PRETREATMENT WITH THE 5-HT1A RECEPTOR AGONISTS 8-OH-DPAT OR GEPIRONE DOES NOT ATTENUATE THE INHIBITORY EFFECT OF SYSTEMICALLY ADMINISTERED CHOLECYSTOKININ (CCK) ON FOOD-INTAKE IN RATS

In order to investigate whether the inhibitory effect of systemically administered cholecystokinin (CCK) on food intake is dependent on an i nteraction with central 5-hydroxytryptamine (5-HT) processes, we exami ned the effects of pretreating rats that were deprived of food for var ious periods of time (22 h in Experiments 1 and 3, 3 h in Experiment 2 , and 1 h in Experiment 4) with the 5-HT1A receptor agonists, 8-OH-DPA T or gepirone, on the suppression of feeding induced by intraperitonea l CCK. 8-OH-DPAT(100 mu g/kg, Experiments 1 and 2) or gepirone (2 mg/k g, Experiments 3 and 4) administered subcutaneously 60 min prior to in traperitoneal injection of CCK (6 mu g/kg) did not attenuate the suppr essant effect of CCK on feeding in any of these experiments. The 5-HT1 A agonists had no significant effects on food intake on their own. As it has been established that the doses of 8-OH-DPAT and gepirone used in this study decrease 5-HT function in the central nervous system, th e present results indicate that it is unlikely that the inhibitory eff ect of systemically administered CCK on food intake is dependent on an interaction with intact central 5-HT systems.