Inhibitory effects of cholecystokinin develop through interaction with duodenal signals.
I previously reported that cholecystokinin octapeptide (CCK-8) had little effect on feeding motivation as indexed by runway performance, but that substantial impairment resulted from the interaction of CCK-8 and prefeeding of sucrose. If the sucrose was sham-fed, potentiation of the effect of CCK-8 was seen only after large doses. The current experiments examined whether synergy between 1 microgram/kg CCK-8 and prefeeding could be reproduced using gastric, duodenal, or hepatic-portal infusions. Gastric and duodenal infusions of 30% sucrose were effective; in conjunction with CCK-8 they decreased running speed as substantially as prefeeding did. The duodenal effect was specific. Glucose appeared to be as effective as sucrose, whereas equi-osmotic saline and mannitol were not. Intraportal glucose was relatively ineffective; interaction with CCK-8 was seen only after very large infusions, and the resulting running speeds did not approach those seen after prefeeding or gastrointestinal infusions. These results suggest that decreased feeding motivation after 1 microgram/kg CCK-8 develops through synergy between this peptide and a carbohydrate-sensitive signal generated within the small intestine.
Cox
J E
JE
Department of Psychology, University of Alabama, Birmingham 35294.
D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects; D001786:Blood Glucose / Q000378:metabolism; D004386:Duodenum / Q000294:innervation*; D004435:Eating / Q000187:drug effects*; D006815:Hunger / Q000187:drug effects; D007262:Infusions, Intravenous; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009433:Neural Inhibition / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects; D012527:Satiation / Q000187:drug effects*; D012528:Satiety Response / Q000187:drug effects*; D012844:Sincalide / Q000494:pharmacology*; D013270:Stomach / Q000294:innervation; D014630:Vagus Nerve / Q000187:drug effects
D001786:Blood Glucose; D012844:Sincalide