CCK-8 can inhibit ingestive behavior by acting on the liver

THE possibility that cholecystokinin octapeptide (CCK-8) can inhibit ingest ive behavior by acting on the liver was investigated. Male rats were traine d to ingest an intraorally infused 1M solution of sucrose and then injected with 10 mu g CCK-8/kg. Intraperitoneal or hepatic portal vein, but not jug ular vein, injection suppressed intake of the sucrose solution. Intraperito neal injection was more potent than hepatic portal vein injection. Inhibiti on by hepatic portal vein injection was blocked by i.p. injection of 80 mu g/kg of the CCK-A receptor antagonist L-364,718 or by hepatic vagotomy. The results support the hypothesis that CCK-8 can inhibit ingestive behavior v ia a hormonal action on the liver. (C) 1999 Lippincott Williams & Wilkins.