Ionic Homeostasis and Seizure Regulation

离子稳态和癫痫发作调节

• 批准号: 7082163
• 负责人: Janet Lynn Stringer
• 金额: $ 27.1万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-01 至 2010-07-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7082163
• 关键词: acid base balance; astrocytes; brain electrical activity; calcium channel; calcium channel blockers; calcium flux; dentate gyrus; electrophysiology; epilepsy; extracellular; hippocampus; laboratory rat; membrane transport proteins; neurons; neuropharmacologic agent; neuropharmacology; neurotoxins; tissue /cell culture; voltage gated channel

DESCRIPTION (provided by applicant): The long-term goal of this research is to understand how neurons become synchronized into seizure discharges and how the brain terminates the synchronized activity. In the last grant period experiments explored the mechanisms underlying regulation of extracellular potassium and how this regulation might influence neuronal excitability and started to examine regulation of pH. Preliminary evidence suggests that the changes in extracellular pH contribute to regulation of neuronal activity and may contribute to the relative seizure sensitivity of brain regions. Preliminary data also suggest that astrocytes play a significant role in regulation of extracellular calcium, thus influencing neuronal excitability and possibly neuronal vulnerability. In this grant period, we will continue to focus on the role of the ionic environment in neuronal synchronization, with an emphasis on pH and calcium. Hypothesis 1 -The regional differences in pH during neuronal activity are due to differences in active acid transporters in the neurons in the region. This will be tested by determining which pH regulatory processes are different in the dentate gyrus compared to CA1, both in vivo and in vitro. Intracellular pH in CA1 will be measured and compared to seizure duration and extracellular pH to determine whether intracellular pH mirrors extracellular pH and whether it contributes to seizure termination in CA1. Anatomical and pharmacological studies will determine which ion transporters are involved in the regulation of pH in the dentate gyrus and CA1, with examination of changes during and after neuronal activity. Hypothesis 2 - Recovery of the extracellular calcium during neuronal activity is due to efflux of calcium from astrocytes. This hypothesis will be tested by determining extracellular calcium changes in CA1 and the dentate gyrus in vivo and in vitro during trains of stimulation. Pharmacological blockers will determine the role of the different voltage-gated calcium channels and the role of calcium released from internal stores. The role of astrocytes in the recovery of extracellular calcium during continued neuronal activity will be tested using glial specific toxins. This hypothesis will be directly tested by measuring changes in intracellular calcium in glial cells and neurons during stimulus trains in hippocampal slices while measuring extracellular calcium.

描述（由申请人提供）：这项研究的长期目标是了解神经元如何同步到癫痫放电以及大脑如何终止同步活动。在最后的资助期内，实验探索了细胞外钾调节的机制以及这种调节如何影响神经元兴奋性，并开始研究 pH 值的调节。初步证据表明，细胞外 pH 值的变化有助于神经元活动的调节，并可能有助于大脑区域的相对癫痫敏感性。初步数据还表明，星形胶质细胞在细胞外钙的调节中发挥着重要作用，从而影响神经元的兴奋性和可能的​​神经元脆弱性。在此资助期间，我们将继续关注离子环境在神经元同步中的作用，重点是 pH 和钙。假设 1 - 神经元活动期间 pH 值的区域差异是由于该区域神经元中活性酸转运蛋白的差异造成的。这将通过确定体内和体外齿状回与 CA1 中哪些 pH 调节过程不同来进行测试。将测量 CA1 中的细胞内 pH 值，并将其与癫痫发作持续时间和细胞外 pH 值进行比较，以确定细胞内 pH 值是否反映细胞外 pH 值以及它是否有助于 CA1 中癫痫发作的终止。解剖学和药理学研究将通过检查神经元活动期间和之后的变化来确定哪些离子转运蛋白参与齿状回和 CA1 的 pH 调节。假设 2 - 神经元活动期间细胞外钙的恢复是由于钙从星形胶质细胞流出。这一假设将通过在体内和体外测定一系列刺激期间 CA1 和齿状回的细胞外钙变化来检验。药理学阻断剂将决定不同电压门控钙通道的作用以及从内部储存释放的钙的作用。将使用神经胶质特异性毒素来测试星形胶质细胞在持续神经元活动期间细胞外钙恢复中的作用。该假设将通过测量海马切片刺激序列期间神经胶质细胞和神经元细胞内钙的变化，同时测量细胞外钙来直接检验。