Effects of hyperprolactinemia on the accessory sexual organs of the male rat.

The growth-promoting effect of prolactin on the ventral prostate lobe, the anterior prostate lobe (or coagulating gland), and seminal vesicles has been studied before, during and after puberty in rats up to 5 months of age. Pituitaries from female rats were grafted under the renal capsule of 23-26-day-old male rats. Within 1/2 month substantial (five- to ten-fold) hyperprolactinemia occurred followed by a gradual decline; levels were still high 4 months after grafting. A statistically significant increase in the weight of the seminal vesicles and the ventral and anterior prostate lobes was observed 1 month after implantation. This effect was only maintained for the seminal vesicles during the next 3 months. Hyperprolactinemia did not influence testosterone metabolism. In the ventral prostate lobe, 1 month after grafting, the nuclear androgen receptor content increased, whereas the cytosolic androgen receptor content decreased. These results suggest that the growth-promoting effect of prolactin, on the ventral prostate lobe of the rat, is brought about by an increased translocation of the androgen receptor.