Study shows stressed mouse brain sends messages to gut that reduce levels of beneficial bacteria

A team of medical researchers from the United States, China and Germany report that when a mouse feels stressed, its brain sends signals to an intestinal gland that leads to the elimination of a type of bacteria that prevents inflammation and an unnecessary immune response.

In their project, published in the journal CellThe group studied communications between the mouse brain and the Brunner glands in the mouse intestine.

In recent decades, medical researchers have discovered that different parts of the body communicate with each other much more than previously thought. One such network has been discovered between the brain and the gut.

For example, researchers have discovered that when an organism experiences stress, the brain sends signals to the organs to release hormones to deal with the stressful event. However, this can also trigger an attack of chronic inflammatory bowel disease. In this new study, the research team took a closer look at the lines of communication between the brain and the mouse gut.

The researchers focused specifically on Brunner’s glands, located in the walls of the small intestine. Previous research has shown that their function is to produce mucus to help move material through the intestine. But because they also house many nerve cells, the research team suspects they might do more.

The team found that removing the glands reduced the ability to fight bacterial infections. It also led to inflammation and an overabundance of immune chemicals. They noted that humans have similar experiences after gland removal due to tumor growth.

The team also found that removing the glands eliminated a type of bacteria known to induce the production of proteins that line the intestine, preventing unwanted contents from passing into the bloodstream. Without these bacteria, the intestinal walls became leaky, allowing unwanted materials to pass into the bloodstream, triggering an immune response, which also caused inflammation.

The research team found that nerve cells from the glands were connected directly to the vagus nerve, which winds its way to the amygdala, a part of the brain involved in processing stress.

The final step of the research involved subjecting mice with healthy Brunner’s glands to stress, which resulted in the same symptoms seen when the glands were removed.

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