人参皂苷Rb1减轻Aβ_(25～35)所致新生神经细胞损伤

Ginsenoside Rb1 alleviets the neonatal rat neural cells damage induced by Aβ_(25～35)

目的研究β-淀粉样蛋白（Aβ）诱导新生大鼠神经细胞中蛋白激酶/蛋白磷酸酯酶系统失衡及人参皂苷Rb1对此作用的干预效应。方法从新生大鼠海马分离神经干细胞（NSCs）体外培养,诱导分化7 d后收获新生神经细胞,分3组：Aβ25~35组的培养基中加入20μmol/L Aβ25~35处理12 h;Rb1＋Aβ25~35组先在含10μmol/L Rb1的培养基中预处理24 h后,再用20μmol/L Aβ25~35处理12 h;对照组不加任何其他处理因素。RT-PCR和免疫细胞化学法检测各组新生神经元的蛋白激酶/蛋白磷酸酯酶和磷酸化Tau蛋白的表达。结果Aβ25~35处理组与对照组相比,糖原合成酶激酶-3β（GSK-3β）和细胞周期蛋白依赖性激酶5（CDK-5）的mRNA表达增加,蛋白磷酸酶2A（PP2A）的mRNA表达减少;荧光显微镜下,活化型GSK-3β（pY279,216）表达增加,PP2A表达降低;微管相关蛋白Tau（pS396）和Tau（pS262）的阳性细胞率明显增高。Rb1预处理可以显著降低Aβ25~35引起的上述蛋白激酶/蛋白磷酸酯酶和Tau改变。结论Aβ25~35诱导体外分化的新生大鼠神经细胞的蛋白激酶/蛋白磷酸酯酶系统失衡和Tau蛋白过度磷酸化,人参皂苷Rb1可减轻Aβ25~35引起的上述作用。

Objective To explore the protein kinase/protein phosphatase imbalance induced by amyloid β（Aβ） and to observe the intervention role of ginsenoside Rb1 in neonatal rat neural cells.Methods The neural stem cells（NSCs） were prepared after isolation from the newborn rat hippocampus and cultured.After 7 days of induction the NSCs differentiated into neural cells were randomly divided into three groups： Aβ25～35 group was treated with 20 μmol/L Aβ25～35 for 12 h;Rb1＋Aβ25～35 group was preconditioned with 10 μmol/L Rb1 for 24 h and then treated with 20 μmol/L Aβ25～35 for 12 h;control group was given nothing else.RT-PCR and immunofluorescence cytochemistry were used to detect the expression of protein kinase/protein phosphatase and tau.Results Compared with control group,in Aβ25～35 group glycogen synthase kinase 3β（GSK-3β） and cyclin dependent kinase 5（CDK-5） mRNA were higher,protein phosphatase 2A（PP2A） mRNA was lower;the expression of GSK-3β（pY279,216） was higher and PP2A was lower as shown by fluorescence microscope;the positive cell rates of microtubule associated protein Tau（pS396） and Tau（pS262） were higher（P0.05）.Rb1 pretreatment can depress the changes of phosphotase/phosphorylase and tau mentioned above induced by Aβ25～35.Conclusion Aβ25～35 induces phosphotase/phosphorylase imbalance and tau hyperphosphorylation in neonatal neural cells which can be depressed by Rb1.