Effects of Green Wavelength Light on Antioxidant Responses in Olive Flounder Paralichthys olivaceus Exposed to Starvation and Re-feeding

Abstract

An understanding of responses to antioxidant enzymes in different starvation and refeeding protocols is critical in the aquaculture of fish. This study investigated the effect of green wavelength (520 nm) on the antioxidant response of the olive flounder, Paralichthys olivaceus, exposed to different starvation and re-feeding protocols for 4 weeks. We analyzed mRNA expression of peroxisome proliferator-activated receptor alpha ( PPARa) and the levels of plasma glucose, superoxide dismutase (SOD), and catalase (CAT), hydrogen peroxide (H2O2), and lipid peroxidation (LPO). Furthermore, we performed immunohistochemistry staining (IHC) to observe the SOD expression in the liver visually. We found that expression and activity of antioxidant enzymes (PPARa, SOD, and CAT), as well as plasma H2O2 and LPO levels, increased significantly during the starvation period compared to the fed group. However, antioxidant enzymes and oxidative stress increased during the fasting period were significantly decreased during the re-feeding period, especially in the group irradiated with green light. Also, using IHC staining, we found that green light and different feeding protocols affected the expression of SOD in the liver. These findings show that irradiation with green light was effective at alleviating the increased oxidative stress during starvation and re-feeding periods in olive flounder.yy