Impact of Astrocytic Glutamate Transport on Epilepsy Associated with Developmenta

描述(申请人提供)：皮质畸形疾病约占所有癫痫病例的25%。它们也是外科手术切除癫痫脑组织的最常见原因。几乎80%的皮质畸形患者患有癫痫，其中超过70%的人有癫痫发作，而这些癫痫发作不是通过抗癫痫药物来控制的。迫切需要新的治疗策略来治疗这组有问题的癫痫。在这项建议中，我们将提出一种假说，即在皮质畸形的发展过程中，星形胶质细胞谷氨酸重摄取的丢失会严重扰乱谷氨酸稳态，并对突触连接和皮质网络功能产生长期影响。正常情况下，星形胶质细胞通过谷氨酸转运体清除神经递质谷氨酸。然而，在皮质畸形的疾病中，星形胶质细胞变得活跃，我们认为这降低了它们清除细胞外谷氨酸的能力。在发育中的皮质中，谷氨酸直接驱动突触的形成。因此，我们假设，在皮质畸形的发展过程中，星形胶质细胞谷氨酸重摄取的丢失会增加细胞外谷氨酸水平，从而促进兴奋性突触的形成，并导致长期的皮质高兴奋性。我们将使用尖端成像技术、星形胶质细胞的电生理记录、皮质兴奋性以及星形胶质细胞谷氨酸运输的分子破坏和增强来验证我们的假设。我们的实验极具创新性。我们开发了一种新的皮质畸形啮齿动物模型，它紧密复制了局灶性皮质发育不良1型，这是一种目前没有动物模型的疾病。我们会 利用令人兴奋的新型谷氨酸生物传感器成像技术来测试网络功能和星形细胞谷氨酸再摄取。我们将记录以前没有被研究过的皮质谷氨酸转运体电流，我们将在畸形的皮质中这样做。我们将利用激光扫描光刺激技术在空间上描绘畸形皮质中星形细胞谷氨酸再摄取是如何改变的。利用星形胶质细胞谷氨酸运输的分子调控，我们将测试星形胶质细胞谷氨酸运输的发育丧失是否足以诱导皮质的过度兴奋，以及畸形皮质中谷氨酸重摄取的增加是否干扰癫痫的发生过程，我们认为这会导致后来的网络功能障碍。重要的是，我们将利用已经在临床上可用的药物来增加谷氨酸的再摄取。如果这种方法成功地减弱了大脑皮层的过度兴奋性，它可能会迅速转化为潜在的抗癫痫临床工具。

DESCRIPTION (provided by applicant): Diseases of cortical malformation cause approximately 25% of all cases of epilepsy. They are also the most common cause for surgical resection of epileptic brain tissue. Almost 80% of people with a cortical malformation suffer from epilepsy and greater than 70% of those people have seizures which are not managed by anti-epileptic drugs. Novel treatment strategies are urgently needed to treat this problematic group of epilepsies. In this proposal we will address the hypothesis that loss of astrocytic glutamate reuptake during the development of a cortical malformation acutely disrupts glutamate homeostasis and has long term effects on synaptic connectivity and cortical network function. Normally, astrocytes remove the neurotransmitter glutamate via glutamate transporters. In diseases of cortical malformation, however, astrocytes become reactive which we believe decreases their ability to remove extracellular glutamate. In the developing cortex glutamate directly drives synapse formation. Therefore, we hypothesize that loss of astrocytic glutamate reuptake during the development of a cortical malformation increases extracellular glutamate levels which promotes excitatory synapse formation and leads to long term cortical hyperexcitability. We will test our hypothesis utilizing cutting-edge imaging techniques, electrophysiological recording from astrocytes, in vivo assays of cortical excitability and molecular disruption and augmentation of astrocyte glutamate transport. Our experiments are extremely innovative. We have developed a novel rodent model of cortical malformation which closely replicates focal cortical dysplasia type 1, a disease with no current animal model. We will utilize exciting, novel glutamate biosensor imaging techniques to assay network function and astrocytic glutamate reuptake. We will record cortical glutamate transporter currents, which have not previously been investigated, and we will do so in the malformed cortex. We will utilize laser-scanning photostimulation to spatially map how astrocytic glutamate reuptake is altered in the malformed cortex. Utilizing molecular modulation of astrocytic glutamate transport we will test whether developmental loss of astrocytic glutamate transport is sufficient to induce cortical hyperexcitability and whether increasing glutamate reuptake in the malformed cortex interrupts epileptogenic processes which we believe lead to later network dysfunction. Importantly, we will utilize drugs which are already clinically available to increase glutamate reuptake. Should this approach successfully attenuate cortical hyperexcitability it could be rapidly translated into a potential anti-epileptogenic clinical tool.