Infusion of CCK-8 into hepatic-portal vein fails to reduce food intake in rats

Abstract

If the putative satiating effect of endogenous cholecystokinin (CCK) is produced through a circulating hormonal mechanism, then administration of exogenous CCK into the hepatic-portal vein should decrease meal size. To test this, one form of endogenous CCK, the C-terminal octapeptide CCK-8, was infused intraportally in doses of 4 and 8 micrograms/kg just prior to a test meal. Neither dose decreased food intake after intraportal infusion even though intraperitoneal administration of 4 micrograms/kg CCK-8 decreased meal size approximately 50% in the same rats. The results suggest that if endogenous CCK-8 has a satiating effect, it acts primarily through a paracrine mechanism.