Exposure to a Three-Phthalate Mixture Tampers with Lipid Metabolic Processes in the Ovarian Antral Follicle Microenvironment

Abstract

Phthalates are a family of endocrine disrupting chemicals with ubiquitous exposure in humans. Dibutyl phthalate (DBP), di-2-ethylhexylphthalte (DEHP), and benzyl butyl phthalate (BBP) are used in personal care, medical, and pharmaceutical products. Antral follicles within the ovary are essential for ovulation and downstream fertilization and pregnancy. DBP, BBP, and DEHP are known to associate with decreased antral follicle counts in women and inhibit mouse antral follicle growth and ovulation in vitro. However, the specific mechanism of toxicity driving these outcomes is largely unknown. Therefore, the aim of the studies outlined in this dissertation address this gap in knowledge by investigating the effects of a three-phthalate mixture on the antral follicle microenvironment. Proteome and lipidome profiling of antral follicles from CD-1 female mice exposed in-vivo to an environmentally relevant dose of a mixture of DBP, BBP, and DEHP revealed that lipid metabolic processes are targeted. Lipidomic analysis of serum and liver tissues from matched mice highly suggested that lipid changes are not occurring through a systemic mechanism. While in vitro treatment of DBP, BBP, DEHP on mouse primary granulosa cells highlighted the ability of this mixture of phthalates to modulate expression of enzymes through activation of peroxisome proliferator activated receptor gamma (PPAR). Overall, these studies demonstrate that phthalates target the antral follicle microenvironment resulting in increased saturated free fatty acid levels, reduced shuttling of carnitines for beta oxidation, and diminished triglyceride stores, which is likely occurring through activated intracellular PPAR and secondary signaling mechanisms.