Acute stimulation of aromatization in Leydig cells by human chorionic gonadotropin in vitro.

Abstract

Aromatization of testosterone [T] in Leydig cells purified from mature rat testes was assessed. Leydig cells incubated for 4 h with increasing concentrations of [3H]T exhibited maximal aromatization at 0.6 .mu.M T. At saturating concentrations of T, human chorionic gonadotropin (hCG) acutely stimulated aromatization. This stimulation was first observed at 1 h, an 8-fold increase being found during a 4 h incubation. The maximal amount of estradiol produced at saturating concentrations of T and hCG was 1.8 ng per 106 cells. Purified Leydig cells have a high capacity for aromatization and hCG can acutely stimulate aromatization independently of stimulating T synthesis in vitro.