Remodeling of synaptic structures in the motor cortex following spinal cord injury
Remodeling of synaptic structures in the motor cortex following spinal cord injury
复制标题
DOI：
10.1016/j.expneurol.2005.12.010
复制
发表时间：
2006-04-01
影响因子：
5.3
通讯作者：
Bregman, BS
中科院分区：
文献类型：
--
作者：
Kim, BG;Dai, HN;Bregman, BS
脊髓损伤（SCI）后，包括运动皮质在内的运动系统的多个水平发生结构重组，这种重构可能是运动功能恢复的基础。本研究确定SCI是否导致运动皮层突触结构的重塑。在共聚焦显微镜下观察大鼠运动皮层树突棘的形态和密度，并在C4水平进行半横断损伤后进行形态学分析。脊柱密度在7天时降低，到28天时部分恢复。脊柱头直径以层特异性方式显著增加。SCI导致更长的脊柱比例更高，特别是在28天时，导致平均脊柱长度增加约10%。此外，在SCI后更频繁地观察到丝状伪足样长树突状突起，这表明突触发生事件增加。这种脊柱重塑伴随着多聚唾液酸化神经细胞粘附分子的表达增加，这减弱了突触前膜和突触后膜之间的粘附，在运动皮层损伤后3天至2周，这表明在重塑过程中突触粘附减少。这些结果表明脊髓损伤后运动皮层的棘密度和形态学的时间依赖性变化。这种突触重塑似乎以从几天到几周的时间尺度进行。树突棘的延长可能表明脊髓损伤后运动皮层中的突触连接的重组模式更不成熟和更易改变。(C)2006年爱思唯尔公司All rights reserved.
After spinal cord injury (SCI), structural reorganization occurs at multiple levels of the motor system including the motor cortex, and this remodeling may underlie recovery of motor function. The present study determined whether SCI leads to a remodeling of synaptic structures in the motor cortex. Dendritic spines in the rat motor cortex were visualized by confocal microscopy in fixed slices, and their density and morphology were analyzed after an overhemisection injury at C4 level. Spine density decreased at 7 days and partially recovered by 28 days. Spine head diameter significantly increased in a layer-specific manner. SCI led to a higher proportion of longer spines especially at 28 days, resulting in a roughly 10% increase in mean spine length. In addition, filopodium-like long dendritic protrusions were more frequently observed after SCI, suggesting an increase in synaptogenic events. This spine remodeling was accompanied by increased expression of polysialylated neural cell adhesion molecule, which attenuates adhesion between the pre- and postsynaptic membranes, in the motor cortex from as early as 3 days to 2 weeks after injury, suggesting a decrease in synaptic adhesion during the remodeling process. These results demonstrate time-dependent changes in spine density and morphology in the motor cortex following SCI. This synaptic remodeling seems to proceed with a time scale ranging from days to weeks. Elongation of dendritic spines may indicate a more immature and modifiable pattern of synaptic connectivity in the motor cortex being reorganized following SCI. (C) 2006 Elsevier Inc. All rights reserved.