VARIABILITY OF THE CONTENT OF SERUM TESTOSTERONE IN BELUGAS OF DELPHINAPTERUS LEUCAS OF DIFFERENT AGES

Recently, the issues of a comprehensive study of the reproductive system of marine mammals, in particular the analysis of hormonal changes in the organism of cetaceans in the process of their growth and development has become urgent. In the present work, the content of serum testosterone in blood samples of male beluga whales Delphinapterus leucas was determined. The studies were carried out on belugas kept in semi-free conditions of an open-air marine enclosure complex in the Barents Sea. Venous blood samples were obtained from animals aged 5 to 10 years, while individuals under 7 years old were considered immature. A total of 5 belugas were examined, 43 samples were obtained. Blood sampling was carried out from the ventral or dorsal vein of the caudal fin using a vacuum blood sampling system in plastic vacuum tubes. The volume of the samples ranged from 3 to 12 ml of native blood. Blood serum for research was obtained by centrifuging the samples at 2000 rpm for 10-15 minutes. About 2.5-3 ml of serum was obtained from 8 ml of native blood. It was frozen, stored and transported to the laboratory at a temperature of -20 ° С. The testosterone content in the samples was determined by the method of heterogeneous enzyme-linked immunosorbent assay (ELISA). A comparative assessment of the concentration of this steroid hormone in young and mature animals showed a positive linear correlation between the level of testosterone secretion and the age of the animal. Studies have shown that the sexual maturity of male beluga whales occurs by the age of 8-10, when serum testosterone levels of 15 nmol / L or higher are reached.