Glucose intolerance and reduced proliferation of pancreatic β-cells in transgenic pigs with impaired GIP function

  1. Eckhard Wolf (ewolf{at}lmb.uni-muenchen.de)1
  1. 1Chair for Molecular Animal Breeding and Biotechnology, and Laboratory for Functional Genome Analysis (LAFUGA), Gene Center, LMU Munich, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany
  2. 2Institute of Veterinary Pathology, Faculty of Veterinary Medicine, LMU Munich, Veterinärstrasse 13, D-80539 Munich, Germany
  3. 3Institute of Pharmacology and Toxicology, and
  4. 4Pharma Center Bonn, University of Bonn, Reuterstrasse 2b, D-53113 Bonn, Germany
  5. 5Experimental Transplantation Immunology, Surgical Clinic I, University Hospital of Würzburg, Oberdürrbacher Strasse 6, D-97080 Würzburg, Germany
  6. 6Institute of Anatomy and Physiology, University of Stuttgart-Hohenheim, Fruhwirthstrasse 35, D-70593 Stuttgart
  7. 7Medical Clinic II, Klinikum Grosshadern, LMU Munich, Marchioninistrasse 15, D-81377 Munich, Germany

Abstract

Objective: The insulinotropic action of the incretin glucose-dependent insulinotropic polypeptide (GIP) is impaired in type 2 diabetes while the effect of glucagon-like peptide-1 (GLP-1) is preserved. To evaluate the role of impaired GIP function in glucose homeostasis and development of the endocrine pancreas in a large animal model, we generated transgenic pigs expressing a dominant-negative GIP receptor (GIPRdn) in pancreatic islets.

Research Design And Methods: GIPRdn transgenic pigs were generated using lentiviral transgenesis. Metabolic tests and quantitative stereological analyses of the different endocrine islet cell populations were performed, and β-cell proliferation and apoptosis were quantified to characterize this novel animal model.

Results: Eleven-week-old GIPRdn transgenic pigs exhibited significantly reduced oral glucose tolerance due to delayed insulin secretion, whereas intravenous glucose tolerance and pancreatic β-cell mass were not different from controls. The insulinotropic effect of GIP was significantly reduced, while insulin secretion in response to the GLP-1 receptor agonist Exendin-4 was enhanced in GIPRdn transgenic vs. control pigs. With increasing age, glucose control deteriorated in GIPRdn transgenic pigs as shown by reduced oral and intravenous glucose tolerance due to impaired insulin secretion. Importantly, β-cell proliferation was reduced by 60% in 11-week-old GIPRdn transgenic pigs, leading to a reduction of β-cell mass by 35% and 58% in 5-month-old and 1-1.4-year-old transgenic pigs compared to age-matched controls, respectively.

Conclusions: The first large animal model with impaired incretin function demonstrates an essential role of GIP for insulin secretion, proliferation of β-cells, and physiological expansion of β-cell mass.

Footnotes

    • Received April 8, 2009.
    • Accepted February 10, 2010.
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  1. Diabetes
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