A major hypothesis in the addiction field suggests deficits in dopamine signaling during abstinence as a driving mechanism for the relapsing course of the disorder. Paradoxically, blockade of mu-opioid receptors (MORs) intended to suppress dopamine release and alcohol reward is a widely used treatment for preventing relapse in alcohol use disorder (AUD). To elucidate this apparent discrepancy, we systematically survey the literature on experimental studies in AUD subjects and animal models, which assessed striatal dopamine levels and D1, D2-like receptor, dopamine transporter and MOR via positron emission tomography (PET) and ex vivo receptor binding assays. The reported evidence indicates a changing dopaminergic signaling over time, which is associated with concomitant alterations in MOR, thus suggesting a highly dynamic regulation of the reward system during abstinence. Such a view can reconcile the various evidences from in vivo and postmortem studies, but makes developing an effective pharmacological intervention that specifically targets either dopamine receptors or the transporter system a daunting task.

中文翻译：

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酒精中毒中的多巴胺和阿片类药物系统适应性的重新研究：来自正电子发射断层扫描和验尸研究的综合证据。

成瘾领域的一个主要假设表明，禁欲期间多巴胺信号传导的缺陷是该疾病复发过程的驱动机制。矛盾的是，旨在抑制多巴胺释放和酒精奖励的μ阿片受体（MOR）的阻断是防止酒精使用障碍（AUD）复发的一种广泛使用的治疗方法。为了阐明这种明显的差异，我们系统地调查了有关AUD受试者和动物模型的实验研究文献，这些文献通过正电子发射断层扫描（PET）和离体受体结合评估了纹状体多巴胺水平以及D1，D2样受体，多巴胺转运蛋白和MOR分析。报告的证据表明，多巴胺能信号随时间变化，这与MOR的伴随变化有关，因此暗示了禁欲期间对奖励系统的高度动态调节。这样的观点可以调和来自体内和死后研究的各种证据，但是使开发针对多巴胺受体或转运蛋白系统的有效药理学干预成为一项艰巨的任务。