摘要:
为评价典型有机污染物共存情况下对长江上游三峡库区特有珍稀鱼类的环境风险，以稀有鮈鲫(Gobiocypris rarus)为对象，研究了多环芳烃和酞酸酯的代表物苯并芘(BaP)和邻苯二甲酸二(2-乙基己基)酯(DEHP)单独及复合暴露而引起的内分泌干扰效应。将成年稀有鮈鲫暴露于不同浓度的BaP(0.1、1 μg·L-1)、DEHP(10、100 μg·L-1)和BaP+DEHP((0.1+10)、(1+100) μg·L-1)中28 d后，测定了体质系数、性激素含量、下丘脑-垂体-性腺(HPG)轴和肝脏中与生殖相关基因的表达。结果表明，在雌鱼中，单独BaP或DEHP暴露对鱼体性激素含量、基因表达量无显著影响；BaP和DEHP复合暴露时，高浓度组睾酮(T)含量升高但雌二醇(E2)含量下降，fsh、vtg、cyp17和17β-hsd基因表达量上调，cyp19a则下调，表现出协同毒性。因而雌鱼中性激素水平的改变可能与类固醇合成相关基因表达量的改变有关。而无论在单独暴露或是复合暴露情况下，对雄鱼体内性激素无显著影响。以上检测到的激素或基因表达量的改变主要发生在高剂量的复合暴露组中，而长江上游三峡库区水体中多环芳烃和酞酸酯含量低于暴露的最低浓度，因此推测，库区存在的多环芳烃和酞酸酯同时作用时不会对三峡库区上游水体中的鱼类产生生殖内分泌干扰效应。
Abstract:
The potential impact of environmental contaminants on endemic fish species that inhabit the Three Gorge Reservoir (TGR) has raised increasing concern. In the present study, we investigated the combined endocrine disrupting effects of benzo(a)pyrene (BaP) and di-(2-ethylhexyl)-phthalate (DEHP) on the Chinese rare minnow (Gobiocypris rarus), a type of endemic fish distributed in upstream of the Yangtze River. Adult rare minnows were exposed to BaP (0.1 or 1 μg·L-1), DEHP (10 or 100 μg·L-1) or a mixture of both (BaP+DEHP: (0.1+10), or (1+100) μg·L-1) for 28 days. Results showed that no significant difference of sex hormones or gene transcription was observed by exposure to BaP, DEHP alone or combination in males. However, in the BaP+DEHP co-exposure ((1+100) μg·L-1) group, plasma concentrations of 17β-estradiol (E2) and testosterone (T) in females were significantly altered, exerting synergy toxic effect. In addition, combined exposure to BaP and DEHP ((1+100) μg·L-1) caused increase of plasma T levels and T/E2 ratio in females compared to BaP or DEHP exposure alone, suggesting an additive effect when BaP is supplemented with DEHP. These altered sex hormones in females were accompanied by modified gene transcription of fsh, vtg, cyp17, 17β-hsd and cyp19a. It should be noted that the observed alterations of sex hormones and gene transcription occurred mostly in the high-dose combined exposure group ((1+100) μg·L-1), which are higher than the concentration detected in TGR surface water. Therefore, it is suggested that environment concentration of polycyclic aromatic hydrocarbons and phthalates alone or in combination might not disturb the endocrine system of the rare minnow in the TGR.
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