Distribution of estrogen receptors alpha and beta mRNA in mouse urogenital tissues and their expression after oophorectomy and estrogen replacement

Early-life exposure to sex hormones promotes voluntary ethanol intake in adulthood. A vulnerability factor to drug addiction

While there is extensive research on alcohol dependence, the factors that make an individual vulnerable to developing alcoholism haven't been explored much. In this study, we aim to investigate how neonatal exposure to sex hormones affects alcohol intake and the regulation of the mesolimbic pathway in adulthood. The study aimed to investigate the impact of neonatal exposure to a single dose of testosterone propionate (TP) or estradiol valerate (EV) on ethanol consumption in adult rats. The rats were subjected to a two-bottle free-choice paradigm, and the content of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) in the nucleus accumbens (NAcc) was measured using HPLC-ED. The expression of critical DA-related proteins in the mesolimbic pathway was evaluated through RT-qPCR and western blot analysis. Supraphysiological neonatal exposure to EV or TP resulted in increased ethanol intake over four weeks in adulthood. In addition, the DA and DOPAC content was reduced and increased in the NAcc of EV and TP-treated rats, and β-endorphin content in the hypothalamus decreased in EV-treated rats. The VTA μ receptor and DA type 2 form short receptor (D2S) expression were significantly reduced in EV and TP male rats. Finally, in an extended 6-week protocol, the increase in ethanol consumption induced by EV was mitigated during the initial two hours post-naloxone injection. Neonatal exposure to sex hormones is a detrimental stimulus for the brain, which can facilitate the development of addictive behaviors, including alcohol use disorder.

Estrogen receptors in human bladder cells regulate innate cytokine responses to differentially modulate uropathogenic E. coli colonization

The bladder epithelial cells elicit robust innate immune responses against urinary tract infections (UTIs) for preventing the bacterial colonization. Physiological fluctuations in circulating estrogen levels in women increase the susceptibility to UTI pathogenesis, often resulting in adverse health outcomes. Dr adhesin bearing Escherichia coli (Dr E. coli) cause recurrent UTIs in menopausal women and acute pyelonephritis in pregnant women. Dr E. coli bind to epithelial cells via host innate immune receptor CD55, under hormonal influence. The role of estrogens or estrogen receptors (ERs) in regulating the innate immune responses in the bladder are poorly understood. In the current study, we investigated the role of ERα, ERβ and GPR30 in modulating the innate immune responses against Dr E. coli induced UTI using human bladder epithelial carcinoma 5637 cells (HBEC). Both ERα and ERβ agonist treatment in bladder cells induced a protection against Dr E. coli invasion via upregulation of TNFα and downregulation of CD55 and IL10, and these effects were reversed by action of ERα and ERβ antagoinsts. In contrast, the agonist-mediated activation of GPR30 led to an increased bacterial colonization due to suppression of innate immune factors in the bladder cells, and these effects were reversed by the antagonist-mediated suppression of GPR30. Further, siRNA-mediated ERα knockdown in the bladder cells reversed the protection against bacterial invasion observed in the ERα positive bladder cells, by modulating the gene expression of TNFα, CD55 and IL10, thus confirming the protective role of ERα. We demonstrate for the first time a protective role of nuclear ERs, ERα and ERβ but not of membrane ER, GPR30 against Dr E. coli invasion in HBEC 5637 cells. These findings have many clinical implications and suggest that ERs may serve as potential drug targets towards developing novel therapeutics for regulating local innate immunity and treating UTIs.

Effect of vaginal or systemic estrogen on dynamics of collagen assembly in the rat vaginal wall

The objective of this study was to compare the effects of systemic and local estrogen treatment on collagen assembly and biomechanical properties of the vaginal wall. Ovariectomized nulliparous rats were treated with estradiol or conjugated equine estrogens (CEEs) either systemically, vaginal CEE, or vaginal placebo cream for 4 wk. Low-dose local CEE treatment resulted in increased vaginal epithelial thickness and significant vaginal growth without uterine hyperplasia. Furthermore, vaginal wall distensibility increased without compromise of maximal force at failure. Systemic estradiol resulted in modest increases in collagen type I with no change in collagen type III mRNA. Low-dose vaginal treatment, however, resulted in dramatic increases in both collagen subtypes whereas moderate and high dose local therapies were less effective. Consistent with the mRNA results, low-dose vaginal estrogen resulted in increased total and cross-linked collagen content. The inverse relationship between vaginal dose and collagen expression may be explained in part by progressive downregulation of estrogen receptor-alpha mRNA with increasing estrogen dose. We conclude that, in this menopausal rat model, local estrogen treatment increased total and cross-linked collagen content and markedly stimulated collagen mRNA expression in an inverse dose-effect relationship. High-dose vaginal estrogen resulted in downregulation of estrogen receptor-alpha and loss of estrogen-induced increases in vaginal collagen. These results may have important clinical implications regarding the use of local vaginal estrogen therapy and its role as an adjunctive treatment in women with loss of vaginal support.

Dietary phytoestrogen improves relaxant responses to 17-β-estradiol in aged but not ovariectomised rat bladders

This study examined the effect of age, ovariectomy and dietary phytoestrogen ingestion on 17-β-estradiol-mediated relaxant responses and messenger RNA (mRNA) and protein expression of oestrogen receptor subtypes in the rat isolated bladder. Female Wistar rats (8 weeks) were anaesthetised, and the ovaries were removed (ovx) or left intact (sham). Rats were fed either normal rat chow (soy, phytoestrogens) or a non-soy (phytoestrogen free) diet. Isolated bladder from rats aged 12, 24 or 52 weeks were pre-contracted with 3 μM carbachol prior to obtaining a concentration response curve to 17-β-estradiol. Protein and mRNA expression of the oestrogen receptor subtypes was completed using immunohistochemistry and real-time PCR, respectively. Relatively moderate relaxant responses to 17-β-estradiol were observed in bladders from all age and treatment groups. However, in soy-fed sham 52-week-old rats, the bladder exhibited enhanced relaxant responses to 17-β-estradiol when compared to tissues from other age-matched rat treatment groups (P < 0.05). In bladders from female rats, the mRNA and protein expression of oestrogen receptors β was significantly greater than the expression of the oestrogen receptor α. Oestrogen receptor α mRNA expression declined with age (P < 0.05), whereas oestrogen receptor β expression did not change in any of the treatment groups (P > 0.05). Diet, overiectomy or age did not alter the protein expression of either oestrogen receptor subtype in the bladder (P > 0.05). While a soy diet improved relaxant effects to the 17-β-estradiol with age, it did not alter relaxant responses in bladders from ovariectomised rats.

[Role of estrogens in lower urinary tract physiology and physiopathology]

GOAL

The aim was to review the literature on estrogens and lower urinary tract.

MATERIAL

A review of literature through the PubMed library until December 31, 2012 was carried out using the following keywords: lower urinary tract, bladder, urethra, nervous central system, innervation, female, women, estrogen, estradiol, urogenital atrophy, urinary incontinence, overactive bladder, urinary tract infection.

RESULTS

On the bladder, estrogens are involved in the trophicity, vascularisation, alpha-adrenergic, cholinergic and muscarinic receptor density, detrusor contractility and inflammation. On the urethra, they impact vascularisation, contractility, urethral pulse and tone, anatomical and functional length. On the neurological control, they act on capsaicin-sensitive afferent fibres, neurological regeneration, nerve growth factor expression and viscerovisceral sensitisation.

CONCLUSION

Estrogens play a major role on the lower urinary tract physiology and physiopathology both on the urethra and the bladder.

[Connective tissue and prolapse genesis]

The pathophysiology of pelvic floor disorders still remains not well understood. Increasing age as well as vaginal multiparity are the main commonly accepted factors. The hypothesis of a defect of connective tissues of the pelvic floor with aging due to collagen deficiency and/or elastic fiber degradation is often highlighted. The issue of a potential protective role of HRT is also discussed although the recent results from the WHI would suggest a negative impact of HRT on urinary incontinence, especially when HRT is initiated in elderly women, far from the menopause. Nevertheless, environmental factors cannot explain the full pathogenesis of pelvic organ prolapse (POP) and the contribution of genetic factors to the development of pelvic floor disorders is widely recognized. Support for a genetic influence on POP derives from reports suggesting that heritability is a strong contributing factor and a familial history of POP is considered as a classical risk factor. However, the characterization of the underlying molecular mechanisms remains limited, since POP may be considered the end result of a multifactorial process leading to destruction of vaginal wall connective tissue. Experimental studies in mice with null mutations in the genes encoding different putative factors involved in elastic fibers remodeling and homeostasis are crucial in the understanding of the pathogenesis of POP. Mice with null mutation in the gene encoding lysyl oxidase-like 1 (LOXL1) or fibulin-5, demonstrate signs of elastinopathy including the development of a POP in the postpartum. Likewise, homeobox genes such as HOXA11, which are essential in the embryonic development of the urogenital tract might also be involved in the pathogenesis of POP. The better understanding of the underlying determinants of pelvic floor disorders with a special focus on genetic factors may offer new therapeutic strategies, in addition to or replacement of surgical procedures.

Relative roles of the epithelial and stromal tissue compartment(s) in mediating the actions of relaxin and estrogen on cell proliferation and apoptosis in the mouse lower reproductive tract

Relaxin and estrogen are secreted by the ovary during the second half of pregnancy in rats and mice. Relaxin promotes marked growth of the lower reproductive tract in both species. Relaxin promotes accumulation of epithelial and stromal cells in the cervix and vagina by both stimulating cell proliferation and inhibiting apoptosis. Estrogen acting through estrogen receptor alpha (ERalpha) plays an essential permissive role in relaxin's actions. A fundamental step toward understanding the actions of relaxin and estrogen is to identify the tissue compartments that initiate their effects. Limited studies using either antibodies to human relaxin receptor (LGR7, RXFP1) or an IRES-LacZ reporter cassette in the LGR7 gene revealed relaxin receptors in subepithelial stroma cells and smooth muscle cells but not in epithelial cells in rodent vaginal and/or cervical tissues. ERalpha has been reported in both stromal and epithelial compartments in the rodent reproductive tract. This chapter describes ongoing studies that use relaxin bioactivity as a means of identifying the tissue compartment(s) that initiates the actions of relaxin and estrogen on the lower reproductive tract. Specifically, a tissue separation-recombination methodology in combination with LGR7 knockout mice was initially used to obtain functional evidence that stromal LGR7 is both necessary and sufficient to promote proliferation and inhibit apoptosis in both stromal and epithelial cells in mouse cervix and vagina. The tissue separation-recombination method is currently being used in conjunction with ERalpha knockout mice to determine if the obligatory permissive effect of estrogen on relaxin-induced cell proliferation occurs through stromal and/or epithelial ERalpha.

Efficacy of Selective Estrogen Receptor Modulators in Nude Mice Bearing Human Transitional Cell Carcinoma

OBJECTIVES

To evaluate estrogen receptors as a therapeutic target for human bladder cancer.

METHODS

The ability of the selective estrogen receptor modulators (SERMs) tamoxifen and raloxifene to inhibit 5637 human transitional cell carcinoma cell proliferation was determined in vitro and in xenograft studies using 5637 cells in female athymic BALB/c nu/nu mice.

RESULTS

Treatment with tamoxifen, raloxifene, or the pure antiestrogen ICI 182,780 inhibited proliferation of 5637 cells in vitro. In the first xenograft study, raloxifene (10, 100, or 1000 microg/day) administered by oral gavage inhibited the growth of tumors compared with placebo or untreated controls (P <0.05). In a second experiment, tamoxifen (8.3, 125, or 1250 microg/day) delivered by time-release pellet inhibited tumor growth compared with placebo-treated controls (P <0.01). A comparison study in which tamoxifen (8.3 or 125 microg/day) or raloxifene (100 microg/day) was administered by slow-release pellet demonstrated that both SERMs reduced growth compared to placebo-treated controls (P <0.05), with comparable effectiveness. There was no detectable tumor in 17 of 30 treated mice. In all studies, average tumor volumes in SERM-treated animals declined over the course of treatment.

CONCLUSIONS

Selective estrogen receptor modulators inhibit the growth of 5637 transitional cell carcinoma cell xenografts, supporting the rationale to evaluate these agents as targeted therapeutics for patients with urothelial carcinoma.

Circulating hormones and estrous stage predict cellular and stromal remodeling in murine uterus

The understanding of how estrogen and progesterone (P4) drive uterine remodeling in rodents has largely been based on studies involving administration of exogenous hormones, using steroid receptor-deficient mice, or relying on vaginal smears. In all these cases, the actual serum levels of 17β-estradiol (E2) and P4are not directly measured, and the relationship between physiological levels of female sex hormones and uterine remodeling in cycling mice has not been fully explored. Here, we measured the circulating levels of E2and P4in cycling mice and performed correlation analysis between hormone levels and epithelial and stromal uterine parameters, irrespective of the estrous stage. In parallel, these parameters were analyzed in relation to the more conventional method of vaginal smear classification of estrous stage. We found that circulating P4inversely correlated with uterine width, luminal epithelial proliferation, stromal apoptosis, and degradation of luminal epithelial basement membrane collagen type-IV. Circulating E2positively correlated with uterine width, stromal cell proliferation, and collagen type-I content, while it negatively correlated with glandular epithelial proliferation, loss of collagen type-IV surrounding glandular epithelium, and apoptosis in luminal, glandular, and stromal compartments. Our findings indicate that measuring P4or E2levels can predict many concurrent cellular and stromal events in the mouse uterus, suggesting that in naturally cycling mice cellular responses to hormone changes are not delayed, but occur very rapidly.

Effects of coumestrol on neonatal and adult mice osteoblasts activities

Estrogen replacement therapy has been shown to reduce postmenopausal osteoporosis. In the present study, we examined the effects of the phytoestrogen coumestrol on neonatal and adult osteoblasts metabolism. Two different sources of osteoblast cells (neonatal mice calvaria and adult mice long bone) cultures were used in this study. The effects of coumestrol on the cellular activities were analyzed by the mitochondrial tetrazolium (MTT) assay, secretion of alkaline phosphatase (ALP), intracellular calcium content (Ca), and the gene expression of bone matrix protein, estrogen receptors (ER-alpha, ER-beta), and osteoprotegerin (OPG) and osteoprotegerin ligand (OPGL). The results showed that the proliferation of neonatal mice osteoblast cells was enhanced by treatment of coumestrol. In the presence of 10(-9)M coumestrol, the osteoblast proliferation attained 139.5% of the control and that the coumestrol can increase the intracellular calcium contents. Type I collagen gene expression was upregulated 167% at the 1st day's culture; ALP gene expression was upregulated 360% at the 7th day's culture; while the osteocalcin gene expression was upregulated 222% at the 14th day's culture. When adult mice osteoblasts were cultured in the presence of 10(-9)M coumestrol, the osteoblasts population increased significantly earlier and attained its maximal effect at the 21st day's culture with 207.4% of control group. The content of ER-beta and osteoprotegerin secretion by neonatal mice control cells gradually increased during osteoblasts differentiation, whereas the ER-alpha and OPGL content were decreased in this study. The cellular responses to the estradiol and counmestrol were quite different in the osteoblasts derived from different age.

Estrogen induced functional hypertrophy and increased force generation of the female rabbit bladder

AIMS

Estrogen is essential for physiological maintenance of the female urogenital tract. It is believed that alterations in female sex hormones play a major role in the etiology and response to urinary tract dysfunctions. In animal studies, ovariectomy (Ovx) results in smooth muscle (SM) weakness and atrophy whereas estrogen supplementation reverses these effects. Our study seeks to establish the mechanisms by which estrogen augmentation results in increased contractility.

METHODS

Twenty New Zealand White female rabbits were separated into five groups of four each. Group 1 served as control, rabbits of groups 2-5 were ovariectomized, group 2 ovariectomized received no estradiol, groups 3-5 were given 17-beta estradiol (1 mg/kg/day) by subcutaneous slow release tablet implant for 1, 3, and 7 days, respectively, beginning 2 weeks after Ovx. At the end of the experimental period, each rabbit was anesthetized and the urinary bladder was removed for contractile, histological, and biochemical studies.

RESULTS

Ovx resulted in significantly decreased bladder contractile function, whereas bladders tested after estradiol administration showed increased contractility. Ovx resulted in a decrease in SM/collagen ratio, whereas estrogen resulted in an increase. The estrogen receptor (ER) density significantly increased following Ovx. After 1 day of estrogen treatment, the ER density decreased significantly below control levels, but rose progressively during the estrogen treatment.

CONCLUSION

The present study demonstrates that estrogen supplementation mediates a "functional hypertrophy," that is a hypertrophy characterized by increased contractile responses to all forms of stimulation, and an increased ratio of SM/collagen.

Expression of estrogen receptors-alpha and -beta in bladder cancer cell lines and human bladder tumor tissue

BACKGROUND

Estrogen receptors (ERs) are known to mediate important physiologic responses as well as the growth of some tumors in response to estradiol stimulation. In a previous study the selective ER modulator raloxifene was shown to induce apoptosis in an ERbeta-positive bladder cancer cell line. However, the expression of ERbeta in human bladder cancer has not been thoroughly investigated.

METHODS

ERalpha and ERbeta expression in 224 bladder tumor samples was evaluated using tissue microarray and immunohistochemistry. Levels of ERalpha and ERbeta protein and mRNA expression were determined in several bladder cancer cell lines using quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot analysis. The effect of estradiol and antiestrogen treatments on RT4 bladder cancer cell growth was determined by cell proliferation assays.

RESULTS

Analyses revealed that only 2 human bladder cancers weakly expressed ERalpha. In contrast, the expression of ERbeta was detected in 141 tumors (63%). ERbeta was expressed in 58% of WHO Grade 1 and 2 tumors, whereas 70% of Grade 3 tumors demonstrated expression (P = .085). Importantly, although only 53% and 55% of Ta and T1 tumors demonstrated ERbeta expression, 80% of T2, 81% of T3, and 75% of T4 tumors showed ERbeta expression. The differences in ERbeta expression between Ta/T1 and T2/T3/T4 tumors were found to be highly significant (P < .001). Metastatic transitional cell carcinomas had ERbeta expression (80%) comparable to that of muscle invasive bladder cancers. Western blot analysis detected ERbeta protein expression in each of the 5 bladder cancer cell lines tested, whereas no or very low levels of ERalpha were found. Quantitative RT-PCR revealed that higher levels of ERbeta than ERalpha mRNA were present in 5637, T-24, TSU-Pr1, and TCC-Sup bladder cancer cells, whereas ER-alpha mRNA levels were greater than ERbeta in RT4 cells. Treatment with 17beta-estradiol modestly increased RT4 cell growth, whereas the antiestrogens, 4-hydroxtamoxifen, raloxifene, or ICI 182,780 inhibited the growth of RT4 cells.

CONCLUSIONS

ERbeta is the dominant receptor expressed in bladder cancer cell lines and in the majority of human bladder tumors. Moreover, the degree of ERbeta expression increases with increasing stage and grade of differentiation. Antiestrogens have an inhibitory effect on the growth of bladder cancer cells in vitro.

Effects of estradiol on spatial learning, hippocampal cytochrome P450 19, and estrogen alpha and beta mRNA levels in ovariectomized female mice

The brain is an important target organ for peripherally synthesized estrogen but it also has its own steroid biosynthesis producing estrogen from testosterone catalyzed by the aromatase enzyme. This study examined the effects of estrogen treatment in two spatial memory tasks, one-arm-baited radial arm maze and a position discrimination task in the T-maze in ovariectomized female mice. Hippocampal cytochrome P450 19 (encoding aromatase), and estrogen receptor alpha and beta gene expressions were also measured using real time quantitative polymerase chain reaction analysis. Estrogen (17beta-estradiol) was administered either tonically via s.c. minipellets or phasically via daily i.p. injections. In ovariectomized mice, the tonic estrogen decreased the number of reference memory errors in radial arm maze. Tonic estrogen treatment also up-regulated the expression of cytochrome P450 19 and estrogen receptors. In contrast, estrogen injections decreased the expression of cytochrome P450 19 and estrogen receptor alpha genes. The number of reference memory errors correlated negatively with estrogen receptor alpha expression. These findings indicate that peripheral estrogen levels affect neuronal estrogen synthesis by regulating the cytochrome P450 19 gene expression and also influence estrogen receptor alpha expression. The results also suggest that tonic rather than cyclic estrogen treatment might be more beneficial for cognitive functions.

Transcriptional regulation of tyrosine hydroxylase by estrogen: opposite effects with estrogen receptors alpha and beta and interactions with cyclic AMP

Reported effects of estrogen administration on tyrosine hydroxylase (TH) gene expression are confusing. Therefore, we studied the mechanism of regulation of TH transcription by estrogen with different estradiol receptor (ER) subtypes. PC12 cells, transiently co-transfected with expression vector for ERalpha or ERbeta, and luciferase gene under control of the TH promoter, were treated with 17 beta-estradiol (E2). E2 doubled luciferase activity with ERalpha; however, it was decreased with ERbeta. Mapping the TH promoter showed that the putative half estrogen response element (ERE) motif at - 675, as well as the activation protein 1 motif at - 205, were not required for response to E2 with either ER. The specificity protein 1/early growth response gene 1 (Egr 1) motif was required for the E2-elicited response with ERbeta, but not with ERalpha. Deletion of the cyclic AMP/Ca2+ response element (CRE/CaRE) nearly abolished E2-triggered responses with either ER. Further analysis revealed an imperfect canonical putative ERE overlapping with CRE/CaRE and Nurr1 response element. Oligonucleotides spanning this ERE displayed binding to ER, Cyclic AMP Response Element Binding Protein (CREB) and other proteins. Moreover, E2 attenuated the increase in TH transcription seen with cyclic AMP analogs. Thus, TH is transcriptionally regulated by estradiol in opposite directions depending on ER subtype. The overlapping ERE and CRE/CaRE may integrate interactions elicited by various regulators of TH transcription including cAMP and estrogens.