Stimulation of Prolactin Secretion by Testosterone in Juvenile Male Rhesus Monkeys1

Abstract

Fifteen juvenile male rhesus monkeys were used to study the effect of testosterone propionate (TP) on serum and pituitary prolactin (PRL). Fice animals were given corn oil alone, 5 received 8 mg/day of TP and 5 received 80 mg/day of the steroid for 28 consecutive days. The concentration of serum PRL was essentially unchanged in the control animals (7.51 .+-. 0.62 ng/ml) throughout the entire experimental period. In those animals given the lower dose (8 mg) of TP, serum PRL increased from 12.36 .+-. 1.10 ng/ml to 21.49 .+-. 1.99 ng/ml in the 1st wk and remained elevated for the duration of the experiment. A similar rise in serum PRL was noted after 1 wk of steroid treatment (12.70 .+-. 0.53 vs. 21.75 .+-. 1.77 ng/ml) in those animals given 80 mg/day of TP. Pituitary PRL levels were also significantly higher in the TP-treated monkeys, with approximately 2.5-3.3 times more PRL being present in the pituitary glands of these animals than in the controls. Light microscopic examination of a portion of the pituitary gland from each animal revealed a marked increase in the number of PRL cells in all monkeys treated with TP. Testosterone or a metabolite of TP can effectively stimulate PRL secretion in the male rhesus monkey.