Fine Mapping Genes for Cocaine Locomotor Response in ENU Mutagenized Mice

描述(由申请人提供)：易对包括可卡因和安非他明在内的精神刺激剂以及酒精等其他药物上瘾，受遗传和环境因素的影响。遗传因素可能会调节人类对药物滥用的不同初始反应，这与发展成药物滥用障碍的倾向有关。应激反应通路的异常适应也与药物依赖的发展有关，尽管这种关系已经确立，但其潜在的神经生物学机制尚未被很好地理解。虽然目前还不存在复制人类药物滥用综合征全谱的动物模型，但存在某些与药物相关的行为的动物模型，包括急性运动激活、行为敏化和对药物治疗的条件性位置偏爱，以及药物自我给药的速度。我们已经鉴定出一个ENU诱导的突变体Highper，它在一个新的环境中表现出多动，对精神刺激剂可卡因和哌醋甲酯的夸大运动反应，以及在急性应激源后皮质酮的长期释放。我们认为，这些动物表现出的异常应激和药物反应是相关的；我们的假设是，先前暴露在应激事件中会加剧对心理刺激剂的夸大运动反应。利用单核苷酸多态(SNP)基因分型，我们将Highper突变定位在12号染色体上一个59兆碱基的区域，该区域包含411个基因，其中没有一个基因与药物和应激反应有关。因此，Highper可能为研究应激和药物反应行为域之间的关系提供了一种新的模型。在这个建议中，我们概述了一个实验策略来解决我们的三个主要目标：1)进一步描述Highper系，以更好地了解异常应激和心理刺激反应以及两者之间的联系；2)精细定位和鉴定致病突变；3)表征体内和体外基因突变所造成的功能障碍。

DESCRIPTION (provided by applicant): Vulnerability to develop addiction to psychostimulants, including cocaine and amphetamine, as well as other drugs, like alcohol, is influenced by both genetic and environmental factors. Genetic factors may modulate differing initial responses to drugs of abuse in humans and this has been linked to the propensity to develop a drug abuse disorder. Abnormal adaptations in stress response pathways have also been implicated in the development of drug dependence and while this relationship is firmly established, the underlying neurobiological mechanisms are not well understood. While no animal model exists that reproduces the entire spectrum of the drug abuse syndrome in humans, animal models do exist for certain drug-related behaviors including acute locomotor activation, behavioral sensitization and conditioned place preference in response to drug treatment, as well as rates of drug self-administration. We have identified an ENU-induced mutant, Highper, that shows hyperlocomotion in a novel environment, an exaggerated locomotor response to the psychostimulants cocaine and methylphenidate and a prolonged release of corticosterone following an acute stressor. We believe that the abnormal stress and drug responses exhibited by these animals are related; our hypothesis is that the exaggerated locomotor response to psychostimulants is exacerbated by previous exposure to stressful events. Using single nucleotide polymorphism (SNP) genotyping, we have mapped the Highper mutation to a 59 megabase region on chromosome 12. This region contains 411 genes, none of which has previously been implicated in both drug and stress responses. Thus, Highper may represent a novel model for studying the relationship between the stress and drug response behavioral domains. In this proposal, we outline an experimental strategy to address our three primary goals: 1) to further characterize the Highper line to better understand the abnormal stress and psychostimulant responses and the link between the two 2) to fine map and identify the causative mutation and 3) to characterize the functional disruption caused by the gene mutation both in vivo and in vitro.