Multigenerational Effects of an Environmentally Relevant Phthalate Mixture on Reproductive Parameters and Ovarian miRNA Expression in Female Rats

Abstract

Phthalates are endocrine-disrupting chemicals used in many consumer products. Our laboratory previously developed an environmentally relevant phthalate mixture consisting of six phthalates and found that it disrupted female fertility in mice. However, it was unknown if maternal exposure to the mixture affects reproductive parameters and ovarian post-transcription in the F1 and F2 generation of female rats. Thus, we tested the hypothesis that maternal exposure to the phthalate mixture affects folliculogenesis, steroidogenesis, and ovarian miRNA in the F1 and F2 generations of female rats. Pregnant female rats were divided into 4 groups and orally dosed daily from gestational day 10 to postnatal day 21 with corn oil (control group), 20 μg/kg/day, 200 μg/kg/day, or 200 mg/kg/day of the phthalate mixture. Maternal exposure to the phthalate mixture impaired folliculogenesis in the F1 and F2 generations of female rats and affected steroidogenesis in the F1 generation of female rats compared to control. Further, the phthalate mixture altered ovarian expression of some genes related to the cell cycle and steroidogenesis compared to control in the F1 and F2 generations of female rats. The mixture also increased in ovarian expression of rno-mir-184 that is involved with the oocyte maturation process. Collectively, our data show that maternal exposure to the phthalate mixture affects folliculogenesis and steroidogenesis in the F1 and F2 generations of female rats and alters ovarian miRNA expression in the F1 generation of female rats.

In silico investigation of the role of miRNAs in a possible developmental origin of prostate cancer in F1 and F2 offspring of mothers exposed to a phthalate mixture

“…According to our previous results, the rno‐miR184 and rno‐miR‐141‐3p expression profile on the ovary of directly exposed females (F1‐PND22) showed a different expression pattern compared to the ventral prostate of male offspring submitted to the same experimental protocol, at the same age, 15,18 showing that the epigenetic changes observed can be tissue, sex or phthalate mixture dependent 38,39 …”

“…35,36 Our previous results showed that maternal exposure to a phthalate mixture altered the expression of microRNAs in the ovary and ventral prostate of rat offspring. 15,18 Likewise, phthalate monoester mixture exposure modulated benign and tumor human prostate cells and increased the expression of the miR-184 and miR-141-3p in vitro. 37 The results presented here agreed with the microRNA sequencing profile presented by Scarano et al 15 and were correlated with some oncogenic targets by in silico analysis.…”

“…Endocrine disrupting chemicals (EDCs) such as phthalates modulate post‐transcriptional events, especially microRNA interaction and mRNA expression 35,36 . Our previous results showed that maternal exposure to a phthalate mixture altered the expression of microRNAs in the ovary and ventral prostate of rat offspring 15,18 . Likewise, phthalate monoester mixture exposure modulated benign and tumor human prostate cells and increased the expression of the miR‐184 and miR‐141‐3p in vitro 37 .…”

“…[14][15][16] Gestational exposure to a four-phthalate mixture increased the incidence of aberrations in gonads and harmed steroidogenesis in male and female offspring in pre-puberty and adulthood. 17 Previously, our group showed that the phthalate mixture (based on Reference 9) exposure during gestation and lactation caused dysfunction in ovarian folliculogenesis and steroidogenesis in F1 and F2 females 18 and increased the breast cancer susceptibility in F1 adult female rats after a chemical-induced carcinogenesis protocol. 19 In male offspring, in addition to altering phenotypic parameters in the prostate of prepubertal, adults and aged rats, 15,16 the phthalate mixture exposure from GD10 to PND21 modulated the transcriptome and miRNAome (especially the rno-miR-184 and rno-miR-141-3p) as well as the proteomic profile in offspring maternally exposed to the same set of phthalates.…”

“…33 Previously, we demonstrated that maternal exposure to a mixture of phthalates modulated the expression of rno-miR-184 and rno-miR-141-3p in male and female offspring immediately after exposure. 15,18 Here, we first investigated whether the changes in the expression of rno-miR-184 and rno-miR-141-3p observed in prepuberty would be maintained in adulthood, and later, in the second generation, considering the offspring of exposed fathers and mothers as well as the association with the prostate oncogenesis.…”