| Abstract: | The marked sex differences in the ratio between the hormonal capacity of estradiol-binding components with Stokes' radii (a) of 7.0 and 2.5 nm observed in sexually mature animals are somewhat reduced but do not disappear completely after gonadectomy. Prolonged administration of estradiol (50  g, 8days) to gonadectomized rats leads to depression of the estradiol-binding activity of all components of liver cytosol of females and males. Injection of testosterone propionate (2 mg, 8 days) into gonadectomized animals leads to selective stimulation of a special estrogen-binding protein with a=2.5 nm, normally characteristic of males alone, in both males and females. It is postulated that sex differences in the system of estradiol-binding proteins of the rat liver cytosol are due to sexual differentiation of the system in the early stages of development, on the one hand, and to the active regulatory influence of androgens and estrogens in the late stages of development, on the other hand.Laboratory of Endocrinology, Biological Faculty, M. V. Lomonosov Moscow State University. (Presented by Academician of the Academy of Medical Sciences of the USSR S. E. Severin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 5, pp. 548–551, May, 1977. |
