Combined injection potentiates the satiety effects of pancreatic glucagon, cholecystokinin, and bombesin.

Pancreatic glucagon (PG), cholecystokinin (CCK), and bombesin (BBS) were injected individually and in combination before nondeprived rats were offered condensed milk test meals. Peptide doses that were individually below the threshold for reliable inhibition of meal size (0.15 microgram/kg CCK, 0.75 microgram/kg BBS, 100 micrograms/kg PG) combined to inhibit meal size 19-40%. The inhibitions produced by combinations including CCK were 16-21% more than the sum of the inhibitions elicited by individual injections. This indicates a potentiation of inhibition. In contrast, when peptide doses were increased, the inhibitory effects of the combinations were similar to the sum of the individual injections. None of the peptide treatments disrupted the normal behavioral sequence of postprandial satiety, and they did not reliably affect water intake in water-deprived rats. We conclude that exogenous CCK, BBS, and PG can interact to potentiate postprandial satiety.