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.
Types The gastrointestinal hormonesVella A and Drucker DJ (2011)Chapter 39 Gastrointestinal Hormones and Gut Endocrine Tumors, pp 1697-1707. In Williams Textbook of Endocrinology (2011, 12th edition) can be divided into three main groups based upon their chemical structure. Gastrin–cholecystokinin family: gastrin and cholecystokinin Secretin family: secretin, glucagon, vasoactive intestinal peptide and gastric inhibitory peptide Somatostatin family Motilin family Substance P.
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 Hormone or peptide Molecular weight (Da) Number of amino acids Main gut localization Principal physiologic actions Gastrin family Cholecystokinin 3918 33 (also 385, 59) Duodenum and jejunum, Enteric nerves Stimulates 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 gastrin 2098 17 Both forms of gastrin are found in the gastric antrum and duodenum Gastrins stimulate the secretion of gastric acid, pepsinogen, intrinsic factor, and secretin; stimulate intestinal mucosal growth; increase gastric and intestinal motility Big gastrin 3839 34 Secretin-glucagon family Secretin 3056 27 Duodenum and jejunum Stimulates pancreatic secretion of HCO3, enzymes and insulin; reduces gastric and duodenal motility, inhibits gastrin release and gastric acid secretion Vasoactive intestinal polypeptide (VIP) 3326 28 Enteric nerves Relaxes 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 insulinotropic 4976 42 Duodenum and jejunum Stimulates insulin release; reduces gastric and intestinal motility; increases fluid and electrolyte secretion from small intestine
+ Brief Description of Some GI Regulatory Peptides Hormone or peptide Major tissue locations in the gut Principal known actions Bombesin Throughout the gut and pancreas Stimulates release of cholecystokinin (CCK) and gastrin Calcitonin gene-related peptide Enteric nerves Unclear Chromogranin A Neuroendocrine cells Secretory protein Enkephalins Stomach, duodenum Opiate-like actions Enteroglucagon Small intestine, pancreas Inhibits insulin secretion Galanin Enteric nerves Ghrelin Stomach Stimulates appetite, increases gastric emptying Glucagon-like peptide 1 Pancreas, ileum Increases insulin secretion Glucagon-like peptide 2 Ileum, colon Enterocyte-specific growth hormone Growth factors Throughout the gut Cell proliferation and differentiation Growth hormone-releasing factor Small intestine Unclear Leptin Stomach Appetite control Motilin Throughout the gut Increases gastric emptying and small bowel motility Neuropeptide Y Enteric nerves Regulation of intestinal blood flow Neurotensin Ileum Affects gut motility; increases jejunal and ileal fluid secretion Pancreatic polypeptide Pancreas Inhibits pancreatic and biliary secretion Peptide YY Colon Inhibits food intake Somatostatin Stomach, pancreas Inhibits secretion and action of many hormones Substance P Enteric nerves Unclear Trefoil peptides Stomach, intestine Mucosal protection and repair
See also Hormone, endocrine system Digestive system, gastrointestinal tract Peptide YY
Notes and references
External links Overview of Gastrointestinal Hormones - Colorado State University website