Di-(2-ethylhexyl) phthalate and Mono-(2-ethylhexyl) phthalate Inhibit Growth and Reduce Estradiol Levels of Antral Follicles In Vitro

摘要

Any insult that affects survival of ovarian antral follicles can cause abnormal estradiol production and fertility problems. Phthalate esters (PEs) are plasticizers used in wide range of consumer and industrial products. Exposure to these chemicals has been linked to reduced fertility in humans and animal models. Di-(2-ethylhexyl) phthalate (DEHP) and Mono-(2-ethylhexyl) phthalate (MEHP) decreases serum estradiol levels and aromatase (Arom) expression, prolongs estrous cycles, and causes anovulation in animal and culture models. These observations suggest PEs directly target antral follicles. We therefore tested the hypothesis that DEHP (1–100 µg/ml) and MEHP (0.1–10 µg/ml) directly inhibit antral follicular growth and estradiol production. Antral follicles from adult mice were cultured with DEHP or MEHP, and/or estradiol for 96 hrs. During culture, follicle size was measured every 24 hrs as a measurement of follicle growth. After culture, media was collected for measurement of estradiol levels and follicles were subjected to measurement of cylin-D-2 (Ccnd2), cyclin-dependant-kinase-4 (Cdk4), and Arom. We found that DEHP and MEHP inhibited growth of follicles and decreased estradiol production compared to controls at highest doses. DEHP and MEHP also decreased mRNA expression of Ccnd2, Cdk4, and Arom with highest dose. Addition of estradiol to the culture medium prevented the follicles from DEHP- and MEHP-induced inhibition of growth, reduction in estradiol levels, and decreased Ccnd2 and Cdk4 expression. Collectively, our results indicate that DEHP and MEHP may directly inhibit antral follicle growth via a mechanism that partially includes reduction in levels of estradiol production and decreased expression of cell cycle regulators.