Effects of typical and atypical antipsychotics and receptor selective compounds on acetylcholine efflux in the hippocampus of the rat.

Some atypical antipsychotic drugs appear to improve cognitive function in schizophrenia and since acetylcholine (ACh) is of importance in cognition, we used in vivo microdialysis to examine the effects of antipsychotics administered acutely (SC or IP) at pharmacologically comparable doses on ACh outflow in the hippocampus of the rat. The atypical antipsychotics olanzapine and clozapine produced robust increases in ACh up to 1500% and 500%, respectively. The neuroleptics haloperidol, thioridazine, and chlorpromazine, as well as the atypical antipsychotics risperidone and ziprasidone produced modest increases in ACh by about 50-100%.