Effects of dietary supplementation with chitosan nanogel on biochemical, antioxidant traits, and resistance to Aeromonas sobria infection, in Cyprinus carpio fingerlings.

This study was designed to evaluate the modulating effect of dietary chitosan nanogel (CHNG) on antioxidant status and hepato-renal function in Cyprinus carpio. Fish were allocated into 4 groups, each group consisted of 45 fish in triplicates, where each replicate was represented by an aquarium (15 fish/ aquarium). The prophylactic feeding trial lasted for sixty days, where fish were placed on either control, CHNG0.5%, 1% or 1.5%-supplemented diet, then, growth performance was assessed and serum samples was collected for biochemical and antioxidant assessments. Afterwards, fish in the four experimental groups were challenged with Aeromonas sobria,where clinical signs and mortalities were monitored over the fourteen-day challenge period. Then, tissue sampling was performed in order to assess the histopathological outcomes and hepatic gene expression in different groups. The outcomes revealed enhancement of hepato-renal function including ALT, AST, ALP, creatinine, and urea in CHNG-supplemented fish. The control group revealed a remarkable increase in tissue malondialdehyde (MDA) levels that was inhibited by CHNG supplementation in a level-related pattern. The activities of reduced glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD) in liver tissue were significantly elevated in a dose-dependent manner in CHNG-supplemented groups. After A. sobria challenge, the hepatic gene expression showed that dietary supplementation with CHNG induced significant down-regulation of apoptosis-related signaling (cERK-1, JNK, P38, and Casp-8) compared with the control group which was challenged with A. sobria and received a basal diet devoid of CHNG. Interestingly, histopathological investigations showed a notable improvement in CHNG-fortified groups relative to the challenged group. Taken together, CHNG-dietary intervention is a potential candidate for enhancing the resistance to A. sobria infection in Cyprinus carpio.