AMPA/Kainate Receptors, Free Radicals, And Motor Neuron Injury

在ALS中观察到CSF谷氨酸增加，以及运动神经元（MN） 选择性地易受谷氨酸受体介导的（“兴奋性毒性”）损伤支持兴奋性毒性贡献 在疾病中的MN损失。过去的研究强调了可能导致这种脆弱性的因素; 与大多数其他神经元相比，MN的兴奋毒性激活诱导更大的线粒体Ca 2+超载 和异常强的活性氧物质（ROS）生成。然而，虽然星形胶质细胞谷氨酸 转运蛋白占CMS中谷氨酸摄取的大部分，它们的损伤似乎是CMS的基础。 ALS中细胞外谷氨酸升高，其功能障碍的原因尚不清楚。提供 可能的线索，最近的研究表明，这种ROS产生的MN内的兴奋性毒性反应， 活化本身可引起周围星形胶质细胞中谷氨酸摄取的破坏。这些观察结果 提示兴奋性毒性MN损伤与谷氨酸氧化破坏因果联系机制 运输，并为ALS的前馈模型提供基础，其中一系列激发因素 可能会导致一种常见的疾病 这项建议的主要目的是使用文化和切片模型来扩展这些研究， 检查MN内ROS产生导致区域谷氨酸丢失的假设 体内运输MN内兴奋性毒性ROS的产生及其穿透周围组织和 将在来自野生型小鼠的解离和切片培养模型中检查破坏谷氨酸转运， 以及携带与家族性ALS相关的超氧化物歧化酶（SOD）突变的小鼠（ 提供疾病的最佳动物模型）。将使用SOD突变小鼠来检查 氧化变化和运输中断发生在大腹侧周围区域 角状MN，如果MN是ROS的来源，则可以预测。最后，选择的能力 减少这些病理过程的药物干预将在切片和动物中进行测试。 模型希望这些研究能进一步阐明导致选择性MN的事件序列 减少ALS，从而促进新治疗策略的开发。

Observations of increased CSF glutamate in ALS, together with findings that motor neurons (MNs) are selectively vulnerable to glutamate receptor mediated ("excitotoxic") injury support an excitotoxic contribution to MN loss in the disease. Past studies have highlighted factors that may underlie this vulnerability; in comparison to most other neurons, excitotoxic activation of MNs induces greater mitochondrial Ca2+ overload and exceptionally strong reactive oxygen species (ROS) generation. However, while astroglial glutamate transporters account for most glutamate uptake in the CMS,and their damage appears to underlie extracellular glutamate elevations in ALS, the reason for their dysfunction has been unclear. Providing a possible clue, recent studies suggest that this ROS generated within MNs in response to excitotoxic activation may in itself cause disruption of glutamate uptake in surrounding astrocytes. These observations suggest a mechanism that causatively links excitotoxic MN damage with oxidative disruption of glutamate transport, and provide the basis the for a feed forward model of ALS, in which a range of inciting factors could lead into a common disease pathway. The broad aim of this proposal is to use culture and slice models to extend these studies and further examine the hypothesis that ROS generation within MNs contributes to the loss of regional glutamate transport in vivo. Excitotoxic ROS generation within MNs and its ability to penetrate surrounding tissue and disrupt glutamate transport will be examined in dissociated and slice culture models from wild type mice as well as mice harboring superoxide dismutase (SOD) mutations associated with familial forms of ALS (which provide the best animal models of the disease). SOD mutant mice will be used to examine the degree to which oxidative changes and disruption of transport occurs in regions immediately surrounding large ventral horn MNs, as would be predicted if the MNs are the source of the ROS. Finally, the ability of selected pharmacological interventions to decrease these pathological processes will be tested in slice and animal models. It is hoped that these studies will further clarify sequences of events culminating in selective MN loss in ALS, and thereby facilitate development of new treatment strategies.