Hippocampal neurotoxicity induced by ethanol withdrawal

乙醇戒断引起的海马神经毒性

• 批准号: 6897859
• 负责人: JOHN M. LITTLETON
• 金额: $ 36.83万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6897859
• 关键词: NMDA receptors; autoradiography; calcium channel blockers; calcium flux; drug withdrawal; ethanol; fluorescence microscopy; glutamate receptor; glutamates; high performance liquid chromatography; hippocampus; laboratory rat; neurotoxicology; neurotransmitter antagonist; neurotransmitter transport; polyamines; protein localization; protein structure function; radiotracer; receptor sensitivity; tissue /cell culture

DESCRIPTION (provided by applicant): A model system has been developed utilizing organotypic cultures of rat hippocampus in which a single cycle of ethanol exposure and removal results in significant "spontaneous" neuronal death, mainly in the pyramidal cells of the CA1 region. This in vitro model is potentially valuable for understanding the mechanisms underlying alcoholic brain damage, arguably the most important preventable cause of dementia in the USA. The data obtained thus far suggest that, in this model, neuronal damage is mostly excitotoxic and occurs during ethanol withdrawal. The primary hypothesis is that ethanol-induced adaptations in the glutamatergic system lead, on withdrawal of ethanol, to a cascade of changes including synaptic hyperactivity, network excitation, and excess release of endogenous glutamate and polyamines. These mediators then co-activate glutamate/NMDA receptors (NMDARs) that may be "supersensitive" to both agents, and which cause toxic Ca2+ entry. The primary specific aim is test these hypotheses and to elucidate the pre-synaptic and post-synaptic mechanisms that lead to withdrawal-induced toxicity in this model. Selective antagonists for ionotropic and metabotropic glutamate receptors and calcium channels will be used to probe mechanisms for initial synaptic excitation (calcium orange fluorescence microscopy), release of glutamate and polyamines (HPLC), distribution and sensitivity of NMDARs ([125I]MK801 autoradiography) and the relation between cumulative Ca2+ uptake (radiotracer 45Ca2+) and neurotoxicity (propidium iodide fluorescence microscopy). A second major aim is to investigate the role of network excitation in these changes by studying effects of transecting neural pathways within the culture on these parameters. Mechanisms that rely on transsynaptic activation should be prevented by this procedure. All studies in the project will focus on the regional distribution of toxicity within the slice culture, and the mechanisms that contribute to this distribution. In addition to testing the hypotheses, these experiments should suggest novel therapeutic interventions into alcohol-induced neurodegenerative disease, and elucidate why specific neuronal phenotypes are susceptible to alcohol withdrawal. Both are research priorities in the recent NIAAA Review of Neuroscience and Behavioral Science Portfolio.

描述（由申请人提供）：利用大鼠海马体的器官型培养物开发了模型系统，其中乙醇暴露和去除的单周期导致显着的“自发”神经元死亡，主要发生在CA1区域的锥体细胞中。这种体外模型对于理解酒精性脑损伤的潜在机制具有潜在价值，酒精性脑损伤可以说是美国痴呆症最重要的可预防原因。迄今为止获得的数据表明，在该模型中，神经元损伤主要是兴奋毒性的，并且发生在乙醇戒断期间。主要假设是，乙醇诱导的谷氨酸能系统适应会在乙醇退出时导致一系列变化，包括突触过度活跃、网络兴奋以及内源性谷氨酸和多胺的过量释放。然后，这些介质共同激活谷氨酸/NMDA 受体 (NMDAR)，后者可能对两种药物都“超级敏感”，并导致有毒的 Ca2+ 进入。主要具体目标是测试这些假设并阐明导致该模型中戒断毒性的突触前和突触后机制。离子型和代谢型谷氨酸受体和钙通道的选择性拮抗剂将用于探测初始突触激发的机制（钙橙荧光显微镜）、谷氨酸和多胺的释放（HPLC）、NMDAR 的分布和敏感性（[125I]MK801 放射自显影）和累积 Ca2+ 摄取（放射性示踪剂 45Ca2+）与神经毒性（碘化丙啶荧光显微镜）之间的关系。第二个主要目标是通过研究培养物中横断神经通路对这些参数的影响来研究网络激励在这些变化中的作用。此过程应防止依赖突触激活的机制。该项目的所有研究将集中于切片培养物中毒性的区域分布，以及促成这种分布的机制。除了检验假设之外，这些实验还应该对酒精引起的神经退行性疾病提出新的治疗干预措施，并阐明为什么特定的神经元表型容易受到酒精戒断的影响。两者都是最近 NIAAA 神经科学和行为科学组合审查中的研究重点。