Neuroendocrine control of prolactin secretion: the role of the serotonergic system

The secretion of prolactin (PRL) falls into distinct patterns in mammals. Suckling, stress, cervical stimulation and estrogen all stimulate PRL secretion. The estrogen-induced afternoon PRL surge is circadian in nature and is regulated by the central serotonergic system. Interruption of the serotonergic system by all means blocks the PRL surge. As for the site and mechanism of 5-HT action, it has been shown that 5-HT has no direct effect on the anterior pituitary and its action on PRL secretion may be dissociated from its peripheral cardiovascular effect. Its action may not involve the central dopaminergic system or interaction with the central opioid system. However, it may be stimulating a yet unidentified PRL-releasing factor during specific time in the afternoon of estrogen-treated rats.