A pioneering study has uncovered the vital role that gut microbiota plays in regulating stress responses by interacting with the body's circadian rhythms. The findings open the door for developing new microbial-based therapies that could help individuals better manage stress related mental health conditions, such as anxiety and depression which are often associated with alterations in circadian and sleep cycles. This breakthrough research from University College Cork and APC Microbiome Ireland - a Research Ireland Centre - offers compelling evidence that the trillions of microorganisms in the gut orchestrate the body's hormonal responses to stress in a time-dependent manner, paving the way for new therapeutic approaches targeting the gut-brain axis.

Published in Cell Metabolism, this study shines a spotlight on the intricate relationship between the gut microbiota and the hypothalamic-pituitary-adrenal (HPA) axis, the body's central stress response system. The research demonstrates that depletion of gut microbiota leads to an hyperactivation of the HPA-axis in a time-of-day specific manner, which alongside with alterations to the brain's stress and circadian responding regions, results in altered stress responsivity across the day. The study further identifies specific gut bacteria, including a Lactobacillus strain ( Limosilactobacillus reuteri) , as key influencers of this circadian-regulated stress mechanism.

L. reuteri emerged as a candidate strain that modulates glucocort.