中文摘要：

以克氏原螯虾为实验材料，研究不同浓度氨氮对克氏原螯虾抗氧化功能的影响。实验分为6组，氨氮梯度设置为0（对照组）、10、20、30、40和50mg/L，分别于1、12、24、36和48h取肝胰脏测定超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性和丙二醛（MDA）含量。结果显示：（1）在同一浓度氨氮作用下，随着作用时间延长，SOD、CAT活性和MDA含量均呈现先上升后下降的趋势。（2）在不同浓度的同一取样时间点，随着氨氮浓度升高，SOD和CAT活性除在48h时逐渐下降外，在其他取样时间点均呈现先上升后下降的趋势；MDA含量均呈现逐渐上升的趋势。结果表明，氨氮对克氏原螯虾抗氧化功能有显著影响，抗氧化酶活性随着氨氮胁迫水平增加表现出先激活后抑制的趋势，在此过程中机体因氨氮胁迫受到的损伤逐渐增加。

英文摘要：

This study explored the effect of different concentrations of ammonia nitrogen on the function of antioxidant system in Procambarus clarkii.This experiment designed 6 ammonia nitrogen concentrations （0, 10, 20, 30, 40 and 50 mg/L）.The activi-ties of superoxide dismutase （SOD） and catalase（CAT）, and the content of malondialdehyde （MDA） in the hepatopancreas were measured at 1, 12, 24, 36 and 48 hours after stress.The results were acquired as follows：（1） Under the condition of same ammo-nia nitrogen concentration , the activities of SOD and CAT , and the content of MDA all increased at first and then decreased as the stress time extended.（2） When sampling time was the same , along with the increase in the concentration of ammonia nitrogen , the activities of SOD and CAT increased at first and then declined at all sampling time （ except that they gradually decreased at 48 hours after stress）, and the content of MDA increased gradually at all sampling time .The above results suggested that ammonia nitrogen stress had significant effects on the function of antioxidant system in Procambarus clarkii, and the activities of antioxidant enzymes were induced at first and then inhibited along with the increase of ammonia nitrogen stress level .In this process , the damage of am-monia nitrogen stress to the crawfish organism increased gradually .