Among the key components of the antioxidant defence system
are enzymes that can be induced by oxidative stress. These enzymes
include superoxide dismutase (SOD; EC1.15.1.1), catalase (CAT;
EC1.11.1.6) and glutathione peroxidase (GSH-Px; EC1.11.1.9), and
their reactions with oxyradicals have been studied in fish [10]. It is
thought that the antioxidants of fish may be useful biomarkers of
exposure to aquatic pollutants [11]. Pesticides may cause oxidative
stress leading to the generation of free radicals and alterations in
antioxidants or free oxygen radical scavenging enzyme systems
[12]. Lipid peroxidation has been suggested as one of the molecular
mechanisms involved in pesticide-induced toxicity [13].