Irbesartan restores the in-vivo insulin signaling pathway leading to Akt activation in obese Zucker rats
- 1 August 2006
- journal article
- research article
- Published by Ovid Technologies (Wolters Kluwer Health) in Journal of Hypertension
- Vol. 24 (8), 1607-1617
- https://doi.org/10.1097/01.hjh.0000239297.63377.3f
Abstract
Angiotensin II (AII) has been shown to contribute to the pathogenesis of hypertension and insulin resistance. In addition, the administration of selective AII type 1 receptor blockers has been shown to improve insulin sensitivity. However, only a few studies have addressed the molecular mechanisms involved in this association. Furthermore, in a previous study we illustrated that obese Zucker rats (OZR) present increased serine 994 (Ser994) phosphorylation of hepatic insulin receptor, and this event seems to be implicated in the regulation of the intrinsic IRK in this model of insulin resistance. We examined the effects of chronic treatment with irbesartan (50 mg/kg a day for 6 months) on the hepatic insulin signaling system of OZR. The extent of phosphorylation of several components of the insulin signaling system was assessed by immunoprecipitation, followed by immunoblotting with phosphospecific antibodies. In addition, liver AII levels and fat deposits were determined by immunohistochemistry and Oil red O, respectively. OZR displayed a marked attenuation in the in-vivo phosphorylation of several components of the insulin signaling pathways in the liver, together with significantly higher hepatic AII levels and hepatic steatosis when compared with lean Zucker rats. We found that in the livers of OZR long-term administration of irbesartan is associated with: (i) increased insulin-stimulated insulin receptor tyrosine phosphorylation; (ii) decreased insulin receptor Ser994 phosphorylation; (iii) augmented insulin receptor substrate (IRS) 1 and 2 abundance and tyrosine phosphorylation; (iv) augmented association between IRS and the p85 regulatory subunit of phosphatidylinositol 3-kinase; (v) increased insulin-induced Akt phosphorylation; and (vi) decreased hepatic steatosis. The present study provides substantial information that demonstrates that long-term selective AII blockade by irbesartan improves insulin signaling and is associated with decreased insulin receptor Ser994 phosphorylation in the liver of a representative animal model of the human metabolic syndrome.This publication has 48 references indexed in Scilit:
- Why blockade of the renin–angiotensin system reduces the incidence of new-onset diabetesJournal of Hypertension, 2005
- Angiotensin II Type-1 Receptor Blocker Valsartan Enhances Insulin Sensitivity in Skeletal Muscles of Diabetic MiceHypertension, 2004
- Insulin-Sensitizing Effects of TelmisartanDiabetes Care, 2004
- Insulin signalling and the regulation of glucose and lipid metabolismNature, 2001
- Selective Angiotensin II Receptor Antagonism Reduces Insulin Resistance in Obese Zucker RatsHypertension, 2001
- Recent Advances in Our Understanding of Insulin Action and Insulin ResistanceDiabetes Care, 2001
- Obesity and insulin resistanceJCI Insight, 2000
- Loss of Insulin Signaling in Hepatocytes Leads to Severe Insulin Resistance and Progressive Hepatic DysfunctionMolecular Cell, 2000
- The effects of an angiotensin-converting enzyme inhibitor and an angiotensin II receptor antagonist on insulin resistance in fructose-fed ratsAmerican Journal of Hypertension, 2000
- Hypertension and Associated Metabolic Abnormalities — The Role of Insulin Resistance and the Sympathoadrenal SystemThe New England Journal of Medicine, 1996