Feeding behavior in rats is differentially affected by pimozide treatment depending on prior experience.

It has been observed in previous research that rats treated with the dopamine receptor antagonist, pimozide, failed to eat palatable food pellets. Two possible interpretations for this effect were evaluated, namely, a reduction in the primary level of food motivation or drug-induced hypokinesia resulting in a subsequent failure to find the food. The effects of several doses of pimozide (1.0, 2.0 and 4.0 mg/kg IP) on feeding in rats with or without experience eating food pellets in an experimental chamber were tested. Pimozide had little effect on feeding in rats with prior experience whereas the drug produced a dose-dependent impairment in rats without similar experience. In addition, although the initial impairment was severe, the nonexperienced rats became more efficient at locating the food despite pimozide treatment. These results appear to rule out a primary motivational interpretation for the effect of pimozide on feeding; rather, the impairment is likely due to the drug's hypokinesia-producing properties.