Acute Exposure to Di(2-Ethylhexyl) Phthalate in Adulthood Causes Adverse Reproductive Outcomes Later in Life and Accelerates Reproductive Aging in Female Mice
Humans are ubiquitously exposed to di(2-ethylhexyl) phthalate (DEHP), which is an environmental toxicant incorporated in consumer products. Studies have shown that DEHP targets the ovary to disrupt essential processes required for reproductive and nonreproductive health. Specifically, 10-day exposure to DEHP accelerates primordial follicle recruitment and disrupts estrous cyclicity in adult mice. However, it is unknown if these effects on folliculogenesis and cyclicity following acute DEHP exposure can have permanent effects on reproductive outcomes. Further, the premature depletion of primordial follicles can cause early reproductive senescence, and it is unknown if acute DEHP exposure accelerates reproductive aging. This study tested the hypothesis that acute DEHP exposure causes infertility, disrupts estrous cyclicity, alters hormone levels, and depletes follicle numbers by inducing atresia later in life, leading to accelerated reproductive aging. Adult CD-1 mice were orally dosed with vehicle or DEHP (20 μg/kg/day-500 mg/kg/day) daily for 10 days, and reproductive outcomes were assessed at 6 and 9 months postdosing. Acute DEHP exposure significantly altered estrous cyclicity compared to controls at 6 and 9 months postdosing by increasing the percentage of days the mice were in estrus and metestrus/diestrus, respectively. DEHP also significantly decreased inhibin B levels compared to controls at 9 months postdosing. Further, DEHP significantly increased the BAX/BCL2 ratio in primordial follicles leading to a significant decrease in primordial and total follicle numbers compared to controls at 9 months postdosing. Collectively, the adverse effects present following acute DEHP exposure persist later in life and are consistent with accelerated reproductive aging.