[Mechanisms of sex differentiation of the level of corticosteroid-binding globulin in rats].

The role of sex steroids was studied at different stages of ontogenesis in the regulation and programming of the level of corticosteroid binding globulin (CBG) in the blood serum of female and male rats. The blood concentration of CBG was shown to be a sex determined feature: its level in female rats was a 2.5-fold higher than that in male rats; sex differences of this function of the liver were preserved in a primary culture of hepatocytes. Androgens (A) in adult animals were shown to decrease the level of CBG, and estrogens (E) did not influence the blood level of this protein. Castration of adult males leading to an increase of the level of CBG by 1.5-fold did not eliminate sex differences. However gonadectomy of males on the first day of the life or in prepubertal period (at the age of 3-4 weeks) resulted in complete "feminization" of the CBG content in these animals at the age of 10-12 weeks. Ovariectomy in female rats in the prepubertal period did not influence the level of CBG in adult female rats. The administration of A to females or castrated males did not prevent the development of a high level of CBG at older age. Irreversible suppression of the level of CBG in adult animals could be artificially induced by the administration of A to gonadectomized female and male rats in the prepubertal period.(ABSTRACT TRUNCATED AT 250 WORDS)