A recent study has found that fecal transplants from older female mice can improve ovarian function and fertility in young mice. The research, published in Nature Aging, highlights a direct connection between the gut microbiome and ovarian health.
"These findings suggest that there is two-way communication between the ovary and the microbiome and that this communication changes throughout life with age," said Bérénice Benayoun, Associate Professor at USC Leonard Davis School of Gerontology and senior author of the study.
The research involved treating young adult female mice with antibiotics to remove their existing gut bacteria. These mice then received fecal transplants from either young or older estropausal (post-reproductive) donor mice. According to Benayoun, who also holds appointments in cancer biology and pharmacology at USC, this process allowed for a complete remodeling of the recipient's microbiome.
"Our original hypothesis was that we would see damaging effects of the older microbiome on ovarian function, but surprisingly, we found the opposite," said Min Hoo Kim, a postdoctoral researcher in Benayoun’s lab and first author of the study.
The results showed that after receiving older microbiome transplants, the gene expression profiles in recipient ovarian cells resembled those of much younger animals. There were also fewer signs of inflammation—a common indicator of tissue aging—in these ovaries.
Fertility outcomes reflected these biological changes. Mice that received transplants from older donors had higher reproductive success compared to those given younger microbiomes. "Some of the mice that received the younger microbiome never produced pups, while all of the mice that received the older microbiome did," Benayoun said.
One possible explanation centers on a group of gut microbes known as the estrobolome, which plays a role in estrogen metabolism. As ovaries age and become less responsive to hormonal signals from these microbes, certain bacteria may increase their signaling activity to compensate. When transplanted into younger animals with more responsive ovaries, this heightened signaling could boost reproductive function.
The authors identified several bacterial species and metabolic pathways that may facilitate communication between gut bacteria and ovaries. Although these findings are currently limited to mouse models, they suggest that adjusting the gut microbiome could affect reproductive aging.
Ovarian aging is linked not only to fertility decline but also to increased risks for osteoporosis, cardiovascular disease, diabetes, dementia, and shorter lifespan among women. Benayoun emphasized its importance: "It has dramatic negative effects on women's overall health and is associated with huge increases in risks of diseases ranging from osteoporosis and diabetes to heart disease and dementia. If we could effectively delay menopause, it would help women live longer, healthier lives."
