Cannabinoid Regulation of CB1 Receptor Function

描述（由申请人提供）：CB1受体（CB1R）介导大麻中的主要精神活性成分德尔塔9-四氢大麻酚（THC）的精神活性作用，以及大麻素（CBs）在中枢神经系统中的治疗作用。然而，由于不良副作用和长期使用的耐受性和依赖性的发展，CBs的治疗使用受到限制。这些影响是由不同脑回路中的CB1R介导的，但使用传统的放射自显像图像分析，对CB1R的功能和结构的理解受到限制。慢性CB效应发生于g蛋白受体激酶/ β -抑制素介导的CB1R与g蛋白的解偶联（脱敏）和/或CB1R密度的降低（下调）。这些适应在中枢神经系统中因发展和恢复的幅度和时间进程等因素而有所不同。很少有研究调查慢性施用不同CBs所产生的区域特异性适应。此外，内源性大麻素或稳定类似物治疗的慢性效果尚不清楚。CB1R在中枢神经系统的广泛分布及其不同的神经调节作用表明，区域适应比以前所认识的更为复杂。此外，适应的区域差异可能是由于CB1R与调节蛋白（如β -arrestin-2）的不同共定位造成的。这些研究将检验慢性给药CB1R激动剂产生不同区域CB1R适应模式的假设。此外，由于区域特异性适应依赖于与不同调节蛋白的相互作用，基于它们与CB1R的解剖共分布，我们假设β -arrestin-2缺失小鼠的CB1R适应会降低。我们建议在重建的小鼠大脑中使用一种新的基于三维体素的成像分析来检查CB1R的适应性，这将为自放射成像数据提供前所未有的解剖学分析水平。这将在无偏倚的全脑基础上进行检查，分别使用激动剂刺激的[35S]GTPgammaS和[3H]配体放射自显影来评估cb1介导的g蛋白活性和受体。由于我们将在整个大脑中研究CB1R的适应性，并在体素水平上建立显著的变化，我们预测我们提出的研究将提供CB1R功能的全面功能解剖学研究，这将为CB系统提供新的见解。我们预测，这些适应也将与对大麻模拟效应的耐受性的发展有关。

DESCRIPTION (provided by applicant): CB1 receptors (CB1R) mediate the psychoactive effects of delta9-tetrahydrocannabinol (THC), the main psychoactive ingredient in marijuana, and therapeutic effects of cannabinoids (CBs) in the CNS. However, therapeutic use of CBs is limited by undesirable side effects and development of tolerance and dependence with chronic use. These effects are mediated by CB1R in diverse brain circuits, but understanding of the functional n euro an an atomy of CBs has been limited using conventional autoradiographic image analysis. Chronic CB effects occur by G-protein receptor kinase/beta-arrestin mediated uncoupling of CB1R from Gproteins (desensitization) and/or reduction in CB1R density (downregulation). These adaptations vary regionally in the CNS with regard to factors such as magnitude and time course for development and recovery. Few studies have investigated region-specific adaption produced by chronic administration of different CBs. Moreover, the chronic effect of treatment with endocannabinoids or stable analogs is unclear. The widespread CNS distribution of CB1R and their diverse neuromodulatory roles suggest a more intricate profile of regional adaptation than previously appreciated. In addition, regional differences in adaptation likely result from differential co-localization of CB1R with regulatory proteins, such as beta-arrestin-2. These studies will test the hypothesis that chronic administration of CB agonists produces differential regional patterns of CB1R adaptation. Further, because region-specific adaptation is dependent on interaction with different regulatory proteins, based on their anatomical co-distribution with CB1 R, we hypothesize that CB1R adaptation will be decreased in Beta-arrestin-2 null mice. We propose to examine CB1R adaptation using a novel 3D voxel-based imaging analysis in reconstructed mouse brains, which will provide an unprecedented level of anatomical analysis of autoradiographic data. This will be examined on an unbiased whole-brain basis, using agonist-stimulated [35S]GTPgammaS and [3H]ligand autoradiography to assess CB1-mediated G-protein activity and receptors, respectively. Because we will investigate CB1R adaptations in the whole brain and establish significant changes at the voxel level, we predict that our proposed studies will provide a comprehensive functional anatomical study of CB1R function that will offer new insight into the CB system. We predict that these adaptations will also be associated with the development of tolerance to cannabimimetic effects. PUBLIC HEALTH RELEVANCE: CBs offer potential therapeutic benefits to public health in the management of many debilitating medical conditions. For patients who are unresponsive to existing treatments, CB-based therapy offers alternatives in their clinical management.