Effect of aromatizable androgens and estradiol on prolactin secretion in prepuberal male rats.

Intact and castrated male rats were injected daily for 10 days, beginning at 35 days of age, with either oil or one of the following steroids: testosterone propionate, dihydrotestosterone benzoate, androsterone acetate, androstenedione, androstandiol, or estradiol benzoate. Doses were 200 micrograms/rat/day for all androgens and 0.5 microgram or 2 micrograms/rat/day for estradiol. Significant increments in prolactin levels (fourfold over control values) in intact and castrated males were obtained after testosterone propionate and androstenedione treatment. Dihydrotestosterone, androsterone, and androstandiol did not induce any changes in either intact or castrated rats. Estradiol-treated males showed a four- and sevenfold increment in serum prolactin with the 0.5- and 2-microgram doses, respectively. These results suggest that androgens have a role in the control of prolactin secretion, particularly those that can be aromatized to estrogens by different tissues, including the hypothalamus.