Effects Of Taurine On The Antioxidant Capacity Of Grouper (Epinephelus Coioides)

1.Effects of taurine levels on growth performance and antioxidant capacity of grouper(Epinephelus coioides).A 56 d feeding trial was conducted to determine the effects of dietary taurine on growth performance of grouper.Four diets were formulated to contain 0,0.5%,1% and 1.5% taurine.Survival rate,weight gain rate,feeding rate,feed efficiency,specific growth rate and condition factor were measured to determine the state of growth performance.The results showed that addition of taurine in diets could significantly promote growth performance of grouper.When fed the taurine-deficient diet,grouper exhibits poor growth performance in comparison with fish fed other taurine-added diets.The DFI increased with the increase of taurine levels,the highest DFI was observed in fish fed diet contain 1% taurine(P<0.05).FE showed the same trends as DFI.WGR and SGR increased from 0-1% taurine,then decreased from 1%-1.5% taurine level,and highest values were found in fish fed 1% taurine diet.Therefore,the appropriate supplemation of taurine in diet for grouper growth is 1%The addition of taurine could significantly increase T-AOC,SOD,CAT,GSH-Px activity and decrease MDA content.Fish fed 1% taurine diet showed the best capacity of antioxidant and removing lipid peroxidation product compared with those fed other diets(P<0.05).This is consistent with the result of growth performance.Thus the appropriate addition level of taurine for the grouper on growth and anti-oxidation ability of the grouper is 1%.2.Establishment of carbon tetrachloride oxidative damage model of primary cultured hepatocytes of grouper(Epinephelus coioides).In this study,the model of carbon tetrachloride oxidative damage was established by using CCl4 as oxidative damage poisoning.The different concentrations of CCl4(4,8,16 mM)were studied at different time(2,4,8 h)to learn the effect of oxidative damage in vitro hepatocytes.Liver cell vability were measured by MTT assay,the activities of GPT,GOT and LDH and the activities of antioxidant enzymes(SOD,CAT,GSH-Px,MDA)were determined in the supernatant of hepatocytes.The results showed that CCl4 decreased the cell viability,but the difference were not significantly at8 mM and 4mM(P>0.05),8 mM was higher than that of 16 mM(P<0.05).The decrease of liver cell viability in 8h was significantly lower than that of CCl4 for 4 hours(P<0.05).The release of GPT,GOT and LDH could significantly increased at 8 mM for 4 h(P<0.05).8 mM CCl4 couldsignificantly decrease the activity of SOD and CAT(P<0.05),and significantly increase the content of MDA(P<0.05).Therefore,8m M can be used as the best damage concentration of CCl4 oxidative damage model,CCl4 for 4 h can be used as the experimental time for the injury experiment,as the experimental basis for the protection of taurine.3.Protective effects of taurine on oxidative damage of primary cultured hepatocytes of grouper(Epinephelus coioides).In this study,the CCl4 hepatocyte oxidative damage model was used to pre-protect and repair the damaged hepatocytes of the grouper.Taurine is added in three different ways(Taurine Pretreatment: CCl4 was added before adding taurine;Taurine before and after treatment: CCl4 was added before and after adding taurine;Taurine post-treatment: CCl4 added after adding taurine),Three different concentrations of taurine were added to each mode of action: 5 mM,10 m M,15 m M.we also set up a blank control,CCl4 control,taurine control.Each treatment takes the same time.The protective effect of taurine on the hepatocytes of grouper was studied by measuring the activity of hepatocytes,the function of hepatocytes,the activities of antioxidant enzymes and the m RNA expression of antioxidant enzymes in culture supernatants.In order to investigate the protective effect of taurine on hepatocytes in grouper in vitro,and find the best mode of action and the optimum concentration.The results showed that the addition of taurine significantly increased the viability of hepatocytes(P<0.05).Taurine pretreatment group and taurine before and after treatment group got the highest cell vability at 10 mM,while the taurine post-treatment group was the highest at 15 mM.Taurine pretreatment group and taurine before and after treatment group could significantly inhibit the activity of GPT,GOT and LDH in liver cells at 10 mM taurine concentration(P<0.05).When the concentration of taurine was 15 m M,GPT?GOT?LDH activity was significantly decreased(P<0.05).In terms of antioxidant capacity,Taurine control group could significantly increase the activities of SOD and CAT(P<0.05).The activity of SOD and CAT in the taurine pretreatment group and the before and after treatment group increased first and then decreased,the highest activity is 10 m M.The activity of SOD in the taurine post-treatment group was gradually increased,the maximum activity appeared at 15 mM,and significantly higher than 5 mM and 10mM(P<0.05).CAT activity was similar to that of SOD.GSH-Px activity in the taurine pretreatment group?before and after treatment group increased with taurine concentration at first,and then decreased,10 mM activity was the highest,and significantly higher than 5 mM(P<0.05),taurine post-treatment group had the highest activity at 15 mM.MDA content in CCl4 group was significantly higher than that in other groups(P<0.05).The content of MDA was significantly decreased with adding taurine(P<0.05),the MDA content of the group was the lowest at 10 mM.It was found that CCl4 significantly down-regulated the m RNA expression of antioxidant enzymes(P<0.05).The addition of taurinecould significantly affect the mRNA expression of antioxidant enzymes(P<0.05).The m RNA expression of SOD and CAT increased with the increase of taurine concentration at 5 mM and 10 mM,then decreased at 15 mM,and the highest expression level of was 10 mM.GSH-Px gene expression increased with the increase of taurine concentration,which was the highest at 15 mM,but not significantly different from that at 10 mM(P>0.05).The results showed that taurine could significantly increase the antioxidant capacity of hepatocytes induced by CCl4,and compare the treatment group and the concentration of taurine,it was found that the before and after group and 10 mM concentration of taurine was the best combination of this study.