Novel presynaptic agents to prevent glutamate-induced neural injury

颞叶癫痫是局灶性（部分）或位置相关性癫痫的最常见形式。它 影响了大约60%的癫痫患者，并且可以发生在任何年龄。红藻氨酸模型 颞叶癫痫极大地促进了对分子、细胞和 癫痫发生的药理学机制。该模型具有神经病理学特征 颞叶癫痫患者的症状有许多潜在的原因，往往是确切的 原因不明。突触前谷氨酸（Glu）的过度释放导致NMDA的过度刺激 与许多导致急性和慢性神经变性的CNS疾病有关的受体 包括癫痫。在这些条件下减少突触谷氨酸过度释放的机制可能 潜在地预防/减少对脆弱的海马神经元的兴奋性毒性损伤。当前治疗选择 防止过量Glu释放的方法是有限的，并且在人类研究中的大多数突触后干预都是 由于疗效差或不可接受的副作用而令人失望。在正常情况下， 突触细胞质Glu水平（~ 2 mM）需要通过α-酮戊二酸衍生的Glu来填充囊泡 合成.该项目的科学前提是谷氨酰胺（Gln）是Glu的前体 在高突触活性下合成，因为在增加的兴奋活性下，Gln被输入轴突 从神经胶质细胞的末端合成。因此，Na+依赖性Gln从神经胶质细胞进入神经元， 在高突触活性下补充突触细胞质Glu储存是预防突触损伤的潜在新靶点。 在兴奋性毒性条件下过量的Glu释放。我们最近发现了一种神经活性调节的 谷氨酰胺转运蛋白在兴奋性突触中表达，可被利鲁唑（一种苯并噻唑）有效抑制 一种被认为能抑制突触释放过多谷氨酸的化合物。一个关键的障碍， 对过量Glu释放所涉及的突触前机制的理解一直缺乏分子水平的研究。 关于介导K+刺激的，活性调节的Gln输入兴奋性的转运蛋白的信息 突触此外，活性调节的Gln转运在突触中的作用支持Glu的过度释放， 和神经损伤尚未被揭示，并且靶向活性调节的Gln的潜在治疗剂 突触中的转运，具有神经保护作用，更具选择性，脑渗透性，副作用较少 利鲁唑还没有开发出来。该项目对推进基础设施建设具有重要意义。 了解神经元和神经元之间Glu、Glu/Gln循环的过度突触释放的神经生物学， 神经胶质突触和Glu诱导的神经元兴奋性毒性。海马神经元突触谷氨酸合成中活性调节的谷氨酰胺转运作用的这一缺失环节的解决为研究海马神经元中的谷氨酸合成提供了基础。 过量Glu释放的体外和体内模型，以更好地理解突触前神经元的基本功能。 导致突触前谷氨酸诱导的急性和慢性神经退行性疾病的机制。

Temporal lobe epilepsy is the most common form of focal (partial) or location related epilepsy. It affects about 60 percent of all people with epilepsy and can occur at any age. The kainic acid model of temporal lobe epilepsy has greatly contributed to the understanding of the molecular, cellular and pharmacological mechanisms underlying epileptogenesis. This model presents with neuropathological features that are seen in patients with temporal lobe epilepsy. There are many potential causes, and often the exact cause is unknown. Excessive presynaptic glutamate (Glu) release causes excessive stimulation of NMDA receptors that is implicated in many CNS disorders that result in acute and chronic neurodegeneration including epilepsy. Mechanisms to reduce excessive synaptic Glu release under these conditions could potentially prevent/reduce excitotoxic damage to vulnerable hippocampal neurons. Current treatment options to prevent excessive Glu release are limited and most post-synaptic interventions in human studies have been disappointing because of poor efficacy or unacceptable side effects. Under normal conditions, maintenance of synaptic cytoplasmic Glu levels (~2mM) required for vesicular filling is via α-ketoglutarate-derived Glu synthesis. The scientific premise for the proposed project is that glutamine (Gln) is a precursor for Glu synthesis under high synaptic activity because under increased excitatory activity Gln is imported into axon terminals from glia where it is synthesized. Hence, Na+-dependent Gln import into neurons from glia to replenish synaptic cytoplasmic Glu stores under high synaptic activity is a potential novel target to prevent excessive Glu release under excitotoxic conditions. We have recently discovered a neuronal activity-regulated Gln transporter expressed in excitatory synapses that is potently inhibited by riluzole, a benzothiazole compound that is believed to inhibit excessive Glu release from synapses. A critical barrier to progress in understanding the presynaptic mechanisms involved in excessive Glu release has been the lack of molecular information about the transporter that mediates K+-stimulated, activity-regulated Gln import into excitatory synapses. In addition, the role of activity-regulated Gln transport in synapses to support excessive Glu release and neural injury has not been revealed and potential therapeutic agents that target activity-regulated Gln transport in synapses and that are neuroprotective, more selective, brain penetrant, with fewer side effects than riluzole have not been developed. This project has important implications in advancing basic understanding of the neurobiology of excessive synaptic release of Glu, Glu/Gln cycling between neuronal and glial synapses, and Glu-induced neuronal excitotoxicity. Resolution of this missing link of the role for activity-regulated Gln transport in synaptic Glu synthesis in hippocampal neurons provide the basis for studies in in vitro and in vivo models of excessive Glu release to better understand the fundamental presynaptic mechanisms that lead to presynaptic Glu-induced acute and chronic neurodegenerative diseases.