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This Article Full Text Full Text (PDF) All Versions of this Article: 295/1/E110    most recent 00258.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Lastra, G. Articles by Sowers, J. R. PubMed PubMed Citation Articles by Lastra, G. Articles by Sowers, J. R.

Low-dose spironolactone reduces reactive oxygen species generation and improves insulin-stimulated glucose transport in skeletal muscle in the TG(mRen2)27 rat

Departments of ¹Internal Medicine and ²Medical Pharmacology and Physiology, Divisions of ³Endocrinology and ⁴Nephrology, and ⁵Diabetes and Cardiovascular Center of Excellence, University of Missouri School of Medicine, Columbia; ⁶Harry S. Truman Veterans Affairs Medical Center, Columbia, Missouri; and ⁷Wake Forest University School of Medicine, Winston-Salem, North Carolina

Submitted 24 April 2007 ; accepted in final form 23 April 2008

Renin-angiotensin-aldosterone system (RAAS) activation mediates increases in reactive oxygen species (ROS) and impaired insulin signaling. The transgenic Ren2 rat manifests increased tissue renin-angiotensin system activity, elevated serum aldosterone, hypertension, and insulin resistance. To explore the role of aldosterone in the pathogenesis of insulin resistance, we investigated the impact of in vivo treatment with a mineralocorticoid receptor (MR) antagonist on insulin sensitivity in Ren2 and aged-matched Sprague-Dawley (SD) control rats. Both groups (age 6–8 wk) were implanted with subcutaneous time-release pellets containing spironolactone (0.24 mg/day) or placebo over 21 days. Systolic blood pressure (SBP) and intraperitoneal glucose tolerance test were determined. Soleus muscle insulin receptor substrate-1 (IRS-1), tyrosine phosphorylated IRS-1, protein kinase B (Akt) phosphorylation, GLUT4 levels, and insulin-stimulated 2-deoxyglucose uptake were evaluated in relation to NADPH subunit expression/oxidase activity and ROS production (chemiluminescence and 4-hydroxy-2-nonenal immunostaining). Along with increased soleus muscle NADPH oxidase activity and ROS, there was systemic insulin resistance and reduced muscle IRS-1 tyrosine phosphorylation, Akt phosphorylation/activation, and GLUT4 expression in the Ren2 group (each P < 0.05). Despite not decreasing blood pressure, low-dose spironolactone treatment improved soleus muscle insulin signaling parameters and systemic insulin sensitivity in concert with reductions in NADPH oxidase subunit expression/activity and ROS production (each P < 0.05). Our findings suggest that aldosterone contributes to insulin resistance in the transgenic Ren2, in part, by increasing NADPH oxidase activity in skeletal muscle tissue.

Ren2 rat; mineralocorticoid receptor blockade