镉对克氏原螯虾肝胰腺触角腺及鳃中SOD和CAT活性的影响

Effects of Cadmium on SOD and CAT in Hepatopancreas,Antennary Gland and Gill of Procambarus clarkii

采用急性毒性实验方法,将克氏原螯虾分别暴露在浓度为7.5、10、15、30mg·L-1的Cd2+溶液中96h,实验期间对肝胰腺、触角腺、鳃等组织的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活力及随时间变化进行了检测。结果表明,在10mg·L-1Cd2+胁迫下,肝胰腺和触角腺中SOD和CAT活力在胁迫初期急剧升高,72h后降低并趋于稳定,而鳃中SOD和CAT两种酶的活力在96h内变化不显著(P>0.05);当Cd2+浓度为30mg·L-1时,肝胰腺、触角腺和鳃中的SOD、CAT酶活力显著受到了抑制(P<0.05)。通过比较发现,克氏原螯虾鳃中SOD和CAT活力要明显低于肝胰腺和触角腺中这两种酶的活力(P<0.05),并且肝胰腺和触角腺对Cd2+的应激反应要比鳃更为敏感。由以上结果可以看出,肝胰腺和触角腺中的抗氧化酶系统在Cd2+胁迫初期发挥了一定的抵御作用,而到后期抗氧化酶活性明显受到了抑制;另外低浓度的镉(7.5mg·L-1)对肝胰腺和触角腺中的SOD和CAT酶活起到了激活作用,而高浓度的镉(30mg·L-1)对3个组织中的抗氧化酶起到了明显的抑制作用。

The correlation between heavy metals pollution and crustacean＇s response is widely studied. The crayfish, Procambarus clarkii, has been extensively studied as a bioindicator of the effects of pollutants and also for its economic importance. This study aimed at evaluating the role of antioxidant defenses during cadmium-induced oxidative stress. The superoxide dismutases（SOD） and catalase（CAT） in hepatopancreas, antennary gland and gill of crayfish were investigated, which induced by cadmium at different concentrations and exposure times. Results showed：when crayfish were treated with 10 mg·L^-1 Cd^2＋, the activities of SOD and CAT in hepatopancreas and antennary gland were first increased swiftly at earlier stage and then decreased to a stable lower level after 72 hours, white SOD and CAT activities in gill were not affected significantly（P〉0.05 ）. When crayfish were exposed to a higher concentration（30 mg·L^-1）, the activities of SOD and CAT in hepatopancreas, antennary gland and gill were inhibited significantly （P〈0.05）. In addition, SOD and CAT activities in gill were lower significantly than those in hepatopancreas and antennary gland（P〈0.05 ）, the stress response to Cd^2＋ were more sensitive in hepatopancreas and antennary gland than in gill. These suggested that the antioxidant enzyme system in hepatopancreas and antennary gland played an important role on resisting Cd^2＋ at the earlier stage, while the activities of antioxidant enzyme were inhibited significantly at the later stage. In addition, the lower concentration of cadmium（7.5 mg·L^-1） induced the activities of both SOD and CAT in hepatopancreas and antennary gland, while the higher concentration of cadmium（30 mg·L^-1） inhibited significantly the activities of antioxidant enzyme in the three kind of tissues, this indicated that the antioxidase system might be damaged by the higher concentration of cadmium.