Novel CB Receptors

描述(申请人提供)：大麻类物质是大麻的主要精神活性成分，大麻是美国最常用的非法药物。除了滥用问题之外，人们还对大麻和大麻素的可能药用用途非常感兴趣。此外，操纵内源性大麻素系统显示出巨大的治疗前景。虽然已知大麻素通过结合CB1和CB2受体而产生生物效应，但强有力的实验证据表明，存在额外的大麻素受体。我们最近证实，孤儿受体GPR55构成了这样一种新的大麻素受体。具体地说，我们发现A9THC、JWH-015(一种合成的大麻素)和甲烷(一种稳定的内源性大麻类似物)在表达GPR55的HEK293细胞中激活了磷脂酶C，增加了细胞内钙，并刺激了p38 MAP激酶的磷酸化。RT-PCR检测，GPR55在脑、免疫系统、脂肪组织和睾丸以及培养的神经元、星形胶质细胞和小胶质细胞中都有高水平的表达。在这项申请中，我们描述了一项计划，以充分表征GPR55的分布和信号，并确定其在调节植物来源的、合成的和内源性大麻素类化合物的影响中的位置。我们将通过完成以下具体目标来完成这项工作：1.确定GPR55的组织和细胞分布。2.确定研究GPR55的最佳药理工具，并阐明其信号转导途径。3.确定GPR55如何调节神经元、小胶质细胞和脂肪细胞的功能。这些特定目标的完成将使我们能够评估GPR55作为另一种大麻素受体的作用，并将提供必要的药理学和分子工具来确定其参与调节大麻仿生效应。

DESCRIPTION (provided by applicant): Cannabinoids are the principal psychoactive component of cannabis, the most commonly used illicit drug in the United States. Going beyond the abuse issues there is also great interest in the possible medicinal use of cannabis and cannabinoids. Furthermore, manipulation of the endogenous cannabinoid system shows great therapeutic promise. While it is known that cannabinoids induce biological effects by engaging CB1 and CB2 receptors, strong experimental evidence suggests that additional cannabinoid receptors exist. We have recently confirmed that the orphan receptor GPR55 constitutes one such novel cannabinoid receptor. Specifically, we found that A9THC, JWH-015 (a synthetic cannabinoid) and methanandamide (a stable endocannabinoid analog) activate phospholipase C, increase intracellular calcium and stimulate p38 MAP kinase phosphorylation in GPR55-expressing HEK293 cells. GPR55 is expressed at high levels throughout the brain, immune system, adipose tissue and testis, as well as in neurons, astrocytes and microglial cells in culture, as assessed by RT-PCR. In this application we describe a plan to fully characterize GPR55 distribution and signaling, and determine its place in mediating the effects of plant-derived, synthetic and endogenous cannabinoids. We will do this by completing the following specific aims: 1. Determining the tissue and cellular distribution of GPR55. 2. Identifying the best pharmacological tools to study GPR55 and elucidating its signaling pathways. 3. Ascertaining how GPR55 regulates neuronal, microglial, and adipocyte functions. The completion of these specific aims will allow us to evaluate the role of GPR55 as an additional cannabinoid receptor, and will provide the necessary pharmacological and molecular tools required to determine its involvement in mediating cannabimimetic effects.