Gastrointestinal hormones

Gastrointestinal regulatory peptides include hormones, paracrines and neurocrines. The hormones include gastrin, cholecystokinin, secretin and glucose-dependent insulinotropic peptide. Paracrines include a peptidic one – somatostatin – and a nonpeptidic one – histamine. Among the neurocrines, there are acetylcholine, norepinephrine, vasoactive intestinal peptide, nitric oxide, gastrin-releasing peptide – also known as bombesin –, enkephalins, neuropeptide Y and substance P. They modulate the activity of the gastrointestinal tract, regulate its motility, and coordinate the digestion and absorption process.