Evaluation of the effects of deltamethrin on the fetal rat testis.

Pregnant Sprague-Dawley rats were administered deltamethrin, at doses 0.1, 1, 5 or 10 mg kg(-1)  day(-1) , or di-n-hexyl phthalate (DnHP) (250 mg kg(-1)  day(-1) ), by gavage, from gestational day 13 to 19. Maternal toxicity was observed at 10 mg kg(-1)  day(-1) , as evidenced by transient clinical signs of neurotoxicity and reductions in body weight, body weight gain and corrected weight gain. Deltamethrin had no statistically significant effect on the incidence of post-implantation loss, fetal weight or anogenital distance in the male fetuses. Unlike DnHP, deltamethrin induced no changes in the expression of several genes involved in cholesterol transport or in the steroid synthesis pathway in the testes of gestational day 19.5 male fetuses (SRB1, StAR, P450scc, 3βHSD, P450 17 A1, 17βHSD). Fetal testicular levels of P450scc and P450 17 A1 protein were also unaffected by deltamethrin. No statistically significant differences were observed in the ex vivo fetal testicular production of testosterone and androstenedione after deltamethrin exposure, whereas DnHP markedly reduced these parameters. The deltamethrin metabolite, 3-phenoxybenzoic acid, was detected in amniotic fluid. In summary, our results demonstrate that in utero exposure to deltamethrin during the period of sexual differentiation had no significant effect on the testosterone synthesis pathway in the male rat fetus up to a maternal toxic dose.