ABSTRACT
OBJECTIVE: A previous study indicated that acute treatment of clozapine increased the neural activity of prefrontal cortical neurons of anesthetized rats. This study was to investigate the effect of clozapine on prefrontal cortical neurons in behaving rats. METHODS: Neural activities of prefrontal cortical neurons of behaving rats were measured before and after clozapine administration using single unit recording. RESULTS: Sixty nine single units (N=69) in the medial prefrontal cortex were isolated in forty three Sprague-Dawley rats. Although clozapine did not change the overall average firing rate of prefrontal cortical neurons, there was a tendency to increase in the neural activity of neurons with low firing rate that were considered to be putative pyramidal cells (N=40). In contrast, neurons with high firing rate assumed to be putative interneurons (N=29) tended to decrease in neural activity by clozapine treatment. CONCLUSION: This result suggests that clozapine treatment enhances the neural activity of pyramidal cells and to inhibit interneurons in the prefrontal cortex. It is speculated that the enhancement of neural activity of pyramidal cells in the prefrontal cortex by clozapine treatment may contribute to its therapeutic effect.