Interaction of cholecystokinin-8 and pancreatic glucagon in control of food intake in dogs.

Feeding responses to continuous intravenous administration of graded doses of the COOH-terminal octapeptide of cholecystokinin (CCK-8) and pancreatic glucagon, alone and in combination, were determined in dogs fasted 4 h. Low doses of glucagon (50, 500, 5,000, 6,000 pmol.kg-1.h-1) had no effect on food intake, whereas higher doses (12 and 24 nmol.kg-1.h-1) depressed intake by 50-60%. Of the CCK-8 doses administered (50 and 400 pmol.kg-1.h-1), food intake was depressed only at the higher dose (53%). This effect was blocked by glucagon (50-5,000 pmol.kg-1.h-1). Simultaneous administration of 50 or 500 pmol.kg-1.h-1 of glucagon and 50 pmol.kg-1.h-1 of CCK-8, doses currently thought to produce plasma peptide levels similar to those occurring postprandially in dogs, had no effect on food intake. These results suggest that plasma levels of CCK and glucagon after a meal are not sufficient alone or in combination to produce satiety.