Nicotinamide Restores the Reduction of Parvalbumin in Cerebral Ischemic Injury

概要

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The aim of this study investigated whether nicotinamide affects parvalbumin expression in focal cerebral ischemic injury. Rats were treated with vehicle or nicotinamide (500 mg/kg) 2 hr after middle cerebral artery occlusion (MCAO), and cerebral cortex tissues were collected 24 hr after MCAO. Nicotinamide significantly decreases the volume of infarct areas in the cerebral cortex. A proteomic approach revealed that MCAO induces decreases of parvalbumin levels, while nicotinamide treatment prevents injury-induced decreases in parvalbumin. RT-PCR and Western blot analyses demonstrated that nicotinamide restores injury-induced decreases in parvalbumin. Moreover, immunohistochemical staining confirmed that the numbers of parvalbumin-positive cells were decreased in vehicle-treated animals with MCAO, and that nicotinamide averted this decrease. In cultured hippocampal cells, nicotinamide treatment prevents the glutamate exposure-induced increase in intracellular Ca2+ concentration and decrease in parvalbumin expression. These results suggest the fact that the maintenance of parvalbumin expression is mediated to the neuroprotective function of nicotinamide against ischemic brain injury.