Enteroglucagon.
The gene encoding proglucagon, the biosynthetic precursor of glucagon, is expressed not only in the pancreatic islets but also in endocrine cells of the gastrointestinal mucosa. The proglucagon (PG)-derived peptides from the gut include glicentin (corresponding to PG 1-69); smaller amounts of oxyntomodulin (PG 33-69) and glicentin-related pancreatic polypeptide (GRPP, PG 1-30); glucagon-like peptide-1 (GLP-1, PG 78-107 amide); intervening peptide-2 (IP-2, PG 111-122 amide); and glucagon-like peptide-2 (GLP-2, PG 126-158). All are secreted into the blood in response to ingestion of carbohydrates and lipids. Only oxyntomodulin and GLP-1 have proven biological activity; oxyntomodulin possibly because it interacts (but with lower potency) with GLP-1 and glucagon receptors. GLP-1 is the most potent insulinotropic hormone known and functions as an incretin hormone. It also inhibits glucagon secretion and, therefore, lowers blood glucose. This effect is preserved in patients with non-insulin-dependent diabetes mellitus, in whom infusions of GLP-1 may completely normalize blood glucose. However, GLP-1 also potently inhibits gastrointestinal secretion and motility, and its physiological functions include mediation of the "ileal-brake" effect, i.e. the inhibition of upper gastrointestinal functions elicited by the presence of unabsorbed nutrients in the ileum. As such it may serve to regulate food intake.
Holst
J J
JJ
Department of Medical Physiology, Panum Institute, University of Copenhagen, Denmark.
D000818:Animals; D053771:Glicentin; D005934:Glucagon / Q000378:metabolism / Q000502:physiology; D052216:Glucagon-Like Peptide 1; D053767:Glucagon-Like Peptide 2; D004763:Glucagon-Like Peptides / Q000502:physiology*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D053772:Oxyntomodulin; D010446:Peptide Fragments / Q000378:metabolism / Q000502:physiology; D010455:Peptides / Q000502:physiology; D052336:Proglucagon; D011498:Protein Precursors / Q000378:metabolism / Q000502:physiology
D053767:Glucagon-Like Peptide 2; D053772:Oxyntomodulin; D010446:Peptide Fragments; D010455:Peptides; D011498:Protein Precursors; D052336:Proglucagon; D004763:Glucagon-Like Peptides; D053771:Glicentin; C031026:glicentin-related pancreatic peptide; D052216:Glucagon-Like Peptide 1; D005934:Glucagon