Aldehyde dehydrogenase 2 and sex influence blood acetaldehyde levels in mice, but not ethanol levels

This study measured the concentrations of blood ethanol (EtOH) and acetaldehyde (AcH) in mice to examine the roles of aldehyde dehydrogenase 2 (ALDH2) and sex following intragastric administration of EtOH. The experiment utilized males and females of two mouse strains: C57BL/6N (wild-type, WT) and Aldh2-knockout (Aldh2-KO) mice. Aldh2-KO mice lack the ALDH2 enzyme, leading to the accumulation of high levels of AcH in the blood. The mice were fasted for approximately six hours before EtOH administration. EtOH (1.0, 2.0, and 3.0 g/kg) was administered intragastrically, and blood samples were collected at 30, 60, 120, 180, 240, and 300 minutes post-EtOH administration through retro-orbital puncture. The samples were then analyzed using headspace gas chromatography. The results for both male and female WT mice showed that EtOH and AcH levels increased in a dose-dependent manner, peaked at 60 min post-ingestion, and then gradually decreased. While there were no significant differences in blood EtOH concentrations between males and females, the concentrations of AcH were significantly higher in female mice than in male mice, indicating potential sex-related differences in EtOH metabolism. In Aldh2-KO mice, the EtOH and AcH levels increased initially and peaked at 30-60 minutes post-ingestion, with no significant differences in EtOH or AcH concentrations between the sexes. While the concentrations of EtOH in both male and female Aldh2-KO mice gradually decreased, the concentration of AcH remained elevated until six hours post-ingestion due to the ALDH2 deficiency inhibiting AcH oxidation. Our findings emphasize the importance of considering the influences of sex and ALDH2 when researching the effects of alcohol, particularly in relation to the EtOH byproduct AcH.