Interactions Between CB1 Receptor and DA Receptors in the Nucleus Accumbens Core

6.项目总结/摘要 大量的文献表明，多巴胺（DA）信号在延髓核（NAc）是一个关键的介导剂成瘾相关的和目标导向的行为。因此，有相当大的兴趣，了解DA可以改变NAc的发射活动和调节行为的分子机制。Bonci实验室以前的研究发现，DA D1和D2受体的协同激活增加了NAc神经元的放电。有趣的是，许多动机和成瘾相关的行为是由NAc中的D1和D2受体的活性维持的。此外，NAc中的大麻素1型（CB 1）受体也可以严格调节动机行为。因此，本提案的主要目标是使用体外技术，特别是在从成年雄性大鼠制备的NAc脑切片中的全细胞膜片钳电生理学，以了解内源性大麻素（eCBs）和CB 1受体活性可以与多巴胺受体相互作用以增强NAc放电活性的分子机制。长期目标是了解NAcore CB 1和多巴胺受体如何相互作用以驱动适应性和病理性动机行为，希望为人类神经系统疾病开发新的治疗干预措施。 我的初步数据表明，CB 1受体拮抗剂阻止D1/D2合作增强NAc核心放电，这表明CB激活CB 1受体可能在这一过程中发挥关键作用。然而，这种情况发生的细胞机制，特别是可能起作用的eCB类型，仍然未知。Specific Aim将研究CB 1受体对D1/D2介导的NAc核心放电增强的贡献。将用几种不同的CB 1受体拮抗剂确定CB 1受体的作用。CB 1受体的贡献也将通过研究CB 1受体激活剂是否可以单独增强NAc核心放电，或者是否需要与D1或D2受体激动剂相互作用来增强放电来检查。Specific Aim将研究CB 1受体激活促进NAc核心放电的细胞内途径。特别地，将使用PLC（一种对几种eCB合成途径至关重要的酶）的抑制剂和FAAH和MGL（其水解eCB AEA和2-AG）的抑制剂来检查介导CB 1/D1/D2相互作用的eCB的鉴定。此外，将用AEA或2-AG填充神经元，以确定这些eCB是否可以单独或与D1或D2受体激动剂组合增加NAc核心放电。总之，这些实验将提供有关eCB的重要信息，这些信息对D1/D2介导的NAc放电增强以及多巴胺和CB 1受体相互作用以增强NAc放电活性的可能机制有重要贡献。 为了促进实现这些目标，我将接受我的赞助商，其他实验室成员和外部合作者的持续培训和指导，包括设计，实施和解释我的实验，相关的研究文献，以及准备我的结果提交出版。

6. Project Summary/Abstract A vast literature has shown that dopamine (DA) signaling in the nucleus accumbens (NAc) is a critical mediator of addiction-related and goal-directed behaviors. Thus, there is considerable interest in understanding the molecular mechanisms through which DA can alter the NAc firing activity and modulate behavior. Previous studies from the Bonci lab found that cooperative activation of DA D1 and D2 receptors increases firing of NAc neurons. Interestingly, many motivated and addiction-related behaviors are sustained by activity of both D1 and D2 receptors in the NAc. Further, cannabinoid type-1 (CB1) receptors in the NAc can also critically regulate motivated behavior. Thus, the main goal of this proposal is to use in vitro techniques, in particular whole-cell patch-clamp electrophysiology in NAc brain slices prepared from adult male rats to understand the molecular mechanisms through which endogenous cannabinoids (eCBs) and CB1 receptor activity could interact with dopamine receptors to enhance NAc firing activity. The long-term goal is to understand how NAcore CB1 and dopamine receptors interact to drive adaptive as well as pathological motivated behaviors, with the hope of developing novel therapeutic interventions for human neurological conditions. My preliminary data indicate that CB1 receptor antagonists prevent the D1/D2 cooperative enhancement of NAc core firing, suggesting that eCB activation of CB1 receptors could play a critical role in this process. However, the cellular mechanisms through which this occurs, especially the type of eCB which might contribute, remain unknown. Specific Aim ¿ will examine the contribution of CB1 receptors to the D1/D2-mediated enhancement in NAc core firing. The role of CB1 receptors will be determined with several different CB1 receptor antagonists. The contribution of CB1 receptors will also be examined by investigating whether CB1 receptor activators can enhance NAc core firing alone, or whether interaction with a D1 or D2 receptor agonist is required to enhance firing. Specific Aim ¿¿ will investigate intracellular pathways through which CB1 receptor activation could facilitates NAc core firing. In particular, the identify of the eCB which mediates the CB1/D1/D2 interaction will be examined using inhibitors of PLC, an enzyme critical for several eCB synthesis pathways, and inhibitors of FAAH and MGL, which hydrolyze the eCBs AEA and 2-AG. Also, neurons will be filled with AEA or 2-AG to determine whether these eCBs can increase NAc core firing alone or in combination with D1 or D2 receptor agonists. Together, these experiments will provide important information about the eCB that contributes critically to the D1/D2-mediated enhancement in NAc firing and the possible mechanism(s) through which dopamine and CB1 receptors could interact to enhance NAc firing activity. To facilitate achieving these goals, I will receive ongoing training and mentoring from my sponsor, other lab members, and outside collaborators in the design, implementation, and interpretation of my experiments, in the relevant research literature, and the preparation of my results for submission for publication.