Genetic basis of methamphetamine intake

描述(由申请人提供)： 非法药物的滥用是一个世界性的问题，给个人和社会带来了许多负面后果。对甲基苯丙胺(MA)的上瘾会损害大脑，会导致精神错乱，并与犯罪和攻击性增加有关。包括退伍军人及其家属在内的军事人员已被确定为需要特别支助的关键人群，以处理他们的药物滥用问题。缺乏研究MA使用风险的遗传动物模型以及风险基础和不断升级的使用机制。本申请描述了一项重点研究人类甲基苯丙胺(MA)使用的遗传小鼠模型，以及确定影响MA滥用遗传风险的遗传因素和具体机制的研究。将被利用的是(1)独特的遗传工具，包括为饮用高和低MA而选择性培育的小鼠品系(Madr品系)和间隔特定的同源品系，用于更精细地定位影响MA摄入量的基因(S)；以及(2)新开发的可操作的MA口服自我给药方法，已被用于验证Madr品系是否为对MA增强效应表现出差异敏感性的遗传模型。这项研究计划将开发一种由基因决定的MA摄入量不断增加、狂欢的模型。它还将跟进定量Trat基因座(QTL)定位的结果，通过完成更精细的定位和序列分析，确定小鼠10号染色体上的一个基因座，该基因座占与MA不同摄入相关的遗传变异的约50%，这将使在识别影响MA成瘾遗传风险的基因和基因网络方面取得进展。初步数据支持u-阿片受体在这一风险中的重要性，将完成药理学和分子研究，以进一步测试这一机制的重要性。此外，分子分析将探索其他潜在的候选机制和基因敲除小鼠，可药物靶点的药理学方法将用于后续有希望的机制。有三个具体目标：(1)检查MA摄入、升级、暴饮暴食和恢复的遗传模式。对自然奖赏强化的敏感性的潜在差异 作为这一目标的一部分，还将进行以下工作：(2)利用现有的一组区间特定的同源菌株来更精细地定位染色体10的QTL；(2)测量这些遗传基因中的遗传相关性状，以检验小鼠10号染色体上的一个共同遗传区域影响MA饮酒及其相关性状的假设；(3)在精细定位了10号染色体上的QTL之后，完成qPCR、测序和蛋白质印迹分析，以寻找可能影响MA摄入的基因；利用这些数据，利用基因敲除和药理学方法，确定应该测试它们对MA摄入量影响的具体机制。也将完成对MADR系中MU-阿片受体的功能分析，MADR系是10号染色体区间的候选基因之一。这项工作有可能开发一种所需的高MA摄入量的遗传动物模型，该模型在开发该模型时利用现有的遗传风险。此外，对阿片系统参与的研究与正在进行的临床工作很好地吻合，这些工作表明，接受丁丙诺啡或美沙酮治疗(两种阿片受体激动剂)治疗阿片依赖的个人，MA的使用伴随着变化。使用遗传模型将表明使用MA的遗传风险较高的动物是否容易受到阿片类药物和所探索的其他药理干预的影响。

DESCRIPTION (provided by applicant): The abuse of illegal drugs poses a worldwide problem, with a multitude of negative individual and societal consequences. Addiction to methamphetamine (MA) damages the brain, can induce psychosis, and is associated with crime and increased aggression. Military personnel, including Veterans and their families, have been identified as among key populations requiring special support to deal with their drug abuse problems. Genetic animal models for investigating risk for MA use and mechanisms that underlie risk and escalating use are lacking. This application describes research focused on a genetic mouse model for human methamphetamine (MA) use and on the identification of genetic factors and specific mechanisms that influence genetic risk for MA abuse. To be utilized are (1) unique genetic tools that consist of lines of mice selectively bred for high and low MA drinking (the MADR lines) and of interval specific congenic strains to be used for finer mapping of a gene(s) that influences MA intake; and (2) a newly developed operant oral MA self-administration method that has been used to validate the MADR lines as a genetic model that shows differential sensitivity to the reinforcing effects of MA. This program of research will develop a model of genetically-determined escalating, binge-like MA intake. It will also follow up the results of quantitative trat locus (QTL) mapping, which identified a locus on mouse chromosome 10 that accounts for ~50% of the genetic variance associated with differential MA intake, by completing finer mapping and sequence analysis that will allow progress to be made in identifying genes and gene networks that influence genetic risk for MA addiction. Preliminary data support the importance of mu-opioid receptors in this risk and pharmacological and molecular studies will be completed to further test the importance of this mechanism. In addition, molecular analyses will explore other potential candidate mechanisms and knockout mice and pharmacological approaches for druggable targets will be used to follow-up promising mechanisms. There are 3 specific aims: (1) examine genetically-determined patterns of MA intake, escalation, binge-like intake, and reinstatement. Potential differences in sensitivity to reinforcement by natural rewards will also be examined as part of this aim; (2) use an existing panel of interval specific congenic strains to more finely map the chromosome 10 QTL; measure genetically correlated traits in these congenics to test the hypothesis that a common genetic region on mouse chromosome 10 influences MA drinking and the correlated trait; (3) complete qPCR, sequence and Western blot analyses, after fine mapping of the chromosome 10 QTL, for genes that could impact MA drinking; use these data to identify specific mechanisms that should be tested for their impact on MA intake, using knockout and pharmacological approaches. Functional analysis of the mu- opioid receptor in the MADR lines, one candidate gene in the chromosome 10 interval, will also be completed. This work has the potential for developing a needed genetic animal model of high MA intake that takes advantage of existing genetic risk in the development of this model. In addition, the study of opioid system involvement dovetails nicely with ongoing clinical work that indicates concomitant changes in MA use in individuals receiving buprenorphine or methadone treatment (both opioid receptor agonists) for opiate dependence. Use of the genetic model will indicate whether animals at higher genetic risk for MA use are susceptible to opioid and other pharmacological interventions that are explored.