Mechanisms underlying opposing neuronal responses to brief vs. prolonged dopamine

神经元对短暂多巴胺和长时间多巴胺反应相反的机制

• 批准号: 7790835
• 负责人: Deborah Jean Baro
• 金额: $ 2.7万
• 依托单位: GEORGIA STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-01-05 至 2012-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7790835
• 关键词: American; Animal Welfare; Bibliography; Binding; Biochemical; Catalytic Domain; Cells; Characteristics; Chronic; Cocaine; Cocaine Dependence; Confocal Microscopy; Cost of Illness; Country; Crustacea; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cyclic AMP-Responsive DNA-Binding Protein; Distant; Dominant-Negative Mutation; Dopamine; Dopamine D2 Receptor; Dopamine Receptor; Dose; Drug Addiction; Drug abuse; Electrodes; Electrophysiology (science); Environment; Environmental Impact; Equipment; Genes; Genetic Programming; Global Change; Grant; Hand; Hour; IACUC; Imagery; International; Ion Channel; Ions; Kv4 channel; Kv4.2 channel; Lead; Learning; Life; Long-Term Effects; Long-Term Potentiation; Measures; Mediating; Membrane; Memory; Modeling; Modification; Molecular; Molecular Biology; Monitor; Mus; Names; Neuromodulator; Neurons; Nuclear Translocation; Pathway interactions; Pharmaceutical Preparations; Phosphorylation; Potassium; Principal Investigator; Prize; Process; Production; Proteins; Reporter; Reporting; Research; Research Ethics Committees; Research Priority; Resources; Reverse Transcriptase Polymerase Chain Reaction; Rewards; Shal channel; Signal Transduction; Societies; Staging; Synapses; Techniques; Testing; Time; Transcript; Vertebrates; abstracting; addiction; classical conditioning; cocaine use; density; dopaminergic neuron; drug of abuse; expiration; human subject; neuroregulation; prevent; programs; receptor; research study; response; reuptake; spatiotemporal; tool; transcription factor; voltage; voltage clamp

Drug abuse is a chronic and devastating disease, costing society over 200 billion per year. The problem is widespread; in 2004, over 34 million Americans reported lifetime use of cocaine. One of NIDA's top research priorities is finding drugs to block cocaine?s effects, which will require an understanding of the molecular mechanisms of addiction. Persistent use of cocaine leads to maladaptations in reward-related learning such that the drug is prized above all other rewards, and is compulsively sought after and used, despite severe negative consequences (addiction). Cocaine prevents dopamine (DA) reuptake. A single dose of an addictive drug can elevate synaptic DA for hours. It is not clear how repeated, prolonged elevations in [DA] disrupt the normal mechanisms of associative learning and memory. Such processes depend upon the flow of ions through channels in the neuronal membrane (ion currents); therefore, the densites and characteristics of ion channels in the neuronal membrane help to determine the neuron?s capacity to engage in mechanisms of learning and memory. Both cocaine and DA are known to alter ion current densities. Perhaps cocaine-induced aberrations in learning and memory are due to changes in ion current densities resulting from prolonged elevations in DA. Elucidating the processes by which prolonged elevations in synaptic DA lead to changes in ion current densities may lead to a deeper appreciation for how addiction usurps the normal mechanisms of reward related learning and memory. The transient potassium current (IA) is important for learning and memory. Kv4 channels mediate IA. Using a model circuit, the crustacean pyloric network, we found that when DA binds to its receptors, D1 and D2, they produce global biochemical signals that have different effects on IA density over the short- and long-term. For example, in response to a brief application of DA, D2 receptors mediate an increase in IA density. On the other hand, a prolonged 4hr. application of DA produces a D2 mediated, persistent decrease in IA density 10-12 hrs. after DA has been removed. This proposal focuses on the mechanism(s) by which brief versus prolonged applications of DA produce opposing effects on IA density. We specifically test the hypothesis that DA induces global changes in [cAMP] that then alter the phosphorylation state of both Kv4 channels and a transcription factor named CREB. Whereas changes in Kv4 channels are relatively short-lived, modifications in CREB activity are long-lived and result in alterations in Kv4 transcript number. Here we propose to use molecular biology and electrophysiology techniques to measure and correlate changes in global [cAMP], IA density and shal transcript number. Furthermore, pharmacological tools will be used to antagonize or mimic global changes in [cAMP] to determine if they underlie the changes in IA density and shal transcript number. Additionally, expression of a dominant-negative CREB protein and visualization of protein kinase A translocation using confocal microscopy will help to determine if CREB is involved in mediating the long-term response.

药物滥用是一种慢性、毁灭性的疾病，每年给社会造成的损失超过 2000 亿美元。问题是 广泛; 2004年，超过3400万美国人报告终生吸食可卡因。 NIDA 的顶级研究之一 首要任务是寻找药物来阻止可卡因的作用，这需要了解分子机制 成瘾机制。持续使用可卡因会导致奖励相关学习的适应不良，例如 该药物的价值高于所有其他奖励，并且尽管存在严重的后果，但仍然受到人们的强烈追捧和使用 负面后果（成瘾）。可卡因可阻止多巴胺 (DA) 的再摄取。单剂量的成瘾物质 药物可使突触 DA 升高数小时。目前尚不清楚 [DA] 的反复、长时间升高如何破坏 联想学习和记忆的正常机制。这些过程取决于离子的流动 通过神经元膜中的通道（离子电流）；因此，离子的密度和特性 神经元膜上的通道有助于确定神经元参与以下机制的能力 学习和记忆。众所周知，可卡因和 DA 都会改变离子电流密度。也许是可卡因引起的 学习和记忆的失常是由于长时间的学习和记忆造成的离子电流密度的变化造成的。 DA 中的高程。阐明突触 DA 长期升高导致 DA 变化的过程 离子电流密度可能会导致人们更深入地了解成瘾如何篡夺正常机制 奖励相关的学习和记忆。 瞬时钾电流（IA）对于学习和记忆很重要。 Kv4 通道调解 IA。 使用模型电路（甲壳类动物幽门网络），我们发现当 DA 与其受体 D1 和 D2 结合时， 它们产生全局生化信号，对短期和长期的 IA 密度产生不同的影响。 例如，短暂使用 DA 后，D2 受体会介导 IA 密度增加。上 另一方面，延长了4小时。应用 DA 会产生 D2 介导的 IA 密度持续降低 10-12 小时。 DA 被删除后。该提案重点关注短期与长期的机制 DA 的应用会对 IA 密度产生相反的影响。我们专门检验了 DA 诱导的假设 [cAMP] 发生全局变化，从而改变 Kv4 通道和转录的磷酸化状态 名为 CREB ​​的因子。虽然 Kv4 通道的变化相对短暂，但 CREB ​​的修改 活性是长期存在的并导致 Kv4 转录本数量的改变。这里我们建议使用分子 生物学和电生理学技术来测量和关联整体 [cAMP]、IA 密度和 应成绩单编号。此外，药理学工具将用于对抗或模仿全球变化 [cAMP] 中以确定它们是否是 IA 密度和 shal 转录本数量变化的基础。此外， 使用显性失活 CREB ​​蛋白的表达和蛋白激酶 A 易位的可视化 共聚焦显微镜将有助于确定 CREB ​​是否参与介导长期反应。