氨氮胁迫对青鲫幼鱼急性毒性和抗氧化功能的影响

Effects of ammonia nitrogen stress on acute toxicity and antioxidant capacity of juvenile Dongtingking crucian carp(Carassius auratus indigentiaus)

为了研究氨氮对洞庭青鲫(Carassius auratus indigentiaus)幼鱼急性毒性及抗氧化功能的影响,本试验采用静态毒性试验方法,以青鲫幼鱼(体质量14.47±1.67 g;体长7.20±0.86 cm)为试验对象,得到氨氮对青鲫幼鱼96 h半致死质量浓度(96 h LC50)为145.21 mg/L,安全浓度为14.5 mg/L。基于半致死质量浓度,研究了20 mg/L和80 mg/L氨氮胁迫对青鲫肝脏抗氧化功能的影响,发现氨氮胁迫后丙二醛(MDA)含量、谷胱甘肽转移酶(GST)和谷胱甘肽过氧化物酶(GPx)活性均出现显著性升高。随着暴露时间的增加,超氧化物歧化酶(SOD)活性显著性增加,然而过氧化氢酶(CAT)活性显著性降低。氨氮胁迫后还原型谷胱甘肽(GSH)呈现浓度和时间依赖性降低。试验结果表明,氨氮胁迫可引起青鲫幼鱼抗氧化防御系统功能紊乱。

In order to investigate the effect of ammonia nitrogen on the acute toxicity and antioxidant function of juvenile Dongtingking crucian carp(Carassius auratus indigentiaus),the static toxicity test method was utilized to study the acute toxicity of ammonia nitrogen to juvenile Dongtingking crucian carp(14.47±1.67 g;7.20±0.86 cm)in the present experiment.The 96-hour half-lethal concentration(96-h LC50)of ammonia nitrogen to juveniles was 145.21 mg/L,and the safe concentration was 14.5 mg/L.Based on the half-lethal concentration,the toxic effects of 20 mg/L and 80 mg/L ammonia nitrogen on the hepatic antioxidant function of the juvenile Dongtingking crucian carp were also studied.After exposure to the ammonia,the malondialdehyde(MDA)content,glutathione transferase(GST)activity and glutathione peroxidase(GPx)activity significantly increased.The superoxide dismutase(SOD)activity increased significantly,while the catalase(CAT)activity decreased significantly with the increased exposure time.Reduced glutathione(GSH)decreased in a concentration-and-time-dependent manner under ammonia stress.The results indicated that ammonia stress could result in the dysfunction of the antioxidant defense system of juvenile Dongtingking crucian carp.