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

描述(申请人提供)：这项研究提案的广泛、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。目前有几种小鼠模型适用于神经疾病的转化性研究，而且很容易获得。然而，对这些小鼠模型的吞咽功能知之甚少，因为还没有开发出评估吞咽反射回路单个神经组件功能的实验方法。这项研究的目的是开发一种实验方案，利用刺激小鼠喉上神经时记录的脑干诱发电位来量化吞咽反射回路的单个感觉、中枢整合和运动部件的功能。三个具体目标将服务于这一目的。《特定目标1》将检验这样一种假设，即可以在小鼠身上记录燕子诱发电位(SwEP)。最佳的刺激和记录参数将在3-4月龄的野生型(C57BL/6J)小鼠身上确定。波形形态(即正负峰数、峰间波幅和波峰潜伏期)将相对于以下变量进行比较：电极位置、滤波器设置、信号放大、信号平均、刺激率和刺激幅度。特定目的2将评估在特定目的1中建立的SWEP测试方案在4个时间点：1、2、3和4个月龄时对肌萎缩侧索硬化症(ALS；SOD1-G93A)转基因小鼠模型和非转基因小鼠的吞咽功能进行表型的有效性。具体目标3将开始调查SWEP峰值的产生源。组织学和免疫组织化学方法将在特定目标2的动物子集上进行，以确定吞咽过程中激活的脑干核(和亚核)；这些区域也将被调查以寻找组织病理学的证据(空泡)。这些发现将指导未来的损伤实验和近场记录研究，旨在积极识别SWEP响应峰值的发生器来源。这三个特定目标将允许：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)在ALS动物模型中识别吞咽困难的中枢神经相关因素。这项工作所获得的知识将直接扩展ALS患者正常吞咽和吞咽困难发病机制的科学知识。此外，这项工作建立的SWEP测试方案有可能用于识别其他各种神经系统疾病的吞咽困难小鼠模型，以及量化各种治疗方法的效果(例如，药物、干细胞治疗等)。在这些动物模型中，吞咽中继回路的单个神经组件的功能。因此，在小鼠身上开发这一实验方案可能最终导致治疗患有神经系统疾病的人类吞咽困难的新的和有效的治疗方案。 公共卫生相关性：神经性吞咽困难(即由卢格里克病等神经疾病引起的吞咽障碍)在美国每年影响大约500,000人，包括儿童和成人。常见症状包括营养不良、脱水和呼吸道并发症，所有这些都可能导致受影响个人的生活质量下降并导致死亡。神经源性吞咽困难的有效治疗方法还很少；因此，神经源性吞咽困难肯定是一个重要的研究领域，有可能使生活在美国境内的数十万人以及生活在这些边界以外的更多人受益，他们受到各种神经系统疾病的困扰。

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.