It is unknown whether the flavonoid rutin can protect the silver catfish liver in response to exposure to a known stressor, such as the prophylactic usage of the antimicrobial agent oxytetracycline. Thus, the current study aimed to assess the effect of rutin incorporation into the silver catfish diet formulation on oxytetracycline-induced liver oxidative stress and apoptosis. Fish were split into four groups as follows: control, rutin (1.5 g kg diet-1), oxytetracycline (0.1 g kg diet-1) and rutin+oxytetracycline (1.5 g kg diet-1 and 0.1 g kg diet-1, respectively). After two weeks of feeding with the different diets (standard, rutin-, oxytetracycline and rutin+oxytetracycline-added diets), fish were euthanized to collect the liver. Although the rutin-added diet was unable to recover glutathione peroxidase activity, ascorbic acid and reduced glutathione (GSH) levels, which were depleted due to oxytetracycline consumption, it markedly diminished the oxidized glutathione (GSSG) content, thus decreasing the GSSG to GSH ratio, an important index of oxidative stress. It also increased glutathione reductase and markedly augmented glucose-6-phosphate dehydrogenase activities, which were declined after oxytetracycline ingestion. Furthermore, the rutin-added diet reestablished superoxide dismutase and catalase activities and reduced lipid peroxidation, nitric oxide and superoxide anion levels as well, all changes resulting from oxytetracycline consumption. Finally, it also prevented oxytetracycline-induced apoptosis through increasing heat shock protein 70 and markedly decreasing high mobility group box 1 and, consequently, reducing cleaved caspase-3 protein levels. Therefore, in conclusion, the incorporation of this flavonoid to the silver catfish diet protected the liver against oxytetracycline-induced liver oxidative stress and apoptosis.
Keywords: Antimicrobial; Fish; Flavonoid; Prophylactic; Stressor.
Copyright © 2020 Elsevier Inc. All rights reserved.