土霉素对日本锦鲫肝脏抗氧化防御系统的影响

Antioxidant Responses in Liver of Carassius auratus Under Oxytetracycline Exposure

土霉素(Oxytetrac ycline,简称OTC)是养殖业中广泛使用的药物之一,由于大量使用,已在水环境中不断被检出,其对水生生物及人类可能产生的影响已经引起人们广泛关注。采用室内染毒实验方法,研究了土霉素对典型淡水鱼类日本锦鲫肝脏抗氧化防御系统的影响,分析暴露于不同浓度(0、0.01、0.05、0.1、0.5、1.0、5.0、10mg·L-1)的OTC溶液15d后鱼体肝脏中ROS、MDA、SOD、CAT和谷胱甘肽等指标,探讨其潜在的致毒机制。结果表明,ROS信号强度在高浓度组(5mg·L-1和10mg·L-1)与对照相比分别减少44.2%和32.5%,呈显著性差异;MDA含量在0.1mg·L-1和5mg·L-1下显著减少,分别减少41.7%和52.3%;SOD活性在0.01mg·L-1下显著性增加32.4%,CAT和GST活性呈低浓度被诱导、高浓度被抑制的趋势;GSH和GSSG含量的变化趋势相似,呈先减少后增加的趋势(P<0.05)。上述结果表明低浓度OTC对日本锦鲫产生氧化应激,诱导了肝脏抗氧化防御系统,但高浓度下清除氧自由基的作用大于其氧化应激毒性,从而使得鱼体氧化应激程度减轻。抗氧化防御系统酶活性的变化只能间接反映污染物对生物造成应激效应的程度,要弄清楚OTC的致毒机制仍需进一步研究。

Oxytetracycline（OTC）is being used commonly for medical treatments in farming industry,but the associated potential effects of OTC is an increasing concern in the aquatic environment.In this paper,the effects of OTC on the antioxidant defense system of the liver of fish（Carassius auratus）were investigated.After the fish was exposed for 15 d to different concentrations of 0,0.01,0.05,0.1,0.5,1.0,5.0,10 mg·L-1 OTC,respectively,ROS,MDA,SOD,CAT,GSH and GSSG in the fish liver were analyzed to study the possible oxidative damage mechanism.The study showed that ROS signal intensity in the fish liver decreased by 44.2% and 32.5%,respectively,compared with the control when the fish was exposed to 5 mg·L-1 and 10 mg·L-1 of OTC.MDA contents decreased by 41.7% and 52.3% when exposed to 0.1 mg·L-1 and 5 mg·L-1,respectively.SOD activity markedly increased by 32.4% at the exposure concentration of 0.01 mg·L-1.CAT and GST activities were induced at low concentrations but inhibited at high concentrations and the contents of GSH and GSSG had the similar change as wel（lP0.05）.These results suggested that low concentrations of OTC generated oxidative stress to Carassius auratus and triggered antioxidant defense,however,higher concentrations of OTC eliminated part of the ROS,and therefore reduced the degree of oxidative stress.Activity changes of anti-oxidization enzymes can only indirectly reflect the degree of pollutant stress to the organism and further studies are needed to understand the toxicity mechanism clearly.