EFFECT OF CYPROTERONE ACETATE ON ANDROGEN-DEPENDENT SYNTHESIS OF α2u GLOBULIN IN RATS

Abstract

SUMMARY Cyproterone acetate (CA, 2·5 mg/100 g body wt) inhibited androgenic induction of α2u globulin in spayed rats. In mature male rats, which normally produce α2u globulin, ten daily injections of CA did not inhibit synthesis of this protein. Long-term treatment of mature male rats (two injections every week for 12 weeks) showed only slight inhibition of α2u synthesis after 10 weeks of CA treatment. CA also failed to compete with 5α-dihydrotestosterone for the cytosol androgen-binding protein of male rat liver. The inhibitory effect of CA on the primary induction of α2u globulin in the spayed rat and its lack of effect on continued synthesis of this protein in maximally induced mature male rats are consistent with the hypothesis of a two-step mechanism for androgenic regulation of α2u synthesis, an initial CA-sensitive step followed later by a CA-insensitive step.