Posmantur R M, Kampfl A, Liu S J, Heck K, Taft W C, Clifton G L, Hayes R L
Department of Neurosurgery, University of Texas Houston 77030, USA.
J Neuropathol Exp Neurol. 1996 Jan;55(1):68-80. doi: 10.1097/00005072-199601000-00007.
Semiquantitative Western blot analyses have shown that traumatic brain injury (TBI) can produce significant loss of cytoskeletal proteins (neurofilament 68 [NF68], neurofilament 200 [NF200] and microtubule associated protein 2 [MAP2]) possibly by calpain-mediated proteolysis. Thus, we employed immunofluorescence (light and confocal microscopy) to study the histopathological correlates of acute neurofilament and MAP2 protein decreases observed 3 hours following unilateral cortical injury in rats. TBI induced dramatic alterations in NF68, NF200, and MAP2 immunolabeling in dendrites within and beyond contusion sites ipsilateral and contralateral to the injury site. Marked changes in immunolabeling were associated with but not exclusively restricted to regions of dark shrunken neurons labeled by hematoxylin and eosin staining, a morphopathological response to injury suggesting impending cell death. Light microscopic studies of NF200 immunofluorescence revealed a prominent fragmented appearance of apical dendrites of pyramidal neurons within layers 3 and 5, as well as a loss of fine dendritic arborization within layer 1. Confocal microscopy detected varying degrees of NF200 disassembly associated with these areas of neurofilament fragmentation. Light microscopic studies of NF68 immunofluorescence detected subtle and less severe structural changes including smaller breaks and focal vacuolization of apical dendrites. Light microscopic immunofluorescence of MAP2 revealed changes similar to those seen for NF200. Acute axonal alterations detected with NF68 were minimal compared to immunofluorescence changes seen in dendritic regions. Therefore, preferential dendritic cytoskeletal derangements may be an early morphological feature of experimental traumatic brain injury in vivo. In addition, these cytoskeletal derangements may not be exclusively restricted to sites of contusion and cell death.
半定量蛋白质免疫印迹分析表明，创伤性脑损伤（TBI）可能通过钙蛋白酶介导的蛋白水解作用，导致细胞骨架蛋白（神经丝68 [NF68]、神经丝200 [NF200]和微管相关蛋白2 [MAP2]）显著丢失。因此，我们采用免疫荧光法（光学显微镜和共聚焦显微镜）研究大鼠单侧皮质损伤3小时后观察到的急性神经丝和MAP2蛋白减少的组织病理学相关性。TBI导致损伤部位同侧和对侧挫伤部位内外树突中NF68、NF200和MAP2免疫标记发生显著改变。免疫标记的显著变化与苏木精和伊红染色标记的深色萎缩神经元区域相关，但不仅限于此，这种损伤的形态病理学反应提示即将发生细胞死亡。对NF200免疫荧光的光学显微镜研究显示，第3层和第5层锥体细胞的顶端树突出现明显的碎片化外观，以及第1层内精细树突分支的丧失。共聚焦显微镜检测到与这些神经丝碎片化区域相关的不同程度的NF200解聚。对NF68免疫荧光的光学显微镜研究检测到细微且不太严重的结构变化，包括顶端树突的较小断裂和局灶性空泡化。MAP2的光学显微镜免疫荧光显示出与NF200相似的变化。与树突区域观察到的免疫荧光变化相比，用NF68检测到的急性轴突改变最小。因此，优先发生的树突细胞骨架紊乱可能是实验性创伤性脑损伤体内的早期形态学特征。此外，这些细胞骨架紊乱可能不仅限于挫伤和细胞死亡部位。
