Interaction of steroid receptor coactivators and estrogen receptors in the human placenta

Mechanisms of probiotic modulation of ovarian sex hormone production and metabolism: a review

Sex hormones play a pivotal role in the growth and development of the skeletal, neurological, and reproductive systems. In women, the dysregulation of sex hormones can result in various health complications such as acne, hirsutism, and irregular menstruation. One of the most prevalent diseases associated with excess androgens is polycystic ovary syndrome with a hyperandrogenic phenotype. Probiotics have shown the potential to enhance the secretion of ovarian sex hormones. However, the underlying mechanism of action remains unclear. Furthermore, comprehensive reviews detailing how probiotics modulate ovarian sex hormones are scarce. This review seeks to shed light on the potential mechanisms through which probiotics influence the production of ovarian sex hormones. The role of probiotics across various biological axes, including the gut-ovarian, gut-brain-ovarian, gut-liver-ovarian, gut-pancreas-ovarian, and gut-fat-ovarian axes, with a focus on the direct impact of probiotics on the ovaries via the gut and their effects on brain gonadotropins is discussed. It is also proposed herein that probiotics can significantly influence the onset, progression, and complications of ovarian sex hormone abnormalities. In addition, this review provides a theoretical basis for the therapeutic application of probiotics in managing sex hormone-related health conditions.

Biochemical Screening for Fetal Trisomy 21: Pathophysiology of Maternal Serum Markers and Involvement of the Placenta

It is now well established that maternal serum markers are often abnormal in fetal trisomy 21. Their determination is recommended for prenatal screening and pregnancy follow-up. However, mechanisms leading to abnormal maternal serum levels of such markers are still debated. Our objective was to help clinicians and scientists unravel the pathophysiology of these markers via a review of the main studies published in this field, both in vivo and in vitro, focusing on the six most widely used markers (hCG, its free subunit hCGβ, PAPP-A, AFP, uE3, and inhibin A) as well as cell-free feto-placental DNA. Analysis of the literature shows that mechanisms underlying each marker's regulation are multiple and not necessarily directly linked with the supernumerary chromosome 21. The crucial involvement of the placenta is also highlighted, which could be defective in one or several of its functions (turnover and apoptosis, endocrine production, and feto-maternal exchanges and transfer). These defects were neither constant nor specific for trisomy 21, and might be more or less pronounced, reflecting a high variability in placental immaturity and alteration. This explains why maternal serum markers can lack both specificity and sensitivity, and are thus restricted to screening.

Mono(2-ethylhexyl) phthalate induces transcriptomic changes in placental cells based on concentration, fetal sex, and trophoblast cell type

Phthalates are ubiquitous plasticizer chemicals found in consumer products. Exposure to phthalates during pregnancy has been associated with adverse pregnancy and birth outcomes and differences in placental gene expression in human studies. The objective of this research was to evaluate global changes in placental gene expression via RNA sequencing in two placental cell models following exposure to the phthalate metabolite mono(2-ethylhexyl) phthalate (MEHP). HTR-8/SVneo and primary syncytiotrophoblast cells were exposed to three concentrations (1, 90, 180 µM) of MEHP for 24 h with DMSO (0.1%) as a vehicle control. mRNA and lncRNAs were quantified using paired-end RNA sequencing, followed by identification of differentially expressed genes (DEGs), significant KEGG pathways, and enriched transcription factors (TFs). MEHP caused gene expression changes across all concentrations for HTR-8/SVneo and primary syncytiotrophoblast cells. Sex-stratified analysis of primary cells identified different patterns of sensitivity in response to MEHP dose by sex, with male placentas being more responsive to MEHP exposure. Pathway analysis identified 11 KEGG pathways significantly associated with at least one concentration in both cell types. Four ligand-inducible nuclear hormone TFs (PPARG, PPARD, ESR1, AR) were enriched in at least three treatment groups. Overall, we demonstrated that MEHP differentially affects placental gene expression based on concentration, fetal sex, and trophoblast cell type. This study confirms prior studies, as enrichment of nuclear hormone receptor TFs were concordant with previously published mechanisms of phthalate disruption, and generates new hypotheses, as we identified many pathways and genes not previously linked to phthalate exposure.

Oxytocin modulates steroidogenesis-associated genes and estradiol levels in the placenta

Oxytocin (OXT) plays a significant role during pregnancy, especially toward the end of pregnancy. Some studies have reported that OXT is involved in the stimulation of steroidogenesis in several organs. However, the effects of OXT on placental steroidogenesis have not yet been established. In this study, we investigated the regulation of steroid hormones and steroidogenic enzymes by OXT-associated signaling in vitro and in vivo. OXT increased the gene expression of steroidogenic enzymes, which convert pregnenolone to progesterone and dehydroepiandrosterone (DHEA) in vitro. In OXT-administered pregnant rats, pregnenolone and DHEA levels were significantly enhanced in the plasma and the expression of the enzymes synthesizing DHEA, testosterone, and estradiol (E2) was increased in placental tissues. Furthermore, OXT was found to affect placental cell differentiation, which is closely related to steroid hormone synthesis. After treatment of the pregnant rats with atosiban, an antagonist of the OXT receptor, the concentration of E2 in the plasma and the expression of E2-synthesizing enzyme were reduced. This regulation may be due to OXT-mediated differentiation, because OXT increases the expression of corticotropin-releasing hormone, which is a biomarker of placental cell differentiation. Our findings suggest that OXT contributes to maintaining pregnancy by regulating the differentiation of placental cells and steroidogenesis during pregnancy.

Evaluation of Different Doses of the Aromatase Inhibitor Letrozole for the Treatment of Ectopic Pregnancy and Its Effect on Villous Trophoblastic Tissue

Letrozole, an aromatase inhibitor, has recently been introduced as a favorable medical treatment for ectopic pregnancy. We aimed at evaluating the effects of different doses of letrozole for termination of ectopic pregnancy and study their effects on villous trophoblastic tissue. Sixty patients with undisturbed ectopic pregnancy were classified into three equal groups. Group I: the control group that contained women who underwent laparoscopic salpingectomy, Group II: patients who received letrozole (5 mg day⁻¹) for 10 days, and Group III: patients who received letrozole (10 mg day⁻¹) for 10 days. Subsequently, the β-hCG levels were determined on the first day and after 11 days of treatment. Group IV consisted of patients of GII and GIII; their β-hCG did not drop below 100 mIU/ml within 11 days, and underwent salpingectomy. Placental tissues from patients undergoing salpingectomy either from the control group or GIV were processed for the evaluation of estrogen (ER) and progesterone (PR) receptors, vascular endothelial growth factor (VEGF), and cleaved caspase 3 (CC-3) expression. Cases exposed to high dose letrozole 10 mg day⁻¹ resulted in a higher ectopic pregnancy resolution rate of 85% (17/20), while the resolution rate of the low dose letrozole-treated group (5 mg day⁻¹) was 65% (13/20), and also showed a significant reduction in β-hCG levels on the 11th day, 25.63 ± 4.29 compared to the low dose letrozole group 37.91 ± 7.18 (P < 0.001), Meanwhile, the letrozole-treated group GIV showed markedly reduced expression of ER, PR, and VEGF and a significant increase in the apoptotic index cleaved caspase-3 compared to the control group (P < 0.001). The utilization of letrozole at a dose of 10 mg day⁻¹ for medical treatment of ectopic pregnancy results in a high-successful rate without any severe side effects. Letrozole depriving the placenta of estrogen that had vascular supporting signals resulted in destroying the vascular network with marked apoptosis.

Expression and regulation of estrogen receptor 2 and its coregulators in mouse granulosa cells

The cooperative effects of estrogen and oocyte-derived paracrine factors (ODPFs) play critical roles in the normal development of ovarian follicles; however, the mechanism underlying this cooperation has not been well studied. The present study aimed to determine whether ODPFs affect estrogen signaling by regulating the expression of estrogen receptor (ESR) and its coregulators in mouse granulosa cells. Some transcripts encoding ESR coregulators were differentially expressed between cumulus and mural granulosa cells (MGCs). The transcript levels of ESR coregulators, including nuclear receptor corepressor 1 and activator 2, in cumulus cells were significantly suppressed by ODPFs; however, they increased when cumulus cell-oocyte complexes were treated with the transforming growth factor beta receptor I inhibitor, SB431542. Moreover, MGCs exhibited significantly higher ESR2 protein and transcript levels than those in cumulus cells. ODPFs promoted Esr2 expression in cumulus cells but had no effect on that in MGCs. Overall, regulation of the expression of ESR2 and its coregulators in cumulus cells by oocytes seems to be one of the mechanisms underlying estrogen-oocyte cooperation in well-developed antral follicles in mice.

Maternal exposure to bisphenol A induces fetal growth restriction via upregulating the expression of estrogen receptors

Bisphenol A (BPA) accumulation in the placenta leads to fetal growth restriction (FGR). Here we aimed to explore the effect and the underlying mechanism of BPA exposure on fetal development. ELISA was performed to measure estrogen levels in human placenta and BeWo cells. qRT-PCR and Western blotting were conducted to determine the expression of estrogen receptors (ERs), breast cancer resistance protein (BCRP), the key enzymes for ER synthesis, and DNA methyltransferases (DNMTs). Bisulfite-sequencing PCR analysis was performed to measure CpG methylation in ER genes. Flow cytometry was used to examine cell apoptosis. We found that human FGR placentae had significantly increased BPA and estrogen levels and decreased BCRP levels compared with healthy placentae. BPA downregulated BCRP expression via ERs, and BCRP silencing promoted ER expression in BeWo cells. Compared with vehicle treatment, BPA treatment significantly enhanced the expression of key enzymes for estrogen synthesis and ERs in BeWo cells. BPA treatment inhibited CpG methylation in ER genes, along with downregulated DNMT1 expression and upregulated DNMT3a and DNMT3b expression. BPA treatment significantly promoted BeWo cell apoptosis compared with vehicle treatment. Importantly, ER inhibitor ICI-182780 significantly reversed all the BPA-induced effects on BeWo cells. In conclusion, BPA promotes estrogen production and cell apoptosis in BeWo cells via upregulating ER expression, leading to FGR.

The Cannabinoid Delta-9-tetrahydrocannabinol Disrupts Estrogen Signaling in Human Placenta

Cannabis consumption is increasing worldwide either for recreational or medical purposes. Its use during gestation is associated with negative pregnancy outcomes such as, intrauterine growth restriction, preterm birth, low birth weight, and increased risk of miscarriage, though the underlying molecular mechanisms are unknown. Cannabis sativa main psychoactive compound, Δ9-tetrahydrocannabinol (THC) is highly lipophilic, and as such, readily crosses the placenta. Consequently, THC may alter normal placental development and function. Here, we hypothesize alterations of placental steroidogenesis caused by THC exposure. The impact on placental estrogenic signaling was examined by studying THC effects upon the enzyme involved in estrogens production, aromatase and on estrogen receptor α (ERα), using placental explants, and the cytotrophoblast cell model BeWo. Aromatase expression was upregulated by THC, being this effect potentiated by estradiol. THC also increased ERα expression. Actions on aromatase were ERα-mediated, as were abolished by the selective ER downregulator ICI-182780 and dependent on the cannabinoid receptor CB1 activation. Furthermore, the presence of the aromatase inhibitor Exemestane did not affect THC-induced increase in ERα expression. However, THC effects on ERα levels were reversed by the antagonists of CB1 and CB2 receptors AM281 and AM630, respectively. Thus, we demonstrate major alterations in estrogen signaling caused by THC, providing new insight on how cannabis consumption leads to negative pregnancy outcomes, likely through placental endocrine alterations. Data presented in this study, together with our recently reported evidence on THC disruption of placental endocannabinoid homeostasis, represent a step forward into a deeper comprehension of the puzzling actions of THC.

Pleiotropic genetic influence on birth weight and childhood obesity

Childhood obesity is a global public health problem. Understanding the molecular mechanisms that underlie early origins of childhood obesity can facilitate interventions. Consistent phenotypic and genetic correlations have been found between childhood obesity traits and birth weight (a proxy for in-utero growth), suggesting shared genetic influences (pleiotropy). We aimed to (1) investigate whether there is significant shared genetic influence between birth weight and childhood obesity traits, and (2) to identify genetic loci with shared effects. Using a statistical approach that integrates summary statistics and functional annotations for paired traits, we found strong evidence of pleiotropy (P < 3.53 × 10^–127) and enrichment of functional annotations (P < 1.62 × 10^–39) between birth weight and childhood body mass index (BMI)/obesity. The pleiotropic loci were enriched for regulatory features in skeletal muscle, adipose and brain tissues and in cell lines derived from blood lymphocytes. At 5% false discovery rate, 6 loci were associated with birth weight and childhood BMI and 13 loci were associated with birth weight and childhood obesity. Out of these 19 loci, one locus (EBF1) was novel to childhood obesity and one locus (LMBR1L) was novel to both birth weight and childhood BMI/obesity. These findings give evidence of substantial shared genetic effects in the regulation of both fetal growth and childhood obesity.

Levels of sex steroid hormones and their receptors in women with preeclampsia

BACKGROUND

Pregnant women have high serum concentrations of sex steroid hormones, which are major regulators of paracrine and autocrine responses for many maternal and placental functions. The main purpose of this study was to compare patients with preeclampsia and patients with uncomplicated pregnancies in terms of serum steroid hormones (estradiol [E2], progesterone [P4], dehydroepiandrosterone sulfate [DHEAS], and testosterone [T]) throughout pregnancy and the levels of cord blood and placental steroid receptors during the third trimester.

METHODS

Quantitative real-time reverse transcription PCR, western blotting, and immunohistochemistry were used to determine the levels of steroid hormones in the serum and cord blood and the placental levels of estrogen receptor-α (ERα), ERβ, androgen receptor (AR), and progesterone receptor (PR).

RESULTS

There were 45 women in the uncomplicated pregnancy group and 30 women in the preeclampsia group. Serum levels of T were greater and serum levels of E2 were reduced in the preeclampsia group, but the two groups had similar levels of P4 and DHEAS during the third trimester. Cord blood had a decreased level of DHEAS in the preeclampsia group, but the two groups had similar levels of P4, E2, and T. The two groups had similar placental mRNA levels of ERα, ERβ, AR, and PR, but the preeclampsia group had a higher level of ERβ protein and a lower level of ERα protein. Immunohistochemistry indicated that the preeclampsia group had a greater level of ERβ in the nucleus and cytoplasm of syncytiotrophoblasts and stromal cells.

CONCLUSIONS

Women with preeclampsia had lower levels of steroid hormones, estrogen, and ERα but higher levels of T and ERβ. These molecules may have roles in the pathogenesis of preeclampsia.

The Expression and Contribution of SRCs with Preeclampsia Placenta

The steroid hormones act by binding to their receptors and subsequently interacting with coactivators. Several classes of coactivators have been identified and shown to be essential in estradiol (E2) responsiveness. The major coregulators are the p160 steroid receptor coactivator (SRC) family. Although the function of SRCs in other organs has been well studied, it has not been thoroughly studied in the placenta. In addition, the correlation between preeclampsia (PE) and SRCs has not been examined previously. Therefore, we compared the expression patterns of SRCs in normal and PE placentas. In human PE placental tissues, SRC-1 mRNA, and protein levels were downregulated in the PE group. In addition, to assess the expression of SRCs in a PE environment, we used Reduced Uterine Perfusion Pressure (RUPP) model and placental cells were cultured in hypoxia condition. SRC-1 proteins were reduced in the placenta of PE-like rat RUPP model. Furthermore, SRCs proteins were significantly downregulated in hypoxia-grown placental cells. To examine the interaction between estrogen receptors (ERs) and SRC-1 protein, we performed co-immunoprecipitation. The interaction of SRC-1 with ERα was significantly stronger than that with ERβ. In PE placenta, the interaction of both ERα and ERβ with SRC-1 was stronger than that in normal placenta. In summary, our results demonstrate that expression levels of SRC-1, not SRC-2 and SRC-3, were decreased in hypoxia-induced PE placenta, which may further reduce the signaling of sex steroid hormones such as E2. The dysregulated signaling of E2 by SRC-1 expression could be associated with the PE placental symptoms of patients.

Steroid receptors and their regulation in avian extraembryonic membranes provide a novel substrate for hormone mediated maternal effects

Exposure of the vertebrate embryo to maternal hormones can have long-lasting effects on its phenotype, which has been studied extensively by experimentally manipulating maternal steroids, mostly androgens, in bird eggs. Yet, there is a severe lack of understanding of how and when these effects are actually mediated, hampering both underlying proximate and ultimate explanations. Here we report a novel finding that the embryo expresses androgen receptor (AR) and estrogen receptor (ERα) mRNA in its extraembryonic membranes (EMs) as early as before its own hormone production starts, suggesting a novel substrate for action of maternal hormones on the offspring. We also report the first experimental evidence for steroid receptor regulation in the avian embryo in response to yolk steroid levels: the level of AR is dependent on yolk androgen levels only in the EMs but not in body tissues, suggesting embryonic adaptation to maternal hormones. The results also solve the problem of uptake of lipophilic steroids from the yolk, why they affect multiple traits, and how they could mediate maternal effects without affecting embryonic sexual differentiation.

Hypoxia-induced Downregulation of SRC-3 Suppresses Trophoblastic Invasion and Migration Through Inhibition of the AKT/mTOR Pathway: Implications for the Pathogenesis of Preeclampsia

Preeclampsia (PE) is characterized by poor placentation, consequent on aberrant extravillous trophoblast (EVT) cell function during placental development. The SRC family of proteins is important during pregnancy, especially SRC-3, which regulates placental morphogenesis and embryo survival. Although SRC-3 expression in mouse trophoblast giant cells has been documented, its role in the functional regulation of extravillous trophoblasts and the development of PE remains unknown. This study found that SRC-3 expression was significantly lower in placentas from PE pregnancies as compared to uncomplicated pregnancies. Additionally, both CoCl₂-mimicked hypoxia and suppression of endogenous SRC-3 expression by lentivirus short hairpin RNA attenuated the migration and invasion abilities of HTR-8/SVneo cells. Moreover, we demonstrated that SRC-3 physically interacts with AKT to regulate the migration and invasion of HTR-8 cells, via the AKT/mTOR pathway. We also found that the inhibition of HTR-8 cell migration and invasion by CoCl₂-mimicked hypoxia was through the SRC-3/AKT/mTOR axis. Our findings indicate that, in early gestation, accumulation of HIF-1α inhibits the expression of SRC-3, which impairs extravillous trophoblastic invasion and migration by directly interacting with AKT. This potentially leads to insufficient uterine spiral artery remodeling and placental hypoperfusion, and thus the development of PE.

Expression of steroidogenic enzymes in human placenta according to the gestational age

Female sex steroid hormones, including estradiol (E2) and progesterone (P4), serve significant physiological roles in pregnancy. In particular, E2 and P4 influence placenta formation, maintain pregnancy and stimulate milk production. These hormones are produced by ovaries, adrenal glands and the placenta, of which the latter is a major endocrine organ during pregnancy. However, the mechanism of hormone production during pregnancy remains unclear. In the present study, the regulation of steroid hormones and steroidogenic enzymes was examined in human placenta according to gestational age. In human placental tissues, expression levels of steroidogenic enzymes were determined with reverse transcription‑quantitative polymerase chain reaction and western blotting. The mRNA and protein expression of CYP17A1, HSD17B3 and CYP19A1, which are associated with the synthesis of dehydroepiandrosterone (DHEA) and E2, was elevated at different gestational ages in human placenta. In addition, to evaluate the correlation between serum and placental‑produced hormones, steroid hormone levels, including pregnenolone (PG), DHEA, P4, testosterone (T) and E2, were examined in serum and placenta. Serum and placenta expression of DHEA and E2 increased with gestational age, whereas T and P4 were differently regulated in placenta and serum. To confirm the mechanism of steroidogenesis in vitro, placental BeWo cells were treated with E2 and P4, which are the most important hormones during pregnancy. The mRNA and protein expression of steroidogenic enzymes was significantly altered by E2 in vitro. These results demonstrated that concentration of steroid hormones was differently regulated by steroidogenic enzymes in the placenta depending on the type of the hormones, which may be critical to maintain pregnancy.

Nuclear Receptor Coactivator 2 Promotes Human Breast Cancer Cell Growth by Positively Regulating the MAPK/ERK Pathway

As a member of the p160 steroid receptor coactivator (SRC) family, nuclear receptor coactivator 2 (NCOA2) is known to play essential roles in many physiological and pathological processes, including development, endocrine regulation, and tumorigenesis. However, the biological function of NCOA2 in breast cancer is not fully understood. We found that the copy number of the NCOA2 gene was frequently amplified in four breast cancers datasets, varying from 6 to 10%, and the mRNA levels of NCOA2 were also upregulated in 11% of the sequenced cases/patients (TCGA provisional dataset). Next, we confirmed that NCOA2 silencing significantly suppressed cell proliferation in different breast cancer cell lines, by inducing cell cycle arrest and apoptosis. Mechanistically, whole-transcriptome sequencing (RNA-Seq) analysis showed that NCOA2 depletion leads to downregulation of the MAPK/ERK signaling cascade, possibly via downregulating NCOA2's downstream target RASEF. In conclusion, our results suggest NCOA2 as a potential target of therapeutics against breast cancer.

The accessible chromatin landscape during conversion of human embryonic stem cells to trophoblast by bone morphogenetic protein 4

Human embryonic stem cells (hESCs) exposed to the growth factor bone morphogenetic protein 4 (BMP4) in the absence of FGF2 have been used as a model to study the development of placental development. However, little is known about the cis-regulatory mechanisms underlying this important process. In this study, we used the public available chromatin accessibility data of hESC H1 cells and BMP4-induced trophoblast (TB) cell lines to identify DNase I hypersensitive sites (DHSs) in the two cell lines, as well as the transcription factor (TF) binding sites within the DHSs. By comparing read profiles in H1 and TB, we identified 17 472 TB-specific DHSs. The TB-specific DHSs are enriched in terms of "blood vessel" and "trophectoderm," consisting of TF motifs family: Leucine Zipper, Helix-Loop-Helix, GATA, and ETS. To validate differential expression of the TFs binding to these motifs, we analyzed public available RNA-seq and microarray data in the same context. Finally, by integrating the protein-protein interaction data, we constructed a TF network for placenta development and identified top 20 key TFs through centrality analysis in the network. Our results indicate BMP4-induced TB system provided an invaluable model for the study of TB development and highlighted novel candidate genes in placenta development in human.

Regulation of steroid hormones in the placenta and serum of women with preeclampsia

Preeclampsia (PE) is a pregnancy‑specific hypertensive syndrome that results in substantial maternal and fetal morbidity and mortality. The exact cause of PE has not been completely elucidate, although abnormal formation of the placenta has been considered. The placenta connects the developing fetus to the uterine wall, producing a large quantity of steroid hormones to maintain pregnancy. Although steroid hormones, particularly progesterone (P4) and estrogen (E2), in the serum of women with PE have been studied, steroidogenesis in the placenta has not well been established. The present study compared the concentrations of steroid hormones, including pregnenolone (PG), P4, dehydroepiandrosterone (DHEA), testosterone (T) and E2, in the serum and placenta of women with PE. PG, P4, DHEA and E2 concentrations tended to be decreased in PE serum and placentas, and the results were statistically significant for P4 and E2 in the serum. Quantification of genes associated with steroidogenesis in the placenta was performed, and the expression of the P4‑ and E2‑synthesizing enzymes testosterone 17‑β‑dehydrogenase 3 and 3 β‑hydroxysteroid dehydrogenase/δ5 4‑isomerase type 1 was reduced. Notably, aromatase, an enzyme required for the production of E2, was upregulated in the PE placenta, suggesting that steroidogenic enzymes may be dynamically regulated and may affect the symptoms of PE. In conclusion, the results of the present study suggested that the levels of steroid hormones, including P4 and E2, in the serum and placenta of women with PE are downregulated, which may be mediated by the regulation of steroidogenic enzyme expression in the PE placenta.

The regulation of oxytocin and oxytocin receptor in human placenta according to gestational age

Oxytocin (OXT) is a peptide hormone that plays a central role in the regulation of parturition and lactation. OXT signaling is mediated by OXT receptor (OXTR), which shows species- and tissue-specific expressions and gene regulation. In the present study, we examined the synthesis of OXT and OXTR in human placenta tissue according to gestational age. A total of 48 placentas were divided into early preterm, late preterm and term groups depending on gestational age, and expression of OXT and OXTR was evaluated. First, OXT and OXTR mRNA and protein were detected in normal placenta tissue via Q-PCR, Dot-blot and Western blot assay. Both OXT and OXTR levels in normal placenta increased gradually in the late stage of pregnancy, suggesting that local OXT may play a critical role in the function of the placenta. To determine the regulatory mechanism of OXT, placental BeWo cells were administrated estrogen (E2) or progesterone (P₄), and expression of OXT and OXTR was tested. The mRNA and protein levels of OXT and OXTR were upregulated by E2 but blocked by co-treatment with P₄ In order to confirm the estrogen receptor (ESR)-mediated signaling, we administrated ESR antagonists together with E2 to BeWo cells. As a result, both OXT and OXTR were significantly altered by ESR1 antagonist (MPP) while moderately regulated by ESR2 antagonist (PHTPP). These results suggest that OXT and OXTR are controlled mainly by E2 in the placenta via ESR1 and thus may play physiological functions in the human placenta during the late stage of pregnancy.