PROPERTIES OF NICOTINIC RECEPTORS IN MUTANT MICE

突变小鼠烟碱受体的特性

• 批准号: 6606516
• 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: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2003-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6606516
• 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

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，在发达国家，烟草使用造成了近 20% 的死亡，使其成为过早死亡的最大单一因素（Peto 等，1992）。尼古丁是烟草中支持持续使用的主要成分，可能通过最初作用于烟碱乙酰胆碱受体（nAChR）来发挥其行为影响。该项目研究突触处 nAChR 的基本特性，期望这些特性是其他两个项目研究的一些系统生理学和行为的基础。该应用重点关注 nAChR 如何响应吸烟者所经历的尼古丁浓度变化。随着尼古丁浓度的变化，nAChRs 的数量分布在功能状态（即激活、脱敏和长期失活状态）之间，这可能是尼古丁介导的奖励的基础，并有助于耐受和戒断。在定量确定 nAChR 介导的钙信号后，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 nAChR 活性的变化如何调节腹侧被盖区神经元的反应。膜片钳电生理学、定量钙测量和荧光技术将用于研究吸烟释放的尼古丁激活 nAChR 并使 nAChR 脱敏的假设，而 nAChR 不断分布在功能状态之间。微岛培养物和脑切片将用于研究突变小鼠的组织，这是该计划项目应用的基本和统一工具。这项工作最初将利用缺乏 alpha3、alpha5、alpha7 或 beta2 的突变小鼠，以及含有 alpha7 (L247T) 亚基的小鼠，其脱敏作用减弱。目前所有这些小鼠均已上市。由于吸烟者大脑中 nAChR 的数量增加，因此有人认为，成瘾的吸烟者通过服用尼古丁来控制 nAChR 脱敏和失活水平。因此，我们对 nAChR 功能状态变化的研究可能对于理解尼古丁成瘾的基本问题具有直接重要性。