Somatostatin secretion

In the trans Golgi compartment the peptide is sorted via secretory vesicles into a regulated pathway. In contrast to vesicles of the constitutive pathway, vesicles of the regulated pathway are stored in the cytoplasm until their stimulated release. Membrane depolarisation as well as a wide range of substances such as intracellular mediators, neuropeptides, neurotransmitters, classical hormones, cytokines, growth factors, ions and nutrients induce somatostatin secretion. General inhibitors of somatostatin release are opiates, GABA, leptin and TGF- 3. 

Octreotide is a somatostatin analogue it is used in the treatment of somatostatin-secreting pituitary tumors. 

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)... 

Bado, A., Moizo, L., Laigneau, J.P., Lewin, M.J.M., 1992b. Gastrin and somatostatin secretion by isolated perfused rat stomach regulation by the gastric histamine H3-receptor. Gastroenterology 102, A916. 

Schubert, M.L., Harrington, L., Makhlouf,. G.M., 1993. Histamine H3-receptors are coupled to inhibition of somatostatin secretion in the fundus and antrum of the stomach. Gastroenterology 104 (Suppl), A854. 

Vuyyuru, L., Harrington, L., Arimura, A., Schubert, ML. (1997). Reciprocal inhibitory paracrine pathways link histamine and somatostatin secretion in the fundus of the stomach. Am. J. Physiol. 273, G106-G111. 

Kitajima N, Chihara K, Abe H, Okimura Y, Fujii Y, Sato M, Shakutsui S, Watanabe M, Fujita T (1989) Effects of dopamine on immunoreactive growth hormone-releasing factor and somatostatin secretion from rat hypothalamic slices perifused in vitro. Endocrinology 124 69-16. 

Plotsky PM, Vale W (1985) Patterns of growth hormone-releasing factor and somatostatin secretion into the hypophysial-portal circulation of the rat. Science 230 461-463. 

Islets of Langerhans are clusters of endocrine cells in the pancreas. One distinguishes the gjucagon-secreting A cells, the insulin-secteting B cells and the somatostatin-secreting D cells. (Named after Paul Langerhans who first described such clusters of ceUs as a medical student in 1869). 

The conorfamides, isolated from Conus spurius, belong to the RFamide neuropeptide family and may act as an agonist of the FMRF-amide-gated ion channels. In invertebrates, this peptide family has many diverse functions, whereas in the mammalian system they moderate opioid function in the CNS, modulate epithelial Na" " channels, have important cardiovascular effects, and stimulate pancreatic somatostatin secretion. ... 

The secretagogues for somatostatin are similar to those that cause secretion of insulin. The metabolites that increase somatostatin release include glucose, arginine, and leucine. The hormones that stimulate somatostatin secretion include glucagon, vasoactive intestinal polypeptide (VIP), and cholecystokinin (CCK). Insulin, however, does not directly influence somatostatin secretion. 

Martha, P.A. Jr, R.M. Blizzard, J.A. McDonald, M.O. Thorner A.D. Rogol. 1988. A persistent pattern of varying pituitary responsivity to exogenous growth hormone (GH)-releasing hormone in GH-deficient children Evidence supporting periodic somatostatin secretion. J. Clin. Endocrinol. Metab. 67 449-54. 

Homeostatic Hormones. Insulin is produced by beta cells found in the islets of Langerhans that are dispersed throughout the pancreas. The islet cells constitute only 1% of total pancreatic tissue. Each islet contains about 3000 endocrine cells with a core of beta cells surrounded by other endocrine cells such as the glucagon-secreting alpha cells, the somatostatin-secreting delta cells, and the pancreatic polypeptide-secreting PP cells. The beta cells first synthesize a 109-amino-acid preproinsulin that is subsequently processed to an 86-amino-acid proinsulin. The... 

Schubert ML, Makhlouf GM. Regulation of gastrin and somatostatin secretion by intramural neurons effect of nicotinic receptor stimulation with dimethyl-phenylpiperazinium. Gastroenterology 1982 83 626-632. 

This process also appears to involve a decrease in parietal and gastrin-secreting cells and a tendency to increase somatostatin-secreting cell numbers. A further change is the generation of a new population of vesiculated cells, some of which have features of immature mucous neck cells. These are present in the... 

Alba-Roth J, Muller OA, Schopohl J, von Werder K. Arginine stimulates growth hormone secretion by suppressing endogenous somatostatin secretion. J Clin Endocrinol Metab 1988 67 1186-1189. 

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