The two-way communication highway between your gut and your brain—including nerves, hormones, and immune signals.The gut-brain axis encompasses bidirectional communication between the gastrointestinal tract and central nervous system via the vagus nerve, enteric nervous system, circulating hormones (ghrelin, CCK, GLP-1, PYY), immune mediators, and microbial metabolites. Gut peptide hormones including cholecystokinin, ghrelin, and neuropeptide Y are key mediators of appetite regulation, satiety signaling, and stress responses. Disruption of gut-brain axis signaling is implicated in functional gastrointestinal disorders, obesity, and mood disorders.H↑ Top