Di-(2-ethylhexyl) phthalate induced developmental abnormalities of the ovary in quail (Coturnix japonica) via disruption of the hypothalamic-pituitary-ovarian axis

An increasing number of epidemiologic studies show that women have a special exposure profile to phthalates, and the exposures have attracted attention regarding their potential health hazards. Here, we developed a model for studying the ovarian action of di-(2-ethylhexyl) phthalate (DEHP) and its major metabolite monoethylhexyl phthalate (MEHP). In vivo, treatment with DEHP (250, 500, and 1000 mg kg<^>-1) induced decreased thickness of ovarian granulosa cell layer and mitochondrial damage in quail, caused oxidative stress, interfered with the transcription of hypothalamic-pituitary-ovarian axis (HPOA) steroid hormone-related factors (increased transcription of StAR, 3 beta-HSD, P450scc, and LH and decreased transcription of 17 beta-HSD, P450arom, FSH, and ER beta), and blocked the secretion of steroid hormones (decreased FSH, E2, and T levels and increased LH, P, and PRL levels). In vitro, granulosa cells were cultured with MEHP (50, 100, and 200 mu M), activator of PPAR gamma (rosiglitazone, 50 mu M), or antagonist of PPAR gamma (GW9662, 10 mu M) for 24 h and gene and protein expression were analyzed by real time RT-PCR and western blot. Rosiglitazone, like MEHP, significantly decreased mRNA and protein levels of P450arom. Antagonist GW9662 partially blocked the suppression of P450arom by MEHP, suggesting that MEHP acts through PPAR gamma, but not exclusively. Our model shows that MEHP acts on granulosa cells in quail by stimu-lating PPARs, which leads to decreased gene and protein expression of P450arom. Therefore, the environmental endocrine disruptor DEHP and its major metabolite MEHP act through a receptor-mediated signaling pathway to inhibit the production of estradiol, interfere with the modulation of HPOA, suppress the synthesis of sex hor-mones, and cause sex hormone secretion disorders, resulting in severe toxicity in the female reproductive sys-tem. A framework for an adverse outcome pathway of DEHP/MEHP-induced ovarian toxicity was constructed, which can facilitate an improved understanding of the mechanism of female reproductive toxicity. (c) 2020 Elsevier B.V. All rights reserved.