A study has uncovered a critical brain-gut connection that links psychological states to changes in the gut microbiome, with profound implications for immune function and stress-related health conditions

>The research reveals how stress-sensitive brain circuits influence the composition of gut bacteria through Brunner’s glands in the small intestine. It sheds light on the intricate mechanisms by which mental states can impact physical health, pointing to new possibilities for therapeutic intervention, for example against inflammatory bowel disease.

>A new study, conducted by researchers at the Icahn School of Medicine at Mount Sinai (New York) and the Max Planck Institute for Biological Cybernetics (Tübingen, Germany), has now identified a circuit that connects the brain with certain gut glands. These organs, called Brunner’s glands, are located in the upper part of the small intestine and secrete the protein mucin, a main component of the mucus that lines the intestinal wall and serves as a substrate for the growth of beneficial gut bacteria. As the team found out, removing Brunner’s glands from mice resulted in lower counts of Lactobacilli, a genus of bacteria abundant in the small intestine of many animals, including humans. The consequence: with fewer Lactobacilli, the mice were more likely to die from gut infections and showed various signs of systemic inflammation.

>he team established that it connects Brunner’s glands to the amygdala, a brain area responsible for emotional responses. Specifically, fear or anxiety causes the amygdala to decrease its activity and send fewer signals to the vagus nerve. When this happens, Brunner’s glands release less mucus, thereby affecting immunity. In fact, exposing the mice to chronic stress had the same effect on their microbiome composition and health as surgically removing the glands. “Brunner’s glands are more important than previously thought,” commented

Paper: [Stress-sensitive neural circuits change the gut microbiome via duodenal glands: Cell](https://www.cell.com/cell/fulltext/S0092-8674(24)00779-7?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0092867424007797%3Fshowall%3Dtrue)