Ion channels in suprachiasmatic nucleus neurons

视交叉上核神经元的离子通道

• 批准号: 6767435
• 负责人: BRUCE P BEAN
• 金额: $ 32.56万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6767435
• 关键词: action potentials; biological clocks; calcium channel; circadian rhythms; immunocytochemistry; laboratory rat; membrane channels; neurons; neurophysiology; organ culture; protein kinase; second messengers; sodium channel; suprachiasmatic nucleus; voltage /patch clamp; voltage gated channel

DESCRIPTION (provided by applicant): The suprachiasmatic nucleus (SCN) in the ventral hypothalamus contains the master clock of the brain, controlling the 24-hour circadian rhythm of physiological functions. Recent work has identified in SCN neurons many components of a molecular clock, composed of transcription factors and kinases that interact in regulatory feedback pathways. A major unanswered question is how the molecular clock is connected to the electrical activity of the neurons. The goal of the proposed research is to understand the ionic conductances that control spontaneous firing of SCN neurons and the circadian variation in their firing rate. We will do complementary experiments on intact SCN neurons in brain slice and on a preparation of acutely-dissociated neurons in which pacemaking is maintained. The brain slice preparation allows recordings under the most undisturbed conditions, while dissociated neurons enable voltage-clamp recordings with high time- and voltage-resolution and permit fast solution exchanges and readily reversible application of drugs and channel blockers. Electrophysiological and pharmacological identification of channels underlying various components of electrical current will be complemented by immunocytochemical identification of the channels expressed in the neurons. In addition to characterizing the ionic currents that directly drive pacemaking of SCN neurons, we will characterize other currents that are important for regulating its frequency. We will then determine which of these currents change in amplitude, voltage-dependence, or kinetics to produce the diurnal variation in firing frequency. Finally, we will attempt to discover how the molecular clock is linked to electrical pacemaking and determine whether the electrical clock is regulated by alteration in the activity of kinases or other second messenger pathways. Understanding the mechanisms involved in regulating the excitability of SCN neurons will help in understanding the normal function of the nervous system as well as dysregulation of sleep, attention, and hormonal release.

描述（由申请人提供）：腹侧下丘脑中的上核（SCN）包含大脑的主时钟，控制生理功能的24小时昼夜节律。最近的工作已经在SCN神经元中确定了分子时钟的许多成分，这些成分由转录因子和激酶组成，这些因子和激酶在调节反馈途径中相互作用。一个主要的未解决的问题是分子时钟如何连接到神经元的电活动。 拟议的研究的目的是了解控制SCN神经元自发解雇的离子电导和发射率的昼夜节律变化。我们将对脑切片中完整的SCN神经元以及急性分离的神经元进行互补实验，并在其中进行起搏。大脑切片制备允许在最不受干扰的条件下记录记录，而分解的神经元可以使用高时间和电压分辨率的电压钳记录，并允许快速溶液交换，并容易逆转药物和通道阻滞剂。电流的各种组成部分的电池生理和药理鉴定，将通过免疫细胞化学鉴定神经元中表达的通道的免疫细胞化学鉴定。 除了表征直接驱动SCN神经元起搏的离子电流外，我们还将表征其他对于调节其频率很重要的电流。然后，我们将确定这些电流的幅度，电压依赖性或动力学的变化，以产生发射频率的昼夜变化。最后，我们将尝试发现分子时钟如何与电气起搏器链接，并确定电时钟是否通过激酶活动或其他第二信使途径的活性来调节。了解调节SCN神经元兴奋性涉及的机制将有助于理解神经系统的正常功能以及睡眠，注意力和荷尔蒙释放的失调。