SEROTONERGIC REGULATION OF RENIN AND PROLACTIN SECRETION

Drugs that, directly or indirectly produce activation of serotonin (5- HT) receptors increase plasma concentrations of both prolactin and ren in. The serotonergic regulation of prolactin and renin secretion share several common characteristics. Serotonergic neurons originating in t he dorsal raphe and terminating in the hypothalamus stimulate the secr etion of both prolactin and renin. Destruction of cells in the hypotha lamic paraventricular nucleus (PVN) inhibits both the prolactin and re nin responses to 5-HT agonists and 5-HT-releasing drugs. Activation of 5-HT2 receptors increases the secretion of both prolactin and renin, while activation of other 5-HT receptor subtypes has differential effe cts on these hormones. However, there are also differences between the serotonergic mechanisms that regulate the secretion of prolactin and renin. Activation of 5-HT1A receptors increases the secretion of prola ctin but not of renin. In addition, activation of peripheral 5-HT3 rec eptors stimulates the secretion of renin, while activation of peripher al 5-HT3 receptors increases plasma levels of prolactin but not renin. In humans, the effect of 5-HT-releasing drugs and 5-HT agonists on pl asma prolactin concentrations has been studied to a greater extent tha n effects on most other hormones. In contrast, the renin response to 5 -HT agonists and 5-HT releasers has not been well characterized in hum ans. Because of the important role of the renin-angiotensin system in cardiovascular regulation, studies on the serotonergic regulation of r enin release in humans could increase our understanding of cardiovascu lar disorders associated with altered serotonergic function. Examples include anxiety and consequences of cocaine abuse. In conclusion, comp aring the serotonergic regulation of prolactin and renin secretion ind icates similarities that might shed light on common brain mechanisms t hat regulate neuroendocrine function.