Cholecystokinin loses its satiating property in food deprived rats

Facial consummatory responses reflecting ingestive and aversive perceptions were studied and quantified in rats chronically implanted with oral catheters. A gustatory stimulus of 50 microliters of 1.75 mol.l-1 sucrose was injected into the mouth every 5 min during 65 min. Five minutes after the beginning of the session, 2 micrograms.kg-1 cholecystokinin (CCK) were injected IP Typical ingestive facial consummatory responses were observed in response to sweet stimuli before IP CCK. Aversive consummatory responses were observed in response to sweet stimuli after the IP CCK (negative alliesthesia). In the second part of the experiment the rats were denied access to food for 36 h and their mean body weight decreased from 426 g to 395 g. When the food deprived rats were subjected again to the same gustatory sessions, the IP CCK was not followed by negative alliesthesia in response to sweet stimuli. After recovery of initial body weights CCK was followed again by a strong negative alliesthesia. These results in rats show that the CCK mediation of duodenal satiety was hindered by body weight decrease.