Mechanisms Underlying Excitability Regulation of Motoneuron Types in ALS

项目总结/摘要 肌萎缩侧索硬化症（ALS）的多种病理已经研究，但有效的治疗 仍然难以捉摸运动神经元（MN）兴奋性的降低仍然与疾病路径最紧密相关- 起源这一提议的中心假设是，这些异常不是一个附带现象， ALS，而是引发导致MN死亡的事件的早期病理生理事件。巧合的是， MN超兴奋性和低兴奋性变化在不同的疾病阶段，在多个 ALS小鼠的品系。缺乏对高兴奋性和低兴奋性变化所起作用的明确性（即，神经保护素， 保护性或有害的），以及这些变化背后的离子通道，代表了细胞的关键障碍。 开发更有效的治疗方法。这一建议的理由是，了解如何低- 兴奋性机制也有助于越来越不稳定的MN环境将填补一个重要的 知识的差距。该建议的工作假设是：1）高兴奋性和低兴奋性变化 在MN中，属性不是相互排斥的，但可以同时存在; 2）它们代表波动， 疾病和代偿机制之间的关系; 3）它们的相反作用导致兴奋性波动， 最初是可管理的;但随后程度升级，最终导致MN死亡;以及4）不足- 高兴奋性和低兴奋性变化背后的离子机制可能导致药物焦油， 稳定MN兴奋性，防止MN死亡。将通过以下目标检验假设： 目的1：确定症状发作时运动神经元兴奋性失调的形式， 将在G93 A ALS小鼠中测量调节兴奋性的电学和解剖学细胞特性 MN相对于野生型（WT）MN。 目的2：通过计算机模拟确定介导MN低兴奋性的细胞机制。高- 保真度计算机模型将分析兴奋性特性的相互作用，然后预测可能的机制。 目的3：实证验证模型预测MN和皮质神经元中Kv2.1通道激活减少。 电生理学、免疫组织化学和蛋白质印迹实验将评估激活和表达。 在四个关键疾病阶段，ALS与WT MN中离子通道的表达水平。 如果得到证实，这些数据将提供MN内并发低兴奋性和高兴奋性的第一个证据 在ALS中，从而提供了ALS和额颞叶中兴奋性失调的新机制， 退行性痴呆（FTD）。

Project Summary/Abstract Multifarious pathologies of amyotrophic lateral sclerosis (ALS) have been studied, yet effective treatments remain elusive. Abnormalities in motoneuron (MN) excitability remain the most tightly linked to disease path- ogenesis. The central hypothesis of this proposal is that these abnormalities are not an epiphenomenon of ALS, but rather an early pathophysiologic event that initiates the events leading to MN death. Paradoxically, both MN HYPER- and HYPO-excitability changes have been seen at various disease stages, in multiple lines of ALS mice. The lack of clarity on what roles hyper- and hypo-excitability changes play (i.e., neuropro- tective or detrimental), and which ion channels underlie these changes, represents a critical barrier to the development of more effective treatments. The rationale for this proposal is that understanding how hypo- excitability mechanisms also contribute to the increasingly unstable MN environment will fill an important gap in knowledge. The working hypotheses of this proposal are that: 1) Hyper- and hypo-excitable changes in MN properties are not mutually exclusive, but can concurrently exist; 2) they represent fluctuations be- tween disease and compensatory mechanisms; 3) their opposing effects cause excitability fluctuations that are initially manageable; but then escalate in magnitude, eventually leading to MN death; and 4) under- standing the ionic mechanisms underlying both hyper- and hypo-excitability changes can lead to drug tar- gets for stabilization of MN excitability to prevent MN death. The hypotheses will be tested via these Aims: Aim 1: Determine the form of motoneuronal excitability dysregulation at symptom onset, A large array of electrical and anatomical cell properties that modulate excitability will be measured in G93A ALS mouse MNs vs. wild-type (WT) MNs. Aim 2: Identify the cellular mechanisms mediating MN hypo-excitability via computational modeling. High- fidelity computer models will analyze interactions of excitability properties; then predict likely mechanisms. Aim 3: Empirically verify model predictions of reduced Kv2.1 channel activation in MNs and cortical neurons. Electrophysiology, immunohistochemistry, and Western blot experiments will assess the activation and ex- pression levels of ion channels in ALS vs. WT MNs at four key disease stages. If verified, these data would provide the first evidence of concurrent hypo- and hyper-excitability within MNs in ALS, thereby providing a novel mechanism of excitability dysregulation in ALS and frontotemporal lobar degeneration dementia (FTD).