Chapter 3 - Neurotransmitter Control of Anterior Pituitary Hormone Secretion and Its Clinical Implications in Man

Abstract

Publisher Summary This chapter reviews some experimental evidence linking classical and putative neurotransmitters with the secretion of anterior pituitary hormones. The hypothalamus and median eminence (ME) are densely innervated by neurons containing the three classical neurotransmitters—dopamine (DA), norepinephrine (NE), and serotonin (5-HT)—their receptors, and other putative neurotransmitter substances. Although there is some confusion about the exact role played by some of the conventional neurotransmitters in pituitary function, it is widely recognized that these neurons, and probably many other more distant ones, regulate the secretion and/or synthesis of hypothalamic hormones that release or inhibit the secretion of all anterior pituitary hormones. Substances traditionally considered to be neurotransmitters—such as DA—can influence the secretion of a pituitary hormone directly at the pituitary level, thus functioning as a hypothalamic neurohormone. Other substances with wide central nervous system distribution—such as the pentapeptides methionine and leucine, enkephalin, or vasoactive intestinal peptide—have been found in high concentrations in the hypothalamus, suggesting that these substances may be involved, as neurotransmitters or modulators, in the hypothalamic control of pituitary function.