Modulators of behavioral hypersensitivity to cocaine following DBH inhibition

DBH 抑制后可卡因行为超敏反应的调节剂

• 批准号: 7864256
• 负责人: Meriem Gaval Cruz
• 金额: $ 2.77万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7864256
• 关键词: Affect; Affinity; Agonist; Attenuated; Behavioral; Binding; Catecholamines; Chelating Agents; Chronic; Cocaine; Cocaine Dependence; Copper; Data; Disulfiram; Dopamine; Dopamine D2 Receptor; Dopamine Receptor; Dopamine-beta-monooxygenase; Enzyme Inhibition; Enzymes; Feeling; Genes; Genetic Polymorphism; Goals; Human; Hypersensitivity; Intake; Knockout Mice; Measures; Microdialysis; Mus; Neurobiology; Neurons; Norepinephrine; Paranoia; Pharmacotherapy; Promoter Regions; Reaction; Rewards; Signal Transduction; Testing; Therapeutic; Up-Regulation; Work; enzyme activity; in vivo; inhibitor/antagonist; insight; nepicastat; noradrenergic; pre-clinical; preference; psychostimulant; radioligand; receptor upregulation; response; success

DESCRIPTION (provided by applicant): Dopamine Beta Hydroxylase (DBH) is the catecholamine biosynthetic enzyme that converts dopamine (DA) to norepinephrine (NE) and controls the NE/DA ratio in noradrenergic neurons. Inhibition and low activity of this enzyme has been found to alter behavioral responses to cocaine. Dbh knockout mice are hypersensitive to the rewarding and aversive effects of cocaine and have reduced basal and psychostimulant-induced DA release. In humans, DBH expression, and therefore activity, is affected by a polymorphism in the promoter region of the Dbh gene. Low DBH activity is associated with increased feelings of paranoia following cocaine administration and increased success in attenuating cocaine intake when administered the pharmacological agent disulfiram (Antabuse). The mechanism of action by which disulfiram is decreasing cocaine-intake is not completely understood. As a copper chelator, disulfiram affects multiple enzymes. We hypothesize that disulfiram is causing altered responses to cocaine by inhibiting DBH (which requires copper as a co-factor). We believe that chronic inhibition of the enzyme, as that seen in Dbh -/- mice, leads to a compensatory upregulation of DA receptors. Therefore, when a psychostimulant such as cocaine is administered, there is an increase in dopaminergic signaling due to the increased number of DA receptors. Specifically, I believe D2 receptor upregulation and increased signaling are responsible for this response since Dbh -/- mice are hypersensitive to the behavioral effects of a D2 agonist, but not a D1 agonist. The overall goal of this project is to assess whether this hyperdopaminergic signaling underlies the aversive reactions to cocaine. I will use pharmacological inhibition of DBH in wildtype mice (via disulfiram and the selective DBH inhibitor nepicastat) to test this by 1) measuring how this affects basal and cocaine-induced catecholamine release using in vivo microdialysis; 2) examining its effect on high affinity state D2 receptors using radioligand binding and; 3) whether pharmacological DBH inhibition can elicit a D2-sensitive conditioned place aversion to cocaine. I will also use Dbh -/- mice to determine whether a D2 agonist can support a Conditioned Place Preference (CPP) and whether this can be blocked by a D2 antagonist. Given the dearth of cocaine addiction therapeutics and the small amount of preclinical data regarding the mechanism by which disulfiram works to decrease cocaine intake, these studies will shed insight into the neurobiology of cocaine addiction, and possibly identify specific targets for cocaine addiction pharmacotherapies.

描述（由申请人提供）：多巴胺β羟化酶（DBH）是儿茶酚胺生物合成酶，将多巴胺（DA）转换为去甲肾上腺素（NE），并控制脱甲肾上腺素的NE/DA比率。已经发现该酶的抑制作用和低活性改变了对可卡因的行为反应。 DBH敲除小鼠对可卡因的奖励和厌恶作用过敏，并减少了基础和精神刺激剂诱导的DA释放。在人类中，DBH表达以及活性受到DBH基因启动子区域的多态性的影响。低DBH活性与可卡因后的偏执狂感增加有关 当服用药理学剂二硫兰兰（Antabuse）时，给药并增加了可卡因摄入量的成功。二硫仑降低可卡因 - 智力的作用机制尚不完全了解。作为铜螯合剂，二硫仑会影响多种酶。我们假设二硫仑通过抑制DBH（需要铜作为副因子）引起对可卡因的反应改变。我们认为，如DBH - / - 小鼠所见，对酶的慢性抑制会导致DA受体的补偿性上调。因此，当 施用心理刺激剂，例如可卡因，由于DA受体的数量增加，多巴胺能信号的增加。具体而言，我认为D2受体上调和信号增加是导致此响应的原因，因为DBH - / - 小鼠对D2激动剂的行为效应过敏，但不是D1激动剂。该项目的总体目的是评估这种高胺能信号是否是对可卡因的厌恶反应的基础。我将使用野生型小鼠（通过二硫仑和选择性DBH抑制剂Nepicastat）中DBH的药理抑制作用来测试这一点，以1）测量这如何影响基础和可卡因诱导的儿童诱导的儿茶酚胺在使用体内微透析中释放； 2）使用放射性结合检查其对高亲和力D2受体的影响； 3）药理学DBH抑制是否可以引起对可卡因的D2敏感的地方厌恶。我还将使用DBH - / - 小鼠来确定D2激动剂是否可以支持条件的位置偏好（CPP），以及是否可以被D2拮抗剂阻止。鉴于可卡因成瘾疗法的缺乏以及少量有关二硫兰氏蛋白酶降低可卡因摄入量的机制的临床前数据，这些研究将深入了解可卡因成瘾的神经生物学，并可能识别可卡因成瘾药物治疗的特定目标。