Modulated expression and enzymatic activities of Darkbarbel catfish, Pelteobagrus vachelli for oxidative stress induced by acute hypoxia and reoxygenation.

Large changes in oxygen availability in aquatic environments, ranging from anoxia through to hyperoxia, can lead to corresponding wide variation in the production of reactive oxygen species (ROS) by fish with aquatic respiration. In order to evaluate the effects of hypoxia and reoxygenation on oxidative stress in fish, the mRNA and protein expression of SODs (Cu/Zn-SOD and Mn-SOD) as well as indices (CP, LPO and MDA) and enzymatic activities (SOD, CAT, GPx, GR and GST) were analyzed in liver and brain tissues of Pelteobagrus vachelli. Predominant expression of PvSOD2 was detected in heart, brain, and liver. In contrast, PvSOD1 was highly expressed in liver. Based on the expression patterns of above parameters, we inferred that brain tissue of P. vachelli under 0.7 mg/L degree of acute hypoxia condition could experience hypometabolic states or no suffering stress, but brain tissue has effective mechanisms to minimize or prevent oxidative stress during the transition from hypoxia to reoxygenation. Our results also demonstrated an increased expression of SODs and enzymatic activities for oxidative stress in liver under hypoxic conditions, which supports the hypothesis that anticipatory preparation takes place in order to deal with the encountered oxidative stress during the recovery from hypoxia as proposed by M. Hermes-Lima. Therefore, this study will provide a clue to better understand the action mode of antioxidant genes and enzymes under oxidative stress in fish.