Changes in Lipids, Fatty Acids, Lipid Peroxidation and Antioxidant Defence System During the Early Development of Wild Brown Trout (Salmo trutta)

Generation of radical oxygen species (ROS) is a natural consequence of aerobic metabolism and it becomes more critical during the early development of fish due to the rapid tissue growth resulting in high oxygen consumption. The present study was conducted as the first to evaluate the changes in lipids, fatty acids, lipid peroxidation and antioxidant defense system during the early development of wild brown trout (Salmo trutta). Total lipids dramatically decreased from 9.3% (egg) to 4.3% (swim-up). Docosahexaenoic acid (DHA; 22:6n-3) was the predominant fatty acid in all cases and was preferentially conserved during the early development. Non-enzymatic antioxidant scavengers (vitamin E, C and B1) were abundant in egg and decreased dramatically after hatching while the activities of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD) and glutathione S-transferase (GST) increased at the same circumstance. The lowest malondialdehyde (MDA), lipid peroxidation product, was in unfertilized eggs and eyed-stage embryo while the highest level was observed in yolk-sac larvae. Our overall results suggest that high level of non-enzymatic free radical scavengers detoxify ROS during the embryonic development and elevated antioxidant enzymes take this duty over after hatch, protecting embryo and fry from oxidative stress.