A groundbreaking study has unveiled a crucial connection between the brain and gut health, shedding light on how psychological stress impacts gut bacteria and immunity. Conducted by researchers from the Icahn School of Medicine at Mount Sinai in New York and the Max Planck Institute for Biological Cybernetics in Tübingen, Germany, the study identifies a previously unknown circuit linking the brain to gut glands known as Brunner’s glands.
Brunner’s glands, located in the upper small intestine, play a significant role in gut health by secreting mucin, a key component of mucus that supports beneficial gut bacteria. The researchers found that removal of these glands in mice led to a reduction in Lactobacilli, a genus of beneficial bacteria. This decrease in Lactobacilli resulted in higher susceptibility to gut infections and signs of systemic inflammation.
The study also revealed that the vagus nerve, part of the parasympathetic nervous system responsible for regulating rest and relaxation, communicates between the brain and Brunner’s glands. The amygdala, a brain region involved in emotional responses, directly affects these glands. When the amygdala’s activity decreases due to stress, it signals the vagus nerve to reduce mucus production, impacting gut immunity. This effect mirrors the consequences of physically removing Brunner’s glands.
Lead author Hao Chang from the Icahn School of Medicine noted, “Brunner’s glands are more crucial than previously realized. They form a unique system controlled by the vagus nerve, establishing a direct link between the brain and gut microbiome.”
The study’s findings provide insights into why psychosocial stress may increase infection risk and open potential avenues for treatment. Stimulating the amygdala or vagus nerve in stressed mice was found to restore normal mucus secretion and reverse stress-induced changes in the gut microbiome and immunity. Probiotic treatment also mitigated stress-related negative effects.
These results advance our understanding of the interplay between mental health and gut health, particularly regarding conditions like anxiety, depression, and gastrointestinal disorders. Senior author Ivan de Araujo of the Max Planck Institute for Biological Cybernetics emphasized the significance of these findings: “We believe that Brunner’s glands may play a crucial role in inflammatory bowel disease. Further research could offer new insights into disease mechanisms and potential therapies.”
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