Estrogenic inhibition of the hepatic synthesis of alpha2u globulin in the rat

Abstract

The hepatic synthesis of the androgen-dependent urinary protein in the rat, called alpha2u globulin, is strongly inhibited by estrogens. In mature male rats, treatment with estradiol-17beta (0.5 mug/g body weight) completely inhibits alpha2u synthesis within 6-7 days. Following withdrawal of estrogen treatment alpha 2u synthesis is not reinitiated for approximately 20 days. Parabiotic joining of estrogen-suppressed male rats with their normal littermates within this lag period fails to change the preparabiotic pattern of alpha2u synthesis in the respective partners. Besides estradiol-17beta, other estrane derivatives such as estrone, estriol and estradiol-17alpha were also found to inhibit the synthesis of alpha2u globulin. All of the above estrane derivatives which inhibit alpha2u synthesis are also found to inhibit the uptake of 5alpha-dihydrotestosterone by the hepatic cytosol androgen binding protein of the mature male rat. Unlike cycloheximide, a known translational inhibitor, estradiol-17beta does not inhibit alpha 2u synthesis in the perfused rat liver.