Failure of the glutamate uptake-ascorbic acid exchange drives seizure susceptibility and severity

谷氨酸吸收-抗坏血酸交换的失败会导致癫痫发作的易感性和严重程度

• 批准号: 10179345
• 负责人: JAMES M. MAY
• 金额: --
• 依托单位: VETERANS HEALTH ADMINISTRATION
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-04-01 至 2022-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10179345
• 关键词: Acute; Aging; Agonist; Alzheimer' s Disease; Alzheimer' s disease model; Amyloid beta-Protein; Animal Model; Animals; Antioxidants; Ascorbic Acid; Astrocytes; Atherosclerosis; Behavioral; Blood; Brain; Caregivers; Ceftriaxone; Cell Death; Chronic; Clinical; Coculture Techniques; Cognitive; Coupled; Culture Media; Culture Techniques; DNA Sequence Alteration; Data; Deterioration; Diabetes Mellitus; Disease; Dose; Elderly; Electroencephalography; Ensure; Epilepsy; Equilibrium; Event; Exposure to; Extracellular Fluid; Failure; Glutamates; Goals; Gulo; Health; Home; Human; Impaired cognition; Intake; Investigation; Kainic Acid; Lead; Liver; Measures; Messenger RNA; Mitochondria; Modeling; Modification; Mus; Mutation; Nerve Degeneration; Neurons; Oxidative Stress; Oxidative Stress Pathway; Pathogenesis; Pathologic; Pathway interactions; Pattern; Pharmacology; Phenotype; Population; Predisposition; Prevalence; Prevention strategy; Process; Production; Prognosis; Property; Proteins; Quality of life; Reactive Oxygen Species; Rodent; Rodent Model; Role; Seizures; Severities; Signal Transduction; Smoking; Speed; Supplementation; Synapses; System; Telemetry; Testing; Toxic effect; Traumatic Brain Injury; Up-Regulation; Veterans; Wireless Technology; abeta accumulation; ascorbate; brain tissue; care costs; clinically relevant; cognitive ability; cognitive function; comorbidity; dietary; excitotoxicity; experimental study; familial Alzheimer disease; family burden; functional outcomes; improved; military veteran; mouse model; neuronal survival; neuropathology; neurotoxic; novel; oxidative damage; patient population; presenilin-1; preservation; relating to nervous system; synaptic failure; tau Proteins; therapeutic target; treatment planning; uptake

Co-occurrence of seizures with Alzheimer's disease dramatically alters prognosis, and speeds cognitive de- cline. Even mild seizures that may go undetected by caregivers can increase Alzheimer's disease pathogene- sis and also independently lead to neurodegeneration and cognitive dysfunction. Subclinical (non-scorbutic) vitamin C (ascorbate) deficiency is widespread in the USA, particularly among the elderly, and veteran popula- tions where smoking and oxidative stress-related diseases such as atherosclerosis and diabetes are common. A critical, but understudied, mechanism of neuronal protection during excitatory signaling is the glutamate up- take-ascorbate release exchange in astrocytes. As glutamate is taken up into perisynaptic astrocytes via GLT- 1, ascorbate is released into the extracellular fluid providing acute protection against oxidative damage. If GLT- 1 transporter function is compromised by oxidative damage, or if insufficient ascorbate is available for release, then this protection is diminished and the neurotoxic effects of prolonged glutamate exposure are magnified. Recent data support the role of ascorbate treatments in mitigating the effects of seizures, but previous re- search has been critically limited by the use of rodent models that synthesize ascorbate and thus cannot be- come deficient. Decreased brain ascorbate, at levels relevant to human deficiency, is achieved in mice by ge- netic modification of the ability to synthesize ascorbate in liver (Gulo-/-) combined with differential ascorbate supplementation. These mice can also be crossed with the APP/PSEN1 mouse model of Alzheimer's disease to model dietary insufficiency in combination with a disease in which co-occurrence of seizures is common. Specific Aim 1) Demonstrate the role of ascorbate in supporting glutamate clearance by cultured astrocytes. Using cultured astrocytes from both mice and humans we will investigate how conditions that alter the oxida- tive balance of the culture media (e.g. ascorbate and β-amyloid) determine the properties of GLT-1 in gluta- mate uptake. We will also test how altered glutamate clearance under these situations impacts neuronal sur- vival using co-culture techniques and measuring survival and dendritic branching of primary cultured neurons following exposure to glutamate. These experiments will provide direct support for the importance of the gluta- mate-ascorbate exchange mechanism in supporting neuronal health and protecting against glutamate toxicity. Specific Aim 2) Determine relationship between low brain ascorbate conditions and susceptibility to spontane- ous and pharmacologically-induced seizures. We will record neuronal hyper excitability and measure seizure events through electroencephalography (EEG) under baseline conditions and following seizure induction using kainic acid. Such studies have not previously been conducted in low ascorbate conditions owing to lack of widespread access to appropriate models. We will use an implantable telemetry (wireless) system that allows long-term measuring of EEG in animals within their home cages. This is a significant advance on more tradi- tional `tethered' EEG systems. We will also determine the extent to which repeated exposures to glutamatergic agonists, even without a clear behavioral (seizure) correlate, can negatively impact both cognitive ability, and β-amyloid production in the APP/PSEN1 mice to explore the functional outcome of seizures in an Alzheimer's disease model in addition to wild-type and Gulo-/- mice. Specific Aim 3) Establish the extent to which upregulation of GLT-1 improves glutamate clearance and de- creases detrimental effects of kainic acid treatments. GLT-1, and therefore glutamate clearance, represents a targetable strategy to reduce the extent of neural damage following hyperexcitability, or seizure events. We will investigate a compound, ceftriaxone, known to up-regulate GLT-1 expression, and assess its ability to de- crease seizure susceptibility and severity. Our long-term goal is to show that protecting glutamate uptake and avoiding ascorbate deficiency can minimize effects of seizure in specific populations, and provide a cheap pre- ventative strategy against cognitive decline.

与阿尔茨海默氏病的癫痫发作的同时发生显着改变了预后，并加快了认知能力 克林。即使是不受照料者未发现的轻度癫痫发作也会增加阿尔茨海默氏病病原体 - SIS并独立导致神经变性和认知功能障碍。亚临床（非筛查） 维生素C（抗坏血酸）缺乏症在美国，尤其是在老年人和老将中的缺乏症 吸烟和氧化应激相关疾病（如动脉粥样硬化和糖尿病）很常见。 兴奋性信号传导期间神经元保护的一种关键但知识的机制是谷氨酸 星形胶质细胞中的抗甲酸盐释放交换。当谷氨酸通过GLT-将谷氨酸置于周突触的星形胶质细胞中 1，抗坏血酸被释放到细胞外液中，从而提供急性保护抗氧化损伤。如果glt- 1转运蛋白功能会因氧化损伤而损害，或者如果抗坏血酸不足以释放， 然后，这种保护减少，并放大了长时间谷氨酸暴露的神经毒性作用。 最近的数据支持抗坏血酸治疗在减轻癫痫发作的作用中的作用，但先前的重新 搜索已受到合成抗坏血酸酯的啮齿动物模型的严重限制，因此无法 - 变得不足。在与人类缺乏有关的水平上，脑抗坏血酸的降低是通过ge-实现的 肝脏中抗坏血酸（Gulo - / - ）合成抗坏血酸的能力的网络修饰与差异抗坏血酸 补充。这些小鼠也可以与阿尔茨海默氏病的APP/PSEN1小鼠模型交叉 与饮食不足结合结合使用的疾病，在这种疾病中，癫痫发作的同时存在很常见。 具体目的1）证明抗坏血酸在支持培养的星形胶质细胞支持谷氨酸清除方面的作用。 使用来自小鼠和人类的培养的星形胶质细胞，我们将研究如何改变氧气的条件 培养基的平衡（例如抗坏血酸和β-淀粉样蛋白）确定GLT-1在谷物中的特性 伴侣吸收。我们还将测试在这些情况下谷氨酸清除率的改变如何影响神经元的表现 使用共培养技术和测量原代神经元的生存和树突分支 暴露于谷氨酸后。这些实验将直接支持谷物的重要性 在支持神经元健康和预防谷氨酸毒性方面的伴侣交换机制。 具体目标2）确定低脑抗坏血酸条件与赞助商的易感性之间的关系 OUS和药物引起的癫痫发作。我们将记录神经元超令人兴奋并测量癫痫发作 在基线条件下通过脑电图（EEG）发生的事件，并在癫痫发​​作后使用 海藻酸。由于缺乏 宽度访问适当的型号。我们将使用可植入的遥测系统（无线）系统 长期测量家居笼中的动物中的脑电图。这是对更传统的重大进步 - 纽约市的脑电图系统。我们还将确定重复接触谷氨酸能的程度 激动剂，即使没有明确的行为（癫痫发作）相关，也会对认知能力和 APP/PSEN1小鼠中的β-淀粉样蛋白产生，以探索阿尔茨海默氏症中癫痫发作的功能结果 疾病模型除了野生型和gulo - / - 小鼠。 特定目的3）确定上调GLT-1可以改善谷氨酸清除率和降低的程度 GLT-1，因此谷氨酸清除率代表 在过度兴奋或癫痫发作事件后减少神经肿瘤程度的有针对性策略。我们将 研究一种化合物，头孢曲松，已知可以上调GLT-1表达，并评估其降低的能力 折痕癫痫发作​​的敏感性和严重性。我们的长期目标是表明保护谷氨酸摄取和 避免抗坏血酸的缺乏症可以最大程度地减少特定人群中癫痫发作的影响，并提供廉价的预审长 违反认知能力下降的企业策略。