THE EFFECTS OF THE ATYPICAL ANTIPSYCHOTIC AMPEROZIDE ON VACUOUS JAW MOVEMENTS IN RATS - A NOVEL DOSE-RESPONSE PROFILE

Classic neuroleptic drugs produce a syndrome of vacuous jaw movements in rats, and this syndrome has been offered as an animal model of earl y onset extrapyramidal side effects. The atypical antipsychotics do no t produce elevations in vacuous jaw movements, or do so only at very h igh doses. The purpose of the present study was to determine the impac t of the putative antipsychotic, amperozide, on vacuous jaw movements in rats. Groups of rats received daily injections of haloperidol (0.2, 0.4, or 0.8 mg/kg), clozapine (2.0, 4.0, 8.0 mg/kg), amperozide (2.0, 4.0, 8.0 mg/kg) or vehicle for 4 weeks. Once per week, rats were obse rved for the presence of vacuous jaw movements. Haloperidol increased vacuous jaw movements with increasing doses. Clozapine only produced e levations in vacuous jaw movements at the highest dose. In contrast, i ncreasing doses of amperozide resulted in decreasing vacuous jaw movem ents for this portion of the dose-response curve. This is the first re port of the effect of amperozide on vacuous jaw movements and results are discussed in terms of a potentially unique behavioral profile with respect to this behavior.