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.

因为有很多小脑损伤的原因（例如酒精中毒，爆炸损伤，神经退行性 疾病，中风和简单衰老），退伍军人遭受失衡，视觉障碍和不协调 由于小脑损伤，很常见。过去，神经科医生几乎没有疗法来改善功能 这些患者。现在，小脑生理学中的两个新兴想法持希望是更好的治疗 可以合理设计。不规则性假设指出，小脑功能障碍会发生 小脑浦肯野细胞（PC）通过失去起搏器特性以不规则的模式发射。这是 引用解释为什么会增加体外PC节奏性的药物，例如4-氨基吡啶（4-AP） 小脑和人类小脑病的某些表现，它可以预测它们在广泛的 小脑疾病范围。 PC同步假设指出，跨多个发射的同步 PC确定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 - 可能破坏PC同步 - 是有害的。如果正确，这些假设表示如何 实验室测定可用于开发更可耐受和有效的药物。如果不正确，他们的申请 药物开发将是徒劳的。目前，这两个假设都未经证实，并且有数据 挑战该理论对絮凝池和其他区域的适用性， 即使是在絮凝中起作用的，首先导致了不规则性假设。这 项目将解决有关违规，4-AP和PC同步的文献中矛盾的发现。喜欢 关于不规则性假设的许多先前的工作，该提案的一部分将在共同的情况下进行 小鼠tottering（tg），它在cacna1a中携带突变，该基因编码了离子孔亚基的基因 P/Q钙通道。我们专注于絮凝及其对维持反射眼运动的控制 明确的视野，因为他们的生理学已经充分理解，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假设的挑战，因为眼动和相关平衡 异常对小脑病的症状产生了重大贡献，并且因为成功 日期预测他们的治疗是可能的。特定目标1将调查为什么沐浴4-AP还原 TG Vermis PC在体外的规律性和口服4-AP可改善TG在Rotarod上的性能，但 属于4-AP的属于肠胃外并不能改善TG的眼动定义归因于 絮凝功能障碍。我们将测试通过非毒性而产生的难题的可能性 不规则性假设，或通过小脑生理学的区域变化或通过不同的影响 慢性口服与短期肠胃外暴露于4-AP。特定目标2解决了PC的想法 不规则性破坏了正常小脑功能的PC-PC同步。我们将测试 通过确定PC同步是否实际上减少了TG中的解释。就像在AIM 1中一样，要解决 生理学区域变化的可能性，我们将记录在絮凝物和非 - vermis的前庭脑区域。特定目标3解决了海报联系的预测 在不规则性和PC同步之间 当PC更加同步发射时，速率应更加强大。利用 Opto遗理小鼠菌株的PC表达通道Ropopsin，我们将用模式刺激PC 预测的光刺激会触发不同程度同步的PC触发。通过录音 PC发射速率和眼动，我们将量化和比较絮凝的效率 信号转移到随后的电路中。该提案的结果将具有广泛的影响 对于不规则性假设的一般有效性，体外规律性的有用性和局限性 药物开发的测定，并预测哪些小脑疾病可能会对4AP做出反应。