Purkinje Cell Rhythmicity, Synchrony, and Enhancing Function in Cerebellar Disorders

小脑疾病中浦肯野细胞的节律性、同步性和增强功能

• 批准号: 9490189
• 负责人: JOHN SAMUEL STAHL
• 金额: --
• 依托单位: LOUIS STOKES CLEVELAND VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9490189
• 关键词: 4-Aminopyridine; Abnormal coordination; Address; Affect; Aging; Alcohol abuse; Alcoholism; Aminopyridines; Animals; Anterior; Area; Bathing; Behavior; Behavioral; Biological Assay; Blast Injuries; Blurred vision; Brain Stem; Calcium Channel; Cerebellar Diseases; Cerebellar vermis structure; Cerebellum; Chronic; Clinic; Code; Conflict (Psychology); Data; Disease; Dizziness; Dose; Effectiveness; Engineering; Equilibrium; Exposure to; Eye Movements; Fire - disasters; Functional disorder; Gait; Genes; Genetic Diseases; Goals; Human; In Vitro; Ions; Knowledge; Laboratories; Literature; Mouse Strains; Mus; Mutation; Neurodegenerative Disorders; Neurologist; Neurology; Oral; Pacemakers; Patients; Pattern; Performance; Periodicity; Pharmaceutical Preparations; Physiology; Population; Property; Publishing; Purkinje Cells; Reflex control; Reflex eye movement; Route; Signal Transduction; Stimulus; Stroke; Symptoms; Synapses; Technology; Testing; Time; Trauma; Tremor; Variant; Veterans; Vision; Visual impairment; Work; awake; cell motility; design; drug development; experimental study; falls; improved; improved functioning; in vitro Assay; in vivo; laboratory equipment; neurophysiology; optogenetics; patient subsets; stem; success; theories; transmission process

Because there are so many causes of cerebellar damage (e.g. alcoholism, blast injury, neurodegenerative diseases, stroke, and simple aging), veterans suffering imbalance, visual impairment, and incoordination due to cerebellar damage are common. In the past, neurologists had few therapies to improve function in these patients. Now two emerging ideas in cerebellar physiology hold the promise that better treatments can be rationally designed. The irregularity hypothesis states that cerebellar dysfunction arises when cerebellar Purkinje cells (PCs) fire in irregular patterns through loss of their pacemaker properties. It is cited to explain why drugs that increase PC rhythmicity in vitro such as 4-aminopyridine (4-AP) improve certain manifestations of cerebellar disease in mice and humans, and it predicts their usefulness in a wide range of cerebellar disorders. The PC synchrony hypothesis states that synchrony of firing across multiple PCs determines the effectiveness with which PCs control their synaptic targets, and may explain why PC irregularity – which could disrupt PC synchrony – is deleterious. If correct, these hypotheses indicate how laboratory assays can be used to develop more tolerable and effective drugs. If incorrect, their application to drug development will be futile. Currently, both hypotheses are unproven, and there are data challenging the applicability of the theory to the flocculus and other regions of the vestibulocerebellum, even though it was work in the flocculus that led to the irregularity hypothesis in the first place. This project will address conflicting findings in the literatures on irregularity, 4-AP, and PC synchrony. Like much previous work on the irregularity hypothesis, parts of the proposal will be conducted in the ataxic mouse tottering (tg), which carries a mutation in Cacna1a, the gene encoding the ion pore subunit of the P/Q calcium channel. We focus on the flocculus and its control of reflex eye movements that maintain clear vision, because their physiology is well understood, because work in this area provides both support and challenges to the irregularity and synchrony hypotheses, because eye movement and related balance abnormalities contribute significantly to the symptoms of cerebellar disease, and because successes to date predict their treatment is possible. Specific Aim 1 will investigate why bath-applied 4-AP restores regularity of tg vermis PCs in vitro, and oral 4-AP improves tg's performance on the rotarod, but parenterally administered 4-AP does not improve tg's eye movement deficits that are attributed to flocculus dysfunction. We will test the possibilities that the conundrum arises through non-validity of the irregularity hypothesis, or through regional variations in cerebellar physiology, or through differing effects of chronic oral vs. short-term parenteral exposure to 4-AP. Specific Aim 2 addresses the idea that PC irregularity disrupts the PC-PC synchrony on which normal cerebellar function depends. We will test that explanation by determining whether PC synchrony is in fact reduced in tg. As in Aim 1, to address the possibility of regional variations of physiology, we will record in the flocculus and in a non- vestibulocerebellar region of the vermis. Specific Aim 3 addresses a prediction of the posited linkage between irregularity and PC synchrony: If these ideas apply to the flocculus, then variations in PC firing rate should drive eye movements more robustly when the PCs fire more synchronously. Making use of an optogenetic mouse strain whose PCs express channelrhodopsin, we will stimulate PCs with patterns of photostimulation predicted to trigger PC firing with varying degrees of synchrony. Through recordings of PC firing rates and eye movements, we will quantify and compare the efficiency with which flocculus signals are transferred to subsequent circuitry. The results of this proposal will have broad implications for the general validity of the irregularity hypothesis, the usefulness and limitations of in vitro regularity assays in drug development, and predicting which cerebellar disorders might respond to 4-AP.

由于小脑损伤的原因很多（如酒精中毒、爆炸伤、神经退行性病变）， 疾病，中风和单纯衰老），退伍军人遭受不平衡，视力障碍和不协调 因为小脑损伤而导致的脑损伤很常见在过去，神经科医生几乎没有治疗方法来改善功能， 这些病人。现在，小脑生理学中的两个新兴观点有望使更好的治疗方法 可以合理设计。不规则假说指出，小脑功能障碍出现时， 小脑浦肯野细胞（PC）通过失去其起搏特性而以不规则模式放电。是 引用来解释为什么在体外增加PC节律性的药物，如4-氨基吡啶（4-AP）， 在小鼠和人类中小脑疾病的某些表现，它预测了它们在广泛的 一系列小脑疾病PC同步假说指出，在多个区域中， PC决定了PC控制其突触目标的有效性，并可能解释为什么PC 不规则性--可能破坏PC同步--是有害的。如果是正确的，这些假设表明 实验室分析可用于开发更耐受和更有效的药物。如果不正确，其应用 药物研发都是徒劳的目前，这两种假设都未经证实，有数据表明， 挑战了该理论对前庭小脑的小叶和其他区域的适用性， 尽管最初是对小叶的研究导致了不规则假说。这 该项目将解决文献中关于不规则性、4-AP和PC同步性的矛盾结果。像 许多以前的工作不规则假说，部分建议将进行共济失调 小鼠tottering（tg），它携带Cacna 1a突变，Cacna 1a是编码细胞膜离子孔亚基的基因。 P/Q钙通道。我们专注于小叶及其对反射性眼球运动的控制， 清晰的视野，因为他们的生理学是很好的理解，因为在这一领域的工作提供了支持， 以及对不规则性和同步性假设的挑战，因为眼球运动和相关的平衡 异常有助于显着小脑疾病的症状，因为成功， 日期预测他们的治疗是可能的。具体目标1将研究为什么浴应用4-AP恢复 体外培养tg蚓部PCs的规律性，口服4-AP可改善tg在转棒上的表现， 胃肠外给药4-AP不能改善TG的眼球运动缺陷， 绒球功能障碍我们将测试的可能性，这个难题产生的非有效性， 不规则假说，或通过小脑生理学的区域变化，或通过不同的影响， 慢性口服与短期胃肠外暴露于4-AP的对比。具体目标2解决了PC 不规则性破坏了正常小脑功能所依赖的PC-PC同步性。我们会测试的 通过确定PC同步是否实际上在tg中减少来解释。与目标1一样，为了解决 生理学的区域变化的可能性，我们将记录在小叶和非- 蚓部的前庭小脑区。具体目标3解决了对假定联系的预测 不规则性和PC同步性之间：如果这些想法适用于小叶，那么PC放电的变化 当PC更同步地启动时，频率应该更有力地驱动眼球运动。利用一个 光遗传学小鼠品系的PC表达通道视紫红质，我们将刺激PC的模式， 预测光刺激以不同程度的同步触发PC放电。通过记录 PC的发射率和眼球运动，我们将量化和比较的效率， 信号被传输到后续电路。这一提议的结果将产生广泛的影响 对于不规则假说的普遍有效性，体外规则性的有用性和局限性， 用于药物开发的分析，以及预测哪些小脑疾病可能对4-AP有反应。