Lipid accumulation in the liver due to chronic alcohol consumption (CAC) is crucial in the development of alcohol liver disease (ALD). It is promoted by the NADH/NAD ratio increase via alcohol dehydrogenase (ADH)-dependent alcohol metabolism and lipogenesis increase via peroxisome proliferator-activated receptor γ (PPARγ) in the liver. The transcriptional activity of PPARγ on lipogenic genes is inhibited by S-nitrosylation but activated by denitrosylation via S-nitrosoglutathione reductase (GSNOR), an enzyme identical to ADH3. Besides ADH1, ADH3 also participates in alcohol metabolism. Therefore, we investigated the specific contribution of ADH3 to ALD onset. ADH3-knockout (Adh3-/-) and wild-type (WT) mice were administered a 10% ethanol solution for 12 months. Adh3-/- exhibited no significant pathological changes in the liver, whereas WT exhibited marked hepatic lipid accumulation (p < 0.005) with increased serum transaminase levels. Adh3-/- exhibited no death during CAC, whereas WT exhibited a 40% death. Liver ADH3 mRNA levels were elevated by CAC in WT (p < 0.01). The alcohol elimination rate measured after injecting 4 g/kg ethanol was not significantly different between two strains, although the rate was increased in both strains by CAC. Thus, ADH3 plays a key role in the ALD onset, likely by acting as GSNOR.

Class III alcohol dehydrogenase (ADH3), primarily localized in the liver and kidney, contributes to alcohol metabolism during chronic alcohol consumption (CAC). However, its role in kidney function remains unclear. This study investigated renal morphological changes associated with ADH3-mediated alcohol metabolism. Nine-week-old male wild-type (WT) and ADH3-deficient (Adh3^-/-) mice were administered 10% ethanol for 1 month. Histological analyses were performed using periodic acid–Schiff (PAS) staining and electron microscopy. Serum biochemical parameters were also assessed. In WT mice, CAC induced an increase in cuboidal parietal epithelial cells (PECs) in Bowman’s capsule, along with elevated testosterone levels in both serum and urine. Adh3^-/- mice showed increased PECs even in the control group, with similarly elevated serum testosterone in both control and ethanol-treated groups. These findings suggest that ADH3 is involved in testosterone metabolism, and that that metabolism is suppressed by CAC because ADH3 shifts toward ethanol metabolism. The resulting testosterone elevation may contribute to PEC proliferation. An increase in PECs observed even in Adh3^-/- control mice may also be caused by the lack of testosterone metabolism via ADH3. Thus, renal ADH3 may protect kidney structure through testosterone metabolism, but its role may be disturbed by CAC. This study highlights the role of ADH3 in the relationship between physiological steroid metabolism and alcoholic pathological abnormality in the kidney.