Environmental signaling: what embryos and evolution teach us about endocrine disrupting chemicals

Environmental epigenetics and phytoestrogen/phytochemical exposures

One of the most important environmental factors to promote epigenetic alterations in an individual is nutrition and exposure to plant compounds. Phytoestrogens and other phytochemicals have dramatic effects on cellular signaling events, so have the capacity to dramatically alter developmental and physiological events. Epigenetics provides one of the more critical molecular mechanisms for environmental factors such as phytoestrogens/phytochemicals to influence biology. In the event these epigenetic mechanisms become heritable through epigenetic transgenerational mechanisms the impacts on the health of future generations and areas such as evolutionary biology need to be considered. The current review focuses on available information on the environmental epigenetics of phytoestrogen/phytochemical exposures, with impacts on health, disease and evolutionary biology considered. This article is part of a Special Issue entitled 'Phytoestrogens'.

Toxicological characterization of phthalic Acid

There has been growing concern about the toxicity of phthalate esters. Phthalate esters are being used widely for the production of perfume, nail varnish, hairsprays and other personal/cosmetic uses. Recently, exposure to phthalates has been assessed by analyzing urine for their metabolites. The parent phthalate is rapidly metabolized to its monoester (the active metabolite) and also glucuronidated, then excreted. The objective of this study is to evaluate the toxicity of phthalic acid (PA), which is the final common metabolic form of phthalic acid esters (PAEs). The individual PA isomers are extensively employed in the synthesis of synthetic agents, for example isophthalic acid (IPA), and terephthalic acid (TPA), which have very broad applications in the preparation of phthalate ester plasticizers and components of polyester fiber, film and fabricated items. There is a broad potential for exposure by industrial workers during the manufacturing process and by the general public (via vehicle exhausts, consumer products, etc). This review suggests that PA shows in vitro and in vivo toxicity (mutagenicity, developmental toxicity, reproductive toxicity, etc.). In addition, PA seems to be a useful biomarker for multiple exposure to PAEs in humans.

Impact of environmental estrogens on Yfish considering the diversity of estrogen signaling

Research on endocrine disruption in fish has been dominated by studies on estrogen-active compounds which act as mimics of the natural estrogen, 17β-estradiol (E2), and generally exert their biological actions by binding to and activation of estrogen receptors (ERs). Estrogens play central roles in reproductive physiology and regulate (female) sexual differentiation. In line with this, most adverse effects reported for fish exposed to environmental estrogens relate to sexual differentiation and reproduction. E2, however, utilizes a variety of signaling mechanisms, has multifaceted functions and targets, and therefore the toxicological and ecological effects of environmental estrogens in fish will extend beyond those associated with the reproduction. This review first describes the diversity of estrogen receptor signaling in fish, including both genomic and non-genomic mechanisms, and receptor crosstalk. It then considers the range of non-reproductive physiological processes in fish that are known to be responsive to estrogens, including sensory systems, the brain, the immune system, growth, specifically through the growth hormone/insulin-like growth factor system, and osmoregulation. The diversity in estrogen responses between fish species is then addressed, framed within evolutionary and ecological contexts, and we make assessments on their relevance for toxicological sensitivity as well as ecological vulnerability. The diversity of estrogen actions raises questions whether current risk assessment strategies, which focus on reproductive endpoints, and a few model fish species only, are protective of the wider potential health effects of estrogens. Available - although limited - evidence nevertheless suggests that quantitative environmental threshold concentrations for environmental protection derived from reproductive tests with model fish species are protective for non-reproductive effects as well. The diversity of actions of estrogens across divergent physiological systems, however, may lead to and underestimation of impacts on fish populations as their effects are generally considered on one functional process only and this may underrepresent the impact on the different physiological processes collectively.

Environmental alkylphenols modulate cytokine expression in plasmacytoid dendritic cells

BACKGROUND

Alkylphenols, such as nonylphenol (NP) and 4-octylphenol (4-OP), have the potential to disturb immune system due to their weak estrogen-like activity, an effect with potential serious public health impact due to the worldwide distribution of these substances. Plasmacytoid dendritic cells (PDCs) can secrete large amounts of type I IFNs and are critical in immune regulation. However, there has been limited study about the influence of alkylphenols on the function of pDCs.

OBJECTIVE

The aim of this study was to examine the effect of alkylphenols on pDC functions in vitro and in vivo and then further explored the involved signaling pathways and epigenetic changes.

METHODS

Circulating pDCs from human peripheral blood mononuclear cells were treated with alkylphenols with or without CpG stimulation. Alkylphenol-associated cytokine responses, signaling events, histone modifications and viral activity were further examined. In NP-exposed mice, the effect of NP on splenic pDC function and allergic lung inflammation were also assessed.

RESULTS

The results showed that NP increased the expression of TNF-α, but suppressed IL-10 production in the range of physiological doses, concomitant with activation of the MKK3/6-p38 signaling pathway and enhanced levels of acetylated histone 3 as well as histone 4 at the TNFA gene locus. Further, in CpG-stimulated pDCs, NP suppressed type I IFNs production, associated with down-regulation of IRF-7 and MKK1/2-ERK-Elk-1 pathways and led to the impaired anti-enterovirus 71 activity in vitro. Additionally, splenic pDCs from NP-exposed mice showed similar cytokine changes upon CpG stimulation under conditions relevant to route and level of exposure in humans. NP treatment also enhanced allergic lung inflammation in vivo.

CONCLUSION

Alkylphenols may influence pDCs' functions via their abilities to induce expression of a pro-inflammatory cytokine, TNF-α, and to suppress regulatory cytokines, including IL-10, IFN-α and IFN-β, suggesting the potential impact of endocrine disrupting chemicals on immune regulation.

Endocrine disruptors found in food contaminants enhance allergic sensitization through an oxidative stress that promotes the development of allergic airway inflammation

In the past few decades, there has been a significant increase in incidence of allergic diseases. The hygiene hypothesis may provide some clues to explain this rising trend, but it may also be attributable to other environmental factors that exert a proallergic adjuvant effects. However, there is limited information on the risks of developing allergic asthma and related diseases through the ingestion of environmental chemicals found in food contaminants. In the present study, we have shown that oral administration of tributyltin, used as a model environmental chemical, induced oxidative-stress status in the bronchial lymph node, mesenteric lymph node and spleen, but not in the lung, where the initial step of allergic asthma pathogenesis takes place. Mice exposed to tributyltin exhibited heightened Th2 immunity to the allergen with more severe airway inflammation. Tributyltin also induced Treg cells apoptosis preferentially over non-Treg cells. All these effects of tributyltin exposure were canceled by the administration of glutathione monoethyl ester. Meanwhile, tributyltin did not affect airway inflammation of mice transferred with allergen-specific Th2 cells. Collectively, these results suggest that tributyltin exerts its pathological effect during the sensitization phase through oxidative stress that enhances the development of allergic diseases. The current study dissects the pathogenic role of oxidative stress induced by oral exposure to an environmental chemical during the sensitization phase of allergic airway inflammation and would be important for developing therapeutics for prevention of allergic diseases.

In ovo inhibition of steroid metabolism by bisphenol-A as a potential mechanism of endocrine disruption

During embryonic development, endogenous signals, for example steroid hormones, and exogenous signals, for example endocrine disrupting chemicals (EDCs), have the capacity to produce phenotypic effects that persist into adulthood. As the actions of steroids are mediated through the binding of steroid receptors, most studies of EDCs have assumed that they too elicit their effects by binding steroid receptors. We tested an alternative hypothesis, namely that EDCs elicit their effects during embryonic development by disrupting the metabolism of maternally derived steroids, thereby allowing maternally derived steroids to bind steroid receptors and elicit effects. Specifically, we examined the ability of the EDC, bisphenol-A (BPA) to inhibit the normal metabolism of oestradiol during the first nine days of embryonic development in the red-eared slider turtle (Trachemys scripta). We found that, when BPA was present, oestrogen metabolism was inhibited when compared to control eggs. In particular, the formation of oestrone sulfate was blocked in BPA-treated eggs. We postulate that the oestrogenic effects of EDCs may be driven, at least in part, by inappropriate oestrogen signalling. The retention of oestrogens at points of development when they would normally be metabolized to inactive forms might also help explain low-dose effects frequently reported for EDCs.

Prenatal testosterone exposure worsen the reproductive performance of male rat at adulthood

The reproductive system is extremely susceptible to environmental insults, for example exogenous steroids during gestational development and differentiation. Experimental induction of androgen excess during prenatal life in female animal models reprograms their reproductive physiology, however the fetal programming of the male reproductive system by androgen excess has not been well studied. We aimed to determine the effect of prenatal exposure of two different doses of testosterone on different gestational days, on the male reproductive system using a rat model. Sixteen pregnant rats were randomly divided into two experimental groups and two control groups. Experimental group І were subcutaneously injected with 3 mg free testosterone on gestational days 16-19 and its controls received solvent for that time; experimental group П were subcutaneously injected with 20 mg free testosterone on day 20 of gestational period and its controls received solvent at the same time. The reproductive system morphology and function of 32 male offspring of these study groups were compared at days 6-30-60 of age and after puberty. The anogenital distance of the male offspring of both experimental groups had no significant differences on the different days of measurement, compared with controls. In the offspring of experimental group І, the testes weight, number of Sertoli, Spermatocyte and Spermatid cells, sperm count and motility and the serum concentration of testosterone after puberty were significantly decreased; except for reduction of sperm motility (p< 0.01), the other effects were not observed in the offspring of experimental group ІІ. In summary, our data show that prenatal exposure of male rat fetuses to excess testosterone disrupted reproductive function, an effect highly dependent on the time, duration and level of exposure. It seems that the reproductive system in individuals exposed to high levels of androgens during fetal life should be evaluated at puberty and likely to be treated.

Bisphenol S disrupts estradiol-induced nongenomic signaling in a rat pituitary cell line: effects on cell functions

BACKGROUND

Bisphenol A (BPA) is a well-known endocrine disruptor that imperfectly mimics the effects of physiologic estrogens via membrane-bound estrogen receptors (mERα, mERβ, and GPER/GPR30), thereby initiating nongenomic signaling. Bisphenol S (BPS) is an alternative to BPA in plastic consumer products and thermal paper.

OBJECTIVE

To characterize the nongenomic activities of BPS, we examined signaling pathways it evoked in GH3/B6/F10 rat pituitary cells alone and together with the physiologic estrogen estradiol (E2). Extracellular signal-regulated kinase (ERK)- and c-Jun-N-terminal kinase (JNK)-specific phosphorylations were examined for their correlation to three functional responses: proliferation, caspase activation, and prolactin (PRL) release.

METHODS

We detected ERK and JNK phosphorylations by fixed-cell immunoassays, identified the predominant mER initiating the signaling with selective inhibitors, estimated cell numbers by crystal violet assays, measured caspase activity by cleavage of fluorescent caspase substrates, and measured PRL release by radioimmunoassay.

RESULTS

BPS phosphoactivated ERK within 2.5 min in a nonmonotonic dose-dependent manner (10-15 to 10-7 M). When combined with 10-9 M E2, the physiologic estrogen's ERK response was attenuated. BPS could not activate JNK, but it greatly enhanced E2-induced JNK activity. BPS induced cell proliferation at low concentrations (femtomolar to nanomolar), similar to E2. Combinations of both estrogens reduced cell numbers below those of the vehicle control and also activated caspases. Earlier activation of caspase 8 versus caspase 9 demonstrated that BPS initiates apoptosis via the extrinsic pathway, consistent with activation via a membrane receptor. BPS also inhibited rapid (≤ 1 min) E2-induced PRL release.

CONCLUSION

BPS, once considered a safe substitute for BPA, disrupts membrane-initiated E2-induced cell signaling, leading to altered cell proliferation, cell death, and PRL release.

History, biology, and health inequities: emergent embodied phenotypes and the illustrative case of the breast cancer estrogen receptor

How we think about biology--in historical, ecological, and societal context--matters for framing causes of and solutions to health inequities. Drawing on new insights from ecological evolutionary developmental biology and ecosocial theory, I question dominant gene-centric and ultimately static approaches to conceptualizing biology, using the example of the breast cancer estrogen receptor (ER). Analyzed in terms of its 4 histories--societal, individual (life course), tumor (cellular pathology), and evolutionary--the ER is revealed as a flexible characteristic of cells, tumors, individuals, and populations, with magnitudes of health inequities tellingly changing over time. This example suggests our science will likely be better served by conceptualizing disease and its biomarkers, along with changing magnitudes of health inequities, as embodied history--that is, emergent embodied phenotype, not innate biology.

Human infertility: are endocrine disruptors to blame?

Over recent decades, epidemiological studies have been reporting worrisome trends in the incidence of human infertility rates. Extensive detection of industrial chemicals in human serum, seminal plasma and follicular fluid has led the scientific community to hypothesise that these compounds may disrupt hormonal homoeostasis, leading to a vast array of physiological impairments. Numerous synthetic and natural substances have endocrine-disruptive effects, acting through several mechanisms. The main route of exposure to these chemicals is the ingestion of contaminated food and water. They may disturb intrauterine development, resulting in irreversible effects and may also induce transgenerational effects. This review aims to summarise the major scientific developments on the topic of human infertility associated with exposure to endocrine disruptors (EDs), integrating epidemiological and experimental evidence. Current data suggest that environmental levels of EDs may affect the development and functioning of the reproductive system in both sexes, particularly in foetuses, causing developmental and reproductive disorders, including infertility. EDs may be blamed for the rising incidence of human reproductive disorders. This constitutes a serious public health issue that should not be overlooked. The exposure of pregnant women and infants to EDs is of great concern. Therefore, precautionary avoidance of exposure to EDs is a prudent attitude in order to protect humans and wildlife from permanent harmful effects on fertility.

Epigenetic transgenerational inheritance of vinclozolin induced mouse adult onset disease and associated sperm epigenome biomarkers

The endocrine disruptor vinclozolin has previously been shown to promote epigenetic transgenerational inheritance of adult onset disease in the rat. The current study was designed to investigate the transgenerational actions of vinclozolin on the mouse. Transient exposure of the F0 generation gestating female during gonadal sex determination promoted transgenerational adult onset disease in F3 generation male and female mice, including spermatogenic cell defects, testicular abnormalities, prostate abnormalities, kidney abnormalities and polycystic ovarian disease. Pathology analysis demonstrated 75% of the vinclozolin lineage animals developed disease with 34% having two or more different disease states. Interestingly, the vinclozolin induced transgenerational disease was observed in the outbred CD-1 strain, but not the inbred 129 mouse strain. Analysis of the F3 generation sperm epigenome identified differential DNA methylation regions that can potentially be utilized as epigenetic biomarkers for transgenerational exposure and disease.

The effect of estrogen compounds on human embryoid bodies

Human embryonic stem cells are derived from the inner cell mass of preimplantation embryo at the blastocyst stage and their differentiation occurs through an intermediate step involving the formation of embryoid bodies (EBs), which are aggregates of embryonic stem cells. The EBs seem to be a powerful tool for investigating the development of embryos, as they can mimic the initial stages of embryonic development. In this study, we aimed to investigate the effect of estrogen compounds on the proliferation and differentiation of short-term and long-term cultured EBs in vitro. For this study, 10-day-old (short-term cultured) and 30-day-old (long-term cultured) EBs were subjected to estradiol (E2), estriol (E3), selective estrogen receptor modulator (raloxifene [RLX]), bisphenol A, and 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole for 7 days. To confirm the effects of estrogen treatment, ICI-182780 was added to the respective EBs for additional 7 days following estrogen treatment. Quantitative reverse transcription-polymerase chain reaction was performed to analyze the relative expression of differentiation marker genes representing the 3 germ layers. The expression of 7 marker genes, which included α-fetoprotein, hepatocyte nuclear factor (HNF)-3β, HNF-4α (endoderm), brachyury, cardiac actin ([cACT]; mesoderm), nestin (ectoderm), and Oct-4 (undifferentiated), was measured. Significantly, lower expression of HNF-4α in both short-term and long-term cultured EBs was observed after treatment of estrogen compounds compared to control. The expression of HNF-3β in short-term cultured EBs has been positively affected by E2, E3, and RLX. Regarding cACT, higher expression was observed after treatment of E2 (10(-7) mol/L) and E3 (10(-9) mol/L) in short-term cultured EBs, but opposite effects were demonstrated in long-term cultured EBs. The lower expressions of HNF-4α by E2 and RLX were negated by ICI-182780 treatment, although these findings were not statistically significant in E3-treated group. These findings suggest that estrogen compounds have effects on endodermal and mesodermal differentiation of human EBs.

The organochlorine o,p'-DDT plays a role in coactivator-mediated MAPK crosstalk in MCF-7 breast cancer cells

BACKGROUND

The organochlorine dichlorodiphenyltrichloroethane (DDT), a known estrogen mimic and endocrine disruptor, has been linked to animal and human disorders. However, the detailed mechanism(s) by which DDT affects cellular physiology remains incompletely defined.

OBJECTIVES

We and others have shown that DDT activates cell-signaling cascades, culminating in the activation of estrogen receptor-dependent and -independent gene expression. Here, we identify a mechanism by which DDT alters cellular signaling and gene expression, independent of the estrogen receptor.

METHODS

We performed quantitative polymerase chain reaction array analysis of gene expression in MCF-7 breast cancer cells using either estradiol (E₂) or o,p´-DDT to identify distinct cellular gene expression responses. To elucidate the mechanisms by which DDT regulates cell signaling, we used molecular and pharmacological techniques.

RESULTS

E₂ and DDT treatment both altered the expression of many of the genes assayed, but up-regulation of vascular endothelial growth factor A (VEGFA) was observed only after DDT treatment, and this increase was not affected by the pure estrogen receptor α antagonist ICI 182780. Furthermore, DDT increased activation of the HIF-1 response element (HRE), a known enhancer of the VEGFA gene. This DDT-mediated increase in HRE activity was augmented by the coactivator CBP (CREB-binding protein) and was dependent on the p38 pathway.

CONCLUSIONS

DDT up-regulated the expression of several genes in MCF-7 breast cancer cells that were not altered by treatment with E₂, including VEGFA. We propose that this DDT-initiated, ER-independent stimulation of gene expression is due to DDT's ability to initiate crosstalk between MAPK (mitogen-activated protein kinase) signaling pathways and transcriptional coactivators.

Immunomodulatory effects of environmental endocrine disrupting chemicals

During recent decades more than 100,000 new chemicals have been introduced as common consumer products into our environment. Among these chemicals, endocrine-disrupting chemicals (EDCs) are of particular concern owing to their toxicity in animal studies and their impacts on human health. EDCs are ubiquitous in the environment, including the air, water, and soil. The endocrine-disrupting effect of EDCs has been found to imitate the action of steroid hormones and promote several endocrine and reproductive disorders in both animal and human studies. In the present review, we focus on the effects of EDCs on the immune system. EDCs interfere with the synthesis of cytokines, immunoglobulins, and inflammatory mediators, and they also affect the activation and survival of immune cells. The dysfunction of the immune system caused by EDCs may lead to the attenuation of immunity (immunodeficiency) against infection or hyperreactivity of immune responses (allergy and autoimmune disease). In this review, we summarize epidemiologic, animal, and cell studies to demonstrate the potential effects of EDCs on immunity, allergy, and autoimmune diseases. We also address the impact of EDCs on epigenetic regulation.

Prematurely elevating estradiol in early baboon pregnancy suppresses uterine artery remodeling and expression of extravillous placental vascular endothelial growth factor and α1β1 and α5β1 integrins

We previously showed that advancing the increase in estradiol levels from the second to the first third of baboon pregnancy suppressed placental extravillous trophoblast (EVT) invasion and remodeling of the uterine spiral arteries. Cell culture studies show that vascular endothelial cell growth factor (VEGF) plays a central role in regulating EVT migration and remodeling of the uterine spiral arteries by increasing the expression/action of certain integrins that control extracellular matrix remodeling. To test the hypothesis that the estradiol-induced reduction in vessel remodeling in baboons is associated with an alteration in VEGF and integrin expression, extravillous placental VEGF and integrin expression was determined on d 60 of gestation (term is 184 d) in baboons in which uterine artery transformation was suppressed by maternal estradiol administration on d 25-59. EVT uterine spiral artery invasion was 5-fold lower (P < 0.01), and VEGF protein expression, quantified by in situ proximity ligation assay, was 50% lower (P < 0.05) in the placenta anchoring villi of estradiol-treated than in untreated baboons. α1β1 and α5β1 mRNA levels in cells isolated by laser capture microdissection from the anchoring villi and cytotrophoblastic shell of estradiol-treated baboons were over 2-fold (P < 0.01) and 40% (P < 0.05) lower, respectively, than in untreated animals. In contrast, placental extravillous αvβ3 mRNA expression was unaltered by estradiol treatment. In summary, extravillous placental expression of VEGF and α1β1 and α5β1 integrins was decreased in a cell- and integrin-specific manner in baboons in which EVT invasion and remodeling of the uterine spiral arteries were suppressed by prematurely elevating estradiol levels in early pregnancy. We propose that estrogen normally controls the extent to which the uterine arteries are transformed by placental EVT in primate pregnancy by regulating expression of VEGF and particular integrin extracellular remodeling molecules that mediate this process.

Haplotype analysis of ESR2 in Japanese patients with spermatogenic failure

The prevalence of spermatogenic failure (SF) has gradually increased during the past few decades at least in several countries. Although multiple factors would be involved in this phenomenon, one important factor would be excessive estrogen effects via estrogen receptors (ERs). Thus, we performed haplotype analysis of ESR2 encoding ERβ in 125 Japanese SF patients and 119 age-matched control males, using single nucleotide polymorphisms (SNPs) 1-9 that are widely distributed on the ~120-kb genomic sequence of ESR2. Consequently, a linkage disequilibrium (LD) block was detected in an ~60-kb region encompassing SNPs 2-7 in both groups, and four major estimated haplotypes were identified within the LD block. Furthermore, the most prevalent 'TGTAGA' haplotype was found to be significantly associated with SF, with the P-value obtained by the Cochran-Armitage trend test (0.0029) being lower than that obtained by a 100 000-times permutation test (0.0038) to cope with the problem of multiple comparisons. The results, in conjunction with our previous data indicating lack of a susceptibility factor on ESR1 encoding ERα, imply that the specific 'TGTAGA' haplotype of ESR2 raises the susceptibility to the development of SF.

Impact of endocrine-disrupting compounds (EDCs) on female reproductive health

Evidence is accumulating that environmental chemicals (ECs) including endocrine-disrupting compounds (EDCs) can alter female reproductive development, fertility and onset of menopause. While not as clearly defined as in the male, this set of abnormalities may constitute an Ovarian Dysgenesis Syndrome with at least some origins of the syndrome arising during foetal development. ECs/EDCs have been shown to affect trophoblast and placental function, the female hypothalamo-pituitary-gonadal axis, onset of puberty and adult ovarian function. The effects of ECs/EDCs are complex, not least because it is emerging that low-level, 'real-life' mixtures of ECs/EDCs may carry significant biological potency. In addition, there is evidence that ECs/EDCs can alter the epigenome in a sexually dimorphic manner, which may lead to changes in the germ line and perhaps even to transgenerational effects. This review summarises the evidence for EC, including EDC, involvement in female reproductive dysfunction, it highlights potential mechanisms of EC action in the female and emphasises the need for further research into EC effects on female development and reproductive function.

Environmental signaling and reproduction: a comparative biological and chemical perspective

Reproduction is a critical element of life. Self-propagation in all living organisms ranging from bacteria to humans involves numerous common strategies. Underlying all reproductive strategies is the essential need for signaling molecules to initiate and maintain the process. In this paper we use comparative biological and chemical approaches to explore the origins and distribution of estrogen signaling as a pathway common to many life forms. In the process we illuminate the mechanisms whereby environmental agents alter reproduction and development. These mechanisms involve altered signaling pathways within cells and shifts in the targets of the signaling pathways to include regulators of gene transcription normally associated with other pathways. We also stress the role of signal cross talk in mediating hormone action.

Endocrine disrupting chemicals promote the growth of ovarian cancer cells via the ER-CXCL12-CXCR4 signaling axis

The majority of ovarian cancers over-express the estrogen receptor (ERα) and grow in response to estrogens. We previously demonstrated that ER induction of the chemokine CXCL12 (stromal cell-derived factor-1) is required for estradiol (E2)-stimulated proliferation of human ovarian carcinoma cells. In the current study, we report that known "endocrine disrupting chemicals" (EDCs) display mitogenic activities in ovarian cancer cells via their ability to activate the ER and upregulate CXCL12 expression. Notably, the EDCs genistein, bisphenol A and HPTE stimulated both cell proliferation and induction of CXCL12 mRNA and protein in a manner comparable to estradiol. The effects were completely attenuated by the ER antagonist ICI 182,780, revealing that observed activities of these agents were receptor-mediated. In cell proliferation assays, the mitogenic effects of estradiol and EDCs were obviated by siRNAs targeting CXCL12 and restored upon addition of exogenous CXCL12. Furthermore, an inhibitor to the CXCL12 receptor CXCR4 completely attenuated growth-stimulatory effects of E2 and EDCs. These studies highlight a potential role of EDCs possessing estrogenic activities in the etiology of ovarian cancer. Moreover, they suggest that the ER-CXCL12-CXCR4 signaling axis may represent a promising target for development of therapeutics for ER+ ovarian cancers.

Perinatal programming of adult rat germ cell death after exposure to xenoestrogens: role of microRNA miR-29 family in the down-regulation of DNA methyltransferases and Mcl-1

Different studies have pointed out that developmental exposure to environmental endocrine disruptors can induce long-term testicular germ cell death probably through epigenetic mechanisms. By using a model of early neonatal post-natal day (PND) 1 to 5 exposure of male rats to a xenoestrogen, estradiol benzoate (EB), we investigated the role of microRNA and DNA methyltransferases (DNMT) on the developmental effects of EB on the adult germ cell death process. Neonatal exposure to EB induced adult germ cell apoptosis together with a dose-dependent increase in miR-29a, miR-29b, and miR-29c expression. Increased miR-29 expression resulted in a decrease in DNMT1, DNMT3a, and DNMT3b and antiapoptotic myeloid cell leukemia sequence 1 (Mcl-1) protein levels as shown in 1) germ cells of adult rats exposed neonatally to EB and 2) in spermatogonial GC-1 transfected with miR-29. The DNMT decrease was associated with a concomitant increase in transcript levels of DNA methylation target genes, such as L1td1-1 ORF1 and ORF2, Cdkn2a, and Gstp1, in correlation with their pattern of methylation. Finally, GC-1 cell lines transfection with miR-29a, miR-29b, or miR-29c undergo apoptosis evidenced by Annexin-V expression. Together, the increased miR-29 with a subsequent reduction in DNMT and Mcl-1 protein levels may represent a basis of explanation for the adult expression of the germ cell apoptosis phenotype. These observations suggest that the increased expression of the "apoptomir" miR-29 family represents the upstream mechanism identified until now that is involved in adult germ cell apoptosis induced by a neonatal hormonal disruption.

The Interplay between Estrogen and Fetal Adrenal Cortex

Estrogen is a steroid hormone that regulates embryogenesis, cell proliferation and differentiation, organogenesis, the timing of parturition, and fetal imprinting by carrying chemical messages from glands to cells within tissues or organs in the body. During development, placenta is the primary source of estrogen production but estrogen can only be produced if the fetus or the mother supplies dehydroepiandrosterone (DHEA), the estrogen prohormone. Studies show that the fetal zone of the fetal adrenal cortex supplies 60% of DHEA for placental estrogen production, and that placental estrogen in turn modulates the morphological and functional development of the fetal adrenal cortex. As such, in developed countries where humans are exposed daily to environmental estrogens, there is concern that the development of fetal adrenal cortex, and in turn, placental estrogen production may be disrupted. This paper discusses fetal adrenal gland development, how endogenous estrogen regulates the structure and function of the fetal adrenal cortex, and highlights the potential role that early life exposure to environmental estrogens may have on the development and endocrinology of the fetal adrenal cortex.

Suppression of trophoblast uterine spiral artery remodeling by estrogen during baboon pregnancy: impact on uterine and fetal blood flow dynamics

The present study was conducted to determine the impact of suppressing trophoblast remodeling of the uterine spiral arteries by prematurely elevating estrogen levels in the first trimester of baboon pregnancy on uterine and umbilical blood flow dynamics. Uteroplacental blood flow was assessed by Doppler ultrasonography after acute administration of saline (basal state) and serotonin on days 60, 100, and 160 of gestation (term: 184 days) to baboons in which uterine spiral artery remodeling had been suppressed by the administration of estradiol on days 25-59 of gestation. Maternal blood pressure in the basal state was increased (P < 0.01), and uterine artery diastolic notching and the umbilical artery pulsatility index and systolic-to-diastolic ratio, reflecting downstream flow impedance, were increased (P < 0.01) after serotonin administration on day 160, but not earlier, in baboons treated with estradiol in early gestation. These changes in uteroplacental flow dynamics in serotonin-infused, estradiol-treated animals were accompanied by a decrease (P < 0.05) in uterine and umbilical artery volume flow and fetal bradycardia. The results of this study show that suppression of uterine artery remodeling by advancing the rise in estrogen from the second trimester to the first trimester disrupted uteroplacental blood flow dynamics and fetal homeostasis after vasochallenge late in primate pregnancy.

PCBs, PBDEs and organochlorine pesticides in crabs Hepatus pudibundus and Callinectes danae from Santos Bay, State of São Paulo, Brazil

The occurrence of persistent organic pollutants (POPs) as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDE) in crabs Hepatus pudibundus and Callinectesdanae was assessed from two different places inside of the Santos Bay and Moela Island near one of the most economically important metropolitan areas in Southern Brazil. Among POPs analyzed, ∑PCBs (222-923 ng g(-1)lipid weight) and ∑DDTs (154-410 ng g(-1)lw) exhibited the highest concentrations in the crabs. ∑HCHs ranged from 10.3 to 30.9 ng g(-1)lw and were found in all individuals. Other OCPs found in lower concentration was Mirex (7.6-41.6 ng g(-1)lw) and HCB (5.83-16.9 ng g(-1)lw). ∑PBDEs (24.1 ng g(-1)lw) were only found in one male individual from the species C. danae collected near to the submarine sewage of Santos. Male crabs showed higher POP concentrations than female crabs for those two species.

Prenatal exposure to bisphenol A promotes angiogenesis and alters steroid-mediated responses in the mammary glands of cycling rats

Prenatal exposure to BPA disturbs mammary gland histoarchitecture and increases the carcinogenic susceptibility to chemical challenges administered long after BPA exposure. Our aim was to assess the effect of prenatal BPA exposure on mammary gland angiogenesis and steroid hormone pathways in virgin cycling rats. Pregnant Wistar rats were exposed to either 25 or 250 g/kg/day (25 and 250 BPA, respectively) or to vehicle. Female offspring were autopsied on postnatal day (PND) 50 or 110. Ovarian steroid serum levels, the expression of steroid receptors and their co-regulators SRC-3 and SMRT in the mammary gland, and angiogenesis were evaluated. At PND 50, all BPA-treated animals had lower serum levels of progesterone, while estradiol levels remained unchanged. The higher dose of BPA increased mammary ERα and decreased SRC-3 expression at PND 50 and PND 110. SMRT protein levels were similar among groups at PND 50, whereas at PND 110, animals exposed to 250 BPA showed a lower SMRT expression. Interestingly, in the control and 25 BPA groups, SMRT increased from PND 50 to PND 110. At PND 50, an increased vascular area associated with higher VEGF expression was observed in the 250 BPA-treated rats. At PND 110, the vascular area was still increased, but VEGF expression was similar to that of control rats. The present results demonstrate that prenatal exposure to BPA alters the endocrine environment of the mammary gland and its angiogenic process. Increased angiogenesis and altered steroid hormone signals could explain the higher frequency of pre-neoplastic lesions found later in life. This article is part of a Special Issue entitled 'Endocrine disruptors'.

Molecular mechanisms of induction of persistent changes by estrogenic chemicals on female reproductive tracts and external genitalia

The effects of environmental endocrine-disrupting chemicals (EDCs) are a great and growing concern for human and animal development and life. The reproductive organs are considered as a primary target of EDCs, yet the effects on reproductive organs can extend to other body systems. Perinatal diethylstilbestrol (DES)-exposed mice exhibit various reproductive organ abnormalities. The perinatal DES-exposure model has allowed insight into our understanding of the mechanisms of persistent reproductive organ abnormalities elicited by exposure to estrogens and/or estrogenic EDCs. The persistent changes in the vagina of neonatally DES-exposed mice result from sustained expression of growth factors by ligand-independent transcriptional activation of the estrogen receptor. Developmental regulatory genes, such as Wnt and Hox genes, are also targets of DES during fetal stages and altered gene expression can induce malformations of the reproductive organs. In this review, we focus on the development of female reproductive tracts and external genitalia, and discuss the recent progress in understanding the disruptive effects of estrogens and EDCs on these organs.

Endocrine disruption via estrogen receptors that participate in nongenomic signaling pathways

When inappropriate (non-physiologic) estrogens affect organisms at critical times of estrogen sensitivity, disruption of normal endocrine functions can result. Non-physiologic estrogen mimetics (environmental, dietary, and pharmaceutical) can signal rapidly and potently via the membrane versions of estrogen receptors, as can physiologic estrogens. Both physiologic and non-physiologic estrogens activate multiple signaling pathways, leading to altered cellular functions (e.g. peptide release, cell proliferation or death, transport). Xenoestrogens' mimicry of physiologic estrogens is imperfect. When superimposed, xenoestrogens can alter endogenous estrogens' signaling and thereby disrupt normal signaling pathways, leading to malfunctions in many tissue types. Though these xenoestrogen actions occur rapidly via nongenomic signaling pathways, they can be sustained with continuing ligand stimulation, combinations of ligands, and signaling that perpetuates downstream, eventually also impinging on genomic regulation by controlling the activation state of transcription factors. Because via these pathways estrogens and xenoestrogens cause nonmonotonic stimulation patterns, they must be carefully tested for activity and toxicity over wide dose ranges. Nongenomic actions of xenoestrogens in combination with each other, and with physiologic estrogens, are still largely unexplored from these mechanistic perspectives.

Epigenetic perspective on the developmental effects of bisphenol A

Bisphenol A (BPA) is an estrogenic environmental toxin widely used in the production of plastics and ubiquitous human exposure to this chemical has been proposed to be a potential risk to public health. Animal studies suggest that in utero and early postnatal exposure to this compound may produce a broad range of adverse effects, including impaired brain development, sexual differentiation, behavior, and immune function, which could extend to future generations. Molecular mechanisms that underlie the long-lasting effects of BPA continue to be elucidated, and likely involve disruption of epigenetic programming of gene expression during development. Several studies have provided evidence that maternal exposure to BPA results in postnatal changes in DNA methylation status and altered expression of specific genes in offspring. However, further studies are needed to extend these initial findings to other genes in different tissues, and to examine the correlations between BPA-induced epigenetic alterations, changes in gene expression, and various phenotypic outcomes. It will be also important to explore whether the epigenetic effects of BPA are related to its estrogenic activity, and to determine which downstream effector proteins could mediate changes in DNA methylation. In this review, we will highlight research indicating a consequence of prenatal BPA exposure for brain, behavior, and immune outcomes and discuss evidence for the role of epigenetic pathways in shaping these developmental effects. Based on this evidence, we will suggest future directions in the study of BPA-induced epigenetic effects and discuss the transgenerational implications of exposure to endocrine disrupting chemicals.

Epigenetic perturbations in the pathogenesis of mustard toxicity; hypothesis and preliminary results

Among the most readily available chemical warfare agents, sulfur mustard (SM), also known as mustard gas, has been the most widely used chemical weapon. SM causes debilitating effects that can leave an exposed individual incapacitated for days to months; therefore delayed SM toxicity is of much greater importance than its ability to cause lethality. Although not fully understood, acute toxicity of SM is related to reactive oxygen and nitrogen species, oxidative stress, DNA damage, poly(ADP-ribose) polymerase (PARP) activation and energy depletion within the affected cell. Therefore several antioxidants and PARP inhibitors show beneficial effects against acute SM toxicity. The delayed toxicity of SM however, currently has no clear mechanistic explanation. One third of the 100,000 Iranian casualties are still suffering from the detrimental effects of SM in spite of the extensive treatment. We, therefore, made an attempt whether epigenetic aberrations may contribute to pathogenesis of mustard poisoning. Preliminary evidence reveals that mechlorethamine (a nitrogen mustard derivative) exposure may not only cause oxidative stress, DNA damage, but epigenetic perturbations as well. Epigenetic refers to the study of changes that influence the phenotype without causing alteration of the genotype. It involves changes in the properties of a cell that are inherited but do not involve a change in DNA sequence. It is now known that in addition to mutations, epimutations contribute to a variety of human diseases. Under light of preliminary results, the current hypothesis will focus on epigenetic regulations to clarify mustard toxicity and the use of drugs to correct possible epigenetic defects.

Endocrine disrupting chemicals: Multiple effects on testicular signaling and spermatogenesis

In the past 200 years, an enormous number of synthetic chemicals with diverse structural features have been produced for industrial, medical and domestic purposes. These chemicals, originally thought to have little or no biological toxicity, are widely used in our daily lives as well as are commonly present in foods. It was not until the first World Wildlife Federation Wingspread Conference held in 1994 were concerns about the endocrine disrupting (ED) effects of these chemicals articulated. The potential hazardous effects of endocrine disrupting chemicals (EDCs) on human health and ecological well-being are one of the global concerns that affect the health and propagation of human beings. Considerable numbers of studies indicated that endocrine disruption is linked to "the developmental basis of adult disease," highlighting the significant effects of EDC exposure on a developing organism, leading to the propensity of an individual to develop a disease or dysfunction in later life. In this review, we intend to provide environmental, epidemiological and experimental data to associate pollutant exposure with reproductive disorders, in particular on the development and function of the male reproductive system. Possible effects of pollutant exposure on the processes of embryonic development, like sex determination and masculinization are described. In addition, the effects of pollutant exposure on hypothalamus-pituitary-gonadal axis, testicular signaling, steroidogenesis and spermatogenesis are also discussed.

Insights from the structure of estrogen receptor into the evolution of estrogens: implications for endocrine disruption

In the last decade, there has been important progress in understanding the origins and evolution of receptors for adrenal steroids (aldosterone, cortisol) and sex steroids (estradiol, progesterone, testosterone) due to the sequencing of genomes from animals that are at key sites in vertebrate evolution. Although the estrogen receptor [ER] appears to be the ancestral vertebrate steroid receptor and estradiol [E2] is the physiological ligand for vertebrate ERs, the identity of the ancestral ligand(s) for the ER remains unknown. Here, using an analysis of crystal structures of human ERα with E2 and other chemicals and 3D models of human ERα with 27-hydroxycholesterol and 5-androsten-3β,17β-diol, I propose that one or more Δ5 steroids were the ancestral ligands for the ER, with E2 evolving later as the canonical estrogen. The evidence that chemicals with a β-hydroxy at C3 in a saturated A ring can act as estrogens and the conformational flexibility of the vertebrate ER can explain the diversity of synthetic chemicals that disrupt estrogen responses by binding to vertebrate ERs.

Molecular cloning, characterization, and chromosome mapping of reptilian estrogen receptors

In many vertebrates, steroid hormones are essential for ovarian differentiation during a critical developmental stage as well as promoting the growth and differentiation of the adult female reproductive system. Although studies have been extensively conducted in mammals and a few fish, amphibians, and bird species, the molecular mechanisms of sex steroid hormone (estrogens) action have been poorly examined in reptiles. Here, we evaluate hormone receptor and ligand interactions in two species of snake, the Okinawa habu (Protobothrops flavoviridis, Viperidae) and the Japanese four-striped rat snake (Elaphe quadrivirgata, Colubridae) after the isolation of cDNAs encoding estrogen receptor α (ESR1) and estrogen receptor β (ESR2). Using a transient transfection assay with mammalian cells, the transcriptional activity of reptilian (Okinawa habu, Japanese four-striped rat snake, American alligator, and Florida red-belly freshwater turtle) ESR1 and ESR2 was examined. All ESR proteins displayed estrogen-dependent activation of transcription via an estrogen-response element-containing promoter; however, the responsiveness to various estrogens was different. Further, we determined the chromosomal locations of the snake steroid hormone receptor genes. ESR1 and ESR2 genes were localized to the short and long arms of chromosome 1, respectively, whereas androgen receptor was localized to a pair of microchromosomes in the two snake species examined. These data provide basic tools that allow future studies examining receptor-ligand interactions and steroid endocrinology in snakes and also expands our knowledge of sex steroid hormone receptor evolution.

Estrogenic response in male bullfrog (Rana catesbeiana) hepatocytes after single or combined exposure to cadmium (Cd) and 17beta-estradiol (E2)

Contamination by heavy metals and sex hormones in a water environment is an important health issue. In this study, we investigated the estrogenic effects of cadmium (Cd) administration alone and in combination with 17beta-estradiol (E2) on the hepatocytes of male Bullfrog (Rana catesbeiana). Their vitellogenin (VTG) expression and reactive oxygen species (ROS) were analyzed upon exposure to Cd alone or to both Cd and E2. Our results suggest that the VTG levels induced by the co-treatment of 100 nM E2 and 100 nM CdCl(2) were significantly higher than those induced by 100 nM E2 alone (p < 0.05), and were comparable to vitellogenin induction observed with 1 μM E2. A similar result was observed by western blot analysis in the culture medium of hepatocytes. Meanwhile, Cd (but not E2) increased the ROS levels. These results suggest that Cd has a cooperative effect with E2 in the induction of VTG, thus acting as an estrogenic disruptor. Cd also causes oxidative stress that occurs with the enhanced vitellogenesis.

Bisphenol A interferes with synaptic remodeling

The potential adverse effects of Bisphenol A (BPA), a synthetic xenoestrogen, have long been debated. Although standard toxicology tests have revealed no harmful effects, recent research highlighted what was missed so far: BPA-induced alterations in the nervous system. Since 2004, our laboratory has been investigating one of the central effects of BPA, which is interference with gonadal steroid-induced synaptogenesis and the resulting loss of spine synapses. We have shown in both rats and nonhuman primates that BPA completely negates the ∼ 70-100% increase in the number of hippocampal and prefrontal spine synapses induced by both estrogens and androgens. Synaptic loss of this magnitude may have significant consequences, potentially causing cognitive decline, depression, and schizophrenia, to mention those that our laboratory has shown to be associated with synaptic loss. Finally, we discuss why children may particularly be vulnerable to BPA, which represents future direction of research in our laboratory.

Cloning and functional characterization of Chondrichthyes, cloudy catshark, Scyliorhinus torazame and whale shark, Rhincodon typus estrogen receptors

Sex-steroid hormones are essential for normal reproductive activity in both sexes in all vertebrates. Estrogens are required for ovarian differentiation during a critical developmental stage and promote the growth and differentiation of the female reproductive system following puberty. Recent studies have shown that environmental estrogens influence the developing reproductive system as well as gametogenesis, especially in males. To understand the molecular mechanisms of estrogen actions and to evaluate estrogen receptor-ligand interactions in Elasmobranchii, we cloned a single estrogen receptor (ESR) from two shark species, the cloudy catshark (Scyliorhinus torazame) and whale shark (Rhincodon typus) and used an ERE-luciferase reporter assay system to characterize the interaction of these receptors with steroidal and other environmental estrogens. In the transient transfection ERE-luciferase reporter assay system, both shark ESR proteins displayed estrogen-dependent activation of transcription, and shark ESRs were more sensitive to 17beta-estradiol compared with other natural and synthetic estrogens. Further, the environmental chemicals, bisphenol A, nonylphenol, octylphenol and DDT could activate both shark ESRs. The assay system provides a tool for future studies examining the receptor-ligand interactions and estrogen disrupting mechanisms in Elasmobranchii.

Molecular cloning and characterization of ligand- and species-specificity of amphibian estrogen receptors

Estrogens are essential for normal reproductive activity in both males and females as well as for ovarian differentiation during a critical developmental stage in most vertebrates. To understand the molecular mechanisms of estrogen action and to evaluate estrogen receptor ligand interactions in amphibians, we isolated cDNAs encoding the estrogen receptors (ERalpha and ERbeta) from the Japanese firebelly newt (Cynops pyrrhogaster), Tokyo salamander (Hynobius tokyoensis), axolotl (Ambystoma mexicanum), and Raucous toad (Bufo rangeri). Full-length amphibian ER cDNAs were obtained using 5' and 3' rapid amplification of cDNA ends. The predicted amino acid sequences of these amphibian ERs showed a high degree of amino acid sequence identity (over 70%) to each other. We analyzed the relationships of these amphibian ER sequences to other vertebrate ER sequences by constructing a phylogenetic tree. We verified that these were bona fide estrogen receptors using receptor dependent reporter gene assays. We analyzed the effects of natural estrogens, ethinylestradiol, and DDT and its metabolites on the transactivation of the four amphibian species listed above, and Xenopus tropicalis ERs and found that there were species-specific differences in the sensitivity of these ERs to hormones and environmental chemicals. These findings will expand our knowledge of endocrine-disrupting events in amphibians.

Effects of perinatal administration of Bisphenol A on the neuronal nitric oxide synthase expressing system in the hypothalamus and limbic system of CD1 mice

Bisphenol A (BPA) is a well-known plastic-derived pollutant that can bind to oestrogen receptors and is considered an endocrine-disrupting chemical. Its impact on different behaviours in rodents has been largely investigated, however, only a few data are available on its effects upon neural circuits. In the present study, we investigated the long-term effects of early exposure of mice of both sexes to BPA on the nitrinergic system, one of the neural systems involved in the control of sexual behaviour and under the control of gonadal hormones. Mice of both sexes were exposed for eight prenatal and eight postnatal days to BPA that was administered to the mothers. The maternally-exposed mice were sacrificed at the age of 2 months and their brains were sectioned and immunohistochemically treated for the detection of neuronal nitric oxide synthase (nNOS). Significant effects of BPA exposure were detected for the number of immunoreactive cells in the medial preoptic nucleus and in the ventromedial subdivision of the bed nucleus of the stria terminalis, in a sex-oriented and dose-dependent way. These results indicate that BPA has a powerful effect on specific portions of the nNOS-immunoreactive system belonging to the accessory olfactory system that are particularly important for the control of sexual behaviour. In addition, they confirm that perinatal exposure to endocrine-disrupting chemicals, in particular to BPA, may have a high impact on the organisation of specific neural pathways that can later affect complex behaviours and functions.

Metals in human placenta: focus on the effects of cadmium on steroid hormones and leptin

Cadmium and other metallic ions can act as metalloestrogens and endocrine disruptors of reproductive tissues and fetal development in mammals, including humans. The detrimental effects occur with respect to the synthesis of both steroid and polypeptide hormones in the placenta. Leptin is produced by the trophoblast and may regulate fetal organogenesis and development. In human term placentas, concentrations of toxic metals and their effects on steroidogenesis were assessed in healthy parturients (109 non-smokers and 99 smokers) in relation to tobacco smoking. Trace elements (cadmium, lead, iron, zinc and copper) were analyzed in placentas using atomic absorption spectroscopy, and steroid hormones (progesterone and estradiol) were assayed in placental samples by an enzyme-immunometric method. Cadmium concentrations were doubled in placentas of smokers as compared with non-smokers, and placental lead and zinc concentrations increased significantly. Placental concentrations of iron, copper, progesterone and estradiol did not differ. In addition, human trophoblast cells were co-cultured with 0, 5, 10 or 20 microm CdCl(2) for 96 h and leptin mRNA assessed by quantitative polymerase chain reaction. Leptin mRNA declined dose-responsively as a result of CdCl(2) exposure. Collectively, the results confirm that human placental tissue offers a unique opportunity to biomonitor cadmium exposure in both the maternal and the internal fetal environments. In addition, the results strongly suggest that cadmium may cause a decline in placental leptin synthesis, as we have previously shown for placental progesterone production. This may constitute further evidence of the endocrine-disrupting effects of cadmium, as a constituent of tobacco smoke, on reproduction in women.

Specific in vitro toxicity of crude and refined petroleum products: II. Estrogen (alpha and beta) and androgen receptor-mediated responses in yeast assays

The present study is the second in a series aiming at a systematic inventory of specific toxic effects of oils. By employing a recombinant yeast stably transfected with human estrogen receptor-alpha (ERalpha) or -beta (ERbeta) or androgen receptor (AR) and expressing yeast enhanced green fluorescent protein, the (anti-)estrogenicity and (anti-)androgenicity of 11 crude oils and refined products were studied. None of the oils tested had significant estrogenic effects in the ERalpha assay or androgenic effects in the AR assay. However, all oils were capable of inducing estrogenic responses in the ERbeta assay, with several responses being above even the maximal response of the standard 17beta-estradiol (E2). Based on the lowest effect concentrations, the potencies of oils in all the assays were between four and seven orders of magnitude lower than those of the standards E2 or testosterone (T). The potencies of the actual individual petrochemical agonists may, however, be relatively high, considering the complex composition of oils. Additive effects, antagonistic effects, and a synergistic effect were measured in the assays upon coexposure to a fixed concentration of standard (E2 or T) and increasing concentrations of oils. To investigate whether the observed effects were receptor-mediated, coexposures to the synthetic inhibitors ICI 182,780 (ERbeta assay) or flutamide (AR assay), a fixed concentration of standard, and various concentrations of oils were performed. The results suggested that the androgenic effects were receptor mediated, whereas the estrogenic effects may be only partially mediated via the receptor. The present study indicates that oils contain compounds with possible endocrine-disrupting potential, some of them acting via the hormone receptors.

Sources and distribution of organic compounds using passive samplers in Lake Mead national recreation area, Nevada and Arizona, and their implications for potential effects on aquatic biota

The delineation of lateral and vertical gradients of organic contaminants in lakes is hampered by low concentrationsand nondetection of many organic compounds in water. Passive samplers (semipermeable membrane devices [SPMDs] and polar organic chemical integrative samplers [POCIS]) are well suited for assessing gradients because they can detect synthetic organic compounds (SOCs) at pg L(-1) concentrations. Semi-permeable membrane devices and POCIS were deployed in Lake Mead, at two sites in Las Vegas Wash, at four sites across Lake Mead, and in the Colorado River downstream from Hoover Dam. Concentrations of hydrophobic SOCs were highest in Las Vegas Wash downstream from waste water and urban inputs and at 8 m depth in Las Vegas Bay (LVB) where Las Vegas Wash enters Lake Mead. The distribution of hydrophobic SOCs showed a lateral distribution across 10 km of Lake Mead from LVB to Boulder Basin. To assess possible vertical gradient SOCs, SPMDs were deployed at 4-m intervals in 18 m of water in LVB. Fragrances and legacy SOCs were found at the greatest concentrations at the deepest depth. The vertical gradient of SOCs indicated that contaminants were generally confined to within 6 m of the lake bottom during the deployment interval. The high SOC concentrations, warmer water temperatures, and higher total dissolved solids concentrations at depth are indicative of a plume of Las Vegas Wash water moving along the lake bottom. The lateral and vertical distribution of SOCs is discussed in the context of other studies that have shown impaired health of fish exposed to SOCs.

The detection of dioxin- and estrogen-like pollutants in marine and freshwater fishes cultivated in Pearl River Delta, China

In this study we aimed to assess the dioxin- and estrogen-like activities of contaminants extracted from twenty species of freshwater and seawater fishes, using luciferase reporter assays. Transfected MCF7 cells were treated with sample extracts and luciferase activities were then measured at 24-h of post-treatment. The mean values of the detected dioxin- and estrogen-like activities in the freshwater fishes were 25.3 pg TEQ/g ww and 102.3 pM EEQ/g ww whereas in the seawater fishes, the values were 46.2 pg TEQ/g ww and 118.8 pM EEQ/g ww. Using sample-relevant dosage of estrogen, inductions of cell proliferation markers (i.e. retinoblastoma, cyclin D) and stimulations of cell growth were revealed by Western blotting, colony formation and BrdU uptake assays. A cotreatment with TCDD significantly reduced these effects. Using the sample extracts with different dioxin- and estrogen-like activities, similar observation was revealed. The data highlighted the mixture effect of food contaminants on human health.

Epigenetic transgenerational actions of environmental factors in disease etiology

The ability of environmental factors to promote a phenotype or disease state not only in the individual exposed but also in subsequent progeny for successive generations is termed transgenerational inheritance. The majority of environmental factors such as nutrition or toxicants such as endocrine disruptors do not promote genetic mutations or alterations in DNA sequence. However, these factors do have the capacity to alter the epigenome. Epimutations in the germline that become permanently programmed can allow transmission of epigenetic transgenerational phenotypes. This review provides an overview of the epigenetics and biology of how environmental factors can promote transgenerational phenotypes and disease.

Estrogen regulation of placental angiogenesis and fetal ovarian development during primate pregnancy

During human and nonhuman primate pregnancy, an extensive blood vessel network is established within the villous placenta to support fetal growth and follicles develop within the fetal ovary to provide a pool of oocytes for reproductive function in adulthood. These two important developmental events occur in association with a progressive increase in placental estrogen production and levels. This review will describe the developmental processes required for placental vascularization and fetal follicular maturation and recent studies which show that estrogen has an important role in regulating these events.

Modulation of cytokine expression in human myeloid dendritic cells by environmental endocrine-disrupting chemicals involves epigenetic regulation

BACKGROUND

Exposure to environmental endocrine-disrupting chemicals (EDCs) is often associated with dysregulated immune homeostasis, but the mechanisms of action remain unclear.

OBJECTIVES

The aim of this study was to test a hypothesis that EDCs regulate the functions of human dendritic cells, a front-line, immunoregulatory cell type in contact with the environment.

METHODS

We investigated circulating myeloid dendritic cells (mDCs) from five subjects and measured their responses, with or without coculture with autologous T cells, to two common EDCs, nonylphenol (NP) and 4-octylphenol (4-OP). EDC-associated cytokine responses, signaling events, and histone modifications were examined using ELISA, Western blotting, and chromatin immunoprecipitation (ChIP) assays, respectively.

RESULTS

In all cases, mDCs treated with NP or 4-OP demonstrated increased expression of tumor necrosis factor-alpha (TNF-alpha) but decreased baseline and lipopolysaccharide (LPS)-induced (interleukin) (IL)-10 production; the increase in TNF-alpha was partially reversible by an estrogen receptor (ER) antagonist. Activation of the MKK3/6-p38 signaling pathway marked the effect of NP on TNF-alpha expression, concomitant with enhanced levels of methyltranferase complex [mixed-lineage leukemia (MLL) and tryptophan-aspartic acid repeat domain 5 (WDR5)] in the nucleus and of trimethylated H3K4, acetylated H3, and H4 at the TNFA gene locus. Further, up-regulated TNF-alpha expression was significantly suppressed in NP-treated mDCs by a histone acetyltransferase inhibitor. In the presence of NP-treated mDCs, T cells showed increased levels of IL-13 but decreased expression of interferon-gamma.

CONCLUSIONS

These results suggest that NP and 4-OP may have functional effects on the response of mDCs via, in part, the ER, MKK3/6-p38 MAPK signaling pathway, and histone modifications, with subsequent influence on the T-cell cytokine responses.