Effects of cholecystokinin on taste preference and sensitivity in rats

Cholecystokinin octapeptide (CCK-8) reduced the amount consumed or the number of licks of several concentrations of sucrose in short-term tests with rats that were hungry, satiated, or fed ad lib. The suppressive effect of CCK-8 was generally smaller in the hungry than in the satiated or ad-lib condition. In the satiated and ad-lib conditions, there was no effect of sucrose concentration on the magnitude of the CCK-8 effect. In hungry rats, the concentration-intake function for sucrose was lowered and flattened by both CCK and natural satiety. In order to determine whether a taste change is involved in this short-term reduction of sucrose intake, integrated chorda tympani responses were measured before and after iv infusions of CCK-8 or NaCl. The peak response to 0.3 M sucrose significantly increased after two 5-microgram infusions of CCK-8. Peak and tonic responses to sucrose and saline tended to increase after CCK-8 but not NaCl infusions. These results indicate that CCK-8 reduces sucrose intake in situations in which postingestional factors are minimal and that sucrose concentration has little effect on the size of this suppression. A change in perceived taste intensity or quality may play a role in the inhibitory effect of CCK-8 on intake.