Molecular changes at the posterior horn of spinal cord resulting from spinal root avulsion

本研究的目的是用免疫组织化学方法显示神经根性撕脱伤后背角的急性到亚急性分子事件。撕脱伤后24小时，HSP27在损伤的胶状质中选择性积聚。双重免疫荧光和免疫电子显微镜证实了HSP27在胶状质内星形胶质细胞中的定位。7d后，Hsp27的表达模式由胶质型转变为点状。免疫电子显微镜显示，亚急性期的点状图案与星形细胞突起的远端部分相对应。我们认为，HSP27是显示撕脱伤后背角损伤的有用标记物。接下来，我们研究了牵引损伤后从中枢神经系统-三叉神经节连接到断裂的背根的时间分子变化。在背侧断裂伤后28天，在背根断裂处，GFAP阳性结构显示出从中心-外周交界处到外周残端的相当直线。28d时，背根断裂处已出现胶质细胞源性神经营养因子免疫反应阳性，呈突起状，与GFAP阳性结构密切相关。因此，我们得出结论，星形胶质细胞显示出一种独特的能力，可以将它们的突起延伸到树桩上。这种能力可能为未来临床实验中轴突再生的研究提供新的媒介。

The aim of this study was to demonstrate acute to subacute molecular episodes in the dorsal horn following root avulsion using immunohistochemical methods. Hsp27 was accumulated selectively in the injured substantia gelatinosa 24 hours after avulsion injury. The localization of Hsp27 in astrocytes within the substantia gelatinosa was confirmed by the double immunofluorescence and by immunoelectron microscopy for Hsp27. The pattern of Hsp27 expression subsequently changed from glial pattern to punctate pattern by 7 days. Immunoelectron microscopy revealed that the punctate pattern in the subacute stage corresponded to distal parts of the astrocytic processes. We conclude that Hsp27 is a useful marker for demonstrating dorsal horn lesions following avulsion. Next, we examined temporal molecular alterations from the CNS-PNS junction to the ruptured dorsal root after traction injury. At 28 days after dorsal rupture injury, GFAP-positive structures were identified showing rather straight lines from the centro-peripheral junction toward the peripheral stump in the ruptured dorsal root. Glial cell line-derived neurotrophic factor immunoreactivity had appeared showing a process-like profile on the ruptured dorsal root by 28 days, and it was closely related with GFAP-positive structures. We therefore conclude that the astrocytes show a unique ability to extend their processes toward the stump. This ability may provide a new medium for the study of axonal regeneration in future clinical experiments.