enteroendocrine cell neuroendocrine cell somatostatin secreting cell type D enteroendocrine cell FMA:62935 D cell ZFA:0009228 A cell found throughout the gastrointestinal tract and in the pancreas. They secrete somatostatin in both an endocrine and paracrine manner. Somatostatin inhibits gastrin, cholecystokinin, insulin, glucagon, pancreatic enzymes, and gastric hydrochloric acid. A variety of substances which inhibit gastric acid secretion (vasoactive intestinal peptide, calcitonin gene-related peptide, cholecystokinin, beta-adrenergic agonists, and gastric inhibitory peptide) are thought to act by releasing somatostatin. Type D enteroendocrine cells, also known as D or delta cells, are specialized hormone-releasing cells found in the pancreas and also scattered throughout the lining of the gastrointestinal tract in mammals, notably within the stomach and the upper part of the small intestine known as the duodenum. The primary role of D cells is to produce and secrete somatostatin, a potent paracrine inhibitor. In the gastrointestinal tract, somatostatin slows down digestion. It reduces gastric acid secretion and slows down the rate of gastric emptying, thereby prolonging and controling the digestive p. Functionally, these effects are aimed at sustaining nutrient absorption to optimize energy extraction from consumed food. In the pancreas, D cells maintain a vital role in endocrine regulation. D cells in the pancreatic islands secrete somatostatin to inhibit the release of both insulin and glucagon from type A cells and B cells, glucoregulatory hormones that control blood sugar levels. Hence, D cells contribute considerably to the homeostasis of the body's metabolic processes. It is also noteworthy that dysfunctional D cells or irregular somatostatin signaling has been associated with certain pathologies such as neuroendocrine tumors and gastric ulcers. (This extended description was generated by ChatGPT and reviewed by the CellGuide team, who added references, and by the CL editors, who approved it for inclusion in CL. It may contain information that applies only to some subtypes and species, and so should not be considered definitional.)