摘要:
三唑醇(triadimenol,TN)是一种广泛使用的手性三唑类杀菌剂，它含有2个手性中心，4个手性对映体，其中，对映体A包括A1(R,S)和A2(S,R)，对映体B包括B1(R,R)和B2(S,S)。三唑醇被认为是一种潜在的内分泌干扰物，能够影响生物体内雌雄激素的合成。为了研究三唑醇不同对映体和外消旋体对爬行动物性腺系统影响的差异，以雄性丽斑麻蜥为实验动物，将外消旋体和4种对映体(100 mg·kg-1 bw)分别经口暴露给雄性蜥蜴28 d。外消旋体和(R,S)对映体暴露后蜥蜴的性腺体细胞指数(GSI)明显低于对照组。(S,R)、(R,S)和(S,S)显著抑制了性腺中性激素合成相关基因(cyp119a、cyp11a、cyp17、hsd-3β、hsd-17β、erα和ar)的表达量，同时降低了血液中睾酮(T)和雌二醇(E2)含量。(R,R)暴露对丽斑麻蜥体内的雌雄激素水平无明显影响。此外，相关性分析表明，外消旋体对性腺中性激素合成相关基因的影响与(R,S)具有较强的相关关系，说明(R,S)可能是外消旋体中生物活性和毒性最高的单体。研究表明，三唑醇对丽斑麻蜥性腺系统的毒性作用具有明显的对映选择性，这为手性农药对爬行动物的生态毒理学评价提供了重要依据。
Abstract:
Triadimenol (TN) is a widely used chiral triazole fungicide with two chiral centers and four enantiomers. Triadimenol was reported to disturb the gonadal system of several non-target organisms and has been regarded as a potential endocrine disruptor. To investigate the adverse effects of triadimenol enantiomers on reptile gonadal systems, in the present study, male Eremias argus was orally exposed to racemic triadimenol and its four enantiomers respectively at 100 mg·kg-1 bw for 28 d. During the experiment, no obvious change of body weight was observed in each group. The gonad somatic index (GSI) in racemate and (R,S) exposure groups was significantly decreased compared with the control group. (S,R), (R,S) and (S,S) enantiomers significantly down-regulated the mRNA levels of steroidogenic-related genes (cyp19a, cyp11a, cyp17, hsd-3β, hsd-17β, erα and ar) in lizard gonads and decreased the plasma concentrations of testosterone (T) and estradiol (E2). (R,R) enantiomer up-regulated the mRNA levels of cyp19a and hsd-3β, which may cause increased estradiol response in gonads. However, no statistically difference of plasma hormones (testosterone and estradiol) concentrations was observed between (R,R) group and the control group, which may be due to the compensatory function regulated by the negative feedback mechanism. Moreover, the correlation analysis revealed that the racemate exerted similar influence with (R,S) enantiomer toward lizard gonads, implicating that (R,S) may be the most active component among the four enantiomers. These results showed that triadimenol enantiomers stereoselectively disturbed the lizard gonadal system and provided important data for the ecotoxicological assessment of chiral triazole fungicides.
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