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

描述(由申请人提供)：大量文献表明，伏核(NAC)中的多巴胺(DA)信号是成瘾相关和目标导向行为的关键中介。因此，人们对了解DA可以改变NAC的激发活性和调节行为的分子机制很感兴趣。Bonci实验室之前的研究发现，DAD1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受体的活动维持的。此外，NAC中的大麻素1型(CB1)受体也可以关键地调节动机行为。因此，本研究的主要目的是利用体外技术，特别是成年雄性大鼠NAC脑片的全细胞膜片钳电生理学，了解内源性大麻素(ECB)和CB1受体活性与多巴胺受体相互作用增强NAC放电活性的分子机制。长期目标是了解NAcore CB1和多巴胺受体是如何相互作用来驱动适应性和病理性动机行为的，希望为人类神经疾病开发新的治疗干预措施。我的初步数据表明，CB1受体拮抗剂阻止了D1/D2协同增强NAC核心放电，表明ECB对CB1受体的激活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。具体目标1将研究CB1受体在D1/D2介导的NAC核心放电增强中的作用。CB1受体的作用将用几种不同的CB1受体拮抗剂来确定。CB1受体的作用也将通过研究CB1受体激动剂是否能单独增强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验。《特定目的2》将研究CB1受体激活促进NAC核心激活的细胞内途径。特别是，将使用PLC的抑制剂以及FAAH和MGL的抑制剂来检查介导CB1/D1/D2相互作用的ECB的同一性。PLC是一种对几种ECB合成途径至关重要的酶，FAAH和MGL是水解ECB AEA和2-AG的抑制剂。此外，还将用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受体激动剂联合使用来增加NAC核心放电。综上所述，这些实验将提供有关欧洲央行在D1/D2介导的NAC放电增强中起关键作用的重要信息，以及多巴胺和CB1受体相互作用增强NAC放电活性的可能机制(S)。为了促进这些目标的实现，我将接受赞助商、其他实验室成员和外部合作者的持续培训和指导，帮助我在相关研究文献中设计、实施和解释我的实验，并准备我的结果以供发表。 与公共健康相关：内源性大麻素(内源性大麻素)在中枢神经系统和外周调节许多不同的生物靶点，因此在许多生理过程中发挥关键作用，如疼痛、哮喘、青光眼、恶心、生殖、免疫系统和癌症以及神经退行性疾病，如帕金森氏病和阿尔茨海默病。对这一系统的药理学操作可能使我们能够确定几种神经疾病的新治疗干预措施，同时消除与大麻相关的不良副作用。这一提议的结果可能有助于识别新的信号相互作用，这些信号相互作用可能代表治疗成瘾或其他疾病的可能的药理靶点。

DESCRIPTION (provided by applicant): 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 1 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 2 will investigate intracellular pathways through which CB1 receptor activation could facilitate NAc core firing. In particular, the identity 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. PUBLIC HEALTH RELEVANCE: Endogenous cannabinoids (endocannabinoids) modulate many diverse biological targets both in the central nervous system and in the periphery, and therefore play a critical role in many physiological processes such as pain, asthma, glaucoma, nausea, reproduction, immune system and cancer and neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease. Pharmacological manipulation of this system may allow us to identify new therapeutic intervention for several neurological disorders while eliminating the undesirable side effects associated with cannabis. The results from this proposal may be useful in identifying novel signaling interactions that could represent possible pharmacological targets for treating addiction or other diseases.