Gastric acid secretion somatostatin

There are a variety of peptide hormones acting in the gut the gastrins stimulate gastric acid secretion secretin and somatostatin inhibit the production of gastrins. Cholecystokinin and somatostatin can inhibit gastric acid secretion directly, and the former one causes the gall-bladder to contract and thus force bile into the duodenum. 

Gastric acid secretion can be pharmacologically inhibited by specific antagonists of the stimulatory receptors (histamine-Hj, muscarine-Mi/Mj, gastrin), by agonists to inhibitory receptors (prostaglandin, somatostatin), by carbonic anhydrase inhibitors, and by HVK -ATPase inhibitors. 

Krejs, G. J. (1986). Physiological role of somatostatin in the digestive tract Gastric acid secretion, intestinal absorption, and motility. Scand.. Gastroenterol., Suppi. 21(119], 47-53. 

The somatostatin analog octreotide can decrease gastric acid secretion. In one report, octreotide, given s.c. to horses at dose rates of 0.1,0.5,1.0 and 5.0 xg/kg, increased gastric pH to >5.0 compared with baseline values (consistently <2.7) (Rabon Reuben 1990). The duration of effect was dose dependent and ranged from 2.4 to 5.4 h. 

Gastric acid secretion can be inhibited by several mechanisms including acid in the stomach (pH 3 inhibits gastrin release), acid in the duodenum, the presence of fat in the pancreas, and hypertonic fluids or hyperglycemia. Somatostatin, a hormone produced by antral mucosal endocrine cells (D cells), inhibits the release of gastrin by directly inhibiting the parietal cells. Somatostatin is also present in other GI tissue and the pancreas. C cells, endocrine cells in the proximal small intestine, secrete secretin in response to mucosal acidification, which also decreases gastric secretion. 

Gastrin Enteroendocrine G cells of the stomach, duodenal bulb, and other cells Induces gastric acid secretion 1. Luminal contents, especially aromatic amino acids, calcium, coffee, and ethanol 2. Vagus nerve stimulation activation of beta-adrenergic and GABA neurons 3. Somatostatin inhibits secretion... 

Secretin Enteroendocrine S cells in upper small bowel 1. Stimulates pancreatic and biliary bicarbonate and water secretion 2. Regulates pancreatic enzyme secretion 3. Inhibits postprandial gastric emptying, gastrin release, and gastric acid secretion 1. Gastric acid, bile salts, fatty acids, peptides, and ethanol 2. Somatostatin inhibits secretion... 

The disorders associated with abnormal gastric secretion rates and the frequency with which the abnormality occurs are listed in Table 4. In the Zollinger-Ellison syndrome (ZES), basal acid secretion rates are 60% of maximal or greater (BAO/PAO O.6). In addition, decreased gastric acid secretion is rarely seen in patients with the som-atostatinoma syndrome, a condition associated with an islet cell tumor that secretes excessive amounts of somatostatin, a hormone that inhibits acid secretion. There are recent reports of decreased gastric acid, pepsin and intrinsic factor outputs as part of a gastric... 

In the mouse, whereas no evidence of H3 receptors was found in isolated gastric glands (Muller et al., 1993), in the whole stomach, (R)a-methylhistamine actually increased, and thioperamide decreased acid secretion, thus indicating a definite stimulatory role for H3 receptors in this species (Table 2). Apparently, this excitatory effect, which contrasts with the observations obtained in other models, was due to an inhibitory effect on somatostatin release from fundic D cells (Schubert et al., 1993 Vuyyuru and Schubert 1993). Also, an inhibitory effect on somatostatin secretion mediated by H3 agonists was observed in other species (rat and dog). However, contrarily to what might have been expected, in these species, the inhibitory effect on somatostatin is not followed by an increase in acid secretion, but it is instead followed by a decrease, owing to the predominant H3-mediated inhibition on the release of excitatory mediators (histamine, acetylcholine) from other sites (ECL, cholinergic nerve terminals)... 

The release of histamine is the most important positive regulation mechanism of the secretion of gastric acid in the stomach its release is stimulated by gastrin and acetylcholine and inhibited by somatostatin. 

The oxyntic gland is the secretory unit of the gastric mucosa. The acid-secreting parietal cells are located in the wall of its midsection. In addition to parietal cells, these glands consist of mucous-secreting superficial and neck cells, pepsinogen-secreting chief cells, endocrine, and somatostatin cells [1]. 

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