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Reproductive Endocrinology

MON-171 - Gavage of Rats with the Human Duodenal Microbe Rothia Mucilaginosa Leads to A PCOS-Like Phenotype While Colonizing the Small Intestine and Is Associated with Minimal Disruption of the Microbial Community

Monday, June 15, 2026
9:00 AM - 2:00 PM CT
Location: ENDOExpo; Poster Floor
Disclosure(s):
Gabriela Leite, PhD: No financial relationships to disclose
Polycystic ovary syndrome (PCOS) is a major endocrine disorder in reproductive-age women. It has diverse clinical manifestations, including hyperandrogenism, ovarian dysfunction, infertility, and others. The gut microbiome may play an important role. We previously showed that Rothia mucilaginosa, a microbe found in the human small bowel, specifically the duodenum, can produce testosterone and induces a PCOS-like phenotype in rats characterized by abnormal estrous cycles and disrupted ovarian androgen pathways. Here, we to confirm the colonization of the small bowel by R. mucilaginosa in this model of PCOS.

Methods
Reproductive-age female Sprague Dawley rats were gavaged with 108 CFU/mL R. mucilaginosa (Rothia) or PBS (Controls) daily for 4 weeks (engraftment phase). The estrous cycle was monitored daily using H&E-stained cells from vaginal lavages. One day after the last gavage, rats were euthanized and the ileum and its contents were harvested. Whole-genome sequencing was performed on the ileal luminal contents on NovaSeq X Plus platform (2x151). Reads were de-hosted and mapped to the QMM-H 1.0 database (Qiagen) available at the CLC Microbial Module (Qiagen). Beta-diversity (Bray-Curtis) and alpha-diversity (Shannon index) were calculated using CLC Microbial Module workflows. Differences in relative abundance (RA) were estimated using a Generalized Linear Model (GLM), assuming that abundances follow a Negative Binomial distribution. The Wald test was used to determine significance between groups.

Results
After the initial 4-week gavage period, 55% of rats from the Rothia group (n=20) showed altered estrous cycles with an arrested diestrus phase, compared with 30% in Controls (n=20). The ileal bacterial fingerprint differed slightly between the Rothia group and controls (Bray-Curtis PERMANOVA, p=0.09). Despite no changes in microbial diversity (Shannon p-value=0.5), the RA of only four phyla from the ileal core dropped in Rothia when compared to Controls [Campylobacterota (Log2 Fold Change (FC)=-0.95, FDR p-value=0.03), Fusobacteriota (FC=-0.84, FDR p-value=0.03), Thermodesulfobiota (FC=-1.17, FDR p-value=0.03), and Verrucomicrobiota (FC=-1.61, FDR p-value=0.03)]. As expected, there was a highly significant increase in the RA of R. mucilaginosa in Rothia compared to controls (FC=7.42, FDR p-value=1.42E-12), along with Streptomyces antimycoticus (FC=5.93, FDR p-value=2.04E-11).

Conclusion
Female rats gavaged with Rothia mucilaginosa develop alterations in estrous cycles. In this study we demonstrate that after 1 month of gavage, there is a high level of R. mucilaginosa colonization in the small intestine of these animals. This occurs without excessive disruption of the duodenal microbial community.

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