The antiandrogenic activity of pyrethroid pesticides cyfluthrin and β-cyfluthrin

Abstract

Herein we describe in vivo and in vitro assays to investigate the suspected antiandrogenic activity of two pyrethroids, cyfluthrin and β-cyfluthrin. A stably transfected, androgen-responsive cell line, MDA-kb2, was used to determine the androgen receptor (AR) antagonistic effects of cyfluthrin and β-cyfluthrin in vitro, and the Hershberger assay was utilized to detect the antiandrogenic potential of the two pyrethroids in vivo. Moreover, we also compared the antiandrogenic activities of cyfluthrin and β-cyfluthrin to four structurally related pyrethoids: permethrin, cypermethrin, β-cypermethrin and bifenthrin. Our results show that cyfluthrin and β-cyfluthrin can block 5-dihydrotestosterone (DHT)-induced AR activity in MDA-kb2 cells. In the Hershberger assay, cyfluthrin, at doses of 18 and 54 mg/kg, and β-cyfluthrin, at a dose of 36 mg/kg, caused significant decrease in the weight of seminal vesicle, ventral prostate, dorsolateral prostate, LABC, Cowper's glands, though not significant in glans penis. β-Cyfluthrin at dose of 12 mg/kg decreased only the weight of seminal vesicle and had no effect on the other accessory sex tissues. The increase rank of antiandrogenic activity was: β-cypermethrin < permethrin < β-cyfluthrin < cypermethrin < cyfluthrin < bifenthrin < flutamide. In conclusion, cyfluthrin and β-cyfluthrin are moderate antiandrogenic chemicals in our experiments, and they elicit antiandrogenic effects at least partly by antagonizing AR.