title: beta-Endorphin involvement in the antidopaminergic effect of caerulein.
abstract: Caerulein has been shown to possess a long-lasting antagonistic effect on amphetamine hyperactivity in rats when given in combination with haloperidol. We found that this effect of caerulein involved beta-endorphin. Naloxone pretreatment and hypophysectomy abolished the caerulein effect, while intracerebroventricular or intra-nucleus accumbens injection of beta-endorphin together with haloperidol administration produced an effect similar to that of caerulein. The results suggest that the long-term antagonism of the amphetamine effect of caerulein is mediated by the endogenous opioid beta-endorphin.
mesh_terms: D000661:Amphetamine / Q000037:antagonists & inhibitors*; D000818:Animals; D002108:Ceruletide / Q000494:pharmacology*; D004723:Endorphins / Q000502:physiology*; D006220:Haloperidol / Q000494:pharmacology; D007016:Hypophysectomy; D007276:Injections, Intraventricular; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology; D009714:Nucleus Accumbens / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*; D012844:Sincalide / Q000494:pharmacology; D001615:beta-Endorphin
chemical_list: D004723:Endorphins; D011954:Receptors, Dopamine; D009270:Naloxone; D001615:beta-Endorphin; D002108:Ceruletide; D000661:Amphetamine; D006220:Haloperidol; D012844:Sincalide