Neurophysiology of breathing behavior in neonatal mice in vitro

描述（由申请人提供）：该 R01 项目将增进我们对产生和控制人类和所有哺乳动物呼吸行为的脑干神经回路的理解。呼吸是心肺生理学不可或缺的一部分，了解其神经起源对人类健康具有重要意义。有节奏的呼吸运动始于胚胎发育期间，源自脑干呼吸神经元的协调活动。节律生成神经元的一个关键群体包含在一个称为前 B"tzinger 复合体 (preB"tC) 的位点中。 preB"tC 的发现使得许多可以在体外进行的强大实验成为可能，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。考虑到 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发生器？如果可以识别节律发生神经元（我们认为确实可以），那么我们是否可以确定节律产生背后的细胞、突触和分子水平机制？最后，肽能调节呼吸节律的重要性在过去十年中已得到广泛认识，但其潜在的生物物理机制仍不完全清楚。该项目通过在体外研究薄脑干切片制剂中的 preB"tC 来寻求这些具体问题的答案。具体目标 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签应用于遗传上不同的亚群，然后选择性地连续损伤它们以测试它们各自在节律发生中的作用。具体目标 2 将检查产生吸气相关爆发的突触树突活性膜特性。具体目标 3 将研究兴奋性传递的突触前抑制是否有助于突发终止。 SPECIFIC AIM 4 旨在通过检查也可终止吸气爆发的突触后膜特性来补充 SPECIFIC AIM 3。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。该项目中获得的新知识将有助于治疗和预防因大脑和中枢神经系统故障而导致的呼吸障碍。此外，研究可测量的行为，如在受控体外条件下的呼吸，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，这将引起神经科学和心肺生理学的极大兴趣。

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.