Apomorphine selectively stimulates opiocortin hormone release from the pars distalis in rats.
Administration of apomorphine (0.3-3.0 mg/kg s.c.) evoked a rapid increase (10 min) in circulating levels of immunoreactive beta-endorphin (i beta-END) in rats. As judged by gel filtration chromatography, virtually all of the increase corresponded to i beta-END resembling beta-lipotropin (beta-LPH) in molecular size. The apomorphine response was inhibited by pretreatment with either the dopamine antagonist, haloperidol (0.1 mg/kg i.p., 2 h) or the glucocorticoid, dexamethasone (50 micrograms/kg i.p., 4 h). Together, these results indicate that dopamine-receptor activation stimulates the release of opiocortin hormones from corticotrophs of the pars distalis.
Farah
J M
JM
Sapun-Malcolm
D
D
Mueller
G P
GP
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism; D004723:Endorphins / Q000378:metabolism*; D008297:Male; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects; D001615:beta-Endorphin
D004723:Endorphins; D011954:Receptors, Dopamine; D001615:beta-Endorphin; D003346:Corticotropin-Releasing Hormone; D001058:Apomorphine