Genetic Dissection of Nucleus Ambiguus Neurons Controlling Cardiorespiratory Functions

项目摘要 心率是一个公认的整体健康和幸福的指标，但对神经元知之甚少 虽然心脏有自己的起搏器，但心率主要由自主神经调节。 系统，使其经受交感神经元和副交感神经元之间的相互作用（即，心脏 迷走神经节前神经元（CVNs））。CVN控制心脏功能的许多方面， 和房室传导（通过结组织）到收缩性和兴奋性（通过心室心肌）。 此外，这些神经元与心脏健康高度相关：心脏死亡率增加时， 活动减少。疑核（nAmb）是延髓网状结构中的一个区域， 脑干，容纳大多数CVN，沿着其他已知控制呼吸功能的神经元 （支气管收缩、支气管分泌）并支配上气道和食管肌肉。该功能 nAmb内神经元的多样性使得分离用于研究的CVN具有挑战性。这极大地限制了 我们知道它们的基因表达、突触回路和在心脏功能中的特定作用，因此限制了我们对它们的研究。 在心血管疾病中靶向这些神经元的能力。为了解决这些问题，我提出了一个 全面的方法，以确定CVN的分子，解剖学和功能。我将描述CVN 基于转录组范围的mRNA表达，这将揭示提供遗传信息的转录标记。 访问每个nAmb子类型。利用nAmb亚型之间的遗传差异， 亚型的轴突投射到胸部器官，揭示了CVN的解剖组织。我们 初步研究指出，nAmb中存在三种分子上不同的神经元亚型， 它支配心脏的多个部位。最后，为了揭示每个亚型的生理作用，我将激活 每种亚型使用交叉光遗传学，同时评估对心率、呼吸和上肢的影响。 气道运动功能总之，这些研究将进一步揭示分子，解剖学， CVN的功能组织，提供对神经元的多维和全面的理解 介导心率。

PROJECT SUMMARY Heart rate is a well-established indicator of overall health and well-being, yet little is known about the neurons that control it. Although the heart has its own pacemaker, heart rate is largely regulated by the autonomic nervous system, subjecting it to the interplay between sympathetic neurons and parasympathetic neurons (i.e., cardiac vagal preganglionic neurons (CVNs)). CVNs control many aspects of cardiac function, ranging from heart rate and atrioventricular conductance (via nodal tissue) to contractility and excitability (via ventricular myocardium). Furthermore, these neurons are highly relevant to heart health: cardiac mortality increases whenever cardiovagal activity is diminished. The nucleus ambiguus (nAmb), a region in the medullary reticular formation of the brainstem, houses the majority of CVNs, along with other neurons that are known to control respiratory functions (bronchoconstriction, bronchosecretion) and innervate upper airway and esophageal muscles. This functional diversity of neurons within the nAmb makes it challenging to isolate CVNs for study. This has greatly limited what we know about their gene expression, synaptic circuitry, and specific roles in cardiac function—thus limiting our ability to target these neurons in the context of cardiovascular diseases. To address these issues, I propose a comprehensive approach to identify CVNs molecularly, anatomically, and functionally. I will characterize CVNs based on transcriptome-wide mRNA expression, which will reveal transcriptional markers that provide genetic access to each nAmb subtype. Leveraging the genetic differences between nAmb subtypes, I will trace each subtype’s axonal projections to thoracic organs, revealing the anatomical organization of the CVNs. Our preliminary studies have pointed to three molecularly distinct neuron subtypes localized in the nAmb, one of which innervates multiple sites in the heart. Lastly, to uncover each subtype’s physiological role, I will activate each subtype using intersectional optogenetics while assessing the effect on heart rate, respiration, and upper airway motor function. Taken together, these studies will further uncover the molecular, anatomical, and functional organization of CVNs, providing a multi-dimensional and comprehensive understanding of the neurons that mediate heart rate.