Role of the CB1 receptor signaling in alcohol consumption

摘要 酒精成瘾的特点是对饮酒失去控制，导致发展为 耐受性和身体依赖性。遗传和环境因素都被证明是 在酒精成瘾的发展中起着重要作用;然而， 过量饮酒的问题还没有得到充分的理解。酒精似乎通过几种方式发挥作用 大脑中的信号传导系统。最近，内源性大麻素（eCB）系统脱颖而出 在这些系统中，就其在酒精成瘾中的功能重要性而言。已充分证实 CB 1受体刺激增加啮齿类动物的酒精消耗，而CB 1受体阻断 功能会减少这种行为。几项研究表明，神经肽Y（NPY）和 NPY-Y1受体基因和杏仁中央核（CeA）中较低的NPY表达促进了 饮酒行为。 基因转录因子cAMP反应元件结合（CREB）蛋白是一种常见的 它是CB 1和NPY信号传导的分母，在饮酒行为中也起着关键作用。删除 CREB基因和CREB功能缺陷的核壳（NAc壳） 和CeA与饮酒行为的增加有关，而将NPY注入 CeA已被证明可以增加CREB磷酸化并减少酒精摄入。表观遗传 由于组蛋白的修饰，如乙酰化，在调节中也很重要。 基因表达，并可能在酒精和药物成瘾的机制中发挥关键作用。CREB 激活募集CREB结合蛋白（CBP）的转录机制，催化乙酰化的 组蛋白H3和组蛋白H4通过其内在的组蛋白乙酰转移酶（HAT）活性从而调节 基因表达。目前尚不清楚CB 1受体和NPY系统是否通过CBP相互作用。 介导的组蛋白修饰在特定的神经回路，调节饮酒行为。 我们假设CB 1受体信号通过CREB-CBP介导的神经肽Y系统与神经肽Y系统相互作用。 NAc和杏仁核中的染色质重塑导致饮酒行为的调节。的 以下具体目标将检验这一假设： 1.检查a）由于CB 1受体基因缺失导致的酒精摄入量减少是否与以下因素有关： CREB、pCREB、CBP表达的代偿性增加，以及组蛋白（H3和 H4）NPY和NPY-Y1受体的乙酰化和表达，和; B）CBP表达的敲低 通过siRNA输注到NAc壳中，CeA减弱HAT诱导的组蛋白乙酰化（H3-K9和H4-K9）。 K8），以及CB 1-/-小鼠中的NPY和NPY-Y1表达，从而增加饮酒行为。 2.检查a）由于CB 1受体的药理学阻断而导致的酒精摄入量减少是否与 CREB、pCREB和CBP表达的增加，以及组蛋白乙酰化的增加（H3和H4）， B）如果通过siRNA敲低CBP表达 注入NAc壳或CeA减弱HAT诱导的组蛋白乙酰化（H3-K9和H4-K8）， 用CB 1受体拮抗剂处理的野生型小鼠中NPY和NPY-Y1受体表达，从而 导致饮酒行为增加。这一目的也将测试是否药理学激活的 CB 1受体降低了所提出的靶分子的表达并增加了酒精 消费 拟议研究的结果可能会导致开发有效的药物疗法 通过靶向与酒精有关的两种重要神经介质（CB 1和NPY）来治疗酒精中毒 饮酒行为

Abstract Alcohol addiction is characterized by a loss of control over drinking, leading to the development of tolerance and physical dependence. Genetic and environmental factors have both been shown to play important roles in the development of alcohol addiction; however, the molecular mechanisms underlying excessive alcohol drinking are not yet fully understood. Alcohol appears to exert its effects through several signal transduction systems in the brain. Recently, the endocannabinoid (eCB) system has stood out among these systems in regards to its functional significance in alcohol addiction. It is well established that CB1 receptor stimulation increases alcohol consumption in rodents, while blockade of CB1 receptor function decreases this behavior. Several studies indicate that deletion of the neuropeptide Y (NPY) and NPY-Y1 receptor genes and lower NPY expression in the central nucleus of amygdala (CeA) promotes alcohol drinking behavior. The gene transcription factor cAMP responsive element-binding (CREB) protein is a common denominator for CB1 and NPY signaling and also plays a critical role in alcohol drinking behavior. Deletion of the CREB gene and a deficiency in CREB function in the shell of the nucleus accumbens (NAc Shell) and CeA have been associated with increased alcohol drinking behavior, while infusion of NPY into the CeA has been shown to increase CREB phosphorylation and decrease alcohol intake. The epigenetic mechanisms, due to histone modifications such as acetylation, appear to also be important in the regulation of gene expression, and may play critical roles in the mechanisms of alcohol and drug addiction. CREB activation recruits CREB binding protein (CBP) to transcriptional machinary, which catalyzes acetylation of histone H3 and histone H4 through its intrinsic histone acetyltransferase (HAT) activity thereby regulating gene expression. It is unknown if CB1 receptors and NPY systems interact with each other via CBP- mediated histone modifications in specific neurocircuitries that regulate alcohol drinking behavior. We hypothesize that CB1 receptor signaling interacts with the NPY system through CREB-CBP-mediated chromatin remodeling in the NAc and amygdala leading to the modulation of alcohol drinking behavior. The following Specific Aims will test this hypothesis: 1. To examine a) if decreased alcohol intake due to genetic deletion of the CB1 receptor is related to compensatory increases in the expression of CREB, pCREB, CBP, and also increases in histone (H3 and H4) acetylation and expression of NPY and the NPY-Y1 receptor and; b) if knock-down of CBP expression by siRNA infusion into the NAc shell and CeA attenuates HAT-induced histone acetylation (H3-K9 and H4- K8), and NPY and NPY-Y1 expression in CB1 -/- mice, thereby increasing alcohol drinking behavior. 2. To examine a) if decreased alcohol intake due to pharmacological blockade of CB1 receptors is related to increases in the expression of CREB, pCREB and CBP, and increases in acetylation of histones (H3 and H4) and expression of NPY and NPY-Y1 receptors and; b) if knock-down of CBP expression by siRNA infusion into the NAc shell or CeA attenuates HAT-induced histone acetylation (H3-K9 and H4-K8) and NPY, and NPY-Y1 receptor expression in wild-type mice treated with CB1 receptor antagonists, thereby resulting in increased alcohol drinking behavior. This aim will also test if pharmacological activation of the CB1 receptor decreases the expression of the proposed target molecules and increases alcohol consumption. The findings of the proposed studies might lead to the development of effective pharmacotherapies for alcoholism by targeting two important neuromediators (CB1 and NPY) implicated in alcohol drinking behavior.