Melatonin is a somnogenic neurotransmiter, a hormone, an antoxidant that blocks the proliferaton and synthesis and secreton of gonadotropins. It is known that melatonin is a universal endogenous adaptogen, has antoxidant, immunomodulatory propertes, and reducing its products in case of violatons of the light regime is accompanied by signs of accelerated aging and an increased risk of tumors. In adults, about 30 μg melatonin is synthesized per day, its concentraton in blood serum at night is 30 tmes higher than in the daytme, with peak actvity at 2:00 pm, its producton is suppressed by the recepton of light informaton by the mesh of the eye. Melatonin is synthesized in the epiphysis only when the light doesn`t influence on the eyes. The melatonin APUD-system acts as apocryphal and paracrine. The presence of melatonin is also determined in all sectons of the gastrointestnal tract (GIT) of animals and humans, from the esophagus to the rectum, with a maximum in the mucous layer and less in the submucosal and muscular layers. The presence of melatonin in the organs of the gastrointestnal tract was demonstrated in studies in pineallectomized animals. This indicates the synthesis of melatonin by the organs of the gastrointestnal tract. Based on these studies it is possible to assume that melatonin plays an important role in the physiology of the gastrointestnal tract and disturbance of its secreton may be the cause of various pathologies of the gastrointestnal tract. The problem of the effect of melatonin on the gastrointestnal tract is relevant, since the relatonship between the degree of disturbance in the rhythm of melatonin producton and the clinical course of some diseases (ulceraton of the stomach and duodenum) has been detected, and there isn`t studies on the effect of excess and lack of melatonin on the functoning of the gastrointestnal tract. In additon, there is a large group of people working in the night shif, exists in the conditons of round the clock lightng (large cites, polar day, sleep in light), which blocks the synthesis and secreton of melatonin by the epiphysis. There is also the possibility of uncontrolled use of melatonin as sleeping pills. All this indicates to the nesessity for a more detailed study of melatonin on the physiological processes in the body. Therefore, the purpose of the work was to study the effect of excess and lack of melatonin on the rate of glucose`s absorpton in the small intestne of rats. The studies were performed on 24 sexually mature white male rats of the Wistar line weighing 220-260 g (3 groups of 8 animals). The frst group was an intact, held in light mode: 12 hours of darkness – 12 hours of light for a period of 30 days. In the second group for modeling hypomelatoninemia animals were kept in the regime of constant illuminaton (1000-1500 lux) for 30 days. In the third group, hypermelatoninemia was modeled by the administraton of melatonin in the diet with a dose of 1 mg/kg body weight/day and 24-hour darkness for 30 days. Determined the amount of glucose that was absorbed in the isolated loop of the small intestne of rats for 10 min. The study found that an excess of melatonin stmulates the absorpton of glucose in the small intestne by 10%, and its lack of – on the contrary, inhibits by 18%. With hypermelatoninemia, the rate of absorpton was 26% higher than with gipomelatoninemia, which indicates the contrainsular propertes of melatonin.
melatonin, antoxidant, small intestne, glucose, gipomelatoninemia, gipermelatoninemia
«Bulletin of problems biology and medicine» Issue 1 Part 2 (143), 2018 year, 82-85 pages, index UDK 612.4:612.33:612.018.2
