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
Författare
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.
Publiceringsår
2007
Språk
Engelska
Sidor
213-223
Publikation/Tidskrift/Serie
European Journal of Neuroscience
Volym
25
Issue
1
Länkar
Dokumenttyp
Artikel i tidskrift
Förlag
Wiley-Blackwell
Ämne
- Neurosciences
Nyckelord
- primary sensory neuron
- CGRP
- low-grade inflammation
- TRPV1
Status
Published
Forskningsgrupp
- Neuroendocrine Cell Biology
ISBN/ISSN/Övrigt
- ISSN: 1460-9568