Hippocampal astrocytic Kir4.1 channel function in Type 2 diabetic mice: impact on neuronal hyperexcitability

2型糖尿病小鼠海马星形胶质细胞Kir4.1通道功能：对神经元过度兴奋的影响

• 批准号: 10896699
• 负责人: Miguel P Mendez
• 金额: $ 6.72万
• 依托单位: UNIVERSITY OF PUERTO RICO AT AGUADILLA
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10896699
• 关键词: 4-Aminopyridine; Address; Adult; Affect; Area; Astrocytes; Barium; Biological; Brain; Buffers; Cells; Central Nervous System; Communication; Communities; Data; Dependovirus; Diabetes Mellitus; Diabetic mouse; Diagnosis; Disease; Down-Regulation; Electrophysiology (science); Epilepsy; Equilibrium; Event; Female; Functional disorder; Genetic; Glucose; Goals; Hippocampus; Human; Hyperglycemia; Impairment; Incidence; Ions; Knowledge; Link; Measures; Medical; Membrane; Membrane Potentials; Messenger RNA; Molecular; Morbidity - disease rate; Mus; Mutation; Neurologic; Neurons; Non-Insulin-Dependent Diabetes Mellitus; Nutrient; Phenotype; Population; Potassium; Predisposition; Process; Productivity; Proteins; Publishing; Quality of life; Regulation; Retina; Reverse Transcriptase Polymerase Chain Reaction; Risk; Seizures; Slice; Streptozocin; Subgroup; Synapses; Testing; Therapeutic Agents; Type 2 diabetic; United States; Variant; Viral; Western Blotting; cell type; db/db mouse; diabetic; diabetic patient; epileptiform; extracellular; hippocampal pyramidal neuron; improved; insight; inward rectifier potassium channel; mRNA Expression; male; mortality; mouse model; nervous system disorder; neuronal circuitry; neuronal excitability; non-diabetic; novel therapeutics; patch clamp; patient subsets; protein expression; response; sex; stem; uptake

Epilepsy is one of the most common neurological disorders in the US. Diabetics are a subgroup of patients that are at increased risk of suffering from this condition, increasing their morbidity and mortality. Whereas, 9.3% of the United States population has diabetes. It has been shown that uncontrolled hyperglycemia (diabetes) increases the susceptibility to epileptiform-like activity in the brain but the mechanism is still unknown. There is a critical need in the identification a potential mechanism that may help link diabetes and seizures. Epilepsy is caused by a disruption of neuronal communication. One of the factors that may contribute to epileptiform activity is the accumulation of extracellular potassium [K+]o in active synaptic areas. Astrocytes provide support, deliver nutrients to neuronal circuits and maintain extracellular ion balance. Furthermore, they are one of the most abundant cell types in the brain and they have been highlighted in epilepsy mostly due to decreased capabilities in potassium uptake. One important well-characterized process that relates to epilepsy is the regulation of [K+]o. The Kir4.1 inwardly rectifying potassium channel (Kir4.1) located in astrocytes surrounding synapses largely carries out the process of potassium uptake. The rationale for the proposed study is based on our published data which shows that astrocytes from hippocampal brain slice from diabetic male mice display Kir4.1 channel protein downregulation and significant decrease in potassium uptake capability. The objective of this project is to find a relationship between Kir4.1 downregulation and seizure-like events in the brain of diabetic male and female mice considering sex as a biological variable. Therefore, our Central Hypothesis is that one of the major causes of the epileptic phenotype in diabetic patients is the inability to buffer excess [K+]o by astrocytes due to downregulation of the Kir4.1 channel protein. We will address this by measure astrocytic Kir4.1 channel mRNA and protein levels, test Kir4.1 channel activity in hippocampal astrocytes and assess the epileptiform activity in hippocampal pyramidal neurons in response to 4-aminopyridine application using electrophysiology in female mice. Finally, we will characterize and determine if reinstatement of Kir4.1 channels protein in hippocampal astrocytes via viral delivery will restore astrocytic Kir channel expression, membrane potential, barium sensitive currents and K+ and further correlate this with neuronal epileptiform-like activity in diabetic mice. These results will contribute to new information specifically to the knowledge of diabetes (high glucose) in the brain which may negatively contribute to neurological problems such as the neuronal hyperexcitability seen in epilepsy. Our main goal is to understand how hyperglycemia affects astrocytic homeostatic functions leading to neuronal hyperexcitability.

癫痫是美国最常见的神经系统疾病之一。糖尿病患者是患者的亚组 患有这种情况的风险增加，增加了其发病率和死亡率。而9.3％ 美国人口患有糖尿病。已经显示出不受控制的高血糖（糖尿病） 增加了大脑中癫痫样活性的敏感性，但该机制仍然未知。有 识别潜在机制的关键需求可能有助于将糖尿病和癫痫发作联系起来。癫痫是 由神经元交流的破坏引起。可能导致癫痫样活动的因素之一 是活性突触区域中细胞外钾[K+] O的积累。星形胶质细胞提供支持，交付 神经元电路的营养并保持细胞外离子平衡。此外，它们是最多的 大脑中的大量细胞类型，它们在癫痫中突出显示主要是由于功能降低而引起的 在钾的摄取中。与癫痫有关的一个重要特征的过程是[K+] O的调节。 Kir4.1向内整流钾通道（Kir4.1），位于突触周围的星形胶质细胞中 进行钾摄取的过程。拟议研究的理由是基于我们已发表的 数据表明，来自糖尿病雄性小鼠海马脑切片的星形胶质细胞显示Kir4.1通道 蛋白质下调和钾摄取能力的显着降低。这个项目的目的是 在糖尿病男性和 雌性小鼠认为性别是生物变量。因此，我们的核心假设是 糖尿病患者癫痫表型的原因是由于星形胶质细胞无法缓冲过量[K+] O KIR4.1通道蛋白的下调。我们将通过测量星形胶质细胞Kir4.1通道mRNA解决此问题 和蛋白质水平，测试KIR4.1海马星形胶质细胞中的通道活性，并评估癫痫表现活性 海马锥体神经元，响应于女性使用电生理学的4-氨基吡啶施用 老鼠。最后，我们将表征并确定kir4.1通道在海马中的蛋白质是否恢复 通过病毒输送的星形胶质细胞将恢复星形细胞KIR通道表达，膜电位，钡敏感 电流和K+，并进一步将其与糖尿病小鼠中的神经元癫痫样活性相关。这些结果 将为新信息做出贡献 负面影响神经系统问题，例如在癫痫中看到的神经元过度兴奋性。我们的主要 目标是了解高血糖如何影响星形胶质稳态功能导致神经元 过度兴奋。