Using Hepatic Gene Expression Assays in English Sole (Parophrys vetulus) to Investigate the Effects of Metro Vancouver Wastewater Effluents

The present study has investigated the effects of Metro Vancouver's wastewater treatment plant (WWTP) effluents on English sole (Parophrys vetulus) hepatic gene expression using novel targeted gene expression assays to complement the 2017 Burrard Inlet Ambient Monitoring Program conducted by Metro Vancouver. Seven locations of varying distance to the WWTPs were included. Twelve genes involved in xenobiotic defense (CYP1A, HSP70), thyroid function (DIO1), lipid and glucose metabolism (FABP1, FASN, GLUT2, PPARδ, PPARγ), protein synthesis (18S rRNA, RPS4X), and reproduction (ERα, VTG) revealed several differences between these impacted sites. A key finding of the present study was that males exhibited VTG transcript levels either equivalent or exceeding female levels of this gene at all sites investigated, indicating widespread exposure of estrogenic contaminants throughout Burrard Inlet. Furthermore, the induction of hepatic CYP1A was observed due to possible downstream sites being subjected to a larger influx of certain planar halogenated and non-halogenated hydrocarbons from multiple industrial contributors. This study also revealed significant differences between the sites examined and in genes involved in transcriptional regulation and synthesis of proteins, lipids and glucose metabolism, and thyroid hormone metabolism. Collectively, this study demonstrates the potential of molecular biomarkers of urban contaminant exposure in wild caught English sole for use in diagnosing a broader range of adverse health effects when combined with conventional whole organism health indicators.

Differences in Age-Related Changes in the Thymus in Rats Developmentally Exposed to Endocrine Disrupter Dichlorodiphenyltrichloroethane

We studied features of age-related changes in the thymus of mature male Wistar rats developmentally exposed to the endocrine disruptor dichlorodiphenyltrichloroethane (DDT). The study was carried out at the stage of early thymus involution. Differences in the thymus morphology associated with imbalance of morphogenetic processes in the cortex and medulla were observed after puberty in rats developmentally exposed to DDT. Increased proliferation of thymocytes, higher content of lymphoblasts, and concomitant decrease in T-cell migration in comparison with the control were found. Our findings indicate lower functional maturity of the thymus and prolonged disorders in the program of postnatal thymus development induced by the endocrine disruptor DDT.

Effects of dioxins on animal spermatogenesis: A state-of-the-art review

The male reproductive system is especially affected by dioxins, a group of persistent environmental pollutants, resulting in irreversible abnormalities including effects on sexual function and fertility in adult males and possibly on the development of male offspring. The reproductive toxicity caused by dioxins is mostly mediated by an aryl hydrocarbon receptor (AhR). In animals, spermatogenesis is a highly sensitive and dynamic process that includes proliferation and maturation of germ cells. Spermatogenesis is subject to multiple endogenous and exogenous regulatory factors, including a wide range of environmental toxicants such as dioxins. This review discusses the toxicological effects of dioxins on spermatogenesis and their relevance to male infertility. After a detailed categorization of the environmental contaminants affecting the spermatogenesis, the exposure pathways and bioavailability of dioxins in animals was briefly reviewed. The effects of dioxins on spermatogenesis are then outlined in detail. The endocrine-disrupting effects of dioxins in animals and humans are discussed with a particular focus on their effects on the expression of spermatogenesis-related genes. Finally, the impacts of dioxins on the ratio of X and Y chromosomes, the status of serum sex hormones, the quality and fertility of sperm, and the transgenerational effects of dioxins on male reproduction are reviewed.

Assessment of endocrine disruptive properties of PFOS: EFSA/ECHA guidance case study utilising AOP networks and alternative methods

Endocrine disruptors (EDs) are chemical substances that interfere with the endocrine system, adversely affecting human health and environment. Legislation with aim to eliminate and ban EDs have been introduced in EU, but the identification of EDs remains challenging and crucial step towards regulation and risk management. A guidance for ED assessment has been recently established for pesticides and biocides in the EU, which heavily relies on traditional toxicological testing in vivo. Most notably lacking mechanistic methods for some ED modalities and not covering many other modalities that might be affected by EDs. In this project, we focus on the ED assessment according to the valid legislation and explore the possibility to employ alternative methods to bolster the mechanistic understanding of the ED effects and eventually decrease the need for in vivo testing. We selected a well‐studied industrial chemical perfluorooctanesulfonic acid (PFOS) to be a model compound in a case study for ED assessment where the EU criteria were applied in the frame of human health risk assessment with focus on thyroid disruption and developmental neurotoxicity. A systematic literature review has been conducted for these effects (Scopus, Pubmed, Embase), and relevant studies were selected by title/abstract screening (RAYYAN) and full‐text examination. Selected studies were assessed for reliability (SciRAP), and all relevant data were extracted into a database and assessed by Weight of Evidence (WoE) approach. The initial analysis showed potential endocrine adverse effects and endocrine activity, meeting the ED criteria. The use of mechanistic and alternative methods enhanced the outcomes of WoE assessment. Also, the study provides a great hands‐on experience with the most up‐to‐date development in the area of risk assessment and EDs.

Converging Effects of Three Different Endocrine Disrupters on Sox and Pou Gene Expression in Developing Rat Hippocampus: Possible Role of microRNA in Sex Differences

Endocrine disrupting chemicals (EDCs) can impair hippocampus-dependent behaviors in rat offspring and in children. In search for key processes underlying this effect, we compared the transcriptomes of rat hippocampus on postnatal day 6 after gestational and lactational exposure to three different EDCs at doses known to impair development of learning and memory. Aroclor 1254, a commercial PCB mixture (5 mg/kg or 0.5 mg/kg), or bisphenol A (5 mg/kg or 0.5 mg/kg) were administered in chow, chlorpyrifos (3 mg/kg or 1 mg/kg) was injected subcutaneously. Male hippocampus exhibited a common effect of all three chemicals on genes involved in cell-autonomous processes, Sox6, Sox11, Pou2f2/Oct2, and Pou3f2/Brn2, all upregulated at the high dose. Additional genes of the Sox and Pou families were affected by only one or two of the chemicals. Real time RT PCR showed a comparable expression change for bisphenol A also at the lower dose. Female hippocampus exhibited much fewer genes with expression changes (almost none with false discovery rate <0.05), and none of the genes of the Sox and Pou families was affected. Since gene network analyses in male hippocampus suggested a link between Sox6 and miR-24, known to be repressed by activation of ER-alpha and to repress Sox6 in other tissues, this microRNA was measured. miR-24 was downregulated by all chemicals at the high dose in males. Values of Sox6 mRNA and miR-24 were inversely correlated in individual male hippocampus samples, supporting the hypothesis that the change in Sox6 expression resulted from an action of miR-24. In contrast, miR-24 levels remained unchanged in hippocampus of females. A sexually dimorphic response of miR-24 may thus be at the basis of the sex difference in Sox6 expression changes following exposure to the three chemicals. ER-alpha expression was also sex-dependent, but the expression changes did not parallel those of potential downstream genes such as Sox6. Sox6 is known to suppress differentiation of Parvalbumin (Pvalb)-expressing interneurons. Individual Sox6 levels (FPKM) were inversely correlated with levels of Pvalb, but not with markers of Sox6-independent interneuron subpopulations, Nos1 and 5HT3aR. Effects on interneuron development are further suggested, in males, by expression changes of Nrg1 and its receptor Erbb4, controlling interneuron migration. Our study disclosed new types of EDC-responsive morphogenetic genes, and illustrated the potential relevance of microRNAs in sexually dimorphic EDC actions.

Acute Changes in Thyroid Hormone Levels among Thai Pesticide Sprayers

The objective of this study was to investigate the relationship of acute pesticide exposures and acute changes in thyroid hormones among Thai farmers. We recruited 78 farmers, who were scheduled to spray insecticides (chlorpyrifos and/or cypermethrin) or herbicides (paraquat and/or glyphosate). On the day before spraying, farmers collected their first morning void urine and went for blood collection. On the spray day, urine samples were collected at end of the spraying event and they were interviewed with questionnaires. The next morning, the first morning void urine and blood samples were collected. Blood samples were analyzed for thyroid hormones. Urine samples were analyzed for the metabolites of the pesticide sprayed. The results showed that the thyroid hormones, free triiodothyronine (FT3) and total triiodothyronine (T3) were significantly reduced as urinary chlorpyrifos metabolite increased the day after spraying. Total thyroxine (T4) significantly increased as cypermethrin metabolites increased the day after spraying. T4 significantly increased as urinary glyphosate levels increased; however, FT3 and T3 decreased significantly as urinary paraquat levels increased the day after spraying. These findings suggest that acute exposures to the pesticides chlorpyrifos, cypermethrin, paraquat and glyphosate can produce acute effects on the hypothalamic-pituitary-thyroid (HPT) axis, acutely altering thyroid hormone levels.

Endocrine Disruptors and Polycystic Ovary Syndrome: Phthalates

OBJECTIVE

We aimed to investigate a possible role of the endocrine disruptors phthalates, di-2-ethylhexyl phthalate (DEHP) and mono (2-ethylhexyl) phthalate (MEHP), in polycystic ovary syndrome (PCOS) aetiopathogenesis. We also wished to evaluate the relationship between phthalates and metabolic disturbances in adolescents with PCOS.

METHODS

A total of 124 adolescents were included. Serum MEHP and DEHP levels were determined by high-performance liquid chromatography. Insulin resistance was evaluated using homeostasis model assessment-insulin resistance, quantitative Insulin Sensitivity Check Index, fasting glucose/insulin ratio, Matsuda index, and total insulin levels during oral glucose tolerance test. Participants were further subdivided into lean and obese subgroups according to body mass index (BMI).

RESULTS

Sixty-three PCOS and 61 controls, (mean age 15.2±1.5; range: 13-19 years) were enrolled. Serum DEHP and MEHP concentrations were not significantly different between PCOS and control groups. The mean (95% confidence interval) values of DEHP and MEHP were 2.62 (2.50-2.75) μg/mL vs 2.71 (2.52-2.90) μg/mL and 0.23 (0.19-0.29) μg/mL vs 0.36 (0.18-0.54) μg/mL in PCOS and the control groups respectively, p>0.05. Correlation analysis, adjusted for BMI, showed that both phthalates significantly correlated with insulin resistance indices and serum triglycerides in adolescents with PCOS.

CONCLUSION

Serum DEHP and MEHP concentrations were not different between adolescents with or without PCOS. However, these phthalates are associated with metabolic disturbances such as dyslipidemia and insulin resistance, independently of obesity, in girls with PCOS.

Ultrastructural Mechanisms of Impaired Aldosterone Synthesis in Rats Exposed to DDT during Prenatal and Postnatal Development

The study is aimed at elucidation of ultrastructural mechanisms underlying impaired aldosterone synthesis by glomerulosa cells in Wistar rats exposed to low doses of endocrine disrupter DDT during prenatal and postnatal development. Analysis of rat zona glomerulosa histology and function during the pubertal and postpubertal periods showed that exposure to endocrine disrupter DDT disturbs its development and reduced the production of aldosterone. Electron microscopy showed that changes in the aldosterone synthesis are related to impaired reorganization of the mitochondrial apparatus, one of the leading factors in the regulation of steroidogenesis, in glomerulosa cells in DDT-exposed rats during puberty.

Waterless Urinals Remove Select Pharmaceuticals from Urine by Phase Partitioning

We investigated the potential for waterless urinal sealants fluids to remove pharmaceuticals from urine. ¹H NMR, FTIR, and GC/MS characterization of the fluids indicated that they are mostly composed of aliphatic compounds. Removal of ethinyl estradiol was >40% for two of the three sealant fluids during simulated urination to a urinal cartridge but removal of seven other compounds with greater hydrophilicity was <30%. At equilibrium with Milli-Q water, ≥ 89% partitioning to the sealant phase was observed for three compounds with pH adjusted log K_ow (log D_ow) > 3.5. At equilibrium with synthetic urine, removal ranged widely from 2% to 100%. K_ow was poorly correlated with removal for both matrices at equilibrium, but D_ow was correlated with removal from synthetic urine for two of the three sealants, indicating that ionization and hydrophilicity control partitioning between the urine and sealant phases. To improve removal during urination, where equilibrium is not achieved, we increased the hydraulic retention time 100-fold over that of typical male urination. Removal of specific hydrophobic compounds increased, indicating that both hydrophobicity and kinetics control removal. Removal of ethinyl estradiol was ≥90% for all sealants in the increased hydraulic retention time experiment, demonstrating the potential for implementation to female urinals.

Carbon quantum dots functionalized agarose gel matrix for in solution detection of nonylphenol

Nonylphenol, an endocrine disrupter, is widely released to the aquatic environment, which is accumulative and extremely toxic to aquatic organisms. Here, we report a simple and cost-effective large-scale green synthesis of water-soluble highly fluorescent carbon quantum dots (CQDs) from marine biowaste (offshore washed algae) which gets quenched strongly in the presence of nonylphenol. These CQDs were around 20-40 nm in size and exhibit fluorescence constantly at 360 nm. The XRD profile depicted the interlayer spacing in the particle as 0.284 nm with a humped peak around 14 degrees showing the amorphous nature of the CQDs. FTIR spectra showed the stretching vibration of the hydroxyl groups (OH), asymmetric and symmetric stretching vibrations of the carboxylate anions (COO-). The fluorescence quantum yield of the CQDs is up to 68% and nonyl phenol detection limit is less than 0.1 µM. Furthermore, the CQDs were found to be stable at a wide pH range which makes it a suitable nonylphenol sensor for a variety of environmental samples. We functionalized these CQDs on an agarose gel matrix to develop a convenient sensor for the rapid detection of nonylphenol.

Rapid prolactin induction in adult male rats after treatment with diethylstilbestrol

Diethylstilbestrol (DES) is a synthetic oestrogen known to disrupt the endocrine system and to cause reproductive toxicity mediated via the hypothalamic-pituitary-adrenal axis; however, its molecular mechanism of action is poorly understood. In the present study, we found that, after only 1 week of exposure to DES, blood testosterone dramatically decreased and that this decrease was associated with a strong induction of prolactin (PRL). Even with the increase in PRL, the luteinising hormone and follicle-stimulating hormone mRNAs slightly decreased. Our results show that, after 48 hours of a single dose of DES, there was a six-fold increase in PRL expression. After exploring the upstream mechanisms, we determined that dopamine, which inhibits PRL secretion in male rats, did not decrease in the pituitary gland of DES-treated rats, whereas vasoactive intestinal peptide (VIP), which mediates the acute release of PRL, was elevated. Serotonin (5-HT) increased in the brain of male rats 24 hours after a single DES treatment; however, PRL, VIP or 5-HT was not induced by DES in female rats. Our results indicate that DES induces the expression of pituitary PRL in male rats by stimulating VIP in the hypothalamus and 5-HT in the central nervous system.

The Possible Impact of Antenatal Exposure to Ubiquitous Phthalates Upon Male Reproductive Function at 20 Years of Age

Phthalates are ubiquitous environmental endocrine-disrupting chemicals suspected to interfere with developmental androgen action leading to adverse effects on male reproductive function. Prenatal exposure studies in rodents show cryptorchidism, hypospadias and reduced testicular volume (TV), testosterone and anogenital distance in males. It is postulated that there is a developmental window in utero when phthalate exposure has the most potent adverse effects. Some human studies show associations between prenatal phthalate exposure and reduced calculated "free" serum testosterone in infant boys and shorter anogenital distance. However, there are no data available yet which link antenatal exposure to long-term effects in men. We aimed to correlate antenatal phthalate exposure with adult TV, semen parameters and serum reproductive hormone concentrations. 913 men from the Western Australian (Raine) Pregnancy Cohort were contacted aged 20-22 years. 423 (56%) agreed to participate; 404 underwent testicular ultrasound examination; 365 provided semen samples, and reproductive hormones were measured in 384. Maternal antenatal serum phthalate metabolite measurements were available for 185 and 111 men, who provided serum and semen, respectively. Maternal serum collected at 18 and 34 weeks gestation, stored at -80°C, was pooled and analyzed for 32 phthalate metabolites by liquid chromatography-tandem mass spectrometry. TV was calculated, semen analysis performed by WHO approved methods, and serum concentrations of gonadotrophins, inhibin B, and testosterone measured. Eleven phthalate metabolites were detected. Primary and secondary metabolites of di-(2-ethyl-hexyl) phthalate (DEHP) and di-iso-nonyl phthalate (DiNP) were positively correlated. After correction for adult height, BMI, presence of a varicocele and exposure to maternal smoking mono-iso-nonyl phthalate (MiNP) (r = -0.22) and sums of DEHP and DiNP metabolites (r = -0.24) and the sum of the metabolites of the high molecular weight phthalates (r = -0.21) were negatively correlated with TV (all p < 0.05). After adjustment for BMI adult serum total testosterone was positively associated with exposure to the following antenatal serum phthalate metabolites: mono-(2-ethylhexyl) phthalate (r = 0.26), MiNP (r = 0.18), the sum of metabolites for DEHP (r = 0.21) and DiNP (r = 0.18), and the sum of high molecular phthalates (r = 0.20) (p = 0.0005 to p = 0.02). Given sample size, storage duration and confounding through postnatal exposures, further studies are required.

Effect of bisphenol A on reproductive processes: A review of in vitro, in vivo and epidemiological studies

As bisphenol A (BPA) is characterized by a pronounced influence on human hormonal regulation, particular attention has been aimed at understanding its role in reproductive processes in males and females, as well as on fetal development. Owing to the increasing number of alarming reports on the negative consequences of the presence of BPA in human surroundings, more and more studies are being undertaken to clarify the negative effects of BPA on human reproductive processes. The aim of this work was to collect and summarize data on the influence of BPA exposure on reproductive health. Based on an analysis of selected publications it was stated that there is strong proof confirming that BPA is an ovarian, uterine and prostate toxicant at a level below the lowest observed adverse effect level (50 mg kg^-1 bodyweight) as well as a level below the proposed safe level (4 μg kg^-1 bodyweight). It seems there is also reliable evidence in relation to the negative effect of BPA on sperm quality and motility. Limited evidence also pertains to the case of the potential of BPA to affect polycystic ovary syndrome occurrence. Although in epidemiological studies this disease was common, in studies on animal models such results were still not confirmed. No unambiguous results of epidemiological studies and with animal models were obtained in relation to the evaluation of associations between BPA and implantation failure in women, evaluation of associations between BPA and sexual dysfunction in men, and impact of BPA on birth rate, birth weight and length of gestation. Copyright © 2017 John Wiley & Sons, Ltd.

The endocrine disruptor effect of the herbicides atrazine and glyphosate on Biomphalaria alexandrina snails

Atrazine (AZ) and glyphosate (GL) are herbicides that are widely applied to cereal crops in Egypt. The present study was designed to investigate the response of the snailBiomphalaria alexandrina(Mollusca: Gastropoda) as a bioindicator for endocrine disrupters in terms of steroid levels (testosterone (T) and 17β-estradiol (E)), alteration of microsomal CYP4501B1-like immunoreactivity, total protein (TP) level, and gonadal structure after exposure to sublethal concentrations of AZ or GL for 3 weeks. In order to study the ability of the snails' recuperation, the exposed snails were subjected to a recovery period for 2 weeks. The results showed that the level of T, E, and TP contents were significantly decreased (p ≤ 0.05) in both AZ- and GL-exposed groups compared with control (unexposed) group. The level of microsomal CYP4501B1-like immunoreactivity increased significantly (p ≤ 0.05) in GL- and AZ-exposed snails and reach nearly a 50% increase in AZ-exposed group. Histological investigation of the ovotestis showed that AZ and GL caused degenerative changes including azoospermia and oocytes deformation. Interestingly, all the recovered groups did not return back to their normal state. It can be concluded that both herbicides are endocrine disrupters and cause cellular toxicity indicated by the decrease of protein content and the increase in CYP4501B1-like immunoreactivity. This toxicity is irreversible and the snail is not able to recover its normal state. The fluctuation of CYP4501B1 suggests that this vertebrate-like enzyme may be functional also in the snail and may be used as a biomarker for insecticide toxicity.

In vitro exposure of Leydig cells to an environmentally relevant mixture of organochlorines represses early steps of steroidogenesis

Leydig cell steroidogenesis is mainly regulated by LH via increased cAMP production leading to STAR protein activation. STAR is essential for cholesterol shuttling inside mitochondria where steroidogenesis is initiated. Accumulating evidence suggest that persistent organochlorine compounds disrupt testicular function, but the mechanism of action remains poorly characterized. Here we report that in vitro exposure of MA-10 and MLTC-1 Leydig cells to an environmentally relevant mixture of 15 organochlorines impairs steroidogenesis. While having no effect on cell viability and basal steroid production, the organochlorine mixture caused a 50% decrease in cAMP-induced progesterone production. The mixture also reduced cAMP-induced 30 kDa STAR protein by 50% while having no effect on basal STAR protein. Basal or cAMP-induced Star mRNA levels and promoter activity were unaffected by the mixture, indicating that the organochlorine mixture acted at the translational/posttranslational level. Further supporting this is the fact that in COS-7 cells overexpressing STAR, the organochlorine mixture caused a decrease in the 30 kDa form of STAR and an accumulation of the 37 kDa forms. In addition to STAR, we found that the organochlorine mixture also decreases the levels of CYP11A1 and ADXR, two proteins essential for the conversion of cholesterol into pregnenolone. In conclusion, our data show that organochlorine exposure disrupts Leydig cell function by targeting different components of the steroidogenic pathway.

The environmental obesogen tributyltin chloride acts via peroxisome proliferator activated receptor gamma to induce adipogenesis in murine 3T3-L1 preadipocytes

Obesogens are chemicals that predispose exposed individuals to weight gain and obesity by increasing the number of fat cells, storage of fats into existing cells, altering metabolic rates, or disturbing the regulation of appetite and satiety. Tributyltin exposure causes differentiation of multipotent stromal stem cells (MSCs) into adipocytes; prenatal TBT exposure leads to epigenetic changes in the stem cell compartment that favor the production of adipocytes at the expense of bone, in vivo. While it is known that TBT acts through peroxisome proliferator activated receptor gamma to induce adipogenesis in MSCs, the data in 3T3-L1 preadipocytes are controversial. Here we show that TBT can activate the RXR-PPARγ heterodimer even in the presence of the PPARγ antagonist GW9662. We found that GW9662 has a 10-fold shorter half-life in cell culture than do PPARγ activators such as rosiglitazone (ROSI), accounting for previous observations that GW9662 did not inhibit TBT-mediated adipogenesis. When the culture conditions are adjusted to compensate for the short half-life of GW9662, we found that TBT induces adipogenesis, triglyceride storage and the expression of adipogenic marker genes in 3T3-L1 cells in a PPARγ-dependent manner. Our results are broadly applicable to the study of obesogen action and indicate that ligand stability is an important consideration in the design and interpretation of adipogenesis assays.

Endocrine disrupting chemicals and the developmental programming of adipogenesis and obesity

Obesity and related disorders are a burgeoning public health epidemic, particularly in the U.S. Currently 34% of the U.S. population is clinically obese (BMI > 30) and 68% are overweight (BMI > 25), more than double the worldwide average and 10-fold higher than Japan and South Korea. Obesity occurs when energy intake exceeds energy expenditure; however, individuals vary widely in their propensity to gain weight and accrue fat mass, even at identical levels of excess caloric input. Clinical, epidemiological, and biological studies show that obesity is largely programmed during early life, including the intrauterine period. The environmental obesogen hypothesis holds that prenatal or early life exposure to certain endocrine disrupting chemicals can predispose exposed individuals to increased fat mass and obesity. Obesogen exposure can alter the epigenome of multipotent stromal stem cells, biasing them toward the adipocyte lineage at the expense of bone. Hence, humans exposed to obesogens during early life might have an altered stem cell compartment, which is preprogrammed toward an adipogenic fate. This results in a higher steady state number of adipocytes and potentially a lifelong struggle to maintain a healthy weight, which can be exacerbated by societal influences that promote poor diet and inadequate exercise. This review focuses on the developmental origins of the adipocyte, the relationship between adipocyte number and obesity, and how obesogenic chemicals may interfere with the highly efficient homeostatic mechanisms regulating adipocyte number and energy balance.

Obesogens, stem cells and the maternal programming of obesity

Obesity and metabolic syndrome diseases have exploded into a global epidemic. Consumption of calorie-dense food and diminished physical activity are the generally accepted causes for obesity. But, could environmental factors expose preexisting genetic differences or exacerbate the root causes of diet and exercise? The environmental obesogen model proposes that chemical exposure during critical developmental stages influences subsequent adipogenesis, lipid balance and obesity. Obesogens are chemicals that stimulate adipogenesis and fat storage or alter the control of metabolism, appetite and satiety to promote weight gain. Tributyltin (TBT) is a high-affinity agonistic ligand for the retinoid X receptor (RXR) and peroxisome proliferator activated receptor gamma (PPARγ). RXR-PPARγ signaling is a key component in adipogenesis and the function of adipocytes; activation of this heterodimer increases adipose mass in rodents and humans. Thus, inappropriate activation of RXR-PPARγ can directly alter adipose tissue homeostasis. TBT exposure promoted adipocyte differentiation, modulated adipogenic genes and increased adiposity in mice after in utero exposure. These results suggest that organotin exposure is a previously unappreciated risk factor for the development of obesity and related disorders. Based on the observed effects of TBT on adipogenesis, we hypothesized that organotin exposure during prenatal adipose tissue development would create an environment that led to more adipocytes. We observed that the multipotent stromal cell compartment was altered by prenatal TBT exposure leading to an increased number of preadipocytes. This increase in the number of preadipocytes could correspondingly increase the steady state number of adipocytes in the adult, which could favor the development of obesity over time.

In utero exposure to low doses of bisphenol A lead to long-term deleterious effects in the vagina

The origins of the "endocrine disrupter hypothesis" may be traced to reports on adolescent daughters born to women who had taken the highly potent synthetic estrogen, diethylstilbestrol, while pregnant, and who developed a rare form of vaginal cancer and adenocarcinoma. Bisphenol A (BPA) is an estrogenic chemical that is highly employed in the manufacture of a wide range of consumer products. Some observational studies have suggested that the amounts of BPA to which we are exposed could alter the reproductive organs of developing rodents. We examined the influence of BPA at low doses to address the questions of (a) whether in utero exposure affects the vagina of the offspring and (b) which mechanisms cause the toxic effects. Gravid Sprague-Dawley dams were administered either 0.1 (low dose) or 50 mg/kg per day BPA, the no observed effect level, or 0.2 mg/kg per day 17 alpha-ethinyl estradiol by gavage. Striking morphological changes were observed in the vagina of postpubertal offspring leading us to examine vaginal estrogen receptor (ER) expression because BPA binds to the ER alpha, which is important for growth of the vaginal epithelium. We show that the full-length ER alpha is not expressed during estrus in the vagina of female offspring exposed to either dose of BPA when compared to the control group, whereas ER alpha expression does not differ from the control group during the diestrus stage. ER alpha downregulation seems to be responsible for the observed altered vaginal morphology.