Expression Of Estrogen Receptor Subtypes Research Articles

Phytoestrogen-like effect of Siwu Decoction and molecular mechanism: based on network pharmacology and in vivo experiment

This study explored the phytoestrogen-like effect of Siwu Decoction(SWD) and the estrogen receptor(ER)-mediated molecular mechanism based on network pharmacology and in vivo experiment. The active components and targets of SWD were retrieved from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP), and related targets of "estrogen" from GeneCards and Online Mendelian Inheritance in Man(OMIM). Cytoscape and STRING were employed to construct the protein-protein interaction(PPI) network and "chemical component-target-disease" network and core targets were identified, followed by Gene Ontology(GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway enrichment of the core targets by R software. For the in vivo experiment, the 22-day-old SD female rats were treated(ig) with SWD for 4 days. Via hematoxylin-eosin(HE) staining, the morphological changes of rat uterus were observed. Reverse transcriptase-polymerase chain reaction(RT-PCR) was performed to detect mRNA expression of ER subtypes, estrogen-related targets, and the main regulatory factors in the estrogen signaling pathway. The results indicated 74 targets of SWD exerted phytoestrogen-like effect. KEGG pathway enrichment result suggested that estrogen signaling pathway was closely related to the phytoestrogen-like effect of SWD. Rats in SWD group demonstrated significantly thickened endometrium and significantly decreased expression of ERα, ERβ, and G protein-coupled estrogen receptor(GPER) mRNA in ovarian tissue. In addition, significant lowering of ERα and ERβ mRNA expression and significant rise of GPER mRNA expression in uterine tissue were observed in the SWD group. The expression of mitogen-activated protein kinase(MAPK) p38, MEK1/2 and extracellular signal-regulated kinase(ERK)1/2 mRNA was significantly low while that of epidermal growth factor receptor(EGFR) mRNA was significantly high in both ovarian and uterine tissues of SWD group compared with those in the control group. In conclusion, the phytoestrogen-like effect of SWD is closely related to the estrogen signaling pathway. The result lays a basis for revealing molecular mechanism of SWD in the treatment of gynecological diseases.

Differential expression of estrogen receptor subtypes in ovarian high-grade serous carcinoma and clear cell carcinoma.

PurposeTo investigate the role of estrogen receptors (ERs) in high‐grade serous carcinoma (HGSC) and clear cell carcinoma (CCC) of the ovary and evaluate ERs as prognostic biomarkers for ovarian cancer.MethodsThis study included 79 patients with HGSC (n = 38) or CCC (n = 41) treated at our institution between 2005 and 2014. Immunohistochemistry examined protein expression of ERα, ERβ, and G protein‐coupled estrogen receptor‐1 (GPER‐1); relationships between ERα, ERβ, and GPER‐1 with patient survival were evaluated. Additionally, cell proliferation assay and phosphokinase proteome profiling were performed.ResultsIn HGSC patients, expression of ERα, cytoplasmic GPER‐1, or nuclear GPER‐1 was associated with poor progression‐free survival (PFS) (P = .041, P = .010, or P = .013, respectively). Cytoplasmic GPER‐1 was an independent prognostic factor for PFS in HGSC patients (HR = 2.83, 95% CI = 1.03‐9.16, P = .007). ER expressions were not associated with prognosis in CCC patients. GPER‐1 knockdown by siRNA reduced the cells number to 60% of siRNA‐control‐treated cells (P < .05), and GPER‐1 antagonist, G‐15 inhibited two HGSC cell lines proliferation (KF and UWB1.289) in a dose‐dependent manner. Phosphoprotein array revealed that GPER‐1 silencing decreased relative phosphorylation of glycogen synthase kinase‐3.ConclusionsHigh GPER‐1 expression is an independent prognostic factor for PFS in HGSC patients, and GPER‐1 may play a role in HGSC cell proliferation.

Genistein inhibits amyloid peptide 25-35-induced neuronal death by modulating estrogen receptors, choline acetyltransferase and glutamate receptors

PurposeTo explore genistein, the most active component of soy isoflavones, on viability, expression of estrogen receptor (ER) subtypes, choline acetyltransferase (ChAT), and glutamate receptor subunits in amyloid peptide 25-35-induced hippocampal neurons, providing valuable data and basic information for neuroprotective effect of genistein in Aβ25-35-induced neuronal injury. MethodsWe established an in vitro model of Alzheimer's disease by exposing primary hippocampal neurons of newborn rats to amyloid peptide 25–35 (20 μM) for 24 h and observing the effects of genistein (10 μM, 3 h) on viability, expression of ER subtypes, ChAT, NMDA receptor subunit NR2B and AMPA receptor subunit GluR2 in Aβ25-35-induced hippocampal neurons. ResultsWe found that amyloid peptide 25–35 exposure reduced the viability of hippocampal neurons. Meanwhile, amyloid peptide 25–35 exposure decreased the expression of ER subtypes, ChAT and GluR2, and increased the expression of NR2B. Genistein at least partially reversed the effects of amyloid peptide 25–35 in hippocampal neurons. ConclusionGenistein could increase the expression of ChAT as a consequence of activating estrogen receptor subtypes, modulating the expression of NR2B and GluR2, and thereby ameliorating the status of hippocampal neurons and exerting neuroprotective effects against amyloid peptide 25–35. Our data suggest that genistein might represent a potential cell-targeted therapy which could be a promising approach to treating AD.

Mechanism of traditional Chinese medicine balancing Yin-Yang by targeting ERα/ERβ and its application in treatment of menopausal syndrome

The coordination and unification of Yin and Yang are the basis of normal human life activities. Along with the age growth and aging of the body, women will suffer from menopausal syndrome during menopause. In addition to the significant changes in the genital system, there are also pathological manifestations in estrogen target points including bone, nerve and cardiovascular systems, due to the imbalance of Yin and Yang. Besides the insufficiency of estrogen, the main cause of menopausal syndrome is the changes in the response of target organs to estrogen. In other words, the biological effects mediated by estrogen receptor(ER) alpha and beta subtypes in target cells are often different or even opposite; the changes of expression level and ratio of ERα and ERβ are also important causes for the abnormal estrogenic effects in target organs and the imbalance of Yin and Yang of the body. Therefore, on one hand, the therapeutic mechanism of drugs is ER-mediated estrogenic effect. On the other hand, the drugs have a regulatory effect on ER subtype expression in target cells and Yin-Yang state in target organs and even organisms, so as to cause further changes in the response of target cells to estrogen or estrogenic components, and exert its therapeutic effects. This paper reviews the pharmacological mechanism of gynecological traditional Chinese medicine in harmonizing Yin and Yang in estrogen-positive target cells and the clinical efficacy in the following aspects, including estrogen and its mechanism, the estrogenic effect of ER in traditional Chinese medicine and the mechanism of ER subtype in balancing Yin and Yang and mediating and regulating the main target tissues in menopausal syndrome treatment.

SAT-LB035 The G Protein-Coupled Estrogen Receptor GPER Plays a Dominant Role in Human Islet Cell Proliferation upon High Glucose

Estrogen exerts its effects through genomic and rapid extra-nuclear signaling pathways. The classic estrogen receptors, ERα and ERβ have demonstrated favorable effects on beta-cell function and survival but their clinical utility has been questioned owing to oncogenic potential and concerns regarding feminizing effects in men. Recent work indicates, however, that the G-protein coupled estrogen receptor (GPER), expressed in pancreatic islet cells retains the estrogenic beta-cell protective effects, without the shortcomings of the classic ERs. GPER activation enhances glucose stimulated insulin secretion, reduces islet apoptosis upon insult and has been implicated in beta-cell mass expansion during pregnancy in rodent islets. Since GPER can thus comprise an attractive treatment target in hyperglycemic states we examined the effects of the three ERs on proliferation of human pancreatic islets in the presence of hyperglycemia. Islets from eight non diabetic human donors (6 males and 2 females) were grown at glucose concentrations of either 11mM or 25mM for 24 hours and examined for DNA synthesis after treatment with E2 (at increasing concentrations) and with specific agonists for ERα, ERβ and GPER (PPT 10nM, DPN 10nM and G1 100nM, respectively). At a glucose concentration of 11mM, E2 and all three ER agonists induced a significant ~2 folds increase in 3[H]-thymidine incorporation. However, under still higher glucose conditions (HG; 25mM) only the GPER agonist G1 increased proliferation equipotently (~2.5 folds; p<0.001), while stimulation of ERα and ERβ enhanced proliferation by ~1.4 folds only (p<0.05 for ERα). In search for an explanation for the differential effects, we examined expression of the three ERs at glucose concentrations of 11mM and 25mM, by qRT-PCR. High glucose reduced expression of ERα and ERβ (by 15%; p<0.05) but not the expression of GPER. Although beta-cells comprise the majority (~70%) of cells in human islets, expression of GPER has also been demonstrated in alpha and delta cells and thus the full effect of hyperglycemia on GPER expression in beta-cells may be masked. Hence, extending previous reports, our results suggest that GPER may comprise an attractive target in the therapy of human diabetes and point to the phenomenon of species specificity regarding effects of glucose on estrogen receptor subtype expression and activity. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. s presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.

Estrogen receptor subtype expression and regulation is altered in papillary thyroid cancer after menopause

Estrogen receptors can regulate growth in papillary thyroid cancer and may affect prognosis after menopause. This study examines changes of estrogen receptor subtype ratio expression in papillary thyroid cancer cell lines derived from pre- and postmenopausal women. Cells were harvested from papillary thyroid cancer and non-papillary thyroid cancer thyroid tissue (control) from pre- (n = 9) and postmenopausal women (n = 11). Protein expression of estrogen receptor α, estrogen receptor β, and phosphorylated extracellular signal-regulated kinase and protein kinase B were analyzed. Matrix metalloproteinase-2 activity was determined as a measure of tumor invasiveness. Mitochondrial retrograde signaling was altered with ethidium bromide to determine its effect on estrogen receptor α protein expression. Estrogen receptor α expression was increased in postmenopausal papillary thyroid cancer cells compared with controls but was unchanged in premenopausal papillary thyroid cancer. Estrogen receptor β expression did not change in either group. Increased matrix metalloproteinase-2 activity was observed only in postmenopausal papillary thyroid cancer. Premenopausal papillary thyroid cancer cells demonstrated increased extracellular signal-regulated kinase and unchanged protein kinase B activation. Conversely, postmenopausal papillary thyroid cancer cells had decreased extracellular signal-regulated kinase and increased protein kinase B activation. Ethidium bromide treatment resulted in increased estrogen receptor α protein expression only in premenopausal papillary thyroid cancer cells. Increased estrogen receptor α expression may be involved in papillary thyroid cancer aggressiveness after menopause. This process may be regulated by differential activation of intracellular pathways and differing sensitivities to mitochondrial signaling regulation.

Differential expression of estrogen receptor subtypes and variants in ovarian cancer: effects on cell invasion, proliferation and prognosis

BackgroundDue to the presence of both classical estrogen receptor (ERα) and another ER subtype (ERβ) in ovarian cancer, hormonal treatment is an attractive option. However, response to tamoxifen in ovarian cancer is modest. The presence of ERβ variants further complicated the issue. We have recently shown that specifically targeting ER subtypes using selective ER modulators showed opposing functions of ER subtypes on cell growth. In the present study, the clinical significance of ERα and ERβ variants (β1, β2 and β5) and the functional effects of ERβ2 and ERβ5 in ovarian cancer was investigated.MethodsERα, ERβ1, ERβ2 and ERβ5 expression were evaluated by immunohistochemistry in 106 ovarian cancer tissues. The association between ERs expression and clinicopathological parameters or prognosis was analyzed. Ectopic expression of ERβ2 and ERβ5 followed by functional assays were performed in ovarian cancer cell lines in order to detect their effects on cell invasion and proliferation.ResultsWe found significantly higher nuclear (n)ERα and nERβ5 and lower cytoplasmic (c)ERα expression in advanced cancers. Significantly lower ERβ1 expression was also detected in high grade cancers. Significant loss of nERα and cERβ2 expression were observed in clear cell histological subtypes. Higher nERβ5 and lower cERβ5 expression were associated with serous/clear cell subtypes, poor disease-free and overall survival. Positive cERα and higher cERβ1 expression were significantly associated with better disease-free and overall survival. Furthermore, we found nERβ5 as an independent prognostic factor for overall survival. Functionally, overexpression of ERβ5 enhanced ovarian cancer cell migration, invasion and proliferation via FAK/c-Src activation whereas ERβ2 induced cell migration and invasion.ConclusionsSince tamoxifen binds to both ERα and ERβ1 which appear to bear opposing oncogenic roles, the histotypes-specific expression pattern of ERs indicates that personalized treatment for women based on ERs expression using selective estrogen receptor modulators may improve response rate. This study also suggests nERβ5 as a potential prognostic marker and therapeutic target in ovarian cancer.

Estrogen Receptor Subtype Expression is Altered in the Hen Model of Ovarian Cancer

There is growing evidence that estrogens may promote tumor progression, including ovarian tumors. Estrogens exert their actions in tissues through two different receptor subtypes (ESR1 and ESR2). Studies have shown that hens develop ovarian cancer spontaneously, therefore providing a suitable animal model for the disease. Our aim was to determine the expression of mRNA and protein of the estrogen receptor subtypes in ovaries of normal hens and ovaries from hens with ovarian cancer. Ovarian tissue from normal hens and hens with ovarian cancer was collected for quantitative real-time PCR and immunofluorescence analysis. Quantitative real-time PCR results showed that the relative mRNA expression of ESR1 and the ratio of ESR1/ESR2 are significantly greater from hens with ovarian cancer when compared to normal ovarian tissue. Immunofluorescence analysis showed differential ESR1 and ESR2 protein expression in ovarian tissue sections from normal hens and hens with ovarian cancer, with results parallel to the mRNA data. There was no significant difference in plasma estradiol levels between normal hens and hens with ovarian cancer. These data suggest an increase in downstream estrogen-mediated actions in chicken ovarian tumors and, indeed, microarray analysis reveals a functionally significant estradiol-signaling pathway in chicken ovarian tumors. Interestingly, expression of a putative ovarian tumor suppressor, EPB41L3, is down regulated in this pathway. Taken together, these results suggest that, in the hen, ESR1 may be mediating a proliferative response in ovarian cancer cells. Although additional studies are required to define the role of ESR1 in tumor formation in the hen, these results support the utility of the hen for testing possible endocrine therapies.

Isolation of estrogen receptor subtypes and vitellogenin genes: expression in female Chalcalburnus tarichi.

Reproductively arrested gonadal development has been previously described in the teleost pearl mullet (Chalcalburnus tarichi, Cyprinidae) from Van Edremit Gulf of Lake Van, Turkey. Oocyte development in some females was arrested at the previtellogenic stage, while gonadosomatic index (GSI) and plasma 17β-estradiol (E2) level were low. A subset of the females was found to have normal ovaries and relatively higher plasma E2 and GSI. These two groups were termed reproductively arrested (RA) and reproductively non-arrested (RN) females. In this study, we cloned estrogen receptor (ER) isoforms (ERα, ERβ1 and ERβ2) and vitellogenin (Vtg), and their mRNA levels were measured in RA and RN fish tissues. C. tarichi ERs fell in the same clade with other fish ERs and ERα and ERβ1 had 97% and 98% identity with the roach (Rutilus rutilus) ERs, respectively. Both Vtg and ER isoforms' mRNA abundance were higher in the liver than in the ovary and hypothalamus (liver>ovary>hypothalamus). The level of ERα mRNA was significantly lower in the liver, ovary and brain of RA fish than in the RN fish tissues. ERβ1 mRNA levels were not different in the liver and ovary from RA and RN fish while ERβ2 expression significantly increased in the liver and ovary from RA fish. All ER subtype expression was found to be lower in the brain from RA fish than RN fish. The level of Vtg mRNA was significantly lower in the liver and ovary from RA fish than RN fish tissue. These results suggest that ER subtypes are differentially regulated by E2, and their functions are also different in vitellogenesis. Analysis of organic contaminants in sediments revealed that C. tarichi living in Van Edremit Gulf of Lake Van are exposed to the contaminants bis(2-ethylhexyl) phthalate and 4,4(') DDT. We suggest that the RA fish represent a segment of the population that is more sensitive to exposure to endocrine disrupting compounds.

Abstract 359: Modulation of Aldosterone Synthase by Estrogens: Evidence for an Interaction of Gper-1 and Estrogen B Receptors and Relevance for the Gender Dimorphism of Blood Pressure

Background. Fertile women have lower blood pressure and are held to be at lower risk for cardiovascular events than age-matched man. However, whether this gender dimorphism involves a modulation of aldosterone synthesis by 17 beta-estradiol (E2) is unknown. Aims. i) To investigate estrogen receptor subtypes gene expression in the normal human adrenal cortex (NAC), in aldosterone producing adenoma (APA) and in a human adrenocortical carcinoma cell line (HAC15); ii) To assess the effect of E2 on aldosterone synthase (CYP11B2) gene expression and to identify the receptor subtypes involved in this effect. Methods. We measured the expression of alpha (ERa), beta (ERb) and of G protein-coupled receptor (GPER-1)-1 in NAC and in APA tissue, and in HAC15 cells by real time RT-PCR. After demonstration that HAC15 cells express ERa, ERb, and GPER-1 we stimulated cells with 10-7M E2 alone, or after ERb selective blockade with 10-5M tetrahydrochrysenediol (THC), ERa selective blockade with 10-5M MPP dihydrochloride (MPP), non selective ERa and ERb blockade with 10-5M ICI 182.780, or after selective GPER-1 receptor blockade with 10-5M G-15. The cells were also exposed to the GPER-1 agonist G-1, alone or in the presence of MPP, THC, or Fulvestrant, and/or G-15. Changes of expression of CYP11B2 mRNA, measured with RT RT-PCR, was the experimental endpoint. Results. The quantitative expression of estrogen receptor subtypes was ERb &gt; GPER-1 &gt;&gt; ERα in NAC, GPER-1 &gt; ERb&gt; ERa in APA, and ERb&gt;ERa=GPER-1 in HAC15 cells. E2 alone or on top of selective ERa antagonism did not alter CYP11B2 expression. By contrast, E2 significantly increased CYP11B2 expression (+500 to + 700% from baseline, p &lt;0.001) after selective ERb antagonism, or combined ERa and ERb blockade. Likewise, G-1 markedly increased CYP11B2 gene after combined ERb blockade, an effect that was abolished by G15 co-treatment. Conclusion. E2 potently stimulates aldosterone synthase expression via GPER-1 subtype receptor activation when the ERb is blocked. The ERb-mediated tonic inhibition of aldosterone synthase could contribute to explaining both the lower BP and CV risk of fertile women and the increase of BP after when this tonic ERb-mediated inhibition wanes during menopause or estrogen-modulation treatment.

Combined Effects of Levonorgestrel and Quinestrol on Reproductive Hormone Levels and Receptor Expression in Females of the Mongolian Gerbil (Meriones unguiculatus)

The effects of treatment with a combination of levonorgestrel and quinestrol (EP-1; ratio of 2:1) on reproductive hormone levels and the expression of their receptors in female Mongolian gerbils were examined. We show that serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) decreased, whereas serum estradiol (E2) and progesterone (P4) increased after EP-1 treatment. EP1 down-regulated mRNA expression of the follicle-stimulating hormone receptor (FSHR) and the estrogen receptor (ER) βin the ovary. EP-1 up-regulated the mRNA expression of the luteinizing hormone receptor (LHR) and the progesterone receptor (PR) in the ovary as well as ERα and PR in the uterus of Mongolian gerbils. The effects were time-dependent and dose-dependent. EP-1 had no obvious effects on ERα mRNA expression in the ovary. The current study demonstrates that the effect of EP-1 on the expression of ER subtypes is tissue-specific in Mongolian gerbils. EP-1 disrupted the reproductive endocrinology of the Mongolian gerbil. These findings suggest that the effects of EP-1 on reproductive hormone levels and their receptor expression in Mongolian gerbils may be the result of synergistic actions of levonorgestrel and quinestrol, with quinestrol playing the major role.

Effect of nylestriol and levonorgestrel on the expression of estrogen receptor subtypes in human osteosarcoma MG-63 cell lines

To observe the effect of different concentrations of nylestriol (NYL) and levonorgestrel (LNG) on the expression of ERα and ERβ in human osteoscarcoma MG-63 cell lines, and to explore the impact of paracrine effect on the gene expression. MG-63 cells were treated with 3 concentrations (10(-10),10(-8), and 10(-6) mol/L) of NYL or LNG. The untreated control group and the positive control group were also established. The 2 groups treated with NYL (10(-10) mol/L) or LNG (10(-8) mol/L) were designed to renew the medium every 12 h. Semi-quantitative RT-PCR was conducted to detect the mRNA expression of ERα and ERβ on the MG-63 cells treated with different concentrations of the 2 drugs, respectively. Both drugs up-regulated ERα and ERβ mRNA expression. The best concentration for both NYL and LNG was 10(-6) mol/L for ERα expression. As for ERβ, the best concentration of NYL and LNG was 10(-10) mol/L and 10(-8) mol/L. The role of medium replacement on the expression of ERα was not observed, but medium replacement inhibited ERβ expression. Both NYL and LNG can up-regulate the mRNA expression of ER subtypes in MG-63 cells, with mutual restriction between the 2 subtypes. The paracrine effect on MG-63 cell lines may be involved in the regulation process of mRNA expression of ERβ.

Expression of receptor-binding cancer antigen expressed on SiSo cells in endometrial carcinoma and the correlation thereof with the expression of estrogen receptor subtypes

To investigate the expression of receptor-binding cancer antigen expressed on SiSo cells (RCAS1) and estrogen receptor subtypes in normal, hyperplastic, and carcinomatous endometrium and to explore their possible roles in carcinogenesis and progression of endometrial carcinoma. Immunohistochemistry and semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) were applied to detect the protein and mRNA expression of RCAS1, estrogen receptor (ER) alpha and ERbeta in 20 specimens of normal endometrium, 24 specimens of hyperplastic endometrium, and 50 specimens of carcinomatous endometrium. Western blotting was used to detect the RCAS1 protein expression. Normal endometrium and simple and complex hyperplastic endometrium showed a P pattern of RCAS1 expression; carcinomatous endometrium showed the D pattern; and the atypical hyperplastic endometrium showed both, 30% (6/20) of which showed D pattern. The high level RCAS1 protein expression rates of the normal, simple and complex hyperplasia, atypical hyperplasia, and endometrial carcinoma were 0% (0/20), 9.1% (2/22), 45.0% (9/20), and 68.0% (34/50) respectively with a significant difference between any 2 groups (all P < 0.05). The high level expression of RCAS1 was detected more frequently in the carcinomatous endometrium with deep myometrial invasion, vascular invasion, and positive of ERalpha (all P < 0.05). The Western blotting and RT-PCR results were correlated with the immunohistochemistry results. The RCAS1 mRNA level was positively correlated with the ERalphamRNA level (P < 0.01), but not correlated with the ERbetamRNA level (P > 0.05). The expression and distribution of RCAS1 may be involved in the malignant transformation of endometrium, and RCAS1 coexpression with ERalpha may be associated with the development and metastasis of endometrial carcinoma.

Mifepristone alters expression of endometrial steroid receptors and their cofactors in new users of medroxyprogesterone acetate

To evaluate the effect of mifepristone on the expression of endometrial steroid receptors and their co-factors in depot medroxyprogesterone acetate (DMPA) users. A prospective, randomized, placebo-controlled trial. Reproductive research center. Fifty healthy women with regular menstrual cycle. One hundred fifty milligrams of DMPA were given every 3 months. Two pills (25 mg each) of placebo or mifepristone were administered every 14 days during the DMPA therapy. Four endometrial biopsy specimens were obtained from each patient. The expression of estrogen receptor subtypes alpha and beta (ERalpha and ERbeta), progesterone receptors A and B (PRAB and PRB), and androgen receptor messenger RNA and protein was detected by real-time polymerase chain reaction and immunohistochemistry, respectively. Steroid receptor coactivator 1 (SRC-1), silencing mediator for retinoid and thyroid-hormone receptors, and cell proliferation were evaluated by immunohistochemistry. The expression of endometrial ERalpha, PRAB, PRB, and SRC-1 was increased significantly after 1 week of mifepristone, but the increase was no longer seen after 10 weeks. A positive correlation between endometrial ERalpha, PRAB, PRB, and SRC-1 production and proliferation was demonstrated. Short-term exposure of mifepristone in new starters of DMPA increases the expression of endometrial ERalpha, PRAB, PRB, and SRC-1 and promotes cell proliferation. Prolonged exposure to mifepristone does not alter the suppression of these receptors that are caused by DMPA and continues to result in endometrial atrophy.

Estrogens in Human Vascular Diseases

Estrogens are correlated with a lower incidence of atherosclerotic vascular disease, but also provide a protective effect on neovascular disorders, such as Kaposi's sarcoma (KS). Estrogens mediate indirect antiatherosclerotic vascular effects by reducing low-density lipoprotein (LDL) levels and by influencing fibrinolysis, and they exert direct actions on vascular cells including vascular relaxation and vasodilatation, thus reducing progression of the lesion. It is increasingly appreciated that the estrogenic effects are mediated not only by the classic genomic action via the specific nuclear hormone receptors ERalpha and ERbeta, but also by distinct rapid, nongenomic actions. Vascular cells have the capacity to express different types of estrogen receptors, and we provide evidence for selective expression of estrogen receptor subtypes on different human vascular cell types. Moreover, we give an overview on the vascular effects of estrogens, selective estrogen receptor modulators (SERMs), and androgens on normal and malignant vascular cells, with particular focus on the protective estrogenic potential on the vasculature.

Diabetic nephropathy is associated with decreasedcirculating estradiol levels and imbalance in the expression of renal estrogen receptors

The incidence of cardiovascular and renal disease is lower in premenopausal women than in aged-matched men. However, in the setting of diabetes mellitus (DM), this "female advantage" no longer exists: the incidence and progression of DM and its associated end-organ complications are equal in men and women, regardless of age. We have recently reported that estrogen supplementation attenuates the progression of diabetic nephropathy, suggesting that lack of estrogen may nullify female sex as a protective factor against DM. This study examined circulating levels of estradiol in DM and expression of estrogen receptor subtypes (ERa and ERP) in the nondiabetic (ND) and diabetic (D) kidney. : The study was performed in ND and streptozotocin-induced D Sprague-Dawley rats after 2 weeks (male and female) and 12 weeks (female) of DM. The animals (N = 8/group) were kept either intact, ovariectomized (OVX), or OVX with 17beta-estradiol (E(2)) supplementation (OVX + E(2), 5 mug/kg/d). Plasma estradiol levels were measured by enzyme-linked immunosorbent assay, and expression of renal ERalpha and ERbeta was measured by immunohistochemistry and Western blot analysis. DM was associated with reduced circulating estradiol levels (ND: mean [SEM] 37.1 [7.2]; D: 24.5 [9.3] pg/mL; P < 0.05). The diabetic kidney exhibited increased expression of ERalpha protein (ND: 0.82 [0.06]; D: 1.15 [0.09] arbitrary units; P < 0.05), but no differences in ERP were observed. This resulted in an overall increase in the ratio of ERalpha/ERbeta protein expression in the diabetic kidney. No differences in the expression of ERa were observed in either females or males with similar glycemic levels after 2 weeks of DM. Reduced circulating levels of estradiol and imbalance in the expression of estrogen receptor subtypes in the diabetic kidney may explain why female sex is no longer a protective factor in the setting of DM. Thus, estradiol supplementation may be an effective regimen in attenuating the onset and progression of diabetic renal complications.

Two estrogen replacement therapies differentially regulate expression of estrogen receptors alpha and beta in the hippocampus and cortex of ovariectomized rat

As estrogens have been implicated in altered cognitive function associated with menopause, the purpose of the present study was to determine the regulatory effects of different estrogen preparations on the expression of estrogen receptor subtypes in the hippocampus and cortex of ovariectomized rats. The expression of estrogen receptor mRNA and protein was determined with RT-PCR and immunohistochemistry, respectively. Two estrogen reagents, Premarin and Progynova, were used in the present study. Premarin, a conjugated equine estrogen, down-regulated ERα expression in the hippocampus and cortex of ovariectomized rats and had no effect on levels of ERβ expression in the same two regions. However, Progynova (valerate estradiol) was shown to up-regulate ERβ expression in the hippocampus and cortex and had no effect on the levels of ERα expression. Our present data suggest that different estrogen reagents used in estrogen replacement therapy could have different regulatory effects on the expression of estrogen receptor subtypes, which might, at least in part, explain why clinically, different estrogen preparations have distinct estrogenic effects on target organs.

Differential distribution of estrogen receptor (ER)-α and ER-β in the midbrain raphe nuclei and periaqueductal gray in male mouse: Predominant role of ER-β in midbrain serotonergic systems

We examined the distribution of estrogen receptor (ER)-α and ER-β immunoreactive (ir) cells in the dorsal (DRN) and median/paramedian (MPRN) raphe nuclei in male mice. ER-α ir neurons were scattered across the three subdivisions (ventral, dorsal, and lateral) of the DRN and the MPRN. Robust ER-β ir cells were observed throughout the raphe nuclei, and were particularly abundant in the ventral and dorsal subdivisions of the DRN. Using dual-label immunocytochemistry for ER-α or ER-β with tryptophan hydroxylase (TPH), the rate-limiting enzyme for 5-hydroxytryptamine (5-HT) synthesis, over 90% of ER-β ir cells exhibited TPH-ir in all DRN subdivisions, whereas only 23% of ER-α ir cells contained TPH. Comparisons of ER-α knockout (αERKO) as well as ER-β knockout (βERKO) mice with their respective wild-type (WT) littermates revealed that gene disruption of either ER-α or ER-β did not affect the other ER subtype expression in the raphe nuclei. In situ hybridization histochemistry revealed that there was a small but statistically significant decrease in TPH mRNA expression in the ventral DRN subdivision in βERKO mice compared with βWT mice, whereas TPH mRNA levels were not affected in αERKO mice. These findings support a hypothesis that ER-β activation may contribute to the estrogenic regulation of neuroendocrine and behavioral functions, in part, by acting directly on 5-HT neurons in the raphe nuclei in male mice.

Expression of estrogen receptor subtypes in rat pituitary gland during pregnancy and lactation.

The aim of this study was to examine whether the expression levels of mRNA of the three estrogen receptor (ER) subtypes, ERalpha, ERbeta, and truncated ER product-1 (TERP-1) found in the rat pituitary gland were modified during gestation, lactation, and postlactation periods. By using relative quantitative RT-PCR, we found that ERalpha mRNA significantly peaked in midpregnancy. However, the ERalpha protein level remained constant. ERbeta gene expression did not change throughout pregnancy, suggesting that it was not related to estradiol levels during this reproductive period. In contrast, both TERP-1 mRNA and protein levels dramatically increased throughout the second half of gestation, being faintly detectable in early pregnancy. TERP-1 expression was rapidly reversed by lactation, whereas neither pituitary ERalpha nor ERbeta relative levels were significantly altered. In addition, pup removal for 24-96 h on d 9 postpartum significantly reduced the expression of both ERalpha and ERbeta mRNA compared with that in lactating animals, but the expression of TERP-1 mRNA was no longer detected. Collectively, our data indicate that 1) TERP-1, ERalpha, and ERbeta expression levels are differentially regulated in the pituitary; 2) TERP-1 is variably expressed depending on the hormonal environment related to the estrous cycle, pregnancy, and lactation; and 3) TERP-1/ERalpha ratios dramatically change depending on reproductive periods, suggesting a critical role for TERP-1 in reproductive events.

Expression of estrogen receptor (ER)-alpha and -beta immunoreactivity in hippocampal cell cultures with special attention to GABAergic neurons.

This study investigated the expression patterns of estrogen receptor-alpha (ER alpha) and -beta (ER beta) in the cultured hippocampal cells of neonatal rats by combined application of cell culture and immunocytochemistry. The results revealed that the expression difference between ER alpha and ER beta seemed to be not obvious in the cultured hippocampal cells of neonatal rats. Moreover, immunoreactivity for either ER alpha or ER beta was observed to be localized in the majority of not only neurons but also astrocytes. The coexpression of both ER alpha and ER beta in the same individual cell was also demonstrated by the double-label immunocytochemistry. Western blot analysis showed that immunoreactivity for ER alpha in the neonatal hippocampal tissues was much higher than in the adult (became rather weak), although there was not such a great difference of immunoreactivity for ER beta. The data also provide direct evidence for the expression of ER subtypes within GABAergic neurons in hippocampal cell cultures and suggest that estrogen's effect on the hippocampus may be mediated at least in part by its ER-containing GABAergic neurons.