Depolarization block of inhibitory neurons impacts neuronal function in epileptic encephalopathy

抑制性神经元的去极化阻滞影响癫痫性脑病的神经元功能

• 批准号: 10020197
• 负责人: Eric Ryan Wengert
• 金额: $ 2.72万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-06 至 2021-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10020197
• 关键词: Action Potentials; Alleles; Anatomy; Behavioral; Brain; Cell Death; Childhood; Data; Disease; Electrophysiology (science); Epilepsy; Equilibrium; Exhibits; Feedback; Frequencies; Functional disorder; Generations; Genes; Genetic; Human; Impaired cognition; Impairment; Interneuron function; Interneurons; Intervention; Kinetics; Knock-in Mouse; Lateral; Metabolic; Minority; Mus; Mutation; Neocortex; Neurons; Parvalbumins; Pathogenesis; Patients; Pharmacology; Phenotype; Physiology; Population; Potassium Channel; Protein Isoforms; Refractory; Risk; Role; SCN8A encephalopathy; SCN8A gene; Seizures; Severities; Sodium; Sodium Channel; Somatostatin; Synapses; Syndrome; Techniques; Testing; Viral; Work; biophysical properties; de novo mutation; dravet syndrome; epileptic encephalopathies; excitatory neuron; gain of function; genetic approach; hippocampal pyramidal neuron; infancy; inhibitory neuron; knock-down; motor impairment; mouse model; mutant; neuronal excitability; novel; novel therapeutic intervention; prevent; small hairpin RNA; somatosensory; sudden unexpected death in epilepsy; tool; voltage

Contact PD/PI: Wengert, Eric Ryan. PROJECT SUMMARY SCN8A epileptic encephalopathy is a severe infantile epilepsy syndrome caused by mutations in the SCN8A gene encoding voltage-gated sodium channel isoform NaV1.6. NaV1.6 is not only expressed in excitatory neurons, where it is critically involved in action potential (AP) generation and propagation, but it is also expressed in inhibitory interneurons. Although they make up the minority (~15%) of cortical neurons, inhibitory interneurons in the neocortex powerfully sculpt network dynamics through various feed-forward, feed-back, and lateral inhibition circuit motifs. Previous work has implicated NaV1.6 dysfunction with abnormal excitability in excitatory neurons driven primarily by persistent and resurgent sodium currents. However, there have been no studies examining the effect of mutant NaV1.6 expression on inhibitory interneuron physiology and the subsequent contribution of these interneurons to behavioral seizures in SCN8A encephalopathy. This proposal seeks to test the hypothesis that inhibitory interneuron excitability is reduced in the Scn8aD/+ mouse model of SCN8A encephalopathy, leading to an increase in overall network excitability. My preliminary data suggest that somatostatin-positive inhibitory interneurons (SST) have reduced intrinsic excitability at high-firing frequencies due to entry into depolarization block, and have aberrantly large persistent sodium currents. In aim 1, I will record WT and Scn8aD/+ and fully characterize the voltage-gated sodium currents, intrinsic excitability, and alterations in synaptic physiology of the two major interneuron subpopulations: parvalbumin (PV) - and somatostatin (SST) -positive inhibitory interneurons. This aim will clarify the impact of a gain-of-function SCN8A mutation on interneuron function and network excitability. In aim 2, I will test the hypothesis that genetic knock-down of SCN8A specifically in inhibitory interneuron populations using a Cre-dependent shRNA will rescue the reduction in interneuron excitability, normalize the aberrant sodium channel physiology and have an impact on seizure frequency and severity in Scn8aD/+ mice. Overall, completion of these aims will resolve an important question in the field regarding how interneurons contribute to SCN8A encephalopathy and hopefully generate novel mechanistically-informed approaches to better treat SCN8A encephalopathy.

联系PD/PI：Wengert，Eric Ryan。 项目摘要 SCN8A癫痫性脑病是由SCN8A突变引起的严重婴儿癫痫综合征 编码电压门控钠通道同工型NAV1.6的基因。 NAV1.6不仅在兴奋性中表达 神经元，它与动作电位（AP）产生和传播非常重要，但也是 在抑制性神经元中表达。尽管它们构成了皮质神经元的少数（约15％），但抑制性 新皮层中的中间神经元通过各种进发料，进料，有力地雕刻网络动力学 和横向抑制回路基序。先前的工作已牵涉到NAV1.6功能障碍，异常兴奋性 在兴奋性神经元中，主要由持续和复苏的钠电流驱动。但是，有 尚无研究突变NAV1.6表达对抑制性中间神经元生理学和 这些中间神经元对SCN8A脑病中行为癫痫发作的随后贡献。这个建议 试图检验以下假设：在SCN8AD/+小鼠模型中降低了抑制性中间神经元的兴奋性 SCN8A脑病，导致整体网络兴奋性的增加。我的初步数据表明 生长抑素阳性抑制性中间神经元（SST）在高射击频率下的内在兴奋性降低 由于进入去极化块，并且具有异常大的持续钠电流。在AIM 1中，我会 记录WT和SCN8AD/+，并充分表征电压门控钠电流，内在的兴奋性和 两种主要中间神经元亚群的突触生理的改变：白蛋白（PV）和 生长抑素（SST） - 阳性抑制性中间神经元。这个目标将阐明功能获得的影响 SCN8A突变对中间神经元功能和网络兴奋性。在AIM 2中，我将检验以下假设 SCN8A的遗传敲除，专门在抑制性间神经元中使用CRE依赖性shRNA 将挽救降低中间神经元兴奋性的降低，使异常钠通道生理和 对SCN8AD/+小鼠的癫痫发作频率和严重程度产生影响。总体而言，这些目标的完成将 解决该领域的一个重要问题，即中间神经元如何对SCN8A脑病和 希望能够生成新颖的机械知识方法，以更好地治疗SCN8A脑病。