Effect of Yokukansan on Nitric Oxide Production and Hydroxyl Radical Metabolism During Cerebral Ischemia and Reperfusion in Mice

Abstract

Background: The purpose of this study was to investigate the effects of yokukansan on forebrain ischemia. Because we can measure nitric oxide production and hydroxyl radical metabolism continuously, we investigated the effect of yokukansan on nitric oxide production and hydroxyl radical metabolism in cerebral ischemia and reperfusion. Methods: Yokukansan (300 mg per kg per day) was mixed into feed and given to 16 mice for 10days. Sixteen additional mice received normal feed (control). Nitric oxide production and hydroxyl radical metabolism were continuously monitored using the salicylate trapping method. Forebrain ischemia was producedin all mice by occluding the common carotid artery bilaterally for 10minutes. Levels of the nitric oxide metabolites nitrite and nitrate were determined using the Griess reaction. Survival rates of hippocampal CA1 neurons were calculated and 8-hydroxydeoxyguanosine-immunopositive cells were counted to evaluate the oxidative stress in hippocampal CA1 neurons 72hours after the start of reperfusion. Results: Arterial blood pressure and regional cerebral blood flow were not significantly different between the 2 groups. The level of nitrate was significantly higher in the yokukansan group than in the control group during ischemia and reperfusion. Levels of 2,3- and 2,5-dihydroxybenzoic acid were significantly lower in the yokukansan group than in the control group during ischemia and reperfusion. Although survival rates in the CA1 did not differ significantly, there were fewer 8-hydroxydeoxyguanosine-immunopositive cells in animals that had received yokukansan than in control animals. Conclusions: These data suggest that yokukansan exerts reducing hydroxyl radicals in cerebral ischemic injury.