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Capsaicin-sensitive sensory fibers in the islets of Langerhans contribute to defective insulin secretion in Zucker diabetic rat, an animal model for some aspects of human type 2 diabetes

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Author

  • Dorte X. Gram
  • Bo Ahrén
  • Istvan Nagy
  • Uffe B. Olsen
  • Christian L. Brand
  • Frank Sundler
  • Rene Tabanera
  • Ove Svendsen
  • Richard D. Carr
  • Peter Santha
  • Nils Wierup
  • Anker J. Hansen
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Summary, in English

The system that regulates insulin secretion from beta-cells in the islet of Langerhans has a capsaicin-sensitive inhibitory component. As calcitonin gene-related peptide (CGRP)-expressing primary sensory fibers innervate the islets, and a major proportion of the CGRP-containing primary sensory neurons is sensitive to capsaicin, the islet-innervating sensory fibers may represent the capsaicin-sensitive inhibitory component. Here, we examined the expression of the capsaicin receptor, vanilloid type 1 transient receptor potential receptor (TRPV1) in CGRP-expressing fibers in the pancreatic islets, and the effect of selective elimination of capsaicin-sensitive primary afferents on the decline of glucose homeostasis and insulin secretion in Zucker diabetic fatty (ZDF) rats, which are used to study various aspects of human type 2 diabetes mellitus. We found that CGRP-expressing fibers in the pancreatic islets also express TRPV1. Furthermore, we also found that systemic capsaicin application before the development of hyperglycemia prevents the increase of fasting, non-fasting, and mean 24-h plasma glucose levels, and the deterioration of glucose tolerance assessed on the fifth week following the injection. These effects were accompanied by enhanced insulin secretion and a virtually complete loss of CGRP- and TRPV1-coexpressing islet-innervating fibers. These data indicate that CGRP-containing fibers in the islets are capsaicin sensitive, and that elimination of these fibers contributes to the prevention of the deterioration of glucose homeostasis through increased insulin secretion in ZDF rats. Based on these data we propose that the activity of islet-innervating capsaicin-sensitive fibers may have a role in the development of reduced insulin secretion in human type 2 diabetes mellitus.

Publishing year

2007

Language

English

Pages

213-223

Publication/Series

European Journal of Neuroscience

Volume

25

Issue

1

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Neurosciences

Keywords

  • primary sensory neuron
  • CGRP
  • low-grade inflammation
  • TRPV1

Status

Published

Research group

  • Neuroendocrine Cell Biology

ISBN/ISSN/Other

  • ISSN: 1460-9568