引用

创伤性轴突损伤(Traumatic axonal injury, TAI)是创伤性脑损伤(Traumatic brain injury, TBI)中常见的神经病理，以轴突原发损伤为特征。在这里，我们在雄性Thy1-eYFP-H转基因小鼠中产生了带有头部撞击加速度(IA)的TAI，其中特定群体的神经元及其轴突用黄色荧光蛋白(YFP)标记。该模型导致多个轴突束的轴突损伤以及血脑屏障(BBB)破坏和神经炎症。皮质脊髓束(CST)是一个典型的长束，受到严重影响，是本研究的重点。在单轴突分辨率下使用优化的CLARITY，我们在3D中可视化了从桥脑桥到颈脊髓的整个CST体积，并计算了轴突病变的总数及其随时间的进展。我们的结果揭示了进行性创伤性轴突病变的存在，在锥体交叉处最大。损伤的皮质脊髓神经元核周萎缩，但未见神经元细胞死亡的证据。我们还在单轴突分辨率下使用CLARITY来探索NMNAT2-SARM1轴突自毁通路在外伤性轴突病中的作用。当我们通过从基因上消融SARM1或从药理学上增加烟酰胺(Nam) (SARM1抑制剂的原型)水平来干扰这一途径时，我们发现损伤后早期轴突病变数量显著减少。我们的研究结果表明，高分辨率神经解剖学策略揭示了TAI的重要特征和生物学意义，特别是TAI的进行性轴突病性质和NMNAT2-SARM1通路在轴突病早期阶段的作用。SIGNIFICANCE STATEMENTIn the first systematic application of novel high-resolution neuroanatomical tools in neuropathology, we combined CLARITY with 2-photon microscopy, optimized for detection of single axonal lesions, to reconstruct the injured mouse brain stem in a model of traumatic axonal injury that is a common pathology associated with traumatic brain injury. The 3D reconstruction of the corticospinal tract at single-axon resolution allowed for a more advanced level of qualitative and quantitative understanding of TAI. Using this model, we showed that TAI is an axonopathy with a prominent role of the NMNAT2-SARM1 molecular pathway, that is also implicated in peripheral neuropathy. Our results indicate that high-resolution anatomical models of TAI afford a level of detail and sensitivity that is ideal for testing novel molecular and biomechanical hypotheses. Copyright 2018 the authors.