Effects of repeated ovarian hyperstimulation on gut microbiota composition in a mouse model

This study investigated whether repeated cycles of controlled ovarian hyperstimulation (COH) influ-ence the gut microbiota composition in female mice.

Eight-week-old female Swiss mice (n=20; 10 per group) underwent ten weekly COH treatments with ex-ogenous gonadotropins or received saline injections as con-trols. One week after the final treatment, fecal samples were collected for gut microbiota profiling using 16S rRNA gene sequencing (V4 region amplification; primers 515F/806R) on the Illumina MiSeq platform. Sequencing data were pro-cessed in QIIME2 with DADA2 for denoising and Green-genes-based taxonomic assignment. Alpha-diversity (Shan-non, Simpson, observed OTUs, Faith's PD) and beta-diversity (Bray-Curtis, Jaccard, unweighted/weighted UniFrac) metrics were calculated. Differential taxonomic abundance and bio-marker analyses were performed using Random Forest and LEfSe. Statistical significance was set at p<0.05.

No significant differences were observed between COH and control groups for alpha-diversity in-dices (all p>0.05) or beta-diversity distances (PERMANO-VA p>0.05). Relative abundances across major taxonomic levels were similar, although the Firmicutes:Bacteroidetes ratio was lower in COH-treated mice. Biomarker analyses identified Bacteroidales, Erysipelotrichaceae, and Parabac-teroides as enriched in the COH group, while Rikenellaceae and Odoribacter were more abundant in controls.

Repeated COH did not significantly alter overall gut microbial diversity in mice under the conditions tested. However, specific taxonomic shifts and biomark-er signatures were detected, indicating associations-not causality-between COH exposure and changes in microbi-ota composition. Further studies are needed to determine the functional and physiological implications of these as-sociations.