Serotonergic stimulation of prolactin release in the young turkey (Meleagris gallopavo).
Serum prolactin (PRL) levels were determined by homologous radioimmunoassay in 6- to 10-week-old domestic white turkeys treated by intraperitoneal injection of agents that alter serotonergic activity. Quipazine (0.1-10.0 mg/kg), a serotonin (5-hydroxytryptamine; 5-HT) agonist, induced a dose-dependent rise in serum PRL level 1 hr after injection. The 5-HT precursor, 5-hydroxytryptophan (5-HTP), at doses of 80 and 150 mg/kg produced over a twofold elevation in PRL level 1 hr after administration, though the 50 mg/kg dose failed to produce any change. Administration of fluoxetine (10 mg/kg), a 5-HT reuptake blocker, induced an elevation in PRL level persisting 3 hr. When fluoxetine injection preceded administration of a weakly stimulatory dose of 5-HTP, a prolonged elevation in PRL level was observed. methysergide (MES), a 5-HT antagonist, administered in a 10 mg/kg dose produced no change in PRL level, while the 25 mg/kg dose initially produced a spike in PRL level which subsequently dropped slightly below the control level. Prior injection of 20 mg/kg MES completely blocked the serum PRL rises induced by quipazine and 5-HTP. These results suggest that serotonergic mechanisms are involved in the regulation of pituitary PRL release beyond basal levels in young domestic turkeys.
D006916:5-Hydroxytryptophan / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005473:Fluoxetine / Q000494:pharmacology*; D007274:Injections, Intraperitoneal; D008784:Methysergide / Q000494:pharmacology*; D011388:Prolactin / Q000097:blood*; D011437:Propylamines / Q000494:pharmacology*; D011804:Quinolines / Q000494:pharmacology*; D011814:Quipazine / Q000031:analogs & derivatives / Q000494:pharmacology*; D011863:Radioimmunoassay; D012701:Serotonin / Q000502:physiology; D013268:Stimulation, Chemical; D014422:Turkeys / Q000502:physiology*
D011437:Propylamines; D011804:Quinolines; D005473:Fluoxetine; D012701:Serotonin; D011814:Quipazine; D011388:Prolactin; D006916:5-Hydroxytryptophan; D008784:Methysergide