Predicted functional alterations in colonic microbiota metabolism underlie ethanol consumption and preference behavior in mice

Abstract Background Alcohol use disorder (AUD) is a complex condition affecting several body systems. Gut microbiota alterations, intestinal‐barrier disruption, and the consequent translocation of metabolites foster chronic inflammation, lower short‐chain fatty acid (SCFA) output, and depleted beneficial bacteria may contribute to transcriptional, epigenetic, and metabolic changes that influence ethanol preference. Methods Two experimental phases were used. T1 (8 weeks): mice received either the American Institute of Nutrition standard diet (AING) or a high‐sugar‐butter (HSB) diet. T2 (4 weeks): HSB animals switched to AING (SWITCH), while AING mice maintained the same diet. Each diet arm was split into ethanol (EtOH; free access to 10% ethanol) or H 2 O, generating four groups (AING + H 2 O, AING + EtOH, SWITCH + H 2 O, and SWITCH + EtOH). Sample processing involved colonic‐content collection, 16S rRNA sequencing, microbiome profiling, functional inference, metabolic‐network analysis, and SCFA/amino acid quantification. Results SWITCH + EtOH mice displayed high ethanol consumption and preference, whereas AING + EtOH mice showed ethanol aversion. Their colonic microbiota differed markedly; amino acid metabolism fell, secondary bile acid synthesis rose, and SCFA production dropped in SWITCH + EtOH animals. Direct measurements confirmed significant reductions in butyrate, acetate, propionate, and selected amino acids. Network analysis revealed enrichment of bacterial metabolism, oxidative stress, and dopamine pathway genes. Conclusions Diet‐induced dysbiosis, reflected in shifts in microbiota‐derived metabolites, was associated with excessive alcohol intake; the metabolites identified can represent potential therapeutic targets for AUD.