Central and Peripheral Elements of Respiratory Pattern Formation

描述（由申请人提供）：呼吸是一种至关重要的多方面行为，其中中枢产生的节律必须转化为脊髓和颅神经上运动活动的协调模式，产生胸壁的泵送作用并调节气道张力。来自气道的机械感觉输入对于这种协调是必不可少的。特别是在具有高度顺应性胸壁的哺乳动物（包括人类婴儿）中，气道受体的拮抗组调节吸气末容积（即潮气量）和呼气末容积。然而，很少有人知道这些不同的呼吸运动反应是如何协调中枢神经系统。在本申请中，我们将定义（在大鼠中）响应于肺充气（缓慢适应受体; SAR）和肺放气（放气激活受体; DAR）引起两种拮抗反射的中枢通路。将有三个具体目标。在目的1中，将使用结合其突触靶标的逆行标记的小群体NTS细胞的顺行标记来全面调查不同类型的SAR和DAR NTS中继神经元的轴突投射。互补的研究，使用互相关的同时记录的尖峰列车将评估这些功能的相互作用。在目标2中，单一的，唯一定义的SAR和DAR中间神经元沿着与其目标的逆行标记的细胞染料填充将允许结合的NTS中继神经元与多个目标的突触连接的光和电子显微镜分析。在目标3中，将使用NTS神经元及其潜在靶标的细胞标记来定义与SAR和DAR NTS中间神经元突触后的神经元的电生理学定义的表型。尖峰触发的平均将允许表征NTS中继神经元和特定突触后细胞之间的突触连接及其相对强度。两者合计，这些实验将确定，第一次，SAR和DAR传入中继神经元的突触后靶点，并提供一个多突触电路图的途径产生协调的呼吸反射反应激活肺机械感受器。这些电路的知识可以阐明患者的治疗策略与受损的气道控制的特点，一系列的呼吸系统疾病和退行性运动疾病。项目叙述：这项研究将检查与调节呼吸的中枢反射相关的脑干回路。通过详细了解从气道和肺部接收信息的神经元之间的相互联系，我们将以一种以前不可能的方式描述呼吸力和时间模式的控制系统。这种类型的信息对于分析这些回路在从肌萎缩侧索硬化到婴儿猝死综合征等各种人类疾病中的作用将是重要的。

DESCRIPTION (provided by applicant): Breathing is a vital, multifaceted behavior in which a centrally generated rhythm must be transformed into coordinated patterns of motor activity on spinal and cranial nerves that produce the pumping action of the chestwall and regulate airway tone. Mechanosensory input from the airways is essential for this coordination. Especially in mammals that have highly compliant chest walls - including human infants - antagonistic sets of airway receptors regulate end-inspiratory volume (ie, tidal volume) and end-expiratory volume. However, little is known about how these differential respiratory motor responses are coordinated within the central nervous system. In this application we will define (in rats) the central pathways by which two antagonistic reflexes are elicited in response to lung inflation (slowly adapting receptors; SARs) and lung deflation (deflation activated receptors; DARs). Three Specific Aims will be addressed. In Aim 1 the axonal projections of the different types of SAR and DAR NTS relay neurons will be comprehensively surveyed using anterograde labeling of small groups of NTS cells combined with retrograde labeling of their synaptic targets. Complementary studies using cross-correlation of simultaneously recorded spike trains will assess these functional interactions. In Aim 2, juxtacellular dye filling of single, uniquely defined SAR and DAR interneurons along with retrograde labeling of their targets will permit combined light- and electron-microscopic analysis of the synaptic connections of NTS relay neurons with multiple targets. In Aim 3 the electrophysiologically defined phenotypes of neurons post- synaptic to SAR and DAR NTS interneurons will be defined using juxtacellular labeling of both NTS neurons and their potential targets. Spike-triggered averaging will permit characterization of the synaptic connectivity, and its relative strength, between the NTS relay neurons and specific post-synaptic cells. Taken together, these experiments will identify, for the first time, the post-synaptic targets of SAR and DAR afferent relay neurons and provide a polysynaptic circuit diagram of the pathways producing coordinated respiratory reflex responses to activation of lung mechanoreceptors. Knowledge of these circuits may elucidate treatment strategies for patients with compromised airway control characteristic of a range of respiratory disorders and degenerative motor diseases. PROJECT NARRATIVE: This research will examine the brainstem circuits related to central reflexes modulating breathing. By following in detail the interconnections of neurons receiving information from the airways and lungs we will describe the control system for the force and temporal pattern of breathing in a way that has not previously been possible. This type of information will be important for analyzing the role of these circuits in a variety of human diseases ranging from amyotrophic lateral sclerosis to sudden infant death syndrome.