Spinal circuitry for ventilatory control and compensation

克龙，S.A. 项目摘要 拟议的研究调查了脊髓V2a神经元在控制辅助性(非 (横隔肌)呼吸肌(手臂)来吸气。这些肌肉通常用来增加 运动时不能通风，但在受伤或疾病后也可用来增强横隔膜的功能。尽管 手臂对于加强通风或补偿横隔膜功能丧失的重要性很小 已知在健康或疾病中驱动他们活动的神经回路。手臂活动增加 ALS模型小鼠在疾病早期进行通风，但存在中枢缺陷，阻止激活 在疾病晚期，手臂用于呼吸，尽管这些肌肉对 自愿行为。增加(通过GQ信号通路)或减少(通过GI信号 在健康和ALS模型小鼠中，V2a神经元的兴奋性能够增加静息状态下的手臂活动。 因此，这些神经元是增加ALS患者手臂活动和换气的潜在靶点，其他 神经肌肉疾病或脊髓损伤。然而，V2a类神经元似乎由 在呼吸控制中扮演不同角色的亚型。为了开发改善呼吸的疗法 通过改变活动，防止变性，或替换退化的V2a神经元，有必要 确定影响通气性的V2a神经元的位置和分子亚型，并了解其 特定的角色。目标1将使用转基因和病毒策略来增加兴奋性，降低兴奋性，或消融 颈、胸、腰段脊髓V2a神经元识别呼吸肌活动的调节 不同节段水平的V2a神经元。目的2将研究V2a神经元的分子多样性 通过研究颈髓内侧呼吸回路中连通性和功能的差异 V2a亚型和侧向V2a亚型。AIM 2还将评估改变兴奋性对通风的影响 只有与呼吸运动神经元有直接兴奋性联系的V2a神经元。目标3将评估长期- V2a神经元变性对呼吸的长期影响--过早消融颈V2a神经元 肌萎缩侧索硬化症小鼠模型。慢性增加V2a兴奋性的潜在好处(和危险) 神经元对ALS模型小鼠手臂活动、运动神经元变性和呼吸健康的影响 评估过了。通过实现这些目标，我们将准确地确定 脊髓V2a神经元模式呼吸肌活动以及评估潜在的药理学 在ALS小鼠模型中改变V2a神经元的兴奋性以改善呼吸。

Crone, S. A. Project Summary The proposed studies investigate the role of spinal V2a neurons in the control of auxiliary (non- diaphragmatic) respiratory muscles (ARMs) for inspiration. These muscles are normally used to increase ventilation during exercise, but they are also used to augment diaphragm function after injury or disease. Despite the importance of ARMs for enhancing ventilation or compensating for loss of diaphragm function, little is known about the neural circuits that drive their activity in either health or disease. ARM activity increases ventilation in ALS model mice at early disease stages, but there is a central deficit that prevents activation of ARMs for breathing at late disease stages, despite the fact that these muscles are active and functional for voluntary behaviors. Either increasing (through Gq signaling pathways) or decreasing (through Gi signaling pathways) the excitability of V2a neurons is able to increase ARM activity at rest in healthy and ALS model mice. Thus, these neurons are a potential target to increase ARM activity and ventilation in patients with ALS, other neuromuscular diseases, or spinal cord injury. However, the V2a class of neurons appears to be composed of subtypes that play distinct roles in the control of breathing. In order to develop therapies to improve breathing by altering the activity, preventing degeneration, or replacing degenerated V2a neurons, it is necessary to determine the location and molecular subtypes of V2a neurons that impact ventilation and to understand their specific roles. Aim 1 will use transgenic and viral strategies to increase excitability, decrease excitability, or ablate V2a neurons in cervical, thoracic, or lumbar spinal cord to identify how respiratory muscle activity is regulated by V2a neurons at different segmental levels. Aim 2 will investigate the molecular diversity of V2a neurons within the cervical cord by investigating differences in connectivity and function within respiratory circuits of a medial V2a subtype and a lateral V2a subtype. Aim 2 will also asses the effects on ventilation of altering excitability of only V2a neurons with direct excitatory connections to respiratory motor neurons. Aim 3 will assess the long- term impact that degeneration of V2a neurons has on breathing by prematurely ablating cervical V2a neurons in a mouse model of ALS. The potential benefit (and hazards) of chronically increasing the excitability of V2a neurons on ARM activity, motor neuron degeneration, and ventilatory health in ALS model mice will also be assessed. By accomplishing these aims, we will pinpoint the location, molecular identity, and connectivity of spinal V2a neurons that pattern respiratory muscle activity as well as assess the potential of pharmacologically altering the excitability of V2a neurons to improve breathing in a mouse model of ALS.