Participation of serotonin in thyrotropin release. I. Evidence for the action of serotonin on thyrotropin releasing hormone release.
Injection of serotonin (5-HT) into the third ventricle of the rat resulted in a rapid increase of serum TSH; a significant effect was observed 5 min after injection, whereas the maximal effect appeared 10 min after the injection of 1 microgram 5-HT. This stimulating effect of 5-HT was completely prevented by pretreatment with cyproheptadine, a blocker of 5-HT receptors, whereas fluphenazine, a dopamine receptor blocker, was unable to block it. Third venticle injection of 5-HT in rats bearing anterior hypothalamic lesions (which did not affect the suprachiasmatic nucleus or the medio-basal hypothalamus) also induced an increase of serum TSH similar to that observed in normal rats despite the fact that these animals show a lower basal TSH. In vitro, the addition of 5-HT to an incubation medium containing one hemi-anterior pituitary did not modify medium TSH, whereas 5-HT addition induced an increase of medium TSH in the system containing one hemi-anterior pituitary and two hypothalami. We conclude that 5-HT acts on TSH function probably through a stimulation of TRH release.
D000818:Animals; D003533:Cyproheptadine / Q000494:pharmacology; D005476:Fluphenazine / Q000494:pharmacology; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology; D008297:Male; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000502:physiology; D051381:Rats; D012701:Serotonin / Q000494:pharmacology*; D013972:Thyrotropin / Q000097:blood*; D013973:Thyrotropin-Releasing Hormone / Q000097:blood*
D003533:Cyproheptadine; D012701:Serotonin; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin; D005476:Fluphenazine