| Objectives: Cerebral ischemia or stroke, one of the leading causes of death and long-term disability in aged populations, often results in irreversible brain damage and subsequent loss of neuronal function [1]. When thrombolysis therapy brings new hope to the patients it also brings a remarkable problem, cerebral ischemia reperfusion injury. Therefor, it is very important to use neuronal protective drugs accompanying with thrombolysis treatment. Puerarin is an isoflavon extracted from Kudzu root. Many researches indicate that puerarin may have protective effects on CNS injury, but it is limited in the therapy of neurological diseases because of the poor permeability through blood-brain barrier (BBB). Acetelpuerarin is a new compound derived from puerarin. When all the hydroxyls are substituted by acetyls acetylpeurarin's solubility in fat is increased and it can be inferred that its permeability through blood-brain barrier would be correspondently increased. Studies of our institute had proved that acetylpuerarin can attenuate brain ischemia/reperfusion damage by decreasing infarct volume and improving neurological deficit of rats injured by middle cerebral artery occlusion (MCAO). This prompted us to investigate further whether this flavonoid will show antioxidant activity and antiapoptotic activity upon live cortical neurons grown in a culture system.Methods: Cortical neurons of fetal rats (16 tol8 days) were cultured in vitro. and sugar free Earle's solution were used to replicate the ischemiainjury model. After the ischemia stage the incubation solution was replaced with complete medium to simulate the reperfusion period. Cell viability was determined by 3- (4, 5-dimethylthialzol-2-yl) -2-5-diphenyl-tetrazolium bromide (MTT). Cell lysis was quantified by assay of lactate dehydrogenase (LDH) released into the culture medium. Cell death was also evaluated morphologically by phase-contrast light microscopy '2'. LDH leakage, hydrogen peroxide (H2O2), malondialdelyde (MDA) production and the intracellular levels of superoxide dismutase (SOD) and glutathione-peroxidase (GSH-px) were assessed by colormetric microassay. We also studied the apoptotic rate of the cortical neurons by flow cytometry. The mRNA levels of the apoptosis related genes bcl-2 and bax of the cortical neurons injured by oxygen-glucose deprivation were evaluated by reverse transcription polymerase chain reaction (RT-PCR).Results: Acetylpuerarin treatment (1. 6 X 10"6mol/L , 4X10"7mol/I^ 1X10"7 mol/L) significantly reduced LDH leakage, H2O2, MDA production and increased the cell viability and SOD, GSH-px levels in cortical neurons subjected to oxygen-glucose deprivation. The apoptotic rates of the neurons were also decreased by different levels. The RT-PCR results showed that acetylpuerarin can decrease the mRNA level of bax and increase the mRNA level of bcl-2 of the injured neurons.Conclusion: Collectively, these results indicated that acetylpuerarin strongly protect primary cultured neurons against oxygen-glucose deprivation-induced oxidative stress. It can also inhibit the apoptosis of the injured cortical neurons by increasing the mRNA level of bcl-2 and decreasing the mRNA level of bax. This suggested that acetylpuerarin may have a broad prospect in the therary of ischemic cerebral diseases.
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