Pyrethroid pesticides, produced and used worldwide, have been reported to impair male reproductive function by reducing sperm count and sperm motility. They are divided into two types: type I pyrethroids including permethrin, etc. and type II pyrethroids including cypermethrin, fenvalerate, cyfluthrin, etc. Our previous study showed that fenvalerate and cypermethrin could reduce sperm motility in vitro. However, it is not clear whether permethrin and 3-phenoxybenzoic acid (3-PBA, the major metabolite of pyrethroids) affect sperm motility directly or indirectly by affecting spermatogenesis via interaction with androgens and/or their receptors. In this study, rat sperm suspensions were treated respectively with permethrin, cypermethrin and 3-PBA, at various concentrations (0, 1, 4, 16, or 64mmol/L) for various times (1, 2, or 4h). The motility parameters of sperm were analyzed with a computer-assisted sperm analysis (CASA) system. The differential effects of permethrin and cypermethrin on sperm motility patterns in vitro were also compared. Our study revealed that permethrin and cypermethrin could reduce sperm motility in vitro in a concentration- and time-dependent manner. Marked differences between the two pyrethroids were not found in this study. Moreover, 3-PBA did not reduce sperm motility directly at all concentrations and treatment periods. These results provide further evidence that permethrin and cypermethrin can directly affect mature rat sperm motility.
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