Neurophysiology of breathing behavior in neonatal mice in vitro

描述（由申请人提供）：这个R01项目将促进我们对人类和所有哺乳动物产生和控制呼吸行为的脑干神经回路的理解。呼吸是心肺生理学的一个组成部分，了解其神经起源对人类健康具有重要意义。节律性呼吸运动始于胚胎发育时期，由脑干呼吸神经元的协调活动发出。一个产生节奏的关键神经元群包含在一个叫做preB"tzinger complex （preB"tC）的部位。preB"tC的发现使许多强大的实验成为可能，这些实验可以在体外进行，并导致我们当代对呼吸神经生理学的理解。然而，关键问题仍未得到解答。鉴于preB"tC中呼吸相关和非呼吸神经元的异质性，我们能否发现哪些神经元是关键的节律产生者？如果产生节律的神经元能够被识别出来（我们认为它们确实可以），那么我们能否确定节律产生背后的细胞、突触和分子水平的机制？最后，在过去的十年中，人们已经广泛认识到多肽能调节呼吸节律的重要性，但其潜在的生物物理机制仍然不完全清楚。本项目通过研究体外薄脑干切片制剂中的preB“tC”来寻求这些具体问题的答案。SPECIFIC AIM 1将评估preB"tC的细胞组成。转基因小鼠模型将用于将荧光标记应用于遗传上不同的亚群，然后选择性地和连续地损伤它们，以测试它们在节律发生中的各自作用。SPECIFIC AIM 2将研究产生吸气相关脉冲的突触-树突活性膜特性。特异性目的3将研究突触前抑制兴奋性传递是否有助于突发终止。SPECIFIC AIM 4旨在通过检查突触后膜特性来补充SPECIFIC AIM 3，这些特性也可以终止吸气爆发。最后，SPECIFIC AIM 5将确定关键神经肽（和其他神经信使）呼吸调节的离子通道。在这个项目中获得的新知识将有助于治疗和预防由大脑和中枢神经系统衰竭引起的呼吸障碍。此外，在体外受控条件下研究可测量的行为，如呼吸，有助于揭示将神经元、突触和分子与全面生理行为联系起来的重要原理，这将在神经科学和心肺生理学中引起极大的兴趣。

DESCRIPTION (provided by applicant): This R01 project will advance our understanding of the brainstem neural circuits that generate and control breathing behavior in humans and all mammals. Breathing is an integral part of cardiopulmonary physiology and understanding its neural origins has significant implications for human health. Rhythmic breathing movements begin during embryonic development and emanate from coordinated activity in brainstem respiratory neurons. One key population of rhythm-generating neurons is contained in a site called the preB"tzinger complex (preB"tC). The discovery of the preB"tC made possible many powerful experiments that could be performed in vitro, and led to our contemporary understanding of the neurophysiology of respiration. Nevertheless, critical questions remain unanswered. Given the heterogeneity of respiratory-related and non-respiratory neurons in the preB"tC, can we discover which neurons are the key rhythm generators? If rhythmogenic neurons can be identified (and we argue that indeed they can), then can we ascertain the cellular, synaptic, and molecular-level mechanisms that underlie rhythm generation? Finally, the importance of peptidergic modulation of respiratory rhythm has been widely recognized in the past decade, but its underlying biophysical mechanisms remain incompletely understood. This project seeks answers to these specific questions by studying the preB"tC in thin brainstem slice preparations in vitro. SPECIFIC AIM 1 will evaluate the cellular composition of the preB"tC. Transgenic mouse models will be used to apply fluorescent tags to genetically distinct sub-populations, and then selectively and serially lesion them to test their respective roles in rhythmogenesis. SPECIFIC AIM 2 will examine the synaptic-dendritic active membrane properties that generate inspiratory-related bursts. SPECIFIC AIM 3 will investigate whether presynaptic depression of excitatory transmission contributes to burst termination. SPECIFIC AIM 4 is designed to complement SPECIFIC AIM 3 by examining the postsynaptic membrane properties that also act to terminate inspiratory bursts. Finally, SPECIFIC AIM 5 will determine the ion channels that underlie respiratory modulation by key neuropeptides (and other neuromessengers). The new knowledge acquired during this project will aid in the treatment and prophylaxis of breathing disorders that result from failures in the brain and central nervous system. Moreover, studying a measurable behavior like breathing under controlled in vitro conditions helps reveal important principles that link neurons, synapses, and molecules to full-scale physiological behaviors, which will be of great interest in neuroscience as well as cardiopulmonary physiology.