Targeting liver aldehyde dehydrogenase-2 prevents heavy but not moderate alcohol drinking

Abstract

Aldehyde dehydrogenase 2 (ALDH2), a key enzyme for detoxification the ethanol metabolite acetaldehyde, is recognized as a promising therapeutic target to treat alcohol use disorders (AUDs). Disulfiram, a potent ALDH2 inhibitor, is an approved drug for the treatment of AUD but has clinical limitations due to its side effects. This study aims to elucidate the relative contribution of different organs in acetaldehyde clearance through ALDH2 by using global- (Aldh2−/−) and tissue-specificAldh2-deficient mice, and to examine whether liver-specific ALDH2 inhibition can prevent alcohol-seeking behavior.Aldh2−/−mice showed markedly higher acetaldehyde concentrations than wild-type (WT) mice after acute ethanol gavage. Acetaldehyde levels in hepatocyte-specificAldh2knockout (Aldh2Hep−/−) mice were significantly higher than those in WT mice post gavage, but did not reach the levels observed inAldh2−/−mice. Energy expenditure and motility were dramatically dampened inAldh2−/−mice, but moderately decreased inAldh2Hep−/−mice compared to controls. In the 2-bottle paradigm and the drinking-in-the-dark model,Aldh2−/−mice drank negligible volumes from ethanol-containing bottles, whereasAldh2Hep−/−mice showed reduced alcohol preference at high but not low alcohol concentrations. Glial cell- or neuron-specificAldh2deficiency did not affect voluntary alcohol consumption. Finally, specific liverAldh2knockdown via injection ofshAldh2markedly decreased alcohol preference. In conclusion, although the liver is the major organ responsible for acetaldehyde metabolism, a cumulative effect of ALDH2 from other organs likely also contributes to systemic acetaldehyde clearance. Liver-targeted ALDH2 inhibition can decrease heavy drinking without affecting moderate drinking, providing molecular basis for hepaticALDH2targeting/editing for the treatment of AUD.