人参皂苷Rb1对脑缺血大鼠GFAP及脑血流的影响

Effect of Ginsenoside Rb1 on GFAP/Regional Cerebral Blood Flow After Photochemical Ischemia in Rats

目的：采用光化学诱导局部脑缺血模型,研究人参皂苷Rb1（ginsenosideRb1,GRb1）对大鼠右侧脑皮质区神经胶质原纤维酸性蛋白（glial fibrillary acidic protein,GFAP）及局部脑血流量（regional cerebral blood flow,rCBF）的影响及可能的机制。方法：48只SD大鼠随机分为模型组,假手术组,GRb1高剂量组（100 mg·kg^-1）,中剂量组（50 mg·kg^-1）,低剂量组（25 mg·kg^-1）,尼莫地平组（1 mg·kg^-1）,每组8只。用激光多普勒血流监测仪测定缺血后24 h右侧脑皮质区r CBF的改变。用实时荧光定量PCR法（Real-time PCR）检测GFAP mRNA的表达,用免疫组化和蛋白免疫印迹法（Western bolt）检测GFAP的表达。应用神经行为学评分评价大鼠神经功能症状。结果：与假手术组比较,模型组r CBF明显下降（P〈0.01）;与模型组比较,高剂量GRb1组神经功能缺损程度降低（P〈0.05）,GRb1各组r CBF明显增加（P〈0.05）;模型组GFAP mRNA和蛋白表达较假手术组明显增加（P〈0.05）,GRb1组GFAP阳性细胞表达较模型组明显增加（P〈0.05）,其中以高剂量GRb1组GFAP表达增加明显（P〈0.01）;GRb1高剂量组与尼莫地平组间差异无统计学意义。结论：在脑缺血急性期GRb1可增加局部r CBF,并促进GFAP的表达,稳定星形胶质细胞形态,保护缺血半暗带细胞。

Objective： To investigate the effect of ginsenoside Rb1（ GRb1） on glial fibrillary acidic protein（ GFAP） and regional cerebral blood flow（ r CBF） in cortex of rats and explore its possible mechanism by using photochemically induced local cerebral ischemia model. Method： Forty-eight SD rats were randomly divided into model group, sham operation group, GRb1 high dose group（ 100 mg ·kg-（-1））, medium dose group（ 50 mg·kg-（-1））,and low dose group（ 25 mg·kg-（-1））,as well as nimodipine group（ 1 mg·kg-（-1））,with 8 rats in each group. The changes of regional cerebral blood flow in the right cerebral cortex were measured by laser Doppler flowmetry after ischemia for 24 h. The expression of GFAP mRNA was detected with Real-time PCR method,while Western blot and immunohistochemistry method were used to detect the expression of GFAP protein. Neurological function of rats was detected by using the neurological behavior score. Result： As compared with the sham operation group,the cerebral blood flow was decreased significantly in the model group（ P〈0. 01）. As compared to the model group,the neurological function deficits were decreased in high dose GRb1 group（ P〈0. 05） and the cerebral blood flow was increased significantly in GRb1 groups（ P〈0. 05）. The expression levels of GFAP mRNA and protein in model group were significantly higher than those in sham operation group（ P〈0. 05）. As compared with the model group,GRb1 groups can respectively increase the positive expression of GFAP（ P〈0. 05）,especially in high dose group（ P〈0. 01）; there was no significant difference between GRb1 high dose group and nimodipine group. Conclusion： GRb1 can increase regional cerebral blood flow,up-regulate the expression of GFAP,protect the morphology of astrocytes,and reduce the damage of ischemic penumbra neurons in acute cerebral ischemia stage.