Volume-regulated anion channels (VRACs) are a group of ubiquitously expressed outwardly-rectifying anion channels that sense increases in cell volume and act to return cells to baseline volume through an efflux of anions and organic osmolytes, including glutamate. Because cell swelling, increased extracellular glutamate levels, and reduction of the brain extracellular space (ECS) all occur during seizure generation, we set out to determine whether VRACs are dysregulated throughout mesial temporal lobe epilepsy (MTLE), the most common form of adult epilepsy. To accomplish this, we employed the IHKA experimental model of MTLE, and probed for the expression of LRRC8A, the essential pore-forming VRAC subunit, at acute, early-, mid-, and late-epileptogenic time points (1-, 7-, 14-, and 30-days post-IHKA, respectively). Western blot analysis revealed the upregulation of total dorsal hippocampal LRRC8A 14-days post-IHKA in both the ipsilateral and contralateral hippocampus. Immunohistochemical analyses showed an increased LRRC8A signal 7-days post-IHKA in both the ipsilateral and contralateral hippocampus, along with layer-specific changes 1-, 7-, and 30-days post-IHKA bilaterally. LRRC8A upregulation 1 day post-IHKA was observed primarily in astrocytes; however, some upregulation was also observed in neurons. Glutamate-GABA/glutamine cycle enzymes glutamic acid decarboxylase, glutaminase, and glutamine synthetase were also dysregulated at the 7-day timepoint post status epilepticus. The timepoint-dependent upregulation of total hippocampal LRRC8A and the possible subsequent increased efflux of glutamate in the epileptic hippocampus suggest that the dysregulation of astrocytic VRAC may play an important role in the development of epilepsy.

中文翻译：

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内侧颞叶癫痫海马内红藻氨酸模型中体积调节阴离子通道成孔亚基 LRRC8A 的调节。

体积调节阴离子通道 (VRAC) 是一组普遍表达的外向整流阴离子通道，可感知细胞体积的增加，并通过阴离子和有机渗透剂（包括谷氨酸）的流出使细胞恢复到基线体积。由于细胞肿胀、细胞外谷氨酸水平增加以及大脑细胞外间隙 (ECS) 缩小均发生在癫痫发作期间，因此我们着手确定 VRAC 是否在成人癫痫最常见形式的内侧颞叶癫痫 (MTLE) 中失调。 。为了实现这一目标，我们采用了 MTLE 的 IHKA 实验模型，并探讨了 LRRC8A（重要的成孔 VRAC 亚基）在急性、早期、中期和晚期致癫痫时间点（1-、7-）的表达。分别为 IHKA 后 14 天和 30 天）。蛋白质印迹分析显示，IHKA 后 14 天，同侧和对侧海马中总背侧海马 LRRC8A 上调。免疫组织化学分析显示，IHKA 后 7 天，同侧和对侧海马中 LRRC8A 信号均增加，并且 IHKA 后 1、7 和 30 天双侧海马层特异性变化。IHKA 后 1 天，LRRC8A 上调主要在星形胶质细胞中观察到；然而，在神经元中也观察到了一些上调。谷氨酸-GABA/谷氨酰胺循环酶谷氨酸脱羧酶、谷氨酰胺酶和谷氨酰胺合成酶在癫痫持续状态后 7 天的时间点也出现失调。总海马 LRRC8A 的时间点依赖性上调以及随后癫痫海马中谷氨酸流出量的增加表明星形细胞 VRAC 的失调可能在癫痫的发展中发挥重要作用。