Effects Of Matrine Against Focal Cerebral Ischemic Injury In Rats And Its Protective Mechanisms Of Astrocyte

Aim:To investigate the effects of matrine against focal cerebral ischemic injury in rats and its protective mechanisms of astrocyte.Methods:Permanent middle cerebral artery occlusion(pMCAO) model was induced by using intraluminal filament technique in rats.Matrine(12.5-50 mg/kg) was injected intravenously(ⅳ) 10 min after the onset of ischemia.The neuroprotection of matrine was analyzed by scoring neurological deficits,assessing brain infarction volume with 2,3,5-triphenyltetrazolium chloride(TTC) and determining the brain water content 24 h after ischemia.The effect of matrine on cerebral blood flow was observed with relative cerebral blood flow(rCBF).Primary astrocyte was exposed to a paradigm of ischemic insult by using oxygen-glucose deprivation(OGD).Immunofluorescence was employed to determine the nuclear translocation of NF-κB and the expression of GFAP.Real Time PCR was used to measure the expression of p53 mRNA.Results:Matrine(12.5-50 mg/kg) diminished infarction volume in a dose-dependent manner(P＜0.01) administered 10 min following permanent focal ischemia in rats. Matrine also significantly ameliorated motor behavior deficits and decreased the brain water content.Matrine 50 mg/kg has no effect on rCBF.Number of GFAP-positive cells in the ischemic cortex was significantly inceased in matrine-treated rats at 12 h after ischemia(P＜0.01),compared with model rats.Number of GFAP-positive cells was markedly deceased 6 h after OGD(P＜0.01).In contrast,matrine obviously increased the number of GFAP-positive cells(P＜0.05,P＜0.01).In addition,LDH showed that OGD induced the increase of LDH leakage in cultured astrocyte as early as 1h,gradually increased;and reached its peak at 12 h(P＜0.05,P＜0.01).Matrine(50-200μM) reduced LDH leakage in a dose-dependent manner 6 h after OGD(P＜0.01).Immunofluorescence revealed that a significant increase in the nuclear translocation of NF-κB was observed as early as 3h(P＜0.01) after OGD,and peaked at 6-12 h(P＜0.01).Matrine strongly inhibited NF-κB nuclear translocation 6 h after OGD(P＜0.05,P＜0.01).Furthermore, consistent with the peak time of NF-κB nuclear translocation,the expression of NF-κB target gene p53 mRNA was up-regulated 6 h after OGD(P＜0.01),and matrine dramaticly down-regulated the expression of p53 mRNA(P＜0.05,P＜0.01).Conclusion:The current findings provide the first evidence that matrine has neuroprotective activity on cerebral ischemic injury,and this effect may be associated with its blocking the activtion of NF-κB and inhibiting proapoptotic target gene of NF-κB p53 in astrocyte,and then protecting astrocyte against iniury induced by cerebral ischemia.