Fine Mapping Genes for Cocaine Locomotor Response in ENU Mutagenized Mice

描述（由申请人提供）：容易对精神兴奋剂上瘾，包括可卡因和安非他明，以及其他药物，如酒精，受到遗传和环境因素的影响。遗传因素可能调节人类对药物滥用的不同初始反应，这与发展为药物滥用障碍的倾向有关。应激反应通路中的异常适应也与药物依赖的发展有关，尽管这种关系已经牢固确立，但潜在的神经生物学机制尚未得到很好的理解。虽然没有动物模型可以再现人类药物滥用综合征的全部谱系，但确实存在某些药物相关行为的动物模型，包括对药物治疗的急性运动激活、行为敏化和条件位置偏好，以及药物自我给药率。我们已经确定了一种enu诱导的突变体Highper，它在新环境中表现出过度运动，对精神兴奋剂可卡因和哌甲酯的过度运动反应，以及急性应激源后皮质酮的延长释放。我们认为这些动物表现出的异常应激与药物反应是相关的；我们的假设是，对精神兴奋剂的过度运动反应因先前的压力事件而加剧。利用单核苷酸多态性（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。这个区域包含411个基因，这些基因之前都没有涉及到药物和应激反应。因此，Highper可能为研究应激与药物反应行为域之间的关系提供了一种新的模型。在本提案中，我们概述了一个实验策略，以解决我们的三个主要目标：1)进一步表征Highper线，以更好地了解异常应激和精神刺激反应以及两者之间的联系；2)精细绘制和识别致病突变；3)表征由基因突变引起的体内和体外功能破坏。

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.