Posmantur R, Hayes R L, Dixon C E, Taft W C
Department of Neurosurgery, University of Texas Houston Health Science Center, Houston.
J Neurotrauma. 1994 Oct;11(5):533-45. doi: 10.1089/neu.1994.11.533.
We have examined the effect of lateral cortical impact injury on the levels of axonal cytoskeletal proteins in adult rats. Traumatic brain injury (TBI) causes a significant decrease in the protein levels of two prominent neurofilament (NF) proteins, NF68 and NF200. We employed quantitative immunoreactivity measurements on Western blots to examine NF68 and NF200 levels in homogenates of hippocampal and cortical tissue taken at several intervals postinjury. Sham injury had no effect on NF protein levels. However, injury was associated with a significant loss of NF68, restricted to the cortex ipsilateral to the injury site. NF68 loss was detectable as early as 3 h and lasted at least 2 weeks postinjury. Similarly, TBI induced a decrease in NF200 protein, although losses were observed both ipsilateral and contralateral to the injury site. No loss of NF68 or NF200 protein was detected in hippocampal samples obtained from the same injured animals. An increase in the presence of lower molecular weight (MW) NF68 immunopositive bands was associated with the decrease of NF68 in the ipsilateral cortex. This NF68 antigenicity pattern suggests the production of NF68 breakdown products caused by the pathologic activation of neuronal proteases, such as calpain. Putative NF68 breakdown products increase significantly until 1 day postinjury, suggesting that NF degradation may be ongoing until that time and indicating that a potential therapeutic window may exist within the first 24 h postinjury. In summary, these data identify specific biochemical alterations of the neuronal cytoskeleton following TBI and lay a foundation for further investigation of postinjury cytoskeletal changes in neuronal processes.
我们研究了成年大鼠外侧皮质撞击损伤对轴突细胞骨架蛋白水平的影响。创伤性脑损伤（TBI）导致两种主要神经丝（NF）蛋白NF68和NF200的蛋白水平显著降低。我们采用蛋白质印迹法进行定量免疫反应性测量，以检测损伤后不同时间点采集的海马和皮质组织匀浆中NF68和NF200的水平。假损伤对NF蛋白水平无影响。然而，损伤与NF68的显著丢失有关，且仅限于损伤部位同侧的皮质。损伤后3小时即可检测到NF68丢失，并持续至少2周。同样，TBI导致NF200蛋白减少，尽管在损伤部位同侧和对侧均观察到了丢失。在从同一损伤动物获取的海马样本中未检测到NF68或NF200蛋白丢失。较低分子量（MW）的NF68免疫阳性条带的出现增加与同侧皮质中NF68的减少相关。这种NF68抗原性模式提示由神经元蛋白酶（如钙蛋白酶）的病理性激活导致了NF68降解产物的产生。假定的NF68降解产物在损伤后1天显著增加，表明NF降解可能一直持续到那时，这也表明在损伤后24小时内可能存在潜在的治疗窗口。总之，这些数据确定了TBI后神经元细胞骨架的特定生化改变，为进一步研究损伤后神经元突起中细胞骨架的变化奠定了基础。
