Effects of in utero exposure to di-n-hexyl phthalate on the reproductive development of the male rat

Recently, the plasticizer di-n-hexyl phthalate (DnHP) has been demonstrated to be teratogenic and adversely affect the reproductive tract in male rat fetuses. This study was undertaken to determine the long-term effects of an in utero exposure to DnHP on the reproductive development of the male offspring. Di-2-ethylhexyl phthalate (DEHP), another phthalate ester known to disrupt the androgen-dependent sexual differentiation in the male rat, was used as a positive control. Pregnant Sprague-Dawley rats were administered DnHP or DEHP, by gavage on gestation Days 12–21, at doses of 0, 50, 125, 250, or 500 mg DnHP/kg-d and 500 mg DEHP/kg-d. DnHP had no significant effect on maternal body weight gain and pup weights during lactation. The proportion of live pups on postnatal day 1 was slightly, but not significantly, lower than control at 250 and 500 mg DnHP/kg-d. Male offspring displayed reduced anogenital distance on postnatal day 1 (PND) at 125 mg DnHP/kg-d and above, and areola/nipple retention before weaning and at adulthood at 250 and 500 mg DnHP/kg-d. At necropsy on PND 70–78 or PND 111–120, severe malformations of the reproductive tract were observed in young adult males at 125 mg DnHP/kg-d and higher doses. They mainly consisted of hypospadias, underdeveloped testis, and undescended testis. Additionally, histopathological examination revealed seminiferous tubule degeneration at the two high doses. Our results showed that prenatal exposure to DnHP caused permanent and dose-related alterations of the male rat reproductive development, with a similar profile as DEHP.