Development of swallow evoked potentials as a novel tool to investigate swallowin

描述（由申请人提供）：本研究计划的广泛、长期目标是更好地了解神经系统疾病中吞咽障碍（吞咽困难）的神经病理学。目前存在几种适合并易于用于神经系统疾病转化研究的小鼠模型。然而，由于评估吞咽反射回路中单个神经成分功能的实验方法尚未开发，因此对这些小鼠模型的吞咽功能知之甚少。本研究的目的是开发一种实验方案，利用脑干诱发电位记录对小鼠喉上神经刺激的反应，量化吞咽反射回路的个体感觉、中枢整合和运动成分的功能。三个具体目标将有助于实现这一目的。特异性目的1将验证在小鼠中记录吞咽诱发电位（SwEPs）的假设。以3-4月龄野生型（C57BL/6J）小鼠为实验对象，确定最佳刺激和记录参数。波形形态（即正负峰的数量、峰对峰幅度和峰潜伏期）将相对于以下变量进行比较：电极放置、滤波器设置、信号放大、信号平均、刺激率和刺激幅度。特异性目标2将评估特异性目标1中建立的SwEP测试方案在四个时间点（1、2、3和4个月大）对肌萎缩性侧索硬化症转基因小鼠模型（ALS; SOD1-G93A）和非转基因窝鼠的吞咽功能进行表型分析的实用性。具体目标3将开始研究产生SwEP峰值的源。将采用组织学和免疫组织化学方法对来自Specific Aim 2的一部分动物进行研究，以确定在吞咽过程中被激活的脑干核（和亚核）；这些区域也将被调查组织病理学证据（液泡）。这些发现将指导未来的损伤实验和近场记录研究，以积极识别SwEP响应峰的产生源。这三个具体目标将允许：1)客观量化SOD1-G93A转基因小鼠的吞咽困难，2)描述该品系神经源性吞咽困难的时间过程，以及3)识别该ALS动物模型中吞咽困难的中枢神经相关因素。从这项工作中获得的知识将直接扩展对ALS患者正常吞咽和吞咽困难发病机制的科学认识。此外，这项工作建立的SwEP测试方案有可能用于识别各种神经系统疾病的其他吞咽困难小鼠模型，以及量化各种治疗方法（例如，药理药物，干细胞治疗等）对这些动物模型中吞咽继电器回路单个神经成分功能的影响。因此，这项小鼠实验方案的发展可能最终为神经系统疾病患者的吞咽困难提供新颖有效的治疗方案。

DESCRIPTION (provided by applicant): The broad, long-term objective of this research proposal is to gain a better understanding of the neuropathology of swallowing impairment (dysphagia) in neurological diseases. Several mouse models currently exist that are suitable and readily available for translational research in neurological diseases. However, relatively little is known about the swallowing function of these mouse models because experimental methods to evaluate the function of the individual neural components of the swallow reflex circuit have not yet been developed. The purpose of the proposed research is to develop an experimental protocol for using brainstem evoked potentials recorded in response to stimulation of the superior laryngeal nerve in mice to quantify the function of the individual sensory, central integration, and motor components of the swallowing reflex circuit. Three specific aims will serve this purpose. Specific Aim 1 will test the hypothesis that it is possible to record swallow evoked potentials (SwEPs) in mice. The optimal stimulus and recording parameters will be identified using 3-4 month old wild-type (C57BL/6J) mice. Waveform morphology (i.e., number of positive and negative peaks, peak-to-peak amplitudes, and peak latencies) will be compared relative the following variables: electrode placement, filter settings, signal amplification, signal averaging, stimulus rate, and stimulus amplitude. Specific Aim 2 will evaluate the utility of the SwEP testing protocol established in Specific Aim 1 to phenotype the swallowing function of a transgenic mouse model of amyotrophic lateral sclerosis (ALS; SOD1-G93A) and nontransgenic littermates at four time points: 1, 2, 3, and 4 months of age. Specific Aim 3 will begin to investigate the generator sources for the SwEP peaks. Histological and immunohistochemical methods will be performed on a subset of animals from Specific Aim 2 to identify the brainstem nuclei (and subnuclei) that are activated during swallowing; these regions also will be investigated for evidence of histopathology (vacuoles). The findings will guide future lesioning experiments and near-field recording studies directed toward positive identification of generator sources of SwEP response peaks. These three specific aims will permit: 1) objective quantification of dysphagia in SOD1-G93A transgenic mice, 2) description of the time-course of neurogenic dysphagia in this strain, and 3) identification of the central neural correlates for dysphagia in this animal model of ALS. The knowledge gained from this work will directly extend the scientific knowledge of normal swallowing and the pathogenesis of dysphagia in ALS. In addition, the SwEP testing protocol established by this work has the potential to be used to identify additional mouse models of dysphagia for various neurological diseases, as well as to quantify the effect of various treatments (e.g., pharmacological agents, stem cell therapy, etc.) on the function of the individual neural components of the swallow relay circuit in these animal models. Thus, development of this experimental protocol in mice may ultimately lead to novel and effective treatment options for dysphagia in humans with neurological diseases. PUBLIC HEALTH RELEVANCE: Neurogenic dysphagia (i.e., swallowing impairment caused by neurological disorders such as Lou Gehrig's disease) affects approximately 500,000 individuals, including pediatric and adult populations, annually in the United States. Common symptoms include malnutrition, dehydration, and respiratory complications, all of which may result in a poor quality of life and contribute to death in affected individuals. Few effective treatments for neurogenic dysphagia have been identified; therefore, neurogenic dysphagia is certainly an important area for research that has the potential to benefit hundreds of thousands of individuals living within the United States, as well as many more living beyond these borders, who are afflicted by various neurological diseases.