Division of Biological Research on Drug Dependence, Department of Pharmaceutical Biosciences, Uppsala University, Box 591, BMC Husargatan 3, SE-75124, Uppsala, Sweden.
Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, 68159, Mannheim, Germany.
Mol Neurobiol. 2018 Aug;55(8):7049-7061. doi: 10.1007/s12035-017-0844-4. Epub 2018 Jan 30.
Molecular changes induced by excessive alcohol consumption may underlie formation of dysphoric state during acute and protracted alcohol withdrawal which leads to craving and relapse. A main molecular addiction hypothesis is that the upregulation of the dynorphin (DYN)/κ-opioid receptor (KOR) system in the nucleus accumbens (NAc) of alcohol-dependent individuals causes the imbalance in activity of D1- and D2 dopamine receptor (DR) expressing neural circuits that results in dysphoria. We here analyzed post-mortem NAc samples of human alcoholics to assess changes in prodynorphin (PDYN) and KOR (OPRK1) gene expression and co-expression (transcriptionally coordinated) patterns. To address alterations in D1- and D2-receptor circuits, we studied the regulatory interactions between these pathways and the DYN/KOR system. No significant differences in PDYN and OPRK1 gene expression levels between alcoholics and controls were evident. However, PDYN and OPRK1 showed transcriptionally coordinated pattern that was significantly different between alcoholics and controls. A downregulation of DRD1 but not DRD2 expression was seen in alcoholics. Expression of DRD1 and DRD2 strongly correlated with that of PDYN and OPRK1 suggesting high levels of transcriptional coordination between these gene clusters. The differences in expression and co-expression patterns were not due to the decline in neuronal proportion in alcoholic brain and thereby represent transcriptional phenomena. Dysregulation of DYN/KOR system and dopamine signaling through both alterations in co-expression patterns of opioid genes and decreased DRD1 gene expression may contribute to imbalance in the activity of D1- and D2-containing pathways which may lead to the negative affective state in human alcoholics.
过量饮酒引起的分子变化可能是导致急性和慢性酒精戒断时出现不愉快状态的基础,从而导致渴望和复发。一个主要的分子成瘾假设是,酒精依赖个体伏核(NAc)中内啡肽(DYN)/κ-阿片受体(KOR)系统的上调导致表达 D1 和 D2 多巴胺受体(DR)的神经回路活动失衡,从而导致不愉快。我们在这里分析了人类酒精中毒者的死后 NAc 样本,以评估前啡肽(PDYN)和 KOR(OPRK1)基因表达和共表达(转录协调)模式的变化。为了研究 D1 和 D2 受体回路的变化,我们研究了这些途径与 DYN/KOR 系统之间的调节相互作用。酒精中毒者和对照组之间 PDYN 和 OPRK1 基因表达水平没有明显差异。然而,PDYN 和 OPRK1 表现出转录协调模式,在酒精中毒者和对照组之间有显著差异。在酒精中毒者中观察到 DRD1 而不是 DRD2 表达下调。DRD1 和 DRD2 的表达与 PDYN 和 OPRK1 的表达强烈相关,表明这些基因簇之间存在高水平的转录协调。表达和共表达模式的差异不是由于酒精性大脑中神经元比例下降所致,因此代表转录现象。DYN/KOR 系统和多巴胺信号的失调,既通过阿片基因共表达模式的改变,也通过 DRD1 基因表达的降低,可能导致包含 D1 和 D2 的途径的活性失衡,从而导致人类酒精中毒者出现负性情感状态。
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