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: 10357770
• 负责人: SANDRA J HEWETT
• 金额: $ 35.09万
• 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 2024-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10357770
• 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.

项目总结 在包括癫痫、中风和创伤性脑损伤在内的几种大脑疾病中， 兴奋性和抑制性(E/I)神经递质系统存在。充分理解细胞和分子 正常的生理传递的基础过程是确定像差如何 这可能会被反驳，为这些人提供E/I失衡的症状缓解。最近的证据 证明了胱氨酸/谷氨酸逆向转运蛋白系统Xc-(sxc-)─在谷氨酸输出中的作用 并进口胱氨酸，后者是合成硫醇抗氧化剂的限速底物 谷胱甘肽─在维持E/I平衡中的作用具体地说，我们发现SUT/SUT小鼠，它们拥有天然的 SLC7a11(SLC7a11sut/sut)突变，因此缺乏SXC-，更容易过度兴奋 在受到红藻氨酸或戊四唑的急性攻击时，它们的野生型窝产仔比野生型窝产仔更多。矛盾的是，在 SLC7a11sut/sut小鼠反复亚急性/亚慢性注射相同的化学惊厥药后出现症状 低兴奋性，一种与野生型产仔对照相反的反应。有这样的想法 这些自相矛盾的发现可能源于相同的潜在机制─，即突触伸缩─ 在本提案中进行了探讨。最先进的活体传感器技术，以及细胞、分子和 药理学方法将被用来检验SXC-慢性丢失导致 谷氨酸受体在基础条件下，而缩小发生在增强条件下 神经元活性─既有稳定神经元放电的作用。这些发现是否是由 谷氨酸和/或谷胱甘肽也将被探索。确定反应的细胞特异性的研究，与 还计划具体关注星形胶质细胞的作用。总体而言，这些研究旨在增加我们的 星形胶质细胞SXC-对谷氨酸、谷胱甘肽和活性动态平衡贡献的机制研究 在活体大脑中。更广泛地说，这些努力补充了其他正在进行的确定治疗E/I目标的努力 存在于许多神经紊乱中的不平衡。