Kushnir A. The effect of melatonin on indices of carbohydrate metabolism under the conditions of alloxan diabetes rats

The dissertation deals with a study of the effect of melatonin on the indices of carbohydrate metabolism in the liver and blood of rats in case of experimental alloxan diabetes. It has been established that in case of a 7-day introduction of melatonin in doses of 5 and 10 mg/kg of the body weight the occurs an augmentation of the intensity of the processes of glycogenesis, the oxidative stage of the pentose-phosphate pathway of the oxidation of glucose-6-phosphate and aerobic glycolysis , with a simultaneous decrease of anaerobic transformation of pyruvate into lactate - in the liver, the latter being reflected in the hypoglycemic effect - in the animals blood that is determined, to a considerable extent, by the functional condition of the pineal gland, modeled lighting regime based on the ratio of the periods of light and darkness. It has been ascertained that an alloxan monohydrate administration to rats results in a significant elevation of the level of basal glycemia in the blood, and an increase of the activities of lactate dehydrogenase and glucose-6-phosphatase in the liver, however a decrease of the glycogen content and the activity glucose-6-phosphate dehydrogenase was in a direct dependence on the presence of hyperglycemia. The established changes of the indices of the carbohydrate metabolism in animals with alloxan diabetes turned out to be more marked under the conditions of permanent lighting than with equinox or permanent darkness. With a 7-day introduction of a higher dose of melatonin an improvement of the state of carbohydrate metabolism was marked and that was accompanied with a normalization of the indices under study, apart from the activities of glucose-6-phosphatase in the liver which is normalized in case of a 42-day administration that was also characterized by a normalization of the level of glycosylated hemoglobin in the rats blood.