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目的探讨星形胶质细胞(astrocyte,AS)对天冬氨酸特异性半胱氨酸蛋白酶(cysteinyl aspartate specific proteinase,caspase)介导β淀粉样蛋白(β-amyloid,Aβ)早期突触毒性作用的影响,以期为进一步研究与血管性痴呆(vascular dementia,Va D)的发病机制奠定基础。方法以原代培养大鼠海马纯神经元体系(NE-S)及混合培养体系(MIX-S,主要包含神经元及AS)为研究对象,各体系分为6组:对照组、caspase-8抑制剂组、caspase-9抑制剂组、Aβ处理组、caspase-8抑制剂预处理加Aβ组和caspase-9抑制剂预处理加Aβ组。免疫荧光检测各组近胞体10μm段树突中突触后密度蛋白(postsynaptic density-95,PSD95)表达量的变化。结果 1在NE-S与MIX-S中,与对照组相比,caspase-8抑制剂组、caspase-9抑制剂组PSD95的表达量均无明显差异,Aβ处理组PSD95的表达量均显著降低(P均<0.001)。2在NE-S中,与Aβ处理组相比,caspase-9抑制剂预处理加Aβ组PSD95的表达量显著回升至对照组水平,caspase-8抑制剂预处理加Aβ组则无显著改变;在MIX-S中的结果则相反,即caspase-8抑制剂预处理加Aβ组PSD95的表达量显著回升至对照组水平,而caspase-9抑制剂预处理加Aβ组则无显著改变。3MIX-S与NE-S两种培养系统间相比较,对照组间及Aβ处理组间PSD95的表达量均无显著差异,而caspase-8抑制剂预处理加Aβ组间及caspase-9抑制剂预处理加Aβ组间PSD95的表达量差异有显著性。结论在Aβ早期突触毒性作用中,AS参与caspase-8介导的死亡受体通路激活过程,且参与抑制神经元的线粒体通路。
Objective To investigate the effect of astrocyte on early synaptic toxicity of β-amyloid (Aβ) mediated by caspase-specific caspase In order to lay the foundation for the further study of the pathogenesis of vascular dementia (VaD). Methods Primary cultured rat hippocampal neuron system (NE-S) and mixed culture system (MIX-S, mainly containing neurons and AS) were divided into six groups: control group, caspase-8 Inhibitor group, caspase-9 inhibitor group, Aβ treatment group, caspase-8 inhibitor pretreatment plus Aβ group and caspase-9 inhibitor pretreatment plus Aβ group. Immunofluorescence was used to detect the expression of postsynaptic density-95 (PSD95) in 10 μm dendrites of each group. Results 1 Compared with the control group, the expression of PSD95 in caspase-8 inhibitor group and caspase-9 inhibitor group was not significantly different in NE-S and MIX-S groups, and the expression of PSD95 in Aβ group was significantly decreased (P <0.001). 2 In NE-S, the expression of PSD95 in caspase-9 inhibitor pretreatment plus Aβ group remarkably increased to the level of control group compared with that of Aβ treatment group, but no significant change was observed in caspase-8 inhibitor pretreatment group and Aβ group. In the MIX-S results, on the contrary, the expression of PSD95 in caspase-8 inhibitor pretreatment plus Aβ group significantly increased to the level of control group, while the caspase-9 inhibitor pretreatment plus Aβ group had no significant change. There was no significant difference in the expression of PSD95 between the control group and the Aβ-treated group when comparing the two culture systems of 3MIX-S and NE-S. However, there was no significant difference in the expression of PSD95 between caspase-8 inhibitor pretreatment and Aβ group and caspase-9 inhibitor There was a significant difference in the expression of PSD95 between pretreatment and Aβ group. Conclusions In the early synaptic toxicity of Aβ, AS participates in caspase-8 mediated activation of death receptor pathway and is involved in the inhibition of neuronal mitochondrial pathway.