Prenatal exposure to di-(2-ethylhexyl) phthalate (DEHP) affects reproductive outcomes in mice

Di-(2-ethylhexyl) phthalate (DEHP) is a plasticizer that is often found in polyvinyl chloride products such as shower curtains, swimming pool liners, rain coats, car upholstery, wire sheathing, baby toys, garden hoses, tablecloths, wall coverings, medical tubing, and blood transfusion bags. DEHP can readily leach from products into the environment. This is of concern because DEHP exhibits endocrine disrupting activity and is a known testicular toxicant. While the effects of DEHP on the testes are well documented, little is known about the effects of DEHP on the ovary and female reproduction. Thus, I tested the hypothesis that prenatal DEHP exposure adversely affects ovarian development and reproductive outcomes in the female offspring of mice. To test this hypothesis, timed pregnant female CD-1 mice were orally dosed daily with tocopherol-stripped corn oil (vehicle control), 20µg/kg/day, 200µg/kg/day, 200mg/kg/day, 500mg/kg/day, or 750mg/kg/day DEHP from gestation day (GD) 11 until birth of the pups. On postnatal day (PND) 0, pups were counted, weighed, and sexed. On PNDs 1, 8, 21, and 60, at least 1 female pup from each litter was euthanized and her ovaries were harvested. At PND 8 and 21, one collected ovary from each pup was subjected to histological evaluation of primordial, primary, preantral, and antral follicle numbers. On PND 21, at least one pup from each litter was weaned and subjected to daily vaginal smears to monitor estrous cyclicity. When the females were three months old they were bred to proven-breeder males to evaluate their fertility based on whether the females became pregnant, time to pregnancy, and numbers of pups born. The results indicate that prenatal DEHP exposure did not significantly affect the numbers of pups born in each litter or their weights at birth, but does alter the male-to-female ratio in each litter. At PND 8, liver weight was significantly reduced in the 200mg/kg/day exposed animals compared to controls. At PND 21 and 60, uterine weight was significantly increased in animals exposed to 200µg/kg/day and 750mg/kg/day, respectively compared to controls. At PND 21, ovarian weight was significantly reduced in animals exposed to 20µg/kg/day compared to controls. At PND 21, prenatal DEHP exposure did not alter estrous cyclicity compared to controls. At PND 8, numbers of ovarian follicles were not significantly affected, however, at PND 21, numbers of preantral follicles were significantly increased in mice exposed to 200µg/kg/day and 500mg/kg/day DEHP in utero compared to controls. Interestingly, 60% of 500mg/kg/day treated animals were unable to become pregnant at three months of age and several DEHP treated animals took longer than 5 days to become pregnant and lost their pups. Collectively, these data suggest that prenatal exposure to DEHP may not affect the numbers or weights of pups at birth, pubertal onset, estrous cyclicity, or the numbers of follicles present in the ovary on PND 8. However, prenatal DEHP exposure does alter F1 sex-ratio, reduce liver weight at PND 8, increase uterine weight at PND 21, reduce ovarian weight at PND 21, and increase numbers of preantral follicles in PND 21 ovaries in mouse offspring. Further, prenatal DEHP exposure may cause breeding abnormalities