Neuroendocrine Control of Prolactin Secretion

Prolactin is the most versatile of pituitary hormones in both the number and diversity of physiologic processes it regulates (107). In mammals, prolactin plays a decisive role in the preparation and maintenance of the mammary gland for milk secretion during lactation. Indeed, prolactin is essential to the survival of most mammalian young after birth. During lactation, the stimulus for prolactin secretion is triggered as the young suckle the mother's nipple. Neural impulses generated by suckling are conveyed to the central nervous system and impinge upon specialized neurons located in the hypo­ thalamus. From the nerve endings of such neurons the hypophysiotropic hormones are released that reach the anterior pituitary via the hypophysial portal vessels. Thus the neurogenic message of suckling is finally conveyed to the pituitary by the action of hypophysiotropic hormones that in the classical sense stimulate or inhibit prolactin secretion. Here we consider recent developments in our understanding of the pituitary gland with par­ ticular regard to the hypophysiotropic control of suckling-induced prolac­ tin secretion. Earlier authoritative accounts of the literature are available (85, 103, 104).