p38 MAPK信号通路在小胶质细胞激活介导多巴胺能神经元变性中的作用研究

Role of p38 mitogen-activated protein kinase in activated microglia-mediated the degeneration of dopaminergic neurons

目的:研究p38丝裂原激活蛋白激酶(p38MAPK)在脂多糖(LPS)诱导小胶质细胞激活介导多巴胺(DA)能神经元变性中的作用。方法:脑立体定位注射LPS于大鼠脑黑质,Western blot印记法检测不同时间点(0、0.5h、1h、6h、12h)黑质p38磷酸化水平。酪氨酸羟化酶(Tyrosine hydroxylase,TH)免疫组织化学染色观察蛋白激酶(MAPK)特异性抑制剂SB203580预处理后LPS对DA能神经元变性的影响。结果:黑质注射LPS后,Western blot结果显示p38MAPK总体蛋白水平在各组均存在表达,无显著性差异(P>0.05),而其磷酸化p-p38MAPK却发生了明显变化。正常对照组和PBS注射侧几乎无p-p38的表达,LPS注射后30min,p-p38即有少量的表达;1h表达量增加;6h表达量达高峰;12h后表达量逐渐下降。与PBS对照侧相比,LPS注入黑质导致TH阳性细胞数下降至38%;SB203580预处理可以显著增加TH+细胞数达63%(P<0.05)。结论:p38MAPK信号通路参与了LPS诱导小胶质细胞激活介导DA能神经元变性,可通过阻断信号通路来减轻LPS诱导DA能神经元变性,为PD治疗提供新的思路。

Objective： To study the role of p38 mitogen-activated protein kinase（p38MAPK） on the degeneration of dopaminergic neurons induced by intranigral injection of Lipopolysaecharide （LPS）. Methods： LPS was stereotaxically injected into substantia nigra（SN）, p38phosphorylation levels at different survival times（0,0.5h, 1h,6h, 12h）were determined by Western-blot. The effect of LPS on the s ubstantia nigral DA neurons after specific inhibitor SB203580 pretreatment was observed by using（Tyrosine hydroxylase,TH ） immnohistochernical staining. Results： Western blot analysis revealed that there was no significant difference of Total p38MAPK in all groups. Level of phosphorylation of p38MAPK （p-p38） was a little upregulated in the ipsilateral SN as early as 30min after LPS and increased at lh. It reached the maximal level at 6h and returned to the basal level at 12h. Compared with PBS control side, TH positive neurons in the SN decreased by 68%, TH-positive neurons in the SN precondhioned by specific inhibitor SB203580 increased significantly. Conclusions： p38MAPK plays an important role in the activation of microglia by LPS and inhibition of the signal transduction pathway may consequently be an effective approach to decrease the degeneration of DA neurons by I.PS for the treatment of PD.