Gastrointestinal hormone

The gastrointestinal hormones (or gut hormones) constitute a group of hormones secreted by enteroendocrine cells in the stomach, pancreas, and small intestine that control various functions of the digestive organs. Later studies showed that most of the gut peptides, such as secretin, cholecystokinin or substance P, were found to play a role of neurotransmitters and neuromodulators in the central and peripheral nervous systems.

Enteroendocrine cells do not form glands but are spread throughout the digestive tract. They exert their autocrine and paracrine actions that integrate gastrointestinal function.[1]

Types

The gastrointestinal hormones[2] can be divided into three main groups based upon their chemical structure.

Ghrelin is a peptide hormone released from the stomach and liver and is often referred to as the "hunger hormone" since high levels of it are found in individuals that are fasting. Ghrelin agonistic treatments can be used to treat illnesses such as anorexia and loss of appetites in cancer patients. Ghrelin treatments for obesity are still under intense scrutiny and no conclusive evidence has been reached. This hormone stimulates growth hormone release. Amylin controls glucose homeostasis and gastric motility

Glucose-dependent insulinotropic polypeptide possesses an acute influence on food intake through its effects on adipocytes

Oxyntomodulin plays a role in controlling acid secretion and satiation

Characteristics of prominent forms of principal gut regulatory peptides[3]: 1719 
Hormone or peptideMolecular weight (Da)Number of amino acidsMain gut localizationPrincipal physiologic actions
Gastrin family
Cholecystokinin391833 (also 385, 59)Duodenum and jejunum, Enteric nervesStimulates gallbladder contraction and intestinal motility; stimulates secretion of pancreatic enzymes, insulin, glucagon, and pancreatic polypeptides; has a role in indicating satiety; the C-terminal 8 amino acid peptide cholecystokinin (CCK)-8 retains full activity
Little gastrin209817Both forms of gastrin are found in the gastric antrum and duodenumGastrins stimulate the secretion of gastric acid, pepsinogen, intrinsic factor, and secretin; stimulate intestinal mucosal growth; increase gastric and intestinal motility
Big gastrin383934
Secretin-glucagon family
Secretin305627Duodenum and jejunumStimulates pancreatic secretion of HCO3, enzymes and insulin; reduces gastric and duodenal motility, inhibits gastrin release and gastric acid secretion
Vasoactive intestinal polypeptide (VIP)332628Enteric nervesRelaxes smooth muscle of gut, blood vessels, and genitourinary system; increases water and electrolyte secretion from pancreas and gut; releases hormones from pancreas, gut, and hypothalamus
Glucose-dependent insulinotropic497642Duodenum and jejunumStimulates insulin release; reduces gastric and intestinal motility; increases fluid and electrolyte secretion from small intestine
Brief Description of Some GI Regulatory Peptides[3]: 1720 
Hormone or peptideMajor tissue locations in the gutPrincipal known actions
BombesinThroughout the gut and pancreasStimulates release of cholecystokinin (CCK) and gastrin
Calcitonin gene-related peptideEnteric nervesUnclear
Chromogranin ANeuroendocrine cellsSecretory protein
EnkephalinsStomach, duodenumOpiate-like actions
EnteroglucagonSmall intestine, pancreasInhibits insulin secretion
GalaninEnteric nerves
GhrelinStomachStimulates appetite, increases gastric emptying
Glucagon-like peptide 1Pancreas, ileumIncreases insulin secretion
Glucagon-like peptide 2Ileum, colonEnterocyte-specific growth hormone
Growth factorsThroughout the gutCell proliferation and differentiation
Growth hormone-releasing factorSmall intestineUnclear
LeptinStomachAppetite control
MotilinThroughout the gutIncreases gastric emptying and small bowel motility
Neuropeptide YEnteric nervesRegulation of intestinal blood flow
NeurotensinIleumAffects gut motility; increases jejunal and ileal fluid secretion
Pancreatic polypeptidePancreasInhibits pancreatic and biliary secretion
Peptide YYColonInhibits food intake
SomatostatinStomach, pancreasInhibits secretion and action of many hormones
Substance PEnteric nervesUnclear
Trefoil peptidesStomach, intestineMucosal protection and repair

See also

Notes and references
  1. "Enteric Endocrine System". www.vivo.colostate.edu. Retrieved 2016-09-16.
  2. Vella A and Drucker DJ (2011)Chapter 39 Gastrointestinal Hormones and Gut Endocrine Tumors, pp 1697-1707. In Williams Textbook of Endocrinology (2011, 12th edition)
  3. Burtis CA, Ashwood ER, Bruns DE (2012-10-14). Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 5th edition. Elsevier Saunders. ISBN 978-1-4160-6164-9.
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