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: 7554141
• 负责人: Deborah Jean Baro
• 金额: $ 32.51万
• 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/7554141
• 关键词: American; Binding; Biochemical; Catalytic Domain; Cells; Characteristics; Chronic; Cocaine; Cocaine Dependence; Confocal Microscopy; Cost of Illness; 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); Genes; Genetic Programming; Global Change; Grant; Hand; Hour; Imagery; 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; Prize; Process; Production; Proteins; Reporter; Reporting; Research Priority; Reverse Transcriptase Polymerase Chain Reaction; Rewards; Shal channel; Signal Transduction; Societies; Staging; Synapses; Techniques; Testing; Time; Transcript; addiction; classical conditioning; cocaine use; density; dopaminergic neuron; drug of abuse; neuroregulation; prevent; receptor; research study; response; reuptake; spatiotemporal; tool; transcription factor; voltage; voltage clamp

DESCRIPTION (provided by applicant): 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 densities 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. One of NIDA's top research priorities is finding drugs to block cocaine's effects. This will require an understanding of the mechanisms by which cocaine acts. Cocaine causes a prolonged exposure of neurons to dopamine, which in turn causes many alterations to neuronal function. This grant aims to understand the mechanisms by which prolonged dopamine alters neuronal function.

描述（由申请人提供）：药物滥用是一种慢性和毁灭性的疾病，每年使社会超过2000亿。这个问题很普遍； 2004年，超过3400万美国人报告了可卡因的终生使用。 NIDA的主要研究重点之一是找到可以阻止可卡因作用的药物，这将需要了解成瘾的分子机制。持续使用可卡因会导致与奖励相关的学习中的适应不良，因此尽管严重的负面后果（成瘾），该药物高于所有其他奖励，并在所有其他奖励中都受到了强迫的追捧和使用。可卡因可防止多巴胺（DA）再摄取。单剂量上瘾的药物可以将突触DA提升数小时。目前尚不清楚[DA]如何重复，延长高程破坏联想学习和记忆的正常机制。这样的过程取决于离子通过神经元膜中的通道的流动（离子电流）；因此，神经元膜中离子通道的密度和特征有助于确定神经元参与学习和记忆机制的能力。可卡因和DA都可以改变离子电流密度。也许可卡因引起的学习和记忆中的畸变是由于DA高度长时间导致的离子当前密度变化所致。阐明突触DA的长时间高程导致离子当前密度变化的过程可能会更深入地理解成瘾如何篡夺奖励相关学习和记忆的正常机制。瞬态钾电流（IA）对于学习和记忆很重要。 KV4通道介导IA。使用模型电路，甲壳类幽门网络，我们发现当DA与其受体D1和D2结合时，它们会产生全局的生化信号，这些信号在短期和长期内对IA密度具有不同的影响。例如，为了响应DA的短暂应用，D2受体介导了IA密度的增加。另一方面，延长了4小时。 DA的应用产生D2介导的IA密度持续降低10-12小时。 DA被删除后。该提案着重于短暂和长时间应用对IA密度产生相反影响的机制。我们特别检验了DA诱导[CAMP]的全局变化的假设，该假设随后改变了KV4通道的磷酸化状态和名为CREB的转录因子的磷酸化状态。尽管KV4通道的变化是相对短暂的，但CREB活性的修改是长期的，并导致KV4转录数的变化。在这里，我们建议使用分子生物学和电生理技术来衡量和相关的全球[CAMP]，IA密度和SHAL转录数的变化。此外，药理学工具将用于对抗或模仿[CAMP]的全球变化，以确定它们是否是IA密度和SHAL转录数的变化的基础。此外，使用共聚焦显微镜的易位的显性阴性CREB蛋白和蛋白激酶A易位的可视化将有助于确定CREB是否参与介导长期反应。 NIDA最重要的研究重点之一是发现药物可以阻止可卡因的作用。这将需要了解可卡因作用的机制。可卡因导致神经元长期暴露于多巴胺，这又导致神经元功能的许多改变。该赠款旨在了解延长多巴胺改变神经元功能的机制。