Chronic phencyclidine (PCP)-induced modulation of muscarinic receptor mRNAs in rat brain : Impact of antipsychotic drug treatment

► M1, M2, and M3 mRNA expression was examined after antipsychotic treatment. ► Clozapine and haloperidol produced different changes in M1 mRNA levels. ► Chronic PCP treatment increased M1 mRNA in the prefrontal cortex. ► Chronic clozapine or haloperidol did not reverse the PCP effect.