Effects of nickel on liver and bone metabolic functions, biochemical and histopathological responses in common carp (Cyprinus carpio)

This study is performed to investigate the effects of water-borne Ni2+ on common carp (Cyprinus carpio) liver and bone metabolisms. Fish (N=60; 184.40±18.56g) were exposed to background concentrations of Ni2+ (based on measured LC50-96h: 5.820 mg/L), including 0.058, 0.291, 0.580, 1.750, 2.910 mg/L for 30 continuous days. Ni2+-exposed fish showed a rising trend in the case of serum aspartate transaminase (AST). Serum alkaline phosphatase (ALP) elevated (p<0.05) in all Ni2+ treatments. Serum total protein, globulin, and albumin showed a transient reduction in 0.058, 0.291 and 0.580 mg/L Ni2+ exposures (p<0.05). Although serum calcium level did not change significantly, serum inorganic phosphorus was elevated (p<0.05) in 0.580 mg/L Ni2+. Bone isoenzyme of ALP observed in higher levels in all Ni2+ treatments than the control group (p<0.05). Pathological damages, such as focal necrosis, pycnosis and cytoplasm degeneration were observed in liver tissues of Ni2+-exposed fish. A higher number of osteocytes as well as osteoclasts in bone of Ni2+-exposed fish revealed dual effect of this metal in the case of bone metabolism. Generally, low level of nickel had no significant effect on metabolic parameters of liver and bone while highest nickel treatment had adverse effects, reflecting dual effects of this metal on carp.