In vitro steroid metabolic studies in human testes. II: Metabolism of cholesterol, pregnenolone, progesterone, androstenedione and testosterone by testes of an estrogen-treated man.

The effect of long-term in vivo estrogen treatment on in vitro steroidogenesis by the testes of a young man was investigated. In vitro incubation of testicular tissue of this man with 3H-pregnenolone, 3H-progesterone, 3H-androstenedione and 3H-testosterone demonstrated suppression of 17-hydroxylase activity, with little or no effect of the treatment on delta5-3beta-hydroxysteroid oxidoreductase, 5alpha-reductase and aromatase. Increased 20alpha-hydroxysteroid oxidoreductase activity was observed. Determination of intratesticular steroid concentrations led to similar conclusions.