INCREASED OXIDATIVE STRESS AND ALDOSTERONE LEVELS IN AGED WISTAR KYOTO AND SPONTANEOUSLY HYPERTENSIVE RATS: EFFECT OF FOOD RESTRICTION: PP.30.201

Abstract

The aim of this study was to investigate on the relationship between the oxidative stress status, aldosterone plasma levels and renal MR functionality in 13- and 84-week old Wistar Kyoto fed ad-libitum (WKY-Ad), or submitted to food restriction (WKY-FR) and spontaneously hypertensive (SHR) rat. Five-week old male WKY and SHR were obtained from Harlan-Interfauna Ibérica. WKY and SHR were fed ad-libitum until 13 or 84 weeks of age. From 5 weeks of age, the food intake of WKY-FR was restricted to 85% of the mean intake of WKY-Ad until 13 or 84 weeks of age. H2O2 levels were measured fluorometrically using the Amplex Red Hydrogen Peroxide Assay kit. Urinary malondialdehyde (MDA) content was analyzed in WKY-Ad, WKY-FR and SHR. All biochemical assays were performed by Cobas Mira Plus analyzer. WKY-Ad became obese with aging; body weight gain from 13 to 84 weeks of age in WKY-Ad was twice that in SHR. FR resulted in a 20% body weight reduction at the age of 84 weeks. Renal H2O2 levels increased significantly with age in both WKY-Ad and SHR. FR significantly reduced H2O2 levels when compared with age-matched WKY-Ad. Furthermore, lipid peroxidation was significantly increased in 84 week old WKY-Ad and SHR, however, FR had no effect on urinary MDA levels. Aldosterone plasma levels were significantly higher in 13-week old SHR than those observed in age matched WKY-Ad, but no differences were found between 84-week old WKY and SHR. WKY-FR at 84 weeks of age had reduced aldosterone plasma levels in comparison to age-matched WKY-Ad. The Na+/K+ urinary ratio, an indirect index of MR functionality, was significantly decreased in aged WKY-Ad and SHR. FR increased the UNa+/K+ ratio at 13 weeks of age but had no effect at 84 weeks of age. Aged WKY and SHR develop exacerbated renal oxidative stress accompanied by increased aldosterone plasma levels and MR functionality which are attenuated by weight loss in WKY.