汞离子胁迫对红鳍笛鲷抗氧化酶及乙酰胆碱酯酶活性的影响

Effects of mercury exposure on the antioxidant enzymes and acetylcholinesterase activities in the young crimson snapper (Lutjanus erythropterus)

为探讨鱼体抗氧化系统以及神经系统对水体中汞胁迫的响应机制,在实验条件下研究了汞离子对红鳍笛鲷幼鱼[体长为(4.95±0.79)cm,体重为(4.57±2.02)g]的急性毒性及对鱼体肝脏、鳃组织的超氧化物歧化酶(SOD)、丙二醛(MDA)及脑组织乙酰胆碱酯酶(AChE)活力的影响。结果表明:半静水实验条件下,汞离子对红鳍笛鲷幼鱼的安全浓度为0.040mg/L。汞离子暴露6h时,各浓度组的肝脏SOD酶活均比对照组有显著升高(P<0.05)。随暴露时间的增加,低浓度组SOD的活性变化较小,而高浓度组鱼体肝脏SOD的活性出现被诱导或被抑制的现象,表明鱼体在高浓度汞胁迫下抗氧化系统出现一定程度的紊乱。鳃的SOD活力在暴露6h亦显著升高,随时间的延长,各浓度组SOD的活性具不同程度的下降趋势。MDA含量的变化表明,鳃组织在暴露6h时已开始受到显著损伤(P<0.05),而肝在6h时无显著变化,在12h时开始受损伤。脑组织AChE活性在暴露6h时略受抑制(P>0.05);暴露12h时高浓度组显著增加(P<0.05),诱导率平均为36%;汞离子暴露24h时,鱼脑AChE的抑制率分别为28%～38%;暴露48h、96h时抑制率为14%～24%、12%～17%。

To understand the response of fish antioxidant defense and neural system to mercury exposure,studies were conducted in laboratory between 26 and 29 ℃ on the acute toxicity and exposed effects on antioxidant enzymes and AChE activities in the young crimson snapper,Lutjanus erythropterus Bloch,of an average weight of（4.57 ±2. 02） g and body length（4. 95 ±0. 79） cm. Using static renewal method,the results showed that the safe concentration of mercury chloride for the young crimson snapper was 0. 040 mg/L. The enzymes activities were evaluated under four sublethal concentrations（0. 000 5 mg/L,0. 002 5 mg/L,0. 005 mg/L and 0. 025 mg/L Hg2＋） . The tissues（gill and liver） were tested for SOD,MDA activity and the brain for AChE after 6 h,12 h,24 h,48 h and 96 h exposure,respectively. The results showed that hepatic SOD activities had significant increase on 6 h exposure（P 0. 05） . With the increase of mercury concentration,the hepatic SOD activities were inhibited or induced,which showed the disturbance of fish metabolism. And the branchial SOD activities were also significantly elevated. The variation of MDA content exhibited that the gill was impaired on 6 h exposure,while the hepatic tissue was detected to be impaired on 12 h. The AChE activities in the brain had no significant decrease（P 0. 05） on 6 h exposure. However,it decreased with the induction rate of 36% on 12 h exposure. When the fish were exposed longer time,the inhibition rates were 28%-38%,14%-24% and 12%-17% on 24 h,48 h and 96 h exposure in concentrations respectively.