Control of LH and FSH secretion in the male: Evidence that aromatization of androgens to estradiol is not required for inhibition of gonadotropin secretion

Recent data indicate that the hypothalamus is capable of aromatizing androgens to estrogens; it has been suggested that this aromatization is required for hormonal activity at the hypothalamic level. In this study dihydrotestosterone and testosterone were administered over a broad dose range to castrate male rats. Dihydrotestosterone, an A-ring reduced steroid which is not convertible to estrogen, was demonstrated to be more potent than testosterone in suppressing serum LH levels while equipotent to testosterone in suppressing FSH. We conclude that conversion of androgens to estrogens is not required for inhibition of the hypothalamic-pituitary axis.