Molecular Determinants of Mossy Fiber Presynaptic Channelopathies in Epilepsy

癫痫苔藓纤维突触前通道病的分子决定因素

• 批准号: 7289098
• 负责人: Emilio Rafael Garrido Sanabria
• 金额: $ 25.37万
• 依托单位: UNIV/TEXAS BROWNSVILLE & SOUTHMOST COLL
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7289098
• 关键词: Affect; Agonist; Agreement; Antiepileptic Agents; Applications Grants; Area; Attenuated; Autoreceptors; Axon; Brain; Cells; Chromosome Pairing; Chronic; DNA Sequence Rearrangement; Data; Depressed mood; Development; Disease; Down-Regulation; Dyes; Epilepsy; Epileptogenesis; Excision; Feedback; Fiber; Foundations; Functional disorder; Funding; Future; Gene Mutation; Genetic; Glutamates; Goals; Hand; Hippocampal Mossy Fibers; Hippocampus (Brain); Human; Imagery; Immunoliposome; Inherited; Ion Channel; Link; Long-Term Depression; Mediating; Messenger RNA; Metabotropic Glutamate Receptors; Modeling; Molecular; Monitor; Mutate; Neurons; Neurotransmitter Receptor; Operative Surgical Procedures; Pathogenesis; Pathway interactions; Patients; Personal Satisfaction; Phenotype; Play; Polymerase Chain Reaction; Potassium Channel; Protease Inhibitor; Pyramidal Cells; RNA Splicing; Rattus; Recurrence; Reporting; Research; Role; Score; Seizures; Synapses; Techniques; Temporal Lobe Epilepsy; Testing; Therapeutic Intervention; Time; Tissues; Transcript; Variant; cell type; dentate gyrus; gene therapy; granule cell; innovation; large-conductance calcium-activated potassium channels; metabotropic glutamate receptor 2; mossy fiber; nerve supply; neuronal excitability; neurotransmission; novel; novel therapeutics; patch clamp; postsynaptic; presynaptic; receptor; response; synaptogenesis; transmission process

DESCRIPTION (provided by applicant): Epilepsies are a diverse group of paroxysmal disorders that have been linked to genetic or acquired ion channel and/or neurotransmitter receptor dysfunctions, the so-called "channelopathies." The hippocampal mossy fibers undergo molecular and structural rearrangement in human and experimental mesial temporal lobe epilepsy (MTLE). Recent data revealed a robust down-regulation of both group II metabotropic glutamate receptors (mGluR II) and the large conductance Ca2+activated potassium channel (BK channels) in mossy fibers of epileptic rats. In the normal brain, "feedback" activation of presynaptic autoreceptor mGluR II in concert with other ion channels (i.e., BK channels) attenuates excessive excitatory transmission. Hence, presynaptic deficit in mGluR II and BK channels may play a major role in epileptogenesis. The specific aims of this project are: (1) to test the hypothesis that down-regulation of mGluR II and BK channels in mossy fiber of epileptic rats correlates with similar deficit in mRNA transcripts and abnormal expression of splice variants in granule cells; (2) to test the hypothesis that seizure-induced down-regulation of mGluR II and BK channels affects presynaptic function and exacerbates excitatory transmission at mossy fiber-CA3 pyramidal cell synapses in an experimental MTLE; and (3) to determine whether mGluR II and BK channels can attenuate excessive excitatory transmission at newly "recurrent" mossy fiber-granule cell synapses in a rat model of MTLE. A combination of modern techniques will be used to study presynaptic mechanisms in control versus chronically epileptic rats. Such approaches will include tissue and seizure monitoring, single-cell quantitative real-time PCR, visualized patch-clamp recordings from granule cells and direct visualization of the presynaptic function via the fluorescent styryl dye FM1-43. The long-term goal is to decipher the molecular mechanisms determining "acquired presynaptic channelopathies" and to investigate the consequences of such presynaptic dysfunction in the pathogenesis of MTLE. Data from this proposal may provide the foundation for novel therapeutic interventions for epilepsy.

描述（由申请人提供）：癫痫是一组不同的阵发性疾病，与遗传性或后天性离子通道和/或神经递质受体功能障碍（所谓的“通道病”）有关。在人类和实验性内侧颞叶癫痫 (MTLE) 中，海马苔藓纤维经历分子和结构重排。最近的数据显示，癫痫大鼠苔藓纤维中 II 类代谢型谷氨酸受体 (mGluR II) 和大电导 Ca2+ 激活钾通道 (BK 通道) 均出现强烈下调。在正常大脑中，突触前自身受体 mGluR II 与其他离子通道（即 BK 通道）的“反馈”激活会减弱过度的兴奋性传递。因此，mGluR II 和 BK 通道的突触前缺陷可能在癫痫发生中起重要作用。该项目的具体目的是：（1）检验癫痫大鼠苔藓纤维中 mGluR II 和 BK 通道的下调与颗粒细胞中 mRNA 转录物的类似缺陷和剪接变体的异常表达相关的假设； (2) 在实验性 MTLE 中检验癫痫发作引起的 mGluR II 和 BK 通道下调影响突触前功能并加剧苔藓纤维-CA3 锥体细胞突触的兴奋性传递的假设； (3) 确定 mGluR II 和 BK 通道是否可以减弱 MTLE 大鼠模型中新“复发”的苔藓纤维颗粒细胞突触的过度兴奋性传递。将结合现代技术来研究对照大鼠与慢性癫痫大鼠的突触前机制。这些方法将包括组织和癫痫监测、单细胞定量实时 PCR、颗粒细胞的可视化膜片钳记录以及通过荧光苯乙烯基染料 FM1-43 直接可视化突触前功能。长期目标是破译决定“获得性突触前通道病”的分子机制，并研究这种突触前功能障碍在 MTLE 发病机制中的后果。该提案的数据可能为癫痫的新型治疗干预措施提供基础。