Background: Oxidative stress and mitochondrial dysfunction have been implicated in the pathophysiology of schizophrenia.
Aims: We investigated whether antipsychotic clozapine modulates nicotinamide adenine dinucleotide phosphate oxidase and mitochondrial burdens induced by phencyclidine in mice.
Methods: We examined the effect of clozapine on nicotinamide adenine dinucleotide phosphate oxidase activation, mitochondrial burdens (i.e. oxidative stress and mitochondrial dysfunction), and activities of enzymatic antioxidant in the prefrontal cortex, and subsequent abnormal behaviors induced by repeated treatment with phencyclidine. p47 phox Knockout mice and LY294002, a phosphoinositide 3-kinase inhibitor, were employed to elucidate the pharmacological mechanism of clozapine.
Results: Phencyclidine treatment resulted in an early increase nicotinamide adenine dinucleotide phosphate oxidase activity, membrane translocation of p47 phox, interaction between p-Akt and p47 phox, and mitochondrial burdens in wild-type mice. Although these increases returned to near control level four days post-phencyclidine, mitochondrial superoxide dismutase and glutathione peroxidase activities were decreased at that time. Clozapine, LY294002, or p47 phox knockout significantly ameliorated social withdrawal and recognition memory deficits produced by phencyclidine. Importantly, LY294002 did not significantly alter the effects of clozapine against abnormal behaviors and the interaction between p-Akt and p47 phox induced by phencyclidine. Furthermore, neither LY294002 nor clozapine exhibited any additive effects to the protection afforded by p47 phox knockout against phencyclidine insult.
Conclusion: Our results suggest that p47 phox gene mediates phencyclidine-induced mitochondrial burdens and abnormal behaviors, and that the interactive modulation between p47 phox and phosphoinositide 3-kinase/Akt is important for the understanding on the pharmacological mechanism of clozapine.
Keywords: Clozapine; mitochondria; nicotinamide adenine dinucleotide phosphate oxidase; oxidative stress; p47phox knockout mice; phencyclidine-induced abnormal behaviors; phosphoinositide 3-kinase/Akt signaling; prefrontal cortex.