Stimulatory and inhibitory effects of prostaglandin E2 on prolactin release in the domestic fowl.
In vivo prolactin secretion was increased in immature cockerels 20-30 min after the intravenous administration of prostaglandin (PG) E2 at a dose of 200 micrograms/kg. The addition of PGE2 to incubation medium had no direct effect on the release of pituitary prolactin during short-term (3-hr) culture, but augmented the stimulatory effect of hypothalamic tissue on prolactin secretion. The stimulatory effect of serotonin, noradrenaline, acetylcholine, and histamine on hypothalamus-induced prolactin release was also increased when pituitaries were coincubated with 10(-7)M PGE2, as was the stimulatory effect of thyrotrophin-releasing hormone (TRH) and hypothalamic extract (HE). The long-term (24-hr) preincubation of pituitaries with 10(-7)M PGE2 reduced the responsiveness of the prolactin-secreting cells to TRH or HE stimulation. PGE2 treatment also reduced the stimulatory effect of hypothalamic tissue on prolactin release and diminished the stimulatory effect of serotonin on hypothalamus-induced prolactin secretion. A 24-hr preincubation of hypothalamic tissue with 10(-7)M PGE2 also reduced its stimulatory effect on prolactin release when subsequently incubated with control pituitary glands. These results demonstrate that PGE2 initially stimulates in vivo and in vitro prolactin secretion in the fowl, possibly by increasing the release of hypothalamic prolactin-releasing activity and/or by increasing pituitary sensitivity to provocative stimuli. Chronic PGE2 stimulation appears to result in a reduction in pituitary responsiveness to stimulatory influences and in the release of hypothalamic-releasing activity.
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002645:Chickens; D015232:Dinoprostone; D006632:Histamine / Q000494:pharmacology; D007031:Hypothalamus / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism*; D011458:Prostaglandins E / Q000494:pharmacology*; D012701:Serotonin / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology
D011458:Prostaglandins E; D012701:Serotonin; D013973:Thyrotropin-Releasing Hormone; D006632:Histamine; D011388:Prolactin; D015232:Dinoprostone; D000109:Acetylcholine; D009638:Norepinephrine