The effect of prolactin deficiency during sexual maturation in the male rat.

Abstract

The effect of prolactin deficiency on sexual development and serum hormone concentrations in male rats was investigated. Prolactin deficiency was induced by a series of sc injections of either normal rabbit serum (NRS) or rabbit antirat prolactin (ARP) beginning on Day 3 of life. The animals were sacrificied either on Day 49 or 61 and body weights and wet weights of the pituitary testis ventral prostate seminal vesicle and adrenal gland were determined. Serum concentrations of luteinizing hormone (LH) follicle stimulating hormone (FSH) prolactin (PRL) and testosterone (T) were measured by radioimmunoassay. Prolactin could not be detected in the serum of ARP-treated animals. Serum LH concentrations on Day 49 were significantly (p less than .001) higher in ARP-treated rats than in NRS controls though serum concentrations of FSH and T were similar in both groups. However on Day 61 serum levels of LH FSH and T in ARP-treated animals were comparable to those in NRS controls. On Day 61 but not on Day 49 prostate and seminal vesicle weights were significantly (p less than .05) lower in ARP-treated animals compared with NRS controls. ARP did not affect body weights and weights of the pituitary testis and adrenal gland. The results suggest that prolactin inhibits LH secretion during sexual maturation in the rat and stimulates the development of secondary sex tissues.