Role of the CB1 receptor signaling in alcohol consumption

摘要 酒精成瘾的特征是对饮酒失去控制，导致 容忍和身体依赖。遗传和环境因素都被证明是起作用的 在酒精成瘾的发展中起重要作用；然而，潜在的分子机制 过度饮酒还没有完全被理解。酒精似乎通过以下几个途径发挥作用 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，关于它在酒精成瘾中的功能意义。众所周知， 刺激CB1受体增加啮齿类动物的酒精摄入量，而阻断CB1受体 函数可以减少这种行为。多项研究表明神经肽Y(NPY)的缺失和 杏仁中央核NPY-Y1受体基因和NPY低表达促进 饮酒行为。 转录因子cAMP反应元件结合蛋白(CREB)是一种常见的 CB1和NPY信号的分母，在饮酒行为中也起着关键作用。删除 伏隔核壳中CREB基因的缺失和CREB功能的缺陷 和CEA与更多的饮酒行为有关，而NPY注入大脑 CEA已被证明可以增加CREB的磷酸化，减少酒精摄入量。表观遗传学 组蛋白修饰的机制，如乙酰化，似乎在调节中也很重要。 并可能在酒精和药物成瘾的机制中发挥关键作用。CREB 激活将CREB结合蛋白(CBP)招募到转录机器，后者催化 组蛋白H3和组蛋白H4通过其固有的组蛋白乙酰转移酶(HAT)活性从而调节 基因表达。CB1受体和NPY系统是否通过CBP相互作用尚不清楚。 在调节饮酒行为的特定神经回路中介导组蛋白修饰。 我们假设CB1受体信号通过CREB-CBP介导与NPY系统相互作用 NAc和杏仁核染色质重塑导致饮酒行为的调节。这个 以下具体目标将检验这一假设： 1.检查a)CB1受体基因缺失导致的酒精摄入量减少是否与 CREB、pCREB、CBP的代偿性表达增加，组蛋白的表达也增加(H3和 H4)NPY和NPY-Y1受体的乙酰化和表达；以及；b)CBP表达是否下调 通过将siRNA注入NAC外壳和CEA来减弱HAT诱导的组蛋白乙酰化(H3-K9和H4- K8)，并在CB1-/-小鼠体内表达NPY和NPY-Y1，从而增加饮酒行为。 2.检查a)药物阻断CB1受体导致的酒精摄入量减少是否与 增加CREB、pCREB和CBP的表达，增加组蛋白的乙酰化(H3和 H4)和NPY和NPY-Y1受体的表达，以及；b)是否通过siRNA下调CBP的表达 向NAC壳或CEA注入可减弱HAT诱导的组蛋白乙酰化(H3-K9和H4-K8)和 CB1受体拮抗剂对野生型小鼠NPY、NPY-Y1受体表达的影响 导致饮酒行为增多。这一目标还将测试是否在药物上激活了 CB1受体减少所建议的靶分子的表达并增加酒精含量 消费。 拟议的研究结果可能会导致有效药物疗法的发展。 通过靶向两个与酒精有关的重要神经介质(CB1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.