Role of dopamine-glutamate receptor heteromers and downstream nuclear calcium signaling in addiction

与其他精神疾病一样，成瘾与多巴胺(DA)和谷氨酸(Glu)介导的大脑突触传递的失衡有关。这项建议的一个中心目标是建立靶向DA受体(DAR)和NMDARs之间的串扰的手段，而不是针对单个受体的功能，这可能为新的、更特异和有效的治疗提供基础。纹状体中DA_1受体(D1Rs)和NMDAR相互作用形成的异构体控制突触可塑性和可卡因诱导的信号传递。我们将探索DAR/NMDAR异构体及其下游的核钙信号在成瘾发生中的作用，并为设计新的抗瘾药物确定关键靶点。合作伙伴1和2建立了新的方法来检测DAR/NMDAR异构体并阻止与它们相关的信号事件。D1R/GluN1和D2R/GluN2B异构体的调节将在可卡因诱导的精神运动敏化过程中的整个奖赏回路中进行研究，并在自然奖赏的背景下进行。我们的初步数据表明，在精神运动敏化过程中，小鼠纹状体中D1R/GluN1异构体急剧增加。将开发基于病毒的方法，以特定区域和时间受控的方式阻止异构体的形成，以确定它们在可卡因成瘾中的功能。D1R/GluN1异构体的破坏抑制了培养的纹状体中型棘神经元(MSN)核钙信号的产生。Partner 3已经证实，核钙瞬变是将神经元活动的变化与基因转录和记忆巩固联系起来的关键事件。伙伴1和伙伴3将研究这种特殊的钙池在成瘾环境中的作用。合作伙伴3将研究在可卡因诱导的精神运动敏化过程中，D1R-MSN或D2R-MSN中纹状体中核钙信号的动态变化，同时使用或不使用异构体形成阻滞剂。核钙信号阻滞剂将被用来建立与长期行为适应、神经元形态变化和基因表达谱之间的因果联系。为了解决在临床前/临床研究中使用多肽相关的困难，合作伙伴4将筛选一个库，寻找专门针对DAR/NMDAR异构体的非肽化合物。将在体外和体内测试先导化合物是否有能力干扰内源性异构体、其下游的核钙信号以及与可卡因成瘾相关的行为变化。这个项目可能导致在寻找新的靶点方面向前迈进一大步，这些靶点不仅对成瘾有治疗潜力，而且对其他各种精神疾病也有治疗潜力，这些疾病伴随着纹状体中DA和Glu介导的突触传递的失衡而引起的奖赏系统功能障碍。

Addiction, like other psychiatric disorders, is associated with an imbalance of dopamine (DA) and glutamate (Glu) mediated synaptic transmission in the brain. A central goal of this proposal is to establish means of targeting the crosstalk between DA receptors (DARs) and NMDA-type glutamate receptors (NMDARs), rather than the functions of the individual receptors, which may provide the basis for novel, more specific and effective therapies. Heteromers that are formed by the interaction of DA D1 receptors (D1Rs) and NMDARs in the striatum control synaptic plasticity and cocaine-induced signaling. We will explore the role of DAR/NMDAR heteromers and their downstream nuclear calcium signaling in the development of addiction and identify key targets for the design of novel pharmacological tools to combat addiction. Partners 1 and 2 set up novel approaches to detect DAR/NMDAR heteromers and to block the signaling events associated with them. The modulation of D1R/GluN1 and D2R/GluN2B heteromers will be studied in the entire reward circuitry during cocaine-induced psychomotor sensitization and in the context of natural reward. Our preliminary data indicate a dramatic increase of D1R/GluN1 heteromers in the striatum of mice during psychomotor sensitization. Viral-based approaches will be developed to block, in a region-specific and temporally controlled manner, heteromer formation in order to determine their functions in cocaine addiction. Disruption of D1R/GluN1 heteromers inhibits the generation of nuclear calcium signals in cultured striatal medium-size spiny neurons (MSNs). Partner 3 has established that nuclear calcium transients are critical events linking changes in neuronal activity to gene transcription and memory consolidation. Partners 1 and 3 will study the role of this particular pool of calcium in the context of addiction. Partner 3 will study the dynamics of nuclear calcium signals in the striatum in D1R-MSN or D2R-MSN in freely moving mice during cocaine-induced psychomotor sensitization with or without pretreatment with blockers of heteromer formation. Blockers of nuclear calcium signaling will be used to establish causal links to long-term behavioral adaptations, changes of the neuronal morphology and gene expression profiles. To address the difficulties associated with the use of peptides in pre-clinical/clinical studies, partner 4 will screen a library for non-peptide compounds that target specifically DAR/NMDAR heteromers. Lead compounds will be tested in vitro and in vivo for their ability to disrupt endogenous heteromers, their downstream nuclear calcium signaling and cocaine addiction associated behavioral alterations. This project may lead to a major step forward towards identifying new targets with therapeutic potentials not only for addiction but also for various other psychiatric diseases that are accompanied by dysfunctions of the reward system due to an imbalance of DA and Glu mediated synaptic transmission in the striatum.