| Abstract: | A study was made of the endocrine mechanisms of the formation and maintenance of a sex-differentiated level of estrogen receptors (ER) in rat liver cytosol. The administration of testosterone-propionate (TP) at a dose of 3 mg for 3 days was shown to cause a significant decrease in the concentration of ER in the liver of gonadectomized animals to the level in intact male rats. In a week after the discontinuation of TP, a complete restoration of the basal level of receptors was observed. Neonatal and prepubertal administration of TP to gonadectomized male rats at early stages of ontogenesis made no effect on the level of ER in the liver cytosol of these animals at the age of 12-14 weeks. The removal of the adrenal and thyroid glands produced no changes in the level of ER in the liver of rats of both sexes. Hypophysectomy in rats resulted even on the 1st day in a decrease in ER concentration in the liver of male and female animals to the same basal level which later on remained unchanged. Ectopic transplantation of a homologous hypophysis and human STH administration led to a significant rise of the level of ER in hypophysectomized animals. TP inhibited a stimulating effect of STH in rats with the removed hypophysis. |
