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

基本信息

批准号：
10676134
负责人：
Miguel P Mendez
金额：
$ 11.52万
依托单位：
UNIVERSITY OF PUERTO RICO AT AGUADILLA
依托单位国家：
美国
项目类别：
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/10676134
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

项目摘要

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。糖尿病患者是一个亚群，患这种疾病的风险增加，从而增加其发病率和死亡率。而 9.3% 的美国人口患有糖尿病。研究表明，不受控制的高血糖（糖尿病）增加大脑中癫痫样活动的易感性，但其机制仍不清楚。有迫切需要确定可能有助于将糖尿病和癫痫发作联系起来的潜在机制。癫痫病是由神经元通讯中断引起。可能导致癫痫样活动的因素之一是活跃突触区域细胞外钾[K+]o 的积累。星形胶质细胞提供支持、传递为神经回路提供营养并维持细胞外离子平衡。此外，它们是最大脑中丰富的细胞类型，它们在癫痫症中的突出表现主要是由于能力下降在钾的吸收方面。与癫痫相关的一个重要且明确的过程是 [K+]o 的调节。 Kir4.1 内向整流钾通道 (Kir4.1) 大部分位于突触周围的星形胶质细胞中进行钾的吸收过程。拟议研究的基本原理基于我们发表的数据显示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吸收能力显着下降。该项目的目标是寻找糖尿病男性和糖尿病患者大脑中 Kir4.1 下调与癫痫样事件之间的关系雌性小鼠将性别视为生物变量。因此，我们的中心假设是，主要的假设之一是糖尿病患者癫痫表型的原因是星形胶质细胞无法缓冲过量的 [K+]o，这是由于 Kir4.1 通道蛋白的下调。我们将通过测量星形细胞 Kir4.1 通道 mRNA 来解决这个问题和蛋白质水平，测试海马星形胶质细胞中的 Kir4.1 通道活性并评估使用电生理学研究女性海马锥体神经元对 4-氨基吡啶应用的反应老鼠。最后，我们将表征并确定海马中 Kir4.1 通道蛋白是否恢复通过病毒递送的星形胶质细胞将恢复星形胶质细胞 Kir 通道表达、膜电位、钡敏感性电流和 K+ 并进一步将其与糖尿病小鼠的神经元癫痫样活动相关联。这些结果将有助于提供新的信息，特别是大脑中糖尿病（高血糖）的知识，这可能对神经系统问题产生负面影响，例如癫痫中出现的神经元过度兴奋。我们的主要目标是了解高血糖如何影响星形胶质细胞稳态功能，从而导致神经元过度兴奋。