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目的探讨脑室内注入EphB2-Fc融合蛋白对大脑皮层梗死后内源性神经干细胞活化的影响。方法采用易卒中型肾血管性高血压大鼠,建立大脑中动脉闭塞模型(MCAO),并将其随机分成:(1)假手术组,(2)脑梗死组,(3)梗死+IgG-Fc组,(4)梗死+EphB2-Fc组,每组24只。MCAO术后第4天,EphB2-Fc组大鼠经侧脑室注入20μl浓度为200μg/m l的EphB2-Fc融合蛋白,IgG-Fc组大鼠注入等量等浓度的IgG-Fc。MCAO术后第1和第4周,将各组大鼠处死取脑,用免疫组化和原位杂交检测各组大鼠不同时点梗死侧EphB2及其mRNA、巢蛋白(nestin)和多聚唾液酸-神经细胞黏附分子(PSA-NCAM)表达,W estern蛋白印迹检测各组大鼠不同时点梗死侧EphB2和nestin蛋白量的变化。结果MCAO术后1周,脑梗死组梗死侧大脑皮层和侧脑室下区EphB2及其mRNA的表达低于假手术组,梗死+EphB2-Fc组高于梗死+IgG-Fc组(均P<0.05),脑梗死组与梗死+IgG-Fc组间差异无统计学意义(P>0.05);脑梗死组梗死侧侧脑室下区nestin、PSA-NCAM的表达高于假手术组,梗死+EphB2-Fc组高于梗死+IgG-Fc组(均P<0.05),并可见PSA-NCAM阳性细胞沿胼胝体向梗死灶迁移。MCAO术后4周,各组间梗死侧EphB2及其mRNA表达水平差异无统计学意义(均P>0.05),各组脑梗死大鼠梗死侧nestin、PSA-NCAM表达水平下降,各组间nestin表达水平差异无统计学意义,但脑梗死组PSA-NCAM表达水平仍高于假手术组。结论阻断内源性EphB2的活化可促进实验性大脑皮层梗死后脑室下区神经干细胞的增殖和迁移。
Objective To investigate the effect of intraventricular injection of EphB2-Fc fusion protein on the activation of endogenous neural stem cells after cerebral cortex infarction. Methods The middle cerebral artery occlusion model (MCAO) was established in rats with stroke-induced renovascular hypertension and then randomly divided into three groups: sham operation group, (2) cerebral infarction group, (3) infarct + IgG- Fc group, (4) infarction + EphB2-Fc group, 24 rats in each group. On the fourth day after MCAO, rats in EphB2-Fc group were injected with 20μl of EphB2-Fc fusion protein at a concentration of 200μg / ml into lateral ventricle. IgG-Fc rats were injected with equal volume of IgG-Fc. At 1 and 4 weeks after MCAO, rats in each group were killed and brain was taken out. EphB2 and its mRNA, nestin and poly Sialic acid-nerve cell adhesion molecule (PSA-NCAM) expression was detected by Western blotting. The protein levels of EphB2 and nestin in infarct side of each group were detected by Western blotting. Results The expression of EphB2 and its mRNA in the infarction side of the cerebral cortex and the subventricular zone in the infarcted group was lower than that in the sham operation group at 1 week after MCAO. The infarction + EphB2-Fc group was higher than the infarction + IgG-Fc group (P <0.05 (P> 0.05). The expression of nestin and PSA-NCAM in the subventricular zone of cerebral infarction group was higher than that in the sham operation group and infarction + EphB2- Fc group was higher than that in infarcted + IgG-Fc group (all P <0.05), and PSA-NCAM positive cells migrated toward the infarct along the corpus callosum. At 4 weeks after MCAO, there was no significant difference of EphB2 and its mRNA expression in infarction between the groups (all P> 0.05). The expression of nestin and PSA-NCAM in infarction side of each group decreased, while nestin The expression level of PSA-NCAM in cerebral infarction group was still higher than that in sham operation group. Conclusion Blocking the activation of endogenous EphB2 can promote the proliferation and migration of neural stem cells in the subventricular zone after experimental cerebral cortex infarction.