Dopaminergic control of prolactin secretion regulation (review of experimental and clinical trials)

Prolactin secretion (PRL) is under complex neuroendocrine control. in which factors of various nature are involved: neurotransmitters, biologically active neuropeptides, as well as hormones of peripheral endocrine glands. However, the dominant role belongs to dopamine, which is the most important of endogenous prolactin inhibiting substances. Convincing evidence of this was obtained after the discovery and study of the tuberoinfundibular dopaminergic system of the hypothalamus, which is a part of a complex neuroendocrine system for regulating the secretion of PRL.

A central action of α-melanocyte-stimulating hormone on serum levels of LH and prolactin in rats

ABSTRACT We have investigated the effect of administration of α-MSH into the median eminence (ME) of rats on the release of LH and prolactin. Continuous infusion of α-MSH (0·5 μg/h) into the ME from the afternoon of the second day of dioestrus and over the 24 h of pro-oestrus inhibited the preovulatory LH and prolactin surge and the occurrence of ovulation. This inhibitory effect on LH and prolactin release was also observed in chronically ovariectomized rats given a single injection of α-MSH (1 μg/μl per rat) into the ME (blood samples were collected 0,20,60,90,105 and 120 min after injection). The intraperitoneal injection of the dopamine receptor blocker, haloperidol (2 mg/kg), 30 min before the injection of α-MSH into the ME prevented the inhibitory effect of α-MSH on the release of LH and prolactin. These results suggest that hypothalamic α-MSH might be involved in the regulation of LH and prolactin release via the tuberoinfundibular dopaminergic system and that this system also modifies the serum concentrations of α-MSH. Journal of Endocrinology (1990) 124, 127–132