Central and Peripheral Elements of Respiratory Pattern Formation

描述(申请人提供)：呼吸是一种重要的、多方面的行为，在这种行为中，中央产生的节律必须转化为脊神经和脑神经上协调的运动活动模式，从而产生胸壁的泵动作用并调节呼吸道张力。来自呼吸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，具有拮抗性的几组呼吸道受体调节吸气末容量(即潮气量)和呼气末容量。然而，关于这些不同的呼吸运动反应是如何在中枢神经系统内协调的，人们知之甚少。在这项应用中，我们将定义(在大鼠中)对肺膨胀(慢适应受体；SARS)和肺收缩(收缩激活受体；DAR)做出反应的两种拮抗反射的中枢通路。将解决三个具体目标。目的1采用小群NTS细胞顺行标记和突触靶点逆行标记相结合的方法，对不同类型的SAR和DAR NTS中继神经元的轴突投射进行综合研究。使用同时记录的棘波序列的相互关联的互补性研究将评估这些功能相互作用。在目标2中，单个唯一定义的SAR和DAR中间神经元的细胞旁染料填充及其靶标的逆行标记将允许结合光镜和电子显微镜分析NTS中继神经元与多个靶点的突触连接。在目标3中，将通过NTS神经元及其潜在靶点的细胞旁标记来确定突触后神经元与SAR和DAR NTS中间神经元的电生理定义的表型。棘波触发的平均化将允许表征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。综上所述，这些实验将首次识别SAR和DAR传入神经元的突触后靶点，并提供对肺机械感受器激活产生协调呼吸反射反应的通路的多突触电路图。对这些回路的了解可以阐明以一系列呼吸系统疾病和退行性运动疾病为特征的呼吸道控制受损患者的治疗策略。项目简介：这项研究将研究与调节呼吸的中枢反射有关的脑干回路。通过详细地跟踪从呼吸道和肺部接收信息的神经元的相互连接，我们将以一种以前不可能的方式描述呼吸的力量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症到婴儿猝死综合症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.