Maladaptive Remodeling of the Neuromuscular Synapse Following Central Nervous System Injury

项目摘要/摘要 中枢神经系统(CNS)损伤，如中风和脊髓损伤(SCI)是导致 全球残疾负担。减轻中枢神经系统损伤是研究和神经康复的核心 促进复苏的战略。然而，越来越多的证据表明，术后周围神经系统(PNS)发生了变化 中枢神经系统损伤为治疗性研究提供了一个未开发的区域。PNS将CNS电机输出与 骨骼肌功能，其中运动单位招募和放电率调节控制。马达单元包括 一个运动神经元和它支配的所有肌纤维。为了运动控制的精确度，健康的肌纤维可以接受一个 通过单个神经肌肉接头(NMJ)的运动神经元轴突。研究表明，严重的运动单位损失 中风和脊髓损伤后的瘫痪肌肉，尽管确切的机制尚不清楚。此外，申请人最近 发现卒中后显著的NMJ重塑，包括异常的多轴神经支配(PAI)，其中NMJ 接受多个轴突输入。SCI的飞行员数据显示，运动单位的损失类似于中风，但影响 在NMJ的SCI仍未被探索。总而言之，这个项目将审问不适应的PNS重塑 在中枢神经系统损伤残疾的背景下。这项工作将测试靶向偏瘫NMJ的治疗潜力 脑源性神经营养因子(BDNF)，已知的运动神经元活性和NMJ可塑性的中介。在……里面 小鼠中风和脊髓损伤模型，申请者将纵向研究运动行为，运动单位电- 生理学和肌肉收缩；评估运动神经元池和NMJ的组织病理学；使用分子 生物技术，以确定PAI的机制；并验证一种新的基因治疗方法。目标1将测试 脊髓损伤导致运动单位功能障碍和NMJ重塑的假说，类似于中风。目标2将定义 卒中导致运动单位丢失的病理生理学机制；一些人预测运动神经元变性是 负责任的，然而我们假设发育介质的重新表达会导致运动单位重叠， PAI在电生理学上表现为假性运动单位丢失。目标3将检验这一假说-- 脑源性神经营养因子信号转导的卒中减少驱动PAI，而通过腺相关病毒传递使脑源性神经营养因子正常化 恢复NMJ形态和运动功能。在翻译神经肌肉生理学方面的指导培训 赞助商(神经肌肉专家，具有丰富的临床前/临床神经肌肉健康经验和 疾病)由一位CNS/PNS疾病的基因治疗专家作为共同赞助者进行补充，并由 两位关键合作者(一位是脊髓损伤内科医生兼科学家，另一位是具有脑源性神经营养因子信号专长的神经学家)。这 导师团队与俄亥俄州立大学优秀的资源和环境相吻合，以促进 在新的调查领域发展，并为申请人的独立做好准备。使用与临床相关的 询问中枢神经系统损伤后运动功能障碍的外周机制的方法，该项目将扩大 对中风和脊髓损伤残疾的基本认识，为未来针对外周的治疗提供信息 并为学术神经学研究的职业发展提供重要的培训机会。

PROJECT SUMMARY / ABSTRACT Central nervous system (CNS) injuries such as stroke and spinal cord injury (SCI) are major contributors to the global burden of disability. Attenuating CNS damage represents the core of research and neurorehabilitation strategies to enhance recovery. Yet, mounting evidence of peripheral nervous system (PNS) alterations after CNS injury provides an untapped area for therapeutic investigation. The PNS links CNS motor output with skeletal muscle function, where motor unit recruitment and firing rate modulate control. A motor unit is comprised of one motoneuron and all myofibers it innervates. For precision of motor control, healthy myofibers receive one motoneuronal axon via a single neuromuscular junction (NMJ). Studies suggest profound motor unit loss in paretic muscle after stroke and SCI, though exact mechanisms are undefined. Moreover, the applicant recently identified striking NMJ remodeling after stroke, including aberrant polyaxonal innervation (PAI), where NMJs receive more than one axonal input. Pilot data in SCI demonstrate motor unit losses similar to stroke, but impacts of SCI at the NMJ remain unexplored. Taken together, this project will interrogate maladaptive PNS remodeling in the context of CNS injury disability. This work will test the therapeutic potential of targeting paretic NMJs with brain-derived neurotrophic factor (BDNF), a known mediator of motor neuron viability and NMJ plasticity. In murine models of stroke and SCI, the applicant will longitudinally study motor behavior, motor unit electro- physiology, and muscle contractility; assess histopathology of motoneuron pools and NMJs; employ molecular biology techniques to define mechanisms of PAI; and validate a novel gene therapy approach. Aim 1 will test the hypothesis that SCI induces motor unit dysfunction and NMJ remodeling, similar to stroke. Aim 2 will define pathophysiological mechanisms of stroke-induced motor unit loss; some predict motoneuron degeneration is responsible, however we hypothesize re-expression of developmental mediators induces motor unit overlap, with PAI presenting electrophysiologically as spurious motor unit loss. Aim 3 will test the hypothesis that post- stroke reduction in BDNF signaling drives PAI, while normalization of BDNF via adeno-associated viral delivery restores NMJ form and motor function. Mentored training in translational neuromuscular physiology from the Sponsor (a neuromuscular specialist with extensive preclinical/clinical experience in neuromuscular health and disease) is complemented by a gene therapy specialist in CNS/PNS diseases as Co-Sponsor, and supported by two key Collaborators (an SCI physician-scientist, and a neuroscientist with BDNF signaling expertise). This mentorship team dovetails with the excellent resources and environment at The Ohio State University to facilitate growth in new areas of investigation and prepare the applicant for independence. Using clinically-relevant approaches to interrogate peripheral mechanisms of motor dysfunction after CNS injury, this project will expand the fundamental understanding of stroke and SCI disability, inform future therapeutics targeting peripheral alterations, and offer critical training opportunities for career development in academic neurological research.