Epilepsy and dendritic excitability

癫痫和树突状兴奋性

• 批准号: 7779790
• 负责人: NICHOLAS P POOLOS
• 金额: $ 34.13万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7779790
• 关键词: Affect; Animal Model; Anisomycin; Antiepileptic Agents; Biochemical; Biochemical Pathway; Biological Assay; Brain; Brain region; Chronic; Cyclic Nucleotides; Data; Dependence; Development; Down-Regulation; Electroencephalography; Electrophysiology (science); Epilepsy; Epileptogenesis; Family; Frequencies; Funding; Gated Ion Channel; Generalized seizures; Generations; HCN1 channel; Hippocampus (Brain); Ion Channel; Link; MAP Kinase Gene; MAPK14 gene; Mediating; Membrane Potentials; Mitogens; Molecular; Neocortex; Neurons; Outcome; Outcome Study; Pathogenesis; Pathway interactions; Patients; Pharmaceutical Preparations; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphotransferases; Pilocarpine; Play; Population; Preparation; Process; Property; Protein Dephosphorylation; Regulation; Role; Seizures; Severities; Signal Pathway; Signal Transduction; Slice; Status Epilepticus; Techniques; Temporal Lobe Epilepsy; Testing; Thalamic structure; Up-Regulation; cyclic-nucleotide gated ion channels; disability; drug development; improved; in vivo; inhibitor/antagonist; knockout animal; lamotrigine; neocortical; nervous system disorder; neuronal excitability; novel; prevent; public health relevance; research study; treatment strategy; voltage

DESCRIPTION (provided by applicant): Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are voltage-gated ion channels that modulate excitability in several brain regions involved in the pathogenesis of epilepsy, including hippocampus, neocortex, and thalamus. The preponderance of evidence shows that downregulation of Ih, the current generated by HCN channels, is associated with neuronal hyperexcitability and epilepsy. In the prior funding period of this project, the onset of epilepsy in an animal model was found to be associated with loss of HCN channel expression, and downregulation of HCN channel gating (i.e. hyperpolarization of Ih voltage-dependent activation). This latter change in HCN channel properties may be particularly important in the generation of seizures, as lamotrigine, an antiepileptic drug, produces upregulation of HCN channel gating as part of its antiepileptic action. A novel modulator of HCN channel gating, p38 mitogen- activated kinase (p38 MAPK), was characterized as well, with inhibition of p38 MAPK causing downregulation of HCN gating. In the present proposal, the links between phosphorylation (i.e. kinase or phosphatase) signaling and HCN channels will be explored. The overall hypothesis is that the downregulation of HCN channel gating that occurs in epilepsy may be due to loss of kinase activity, such as that of p38 MAPK, or to increased phosphatase activity. We will also explore whether direct modulation of p38 MAPK activity exerts an antiepileptic action in vivo. Specifically, we will answer the following questions: 1) Is altered HCN channel gating in epilepsy associated with loss of kinase activity? 2) Is altered HCN channel gating in epilepsy associated with increased phosphatase activity? 3) Is upregulation of HCN gating via activation of p38 MAPK signaling effective in an animal model of temporal lobe epilepsy (TLE)? To answer these questions, we will use cellular electrophysiology techniques in the brain slice preparation, biochemical techniques to assay kinase and phosphatase activity, and long-term video-electroencephalography (VEEG) in the pilocarpine animal model of epilepsy. The outcome of these experiments should increase our understanding of the molecular mechanisms by which seizures alter ion channel biophysical properties, determine whether epilepsy is associated with derangement of phosphorylation signaling pathways, and explore possible novel antiepileptic treatment strategies. PUBLIC HEALTH RELEVANCE: The current proposal will study the mechanisms of epilepsy at cellular and molecular levels. Epilepsy is one of the most common neurological diseases, affecting nearly 1% of the population, and causing significant disability in the 30% of epilepsy patients whose seizures are uncontrolled by existing medication. The outcome of this study may identify specific biochemical pathways that could be targeted for development of novel antiepileptic drugs, improving the likelihood that currently poorly-controlled patients may one day be seizure-free.

描述（由申请人提供）：超极化激活的环核苷酸门控（HCN）通道是电压门控离子通道，可调节与癫痫发病有关的几个脑区域的兴奋性，包括海马、新皮层和丘脑。大量证据表明，HCN通道产生的电流Ih的下调与神经元高兴奋性和癫痫有关。在本项目前期资助期内，在动物模型中发现癫痫发作与HCN通道表达缺失和HCN通道门控下调（即Ih电压依赖性激活的超极化）有关。后一种HCN通道特性的改变在癫痫发作的产生中可能特别重要，因为抗癫痫药物拉莫三嗪在其抗癫痫作用中会产生HCN通道门控上调。一种新的HCN通道门控调节剂p38丝裂原活化激酶（p38 MAPK）也被表征为抑制p38 MAPK导致HCN门控下调。在本提案中，将探讨磷酸化（即激酶或磷酸酶）信号传导与HCN通道之间的联系。总的假设是，癫痫中HCN通道门控的下调可能是由于激酶活性的丧失，如p38 MAPK，或磷酸酶活性的增加。我们还将探讨p38 MAPK活性的直接调节是否在体内发挥抗癫痫作用。具体来说，我们将回答以下问题：1)癫痫患者HCN通道门控改变是否与激酶活性丧失相关？2)癫痫患者HCN通道门控改变是否与磷酸酶活性增加有关？3)在颞叶癫痫（TLE）动物模型中，通过激活p38 MAPK信号来上调HCN门控是否有效？为了回答这些问题，我们将在匹罗卡品癫痫动物模型中使用细胞电生理学技术制备脑切片，生化技术测定激酶和磷酸酶活性，以及长期视频脑电图（VEEG）。这些实验的结果将增加我们对癫痫发作改变离子通道生物物理特性的分子机制的理解，确定癫痫是否与磷酸化信号通路紊乱有关，并探索可能的新型抗癫痫治疗策略。