Beta cell adaptation to dexamethasone-induced insulin resistance in rats involves increased glucose responsiveness but not glucose effectiveness

Research output: Contribution to journalArticle

Abstract

Islet beta cell adaptation to dexamethasone-induced insulin resistance was characterized with respect to glucose-stimulated insulin secretion and islet innervation. Male Sprague-Dawley rats were injected daily with dexamethasone (2 mg/kg for 12 days), which resulted in hyperinsulinemia and hyperglycemia compared with controls (which were injected with sodium chloride). Insulin secretion was characterized in collagenase-isolated islets. Islet innervation was examined by immunocytochemical analysis of tyrosine hydroxylase, neuropeptide Y (sympathetic nerves), and vasoactive intestinal polypeptide (cholinergic nerves). In islets isolated from the insulin-resistant animals, the insulin response to 3.3 or 8.3 mM glucose was three times greater during perifusion compared with controls (p < 0.001). Incubation of islets at 0 to 20 mM glucose revealed a marked leftward shift of the glucose dose-response relation after dexamethasone treatment (potency ratio, 1.78; p < 0.01), with no difference at 0 or 20 mM glucose. Thus, the potency but not the efficacy of glucose was increased. The number of islet nerves did not differ between dexamethasone-treated rats and controls. Dexamethasone-induced insulin resistance leads to adaptively increased glucose responsiveness of the islet beta cells, with increased potency, but not increased efficacy, of glucose to stimulate insulin secretion without any evidence of altered islet innervation.

Details

Authors
  • Sven Karlsson
  • Björn Ostlund
  • Ulrika Myrsen-Axcrona
  • Frank Sundler
  • Bo Ahrén
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Cell and Molecular Biology
  • Other Clinical Medicine

Keywords

  • Islet, Beta Cell, Insulin Secretion, Insulin Resistance, Dexamethasone, Autonomic Nerves, Neuropeptide Y, Vasoactive Intestinal Polypeptide
Original languageEnglish
Pages (from-to)148-156
JournalPancreas
Volume22
Issue number2
Publication statusPublished - 2001
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Medicine (Lund) (013230025), Neuroendocrine Cell Biology (013212008)