Non-canonical mechanisms of excitotoxicity

项目摘要 该项目旨在探讨易受损组织缺血性损伤的潜在机制， 急性脑损伤，如中风。我们的长期目标是确定 将代谢受损的组织转变为受损的促死亡半影区，并发展为临床相关 治疗目标，以提高脑损伤后患者的生存率。虽然了解缺血性方法， 神经元损伤一直是主要的焦点，探索后果和潜在的具体机制， 治疗目标远远落后。这个项目特别关注扩展去极化（SD） 最近被确定为对脆弱人群的伤害进展有重大贡献， 半影这些事件的主要焦点是它们对延长NMDA介导的Ca 2 + 流入和随后的损害。然而，SDs提出了一个更复杂和未充分探索的激增的预- 突触阳离子释放和通过交替途径的突触后摄取。尤其是突触后 电压门控Ca 2+通道的激活和细胞外Zn 2+释放和摄取的增加已经被联系起来， SD的发生和随后的传播。我们的中心假设是SD诱导的损伤进展 在代谢耗尽的组织中，由非NMDA中心阳离子稳态的失调介导。 此外，可以选择性地减少替代Ca 2+通道激活和/或减少后激活的药物 突触Zn 2+摄取将减少SD后发生的下游介导的损伤。我们要用脑子 探讨Zn 2+和Ca 2+特异性损伤机制以及药理学作用 在SD发作期间和之后进行干预以支持受损组织。具体目标1侧重于 假设神经元电压门控Ca 2+通道有助于突触后细胞内Ca 2+摄取， 导致下游单元执行。神经元Ca 2+负荷将使用特定的基因修饰的 模型和药物干预将用于评估代谢受损组织的恢复情况 设置.具体目标2检验了Zn 2+稳态的破坏有助于以下机制的假设： 易受伤害环境中的SD诱导损伤。脆弱组织中的Zn 2+波和Zn 2+的特异性储存将被破坏。 评估以探索哪里释放了破坏性水平。具体目标3然后评估这些机制， 体内设置。在所有目标中，电生理和成像技术将用于评估特定的 脑切片中的机制（目标1和2），然后转化为体内模型（目标3）。药理 干预和特定的击倒模型将探索这些阳离子对损害的贡献， 确定这些阳离子的破坏性水平起源于何处。实现这些目标应确定具体的 Ca 2+和Zn 2+介导的损伤机制，并提出了潜在的目标， 临床预防模式。

PROJECT SUMMARY This project addresses the underlying mechanisms that progress ischemic damage of vulnerable tissue that surround acute brain injuries such as stroke. Our long-term goal is to identify the specific mechanisms that transition metabolically compromised tissue to damaged, pro-death penumbra and to develop clinically relevant therapeutic targets to improve patient survival after brain injury. While understanding of ischemic methods of neuronal injury has been the primary focus, exploring specific mechanisms of consequence and potential therapeutic targets has lagged far behind. This project looks specifically at Spreading Depolarizations (SDs) which have recently been identified as contributing significantly to the progression of injury in vulnerable penumbra. The main focus of these events has been on their contribution to prolonged NMDA-mediated Ca2+ influx and subsequent damage. However, SDs present a much more complex and underexplored surge of pre- synaptic cation release and post-synaptic uptake through alternate pathways. Specifically both post-synaptic activation of voltage-gated Ca2+ channels and increase in extracellular Zn2+ release and uptake have been linked to the initiation and subsequent propagation of SD. Our central hypothesis is that SD-induced injury progression in metabolically depleted tissue is mediated by dysregulation of non-NMDA-centric cation homeostasis. Furthermore, agents that are selective to reduce alternative Ca2+ channel activation and/or decrease post- synaptic Zn2+ uptake will reduce the downstream mediated damage that occurs following SD. We will use brain slice and animal models to explore Zn2+ and Ca2+ specific mechanisms of injury as well as pharmacological intervention to support compromised tissue during and after onset of SD. Specific Aim 1 focuses on the hypothesis that neuronal voltage-gated Ca2+ channels contribute to post-synaptic uptake of intracellular Ca2+ and lead to downstream cell execution. Neuronal Ca2+ loading will be assessed using a specific genetically modified model and pharmacological intervention will be used to assess recovery in a metabolically compromised tissue setting. Specific Aim 2 tests the hypothesis that disruption of Zn2+ homeostasis contributes to mechanisms of SD-induced injury in vulnerable setting. Zn2+ wave in vulnerable tissue and specific stores of Zn2+ will be assessed to explore where damaging levels are released. Specific Aim 3 then assess these mechanisms in an in vivo setting. In all aims, both electrophysiological and imaging techniques will be used to assess specific mechanisms in brain slice (Aim 1 and 2) and then translate into in vivo model (Aim 3). Pharmacological intervention and specific knockdown models will explore where these cations contributions to damage and identify where damaging levels of these cations originate. Completion of these aims should ascertain specific mechanisms of Ca2+ and Zn2+-mediated injury following SD in vulnerable tissue and propose potential targets for clinical prevention paradigms.