三泰隆藉由干擾青鱂魚體內荷爾蒙恆定而造成生殖及發育毒性效應之探討

Triadimenol Disrupts Homeostasis of Sex Hormone and Causes Reproductive and Developemental Toxicity in Medaka Fish (Oryzias latipes)

朱思泓(Szu-Hung Chu)

指導教授 ： 陳佩貞

國立臺灣大學/生物資源暨農學院/農業化學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.01350

摘要

三泰隆 (triadimenol) 為農業上常用之康唑類殺真菌劑 (conazole fungicides)，其化學結構穩定，在水中不易被水解，且半生期可達一年以上。因此，三泰隆可在環境水體被檢出 (ng/L-μg/L)，在台灣土壤及農業灌溉水中也常檢測出三泰隆殘留，顯示三泰隆有進入環境水體之風險。研究顯示多種康唑類殺真菌劑皆會抑制魚類生殖能力，然而目前為止針對三泰隆對魚類的生殖毒性之相關研究仍有限。本研究以青鱂魚 (medaka, Oryzias latipes) 為模式生物，分別針對胚胎、早期發育及成魚階段進行三泰隆暴露實驗，探討三泰隆對青鱂魚不同生命階段之內分泌干擾及生殖或發育相關毒性效應。青鱂魚成魚暴露於環境相關濃度 (10-300 μg/L) 之三泰隆21天後，其產卵量顯著下降，且胚胎 (F1) 受精率和孵化率也顯著下降，顯示其生殖能力明顯受到三泰隆之影響。三泰隆 (10-300 μg/L) 會抑制母魚性腺中性荷爾蒙生成基因 (如cyp19a、cyp17a、erβ)，及誘導肝臟中代謝性荷爾蒙之基因(如cyp3a38) 表達量，因而造成母魚血液中雌激素 (17β-estradiol, E2) 及雄激素 (testosterone, T) 濃度下降，以及生殖相關基因(如erα、vtg1、vtg2) 的表達量。三泰隆 (10-300 μg/L) 誘導公魚性腺中合成E2基因 (cyp19a) 之表達量，造成血液中E2濃度上升，且誘導公魚肝臟中代謝外來物質及性荷爾蒙之基因 (如cyp1a、cyp3a40) 表達量，因而造成T濃度下降，顯示公魚性荷爾蒙的恆定受到干擾。於早期發育階段暴露過三泰隆 (3-300 μg/L) 之青鱂魚成魚，母魚性腺及肝臟中與性荷爾蒙恆定及生殖相關的基因 (如vitellogenin, vtg2) 表達量皆受到干擾，且降低青鱂魚的生殖能力。此外，青鱂魚胚胎暴露三泰隆 (600-3000 μg/L) 後，胚胎孵化率顯著降低、胚胎孵化時間延遲，且造成胚胎死亡。綜合上述結果，環境相關濃度 (10-300 μg/L) 下之三泰隆暴露會干擾青鱂魚性腺及肝臟中與性荷爾蒙生合成及代謝相關基因表達量，因而破壞性荷爾蒙恆定，並降低青鱂魚產卵量、胚胎受精率及孵化率，造成生殖毒性。早期發育階段暴露環境相關濃度下之三泰隆也會影響之後的青鱂魚成長及成魚之生殖能力及相關基因表達量；較高濃度之三泰隆 (600-3000 μg/L) 會使青鱂魚胚胎孵化率降低、孵化時間延遲。因此，三泰隆存在環境中對水域生態之危害不容忽視。

關鍵字

三泰隆 ； 細胞色素P450酵素 ； 生殖毒性 ； 性荷爾蒙 ； 青鱂魚

並列摘要

Triadimenol is a triazole-containing conazole fungicides widely used in agriculture to prevent fungal infection. Conazoles may inhibit CYPs, potentially disrupt synthesis of sex steroid, and then cause reproductive toxicities in fishes. Since triadimenol residues have been frequently detected in soil, sediments and stream water worldwide, the ecological effect of triadimenol, especially its endocrine disruption potency, in fish should be evaluated. This study demonstrates the the adverse effects of triadimenol on the early life stages and reproduction in medaka fish (Oryzias latipes). First, results showed that triadimenol at high concerntration ranges (600-3000 μg/L) caused larvae mortality and delayed hatching in medaka embryos. Second, triadimenol at environmental concerntration (10-300 μg/L) decreased reproductive performance after the 21-day exposure, including decrease in fecundity, fertility and hatchability of F1 generation. After the 21-day exposure, plasma sex steroid (both testosterone [T] and 17β-estradiol [E2]) concentrations in females and T concentrations in males were reduced, but E2 concentrations in males were increased. Quantitative real-time PCR analyses revealed that triadimenol induced mRNA expression of hepatic hormone metabolism–related enzymes (eg. CYP1A and CYP3A) in both sex. Also, gene expression of steriodogenic exzymes including CYP19A and CYP17A were reduced in females, but these genes were induced in males. Furtheremore, gene expression of reproduction biomarker including ERα, VTG1 and VTG2 were reduced in females. Third, early life stage exposure from embryo to 28 day-post-hatch to triadimenol (3-300 μg/L) also decreased reproductive performance (fecundity, fertility and hatchability of F1 generation) of adults even though treated fish were transferred to clean water and reared until adulthood. Gene expression of steriodogenic CYPs, hormone metabolism–related CYPs and reproduction biomarkers in matured females showed a similar pattern as the previous 21 day’s reproduction assay. Overall, environmental relavent concerntration of triadimenol exposure interferes early sex development, and causes reproductive toxicity via disrupts homeostasis of sex hormones in medaka.

並列關鍵字

triadimenol ； cytochrome P450 enzymes (CYPs) ； reproduction toxicity ； sex hormones ； medaka (Oryzias latipes)

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