Adverse effects of environmental toxicants, octylphenol and bisphenol A, on male reproductive functions in pubertal rats

Exposure, toxicological mechanism of endocrine disrupting compounds and future direction of identification using nano-architectonics

Endocrine-disrupting compounds (EDC) are a group of exogenous chemicals that structurally mimic hormones and interfere with the hormonal signaling cascade. EDC interacts with hormone receptors, transcriptional activators, and co-activators, altering the signaling pathway at both genomic and non-genomic levels. Consequently, these compounds are responsible for adverse health ailments such as cancer, reproductive issues, obesity, and cardiovascular and neurological disorders. The persistent nature and increasing incidence of environmental contamination from anthropogenic and industrial effluents have become a global concern, resulting in a movement in both developed and developing countries to identify and estimate the degree of exposure to EDC. The U.S. Environment Protection Agency (EPA) has outlined a series of in vitro and in vivo assays to screen potential endocrine disruptors. However, the multidisciplinary nature and concerns over the widespread application demand alternative and practical techniques for identifying and estimating EDC. The review chronicles the state-of-art 20 years (1990-2023) of scientific literature regarding EDC's exposure and molecular mechanism, highlighting the toxicological effects on the biological system. Alteration in signaling mechanisms by representative endocrine disruptors such as bisphenol A (BPA), diethylstilbestrol (DES), and genistein has been emphasized. We further discuss the currently available assays and techniques for in vitro detection and propose the prominence of designing nano-architectonic-sensor substrates for on-site detection of EDC in the contaminated aqueous environment.

Estrogenic and Non-Estrogenic Disruptor Effect of Zearalenone on Male Reproduction: A Review

According to some estimates, at least 70% of feedstuffs and finished feeds are contaminated with one or more mycotoxins and, due to its significant prevalence, both animals and humans are highly likely to be exposed to these toxins. In addition to health risks, they also cause economic issues. From a healthcare point of view, zearalenone (ZEA) and its derivatives have been shown to exert many negative effects. Specifically, ZEA has hepatotoxicity, immunotoxicity, genotoxicity, carcinogenicity, intestinal toxicity, reproductive toxicity and endocrine disruption effects. Of these effects, male reproductive deterioration and processes that lead to this have been reviewed in this study. Papers are reviewed that demonstrate estrogenic effects of ZEA due to its analogy to estradiol and how these effects may influence male reproductive cells such as spermatozoa, Sertoli cells and Leydig cells. Data that employ epigenetic effects of ZEA are also discussed. We discuss literature data demonstrating that reactive oxygen species formation in ZEA-exposed cells plays a crucial role in diminished spermatogenesis; reduced sperm motility, viability and mitochondrial membrane potential; altered intracellular antioxidant enzyme activities; and increased rates of apoptosis and DNA fragmentation; thereby resulting in reduced pregnancy.

Susceptibility of male reproductive system to bisphenol A, an endocrine disruptor: Updates from epidemiological and experimental evidence

Bisphenol A (BPA) is an omnipresent environmental pollutant. Despite being restrictions in-force for its utilization, it is widely being used in the production of polycarbonate plastics and epoxy resins. Direct, low-dose, and long-term exposure to BPA is expected when they are used in the packaging of food products and are used as containers for food consumption. Occupationally, workers are typically exposed to BPA at higher levels and for longer periods during the manufacturing process. BPA is a known endocrine disruptor chemical (EDC), that causes male infertility, which has a negative impact on human life from emotional, physical, and societal standpoints. To minimize the use of BPA in numerous consumer products, efforts and regulations are being made. Despite legislative limits in numerous nations, BPA is still found in consumer products. This paper examines BPA's overall male reproductive toxicity, including its impact on the hypothalamic-pituitary-testicular (HPT) axis, hormonal homeostasis, testicular steroidogenesis, sperm parameters, reproductive organs, and antioxidant defense system. Furthermore, this paper highlighted the role of non-monotonic dose-response (NMDR) in BPA exposure, which will help to improve the overall understanding of the harmful effects of BPA on the male reproductive system.

The effects of safranal against bisphenol AF on some reproductive parameters in male new zealand rabbits

Bisphenol AF (BPAF) is used as an analog of the endocrine disruptor BPA, whereas safranal is a powerful antioxidant obtained from the saffron plant. In the current study, the possible effects of BPAF and Safranal on some spermatological parameters, reproductive hormones, oxidant/antioxidant enzymes, and histopathological parameters were investigated. A total of 24 male New Zealand rabbits were divided into 4 groups (n= 6 for each group). The groups and the treatments they received by oral gavage for 9 weeks are as follows: The control group received 1 ml/day of corn oil, the BPAF group received 20 mg/kg/day of bisphenol AF, the Safranal group received 100 mg/kg/day safranal, and the treatment group received 20 mg/kg/day bisphenol AF and 100 mg/kg/day safranal. Although the spermatological parameters prior to the experiment revealed no differences among the groups, BPAF treatment reduced sperm quantity and motility, and elevated seminal plasma estrogen levels at the end of the study. BPAF treatments also had a negative impact on testicular MDA and GSH levels. It also caused seminiferous tubule degeneration in testicular tissue. On the other hand, the administration of safranal with BPAF decreased estrogen levels while increasing sperm concentration and motility to control group levels. Thus, the results suggested that safranal could have a beneficial effect in reducing BPAF-induced tissue damage. In conclusion, BPAF may have potentially harmful to the male reproductive system and safranal may exhibit a protective effect against BPAF exposure.

Molecular mechanisms regulating spermatogenesis in vertebrates: Environmental, metabolic, and epigenetic factor effects

The renewal of the natural resources is one of the most concerning aspects of modern farming. In animal production, there are many barriers breeders and researchers have to overcome to develop new practices to improve reproductive potential and hasten sexual maturation of the commercially viable species, while maintaining meat quality and sustainability. With the utilization of molecular biology techniques, there have been relevant advances in the knowledge of spermatogenesis, especially in mammals, resulting in new possibilities to control male fertility and the selection of desirable characteristics. Most of these discoveries have not been implemented in animal production. In this review, recent studies are highlighted on the molecular pathways involved in spermatogenesis in the context of animal production. There is also exploration of the interaction between environmental factors and spermatogenesis and how this knowledge may revolutionize animal production techniques. Furthermore, new insights are described about the inheritance of desired characteristics in mammals and there is a review of nefarious actions of pollutants, nutrition, and metabolism on reproductive potential in subsequent generations. Even though there are these advances in knowledge base, results from recent studies indicate there are previously unrecognized environmental effects on spermatogenesis. The molecular mechanisms underlying this interaction are not well understood. Research in spermatogenesis, therefore, remains pivotal as a pillar of animal production sustainability.

The impact of preconceptional exposure of F0 male mice to bisphenol A alone or in combination with X-rays on the intrauterine development of F2 progeny

Bisphenol A (BPA) is used for the production of polycarbonates and epoxy resins. Exposure to chemical and physical environmental factors may influence the health of exposed individuals, and of the next generations. This paper describes the prenatal effects in the F2 generation of mice after exposure of F0 pubescent or mature males to BPA (5 mg/kg bw, 10 mg/kg bw, 20 mg/kg bw), X-rays (0.05 Gy) or a combination of both factors in low doses (0.05 Gy + 5 mg/kg bw BPA) for 8 weeks. F1 males were mated with females from the same group but from a different litter. The females were sacrificed before parturition and examined for the number of implantations, live foetuses, as well as early and late post-implantation deaths. The fertility of males and the percentage of pregnant females in each group were also assessed. Exposure of pubescent F0 males to 10 mg/kg bw of BPA decreased the frequency of fertile males. Following exposure of pubescent males, the frequency of pregnant females decreased in the groups of 10 mg/kg bw and 20 mg/kg bw of BPA, whereas after exposure of adult F0 males in the groups of 5 mg/kg bw and 20 mg/kg bw of BPA, no significant changes in the frequency of total, live and dead implantations in all the experimental groups were found. The results observed in regard to prenatal development of the F2 generation suggest that sperm of the sons of F0 pubescent males exposed to BPA contains genetic defects that affect the possibility of fertilization. The results of both pubescent and mature males exposed to BPA showed that fertilized eggs died before implantation, probably due to defects induced in the sperm. This confirmed that BPA induced transgenerational effects in male germ cells.

Multigenerational impacts of gestational bisphenol A exposure on the sperm function and fertility of male mice

Growing evidence suggests that developmental exposure to bisphenol A (BPA)-a synthetic endocrine disruptor-causes atypical reproductive phenotypes that may persist for generations. However, the precise mechanism(s) by which BPA causes these adverse consequences is unclear. Here, pregnant female mice were orally exposed to 50 μg, 5 mg, and 50 mg BPA/kg body weight (bw)/day from 7 to 14 days of gestation. Corn oil treatments were used as control. The first filial generation (F1) and F2 males were used to generate F3 by mating them with unexposed females. High BPA doses impaired F1 and/or F1-F2 (multigenerational effect) male reproduction (i.e., disrupted testicular germ cell organization and spermatogenesis, altered sperm biochemical properties, and decreased sperm count, motility, and fertility) but not that of F3 males (transgenerational effect). Moreover, the observed multigenerational transmission of the abnormal reproductive traits was associated with alterations in the sperm DNA methylation patterns of specific male generations, with substantial proteomic changes in F1-F3 at the highest BPA dose. Given that the proteins related to male fertility and epigenetic modification are highly conserved among vertebrates, our findings may shed light on how exposure to environmental factors during pregnancy affects fertility in future generations in both humans and the other animals.

Breast and prostate glands affected by environmental substances (Review)

Environmental endocrine disruptor chemicals are substances that can alter the homeostasis of the endocrine system in living organisms. They can be released from several products used in daily activities. Once in the organism, they can disrupt the endocrine function by mimicking or blocking naturally occurring hormones due to their similar chemical structure. This endocrine disruption is the most important cause of the well‑known hormone‑associate types of cancer. Additionally, it is decisive to determine the susceptibility of each organ to these compounds. Therefore, the present review aimed to summarize the effect of different environmental substances such as bisphenol A, dichlorodiphenyltrichloroethane and polychlorinated biphenyls in both the mammary and the prostate tissues. These organs were chosen due to their association with the hormonal system and their common features in carcinogenic mechanisms. Outcomes derived from the present review may provide evidence that should be considered in future debates regarding the effects of endocrine disruptors on carcinogenesis.

Evaluation of post-adolescence exposure to bisphenol A on reproductive outcomes of male rodent models

The effect of post-adolescence bisphenol A (BPA) exposure on the reproductive system is not well-defined. We therefore performed this meta-analysis to elucidate the associations between post-adolescence BPA exposure and reproductive-related outcomes. A search was performed on the PubMed, EMBASE, and Web of science databases to identify relevant literature. The standardized mean differences (SMDs) and the 95 % confidence intervals (CIs) were measured by fixed-effects or random-effects models. Publication bias was assessed using funnel plots and Egger's regression test. A total of 40 studies were included in the final analysis. The results showed that post-adolescence BPA exposure was negatively associated with reproductive-related organ weighty (Testis weight: SMD: -0.61; 95 % Cl: -0.85, -0.36; epididymis weight; SMD: -0.43; 95 % Cl: -0.69, -0.17; seminal vesicles weight; SMD: -0.77; 95 % Cl: -1.05, -0.49) and sperm parameters (Sperm motility: SMD: -1.44; 95 % Cl: -1.95, -0.93; epididymal sperm concentration: SMD: -2.26; 95 % Cl: -2.79, -1.72; and abnormal sperm morphology: SMD: 2.41; 95 % Cl: 1.41, 2.86). Moreover, BPA exposure decreased the level of testosterone (T) and superoxide dismutase (SOD), but increased the ratio of serum estradiol (E2) to T. This systematic review demonstrates that post-adolescence exposure to BPA may adversely affect reproductive functions in male rodents.

The insulin-like growth factor system: A target for endocrine disruptors?

The insulin-like growth factor (IGF) system is a critical regulator of growth, especially during fetal development, while also playing a central role in metabolic homeostasis. Endocrine disruptors (EDs) are ubiquitous compounds able to interfere with hormone action and impact human health. For example, exposure to EDs is associated with decreased birthweight and increased incidence of metabolic disorders. Therefore, the IGF system is a potential target for endocrine disruption. This review summarises the state of the science regarding effects of exposure to major classes of endocrine disruptors (dioxins and dioxin-like compounds, polycyclic aromatic hydrocarbons, polybrominated diphenyl ethers, phthalates, perfluoroalkyl substances and bisphenol A) on the IGF system. Evidence from both experimental models (in vitro and in vivo) and epidemiological studies is presented. In addition, possible molecular mechanisms of action and effects on methylation are discussed. There is a large body of evidence supporting the link between dioxins and dioxin-like compounds and IGF disruption, but mixed findings have been reported in human studies. On the other hand, although only a few animal studies have investigated the effects of phthalates on the IGF system, their negative association with IGF levels and methylation status has been more consistently reported in humans. For polybrominated diphenyl ethers, perfluoroalkyl substances and bisphenol A the evidence is still limited. Despite a lack of studies for some ED classes linking ED exposure to changes in IGF levels, and the need for further research to improve reproducibility and determine the degree of risk posed by EDs to the IGF system, this is clearly an area of concern.

The prostaglandin synthases, COX-2 and L-PGDS, mediate prostate hyperplasia induced by low-dose bisphenol A

This study aimed to identify prostaglandin synthases (PGS) that mediate bisphenol A (BPA)-induced prostatic hyperplasia and explore their underlying mechanisms. In an in vivo study, male adult Sprague–Dawley rats were treated with different concentrations of BPA (10, 30, 90, or 270 μg/kg, i.g., daily), or with vehicle for 4 weeks. Results revealed that low-dose BPA induced prostatic hyperplasia with increased PCNA/TUNEL ratio. It significantly upregulated the expression of cyclooxygenase-2 (COX-2) and NF-κB in the dorsolateral prostate (P < 0.05) and the expression of lipocalin-type prostaglandin D synthase (L-PGDS) in ventral prostate (P < 0.05). The level of estradiol (E₂)/testosterone (T) and expression of androgen receptor (AR) and estrogen receptor α (ERα) were also altered. In vitro studies showed that low-dose BPA (0.1–10 nM) promoted the proliferation of human prostate fibroblasts and epithelial cells, and significantly upregulated the expression of COX-2 and L-PGDS in the cells. The two types of cell proliferation induced by BPA were inhibited by COX-2 inhibitor (NS398) and L-PGDS inhibitor (AT56), with increased apoptosis level. These findings suggested that COX-2 and L-PGDS could mediate low-dose BPA-induced prostatic hyperplasia through pathways involved in cell proliferation and apoptosis, which might be related to the functions of ERα and AR. The role of COX-2/NF-κB pathway in dorsolateral prostate requires further research.

Oral exposure to low-dose bisphenol A induces hyperplasia of dorsolateral prostate and upregulates EGFR expression in adult Sprague-Dawley rats

Prostate is sensitive to endocrine hormone level, and the synergetic effect of estrogen and androgen is critical in prostate growth. The change of signal pathways caused by the imbalance of estrogen and androgen might function in the occurrence of prostate diseases. As a well-known endocrine disruptor compound, bisphenol A (BPA) can disturb the normal function of endocrine hormone and affect prostate development. This study aims to investigate effects of BPA on the dorsolateral prostate (DLP) and the related gene expression of the tissue in adult Sprague-Dawley (SD) rats and to explore the mechanism for the effect of low-dose BPA on DLP hyperplasia. Three-month-old male SD rats were treated with BPA (10.0, 30.0, or 90.0 µg (kg.day)^-1, gavage) or vehicle (gavage) for 4 weeks. BPA significantly increased the DLP weight, the DLP organ coefficient, and the prostate epithelium height (p < 0.01) of rats dose-dependently. Microarray analysis and quantitative real-time polymerase chain reaction showed that BPA significantly upregulated the transcriptional levels of some genes, including pituitary tumor transforming gene 1, epidermal growth factor, Sh3kbp1, and Pcna. Furthermore, the expression of PCNA (p < 0.01), androgen receptor (p < 0.01), and EGF receptor (EGFR) (p < 0.001) in DLP was increased significantly by BPA treatment, and the expression of estrogen receptor alpha was also upregulated. The findings evidenced that low-dose BPA could induce DLP hyperplasia in adult rats, and the upregulated EGF/EGFR pathway that was responsive to estrogen and androgen might play an essential role in the DLP hyperplasia induced by low-dose BPA.

Environmental inhibitors of the expression of cytochrome P450 17A1 in mammals

Cytochrome P450 17A1 (CYP17A1; EC: 1.14.14.19) is a critically important bifunctional enzyme with nicotinamide adenine dinucleotide phosphate (NADPH) as its cofactor that catalyzes the formation of all endogenous androgens. Its hydroxylase activity catalyzes the 17α-hydroxylation of pregnenolone (PREG)/progesterone (P4) to 17α-OH-pregnenolone/17α-OH-progesterone, and its 17,20-lyase activity converts 17α-OH-pregnenolone/17α-OH-progesterone to dehydroepiandrosterone/androstenedione. Androgens are required for male reproductive development, so androgen deficiency resulting from CYP17A1 inhibition may lead to reproductive disorders. There has been some advances on the study of environmental chemicals inhibiting mammalian CYP17A1 expression but no related review was available so we think it now necessary to review their characteristics and inhibiting properties.

N-acetylcysteine alleviated bisphenol A-induced testicular DNA hypermethylation of rare minnow (Gobiocypris rarus) by increasing cysteine contents

Ubiquitous BPA exposure resulted in DNA methylation errors and oxidative stress. Numerous studies have demonstrated that oxidative stress can lead to changes in DNA methylation levels and supplementation with antioxidants, including N-acetylcysteine (NAC), was able to restore these changes. Our previous study supposed that BPA-induced de novo synthesis of glutathione (GSH) promoted DNA methylation process in Gobiocypris rarus testes. To validate this conjecture and explore the protective effects of NAC on BPA toxicity, the present study was carried out. Adult male G. rarus was treated with 225 μg L^-1 BPA and/or NAC for 7 days. The sperm motility and DNA integrity of G. rarus were determined. Meanwhile, the levels of 5-methylcytosine (5mC), GSH, hydrogen peroxide (H₂O₂), DNA methyltransferase proteins (DNMTs), γ-glutamyl cysteine synthetase (GCS), S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), homocysteine (HCY), nicotinamide adenine dinucleotide phosphate (NADPH) and cysteine in the testes were detected. Furthermore, the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were measured. Results indicated that NAC addition resulted in increase of cysteine contents and partially inhibited the BPA-induced DNA hypermethylation of G. rarus testes. In addition, the changes in DNA methylation levels in the testes after BPA and/or NAC treatment might be controlled by DNA methylation process that mediated by DNMTs. Moreover, BPA exposure caused oxidative stress in the testes and the elimination of H₂O₂ might be mainly accomplished by CAT while it changed to mainly through GPx after NAC supplement. Finally, the positive response of testicular antioxidant enzyme system and the antioxidant activity of NAC itself protected sperm motility and DNA integrity from oxidative damage in each group.

Effect of Surface Chemistry and Crystallographic Parameters of TiO2 Anatase Nanocrystals on Photocatalytic Degradation of Bisphenol A

The photocatalytic activity of a series of anatase TiO2 materials with different amounts of exposed (001) facets (i.e., 12% (TiO2-1), 38% (TiO2-3), and 63% (TiO2-3)) was tested in a batch slurry reactor towards liquid-phase bisphenol A (BPA, c0(BPA) = 10 mg/L, ccat. = 125 mg/L) degradation. Photo-electrochemical and photo-luminescence measurements revealed that with the increasing amount of exposed anatase (001) facets, the catalysts generate more electron-hole pairs and OH∙ radicals that participate in the photocatalytic mineralization of pollutants dissolved in water. In the initial stages of BPA degradation, a correlation between % exposure of (001) facets and catalytic activity was developed, which was in good agreement with the findings of the photo-electrochemical and photo-luminescence measurements. TiO2-1 and TiO2-3 solids achieved 100% BPA removal after 80 min in comparison to the TiO2-2 sample. Adsorption of BPA degradation products onto the TiO2-2 catalyst surface was found to have a detrimental effect on the photocatalytic performance in the last stage of the reaction course. Consequently, the global extent of BPA mineralization decreased with the increasing exposure of anatase (001) facets. The major contribution to the enhanced reactivity of TiO2 anatase (001) surface is the Brønsted acidity resulting from dissociative chemisorption of water on a surface as indicated by FTIR, TPD, and MAS NMR analyses.

"Bisphenol a: an emerging threat to male fertility"

BACKGROUND

Among the factors causing male infertility, one of the most debated is the exposure to environmental contaminants. Recently, the chemical compound Bisphenol A (BPA) has drawn attention from the reproductive science community, due to its ubiquitous presence in day-to-day life. Its toxic action appears to mainly affect the male reproductive system, directly impacting male fertility. MAIN: The purpose of this review is to investigate current research data on BPA, providing an overview of the findings obtained from studies in animal and human models, as well as on its supposed mechanisms of action.

CONCLUSION

A clear understanding of BPA action mechanisms, as well as the presumed risks deriving from its exposure, is becoming crucial to preserve male fertility. The development and validation of methodologies to detect BPA toxic effects on reproductive organs can provide greater awareness of the potential threat that this chemical represents.

Reproductive and developmental F1 toxicity following exposure of pubescent F0 male mice to bisphenol A alone and in a combination with X-rays irradiation

Exposure to environmental toxicants may affect reproduction and development of subsequent generations. This study was aimed at determining the male-mediated F1 effects induced following 8-weeks of subchronic exposure of F0 male mice to bisphenol A (BPA) alone and in a combination with X-rays irradiation (IR) started during their puberty. 4.5 weeks old F0 male mice were exposed to BPA dissolved in ethyl alcohol and diluted in drinking water at the following doses: 5 mg/kg bw, 10 mg/kg bw, 20 mg/kg bw or irradiated with X-rays (0.05 Gy) or exposed to a combination of low doses of both agents (0.05 Gy + 5 mg/kg bw BPA). Immediately after the end of the 8 weeks exposure F0 males were caged with two unexposed females each. Three quarters of the mated females from each group were sacrificed 1 day before expected parturition for examination of prenatal development of the offspring. The remainder of the females from each group were allowed to deliver and rear litters. Pups of exposed males were monitored for postnatal development for 8 weeks. At 8-9 weeks of age 6-8 males from each group of F1 generation were sacrificed to determine sperm count and quality. The current results, compared to the earlier results, showed that exposure of pubescent males to BPA alone or in combination with irradiation may be more damaging to their offspring than the exposure of adult males. The exposure of pubescent males to BPA alone and in combination with irradiation significantly increased the frequency of abnormal skeletons of surviving fetuses, increased the percent of mortality of pups in the F1 generation, reduced the sperm motility of F1 males and may induce obesity. Additionally, the combined BPA and irradiation exposure reduced the number of total and live implantations, whereas the exposure to BPA alone disturbed the male:female sex ratio. The above results may be caused by genetic or by epigenetic mechanisms. Limitation of use of products including BPA, especially by children and teenagers, is strongly recommended.

Reactive oxygen species and male reproductive hormones

Reports of the increasing incidence of male infertility paired with decreasing semen quality have triggered studies on the effects of lifestyle and environmental factors on the male reproductive potential. There are numerous exogenous and endogenous factors that are able to induce excessive production of reactive oxygen species (ROS) beyond that of cellular antioxidant capacity, thus causing oxidative stress. In turn, oxidative stress negatively affects male reproductive functions and may induce infertility either directly or indirectly by affecting the hypothalamus-pituitary-gonadal (HPG) axis and/or disrupting its crosstalk with other hormonal axes. This review discusses the important exogenous and endogenous factors leading to the generation of ROS in different parts of the male reproductive tract. It also highlights the negative impact of oxidative stress on the regulation and cross-talk between the reproductive hormones. It further describes the mechanism of ROS-induced derangement of male reproductive hormonal profiles that could ultimately lead to male infertility. An understanding of the disruptive effects of ROS on male reproductive hormones would encourage further investigations directed towards the prevention of ROS-mediated hormonal imbalances, which in turn could help in the management of male infertility.

Endocrine disruptors and testicular function

Despite concerns of the scientific community regarding the adverse effects of human exposure to exogenous man-made chemical substances or mixtures that interfere with normal hormonal balance, the so called "endocrine disruptors (EDs)", their production has been increased during the last few decades. EDs' extensive use has been implicated in the increasing incidence of male reproductive disorders including poor semen quality, testicular malignancies and congenital developmental defects such as hypospadias and cryptorchidism. Several animal studies have demonstrated that exposure to EDs during fetal, neonatal and adult life has deleterious consequences on male reproductive system; however, the evidence on humans remains ambiguous. The complexity of their mode of action, the differential effect according to the developmental stage that exposure occurs, the latency from exposure and the influence of the genetic background in the manifestation of their toxic effects are all responsible factors for the contradictory outcomes. Furthermore, the heterogeneity in the published human studies has hampered agreement in the field. Interventional studies to establish causality would be desirable, but unfortunately the nature of the field excludes this possibility. Therefore, future studies based on standardized guidelines are necessary, in order to estimate human health risks and implement policies to limit public exposure.

Melatonin ameliorates bisphenol A-induced perturbations of the prostate gland of adult Wistar rats

Bisphenol A (BPA) is an endocrine disrupting chemical (EDC) that has been demonstrated to induce alterations in reproductive organs while melatonin (ML), an antioxidant, present in plants and animals, is capable of protecting against EDC-induced alterations. Adult male Wistar rats (average weight, 240 + 10 g) were divided into four groups of ten animals each: Rats in group I (control) received oral 0.2 ml 1% dimethyl sulfoxide (DMSO)/99% canola oil as vehicle; group II received intra-peritoneal 10 mg/kg BW/day ML. Group III received oral BPA dissolved in DMSO and solubilized in canola oil at 10 mg/kg BW/day. Group IV were treated with same dose of BPA as group III with a concomitant intra-peritoneal 10 mg/kg BW/day ML. All treatments lasted for 14 days. BPA significantly increased the prostatic index of the rats while ML ameliorated it. BPA significantly increased serum levels of estrogen as well as prostate-specific antigen but decreased serum testosterone in the rats while concomitant treatment with ML ameliorated these alterations. Also, BPA caused vascular congestion, hyperplasia (functional, reactive and atypical) of prostatic epithelium as well as tubular atrophy the rats while ML attenuated the observed lesions. Decreased localization of αSmooth muscle actin, vimentin and S100 proteins were observed in the BPA-treated rats while these decreases were ameliorated by ML. The present study has shown that sub-acute oral administration of BPA induced alterations in prostatic index, serum hormone levels, down-regulated protein localization and induced morphological lesions of the prostate gland in rats while concomitant treatment with intra-peritoneal ML ameliorated these conditions. Hence, low dose of ML can protect against BPA-induced toxicity of the prostate gland of rats.

Parallel effect of 4-octylphenol and cyclic adenosine monophosphate (cAMP) alters steroidogenesis, cell viability and ROS production in mice Leydig cells

Over the last decade, there is growing incidence of male reproductive malfunctions. It has been documented that numerous environmental contaminants, such as endocrine disruptors (EDs) may adversely affect the reproductive functions of humans as well as wildlife species. The aim of this in vitro study was to examine the effects of 4-octylphenol (4-OP) on the steroidogenesis in mice Leydig cells. We evaluated the impact of this endocrine disruptor on the cholesterol levels and hormone secretion in a primary culture. Subsequently, we determined the cell viability and generation of reactive oxygen species (ROS) following 4-OP treatment. Isolated mice Leydig cells were cultured in the presence of different 4-OP concentrations (0.04-5.0 μg/mL) and 1 mM cyclic adenosine-monophosphate during 44 h. Cholesterol levels were determined from the culture medium using photometry. Quantification of steroid secretion was performed by enzyme-linked immunosorbent assay. The cell viability was assessed using the metabolic activity assay, while ROS production was assessed by the chemiluminescence technique. Slightly increased cholesterol levels were recorded following exposure to the whole applied range of 4-OP, without significant changes (P>0.05). In contrast, the secretion of steroid hormones, specifically dehydroepiandrosterone, androstenedione, and testosterone was decreased following exposure to 4-OP. Experimental doses of 4-OP did not affect cell viability significantly; however a moderate decrease was recorded following the higher doses (2.5 and 5.0 μg/mL) of 4-OP. Furthermore, relative treatment of 4-OP (5.0 μg/mL) caused a significant (P < 0.001) ROS overproduction in the exposed cells.

Urinary bisphenol A concentrations are associated with reproductive parameters in young men

Bisphenol A (BPA) is a pervasive environmental toxicant with known reproductive effects on sperm parameters and hormone levels. Several observational studies have investigated the associations between BPA exposure and male reproductive function, but findings are inconsistent. The objective of this study was to assess the associations between urinary BPA concentrations and semen quality and reproductive hormone levels in a cross-sectional study with 215 healthy young university students (18-23 years old), investigated between 2010 and 2011 in Southern Spain (Murcia Region). All subjects provided urine, blood serum and semen samples on a single day. Urinary BPA concentrations were measured by dispersive liquid-liquid microextraction and ultra-high performance liquid chromatography with tandem mass spectrometry detection. Semen quality was evaluated by measuring volume, concentration, motility, morphology and total sperm count (TSC). Serum samples were analyzed for reproductive hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, inhibin B and estradiol. Relationships between urinary BPA concentrations and semen quality parameters and reproductive hormone levels were examined using linear regression, adjusting for potential confounders and covariates. Ninety-five percent of the men had detectable urinary BPA concentrations with unadjusted median (5th-95th) of 2.8 (0.16-11.5) ng/mL. After adjustment for important covariates, there was a significant positive association between urinary BPA concentrations and serum LH levels (β = 0.07, 95%CI: 0.02;0.12, p-value < 0.01). Urinary BPA concentration was also significantly and inversely associated with sperm concentration (β = - 0.04, 95%CI: - 0.07;- 0.02, p-value < 0.01) and TSC (β = - 0.05, 95%CI: - 0.08;- 0.02, p-value < 0.01). No significant associations were found between BPA and other semen parameters or reproductive hormone levels. Our results support the hypothesis that BPA exposure may be associated with a reduction in Leydig cell capacity (increased LH levels) and decreased sperm counts in young men.

Oral exposure of low-dose bisphenol A promotes proliferation of dorsolateral prostate and induces epithelial-mesenchymal transition in aged rats

Bisphenol A (BPA) is a well-known endocrine disruptor compound reported to have prostate toxicity. This study aimed to assess the effect of BPA on the proliferation of dorsolateral prostate (DLP) and the expression of epithelial-mesenchymal transition (EMT)-related genes in aged rats. Male aged SD rats were treated with BPA (10.0, 30.0, and 90.0 µg/kg i.g., daily) or vehicle (i.g., daily) for 3 months. Treatment with BPA resulted in increased the expression of PCNA, DLP weight and DLP epithelial height compared with the control group (P < 0.01); such effects were more obvious at higher BPA doses. 90 µg/kg BPA significantly increased the estrogen to androgen ratio (P < 0.05). The EMT chip showed the BPA induced upregulation of vimentin, Snail, Twist1, and transforming growth factor beta 1, as well as the downregulation of E-cadherin in the DLP. Immunohistochemical data showed that the expression of vimentin, estrogen receptor subtypes, and androgen receptor increased and the expression of E-cadherin decreased in 30 and 90 µg/kg BPA groups. It was concluded that environmental exposure to low doses of BPA might promote the proliferation of DLP in aged rats by increasing the estrogen to androgen ratio and inducing EMT.

Effects of low dose of bisphenol A on the proliferation and mechanism of primary cultured prostate epithelial cells in rodents

Bisphenol A (BPA) is a well-known endocrine disruptor compound (EDC) that aggravates testosterone-induced benign prostate hyperplasia by increasing the relative weight of the ventral and dorsolateral prostate in rats. This phenomenon is primarily attributed to the exogenous estrogen effect of BPA. However, the direct effect of BPA on prostate cells has not been characterized. The present study investigated the proliferative effect and possible mechanisms of action of BPA on the prostatic epithelium of rats. The ventral prostate epithelial cells were cultured in vitro and the proliferation effects of BPA on cells were studied. The cells were identified as prostatic epithelial cells, and cell viability, cell apoptosis and the expressions of androgen receptors (AR) and estrogen receptors (ER), were detected. It was observed that 0.01–1 nM BPA promoted cell growth, with 1 nM BPA inducing the greatest increase in the rate of cell growth. However, BPA-treated cells exhibited no marked morphological changes compared with the control group. The cell apoptosis rate in each BPA-treated group was lower compared with the control group. The expression levels of ERα and ERβ increased, but the expression of AR decreased. The present study demonstrated that environmental exposure to BPA directly promoted the proliferation of prostate cells in rats through increasing the expression of estrogen receptors, reducing the expression of androgen receptors of the cells and decreasing apoptosis-induced cell death.

Mitochondrial Dysfunction and Ca2+ Overload in Injured Sertoli Cells Exposed to Bisphenol A

Bisphenol-A (BPA) is well known as one of endocrine-disrupting chemicals and testicular toxicant. In this present study, we determined whether BPA caused cell injury through mitochondria impairment and ROS overproduction. The cellular ROS production, mitochondrial ATP synthetase activity and Ca²⁺ concentration were examined. We have found BPA caused the cellular mitochondria dysfunction and followed by cell death in Sertoli cells. Moreover cytoplasm Ca²⁺ overload was also involved. Furthermore, pretreatment with N-acetyl-L-cysteine (NAC) could alleviate the damage by causing a remarkable decrease in ROS production and mitochondrial dysfunction. Collectively, our results showed that BPA exposure induced Sertoli cell apoptosis because of excessive ROS generation and mitochondrial dysfunction. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 823-831, 2017.

Serum Testosterone Concentrations and Urinary Bisphenol A, Benzophenone-3, Triclosan, and Paraben Levels in Male and Female Children and Adolescents: NHANES 2011-2012

BACKGROUND

Exposure to environmental phenols (e.g., bisphenol A, benzophenone-3, and triclosan) and parabens is widespread in the population. Many of these chemicals have been shown to have anti-androgenic effects both in vitro and in vivo.

OBJECTIVE

We examined the association of bisphenol A (BPA), benzophenone-3 (BP-3), triclosan (TCS), and parabens with serum total testosterone (TT) levels in child and adolescent participants (ages 6-19 years) in the National Health and Nutrition Examination Survey (NHANES) 2011-2012.

METHODS

We performed multivariable linear regression to estimate associations between natural log-transformed serum TT and quartiles of urinary BPA, BP-3, TCS, and parabens in male and female children (ages 6-11 years) and adolescents (ages 12-19 years).

RESULTS

BP-3 and BPA were associated with significantly lower TT in male adolescents, and BPA was associated with significantly higher TT in female adolescents. TT was not consistently associated with TCS or total parabens in children or adolescents of either sex.

CONCLUSIONS

To our knowledge, this is the first study to report an association of both BP-3 and BPA with serum TT in adolescents. Associations between BPA and TT differed according to sex in adolescents, with inverse associations in boys and positive associations in girls. BP-3 was associated with significantly lower TT in adolescent boys only. However, because of the limitations inherent to the cross-sectional study design, further studies are needed to confirm and elucidate on our findings. Citation: Scinicariello F, Buser MC. 2016. Serum testosterone concentrations and urinary bisphenol A, benzophenone-3, triclosan, and paraben levels in male and female children and adolescents: NHANES 2011-2012. Environ Health Perspect 124:1898-1904; http://dx.doi.org/10.1289/EHP150.

Oral administration of low-dose bisphenol A promotes proliferation of ventral prostate and upregulates prostaglandin D2 synthase expression in adult rats

This study aims to assess the effect of low oral dose of bisphenol A (BPA) on proliferation of ventral prostate (VP) and expression of related genes in adult rats. Three-month-old male Sprague Dawley rats were treated daily with BPA (10, 30, or 90 µg/kg, per os), 17β-estradiol (E2, 10.0 µg/kg, subcutaneously), or vehicle for 4 weeks. Treatment with 10 µg/kg BPA resulted in increased animal weight and VP epithelial height compared with the controls ( p < 0.01), while such effects were less pronounced in higher BPA doses. Treatment with E2 showed opposite effects, with significantly decreased animal weight and VP epithelial height ( p < 0.01). Interestingly, BPA increased serum E2 and reduced testosterone levels and significantly increased the estrogen to androgen ratio ( p < 0.05). In addition, BPA slightly increased dihydrotestosterone (DHT) levels. Immunohistochemistry data showed that BPA significantly upregulated proliferating cell nuclear antigen expression ( p < 0.01). Furthermore, microarray and reverse transcription polymerase chain reaction analyses showed that BPA induced upregulation of prostaglandin D2 synthase ( Ptgds), Fas, Pbef1, and complement factor B ( Cfb)as well as downregulation of Pttg1 and Fabp4 in the VP. These results indicated that environmental exposure to low doses of BPA may induce proliferation of VP in adult rats by increasing the estrogen to androgen ratio and upregulating expression of Ptgds to promote production of DHT.

Histopathology and Histomorphometric Investigation of Bisphenol A and Nonylphenol on the Male Rat Reproductive System

Background:

Bisphenol A (BPA) and nonylphenol (NP) have harmful effects on the endocrine system of humans and animals.

Aim:

We sought to investigate the effect of three doses of BPA and NP on the reproductive parameters of rats.

Materials and Methods:

Adult Wistar male rats weighing 150–200 g were used for a consecutive 35-day study. BPA and NP were given as gavage in three doses (5, 25, and 125 μg/kg). At the end of the study, the rats were anesthetized and 2 ml blood sample was obtained from the auxiliary venous plexus for the assessment of sex hormone levels. The testes were removed and kept in 10% formalin for the histomorphometric and histopathologic analyses.

Results:

BPA and NP significantly decreased the body weight of the animals compared to the controls (P < 0.05). The seminiferous tubule diameter and thickness of the seminiferous epithelium were significantly decreased in the groups receiving BPA and NP compared to the control (P < 0.05). The number of seminiferous tubules in every experimental group increased, except for the highest dose of NP (125 μg/kg), which showed a significant difference compared to the controls (P < 0.05). The number of spermatocytes and spermatogonia (54.97 ± 5.824, 35.78 ± 3.956, respectively) in the group receiving NP (125 μg/kg) was significantly decreased compared to the other groups. Serum levels of luteinizing hormone, Follicle stimulating hormone, and testosterone did not show any significant change compared to the controls.

Conclusion:

Based on the results, all three doses of BPA and NP significantly produced weight loss, as well as destruction of the testis tissue and impairment of the spermatogenesis.

BPA Directly Decreases GnRH Neuronal Activity via Noncanonical Pathway

Peripheral feedback of gonadal estrogen to the hypothalamus is critical for reproduction. Bisphenol A (BPA), an environmental pollutant with estrogenic actions, can disrupt this feedback and lead to infertility in both humans and animals. GnRH neurons are essential for reproduction, serving as an important link between brain, pituitary, and gonads. Because GnRH neurons express several receptors that bind estrogen, they are potential targets for endocrine disruptors. However, to date, direct effects of BPA on GnRH neurons have not been shown. This study investigated the effects of BPA on GnRH neuronal activity using an explant model in which large numbers of primary GnRH neurons are maintained and express many of the receptors found in vivo. Because oscillations in intracellular calcium have been shown to correlate with electrical activity in GnRH neurons, calcium imaging was used to assay the effects of BPA. Exposure to 50μM BPA significantly decreased GnRH calcium activity. Blockage of γ-aminobutyric acid ergic and glutamatergic input did not abrogate the inhibitory BPA effect, suggesting direct regulation of GnRH neurons by BPA. In addition to estrogen receptor-β, single-cell RT-PCR analysis confirmed that GnRH neurons express G protein-coupled receptor 30 (G protein-coupled estrogen receptor 1) and estrogen-related receptor-γ, all potential targets for BPA. Perturbation studies of the signaling pathway revealed that the BPA-mediated inhibition of GnRH neuronal activity occurred independent of estrogen receptors, GPER, or estrogen-related receptor-γ, via a noncanonical pathway. These results provide the first evidence of a direct effect of BPA on GnRH neurons.

The Effects of Endocrine Disruptors on Adipogenesis and Osteogenesis in Mesenchymal Stem Cells: A Review

Endocrine-disrupting chemicals (EDCs) are prevalent in the environment, and epidemiologic studies have suggested that human exposure is linked to chronic diseases, such as obesity and diabetes. In vitro experiments have further demonstrated that EDCs promote changes in mesenchymal stem cells (MSCs), leading to increases in adipogenic differentiation, decreases in osteogenic differentiation, activation of pro-inflammatory cytokines, increases in oxidative stress, and epigenetic changes. Studies have also shown alteration in trophic factor production, differentiation ability, and immunomodulatory capacity of MSCs, which have significant implications to the current studies exploring MSCs for tissue engineering and regenerative medicine applications and the treatment of inflammatory conditions. Thus, the consideration of the effects of EDCs on MSCs is vital when determining potential therapeutic uses of MSCs, as increased exposure to EDCs may cause MSCs to be less effective therapeutically. This review focuses on the adipogenic and osteogenic differentiation effects of EDCs as these are most relevant to the therapeutic uses of MSCs in tissue engineering, regenerative medicine, and inflammatory conditions. This review will highlight the effects of EDCs, including organophosphates, plasticizers, industrial surfactants, coolants, and lubricants, on MSC biology.

Estrogenic environmental contaminants alter the mRNA abundance profiles of genes involved in gonadal differentiation of the American bullfrog

Wildlife and human populations are exposed to anthropogenic mixtures of chemicals in the environment that may adversely influence normal reproductive function and development. We determined the effects of exposure to estrogenic chemicals and wastewater effluent (WWE) on developing gonads of the American bullfrog, Rana (Lithobates) catesbeiana, a species whose widespread distribution make it an ideal model for environmental monitoring of endocrine effects of chemical contaminants. Premetamorphic bullfrog tadpoles were exposed to treatment vehicle, 17β-estradiol (E2; 10(-9)M) or 4-tert-octylphenol (OP; 10(-9)M, 10(-8)M, and 10(-7)M). Additionally, gonadal differentiation was evaluated in bullfrog tadpoles from a WWE-containing site versus those from a reference location receiving no WWE. In both studies, phenotypic sex, steroidogenic factor-1 (nr5a1), and aromatase (cyp19a1) mRNA levels using quantitative real-time PCR were determined. Exposure to E2 or OP did not alter sex ratios. In controls, both nr5a1 and cyp19a1 transcript levels exhibited sexual dimorphism, with males demonstrating higher levels of nr5a1 and females greater abundance of cyp19a1. However, E2 exposure increased cyp19a1 mRNA abundance in testes and decreased levels in ovaries, eliminating the sexual dimorphism observed in controls. E2-exposed males exhibited increased nr5a1 transcript levels in the testes compared to controls, while females demonstrated no E2 effect. OP treatment had no effect on female cyp19a1 mRNA abundance, but exposure to 10(-7)M OP increased testicular transcript levels. Treatment with 10(-9) and 10(-8)M OP, but not 10(-7)M, resulted in decreased abundance of nr5a1 transcript in both ovaries and testes. Animals from the field had sexually dimorphic gonadal levels of cyp19a1, but both sexes from the WWE site exhibited elevated cyp19a1 transcript abundance compared to the reference location. Individual chemical compounds and anthropogenic wastewater effluent dispersed within the environment influence the levels of gonadal mRNA encoding key proteins involved in gonadal differentiation.

Higher urinary bisphenol A concentration is associated with unexplained recurrent miscarriage risk: evidence from a case-control study in eastern China

Background

Evidence about the association between Bisphenol A (BPA) and the risk of recurrent miscarriage (RM) in human being is still limited.

Objective

We evaluated the association of urinary BPA concentrations with RM in human being.

Methods

A hospital-based 1:2 matched case-control study on RM was carried out in Suzhou and Kunshan in Jiangsu Province in China between August 2008 and November 2011. Total urinary BPA concentrations in 264 eligible urine samples (102 RM patients and 162 controls) were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The Wilcoxon test and conditional logistic regression were used to estimate the differences between the groups and odds ratios (OR) with 95% confidence intervals (CI), respectively.

Results

The median ± IQR (interquartile range) (P₇₅-P₂₅) values of non-creatinine-adjusted total urinary BPA levels in the RM patients and the controls were 1.66±3.69ng/ml and 0.58±1.07ng/ml, respectively (0.98±2.67μg/g Cr (creatinine) and 0.40±0.77μg/g Cr. The adjusted BPA level was significantly higher in the RM patients than in the controls (Wilcoxon test, Z = 4.476, P<0.001). Higher level of urinary BPA was significantly associated with an increased risk of RM (P-trend <0.001). Compared to the groups with urinary BPA levels less than 0.16μg/g Cr, the women with levels of 0.40–0.93μg/g Cr and 0.93μg/g Cr or above had a significantly higher risk of RM (OR = 3.91, 95%CI: 1.23–12.45 and OR = 9.34, 95%CI: 3.06–28.44) that persisted after adjusting for confounding factors. The time from recently RM date to recruitment does not significantly influence the urinary BPA level (P = 0.090).

Conclusion

Exposure to BPA may be associated with RM risk.

Photodegradation of bisphenol A in aqueous medium: monitoring and identification of by-products by liquid chromatography coupled to high-resolution mass spectrometry

RATIONALE

Environmental bisphenol A (BPA) contamination is currently a matter of concern. This compound can disrupt the endocrine system by mimicking natural hormones and cause adverse effects on different organisms. In addition, it has been suggested that BPA can impair brain development, especially in fetuses and children. To efficiently remove BPA from contaminated water and wastewaters, several emerging technologies have been developed. Most are based on photodegradation. However, by-products resulting from the application of such methods have not been properly characterized.

METHODS

The photodegradation of BPA was conducted using two different methods: photocatalysis (TiO2/UV-A and TiO2/UV-C systems) and direct photolysis (UV-A and UV-C radiation). The degradation process was continuously monitored to identify and observe the by-products formed under these conditions. Direct infusion electrospray ionization coupled to high-resolution mass spectrometry in negative ion mode [ESI(-)-HRMS] and liquid chromatography coupled to high-resolution mass spectrometry (HPLC/HRMS) were employed to monitor these by-products.

RESULTS

The results revealed that the TiO2/UV-C system was the most efficient in causing both BPA depletion and mineralization of the organic matter in solution. Moreover, accurate mass data allowed for the assignment of molecular formulae for seven by-products, many of them unprecedented, formed under these conditions. Thus, a route for the photodegradation of BPA in aqueous medium could be proposed based on these results. Finally, additional tests revealed that the by-products showed a higher toxicity against Artemia salina than the primary precursor.

CONCLUSIONS

All of these findings indicate that the identification of by-products arising from oxidative treatments is of primary importance because such compounds can be more hazardous than their precursors.

Studies on the potential protective effect of cinnamon against bisphenol A- and octylphenol-induced oxidative stress in male albino rats

Among the numerous chemicals discharged into the surrounding environment, bisphenol A (BPA) and octylphenol (OP) have been shown to increase oxidative stress in body by disturbing the prooxidant/antioxidant balance of cells. Cinnamon aqueous extract (CAE) is a natural product rich in polyphenolic compounds that have antioxidant activity. This study was designed to investigate the protective efficacy of CAE against oxidative disorders induced by BPA and OP in male albino rats. Animals were divided into 6 groups (10 rats each) and treated orally, 3 times weekly for 50 days. Group 1: control vehicle (olive oil); group 2 (25 mg BPA/kg b.wt./day); group 3 (25 mg OP/kg b.wt./day); group 4 (200 mg CAE/kg b.wt./day); group 5 (CAE 2 h before BPA administration); and group 6 (CAE 2 h before OP administration). BPA- and OP-exposed groups showed insignificant elevation in the final body weight; weight gains and significant reduction only in the relative kidneys weight. Also, BPA and OP exposure resulted in significant increase in serum urea, creatinine and kidney, brain, testicular malondialdehyde (MDA) levels. Significant reduction in tissues reduced glutathione (GSH) contents; catalase (CAT) and superoxide dismutase (SOD) activities were also recorded in BPA and OP exposed animals compared to the control vehicle group. Pretreatment with CAE 2 h either before BPA or OP administration ameliorated the BPA- and OP-induced body weight; weight gains and relative organs weight changes and biochemical adverse effects. CAE pretreatment also protected against the recorded pathological changes in kidney, brain and testis. In conclusion, CAE could ameliorate the oxidative toxic effects of BPA and OP indicating its protective antioxidant effect.

Bisphenol A and Human Reproductive Health

Bisphenol A (BPA) is a high production volume chemical with adverse endocrine and reproductive health effects in toxicological studies. Despite widespread general population exposure to BPA, knowledge of its potential impacts upon reproduction and pregnancy in humans is limited. This paper reviews the current epidemiological literature on fertility and adverse pregnancy outcomes associated with BPA exposure. It also provides relevant resources for health care providers who are in a unique position to provide guidance in reducing exposure to this endocrine disrupting chemical.

Exposure to bisphenol A disrupts meiotic progression during spermatogenesis in adult rats through estrogen-like activity

The effect of bisphenol A (BPA) on the reproductive system is highly debated but has been associated with meiotic abnormalities. However, evidence is lacking with regard to the mechanisms involved. In order to explore the underlying mechanisms of BPA-induced meiotic abnormalities in adult male rats, we exposed 9-week-old male Wistar rats to BPA by gavage at 0, 2, 20 or 200 μg/kg body weight (bw)/day for 60 consecutive days. 17β-Estradiol (E2) was administered at 10 μg/kg bw/day as the estrogenic positive control. Treatments with 200 μg/kg bw/day of BPA and E2 significantly decreased sperm counts and inhibited spermiation, characterized by an increase in stage VII and decrease in stage VIII in the seminiferous epithelium. This was concomitant with a disruption in the progression of meiosis I and the persistence of meiotic DNA strand breaks in pachytene spermatocytes,and the ataxia-telangiectasia-mutated and checkpoint kinase 2 signal pathway was also activated; Eventually, germ cell apoptosis was triggered as evaluated by terminal dUTP nick-end labeling assay and western blot for caspase 3. Using the estrogen receptor (ER) antagonist ICI 182780, we determined that ER signaling mediated BPA-induced meiotic disruption and reproductive impairment. Our results suggest that ER signaling-mediated meiotic disruption may be a major contributor to the molecular events leading to BPA-related male reproductive disorders. These rodent data support the growing association between BPA exposure and the rapid increase in the incidence of male reproductive disorders.

Endocrine-disrupting chemicals and male reproductive health

Endocrine-disrupting chemicals are substances present in the environment that can interfere with normal hormonal balance and thus exert potentially adverse health effects on the human organism. Male reproductive system development and function may be susceptible to the effects of such environmental toxicants. Bisphenol A, phthalates and alkylphenols are important components of multiple products and are thus ubiquitously present in the environment. It has been demonstrated under laboratory conditions that they can exert detrimental effects on the male reproductive system. However, human exposure data are scarce and do not uniformly support toxicity of these substances at environmental concentrations. Despite substantial research efforts, the final answer to the problem of endocrine-disrupting chemicals is not yet in sight.

Perinatal BPA exposure demasculinizes males in measures of affect but has no effect on water maze learning in adulthood

Bisphenol A (BPA) is an endocrine disrupting agent that can alter the normal gonadal steroid-sensitive sexual differentiation of the brain and behavior. While reproductive behavior and physiology are known to be altered by perinatal exposure to this compound, less is known about BPA's effects on sex differences in learning and measures of affect. In order to evaluate the effects of perinatal BPA treatment on learning and affect in adulthood, we exposed rats to one of five doses of BPA through gestation and lactation then examined adult behavior in the Morris Water Maze (MWM), the Elevated Plus Maze (EPM) and the Forced Swim Test (FST). No effect of BPA was observed in the MWM, but on both the EPM and FST, low doses (5 μg/kg) of BPA eliminated sex differences found between controls; furthermore, a non-monotonic dose-response observed in previous studies was confirmed for these tasks. Overall, our study adds to the growing data suggesting that BPA interferes with the normal development of affective behaviors in a non-linear, dose-dependent manner.