APOPTOSIS IN TRAUMATIC SPINAL CORD INJURY

这项研究计划的重点是鉴定和表征创伤性脊髓损伤（SCI）后凋亡细胞死亡所涉及的分子信号事件。尽管最近有证据表明SCI后神经元和神经胶质细胞广泛发生凋亡，但凋亡途径的分子组成仍然很大程度上未知。拟议的实验将提供证据的组件在细胞凋亡机制负责启动和执行这一细胞死亡过程。此外，实验表明，参与细胞凋亡死亡途径的阻断步骤提供了神经保护，促进急性SCI的功能恢复。我们假设钙调神经磷酸酶介导的BAD去磷酸化是凋亡级联反应的初始上游事件之一，并与caspase-3激活有关。谷氨酸诱导的Ca 2+内流导致钙调神经磷酸酶激活，并且在SCI后不久释放高水平的谷氨酸。因此，我们将研究鞘内注射选择性谷氨酸受体激动剂到未损伤的脊髓是否会导致钙调磷酸酶介导的BAD去磷酸化。此外，我们将证明，注射谷氨酸受体拮抗剂减少激活的caspase-3凋亡级联。最后，目前尚不清楚细胞凋亡对SCI后功能缺陷的影响。因此，我们将用靶向钙调磷酸酶和半胱天冬酶-3的抑制剂治疗受伤的动物，并使用形态学、组织学和行为学标准来测量凋亡细胞死亡和功能恢复的指数。这些研究的结果将对减少继发性神经元和神经胶质细胞死亡和促进SCI后功能恢复具有明确的临床意义。

The studies proposed in this grant application focus on identifying and characterizing the molecular signaling events involved in apoptotic cell death following traumatic spinal cord injury (SCI). Despite the recent evidence of widespread apoptosis in neurons and glia after SCI, the molecular components of the apoptotic pathway remain largely unknown. The proposed experiments will provide evidence of components in the apoptotic machinery responsible for initiating and executing this cell death process. In addition, experiments are proposed to demonstrate that blocking steps involved in the apoptotic cell death pathway provides neuroprotection and promotes functional recovery in acute SCI. We hypothesize that calcineurin-mediated BAD dephosphorylation is one of the initial upstream events in the apoptotic cascade and is linked to caspase-3 activation. Glutamate-induced Ca2+ influx leads to calcineurin activation and high levels of glutamate are released soon after SCI. Therefore, we will examine whether intrathecal injections of selective glutamate receptor agonists into uninjured spinal cord lead to calcineurin- mediated BAD dephosphorylation. In addition, we will demonstrate that injections of glutamate receptor antagonists reduce activation of the caspase-3 apoptotic cascade. Finally, the contribution of apoptosis to the functional deficits observed following SCI is not clear at this time. Therefore, we will treat injured animals with inhibitors targeting calcineurin and caspase-3 and use morphological, histological, and behavioral criteria to measure indices of apoptotic cell death and functional recovery. The outcome of these studies will have clear clinical implications for minimizing secondary neuronal and glial cell death and promoting recovery of function following SCI.