Accumulation and effects of copper on detoxification enzyme activities and nonenzyme antioxidants in various tissues of Oreochromis niloticus exposed to copper, copper-calcium and copper-edta complex

In this study, effects of copper on detoxification enzyme activities and nonenzymatic antioxidants and accumulation in tissues of Oreochromis niloticus were investigated in Cu, Cu+EDTA and Cu+Ca mixtures. Fish were exposed to 0.1, 0.5 and 1.0 mg/L Cu and 0.1 mg/L Cu+1.0 mg/L Ca, 0.5 mg/L Cu+5.0 mg/L Ca, 1.0 mg/L Cu+10.0 mg/L Ca and 0.1 mg/L Cu+0.3 mg/L EDTA, 0.5 mg/L Cu+1.5 mg/L EDTA and 1.0 mg/L Cu+3.0 mg/L EDTA mixtures for 7, 14 and 28 days to observe copper accumulation and enzyme activities in tissues.Copper accumulated significantly in all the tissues after exposure to copper for 7, 14 and 28 days. Copper accumulation in the tissues of fish exposed to Cu+EDTA and Cu+Ca mixtures were lower when compared to those exposed to copper only.In tissues of O. niloticus, nonenzymatic antioxidants (total glutathione (tGSH), bilirubin, albumin, transferrin, hemoglobin, haptoglobin, glucose, uric acid) and detoxification enzyme activities like acetylcholinesterase (AChE), glutathione S-transferase (GST) were altered by exposure Cu, Cu+EDTA and Cu+Ca mixtures.In all the concentrations tested, copper caused a decrease in AChE activity in the liver and kidney while it caused an increase in gill and brain tissues. In all concentrations of tested copper caused an increase GST activity in liver and gill and a decrease in brain and kidney tissues of O. niloticus. GSH levels increased in liver, kidney and gill tissues and decreased significantly in brain of the Cu exposed of fish. Cu and Cu+EDTA, Cu+Ca mixtures caused an increase in the levels of bilirubin, albumin, transferrin, hemoglobin, glucose, uric acid and a decrease haptoglobin in blood tissue of exposed fish