Xenoestrogens at picomolar to nanomolar concentrations trigger membrane estrogen receptor-alpha-mediated Ca2+ fluxes and prolactin release in GH3/B6 pituitary tumor cells

BPA qualtitative and quantitative assessment associated with orthodontic bonding in vivo

OBJECTIVE

To assess the in vivo amount of BPA released from a visible light-cured orthodontic adhesive, immediately after bracket bonding.

METHODS

20 orthodontic patients were recruited after obtaining informed consent. All patients received 24 orthodontic brackets in both dental arches. In Group A (11 patients), 25 ml of tap water were used for mouth rinsing, whereas in Group B (9 patients) a simulated mouth rinse formulation was used: a mixture of 20 ml de-ionized water plus 5 ml absolute ethanol. Rinsing solutions were collected before, immediately after placing the orthodontic appliances and after washing out the oral cavity and were then stored in glass tubes. Rinsing was performed in a single phase for 60s with the entire volume of each liquid. The BPA analysis was performed by gas chromatography-mass spectrometry.

RESULTS

An increase in BPA concentration immediately after the 1st post-bonding rinse was observed, for both rinsing media, which was reduced after the 2nd post-bonding rinse. Water exhibited higher levels of BPA concentration than water/ethanol after 1st and 2nd post-bonding rinses. Two-way mixed Repeated Measures ANOVA showed that the primary null hypothesis declaring mean BPA concentration to be equal across rinsing medium and rinsing status was rejected (p-value <0.001). The main effects of the rinsing medium and status, as well as their interaction were found to be statistically significant (p-values 0.048, <0.001 and 0.011 respectively).

SIGNIFICANCE

A significant pattern of increase of BPA concentration, followed by a decrease that reached the initial values was observed. The amount of BPA was relatively low and far below the reference limits of tolerable daily intake.

Neonatal exposure to xenoestrogens impairs the ovarian response to gonadotropin treatment in lambs

Bisphenol A (BPA) and diethylstilbestrol (DES) are xenoestrogens, which have been associated with altered effects on reproduction. We hypothesized that neonatal xenoestrogen exposure affects the ovarian functionality in lambs. Thus, we evaluated the ovarian response to exogenous ovine FSH (oFSH) administered from postnatal day 30 (PND30) to PND32 in female lambs previously exposed to low doses of DES or BPA (BPA50: 50 μg/kg per day, BPA0.5: 0.5 μg/kg per day) from PND1 to PND14. We determined: i) follicular growth, ii) circulating levels of 17β-estradiol (E2), iii) steroid receptors (estrogen receptor alpha, estrogen receptor beta, and androgen receptor (AR)) and atresia, and iv) mRNA expression levels of the ovarian bone morphogenetic protein (BMPs) system (BMP6, BMP15, BMPR1B, and GDF9) and FSH receptor (FSHR). Lambs neonatally exposed to DES or BPA showed an impaired ovarian response to oFSH with a lower number of follicles ≥2 mm in diameter together with a lower number of atretic follicles and no increase in E2 serum levels in response to oFSH treatment. In addition, AR induction by oFSH was disrupted in granulosa and theca cells of lambs exposed to DES or BPA. An increase in GDF9 mRNA expression levels was observed in oFSH-primed lambs previously treated with DES or BPA50. In contrast, a decrease in BMPR1B was observed in BPA0.5-postnatally exposed lambs. The modifications in AR, GDF9, and BMPR1B may be associated with the altered ovarian function due to neonatal xenoestrogen exposure in response to an exogenous gonadotropin stimulus. These alterations may be the pathophysiological basis of subfertility syndrome in adulthood.

Endocrine disrupting chemicals in the atmosphere: Their effects on humans and wildlife

Endocrine disrupting chemicals (EDCs) are exogenous agents that interfere or disrupt the normal synthesis, secretion, transportation, binding and metabolism of natural hormones; eventually dysregulating homeostatic mechanisms, reproduction and development. They are emitted into the atmosphere during anthropogenic activities and physicochemical reactions in nature. Inhalation of these EDCs as particulate and gaseous vapors triggers their interaction with endocrine glands and exerts agonist or antagonists actions at hormone receptors. The endocrine disruption at nanogram levels of EDC's has gained concern in the last decade, due to infertility among men and women, early puberty, obesity, diabetes and cancer. Thus, the review explores the literature that addresses the major occurring EDCs in the atmosphere including phthalates, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), brominated flame retardants (BFRs), dioxins, alkylphenols (APs) and perfluorinated chemicals (PFCs). Sources, fate, half-life, mechanism, measured concentrations in air, bioaccumulation in tissues, laboratory exposures correlating to toxicological effects of these EDCs in humans and wildlife are discussed.

Non-monotonic dose-response relationships and endocrine disruptors: a qualitative method of assessment

Experimental studies investigating the effects of endocrine disruptors frequently identify potential unconventional dose-response relationships called non-monotonic dose-response (NMDR) relationships. Standardized approaches for investigating NMDR relationships in a risk assessment context are missing. The aim of this work was to develop criteria for assessing the strength of NMDR relationships. A literature search was conducted to identify published studies that report NMDR relationships with endocrine disruptors. Fifty-one experimental studies that investigated various effects associated with endocrine disruption elicited by many substances were selected. Scoring criteria were applied by adaptation of an approach previously used for identification of hormesis-type dose-response relationships. Out of the 148 NMDR relationships analyzed, 82 were categorized with this method as having a "moderate" to "high" level of plausibility for various effects. Numerous modes of action described in the literature can explain such phenomena. NMDR can arise from numerous molecular mechanisms such as opposing effects induced by multiple receptors differing by their affinity, receptor desensitization, negative feedback with increasing dose, or dose-dependent metabolism modulation. A stepwise decision tree was developed as a tool to standardize the analysis of NMDR relationships observed in the literature with the final aim to use these results in a Risk Assessment purpose. This decision tree was finally applied to studies focused on the effects of bisphenol A.

Association of serum bisphenol-A concentration and male reproductive function among exposed workers

Bisphenol-A (BPA) can alter endocrine function in animals, yet the relationship between human exposure to BPA and male reproductive function is not well understood. We collected serum samples from 281 male workers exposed to BPA and 278 controls. Serum BPA concentrations were analyzed by gas chromatography-mass spectrometry after derivatization. The serum levels of sex hormone-binding globulin (SHBG) and total testosterone (TT) were detected by radioimmunoassay and levels of inhibin B (INB) and androstenedione (AD) by enzyme-linked immunosorbent assay. We examined the association of BPA exposure and male sex hormone levels by multivariable linear regression. Both serum BPA concentrations and detection rates were greater in males exposed than those not exposed to BPA, but the two groups did not differ in levels of SHBG, TT, INB, or AD. Compared with exposure for ≤5 years, exposure for >5 years was associated with increased serum BPA and SHBG 1evels and decreased AD levels. Compared with undetectable BPA and BPA ≤ 18.75 ng/mL, BPA level >18.75 ng/mL was associated with low AD and high SHBG levels (P < 0.05). On adjusted multivariable regression, increased serum BPA level was associated with decreased mean serum AD level (0.18 ng/mL; 95% confidence interval CI -0.22 to -0.13) and increased mean serum SHBG level (2.79 nmol/L; 95% CI 2.11-3.46). Serum BPA levels were increased after occupational exposure. BPA exposure was negatively associated with serum AD level but positively associated with serum SHBG level.

Neurological Effects of Bisphenol A and its Analogues

The endocrine disrupting chemical bisphenol A (BPA) is widely used in the production of polycarbonate plastics and epoxy resins. The use of BPA-containing products in daily life makes exposure ubiquitous, and the potential human health risks of this chemical are a major public health concern. Although numerous in vitro and in vivo studies have been published on the effects of BPA on biological systems, there is controversy as to whether ordinary levels of exposure can have adverse effects in humans. However, the increasing incidence of developmental disorders is of concern, and accumulating evidence indicates that BPA has detrimental effects on neurological development. Other bisphenol analogues, used as substitutes for BPA, are also suspected of having a broad range of biological actions. The objective of this review is to summarize our current understanding of the neurobiological effects of BPA and its analogues, and to discuss preventive strategies from a public health perspective.

The effect of the aquatic contaminants bisphenol-A and PCB-95 on the zebrafish lateral line

Environmental toxicants such as bisphenol-A (BPA) and polychlorinated biphenyls (PCBs) are prevalent in our water supply, soil, and many food products and can profoundly affect the central nervous system. Both BPA and PCBs can disrupt endocrine signaling, which is important for auditory development and function, but the effect of these toxicants on the auditory periphery is not understood. In this study we investigated the effect of PCB-95 and BPA on lateral line development, function, and regeneration in larval zebrafish. The lateral line is a system of mechanosensory hair cells on the exterior of the fish that are homologous to the hair cells located in the mammalian inner ear. We found that PCB-95 had no effect on lateral line development or hair cell survival. BPA also did not affect lateral line development, but instead had a significant effect on both hair cell survival and regeneration. BPA-induced hair cell loss is both dose- and time-dependent, with concentrations of 1 μM or higher killing lateral line hair cells during a 24h exposure period. Pharmacologic manipulation experiments suggest that BPA kills hair cells via activation of oxidative stress pathways, similar to prior reports of BPA toxicity in other tissues. We also observed that hair cells killed with neomycin, a known ototoxin, failed to regenerate normally when BPA was present, suggesting that BPA in aquatic environments could impede innate regenerative responses in fishes. Collectively, these data demonstrate that BPA can have detrimental effects on sensory systems, both in aquatic life and perhaps in terrestrial organisms, including humans.

Bisphenol A enhances adipogenic differentiation of human adipose stromal/stem cells

Exposure of humans to the endocrine disrupter bisphenol A (BPA) has been associated with increased weight and obesity. However, the mechanism(s) by which BPA increases adipose tissue in humans remains to be determined. The goal of this study was to determine the effects of BPA on adipogenesis of cultured human adipose stromal/stem cells (ASCs), precursors to mature adipocytes. ASCs from three donors were cultured for either 14 or 21 days in adipogenic differentiation media containing increasing concentrations of BPA (100 pM-10 μM). The extent of adipogenic differentiation in the ASCs was assessed by staining with Oil Red O to visualize adipogenic differentiation and then quantified by extraction and optical density measurement of the retained dye. BPA significantly enhanced adipogenesis at a concentration of 1 μM after 21 days of culture. Additionally, we found that BPA increased transcription of the estrogen receptor (ER (ESR1)) and that treatment with the ER antagonist ICI 182 780, blocked the effects of BPA, indicating that BPA may act via an ER-mediated pathway. The results of molecular analyses indicated that the expression of the adipogenesis-associated genes dual leucine zipper-bearing kinase (DLK (MAP3K12)), IGF1, CCAAT/enhancer-binding protein alpha (C/EBPα (CEBPA)), peroxisome proliferator-activated receptor gamma (PPARγ (PPARG)), and lipoprotein lipase (LPL) was temporally accelerated and increased by BPA. In summary, these results indicate that BPA significantly enhances adipogenesis in ASCs through an ER-mediated pathway at physiologically relevant concentrations.

Determination of urinary levels of Bisphenol A in a Turkish population

Bisphenol A (BPA) is one of the environmental endocrine disrupting chemicals that is widely used in common consumer products. The aim of this study was to report the total urinary BPA concentrations (free plus conjugated) in 200 urine samples (children: 57; male: 74; female: 69) obtained from residents of a Mediterranean city, Mersin. Analyses were performed by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) and for assessing environmental exposure to free BPA and its major metabolite bisphenol A glucuronide (BPAG) in human urine were determinated. Our results indicated that the free BPA and BPAG concentrations were in the range of 0.06-0.99 μg/g creatinine and 0.24-615 μg/g creatinine, respectively. No statistically significant difference obtained in BPA concentrations between genders (male and female) or domicile of residence (rural and urban) (p > 0.05). In our study, the mean level of detected free BPA was 0.46 μg/g creatinine in the urban area and 0.37 μg/g creatinine in the rural area. The average amount of BPAG was 60.56 μg/g creatinine in the urban area and 30.28 μg/g creatinine in the rural area. The data demonstrate that determined amount of total BPA in the present study is lower than the results of similar studies conducted in developed countries. There is no data about the levels of BPA in humans and environment in Turkey. Because of this reason, present study is very important since it is the first study in Turkey which determined the concentrations of free BPA and total BPA in human.

Urinary bisphenol a levels in girls with idiopathic central precocious puberty

OBJECTIVE

Bisphenol A (BPA) is an industrial chemical, particularly used to harden plastics. BPA is thought to have negative health effects on both laboratory animals and humans. Consider ing the decline in age of onset of puberty noted in recent years, particularly among girls, the importance of BPA as an estrogenic endocrine disruptor has increased. In this study, we aimed to determine urinary BPA levels in girls with idiopathic central precocious puberty (ICPP).

METHODS

Non-obese girls newly diagnosed with ICPP (n=28, age 4-8 years) constituted the study group. The control group consisted of 25 healthy age-matched girls with no history of ICPP or any other endocrine disorder. Urinary BPA levels were measured by using high-performance liquid chromatography.

RESULTS

In the ICPP group, urinary BPA levels were significantly higher compared to the control group [median 8.34 (0.84-67.35) μg/g creatinine and 1.62 (0.3-25.79) μg/g creatinine, respectively (OR=8.68, 95% CI:2.03-32.72, p=0.001)]. There was no marked correlation between urinary BPA levels and body mass index in either group. In the ICPP group, no significant correlations were found between urinary BPA levels and serum luteinizing hormone, follicle-stimulating hormone and estradiol levels.

CONCLUSIONS

To our knowledge, this is the first study evaluating the urinary BPA levels in Turkish girls with ICPP. Our results indicate that the estrogenic effects of BPA may be an etiologic factor in ICPP.

In utero exposure to mixtures of xenoestrogens and child neuropsychological development

BACKGROUND

To date, no epidemiological studies have explored the impact and persistence of in utero exposure to mixtures of xenoestrogens on the developing brain. We aimed to assess whether the cumulative effect of xenoestrogens in the placenta is associated with altered infant neuropsychological functioning at two and at four years of age, and if associations differ among boys and girls.

METHODS

Cumulative prenatal exposure to xenoestrogens was quantified in the placenta using the biomarker Total Effective Xenoestrogen Burden (TEXB-alpha) in 489 participants from the INMA (Childhood and the Environment) Project. TEXB-alpha was split in tertiles to test its association with the mental and psychomotor scores of the Bayley Scales of Infant Development (BSID) at 1-2 years of age, and with the McCarthy Scales of Children׳s Abilities (MSCA) general cognitive index and motor scale assessed at 4-5 years of age. Interactions with sex were investigated.

RESULTS

After adjustment for potential confounders, no association was observed between TEXB-alpha and mental scores at 1-2 years of age. We found a significant interactions with sex for the association between TEXB-alpha and infant psychomotor development (interaction p-value=0.029). Boys in the third tertile of exposure scored on average 5.2 points less than those in the first tertile on tests of motor development at 1-2 years of age (p-value=0.052), while no associations were observed in girls. However, this association disappeared in children at 4-5 years of age and no association between TEXB-alpha and children׳s cognition was found.

CONCLUSIONS

Our results suggest that boys' early motor development might be more vulnerable to prenatal exposure to mixtures of xenoestrogens, but associations do not persist in preschool children.

The UV filter benzophenone 3 (BP-3) activates hormonal genes mimicking the action of ecdysone and alters embryo development in the insect Chironomus riparius (Diptera)

Numerous studies have evaluated the endocrine effects of UV filters in vertebrates, but little attention has been paid to their possible hormonal activity in invertebrates. We examined the effects of benzophenone-3 (BP-3), one of the most common sunscreen agents, in Chironomus riparius (Insecta), a reference organism in aquatic toxicology. Salivary glands from larvae were treated with either the hormone ecdysone or BP-3 to compare the response of endocrine genes. It was found that BP-3 elicits the same effects as the natural hormone activating the expression of a set of ecdysone responsive genes. BP-3 also activated the stress gene hsp70. Interestingly, similar effects have been confirmed in vivo in embryos. Moreover, BP-3 also altered embryogenesis delaying hatching. This is the first demonstration of hormonal activity of UV filters in invertebrates, showing a mode of action similar to ecdysteroid hormones. This finding highlights the potential endocrine disruptive effects of these emergent pollutants.

Presence and bioavailability of bisphenol A in the uterus of rats and mice following single and repeated dietary administration at low doses

This research examined the distribution of low dietary doses of bisphenol A (BPA). When female rats received 50μg/kg (14)C-BPA orally, radioactivity was distributed throughout the body, with especial presence in the uterus. Pre-treatment with estradiol or the estrogen antagonist ICI 182,780 significantly reduced radioactivity in the uterus. The majority of BPA at the uterus was determined to be aglycone (receptor-active) via GC-MS. Subsequently, mice given 0.5, 5, or 50μg/kg (14)C-BPA showed more radioactivity in the uterus than in other non-metabolic tissues. When female mice received 1, 7, or 28 daily doses of 50μg/kg (14)C-BPA, then were measured 24h after the last dose, significantly more radioactivity was detected in the uterus, liver, and kidney following repeated doses. Collectively, these data provide evidence for the in vivo interaction of BPA with estrogen receptors. They also indicate elevated presence of BPA in reproductive tissues after repeated low doses.

Exposure assessment of endocrine disruptors in bottled drinking water of Lebanon

Bisphenol A (BPA) is a commonly used monomer in various products including bottled water. Numerous studies have reported endocrine adverse effects and neoplasia associated with BPA exposure in animals. However, considerable discrepancies exist among these studies with respect to both the nature of the toxic effects and the threshold dose. In Lebanon, 19-L polycarbonate (PC) bottles of drinking water are widely used in urban areas. The present study aims at assessing BPA human exposure and associated health risks from drinking water in Lebanese. A total of 22 bottled water sources, packaged in PC, were identified from licensed and non-licensed sources. Water samples were analyzed following exposure to sunlight for 72 h. BPA in water was quantified by HPLC, and other potential organic pollutants were screened by GC/MS. Fifty-nine percent of samples showed BPA levels above detection limits (>0.05 ng/mL). The median BPA level was 0.1 ng/mL (range 0.05 to 1.37 ng/mL). The mean BPA level for the total number of samples was 0.169 ng/mL (±0.280). A higher mean BPA level was found in water from licensed companies compared to non-licensed sources, however, not statistically significant. Screening showed the presence of dibutyl-phthalate and dioctyl-phthalate in only two samples. Endocrine disruptors (EDR) are ubiquitous contaminants in bottled water in Lebanon with potential health risk implications. Although estimated exposure levels are below the reference dose (RfD), further studies are needed to quantitate exposure from various sources and to investigate EDR contribution to existing epidemics in the country.

Impact of bisphenol a on the cardiovascular system - epidemiological and experimental evidence and molecular mechanisms

Bisphenol A (BPA) is a ubiquitous plasticizing agent used in the manufacturing of polycarbonate plastics and epoxy resins. There is well-documented and broad human exposure to BPA. The potential risk that BPA poses to the human health has attracted much attention from regulatory agencies and the general public, and has been extensively studied. An emerging and rapidly growing area in the study of BPA's toxicity is its impact on the cardiovascular (CV) system. Recent epidemiological studies have shown that higher urinary BPA concentration in humans is associated with various types of CV diseases, including angina, hypertension, heart attack and coronary and peripheral arterial disease. Experimental studies have demonstrated that acute BPA exposure promotes the development of arrhythmias in female rodent hearts. Chronic exposure to BPA has been shown to result in cardiac remodeling, atherosclerosis, and altered blood pressure in rodents. The underlying mechanisms may involve alteration of cardiac Ca2+ handling, ion channel inhibition/activation, oxidative stress, and genome/transcriptome modifications. In this review, we discuss these recent findings that point to the potential CV toxicity of BPA, and highlight the knowledge gaps in this growing research area.

Bisphenol-A: epigenetic reprogramming and effects on reproduction and behavior

Bisphenol A (BPA) is a synthetic compound used in the production of many polycarbonate plastics and epoxy resins. It is one of the most widely produced chemicals in the world today and is found in most canned goods, plastics, and even household dust. Exposure to BPA is almost universal: most people have measurable amounts of BPA in both urine and serum. BPA is similar in structure to estradiol and can bind to multiple targets both inside and outside the nucleus, in effect acting as an endocrine disruptor. Research on BPA exposure has accelerated in the past decade with findings suggesting that perinatal exposure to BPA can negatively impact both male and female reproduction, create alterations in behavior, and act as a carcinogen. BPA can have both short term and long term effects with the latter typically occurring through epigenetic mechanisms such as DNA methylation. This review will draw on both human and animal studies in an attempt to synthesize the literature and examine the effects of BPA exposure on reproduction, behavior, and carcinogenesis with a focus on the potential epigenetic mechanisms by which it acts.

Association of urinary concentrations of bisphenol A and phthalate metabolites with risk of type 2 diabetes: a prospective investigation in the Nurses' Health Study (NHS) and NHSII cohorts

BACKGROUND

Prospective evidence regarding associations for exposures to bisphenol A (BPA) and phthalates with type 2 diabetes (T2D) is lacking.

OBJECTIVE

We prospectively examined urinary concentrations of BPA and phthalate metabolites with T2D risk.

METHODS

We measured BPA and eight major phthalate metabolites among 971 incident T2D case-control pairs from the Nurses' Health Study (NHS) (mean age, 65.6 years) and NHSII (mean age, 45.6 years).

RESULTS

In the NHSII, BPA levels were not associated with incident T2D in multivariate-adjusted analysis until body mass index was adjusted: odds ratio (OR) comparing extreme BPA quartiles increased from 1.40 (95% CI: 0.91, 2.15) to 2.08 (95% CI: 1.17, 3.69; p(trend) = 0.02) with such an adjustment. In contrast, BPA concentrations were not associated with T2D in the NHS (OR = 0.81; 95% CI: 0.48, 1.38; p(trend) = 0.45). Likewise, urinary concentrations of total phthalate metabolites were associated with T2D in the NHSII (OR comparing extreme quartiles = 2.14; 95% CI: 1.19, 3.85; p(trend) = 0.02), but not in the NHS (OR = 0.87; 95% CI: 0.49, 1.53; p(trend) = 0.29). Summed metabolites of butyl phthalates or di-(2-ethylhexyl) phthalates were significantly associated with T2D only in the NHSII; ORs comparing extreme quartiles were 3.16 (95% CI: 1.68, 5.95; p(trend) = 0.0002) and 1.91 (95% CI: 1.04, 3.49; p(trend) = 0.20), respectively.

CONCLUSIONS

These results suggest that BPA and phthalate exposures may be associated with the risk of T2D among middle-aged, but not older, women. The divergent findings between the two cohorts might be explained by menopausal status or simply by chance. Clearly, these results need to be interpreted with caution and should be replicated in future studies, ideally with multiple urine samples collected prospectively to improve the measurement of these exposures with short half-lives.

A round robin approach to the analysis of bisphenol A (BPA) in human blood samples

BACKGROUND

Human exposure to bisphenol A (BPA) is ubiquitous, yet there are concerns about whether BPA can be measured in human blood. This Round Robin was designed to address this concern through three goals: 1) to identify collection materials, reagents and detection apparatuses that do not contribute BPA to serum; 2) to identify sensitive and precise methods to accurately measure unconjugated BPA (uBPA) and BPA-glucuronide (BPA-G), a metabolite, in serum; and 3) to evaluate whether inadvertent hydrolysis of BPA-G occurs during sample handling and processing.

METHODS

Four laboratories participated in this Round Robin. Laboratories screened materials to identify BPA contamination in collection and analysis materials. Serum was spiked with concentrations of uBPA and/or BPA-G ranging from 0.09-19.5 (uBPA) and 0.5-32 (BPA-G) ng/mL. Additional samples were preserved unspiked as 'environmental' samples. Blinded samples were provided to laboratories that used LC/MSMS to simultaneously quantify uBPA and BPA-G. To determine whether inadvertent hydrolysis of BPA metabolites occurred, samples spiked with only BPA-G were analyzed for the presence of uBPA. Finally, three laboratories compared direct and indirect methods of quantifying BPA-G.

RESULTS

We identified collection materials and reagents that did not introduce BPA contamination. In the blinded spiked sample analysis, all laboratories were able to distinguish low from high values of uBPA and BPA-G, for the whole spiked sample range and for those samples spiked with the three lowest concentrations (0.5-3.1 ng/ml). By completion of the Round Robin, three laboratories had verified methods for the analysis of uBPA and two verified for the analysis of BPA-G (verification determined by: 4 of 5 samples within 20% of spiked concentrations). In the analysis of BPA-G only spiked samples, all laboratories reported BPA-G was the majority of BPA detected (92.2 - 100%). Finally, laboratories were more likely to be verified using direct methods than indirect ones using enzymatic hydrolysis.

CONCLUSIONS

Sensitive and accurate methods for the direct quantification of uBPA and BPA-G were developed in multiple laboratories and can be used for the analysis of human serum samples. BPA contamination can be controlled during sample collection and inadvertent hydrolysis of BPA conjugates can be avoided during sample handling.

Molecular cloning and expression of the gene for G protein alpha subunit induced by bisphenol A in marine polychaete Perinereis aibuhitensis

A G protein alpha subunit gene named Pa Gα was isolated from the marine polychaete Perinereis aibuhitensis. The full-length cDNA of Pa Gα was 1832 bp and contained a 205 bp 5' untranslated region (5'UTR), a 565 bp 3' UTR and a 1062 bp open reading frame encoding 353 amino acid residues. The deduced protein sequence of Pa Gα showed 73% homology with the Gα protein of Dipolydora quadrilobata. Tissue-specific expression induced by exposure to bisphenol A (BPA) in P. aibuhitensis was detected by real-time PCR, which showed BPA induced expression of the Pa Gα gene, and the level of transcription was related positively to the concentration of BPA and the length of exposure time. With increasing concentration of BPA and length of exposure time, the level of mRNA transcription was raised gradually, but the level of increasing expression of Pa Gα mRNA induced by exposure to BPA varied significantly among different tissues.

Investigation of serum bisphenol A, vitamin D, and parathyroid hormone levels in patients with obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a common health problem, and associated with obesity, metabolic syndrome (MetS), and diabetes. Growing evidence shows that 25-hydroxyvitamin-D3 (25-OH-D) insufficiency and high parathyroid hormone (PTH) levels may be correlated to glucose intolerance, MetS, obesity, and cardiovascular abnormalities similar to OSAS. Bisphenol A (BPA) is an endocrine disruptor agent which exerts a wide variety of metabolic effects. It has estrogenic activity and its exposure may contribute to weight gain, obesity, impaired glucose metabolism, and the development of diabetes, also similar to OSAS. The aim of this study is to investigate the relationships between OSAS and serum BPA, 25-OH-D, and PTH levels. This study enrolled 128 subjects, with all of the OSAS patients having been diagnosed by polysomnography. The 128 subjects were divided into three groups: a control (n = 43), a moderate OSAS (n = 23) (AHI = 15-30), and a severe OSAS groups (n = 62) (AHI > 30). The serum BPA, 25-OH-D, and PTH levels for each subject were analyzed. 25-OH-D was lower in both OSAS groups, and PTH was higher in the OSAS groups than in the control subjects. The BPA levels were higher in the severe OSAS group than the moderate OSAS and control. There was a positive correlation between the BPA and body mass index, and a negative correlation between the 25-OH-D and BPA levels in all of the individuals. OSAS is related to high BPA and PTH levels, and low vitamin D levels. There is a positive association between BPA levels and OSAS, and the severity of OSAS. These results suggest that the BPA levels may have a role in the pathogenesis of OSAS.

Urinary bisphenol A, phthalates, and couple fecundity: the Longitudinal Investigation of Fertility and the Environment (LIFE) Study

OBJECTIVE

To assess the relationship between environmental chemicals and couple fecundity or time to pregnancy (TTP).

DESIGN

Prospective cohort.

SETTING

Communities of targeted populations with reported exposure.

PATIENT(S)

501 couples recruited upon discontinuing contraception to become pregnant, 2005-2009.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Fecundability odds ratios (FORs) and 95% confidence intervals (CIs) estimated for each partner's chemical concentrations adjusted for age, body mass index, cotinine, creatinine, and research site while accounting for time off contraception.

RESULT(S)

Couples completed interviews and anthropometric assessments and provided the urine specimens for quantification of bisphenol A (BPA) and 14 phthalate metabolites, which were measured using high-performance liquid chromatography with electrospray triple-quadrupole mass spectrometer. Women recorded menstruation and pregnancy test results in daily journals. Couples were evaluated until a positive human-chorionic gonadotropin pregnancy test or 12 cycles without pregnancy. Neither female nor male BPA concentration was associated with TTP (FOR 0.98; 95% CI, 0.86, 1.13 and FOR 1.04; 95% CI, 0.91, 1.18, respectively). Men's urinary concentrations of monomethyl, mono-n-butyl, and monobenzyl phthalates were associated with a longer TTP (FOR 0.80; 95% CI, 0.70, 0.93; FOR 0.82, 95% CI, 0.70, 0.97; and FOR 0.77, 95% CI, 0.65 0.92, respectively).

CONCLUSION(S)

Select male but not female phthalate exposures were associated with an approximately 20% reduction in fecundity, underscoring the importance of assessing both partners' exposure to minimize erroneous conclusions.

Influence of bottle-feeding on serum bisphenol a levels in infants

Exposure to endocrine disrupting chemicals (EDCs), particularly during developmental periods, gives rise to a variety of adverse health outcomes. Bisphenol A (BPA) is a well-known EDC commonly found in plastic products including food and water containers, baby bottles, and metal can linings. This study investigates infant exposure to BPA and the effect of bottle-feeding on serum BPA levels in infants. Serum BPA levels in normal healthy infants 6 to 15 months of age (n=60) were evaluated by a competitive ELISA. BPA was detected in every study sample. Serum BPA levels of bottle-fed infants (n=30) were significantly higher than those of breast-fed infants (n=30) (96.58±102.36 vs 45.53±34.05 pg/mL, P=0.014). There were no significant differences in serum BPA levels between boys (n=31) and girls (n=29). No significant correlations were found between serum BPA levels and age, body weight, birth weight, and gestational age. Bottle-feeding seems to increase the risk of infant exposure to BPA. Establishment of health policies to reduce or prevent BPA exposure in infants is necessary.

Estrogenic endocrine-disrupting chemicals: molecular mechanisms of actions on putative human diseases

Endocrine-disrupting chemicals (EDC), including phthalates, bisphenol A (BPA), phytoestrogens such as genistein and daidzein, dichlorodiphenyltrichloroethane (DDT), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), are associated with a variety of adverse health effects in organisms or progeny by altering the endocrine system. Environmental estrogens, including BPA, phthalates, and phytoestrogens, are the most extensively studied and are considered to mimic the actions of endogenous estrogen, 17β-estradiol (E2). Diverse modes of action of estrogen and estrogen receptors (ERα and ERβ) have been described, but the mode of action of estrogenic EDC is postulated to be more complex and needs to be more clearly elucidated. This review examines the adverse effects of estrogenic EDC on male or female reproductive systems and molecular mechanisms underlying EDC effects that modulate ER-mediated signaling. Mechanisms of action for estrogenic EDC may involve both ER-dependent and ER-independent pathways. Recent findings from systems toxicology of examining estrogenic EDC are also discussed.

GC-MS determination of bisphenol A and alkylphenol ethoxylates in river water from India and their ecotoxicological risk assessment

Water samples from three rivers in southern India were analyzed for octylphenol (OP), nonylphenol (NP), and bisphenol A (BPA) residues by gas chromatography and mass spectrometry. The concentrations of OP, NP and BPA ranged from ND (not detected) to 16.3 ng/L, ND to 2200 ng/L, and 2.8 to 136 ng/L with detection frequencies of 96%, 66% and 100%, respectively. All three rivers showed a similar distribution pattern of NP>>BPA>OP, however, the Kaveri river had elevated levels. The phenolic compounds in rivers are expected to cause potential toxicity to aquatic organism including crustaceans, molluscs, insects and fish. In respect to aquatic risk assessment, NP showed a greater hazard quotient (HQ) than did OP and BPA, and the highest HQ (62) was observed for fish in the Kaveri river. The backwater and estuarine NP levels may pose a risk to larvae of oysters and barnacles. Based on tolerable daily intake and reference dose, BPA and NP levels are considered safe for humans. However, NP levels in some water samples were greater than the drinking water safety limit (0.5 µg/L). This is the first report on phenolic compounds and their associated aquatic risks in Indian rivers.

Multi-well plate immunoassays for measuring signaling protein activations/deactivations and membrane vs. intracellular receptor levels

We developed fixed-cell multi-well plate immunoassays that increase the throughput and ease of quantification for questions formerly assessed by immunoblot scanning. The assays make use of the now abundant antibodies designed to recognize receptor subtypes and posttranslationally modified signaling proteins. By optimizing permeabilization and fixation conditions, mainly based on specific cell types, the assay can be adapted to the study of many different antigens of importance to hormonal and neurotransmitter signaling scenarios.

p,p'-DDE activates CatSper and compromises human sperm function at environmentally relevant concentrations

STUDY QUESTION

Is the environmental endocrine disruptor p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE) able to induce non-genomic changes in human sperm and consequently affect functional sperm parameters?

SUMMARY ANSWER

p,p′-DDE promoted Ca²⁺ flux into human sperm by activating CatSper channels even at doses found in human reproductive fluids, ultimately compromising sperm parameters important for fertilization.

WHAT IS KNOWN ALREADY

p,p′-DDE may promote non-genomic actions and interact directly with pre-existing signaling pathways, as already observed in other cell types. However, although often found in both male and female reproductive fluids, its effects on human spermatozoa function are not known.

STUDY DESIGN, SIZE, DURATION

Normozoospermic sperm samples from healthy individuals were included in this study. Samples were exposed to several p,p′-DDE concentrations for 3 days at 37°C and 5% CO₂in vitro to mimic the putative continuous exposure to this toxicant in the female reproductive tract in vivo. Shorter p,p′-DDE incubation periods were also performed in order to monitor sperm rapid Ca²⁺ responses. All experiments were repeated on a minimum of five sperm samples from different individuals.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All healthy individuals were recruited at the Biosciences School, University of Birmingham, the Medical Research Institute, University of Dundee and in the Human Reproduction Service at University Hospitals of Coimbra. Intracellular Ca²⁺ concentration ([Ca²⁺]_i) was monitored by imaging single spermatozoa loaded with Oregon Green BAPTA-1AM and further whole-cell patch-clamp recordings were performed to validate our results. Sperm viability and acrosomal integrity were assessed using the LIVE/DEAD sperm vitality kit and the acrosomal content marker PSA-FITC, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

p,p′-DDE rapidly increased [Ca²⁺]_i (P < 0.05) even at extremely low doses (1 pM and 1 nM), with magnitudes of response up to 200%, without affecting sperm viability, except after 3 days of continuous exposure to the highest concentration tested (P < 0.05). Furthermore, experiments performed in a low Ca²⁺ medium demonstrated that extracellular Ca²⁺ influx was responsible for this Ca²⁺ increase (P < 0.01). Mibefradil and NNC 55-0396, both inhibitors of the sperm-specific CatSper channel, reversed the p,p′-DDE-induced [Ca²⁺]_i rise, suggesting the participation of CatSper in this process (P < 0.05). In fact, whole-cell patch-clamp recordings confirmed CatSper as a target of p,p′-DDE action by monitoring an increase in CatSper currents of >100% (P < 0.01). Finally, acrosomal integrity was adversely affected after 2 days of exposure to p,p′-DDE concentrations, suggesting that [Ca²⁺]_i rise may cause premature acrosome reaction (P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

This is an in vitro study, and caution must be taken when extrapolating the results.

WIDER IMPLICATIONS OF THE FINDINGS

A novel non-genomic p,p′-DDE mechanism specific to sperm is shown in this study. p,p′-DDE was able to induce [Ca²⁺]_i rise in human sperm through the opening of CatSper consequently compromising male fertility. The promiscuous nature of CatSper activation may predispose human sperm to the action of some persistent endocrine disruptors.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by both the Portuguese National Science Foundation (FCT; PEst-C/SAU/LA0001/2011) and the UK Wellcome Trust (Grant #86470). SM was supported by the Infertility Research Trust. RST is a recipient of a PhD fellowship from FCT (SFRH/BD/46002/2008). None of the authors has any conflict of interest to declare.

Waterborne exposure of zebrafish embryos to micromole concentrations of ioxynil and diethylstilbestrol disrupts thyrocyte development

The herbicide ioxynil (IOX) and synthetic estrogen diethylstilbestrol (DES) are common aquatic contaminants with an endocrine disrupting action. In juvenile teleost fish IOX and DES disrupt the hypothalamic-pituitary-thyroid (HPT) axis. To assess how IOX and DES influence the developing HPT axis prior to establishment of central regulation of thyroid hormones, zebrafish embryos were exposed to low concentrations of the chemicals in water. IOX and DES (1 and 0.1 μM) exposure failed to modify hypothalamic development but had a negative effect on thyrocyte development. Specifically, IOX and DES caused a significant (p<0.05) reduction in the size of the thyroid anlagen by decreasing the mRNA expression field of both nk2.1a and thyroglobulin (Tg) genes. Inhibition of thyroid gland development by IOX and DES (0.1 μM) was strongly associated with altered heart morphology. To test if the effect of IOX and DES on the thyroid was a consequence of altered cardiac development a morpholino (MO) against zebrafish cardiac troponin I (zcTnI) was microinjected. The zcTnI morphants had modified heart function, a small thyroid anlagen and a reduction in the mRNA expression of nk2.1a and Tg genes similar to that of zebrafish exposed to IOX (1 and 0.1 μM) and DES (0.1 μM). Collectively the data indicate that IOX and DES alter thyroid development in zebrafish and chemicals that alter heart development and function can have an indirect endocrine disrupting action on the thyroid in teleosts.

Bisphenol A inhibits cultured mouse ovarian follicle growth partially via the aryl hydrocarbon receptor signaling pathway

Bisphenol A (BPA) is an endocrine disruptor that inhibits growth of mouse ovarian follicles and disrupts steroidogenesis at a dose of 438μM. However, the effects of lower doses of BPA and its mechanism of action in ovarian follicles are unknown. We hypothesized that low doses of BPA inhibit follicular growth and decrease estradiol levels through the aryl hydrocarbon receptor (AHR) pathway. Antral follicles from wild-type and Ahr knock-out (AhrKO) mice were cultured for 96h. Follicle diameters and estradiol levels then were compared in wild-type and AhrKO follicles ± BPA (0.004-438μM). BPA inhibited follicle growth (110-438μM) and decreased estradiol levels (43.8-438μM) in wild-type and AhrKO follicles. However, at BPA 110μM, inhibition of growth in AhrKO follicles was attenuated compared to wild-type follicles. These data suggest that BPA may inhibit follicle growth partially via the AHR pathway, whereas its effects on estradiol synthesis likely involve other mechanisms.

Gender-specific transcriptomic response to environmental exposure in Flemish adults

Flanders, Belgium, is one of the most densely populated areas in Europe. The Flemish Environment and Health Survey (2002-2006) aimed at determining exposure to pollutants of neonates, adolescents, and older adults and to assess associated biological and health effects. This study investigated genome wide gene expression changes associated with a range of environmental pollutants, including cadmium, lead, PCBs, dioxin, hexachlorobenzene, p,p'-DDE, benzene, and PAHs. Gene expression levels were measured in peripheral blood cells of 20 adults with relatively high and 20 adults with relatively low combined internal exposure levels, all non-smokers aged 50-65. Pearson correlation was used to analyze associations between pollutants and gene expression levels, separately for both genders. Pollutant- and gender-specific correlation analysis results were obtained. For organochlorine pollutants, analysis within genders revealed that genes were predominantly regulated in opposite directions in males and females. Significantly modulated pathways were found to be associated with each of the exposure biomarkers measured. Pathways and/or genes related to estrogen and STAT5 signaling were correlated to organochlorine exposures in both genders. Our work demonstrates that gene expression in peripheral blood is influenced by environmental pollutants. In particular, gender-specific changes are associated with organochlorine pollutants, including gender-specific modulation of endocrine related pathways and genes. These pathways and genes have previously been linked to endocrine disruption related disorders, which in turn have been associated with organochlorine exposure. Based on our results, we recommend that males and females be considered separately when analyzing gene expression changes associated with exposures that may include chemicals with endocrine disrupting properties.

Hyperprolactinemia is not associated with hyperestrogenism in noncycling African elephants (Loxodonta africana)

African elephants in US zoos are not reproducing at replacement levels. This is in part due to physiological problems, one of which is abnormal ovarian cyclicity that has been linked to increased prolactin secretion (hyperprolactinemia). A relationship between increased estrogen production (hyperestrogenism) and hyperprolactinemia has been found in other species. Therefore, the objective of this study was to determine if elevated prolactin was associated with increased estrogen concentrations in non-cycling African elephants. In cycling elephants (n=12), prolactin secretion followed a normal cyclic pattern, with higher concentrations observed during the follicular phase; overall mean concentration was ∼18ng/ml and baseline prolactin was ∼6ng/ml. Non-cycling females (n=18) were categorized into three groups: (1) low prolactin (<15ng/ml; n=3); (2) moderate hyperprolactinemia (16-30ng/ml; n=7); and marked hyperprolactinemia (>31ng/ml; n=8). Mean urinary estrogen conjugate concentrations ranged from 5.4 to 41.4ng/mg Crt, and were similar between normal cycling (15.4±1.5ng/mg Crt) and non-cycling, low prolactin elephants (18.4±7.3ng/mg Crt), but were lower in moderate (9.4±1.3ng/mg Crt) and marked hyperprolactinemic (9.8±1.1ng/mg Crt) groups (P<0.05). In conclusion, African elephants appear to be sensitive to alterations in prolactin production, with both low (e.g., a non-cycling pattern) and high prolactin secretion being associated with abnormal ovarian activity. However, hyperestrogenism was not related to hyperprolactinemia in the non-cycling females.

A systematic review of Bisphenol A "low dose" studies in the context of human exposure: a case for establishing standards for reporting "low-dose" effects of chemicals

Human exposure to the chemical Bisphenol A is almost ubiquitous in surveyed industrialized societies. Structural features similar to estrogen confer the ability of Bisphenol A (BPA) to bind estrogen receptors, giving BPA membership in the group of environmental pollutants called endocrine disruptors. References by scientists, the media, political entities, and non-governmental organizations to many toxicity studies as "low dose" has led to the belief that exposure levels in these studies are similar to humans, implying that BPA is toxic to humans at current exposures. Through systematic, objective comparison of our current, and a previous compilation of the "low-dose" literature to multiple estimates of human external and internal exposure levels, we found that the "low-dose" moniker describes exposures covering 8-12 orders of magnitude, the majority (91-99% of exposures) being greater than the upper bound of human exposure in the general infant, child and adult U.S. Population. "low dose" is therefore a descriptor without specific meaning regarding human exposure. Where human exposure data are available, for BPA and other environmental chemicals, reference to toxicity study exposures by direct comparison to human exposure would be more informative, more objective, and less susceptible to misunderstanding.

Effects of low doses of bisphenol A on the metabolome of perinatally exposed CD-1 mice

BACKGROUND

Bisphenol A (BPA) is a well-known endocrine disruptor used to manufacture polycarbonate plastics and epoxy resins. Exposure of pregnant rodents to low doses of BPA results in pleiotropic effects in their offspring.

OBJECTIVE

We used metabolomics--a method for determining metabolic changes in response to nutritional, pharmacological, or toxic stimuli--to examine metabolic shifts induced in vivo by perinatal exposure to low doses of BPA in CD-1 mice.

METHODS

Male offspring born to pregnant CD-1 mice that were exposed to vehicle or to 0.025, 0.25, or 25 µg BPA/kg body weight/day, from gestation day 8 through day 16 of lactation, were examined on postnatal day (PND) 2 or PND21. Aqueous extracts of newborns (PND2, whole animal) and of livers, brains, and serum samples from PND21 pups were submitted to (1)H nuclear magnetic resonance spectroscopy. Data were analyzed using partial least squares discriminant analysis.

RESULTS

Examination of endogenous metabolic fingerprints revealed remarkable discrimination in whole extracts of the four PND2 newborn treatment groups, strongly suggesting changes in the global metabolism. Furthermore, statistical analyses of liver, serum, and brain samples collected on PND21 successfully discriminated among treatment groups. Variations in glucose, pyruvate, some amino acids, and neurotransmitters (γ-aminobutyric acid and glutamate) were identified.

CONCLUSIONS

Low doses of BPA disrupt global metabolism, including energy metabolism and brain function, in perinatally exposed CD-1 mouse pups. Metabolomics can be used to highlight the effects of low doses of endocrine disruptors by linking perinatal exposure to changes in global metabolism.

Mixtures of xenoestrogens disrupt estradiol-induced non-genomic signaling and downstream functions in pituitary cells

BACKGROUND

Our study examines the effects of xenoestrogen mixtures on estradiol-induced non-genomic signaling and associated functional responses. Bisphenol-A, used to manufacture plastic consumer products, and nonylphenol, a surfactant, are estrogenic by a variety of assays, including altering many intracellular signaling pathways; bisphenol-S is now used as a bisphenol-A substitute. All three compounds contaminate the environment globally. We previously showed that bisphenol-S, bisphenol-A, and nonylphenol alone rapidly activated several kinases at very low concentrations in the GH3/B6/F10 rat pituitary cell line.

METHODS

For each assay we compared the response of individual xenoestrogens at environmentally relevant concentrations (10-15 -10-7 M), to their mixture effects on 10-9 M estradiol-induced responses. We used a medium-throughput plate immunoassay to quantify phosphorylations of extracellular signal-regulated kinases (ERKs) and c-Jun-N-terminal kinases (JNKs). Cell numbers were assessed by crystal violet assay to compare the proliferative effects. Apoptosis was assessed by measuring caspase 8 and 9 activities via the release of the fluorescent product 7-amino-4-trifluoromethylcoumarin. Prolactin release was measured by radio-immunoassay after a 1 min exposure to all individual and combinations of estrogens.

RESULTS

Individual xenoestrogens elicited phospho-activation of ERK in a non-monotonic dose- (fM-nM) and mostly oscillating time-dependent (2.5-60 min) manner. When multiple xenoestrogens were combined with nM estradiol, the physiologic estrogen's response was attenuated. Individual bisphenol compounds did not activate JNK, while nonylphenol did; however, the combination of two or three xenoestrogens with estradiol generated an enhanced non-monotonic JNK dose-response. Estradiol and all xenoestrogen compounds induced cell proliferation individually, while the mixtures of these compounds with estradiol suppressed proliferation below that of the vehicle control, suggesting a possible apoptotic response. Extrinsic caspase 8 activity was suppressed by estradiol, elevated by bisphenol S, and unaffected by mixtures. Intrinsic caspase 9 activity was inhibited by estradiol, and by xenoestrogen combinations (at 10-14 and 10-8 M). Mixtures of xenoestrogens impeded the estradiol-induced release of prolactin.

CONCLUSIONS

In mixtures expected to be found in contaminated environments, xenoestrogens can have dramatic disrupting effects on hormonal mechanisms of cell regulation and their downstream functional responses, altering cellular responses to physiologic estrogens.

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.

Bisphenol A stimulates human prostate cancer cell migration via remodelling of calcium signalling

Bisphenol A (BPA), the principal constituent of reusable water bottles, metal cans, and plastic food containers, has been shown to be involved in human prostate cancer (PCa) cell proliferation. The aim of the present study was to explore the effect of BPA on PCa cell migration and the pathways involved in these processes. Using the transwell technique, we clearly show for the first time that the pre-treatment of the cells with BPA (1–10 nM) induces human PCa cell migration. Using a calcium imaging technique, we show that BPA pre-treatment induces an amplification of Store-Operated Calcium Entry (SOCE) in LNCaP cells. RT-PCR and Western blot experiments allowed the identification of the ion channel proteins which are up-regulated by BPA pre-treatments. These include the Orai1 protein, which is known as an important SOCE actor in various cell systems, including human PCa cells. Using a siRNA strategy, we observed that BPA-induced amplification of SOCE was Orai1-dependent. Interestingly, the BPA-induced PCa cell migration was suppressed when the calcium entry was impaired by the use of SOCE inhibitors (SKF96365, BTP2), or when the extracellular calcium was chelated. Taken together, the results presented here show that BPA induces PCa cells migration via a modulation of the ion channel protein expression involved in calcium entry and in cancer cell migration. The present data provide novel insights into the molecular mechanisms involved in the effects of an environmental factor on cancer cells and suggest both the necessity of preventive measures and the possibility of targeting ion channels in the treatment of PCa cell metastasis.

The male mammary gland: a target for the xenoestrogen bisphenol A

Males of some strains of mice retain their mammary epithelium even in the absence of nipples. Here, we have characterized the mammary gland in male CD-1 mice both in whole mounts and histological sections. We also examined the effects of bisphenol A (BPA), an estrogen mimic that alters development of the female mouse mammary gland. BPA was administered at a range of environmentally relevant doses (0.25-250μg/kg/day) to pregnant and lactating mice and then the mammary glands of male offspring were examined at several periods in adulthood. We observed age- and dose-specific effects on mammary gland morphology, indicating that perinatal BPA exposures alter the male mammary gland in adulthood. These results may provide insight into gynecomastia, the most common male breast disease in humans, where proliferation of the mammary epithelium leads to breast enlargement.

Is bisphenol-A exposure during pregnancy associated with blood glucose levels or diagnosis of gestational diabetes?

Recent epidemiological studies indicate bisphenol A (BPA), an estrogenic chemical used in production of epoxy, polycarbonate, and plastic may increase risk of insulin resistance and type 2 diabetes. Exposure to BPA during pregnancy may contribute to development of gestational diabetes mellitus (GDM), a precursor to type 2 diabetes in women. This pilot study examined the association between BPA exposure, fasting blood glucose levels (FBG), and GDM diagnosis during pregnancy. Banked urine samples from 22 cases of GDM and 72 controls were analyzed for total (free BPA + conjugates) urinary BPA concentrations (μg/L). FBG levels (mg/dl) were obtained from 1-h 50-g glucose tolerance tests (GTT) that women underwent for routine GDM screening (mean gestational age = 26.6 weeks, SD = 3.8). Those with an initial screening value ≥ 135 mg/dl underwent 3-h 100 g oral GTT. GDM diagnoses were made when the initial screening value was ≥ 200 mg/dl or when values at ≥ 2 time points exceeded 3-h oral GTT thresholds. Among controls, median FBG levels (mg/dL) did not differ across exposure tertiles, defined according to the distribution of total specific-gravity-adjusted urinary BPA concentrations. Logistic regression models controlling for race/ethnicity did not provide evidence of association between BPA exposure and case status across increasing tertiles of BPA exposure (number of GDM cases/controls in tertile1: 13/24; in tertile 2: 6/24; in tertile 3: 3/24). Findings do not support a relationship between total urinary BPA concentrations and altered glucose metabolism during pregnancy. However, due to study limitations, findings need to be interpreted with caution.

Serum bisphenol a concentration in postmenopausal women with osteoporosis

Objectives

Bishphenol A (BPA) is a representative endocrine disruptor and is also known as a xenoestrogen. The objective of the present study is to investigate how many patients are exposed to BPA and to analyze the relationships between serum BPA concentration, bone mineral density (BMD) and biochemical bone markers in postmenopausal women with osteoporosis.

Methods

Total 51 patients were enrolled for measuring BPA and clinical variables including BMD and bone markers. The relationship between BPA and clinical variables were analyzed by the Pearson's correlation test and the Kruskal-Wallis test. Serum BPA concentration was measured by enzyme linked immunosorbent assay (ELISA).

Results

BPA was detected in all samples. The mean BPA concentration was 1.44 ± 0.52 ng/mL. There was no statistically significant correlation between BPA and clinical variables.

Conclusion

There was no statistical significance between serum BPA concentration and clinical variables related to bone metabolism. To clarify the effect of BPA on bone metabolism, further large scaled and high risk group investigation may be needed.

Estrogen-like disruptive effects of dietary exposure to bisphenol A or 17α-ethinyl estradiol in CD1 mice

Bisphenol A (BPA) is an endocrine disrupting chemical that is ubiquitous in wild and built environments. Due to variability in study design, the disruptive effects of BPA have proven difficult to experimentally replicate. This study was designed to assess the disruptive actions of dietary BPA exposure, while carefully controlling for known confounders. Parental CD1 mice were acclimated to defined diet containing BPA (0.03, 0.3, 3, 30, or 300 ppm) or 17α-ethinyl estradiol (EE; 0.0001, 0.001, and 0.01 ppm) and bred to produce progeny (F1) that were maintained through adulthood on the same diet as the parents. In F1 females, uterine weights were increased in all EE and the 30-ppm BPA-exposure groups, demonstrating model sensitivity and estrogen-like actions of BPA. In BPA-exposed females, no treatment-related differences were observed in parental reproductive function, or in the timing of puberty and metabolic function in female offspring. In F1 males, modest changes in body weight, adiposity and glucose tolerance, consistent with improved metabolic function, were observed. Associated with increased prolactin and increased circulating testosterone levels, balanopreputial separation was accelerated by 0.03 and 3.0 ppm BPA and anogenital distance at postnatal day 21 was increased in males by 0.03 ppm BPA. Sperm counts were also increased with 3.0 ppm BPA exposures. Overall, BPA was found to have modest, sex specific endocrine disruptive effects on a variety of end points below the established no observed adverse effect level. The dose response characteristics for many of the effects were nonmonotonic and not predictable from high-dose extrapolations.