Pharmacological manipulation of sincalide (CCK-8)-induced suppression of feeding.
The current study involves an investigation of the possible neurotransmitter systems involved in the ability of exogenously administered sincalide (cholecystokinin octapeptide, CCK-8) to suppress feeding. Male rats previously trained to obtain food either during a daily 3-hr session, or conditioned to obtain food pellets on a fixed-ratio or fixed-interval schedule of reinforcement, were treated IP with CCK-8, following pretreatment with representative drugs of several pharmacological classes. Pretreatment with phenoxybenzamine, tolazoline, yohimbine, morphine, haloperidol or picrotoxin reduced the efficacy of CCK-8. However, pretreatment with naloxone or clonidine potentiated the suppressant action of CCK-8 on feeding. Propranolol, diphenhydramine, cimetidine, atropine, d-amphetamine, fenfluramine or diazepam pretreatment either had no effect or no consistent action in altering the activity of CCK-8. The ability of CCK-8 to suppress feeding was not altered by subacute treatment with the anorectics, d-amphetamine or fenfluramine, using a regimen known to induce tolerance. These data indicate that CCK-8 exerts a different mechanism of action than that of fenfluramine or d-amphetamine, and furthermore, that noradrenergic, dopaminergic, GABAergic or endogenous opioid systems either mediate or can modify the effect of CCK-8 on feeding.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D003913:Dextroamphetamine / Q000494:pharmacology; D004361:Drug Tolerance; D004435:Eating / Q000187:drug effects*; D005277:Fenfluramine / Q000494:pharmacology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000187:drug effects; D011956:Receptors, Cell Surface / Q000187:drug effects; D012054:Reinforcement, Psychology; D012844:Sincalide / Q000494:pharmacology*
D011941:Receptors, Adrenergic; D011956:Receptors, Cell Surface; D005277:Fenfluramine; D012844:Sincalide; D003913:Dextroamphetamine