Chronic alcohol-induced dysbiosis of the gut microbiota and gut metabolites impairs sperm quality

Purpose: To explore whether chronic alcohol consumption affects sperm quality by inducing changes in the gut microbiota. In this study, we established a mouse model of chronic alcohol consumption by allowing male C57 mice to freely ingest 10% ethanol for 8 weeks. We then collected the faecal microbiota of the male mice in the chronic drinking group (alcohol) and the control group (control) and transplanted them into the transplant groups (the alcohol-faecal microbiota transplantation [FMT] group and the control-FMT group). Next, we collected faecal, testes, and blood samples from each group. The Suiplus semen analysis (SSA) system was used to analyse sperm quality; 16S ribosomal RNA sequencing and non-targeted metabolomics were performed to evaluate the gut microbiota and its metabolites; a cytokine antibody array was used to evaluate the levels of inflammatory cytokines in mouse blood and testicular cells; RNA sequencing was performed to analyse the gene expression in mouse testes; and testicular blood flow was evaluated by ultra-high resolution imaging system.