Pharmacologically specific pretreatment effects on apomorphine-mediated conditioned taste aversions in rats.

Pretreatment with pimozide (0.2-1.2 mg/kg) reduced a conditioned taste aversion produced by apomorphine (0.4 mg/kg) in a dose-related manner. This pretreatment effect was pharmacologically specific as shown by the inability of pimozide to prevent a conditioned taste aversion produced by nicotine (0.4 mg/kg). The results argue against the hypothesis that "proximal pre-exposure" effects are always non-specific and indicate that further pharmacological characterisation of drug-induced conditioned taste aversion may be possible. Pretreatment with a peripherally-acting antiemetic compound, domperidone, did not prevent apomorphine producing conditioned taste aversions. These data suggest that conditioned taste aversions produced by apomorphine are mediated through central dopamine receptors unrelated to the emetic properties of apomorphine and are not a result of conditioned nausea.