Nicotinic regulation of neurotransmission in the CNS

烟碱对中枢神经系统神经传递的调节

• 批准号: 355822-2008
• 负责人: Nashmi, Raad
• 金额: $ 2.91万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2010
• 资助国家: 加拿大
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=459577
• 关键词: Nicotinic; regulation; neurotransmission; CNS

The transmission of information between neurons in the brain is governed by the release of chemicals called "neurotranmitters" which bind to ion channels located on the surface of neurons. The binding of neurotransmitters to ion channels transduces changes in electrical activity of the neuron via the flux of ions across the membrane. The present study focuses on a class of ligand-gated ion channels called nicotinic acetylcholine receptors. alpha4beta2 is the most prevalent nicotinic receptor subtype in the CNS. Our long term goal is to examine the basic function of nicotinic receptors in modulating neurotransmission in the CNS. To address this issue we have produced three lines of knock-in mice, whereby a nicotinic receptor subunit (alpha4) was mutated to contain a fluorescent tag allowing us to localize the receptor in the CNS with exquisite detail. One of the mouse lines also contains a gain-of-function mutation rendering nicotinic receptors with several fold larger nicotinic currents and 50 fold greater affinity to nicotine. This mouse line will allow us to specifically target the receptor with very low concentrations of nicotinic agonist to unambiguously ascertain the receptor's function in physiology and behavioral experiments. We plan to achieve our overall goal firstly by imaging the localization and quantifying nicotinic receptors in specific neurons in various brain regions by exploiting the alpha4 fluorescent mouse lines. To our knowledge, these mice are the first knock-ins to express fluorescently tagged ion channels. After mapping the location and quantifying the receptor we can then precisely target specific neurons for electrophysiological recordings and design intelligently the experiments to ascertain the function of the receptor in influencing neuronal excitability. By knowing the precise quantity and subcellular localization and function of nicotinic receptors in specific neurons and circuits in the brain, we can then predict and test the role of the nicotinic receptor in modulating certain behaviors, such as reward, cognition and pain. We are also interested in understanding the function of other nicotinic receptor subtypes and we will produce fluorescently tagged alpha7 nicotinic receptors as a first step in this endeavor.

大脑中神经元之间的信息传输是由一种名为“神经递质”的化学物质的释放控制的，这种化学物质与位于神经元表面的离子通道相结合。神经递质与离子通道的结合通过跨膜的离子通量传递神经元电活动的变化。目前的研究集中在一类称为烟碱型乙酰胆碱受体的配体门控离子通道上。α4β2是中枢神经系统中最常见的烟碱受体亚型。我们的长期目标是研究尼古丁受体在调节中枢神经系统神经传递中的基本功能。为了解决这个问题，我们培育了三个敲入小鼠品系，其中尼古丁受体亚单位(α4)发生突变，包含一个荧光标记，使我们能够以精细的细节定位中枢神经系统中的受体。其中一个小鼠品系还包含一个功能获得突变，使尼古丁受体具有几倍大的尼古丁电流和50倍的尼古丁亲和力。这一小鼠品系将使我们能够以非常低浓度的尼古丁激动剂特异性地靶向受体，以明确地在生理学和行为实验中确定受体的功能。我们计划首先通过利用Alpha4荧光小鼠品系对不同脑区特定神经元中的尼古丁受体进行成像和定量来实现我们的总体目标。据我们所知，这些小鼠是第一批表达荧光标记离子通道的小鼠。在定位和量化受体之后，我们就可以精确地针对特定的神经元进行电生理记录，并智能地设计实验，以确定受体在影响神经元兴奋性方面的功能。通过了解尼古丁受体在大脑中特定神经元和回路中的准确数量、亚细胞定位和功能，我们可以预测和测试尼古丁受体在调节某些行为(如奖励、认知和疼痛)中的作用。我们还对了解其他尼古丁受体亚型的功能感兴趣，我们将生产荧光标记的α7尼古丁受体，作为这一努力的第一步。