Receptors gastrin

Two CCK receptor subtypes, CCK and CCKg are known. A related receptor, the gastrin receptor, has also been described. CCK receptors predominate in the gastrointestinal tract and pancreas and are also localized in discrete brain regions. CCKg receptors predominate in the brain. A 71623... 

CCKp/Gastrin Receptor Mutations and Gastrointestinal Carcinoma... 

Schmitz, F., Schrader, H., Otte, J. M., et al. (2001) Identification of CCK-B/gastrin receptor splice variants in human peripheral blood mononuclear cells. Regul. Pept. 101, 25-33. 

Gastrin receptors Gastrin carcinomas, colonic carcinomas... 

Lee YM, Beinbom M, McBride EW, et al The human brain cholecystokinin-B/gastrin receptor cloning and characterization. J Biol Chem 268 8164-8169, 1993 Legris P, George Y, Boval P, et al A comparative study of alpidem versus Buspirone, in Imidazopyridines in Anxiety Disorders A Novel Experimental and Therapeutic Approach. Edited by Barthohni G, Garreau M, MorseUi PL. New York, Raven, 1993, pp 183-192... 

Hormonal gastrin secreted by the G cells of the gastric antrum stimulates the parietal cells directly through gastrin receptors (increased Ca2+ as second messenger), and probably also indirectly by acting on enterochromaffin-iike (ECL) cells to release histamine. 

Fig. 1. Schematic diagram showing the different mechanisms of action proposed for the antiulcer action of flavonoids. 1. Blockade of add secretion by decreasing histamine production or inhibiting the proton pump. 2. Bactericidal effect on H. pylori. 3. Antioxidative activity by scavenging free radicals and preventing ROM formation. 4. Potentiation of the mucosal protective factors. PAF platelet activating factor ROM reactive oxygen metabolites H2 histamine receptor 2 M muscarinic receptor G gastrin receptor.

As the H+ is pumped into the lumen of the stomach, HC03 moves out of parietal cells into blood and Cl- enters the cell in exchange. Acid secretion is stimulated by histamine acting on H2 receptors, by acetylcholine acting on muscarinic (Ml) receptors and by gastrin acting on gastrin receptors of the parietal cells. 

The gastrin receptor is one of the receptors that bind cholecystokinin (Table 13.4), and is known as the CCK-B receptor it is another member of the G-protein-coupled receptor family. 

Pentagastrin is a short peptide that stimulates the production of gastric acid from the stomach by a direct action on gastrin receptors and of calcitonin from thyroid C cells (1). It also acts on cholecystokinin receptors centrally and stimulates the release of adrenocorticotropin (ACTH) and hence the production of glucocorticoids (2). 

CCKg receptors (also called CCKg/gastrin receptors) show an order of potency CCK-8 > gastrin = desulpluted-CCK-8... 

Gastrin receptor antagonists and gastrin-releasing peptide antagonists have now been developed for experimental use. but it is not yet clear if either will be useful clinically. See BOMBESIN RECEPTOR ANTAGONISTS) CHOLECYSTOKININ RECEPTOR ANTAGONISTS. 

It is involved in the control of gastric secetion. The main member of the series is a 17 amino acid residue linear peptide, which has a structure similar to cholecystokinin, and is a (CCKj/gastrin receptor subtype) cholecystokinin RECEPTOR AGONIST. There are large numbers of species-... 

Therefore, there seems to be a complex interaction among the three receptors, acetylcholine receptors, H2 receptors, and gastrin receptors involved in the acid secretion by parietal cells. 

The discovery of the first nonpetide CCK antagonist, the natural product asperlicin, in 1985 (495) shifted the medicinal chemistry focus from peptides to small molecule antagonists (496,497).CCK-B receptors are the dominant isoform in the brain, and antagonists at this subtype are potential anxiolytics. Many CCK-B antagonists also modulate gastric acid secretion through peripheral CCK-B (gastrin) receptors. 

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