FIGURE 3.

The microbiota–gut–brain axis. The microbiota exerts an effect on the gut-brain axis, impacting the biochemistry of the peripheral and central nervous system. Commensal and/or pathogenic bacteria and their metabolites are translocated across the intestinal barrier and act on both the digestive immune system and vagal afferents. Similarly, the brain acts on the various organs, including the digestive tract, and can thus regulate the survival and proliferation of the intestinal microbiota.