Microcircuits of the Subiculum and Epilepsy

项目摘要/摘要 关于人和动物癫痫超同步性发展的一种重要理论 颞叶癫痫模型提示特异性下调β-氨基丁酸的表达具有关键作用 锥体下层细胞中的KCC2转运蛋白。因为KCC2是维持低细胞内浓度所必需的 超极化GABA能信号所需的氯浓度，KCC2表达的丧失将 削弱GABA能抑制并触发一系列事件导致下丘脑启动的出现 发作间歇期活动。此外，发作间期放电与突触可塑性的耦合将导致发作间期- 发作期转换和将超兴奋性传播到海马区外。 总而言之，如果这种基于KCC2的癫痫发生机制理论的基本方面是 正确的是，在幼稚的下丘脑中选择性地降低KCC2转运蛋白的活性应该是 足以产生癫痫样活动，范围从发作间歇性事件到可能的全面性发作样事件。 尽管这一预测得到了计算模型的支持，但直接的实验证据却没有。 产生了明确的结果。 我们的初步数据表明，高选择性的KCC2拮抗剂在分离的小切片上的应用 产生依赖去极化的同步性发作间歇性爆发 GABA能信号，但显然不足以触发发作-发作间期转换。 我们将利用各种最先进的技术(同步膜片钳记录 从突触耦合和非耦合细胞，对特定神经元群体的光遗传控制，以及 高分辨率解剖重建)来研究这种类型的药理学影响- 在小脑片上诱发癫痫样活动。我们将探讨其对内在和 突触可塑性，揭示了不同中间神经元亚型发挥作用的潜在机制，以及 探讨额外的致痫改变和/或来自丘下外区域的突触输入是否 是驱动发作间歇性到发作间歇性转变所必需的。

Project Summary / Abstract A prominent theory regarding the development of epileptic hyper-synchronization in human and animal models of temporal lobe epilepsy proposes a key role for the specific down-regulation of the expression of the KCC2 transporter in subicular pyramidal cells. As KCC2 is essential to maintain the low intracellular chloride concentrations required for hyperpolarizing GABAergic signaling, loss of KCC2 expression would impair GABAergic inhibition and trigger a series of events leading to the emergence of subicular-initiated interictal activity. Furthermore, interictal discharges coupled to synaptic plasticity would result in interictal- ictal transitions and spread hyper-excitability to extra-hippocampal regions. In summary, if the essential aspects of this KCC2-based mechanistic theory of epileptogenesis were correct, the selective pharmacological reduction of KCC2 transporter activity in a naïve subiculum should be sufficient to generate epileptiform activity ranging from interictal-like to, possibly, full ictal-like events. Although this prediction was supported by computational modeling, direct experimental evidence has not yielded definitive results. Our preliminary data show that the application of highly selective KCC2 antagonists on isolated mini-slices of the mouse subiculum generate synchronous interictal-like bursting that depends on depolarizing GABAergic signaling, but are not, apparently, sufficient to trigger ictal-interictal transitions. We will take advantage of a variety of state of the art techniques (simultaneous patch-clamp recordings from synaptically coupled and uncoupled cells, optogenetic control of specific neuronal populations, and high resolution anatomical reconstructions) to investigate the impact of this type of pharmacologically- induced epileptiform activity in subicular mini-slices. We will explore its consequences on intrinsic and synaptic plasticity, reveal the underlying mechanisms played by different interneuron subtypes, and explore whether additional epileptogenic changes and/or synaptic input from extra-subicular regions are necessary to drive interictal-like to ictal-like transitions.