Function of serotonin in physiologic secretion of growth hormone and prolactin: action of 5,7-dihydroxytryptamine, fenfluramine and p-chlorophenylalanine.
Growth hormone (GH) and prolactin secretory patterns in male rats chronically implanted with venous cannulae were studied in response to treatments known to acutely or chronically deplete central serotonin (5-HT) or to permanently destroy a high proportion of 5-HT neural structures. Spontaneous prolactin secretion was little affected by chronic 5-HT depletion produced by 5,7-dihydroxytryptamine (5,7-DHT) or parachlorophenylalanine (PCPA). Acute 5-HT release induced by fenfluramine produced sustained prolactin secretion in intact and 5-HT-depleted rats. GH secretion was inhibited by PCPA, and for 3 days following 5,7-DHT, but was normal by 7 and 21 days. Acute 5-HT release stimulated by fenfluramine unexpectedly inhibited GH in intact and 5-HT-depleted rats. It is concluded that 5-HT is a potent facilitatory neurotransmitter for prolactin; and it appears to have both facilitatory and inhibitory effects on GH. Recovery of GH secretory patterns within 7 days of 5,7-DHT treatment indicates that mechanisms act rapidly to compensate for depletion of 5-HT, and that it is difficult to achieve functional depletion of 5-HT for more than a few days.
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology*; D000818:Animals; D004102:Dihydroxytryptamines / Q000494:pharmacology*; D010134:Fenclonine / Q000494:pharmacology*; D005277:Fenfluramine / Q000494:pharmacology*; D013006:Growth Hormone / Q000097:blood*; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology*; D007276:Injections, Intraventricular; D008297:Male; D008473:Median Eminence / Q000187:drug effects / Q000502:physiology*; D009115:Muridae; D011388:Prolactin / Q000097:blood*; D011985:Receptors, Serotonin / Q000187:drug effects; D012701:Serotonin / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects
D004102:Dihydroxytryptamines; D011985:Receptors, Serotonin; D005277:Fenfluramine; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D011388:Prolactin; D013006:Growth Hormone; D010134:Fenclonine