Effects Of Dietary Glutathione Supplementation On Immunity,antioxidant Capacity And Relieving Hepatopancreatic Injury Of Chinese Mitten Crab,eriocheir Sinensis

Eriocheir sinensis(E.sinensis)is favored by consumers for its unique flavor and high nutritional value,and its yield increases year by year.However,the increasing of breeding density resulted in the frequent occurrence of diseases and the deterioration of water quality of E.sinensis,among which bacterial disease was the main disease.However,the deterioration of water quality led to the outbreak of cyanobacteria in the high temperature period,and Microcystin-LR(MC-LR)induced hepatopancreas injury in E.sinensis.The disease resistance of lower crustaceans of E.sinensis is poor,so it is very important to add non-nutritive additives to the feed to improve its disease resistance.Add antioxidant become hot spot in the aquaculture in recent years.In this study,Glutathione(GSH)was as an antioxidant,E.sinensis was as experimental animals,to explore the diet adding GSH on growth of E.sinensis,nonspecific immunity and anti-oxidation function,and under the stress of lipopolysaccharide(LPS)and MC-LR,to explore GSH in E.sinensis alleviate the impact of the oxidative stress and cell apoptosis.This experiment is divided into the following three aspects:Experiment 1 Dietary reduced glutathione supplementation can improve growth,antioxidant capacity,and immunity on Chinese mitten crab,Eriocheir sinensisIn this study,to understand the effects of GSH as an exogenous feed regulator on the growth,immunity and antioxidant of E.sinensis,crabs were fed GSH(0,300,600,900 and 1200 mg/kg)for 10 weeks.The results showed that when the GSH content in the feed increased from 0 to 900 mg/kg,the weight gain rate and survival rate were significantly increased.The results showed that dietary addition of 600 or 900 mg/kg of GSH could improve the antioxidant capacity(Superoxide dismutase(SOD),Glutathione peroxidase(GSH-Px)activity and GSH content)and immunity(Total protein(TP)content,Albumin(Alb)content,Globulin(Glb)content,Myeloperoxidase(MPO)activity,Complement component 3(C3)content,Complement component 4(C4)content,Alkaline phosphatase(AKP),Acid phosphatase(ACP)and lysozyme(LZM)activity)of E.sinensis.At the same time,the expression of antioxidant and immune genes(Cytosolic manganese superoxide dismutase(CYTMnSOD),Mitochondrial manganese superoxide dismutase(MTMnSOD),Cu-ZnSOD,LZM and GSH-Px)was increased and the expression of immune cytokines(Toll-like receptor 1(TLR1),Toll-like receptor 1(TLR2),Myeloid differentiation factor 88(Myd88),Dorsal)was reduced,leading to better health.Experiment 2 Repair of hepatopancreatic injury induced by LPS induced by dietary glutathione in Chinese mitten crab,Eriocheir sinensisDeteriorating water conditions lead to frequent bacterial diseases in E.sinensis.The bacterial diseases are mainly caused by the oxidative stress induced by the action of LPS on cells from bacteria.In this study,to further understand the anti-disease effect of GSH on crabs,the crabs were fed a diet(with 0,300,600,900,and 1200 mg/kg GSH diets)for 3 weeks,and then injected with LPS(400μg/kg).After 6 hours,hepatopancreas samples were taken.Dietary addition of 600 and 900 mg/kg GSH not only increased the content of GSH in hepatopancreas,but also increased the activity and mRNA expression of SOD,GSH-Px and GSH-S-transferase(GST)(p<0.05).Histopathological and submicroscopic analysis showed that dietary addition of 600 or 900 mg/kg GSH significantly alleviated LPS-induced crab injury and reduced the level of reactive oxygen species and apoptosis in hepatopancreas.Dietary addition of 600 or 900 mg/kg GSH significantly reduced the activity of caspases-3,-8,and-9,and inhibited the relative expression of caspase-3 and-8,but increased the expression of B cell lymphoma-2(bcl-2)and B cell lymphoma-2-related X inhibitator(bax inhibitator).Dietary addition of 600 or 900 mg/kg GSH further significantly reduced relative protein levels of caspase-3,-8,-9,and bax in LPS-stressed crabs and upregulated relative protein levels of bcl-2.Overall,our results suggest that dietary supplementation of 600 or 900 mg/kg GSH can enhance the antioxidant capacity and anti-apoptosis mechanism of crabs after LPS injection.Experiment 3 Hepatopancreatic detoxification of Eriocheir sinensis under MC-LR stress by dietary glutathione supplementationMC-LR contained in cyanobacteria is toxic.GSH has been shown to have a detoxification effect on MC-LR,but it has not been studied in E.sinensis.In this study,hepatopancreatic sampling was conducted at 0,6 and 12 h after 10 weeks of acute MC-LR challenge injection(basal diet with 0,300,600,900 and 1200 mg/kg GSH).Results show that the diet to add 600 or 900 mg/kg GSH can enhance antioxidant capacity(SOD,GSH-Px activity and GSH content rised)and immune activity of ACP and AKP after MC-LR injection,and improve the antioxidant and immune related gene expression,and thus thus providing a theoretical basis for the application of dietary GSH in E.sinensis.