Genetic Factors Underlying Risk for Methamphetamine Intake and Associated Traits

在没有药物暴露的情况下，可以在动物模型中评估风险作为人群指标， 许多战略，如通过使用选择性繁殖的动物品系。然而，建模风险不是一个 简单的过程，即使在非人类模型中，因为风险不是一个单一的结构;因此，多基因 必须考虑非遗传因素，风险因素可能因人而异。甲基苯丙胺 (MA)具有强烈的欣快效果，鼓励使用;但是，经过多年的研究，广泛有效 药物尚未确定。我们开发了一种遗传动物模型， 选择性地饲养高和低自愿MA饮用（MAHDR和MALDR），目的是识别 MA使用的遗传风险和保护因素。这些品系在与MA关键相关的多个MA性状上不同 使用障碍。我们绘制了小鼠10号染色体上的一个区域，该区域占遗传多样性的50%以上。 MA消耗量的变化，并获得了为痕量胺相关受体提供证据的数据 1基因Taar 1作为MA摄入量的数量性状基因。该应用程序侧重于MA风险中的Taar 1 使用，以及发现与Taar 1突变（Taar 1 m1 J）相关的风险增加的遗传修饰剂 编码一种非功能性受体TAAR 1这将通过确定 转录组的个体差异影响Taar 1 m1 J/m1 J基因型对MA摄入量的影响。我们 研究结果将指导检查治疗MA使用障碍的新机制。三个目标是 提出了在目标1中，CRISPR-Cas9 Taar 1 m1 J等位基因取代了TAAR 1功能恢复的小鼠 特别是在MAHDR小鼠（MAHDR-Taar 1 +/+）中，将与非替代对照（MAHDR-Taar 1 m1J/m1J）。可靠区分MAHDR和MALDR选择系的MA相关性状，其在Taar 1中不同 基因型，将被检查（即，MAHDR均为Taar 1 m1 J/m1 J，MALDR均为Taar 1 +/+或Taar 1 +/m1 J）。研究 与糖精（作为促味剂和自然奖励）和奎宁（作为促味剂）也将执行。行为 等位基因交换的有效性的评估将使用TAAR 1特异性激动剂进行测试。在目标2中， RNA-Seq数据将用于重组近交系小鼠（BXD）的基因表达网络分析 RI）均具有Taar 1 m1 J/m1 J基因型。目标是找出减少影响的遗传修饰剂 Taar 1 m1 J/m1 J基因型对MA摄入量的影响，因为它们可能导致新的治疗方法。伏隔核 (NAc)由于内侧壳在药物奖赏中的关键作用，将对其进行初步研究。在目标3中，RNA-Seq结果、数据 基础检索（DrugBank，Broad Institute Connectivity Map，PubChem at NCBI）和发表的结果将 用于提名神经靶点，以操纵其对MA摄入的影响，并最终确定新的 治疗。这项研究的长期目标是确定可以减少MA使用的新治疗方法， 与个体遗传易感性“标记”相匹配，由特定的基因星座组成。

Risk as a population measure can be assessed in animal models in the absence of drug exposure through a number of strategies, such as via the use of selectively bred animal lines. However, modelling risk is not a straightforward process, even in non-human models, since risk is not a unitary construct; thus, multiple genetic and non-genetic factors must be considered, and risk factors likely vary across individuals. Methamphetamine (MA) has powerful euphoric effects that encourage use; but, after many years of research, broadly effective medications have not been identified. We have developed a genetic animal model comprised of lines of mice selectively bred for high and low voluntary MA drinking (MAHDR and MALDR), with the goal of identifying genetic risk and protective factors for MA use. These lines differ for multiple MA traits critically relevant to MA use disorders. We mapped a region on mouse chromosome 10, that accounts for >50% of the genetic variance in MA consumption, and obtained data that provide evidence for the trace amine-associated receptor 1 gene, Taar1, as a quantitative trait gene for MA intake. This application is focused on Taar1 in risk for MA use, and on the discovery of genetic modifiers of the increased risk associated with a Taar1 mutation (Taar1m1J) that codes for a non-functional receptor; TAAR1. This will be accomplished through the identification of individual differences in the transcriptome that impact the effect of the Taar1m1J/m1J genotype on MA intake. Our findings will guide the examination of novel mechanisms for the treatment of MA use disorders. Three aims are proposed. In Aim 1, CRISPR-Cas9 Taar1m1J allele replaced mice, in which TAAR1 function has been restored specifically in MAHDR mice (MAHDR-Taar1+/+) will be compared to non-replaced controls (MAHDR-Taar1 m1J/m1J). MA-related traits that reliably differentiate the MAHDR and MALDR selected lines, which differ in Taar1 genotype, will be examined (i.e., MAHDR are all Taar1m1J/m1J and MALDR are Taar1+/+ or Taar1+/m1J). Studies with saccharin (as a tastant and a natural reward) and quinine (as a tastant) will also be performed. Behavioral assessment of the effectiveness of the allele swap will be tested using a TAAR1-specific agonist. In Aim 2, RNA-Seq data will be used in gene expression network analyses in recombinant inbred strains of mice (BXD RI) that all possess the Taar1m1J/m1J genotype. The goal is to identify genetic modifiers that reduce the impact of the Taar1m1J/m1J genotype on MA intake, because they could lead to new treatments. The nucleus accumbens (NAc) medial shell will be initially studied due for its critical role in drug reward. In Aim 3, RNA-Seq results, data base searches (DrugBank, Broad Institute Connectivity Map, PubChem at NCBI) and published results will be used to nominate neural targets to manipulate for their impact on MA intake and ultimately to identify novel treatments. The long-term goal of this research is to identify novel treatments that could reduce MA use, based on matching to individual genetic susceptibility “markers”, comprised of specific constellations of genes.