Oxidative Stress and Pathological Glutamate Release in Stroke

摘要 在美国和其他地区，中风是第五大死亡原因，也是导致成年人长期残疾的主要原因 工业化国家。然而，只有一种治疗药物(溶解血栓的药物tPA)被批准用于急性 治疗。在中风的关键伤害因素中，氧化应激被认为是导致终末期的原因 组织损伤的步骤。抗氧化剂和自由基清除剂在动物中风模型中具有高度的保护作用。 然而，由于鲜为人知的原因，它们在临床试验中显示出的益处有限或没有。在之前的NIH- 我们收集了强有力的数据，这些数据可能有助于修正我们对这些机制的理解 脑缺血时的氧化损伤：(1)在卒中大鼠模型中，我们发现超氧化物歧化酶 与临床使用的抗氧化剂相比，(超氧化物歧化酶)模拟坦普尔具有更强的保护作用。(2)临时工的强力保护 与缺血半暗带对氧化还原敏感的谷氨酸释放减少有关。(3)谷氨酸释放 至少由两种氧化还原敏感机制介导：容量调节阴离子通道(Vrac)和钙离子通道。 膜通透性的依赖性变化。(4)谷氨酸通透性vrac由蛋白质组成。 来自富含亮氨酸重复序列的家族8(LRRC8)。我们已经组建了一支投资协同团队- 并提议使用高度创新的分子和动物工具来检验这一假说 氧物种(ROS，特别是超氧阴离子)通过刺激传播和放大中风损伤 临床相关半影区对氧化还原敏感的谷氨酸释放。在计划中的研究中，我们将 解决以下关键问题：(1)含有LRRC8A的vrac是神经保护的可行靶点吗？ 中风？(2)通过异构体LRRC8通道释放谷氨酸是导致组织损伤的原因吗？(3)什么 Tempol靶向ROS的化学性质及其产生的细胞位置？(4)谷氨酸 通过vrac驱动神经血管界面的破坏释放(血流和血脑屏障完整性的改变)？这个 这项拟议工作的直接目标是确定控制氧化大脑的新分子机制 并确定抗氧化剂的保护作用。我们的长期目标是提供一幅蓝图 用于开发基于超氧化物歧化酶模拟物和/或vrac阻滞剂的新的有效中风疗法。

SUMMARY Stroke is the fifth leading cause of death and the leading cause of adult long-term disability in the U.S. and other industrialized nations. Yet only one therapeutic agent (the clot-dissolving drug tPA) is approved for acute treatment. Among the critical injurious factors in stroke, oxidative stress is thought to contribute to the terminal steps of tissue damage. Antioxidants and free radical scavengers are highly protective in animal stroke models. Yet, for poorly understood reasons, they have shown limited or no benefits in clinical trials. In the prior NIH- sponsored project, we collected strong data which may help to revise our understanding of the mechanisms contributing to oxidative injury in ischemia: (1) In a rat model of stroke, we found that the superoxide dismutase (SOD) mimetic tempol was more protective than clinically used antioxidants. (2) Potent protection by tempol correlated with reduction of redox-sensitive glutamate release in the ischemic penumbra. (3) Glutamate release was mediated by at least two redox-sensitive mechanisms: volume-regulated anion channels (VRAC) and Ca2+- dependent changes in membrane permeability. (4) The glutamate-permeable VRAC was composed of proteins from the leucine-rich repeat-containing family 8 (LRRC8). We have assembled a synergistic team of investi- gators and propose to use highly innovative molecular and animal tools to test the HYPOTHESIS that reactive oxygen species (ROS, particularly superoxide anions) propagate and amplify stroke injury via stimulation of redox-sensitive glutamate release in the clinically relevant penumbra. In the planned studies we will address the following critical questions: (1) Is the LRRC8A-containing VRAC a viable target for neuroprotection in stroke? (2) Is glutamate release via the heteromeric LRRC8 channels responsible for tissue injury? (3) What is the chemical nature of the tempol-targeted ROS and the cellular site of their production? (4) Does glutamate release via VRAC drive disruption at the neurovascular interface (changes in blood flow and BBB integrity)? The immediate goal of the proposed work is to identify new molecular mechanisms that govern oxidative brain injury and determine the protective actions of antioxidants. Our long-term objective is to provide a blueprint for the development of new effective stroke therapies based on SOD mimetics and/or VRAC blockers.