Axonal degeneration plays a key role in the pathogenesis of numerous neurological disorders including spinal cord injury. After the irreversible destruction of the white matter elements during the primary (mechanical) injury, spared axons and their supporting glial cells begin to breakdown causing an expansion of the lesion site. Here we mechanistically link external sources of calcium entry through axoplasmic reticulum calcium store depletion that contributes to secondary axonal degeneration through a process called store-operated calcium entry. There is increasing evidence suggesting that store-operated calcium entry impairment is responsible for numerous disorders. Nevertheless, its role following spinal cord injury remains poorly understood. We hypothesize that store-operated calcium entry mediates secondary white matter degeneration after spinal cord injury. We used our previously published model of laser-induced spinal cord injury to focally transect mid cervical dorsal column axons from live 6-8-week-old heterozygous CNPaseGFP/+: Thy1YFP+ double transgenic murine spinal cord preparations (five treated, eight controls) and documented the dynamic changes in axons over time using two-photon excitation microscopy. We report that 1 hour delayed treatment with YM-58483, a potent inhibitor of store-operated calcium entry, significantly decreased intra-axonal calcium accumulation, axonal dieback both proximal and distal to the lesion site, reduced secondary axonal "bystander" damage acutely after injury, and promoted greater oligodendrocyte survival compared to controls. We also targeted store-operated calcium entry following a clinically relevant contusion spinal cord injury model in vivo. Adult, 6-8-week-old Advillin-Cre: Ai9 mice were subjected to a mild 30 kdyn contusion and imaged to observe secondary axonal degeneration in live animals. We found that delayed treatment with YM-58483 increased axonal survival and reduced axonal spheroid formation compared to controls (n = 5 mice per group). These findings suggest that blocking store-operated calcium entry acutely is neuroprotective and introduces a novel target to prevent pathological calcium entry following spinal cord injury using a clinically relevant model.

中文翻译：

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SCI后，抑制钙库操纵的钙进入会减弱白质继发性变性。

轴突变性在包括脊髓损伤在内的许多神经系统疾病的发病机理中起着关键作用。在原发性（机械性）损伤期间，白质元素不可逆转地破坏后，多余的轴突及其支持的神经胶质细胞开始分解，导致病变部位扩大。在这里，我们通过轴质网的钙存储消耗机制性地联系了钙输入的外部来源，而钙存储消耗是通过称为存储操作性钙输入的过程导致继发性轴突变性的原因。越来越多的证据表明，商店经营的钙进入障碍是造成许多疾病的原因。然而，其在脊髓损伤后的作用仍知之甚少。我们假设在脊髓损伤后，钙存储的钙进入介导了继发性白质的退化。我们使用先前发表的激光诱发的脊髓损伤模型从活的6-8周龄的杂合CNPaseGFP / +集中横切颈背中轴轴突：Thy1YFP +双转基因鼠脊髓制剂（5种治疗，8种对照），以及用双光子激发显微镜记录了轴突随时间的动态变化。我们报告说，YM-58483（一种有效的钙池操纵性钙进入抑制剂）延迟治疗1小时，显着降低了轴突内钙积累，病变部位近端和远端的轴突枯死，急性继发性轴突“旁观者”损伤减少。与对照组相比，损伤程度更高，并促进少突胶质细胞存活。我们还针对临床相关的挫伤性脊髓损伤体内模型，针对了钙库操作的钙离子进入。对成年的6-8周大的Advillin-Cre：Ai9小鼠进行30 kdyn轻度挫伤，并进行成像以观察活体动物的继发性轴突变性。我们发现，与对照组相比，YM-58483延迟治疗可增加轴突存活率并减少轴突球体的形成（每组n = 5只小鼠）。这些发现表明，使用临床上相关的模型，急性阻断储库操作的钙进入具有神经保护作用，并引入了一种新的靶标，以防止脊髓损伤后病理性钙进入。Ai9小鼠受到轻度的30 kdyn挫伤，并成像以观察活体动物的继发性轴突变性。我们发现，与对照组相比，YM-58483延迟治疗可增加轴突存活率并减少轴突球体的形成（每组n = 5只小鼠）。这些发现表明，使用临床上相关的模型，急性阻断储库操作的钙进入具有神经保护作用，并引入了一种新的靶标，以防止脊髓损伤后病理性钙进入。Ai9小鼠受到轻度的30 kdyn挫伤，并成像以观察活体动物的继发性轴突变性。我们发现，与对照组相比，YM-58483延迟治疗可增加轴突存活率并减少轴突球体的形成（每组n = 5只小鼠）。这些发现表明，使用临床上相关的模型，急性阻断储库操作的钙进入具有神经保护作用，并引入了一种新的靶标，以防止脊髓损伤后病理性钙进入。