TOLERANCE TO THE ANORECTIC EFFECT OF DEXFENFLURAMINE IN RATS - ROLE OF SEROTONIN, CHOLECYSTOKININ, AND NEUROPEPTIDE-Y

Tolerance to the anorectic effect of dexfenfluramine (DFEN) is shown i n rats treated either chronically with low doses or once with a high d ose of the agent. Rats given DFEN regimens that result in complete los s of DFEN anorexia showed no change in the anorexia caused by peripher al injection of cholecystokinin (CCK). The orexigenic effects of meter goline and neuropeptide Y were also unaltered as a function of DFEN pr etreatment. Both the magnitude and duration of tolerance to a test dos e of DFEN seemed to depend, in part, upon contingent (situational) fac tors, and were independent of whether brain serotonin (5-HT) measures were either unaffected or decreased by the DFEN pretreatment (low and high doses, respectively).