Physiological Levels Of Estradiol Research Articles

The relationship between serum estrogen concentration and post-dural puncture headache: a retrospective study.

Post-Dural puncture headache (PDPH) is a severe and undesirable complication for the patient and anesthesiologist. PDPH is more common in female patients. However, its relationship with plasma estrogen levels has not been demonstrated. This study aimed to investigate the relationship between estrogen levels and PDPH in patients who underwent spinal anesthesia for in vitro fertilization (IVF) with supraphysiological estrogen levels. In this retrospective study, the data of patients between the ages of 18-45 with the following characteristics were included in the study: those who underwent IVF procedure between January 2021 and August 2022, in the ASA I-II risk group, and who underwent spinal anesthesia using a 25 G Quinke-tipped spinal needle at the L3-L4 or L4-L5 vertebra levels. The 48 patients in the study were in two groups according to their estradiol values: 'Supra physiological estradiol levels' (Group I=24 patients) and 'Normal estradiol levels' (Group C=24 patients). The relationship between PDPH and estrogen, progesterone, spinal needle diameter, and patient demographic characteristics were evaluated. The estrogen and progesterone levels of patients in Group I were higher than in Group C (p<0.001 and p<0.001, respectively). PDPH was present in 6 (25%) patients in Group I and 5 (20.8%) patients in Group C (p=0.731). There was no significant correlation between PDPH and estrogen and progesterone levels (p>0.05). Since there is no relationship between the supraphysiological estrogen level and PDPH, high serum estrogen level should not be considered as an additional risk factor for PDPH in the decision of anesthesia type for IVF procedure.

Sexual attraction to visual sexual stimuli in association with steroid hormones across menstrual cycles and fertility treatment

BackgroundSteroid hormones (i.e., estradiol, progesterone, and testosterone) are considered to play a crucial role in the regulation of women’s sexual desire and sexual attraction to sexual stimuli throughout the menstrual cycle. However, the literature is inconsistent, and methodologically sound studies on the relationship between steroid hormones and women’s sexual attraction are rare. MethodsThis prospective longitudinal multisite study examined estradiol, progesterone, and testosterone serum levels in association with sexual attraction to visual sexual stimuli in naturally cycling women and in women undergoing fertility treatment (in vitro fertilization, IVF). Across ovarian stimulation of fertility treatment, estradiol reaches supraphysiological levels, while other ovarian hormones remain nearly stable. Ovarian stimulation hence offers a unique quasi-experimental model to study concentration-dependent effects of estradiol. Hormonal parameters and sexual attraction to visual sexual stimuli assessed with computerized visual analogue scales were collected at four time points per cycle, i.e., during the menstrual, preovulatory, mid-luteal, and premenstrual phases, across two consecutive menstrual cycles (n = 88 and n = 68 for the first and second cycle, respectively). Women undergoing fertility treatment (n = 44) were assessed twice, at the beginning and at the end of ovarian stimulation. Sexually explicit photographs served as visual sexual stimuli. ResultsIn naturally cycling women, sexual attraction to visual sexual stimuli did not vary consistently across two consecutive menstrual cycles. While in the first menstrual cycle sexual attraction to male bodies, couples kissing, and at intercourse varied significantly with a peak in the preovulatory phase, (all p ≤ 0.001), there was no significant variability across the second cycle. Univariable and multivariable models evaluating repeated cross-sectional relationships and intraindividual change scores revealed no consistent associations between estradiol, progesterone, and testosterone and sexual attraction to visual sexual stimuli throughout both menstrual cycles. Also, no significant association with any hormone was found when the data from both menstrual cycles were combined. In women undergoing ovarian stimulation of IVF, sexual attraction to visual sexual stimuli did not vary over time and was not associated with estradiol levels despite intraindividual changes in estradiol levels from 122.0 to 11,746.0 pmol/l with a mean (SD) of 3553.9 (2472.4) pmol/l. ConclusionsThese results imply that neither physiological levels of estradiol, progesterone, and testosterone in naturally cycling women nor supraphysiological levels of estradiol due to ovarian stimulation exert any relevant effect on women’s sexual attraction to visual sexual stimuli.

RF03 | PMON286 Engineering Steroid Receptors to Respond to Chemicals of Choice

Abstract In synthetic biology, small molecules are commonly used for altering gene expression through the (in)activation of gene switches. Current switches, however, have a narrow species range, are non-titratable, or use non-inert inducers which evoke important side effects. Universal gene switches (XRs) that have dynamic ranges without interference with the host cell physiology will overcome these limitations. Ideal starting points for developing such XRs are the steroid receptors (SRs). The SRs are frequently applied as regulator domain or gene switch in organisms in which they are not naturally expressed, like microbes and plants. Several SRs, such as the estrogen receptor alpha (ERα), have been redesigned to respond to synthetic effectors but these variants require inducer amounts that are detrimental to the host or affect endogenous SRs. By combining in silico modelling with directed evolution in the yeast Saccharomyces cerevisiae, we developed a platform and strategy for evolving SRs towards a chemical of choice. Validation of this method was achieved by first evolving the ERα to employ tamoxifen as an agonist, yielding the preTERRA variant. Subsequently, activation by estradiol was removed, rendering a tamoxifen receptor (TERRA). We show that TERRA gets activated by subtoxic tamoxifen amounts while remaining insensitive for physiological estradiol levels. Further evaluation demonstrated TERRA to be transferable to mammalian cells. Ongoing research aims at converting the TERRA receptor into a regulatory domain for controlling nuclear translocation of Cre recombinases and Cas9 proteins in both cell lines and mouse models. The same platform was employed for adapting ERα towards the plasticizer Bisphenol A. This yielded an ERα variant that is no longer inducible by estradiol but is responsive to lower concentrations of Bisphenol in yeast. The transferal to cell lines will provide us with an additional regulatory domain. The ability to engineer any SR towards a synthetic ligand of choice not only expands the synthetic biology toolbox but can find applications in landscaping SR-related drug resistance and ligand-inducibility. Presentation: Saturday, June 11, 2022 1:48 p.m. - 1:53 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Transcriptome responses in polar cod (Boreogadus saida) liver slice culture exposed to benzo[a]pyrene and ethynylestradiol: insights into anti-estrogenic effects

Polar cod (Boreogadus saida) is a key species in the arctic marine ecosystem vulnerable to effects of pollution, particularly from petroleum related activities. To facilitate studying the effects of those pollutants, we adapted a precision-cut liver slice culture protocol for this species. Using this system on board a research vessel, we studied gene expression in liver slice after exposure to the polycyclic aromatic hydrocarbon (PAH) benzo[a]pyrene (BaP), ethynylestradiol (EE2), and their mixtures, to map their molecular targets and examine possible anti-estrogenic effects of BaP. The exposure experiments were performed with BaP alone (0.1, 1, and 10 μM) or in combination with low concentrations of EE2 (5 nM) to mimic physiological estradiol levels in early vitellogenic female fish. Transcriptome analysis (RNA-seq) was performed after 72 h exposure in culture to map the genes and cellular pathways affected. The results provide a view of global transcriptome responses to BaP and EE2, which resulted in enrichment of many pathways such as the aryl hydrocarbon (Ahr) and estrogen receptor pathways. In the mixture exposure, BaP resulted in anti-estrogenic effects, shown by attenuation of EE2 activated transcription of many estrogen target genes. The results from this ex vivo experiment suggest that pollutants that activate the Ahr pathway such as the PAH compound BaP can result in anti-estrogenic effects that may lead to endocrine disruption in polar cod.

Fulvestrant-Mediated Attenuation of the Innate Immune Response Decreases ER+ Breast Cancer Growth In Vivo More Effectively than Tamoxifen.

Although blocking estrogen-dependent signaling is a cornerstone of adjuvant treatment for breast cancer, 25% of patients experience recurrent disease. Stroma events including innate immune responses are key in cancer progression. How different estrogen receptor (ER)-targeting therapies, including the partial agonist tamoxifen and the pure antagonist fulvestrant, affect the tumor stroma has not yet been elucidated. Fulvestrant is used in only postmenopausal patients, and its effects in the presence of estradiol remain undetermined. Here we observe that fulvestrant decreases ER+ breast cancer growth compared with tamoxifen in the presence of physiologic levels of estradiol in human breast cancer in nude mice and in murine breast cancer in immune-competent mice. Fulvestrant significantly inhibited macrophage and neutrophil infiltration in both models. These effects were corroborated in a zebrafish model where fulvestrant inhibited neutrophil- and macrophage-dependent cancer cell dissemination more effectively than tamoxifen. A comprehensive analysis of 234 human proteins released into the cancer microenvironment by the cancer cells sampled via microdialysis in vivo revealed that 38 proteins were altered following both treatments; 25 of these proteins were associated with immune response and were altered by fulvestrant only. Compared with tamoxifen, fulvestrant significantly affected inflammatory proteins released by murine stroma cells. Importantly, in vivo microdialysis of human ER+ breast cancer revealed that the majority of affected proteins in murine models were upregulated in patients. Together, these results suggest that fulvestrant targets ER+ breast cancer more effectively than tamoxifen even in the presence of estradiol, mainly by attenuation of the innate immune response. SIGNIFICANCE: These findings demonstrate novel effects of the pure antiestrogen fulvestrant in ER+ breast cancer and evaluate its effects under physiologic levels of estradiol, representative of premenopausal patients.

Scaffold-Free Endometrial Organoids Respond to Excess Androgens Associated With Polycystic Ovarian Syndrome.

Polycystic ovary syndrome (PCOS) is a prevalent disorder in reproductive aged women associated with a number of endocrine and metabolic complications, including increased risk of endometrial cancer. To study the effect of the characteristic increased androgen levels in PCOS on the endometrium, a novel scaffold-free multicellular endometrial organoid was established. Human endometrial organoids were constructed using primary endometrial epithelial and stromal cells from endometrial tissues. Organoids were treated for 14 days with physiologic levels of estradiol and testosterone to mimic a normal follicular phase or PCOS hormone profiles. Organoids were harvested for immunostaining and ribonucleic acid sequencing. Academic institution. Endometrial tissues from 10 premenopausal women undergoing hysterectomy for benign pathologies were obtained following written consent. Organoid architecture, cell specific markers, functional markers, proliferation, and gene expression were measured. A method to generate scaffold-free endometrial organoids containing epithelial and stromal cells was established. These organoids exhibited distinct organization with epithelial cells lining the outer surface and stromal cells in the center of the organoids. Epithelial cells were polarized, organoids expressed cell type specific and functional markers, as well as androgen, estrogen, and progesterone receptors. Treatment with PCOS hormones increased cell proliferation and dysregulated genes in endometrial organoids. A new multicellular, scaffold-free endometrial organoid system was established that resembled physiology of the native endometrium. Excess androgens in PCOS promoted cell proliferation in endometrial organoids, revealing new mechanisms of PCOS-associated with risk of endometrial neoplasia.

Progesterone Is Important for Transgender Women's Therapy-Applying Evidence for the Benefits of Progesterone in Ciswomen.

Although the 2017 Endocrine Society Guidelines for gender dysphoria stipulated that cross-sex hormone therapy (CHT) achieve gonadal steroid levels equivalent to those of a cisperson of the chosen sex, for transgender women (male-to-female gender dysphoria), current gonadal therapy is usually estradiol. Accumulated evidence indicates that normally ovulatory menstrual cycles are necessary for ciswomen's current fertility, as well as for later-life bone and cardiovascular health and the prevention of breast and endometrial cancers. Extensive past clinical experience with transgender women's CHT using estradiol/estrogen combined with progesterone/medroxyprogesterone and pioneering the addition of spironolactone. Comprehensive progesterone physiology research plus a brief review of transgender women's literature to assess current therapy and clinical outcomes, including morbidity and mortality. To emphasize that both ovarian hormones, progesterone as well as estradiol, are theoretically and clinically important for optimal transgender women's CHT. It is important to add progesterone to estradiol and an antiandrogen in transgender women's CHT. Progesterone may add the following: (i) more rapid feminization, (ii) decreased endogenous testosterone production, (iii) optimal breast maturation to Tanner stages 4/5, (iv) increased bone formation, (v) improved sleep and vasomotor symptom control, and (vi) cardiovascular health benefits. Evidence has accrued that normal progesterone (and ovulation), as well as physiological estradiol levels, is necessary during ciswomen's premenopausal menstrual cycles for current fertility and long-term health; transgender women deserve progesterone therapy and similar potential physiological benefits.

F122. The Neuronal Stem Cell Transcriptome of Premenstrual Dysphoric Disorder

Premenstrual dysphoric disorder (PMDD) is characterized by recurrent affective and behavioral symptoms during the luteal phase of the menstrual cycle. Clinical studies show that in women with PMDD, symptoms recur after re-exposure to physiologic levels of estradiol (E2) or progesterone (P4) during GnRH-agonist-induced ovarian suppression. Furthermore, women with PMDD show symptom reduction after blocking the conversion of P4 to allopreganolone (ALLO) across the menstrual cycle.

Impact of in vitro treatments of physiological levels of estradiol and progesterone observed in pregnancy on bovine monocyte-derived dendritic cell differentiation and maturation

The specific factors which regulate differentiation and maturation of dendritic cells in bovine pregnancy remain unclear. We evaluated the influence of physiologically relevant in vitro treatments of progesterone (PG) and estradiol (E2) observed in late pregnancy on the differentiation and maturation of CD14+ monocyte-derived dendritic cell (moDC) from non-pregnant, lactating dairy cows (n=7). We found that moDC differentiated in the presence of both E2 and PG had impaired E. coli-induced phenotypic maturation, specifically a significant reduction in CD80 and MHC II expression. Contrary to our previous work characterizing moDC from late gestating dairy cattle, we did not observe an increase in CD14 expression relative to the untreated control; this increase was only observed in the current data in the dexamethasone-treated moDC. The moDC treated with a combination of both E2 and PG had significantly greater upregulation of anti-inflammatory cytokine IL-10 relative to the untreated control, but TNFα production was not suppressed; only dexamethasone-treated moDC showed abrogated TNFα production. These data suggest moDC may be regulated by E2 and PG to hinder phenotypic maturation and regulate inflammatory responses. Pregnancy-associated hormone profiles appear to be involved in the generation of maternal immune tolerance in pregnancy. These hormone-facilitated changes to moDC in pregnancy may also impede optimal immune responses to both invading pathogens and routine vaccinations administered in late gestation through limited antigen presentation and increased anti-inflammatory cytokine production. These results provide insight into maternal immune modulation and elucidate potential immune changes necessary to facilitate bovine pregnancy.

Chemoattraction of bone marrow-derived stem cells towards human endometrial stromal cells is mediated by estradiol regulated CXCL12 and CXCR4 expression

Bone marrow derived cells engraft to the uterine endometrium and contribute to endometriosis. The mechanism by which these cells are mobilized and directed to the endometrium has not been previously characterized. We demonstrate that human endometrial stromal cells (hESCs) produce the chemokine CXCL12 and that bone marrow cells (BMCs) express the CXCL12 receptor, CXCR4. Treatment with physiological levels of estradiol (E2) induced both CXCL12 and CXCR4 expression in hESCs and BMCs, respectively. BMCs migrated towards hESCs conditioned media; a CXCR4 antagonist blocked migration indicating that CXCL12 acting through its receptor, CXCR4, is necessary for chemoattraction of BM cells to human endometrial cells. E2 increased both CXCL12 expression in endometrial cells and CXCR4 expression in BM cells, further enhancing chemoattraction. E2 induced CXCL12/CXCR4 expression in endometrium and BM, respectively, drives migration of stem cells to the endometrium. The E2-CXCL12/CXCR4 signaling pathway may be useful in determining treatments for endometrial disorders, and may be antagonized to block stem cell migration to endometriosis.

Characterization of the temporal and spatial expression of a disintegrin and metalloprotease 17 in the human endometrium and fallopian tube.

Metalloproteinases are thought to mediate shedding of mucins from the endometrium surface, exposing oligosaccharide ligands involved in implantation. We hypothesized that a disintegrin and metalloprotease 17 (ADAM17) is upregulated during the "window of implantation" in human endometrium but not in fallopian tube (FT) where implantation is pathological. Endometrial and FT expression of ADAM17 throughout the menstrual cycle was determined using quantitative reverse-transcription polymerase chain reaction and immunohistochemistry. The ADAM17 transcription was significantly downregulated (P < .01) during the early-midsecretory phase in the endometrium but not in the FT. The ADAM17 was localized to the surface of epithelial cells and was also detected in the endometrial stroma during the late luteal and proliferative phase of the cycle. Physiological levels of estradiol significantly (P < .05) upregulated ADAM17 transcription in vitro. Our observations do not support the role of ADAM17 in shedding of mucins during the window of implantation. The precise role of ADAM17 in the female reproductive tract requires further investigation.

Cognitive performance in healthy women during induced hypogonadism and ovarian steroid addback.

Gynecology clinic-based studies have consistently demonstrated that induced hypogonadism is accompanied by a decline in cognitive test performance. However, a recent study in healthy asymptomatic controls observed that neither induced hypogonadism nor estradiol replacement influenced cognitive performance. Thus, the effects of induced hypogonadism on cognition might not be uniformly experienced across individual women. Moreover, discrepancies in the effects of hypogonadism on cognition also could suggest the existence of specific risk phenotypes that predict a woman's symptomatic experience during menopause. In this study, we examined the effects of induced hypogonadism and ovarian steroid replacement on cognitive performance in healthy premenopausal women. Ovarian suppression was induced with a GnRH agonist (Lupron) and then physiologic levels of estradiol and progesterone were reintroduced in 23 women. Cognitive tests were administered during each hormone condition. To evaluate possible practice effects arising during repeated testing, an identical battery of tests was administered at the same time intervals in 11 untreated women. With the exception of an improved performance on mental rotation during estradiol, we observed no significant effects of estradiol or progesterone on measures of attention, concentration, or memory compared with hypogonadism. In contrast to studies in which a decline in cognitive performance was observed in women receiving ovarian suppression therapy for an underlying gynecologic condition, we confirm a prior report demonstrating that short-term changes in gonadal steroids have a limited effect on cognition in young, healthy women. Differences in the clinical characteristics of the women receiving GnRH agonists could predict a risk for ovarian steroid-related changes in cognitive performance during induced, and possibly, natural menopause.

Effects of estradiol on avian myogenic satellite cell proliferation and expression of heparan sulfate proteoglycans, MyoD and myogenin

The objective of this study was to determine the effects of estradiol on avian myogenic satellite cell proliferation and the gene expression of proteins recognized as important in regulating skeletal muscle growth and development. Estradiol (0 M 10−5M, 10−6M, 10−9M, or 10−12M) was administered in basal medium containing additional nutrients. Female‐derived pectoralis major (PM) satellite cell proliferation was stimulated at a level of 10−9 M following 4 days of treatment. Male PM satellite cell proliferation was increased beginning at 10−12M estradiol. Likewise, male biceps femoris satellite cells demonstrated increased proliferation in the presence of 10−12M estradiol. Turkey embryonic myoblast proliferation, however, was not responsive to estradiol following 3 days administration under these conditions. Syndecan‐4 and glypican‐1 expression in male PM cells was not effected by physiological levels of estradiol (10−9M). However, MyoD and myogenin expression decreased in these cells when exposed to 10−12M and 10−9M estradiol, respectively. Expression of syndecan‐4, glypican‐1 and MyoD in embryonic myoblasts was not effected by estradiol. However, myogenin expression was decreased when administered 10−12M estradiol. The results demonstrate a direct effect of estradiol on avian satellite cell proliferation independent of syndecan‐4 and glypican‐1, and decreased expression of MyoD and myogenin coinciding with increased cellular proliferation.

ACTH and Cortisol Response to Dex/CRH Testing in Women with and without Premenstrual Dysphoria during GnRH Agonist-Induced Hypogonadism and Ovarian Steroid Replacement

During conditions of ovarian suppression, women with premenstrual dysphoria (PMD) experience abnormal behavioral responses to physiological levels of ovarian steroids. Although hypothalamic-pituitary-adrenal (HPA) axis dysregulation frequently accompanies depression, and ovarian steroids regulate HPA axis responsivity, the role of HPA axis dysregulation in PMD is not known. We hypothesized that women with PMD would show abnormalities of HPA axis function analogous to those reported in depressive illness, and that ovarian steroids would differentially regulate HPA axis function in women with PMD compared with asymptomatic controls (AC). Our objective was to characterize the HPA axis response to physiological levels of estradiol and progesterone in women with PMD and AC. We conducted an open-label trial of the GnRH agonist depot Lupron with ovarian steroid replacement administered in a double-blind crossover design in an outpatient clinic. Forty-three women (18 with prospectively confirmed PMD and 25 AC) participated. Women received Lupron for 6 months. After 3 months of hypogonadism, women received 5 wk each of estradiol (100-μg patch daily) or progesterone (suppositories 200 mg twice daily). During each condition, combined dexamethasone-suppression/CRH-stimulation tests and 24-h urinary free cortisol levels were performed. Plasma cortisol and ACTH levels were evaluated. HPA axis function was similar in PMD compared with AC. In all, progesterone significantly increased the secretion of cortisol compared with estradiol [area under the curve (t(74) = 3.1; P < 0.01)] and urinary free cortisol (t(74) = 3.2; P < 0.01) and ACTH compared with hypogonadism [area under the curve (t(74) = 2.4; P < 0.05)]. HPA axis regulation is normal in PMD, suggesting that the pathophysiology of PMD differs from major depression. As observed previously, progesterone but not estradiol up-regulates HPA axis function in women.

Evaluation of the effects of estradiol on the hypothalamic-pitutary adrenal axis response during systemic and local inflammation

The immune and nervous systems are closely interrelated through their messenger molecules: cytokines, hormones and nitric oxide. There are sex differences in the magnitude of the inflammatory response and one of the mechanism by which female sex steroids modulate the inflammatory response could be through the hypothalamo-pituitary-adrenal axe(HPA axes). In this study, we aimed to investigate the inter-relationship between the different levels of estradiol hormone and the different inflammatory stimuli on the HPA axis response, and the role of interleukin 6(IL6) and nitric oxide (NO). This was achieved by using 100 female albino rats divided in to 3 main groups: The first group was the sham group, which was used to test the effect of all sham procedures used in the study. The two other groups represented the two inflammatory states: local (induced by formaline injection) and systemic (cecal ligation and puncture: CLP). Under each inflammatory state, the effect of intact ovary, estradiol treated ovariectomy and placebo treated ovariectomy were studied. HPA responses were evaluated, 24 hours after the sham or the inflammatory procedure, through the measurement of the plasma levels of Corticotropin-releasing Hormone (CRH), adrenocorticotropes Hormone (ACTH) and cortisol. Both IL6 and nitrite were also measured.We found that high physiological levels of estradiol reduced the enhanced HPA response induced by different inflammatory mediators during systemic and local inflammation. With significant enhancement of the HPA response observed mainly during local inflammation. We conclude that both the levels of estradiol hormone and the type of inflammation seem to play an important determining role on HPA response. IL6 and NO play important roles that could explain the previous findings.

Female Reproductive Hormones Alter Sleep Architecture in Ovariectomized Rats

Treating ovariectomized rats with physiological levels of estradiol and/or progesterone affects aspects of both baseline (24 h) sleep and recovery (18 h) sleep after 6 h of sleep deprivation. We have extended the analysis of these effects by examining several additional parameters of sleep architecture using the same data set as in our previous study (Deurveilher et al. SLEEP 2009;32(7):865-877). Sleep in ovariectomized rats implanted with oil, 17 β-estradiol and/or progesterone capsules was recorded using EEG and EMG before, during, and after 6 h of sleep deprivation during the light phase of a 12/12 h light/dark cycle. During the baseline dark, but not light, phase, treatments with estradiol alone or combined with progesterone decreased the mean duration of non-rapid eye movement sleep (NREMS) episodes and the number of REMS episodes, while also increasing brief awakenings, consistent with the previously reported lower baseline NREMS and REMS amounts. Following sleep deprivation, the hormonal treatments caused a larger percentage increase from baseline in the mean durations of NREMS and REMS episodes, and a larger percentage decrease in brief awakenings, consistent with the previously reported larger increase in recovery REMS amount. There were no hormonal effects on NREMS and REMS EEG power values, other than on recovery NREMS delta power, as previously reported. Physiological levels of estradiol and/or progesterone in female rats modulate sleep architecture differently at baseline and after acute sleep loss, fragmenting baseline sleep while consolidating recovery sleep. These hormones also play a role in the diurnal pattern of NREMS maintenance.

Interactions between kisspeptin and neurokinin B in the control of GnRH secretion in the female rat

Neurokinin B (NKB) and its cognate receptor neurokinin 3 (NK3R) play a critical role in reproduction. NKB and NK3R are coexpressed with dynorphin (Dyn) and kisspeptin (Kiss1) genes in neurons of the arcuate nucleus (Arc). However, the mechanisms of action of NKB as a cotransmitter with kisspeptin and dynorphin remain poorly understood. We explored the role of NKB in the control of LH secretion in the female rat as follows. 1) We examined the effect of an NKB agonist (senktide, 600 pmol, administered into the lateral cerebral ventricle) on luteinizing hormone (LH) secretion. In the presence of physiological levels of estradiol (E(2)), senktide induced a profound increase in serum levels of LH and a 10-fold increase in the number of Kiss1 neurons expressing c-fos in the Arc (P < 0.01 for both). 2) We mapped the distribution of NKB and NK3R mRNAs in the central forebrain and found that both are widely expressed, with intense expression in several hypothalamic nuclei that control reproduction, including the Arc. 3) We studied the effect of E(2) on the expression of NKB and NK3R mRNAs in the Arc and found that E(2) inhibits the expression of both genes (P < 0.01) and that the expression of NKB and NK3R reaches its nadir on the afternoon of proestrus (when circulating levels of E(2) are high). These observations suggest that NKB/NK3R signaling in Kiss1/NKB/Dyn-producing neurons in the Arc has a pivotal role in the control of gonadotropin-releasing hormone (GnRH)/LH secretion and its regulation by E(2)-dependent negative feedback in the rat.

Abstract 609: Paradoxical actions of a c-Src inhibitor on estradiol-induced apoptosis in long-term estrogen deprivation breast cancer cells

Abstract Resistance to aromatase inhibitors used for the treatment of estrogen receptor (ER) positive breast cancer is an increasing problem clinically. We have demonstrated in the laboratory that long term estrogen-deprived MCF-7 breast cancer cells referred to as MCF-7:5C (Lewis et al, JNCI 2005, 97:1746-1759), respond to physiological estrogen by triggering apoptosis. This scientific observation is now in clinical trial, but only 30% of patients receive clinical benefit (Ellis et al, JAMA 2009, 302:774-780). A goal of translational research is to increase the therapeutic responsiveness of antihormone resistant breast cancer. c-Src inhibitors are currently of interest, as they inhibit survival pathways in breast cancer. We have evaluated the potential of the c-Src inhibitor, PP2, alone (5 µM), and compared results of cell survival with estradiol (1 nM E2) alone, or in combination with PP2. The MCF-7:5C cells have increased levels of phosphorylation c-Src, compared to wild type MCF-7 cells. Long term treatment (at least 2 months) with PP2 initially decreased growth rates of MCF-7:5C cells, but then growth recovered. Long term treatment of MCF-7:5C cells with E2 initially causes massive apoptosis, but a population of surviving cells subsequently regrew, but these ER-positive cells were refractory to estrogen action. In contrast, a combination of PP2 + E2 actually retarded apoptosis and the resulting cell line (MCF-7:PF) is unique, as they grew vigorously in culture with physiological levels of estradiol, but remarkably are also stimulated in vitro by a panel of selective estrogen receptor modulators (SERMs). This is the first description of a Phase I (Jordan, Cancer Cell 2004, 5:207-213) resistant breast cancer cell line in vitro. These data illustrate that caution must be exercised when considering the evaluation of c-Src inhibitors in clinical trial following the development of acquired resistance to aromatase inhibitors. A combination with therapeutic estrogen treatment or indeed endogenous estrogen may impair therapeutic effectiveness of c-Src in breast cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 609.

Estrogen receptor signaling promotes dendritic cell differentiation by increasing expression of the transcription factor IRF4

AbstractDuring inflammation, elevated granulocyte macrophage–colony-stimulating factor (GM-CSF) directs the development of new dendritic cells (DCs). This pathway is influenced by environmental factors, and we previously showed that physiologic levels of estradiol, acting through estrogen receptor alpha (ERα), promote the GM-CSF–mediated differentiation of a CD11b+ DC subset from myeloid progenitors (MPs). We now have identified interferon regulatory factor 4 (IRF4), a transcription factor induced by GM-CSF and critical for CD11b+ DC development in vivo, as a target of ERα signaling during this process. In MPs, ERα potentiates and sustains GM-CSF induction of IRF4. Furthermore, retroviral delivery of the Irf4 cDNA to undifferentiated ERα−/− bone marrow cells restored the development of the estradiol/ERα-dependent DC population, indicating that an elevated amount of IRF4 protein substitutes for ERα signaling. Thus at an early stage in the MP response to GM-CSF, ERα signaling induces an elevated amount of IRF4, which leads to a developmental program underlying CD11b+ DC differentiation.

Differential Regulation of Gonadotropin-Releasing Hormone Neuron Activity and Membrane Properties by Acutely Applied Estradiol: Dependence on Dose and Estrogen Receptor Subtype

Gonadotropin-releasing hormone (GnRH) neurons are critical to controlling fertility. In vivo, estradiol can inhibit or stimulate GnRH release depending on concentration and physiological state. We examined rapid, nongenomic effects of estradiol. Whole-cell recordings were made of GnRH neurons in brain slices from ovariectomized mice with ionotropic GABA and glutamate receptors blocked. Estradiol was bath applied and measurements completed within 15 min. Estradiol from high physiological (preovulatory) concentrations (100 pm) to 100 nm enhanced action potential firing, reduced afterhyperpolarizing potential (AHP) and increased slow afterdepolarization amplitudes (ADP), and reduced I(AHP) and enhanced I(ADP). The reduction of I(AHP) was occluded by previous blockade of calcium-activated potassium channels. These effects were mimicked by an estrogen receptor (ER) beta-specific agonist and were blocked by the classical receptor antagonist ICI182780. ERalpha or GPR30 agonists had no effect. The acute stimulatory effect of high physiological estradiol on firing rate was dependent on signaling via protein kinase A. In contrast, low physiological levels of estradiol (10 pm) did not affect intrinsic properties. Without blockade of ionotropic GABA and glutamate receptors, however, 10 pm estradiol reduced firing of GnRH neurons; this was mimicked by an ERalpha agonist. ERalpha agonists reduced the frequency of GABA transmission to GnRH neurons; GABA can excite to these cells. In contrast, ERbeta agonists increased GABA transmission and postsynaptic response. These data suggest rapid intrinsic and network modulation of GnRH neurons by estradiol is dependent on both dose and receptor subtype. In cooperation with genomic actions, nongenomic effects may play a role in feedback regulation of GnRH secretion.