First, they noted that there is a lot of overlap between the body’s circadian system and its stress response. Circadian rhythms refer to the regulation of basic bodily functions that occur throughout the 24 hours of the day, such as the sleep-wake cycle.
As the researchers note in their paper, the stress response is “characterized as a rapid adaptive process to real or perceived danger,” and as previous research has shown, circadian This can have a big impact on rhythm.
The authors of the recent study further explained that one important pathway that helps inform circadian rhythms and stress responses is the hypothalamic-pituitary-adrenal (HPA) axis. This pathway is also at the core of how bacteria in the gut influence both behavior and brain function.
The researchers used germ-free and conventional mice to help study the complex relationship between the gut microbiome and stress responses. They collected data from elements such as blood samples, brain imaging, behavioral tests, and tissue analyses.
Using control mice, they were able to find that the gut microbiome changes throughout the day. The researchers used antibiotics to deplete the gut microbiota in some mice and examined germ-free mice.
While studying these mice, we discovered that this microbiota depletion affected the daily rhythm of corticosterone levels in the mice’s plasma. The human equivalent of corticosterone is the glucocorticoid cortisol. Glucocorticoids are central to stress responses and circadian rhythms.
Further analysis of the mice suggested that gut bacteria influence central circadian rhythms. The results further showed that changes in gut bacteria can alter the rhythms of stress pathways in parts of the brain that regulate the “stress response,” and that microbial depletion alters the 24-hour rhythm of the HPA axis.
Next, the researchers were interested in observing how the mice responded to stress based on time of day and microbiome depletion.
After exposure to stress, mice with depleted gut microbiota did not have increased corticosterone at specific times of day like control mice.
Similarly, microbe-depleted mice showed no changes in social interactions after being exposed to stress at specific times of day. In contrast, interactions with other mice were reduced in the control group. The groups behaved similarly when measured at different times of day.
They also found that microbe-depleted mice showed changes in their gut bacteria throughout the day. This time-specific change was suggested to be related to a time-specific increase in corticosterone in plasma, a blood component.
The researchers also found, based on fecal microbial transplant data, that the bacterial species Limosylactobacillus reuteri may be key to changes in corticosterone levels.
Overall, the results showed that the gut microbiota likely plays an important role in the stress response “with a circadian rhythm.”
Mark J. Tetell, Ph.D., a professor of neuroscience at Wellesley College in Massachusetts, who was not involved in the study, commented to Medical News Today with his thoughts on the findings.
“Recent papers (…) provide compelling and exciting evidence that the gut microbiota can modulate both stress and circadian systems through the gut-brain axis. Recognizing how they interact and are influenced by the gut microbiome is important to better understand the role of these systems in various mental health disorders, including anxiety and depression. ”
Because this study was conducted in mice, some questions remain as to whether and how these findings apply to humans.
Research in people could add to the data in this area and support the findings. The authors said in their paper that it would be useful to study these concepts in people from different regions and who follow different dietary and lifestyle patterns.
There are also aspects of the research that raise further questions. For example, researchers may also be interested in discovering how gut flora signals reach the brain.
He also emphasized that, “while the findings and conclusions are interesting, questions remain about how translatable they are to humans.”
“To my knowledge, long-term broad-spectrum antibiotic treatment or even intake of the probiotic L. reuteri in humans does not significantly impact stress reactivity,” Mayer explained.
“Furthermore, the stress response to everyday stressors is primarily mediated by the sympathetic nervous system and not by the HPA axis, but this aspect was not addressed in this study. Much of the interesting data “Because these results come from studies in mice, care must be taken when applying the results to human health and disease,” he added.
Although more research is needed, people can take steps to look after their gut health as an important component of their overall well-being. This may include measures such as eating fermented foods and cutting back on sugar.
People should seek the help of their GP or other professional to determine what steps to improve their gut health will be most beneficial to them.
David Merrill, MD, a board-certified geriatric psychiatrist and Singleton Endowed Chair in Integrative Brain Health at Providence St. John’s Health Center in Santa Monica, California, who was not involved in the recent study, said: , advised as follows:
“You can support a healthy gut microbiome by making dietary changes rich in fiber and consuming prebiotic foods like bananas, onions, and oats that feed beneficial bacteria. Supplements In this case, probiotics containing Lactobacillus and Bifidobacterium strains can be expected to have a positive impact on mood and stress responses by increasing microbial diversity.
However, you need to be careful. “Until data from well-designed human studies are available to confirm the above hypothesis, specific diets and supplements aimed at normalizing excessive stress reactivity will not be effective,” Mayer said. I believe that this recommendation should not be made.
“However, there is already a wealth of clinical data supporting the many health benefits of a primarily plant-based diet, and this information is being incorporated into the emerging field of nutritional psychiatry,” he noted.
