Effects of Androgen and Estrogen on DNA Synthesis in Immature Rat Prostate

We investigated the effects of testosterone propionate (T) and/or estradiol (E₂) on the activity of thymidine kinase (TK) and its isozymes and the incorporation of ³H-thymidine in the prostate of immature rats. The maximum activity of prostatic TK increased approximately 50 times the basal level 48 hr after T administration. Puromycin and actinomycin D inhibited nearly 100% of the increase induced by T administration. The prostatic TK isozymes were separated into 3 types by DEAE-cellulose column chromatography, and the activity of the isozyme eluted with buffer alone was markedly increased in T-treated rats, and this isozyme was suggested to be involved in rapid DNA replication because its activity was not affected by deoxycytidine triphosphate (dCTP). The addition of E2 quickened the induction of maximum TK activity due to T administration. Autoradiographic examination indicated that T alone induced marked DNA synthesis in prostatic epithelium, and E2 plus T enhanced DNA synthesis synergistically.