草甘膦对青鳉鱼卵黄蛋白原的诱导及其潜在分子机理

Induction of vitellogenin gene expression in medaka exposed to glyphosate and potential molecular mechanism.

为了研究草甘膦潜在的雌激素效应,将1～3d的雌雄青鳉幼鱼暴露于不同浓度(0.2,2,20,200,2000μg/L)的草甘膦5周,发现雌雄鱼肝脏卵黄蛋白原(VTG I)基因表达分别在0.2,2,20μg/L浓度(雌鱼)和2,20,200μg/L浓度(雄鱼)下受到显著诱导,但在高浓度下(雌鱼,200μg/L和2000μg/L;雄鱼,2000μg/L)恢复到正常水平.草甘膦诱导雌激素效应的机理存在雌雄差异:雌鱼中雌激素效应主要由于草甘膦诱导了脑部FSH和性腺CYP19A基因,从而增加了雌激素合成能力.雄鱼中主要由于草甘膦抑制肝脏中雌激素代谢酶(CYP1A、CYP1B和CYP3A)而显示雌激素效应.

To demonstrate the estrogenic activities of glyphosate and clarify the underlying molecular mechanism, 1-3days old Japanese medaka were exposed to 0.2, 2, 20, 200, 2000μg/L of glyphosate for 5weeks. Transcription levels of vitellogenin （VTG I） and enzyme genes involved in 17β-E2biosynthesis and metabolism were measured by Q-RT-PCR. While glyphosate markedly up-regulated VTG transcription levels in both female and male fish, the upward trend was inhibited at the high glyphosate concentrations （at 200μg/L and 2000μg/L for female, at 2000μg/L for male）. The gender specific molecular mechanism was observed. In female fish, VTG induction would be due to the increase of transcription levels ofFSH gene in brain and CYP19A gene in the gonad, and therefore enhancing the biosynthesis of 17β-E2. However in male fish, the inhibited CYP1A, CYP1B and CYP3A transcription levels which would inhibit 17β-E2metabolism would be the reasonable explanation.