Clozapine antagonizes the induction of striatal Fos expression by typical neuroleptics.

Previous studies have shown that the atypical neuroleptic clozapine is less potent at inducing Fos expression in the dorsolateral striatum than are typical neuroleptics. We report here that pretreatment with clozapine (5-20 mg/kg) actually attenuates the striatal Fos expression induced by the typical neuroleptics haloperidol and raclopride. These results suggest clozapine has pharmacological properties which actively antagonize the effects of dopamine D2 receptor blockade on striatal immediate-early gene expression.