




"We found that even a single exposure to social stress causes a change in the gut microbiota, similar to what is seen following other, much more severe physical stressors, and this change gets bigger following repeated exposures," said Dr. Kim Huhman, Distinguished University Professor of Neuroscience at Georgia State. "Because 'losers' show much more stress hormone release than do 'winners,' we initially hypothesized that the microbial changes would be more pronounced in animals that lost than in animals that won."

"Interestingly, we found that social stress, regardless of who won, led to similar overall changes in the microbiota, although the particular bacteria that were impacted were somewhat different in winners and losers. It might be that the impact of social stress was somewhat greater for the subordinate animals, but we can't say that strongly."

Another unique finding came from samples that were taken before the animals were ever paired, which were used to determine if any of the preexisting bacteria seemed to correlate with whether an animal turned out to be the winner or loser.

"It's an intriguing finding that there were some bacteria that seemed to predict whether an animal would become a winner or a loser," Huhman said.

"These findings suggest that bi-directional communication is occurring, with stress impacting the microbiota, and on the other hand, with some specific bacteria in turn impacting the response to stress," said Dr. Benoit Chassaing, assistant professor in the Neuroscience Institute at Georgia State.

This is an exciting possibility that builds on evidence that gut microbiota can regulate social behavior and is being investigated by Huhman and Chassaing.