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Somatostatin secreted by islet delta-cells fulfills multiple roles as a paracrine regulator of islet function.
- Source :
- Diabetes; Feb2009, Vol. 58 Issue 2, p403-411, 9p
- Publication Year :
- 2009
-
Abstract
- <bold>Objective: </bold>Somatostatin (SST) is secreted by islet delta-cells and by extraislet neuroendocrine cells. SST receptors have been identified on alpha- and beta-cells, and exogenous SST inhibits insulin and glucagon secretion, consistent with a role for SST in regulating alpha- and beta-cell function. However, the specific intraislet function of delta-cell SST remains uncertain. We have used Sst(-/-) mice to investigate the role of delta-cell SST in the regulation of insulin and glucagon secretion in vitro and in vivo.<bold>Research Design and Methods: </bold>Islet morphology was assessed by histological analysis. Hormone levels were measured by radioimmunoassay in control and Sst(-/-) mice in vivo and from isolated islets in vitro.<bold>Results: </bold>Islet size and organization did not differ between Sst(-/-) and control islets, nor did islet glucagon or insulin content. Sst(-/-) mice showed enhanced insulin and glucagon secretory responses in vivo. In vitro stimulus-induced insulin and glucagon secretion was enhanced from perifused Sst(-/-) islets compared with control islets and was inhibited by exogenous SST in Sst(-/-) but not control islets. No difference in the switch-off rate of glucose-stimulated insulin secretion was observed between genotypes, but the cholinergic agonist carbamylcholine enhanced glucose-induced insulin secretion to a lesser extent in Sst(-/-) islets compared with controls. Glucose suppressed glucagon secretion from control but not Sst(-/-) islets.<bold>Conclusions: </bold>We suggest that delta-cell SST exerts a tonic inhibitory influence on insulin and glucagon secretion, which may facilitate the islet response to cholinergic activation. In addition, delta-cell SST is implicated in the nutrient-induced suppression of glucagon secretion. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00121797
- Volume :
- 58
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- Diabetes
- Publication Type :
- Academic Journal
- Accession number :
- 105634479
- Full Text :
- https://doi.org/10.2337/db08-0792