Disruption of sex-hormone levels and steroidogenic-related gene expression on Mongolia Racerunner (Eremias argus) after exposure to triadimefon and its enantiomers

- Triadimefon and its enantiomers can disturb the synthesis of sex steroid hormones.
- The biotoxicity of the two enantiomers is different and (S)-TF show higher biotoxicity than (R)- TF.
- The plasma testosterone level was elevated, while the estradiol level was reduced.
- The expression of steroidogenic-related genes was changed.

Triadimefon (TF) is a widely used chiral fungicide with one chiral centre and two enantiomers (TF1 and TF2). However, little is reported about the ecological toxicity of reptiles on an enantioselective level. TF is a potential endocrine disruptor that may interfere with sex steroid hormones, such as testosterone (T) and 17beta-estradiol (E2). In our study, the lizards Mongolia Racerunner (Eremias argus) were orally exposed to TF and its enantiomers for 21 days. Plasma sex steroid hormones and steroidogenic-related genes, including 17-beta-hydroxysteroid (hsd17β), cytochrome P450 enzymes (cyp19 and cyp17), and steroid hormone receptors (erα and Ar) were evaluated. After exposure, the plasma testosterone level in the 100 mg/kgbw group was elevated, while the oestradiol level was reduced. This phenomenon may be caused by the transformation of cyp19, which may inhibit the conversion of testosterone to oestradiol and affect sexual behaviour. In addition, the two enantiomers have different effects on hormone levels, which testified to the previously reported biotoxic dissimilarity between TF1 and TF2 in organisms. Furthermore, the cyp19 mRNA level in liver and gonad of the TF2 and TF group (100 mg/kgbw) were significantly down-regulated, while the cyp17 and hsd17β mRNA levels were up-regulated. The expression of erα and Ar mRNA levels were up-regulated in males but not in females, which may indicate that TF has sex differences on these two genes. As seen from the above results, TF and its enantiomers may have endocrine-disrupting effects on lizards (E. argus) by acting sensitively on sex steroid hormones and steroidogenic-related genes.