Biological role of prolactin

Prolactin (PRL) is a peptide hormone primarily associated with lactation. It is synthesized and secreted by lactotrope cells in the adenohypophysis. It is also produced in other tissues including the breast and the decidua. Pituitary prolactin secretion is regulated by neuroendocrine neurons in the hypothalamus, most importantly by neurosecretory dopamine neurons of the arcuate nucleus, which inhibit prolactin secretion. Prolactin has many effects: it plays a role in processes such as reproduction, fat metabolism, hair shedding and immune response, the most important of which is to stimulate the mammary glands to produce milk (lactation). Prolactin has been found to stimulate proliferation of oligodendrocyte precursor cells. The activation of the prolactin-prolactin receptor complex has been recognized as an important mechanism in the induction and progression of mammary tumors, but it is not a major cause of their genesis.