Gastric Inhibitory PolypeptidePharmaceutical InformationUpdated on Feb 26, 2019 View more like this | Visit SHIRLEY, NY | Contact Cathy Miller |
Introduction
Gastric inhibitory polypeptide (GIP) is an important metabolic hormone in animals. It has a special molecular structure and plays an important physiological role in animal organisms. GIP is an incretin synthesized and secreted by the enteroendocrine cell-K cells in the upper part of the small intestine of the mammal and is an important member of the gastrointestinal regulatory peptide secretin family. GIP was originally isolated in the pig intestines and inhibits the secretion of gastric acid. The half-life of GIP in plasma is shorter, less than 2 min in mice and 7 and 5 min in normal and type 2 diabetic patients, respectively. The highest concentration in the jejunum and a certain amount of secretion in the duodenum and ileum. Its physiological role is inhibition of gastric acid secretion; inhibition of pepsin secretion; stimulation of insulin release; inhibition of gastric peristalsis and emptying; stimulation of intestinal secretion; stimulation of glucagon secretion.
Mechanism of action
GIP has its special precursor structure. GIP is released when the precursor is hydrolyzed by a protease. The released GIP still cannot directly play its role and must be combined with its receptor to produce biological effects. GIP has a role in promoting insulin secretion. When GIP binds to its receptor, it activates adenylate cyclase (AC), which causes an increase in intracellular cyclic AMP (cAMP). cAMP further activates downstream effector proteins including protein kinase A (PKA) and exchange protein directly activated by cAMP (Epac). Activated PKA and Epac cause the downstream KATP channel to shut down, the mitochondrial membrane potential to depolarize, the Ca2+ channel to open and influx, and the intracellular Ca2+ concentration to increase. Finally, the insulin secreting granules are secreted from the pancreatic β cells.
Gastric inhibitory polypeptide (GIP) is an important metabolic hormone in animals. It has a special molecular structure and plays an important physiological role in animal organisms. GIP is an incretin synthesized and secreted by the enteroendocrine cell-K cells in the upper part of the small intestine of the mammal and is an important member of the gastrointestinal regulatory peptide secretin family. GIP was originally isolated in the pig intestines and inhibits the secretion of gastric acid. The half-life of GIP in plasma is shorter, less than 2 min in mice and 7 and 5 min in normal and type 2 diabetic patients, respectively. The highest concentration in the jejunum and a certain amount of secretion in the duodenum and ileum. Its physiological role is inhibition of gastric acid secretion; inhibition of pepsin secretion; stimulation of insulin release; inhibition of gastric peristalsis and emptying; stimulation of intestinal secretion; stimulation of glucagon secretion.
Mechanism of action
GIP has its special precursor structure. GIP is released when the precursor is hydrolyzed by a protease. The released GIP still cannot directly play its role and must be combined with its receptor to produce biological effects. GIP has a role in promoting insulin secretion. When GIP binds to its receptor, it activates adenylate cyclase (AC), which causes an increase in intracellular cyclic AMP (cAMP). cAMP further activates downstream effector proteins including protein kinase A (PKA) and exchange protein directly activated by cAMP (Epac). Activated PKA and Epac cause the downstream KATP channel to shut down, the mitochondrial membrane potential to depolarize, the Ca2+ channel to open and influx, and the intracellular Ca2+ concentration to increase. Finally, the insulin secreting granules are secreted from the pancreatic β cells.
