Autophagy Is Activated in Injured Neurons and Inhibited by Methylprednisolone After Experimental Spinal Cord Injury
Autophagy Is Activated in Injured Neurons and Inhibited by Methylprednisolone After Experimental Spinal Cord Injury
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DOI：
10.1097/brs.0b013e318221e859
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发表时间：
2012-03-15
期刊：
影响因子：
3
通讯作者：
Chiu, Wen-Ta
中科院分区：
文献类型：
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作者：
Chen, Hsien-Chih;Fong, Tsorng-Harn;Chiu, Wen-Ta
研究设计.实验，对照试验，动物研究。评估大鼠脊髓损伤（SCI）后自噬的表达，并研究甲基强的松龙治疗对自噬的影响。尽管SCI诱导细胞坏死和凋亡是显而易见的，但其与自噬的关系尚不确定。自噬与神经系统的各种病理状态有关，如神经退行性疾病、脑缺血和创伤性脑损伤。到目前为止，通过透射电镜（TEM）和自噬标志物微管相关蛋白轻链3（LC 3）观察，SCI后神经组织中未见自噬表达。66只Sprague-Dawley大鼠用于实验程序。在脊髓损伤组中，在T9进行椎板切除术，然后进行脊髓撞击器挫伤。在假手术组中，仅进行椎板切除术而不进行挫伤。我们使用Western blot分析SCI后2小时、4小时、1天、3天和7天的LC 3。我们还研究了甲基强的松龙对挫伤脊髓自噬表达的影响。应用免疫荧光双标记法和透射电镜观察脊髓损伤后细胞定位和超微结构的变化。使用非参数Kruskal-Wallis检验分析来自蛋白质印迹的数据，P < 0.05被认为是显著的。脊髓损伤后2 h，LC 3水平显著升高，随后下降，直至1周。甲基强的松龙在SCI后2小时降低LC 3表达。LC 3阳性细胞与神经元胞核共定位，但不与胶质细胞酸性蛋白共定位。透射电镜证实了脊髓损伤后自噬的存在和自噬性细胞死亡的进程。本研究通过观察脊髓挫伤后神经元自噬表达的增强及甲基强的松龙的抑制作用，揭示了脊髓损伤后自噬表达的特点，提示自噬细胞死亡可能在脊髓损伤后神经元死亡中起一定作用。
Study Design. Experimental, controlled trial, animal study.Objective. To assess autophagy expression after rat spinal cord injury (SCI) and investigate the effect of methylprednisolone treatment on autophagy.Summary of Background Data. Although it is evident that SCI induces necrosis and apoptosis, its relationship to autophagy is uncertain. Autophagy is implicated in various pathological states in the nervous system, such as neurodegenerative diseases, cerebral ischemia, and traumatic brain injury. Up to now, no autophagy expression was evidenced by transmission electronic microscope (TEM) and the autophagy marker, microtubule-associated protein light chain 3 (LC3) in neural tissue after SCI.Methods. Sixty-six Sprague-Dawley rats were used for the experimental procedure. In the SCI group, laminectomy at T9 were performed, followed by impactor contusion of the spinal cord. In the sham group, only a laminectomy was performed without contusion. We used Western blot to analyze LC3 at 2 hours, 4 hours, 1 day, 3 days, and 7 days after SCI. We also investigated the effect of methylprednisolone on autophagy expression of contused spinal cord. Cellular localization and ultrastructural changes after spinal cord injury were compared with those sham-operated rats using immunofluorescent double labeling and TEM, respectively. Data from the Western blot were analyzed using a nonparametric Kruskal-Wallis test with P < 0.05 being considered significant.Results. We detected significantly elevated level of LC3 2 hours after SCI, and then the level declined until 1 week after SCI. Methylprednisolone decreased LC3 expression at 2 hours after SCI. LC3 positive cells were colocalized with neuronal nuclei, but not with glial fibrillary acidic protein. The existence of autophagy and progress of autophagic cell death after SCI were confirmed by TEM.Conclusion. Through observing the enhanced autophagy expression in neurons soon after contusion injury and the inhibitive effect of methylprednisolone treatment, this study demonstrates the characteristics of autophagy expression after SCI and suggests that autophagic cell death may play a role in neuronal death after spinal cord trauma.