Huang Si-Qin, Tang Cheng-Lin, Sun Shan-Quan, Yang Cheng, Xu Jin, Wang Ke-Jian, Lu Wei-Tian, Huang Juan, Zhuo Fei, Qiu Guo-Ping, Wu Xiu-Yu, Qi Wei
Traditional Chinese Medicine College, Chongqing Medical University, Chongqing, China; Institute of Neuroscience, Chongqing Medical University, Chongqing, China.
CNS Neurosci Ther. 2014 Jan;20(1):20-31. doi: 10.1111/cns.12155. Epub 2013 Aug 13.
Demyelination is one of the most important pathological factors of spinal cord injury. Oligodendrocyte apoptosis is involved in triggering demyelination. However, fewer reports on pathological changes and mechanism of demyelination have been presented from compressed spinal cord injury (CSCI). The relative effect of oligodendrocyte apoptosis on CSCI-induced demyelination and the mechanism of apoptosis remain unclear.
In this study, a custom-designed model of CSCI was used to determine whether or not demyelination and oligodendrocyte apoptosis occur after CSCI. The pathological changes in axonal myelinated fibers were investigated by osmic acid staining and transmission electron microscopy. Myelin basic protein (MBP), which is used in myelin formation in the central nervous system, was detected by immunofluorescence and Western blot assays. Oligodendrocyte apoptosis was revealed by in situ terminal-deoxytransferase-mediated dUTP nick-end labeling. To analyze the mechanism of oligodendrocyte apoptosis, we detected caspase-12 [a representative of endoplasmic reticulum (ER) stress], cytochrome c (an apoptotic factor and hallmark of mitochondria), and inhibitor of DNA binding 2 (Id2, an oligodendrocyte lineage gene) by immunofluorescence and Western blot assays.
The custom-designed model of CSCI was successfully established. The rats were spastic, paralyzed, and incontinent. The Basso, Beattie, and Bresnahan (BBB) locomotor rating scale scores were decreased as time passed. The compressed spinal cord slices were ischemic. Myelin sheaths became swollen and degenerative; these sheaths were broken down as time passed after CSCI. MBP expression was downregulated after CSCI and consistent with the degree of demyelination. Oligodendrocyte apoptosis occurred at 1 day after CSCI and increased as caspase-12 expression was enhanced and cytochrome c was released. Id2 was distributed widely in the white matter. Id2 expression increased with time after CSCI.
Demyelination occurred after CSCI and might be partly caused by oligodendrocyte apoptosis, which was positively correlated with ER-mitochondria interactions and enhanced Id2 expression after CSCI in rats.
脱髓鞘是脊髓损伤最重要的病理因素之一。少突胶质细胞凋亡参与引发脱髓鞘。然而，关于压缩性脊髓损伤（CSCI）的脱髓鞘病理变化及机制的报道较少。少突胶质细胞凋亡对CSCI诱导的脱髓鞘的相对影响以及凋亡机制仍不清楚。
在本研究中，使用定制设计的CSCI模型来确定CSCI后是否发生脱髓鞘和少突胶质细胞凋亡。通过锇酸染色和透射电子显微镜研究轴突有髓纤维的病理变化。通过免疫荧光和蛋白质印迹分析检测用于中枢神经系统髓鞘形成的髓鞘碱性蛋白（MBP）。通过原位末端脱氧核苷酸转移酶介导的dUTP缺口末端标记揭示少突胶质细胞凋亡。为了分析少突胶质细胞凋亡的机制，我们通过免疫荧光和蛋白质印迹分析检测了半胱天冬酶-12（内质网应激的代表）、细胞色素c（一种凋亡因子和线粒体标志）以及DNA结合抑制因子2（Id2，一种少突胶质细胞谱系基因）。
成功建立了定制设计的CSCI模型。大鼠出现痉挛、瘫痪和大小便失禁。随着时间的推移，Basso、Beattie和Bresnahan（BBB）运动评分量表得分降低。受压脊髓切片缺血。髓鞘肿胀并发生变性；CSCI后随着时间的推移这些髓鞘被破坏。CSCI后MBP表达下调，且与脱髓鞘程度一致。少突胶质细胞凋亡在CSCI后1天发生，并随着半胱天冬酶-12表达增强和细胞色素c释放而增加。Id2广泛分布于白质中。CSCI后Id2表达随时间增加。
CSCI后发生脱髓鞘，可能部分由少突胶质细胞凋亡引起，少突胶质细胞凋亡与内质网-线粒体相互作用呈正相关，且在大鼠CSCI后Id2表达增强。
