Fecal transplants from old female mice appear to boost fertility and ovarian health in younger ones. The findings, detailed in a study published Tuesday in the journal Nature Aging, indicate a direct link between gut health and reproductive health in the animals. They could also hold implications for future research into how the microbiome influences ovarian function and fertility in humans.
The results came as a surprise, says Bérénice Benayoun, a biologist at the University of South California Leonard Davis School of Gerentology and the leader of the research. “We went into the study expecting the old fecal microbiome would prematurely age the young ovaries,” she says. “So we were very intrigued to see the opposite being true, suggesting that some very interesting biology was happening.”
Scientists already know that the microbiome—a collection of bacteria, organisms and viruses that live both on and inside the body—plays a role in myriad aspects of health, including reproduction and fertility.
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
Fecal transplants promise to replace “bad” bacteria in a diseased gut with “healthy” bacteria via a donor’s feces. In humans, the benefits of the procedure are still under investigation, but it is used in some cases to treat certain conditions, such as bacterial infections. It may also be useful for treating gastrointestinal and other metabolic issues, and even neurobiological conditions—but the science is preliminary.
The older female mice in the study were all in a stage of life called the “estropause,” which is similar to menopause in humans, and had all stopped ovulating. When the younger mice received fecal transplants from these older animals, genetic markers in their ovarian cells appeared rejuvenated and they were more successful at reproducing.
The effect may be a result of compensation, Benayoun says. In mice there is a communication pathway between a group of gut microbes called the estrobolome and the ovaries. But as mice age, this highway appears to break down, she explains. The younger mice that receive the older fecal transplants may boost the signals between this subset of gut microbes and the ovaries to compensate for the degrading pathway, bolstering their reproductive health.
The study suggests that ovarian function is “plastic,” Benayoun says. Importantly, the findings in mice cannot be applied directly to humans. Researchers would need to investigate whether the human gut microbiome has specific organisms that communicate with the ovaries, as the mice do, she says. Still, the discovery suggests the microbiome may be an entry point to tweak ovarian function, she adds.
“You could imagine that once such bacteria are identified,” she says, “it would be easy enough to design ovarian-supporting probiotics.”