PROPERTIES OF NICOTINIC RECEPTORS IN MUTANT MICE

突变小鼠烟碱受体的特性

• 批准号: 6464635
• 负责人: John A. Dani
• 金额: $ 35.07万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-01 至 2002-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6464635
• 关键词: autonomic nervous system; behavioral /social science research tag; biological signal transduction; calcium flux; cholinergic receptors; drug withdrawal; electrophysiology; hippocampus; immunofluorescence technique; laboratory mouse; memory; mutant; neural plasticity; neurons; neuroregulation; nicotinic receptors; protein structure function; psychological reinforcement; receptor expression; receptor sensitivity; superior cervical ganglion; synapses; tissue /cell culture; tobacco abuse; voltage /patch clamp; autonomic nervous system; behavioral /social science research tag; biological signal transduction; calcium flux; cholinergic receptors; drug withdrawal; electrophysiology; hippocampus; immunofluorescence technique; laboratory mouse; memory; mutant; neural plasticity; neurons; neuroregulation; nicotinic receptors; protein structure function; psychological reinforcement; receptor expression; receptor sensitivity; superior cervical ganglion; synapses; tissue /cell culture; tobacco abuse; voltage /patch clamp

Tobacco use in developed countries has been estimated to cause nearly 20% of all deaths, making it the largest single contributor to premature death (Peto et al., 1992). Nicotine is the primary component of tobacco that supports continued use, presumably exerting its behavior effects by initially acting upon nicotinic acetylcholine receptors (nAChRs). This project investigates basic properties of nAChRs at synapses, with the expectation that those properties underlie some of the systems physiology and behaviors investigated in the other two projects. The application focuses on how nAChRs respond to the changing concentrations of nicotine experienced by a smoker. As the nicotine concentrations changes, the population of nAChRs distributes among functional states (i.e. activated, desensitized, and long-term inactivated states) that may underlie the reward mediated by nicotine as well as contributing to aspects of tolerance and withdrawal. After determining quantitatively the calcium signals mediated by nAChRs, we will determine how those calcium signals may modulate hippocampal synapses. Finally, we will determine how the changing activity of nAChRs modulates the responses of ventral tegmental area neurons. Patch clamp electrophysiology, quantitative calcium measurements, and fluorescence techniques will be used to investigate the hypothesis that nicotine delivered by smoking activates and desensitizes nAChRs, which are constantly distributing among functional states. Microisland cultures and brain slices will be used to study tissue from mutant mice, which serve as the fundamental and unifying tool for this Program Project application. The work will initially utilize mutant mice lacking alpha3, alpha5, alpha7, or beta2, and the mouse containing the alpha7 (L247T) subunit, which exhibits diminished desensitization. All of these mice are presently available. Because the number of nAChRs is increased in the brains of smokers, it has been argued that addicted smokers medicate themselves with nicotine to control the level nAChR desensitization and inactivation. Thus, our studies of the changing functional states of nAChRs may have direct importance for understanding issues fundamental to nicotine addiction.

据估计，发达国家的烟草使用会造成所有死亡的20％，使其成为过早死亡的最大贡献者（Peto等，1992）。尼古丁是支持继续使用的烟草的主要成分，大概是通过作用于烟碱乙酰胆碱受体（NACHRS）来发挥其行为效应。该项目研究了NACHRS在突触时的基本特性，期望这些特性是其他两个项目中研究的一些系统生理和行为。该应用集中在NACHRS如何应对吸烟者所经历的尼古丁浓度变化的情况下。随着尼古丁浓度的变化，NACHR的种群分布在功能状态（即激活，脱敏和长期灭活状态）之间，这些状态可能是尼古丁介导的奖励以及对耐受性和戒断方面的贡献的基础。在定量确定由NACHR介导的钙信号之后，我们将确定这些钙信号如何调节海马突触。最后，我们将确定NACHRS的变化活动如何调节腹侧段区域神经元的反应。斑块夹电生理学，定量钙测量和荧光技术将用于研究以下假设：通过吸烟而激活的尼古丁激活并使NACHRS脱敏，而NACHR则在功能状态下不断分布。微岛培养物和脑切片将用于研究突变小鼠的组织，这些组织是该程序项目应用的基本和统一工具。这项工作最初将利用缺乏α3，alpha5，alpha7或beta2的突变小鼠，以及包含α7（L247T）亚基的小鼠，该小鼠表现出脱敏化的降低。所有这些小鼠目前都可以使用。由于吸烟者的大脑增加了NACHR的数量，因此有人认为，上瘾的吸烟者用尼古丁给自己药水以控制NACHR脱敏和灭活水平。因此，我们对NACHRS不断变化的功能状态的研究可能对理解尼古丁成瘾基础的问题具有直接的重要性。