Gastrointestinal melatonin: localization, function, and clinical relevance.

Area of Science:

• Gastroenterology
• Endocrinology
• Chronobiology

Background:

• The gastrointestinal (GI) tract is a significant extrapineal source of melatonin, with concentrations 10-100 times higher than in blood.
• GI melatonin influences epithelial regeneration, gut immunity, and muscle tone, acting as an endocrine, paracrine, or autocrine hormone.
• Unlike pineal melatonin, GI melatonin release appears linked to feeding patterns, not photoperiod.

Purpose of the Study:

• To review the significance of gastrointestinal melatonin.
• To explore its physiological roles and potential therapeutic applications in digestive diseases.

Main Methods:

• Literature review of studies on melatonin in the vertebrate gastrointestinal tract.
• Analysis of melatonin's concentration, regulation, and functions within the GI system.
• Examination of phylogenetic presence and effects of melatonin on GI tissues.

Main Results:

• Melatonin is abundant in the GI tract across vertebrates, including embryonic stages.
• GI melatonin concentrations increase with food intake and prolonged food deprivation.
• Melatonin demonstrates protective effects against gastric ulcers via antioxidant and regenerative mechanisms.

Conclusions:

• Gastrointestinal melatonin is a key regulator of gut function and health.
• Its unique properties suggest potential for treating conditions like colorectal cancer, ulcerative colitis, and irritable bowel syndrome.
• Melatonin's role in the GI tract warrants further investigation for therapeutic development.