The objective of the present studies was to evaluate and compare the effects of 5 alpha-dihydrotestosterone (DHT) to those of 2-hydroxyestradiol (2-OH-E2) and 2-methoxyestradiol (2-MeO-E2) on progesterone production in cultured porcine granulosa cells. Granulosa cells were exposed to various treatments of DHT, 2-OH-E2 and 2-MeO-E2 in the absence or presence of follicle stimulating hormone (FSH) for 4 days and concentrations of progesterone in medium and cell numbers were determined. In the absence of FSH, maximally effective concentrations of DHT (1 micrograms/ml) and 2-OH-E2 (4 micrograms/ml) stimulated progesterone production (ng/10(5) cells/48 h) to 2.2 +/- 0.2- and 10.8 +/- 2.2-fold of controls (n = 4 experiments), respectively. In the presence of 200 ng/ml FSH, progesterone production stimulated by 1 micrograms/ml DHT and 4 micrograms/ml 2-OH-E2 was 5.4 +/- 1.1- and 15.5 +/- 6.0-fold of controls (n = 4 experiments), respectively. Thus, FSH appeared to enhance the response of both DHT and 2-OH-E2. The dose-response of DHT was biphasic in the presence and absence of FSH, such that progesterone production in the presence of 8 micrograms/ml DHT was similar to basal progesterone production. Concurrent treatment with saturating concentrations of 2-OH-E2 and DHT resulted in fully additive increases in progesterone production. Testosterone mimicked the effect of DHT. In comparison, concurrent treatment of saturating concentrations of 2-MeO-E2 and DHT or 2-MeO-E2 and 2-OH-E2 resulted in progesterone production that was only partially additive.(ABSTRACT TRUNCATED AT 250 WORDS)