Variants in nicotine receptors and pharmacogenetics

描述（由申请人提供）：吸烟是成瘾性的，流行病学研究的数据表明，遗传因素在吸烟和尼古丁成瘾中起重要作用。最近的多项研究表明，染色体15 q25上的CHRNA 5/CHRNA 3/CHRNB 4基因座的变异与重度吸烟和尼古丁依赖（ND）相关。其中一个变体，SNP rs 16969968，将CHRNA 5基因中第398个氨基酸从天冬氨酸（D）变为天冬酰胺（N）（D398 N）。这一发现为我们提供了一个机会，以测试这种功能性D398 N多态性和/或基因座中的其他变体是否会改变人类对尼古丁给药的药理学和生理学反应。我们假设，这种D398 N和/或CHRNA 5/CHRNA 3/CHRNB 4基因中的其他变体可能会改变nAChR的功能特性，最终改变对尼古丁给药的反应。为了验证这一假设，我们提出以下几点：1。测量400名非吸烟志愿者的尼古丁反应表型。在单次实验室治疗中，每例受试者将按递增顺序接受0、2和4 mg尼古丁咀嚼胶剂量。结果指标包括尼古丁给药前后对一系列问卷的回答，以及尼古丁给药前后测量的皮肤温度、心率和血压。这些问卷包括情绪和状态的轮廓（POMS），尼古丁的直接影响量表（DENS）和积极和消极的影响计划（PANAS）。2.评价D398 N位点的基因型和CHRNA 5/CHRNA 3/CHRNB 4位点的其他多态性是否影响尼古丁咀嚼胶给药的药理学和生理学反应。我们将对所有受试者的D398 N多态性和该基因座的其他SNP进行基因分型，并使用UNPHASED和PLINK程序来测试基因型是否与上述目的1获得的表型相关。有证据表明，遗传因素会影响人类对尼古丁的主观体验和生理反应。由于经常吸烟者会产生尼古丁耐受性，这会混淆人体对尼古丁的反应，因此我们建议在此应用中使用非吸烟者。人类的主观经验与吸烟行为密切相关，因此，了解基因变异对主观经验的影响为理解吸烟和尼古丁成瘾的遗传机制提供了新的途径。 公共卫生相关性：最近的多项研究表明，CHRNA 5、CHRNA 3和CHRNB 4基因的变异增加了吸烟和尼古丁依赖的风险。在本申请中，我们提出测试这些基因中的变体是否介导人类对尼古丁施用的主观体验和生理反应的假设。该计划包括两个具体目标。首先是招募400名非吸烟者参加一项实验，测量他们对尼古丁口香糖的主观和生理反应。只使用非吸烟者的原因是为了避免在经常吸烟者中观察到的尼古丁耐受和大脑适应。第二个目的是分析CHRNA 5、CHRNA 3和CHRNB 4基因的遗传变异，并将这些变异与从第一个目的获得的响应数据相关联。总体目标是评估特定基因的遗传变异是否以及如何影响人类对尼古丁给药的反应。从这项研究中获得的知识可以用来指导未来的吸烟和尼古丁成瘾的遗传研究，并帮助制定戒烟和预防治疗的策略。

DESCRIPTION (provided by applicant): Tobacco smoking is addictive and data from epidemiological studies have suggested that genetic factors play an important role in smoking and nicotine addiction. Multiple recent studies indicate that variants in the CHRNA5/CHRNA3/ CHRNB4 locus on chromosome 15q25 are associated with heavy smoking and nicotine dependence (ND). One of the variants, SNP rs16969968, changes the 398th amino acid from aspartic acid (D) to asparagine (N) (D398N) in the CHRNA5 gene. This finding gives us an opportunity to test whether this functional D398N polymorphism and/or other variants in the locus change the pharmacological and physiological responses to nicotine administration in humans. We hypothesize that this D398N and/or other variants in the CHRNA5/CHRNA3/CHRNB4 genes may change the functional properties of nAChRs, ultimately altering the responses to nicotine administration. To test this hypothesis, we propose the following: 1. To measure the nicotine response phenotypes of 400 non-smoking volunteers. In a single laboratory session, each participant will receive 0, 2 and 4 mg of nicotine gum doses in ascending order. Outcome measures include responses to a battery of questionnaires administered before and after nicotine dosing, as well as skin temperature, heart rate and blood pressure measured before and during nicotine dosing. These questionnaires include the Profile of Mood and States (POMS), the Direct Effects of Nicotine Scale (DENS) and the Positive and Negative Affect Schedule (PANAS). 2. To evaluate whether genotypes at the D398N site and other polymorphisms in the CHRNA5/CHRNA3/CHRNB4 locus affect the pharmacological and physiological responses of nicotine gum administration. We will genotype all subjects for the D398N polymorphism and other SNPs in the locus and use the UNPHASED and PLINK programs to test whether genotypes are associated with the phenotypes obtained from aim 1 above. There is evidence that genetic factors influence humans' subjective experience and physiological responses to nicotine administration. Since regular smokers develop nicotine tolerance, which confounds human responses to nicotine, we propose to use non-smokers in this application. Humans' subjective experience is correlated to smoking behaviors, therefore, understanding the influence of genetic variants on subjective experience provides a new approach to understand the genetic mechanisms of smoking and nicotine addiction. PUBLIC HEALTH RELEVANCE: Multiple recent studies have shown that variants in the CHRNA5, CHRNA3 and CHRNB4 genes increase risks for tobacco smoking and nicotine dependence. In this application, we propose to test the hypothesis whether variants in these genes mediate humans' subjective experience and physiological responses to nicotine administration. The plan includes two specific aims. The first is to recruit 400 non- smokers to participate an experiment that measures their subjective and physiological responses to nicotine gum administration. The reason to use only non-smokers is to avoid nicotine tolerance and brain adaptation observed in regular smokers. The second aim is to analyze genetic variations at the CHRNA5, CHRNA3 and CHRNB4 genes and to correlate these variations with the response data obtained from the first aim. The overall goal is to evaluate whether and how genetic variants at particular genes affect humans' responses to nicotine administration. Knowledge obtained from this study can be used to guide future genetic studies of smoking and nicotine addiction and to help development of strategies for smoking cessation and prevention treatments.