Enhanced excitation and epilepsy with chloride channel dysfunction

神经网络兴奋性是由兴奋和抑制之间的平衡来定义的。当这种平衡被破坏而有利于兴奋时，网络就会变得极度兴奋。这一观察构成了确定癫痫相关病理的一般指导原则。考虑到这一点，人们已经做出了重大努力来了解兴奋性和抑制性神经传递的分子特性。大脑中抑制的一个主要来源是神经递质Y-氨基丁酸(GABA)与GABAA受体亚型的结合，GABAA受体亚型的功能是配体门控氯离子通道。这种GABA能抑制反过来又依赖于神经细胞膜上存在的氯浓度梯度。Clc2氯通道亚型是负责建立这种梯度的几个通道之一。最近，人们发现一些人类特发性全身性癫痫(IGES)与CLc2基因突变有关。丘脑是一种皮质下结构，是产生与IGES相关的癫痫活动的关键组成部分。然而，CLc2在丘脑中的功能尚不清楚。我提议的项目的目标是了解CLC2中断如何促进丘脑的网络过度兴奋。我的初步结果表明，CLC2功能障碍在体外增强了丘脑网络活动的兴奋性。这种网络增强与选择性地增加对丘脑神经元亚型的突触兴奋是平行的。虽然在CLC2中断期间观察到兴奋性传递的变化令人惊讶，但这种效应可能会使丘脑网络过度兴奋。我设计了几个实验来确定调节这种增强的突触兴奋的机制。其中几个实验依赖于技术--脑电记录/解释、局部脑灌注、成像技术--我将从同意培训我的顾问那里学到这些技术。

Neural network excitability is defined by the balance between excitation and inhibition. When this balance is disrupted in favor of excitation, networks become hyperexcitable. This observation constitutes a general guiding principle for determining the pathologies associated with epilepsy. With this in mind, significant effort has been directed towards understanding the molecular properties that define excitatory and inhibitory neurotransmission. A major source of inhibition in the brain results from the binding of the neurotransmitterY-aminobutyric acid (GABA) to GABAA receptor subtypes, which function as ligand-gated chloride channels. This GABAergic inhibition, in turn, depends on the chloride concentration gradient present across neuronal membranes. The CLC2 chloride channel subtype is one of several channels responsible for establishing this gradient. Recently, it was discovered that several human idiopathic generalized epilepsies (IGEs) are associated with CLC2 mutations. The thalamus, a subcortical structure, is a critical component for the generation of seizure activity associated with the IGEs. However, the function of CLC2 in the thalamus is unknown. The goal of my proposed project is to understand how CLC2 disruptions promote network hyperexcitability in the thalamus. My preliminary results indicate that CLC2 dysfunction enhances the excitability of thalamic network activity in vitro. This network enhancement is paralleled by a selective increase in synaptic excitation onto a subtype of thalamic neurons. While surprising to observe altered excitatory transmission during CLC2 disruption, this effect likely renders thalamic networks hyperexcitable. I have designed several experiments to determine the mechanism mediating this enhanced synaptic excitation. Several of these experiments rely on techniques - EEG recording/interpretation, local brain perfusion, imaging techniques - that I will learn from consultants that have agreed to train me.