The administration of Alda-1, an activator of ALDH2, inhibits relapse-like ethanol intake in female alcohol-preferring UChB rats.

Aims: Alcohol relapse is a main limitation for the treatment of alcohol use disorders. Previous studies have shown that Alda-1, a pharmacological activator of ALDH2, inhibits both acquisition and chronic ethanol intake in rats; however, its effects on relapse-like ethanol intake are unknown. The aim of this study was to assess the effect of Alda-1 on post-deprivation and reaccess relapse-like ethanol intake in alcohol-preferring UChB rats. We also aimed to assess the possible mechanisms associated with the effects of Alda-1 by measuring the levels of glutamate transporter (GLT-1), oxidative stress and neuroinflammation markers in different regions of the mesocorticolimbic system.

Main Methods: In Experiment I, UChB female rats were exposed for 100 days to voluntary ethanol intake followed by 2-weeks of ethanol withdrawal and 1 week of ethanol reaccess. Alda-1 (25 mg/kg, intragastric, i.g) or vehicle was administered daily for 14 days during the withdrawal/re-access period. Experiment II was similar to Experiment I, but after the withdrawal period, ethanol re-access was not allowed, and Alda-1 was administered during the last week of withdrawal. At the end of both experiments, the levels of GLT-1, oxidative stress (GSH, MDA), and neuroinflammation markers (GFAP, Iba-1) were assessed in nucleus accumbens and/or hippocampus.

Key Findings: The results showed that Alda-1 administration markedly blocked (90 %, p < 0.001) relapse-like ethanol intake in UChB rats. Alda-1 increased Iba-1 reactivity (microglial marker) in the NAc of ethanol-deprived rats. Alda-1 administration did not influence the levels of GLT-1, oxidative stress markers (MDA, GSH) or GFAP reactivity in the mesocorticolimbic system.

Significance: These preclinical findings support the use of activators of ALDH2, such as Alda-1, as a potential pharmacological strategy in the treatment of alcohol relapse.