【作者】 李莉；

【导师】 谢平；

【作者基本信息】 中国科学院研究生院（水生生物研究所） ， 水生生物学， 2006， 博士

【摘要】 目前,尽管滤食性鱼类经常被暴露在高浓度的微囊藻毒素(MC)中,但MC对这类鱼影响的毒理学研究还很缺乏,滤食性鱼类高强度的抗毒机制也未阐明。本文以我国四大家鱼中的滤食性鱼类鲢、鳙为研究对象,开展了从室内的急性染毒实验到野外的围栏实验,研究MC在鲢、鳙的主要组织器官(肝、肾)中的累积及其引起的细胞和亚细胞结构上的病理变化,血清生化指标的变化和组织匀浆中抗氧化酶系的生化响应,来确定MC对鲢、鳙的毒害作用,以探讨鲢、鳙的抗毒机理及可能的解毒途径,为预防MC对水生动物和人类的危害提供实验依据。主要结果如下:1)室内鳙鱼急性毒性实验中,腹腔注射400和1000μg kg-1 bw剂量的MC粗提液,并注射后的1、3、12、24和48h取样,研究MC在肝中的累积和对肝的毒性效应。鳙肝中的MC用HPLC和LC/MS进行定性、定量检测,结果发现低剂量组在注射后12h肝中微囊藻毒素含量最高(2.89μg MCs g-1 DW),高剂量组在注射后3h肝中MC含量即达到最高值(5.43μg MCs g-1 DW),随后MC含量下降,然而肝脏的病理变化在注射后24h内呈时间依赖性的增长,并且肝细胞在低浓度MC作用下主要以细胞凋亡的形式死亡,而高浓度MC作用下主要以细胞坏死的形式死亡。显然,组织损伤相对毒素的累积具滞后性。与病理变化相一致的是,鳙鱼血清中的肝特征酶(ALT、AST、LDH)在注射后开始上升,并在24h达到峰值,之后逐渐恢复到对照组水平。研究中有两个新发现:MC导致的肝脏早期超微结构的变化是使细胞间隙增宽;注射后48h,在两个剂量组均观察到肝组织的恢复现象。另一方面,肝组织中ROS含量,抗氧化酶CAT、SOD,GPX、GR活性和脱毒酶GST活性在处理后均表现出一种先升后降的变化趋势,即在注射后3h逐渐上升达最大值,随后下降到对照组水平,表明CAT、SOD、GPX在清除ROS,抵抗MC的毒性伤害中发挥了关键的作用。尽管两剂量组肝中GSH的含量并未有显著的降低,但GST活性的增加更多还原

【Abstract】 Little is known on the toxic effects of MC on the phytoplanktivorous fish that are frequently exposed to cyanobacterial toxins because of their habitat and feeding mode. The mechanisms implicated in the high resistance of such fishes to MC have not been elucidated yet. The purposes of this study were to examine, through both acute toxic experiment under laboratory conditions and field investigation in fish pen, the changes of MC concentration, histo- and ultrastructure of liver and kidney and serum biochemical parameters as well as biochemical responses of antioxidant and detoxification systems in the phytoplantivorous silver and bighead carps and to discuss the toxic effects of MC on these fish with comments on the possible mechanisms of high resistance and detoxification capacities in phytoplantivorous fish. The results were summarized as follows:1) Bighead carp were injected i.p. with extracted microcystins (mainly MC-RR and–LR) at two doses, 400 and 1000μg kg-1 bw, and the changes in extractable MC in liver, in the histo- and ultra-structure of hepatocytes, and in serum biochemical parameters as well as biochemical responses of antioxidant and detoxification systems were studied at 1, 3, 12, 24 and 48 hr after injection. Quantitative and qualitative determinations of MC in the liver were conducted by HPLC更多还原