Effect of sublethal doses of cadmium on the disposition of zinc and copper elements and liver function in common carp [Cyprinus carpio L.]

ABSTRACT

The present study was carried out to determine the levels of Zn and Cu in various organs and tissues of common carp as well as hepatic asperatate aminotransferase [AST] and alanine aminotransferase [ALT] activities under the effect of low and high doses of cadmium [Cd]. Common carp; Cyprinus carpio L. of an average weight 60-70 g were exposed to sublethal doses of cadmium sulfate [8.75 and 17.5 mg/L] under controlled laboratory conditions. Analyses of the studied fish were carried out at intervals of 7, 15 and 30 days of exposure. The obtained results revealed that, Zn level in liver did not exhibit significant variation in fish exposed to low dose at all exposure periods, while its level in muscle in fish exposed to high dose decreased significantly [P<0.01] after 7 days. On the 15[th] day, Zn level in plasma and kidneys was decreased significantly [P<0.01] in fish subjected to high dose of Cd. Decrease was also recorded in plasma, liver, kidneys and gills in fish exposed to high dose of Cd at the end of experiment. Moreover, Cu level in plasma was increased significantly [P<0.05] in fish after prolonged exposure to high dose of Cd, while hepatic Cu was decreased significantly in fish exposed to low dose of Cd after 30 days. On the 7[th] day, the Cu level in gills of fish exposed to the both doses of Cd was significantly decreased. On the 15[th] and the 30[th] day, Cu reduction was also recorded in kidneys in fish intoxicated with high dose of Cd. The AST activity increased significantly [P<0.01] in fish exposed to high dose of Cd on the 7[th] day, while on the 30[th] day hepatic ALT activity was decreased significantly [P<0.01] in fish exposed to high dose of Cd. On the other hand, the hepatosomatic index [HIS] did not exhibit significant changes