MODULATION OF DOPAMINE AUTORECEPTOR FUNCTION BY COCAINE

可卡因对多巴胺自身受体功能的调节

• 批准号: 2121579
• 负责人: KAREN L O'MALLEY
• 金额: $ 20.58万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-02-01 至 1997-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2121579
• 关键词: G protein; cocaine; dopamine; dopamine receptor; drug interactions; enzyme activity; enzyme inhibitors; membrane channels; molecular cloning; neurotransmitter biosynthesis; neurotransmitter transport; pertussis toxin; phosphatase inhibitor; phosphorylation; receptor expression; receptor sensitivity; tissue /cell culture; transfection; tyrosine 3 monooxygenase

The long term goal of this project is to define the molecular interactions of cocaine with dopaminergic systems. Many of the behavioral effects of cocaine are attributed to its ability to block the reuptake of dopamine in mesolimbic neurons. Consequently, increased extracellular dopamine may enhance postsynaptic transmission and/or modulate presynaptic dopamine receptors known to inhibit neurotransmitter synthesis as well as further release. The specific aim of this application is to dissect this system by focussing on presynaptic events associated with cocaine's purported modulation of dopamine autoreceptors. Towards this end, model neuronal systems have been engineered by transfecting immortalized mesencephalic dopamine producing cell lines with cloned D2 and D3 receptors. While traditionally D2 receptors have been implicated in autoreceptor function, it is not known which of the D2-like subtypes subserves autoregulation of release and/or synthesis. To test the hypothesis that the D2-like receptors subserve different roles, the transfected cell lines will be systematically tested for receptor mediated effects on synthesis and release. Preliminary results show that agonist stimulation ofD2 and D3 receptors lead to subtype specific reductions in dopamine release and synthesis. These data imply specific roles for each receptor and suggest the effects of cocaine may vary depending upon receptor subtype. Studies outlined in this proposal will l) determine the effect of various D2 agonists on dopamine release in the individual transfected cell lines as well as the general roles of pertussis toxin, cation channels, desensitization and phosphorylation pathways in modulating this response. 2) Determine the role of receptor stimulation and desensitization on dopamine synthesis by measuring tyrosine hydroxylase activity and changes in the state of tyrosine hydroxylase phosphorylation. The roles of various signal transduction pathways will be tested by using specific protein kinase and phosphatase inhibitors to alter autoregulation of dopamine synthesis. In either case receptor coupling to specific GTP binding proteins will be tested for using mutant G proteins. 3) Test the effect of acute and chronic cocaine on autoreceptor function in both the release and synthesis paradigms. These studies have direct implications for understanding the presynaptic mechanisms involved in the reinforcing and behavior sensitization effects of cocaine.

这个项目的长期目标是确定分子间的相互作用 可卡因与多巴胺能系统许多行为影响 可卡因是由于它能够阻止多巴胺的再摄取， 中脑边缘神经元因此，细胞外多巴胺的增加可能 增强突触后传递和/或调节突触前多巴胺 已知抑制神经递质合成的受体以及进一步 release.本申请的具体目的是通过以下方式剖析该系统： 专注于与可卡因相关的突触前事件 多巴胺自身受体的调节。为此，模型神经元 系统已经通过移植永生化的中脑 具有克隆的D2和D3受体的多巴胺产生细胞系。而 传统上D2受体与自身受体功能有关， 目前尚不清楚哪种D2样亚型有助于自身调节， 释放和/或合成。为了验证D2样蛋白 受体具有不同的作用，转染的细胞系将 系统测试了受体介导的对合成的影响， release.初步结果表明，D2和D3的激动剂刺激 受体导致多巴胺释放的亚型特异性减少， 合成.这些数据暗示了每种受体的特定作用， 可卡因的作用可根据受体亚型而变化。研究 1）确定各种D2的影响 激动剂对单个转染细胞系中多巴胺释放的影响， 以及百日咳毒素，阳离子通道， 脱敏和磷酸化途径调节这种反应。 2)确定受体刺激和脱敏对 通过测量酪氨酸羟化酶活性和变化来合成多巴胺 处于酪氨酸羟化酶磷酸化状态。各种角色 将通过使用特定蛋白质来测试信号转导途径 激酶和磷酸酶抑制剂改变多巴胺自动调节 合成.在任一情况下，受体偶联至特异性GTP结合 将使用突变G蛋白测试蛋白。3)测试的效果 急性和慢性可卡因对自身受体功能的影响， 综合范式这些研究直接影响到 理解参与强化的突触前机制， 可卡因的行为敏化作用。