水体铅对胚胎-仔鱼期南方鲇的氧化应答及神经毒性作用

摘要

为了解水体中铅(Pb)对鱼类早期发育阶段的毒性影响,使用人工受精获得南方鲇(Silurus meridionalis Chen)胚胎和仔鱼为研究对象,以硝酸铅(Pb(NO3)2) 为毒物源,探讨研究对象在胚胎期和仔鱼期受到5个(0~400 μg/L) 不同浓度水平铅持续暴露、半持续暴露以及暴露后恢复处理条件下,实验鱼鳃、肝脏和肾脏抗氧酶的活性变化以及脑组织中乙酰胆碱酯酶活性情况.结果表明,恢复组实验鱼鳃、肝脏和肾脏组织中总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性在后期恢复过程中呈升高趋势;三种组织中丙二醛(MDA)含量随着胚胎期水体 Pb浓度升高而升高.持续组和半持续组实验鱼鳃、肝脏和肾脏组织中 T-AOC、SOD、CAT活性随着水体铅浓度升高而降低,显著低于对照组(P<0.05),丙二醛含量随着Pb浓度升高而升高,脂质过氧化程度加剧;而相同Pb浓度水平之间,持续组和半持续组实验鱼三种组织中,持续组中T-AOC、SOD、CAT的活性和MDA的含量变化大于半持续组.发现:南方鲇胚胎期受重金属暴露,后期恢复饲养,其鳃、肝脏和肾脏组织中T-AOC、SOD、CAT的活性会出现恢复效应;胚胎期和仔鱼期重金属暴露存在叠加效应,且重金属对仔鱼的毒性作用更加剧烈.%To determine the toxic effects caused by waterborne lead (Pb)of five different exposure concentration(0~400 ug/L) on embryonic and larval development of the Silurus meridionalis Chen in continuous, semi-continuous exposure, or recovery after exposure, this research investigated two aspects on, the activity changes of antioxidant enzymes in gill, liver, kidney, and acetylcholinesterase in the brain tissue.The results of the recovery group showed an increase trend in the activity of T-AOC, SOD and CAT during the later phases of the recovery process.The content of MDA increased as the liquid Pb exposure concentration gets higher at the embryo stage.The activity of T-AOC, SOD, CAT decreased as the liquid Pb concentration exposure increased in the continuous and semi-continuous groups, which was significantly lower compared with the control group (P<0.05).The MDA content increased as the Pb exposure concentration increased.At the same time, the lipid per oxidation? reacted more violently.Under the condition of equal Pb exposure, both the activity of T-AOC, SOD, CAT and MDA content in the continuous group had more significant changes than that in semi- con-tinuous group.The results showed recovery effect occurred in the activity of T-AOC, SOD, CAT in gill, liver and kidney of the later phases of recovery, even if the embryos of S.meridionalis were exposed to Pb resolution.Superimposed effect occurred in the embryo stage and larva stage due to Pb exposure which caused more severe toxicity on larvae than it did to embryos.