大黄素、维生素C及其配伍对团头鲂生长、生理生化指标、抗病原感染以及两种HSP70s mRNA表达的影响

Effects of emodin,vitamin C and their combination on growth,physiological and biochemical parameters,disease resistance and two HSP70s mRNA expression of Wuchang bream( Megalobrama amblycephala)

选取1200尾健康的团头鲂,体重为(133.44±2.11)g,随机分成4组,其中1组为对照组,投喂基础日粮(含50.3mg/kg维生素C,以L-抗坏血酸-2-多聚磷酸酯为Vc源),另外3组为试验组,投喂饲料是在基础日粮中分别添加60mg/kg大黄素、700mg/kgVc、60mg/kg大黄素+700mg/kgVc。连续投喂60d后,检测团头鲂生长、肌肉成分、血液和肝脏生化指标以及两种热休克蛋白70s(HSP70s)mRNA的表达水平,并统计团头鲂感染嗜水气单胞菌后的成活率,以综合评价大黄素、高剂量Vc及其配伍对团头鲂的作用效果。结果表明,与对照组相比,大黄素、Vc组显著提高了鱼体增重率和特定生长率,血清中总蛋白(TP)、溶菌酶(LSZ)和碱性磷酸酶(AKP)的水平,肝脏中超氧化物歧化酶(SOD)的活性和诱导型HSP70 mRNA的基础表达水平,降低了饵料系数、死亡率、血清中皮质醇(COR)、甘油三酯(TG)以及肝脏丙二醛(MDA)的含量(P<0.05);配伍组虽然血清中TP、LSZ的含量以及肝脏HSP70 mRNA水平显著升高,肝脏MDA的含量也显著降低(P<0.05),但均未表现出协同增效作用,其它指标与对照组相比差异均不显著(P>0.05)。此外,与对照组相比,大黄素组还显著提高了团头鲂肝脏过氧化氢酶(CAT)的活性(P<0.05),而Vc和配伍组的CAT活性与对照组的差异不显著(P>0.05);其它一些指标如血清中葡萄糖(GLU)、谷丙转氨酶(GPT)、谷草转氨酶(GOT)、胆固醇(CHOL)、肝脏组成型HSC70mRNA的表达水平、鱼体形体指标以及肌肉组成成分等各组间差异均不显著(P>0.05)。攻毒试验也表明,大黄素和高剂量Vc组能显著提高攻毒后鱼的成活率(P<0.05),而二者配伍后效果反而下降,其相互作用的机理还有待于进一步研究。

The study aims to evaluate the effects of dietary emodin,high-dose vitamin C （ Vc） and their combination on growth,non-specific immunity and resistance to pathogens of Wuchang bream,Megalobrama amblycephala. 1200 healthy fish with initial body weight（ 133. 44 ±2. 11） g were selected and randomly divided into four groups： one control and three tested. The control group was fed with basal diet（ Vc content 50. 3 mg / kg,with L-ascorbyl-2-ployphosphate as source ） . The three tested groups were fed with basal diets supplemented with 60 mg /kg emodin,700 mg /kg Vc,and 60 mg /kg emodin ＋ Vc 700 mg /kg,respectively. Fish were fed twice daily（ 8： 30 and 16： 30） at a feeding rate of 2% -4% body weight. After 60 days feeding, the growth performance,muscle composition,biochemical parameters of serum and liver,the mRNA levels of two heat shock protein 70s（ HSP70s） ,and survival rates after being infected with Aeromonas hydrophila were investigated. The results showed that compared with the control,the weight gain and specific growth rates,the levels of total protein（ TP） ,lysozyme（ LSZ） and the alkaline phosphatase（ AKP） in serum,the activity of superoxide dismutase（ SOD） and basal expression level of inducible HSP70 mRNA in liver were significantly improved（ P 0. 05） ,while feed coefficient,mortality,the contents of serum cortisol（ COR） and triglycerides （ TG） ,and liver malondialdehyde（ MDA） were reduced（ P 0. 05） in emodin and Vc groups. Although the serum TP,LSZ levels,and the mRNA level of liver HSP70 increased significantly（ P 0. 05） ,and the liver MDA content also significantly decreased（ P 0. 05） in combination group,the synergism didn’t appear,and other indices were not significantly different（ P 0. 05） from the control. In addition,the liver catalase（ CAT） activity was also significantly improved in emodin group compared with the control（ P 0. 05） ,while the CAT activities in Vc and combination groups were not significantly different from the control（ P 0. 05） . Other indices,such as serum glucose （ GLU ） ,glutamic-pyruvic transaminase （ GPT ） ,glutamic-oxaloacetic transaminase（ GOT） ,cholesterol（ CHOL） ,the mRNA level of liver constitutive HSC70,the fish body indices, and muscle composition were not significantly different between groups（ P 0. 05） . The challenge experiment with A. hydrophila showed that compared with the control the survival rates in emodin and Vc groups significantly increased（ P 0. 05） whereas the survival rate in combination group had no significant difference （ P 0.05） . These results indicate that the basal diets supplemented with emodin 60 mg/kg or Vc 700 mg/kg could promote the growth of fish,improve the non-specific immunity,antioxidation capacity,and the basal expression level of HSP70 mRNA,and enhance disease resistance. However,the combination of emodin and high-dose Vc showed no better effect,and the mechanism of their interaction remains to be further studied.