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: 9346859
• 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/9346859
• 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; Goals; Hereditary Disease; 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.

因为造成小脑损伤的原因有很多（例如酗酒、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、视力障碍和不协调的困扰 由于小脑损伤很常见。过去，神经科医生几乎没有改善神经功能的疗法 这些病人。现在，小脑生理学中的两个新兴观点有望提供更好的治疗方法 可以合理设计。不规则假说指出，小脑功能障碍发生在以下情况： 小脑浦肯野细胞 (PC) 由于失去起搏器特性而以不规则的模式放电。这是 被引用来解释为什么在体外增加 PC 节律性的药物（例如 4-氨基吡啶 (4-AP)）可以改善 小鼠和人类小脑疾病的某些表现，并预测它们在广泛的用途 小脑疾病的范围。 PC 同步假说指出，多个设备之间的发射同步 PC 决定 PC 控制其突触目标的有效性，并可以解释为什么 PC 不规则性——可能会破坏电脑同步——是有害的。如果正确，这些假设表明如何 实验室测定可用于开发更耐受和更有效的药物。如果不正确，他们的申请 药物研发将是徒劳的。目前，这两种假设均未得到证实，并且有数据 挑战该理论对绒球和前庭小脑其他区域的适用性， 尽管正是绒球的作用首先导致了不规则性假说。这 该项目将解决有关不规则性、4-AP 和 PC 同步性的文献中相互矛盾的发现。喜欢 先前关于不规则性假设的许多工作，该提案的部分内容将在共济失调中进行 小鼠摇摇欲坠 (tg)，其携带 Cacna1a 突变，Cacna1a 是编码小鼠离子孔亚基的基因 P/Q钙通道。我们重点关注小叶及其对反射性眼球运动的控制，以维持 清晰的视野，因为他们的生理机能很好地了解，因为这方面的工作提供了支持 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 异常对小脑疾病的症状有显着影响，并且因为成功 日期预测他们的治疗是可能的。具体目标 1 将调查为什么浴应用 4-AP 会恢复 体外 tg 蚓 PC 的规律性，口服 4-AP 可以提高 tg 在旋转棒上的性能，但是 肠外给予 4-AP 并不能改善 tg 的眼球运动缺陷，该缺陷归因于 絮球功能障碍。我们将测试因无效性而产生难题的可能性 不规则假说，或通过小脑生理学的区域差异，或通过不同的影响 长期口服与短期肠外暴露于 4-AP 的比较。具体目标 2 阐述了 PC 不规则性会破坏正常小脑功能所依赖的 PC-PC 同步。我们将测试一下 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 生理学区域差异的可能性，我们将记录在絮状和非 蚓部的前庭小脑区域。具体目标 3 解决了对所假定的联系的预测 不规则性和 PC 同步之间：如果这些想法适用于絮状体，那么 PC 发射的变化 当 PC 更加同步地发射时，速率应该更强劲地驱动眼球运动。利用一个 其 PC 表达视紫红质通道的光遗传学小鼠品系，我们将用以下模式刺激 PC 光刺激预计会以不同程度的同步触发 PC 放电。通过录音 PC发射率和眼球运动，我们将量化并比较絮状的效率 信号被传输到后续电路。该提案的结果将产生广泛的影响 对于不规则性假设的一般有效性，体外规则性的有用性和局限性 药物开发中的检测，并预测哪些小脑疾病可能对 4-AP 产生反应。