Research On Endocrine Disrupting Effects Of Permethrin Enantiomers In Zebrafish

Growing concerns over endocrine-disrupting chemicals(EDCs)including estrogens are due to their ability of mimicking the action of endogenous steroid hormones to interfere with the estrogen receptor(ER)mediated hormone response. Man-made pesticides are among the most common source of EDCs worldwide. Approximately 25%of currently used pesticides are chiral and this ratio is still increasing.However,little attention has been paid to enantioselectivity in the endocrine disrupting potential of enantiomers of chiral pesticides,although the racemates have been shown to be endocrine-disruptive.The aims of this research are:establish a model to detect the EDCs;use the model to evaluate enantioselectivity in the endocrine-disrupting potential of PM,which is a chiral synthetic pyrethroid.In the research of establishing the endocrine disrupting model,a real-time quantitative RT-PCR was adopted to investigate the expressions of three estrogen responsive genes,Vtg1,Vtg2,ERα,in different tissues of male adult zebrafish exposed to varying concentrations of 17β-estradiol(E2)for selected periods.The genes in the liver were significantly induced following exposure.The results suggest that Vtgs and ERαare sensitive biomarkers for determining the estrogenic effects of E2 and that the geness used in this research may serve as good biomarkers.In the research of the permethrin enantiomers,the PM enantiomers were completely separated by a chrial HPLC column,and real-time RT-PCR was adopted for invertigating induction of hepatic expression of mRNA of selected genes in male adult zebrafish after short-term exposure to permethrin enantiomers.The in vivo study found that a 2-day exposure to 500 ng/1 permethrin racemate and its enantiomers was sufficient to stimulate transcription of two vitellogenin genes and the ERαgene while the genes were induced in a pattern similar to that of the control(100 ng/l 17β-estradiol (E2)).Significant differences were detected between the enantiomers in the induction of hepatic gene transcription.The results strongly suggested the occurrence of significant enantioselectivity in estrogenic activity of permethrin enantiomers.It would appear from our results that using chiral pesticide as a single compound would increase the environmental risk of chronic toxicity.The enantioselective effects of trans-PM on the protein expression of male zebrafish liver were determined using 2D assay based on the results from gene expression research.The results showed that trans-PM enantiomers have enantioselectivity in the protein expressions.Based on the proteome analyse,our research suggests that further studies should be put on the SULT and MAPKAPK5 proteins,which are suspected to be associated with enantioselectivity of trans-PM.In conclution,enantioselectivity should be involved in evaluation of chiral chemicals,and further research on the mechanism of enantioselectivity is necessary.