Xenoestrogens Research Articles

The effect of bisphenol A on testicular steroidogenesis and its amelioration by quercetin: an in vivo and in silico approach.

Bisphenol A (BPA), a phenyl ring containing synthetic xenoestrogen, is widely used in the manufacture of polycarbonate plastics, epoxy resins and as a non-polymer additive to other plastics. Food is considered as the main source of exposure to BPA as it leaches out from food containers as well as surface coatings. It causes toxicity in the liver, kidney, brain, and other organs by initiating the process of lipid peroxidation. The present investigation was an attempt to evaluate the effect of BPA on steroidogenesis and its amelioration by quercetin. Inbred Swiss strain male albino mice were orally administered with 80, 120 and 240 mg per kg body weight per day of BPA for 45 days. The results revealed that BPA causes significant (p < 0.05) and dose-dependent changes in the body weight and biochemical parameters like protein, cholesterol and lipid contents as well as activities of 3β-and 17β-hydroxysteroid dehydrogenases in the testis of mice. It was also found to significantly reduce the testosterone level in serum. Oral administration of quercetin (30, 60 and 90 mg per kg body weight per day) along with a high dose of BPA (240 mg per kg body weight per day) for 45 days caused significant amelioration in the body weight and steroidogenesis as compared to the BPA alone treated group. The effect was dose-dependent. This amelioration in BPA-induced toxicity might be due to the antioxidative properties of quercetin. The reduction in the function of enzymes was confirmed by in silico bindings. BPA and quercetin show competitive binding with steroidogenic enzymes as well as binding with each other. This could be a possible mechanism to reduce the toxic effect of BPA which has been supported by molecular dynamics simulations for molecular level recognition with structural insights.

Diethylstilbestrol regulates mouse gubernaculum testis cell proliferation via PLC-Ca2+ -CREB pathway.

Environmental estrogens remain a serious threat to male reproductive health, and it is important to understand the mechanism by which EEs affect the male productive system. Here we explore potential mechanisms how the proliferation and contractility of gubernaculum testis cells are regulated by diethylstilbestrol. Our findings provide the first evidence that PLC-Ca2+ -CREB signalling pathway mediates the nongenomic effects of diethylstilbestrol on gubernaculum testis cells. These findings provide new insight into the role of diethylstilbestrol in the aetiology of male reproductive dysfunction and will help develop better approaches for the prevention and therapy of male reproductive malformation.

Natural and environmental oestrogens induce TGFB1 synthesis in oviduct cells.

Autocrine/paracrine factors generated in response to 17β-oestradiol (E2), within the oviduct, facilitate early embryo development for implantation. Since transforming growth factor beta 1 (TGFB1) plays a key role in embryo implantation, regulation of its synthesis by E2 may be of biological/pathophysiological relevance. Here, we investigated whether oviduct cells synthesize TGFB1 and whether E2 and environmental oestrogens (EOEs; xenoestrogens and phytoestrogens) modulate its synthesis. Under basal conditions, bovine oviduct cells (OCs; oviduct epithelial cells and oviduct fibroblasts; 1:1 ratio) synthesized TGFB1. E2 concentration-dependent induced TGFB1 levels in OCs and these effects were mimicked by some, but not all EOEs (genistein, biochanin A and 4-hydroxy-2',4',6'-trichlorobiphenyl, 4-hydroxy-2',4',6'-dichlorobiphenyl); moreover, EOEs enhanced (P < 0.05) the stimulatory effects of E2 on TGFB1 synthesis. The OCs expressed oestrogen receptors alpha and beta and aryl hydrocarbon; moreover, co-treatment with ER antagonist ICI182780 blocked the stimulatory effects of E2 and EOEs on TGFB1 synthesis. Treatment with non-permeable E2-BSA failed to induce TGFB1, thereby ruling out the involvement of membrane ERs. Cycloheximide (protein synthesis inhibitor) blocked E2-induced TGFB1 synthesis providing evidence for de novo synthesis. The stimulatory effects of E2 and EOEs, were inhibited (P < 0.05) by MAPK inhibitor (PD98059), whereas intracellular-Ca2+ chelator (BAPTA-AM) and adenylyl cyclase inhibitor (SQ22536) abrogated the effects of E2, but not EOEs, suggesting that post-ER effects of E2 and EOEs involve different pathways. Our results provide the first evidence that in OCs, E2 and EOEs stimulate TGFB1 synthesis via an ER-dependent pathway. Exposure of the oviduct to EOEs may result in continuous/sustained induction of TGFB1 levels in a non-cyclic fashion and may induce deleterious effects on reproduction.

Evaluating estrogenic and anti-estrogenic effect of endocrine disrupting chemicals (EDCs) by zebrafish (Danio rerio) embryo-based vitellogenin 1 (vtg1) mRNA expression

By measuring the vitellogenin 1 (vtg1) expression through quantitative PCR and in situ hybridization, we used the zebrafish embryo as an in vivo model to access the estrogenic or anti-estrogenic effects of several endocrine disrupting chemicals (EDCs), such as natural estrogen 17β-estradiol (E2), estriol (E3), synthetic hormones including diethylstilbestrol (DES), 4-octyl phenol (OP), bisphenol A (BPA), tamoxifen (TMX) and 3-(2,3-dibromopropyl) isocyanurate (TBC). According to our data, the estrogenic effect of the tested chemicals was ranked as: DES>E2>E3>OP>BPA, which is consistent with various in vivo and in vitro models. Therefore, the measurement of vtg1 gene expression in zebrafish embryos would be a valuable method for screening EDCs including both environmental estrogens and anti-estrogens.

UV photoconversion of environmental oestrogen diethylstilbestrol and its persistence in surface water under sunlight

As one of the most oestrogenic synthetic compounds in water environment, diethylstilbestrol (DES) has been studied for decades. Some studies showed that DES can be removed by ultraviolet (UV) irradiation. However, no one has paid attention to the formation of oestrogenic disinfection by-products (DBPs) and the persistence of DES in surface water remains a mystery. In this study, UV was found to be very effective in removing oestrogenic activity regardless of water quality. Three oestrogenic DBPs were specifically isolated by oestrogen receptor-based affinity chromatography and identified as 9,10-diethylphenanthrene-3,6-diol, cis-DES and Z,Z-dienestrol. Among them, 9,10-diethylphenanthrene-3,6-diol was proved to have stronger oestrogenic activity than E2, but it can be further photodegraded. In addition, DES was also demonstrated to be a photochromic compound, whose UV-induced intermediates can be transformed back to DES under sunlight, which significantly slows down the photodegradation of DES. This study solves the question as to why UV-degradable DES is still detectable in the ambient water and provides a deep understanding of DES removal during UV disinfection.

Disruption of the Reproductive Axis in Freshwater Fish, Catla catla, After Bisphenol-A Exposure

Environmental estrogens such as bisphenol-A (BPA) cause reproductive disorders in many vertebrate species, especially fish. BPA is used extensively in the manufacture of plastic and plastic products, epoxy resins, and dental sealants. The presence of BPA in sewage and surface water raises a potential threat to aquatic populations. In the present study, we investigated the effects of BPA on ovarian histology and transcription of key genes involved in reproduction. Adult female Catla catla were exposed to graded concentrations of BPA (10, 100, 1000 µg/l) for 14 days. Ovary histology and expression of steroidogenic acute regulatory protein (star), ovary aromatase (cyp19a), follicle-stimulating hormone receptor (fshr), and luteinizing hormone receptor (lhr) were evaluated in ovary of female fish after 14 days. Fish ovaries from the control and 10 µg/l BPA exposed groups included primary oocytes (POCs), while fish exposed to higher concentrations of BPA (100 and 1000 µg/l) contained tertiary and mature oocytes with increased numbers of atretic follicles. Significant increases in mRNA transcripts of star were observed in fish exposed to 100 and 1000 µg/l BPA. A 15-fold increase in the expression of ovary aromatase (cyp19a) was detected in fish exposed to 100 µg/l BPA. fshr increased in a dose-dependent manner. Increases in the expression of lhr, although not statistically significant, were observed in fish exposed to 100 and 1000 µg/l BPA when compared to control. The results of the present study indicate that BPA causes alterations in the expression patterns of genes involved in the reproductive pathway, which may lead to negative effects on the reproductive system in female fish.

Evaluation of long term low dose exposure to mixtures on the lymphocytes of the peripheral blood of rats

The environmental risks of environmental estrogens (EEs) are often assessed via the same mode of action in the concentration addition (CA) model, neglecting the complex combined mechanisms at the genetic level. In this study, the cell proliferation effects of estrone, 17α-ethinylestradiol, 17β-estradiol, estriol, diethylstilbestrol, estradiol valerate, bisphenol A, 4-tert-octylphenol and 4-nonylphenol were determined individually using the CCK-8 method, and the proliferation effects of a multicomponent mixture of estrogenic chemicals mixed at equipotent concentrations using a fixed-ratio design were studied using estrogen-sensitive MCF-7 cells. Furthermore, transcription factors related to cell proliferation were analyzed using RT-PCR assays to explore the potential molecular mechanisms related to the estrogenic proliferative effects. The results showed that the estrogenic chemicals act together in an additive mode, and the combined proliferative effects could be predicted more accurately by the response addition model than the CA model with regard to their adverse outcomes. Furthermore, different signaling pathways were involved depending on the different mixtures. The RT-PCR analyses showed that different estrogens have distinct avidities and preferences for different estrogen receptors at the gene level. Furthermore, the results indicated that estrogenic mixtures increased ERα, PIK3CA, GPER, and PTEN levels and reduced Akt1 level to display combined estrogenicity. These findings indicated that the potential combined environmental risks were greater than those found in some specific assessment procedures based on a similar mode of action due to the diversity of environmental pollutions and their multiple unknown modes of action. Thus, more efforts are needed for mode-of-action-driven analyses at the molecular level. Furthermore, to more accurately predict and assess the individual responses in vivo from the cellular effects in vitro, more parameters and correction factors should be taken into consideration in the addition model.

Emerging Estrogenic Pollutants in the Aquatic Environment and Breast Cancer.

The number and amount of man-made chemicals present in the aquatic environment has increased considerably over the past 50 years. Among these contaminants, endocrine-disrupting chemicals (EDCs) represent a significant proportion. This family of compounds interferes with normal hormonal processes through multiple molecular pathways. They represent a potential risk for human and wildlife as they are suspected to be involved in the development of diseases including, but not limited to, reprotoxicity, metabolic disorders, and cancers. More precisely, several studies have suggested that the increase of breast cancers in industrialized countries is linked to exposure to EDCs, particularly estrogen-like compounds. Estrogen receptors alpha (ERα) and beta (ERβ) are the two main transducers of estrogen action and therefore important targets for these estrogen-like endocrine disrupters. More than 70% of human breast cancers are ERα-positive and estrogen-dependent, and their development and growth are not only influenced by endogenous estrogens but also likely by environmental estrogen-like endocrine disrupters. It is, therefore, of major importance to characterize the potential estrogenic activity from contaminated surface water and identify the molecules responsible for the hormonal effects. This information will help us understand how environmental contaminants can potentially impact the development of breast cancer and allow us to fix a maximal limit to the concentration of estrogen-like compounds that should be found in the environment. The aim of this review is to provide an overview of emerging estrogen-like compounds in the environment, sum up studies demonstrating their direct or indirect interactions with ERs, and link their presence to the development of breast cancer. Finally, we emphasize the use of in vitro and in vivo methods based on the zebrafish model to identify and characterize environmental estrogens.

Toxic responses of Perna viridis hepatopancreas exposed to DDT, benzo(a)pyrene and their mixture uncovered by iTRAQ-based proteomics and NMR-based metabolomics

Dichlorodiphenyltrichloroethane (DDT) and benzo(a)pyrene (BaP) are environmental estrogens (EEs) that are ubiquitous in the marine environment. In the present study, we integrated isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic and nuclear magnetic resonance (NMR)-based metabolomic approaches to explore the toxic responses of green mussel hepatopancreas exposed to DDT (10μg/L), BaP (10μg/L) and their mixture. The metabolic responses indicated that BaP primarily disturbed energy metabolism and osmotic regulation in the hepatopancreas of the male green mussel P. viridis. Both DDT and the mixture of DDT and BaP perturbed the energy metabolism and osmotic regulation in P. viridis. The proteomic responses revealed that BaP affected the proteins involved in energy metabolism, material transformation, cytoskeleton, stress responses, reproduction and development in green mussels. DDT exposure could change the proteins involved in primary metabolism, stress responses, cytoskeleton and signal transduction. However, the mixture of DDT and BaP altered proteins associated with material and energy metabolism, stress responses, signal transduction, reproduction and development, cytoskeleton and apoptosis. This study showed that iTRAQ-based proteomic and NMR-based metabolomic approaches could effectively elucidate the essential molecular mechanism of disturbances in hepatopancreas function of green mussels exposed to environmental estrogens.

Effects of zearalenone, α-zearalenol, and genistein on boar sperm motility in vitro

Genistein (GEN) and zearalenone (ZEA), environmental oestrogens commonly present in feedstuff for pigs, are known for their effects on reproductive functions. The aim was to verify the in vitro effects of 0.5–20 µM concentrations of GEN, ZEA and its metabolite α-zearalenol (α-ZOL) on pig sperm motility. A dose-dependent increase of the immotile sperm amount against fast and medium-fast sperm clusters was observed with all three oestrogens from the lowest concentrations tested. Individual CASA (computer-assisted sperm analysis) parameters of motile sperms seemed to be less sensitive indicators. This should be considered especially in toxicological research on a sperm model. Background of inconsistencies in to date-published papers is discussed. The results shift the effective concentrations of ZEA, α-ZOL, and GEN to values achievable in vivo and raises the questions of risk assessment of these compounds in pig reproduction.

Genome reprogramming inSaccharomyces cerevisiaeupon nonylphenol exposure

Bioaccumulative environmental estrogen, nonylphenol (NP; 4-nonylphenol), is widely used as a nonionic surfactant and can affect human health. Since genomes of Saccharomyces cerevisiae and higher eukaryotes share many structural and functional similarities, we investigated subcellular effects of NP on S. cerevisiae BY4742 cells by analyzing genome-wide transcriptional profiles. We examined effects of low (1 mg/l; <15% cell number reduction) and high (5 mg/l; >65% cell number reduction) inhibitory concentration exposures for 120 or 180 min. After 120 and 180 min of 1 mg/l NP exposure, 187 (63 downregulated, 124 upregulated) and 103 genes (56 downregulated, 47 upregulated), respectively, were differentially expressed. Similarly, 678 (168 repressed, 510 induced) and 688 genes (215 repressed, 473 induced) were differentially expressed in cells exposed to 5 mg/l NP for 120 and 180 min, respectively. Only 15 downregulated and 63 upregulated genes were common between low and high NP inhibitory concentration exposure for 120 min, whereas 16 downregulated and 31 upregulated genes were common after the 180-min exposure. Several processes/pathways were prominently affected by either low or high inhibitory concentration exposure, while certain processes were affected by both inhibitory concentrations, including ion transport, response to chemicals, transmembrane transport, cellular amino acids, and carbohydrate metabolism. While minimal expression changes were observed with low inhibitory concentration exposure, 5 mg/l NP treatment induced substantial expression changes in genes involved in oxidative phosphorylation, cell wall biogenesis, ribosomal biogenesis, and RNA processing, and encoding heat shock proteins and ubiquitin-conjugating enzymes. Collectively, these results provide considerable information on effects of NP at the molecular level.

Estrogen and soy isoflavonoids decrease sensitivity of medulloblastoma and central nervous system primitive neuroectodermal tumor cells to chemotherapeutic cytotoxicity

BackgroundOur previous studies demonstrated that growth and migration of medulloblastoma (MB), the most common malignant brain tumor in children, are stimulated by 17β-estradiol. The growth stimulating effects of estrogens are mediated through ERβ and insulin-like growth factor 1 signaling to inhibit caspase 3 activity and reduce tumor cell apoptosis. The objective of this study was to determine whether estrogens decreased sensitivity of MB cells to cytotoxic actions of chemotherapeutic drugs.MethodsUsing in vitro cell viability and clonogenic survival assays, concentration response analysis was used to determine whether the cytoprotective effects of estradiol protected human D283 Med MB cells from the cytotoxic actions of the MB chemotherapeutic drugs cisplatin, vincristine, or lomustine. Additional experiments were done to determine whether the ER antagonist fulvestrant or the selective ER modulator tamoxifen blocked the cytoprotective actions of estradiol. ER-selective agonists and antagonists were used to define receptor specificity, and the impacts of the soy-derived phytoestrogens genistein, daidzein, and s-equol on chemosensitivity were evaluated.ResultsIn D283 Med cells the presence of 10 nM estradiol increased the IC50 for cisplatin-induced inhibition of viability 2-fold from ~5 μM to >10 μM. In clonogenic survival assays estradiol decreased the chemosensitivity of D283 Med cells exposed to cisplatin, lomustine and vincristine. The ERβ selective agonist DPN and low physiological concentrations of the soy-derived phytoestrogens genistein, daidzein, and s-equol also decreased sensitivity of D283 Med cells to cisplatin. The protective effects of estradiol were blocked by the antiestrogens 4-hydroxytamoxifen, fulvestrant (ICI 182,780) and the ERβ selective antagonist PPHTP. Whereas estradiol also decreased chemosensitivity of PFSK-1 cells, estradiol increased sensitivity of Daoy cell to cisplatin, suggesting that ERβ mediated effects may vary in different MB celltypes.ConclusionsThese findings demonstrate that E2 and environmental estrogens decrease sensitivity of MB to cytotoxic chemotherapeutics, and that ERβ selective and non-selective inhibition of estrogen receptor activity blocks these cytoprotective actions. These findings support the therapeutic potential of antiestrogen adjuvant therapies for MB, and findings that soy phytoestrogens also decrease sensitivity of MB cells to cytotoxic chemotherapeutics suggest that decreased exposure to environmental estrogens may benefit MB patient responses to chemotherapy.

Epigenetic and genetic landscape of uterine leiomyomas: a current view over a common gynecological disease.

Despite the numerous studies on the factors involved in the genesis and growth of uterine leiomyomas, the pathogenesis of these tumors remains unknown. Intrinsic abnormalities of the myometrium, abnormal myometrial receptors for estrogen, and hormonal changes or altered responses to ischemic damage during the menstrual period may be responsible for the initiation of (epi)genetic changes found in these tumors. Considering these elements, we aimed to offer an overview about epigenetic and genetic landscape of uterine leiomyomas. Narrative overview, synthesizing the findings of literature retrieved from searches of computerized databases. Several studies showed that leiomyomas have a monoclonal origin. Accumulating evidence converges on the risk factors and mechanisms of tumorigenesis: the translocation t (12;14) and deletion of 7q were found in the highest percentages of recurrence; dysregulation of the HMGA2 gene has been mapped within the critical 12q14-q15 locus. Estrogen and progesterone are recognized as promoters of tumor growth, and the potential role of environmental estrogens has been poorly explored. The growth factors with mitogenic activity, such as transforming growth factor-β3, fibroblast growth factor, epidermal growth factor, and insulin-like growth factor-I are elevated in fibroids and may have a role as effectors of the tumor promotion. The new clues on genetics and epigenetics, as well as about the growth factors that control normal and pathological myometrial cellular biology may be of great help for the development of new effective and less invasive therapeutic strategies in the near future.

Determination of Serum Methylparaben Concentrations of Bangladeshi Breast Cancer Patients by RP-HPLC

Breast cancer is one of the two major cancers of females. The mortality rate for breast cancer is significantly high in Bangladesh (about 15.4% among the female cancer patients). There are many possible reasons for breast cancer, among those, the environmental estrogen is considered as one of the potential factors. Parabens, which are widely used as antimicrobial preservatives in cosmetics, pharmaceuticals, food and beverage processing; has a tendency to act as environmental estrogens. In the present study we have estimated and compared the serum methylparaben concentration for control and breast cancer patients (stage III + IV). The serum concentration of methylparaben was determined by using reverse phase high performance liquid chromatography (RP-HPLC). The number of participants for this study was 45 and they were divided into two main groups named as the control group which consisted of 22 healthy females and the case group consisted of 23 breast cancer patients. The results of HPLC data demonstrated there is no existence of methylparaben in the control samples. There was only one sample from breast cancer patients, which had been found to contain traces of methylparaben. Though we are exposed to methylparaben extensively, very limited evidence has been found towards its relationship with breast cancer.

Biological effects of xenoestrogens and the functional mechanisms via genomic and nongenomic pathways

Xenoestrogens (XEs) are a class of substances that exert estrogenic effects by mimicking or blocking endogenous hormones. The sources, environmental behavior, and fate of typical XEs are described. XEs’ adverse developmental, metabolic, and immunological effects are then presented with respect to reproductive functions. The mechanisms underlying XEs’ genomic and nongenomic effects are reviewed. XEs can alter gene transcription by interfering with the functioning of conventional estrogen receptors, but they are also capable of activating multiple kinase signaling pathways that disrupt membrane-associated receptors, such as estrogen receptor alpha-36 (ERα36), estrogen receptor alpha-46 (ERα46), and G protein-coupled receptor 30 (GPR30). This review aims to provide insight into XEs’ environmental effects and to explore the prevention and treatment of their estrogenic effects based on sufficient comprehension of the mechanisms involved.

Estrogenic chemicals at body burden levels attenuate energy metabolism in 3T3-L1 adipocytes.

The study aimed to examine effects of environmental estrogens at body burden levels on energy metabolism in fat cells. Acclimation of T47D-KBluc cells in estrogen-deprived medium was established for high performance of estrogen-responsive luciferase reporter assay. With the assay, relative estrogenic potency of four selected estrogen receptor (ER) agonists, i.e. diethylstilbestrol, β-estradiol, 4-nonylphenol and bisphenol A, were determined. Immunoblot analysis revealed that the ER agonists at both EC80 and EC100 caused rapid and transient phosphorylation of extracellular signal-regulated kinases (ERK) in an ER-dependent manner. 3T3-L1 adipocytes treated with the ER agonists at EC80 for 24hours exhibited significant downregulation in mitochondrial respiration and glycolytic function. Importantly, EC80 values of 4-nonylphenol (6.0×10-10 m) and bisphenol A (1.0×10-8 m) are in the range of human body burdens. The finding that estrogenic chemicals at body burden levels cause significant impact on fat cell energy metabolism raises an important public health issue that deserves more attention.

Vitellogenin induction in caudal fin of guppy (Poecilia reticulata) as a less invasive and sensitive biomarker for environmental estrogens

Guppy (Poecilia reticulata) is an ideal model for studying environmental estrogens, and its large caudal fin has a high capacity to regenerate. This study analyzed the feasibility of caudal fin for detecting vitellogenin (Vtg), the most commonly used biomarker of environmental estrogens. Firstly, a sandwich ELISA for guppy Vtg was developed using purified lipovitellin and its antibody and it had a working range of 7.8–1000 ng/mL and detection limit of 3.1 ng/mL. The ELISA was used to detect tissue distribution of Vtg. In male guppy exposed to 50 and 100 ng/L 17β-estradiol (E2), Vtg concentration in caudal fin was higher than that in whole fish, brain, eyes, gonad, and skin, and was close to that in the liver. Furthermore, male guppies were exposed to environmental concentrations of 17a-ethinylestradiol (EE2) and bisphenol S (BPS) to validate the utility of caudal fin Vtg for detecting estrogenic activities. The lowest observed effect concentration of EE2 and BPS were lower than 2 ng/L and 1 μg/L, which were below or equal to the values reported for other species, demonstrating that caudal fin Vtg was highly sensitive to estrogenic chemicals. Therefore, caudal fins of guppies are suggested as alternative samples for Vtg biomarker detection.

HLA-DR expression variations on human regulatory T cells is associated with impaired immune tolerance

di(2-ethylhexyl) phthalate (DEHP) is one of the most commonly-used plasticizers and can exert estrogen-like effects and anti-androgen-like effects after entering the body. The critical windows for DEHP exposure are in utero and during lactation. There’s substantial evidence that hormonally active environmental estrogen perturbations in early life are associated with prostate carcinogenesis susceptibility later in life. In order to explore the effects of in utero and lactational exposure to DEHP on the male offspring’s susceptibility to prostate carcinogenesis, we established a rat model of developmental estrogenization: pregnant rats in three treatment groups were treated with DEHP at 0.01, 0.1 and 1 mg/kg BW/day from GD7 to PND21, and the male pups in positive group were treated with EB at 25ug/pup on PND 1, 3, 5. In order to induce the prostate carcinogenesis, half of the male offspring were given implants packed with estradiol and testosterone, and the other half were given empty tubes on PND90. The prostate weight, concentration of PSA in serum and histopathological changes were measured in male offspring on PND196. Data was analyzed by one-way analysis of variance (ANOVA) and x2 using SPSS Statistics software. Results showed that in utero treatment of DEHP decreased the prostate weight, prostate/body weight ratio and increased PSA concentrations of male pups in a dose-dependent manner. Compared with non-T + E treatment groups, T + E treatment increased the prostate weight and ratio of prostate/body weight, as well as the concentration of PSA. The results of prostate carcinogenesis parameters including PIN scores/frequency and Gleason scores/frequency were consistent with PSA, which meant that in utero and lactational exposure of DEHP was a risk factor of prostate carcinogenesis, and the increased estrogen/testosterone (E/T) ratio in adult might exert synergistic effects in the process of prostate carcinogenesis formation.

Effect of Bisphenol-A (BPA) on insulin signal transduction and GLUT4 translocation in gastrocnemius muscle of adult male albino rat

Environmental estrogens bind to estrogen receptors, mimic estrogenic actions, and have adverse effects on human health like Bisphenol – A (BPA) which is used as a monomer in the production of polycarbonate plastics (PC) and epoxy resins which are used in variety of canned foods. Skeletal muscle plays an essential role in maintaining systemic glucose metabolism. In the present study, we investigated the possible effects of BPA on insulin signalling molecules and GLUT4 translocation in the gastrocnemius muscle of adult male rat. Rats were divided into four groups – Group I: Control (vehicle-corn oil treated), Group II, III and IV were administered with BPA (10, 100 and 400mg/kg b.wt/day, respectively) through oral gavage. Fasting blood glucose level of BPA treated groups showed a significant increase, oral glucose tolerance and insulin tolerance were also impaired in these animals. BPA significantly decreased the protein levels of insulin signalling molecules like IR, IRS-1, Akt, AS160 and its phosphorylated forms and blunts GLUT4 translocation by altering the levels of v- and t- SNARE proteins that assist the translocation process, thereby decreasing glucose uptake and oxidation in the gastrocnemius muscle. These results suggest that BPA has detrimental effects on insulin signalling molecules and GLUT4 translocation in the gastrocnemius muscle and thus impairs glucose homeostasis.

Germline and reproductive tract effects intensify in male mice with successive generations of estrogenic exposure.

The hypothesis that developmental estrogenic exposure induces a constellation of male reproductive tract abnormalities is supported by experimental and human evidence. Experimental data also suggest that some induced effects persist in descendants of exposed males. These multi- and transgenerational effects are assumed to result from epigenetic changes to the germline, but few studies have directly analyzed germ cells. Typically, studies of transgenerational effects have involved exposing one generation and monitoring effects in subsequent unexposed generations. This approach, however, has limited human relevance, since both the number and volume of estrogenic contaminants has increased steadily over time, intensifying rather than reducing or eliminating exposure. Using an outbred CD-1 mouse model, and a sensitive and quantitative marker of germline development, meiotic recombination, we tested the effect of successive generations of exposure on the testis. We targeted the germline during a narrow, perinatal window using oral exposure to the synthetic estrogen, ethinyl estradiol. A complex three generation exposure protocol allowed us to compare the effects of individual, paternal, and grandpaternal (ancestral) exposure. Our data indicate that multiple generations of exposure not only exacerbate germ cell exposure effects, but also increase the incidence and severity of reproductive tract abnormalities. Taken together, our data suggest that male sensitivity to environmental estrogens is increased by successive generations of exposure.