Investigating the role of system xc- in glutamate, glutathione and synapse homeostasis in vivo

研究系统 xc- 在体内谷氨酸、谷胱甘肽和突触稳态中的作用

• 批准号: 10116499
• 负责人: SANDRA J HEWETT
• 金额: $ 34.91万
• 依托单位: SYRACUSE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-03-01 至 2023-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10116499
• 关键词: AMPA Receptors; Acetylcysteine; Acute; Address; Affect; Amino Acids; Antioxidants; Astrocytes; Biological Models; Brain; Brain Diseases; Chronic; Complement; Couples; Cysteine; Cystine; Data; Dendritic Spines; Disease; Dose; Electroencephalogram; Epilepsy; Equilibrium; Exhibits; Exons; Glutamate Receptor; Glutamates; Glutathione; Glutathione Disulfide; High Pressure Liquid Chromatography; Hippocampus (Brain); Homeostasis; Immunohistochemistry; Individual; Kainic Acid; Knockout Mice; Knowledge; Light; Maintenance; Measurement; Mediating; Molecular; Morphology; Mus; Mutation; Neuraxis; Neurons; Neurotransmitters; Oxidation-Reduction; Pentylenetetrazole; Pharmacology; Phenotype; Physiological; Process; Pump; Regulation; Role; Signal Transduction; Source; Specificity; Stroke; Sulfhydryl Compounds; Synapses; System; Testing; Time; Traumatic Brain Injury; Vertebral column; Western Blotting; antiporter; brain electrical activity; brain tissue; conditional knockout; design; electrical measurement; experimental study; extracellular; in vivo; interest; nervous system disorder; neuronal excitability; new therapeutic target; receptor; receptor expression; response; scale up; sensor technology; stem; therapeutic target; transmission process

PROJECT SUMMARY In several brain disorders including epilepsy, stroke and traumatic brain injury, an imbalance between the excitatory and inhibitory (E/I) neurotransmitter systems exists. Understanding fully the cellular and molecular processes that underlie normal, physiological transmission is the first step in determining how aberrations of such might be countered to provide such individuals with E/I imbalance symptomatic relief. Recent evidence from our lab demonstrates a role for the cystine/glutamate antiporter System xc- (Sxc-) ─ which exports glutamate and imports cystine, the latter of which is the rate-limiting substrate for the synthesis of the thiol antioxidant glutathione ─ in maintenance of E/I balance. Specifically, we find that sut/sut mice, which harbor a natural mutation in SLC7a11 (SLC7a11sut/sut) and are therefore devoid of Sxc-, are considerably more hyperexcitable than their wild-type littermates upon acute challenge with kainic acid or pentylenetetrazole. Paradoxically, after repeated sub-acute/sub-chronic administration of the same chemoconvulsants, SLC7a11sut/sut mice exhibit signs of hypoexcitability, a response polar opposite to that which occurs in wild-type littermate controls. The idea that these paradoxical findings may result from the same underlying mechanism ─ namely synaptic scaling ─ will be explored in this proposal. State-of-the-art in vivo sensor technology, as well as, cellular, molecular and pharmacological approaches will be used to test the hypothesis that chronic loss of Sxc- leads to a scaling up of glutamate receptors under basal conditions, whereas scaling down occurs under conditions of enhanced neuronal activity ─ both in efforts to stabilize neuronal firing. Whether these finding are mediated by changes in glutamate and/or glutathione will also be explored. Studies to determine the cellular specificity of response, with specific focus on the role of the astrocyte, are also planned. Overall, these studies are designed to increase our mechanistic understanding of the contribution of astrocyte Sxc- to glutamate, glutathione and activity homeostasis in in vivo brain. More broadly, these efforts complement other ongoing efforts to identify targets to treat the E/I imbalance that exists in many neurological disorders.

项目概要 在癫痫、中风和创伤性脑损伤等多种脑部疾病中， 充分了解细胞和分子的兴奋性和抑制性 (E/I) 神经递质系统。 正常生理传输的过程是确定畸变如何的第一步 最近的证据可能会抵消这种情况，从而为这些人提供 E/I 失衡症状的缓解。 我们实验室的研究证明了胱氨酸/谷氨酸逆向转运蛋白系统 xc- (Sxc-) 的作用，该系统输出谷氨酸 并进口胱氨酸，后者是硫醇抗氧化剂合成的限速底物 具体而言，我们发现 sut/sut 小鼠具有天然的谷胱甘肽维持 E/I 平衡的作用。 SLC7a11 (SLC7a11sut/sut) 突变，因此缺乏 Sxc-，因此更加过度兴奋 矛盾的是，在受到红藻氨酸或戊四唑的急性攻击后，它们的野生型同窝动物相比。 重复亚急性/亚慢性给予相同的化学惊厥药，SLC7a11sut/sut 小鼠表现出体征 兴奋性低下，这种反应与野生型同窝对照中发生的反应截然相反。 这些矛盾的发现可能是由相同的潜在机制（即突触缩放）引起的。 该提案探讨了最先进的体内传感器技术以及细胞、分子和技术。 将使用药理学方法来检验以下假设：Sxc- 的慢性丢失会导致 Sxc- 的扩大 谷氨酸受体在基础条件下，而缩小发生在增强条件下 神经元活动 ─ 都在努力稳定神经放电，这些发现是否是由变化介导的。 还将探索谷氨酸和/或谷胱甘肽的研究以确定反应的细胞特异性。 总体而言，这些研究旨在增加我们对星形胶质细胞作用的具体关注。 星形胶质细胞 Sxc- 对谷氨酸、谷胱甘肽和活性稳态的贡献的机制理解 更广泛地说，这些努力补充了其他正在进行的努力，以确定治疗 E/I 的目标。 许多神经系统疾病中存在不平衡。