p38MAPK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

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。

Role of p38mitogen-activated protein kinase in activated microglia-mediated the degeneration of dopaminergic neurons

Objective :To study the role of p38 mitogen-activated protein kinase(p38 MAPK) onthe degeneration of dopaminergicneurons induced byintranigral injection of Lipopolysaccharide (LPS) .Methods :LPS was stereotaxicallyinjectedinto sub-stantia nigra(SN) .p38phosphorylationlevels at different survival ti mes(0、0 .5h、1h、6h、12h)were determined by Western-blot .The effect of LPS onthe substantia nigral DAneurons after specific inhibitor SB203580 pretreat ment was observed byusing(Tyrosine hydroxylase ,TH)i mmunohistochemical staining .Results :Western blot analysis revealed that there wasno significant difference of Total p38 MAPKin all groups .Level of phosphorylation of p38 MAPK(p-p38) was a little up-regulated in the ipsilateral SNas early as 30 min after LPS and increased at 1h.It reached the maxi mal level at 6h and re-turned to the basal level at 12h.Compared with PBS control side , TH-positive neurons inthe SNdecreased by 68 %, TH-positive neurons in the SN preconditioned by specific inhibitor SB203580 increased significantly .Conclusions :p38 MAPKplays ani mportant role in the activation of microglia by LPS andinhibition of the signal transduction pathway may conse-quently be an effective approach to decrease the degeneration of DA neurons by LPS for the treat ment of PD.