美国科学家经过研究发现，吸烟成瘾主要是遗传基因使然，这一发现将有助于帮助开发戒烟药品。
美国密歇根大学医学教育系的研究人员称已经找到一种基因，它通常会让那些首次尝试抽烟的人产生一种“飘飘然的感觉”， 从而使人很易上瘾，而且这种基因有可能增加吸烟者患肺癌的可能性。来自美国密歇根大学医学教育系的帕莫洛（Ovide Pomerleau）是该研究项目的主要负责人，他已经将这一项研究成果发表在最新一期的《上瘾》（Addiction）杂志上。
帕莫洛和他的研究小组对435对志愿者进行了跟踪研究。这些志愿者中有一些从没有吸过烟，有的曾经尝试过几次但是没有上瘾。研究结果发现，人们容易吸烟上瘾六成是因为遗传基因，两成基于家庭环境，而剩下两成则缘于个人经历。
容易导致人吸烟成瘾的基因名叫CHRNA5基因，研究发现，CHRNA5基因会影响机体对尼古丁的吸收。帕莫洛的研究小组对白鼠进行实验发现，CHRNA5基因会进行变异，带有变异基因的实验鼠所吸收的尼古丁量明显高于正常实验鼠。 此外，CHRNA5基因还会参与乙酰胆碱（Acetylcholine）受体蛋白的合成，而乙酰胆碱是产生欣快感的主要神经传导物质，它同时也影响机体的学习与记忆能力、睡眠、肌肉运动、心跳和血压等。 研究人员认为，尼古丁的构成与乙酰胆碱高度相似，很可能与相同的受体蛋白结合发生作用，神经系统在吸收尼古丁后，也会产生和吸收乙酰胆碱相似的欣快感。帕莫洛说，在CHRNA5基因发生变异之后，机体产生的乙酰胆碱受体蛋白更易于和尼古丁结合。 对于实验鼠，这会促使机体吸收更多的尼古丁而不对神经系统产生副作用；对于人类，这会使人体易于对尼古丁产生依赖性，也就是烟瘾。帕莫洛说，分析与烟瘾相关的基因，可以增加对烟瘾机理的了解，也有利于针对不同的基因类型设计更有效的戒烟疗法。这一发现还可以用来帮助开发戒烟药品。（生物谷Bioon.com）
生物谷推荐原始出处：
Addiction，Volume 103 Issue 9, Pages 1544 - 1552，Richard Sherva，Ovide F. Pomerleau
Association of a single nucleotide polymorphism in neuronal acetylcholine receptor subunit alpha 5 (CHRNA5) with smoking status and with 'pleasurable buzz' during early experimentation with smoking
Richard Sherva 1 , Kirk Wilhelmsen 2 , Cynthia S. Pomerleau 3 , Scott A. Chasse 4 , John P. Rice 1 , Sandy M. Snedecor 3 , Laura J. Bierut 1 , Rosalind J. Neuman 1 & Ovide F. Pomerleau 3
1 Department of Psychiatry, Washington University School of Medicine, St Louis, MO, USA, 2 Department of Genetics and Neurology, Carolina Center for Genome Sciences, Chapel Hill, NC, USA, 3 Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA and 4 Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
Correspondence to Ovide Pomerleau, University of Michigan Department of Psychiatry, Room 2137, Rachel Upjohn Building, Ann Arbor, MI 48109-5765, USA. E-mail ofpom@umich.edu
Re-use of this article is permitted in accordance with the Creative Commons Deed, Attribution 2.5, which does not permit commercial exploitation.
ABSTRACT
Aims To extend the previously identified association between a single nucleotide polymorphism (SNP) in neuronal acetylcholine receptor subunit alpha-5 (CHRNA5) and nicotine dependence to current smoking and initial smoking-experience phenotypes.
Design, setting, participants Case–control association study with a community-based sample, comprising 363 Caucasians and 72 African Americans (203 cases, 232 controls).
Measurements Cases had smoked ≥ five cigarettes/day for ≥ 5 years and had smoked at their current rate for the past 6 months. Controls had smoked between one and 100 cigarettes in their life-time, but never regularly. Participants also rated, retrospectively, pleasurable and displeasurable sensations experienced when they first smoked. We tested for associations between smoking phenotypes and the top 25 SNPs tested for association with nicotine dependence in a previous study.
Findings A non-synonymous coding SNP in CHRNA5, rs16969968, was associated with case status [odds ratio (OR) = 1.5, P = 0.01] and, in Caucasians, with experiencing a pleasurable rush or buzz during the first cigarette (OR = 1.6, P = 0.01); these sensations were associated highly with current smoking (OR = 8.2, P = 0.0001).
Conclusions We replicated the observation that the minor allele of rs16969968 affects smoking behavior, and extended these findings to sensitivity to smoking effects upon experimentation. While the ability to test genetic associations was limited by sample size, the polymorphism in the CHRNA5 subunit was shown to be associated significantly with enhanced pleasurable responses to initial cigarettes in regular smokers in an a priori test. The findings suggest that phenotypes related to subjective experiences upon smoking experimentation may mediate the development of nicotine dependence.
