Spinal cord injury, paralysis and neuromuscular junctions

描述（由申请人提供）：几种不同的治疗方法已经在脊髓损伤（SCI）的实验模型中产生了运动功能的显著恢复。这些治疗包括旨在增强轴突再生的策略和针对髓鞘再生、组织保留和训练备用回路的策略。然而，它们在床边的潜在用途严重依赖于神经肌肉连接，不仅保持功能，而且尽可能有效地发挥作用。然而，令人惊讶的是，肌肉对SCI的突触反应很少受到关注，SCI尾侧的神经肌肉接头（NMJ）被认为保持完整。然而，我们的初步形态学分析表明，脊髓损伤瘫痪的成年大鼠后肢肌肉中的NMJ可能是极其功能失调的。此外，这些研究表明，成年NMJ可能是非常多样化和具体的麻痹的敏感性。在这个R21应用中，我们将使用荧光转基因小鼠，在体内延时成像，并结合电生理和形态学分析，以确定（1）是否有多个亚群的NMJ不同的前和突触后敏感性SCI引起的瘫痪，（2）如果生理上显着的神经肌肉连接的损失伴随着形态学不稳定的NMJ远端SCI。这些结果将提供关键数据，以证明更大的拨款申请：探索成熟NMJ意外多样性的分子机制;全面评估NMJ损失对SCI相关运动缺陷的贡献;并试图通过稳定NMJ来促进运动恢复。因此，拟议的工作有可能为开发脊髓损伤患者的新型治疗方法奠定坚实的基础。公共卫生相关性：几种不同的治疗方法在脊髓损伤的实验模型中产生了运动功能的显著恢复。这些治疗包括旨在增强轴突再生的策略和针对髓鞘再生、组织保留和训练备用回路的策略。该项目旨在通过确定神经肌肉连接（称为神经肌肉接头）作为新的治疗靶点，为脊髓损伤后的运动缺陷和恢复提供新的基础。

DESCRIPTION (provided by applicant): Several different therapeutic approaches have produced significant recovery of motor function in experimental models of spinal cord injury (SCI). These treatments include strategies designed to enhance axon regeneration and strategies targeted towards remyelination, tissue sparing and training the spared circuits. Their potential usefulness at the bedside, however, is critically dependent on nerve-muscle connectivity that not only remains functional but also functions as efficiently as possible. Surprisingly, however, the synaptic responses of muscles to SCI have received little attention, and the neuromuscular junctions (NMJs) caudal to SCI are assumed to remain intact. Our preliminary morphological analyses, however, suggest that NMJs in hindlimb muscles of adult rats paralyzed by SCI may be extremely dysfunctional. Furthermore, these studies imply that adult NMJs may be extraordinarily diverse and specific in their sensitivity to paralysis. In this R21 application, we will use fluorescent transgenic mice, in vivo time-lapse imaging, and combined electrophysiological and morphological analyses to determine (1) if there are multiple subpopulations of NMJs that differ in pre- and postsynaptic sensitivity to the SCI-elicited paralysis, and (2) if physiologically significant loss of nerve-muscle connectivity accompanies morphological instability of NMJs distal to SCI. These results will provide critical data to justify a larger grant application to: explore the molecular mechanisms underlying the unexpected diversity of mature NMJs; comprehensively assess the contribution of NMJ loss to motor deficits associated with SCI; and attempt to promote motor recovery by stabilizing NMJs. The proposed work therefore has the potential to establish a strong foundation for developing novel treatments for spinal cord injured patients. PUBLIC HEALTH RELEVANCE: Several different therapeutic approaches have produced significant recovery of motor function in experimental models of spinal cord injury. These treatments include strategies designed to enhance axon regeneration and strategies targeted towards remyelination, tissue sparing and training the spared circuits. The project seeks to provide a novel basis for motor deficits and recovery following spinal cord injury by identifying nerve-muscle connections, termed neuromuscular junctions, as novel therapeutic targets.