M6 Gut-brain axis

Topic

The gut microbiota communicates bidirectionally with the central nervous system via the gut-brain axis. The composition of the gut microbiota is shaped by Lotka-Volterra-type competitive dynamics, wherein the various species constituting the microbiota compete for available resources within the gut.

The fermentative activity of the gut microbiota generates short-chain fatty acids that act as signals transmitted to the vagus nerve; this extends the neural coding formalism—previously described in another model—to an afferent signal originating in the body's periphery rather than the central nervous system.

The integrity of the intestinal epithelial barrier regulates the translocation of bacterial lipopolysaccharides (produced by the gut microbiota) into the systemic circulation: when local inflammation increases barrier permeability, greater amounts of bacterial lipopolysaccharide enter the systemic circulation, potentially inducing central neuroinflammation—the same type of neuroinflammation relevant to other models in this catalog.

Furthermore, the gut microbiota participates in the metabolism of neurotransmitter precursors such as tryptophan—the same precursor involved in serotonergic monoamine neurotransmission previously described in the major depression model. Ultimately, it is this gut microbiota—characterized by its competitive composition, fermentative signaling to the vagus nerve, regulation of intestinal epithelial barrier permeability, and involvement in neurotransmitter precursor metabolism—that sustains the bidirectional communication of the gut-brain axis with the central nervous system.

ID:4278