The influence of steroidal and nonsteroidal estrogens on the 5 alpha-reduction of testosterone by the ventral prostate of the rat.

The 5 alpha-reduction of testosterone to dihydrotestosterone (DHT) correlates with the androgen-mediated growth of the prostate under different experimental and clinical conditions. The aim was to study the regulation of the prostatic growth and enzyme activity by steroidal and nonsteroidal estrogens. Estrogens did not activate the androgen-dependent 5 alpha-reductase activity in cultured prostate of the rat. The direct inhibition of the enzyme activity by estrogens at the concentrations achievable in the male is not probable either. However, early estrogenization of the male rats in utero (on Day 17 of pregnancy) with diethylstilbestrol (DES) resulted in a persistent decrease of the enzyme activity and growth of the prostate indicating a critical estrogen-sensitive period in the regulation of the ultimate enzyme activity. The similar DES-like inhibitory effect on the growth of the prostate was achieved by keeping animals from fertilization throughout the pregnancy until weaning on diet containing soy, rich in environmental estrogens. Zearalenone (Zeranol) and coumestrol, two nonsteroidal estrogens found in human and animal food mimicked estradiol action in culture, but they were not estrogenic or antiestrogenic when administered to normal adults.