Physiological and Oxidative Stress Biomarkers in the Freshwater Nile Tilapia, Oreochromis Niloticus L., Exposed to Sublethal Doses of Cadmium

This study was designed to investigate the possibility of cadmium (Cd) to induce oxidative stress and biochemical perturbations in Nile tilapia liver and gills and the role of Vitamin C (Vit. C) in alleviating its toxic effects. Nile tilapia fish were randomly divided into four groups of thirteen each, group one served as control without any treatment, group two exposed to Cd (5mg/liter water), group three supplemented with vitamin C (Vit.C) (500mg/kg diet), and group four exposed to Cd plus Vit. C. The exposure to Cd caused increase in Liver aminotransferases (AST and ALT), elevation in lipid peroxidation (LPO), activity of catalase (CAT) enzyme, and the activity of glutathione S-transferase (GST). The urea and creatinine levels were not affected. However, reduction in the activity of glutathione peroxidase (GPx) was observed. An increase in reduced glutathione (GSH) content was also observed and in gills there were no significant changes in LPO, antioxidant enzymes activity and GSH level. Vit.C supplementation in Cd-induced oxidative stress of Nile tilapia maintained Liver AST and ALT near normal level and modulated LPO, CAT, GST, GPx and GSH level in liver. It is concluded that Vit.C scavenges reactive oxygen species and render a protective effect against Cd toxicity.