A possible direct effect of androgens at the pituitary level on gonadotropin release was studied using rat anterior pituitary cells in primary culture. The preincubation of cells with 3 X 10(-9)M testosterone (T) for 40 h increased the concentration of luteinizing hormone-releasing hormone (LHRH) required for half-maximal stimulation (ED50) of LH release from 3 X 10(-10)M to 1 X 10(-9)M. In the same experiment, the LHRH ED50 for FSH release (3 X 10(-10)M) was not affected by preincubation with T, while a slight stimulatory effect of the androgen was observed on balal FSH release and on the maximal FSH response to LHRH. Time-course experiments showed that the inhibitory effect of T on the LH response to LHRH was maximal after about 48 h of incubation and that 54 h after the removal of T, only 50% of the inhibition was reversed. 5 alpha-Dihydrotestosterone (DHT) and T led to the same maximal inhibition (15-20% of control) of the LH response to 10(-10)M LHRH. DHT was, however, about 3 times more potent than T, their ED50 values being 1.6 X 10(-10)M and 5 X 10(-10)M, respectively. In contrast to the effect on LH, the FSH response to 10(-10)M LHRH was only slightly, but not significantly, inhibited by increasing concentrations of DHT or T. The finding that total LH (medium + cell content) remained constant after incubation with T or DHT clearly indicates that the inhibition of the LH response to LHRH is really due to changes in the sensitivity of the releasing mechanisms in the LH-secreting cells. Androgens did, however, lead to increased total FSH. The present data indicate an independent control of LH and FSH secretion by a direct action of androgens at the pituitary level.