Figure 1. Diagrammatic representation of the M-G-B axis showing the proposed bidirectional communications.
Gut microbiota can release molecules that can: activate the neuroenteric plexus, stimulate brain production of neuropeptides, as well as increase gut-blood barrier and BBB permeability. The brain releases molecules that stimulate the neuroenteric plexus and gut function. The vagus nerve sends orthodromic and antidromic.
Ach= Acetylcholine
BBB= Blood-brain barrier
CRH= Corticotropin-releasing hormone
5-HT= 5-hydroxytryptamine
IL-6= Interleukin 6
NT= Neurotensin
SP= Substance P
TNF= Tumor necrosis factor
VIP= Vasoactive intestinal peptide