Dietary optimal reduced glutathione improves innate immunity, oxidative stress resistance and detoxification function of grass carp (Ctenopharyngodon idella) against microcystin-LR

The present study reports on the effects of dietary glutathione (GSH) on non-specific immunity, oxidative stress resistance and detoxification in grass carp (Ctenopharyngodon idella) infected with microcystins. Six hundred and thirty juvenile grass carp with initial body weight of (5.10 ± 0.09) g were randomly distributed into six groups with three replicates each and stocked in 18 tanks (35 fish per tank), fed six diets containing graded levels of GSH for 60 days. At the end of the feeding trial, ten fish per tank were selected and injected intraperitoneally with 200 μg/kg body weight (BW) dose of pure microcystin-LR (MC-LR). The results showed that, at 0 h, 24 h of MC-LR injection, with the increase of dietary GSH content, serum lysozyme, alkaline phosphatase (ALP) and complement 3 (C3) levels, the activities and mRNA expression levels of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in liver, and liver GSH content increased first and then decreased (P