Effects of hyperprolactinemia on copulatory behavior and testicular human chorionic gonadotropin binding in adrenalectomized rats

Hyperprolactinemia (hyperPRL) induced by grafting four ectopic pituitary glands under the kidney capsules results in suppressed copulatory behavior, increased testicular hCG binding, and increased adrenal weights and plasma corticosterone levels. To determine whether stimulation of adrenal activity may be involved in the effects of hyperPRL on copulatory behavior and testicular hCG binding, we have examined the effects of four ectopic pituitary grafts in intact and adrenalectomized, corticosterone-replaced (1 mg, three times per week) male rats. Pituitary grafting resulted in significant elevations in plasma PRL levels and had a significant suppressive effect on male copulatory behavior in both intact and adrenalectomized animals. Plasma levels of FSH were suppressed in the adrenalectomized, pituitary-grafted animals but were significantly reduced only in the samples taken just before the rats were killed. In contrast, plasma LH was significantly lowered in both groups of grafted animals 6 weeks after the induction of hyperPRL, but only in the intact hyperprolactinemic animals at the termination of the experiments. Plasma testosterone levels were increased in both sham-operated and pituitary-grafted animals that had been adrenalectomized. Testicular LH/hCG binding, measured via the use of [¹²⁵I]iodo-hCG, was significantly increased both on a per testis and a per milligram protein basis in both groups of hyperprolactinemic rats. A significant decrease in body weight was observed in the adrenalectomized animals. Despite this, testes weight were normal in all groups, and seminal vesicle weights were significantly increased in both groups of pituitarygrafted animals. In addition, the weights of the ventral prostateand adrenals were significantly increased in the intact hyperprolactinemic animals. These results indicate that induction ofadrenal hyper activity which occurs during hyperPRL does not mediate the effects of pituitary grafts on copulatory behavior or testicular hCG binding in these animals.