Studies on the mode of oestrogenic inhibition of hepatic synthesis of α₂u globulin and its corresponding messenger ribonucleic acid in rat liver

1. The possible mechanism of the oestrogenic inhibition of the androgen-dependent synthesis of α(2u)-globulin in rat liver was explored by a correlative study of the amounts of α(2u)-globulin, its corresponding mRNA and circulating testosterone in oestrogen-treated male rats. 2. Daily treatments of mature male rats with oestradiol-17β (10 μg/100 g body wt.) decreased and ultimately stopped the hepatic synthesis of α(2u)-globulin as determined by both hepatic and urinary concentrations of the protein. The oestrogen-mediated decrease in the hepatic synthesis of α(2u)-globulin was correlated with a decrease in the mRNA for this protein. 3. Withdrawal of oestrogen resulted in the recovery of α(2u)-globulin synthesis and an increase in mRNA for α(2u)-globulin. 4. At higher doses of oestradiol-17β (50 μg/100 g body wt.), synthesis of α(2u)-globulin was totally suppressed. In addition, this treatment resulted in an extended period of androgen-insensitivity during which treatment with androgens induced synthesis of neither α(2u)-globulin nor its corresponding mRNA. 5. It is concluded that the oestrogenic inhibition of α(2u)-globulin synthesis is mediated by an oestrogen-dependent decrease in the hepatic content of translatable mRNA for α(2u)-globulin.