溴氰菊酯对中华绒螯蟹肝胰腺氧化胁迫效应和组织结构的影响

Effects of deltamethrin exposure on oxidative stress indexes and histological structure of hepatopancreas in Eriocheir sinensis

为探究溴氰菊酯对中华绒螯蟹的毒性和致毒机制,从免疫学和形态学2个方面研究了溴氰菊酯对中华绒螯蟹的毒害作用。采用24 h换水式渔药毒性试验的方法,先测出溴氰菊酯对中华绒螯蟹的24 h-LC_(50)、48 h-LC_(50)、96 h-LC_(50)分别为4.289 4、3.481 8、1.319 5μg·L^(-1),安全浓度为0.658 9μg·L^(-1);再选取96 h-LC_(50)的1/2(浓度Ⅰ)、1/5(浓度Ⅱ)、1/10(浓度Ⅲ)3个溴氰菊酯浓度组为试验组,空白组和溶剂组为对照组,分别在给药后测定肝胰腺超氧化物歧化酶(SOD)、过氧化氢酶(CAT)的活性和丙二醛(MDA)积累量等氧化胁迫相关指标的变化;同时在溴氰菊酯胁迫15 d后,观察各浓度组中华绒螯蟹肝胰腺组织结构的变化。结果表明:(1)各个试验组SOD和CAT活力都呈现了先下降后上升再下降的变化趋势,试验组MDA含量始终高于空白组,空白组和溶剂组各个时间点各项指标之间无明显差异。胁迫6 h后,各试验组的CAT的活力极显著低于空白组,其中浓度Ⅱ和Ⅲ组比空白组下降了37.96%和38.92%,MDA含量极显著高于空白组;胁迫12~24 h,SOD和CAT分别受到诱导,24 h时试验组的3个浓度组SOD活力分别比空白组升高了72.13%、87.93%和83.20%,MDA含量减少;胁迫48 h和72 h时,SOD和CAT活力受到抑制,72 h时,浓度Ⅰ和浓度Ⅲ组的SOD分别比空白组下降了40.94%和51.06%,浓度Ⅲ组的CAT值比空白组下降了32.58%,随着胁迫时间的延长,MDA的积累量逐渐增加;(2)在溴氰菊酯胁迫15 d后,各试验组中华绒螯蟹的肝胰腺结构均受到了不同程度的破坏,B细胞数量减少,基膜增厚,肝胰腺上皮细胞肿大并出现空泡样变性,随着溴氰菊酯的浓度增大,肝胰腺受损程度加大,空泡数量增多,上皮细胞脱落,肝胰腺基膜和上皮细胞分离且部分破裂,细胞核固缩。由此得出,溴氰菊酯对淡水中华绒螯蟹属于高毒药物,随着溴氰菊酯胁迫时间的延长和胁迫浓度的增加,肝胰腺MDA含量增加,机体非特异性防御系统受到损伤,肝胰腺正常细胞结构受到破坏。

In order to explore the toxicological effects and mechanism of deltamethrin on Eriocheir sinensis,an acute semi-static toxic test was carried out,the LC50 values of 24,48 and 96 h were 4.289 4,3.481 8 and 1.319 5 μg·L^-1,respectively,and the safe concentration was 0.658 9 μg·L-1.This study also revealed the modulation of antioxidant enzymes such as superoxide dismutase（SOD）,catalase（CAT） and malondialdehyde（MDA） content,which was the main product of lipid peroxidation,at 6,12,24,48 and 72 h in different deltamethrin concentration.96 h-LC50/2（concentration I） group,96 h-LC50/5（concentration II） group and 96 h-LC50/10（concentration III）group were test groups,and blank group and vehicle group were control groups.Histological structure of hepatopancreas was observed on 15th day in different deltamethrin concentrations.The results were as follows：（1） The oxidative stress indicators were varied in all groups exposed to deltamethrin,SOD and CAT activities showed similar variation of inhibition-induction-inhibition during the test,and the levels of MDA in test groups were all higher than that in blank group.The three indicators had no significant difference at different time in both vehicle group and blank group,and vehicle group also had no obvious difference from blank group.After 6 h exposed to deltamethrin,the CAT activities of all test groups were significantly lower than those of control group,and CAT activities of concentration II and III groups decreased by 37.96% and 38.92% compared with blank groups.MDA levels of test groups were obviously higher than that of control group.After 12 and 24 h,SOD and CAT activities were induced,SOD activities of three test groups were 72.13%,87.93% and 83.20% higher than that of blank group,and the levels of MDA decreased at 24 h.After 48 h and 72 h,SOD and CAT activities were inhibited again,SOD activities of concentration I and III groups were 40.94% and 51.06% lower than that of blank group,CAT activities of concentration III group were 32.85% lower than that of blank group,and MDA levels of test groups gradually increased along with the increase of stress time of deltamethrin.（2） Histological structure of hepatopancreas was affected at different degrees in different deltamethrin concentration for 15 d.In these three test groups,the number of B cells of hepatopancreas was decreased,the basement membrane became thicker,some hepatic cells were swelling and cavity appeared,some vacuoles appeard in B cells.As deltamethrin concentration increased,the degree of deterioration of hepatopancreas aggravated,the number of vacuoles increased and some hepatic cells were crushing and many cell debris appeared in the lumen,many vacuoles existed between basement membrane and epithelial cells,part of the basement membranes were separated from epithelial cells and ruptured,nucleus were pyknotic.The results indicated that deltamethrin was high toxic pesticide to E.sinensis,with the deltamethrin concentration increasing and stress time prolonging,MDA levels increased,and the non-specific defense system and normal cell structure of E.sinensis were destroyed.