Parabens Impair Mouse Antral Follicle Growth and Alter Ovarian Hormone and Gene Expression Similar to Phthalates

Benzyl paraben (BzP) and butyl paraben (BuP) are used as preservatives and antimicrobial agents in cosmetics, pharmaceuticals, and foods. BzP and BuP have been detected in urine, placental tissue, and ovarian follicular fluid and are understudied with regards to their endocrine activity, raising concerns on their impact to the reproductive system. We tested the hypothesis that BzP and BuP are toxic to the ovary and behave similarly to other structurally similar endocrine disrupting chemicals, such as phthalates and terephthalates, by altering hormone levels and impacting cell growth and gene expression in vitro. Untreated mouse antral follicles were exposed to vehicle, 0.1, 1, 10, or 100 g/mL BzP, BuP, or the BuP analog monobutyl terephthalate (MBuTP) for 96 hours. The highest dose of BzP and BuP were cytotoxic to follicles, suggesting that medium chain length hydroxybenzoates are more cytotoxic to the ovary than corresponding terephthalic acids. BzP significantly increased levels of estradiol and testosterone compared to control. BuP decreased follicle growth and disrupted expression of cell cycle regulators, similar to phthalates. The peroxisome proliferator-activated receptor gamma (PPARg)-transcriptionally controlled gene Fabp4 was significantly upregulated by both BzP and BuP, whereas MBuTP upregulated all four PPAR target genes and decreased follicle growth. Overall, BzP, BuP, and MBuTP disrupted hormone levels, follicle growth, and cell cycle progression, suggesting similarities in toxicity to phthalates and potential endocrine disruption. Further study should be done on the reproductive toxicity and endocrine disrupting effects of chemicals similar in structure to phthalates to reduce exposure to endocrine disruptors and inform design of safer replacements.