Chronic infusion of angiotensin-(1-7) improves insulin resistance and hypertension induced by a high-fructose diet in rats

Am J Physiol Endocrinol Metab. 2009 Feb;296(2):E262-71. doi: 10.1152/ajpendo.90678.2008. Epub 2008 Nov 11.

Abstract

The current study was undertaken to determine whether Ang-(1-7) is effective in improving metabolic parameters in fructose-fed rats (FFR), a model of metabolic syndrome. Six-week-old male Sprague-Dawley rats were fed either normal rat chow (control) or the same diet plus 10% fructose in drinking water. For the last 2 wk of a 6-wk period of either diet, control and FFR were implanted with subcutaneous osmotic pumps that delivered Ang-(1-7) (100 ng.kg(-1).min(-1)). A subgroup of each group of animals (control or FFR) underwent a sham surgery. We measured systolic blood pressure (SBP) together with plasma levels of insulin, triglycerides, and glucose. A glucose tolerance test (GTT) was performed, with plasma insulin levels determined before and 15 and 120 min after glucose administration. In addition, we evaluated insulin signaling through the IR/IRS-1/PI3K/Akt pathway as well as the phosphorylation levels of IRS-1 at inhibitory site Ser(307) in skeletal muscle and adipose tissue. FFR displayed hypertriglyceridemia, hyperinsulinemia, increased SBP, and an exaggerated release of insulin during a GTT, together with decreased activation of insulin signaling through the IR/IRS-1/PI3K/Akt pathway in skeletal muscle, liver, and adipose tissue, as well as increased levels of IRS-1 phospho-Ser(307) in skeletal muscle and adipose tissue, alterations that correlated with increased activation of the kinases mTOR and JNK. Chronic Ang-(1-7) treatment resulted in normalization of all alterations. These results show that Ang-(1-7) ameliorates insulin resistance in a model of metabolic syndrome via a mechanism that could involve the modulation of insulin signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / drug effects
  • Adipose Tissue / metabolism
  • Angiotensin I / administration & dosage
  • Angiotensin I / pharmacology*
  • Animals
  • Diet*
  • Drug Evaluation, Preclinical
  • Fructose / adverse effects*
  • Fructose / pharmacology
  • Glucose Tolerance Test / veterinary
  • Hypertension / chemically induced*
  • Hypertension / prevention & control*
  • Infusion Pumps
  • Insulin / metabolism
  • Insulin Resistance* / physiology
  • Liver / drug effects
  • Liver / metabolism
  • Male
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / metabolism
  • Peptide Fragments / administration & dosage
  • Peptide Fragments / pharmacology*
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction / drug effects
  • Time Factors

Substances

  • Insulin
  • Peptide Fragments
  • Fructose
  • Angiotensin I
  • angiotensin I (1-7)