Impaired homeostatic potentiation of GABAergic currents initiates seizures

在美国，癫痫发作影响着近300万人，在三分之二的患者中，原因不是 已知（可能的遗传起源）。特发性全身性癫痫（IGE）被认为是 它的遗传起源包括许多单核苷酸多态性（SNP）或 离子型受体，如GABA能受体（GABAR）亚单位突变（Gabrg 2 Q390 X和 与严重Dravet癫痫综合征和儿童失神癫痫有关， 患者的认知共病。与获得性癫痫发作研究相反，IGE癫痫发作和 癫痫的发生机制仍然很难解释。此外，癫痫发作和睡眠 在生理机制上相互影响/相互作用，这对 IGE研究和患者治疗。在最近的一项人类患者研究中， 振荡已经显示出促进癫痫发作活动。因此，我们假设， 睡眠相关慢波超极化-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， 用Gabrg 2 Q390 X或 Gabra 1A 322 D突变，并因此产生逃逸兴奋性突触电流（无 平衡抑制性突触电流）在睡眠和睡眠-觉醒过程中的皮层神经元 过渡SWO诱导的GABA能电流HSP损伤的这一关键步骤可导致 癫痫发作的发生/开始，也有助于IGE模型中的癫痫发生。这项工作将 填补了我们对癫痫发作机制以及癫痫发生的理解中的一个关键空白， 有可能产生一种新的癫痫治疗方法首先，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介导的电流未受损 在来自杂合Gabrg 2 +/Q390 X或Gabra 1 +/A322 D敲入的体外V-VI层皮质神经元中， 以及这种损伤是否导致神经元放电升高。第二，我们将确定 体内光诱导SWO是否会引起小鼠皮层癫痫活动 表达盐视紫红质（NpHR）和Gabrg 2 Q390 X或Gabra 1A 322 D突变。最后，我们将使用 维甲酸合成阻断剂DEAB维持突触间HSP的动态平衡 IGE模型中SWO期间的兴奋性和抑制性电流，这将提供以下证据： 一个潜在的癫痫治疗原则。这些研究产生的信息将 实质上改变了我们对癫痫发作/癫痫发生与睡眠波相互作用的看法 并最终导致IGE患者的新癫痫治疗。

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.