Effects of Cu2+ and Pb2+ on different fish species: Liver cytochrome P450-dependent monooxygenase activities and FTIR spectra

The effects of Cu2+-sulfate and Pb2+-acetate on carp (Cyprinus carpio L.), silver carp (Hypopthalmichtys molitrix V.) and wels (Silurus glanis L.) were studied. The liver microsomal Cyt P450 content, the EROD, ECOD and APND monooxygenase activities were measured. In vivo treatment with 1 mg L− 1 Cu2+ significantly elevated the activities of these enzymes and Cyt P450 content in silver carp livers. The high-dose Cu2+ treatment (10 mg L− 1) on silver carp caused two-fold higher induction in the P450 dependent monooxygenase isoensymes than in wels. Although the 2 mg kg− 1 treatment with Pb2+ in carp elevated significantly the P450 content, the EROD isoenzyme activities were significantly decreased after 1 day, showing the destructive effect of metal ion on the enzyme system. In vitro, Cu2+ and Pb2+ decreased the Cyt P450 content in the carp liver microsomes and the absorption peak shifted to higher wavelength. Fourier Transform Infrared (FTIR) spectroscopy was used to detect the damaging effects of the heavy metals. According to the inhibitory potency to Cu2+, the most sensitive isoenzyme was the EROD in wels, the least was the silver carp's isoenzyme. The investigated fish P450 isoenzymes showed, that the Cu2+ was a stronger inhibitor than Pb2+.