The effects of pimozide on the consumption of a palatable saccharin-glucose solution in the rat.

Two experiments investigated the role of dopamine in reward mechanisms by examining the effects of the specific dopamine receptor blocker pimozide on drinking behavior in the rat. In Experiment 1, the effects of pimozide on the consumption of a palatable saccharin-glucose solution were compared to the effects of quinine adulteration of the same solution. Pimozide and quinine both reduced 30 min/day consumption, decreased lick rate early in the drinking session and reduced lick efficiency in a dose related manner. In Experiment 2, the effects of pimozide on the consumption of a saccharin-glucose solution and water were compared in thirsty and nonthirsty rats. Pimozide suppressed the consumption of both water and the saccharin-glucose solution in a dose related manner. However, saccharin-glucose solution intake was suppressed more than water intake, and this effect was independent of thirst drive. The drug also decreased lick rate early in the drinking session and lick efficiency. The results are discussed in terms of the reward and sensory-motor deficits produced by dopamine receptor blocking agents.