Induction of oxidative stress and antioxidant defenses in the livers of sea trout, Salmo trutta L., with ulcerative dermal necrosis

The aim of this study was to investigate the lipid peroxidation (thiobarbituric acid reactive substance content) and oxidative modified protein levels (stable 2.4-dinitrophenyl hydrazine derivates of the carbonyl groups), and antioxidant defense system (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase activity, and total antioxidative activity) in livers of males and females from a control group (healthy specimens) and a group of sea trout, Salmo trutta L., affected by ulcerative dermal necrosis (UDN). Ulcerative dermal necrosis tends to induce protein oxidative destruction and negatively affects the livers of infected trout by initiating oxidative stress. UDN-affected males are characterized by higher expressed oxidative-modified protein levels in their livers compared to healthy specimens. Our results indicate there is a connection between the level of oxidative stress and antioxidant defenses in the livers of trout with UDN. Increased levels of protein oxidation and modified activities of antioxidant defenses caused declines in total antioxidant activity in the livers of UDN-affected females. The glutathione-mediated antioxidant defense system and endogenous catalase play critical roles in the intracellular antioxidant defenses under UDN-induced oxidative stress.