The inhibition of 3 beta HSD activity in porcine granulosa cells by 4-MA, a potent 5 alpha-reductase inhibitor.

Addition of 17 beta-N,N,-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstane-3-one, a potent 5 alpha-reductase inhibitor, to granulosa cell cultures inhibited the FSH-stimulated progesterone synthesis during both the initial 48 h induction period and the subsequent 6h test period in a dose-dependent fashion. Besides being a more potent inhibitor of FSH-stimulated progesterone synthesis than testosterone, 4-MA also synergized with the androgen to inhibit progesterone synthesis. These results indicate that 4-MA has a direct inhibitory action on 3 beta-HSD.