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.

项目概要/摘要 舌肌由舌下运动神经元 (XIIMN) 支配，对于生存至关重要，因为它们具有 在哺乳、吞咽、咀嚼、呼吸和人类言语等更高级的功能中发挥作用。这 舌下运动核是七个独立运动神经元池的双边集合，运动神经元位于 每个池支配七个不同的舌头肌肉之一。我们最近表明 XIIMN 神经支配 新生大鼠舌上纵肌和颏舌肌静息状态存在显着差异 膜电位、动作电位放电阈值和 f-I 曲线，即放电率随函数的变化 注入电流。这些发现提出了三个非常重要的问题：1） 各个 XIIMN 库内部和之间的表型多样性？ 2）什么是解剖性和离子性 这种表型多样性背后的机制是什么？ 3）XIIMN之间的结构和功能差异 每个库都映射到独特的基因表达谱？我们提出了一种合理而稳健的方法来解决这些问题 问题：具体来说，描述形态、内在膜特性和转录组 肌肉特异性 XIIMN。我们的初始目标是支配颏舌肌、舌舌肌和上颌肌的 XIIMN 纵肌，因为每块肌肉对舌头运动都有不同的影响。肌肉特异性 XIIMN 将 通过向每块肌肉注射与荧光报告剂结合的逆行示踪剂来识别。全部 实验使用 5-12 天龄新生大鼠的脑组织。关键技术包括神经解剖学追踪 定义神经元形态、免疫组织化学、全细胞膜片钳电生理学和下一步 一代RNA测序。这些基础科学研究将确定与相关的独特分子靶标 运动神经元池之间的功能和/或结构差异。如果没有这些基本信息， 旨在刺激或抑制特定舌头肌肉活动的干预措施将是不精确的，并且可能 导致意想不到的结果。相比之下，独特分子靶标的具体知识将集中于 开发旨在刺激和/或抑制特定舌头肌肉的治疗方法。 初步数据显示运动神经元功能和基因表达方面存在一些特定于池的差异，强烈 表明拟议的工作将提供有关解剖学、生理学和分子学的真正新颖的数据 肌肉特异性舌下运动神经元池内部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执行复杂、协调的理解的重大飞跃 睡眠时的吸吮、吞咽、上呼吸道防御等行为，将为 表彰其开发旨在控制特定舌头肌肉活动的疗法。