The Amygdala Noradrenergic System Is Compromised With Alcohol Use Disorder

BACKGROUND: Alcohol use disorder (AUD) is a leading preventable cause of death. The central amygdala (CeA) is a hub for stress and AUD, while dysfunction of the noradrenaline (NA) stress system is implicated in AUD relapse. METHODS: Here we investigated whether alcohol (ethanol) dependence and protracted withdrawal alter noradrenergic regulation of the amygdala in rodents and humans. Male adult rats were housed under control conditions, subjected to chronic intermittent ethanol vapor exposure (CIE) to induce dependence, or withdrawn from CIE for two weeks, and ex vivo electrophysiology, biochemistry (catecholamine quantification by HPLC), in situ hybridization and behavioral brain-site specific pharmacology studies were performed. We also used qRT-PCR to assess gene expression of the α1(B), β1, and β2 adrenergic receptor in human post-mortem brain tissue from men diagnosed with AUD and matched controls. RESULTS: We found that α1 receptors potentiate CeA GABAergic transmission and drive moderate alcohol intake in control rats. In dependent rats, β receptors disinhibit a subpopulation of CeA neurons, contributing to their excessive drinking. Withdrawal produces CeA functional recovery with no change in local noradrenaline tissue concentrations, though there are some long-lasting differences in the cellular patterns of adrenergic receptor mRNA expression. Additionally, post-mortem brain analyses reveal increased α1B receptor mRNA in the amygdala of humans with AUD. CONCLUSIONS: Thus, CeA adrenergic receptors are key neural substrates of AUD. Identification of these novel mechanisms that drive alcohol drinking, particularly during the alcohol-dependent state, support ongoing new medication development for AUD.