The importance of the stomach for conditioned place preference produced bydrinking sucrose in rats

Sucrose produces conditioned place preference when the sweetener is deliver ed immediately before confinement in the place preference box. To evaluate the role of the oral and gastric effects of sucrose, rats were allowed to d rink sucrose or were given sucrose or water intragastrically by gavage. The rats developed a preference in all cases in which the reinforcing event wa s delivered 3 min 30 sec before confinement, but not when an interval of 15 min was used. Contiguity between reinforcing event and conditioning is of importance, in an additional experiment, we tried to replicate the effect o btained with plain water and evaluated the role of cholecystokinin (CCK) re ceptors. Before water administration, the rats were subcutaneously injected with saline, devazepide (0.01 mg/kg), or L-365,260 (0.01 mg/kg). Only the group treated with devazepide showed significant place preference. CCKA rec eptor blockade seems to enhance the reward value of gastric distension, and distension alone appears to be an unreliable reinforcing event.