Genetic Approaches To Characterizing Drug Responses And Vulnerabilities: Mice

人和动物对滥用药物的行为、生理和毒理学反应存在很大的个体差异。在对药物的行为反应中，许多个体差异表现出实质性的遗传因素。转基因动物为实现几个相互关联的目标提供了手段：1)确定特定基因引入或中断的生化和行为后果；2)确定在人类研究中确定的过高或低表达候选基因的后果；3)阐明产生细胞类型特异性表达和跨突触基因调控的基因元件；4)研究不同基因组位点上的变异体之间相互作用的影响；5)阐明体内单倍型特异的表达差异水平；以及6)使我们能够监测突触连接性及其因给药和细胞黏附及其他重要脑分子中单倍型的变化而调节的情况。在这一年里，奖励、强化和学习的兴趣机制导致了对这些系统的继续关注，因为我们已经为识别脑片中的连接差异奠定了很多基础。 在对候选基因敲除(因为它们编码药物靶标和/或在感兴趣的电路中表达)的持续研究中，我们报告了关于这些敲除对a)可卡因(神经降压素KO)的适应性反应(MU/OPRM1基因敲除)b)由社会缺陷引起的压力反应(MU/OPRM1基因敲除)c)抗抑郁和止痛药(OPRM1基因敲除)d)物质诱导的多巴胺释放(MU/OPRM1基因敲除)e)脑电路(DAT/SLC6A4，SERT/SLC6A4和MU/OPRM1基因敲除)疼痛反应(DAT/SLC6A4，SERT/SLC6A4和MU/OPRM1基因)的不同影响的新数据。我们还帮助组胺机制的小鼠研究，并向许多国际合作者提供基因敲除小鼠。 我们已经开始了对细胞黏附基因改变的影响的研究，方法是启动对四个基因表达改变的小鼠的研究，我们的人类基因组广泛关联数据为这些基因提供了msot一致的复制。我们以抽象的形式报道，在人类中我们有最强证据的CDH13基因纯合或杂合缺失的小鼠，极大地降低了对可卡因配对环境的偏好。这些结果显示出特异性，因为可卡因保留了运动刺激，而且这些基因敲除的小鼠可以在Morris水迷宫和其他比较行为中表现出正常(或超常)的水平。初步数据支持在CDH13基因敲除中灭绝和恢复的幅度也有所降低的可能性。因此，这些动物提供了最好的小鼠确认全基因组关联的结果，这是复杂的、多基因的人类基因座造成的。

There are large individual differences among humans and animals in behavioral, physiological and toxicological responses to drugs of abuse. Many of these individual differences in behavioral responses to drugs display substantial genetic components. Transgenic animals provide means for approaching several interrelated goals: 1)Ascertainment of biochemical and behavioral consequences of the introduction of or disruption of specific genes; 2)Ascertainment of the consequences of over- or under-expressing candidate genes identified in human studies; 3) Elucidation of gene elements yielding cell-type specific expression and trans-synaptic gene regulation; 4) Studying influences of interactions between variants at different genomic loci; 5)Elucidating haplotype-specific levels of expression differences in vivo, and 6) allowing us to monitor synaptic connectivities and their modulation by drug administration and alterations in haplotypes in cell adhesion and other impoprtant brain molecules. Interest mechanisms of reward, reinforcement and learning have led to continuing focus on these systems during this year, as we have established much of the groundwork for identification of wiring differences in brain slices. In continuing studies of knockouts of candidate genes that are interesting because they encode drug targets and/or are expressed in circuits of interest, we have reported novel data concerning the differential influences of these knockouts on a) adaptive responses to cocaine (neurotensin KOs) b) stress engendered by social defect (mu/OPRM1 knockouts)c) antidepressants and analgesics (OPRM1 knockouots) d) substance-induced dopamine release (mu/OPRM1 knockouts) e) brain circuitry (DAT/SLC6A3 knockouts) and f) pain responses (DAT/SLC6A4, SERT/SLC6A4 and mu/OPRM1 knockouts). We also aided mouse studies of histamine mechanisms, and supplied knockout mice to many international collaborators. We have initiated studies of the influences of cell adhesion gene alterations by initiating studies of mice with altered expression of the four genes for which our human genome wide association datasests provide the msot consistent replication. We report in abstract form that mice with homozygous or heterozygous deletion of the gene for which we have the strongest evidence in humans, CDH13, dramatically reduce preference for cocaine paired environments. These results display specificity, since cocaine retains locomotor stimulation and since these knockout mice can perform at normal (or supranormal) levels in Morris water maze and other comparison behaviors. Initial data supports the possibility that the magnitude of extinction and reinstatement are also reduced in CDH13 knockouts. These animals thus provide one of the best mouse confirmations of a genome wide association result from a complex, polygenic human locus.