Olanzapine, quetiapine, and risperidone: long-term effects on monoamine transporters in rat forebrain.

Long-term effects of novel atypical antipsychotic drugs on monoamine transporters are unknown. We compared labeling of dopamine (DAT) and serotonin (SERT) transporter proteins in subregions of rat corpus striatum by quantitative autoradiography with [(3)H]2-beta-carbomethoxy-3-beta-[4'-iodophenyl]tropane ([(3)H]beta-CIT) and [(3)H]paroxetine after 28 days of continuous subcutaneous infusion of olanzapine, quetiapine, risperidone, or vehicle controls. Drug treatment did not significantly alter the abundance of either transporter type in caudate-putamen or nucleus accumbens, indicating that transporter proteins required to inactivate synaptically released dopamine and serotonin resist adaptations to long-term treatment with novel antipsychotics that affect neurotransmission by these amines.