Induction of hepatic estrogen-responsive gene transcription by permethrin enantiomers in male adult zebrafish
Yuanxiang Jin, Wanyuan Wang, Chao Xu, Zhengwei Fu, Weiping Liu
Despite recent studies on enantioselectivity in acute aquatic toxicity and biodegradation of some pyrethroid pesticides, including permethrin (PM), enantiomer-specific estrogenic activity has been the subject of limited research. In this study, real-time quantitative RT-PCR was adopted to investigate induction of hepatic expression of mRNA of selected genes in male adult zebrafish after short-term exposure to PM enantiomers. The PM enantiomers were completely separated by a chiral HPLC column. The in vivo study found that a 2-day exposure to 100 ng/l PM racemate and its enantiomers was sufficient to stimulate transcription of two vitellogenin (vtg) genes, while 250 ng/l exposure significantly induced gene transcription in a pattern and content similar to that of the control (50 ng/l 17β-estradiol (E2)). Significant differences were detected between the enantiomers in induction of hepatic gene transcription. At exposure level of 500 ng/l, the response to the (−)-trans enantiomer was 2.6 and 1.8 times greater than the (+)-trans enantiomer based on zebrafish vtg1 and vtg2 mRNA induction (p < 0.05), respectively. Of the four enantiomers, the (−)-trans enantiomer showed the greatest estrogenic activity, with a relative activity 4-fold higher than the 50 ng/l E2 group. The results strongly suggested the occurrence of significant enantioselectivity in estrogenic activity of PM enantiomers. It would appear from our results and previous studies that using chiral pesticide as a single compound would increase the environmental risk of chronic toxicity, such as endocrine disruption, to humans and wildlife.
HPLC, Zebrafish, Permethrin, enantiomers, Gene expression, Enantioselectivity