FNDC5 and polycystic ovary syndrome: Through the detection and analysis of mouse fecal microbiome and metabolite, we found that there were significant and extensive differences in fecal microbial abundance and metabolite levels between PCOS mice and healthy control mice, and there were also significant differences in fecal flora and metabolite between PCOS and PCOS mice treated with r-irisin, indicating that irisin may affect the phenotype of PCOS by intestinal microbes and metabolites.