Estrogenic effects of food wrap packaging xenoestrogens and flavonoids in female Wistar rats: a comparative study

Effects of Bisphenol A and Bisphenol F on Porcine Uterus Contractility

Introduction

Bisphenols, as endocrine disruptors, may cause a wide range of health problems in humans, but so far, not all of them have been confirmed in animals, including pigs. Since animals are also exposed to bisphenols, we hypothesised that these substances may have an effect on uterine contractility in pigs. Therefore, the aim of the study was to investigate the effect of the most-used bisphenol, bisphenol A (BPA), and a selected analogue, bisphenol F (BPF), on the contractile activity of the pig uterus.

Material and Methods

The investigation utilised smooth muscles from immature pigs (n = 6), cyclic pigs on days 12–14 of the oestrous cycle (n = 6) or early pregnant pigs on days 12–16 of pregnancy (n = 6). Strips of the myometrium were exposed to BPA and BPF at concentrations of 10⁻¹³–10⁻¹ M. Smooth muscle contractility was determined with equipment for measuring isometric contractions.

Results

BPA caused a significant decrease in contraction amplitude, and frequency and in myometrial tension in all groups examined. BPF caused a decrease in the amplitude and frequency of contractions in all groups and in myometrial tension in the early pregnant group.

Conclusion

The obtained results indicate that both BPA and BPF relaxed the porcine myometrium, but these changes, especially in the amplitude and frequency of contractions, were more evident after BPF treatment. The extent of relaxation is dependent on the physiological status of the animals.

Bisphenol A replacement chemicals, BPF and BPS, induce protumorigenic changes in human mammary gland organoid morphology and proteome

SignificanceBisphenol A (BPA), found in many plastic products, has weak estrogenic effects that can be harmful to human health. Thus, structurally related replacements-bisphenol S (BPS) and bisphenol F (BPF)-are coming into wider use with very few data about their biological activities. Here, we compared the effects of BPA, BPS, and BPF on human mammary organoids established from normal breast tissue. BPS disrupted organoid architecture and induced supernumerary branching. At a proteomic level, the bisphenols altered the abundance of common targets and those that were unique to each compound. The latter included proteins linked to tumor-promoting processes. These data highlighted the importance of testing the human health effects of replacements that are structurally related to chemicals of concern.

Environmental level of bisphenol F induced reproductive toxicity toward zebrafish

Bisphenol F (BPF), as an important bisphenol A substitute, is being increasingly used for industrial production. Here we performed large scale fecundity test for zebrafish that are continuous exposed to environmental levels of BPF (0.5, 5 and 50 μg/L) from embryonic stage, and identified suppressed spawning capacity of females and reduced fertility rate of males in adulthood. Although pathological change is only observed in female gonads, the transcriptional change in the hypothalamic-pituitary-gonad axis genes occurred in the gonads of both female and male fish at 150 days post-exposure. F1 generation embryos showed abnormal developmental outcomes including decreased heart rate, reduced body length, and inhibition of spontaneous movement after parental exposure to BPF. RNA-sequencing showed that the genes involved in skeletal/cardiac muscle development were significantly altered in F1 embryos spawned by BPF-treated zebrafish. The advanced pathway analysis showed that cancer and tumour formation were the most enriched pathways in the offspring of 0.5 and 5.0 μg/L groups; organismal development and cardiovascular system development were mainly affected after parental exposure to 50 μg/L of BPF; these changes were mediated by several involved regulators such as GATA4, MYF6, and MEF2C. These findings confirmed that long-term exposure to BPF at environment relevant concentration would result in reproductive toxicity among zebrafish indicating the urgent demand for the control of BPA substitutes.

Variability of Urinary Concentrations of Phenols, Parabens, and Triclocarban during Pregnancy in First Morning Voids and Pooled Samples

Urinary concentrations of phenols, parabens, and triclocarban have been extensively used as biomarkers of exposure. However, because these compounds are quickly metabolized and excreted in urine, characterizing participants' long-term average exposure from a few spot samples is challenging. To examine the variability of urinary concentrations of these compounds during pregnancy, we quantified four phenols, four parabens, and triclocarban in 357 first morning voids (FMVs) and 203 pooled samples collected during the second and third trimesters of 173 pregnancies. We computed intraclass correlation coefficients (ICCs) by the sample type (FMV and pool) across two trimesters and by the number of composite samples in pools, ranging from 2 to 4, within the same trimester. Among the three compounds detected in more than 50% of the samples, the ICCs across two trimesters were higher in pools (0.29-0.68) than in FMVs (0.17-0.52) and the highest ICC within the same trimester was observed when pooling either two or three composites. Methyl paraben and propyl paraben primarily exposed via cosmetic use had approximately 2-3 times higher ICCs than bisphenol A primarily exposed via diet. Our findings support that within-subject pooling of biospecimens can increase the reproducibility of pregnant women's exposure to these compounds and thus could potentially minimize exposure misclassification.

Bisphenol A Analogues Suppress Spheroid Attachment on Human Endometrial Epithelial Cells through Modulation of Steroid Hormone Receptors Signaling Pathway

Bisphenol A (BPA) is a well-known endocrine disruptor, widely used in various consumer products and ubiquitously found in air, water, food, dust, and sewage leachates. Recently, several countries have restricted the use of BPA and replaced them with bisphenol S (BPS) and bisphenol F (BPF), which have a similar chemical structure to BPA. Compared to BPA, both BPS and BPF have weaker estrogenic effects, but their effects on human reproductive function including endometrial receptivity and embryo implantation still remain largely unknown. We used an in vitro spheroid (blastocyst surrogate) co-culture assay to investigate the effects of BPA, BPS, and BPF on spheroid attachment on human endometrial epithelial cells, and further delineated their role on steroid hormone receptor expression. We also used transcriptomics to investigate the effects of BPA, BPS, and BPF on the transcriptome of human endometrial cells. We found that bisphenol treatment in human endometrial Ishikawa cells altered estrogen receptor alpha (ERα) signaling and upregulated progesterone receptors (PR). Bisphenols suppressed spheroid attachment onto Ishikawa cells, which was reversed by the downregulation of PR through PR siRNA. Overall, we found that bisphenol compounds can affect human endometrial epithelial cell receptivity through the modulation of steroid hormone receptor function leading to impaired embryo implantation.

Relationship between endocrine disruptors and obesity with a focus on bisphenol A: a narrative review

Introduction: Scientific data suggest that early exposure to endocrine-disrupting chemicals (EDCs) affect -repro, -neuro, -metabolic systems, to which are added other notions such as mixtures, window and duration of exposure, trans-generational effects, and epigenetic mechanisms. Methods: In the present narrative review, we studied the relationship between exposure to EDCs with the appearance and development of obesity. Results: Exposure to EDCs like Bisphenol A during the early stages of development has been shown to lead to weight gain and obesity. EDCs can interfere with endocrine signaling, affect adipocytes differentiation and endocrine function and disrupt metabolic processes, especially if exposure occurs at very low doses, in the mixture, during early development stages for several generations. Conclusion: Exposure to EDCs is positively associated with obesity development. Moreover, the use of integrative approaches which mimicking environmental conditions are necessary and recommended to evaluate EDCs' effects in future studies.

Bisphenol A substitutes and sex hormones in children and adolescents

Bisphenol F (BPF) and bisphenol S (BPS) are increasingly used as bisphenol A (BPA) substitutes in consumer products. Little is known about the effects of BPA substitutes on reproductive endocrine function in children and adolescents. Thus, we conducted a cross-sectional study to examine the associations of BPA, BPF, and BPS with sex steroid hormones among 6-19-year old participants. Included were 1317 participants with information on BPA, BPF, BPS, and serum sex hormones [total testosterone (TT), estradiol (E₂), and sex hormone binding globulin (SHBG)]. Multiple linear regression accounting for complex survey design was used to assess the association between bisphenols and sex hormones by sex-age groups. Exposure-response (ER) relationships were examined via restricted cubic splines. Significant association with BPF or BPS was sporadic, but BPA presented inverse association with the free androgen index (FAI, calculated as the ratio of TT to SHBG) and E₂ and positive association with SHBG and TT/E₂ in female adolescents. Further exploration of ER relationships showed that BPA (P for non-linearity = 0.03), BPF (P for non-linearity = 0.005), and BPS (P for non-linearity = 0.08) had a U-shaped relationship with FAI among female adolescents. Additionally, an inverse U-shaped curve was observed for BPA (P for non-linearity = 0.03), BPS (P for non-linearity = 0.01), and BPF (P for non-linearity = 0.01) with SHBG. The associations were virtually nonsignificant among males. Our study demonstrated that BPS and BPF may possess similar endocrine interrupting abilities as BPA.

Temporal Trends of Phenol, Paraben, and Triclocarban Exposure in California Pregnant Women during 2007-2014

Little is known about temporal trends of pregnant women's exposures to environmental phenols and parabens. We quantified four phenols [bisphenol A (BPA), bisphenol F, bisphenol S, and triclosan), four parabens [butyl paraben, ethyl paraben (ETPB), methyl paraben (MEPB), and propyl paraben (PRPB)], and triclocarban in 760 urine samples collected during 2007-2014 from 218 California pregnant women participating in a high-familial risk autism spectrum disorder cohort. We applied multiple regression to compute least square geometric means of urinary concentrations and computed average annual percent changes. We compared our urinary concentrations with those of other study populations to examine geographic variations in pregnant women's exposure to these target compounds. Urinary concentrations of BPA, MEPB, ETPB, and PRPB in this study population decreased over the study period [percent change per year (95% confidence interval): -5.7% (-8.2%, -3.2%); -13.0% (-18.1%, -7.7%); -5.5% (-11.0%, 0.3%); and -13.3% (-18.3%, -8.1%), respectively] and were consistently lower than those in pregnant women in other U.S. regions during the same study period. In recent years, certain phenols and parabens with known adverse health effects are being regulated or replaced with alternatives, which explains decreased body burdens observed in this study population. Either the national regulations or the advocacy campaigns in California may have influenced exposures or consumer product choices.

Development of a Generic Physiologically Based Kinetic Model to Predict In Vivo Uterotrophic Responses Induced by Estrogenic Chemicals in Rats Based on In Vitro Bioassays

The present study assessed the potential of a generic physiologically based kinetic (PBK) model to convert in vitro data for estrogenicity to predict the in vivo uterotrophic response in rats for diethylstibestrol (DES), ethinylestradiol (EE2), genistein (GEN), coumestrol (COU), and methoxychlor (MXC). PBK models were developed using a generic approach and in vitro concentration-response data from the MCF-7 proliferation assay and the yeast estrogen screening assay were translated into in vivo dose-response data. Benchmark dose analysis was performed on the predicted data and available in vivo uterotrophic data to evaluate the model predictions. The results reveal that the developed generic PBK model adequate defines the in vivo kinetics of the estrogens. The predicted dose-response data of DES, EE2, GEN, COU, and MXC matched the reported in vivo uterus weight response in a qualitative way, whereas the quantitative comparison was somewhat hampered by the variability in both in vitro and in vivo data. From a safety perspective, the predictions based on the MCF-7 proliferation assay would best guarantee a safe point of departure for further risk assessment although it may be conservative. The current study indicates the feasibility of using a combination of in vitro toxicity data and a generic PBK model to predict the relative in vivo uterotrophic response for estrogenic chemicals.

Factors Associated with Exposure to Dietary Bisphenols in Adolescents

Obesogenic endocrine-disrupting chemicals, such as bisphenol A (BPA) and its analogue bisphenol S (BPS), seem to play an important role in the development of obesity, although contradictory results have been reported. The aim of the present study was to conduct a gender analysis of the factors associated with exposure to dietary bisphenols in 585 Spanish adolescents. Dietary BPA and BPS exposure was assessed using a food frequency questionnaire. Foods and macronutrients accounting for more than 95% of energy intake were selected for analysis. Stepwise regression was used to estimate the foods that most contributed to dietary bisphenol exposure in the sample. Gender-related factors associated with greater dietary bisphenol exposure were evaluated using multivariate logistic regression models. Canned tuna was the main dietary source of BPA and BPS in both adolescent boys and girls. Overweight/obese girls showed a higher risk of high dietary exposure to BPA (odds ratio (OR): 3.38, 95% confidence interval (CI): 1.25-9.07) and total bisphenols (OR: 2.81, 95% CI: 1.03-7.67) in comparison with girls with a BMI lower than 25 kg/m². Present results indicate a positive association of dietary exposure to both total bisphenols and BPA with being overweight/obese in adolescent girls.

Sex-specific associations of prenatal exposure to bisphenol A and its alternatives with fetal growth parameters and gestational age

BACKGROUND

Bisphenol A (BPA) can cause detrimental effects on fetal growth. However, the effects of BPA alternatives, such as bisphenol F (BPF) and bisphenol S (BPS), on fetal growth are less known.

OBJECTIVE

To investigate the relationships of prenatal BPA, BPF, and BPS exposures with fetal growth parameters and gestational age.

METHODS

Urinary BPA, BPF, and BPS were measured in 1,197 pregnant women before delivery in a Chinese cohort. The associations of prenatal exposure to BPA, BPF, and BPS with fetal growth parameters and gestational age were examined, and associations stratified by fetal sex were also conducted. We used a restricted cubic splines (RCS) model to examine the dose-response associations between exposures and outcomes.

RESULTS

Maternal urinary BPA and BPF were negatively related to birth length (-0.30 cm, 95% CI: -0.44, -0.15 and -0.21 cm, 95% CI: -0.36, -0.07 comparing the extreme exposure groups, respectively, both p for trends < 0.01). These associations were more pronounced in girls with inverted U-shaped dose-response relationships. Maternal urinary BPA and BPF were positively related to ponderal index (0.05 g/cm³ × 100, 95% CI: 0.01, 0.09 and 0.04 g/cm³ × 100, 95% CI: 0.01, 0.08 comparing the extreme exposure groups, respectively, both p for trends = 0.02), and maternal urinary BPS was associated with shorter gestational age (-0.20 weeks, 95% CI: -0.37, -0.03 comparing the extreme exposure groups, p for trend = 0.02). These associations were only observed in girls and exhibited a linear dose-response relationship.

CONCLUSIONS

Prenatal BPA, BPF, and BPS exposures were associated with detrimental effects on fetal growth parameters, and stronger effects were noted in female infants.

Genome-wide expression changes induced by bisphenol A, F and S in human stem cell derived hepatocyte-like cells

The debate about possible adverse effects of bisphenol A (BPA) has been ongoing for decades. Bisphenol F (BPF) and S (BPS) have been suggested as “safer” alternatives. In the present study we used hepatocyte-like cells (HLCs) derived from the human embryonic stem cell lines Man12 and H9 to compare the three bisphenol derivatives. Stem cell-derived progenitors were produced using an established system and were exposed to BPA, BPF and BPS for 8 days during their transition to HLCs. Subsequently, we examined cell viability, inhibition of cytochrome P450 (CYP) activity, and genome-wide RNA profiles. Sub-cytotoxic, inhibitory concentrations (IC₅₀) of CYP3A were 20, 9.5 and 25 µM for BPA, BPF and BPS in Man12 derived HLCs, respectively. The corresponding concentrations for H9-derived HLCs were 19, 29 and 31 µM. These IC₅₀ concentrations were used to study global expression changes in this in vitro study and are higher than unconjugated BPA in serum of the general population. A large overlap of up- as well as downregulated genes induced by the three bisphenol derivatives was seen. This is at least 28-fold higher compared to randomly expected gene expression changes. Moreover, highly significant correlations of expression changes induced by the three bisphenol derivatives were obtained in pairwise comparisons. Dysregulated genes were associated with reduced metabolic function, cellular differentiation, embryonic development, cell survival and apoptosis. In conclusion, no major differences in cytochrome inhibitory activities of BPA, BPF and BPS were observed and gene expression changes showed a high degree of similarity.

Bisphenol A Analogues in Food and Their Hormonal and Obesogenic Effects: A Review

Bisphenol A (BPA) is the most well-known compound from the bisphenol family. As BPA has recently come under pressure, it is being replaced by compounds very similar in structure, but data on the occurrence of these BPA analogues in food and human matrices are limited. The main objective of this work was to investigate human exposure to BPA and analogues and the associated health effects. We performed a literature review of the available research made in humans, in in vivo and in vitro tests. The findings support the idea that exposure to BPA analogues may have an impact on human health, especially in terms of obesity and other adverse health effects in children.

In vivo actions of Bisphenol F on the reproductive neuroendocrine system after long-term exposure in zebrafish

Although Bisphenol F (BPF), a bisphenol A (BPA) analogue with a similar chemical structure to that of BPA, is widely used in commercial products, little is known about its potential toxic effects on the reproductive neuroendocrine system in vivo. The present study aimed to comprehensively evaluate the effects of BPF on the reproductive neuroendocrine system in zebrafish and to assess the potential mechanisms underlying its association with estrogen receptor (ER) and aromatase (AROM) pathways. Long-term exposure to environmentally relevant and low levels of BPF led to increased expression of reproductive neuroendocrine-related genes (kiss1, kiss1r, gnrh3, lhβ, and fshβ) in the zebrafish brain, as well as increased levels of adrenocorticotropic, gonadotropin-releasing, luteinizing, and follicle-stimulating hormones in the zebrafish brain and vitellogenin in the zebrafish liver. In addition, these effects were associated with an increase in erα, erβ, cyp19a, and cyp19b activity. Meanwhile, ER and AROM antagonists, alone or in combination, significantly attenuated the stimulation of kiss1, lhβ, vtg, and gnrh3 expression, thereby suggesting that chronic BPF exposure affects the regulation of the reproductive neuroendocrine system through activation of the ER and AROM pathways. Moreover, since BPF and bisphenol S induced toxic and reproductive neuroendocrine effects similar to those of BPA, the current accepted usage of BPA and its analogs should be reconsidered in the future.

Elevated concentrations of urinary triclocarban, phenol and paraben among pregnant women in Northern Puerto Rico: Predictors and trends

BACKGROUND

Understanding important sources and pathways of exposure to common chemicals known or suspected to impact human health is critical to eliminate or reduce the exposure. This is particularly important in areas such as Puerto Rico, where residents have higher exposures to numerous chemicals, as well as higher rates of many adverse health outcomes, compared to the mainland US.

OBJECTIVE

The aim of this study was to assess distributions, time trends, and predictors of urinary triclocarban, phenol, and paraben biomarkers measured at multiple times during pregnancy among women living in Northern Puerto Rico.

METHODS

We recruited 1003 pregnant women between years 2010 and 2016 from prenatal clinics and collected urine samples and questionnaire data on personal care product use at up to three separate visits, between 16 and 28 weeks gestation. Urine samples were analyzed for triclocarban, seven phenols and four parabens: 2,4-dichlorophenol, 2,5-dichlorophenol, benzophenone-3, bisphenol A (BPA), bisphenol S (BPS), bisphenol F, triclosan, butylparaben, ethylparaben, methylparaben, and propylparaben.

RESULTS

Detectable triclocarban, phenol and paraben concentrations among pregnant women were prevalent and tended to be higher than levels measured in women of reproductive age from the general US population, especially triclocarban, which had a median concentration 37 times higher in Puerto Rico participants (2.6 vs 0.07 ng/mL). A decreasing temporal trend was statistically significant for urine concentrations of BPA during the study period, while the BPA substitute BPS showed an increasing temporal trend. Significant and positive associations were found between biomarker concentrations with the products use in the past 48-h (soap, sunscreen, lotion, cosmetics). There was an increasing trend of triclocarban/triclosan urinary concentrations with increased concentrations of triclocarban/triclosan listed as the active ingredient in the bar soap/liquid soap products reported being used.

CONCLUSION

Our results suggest several potential exposure sources to triclocarban, phenols, and parabens in this population and may help inform targeted approaches to reduce exposure.

An Untargeted Metabolomics Approach to Investigate the Metabolic Modulations of HepG2 Cells Exposed to Low Doses of Bisphenol A and 17β-Estradiol

The model xeno-estrogen bisphenol A (BPA) has been extensively studied over the past two decades, contributing to major advances in the field of endocrine disrupting chemicals research. Besides its well documented adverse effects on reproduction and development observed in rodents, latest studies strongly suggest that BPA disrupts several endogenous metabolic pathways, with suspected steatogenic and obesogenic effects. BPA's adverse effects on reproduction are attributed to its ability to activate estrogen receptors (ERs), but its effects on metabolism and its mechanism(s) of action at low doses are so far only marginally understood. Metabolomics based approaches are increasingly used in toxicology to investigate the biological changes induced by model toxicants and chemical mixtures, to identify markers of toxicity and biological effects. In this study, we used proton nuclear magnetic resonance (1H-NMR) based untargeted metabolite profiling, followed by multivariate statistics and computational analysis of metabolic networks to examine the metabolic modulation induced in human hepatic cells (HepG2) by an exposure to low and very low doses of BPA (10-6M, 10-9M, and 10-12M), vs. the female reference hormone 17β-estradiol (E2, 10-9M, 10-12M, and 10-15M). Metabolomic analysis combined to metabolic network reconstruction highlighted different mechanisms at lower doses of exposure. At the highest dose, our results evidence that BPA shares with E2 the capability to modulate several major metabolic routes that ensure cellular functions and detoxification processes, although the effects of the model xeno-estrogen and of the natural hormone can still be distinguished.

Ginkgo biloba extract (EGb761) did not express estrogenic activity in an immature rat uterotrophic assay

Ginkgo biloba is a dioecious tree that has been used in traditional Chinese medicine for about 5,000 years. In previous studies on ginkgo biloba extract (EGb761) using in vitro systems, we confirmed that EGb761 has biphasic effects on estrogenicity. In this study, we evaluated the agonistic and antagonistic activities of EGb761 using a uterotrophic assay in immature female rats. To evaluate agonistic and antagonistic effects of EGb761 on uterus, 21-day-old immature Sprague-Dawley (SD) female rats were treated with EGb761 (100, 200, or 400 mg/kg) by oral gavage, 10 μg/kg of estradiol (E2) or 1 mg/kg tamoxifen (TM) by subcutaneous injection, or with EGb761 plus E2 or TM for 3 consecutive days. At the end of the treatment period, animals were sacrificed and their body weights and organ weights (liver, lung, spleen and kidney) were measured. In addition, estrogen-related gene expressions (IGFBP-1 in liver and CaBP-9 in uterus) were determined. During the experiment, no animal showed clinical signs, a change in body weight or died. EGb761 treatment alone had no effect on absolute/relative uterine weight, luminal epithelial cell height (LECH, μm), or luminal circumference (LC, μm). In addition, uterine weights, LECHs, and LC induced by E2 or TM were not significantly changed by EGb761 at any dose. These results collectively suggested EGb761 has no agonistic/antagonistic effects in utero.

Effects of bisphenol A and its analogs on reproductive health: A mini review

Known endocrine disruptor bisphenol A (BPA) has been shown to be a reproductive toxicant in animal models. Its structural analogs: bisphenol S (BPS), bisphenol F (BPF), bisphenol AF (BPAF), and tetrabromobisphenol A (TBBPA) are increasingly being used in consumer products. However, these analogs may exert similar adverse effects on the reproductive system, and their toxicological data are still limited. This mini-review examined studies on both BPA and BPA analog exposure and reproductive toxicity. It outlines the current state of knowledge on human exposure, toxicokinetics, endocrine activities, and reproductive toxicities of BPA and its analogs. BPA analogs showed similar endocrine potencies when compared to BPA, and emerging data suggest they may pose threats as reproductive hazards in animal models. While evidence based on epidemiological studies is still weak, we have utilized current studies to highlight knowledge gaps and research needs for future risk assessments.

Post-weaning xenohormone intake affects adult rat submandibular gland in a sex-dependent manner

OBJECTIVES

We previously reported that maternal exposure to genistein and vinclozolin, ingested alone or in combination, affects submandibular salivary glands of rat offspring. Here, we investigated the responsiveness of submandibular gland when such xenohormone exposure occurs later in life.

MATERIALS AND METHODS

Chemicals were given orally to male and female Wistar rats (1 mg/kg body weight per day), from weaning to adulthood. Submandibular glands and plasma were collected at postnatal day 100 for histologic and molecular analysis.

RESULTS

Whereas no effect was observed in females, increases in granular convoluted tubules area coupled with a modification of salivary secretions were found in male submandibular glands. Genistein and vinclozolin similarly increased the mRNA expression of Cystatin C, Mucin 10, Growth factors, and plasmatic EGF. Negative correlations were found between the expressions of androgen receptor and EGF (-0.34; p < 0.05), TGFα (-0.52; p < 0.01), Mucin 10 (-0.43; p < 0.05), and Cystatin C (-0.42; p < 0.05) as well as between progesterone receptor and EGF (-0.56; p < 0.01). The Spearman correlation test revealed also a positive correlation between salivary EGF-mRNA expression and EGF in plasma (+0.32; p < 0.05).

CONCLUSION

Our findings confirm the sex-dependent sensitivity of submandibular salivary glands to dietary xenohormones and underline the influence of the exposure period.

Effects of BPF on steroid hormone homeostasis and gene expression in the hypothalamic-pituitary-gonadal axis of zebrafish

Bisphenol F (BPF) has been frequently detected in various environmental compartments, and previous studies found that BPF exhibits similar estrogenic and anti-androgenic effects on the mammalian endocrine system to those of bisphenol A (BPA). However, the potential disrupting effects of BPF on aquatic organisms and the underling disrupting mechanisms have not been investigated. In this study, the potential disrupting mechanisms of BPF on the hypothalamic-pituitary-gonadal (HPG) axis and liver were probed by employing the OECD 21-day short-term fecundity assay in zebrafish. The results show that BPF exposure (1 mg/L) impaired the reproductive function of zebrafish, as exemplified by alterations to testicular and ovarian histology of the treated zebrafish. Homogenate testosterone (T) levels in male zebrafish decreased in a concentration-dependent manner, and 17β-estradiol (E2) levels increased significantly when fish were exposed to 0.1 and 1 mg/L BPF. The real-time polymerase chain reaction was performed to examine gene expression in the HPG axis and liver. Hepatic vitellogenin expression was significantly upregulated in males, suggesting that BPF possesses estrogenic activity. The disturbed hormone balance was enhanced by the significant changes in gene expression along the HPG axis. These alterations suggest that BPF leads to adverse effects on the endocrine system of teleost fish, and that these effects were more prominent in males than in females.

Evidence of Absence: Estrogenicity Assessment of a New Food-Contact Coating and the Bisphenol Used in Its Synthesis

Consumer concerns about exposure to substances found in food contact materials with estrogenic activity (EA) have created substantial demand for alternatives. We assessed the potential EA of both a new bisphenol monomer used to synthesize polymeric coatings for metal food-contact applications and the nonintentionally added substances (NIAS) that may migrate into food. We evaluated tetramethyl bisphenol F (TMBPF) using in vitro and in vivo assays. We extracted the polymeric coating using food simulants ethanol (50% v/v) and acetic acid (3% w/v) and measured migration using tandem liquid chromatography (LC)/mass spectrometry (MS) and LC time-of-flight MS for TMBPF and NIAS, respectively. We also tested migrants for EA using the E-SCREEN assay. TMBPF did not show estrogenic activity in the uterotrophic assay and did not alter puberty in male and female rats or mammary gland development in female rats. Neither TMBPF nor the migrants from the final polymeric coating increased proliferation of estrogen-sensitive MCF7 cells. TMBPF did not show estrogen-agonist or antagonist activity in the estrogen receptor-transactivation assay. TMBPF migration was below the 0.2 parts per billion detection limit. Our findings provide compelling evidence for the absence of EA by TMBPF and the polymeric coating derived from it and that human exposure to TMBPF would be negligible.

Natural occurrence of bisphenol F in mustard

Bisphenol F (BPF) was found in mustard up to a concentration of around 8 mg kg(-1). Contamination of the raw products or caused by the packaging could be ruled out. Also, the fact that only the 4,4'-isomer of BPF was detected spoke against contamination from epoxy resin or other sources where technical BPF is used. Only mild mustard made of the seeds of Sinapis alba contained BPF. In all probability BPF is a reaction product from the breakdown of the glucosinolate glucosinalbin with 4-hydroxybenzyl alcohol as an important intermediate. Hot mustard made only from brown mustard seeds (Brassica juncea) or black mustard seeds (Brassica nigra) contained no BPF. BPF is structurally very similar to bisphenol A and has a similar weak estrogenic activity. The consumption of a portion of 20 g of mustard can lead to an intake of 100-200 µg of BPF. According to a preliminary risk assessment, the risk of BPF in mustard for the health of consumers is considered to be low, but available toxicological data are insufficient for a conclusive evaluation. It is a new and surprising finding that BPF is a natural food ingredient and that this is the main uptake route. This insight sheds new light on the risk linked to the family of bisphenols.

Bisphenol S and F: A Systematic Review and Comparison of the Hormonal Activity of Bisphenol A Substitutes

BACKGROUND

Increasing concern over bisphenol A (BPA) as an endocrine-disrupting chemical and its possible effects on human health have prompted the removal of BPA from consumer products, often labeled "BPA-free." Some of the chemical replacements, however, are also bisphenols and may have similar physiological effects in organisms. Bisphenol S (BPS) and bisphenol F (BPF) are two such BPA substitutes.

OBJECTIVES

This review was carried out to evaluate the physiological effects and endocrine activities of the BPA substitutes BPS and BPF. Further, we compared the hormonal potency of BPS and BPF to that of BPA.

METHODS

We conducted a systematic review based on the Office of Health Assessment and Translation (OHAT) protocol.

RESULTS

We identified the body of literature to date, consisting of 32 studies (25 in vitro only, and 7 in vivo). The majority of these studies examined the hormonal activities of BPS and BPF and found their potency to be in the same order of magnitude and of similar action as BPA (estrogenic, antiestrogenic, androgenic, and antiandrogenic) in vitro and in vivo. BPS also has potencies similar to that of estradiol in membrane-mediated pathways, which are important for cellular actions such as proliferation, differentiation, and death. BPS and BPF also showed other effects in vitro and in vivo, such as altered organ weights, reproductive end points, and enzyme expression.

CONCLUSIONS

Based on the current literature, BPS and BPF are as hormonally active as BPA, and they have endocrine-disrupting effects.

CITATION

Rochester JR, Bolden AL. 2015. Bisphenol S and F: a systematic review and comparison of the hormonal activity of bisphenol A substitutes.

Cyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo

Hormone replacement therapy associated risks, and the concomitant reluctance of usage, has instigated the search for new generations of estrogen analogues that would maintain estrogen benefits without associated risks. Furthermore, if these analogues display chemo-preventative properties in breast and endometrial tissues it would be of great value. Both the selective estrogen receptor modulators as well as the selective estrogen receptor subtype modulators have been proposed as estrogen analogues with improved risk profiles. Phytoestrogen containing extracts of Cyclopia, an indigenous South African fynbos plant used to prepare Honeybush tea may serve as a source of new estrogen analogues. In this study three extracts, P104, SM6Met, and cup-of-tea, from two species of Cyclopia, C. genistoides and C. subternata, were evaluated for ER subtype specific agonism and antagonism both in transactivation and transrepression. For transactivation, the Cyclopia extracts displayed ERα antagonism and ERβ agonism when ER subtypes were expressed separately, however, when co-expressed only agonism was uniformly observed. In contrast, for transrepression, this uniform behavior was lost, with some extracts (P104) displaying uniform agonism, while others (SM6Met) displayed antagonism when subtypes were expressed separately and agonism when co-expressed. In addition, breast cancer cell proliferation assays indicate that extracts antagonize cell proliferation in the presence of estrogen at lower concentrations than that required for proliferation. Furthermore, lack of uterine growth and delayed vaginal opening in an immature rat uterotrophic model validates the ERα antagonism of extracts observed in vitro and supports the potential of the Cyclopia extracts as a source of estrogen analogues with a reduced risk profile.

Simple, sensitive and reliable in vivo assays to evaluate the estrogenic activity of endocrine disruptors

Purpose

We compared three in vivo assays, determining changes of body weight, and uterotropic and vaginal cytology assays, for the evaluation of estrogenic activity of an estrogen disrupting compound, Pueraria mirifica (PM), in comparison with 17β-estradiol (E).

Methods

Female rats were ovariectomized and gavaged with distilled water, 0.01, 0.1, 1, 10 and 20 mg/kg BW/day of E and 100 and 1,000 mg/kg BW/day of PM for 14 days. Body weights were measured weekly, and vaginal epithelium cells were monitored daily. The uterus was dissected at the end of the treatment period, weighed and examined for histomorphometry.

Results

There were a decrease in body weight and an increase in uterine weight, uterine, endometrium and myometrium areas, uterine gland numbers, and percent of cornified cell which were dependent on doses of E and PM treatments.

Conclusions

Of the three assays proposed, although all are reliable and had critical read-out, measurements of body and uterine weights is likely convenient and simple, but the uterotropic assay needs to kill the animals. Vaginal cytology assay appears most promising for sensitivity and shortening the duration of the assay. Compared to those of E, the estrogenic activity of PM at concentrations of 100 and 1,000 mg/kg BW was in the range of 14 to >20 mg/kg BW.

Perinatal xenohormone exposure impacts sweet preference and submandibular development in male rats

OBJECTIVE

To determine the effect of perinatal exposure to low doses of genistein and/or vinclozolin on submandibular salivary gland (SSG) development in juvenile and adult male rats and to establish a link with sweet preference.

MATERIAL AND METHODS

Female rats received orally (1 mg kg(-1) body weight/day) genistein and vinclozolin, alone or in combination, from the first gestational day up to weaning. Sweet preference was assessed at weaning and in adulthood in male offspring; submandibular glands were then collected to study the morphogenesis and mRNA expression of steroid receptors, growth factors and taste related proteins.

RESULTS

Exposure to genistein and/or vinclozolin resulted in a higher saccharin intake on postnatal day 25 (P < 0.05) linked to a higher number of pro-acinar cells (P < 0.01) and mRNA expression of progesterone receptor, growth factors and gustine (P < 0.01). These increases disappeared in adulthood, but mRNA expressions of sex hormone receptors and growth factors were strongly repressed in all treated groups (P < 0.01).

CONCLUSION

Our findings confirm that the SSG are target for xenohormones and provide evidence that perinatal exposure to low doses of genistein and/or vinclozolin could simultaneously disrupt not only the salivary gland prepubertal development and sweet intake but also endocrine gene mRNA expression later in life.

Kaempferol Exhibits Progestogenic Effects in Ovariectomized Rats

OBJECTIVE

Progesterone (P₄) plays a central role in women's health. Synthetic progestins are used clinically in hormone replacement therapy (HRT), oral contraceptives, and for the treatment of endometriosis and infertility. Unfortunately, synthetic progestins are associated with side effects, including cardiovascular disease and breast cancer. Botanical dietary supplements are widely consumed for the alleviation of a variety of gynecological issues, but very few studies have characterized natural compounds in terms of their ability to bind to and activate progesterone receptors (PR). Kaempferol is a flavonoid that functions as a non-steroidal selective progesterone receptor modulator (SPRM) in vitro. This study investigated the molecular and physiological effects of kaempferol in the ovariectomized rat uteri.

METHODS

Since genistein is a phytoestrogen that was previously demonstrated to increase uterine weight and proliferation, the ability of kaempferol to block genistein action in the uterus was investigated. Analyses of proliferation, steroid receptor expression, and induction of well-established PR-regulated targets Areg and Hand2 were completed using histological analysis and qPCR gene induction experiments. In addition, kaempferol in silico binding analysis was completed for PR. The activation of estrogen and androgen receptor signalling was determined in vitro.

RESULTS

Molecular docking analysis confirmed that kaempferol adopts poses that are consistent with occupying the ligand-binding pocket of PRA. Kaempferol induced expression of PR regulated transcriptional targets in the ovariectomized rat uteri, including Hand2 and Areg. Consistent with progesterone-l ke activity, kaempferol attenuated genistein-induced uterine luminal epithelial proliferation without increasing uterine weight. Kaempferol signalled without down regulating PR expression in vitro and in vivo and without activating estrogen and androgen receptors.

CONCLUSION

Taken together, these data suggest that kaempferol is a unique natural PR modulator that activates PR signaling in vitro and in vivo without triggering PR degradation.

In Utero and Lactational Exposure to Low-Dose Genistein-Vinclozolin Mixture Affects the Development and Growth Factor mRNA Expression of the Submandibular Salivary Gland in Immature Female Rats

It has been suggested that hormonally controlled submandibular salivary gland (SSG) development and secretions may be affected by endocrine disruptor compounds. We investigated the effects of oral gestation-lactation exposure to 1 mg/kg body weight daily dose of the estrogenic soy-isoflavone genistein and/or the anti-androgenic food contaminant vinclozolin in female rats. The SSGs of female offspring were collected at postnatal day 35 to study gland morphogenesis and mRNA expression of sex-hormone receptors and endocrine growth factors as sex-dependent biomarkers. Because of high expression in neonatal SSG, mRNA expression of transforming growth factor α was also studied. Exposure to genistein, vinclozolin, or a genistein+vinclozolin mixture resulted in significantly lower numbers of striated ducts linked to an increase in their area and lower acinar proliferation (Ki-67–positive nuclei). Exposure to the mixture had the highest significant effects, which were particularly associated with repression of epidermal growth factor, nerve growth factor, and transforming growth factor α expression. In conclusion, early exposure to low doses of genistein and vinclozolin can affect glandular structure and endocrine gene mRNA expression in prepubertal SSG in female rats, and the effects are potentialized by the genistein+vinclozolin mixture. Our study provides the first evidence that SSG are targeted by both estrogenic and anti-androgenic disrupting compounds and are more sensitive to mixtures.

Estrogenic activity of friedelin rich fraction (IND-HE) separated from Cissus quadrangularis and its effect on female sexual function

Women experience menopause differently across the world, in terms of their symptomology. Many experience symptoms of menopause like hot flashes, joint pain and loss of libido. Estrogen replacement is the prescribed therapy for most of the sexual dysfunction observed in menopausal women. Many women are reluctant to use exogenous hormone therapy for treatment of menopausal symptoms and are turning to botanical and dietary supplements for relief. In the present study IND-HE (friedelin rich fraction) was studied for estrogenic activity as well as its effect on sexual behavior in overiectomized female Wistar rats.

The rats were divided into 4 groups of six rats each. The Group 1 received distilled water, Group II - IND-HE (75 mg/kg p. o.), Group III - IND-HE (100 mg/kg p. o.) and Group IV received estrogen (estradiol) (1 mg/kg in olive oil suspension, s.c. bi-weekly). The treatment period was 8 weeks. On 1 day, one month and two month of treatment the sexual behavior was studied. At the end of the treatment the blood was withdrawn from retro-orbital plexus. The animals were sacrificed and uterus was removed, weighed and histology was studied. In different group of rats estrous cycle was studied which indicate estrogenic activity and for progestogenic activity of deciduoma formation was studied.

The result indicated that IND-HE (75 and 100 mg/kg p.o.) improved sexual behavior parameters. IND-HE (75 and 100) significantly (P< 0.01) decreased darting and hopping latency. The darting frequency and hopping frequency was significantly (P< 0.01) improved in IND-HE (75 and100 mg/kg p.o.) as well as estrogen group. Lordosis interval (LI) was increased significantly in estrogen group after 1^st month (P< 0.05), and after 2^nd month (P< 0.01). IND-HE (100) treatment showed increase in LI after 1^st month (P< 0.05) remained during 2^nd month (P< 0.01). While IND-HE (75) treatment increased LI only after 2^nd month (P< 0.05).IND-HE (75 and 100 mg/kg p.o.) showed estrogenic activity as indicated by vaginal cornification, increase in uterine weight and rise in serum estrogen.

Bis(hydroxyphenyl)methane-bisphenol F-metabolism by the HepG2 human hepatoma cell line and cryopreserved human hepatocytes

Bisphenol F (BPF) is present in the environment and as a contaminant of food. Humans may, therefore, be exposed to BPF, and an assessment of this risk is required. BPF has been shown to have genotoxic and endocrine-disruptor properties in a human hepatoma cell line (HepG2), which is a model system for studies of xenobiotic toxicity. In this study, we investigated the ability of HepG2 cells to biotransform BPF, because metabolism may affect the observed effects of BPF, and we compared this metabolic capacity with that of human hepatocytes. Cells were incubated for 24 hours with [(3)H]-BPF. The culture medium was then concentrated and its metabolites were isolated by high-performance liquid chromatography and identified by mass spectrometry. BPF was largely metabolized into the corresponding sulfate by the HepG2 cell line. BPF was metabolized into both sulfate and glucuronide by human hepatocytes, but with differences between individuals. The metabolism of BPF in both HepG2 cells and human hepatocytes suggests the existence of a detoxification pathway. Thus, these two cell models differ in metabolic capacity. It is, therefore, very important, when assessing the toxic effects of substances in vitro, to determine, in parallel, the biotransformation capacities of the model used to extrapolate in vivo.

Oral p-tert-octylphenol exposures induce minimal toxic or estrogenic effects in adult female Sprague-Dawley rats

Contamination of the environment with endocrine-disrupting chemicals (EDC) has raised concerns about potential health hazards for humans and wildlife. Human and wildlife exposure to one such ubiquitous chemical, p-tert-octylphenol (OP), are likely, due to its persistence in the environment and its presence in food, water, and items of daily use. OP is reported to bind to the estrogen receptor (ER) and alter expression of estrogen-responsive genes. Detrimental effects of OP exposures on the reproductive system have been observed in most, but not all, in vivo experiments. This study examined estrogenic effects of oral exposures of adult female rats to OP. In vitro, OP bound weakly to human ER and a co-activator protein, and accelerated proliferation of MCF-7 cells. Adult Sprague-Dawley rats were given OP by gavage daily for 35 d (25, 50, or 125 mg/kg/d). Body and organ weights and ovarian follicle populations were not significantly altered in OP-exposed adult rats, despite detectable levels of OP in reproductive organs. The estrous cycle of rats was slightly altered, but there were no significant estrogen-like changes in histomorphology or gene expression of the uterus. Prepubertal rats given 125 or 250 mg/kg OP by gavage for 3 d had reduced body weight compared to vehicle-exposed rats but failed to show any uterotrophic response, although 17alpha-ethinyl estradiol (EE, 10 microg/kg/d, ip) induced a threefold increase in uterine weight. Overall, results suggest that toxicity will occur before estrogenic effects with oral exposures to OP. Relevant environmental exposures likely pose little risk for estrogenic effects.

Analysis of isoflavonoids from leguminous plant extracts by RPHPLC/DAD and electrospray ionization mass spectrometry

Traditionally, food is associated with energetic and nutritious characteristics such as sources of carbohydrates, proteins and lipids. Recently, however, foods with bioactive substances such as isoflavones have received great attention. The objective of this study was therefore to evaluate the presence of the isoflavones daidzein, glycitein, genistein and their conjugated forms in grains and leaves of several leguminous plants utilized largely in Brazilian cuisine. Grains used in Peruvian cuisine were also analyzed. After extracting phenolic compounds with methanol (80%), isoflavones as detected by reversed-phase high-performance liquid chromatography/ diode-array detector were only found in chickpeas and soybean. Chickpea extracts showed only the isoflavone genistein at 31 microg/g defatted flour. Detection of these isoflavones was confirmed by electrospray ionization mass and tandem mass spectrometric experiments. For soybean, a distinct distribution of isoflavones was found in hypocotyls and cotyledon. The highest concentration of isoflavones found was approximately 5.9 mg/g for hypocotyls, whereas the total concentration of isoflavone was around 0.4 mg/g for the cotyledons (dry matter). These results indicate that isoflavone concentrations vary within the different tissues of the leguminous species tested.

Phytoestrogens and avian reproduction: Exploring the evolution and function of phytoestrogens and possible role of plant compounds in the breeding ecology of wild birds

Phytoestrogens are secondary plant compounds, which can act to mimic estrogen and cause the disruption of estrogenic responses in organisms. Although there is a substantial body of research studying phytoestrogens, including their mechanisms of estrogenic effects, evolution, and detection in biological systems, little is known about their ecological significance. There is evidence, however, that an ecological relationship involving phytoestrogens exists between plants and animals-plants may produce phytoestrogens to reduce fecundity of organisms that eat them. Birds and other vertebrates may also exploit phytoestrogens to regulate their own reproduction-there are well known examples of phytoestrogens inhibiting reproduction in higher vertebrates, including birds. Also, common plant stressors (e.g., high temperature) increase the production of secondary plant compounds, and, as evidence suggests, also induce phytoestrogen biosynthesis. These observations are consistent with the single study ever done on phytoestrogens and reproduction in wild birds [Leopold, A.S., Erwin, M., Oh, J., Browning, B., 1976. Phytoestrogens adverse effects on reproduction in California quail. Science 191, 98-100.], which found that drought stress correlated with increased levels of phytoestrogens in plants, and that increased phytoestrogen levels correlated with decreased young. This review discusses the hypothesis that plants may have an effect on the reproduction of avian species by producing phytoestrogens as a plant defense against herbivory, and that birds may "use" changing levels of phytoestrogens in the vegetation to ensure that food resources will support potential young produced. Evidence from our laboratory and others appear to support this hypothesis.

Dietary red clover (Trifolium pratense) induces oviduct growth and decreases ovary and testes growth in Japanese quail chicks

To determine whether drought-stress alters phytoestrogens in red clover and whether red clover in the diet influences sexual development in Japanese quail, we fed chicks diets containing irrigated or non-irrigated clover. Irrigation altered phytoestrogenic activity of red clover (determined using an in vitro bioassay), with extracts of irrigated clover diet containing more estrogenic activity than extracts of non-irrigated clover diet. Chick growth was negatively correlated with the amount of irrigated or non-irrigated clover in the diet. Dietary red clover also depressed both absolute and relative gonad weights; however, relative oviduct weight was increased by the irrigated diet. Diets did not affect serum vitellogenin. These results reveal a negative influence of drought-stress on phytoestrogenic potency of clover, and that red clover in the diet can inhibit avian growth and development independent of irrigation state. Thus, phytoestrogens may affect reproductive development in wild birds, and environmental stressors may influence levels of phytoestrogens in the field.

Postnatal development of pups from nursing rats treated with Gingko biloba

The Gingko biloba extract is contraindicated during pregnancy and lactation due to the lack of information about its effects on these reproductive phases. Previous studies have shown that G. biloba extract contains components with estrogenic and antiestrogenic activities, thus nursing dams treated with the extract of this plant could show reduction in milk production, resulting in malnutrition and poor development of pups. This work analyzes the postnatal development of pups, whose mothers were treated with G. biloba extract during the lactation period. Nursing Wistar rats received 3.5 mg/kg/day of G. biloba aqueous extract, corresponding to the highest human dose. Clinical signs of maternal toxicity were evaluated. The growth rate, viability, survival during treatment and lactation indices of the pups were calculated. The physical, motor and sensorial development of the pups was also evaluated. No maternal signs of toxicity were observed. As there were no biological differences between control and G. biloba treated pups, it is possible to assume that, in this experimental design, the administration of G. biloba aqueous extract to nursing rats during the lactation period seems to be devoid of toxic effect to mothers and to the physical, motor and sensory development of the pups.

Pediatric susceptibility to 18 industrial chemicals: A comparative analysis of newborn with young animals

We comprehensively re-analyzed the toxicity data for 18 industrial chemicals from repeated oral exposures in newborn and young rats, which were previously published. Two new toxicity endpoints specific to this comparative analysis were identified, the first, the presumed no observed adverse effect level (pNOAEL) was estimated based on results of both main and dose-finding studies, and the second, the presumed unequivocally toxic level (pUETL) was defined as a clear toxic dose giving similar severity in both newborn and young rats. Based on the analyses of both pNOAEL and pUETL ratios between the different ages, newborn rats demonstrated greater susceptibility (at most 8-fold) to nearly two thirds of these 18 chemicals (mostly phenolic substances), and less or nearly equal sensitivity to the other chemicals. Exceptionally one chemical only showed toxicity in newborn rats. In addition, Benchmark Dose Lower Bound (BMDL) estimates were calculated as an alternative endpoint. Most BMDLs were comparable to their corresponding pNOAELs and the overall correlation coefficient was 0.904. We discussed how our results can be incorporated into chemical risk assessment approaches to protect pediatric health from direct oral exposure to chemicals.

Disposition and metabolic profiling of bisphenol F in pregnant and nonpregnant rats

The distribution of bisphenol F (4,4'-dihydroxydiphenyl-methane, BPF) was studied in female Sprague-Dawley rats. Pregnant and nonpregnant animals were gavaged with a single dose of 7 or 100 mg/kg [3H]BPF and were kept for 96 h in metabolic cages. The excretion of BPF residues occurred mainly in urine (43-54% of the administered dose), which was found to contain at least six different metabolites, and to a lesser extent in feces (15-20% of the administered dose). Sulfatase treatment and subsequent high-performance liquid chromatography analyses suggest that the major urinary metabolite (more than 50% of the radioactivity present in urine) is a sulfate conjugate of BPF. At 96 h, BPF residues were detectable in all tissues examined with the largest amounts in the liver (0.5% of the dose). In pregnant rats dosed at day 17 of gestation, BPF residues were detected in the uterus, placenta, amniotic fluid, and fetuses (0.9-1.3% of the administered dose). Large amounts of radioactivity (8-10% of the dose) were still located in the digestive tract lumen at the end of the study. After administration of a single oral dose of [3H]BPF, 46% of the distributed radioactivity was excreted in bile over a 6 h period. In rats, BPF and/or its metabolites very likely undergo enterohepatic cycling, which could be responsible for the relatively high amounts of residues still excreted 4 days after BPF administration. This bisphenol is efficiently absorbed and distributed to the reproductive tract in female rats, and its residues pass the placental barrier at a late stage of gestation in rats.

Using vaginal cytology to assess the estrogenic activity of phytoestrogen-rich herb

To assess the estrogenic activities of synthetic estrogen, synthetic phytoestrogen, Pueraria lobata and three distinct cultivars of Pueraria mirifica, a phytoestrogen-rich herb, a vaginal cytology assay in ovariectomized rats were used. Rats were ovariectomized and treated with DW, estradiol valerate (1 mg/kg BW), genistein (0.25-2.5 mg/kg BW), Pueraria lobata and Pueraria mirifica (10-1,000 mg/kg BW) for 14 days. The vaginal cytology was checked daily and the uteri were dissected and weighed at the end of treatment or post-treatment periods. The treatments of DW, genistein and Pueraria lobata did not influence the vaginal epithelium, but the injection of estradiol valerate induced a vaginal cornification from day-3 of treatment to day-14 of post-treatment period. The occurrence of vaginal cornification after treatment and the recovery after the cessation was dependent on dosages and cultivars of Pueraria mirifica. The increments of uterus weight in all rats agreed with the cornification of vaginal epithelium. Although both uterotropic and vaginal cytology assays can be used to assess the estrogenic activity of phytoestrogen-rich herb, however, using vaginal cytology assay has two advantages: (1) we do not need to kill the animals and (2) we can follow up the recovery after the cessation of treatment.

Comparative susceptibility of newborn and young rats to six industrial chemicals

To elucidate the comparative susceptibility of newborn rats to chemicals, newborn and young animals were administered six industrial chemicals by gavage from postnatal days (PND) 4 to 21, and for 28 days starting at 5-6 weeks of age respectively, under the same experimental conditions as far as possible. As two new toxicity endpoints specific to this comparative analysis, presumed no-observed-adverse-effect-levels (pNOAELs) were estimated based on results of both main and dose-finding studies, and presumed unequivocally toxic levels (pUETLs) were also decided. pNOAELs for newborn and young rats were 40 and 200 for 2-chlorophenol, 100 and 100 for 4-chlorophenol, 30 and 100 for p-(alpha,alpha-dimethylbenzyl) phenol, 100 and 40 for (hydroxyphenyl)methyl phenol, 60 and 12 for trityl chloride, and 100 and 300 mg/kg/day for 1,3,5-trihydroxybenezene, respectively. To determine pUETLs, dose ranges were adopted in several cases because of the limited results of experimental doses. Values for newborn and young rats were thus estimated as 200-250 and 1000 for 2-chlorophenol, 300 and 500 for 4-chlorophenol, 300 and 700-800 for p-(alpha,alpha-dimethylbenzyl) phenol, 140-160 and 1000 for (hydroxyphenyl)methyl phenol, 400-500 and 300 for trityl chloride, and 500 and 1000 mg/kg/day for 1,3,5-trihydroxybenzene, respectively. In most cases, newborn rats were 2-5 times more susceptible than young rats in terms of both the pNOAEL and the pUETL. An exception was that young rats were clearly more susceptible than their newborn counterparts for trityl chloride.