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Effect of dexamethasone on insulin secretion: examination of underlying mechanisms.
MedLine Citation:
PMID:  20350918     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Objective: To study the mechanism of increased insulin secretion in response to short-term administration of dexamethasone.Methods: Male Wistar rats were injected intraperitoneally with dexamethasone (dexamethasone; 200 mcg/kg body weight per day) or saline for 3 consecutive days. Insulin secretion in response to glucose, ionomycin, and KCl was quantified in islets isolated from the animals, and the amount of glucokinase was measured by Western blot.Results: Dexamethasone-treated animals had 1.18-fold higher fasting blood glucose concentration and 6.5-fold increase in fasting serum insulin concentration compared with findings from animals injected with saline. Compared with islets isolated from control rats, islets from dexamethasone-treated rats secreted more insulin at 60 minutes in response to 5.5 mM glucose (416.4 vs 115.6 fmoles/10 islets, P = .011) and in response to 16.6 mM glucose (985.5 vs 520.6 fmoles/10 islets, P = .014); no change in insulin secretion was observed at 10 minutes. Insulin secretion from islets of dexamethasone-treated rats and control rats was not differentially augmented in response to either ionomycin or potassium chloride. Glucokinase expression was not altered by treatment with dexamethasone.Conclusions: Augmentation of insulin secretion in response to glucose in the pancreatic islets from dexamethasone-treated rats is preserved in islets studied in vitro. The increase in glucose-stimulated insulin secretion appears to be mediated by steps upstream to β-cell membrane depolarization and the attended increase in intracellular calcium in the signaling pathway of insulin secretion.
Authors:
Ajay Sood; Faramarz Ismail-Beigi
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Endocrine practice : official journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists     Volume:  16     ISSN:  1934-2403     ISO Abbreviation:  Endocr Pract     Publication Date:    2010 Sep-Oct
Date Detail:
Created Date:  2011-03-01     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9607439     Medline TA:  Endocr Pract     Country:  United States    
Other Details:
Languages:  eng     Pagination:  763-9     Citation Subset:  IM    
Affiliation:
Division of Clinical and Molecular Endocrinology, Department of Medicine, Case Western Reserve University, Cleveland, Ohio.
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