D-2 AND 5-HT2 MODULATION OF PSYCHOSTIMULANT-INDUCED FACILITATION OF BRAIN-STIMULATION REWARD

Previous research in our laboratory demonstrated that mixed D-2/5-HT2 antagonists (i.e., MDL 28, 133A, and risperidone) attenuate both amphe tamine and cocaine-induced facilitation of brain stimulation reward. T he relative contributions of dopaminergic and serotonergic antagonism to these effects was assessed in the present study. Factorial combinat ions of the D, antagonist eticlopride and the 5-HT2 antagonist MDL 100 ,907 were evaluated for their ability to reverse both cocaine and amph etamine-induced facilitation of brain stimulation reward. Eticlopride significantly reduced the effects of both amphetamine and cocaine, whi le MDL 100,907 had no effect on self-stimulation thresholds when admin istered alone, or in combination with eticlopride. Thus, no evidence f or serotonergic regulation of the euphoric effects of psychostimulants was obtained. (C) 1995 Wiley-Liss, Inc.