Impact of acute arsenic and cadmium exposure on the expression of two haeme oxygenase genes and other antioxidant markers in common carp (Cyprinus carpio).

The aim was to study the effects of cadmium (Cd) and arsenic (As) on haeme oxygenases (HOs) and other oxidative stress biomarkers, and their roles in macromolecule damage in liver and kidney of common carp (Cyprinus carpio L.). HOs play a critical role in the defence system against oxidative damage, producing biliverdin and carbon monoxide with important free radical scavenging properties. However, increased HO activity in haeme degradation may also lead to a pro-oxidant effect through the liberation of Fe-modifying Cd and As toxicity. The response of an organism to exposure to toxic metals is in many cases brought about by changes at the level of gene expression. In this study, the genes ho-1 and ho-2 of the common carp were identified, and the changes in gene expressions were analysed from the aspect of Cd and As accumulation. Both ho-1 and ho-2 are transcriptionally induced by Cd and As, but their inductions differ in time course, dose response and tissue specificity. The expression of ho1 was mostly affected by As, primarily in the liver (45-fold), whereas it was enhanced with higher efficacy by Cd in the kidney (25-fold). The cellular redox status and the damage of lipid molecules were monitored via the ratio of reduced to oxidized glutathione, the levels of H2 O2 and lipid peroxidation, and the activities of superoxide dismutase (SOD) and catalase (CAT).