不同维生素E水平饲料对云纹石斑鱼幼鱼低盐胁迫前后抗氧化和渗透压调节功能的比较

维生素E(VE)在鱼类繁殖、生长代谢、抗氧化能力和免疫机能等方面有至关重要的作用。为探究饲料VE添加量对云纹石斑鱼低盐度胁迫下抗氧化和渗透压调节功能的作用,本实验设计0、20、40、80和160 mg/kg等5个VE水平饵料添加量,依次为A、B、C、D、E组,饲喂云纹石斑鱼幼鱼56 d。然后进行6 h低盐度(12)胁迫实验,测试皮质醇(COR)、葡萄糖(GLU)、乳酸(LD)等血清生化指标,超氧化物岐化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)、总抗氧化能力(T-AOC)和丙二醛(MDA)等抗氧化指标,以及鳃Na⁺/K⁺-ATP酶(NKA)、Ca²⁺-ATP酶活力等。结果显示,血清COR含量最高为盐度胁迫后A(32.74±1.53) ng/mL,最低为胁迫前E(19.06±3.88) ng/mL;GLU含量最高为盐度胁迫后A(16.46±0.99) mmol/L,最低为养殖前O(7.90±0.34) mmol/L;LD含量最高为低盐度胁迫前C(1.94±0.15) mmol/L,最低为胁迫后E组(1.30±0.06) mmol/L。说明VE的添加可以增强云纹石斑鱼抗应激的能力,且在47.524~134.566 mg/kg(B~D)的添加范围,效果较好。血清SOD、CAT、GSH-Px活力、T-AOC和MDA含量与投喂饲料中VE水平密切相关,SOD最高为胁迫前C(105.29±9.07) U/mL,最低为胁迫后A(11.23±2.30) U/mL;CAT最高为养殖前O(4.09±0.17) U/mL,最低为胁迫后A(0.35±0.10) U/mL;GSH-Px最高为胁迫前E(972.58±55.35) U,最低为胁迫后A(47.90±10.64) U;MDA最低为胁迫前D(33.48±2.34) nmol/mL,最高为胁迫后A(101.79±7.79) nmol/mL。饲料中添加91.378~178.924 mg/kg(C~E)水平VE对其抗氧化能力有增强作用。VE可增强NKA活力,当VE添加量为91.378 mg/kg(C)时,低盐度胁迫对NKA影响较小。而添加91.378~178.924 mg/kg(C~E)水平VE可增强云纹石斑鱼Ca²⁺-ATP酶活力。研究表明,饲料中添加91.378~134.566 mg/kg范围的维生素E,可以增强云纹石斑鱼的机体活力、抗应激及环境胁迫能力。

Effect of dietary vitamin Eonphysiological and antioxidant functions in juvenile Epinephelus moara under low salinity stress

Vitamin E (VE) plays a key role in reproduction,metabolism,antioxidant function and immunity of fish.For the research of effects of dietary VE on tolerance of Epinephelus moara for low salinity stress,five levels of VE supplementation were designed as 0,20,40,80 and 160 mg/kg (A,B,C,D,E in turn) in this experiment.Juvenile E.moara were fed for 56 days,and the real supplementation of VE was tested.Then,low salinity (12) stress experiment lasted for 6 h,different indexes of experimental fish were tested,serum biochemical indexes:cortisol (COR),glucose (GLU),lactic acid (LD);serum antioxidant:superoxide dismutase (SOD),catalase (CAT),glutathione peroxidase (GSH-Px) activities,total antioxidant capacity (T-AOC) and malondialdehyde (MDA);as well as gill Na⁺/K⁺-ATPase (NKA),Ca²⁺-ATPase activities.The results showed that serum COR concentration was increased by supplementing VE in diet.And after low salinity stress,serum COR concentration in every groups increased.There was no huge difference among serum GLU concentration in different groups.And after low salinity stress,serum GLU concentration in groups A,B,C increased significantly.Serum LD concentration in groups C,D,E increased in feeding experiment,then it increased in groups A,B and decreased in groups C,D,E after low salinity stress.Maximum of serum COR concentration was after stress A (32.74±1.53) ng/mL,minimum was before stress E(19.06±3.88) ng/mL;maximum of GLU concentration was after stress A (16.46±0.99) mmol/L,minimum was before culture O (7.90±0.34) mmol/L;maximum of LD concentration was before stress C(1.94±0.15) mmol/L,minimum was after stress E(1.30±0.06) mmol/L.The results of serum COR,GLU,and LD suggested that supplementation of VE would enhance anti-stress ability of E.moara,and the best range of supplementation of VE was 47.524-134.566 mg/kg (B-D).Maximum of SOD activity was before stress C (105.29±9.07) U/mL,minimum was after stress A(11.23±2.30) U/mL;maximum of CAT was before culture O (4.09±0.17) U/mL,minimum was after stress A (0.35±0.10) U/mL;maximum of GSH-Px was before stress E (972.58±55.35) U,minimum was after stress A (47.90±10.64)U;minimum of MDA was before stress D(33.48±2.34) nmol/mL,maximum was after stress A (101.79±7.79) nmol/mL.The supplementation of VE were close relative to serum SOD,CAT,and GSH-Px activities,T-AOC,MDA concentration,of which range was 91.378-178.924 mg/kg (C-E) that could strengthen antioxidant function of E.moara.VE can enhance the NKA activity.When the supplementation of VE was 91.378 mg/kg (C),low salinity stress had little effect on NKA activity.The range of supplementary VE which was 91.378-178.924 mg/kg (C-E),appeared to result in the activation of the Ca²⁺-ATPase activity.This study suggested that diets supplemented with VE can enhance vitality and anti-stress ability of body.In summary,analysis of biochemical,antioxidant and ion-regulatory indicators estimated that the best range of supplementation of VE was 91.378-134.566 mg/kg (C-D).