Impaired homeostatic potentiation of GABAergic currents initiates seizures

GABA能电流的稳态增强受损引发癫痫发作

• 批准号: 9243819
• 负责人: MARTIN J GALLAGHER
• 金额: $ 23.7万
• 依托单位: VANDERBILT UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9243819
• 关键词: Absence Epilepsy; Acids; Address; Affect; Animal Model; Brain; Chemosensitization; Child; Cognitive; Comorbidity; Dominant-Negative Mutation; Electroencephalography; Epilepsy; Epileptogenesis; Equilibrium; GABA Receptor; Gene Mutation; Generalized Epilepsy; Generalized seizures; Genetic; Goals; Halorhodopsins; Human; Impairment; In Vitro; Knock-in Mouse; Lead; Light; Link; Mediating; Methods; Modeling; Mus; Mutation; Neurons; Patients; Physiology; Retinoids; Seizures; Single Nucleotide Polymorphism; Sleep; Synapses; Syndrome; Therapeutic Intervention; Time; Wakefulness; Work; in vitro Model; in vivo; non rapid eye movement; receptor; trafficking

Seizures affect almost 3 million peoples in US and in two thirds of patients, the causes are not known (possible genetic origins). Idiopathic generalized epilepsy(IGE) has been recognized as its genetic origins which include many single-nucleotide polymorphisms (SNPs) or mutation of ionotropic receptors, such as GABAergic receptor (GABAR) subunit mutations (Gabrg2Q390X and Gabra1A322D) linked to severe Dravet epilepsy syndrome and child absence epilepsy, and cognitive comorbidity in patients. In contrast to acquired seizures study, IGE seizure and epileptogenesis mechanism remains largely elusive. Moreover, seizures and sleep influence/interact with each other in their physiology mechanism, which imposes a challenge to IGE study and patient treatment. In one recent human patient study, sleep-like slow-wave oscillation has been shown to facilitate epileptic seizure activity. Therefore, we hypothesize that sleep-related slow-wave hyperpolarization-depolarization oscillation(SWO) can drive homeostatic potentiation(HSP) of excitatory synaptic currents, not inhibitory synaptic currents in cortical neurons of thalamocortical circuitry in IGE animal models with Gabrg2Q390X or Gabra1A322D mutation, and therefore create an escaped excitatory synaptic currents (without balancing from inhibitory synaptic currents) in cortical neurons during sleep and sleep-wake transition. This critical step of gabaergic current HSP impairment induced by SWOs can lead to seizure occurrence/initiation and also contribute to epileptogenesis in IGE models. This work will fill a critical void in our understanding of seizure mechanism, plus epileptogenesis, and potentially generate a new seizure therapy. First, we will study whether SWO-induced HSP of inhibitory GABAR-mediated currents is impaired, but not excitatory AMPAR-mediated currents in layer V-VI cortical neurons in vitro from heterozygous Gabrg2+/Q390X or Gabra1+/A322D knock-in mice and whether this impairment results in neuronal elevated firing. Second, we will determine whether light-induced SWOs in vivo causally initiate epileptic activity in cortex from mice expressing halorhodopsin (NpHR) and Gabrg2Q390X or Gabra1A322D mutation. Last, we will use a retinoid acid synthesis blocker DEAB to maintain the dynamic HSP balance between synaptic excitatory and inhibitory currents during SWOs in IGE models, which will provide a proof of principle for a potential seizure therapy. The information generated in these studies will substantially alter our view of seizure/epileptogenesis regarding its interaction with sleep waves and eventually lead to a new seizure therapy in IGE patients.

在美国，癫痫发作影响了近300万人，三分之二的患者癫痫发作的原因并不是 已知的(可能的基因起源)。特发性全身性癫痫(IGE)已被公认为 其遗传起源包括许多单核苷酸多态(SNPs)或突变 亲离子受体，如GABA能受体(GABAR)亚单位突变(Gabrg2Q390X和 Gabra1A322D)与严重的Drave型癫痫综合征和儿童失神癫痫有关，以及 患者的认知共病。与获得性癫痫研究相反，免疫球蛋白E发作和 癫痫的发生机制在很大程度上仍然难以捉摸。此外，癫痫发作和睡眠 它们在生理机制上相互影响/相互作用，这对 免疫球蛋白E研究和患者治疗。在最近的一项人类患者研究中，睡眠样慢波 振荡已被证明有助于癫痫发作活动。因此，我们假设 睡眠相关的慢波超极化-去极化振荡(SWO)可以驱动 兴奋性突触电流的稳态增强(HSP)，而不是抑制性突触电流 Gabrg2Q390X或GABRG2Q390X对IGE动物模型丘脑皮质环路的皮质神经元的影响 Gabra1A322D突变，从而产生逃逸的兴奋性突触电流(没有 睡眠和睡眠-觉醒过程中皮层神经元的平衡 过渡。SWO诱导的GABA能电流HSP损伤的这一关键步骤可导致 在免疫球蛋白E模型中，癫痫的发生/启动也有助于癫痫的发生。这项工作将 填补了我们对癫痫发病机制以及癫痫发生机制的理解上的一个关键空白，以及 可能会产生一种新的癫痫疗法。首先，我们将研究SWO诱导的HSP是否 抑制性GABAR介导的电流受损，但兴奋性AMPAR介导的电流不受损害 杂合子Gabrg2+/Q390X或Gabra1+/A322D敲入体外培养的V-VI层皮质神经元 以及这种损伤是否会导致神经元放电增加。第二，我们将确定 在体光诱导的SWO是否引起小鼠大脑皮层癫痫活动 表达卤视紫红质(NpHR)和Gabrg2Q390X或Gabra1A322D突变。最后，我们将使用 维甲酸合成阻滞剂Deab维持突触间热休克蛋白的动态平衡 在IGE模型中，SWO过程中的兴奋和抑制电流，这将提供一个证据 潜在癫痫治疗的原则。在这些研究中产生的信息将 关于癫痫与睡眠波的相互作用，极大地改变了我们对癫痫/癫痫发生的看法 并最终为IGE患者带来一种新的癫痫疗法。