视神经损伤后发生非折叠蛋白反应的超微证据

目的:探索视神经损伤后视网膜节细胞(retinal ganglion cell,RGC)及其纤维渐进性死亡机制。方法:利用包埋前与包埋后免疫金细胞化学标记技术结合电镜观察研究大鼠(n=15)视神经钳夹损伤后RGC与视神经干少突胶质细胞内的非折叠蛋白反应(unfolding protein response,UPR)。结果:视神经钳夹后,需肌醇酶1(inositol requiring enzyme 1,IRE1)在RGC与少突胶质细胞内胶体金标记数目增多,在钳夹0.5d后RGC内即有显著地增加(18.4±5.1～30.4±7.2个,P<0.05),随损伤时间延长,增多更为明显,在钳夹3d后达高峰(48.5±9.7个),IRE1在视神经干上的少突胶质细胞内增多时程变化与在RGC内相似。IRE1在RGC与少突胶质细胞内胶体金标记颗粒分布部位距离ER管腔距离增加为特征,在钳夹0.5d内神经干少突胶质细胞以及视网膜RGC内均表现非常明显的距离增加。结论:视神经钳夹导致损伤细胞触发UPR,UPR可能参与视神经损伤后RGC及其纤维渐进性死亡机制。

Electron microscopic localization of IRE1 on the retinal ganglion cells and oligodendrocytes on retinal nerve of the rat after optic nerve crushing

AIM:To explore the role of unfolding protein response(UPR) on the mechanism for delayed retinal ganglion cell(RGC) and its axonal degenerating after injury at ultrastructure level. ·METHODS:Using pre-embedding and post-embedding immunogold cytochemistry,we study the distribution of immunogold particles for Inositol requiring enzyme 1(IRE1) in RGCs of the retina and oligodendrocytes of the optic nerves after optic nerve crushing. ·RESULTS:Immunogold particles for IRE1 could be identified in RGCs of the retina and oligodendrocytes of the optic nerves. IRE1 immunogold particles were found in close apposition to the endoplasmic reticulum (ER) and in the cavity of ER in the control group,and some IRE1 immunogold particles were found distance to ER and the number of IRE1 immunogold particles increased after optic nerve crushing. Half a day after optic nerve crushing,the immunogold particles-ER distance and the number were found increased compared with that of control group (from 18.4±5.1 to 30.4±7.2,P<0.05),and 3 days after optic nerve crushing,to the highest compared with that of control group (48.5±9.7,P<0.01). ·CONCLUSION:These findings provide a morphological basis for the possibility that the UPR may contribute to the mechanism for delayed RGC and its axonal degenerating after injury.