Cholecystokinin-induced suppression of feeding: an evaluation of the generality of gustatory-cholecystokinin interactions.

Previous findings in this laboratory suggest that the cholecystokinin-induced decrease in food intake may be the result of a modulation of the orosensory factors controlling feeding. More recently we have presented evidence indicating that in sated animals the magnitude of cholecystokinin-induced inhibition of intake is proportional to the concentration of sucrose feeding solutions. The present study examined the generality of this finding by determining the effect of the synthetic octapeptide of cholecystokinin (CCK-8) on the intake of solutions varying in both taste intensity and taste quality. To eliminate the need to consider CCK-8 effects on food deprivation and to more precisely address the effect of CCK-8 on the component of feeding maintained by taste stimuli, the effect of CCK-8 was evaluated in animals being maintained on an ad lib feeding schedule. The ingestion of water, glucose, NaCl and quinine was induced with intraperitoneal injections of hypertonic saline. It was found that although CCK-8 injections did not inhibit intake when water was being consumed, the addition of tastents to water resulted in inhibitions of intake that were positively related to the tastent concentration. These data add further support to the earlier finding of a covariation between the magnitude of the CCK-8 decrease in ingestive behavior and the concentration of sucrose feeding solutions. Furthermore, these findings indicate that this covariation relation is seen using a different motivating stimulus than in our previous studies (hypertonic saline-induced consumption) and across a number of taste modalities including those on the negative side of the so-called "hedonic" continuum.