PIMOZIDE DOES NOT SHIFT PALATABILITY - SEPARATION OF ANHEDONIA FROM SENSORIMOTOR SUPPRESSION BY TASTE REACTIVITY

Several ''taste reactivity'' studies of dopamine and reward have concl uded that pimozide suppresses the hedonic reaction patterns normally e licited by sucrose but enhances aversive reaction patterns elicited by quinine. However, other taste reactivity studies have failed to find hedonic/aversive shifts in reaction patterns after dopamine antagonist s or dopamine lesions. The divergent conclusions have come from two di fferent laboratories. To resolve the controversy regarding dopamine bl ockade and palatability, the present study joined the two laboratories to investigate the effect of pimozide on taste reactivity patterns el icited by sucrose and quinine. The results replicated many (but not al l) of the earlier findings and identified procedural factors responsib le for different outcomes. Overall, the results provide evidence for s ensorimotor effects of pimozide on taste reactivity but not for a hedo nic shift in palatability. Pimozide suppressed both hedonic and aversi ve reaction patterns in a gradual sensorimotor fashion when the elicit ing taste stimulus was repeated or continued for several minutes. The general suppression typically did not alter the initial reaction to a taste but emerged only after an oral infusion of sucrose or quinine co ntinued for several minutes or trials. Aversive reactions were never e nhanced. The balance between hedonic and aversive reaction patterns wa s not shifted by pimozide. We conclude that pimozide produces a sensor imotor impairment of taste reactivity patterns but does not shift tast e palatability toward anhedonia or aversion. (C) 1997 Elevier Science Inc.