Effects of Dopamine, Norepinephrine, and Serotonin on Plasma Prolactin Levels in Ovariectomized, Pituitary-Grafted Rats

Chronically ovariectomized rats with intact pituitary glands were implanted with anterior pituitary homografts under the kidney capsule. Rats which received a transplanted anterior pituitary exhibited significantly higher basal plasma prolactin levels than rats receiving no transplants. Rats received systemic infusions of norepinephrine, dopamine, and serotonin. Only dopamine was capable of significantly suppressing prolactin secretion from the pituitary homograft. Norepinephrine and serotonin had no effect on plasma prolactin levels. These results demonstrate the direct effect of dopamine on prolactin release by the anterior pituitary and are consistent with the view that dopamine may be PIF.