镉对长江华溪蟹酶活性及脂质过氧化的影响

EFFECTS OF CADMIUM ON ENZYME ACTIVITY AND LIPID PEROXIDATION IN FRESHWATER CRAB SINOPOTAMON YANGTSEKIENSE

本实验于2005年3—7月,采用急性毒性实验方法,研究了镉(Cd)对长江华溪蟹(Sinopotamon yangtsekiense)酶活性及脂质过氧化产物的影响。Cd处理设5个浓度组,分别为7.25mg/L、14.5mg/L、29mg/L、58mg/L和116mg/L,实验同时设对照组。分别在24h、48h、72h和96h取肝胰腺和鳃进行超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性的测定和脂质过氧化产物丙二醛(MDA)含量的测定。结果显示,在实验剂量范围内,随着镉浓度的增加和处理时间的延长,SOD和GSH-Px的活性均呈现先增高后降低的趋势,并存在组织差异性;而组织中MDA的含量随镉浓度的增加和处理时间的延长而升高。当处理时间为48h、Cd浓度为14.5mg/L时,肝胰腺和鳃中SOD活性均达最大值,较对照组差异极显著;当处理时间为48h、Cd浓度为7.25mg/L时,肝胰腺中GSH-Px活性达最大值,较对照组差异极显著;当处理时间为24h、Cd浓度为14.5mg/L时,鳃中GSH-Px活性达最大值,较对照组差异极显著。伴随处理时间和Cd浓度的增加,SOD和GSH-Px的活性开始逐渐下降。肝胰腺和鳃中GSH-Px/SOD的比值在对照组中处于平衡状态,但是在处理组中失去了平衡,有降低的趋势。结论:SOD与GSH-Px的活性和MDA含量的变化可以灵敏地反映Cd的胁迫程度及毒性大小。

With variant concentrations of cadmium （Cd） （7.25mg/L, 14.5mg/L, 29mg/L, 58mg/L and 116mg/L） and treating times （24h,48h,72h and 96h） disposed on freshwater crab, Sinopotamon yangtsekiense, the activities of Superoxide dismutase （SOD） and Glutathione Peroxidase （GSH-Px） were investigated by acute toxicity. In the range of exposure dosages, the activities of SOD and GSH-Px in these two tissues were found going up and then down with the increasing concentration of Cd and treating time. However,the content of Maglonydiadehyde （MDA） was continuatively improved. When explored at 14.5mg/L of Cd for 48h, the SOD activity of the two tissues amount to the highest, being（34. 123 ± 0.993）U/mg protein and（29.340 ± 1. 802） U/ mg protein, respectively in hepatopancreas and gill, and values were both significant. However, the GSH-Px activities in hepatopancreas, when treated by 7.25mg/L of Cd for 48h, attained to the maximum, and it was in gill by 14.5mg/L for 24h. Moreover, the activities of SOD and GSH-Px potentially decreased with the up of Cd concentration and treating time, and then dropped to the lowest at 116mg/L of Cd. Ratio of GSH-Px/SOD is useful tool as index of antioxidant level. It was revealed that the ratio of GSH-Px/SOD in tissues and treated Cd concentration plus time was converse. Briefly, the experimental results suggested that the variations on the enzyme activity and the MDA content may sensitively indicate the toxicity of Cd as well as the inhibition effects of enzymes to it. Besides, the possible mechanism was also analyzed and discussed.