Hippocampal astrocytic Kir4.1 channel function in Type 2 diabetic mice: impact on 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一个亚群 患有这种疾病的风险增加，增加了他们的发病率和死亡率。然而，9.3%的 美国人口患有糖尿病。已有研究表明，未加控制的高血糖(糖尿病) 增加大脑对癫痫样活动的易感性，但其机制仍不清楚。的确有 确定一种可能有助于将糖尿病和癫痫发作联系起来的潜在机制是一项迫切需要。癫痫是 由神经元通讯中断引起。可能导致癫痫样活动的因素之一 是细胞外[K+]o在活跃突触区域的积聚。星形胶质细胞提供支持，提供 营养物质进入神经元回路，维持细胞外离子平衡。此外，它们是世界上最大的 大脑中有丰富的细胞类型，它们在癫痫中得到强调，主要是由于能力下降 在钾的吸收方面。与癫痫有关的一个重要的、特征明确的过程是[K+]o的调节。 Kir4.1内向整流钾通道(Kir4.1)主要位于突触周围的星形胶质细胞中 进行钾吸收的过程。这项拟议研究的理由是基于我们已发表的 数据显示，糖尿病雄性小鼠海马脑片的星形胶质细胞显示Kir4.1通道 蛋白质表达下调，钾吸收能力显著下降。这个项目的目标是 探讨男性糖尿病患者脑组织Kir4.1基因下调与癫痫样事件的关系 雌性老鼠将性别视为一个生物变量。因此，我们的中心假设是，主要的 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 下调Kir4.1通道蛋白。我们将通过测量星形胶质细胞Kir4.1通道mRNA来解决这一问题 和蛋白水平，检测海马星形胶质细胞Kir4.1通道活性，并评估大鼠癫痫样活动 电生理学研究4-氨基吡啶对雌性大鼠海马锥体神经元的影响 老鼠。最后，我们将鉴定并确定Kir4.1通道蛋白是否在海马区恢复 星形胶质细胞通过病毒传递将恢复星形胶质细胞KIR通道的表达，膜电位，钡敏感 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。这些结果 将有助于了解大脑中的糖尿病(高血糖)的新信息，这可能 对神经学问题有负面影响，如癫痫所见的神经元过度兴奋性。我们的Main 目的是了解高血糖如何影响星形细胞的稳态功能，从而导致神经元 过度兴奋。

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.