Ovulation Is Inhibited by Exposure to an Environmentally Relevant Phthalate Mixture via Disrupted Progesterone Production in Mouse Antral Follicles In Vitro.

Ovulation Is Inhibited by Exposure to an Environmentally Relevant Phthalate Mixture via Disrupted Progesterone Production in Mouse Antral Follicles In Vitro. Katie L. Land, Madison E. Lane, Patrick R. Hannon, Thomas E. Curry, Jr. University of Kentucky, Department of Obstetrics & Gynecology, Lexington, Kentucky Phthalates are chemicals that are used as solvents and plasticizers in many common consumer products such as cosmetics, food/beverage containers, medical tubing, etc. They are known endocrine-disrupting chemicals and reproductive toxicants, in which exposure could possibly inhibit ovulation and reduce fertility in women. The luteinizing hormone (LH) surge initiates the ovulatory process, which includes differentiating the preovulatory antral follicle into a progesterone producing corpus luteum (CL) via LH-induced increases in steroidogenic genes (Star, Cyp11a1, Hsd3b1 Parm1, Pgr). Progesterone signaling is essential for downstream processes required for ovulation and fertility. We hypothesized that an environmentally relevant phthalate mixture inhibits ovulation via disrupted progesterone production. Antral follicles were isolated from CD-1 mice and were cultured for 96hr in media supplemented with follicle-stimulating hormone to stimulate pre-ovulatory development, and treated with vehicle control (dimethylsulfoxide, DMSO) or phthalate mixture (PHTmix; 1-500μg/ml). The media was then replaced with maturation media ± hCG (an LH analog) to induce ovulation and treated with DMSO or PHTmix. Ovulation was assessed, and media and follicles/CLs were collected for progesterone measurements and analysis of gene expression, respectively, at time-points across the ovulatory period (0hr, 4hr, 11hr, 18hr, ovulation occurs at approximately 12hr) (n=3-10, p≤0.05). The PHTmix inhibited ovulation in a dose-dependent manner. Progesterone levels were decreased at 4hr and 11hr by the 1 and 500μg/ml doses but were increased at 4hr and 18hr by the 10μg/ml dose when compared to hCG controls. This altered progesterone production was mediated by alterations in expression of Star, Cyp11a1, and Parm1 compared to hCG. Further, altered progesterone levels reduced expression of progesterone mediated downstream regulators of ovulation (Il6, Adamts1) in comparison to hCG. Ultimately, these data suggest that phthalate exposure inhibits ovulation by altering progesterone steroidogenesis, and therefore potentially contributing to the negative health effects associated with infertility in women. Supported by P01HD071875, K99ES028748. 300 Word