[A comparative study of the osmoregulating system in the hamsters Phodopus roborovskii and Phodopus sungorus]

The hamster Phodopus roborovskii is adapted to live in desert, Phodopus sungorus in less arid regions. Hamsters of both species have rather close values of blood serum osmolality and ion concentration, after dehydration the value of urine osmolality is found to be equally high. The microdissection of the kidney did not reveal any difference in the structure and arrangement of nephrons in cortex and medulla. According to the results of immunocytochemical analysis of the hypothalamo-hypophyseal neurosecretory system of hamster Phodopus roborovskii, compared to Phodopus sungorus, has a smaller quantity of vasopressin-positive neurons, which is likely to be a result of a release of larger quantities of vasopressin in long-term dehydration. It is suggested that of importance in the animal adaptation to life in arid condition may be not only morphofunctional reorganization of kidney but also of the hypothalamo-hypophyseal system which is involved in permanent secretion of vasopressin.