镉对克氏原螯虾肝胰腺抗氧化系统的影响

采用毒性试验方法,研究了不同浓度Cd2+(1.72、3.44、6.89、13.77和27.55mg·L-1)对克氏原螯虾肝胰腺抗氧化酶(SOD、CAT、GSH-PX)和抗氧化物质(GSH、Vc)的影响.结果表明:超氧化物歧化酶(SOD)活性受低浓度Cd2+诱导和高浓度Cd2+抑制,且受抑制程度与Cd2+浓度呈正相关.过氧化氢酶(CAT)活性总体表现为先激活后下降,且在第3天达最大值,CAT活性对低浓度Cd2+(≤6.89 mg·L-1)暴露敏感,而高浓度Cd2+对其影响较小.谷胱甘肽过氧化物酶(GSH-PX)活性对Cd2+浓度敏感,当Cd2+≤6.89 mg · L-1时,GSH-PX活性先升高后下降,更高浓度下GSH-PX活性在暴露后第1天即表现出抑制作用.还原型谷胱甘肽(GSH)含量在Cd2+≤6.89 mg·L-1时始终被诱导,且均在第1天达最大值,而高浓度Cd2+(≥13.77 mg·L-1)对GSH含量影响不明显.维生素C(Vc)对Cd2+胁迫敏感,各处理组Vc含量在第1天均显著下降,且下降程度与Cd2+浓度呈正相关,之后具有一定的合成恢复能力.抗氧化酶和非酶抗氧化物质在抵御Cd2+胁迫反应中共同发挥作用,且大多表现出明显的时间和剂量效应性.GSH-PX和Vc可以作为Cd2+污染的潜在生物指示物.

Effects of Cd2+ on antioxidant system in hepatopancreas of Procambarus clarkii

By the method of toxicity bioassay,this paper studied the effects of different concentration(1.72,3.44,6.89,13.77,and 27.55 mg·L-1) Cd2+ on the activities of antioxidative enzymes(SOD,CAT,and GSH-PX) and the antioxidation substances(GSH and Vc) in hepatopancreas of freshwater crayfish Procambarus clarkii.The results showed that the SOD activity was induced at the lowest concentration(1.72 mg·L-1) Cd2+ but inhibited at all other test concentrations Cd2+,and the inhibition degree was positively correlated with the Cd2+ concentration.Under all test concentrations Cd2+,the CAT activity decreased after an initial increase,with a peak 3 days after exposure.The CAT activity was sensitive to lower concentrations(≤6.89 mg·L-1) Cd2+,but had no significant difference at higher concentrations(>6.89 mg·L-1) Cd2+.When the Cd2+ concentration was ≤6.89 mg·L-1,the GSH-PX activity showed a trend of increasing first and then decreased;when the Cd2+ concentration was 13.77 or 27.55 mg·L-1,the GSH-PX activity was depressed during the first day of exposure.When the Cd2+ concentration was ≤6.89 mg·L-1,the GSH content reached the highest value on the first day of exposure,and maintained at a higher level than the control group.However,when the Cd2+ concentration was ≥13.77 mg·L-1,the GSH content had no significant difference with the control.The Vc content was very sensitive to all test concentrations Cd2+.It decreased significantly on the first day of exposure,with the decrement positively correlated to Cd2+ concentration,but showed a recovering trend with exposure time.The results indicated that both the antioxidative enzymes and the antioxidation substances in the hepatopancreas of P.clarkii played important roles in coping with Cd2+ stress,and in most cases,showed a time-and dose-dependent relationship with Cd2+ concentration.The GSH-PX activity and Vc content of P.clarkii could be used as the potential bio-indicators in evaluating Cd2+ contamination.