Alcohol dependence and brain endocannabinoid function

描述（由申请人提供）：酒精使用障碍的发生是由享乐和抗焦虑作用驱动的社会使用转变为戒断症状增加和戒断期间饮酒欲望的演变驱动的依赖。在酒精依赖的后一阶段，戒酒往往伴随着负面的情绪症状，如焦虑和抑郁的增加，这些负面情绪状态的缓解被假设为继续饮酒的主要驱动力。这种从正强化机制到负强化机制的转变可能是由于过量饮酒引起的CNS功能的持久变化。虽然有几个信号系统已经牵连在这个过程中，仍然是一个不完整的了解酒精依赖的神经机制。我们已经收集到的证据表明，EtOH消耗增加了啮齿动物大脑中内源性大麻素（eCB）2-花生四烯酸甘油（2-AG）的水平，而长期间歇性EtOH暴露下调了与情绪处理相关的大脑区域中的eCB信号。依赖性相关的焦虑样行为和过量的乙醇消耗减少了eCB张力的普遍增强，虽然类似的操作不会产生这些影响，在非依赖性动物。基于这些发现，我们假设eCB清除抑制剂对治疗酒精依赖和酒精中毒具有治疗价值。这一假设将通过三个具体目标进行检验。目的1将表征高选择性eCB清除抑制剂在长期戒断期间缓解EtOH依赖性小鼠中焦虑样行为的能力。重要的是，这些实验将通过选择性抑制从大脑中清除这些脂质的不同水解机制来表征两种主要eCB分子2-AG和花生四烯酸（AEA）的相对影响。目标2中的实验将采用生物化学和神经化学方法来表征导致依赖相关脑eCB信号转导失调的机制。本目标中的其他工作将评估eCB失调对其他神经递质系统的影响，这些神经递质系统涉及戒断相关的焦虑样行为和过量EtOH消耗（包括谷氨酸盐、5-羟色胺和去甲肾上腺素）。目标3中的实验将表征选择性eCB清除抑制剂降低与依赖性和长期戒断相关的高水平EtOH消耗的有效性。这些实验还将表征eCB信号传导对非依赖性小鼠中暴食样乙醇摄入的影响。完成拟议的工作可能会突出一个以前未被认识到的机制，酒精依赖的病因，并可能确定新的治疗酒精中毒的目标。

DESCRIPTION (provided by applicant): The development of alcohol use disorders follows a transition from social use motivated by hedonic and anxiolytic effects to dependence motivated by increasing withdrawal symptoms and an evolving desire to drink during abstinence. In this latter stage of alcohol dependence, abstinence from drinking is often accompanied by negative emotional symptoms, such as increased anxiety and depression, and the alleviation of these negative emotional states is hypothesized to be a major driving force for continued alcohol consumption. This shift from positive to negative reinforcement mechanisms likely results from enduring changes in CNS function induced by excessive alcohol consumption. Although several signaling systems have been implicated in this process there is still an incomplete understanding of the neural mechanisms underlying alcohol dependence. We have gathered evidence that EtOH consumption increases levels of the endogenous cannabinoid (eCB) 2- arachidonoyl glycerol (2-AG) in rodent brain, while long-term intermittent EtOH exposure down-regulates eCB signaling in brain regions relevant to emotional processing. Dependence-associated anxiety-like behavior and excessive EtOH consumption are reduced by generalized enhancement of eCB tone, though similar manipulations do not produce these effects in non-dependent animals. Based on these findings, we hypothesize that eCB clearance inhibitors have therapeutic value for treating alcohol dependence and alcoholism. This hypothesis will be tested through three Specific Aims. Aim 1 will characterize the ability of highly selective eCB clearance inhibitors to alleviate anxiety-like behavior in EtOH dependent mice throughout a period of protracted withdrawal. Importantly, these experiments will characterize the relative influence of two primary eCB molecules, 2-AG and anandamide (AEA), by selectively inhibiting the distinct hydrolytic mechanisms that clear these lipids from the brain. The experiments in Aim 2 will employ biochemical and neurochemical approaches to characterize the mechanisms contributing to dependence-associated dysregulation of brain eCB signaling. Additional work in this Aim will evaluate the influence of eCB dysregulation on other neurotransmitter systems involved in withdrawal-associated anxiety-like behavior and excessive EtOH consumption (including glutamate, serotonin and norepinephrine). The experiments in Aim 3 will characterize the efficacy of selective eCB clearance inhibitors for reducing high levels of EtOH consumption associated with dependence and protracted withdrawal. These experiments will also characterize the influence of eCB signaling on binge-like ethanol intake in non-dependent mice. Completion of the proposed work is likely to highlight a previously unrecognized mechanism in the etiology of alcohol dependence and may identify novel therapeutic targets for alcoholism.