Time Course Effects of Dietary Vitamin D on Diethylnitrosamine-Induced Oxidative Stress in Rat Kidney

Abstract

The kidney is an essential organ known for its role in the endogenous elimination of the body's waste products. The kidney also functions in metabolic activities, including vitamin D metabolism. Other kidney functions involves transport and reabsorption of solutes exposing the organ to oxidative stress induced by toxicants. The study, therefore, examined the effects of dietary vitamin D (Vit D) on diethylnitrosamine (DEN)-induced oxidative stress in rat kidney. Eighty-four male Wistar rats were divided into four groups of 21 animals each, and 30 mg/kg body weight of DEN was administered twice weekly for 11 weeks. Each group received either DEN + Vit D deficient diet or Vit D diet, and normal saline + Vit D deficient diet, or a Vit D diet. Oxidative stress/antioxidant parameters, including Glutathione S-transferase (GST), Thiobarbituric acid reactive substances (TBARS), Glutathione (GSH), Superoxide dismutase (SOD), and Nitric Oxide (NO), were measured using spectrophotometric methods after weeks 6, 12, and 20. Results showed an early significant (p < 0.05) increase in GST activity with DEN exposure, which was significantly (p < 0.05) reduced with the Vit D diet. In the DEN + Vit D deficient diet group, a significant (p < 0.05) decrease in nephrotic NO concentration and increased SOD activities were observed in the 20th week of evaluation. Nephrotic tubular hyalinization and inflammation were noticeable after 11 weeks of DEN exposure from histopathology results. The findings showed that dietary Vit D could, in part, alleviate kidney oxidative stress effects through oxidative stress modulation.