title: Possible direct effect of serotonin on pituitary prolactin secretion: in vivo and in vitro studies.
abstract: In this work we analyze the possibility of serotonin (5-HT)-releasing prolactin (PRL) through a direct action at the pituitary level. 5-HT (2 mg/kg i.v.) stimulates PRL secretion in hypophysectomized autotransplanted animals (HAG) significantly and this effect was not influenced by pretreatment with the dopaminergic antagonist domperidone. In perifused pituitaries, 5-HT administration (0.01, 0.1 and 1 microM for 90 min, or 1, 10, 100 microM for 15 min) was ineffective in stimulating PRL release. In pituitaries obtained from animals previously treated with the neurotoxic 5,7-dihydroxytryptamine (5,7-DHT) or vehicle and incubated in the presence of 5-HT (2.5, 5 and 10 microM), no response in PRL secretion was observed. These results suggested that 5-HT does not release PRL through a direct pituitary action, and that the effect observed in HAG animals could be mediated through the release of a PRL-releasing factor after 5-HT administration.
mesh_terms: D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D004298:Dopamine / Q000494:pharmacology; D007016:Hypophysectomy; D066298:In Vitro Techniques; D008297:Male; D010903:Pituitary Gland, Anterior / Q000187:drug effects* / Q000378:metabolism / Q000637:transplantation; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology
chemical_list: D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D004298:Dopamine