Functional and Structural Diversity in Hypoglossal Motoneurons

舌下运动神经元的功能和结构多样性

• 批准号: 10608440
• 负责人: Ralph Frank Fregosi
• 金额: $ 44.76万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-12-01 至 2026-11-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10608440
• 关键词: Action Potentials; Address; Age; Anatomy; Basic Science; Behavior; Bilateral; Birth; Brain Stem; Breathing; Cell Nucleus; Cells; Collection; Complex; Data; Deglutition; Dendrites; Electrophysiology (science); Fluorescence-Activated Cell Sorting; Foundations; Gene Expression; Genetic; Human; Immunohistochemistry; In Vitro; Individual; Intervention; Ion Channel; Knowledge; Maps; Mastication; Membrane; Membrane Potentials; Molecular; Molecular Target; Morphology; Motor; Motor Neurons; Movement; Muscle; Nature; Neonatal; Neuroanatomy; Neurons; Neurotransmitter Receptor; Outcome; Pattern; Performance; Phenotype; Physiological; Property; Publishing; Rattus; Reporter; Rest; Role; Sleep; Slice; Speech; Synapses; Techniques; Tissue-Specific Gene Expression; Tongue; Tracer; Work; brain tissue; experimental study; genioglossus muscle; innovation; next generation; novel; patch clamp; pharmacologic; receptor expression; suckling; therapeutic development; therapy development; transcriptome; transcriptome sequencing; transcriptomics; voltage

PROJECT SUMMARY/ABSTRACT Tongue muscles, which are innervated by hypoglossal motoneurons (XIIMNs), are critical for survival given their role in suckling, swallowing, mastication, breathing and more advanced functions such as human speech. The hypoglossal motor nucleus is a bilateral collection of seven separate motoneuron pools, with motoneurons in each pool innervating one of the seven different tongue muscles. We recently showed that XIIMNs innervating the superior longitudinalis and genioglossus tongue muscles of neonatal rats have significantly different resting membrane potentials, action potential firing thresholds, and f-I curves, i.e., the change in firing rate as a function of injected current. These findings raise three very important questions: 1) what is the extent and nature of phenotypic diversity both within and between individual XIIMN pools? 2) what are the anatomic and ionic mechanisms that underlie this phenotypic diversity? 3) do structural and functional differences among XIIMNs in each pool map to unique gene expression profiles? We propose a rational and robust approach to address these questions: specifically, to describe the morphology, intrinsic membrane properties, and the transcriptome of muscle specific XIIMNs. Our initial targets are XIIMNs innervating the genioglossus, hyoglossus and superior longitudinalis muscles, as each muscle has different effects on tongue movement. Muscle-specific XIIMNs will be identified by injecting each of the muscles with a retrograde tracer conjugated to a fluorescent reporter. All experiments use brain tissue from neonatal rats 5-12 days of age. Key techniques include neuroanatomic tracing to define neuron morphology, immunohistochemistry, whole cell patch clamp electrophysiology and next- generation RNA sequencing. These basic science studies will identify unique molecular targets associated with functional and/or structural differences between the motoneuron pools. Without this fundamental information, interventions aimed at stimulating or inhibiting the activity of specific tongue muscles will be imprecise and may result in unintended outcomes. In contrast, specific knowledge of unique molecular targets will focus the development of therapeutic approaches aimed at stimulation and/or inhibition of specific tongue muscles. Preliminary data show several pool-specific differences in motoneuron function and gene expression, strongly suggesting that the proposed work will provide truly novel data on the anatomic, physiologic, and molecular underpinnings of phenotypic diversity within and between muscle-specific hypoglossal motoneuron pools. This, in turn, will lead to a major leap in our understanding of how the tongue muscles perform complex, coordinated behaviors such as suckling, swallowing, and defense of the upper airway during sleep, and will lay the foundation for the development of therapies aimed at controlling the activity of specific tongue muscles.

项目摘要/摘要 舌头肌肉是由降压运动神经元（XIIMN）支配的，鉴于其生存至关重要 在哺乳，吞咽，咀嚼，呼吸和更先进的功能（例如人类言语）中的作用。这 降压运动核是七个单独的运动神经元池的双边收集，并在运动神经元中 每个池介绍了七个不同的舌头肌肉之一。我们最近表明XIIMNS支配 新生大鼠的上纵向和Genioglossus舌头肌肉的静止 膜电位，动作电势发射阈值和F-I曲线，即发射速率随功能的变化 注射电流。这些发现提出了三个非常重要的问题：1） 单个XIIMN池之间和之间的表型多样性？ 2）解剖和离子是什么 这种表型多样性的基础的机制？ 3）在xiimns中进行结构和功能差异 每个池图到独特的基因表达曲线？我们提出了一种理性和强大的方法来解决这些问题 问题：具体来说，要描述形态，内在膜特性和转录组 肌肉特异性XIIMN。我们的最初目标是XIIMNS支配Genioglossus，Hyoglossus和Superior 纵向肌肉，因为每个肌肉对舌头运动都有不同的影响。肌肉特异性的Xiimns会 可以通过将每个肌肉的逆行示踪剂连接到荧光报告基因来识别。全部 实验使用来自新生大鼠的脑组织5-12天。关键技术包括神经解剖学跟踪 定义神经元的形态，免疫组织化学，全细胞贴片夹电生理学和下一步 生成RNA测序。这些基础科学研究将确定与 运动神经元池之间的功能和/或结构差异。没有这些基本信息， 旨在刺激或抑制特定舌头肌肉活性的干预措施将不精确，并且可能 导致意外的结果。相反，对独特分子靶标的特定知识将集中在 旨在刺激和/或抑制特定舌头肌肉的治疗方法的发展。 初步数据显示了运动神经元功能和基因表达的几种池特异性差异，强烈 提出的工作将提供有关解剖，生理和分子的真正新数据 在肌肉特异性降压运动神经元池内和之间表型多样性的基础。这， 反过来，将导致我们对舌头肌肉如何表现复杂，协调的理解有了重大飞跃 睡眠期间的哺乳，吞咽和防御诸如哺乳，吞咽和防御等行为，并将奠定基础 为了开发旨在控制特定舌肌活动的疗法。