Apomorphine increases plasma oxytocin concentration in male rats.
The effect of systemic administration of the dopamine agonist apomorphine on plasma oxytocin concentration was studied in male rats by a specific radioimmunoassay. Apomorphine given subcutaneously in doses ranging from 80 to 480 micrograms/kg increased oxytocin levels in a dose-dependent manner. The minimal effective dose was found to be 80 micrograms/kg, which induced a 66% increase above basal values, while the maximal effect (210%) was seen with a dose of 240 micrograms/kg. The apomorphine effect was prevented by pretreatment with the DA D2-receptor blockers haloperidol (0.2 mg/kg i.p.) or (-) sulpiride (10 mg/kg i.p.) and, but only partially, with the DA D1-receptor blocker SCH 23390 (0.2 mg/kg s.c.). The present results suggest that hypothalamic dopamine has a facilitatory role on the release of oxytocin in male rats.
Melis
M R
MR
Department of Neurosciences, University of Cagliari, Italy.
Argiolas
A
A
Gessa
G L
GL
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D001552:Benzazepines / Q000494:pharmacology; D004298:Dopamine / Q000502:physiology*; D006220:Haloperidol / Q000494:pharmacology; D008297:Male; D010121:Oxytocin / Q000097:blood*; D010904:Pituitary Gland, Posterior / Q000187:drug effects; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013469:Sulpiride / Q000494:pharmacology
D001552:Benzazepines; D010121:Oxytocin; D013469:Sulpiride; D006220:Haloperidol; D001058:Apomorphine; D004298:Dopamine