Bombesin and cholecystokinin differentially affect ingestive microstructural variables whether given alone or in combination.

The ability of dose combinations of cholecystokinin (CCK) and bombesin to inhibit liquid glucose (0.125 gm/ml) intake and affect microstructural components of ingestive behavior in rats was examined. Five minutes before access to the glucose solution, rats were injected with dose pairs of CCK and bombesin. Both CCK and bombesin inhibited intake in a dose-related fashion. The magnitude of the inhibition produced by dose combinations was never greater than the sum of the inhibitions produced by the individual doses. CCK and bombesin affected different microstructural components of ingestion. CCK reduced burst size and cluster size, whereas bombesin reduced burst number and cluster number. These effects of the 2 peptides were not altered by the presence of the other peptide. These results suggest that different mechanisms of action underlie the feeding inhibitory actions of the 2 peptides.