Influence of estrogens on the androgen metabolism in different subunits of human hair follicles.

The study investigated the influence of estrogens on androgen metabolism in human hair follicles, particularly focusing on their ability to modulate enzymes involved in dihydrotestosterone (DHT) synthesis. Scalp biopsies from volunteers were used to analyze the effects of 17alpha-estradiol, 17beta-estradiol, progesterone, and finasteride on DHT formation. Finasteride was a potent inhibitor, reducing DHT synthesis by 86% at 1 nM concentration, while progesterone inhibited it by 75%. Estrogens were less effective, with 100 nM 17alpha-estradiol and 17beta-estradiol reducing DHT synthesis by 20% and 60%, respectively. The study suggested that estrogens might inhibit DHT synthesis either by directly inhibiting 5alpha-reductase or by increasing the conversion of testosterone to weaker androgens, thus reducing the substrate available for DHT production.