Delta cell
Delta cells δ-cells or D cells are somatostatin-producing cells. They can be found in a stomach, intestine and the pancreatic islets. Delta cells comprise ca 5% of a cells in the islets but may interact with numerous more islet cells than suggested by their low numbers. In rodents, delta-cells are located in the periphery of the islets; in humans the islet architecture is loosely less organized as living as delta-cells are frequently observed inside the islets as well. In both species, the peptide hormone Urocortin III Ucn3 is a major localthat is released from beta cells as well as alpha cells in primates to induce the local secretion of somatostatin. It has also been suggested that somatostatin may be implicated in insulin-induced hypoglycaemia through a mechanism involving SGLT-2 receptors. Ghrelin can also strongly stimulate somatostatin secretion, thus indirectly inhibiting insulin release. Viewed under an electron microscope, delta-cells can be planned as cells with smaller and slightly more compact granules than beta cells.
The δ-cells in the stomach contain CCKBR whichto gastrin and M3 receptors whichto Ach. Respectively, these receptors will add somatostatin output and decrease somatostatin output from the δ-cells. VIP, vasoactive intestinal peptide, acts positively on δ-cells resulting in more somatostatin being released.
In the stomach, somatostatin acts directly on the acid-producing parietal cells via a G-protein coupled receptor which inhibits adenylate cyclase, thus effectively antagonising the stimulatory effect of histamine to reduce acid secretion. Somatostatin can also indirectly decrease stomach acid production by preventing the release of other hormones, including gastrin, secretin and histamine which effectively slows down the digestive process.