Prooxidant and antioxidant sex-linked response and its relationship to mixed oxidase function enzymes in liver of Ameca splendens, an endangered goodeid fish exposed to PCBs

The butterfly split-fin goodeid Ameca splendens is an endemic and endangered Mexican fish species whose habitat is polluted with persistent xenobiotics, such as polychlorinated biphenyls (PCB). These toxicants are potent inducers of mixed oxidase function (MOF) enzymes including cytochrome P450 (CYP450) and other cytoplasmatic enzymes such as alcohol dehydrogenase (ADH). During PCB biotransformation by MOF isoenzymes, reactive oxygen species (ROS) are generated that are able to produce oxidative stress. However, in A. splendens the linkage between the induction of MOF and the oxidative stress response produced by PCB remains unknown. To clarify the possible relationships between the induction of CYP450 and the ADH activity with the oxidative stress response, the induction of lipid peroxidation (LPOX) and superoxide dismutase (SOD) and the catalase (CAT) activity produced by exposure to PCB mixture were examined for 1, 2, 4, 8, or 16 days. In both genders, the response pattern induced by PCB was different. PCB induced LPOX and CAT, while a decrease in SOD activity was observed. It was not possible to explain the toxicity of PCB based on toxic equivalency factors. The response seems to be dependent on several factors including species, gender, and interaction of PCB in the mixture. A correlation was found between LPOX and ADH but not with CYP450. A correlation between ADH and SOD was observed in both genders but not with CAT. In males, a correlation between CYP450 with SOD was detected. Data suggest that the redox process involving ADH possesses a dual function, whereby in an indirect manner there is induction of LPOX, which generates energy for SOD and CYP450.