Pro-oxidant and antioxidant response elicited by CH₂Cl₂, CHCl₃ and BrCHCl₂ in Goodea gracilis using non-invasive methods

The development of non-invasive methods aimed to evaluate the effects of many toxicants is required. Although there are some studies conducted in successful ways, a lack of information prevails especially for those substances that could be formed autochthonously in the water bodies, such as halomethanes (HMs). In this study, induction of pro-oxidant forces (CH₂O, O₂, H₂O₂), oxidative stress (TBARS, RCO) and antioxidant defenses (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in the skin mucus layer regarding to the liver of Goodea gracilis exposed to CH₂Cl₂, CHCl₃ and BrCHCl₂ were evaluated, in addition to the hepatic cytochrome P450 (CYP 2E1) and glutathione S-transferase theta (GSTT) activities. Regardless of the implicit toxicity involved in the bioactivation of the HMs, carried out by the CYP 2E1 and GST, it was noticeable that this process induces oxidative stress. The usefulness of the mucus layer for the evaluation of the oxidative stress response was demonstrated, despite some peculiar characteristics concerning induction of oxidative stress in liver and skin mucous layer. However, for the understanding of the induction of reactive oxygen species in both targets it is essential to evaluate the activity of antioxidant defenses; otherwise the interpretation of toxic effects elicited by HMs would be erroneous. In the skin mucus layer, lower activities of the enzymes involved in antioxidant defense than in liver were observed. The evaluation of the biomarkers in the skin mucus layer involved in the oxidative stress is useful due the consistent response regarding to concentration of the HMs.