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Authors

  • Gault, Victor
  • Irwin, Nigel
  • Green, BD
  • McCluskey, Janie
  • Greer, B
  • Bailey, CJ
  • Harriott, P
  • O'Harte, Finbarr
  • Flatt, Peter

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Chemical ablation of gastric inhibitory polypeptide receptor action by daily (Pro(3))GIP administration improves glucose tolerance and ameliorates insulin resistance and abnormalities of islet structure in obesity-related diabetes

Date

01-08-2005

Abstract

Glucose-dependent insulinotropic polypeptide (gastric inhibitory polypeptide [GIP]) is an important incretin hormone secreted by endocrine K-cells in response to nutrient ingestion. In this study, we investigated the effects of chemical ablation of GIP receptor (GIP-R) Action on aspects of obesity-related diabetes using a stable and specific GIP-R antagonist, (Pro 3)GIP. Young adult ob/ob mice received once-daily intraperitoneal injections of saline vehicle or (Pro(3))GIP over an 11-day period. Nonfasting plasma glucose levels and the overall glycemic excursion (area under the curve) to a glucose load were significantly reduced (1.6-fold; P < 0.05) in (Pro 3)GIP-treated mice compared with controls. GIP-R Ablation also significantly lowered overall plasma glucose (1.4-fold; P < 0.05) and insulin (1.5-fold; P < 0.05) responses to feeding. These changes were associated with significantly enhanced (1.6-fold; P < 0.05) insulin sensitivity in the (Pro3)GIP-treated group. Daily injection of (Pro3)GIP reduced pancreatic insulin content (1.3-fold; P < 0.05) and partially corrected the obesity-related islet hypertrophy and beta-cell hyperplasia of ob/ob mice. These comprehensive beneficial effects of (Pro3)GIP were reversed 9 days after cessation of treatment and were independent of food intake and.. body weight, which were unchanged. These studies highlight a role for GIP in obesity-related glucose intolerance and emphasize the potential of specific GIP-R antagonists as a new class of drugs for the alleviation of insulin resistance and treatment of type 2 diabetes.