project; Chen CQ, Fichna J, Bashashati M and Li YY performed literature research; Chen CQ, Fichna J, Bashashati M and Storr M wrote the paper.
Correspondence to: Martin Storr, MD, Division of Gastroenterology, Department of Medicine, University of Munich, Marchioninistr 15, 81377 Munich, Germany. gidoc@gmx.com
Telephone: +49-89-70950 Fax: +49-3212-1027208
Received: January 11, 2011
Revised: March 18, 2011
Accepted: March 25, 2011
Published online: September 14, 2011
Abstract

Melatonin is a hormone with endocrine, paracrine and autocrine actions. It is involved in the regulation of multiple functions, including the control of the gastrointestinal (GI) system under physiological and pathophysiological conditions. Since the gut contains at least 400 times more melatonin than the pineal gland, a review of the functional importance of melatonin in the gut seems useful, especially in the context of recent clinical trials. Melatonin exerts its physiological effects through specific membrane receptors, named melatonin-1 receptor (MT1), MT2 and MT3. These receptors can be found in the gut and their involvement in the regulation of GI motility, inflammation and pain has been reported in numerous basic and clinical studies. Stable levels of melatonin in the lower gut that are unchanged following a pinealectomy suggest local synthesis and, furthermore, implicate physiological importance of endogenous melatonin in the GI tract. Presently, only a small number of human studies report possible beneficial and also possible harmful effects of melatonin in case reports and clinical trials. These human studies include patients with lower GI diseases, especially patients with irritable bowel syndrome, inflammatory bowel disease and colorectal cancer. In this review, we summarize the presently available information on melatonin effects in the lower gut and discuss available in vitro and in vivo data. We furthermore aim to evaluate whether melatonin may be useful in future treatment of symptoms or diseases involving the lower gut.

Keywords: Melatonin; Ileum; Colon; Receptor; Motility; Inflammatory bowel disease; Clinical trial