-8-Bromo-cAMP stimulated the release of LH (approximately 20-fold) and FSH (approximately 2-fold) in control rat anterior pituitary cells in primary culture. 8-Bromo-cAMP-induced LH release was 2-3 times greater in cells preincubated for 48 h in the presence of 10(-8) M 17 beta-estradiol (E2). The LH response to 10(-10) M LHRH was similarly increased by E2 pretreatment whereas progesterone (P), which had no effect on the response to 8-bromo-cAMP, led to a reduction of the stimulatory effect of E2 on the LH response to the neurohormone. Preincubation with 10(-8) M testosterone (T) decreased the LH response to 8-bromo-cAMP by about 40%, whereas the response to LHRH was 80% inhibited. 8-Bromo-cAMP-induced FSH release was slightly increased in cells preincubated with E2 but was greatly augmented in cells treated with E2 + P. Basal FSH release was slightly increased (40%) after preincubation with P or T whereas the response to 8-bromo-cAMP was not significantly affected. The sensitivity of the FSH response to LHRH was increased by E2 whereas P and T led to a stimulation of the maximal FSH response to LHRH with no significant effect on the LHRH ED50 value. The present data indicate that P and E2 exert their effects on LH and FSH release at steps before and after cAMP formation, respectively. T appears to act at both steps on the release of the two gonadotropins.