Genetic Dissection of Nucleus Ambiguus Neurons Controlling Cardiorespiratory Functions

项目总结 心率是衡量整体健康和幸福感的可靠指标，但人们对神经元知之甚少 这就控制了它。虽然心脏有自己的起搏器，但心率在很大程度上是由自主神经调节的。 系统，使其受到交感神经元和副交感神经元(即心脏)之间的相互作用 迷走神经节前神经元(CVN)。CVN控制心脏功能的许多方面，从心率到 房室传导(通过结节组织)到收缩和兴奋性(通过心肌)。 此外，这些神经元与心脏健康高度相关：每当心脏迷走时，心脏死亡率就会增加。 活跃度下降。疑核是延髓网状结构中的一个区域。 脑干容纳了大部分CVN，以及其他已知控制呼吸功能的神经元 (支气管收缩、支气管排泄)，并神经支配上呼吸道和食道肌。此功能 NAMB内神经元的多样性使分离CVN进行研究具有挑战性。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--因此限制了我们的 在心血管疾病的背景下针对这些神经元的能力。为了解决这些问题，我建议 从分子、解剖学和功能上识别CVN的综合方法。我将描述CVN的特征 基于转录组范围的mRNA表达，这将揭示提供遗传基因的转录标记 访问每个NAMB子类型。利用Namb亚型之间的遗传差异，我将跟踪每个亚型 亚型的轴突投射到胸部器官，揭示了CVN的解剖组织。我们的 初步研究指出，NAMB中有三种分子上不同的神经元亚型，其中一种是 它支配着心脏的多个部位。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 呼吸道运动功能。综上所述，这些研究将进一步揭示分子、解剖和 CVN的功能组织，提供对神经元的多维和全面的了解 调节心率的物质。

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.