Functional studies of cannabinoid receptor-interacting protein 1a in null mice

描述（由申请人提供）：大麻素CB 1受体介导δ 9-四氢大麻酚（THC）（大麻中的主要精神活性成分）和内源性大麻素的CNS效应。该系统在药物滥用中起作用，并且具有治疗恶心、食欲障碍、肌肉痉挛和慢性疼痛、神经变性疾病和情绪障碍的治疗潜力。然而，大麻/THC有副作用，包括镇静，协调和短期记忆障碍，以及滥用倾向，这限制了它们的效用。更好地了解调节CB 1受体的机制可能会导致针对该系统的改进策略，包括选择性靶向受体与调节蛋白相互作用的潜力。该项目将使用空小鼠模型研究大麻素受体相互作用蛋白1a（CRIP 1a）的功能。CB 1受体是抑制突触神经传递的G蛋白偶联受体。我们在共表达CRIP 1a与CB 1受体的细胞模型中发表的和初步的数据表明，CRIP 1a抑制CB 1受体的基础（组成型）和激动剂诱导的G蛋白活化，而不影响受体表达水平。我们建议研究CRIP 1a基因缺失对生物表型的影响，包括体重增加，体温，运动活动和协调，焦虑和疼痛敏感性。然后，我们将研究CRIP 1a缺失对THC体内药理作用的影响，以及对与大麻素作用相关的CNS区域中CB 1受体表达和G蛋白活化的影响。假定CRIP 1a负调节CB 1受体，因此我们将检验CRIP 1a缺失小鼠将显示以下表型的假设：1）模拟THC给药（体重增加、体温过低、抗焦虑、运动不足、协调性降低、抗伤害感受）和/或2）增强THC的药效学效力或功效。我们将进一步检验这一假设，即这些效应将与特定CNS区域中CB 1受体介导的G蛋白活性增强相关，并预测CRIP 1a缺失的效应将存在CNS区域特异性差异，对应于对行为和体内THC敏感性的不同效应。

DESCRIPTION (provided by applicant): Cannabinoid CB1 receptors mediate the CNS effects of delta9-tetrahydrocannabinol (THC), the main psychoactive constituent in marijuana, and the endogenous cannabinoids. This system plays a role in drug abuse, and has therapeutic potential for treatment of nausea, appetite disorders, muscle spasticity and chronic pain, neurodegenerative diseases and mood disorders. However, marijuana/THC have side effects, including sedation, impairment of coordination and short-term memory, and abuse liability, which limits their utility. A better understanding of mechanisms that regulate CB1 receptors could lead to improved strategies to target this system, including the potential to selectively target receptor interaction with regulatory proteins. The proposed project will investigate the function of cannabinoid receptor-interacting protein 1a (CRIP1a) using a null mouse model. CB1 receptors are G-protein-coupled receptors that inhibit synaptic neurotransmission. Our published and preliminary data in cell models co-expressing CRIP1a with CB1 receptors indicate that CRIP1a inhibits both basal (constitutive) and agonist-induced G-protein activation by CB1 receptors without affecting receptor expression levels. We propose to investigate the effects of genetic deletion of CRIP1a on biological phenotype, including weight gain, body temperature, motor activity and coordination, anxiety and pain sensitivity. We will then examine effects of CRIP1a deletion on the pharmacological actions of THC in vivo, and on CB1 receptor expression and activation of G-proteins in CNS regions associated with cannabinoid effects. CRIP1a is postulated to negatively regulate CB1 receptors, so we will test the hypothesis that CRIP1a null mice will display a phenotype that could: 1) mimic the administration of THC (weight gain, hypothermia, anxiolysis, hypolocomotion, reduced coordination, antinociception) and/or 2) enhance the pharmacodynamic potency or efficacy of THC. We further will test the hypothesis that these effects will be associated with enhancement of CB1 receptor-mediated G-protein activity in specific CNS regions, and predict there will be CNS region-specific differences in the effects of CRIP1a deletion corresponding to different effects on behavior and in vivo sensitivity to THC.