Zhang Zhaobin, Hu Jianying
College of Environmental Sciences, Peking University, Beijing 100871, China.
J Environ Sci (China). 2008;20(3):347-52. doi: 10.1016/s1001-0742(08)60054-6.
Although 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethylene (p,p'-DDE), the major and most persistent metabolite of dichlorodiphenyltrichloroethane (DDT), was continually detected in wild fishes that showed abnormal gonad development such as intersex, little is known about the impact of p,p'-DDE exposure on gonad development in fishes. To survey the effects of p,p'-DDE on gonadal development and gene expressions, male juvenile (20-d post hatch) Japanese medaka (Oryzias latipes) was exposed to 1, 5, 20, and 100 microg/L p,p'-DDE for two months. Increased hepatosomatic index (HSI) and decreased gonadosomatic index (GSI) were found in the p,p'-DDE-treated groups. Intersex was found in 100 microg/L p,p'-DDE exposure group, as well as 100 ng/L 17alpha-ethynylestradiol (EE2) group. By quantitative real-time RT-PCR, it was found that gene expressions of vitellogenins (VTG-1, VTG-2), choriogenins (CHG-H, CHG-L), and estrogen receptor alpha (ER-alpha) in the liver of the fish were significantly up-regulated byp,p'-DDE exposure. VTG-1 and VTG-2 were recommended as the preferred biomarker for assessing anti-androgenic p,p'-DDE because they were the highest up-regulated among the genes and showed good dose-response relationship. The up-regulated ER-alpha suggested that a potential synergetic effect would occur when p,p'-DDE coexists with other ER-alpha-binding endocrine-disrupting chemicals (EDCs).
虽然在出现性腺发育异常如雌雄同体的野生鱼类中持续检测到二氯二苯三氯乙烷（DDT）的主要且最持久的代谢产物1,1-二氯-2,2-双（对氯苯基）乙烯（p,p'-DDE），但关于p,p'-DDE暴露对鱼类性腺发育的影响却知之甚少。为了研究p,p'-DDE对性腺发育和基因表达的影响，将雄性日本青鳉幼鱼（孵化后20天）暴露于1、5、20和100微克/升的p,p'-DDE中两个月。在p,p'-DDE处理组中发现肝体指数（HSI）升高而性腺体指数（GSI）降低。在100微克/升p,p'-DDE暴露组以及100纳克/升17α-乙炔基雌二醇（EE2）组中发现了雌雄同体现象。通过定量实时RT-PCR发现，p,p'-DDE暴露显著上调了鱼肝脏中卵黄蛋白原（VTG-1、VTG-2）、卵壳蛋白原（CHG-H、CHG-L）和雌激素受体α（ER-α）的基因表达。VTG-1和VTG-2被推荐作为评估p,p'-DDE抗雄激素作用的首选生物标志物，因为它们在这些基因中上调幅度最大且呈现出良好的剂量反应关系。ER-α上调表明当p,p'-DDE与其他与ER-α结合的内分泌干扰化学物质（EDC）共存时可能会产生潜在的协同效应。
