Oxidative stress and antioxidant defense in fish: the implications of probiotic, prebiotic and synbiotics

In fish, like other organisms, the lack of balance between the production of reactive oxygen species (ROS) and antioxidant defense system (so-called oxidative stress) can cause DNA hydroxylation, protein denaturation, lipid peroxidation, apoptosis, and ultimately cell damage. To improve the antioxidant defense capability, different approaches such as the administration of synthetic antioxidants were practiced. During the past years, dietary approaches have been suggested as a promising way of increasing the antioxidant defense activity in different fish and shellfish species. Among them, microbial feed additives (including pre-, pro-, and synbiotics) showed promising effects in terms of affecting antioxidant enzymes activities. Their mechanism of action in influencing the antioxidant system is not fully understood. The present review briefly discussed the antioxidant defense activity in fish, influencing factors with special focus on dietary approaches and microbial feed additives. In addition, the proposed mechanism of action of microbial feed additives on the antioxidant system has been discussed.