RESUMO
Previously, we have shown that perinatal exposure to a glyphosate-based herbicide (GBH) induces implantation failures in rats. Estrogen receptor alpha (ERα) is critical for successful implantation. ERα transcription is under the control of five promoters (E1, OT, O, ON, and OS), which yield different transcripts. Here, we studied whether perinatal exposure to a GBH alters uterine ERα gene expression and prompts epigenetic modifications in its regulatory regions during the preimplantation period. Pregnant rats (F0) were orally treated with 350â¯mg glyphosate/kg bw/day through food from gestational day (GD) 9 until weaning. F1 females were bred, and uterine samples were collected on GD5 (preimplantation period). ERα mRNA levels and its transcript variants were evaluated by RT-qPCR. Enzyme-specific restriction sites and predicted transcription factors were searched in silico in the ERα promoter regions to assess the methylation status using the methylation-sensitive restriction enzymes-PCR technique. Post-translational modifications of histones were studied by the chromatin immunoprecipitation assay. GBH upregulated the expression of total ERα mRNA by increasing the abundance of the ERα-O transcript variant. In addition, different epigenetic changes were detected in the O promoter. A decrease in DNA methylation was observed in one of the three sites evaluated in the O promoter. Moreover, histone H4 acetylation and histone H3 lysine 9 trimethylation (H3K9me3) were enriched in the O promoter in GBH-exposed rats, whereas H3K27me3 was decreased. All these alterations could account for the increase in ERα gene expression. Our findings show that perinatal exposure to a GBH causes long-term epigenetic disruption of the uterine ERα gene, which could be associated with the GBH-induced implantation failures.
Assuntos
Implantação do Embrião/genética , Epigênese Genética , Receptor alfa de Estrogênio/genética , Glicina/análogos & derivados , Herbicidas/toxicidade , Útero/metabolismo , Animais , Sítios de Ligação , Simulação por Computador , Metilação de DNA/efeitos dos fármacos , Metilação de DNA/genética , Implantação do Embrião/efeitos dos fármacos , Epigênese Genética/efeitos dos fármacos , Receptor alfa de Estrogênio/metabolismo , Feminino , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Genoma , Glicina/toxicidade , Histonas/metabolismo , Regiões Promotoras Genéticas , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos Wistar , Fatores de Transcrição/metabolismo , Transcrição Gênica/efeitos dos fármacos , Útero/efeitos dos fármacos , GlifosatoRESUMO
In this study, we investigated whether neonatal exposure to a glyphosate-based herbicide (GBH) alters the reproductive performance and the molecular mechanisms involved in the decidualization process in adult rats. Newborn female rats received vehicle or 2 mg/kg/day of a GBH on postnatal days (PND) 1, 3, 5 and 7. On PND90, the rats were mated to evaluate (i) the reproductive performance on gestational day (GD) 19 and (ii) the ovarian steroid levels, uterine morphology, endometrial cell proliferation, apoptosis and cell cycle regulators, and endocrine pathways that regulate uterine decidualization (steroid receptors/COUP-TFII/Bmp2/Hoxa10) at the implantation sites (IS) on GD9. The GBH-exposed group showed a significant increase in the number of resorption sites on GD19, associated with an altered decidualization response. In fact, on GD9, the GBH-treated rats showed morphological changes at the IS, associated with a decreased expression of estrogen and progesterone receptors, a downregulation of COUP-TFII (Nr2f2) and Bmp2 mRNA and an increased expression of HOXA10 and the proliferation marker Ki67(Mki67) at the IS. We concluded that alterations in endometrial decidualization might be the mechanism of GBH-induced post-implantation embryo loss.
Assuntos
Glicina/análogos & derivados , Herbicidas/toxicidade , Efeitos Tardios da Exposição Pré-Natal/fisiopatologia , Reprodução/fisiologia , Animais , Animais Recém-Nascidos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Decídua/efeitos dos fármacos , Decídua/crescimento & desenvolvimento , Endométrio/efeitos dos fármacos , Endométrio/crescimento & desenvolvimento , Feminino , Glicina/toxicidade , Gravidez , Efeitos Tardios da Exposição Pré-Natal/induzido quimicamente , Ratos , Reprodução/efeitos dos fármacos , Útero/efeitos dos fármacos , Útero/crescimento & desenvolvimento , GlifosatoRESUMO
Neonatal exposure to a low dose of endosulfan may disrupt the expression of Wnt7a and ß-catenin during uterine development leading to the failure of uterine functional differentiation during implantation. New-born female Wistar rats were treated with vehicle, endosulfan (600 µg/kg/d, E600) or diethylstilbestrol (0.2 µg/kg/d, DES) on postnatal days (PNDs) 1, 3, 5 and 7. Subsequently, uterine histomorphology and the protein expression of Wnt7a and ß-catenin were evaluated on PND8, PND21 and gestational day (GD) 5 (pre-implantation period). In the E600 rats, Wnt7a and ß-catenin protein expression was increased in the epithelium on PND8, and Wnt7a expression was decreased in the endometrial glands on PND21. On GD5, the number of uterine glands was decreased in the E600-and DES-treated rats. In addition, Wnt7a expression was decreased in all uterine compartments, and ß-catenin expression was increased in the luminal and glandular epithelia of the E600-and DES-treated rats. Disruption of Wnt7a and ß-catenin uterine expression in the prepubertal and adult females altered the uterine preparation for embryo implantation, which could be associated with the subfertility triggered by endosulfan.