Gastrointestinal tract and melatonin: Reducing pathophysiology

Due to its receptor-independent actions as a free radical scavenger and its receptor-mediated functions, melatonin has the capability of reducing a number of pathophysiologies that are common throughout the alimentary canal. The large quantities of melatonin in gut tissues from the stomach to the colon, as well as the exceptionally high levels in bile, support the notion that melatonin is functionally relevant in the gastrointestinal tract. The area of greatest research endeavor to date has related to the ability of melatonin to reduce oxidative damage to the lower esophagus during gastroesophageal reflux and its marked action in reducing gastric ulcers due to a variety of processes, e.g., water immersion and restraint stress, aspirin toxicity, prescription drug toxicity (especially those used to treat osteoporosis) and ethanol. In each of these cases, the concurrent administration of melatonin either partially or totally, prevented the damage resulting from these treatments in experimental animals. A recent study has also revealed that melatonin prevents aspirin toxicity in the stomach of humans. Besides preventing ulcer formation, melatonin has also been found to hasten healing of pre-existing lesions. Finally, melatonin has been shown to reduce gallstone formation; the means by which it does so are multiple. It is the hope of the authors that the data summarized herein will serve as a stimulus for clinical studies of a similar nature.