Antonova O. The functional state of liver in lack and surplus of melatonin in different conditions.

It is experimentally proved that melatonin with its lack and surplus is able to change the pro-oxidant and antioxidant balance of liver and metabolic function and histological state of liver tissue. The complex research of melatonin lack and surplus on liver state in its normal functioning and in the conditions of oxidant stress was carried on. It was established that melatonin lack and surplus result in considerable changes in pro-oxidant and antioxidant system during long-term effect of these states: the most expressed enforcement of peridoxication in liver is occurred on 55days hypomelatoninemia while peridoxication reduction and antioxidant defense enforcement in liver take place on 55 days hypermelatoninemia. Some changes in metabolic processes are stated in more durable melatonin lack and surplus: while 55 days melatonin lack. The following histological changes in liver tissue in hypo- and hipermelatoninemia were revealed: carioloses, chromosome fragmentation and k-mitoses on long-term hypomelatoninemia, mitoses pathology, k-mitoses, hepatodepressed syndrome on long-term hypermelatoninemia. The proved physiological features of melatonin effect on liver functioning warn against unchecked melatonin usage that is used as medicine or continuous twenty-four-hour lighting that results in melatonin secretion reduction including dreaming. The data gained can become the base for elaboration of physiologically based doses of melatonin usage.