Baicalin Treatment Effect On Cerebral Ischemia And Antioxidant Mechanisms

Ischemic stroke results from cerebrovascular stenosis and cerebral vascular in a short time,concluding transient ischemic attack,cerebral thrombosis and cerebral embolism.The pathogenesis of ischemic stroke is mainly related to inflammatory damage, intracellular calcium overload, free radical damage, apoptosis, excitatory amino acid damage and so on. Baicalin as one of flavonoids is the main pharmacological ingredient of Chinese herbal Scutellaria, with a good antioxidant activity. Although it was reported that baicalin could treat ischemic stroke as an antioxidant, there is no further research on the mechanism of antioxidant effect, just mainly aimed at endogenous activity of antioxidant enzymes and lipid peroxidation. This paper aims to investigate the further mechanism of baicalin antioxidant effect.1 ObjectiveThe objectives of this paper are to research the mechanism of antioxidant effect of baicalin in three different levels on animal model, cell model and vitro chemical system, and to confirm the therapeutic time window of baicalin on MCAO rats.2 Methods2.1 Therapeutic time window of baicalin on middle cerebral artery occlusion (MCAO) rats60 healthy male rats were devided into 6 groups randomly:10 rats in sham operation group,10 rats in model group,10 rats in baicalin Oh group,10 rats in 2h group,10 rats in 4h group,10 rats in 6h group. Therapeutic time window of baicalin was determined by neurological scores and cerebral infarct volume of MCAO rats.2.2 The intervention of baicalin on oxidative stress in MCAO mice60 healthy male mice were devided into 3 groups randomly:20 mice in sham operation group,20 mice in model group, and 20 mice in baicalin group. In each group 10 mice were used to detect SOD activity and MDA content,5 mice to ROS fluorescence, and 5 mice to NADPH oxidase activity. The intervention of baicalin on Oxidative stress was detected by SOD test, MDA test, and ROS fluorescence expression.2.3 The ettect of baicalin on rat primary neurons oxidative injury induced by hydrogen peroxide (H2O2)The experimental model of oxidative stress of SD neonatal rats primary neurons were induced by 300μmol/L H2O2. The antioxidative effect of baicalin was measured by assaying cell survival, LDH content and the activity of SOD in primary neuron culture fluid.2.4 The effect of baicalin on free radical scavenging and producingUsing kits and chemical reaction systems to test different concentrations of baicalin in scavenging free radical DPPH, superoxide anion. The effect of baicalin on free radical producing were measured by total antioxidant capacity kit and xanthine oxidase test.3 Results3.1 Therapeutic time window of baicalin on middle cerebral artery occlusion (MCAO) ratsCompared with model group, baicalin Oh,2h,4h group can improve the neurological scores and reduce infarct volume (P<0.01, P<0.01, P<0.05). Baicalin 6h group also can improve the neurological scores and infarct volume, but there is no statistically significance compared with model group (P>0.05).3.2 The intervention of baicalin on Oxidative Stress in MCAO miceCompared with model group, baicalin group can significantly inhibit MDA production and increase SOD activity in mouse brain homogenate (P<0.01, P<0.01). Baicalin can significantly reduce the ROS fluorescence expression (P<0.01) and inhibit NADPH oxidase activity (P<0.05) after cerebral ischemia.3.3 The ettect of baicalin on rat primary neurons oxidative injury induced by hydrogen peroxide (H2O2)Baicalin can significantly increase the neuronal survival rate after hydrogen peroxide injury, decrease LDH leakage (P<0.05, P<0.01) and enhance SOD activity (P<0.01) in primary neuron culture fluid.3.4 The effect of baicalin on free radical scavenging and producingBaicalin has a good scavenging effect in free radical DPPH and superoxide anion. The content of uric acid produced by xanthine decrease followed the concentration of baicalin increasing. Baicalin has significant total antioxidant capacity, and shows an obvious dose-effect relationship.4 ConclusionsIn animal experiments, baicalin shows a good protective effect on MCAO rats, and the therapeutic time window is 4 hours after ischemia. The results demonstrate that cerebral protective effect of baicalin is related to its antioxidant effect, concluding reduction of ROS expression and MDA content, inhibition of NADPH oxidase activity and enhancement of SOD activity.Baicalin plays a protective role in primary neuronal hydrogen peroxide injury, which furtherly demenstrates baicalin against oxidative stress.The vitro chemical experiments confirm that baicalin can scavenge free radicals directly, inhibit xanthine oxidase activity, decrease superoxide anion, and show a good total antioxidant capacity.