Effects of Dietary Selenium Nanoparticle Supplementation on Antioxidant Status in Rainbow Trout (Oncorhynchus mykiss)

This study investigates the impact of dietary supplementation with selenium nanoparticles (SeNPs) on key oxidative stress markers in rainbow trout serum. SeNPs were added to the basal fish diet at concentrations of 0, 0.5, 1.0, and 2.0 mg per kg feed, providing 0.72, 1.15, and 2.31 mg Se per kg diet, respectively. Each diet was administered to triplicate groups of rainbow trout with initial mean body weight of 5.54 ± 0.45 g. After a 60-day culture period, significant alterations were observed in glutathione peroxidase (GPX) activities among treatment groups. Particularly, the highest SeNPs treatment group (T3) exhibited a marked increase in GPX activity compared to both T2, T1, and the control. While no significant differences were noted between T1 and T2, as well as T1 and the control, the variations in GPX levels shed light on the nuanced selenium-induced responses in rainbow trout plasma. Glutathione reductase (GR) levels displayed subtle changes with SeNPs supplementation. Notably, the T3 group exhibited a significant increase in GR levels compared to the control. However, no significant differences were observed between T1, T2, and both the control and T3. In contrast, plasma levels of glutathione (GSH) remained unaffected, indicating a stability in this nonenzymatic parameter across all experimental groups. The study also revealed a noteworthy trend in malondialdehyde (MDA) levels, showcasing a decrease with increasing SeNPs concentration in the feed. T2 and T3 treatments displayed significantly lower MDA levels compared to the control, with T3 exhibiting the lowest values. Although T1 did not exhibit significant differences from the control and T2, the overall trend suggests a potential antioxidant effect of SeNPs on rainbow trout plasma. Both T2 and T3 demonstrated an increase in final body weight and condition factor compared to the control. However, T1 did not display any differences with the control or the other two treatment groups. In summary, this research elucidates the complex interplay between SeNPs supplementation and oxidative stress markers in rainbow trout, providing valuable insights into the modulation of antioxidant defenses in aquatic organisms.