Dietary trans-cinnamaldehyde improves oxidative stress response of channel catfish (Ictalurus punctatus) following Edwardsiella ictaluri infection

Abstract

Commercial channel catfish (Ictalurus punctatus) is an economically valuable agricultural commodity in the United States, which suffers heavily from bacterial pathogens including Edwardsiella ictaluri. Our previous study revealed that dietary trans-cinnamaldehyde (TC) reduces catfish mortality after E. ictaluri infection, but there is limited knowledge of the effect of TC on the antioxidant defense system in catfish. In this study, we aimed to investigate the response of the catfish antioxidant defense system following TC feeding as well as E. ictaluri infection. In the first experiment, catfish fingerlings were fed with a basal diet or a basal diet supplemented with TC (20 mg/kg diet) for 10 days, and the level of five oxidative stress biomarkers were measured in the hepatic tissue. Compared with the control group, superoxide dismutase (SOD) activity was increased significantly and the malondialdehyde (MDA) concentration decreased significantly (P < 0.001) in hepatic tissue of catfish that were fed a TC-supplemented diet. Whereas activities of catalase (CAT) and reduced glutathione (GSH) as well as nitric oxide (NO) concentration did not show significant differences between TC and control groups. In the second experiment, catfish fingerlings were fed a TC-supplemented or normal diet followed by infection with E. ictaluri, and the activities of oxidative biomarkers were measured on 1, 6, and 14-days post-infection (dpi). Significant (P < 0.001) increases in CAT, SOD, and GSH activities were observed in catfish fed TC when compared with those fish fed a normal diet on 1, 6, and 14 dpi. A significant (P < 0.001) decrease in NO and MDA concentrations were found in catfish that received a TC diet compared to the control group at 1, 6, and 14 dpi. In conclusion, dietary TC improved the oxidative stress response in catfish following E. ictaluri challenge. These results provide information regarding the mechanisms by which TC provides protection against E. ictaluri infection.