Co-administration of Vitamins E and C protects against stress-induced hepatorenal oxidative damage and effectively improves lipid profile at both low and high altitude

Abstract

The aim of this study was to evaluate the effect of co- administration of vitamins E and C on exhaustive exercise induced-stress in regards to hepatorenal function in rats native to low altitude (LA) and high altitude (HA). In both LA and HA areas, native wistar rats of each area were divided into three groups of 6 rats each, which include stress-free control, forced swimming-induced experimental stress and experimental stress plus vitamins E and C treatment. Lipid profile and Liver and kidney functions were assessed in both groups. HA and LA rats exhibit similar baseline levels of liver and kidney function as well as lipid metabolism profiles. However, HA rats showed decreased levels of antioxidant markers with an increased level of lipid peroxidation. Exhaustive swimming exercise induced a significant increase in the liver and kidney function of rats at both altitudes accompanied with a decrease in antioxidants levels. However, the magnitude of change observed in HA rats was more profound. Also at LA, forced swimming exercise resulted in a significant increase in serum total cholesterol (TChol), triacylglycerides (TAG) and high-density lipoprotein cholesterol (HDL). However, in HA rats, forced swimming exercise caused a significant decrease in serum TChol and low-density lipoprotein (LDL), except for HDL levels which were significantly elevated. Pre- and co-administration of vitamins E and C counteracted the induction of liver and/or kidney function by exhaustive exercise, and lowered TChol and LDL levels in rats at either altitude. In conclusion, at native high altitude: kidney and liver function essentially remained stable; response to stress included more profound oxidative damage to liver and kidney tissues as well as augmented deterioration in lipid metabolism compared to low altitude; and combined administration of vitamins E and C protected against observed oxidative stress damage to liver and kidney tissues and preserved lipid metabolism. At low altitude, combined administration of vitamin E and C protected against stress-induced oxidative damage to the liver and kidney and did preserve normal lipid metabolism, except for HDL. These novel findings reveal the pathophysiological changes in the liver function, kidney function and lipid metabolism occurring at high altitude specifically under stress, and demonstrate the efficacy of combined supplementation of vitamins E and C to normalize these changes.

Key words: Exercise, oxidative stress, vitamin E, vitamin C, altitude, rats.