Diisobutyl phthalate alters estradiol synthesis and expression of genes associated with epigenetic regulation and inflammation in bovine granulosa cells

Phthalates are widely used plasticizers that leach into the environment and have impacts on health and fertility of humans and animals. Among these ubiquitous environmental contaminants is diisobutyl phthalate (DiBP), a plasticizer known to affect fetal murine reproductive organs during prenatal exposure. However, studies investigating whether DiBP influences mammalian postpubertal ovarian function are lacking. In the present study, we tested the hypothesis that DiBP influences the function of bovine granulosa cells. Furthermore, we investigated the impacts of DiBP on expression of genes associated with ovarian steroidogenesis, DNA methylation, RNA methylation, histone acetylation, and inflammation. Bovine granulosa cells were treated with various doses of DiBP (0, 1, 10, and 100 ng/mL) combined with FSH or FSH plus IGF1 from 24 to 48 h. In combination with FSH, various doses of DiBP influenced the expression of genes associated with histone acetylation. In combination with FSH plus IGF1, DiBP at 10 ng/mL decreased synthesis of estradiol and expression of genes associated with RNA m6A methylation, RNA m5C methylation, and inflammation in comparison to the negative control (0 ng/mL DiBP) group. Taken together, these findings show that DiBP alters the function of granulosa cells of cattle, a mono-ovulatory species, at environmentally important doses and may impair mammalian fertility via inflammatory and epigenetic mechanisms.