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

Potent Clastogenicity of Bisphenol Compounds in Mammalian Cells-Human CYP1A1 Being a Major Activating Enzyme

Bisphenols (BPs) are environmental pollutants with relevant DNA damage in human population; however, they are generally inactive in standard mutagenicity assays, possibly due to insufficient metabolic activation. In this study, induction of micronuclei and double-strand DNA breaks by BPA, BPF, and BPS in Chinese hamster V79-derived cell lines expressing various human CYP enzymes and a human hepatoma (C3A) (metabolism-proficient) cell line were investigated. Molecular docking of BPs to human CYPs indicated some substrate-enzyme potentials, including CYP1A1 for each compound, which did not induce micronuclei in V79-derived cell lines expressing human CYP1A2, 2E1, or 3A4 but became positive in human CYP1A1-expressing (V79-hCYP1A1) cells. In V79-hCYP1A1 and C3A cells, all compounds induced double-strand DNA breaks and micronuclei formation, which were blocked/significantly attenuated by 1-aminobenzotriazole (CYP inhibitor) or 7-hydroxyflavone (selective CYP1A1 inhibitor). Coexposure of C3A cells to pentachlorophenol (sulfotransferase 1 inhibitor) or ketoconazole (UDP-glucuronosyltransferase 1A inhibitor) potentiated micronuclei induction by each compound, with thresholds lowered from 2.5-5.0 to 0.6-1.2 μM. Immunofluorescence staining of centromere protein B with micronuclei formed in C3A cells by each compound indicated pure clastogenic effects. In conclusion, BPs are potently clastogenic in mammalian cells, which require activation primarily by human CYP1A1 and are negatively modulated by phase II metabolism.

Enhancement effects of ethanolic extract of Fagonia cretica on Bisphenol A (BPA)-induced genotoxicity and biochemical changes in rats

Background

Fagonia cretica L. was considered to be a medical plant that was used for the treatment of different diseases, so the current study was designed to clarify whether Fagonia cretica extract (FCE) can avoid Bisphenol A (BPA)-induced genotoxicity and biochemical alterations in rats. Sixty-three male rats were used in this experiment. These animals were distributed into nine groups (seven rats each): negative control, control of corn oil, positive control that were administrated BPA in corn oil (10 mg/kg. b.w.) for 3 weeks, three protection groups received the same dose of BPA in corn oil at the same period together with FCE (3.3, 4.2 and 5.0 g/kg) daily for 3 weeks, and three therapeutic groups received FCE alone at the same doses for 10 days after cessation of BPA treatment. Genetic and biochemical studies were conducted. Genetic studies involved DNA comet assay, micronucleus test, chromosome examination, and mitotic index analysis. Biochemical studies involved liver function (AST, ALT, ALph, and Bilirubin), kidney function (urea and creatinine contents), protein profile, MDA, and endogenous antioxidative system (SOD, CAT, and ACHE) as well as nucleic acid (DNA and RNA) contents in the liver, kidney, and brain tissues.

Results

The results demonstrated that the treatment with BPA induced a significant elevation in genetic abnormalities and deleterious effects in biochemical parameters in relation to untreated control. FCE treatment was found to be significantly diminished the massive damage in the genetic constituents and dangerous alterations in biochemical parameters with respect to BPA treatment alone. These enhancements were increased by increasing the dose level of FCE. Moreover, better results were clarified by utilizing FCE as a protective agent than its utilization as a therapeutic agent especially by using the high dose (5.0 g/kg), in which mostly genetic and biochemical alterations were observed to be restored towards natural levels.

Conclusions

These findings clarified a new insight into the protective effect of FCE in minimizing BPA-induced genotoxicity and biochemical changes in rats detecting the capability of such medicinal plant for alleviating the adverse effect of BPA.

Impact of environmental toxin exposure on male fertility potential

Idiopathic infertility is the most common individual diagnosis in male infertility, representing nearly 44% of cases. Research studies dating over the last half-century consistently demonstrate a decline in male fertility that is incompletely explained by obesity, known genetic causes, or diet and lifestyle changes alone. Human exposures have changed dramatically over the same time course as this fertility decline. Synthetic chemicals surround us. Some are benevolent; however, many are known to cause disruption of the hypothalamic-pituitary-gonadal axis and impair spermatogenesis. More than 80,000 chemicals are registered with the United States National Toxicology Program and nearly 2,000 new chemicals are introduced each year. Many of these are known toxins, such as phthalates, polycyclic aromatic hydrocarbons, aromatic amines, and organophosphate esters, and have been banned or significantly restricted by other countries as they carry known carcinogenic effects and are reproductively toxic. In the United States, many of these chemicals are still permissible in exposure levels known to cause reproductive harm. This contrasts to other chemical regulatory legislature, such as the European Union's REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) regulations which are more comprehensive and restrictive. Quantification of these diverse exposures on an individual level has proven challenging, although forthcoming technologies may soon make this data available to consumers. Establishing causality and the proportion of idiopathic infertility attributable to environmental toxin exposures remains elusive, however, continued investigation, avoidance of exposure, and mitigation of risk is essential to our reproductive health. The aim of this review is to examine the literature linking changes in male fertility to some of the most common environmental exposures. Specifically, pesticides and herbicides such as dichlorodiphenyltrichloroethane (DDT), dibromochloropropane (DBCP), organophosphates and atrazine, endocrine disrupting compounds including plastic compounds phthalates and bisphenol A (BPA), heavy metals, natural gas/oil, non-ionizing radiation, air and noise pollution, lifestyle factors including diet, obesity, caffeine use, smoking, alcohol and drug use, as well as commonly prescribed medications will be discussed.

Gestational Exposure to Bisphenol A Affects Testicular Morphology, Germ Cell Associations, and Functions of Spermatogonial Stem Cells in Male Offspring

Exposure to bisphenol A (BPA) in the gestational period damages the reproductive health of offspring; detailed evidence regarding BPA-induced damage in testicular germ cells of offspring is still limited. In this study, pregnant mice (F0) were gavaged with three BPA doses (50 μg, 5 mg, and 50 mg/kg body weight (bw)/day; tolerable daily intake (TDI), no-observed-adverse-effect-level (NOAEL), and lowest-observed-adverse-effect level (LOAEL), respectively) on embryonic days 7 to 14, followed by investigation of the transgenerational effects of such exposure in male offspring. We observed that the NOAEL- and LOAEL-exposed F1 offspring had abnormalities in anogenital distance, nipple retention, and pubertal onset (days), together with differences in seminiferous epithelial stages and testis morphology. These effects were eradicated in the next F2 and F3 generations. Moreover, there was an alteration in the ratio of germ cell population and the apoptosis rate in germ cells increased in F1 offspring at the LOAEL dose. However, the total number of spermatogonia remained unchanged. Finally, a reduction in the stemness properties of spermatogonial stem cells in F1 offspring was observed upon LOAEL exposure. Therefore, we provide evidence of BPA-induced disruption of physiology and functions in male germ cells during the gestational period. This may lead to several reproductive health issues and infertility in offspring.

Linoleic acid promotes testosterone production by activating Leydig cell GPR120/ ERK pathway and restores BPA-impaired testicular toxicity

Bisphenol A (BPA) [2,2-bis(4-hydroxyphenyl) propane] has attracted increasing attention over the past few decades as an endocrine-disrupting chemicals that causes low testosterone levels. Linoleic acid (LA) is an essential fatty acid and GPR120 agonist. Herein, we are the first to report that LA induces the expression of GPR120 in mouse Leydig cells to directly promote testosterone production. In addition, we demonstrated that the activated GPR120 / ERK signaling pathway was involved in upregulating the expression of 3β-HSD and StAR for testosterone production by stimulation of LA. Interestingly, although BPA failed to affect GPR120 expression, LA restored the testosterone levels decreased by BPA in Leydig cells in vitro. Furthermore, the in vivo restoration of testosterone levels and testicular structure was also observed in BPA-impaired mice fed LA. As a result, the sperm functions of BPA-impaired mice returned to normal levels. At the same time, the damaged blood-testis barrier and infertility were also resolved by LA. Our study indicates a novel and safe strategy that utilizes LA to repair reproductive damage caused by low testosterone levels through activating the GPR120/ERK pathway in Leydig cells.

Prenatal Exposure to Bisphenol A, E, and S Induces Transgenerational Effects on Male Reproductive Functions in Mice

This study was performed to examine the transgenerational effects of bisphenol (BP) A analogs, BPE, and BPS on male reproductive functions using mice as a model. CD-1 mice (F0) were orally exposed to control treatment (corn oil), BPA, BPE, or BPS (0.5 or 50 µg/kg/day) from gestational day 7 (the presence of vaginal plug = 1) to birth. Mice from F1 and F2 offspring were used to generate F3 males. Prenatal exposure to BPA, BPE, and BPS decreased sperm counts and/or motility and disrupted the progression of germ cell development as morphometric analyses exhibited an abnormal distribution of the stages of spermatogenesis in F3 males. Dysregulated serum levels of estradiol-17β and testosterone, as well as expression of steroidogenic enzymes in F3 adult testis were also observed. In the neonatal testis, although apoptosis and DNA damage were not affected, mRNA levels of DNA methyltransferases, histone methyltransferases, and their associated factors were increased by BP exposure. Furthermore, BP exposure induced immunoreactive expression of DNMT3A in Sertoli cells, strengthened DNMT3B, and weakened H3K9me2 and H3K9me3 in germ cells of the neonatal testis, whereas DNMT1, H3K4me3, and H3K27ac were not affected. In adult testis, stage-specific DNMT3B was altered by BP exposure, although DNMT3A, H3K9me2, and H3K9me3 expression remained stable. These results suggest that prenatal exposure to BPA, BPE, and BPS induces transgenerational effects on male reproductive functions probably due to altered epigenetic modification following disruption of DNMTs and histone marks in the neonatal and/or adult testis.

Developmental Exposure to Tetrabromobisphenol A Has Minimal Impact on Male Rat Reproductive Health

The flame retardant and plasticizer, tetrabromobisphenol-A (TBBPA) has rapidly become a common component in the manufacture of circuit boards and plastics worldwide. It is also an analog of bisphenol A (BPA), an endocrine disrupting chemical identified by the Endocrine Society. As such, TBBPA needs to be investigated for similar potential human health risks. Using rats as a model, we exposed pregnant dams and their progeny to 0, 0.1, 25, or 250 mg TBBPA/kg of body weight until the offspring reached adulthood and assessed the first generation of males for any reproductive tract abnormalities. We found no differences in the morphology of testes, sperm, prostates, or secondary sex organs from post-natal day 21 through one-year of age. A delay in the time to preputial separation was found with the 250 mg/kg treatment. Also, minor differences of sperm count at one-year old with the 25 mg/kg treatment and expression levels of two steroidogenic pathway enzymes at either post-natal day 90 or one-year old in the 250 mg/kg treatment group were detected, but spermatogenesis was not disrupted. While these results may lead to the supposition that TBBPA is less harmful than its parent compound BPA, more studies need to be conducted to assess long-term exposure effects.

Paternal Exposure to Bisphenol-A Transgenerationally Impairs Testis Morphology, Germ Cell Associations, and Stemness Properties of Mouse Spermatogonial Stem Cells

Bisphenol-A (BPA) exposure in an adult male can affect the reproductive system, which may also adversely affect the next generation. However, there is a lack of comprehensive data on the BPA-induced disruption of the association and functional characteristics of the testicular germ cells, which the present study sought to investigate. Adult male mice were administered BPA doses by gavage for six consecutive weeks and allowed to breed, producing generations F1-F4. Testis samples from each generation were evaluated for several parameters, including abnormal structure, alterations in germ cell proportions, apoptosis, and loss of functional properties of spermatogonial stem cells (SSCs). We observed that at the lowest-observed-adverse-effect level (LOAEL) dose, the testicular abnormalities and alterations in seminiferous epithelium staging persisted in F0-F2 generations, although a reduced total spermatogonia count was found only in F0. However, abnormalities in the proportions of germ cells were observed until F2. Exposure of the male mice (F0) to BPA alters the morphology of the testis along with the association of germ cells and stemness properties of SSCs, with the effects persisting up to F2. Therefore, we conclude that BPA induces physiological and functional disruption in male germ cells, which may lead to reproductive health issues in the next generation.

Cdc14a has a role in spermatogenesis, sperm maturation and male fertility

Cdc14a is an evolutionarily conserved dual-specific protein phosphatase, and it plays different roles in different organisms. Cdc14a mutations in human have been reported to cause male infertility, while the specific role of Cdc14a in regulation of the male reproductive system remains elusive. In the present study, we established a knockout mouse model to study the function of Cdc14a in male reproductive system. Cdc14a^-/- male mice were subfertile and they could only produce very few offspring. The number of sperm was decreased, the sperm motility was impaired, and the proportion of sperm with abnormal morphology was elevated in Cdc14a^-/- mice. When we mated Cdc14a^-/- male mice with wild-type (WT) female mice, fertilized eggs could be found in female fallopian tubes, however, the majority of these embryos died during development. Some empty spaces were observed in seminiferous tubule of Cdc14a^-/- testes. Compared with WT male mice, the proportions of pachytene spermatocytes were increased and germ cells stained with γH2ax were decreased in Cdc14a^-/- male mice, indicating that knockout of Cdc14a inhibited meiotic initiation. Subsequently, we analyzed the expression levels of some substrate proteins of Cdc14a, including Cdc25a, Wee1, and PR-Set7, and compared those with WT testes, in which the expression levels of these proteins were significantly increased in Cdc14a^-/- testes. Our results revealed that Cdc14a^-/- male mice are highly subfertile, and Cdc14a is essential for normal spermatogenesis and sperm function.

Endocrine-disrupting chemicals and male reproductive health

BACKGROUND

A number of different types of endocrine-disrupting chemicals (EDCs) including bisphenol A, phthalates, pesticides, and other environmental chemicals have been shown to adversely impact upon male reproductive health. Understanding the potential effects of EDCs on male reproductive health may enable the development of novel treatments and early prevention of the effects of EDCs on male infertility and their potential long-term sequelae. This review critically evaluates the research performed in this area and explores potential harmful effects of EDCs in animals and humans, including the possibility of trans-generational transmission.

METHODS

A literature review was conducted using electronic databases using the following terms: 'endocrine disrupt*' OR 'endocrine disruptors' OR 'endocrine disruptor chemicals' OR 'EDC' AND 'sperm*' OR 'spermatozoa' OR 'spermatozoon' OR 'male reproductive health' OR' male fertility'.

MAIN FINDINGS

Several studies have shown that EDCs have a variety of pathophysiological effects. These include failure of spermatogenesis, embryonic development, the association with testicular cancer, and long-term metabolic effects.

CONCLUSIONS

Several studies observe correlations between chemical doses and at least one sperm parameter; however, such correlations are sometimes inconsistent between different studies. Mechanisms through which EDCs exert their pathophysiological effects have not yet been fully elucidated in human studies.

Zinc deficient diet increases the toxicity of bisphenol A in rat testis

Zinc (Zn) plays an important role in maintaining the process of spermatogenesis and reproductive health. Bisphenol A (BPA), an endocrine disrupting chemical is known to be a reproductive toxicant in different animal models. The present study was designed to study the effect of two of the utmost determinative factors (Zn deficient condition and influence of toxicant BPA) on germ cell growth and overall male reproductive health in the testis, epididymis, and sperm using (a) biochemical, (b) antioxidant, (c) cellular damage, (d) apoptosis, and (e) protein expression measurements. Rats were divided into Control (normal feed and water), BPA (100 mg/kg/d), zinc deficient diet (ZDD; fed with ZDD), and BPA + ZDD for 8 weeks. Body and organ weights, sperm motility and counts, and sperm head morphology were evaluated. The histology of testes, epididymides, and prostate was investigated. Testicular deoxyribonucleic acid (DNA) damage was evaluated by Halo and Comet assay, apoptosis of sperm and testes were quantified by TUNEL assay. Serum protein electrophoretic patterns and testicular protein expressions such as Nrf-2, catalase, PCNA, and Keap1 were analyzed by Western blot analysis. The results showed that BPA significantly increased the testicular, epididymal, and prostrate toxicity in dietary Zn deficient condition due to testicular hypozincemia, hypogonadism, increased cellular and DNA damage, apoptosis, as well as perturbations in protein expression.

Bisphenol A and Male Fertility: Myths and Realities

Bisphenol A (BPA) represents the main chemical monomer of epoxy resins and polycarbonate plastics. The environmental presence of BPA is widespread, and it can easily be absorbed by the human body through dietary and transdermal routes, so that more than 90% of the population in western countries display detectable BPA levels in the urine. As BPA is qualified as an endocrine disruptor, growing concern is rising for possible harmful effects on human health. This review critically discusses the available literature dealing with the possible impact of BPA on male fertility. In rodent models, the in vivo exposure to BPA negatively interfered with the regulation of spermatogenesis throughout the hypothalamic-pituitary-gonadal axis. Furthermore, in in vitro studies, BPA promoted mitochondrial dysfunction and oxidative/apoptotic damages in spermatozoa from different species, including humans. To date, the claimed clinical adverse effects on male fertility are largely based on the results from studies assessing the relationship between urinary BPA concentration and conventional semen parameters. These studies, however, produced controversial evidence due to heterogeneity in the extent of BPA exposure, type of population, and enrollment setting. Moreover, the cause-effect relationship cannot be established due to the cross-sectional design of the studies as well as the large spontaneous between- and within-subject variability of semen parameters. The best evidence of an adverse effect of BPA on male fertility would be provided by prospective studies on clinically relevant endpoints, including natural or medically assisted pregnancies among men either with different exposure degrees (occupational/environmental) or with different clinical conditions (fertile/subfertile).

Neuro-toxic and Reproductive Effects of BPA

Background:

Bisphenol A (BPA) is one of the highest volume chemicals produced worldwide. It has recognized activity as an endocrine-disrupting chemical and has suspected roles as a neurological and reproductive toxicant. It interferes in steroid signaling, induces oxidative stress, and affects gene expression epigenetically. Gestational, perinatal and neonatal exposures to BPA affect developmental processes, including brain development and gametogenesis, with consequences on brain functions, behavior, and fertility.

Methods:

This review critically analyzes recent findings on the neuro-toxic and reproductive effects of BPA (and its ana-logues), with focus on neuronal differentiation, synaptic plasticity, glia and microglia activity, cognitive functions, and the central and local control of reproduction.

Results:

BPA has potential human health hazard associated with gestational, peri- and neonatal exposure. Beginning with BPA’s disposition, this review summarizes recent findings on the neurotoxicity of BPA and its analogues, on neuronal dif-ferentiation, synaptic plasticity, neuro-inflammation, neuro-degeneration, and impairment of cognitive abilities. Furthermore, it reports the recent findings on the activity of BPA along the HPG axis, effects on the hypothalamic Gonadotropin Releas-ing Hormone (GnRH), and the associated effects on reproduction in both sexes and successful pregnancy.

Conclusion:

BPA and its analogues impair neuronal activity, HPG axis function, reproduction, and fertility. Contrasting re-sults have emerged in animal models and human. Thus, further studies are needed to better define their safety levels. This re-view offers new insights on these issues with the aim to find the “fil rouge”, if any, that characterize BPA’s mechanism of action with outcomes on neuronal function and reproduction.

High-Content Image-Based Single-Cell Phenotypic Analysis for the Testicular Toxicity Prediction Induced by Bisphenol A and Its Analogs Bisphenol S, Bisphenol AF, and Tetrabromobisphenol A in a Three-Dimensional Testicular Cell Co-culture Model

Emerging data indicate that structural analogs of bisphenol A (BPA) such as bisphenol S (BPS), tetrabromobisphenol A (TBBPA), and bisphenol AF (BPAF) have been introduced into the market as substitutes for BPA. Our previous study compared in vitro testicular toxicity using murine C18-4 spermatogonial cells and found that BPAF and TBBPA exhibited higher spermatogonial toxicities as compared with BPA and BPS. Recently, we developed a novel in vitro three-dimensional (3D) testicular cell co-culture model, enabling the classification of reproductive toxic substances. In this study, we applied the testicular cell co-culture model and employed a high-content image (HCA)-based single-cell analysis to further compare the testicular toxicities of BPA and its analogs. We also developed a machine learning (ML)-based HCA pipeline to examine the complex phenotypic changes associated with testicular toxicities. We found dose- and time-dependent changes in a wide spectrum of adverse endpoints, including nuclear morphology, DNA synthesis, DNA damage, and cytoskeletal structure in a single-cell-based analysis. The co-cultured testicular cells were more sensitive than the C18 spermatogonial cells in response to BPA and its analogs. Unlike conventional population-averaged assays, single-cell-based assays not only showed the levels of the averaged population, but also revealed changes in the sub-population. Machine learning-based phenotypic analysis revealed that treatment of BPA and its analogs resulted in the loss of spatial cytoskeletal structure, and an accumulation of M phase cells in a dose- and time-dependent manner. Furthermore, treatment of BPAF-induced multinucleated cells, which were associated with altered DNA damage response and impaired cellular F-actin filaments. Overall, we demonstrated a new and effective means to evaluate multiple toxic endpoints in the testicular co-culture model through the combination of ML and high-content image-based single-cell analysis. This approach provided an in-depth analysis of the multi-dimensional HCA data and provided an unbiased quantitative analysis of the phenotypes of interest.

Bisphenol A disturbs transcription of steroidogenic genes in ovary of rare minnow Gobiocypris rarus via the abnormal DNA and histone methylation

Increasing studies have established the toxic effects of BPA on development and reproduction in animals. In present study, we investigated epigenetic effects on the transcription of several ovarian steroidogenic genes in rare minnows Gobiocypris rarus after BPA exposure at 15 μgL^-1 for 21, 42 and 63 d. Results showed that short term BPA exposure (21 d) caused significant increase of both estradiol and testerone levels whereas long term exposure (63 d) led to significant decrease of them. The oocytes development was hindered after BPA exposure. BPA treatments for 21 and 42 d resulted in significant increase of genome DNA methylation in ovary while 63-d exposure caused marked decrease. The histone trimethylation levels (H3K4me3, H3K9me3 and H3K27me3) in the ovary were also disturbed by BPA. H3K9me3 was significantly decreased after 21 d whereas it was markedly increased after 42 and 63 d. The 42-d exposure caused significant decrease for H3K4me3. Meanwhile, 42- and 63-d BPA exposure led to significant decrease of H3K27me3. DNA methylation could involve in gene expression regulation of cyp17a1 and cyp19a1a after BPA exposure. After short (21 d) and long term (63 d) BPA exposure, the respective mRNA expression down-regulation and up-regulation of star, cyp11a1, and cyp17a1 were mediated by H3K9me3. This study suggests that epigenetic modulation including DNA and histone methylation could be responsible for the detrimental effects on ovary development upon BPA exposure in G. rarus. It is speculated that BPA exposures for short or long term duration could disturb the steroidogenesis in entirely different mechanisms.

Effects of starvation and refeeding cycles on spermatogenesis and sex steroids in the Nile tilapia Oreochromis niloticus

Food restriction is part of the life cycle of many fish species; however, nutritional deficiency may negatively influence gametogenesis and gonadal maturation. The aim of this study was to evaluate the effects of food restriction on the spermatogenesis of Nile tilapia. For this, adult males were submitted to starvation and refeeding cycles (alternating periods of starvation and feeding) for 7, 14, 21, and 28 days. After 7 days of starvation, glycaemic and lipid levels were significantly reduced, followed by reduction of plasma testosterone (T) and 11-ketotestosterone (11-KT). In addition, reduced proliferation of spermatogonia and increased apoptosis of spermatocytes, spermatids, and spermatozoa was observed in starvation groups. In the refeeding groups, the sex steroids and the proportion of germ cells had no significant alterations compared to the control group, except for spermatozoa. In this sense, the present study suggests that starvation after 7 days progressively reduces T and 11-TK, resulting in damage to the production of spermatogenic cells, while refeeding may delay spermatogenesis but does not lead to testicular impairment.

Bisphenols and Male Reproductive Health: From Toxicological Models to Therapeutic Hypotheses

Bisphenols, and in particular bisphenol A (BPA), have been widely used for the production of plastic manufacts in the last 50 years. Currently, BPA is present in a variety of daily use polycarbonate plastics and epoxy resins, and dietary ingestion is considered the main route of human exposure. Accordingly, BPA is the chemical pollutant with the widest exposure in humans, involving nearly 90% of general population, according to recent studies. Concerns about BPA effects on human health date back to 1930s, when severe impact on male sexual development was suggested. Now, the acknowledged biological effects of BPA are various. In regard to human fertility, BPA has been shown to disrupt hormone signaling even at low concentrations. Results from human epidemiological studies have reported BPA interference with follicle stimulating hormone, inhibin B, estradiol, testosterone levels, and sexual function in male subjects. Moreover, recent studies have reported an association between BPA levels and reduced sperm concentration, motility, normal morphology, sperm DNA damage, and altered epigenetic pattern, resulting in trans-generational legacy of BPA effects. In this review, the recognized effects of BPA on male reproductive health are described, from the most recent issues on experimental models to epidemiological data. In addition, the very recent interest about the use of nutraceutical remedies to counteract BPA effects are discussed.

Genetic and epigenetic alterations induced by bisphenol A exposure during different periods of spermatogenesis: from spermatozoa to the progeny

Exposure to bisphenol A (BPA) has been related to male reproductive disorders. Since this endocrine disruptor also displays genotoxic and epigenotoxic effects, it likely alters the spermatogenesis, a process in which both hormones and chromatin remodeling play crucial roles. The hypothesis of this work is that BPA impairs early embryo development by modifying the spermatic genetic and epigenetic information. Zebrafish males were exposed to 100 and 2000 μg/L BPA during early spermatogenesis and during the whole process. Genotoxic and epigenotoxic effects on spermatozoa (comet assay and immunocytochemistry) as well as progeny development (mortality, DNA repairing activity, apoptosis and epigenetic profile) were evaluated. Exposure to 100 µg/L BPA during mitosis slightly increased sperm chromatin fragmentation, enhancing DNA repairing activity in embryos. The rest of treatments promoted high levels of sperm DNA damage, triggering apoptosis in early embryo and severely impairing survival. Regarding epigenetics, histone acetylation (H3K9Ac and H3K27Ac) was similarly enhanced in spermatozoa and embryos from males exposed to all the treatments. Therefore, BPA male exposure jeopardizes embryonic survival and development due to the transmission of a paternal damaged genome and of a hyper-acetylated histone profile, both alterations depending on the dose of the toxicant and the temporal window of exposure.

The effects of long-term exposure to low doses of cadmium on the health of the next generation of mice

Cadmium (Cd) is an important toxic chemical due to its increasing levels in the environment and bioaccumulation in humans and animals. The present study was performed to evaluate the effects of long-term exposure to 1, 10, or 100 μg/L Cd in drinking water on the development, reproduction and neurotoxicity of offspring when administered to mice from parental puberty to postnatal 10 weeks in offspring. The development parameters measured in offspring included physical development, reflex ontogeny, body weight and body size. The reproductive indices measured consisted of anogenital distances (AGDs), estrous cycle, sperm quality, specific gene expression in Leydig or Sertoli cells, seminiferous epithelium cycle, sex hormone levels, histological morphology and apoptosis in testis or ovary, and the levels of oxidative stress. The determination of neurotoxicity included learning and memory ability, anxiety, and related serum indicators. In addition, blood lipid level, liver and kidney function were also determined by serum biochemical assays. The results showed that exposure to Cd in the present model had no adverse effects on development, but had some reproductive toxicity and neurotoxicity, including alteration of spermatogenic epithelial staging in testis and inducing anxiety in offspring. Furthermore, the levels of total protein, globulins, total bile acid and direct bilirubin were also significantly altered, especially in female offspring. The present study suggested that long-term exposure to low doses of Cd had adverse effects on the health of the next generation, and some harmful effects showed gender differences in offspring. The present study demonstrated that attention should be paid to Cd pollution in the environment, especially before pregnancy.

Understanding the molecular mechanisms of bisphenol A action in spermatozoa

Bisphenol A (BPA) is an endocrine-disrupting chemical that is capable of interfering with the normal function of the endocrine system in the body. Exposure to this chemical from BPA-containing materials and the environment is associated with deleterious health effects, including male reproductive abnormalities. A search of the literature demonstrated that BPA, as a toxicant, directly affects the cellular oxidative stress response machinery. Because of its hormone-like properties, it can also bind with specific receptors in target cells. Therefore, the tissue-specific effects of BPA mostly depend on its endocrine-disrupting capabilities and the expression of those particular receptors in target cells. Although studies have shown the possible mechanisms of BPA action in various cell types, a clear consensus has yet to be established. In this review, we summarize the mechanisms of BPA action in spermatozoa by compiling existing information in the literature.

Male exposure to bisphenol a impairs spermatogenesis and triggers histone hyperacetylation in zebrafish testes

Bisphenol A (BPA) is an endocrine disruptor whose ubiquitous presence in the environment has been related with impairment of male reproduction. BPA can cause both transcriptomic and epigenetic changes during spermatogenesis. To evaluate the potential effects of male exposure to BPA, adult zebrafish males were exposed during spermatogenesis to doses of 100 and 2000 μg/L, which were reported in contaminated water bodies and higher than those allowed for human consumption. Fertilization capacity and survival at hatching were analysed after mating with untreated females. Spermatogenic progress was analysed through a morphometrical study of testes and apoptosis was evaluated by TUNEL assay. Testicular gene expression was evaluated by RT-qPCR and epigenetics by using ELISA and immunocytochemistry. In vitro studies were performed to investigate the role of Gper. Chromatin fragmentation and the presence of transcripts were also evaluated in ejaculated sperm. Results on testes from males treated with the highest dose showed a significant decrease in spermatocytes, an increase in apoptosis, a downregulation of ccnb1 and sycp3, all of which point to an alteration of spermatogenesis and to meiotic arrest and an upregulation of gper1 and esrrga receptors. Additionally, BPA at 2000 μg/L caused missregulation of epigenetic remodelling enzymes transcripts in testes and promoted DNA hypermethylation and H3K27me3 demethylation. BPA also triggered an increase in histone acetyltransferase activity, which led to hyperacetylation of histones (H3K9ac, H3K14ac, H4K12ac). In vitro reversion of histone acetylation changes using a specific GPER antagonist, G-36, suggested this receptor as mediator of histone hyperacetylation. Males treated with the lower dose only showed an increase in some histone acetylation marks (H3K14ac, H4K12ac) but their progeny displayed very limited survival at hatching, revealing the deleterious effects of unbalanced paternal epigenetic information. Furthermore, the highest dose of BPA led to chromatin fragmentation, promoting direct reproductive effects, which are incompatible with embryo development.

Adverse effects of bisphenol A on Sertoli cell blood-testis barrier in rare minnow Gobiocypris rarus

Bisphenol A (BPA), an environmental contaminant, has been shown to disturb the dynamics of Sertoli cell blood-testis barrier (BTB) in mammal testis. However, the effects of BPA on Sertoli cell barrier (SC barrier) were little known in fish to date. To evaluate the potential mechanism of reproductive toxicity of BPA, we studied the damage of SC barrier using in vivo models. In this study, male adult rare minnow Gobiocypris rarus were exposed to 15 μg/L BPA for 7-35 days. Gonadal histology and the integrity of SC barrier were analyzed. Meanwhile, the expressions of SC barrier -associated proteins, tumor necrosis factor (TNFα) content, and the mRNA expressions of genes in the mitogen activated protein kinase (MAPK) pathway were detected. Histological analysis demonstrated 15 μg/L BPA promoted the infiltration of inflammatory cells in fish testes after 7-days exposure. The biotin tracer assay showed that 7-days BPA exposure increased permeability for spermatid cysts. In addition, the BPA treatment caused increased TNFα in testis, which was reportedly related to SC barrier impairment. The expressions of Occludin and β-Catenin protein were significantly decreased in the testes after 7- and 21-days exposure. BPA also altered the mRNA expressions of occludin, β-catenin, p38 MAPK and JNK. Therefore, the detrimental effects of BPA on reproduction of male fish may attribute to the disturbed expressions of SC junction proteins.

Water and soil pollution as determinant of water and food quality/contamination and its impact on male fertility

Over the past two decades, public health has focused on the identification of environmental chemical factors that are able to adversely affect hormonal function, known as endocrine disruptors (EDs). EDs mimic naturally occurring hormones like estrogens and androgens which can in turn interfere with the endocrine system. As a consequence, EDs affect human reproduction as well as post and pre-natal development. In fact, infants can be affected already at prenatal level due to maternal exposure to EDs. In particular, great attention has been given to those chemicals, or their metabolites, that have estrogenic properties or antagonistic effects on the activity of androgen or even inhibiting their production. These compounds have therefore the potential of interfering with important physiological processes, such as masculinization, morphological development of the urogenital system and secondary sexual traits. Animal and in vitro studies have supported the conclusion that endocrine-disrupting chemicals affect the hormone-dependent pathways responsible for male gonadal development, either through direct interaction with hormone receptors or via epigenetic and cell-cycle regulatory modes of action. In human populations, epidemiological studies have reported an overall decline of male fertility and an increased incidence of diseases or congenital malformations of the male reproductive system. The majority of studies point towards an association between exposure to EDs and male and/or female reproductive system disorders, such as infertility, endometriosis, breast cancer, testicular cancer, poor sperm quality and/or function. Despite promising discoveries, a causal relationship between the reproductive disorders and exposure to specific toxicants has yet to be established, due to the complexity of the clinical protocols used, the degree of occupational or environmental exposure, the determination of the variables measured and the sample size of the subjects examined. Despite the lack of consistency in the results of so many studies investigating endocrine-disrupting properties of many different classes of chemicals, the overall conclusion points toward a positive association between exposure to EDs and reproductive system. Future studies should focus on a uniform systems to examine human populations with regard to the exposure to specific EDs and the direct effect on the reproductive system.

Epigenetic Transgenerational Inheritance

Epigenetic information refers to heritable changes in gene expression that occur without modifications at the DNA sequence level. These changes are orchestrated by different epigenetic mechanisms such as DNA methylation, posttranslational modifications of histones, and the presence of noncoding RNAs. Epigenetic information regulates chromatin structure to confer cell-specific gene expression.The sperm epigenome is the result of three periods of global resetting during men's life. Germ cell epigenome reprogramming is designed to allow cell totipotency and to prevent the transmission of epimutations via spermatozoa. At the end of these reprogramming events, the sperm epigenome has a very specific epigenetic pattern that is a footprint of past reprogramming events and has an influence on embryo development.Several data demonstrate that not all regions of the epigenome are erased during the reprogramming periods, suggesting the transmission of epigenetic information from fathers to offspring via spermatozoa. Moreover, it is becoming increasingly clear that the sperm epigenome is sensitive to environmental factors during the process of gamete differentiation, suggesting the plasticity of the sperm epigenetic signature according to the circumstances of the individual's life.In this chapter, we provided strong evidences about the association between variations of the sperm epigenome and the exposure to environmental factors. Moreover, we will present data about how epigenetic mechanisms are candidates for transferring paternal environmental information to offspring.

Protective effects of selenium and nano-selenium on bisphenol-induced reproductive toxicity in male rats

Bisphenol A (BPA) is a widespread compound associated with the manufacture of many consumer products. The BPA-induced reproductive toxicity was reported to be mainly attributed to oxidative stress. However, the role of antioxidants usage to decrease the injurious effects of BPA, on male reproductive functions, remains to unveil. The present research is established to evaluate the role of selenium (Se) and its nano form (NSe) as protective agents to alleviate BPA-induced testicular toxicity. Ninety mature albino male rats were assigned into six equal groups: negative control; orally BPA 150 mg/kg; Se 3 mg/kg; NSe 2 mg/kg; both BPA 150 mg/kg and Se 3 mg/kg; and BPA 150 mg/kg + NSe 2 mg/kg. The experiment lasted for 70 consecutive days, and then serum was collected for estimation of prostatic acid phosphatase. Testicular tissues were subjected to measurement of antioxidant status, lipid peroxidation, DNA damage, and expression of some apoptotic genes. Our results reported that BPA-induced marked testicular damage evidenced by significant elevations in serum prostatic acid phosphatase activity, malondialdehyde levels, a decrease in testicular catalase activity and reduced glutathione level. Moreover, marked DNA internucleosomal fragmentation pattern as well as upregulation of cyclooxygenase-2 and estrogen receptor-2 NSe genes were detected. Coadministration of Se and NSe attenuated the reproductive toxicity induced by BPA via improvement of the antioxidant activity, genetic changes, and restoration of testicular tissue nearly as control one. These results indicated that both Se and NSe forms could be used as reproductive protective agents against the detrimental effect induced by BPA. However, the NSe surpassed the selenium in modulating the DNA laddering, and the studied gene expression levels, and offered a potent reproductive protection.

Aqueous extract of Eruca Sativa protects human spermatozoa from mitochondrial failure due to bisphenol A exposure

Medicinal plants are suggested to counteract health disorders from chemical pollutants. Here we explored the possible ameliorative effect of Eruca sativa aqueous extract (ESAE) on in vitro acute functional disturbance induced by Bisphenol A (BPA), a disruptor model in human spermatozoa. Phytochemical screening, high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) analysis and 2,2'-azino-bis [3-ethylbenzthiazoline-6-sulphonic acid]/α,α-diphenyl-β-picrylhydrazyl (ABTS/DPPH) tests disclosed antioxidant properties of ESAE, ascribed to polyphenols and flavonoids. The toxicological impact of BPA on sperm viability and motility was detected for concentration greater than 10 μM but co-incubation with ESAE recovered sperm function at low concentration (15.62 μg/ml). BPA reduced mitochondrial membrane potential (ΔΨm), with no impact on plasma membrane potential (ΔΨp). At low doses, ESAE recovered ΔΨm but higher doses were associated with impairment of both ΔΨm and ΔΨp. ESAE protects towards in vitro BPA-mediated toxicity and its possible use as complementary treatment for male reproductive disorders is critically discussed.

Decreased Capacity for Sperm Production Induced by Perinatal Bisphenol A Exposure Is Associated with an Increased Inflammatory Response in the Offspring of C57BL/6 Male Mice

Many previous studies have indicated the adverse effects of bisphenol A (BPA) on sperm production and quality; however, the mechanisms underlying BPA male reproductive toxicity have yet to be elucidated. The main purpose of this study was to investigate the effect of perinatal exposure to BPA on the spermatogenic capacity of male offspring, and to explore the possible influence of inflammatory responses in BPA reproductive toxicity. Twenty-one pregnant C57BL/6mice were randomly divided into three groups: a control group, a group receiving 0.2 μg/mL (LBPA), and a group receiving 2 μg/mL of BPA (HBPA), all via drinking water from gestational day 6 to the end of lactation. After weaning, one male mouse was randomly selected from each group (n = 7/group); these three mice were fed a normal diet and drinking water for 1 month. Levels of serum testosterone (T) and tumor necrosis factor (TNF)-α were then measured in all mice. Sperm count and the proportion of sperm malformation were also determined. The levels of Toll-like receptor 4 (TLR4), nuclear factor (NF)-κB, and aryl hydrocarbon receptor (AhR) protein expression in the testis tissue were determined. Analysis showed that the proportion of sperm malformation increased in the LBPA and HBPA groups (p < 0.05). Sperm count significantly decreased only in the HBPA group (p < 0.05), while the levels of serum TNF-α increased in the LBPA and HBPA groups (p < 0.05). Levels of serum T decreased significantly in the HBPA group, compared with controls (p < 0.05). Levels of TLR4 and NF-κB protein expression in the testis were significantly higher in the LBPA and HBPA groups (p < 0.05 or p < 0.01), while AhR protein expression was higher and seminiferous tubules in the testis showed more damage in the HBPA group compared to controls (p < 0.05 and p < 0.01, respectively). Our results showed that perinatal exposure to low or high doses of BPA decreased the capacity for spermatogenesis in male offspring, which may be associated with an inflammatory response activated by the TLR4/ NF-κB and AhR signaling pathways in the testis.

Bisphenol A: Food Exposure and Impact on Human Health

Bisphenol A (BPA) is an industrial compound used extensively to produce synthetic polymers, such as epoxy resins, which are incorporated into the inner coating of metal cans, and also to manufacture polycarbonates with applications in bottles, including bottles of water. Several studies have reported on the transfer of this compound to food. Regarding human exposure to BPA, food intake can be considered the most serious among all the routes, not only because it potentially reaches more people in different age groups (including infants, an especially vulnerable group), but also because it inadvertently occurs over long time periods. BPA is considered an endocrine disruptor and several studies have proposed a relationship between exposure to BPA and the appearance of adverse health effects, such as cancer, infertility, diabetes, and obesity, among others. In 2015 however, the European Food Safety Authority concluded in its last scientific opinion that this compound does not pose any risk to the exposed population's health. Therefore, the EU regards BPA as an authorized product to be used as food contact material. Although BPA intake through food is apparently below the set limits, research into BPA and its potential negative effects is still ongoing. This review contains the most recent in vitro and in vivo studies on BPA toxicity and its harmful effects on health, and it intends to address human exposure to BPA, namely through dietary exposure and its impact on human health.

Alteration in apoptotic rate of testicular cells and sperms following administration of Bisphenol A (BPA) in Wistar albino rats

The aim of the study was to evaluate the effect of Bisphenol A [BPA] widely used as a plasticizer in the formation of polycarbonate plastics and epoxy resins, exposure causing alteration in apoptosis rate, and protective effect of Vitamin E when supplemented with BPA orally. Adult male Wistar albino rats aged 3 months were randomly divided into seven groups: control (olive oil treated) BPA-treated (dose 5, 50,100 μg/100gmBW) and Vitamin E intervention group (dose 5, 50, 100 μg/100gmBW BPA+ Vitamin E dose 4 mg/100gmBW). Animals were sacrificed 3 months later, and blood and tissue samples were collected. Apoptotic changes were analyzed in epididymal spermatozoa and testis tissue by binding of annexin V apoptotic biomarker. A significant decline in the weight of testis, testosterone level, and sperm count was observed. Histopathological and apoptotic changes were observed in testis tissue. In epididymal sperms, the early apoptotic cells were observed by staining of annexin V-conjugated FITC and PI green fluorescence in spermatozoa head which indicated the damage of membrane and late apoptotic cells. These changes reduced significantly in Vitamin E-treated groups though were not found to be comparable to control animals. All these changes were attributed to disrupted spermatogenesis that would interfere with sperm formation. Thus, the study infers that BPA affects the apoptosis process in the testis and epididymal sperm that would interfere with its function and contribute to infertility, whereas Vitamin E-supplemented dose has a protective effect towards these changes, indicating its role in improving male fertility.

Estrogenic Mechanisms and Cardiac Responses Following Early Life Exposure to Bisphenol A (BPA) and Its Metabolite 4-Methyl-2,4-bis( p-hydroxyphenyl)pent-1-ene (MBP) in Zebrafish

Environmental exposure to Bisphenol A (BPA) has been associated with a range of adverse health effects, including on the cardiovascular system in humans. Lack of agreement on its mechanism(s) of action likely stem from comparisons between in vivo and in vitro test systems and potential multiple effects pathways. In rodents, in vivo, metabolic activation of BPA produces 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), which is reported to be up to 1000 times more potent as an estrogen than BPA. We investigated the estrogenic effects and estrogen receptor signaling pathway(s) of BPA and MBP following early life exposure using a transgenic, estrogen responsive (ERE-TG) zebrafish and a targeted morpholino approach to knockdown the three fish estrogen receptor (ER) subtypes. The functional consequences of BPA exposure on the cardiovascular system of zebrafish larvae were also examined. The heart atrioventricular valves and the bulbus arteriosus were primary target tissues for both BPA and MBP in the ERE-TG zebrafish, and MBP was approximately 1000-fold more potent than BPA as an estrogen in these tissues. Estrogen receptor knockdown with morpholinos indicated that the estrogenic responses in the heart for both BPA and MBP were mediated via an estrogen receptor 1 (esr1) dependent pathway. At the highest BPA concentration tested (2500 μg/L), alterations in the atrial:ventricular beat ratio indicated a functional impact on the heart of 5 days post fertilization (dpf) larvae, and there was also a significantly reduced heart rate in these larvae at 14 dpf. Our findings indicate that some of the reported adverse effects on heart function associated with BPA exposure (in mammals) may act through an estrogenic mechanism, but that fish are unlikely to be susceptible to adverse effects on heart development for environmentally relevant exposures.

Effects of maternal or paternal bisphenol A exposure on offspring behavior

Bisphenol A (BPA) is an endocrine disrupting chemical used in the production of polycarbonate plastics and resins. Exposure to BPA during gestation has been proposed as a risk factor for the development of neurobehavioral disorders, such as autism spectrum disorder. To address the behavioral impact of developmental exposure to BPA, we tested offspring of mice exposed to a daily low dose of BPA during pregnancy. We also asked if preconception exposure of the sire affected behaviors in offspring. Sires that consumed BPA for 50days prior to mating weighed less than controls, but no effects on any reproductive measures were noted. Juvenile offspring exposed to BPA maternally, but not paternally, spent less time in the open arms of the elevated plus maze than controls, indicating increased anxiety-like behavior. However, neither parental exposure group differed significantly from controls in the social recognition task. We also assessed the behaviors of maternally exposed offspring in two novel tasks: ultrasonic vocalizations (USVs) in pups and operant reversal learning in adults. Maternal BPA exposure increased the duration and median frequency of USVs emitted by pups during maternal separation. In the reversal learning task, females responded more accurately and earned more rewards than males. Additionally, control females received more rewards than BPA females during the acquisition phase of the task. These are among the first studies conducted to ask if BPA exposure via the sire affects offspring behavior and the first study to report effects of gestational BPA exposure on pup USVs and adult operant responding.

Protective effect of Lespedeza cuneata ethanol extract on Bisphenol A-induced testicular dysfunction in vivo and in vitro

PURPOSE

Bisphenol A (BPA) has been regarded as a possible risk factor for reproductive health. We examined potential reproductive health benefits of Lespedeza cuneata ethanol extract (LCE). Previously, Lespedeza cuneata showed many therapeutic effects. However, the protective effect of LCE on BPA-induced testicular dysfunction and its mechanisms have not been precisely studied.

METHODS

Mice were randomly divided into six groups (n = 7). Sperm counts and motility were measured by light microscope. Testosterone, total cholesterol, triglycerides, HDL, LDL-cholesterol, glucose, free fatty acids, hs-CRP, Angiotensinogen, Angiotensin II, GOT, GPT, TBARS, GSH, CAT, and SOD1 were measured in mouse serum. The potential protective effects of the LCE on mouse sertoli cells were evaluated.

RESULTS

Oral administration of LCE in BPA-exposed male mice restored testis weight, sperm count, motility, and testosterone levels by inhibiting markers in serum. In addition, treatment with LCE in BPA-treated TM4 sertoli cells recovered cell viability by attenuating Bax expression and activating caspase 3 and PARP.

CONCLUSIONS

These results indicate that LCE prevented BPA-induced testicular dysfunction and cell viability in BPA-treated TM4 sertoli cells. Our study also suggests that LCE has the potential to protect male reproductive health.

Acute effect of bisphenol A: Signaling pathways on calcium influx in immature rat testes

We investigated the acute effect of low concentrations of BPA on calcium influx and the mechanism of action of BPA in this rapid response in the rat testis. BPA increased calcium influx at 1 pM and 1 nM at 300 s of incubation, in a similar manner to that of estradiol. At 1 pM, BPA stimulated calcium influx independently of classical estrogen receptors, consistent with a G-protein coupled receptor. This effect also involves the modulation of ionic channels, such as K⁺, TRPV1 and Cl^- channels. Furthermore, BPA is able to modulate calcium from intracellular storages by inhibiting SERCA and activating IP₃ receptor/Ca²⁺ channels at the endoplasmic reticulum and activate kinase proteins, such as PKA and PKC. The rapid responses of BPA on calcium influx could, in turn, trigger a cross talk by MEK and p38^MAPK activation and also mediate genomic responses.

Bisphenol A and di(2-ethylhexyl) phthalate exert divergent effects on apoptosis and the Wnt/β-catenin pathway in zebrafish embryos: A possible mechanism of endocrine disrupting chemical action

Polyethylene terephthalate (PET) and polycarbonate (PC) are the most commonly used plastics in water bottles. Di(2-ethylhexyl) phthalate (DEHP) is used as a plasticizer in PET plastics, and bisphenol A (BPA) is used to produce PC. Both DEHP and BPA are known for their potential endocrine disrupting effects. The Wnt/β-catenin signaling pathway has important roles in cell proliferation, cell specification and cell fate determination during embryonic development. Recent reports suggest a link between the Wnt/β-catenin signaling pathway and apoptosis. The aim of this study was to investigate the relation between Wnt/β-catenin signaling and apoptosis in the case of BPA and DEHP exposure in zebrafish embryos. Accordingly, in vivo cell death was assessed using acridine orange staining, and reverse transcription polymerase chain reaction was used to determine the expressions of wnt3a, gsk3β and ccnd1. Proliferative cell nuclear antigen, β-catenin and Wnt3a expressions were determined immunohistochemically. Vitellogenin levels were determined using Enzyme Linked ImmunoSorbent Assay (ELISA). Increased vitellogenin levels, apoptosis, and wnt3a and gsk3β expressions were observed in BPA-exposed zebrafish embryos. Increased apoptosis in the BPA-exposed embryos may be due to the pro-apoptotic changes induced by Wnt3a, whereas DEHP might be suggested to have a minor effect as Wnt3a expression; vitellogenin levels and apoptosis did not increase significantly following exposure to DEHP.

Interaction between Y chromosome haplogroup O3* and 4-n-octylphenol exposure reduces the susceptibility to spermatogenic impairment in Han Chinese

Certain genetic background (mainly Y chromosome haplogroups, Y-hg) may modify the susceptibility of certain environmental exposure to some diseases. Compared with respective main effects of genetic background or environmental exposure, interactions between them reflect more realistic combined effects on the susceptibility to a disease. To identify the interactions on spermatogenic impairment, we performed Y chromosome haplotyping and measurement of 9 urinary phenols concentrations in 774 infertile males and 520 healthy controls in a Han Chinese population, and likelihood ratio tests were used to examine the interactions between Y-hgs and phenols. Originally, we observed that Y-hg C and Y-hg F^* might modify the susceptibility to male infertility with urinary 4-n-octylphenol (4-n-OP) level (P_inter = 0.005 and 0.019, respectively). Subsequently, based on our results, two panels were tested to identify the possible protective sub-branches of Y-hg F^* to 4-n-OP exposure, and Y-hg O3^* was uncovered to interact with 4-n-OP (P_inter = 0.019). In conclusion, while 4-n-OP shows an adverse effect on spermatogenesis, Y-hg O3^* makes individuals more adaptive to such an effect for maintaining basic reproductive capacity.

Neuroendocrine disruption in animal models due to exposure to bisphenol A analogues

Animal and human studies provide evidence that exposure to the endocrine disrupting chemical (EDC), bisphenol A (BPA), can lead to neurobehavioral disorders. Consequently, there is an impetus to identify safer alternatives to BPA. Three bisphenol compounds proposed as potential safer alternatives to BPA are bisphenol S (BPS), bisphenol F (BPF), and bisphenol AF (BPAF). However, it is not clear whether these other compounds are safer in terms of inducing less endocrine disrupting effects in animals and humans who are now increasingly coming into contact with these BPA-substitutes. In the past few years, several animal studies have shown exposure to these other bisphenols induce similar neurobehavioral disruption as BPA. We will explore in this review article the current studies suggesting these other bisphenols result in neuroendocrine disruptions that may be estrogen receptor-dependent. Current work may aide in designing future studies to test further whether these BPA-substitutes can act as neuroendocrine disruptors.

Bisphenol A Affects on the Functional Properties and Proteome of Testicular Germ Cells and Spermatogonial Stem Cells in vitro Culture Model

The endocrine disruptor bisphenol A (BPA) is well known for its adverse effect on male fertility. Growing evidence suggests that BPA may interact with testicular germ cells and cause infertility as a result of its estrogenic activity. Objective of current in vitro study was to investigate the proliferation, survivability and stemness properties of mouse testicular germ cells exposed to BPA, and to evaluate possible expression of cellular proteome. Our results showed that germ cell viability and proliferation were not affected by low concentrations (0.01, 0.1, 1, and 10 µM) although significant reduction observed at 100 µM BPA. Germ cell self-renewal and differentiation related marker proteins expression found unchanged at those concentrations. When BPA-exposed germ cells were transplanted into recipient testes, we observed fewer colonies at higher concentrations (10 and 100 µM). Additionally, a significant frequency of recombination failure during meiosis was observed in 10 µM BPA-exposed germ cell transplanted recipient. Moreover, experiment on continuous BPA-exposed and 100 µM BPA-recovered germ cells suggested that spermatogonial stem cells are more potential to survive in adverse environment. Finally, scrutinizing differentially expressed cellular proteins resulted from our proteomic analysis, we conclude that BPA exposure might be associated with several health risks and infertility.

Bisphenol A induced apoptosis and transcriptome differences of spermatogonial stem cells in vitro

Bisphenol A (BPA) is widely used as an industrial plasticizer, which is also an endocrine disruptor and considered to have adverse effects on reproduction. In male mammals, the long-term production of billions of spermatozoa relies on the regulated proliferation and differentiation of spermatogonial stem cells (SSCs). However, little is known about the effects of BPA on the viability of SSCs. To investigate the influence of BPA exposure on SSCs in vitro, we isolated SSCs from mouse and successfully established in vitro propagation of SSCs. After BPA treatment, we found that BPA reduced the viability of SSCs and induced SSC apoptosis. For revealing the transcriptome differences of the BPA-treated SSCs, we performed high-throughput RNA sequencing and found that 860 genes were differentially expressed among 18,272 observed genes. The gene ontology (GO) terms, regulation of programmed cell death and apoptotic process, were enriched in the differentially expressed genes (DEGs). Among the cluster of DEGs associated with the kyoto encyclopedia of genes and genomes (KEGG) apoptosis pathway, activating transcription factor 4 (Atf4) and DNA damage inducible transcript 3 (Ddit3) genes were significantly up-regulated in BPA-treated SSCs, which were proved by qPCR. Taken together, these findings suggest that BPA can increase the mRNA expression of pro-apoptosis genes and reduce the viability of SSCs by inducing apoptosis.

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

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

Endocrine-disrupting chemicals-Mechanisms of action on male reproductive system

Endocrine-disrupting chemicals (EDCs) are exogenous compounds that can cause disturbances in the endocrine system and have multiple harmful effects on health by targeting different organs and systems in the human body. Mass industrial production and widespread use of EDCs have resulted in worldwide contamination. Accumulating evidence suggest that human exposure to EDCs is related to the impairment of male reproductive function and can interrupt other hormonally regulated metabolic processes, particularly if exposure occurs during early development. Investigation of studies absent in previous reviews and meta-analysis of adverse effects of EDCs on functioning of the male reproductive system is the core of this work. Four main modes of action of EDCs on male fertility have been summarized in this review. First, studies describing estrogen- pathway disturbing chemicals are investigated. Second, androgen-signaling pathway alterations and influence on androgen sensitive tissues are examined. Third, evaluation of steroidogenesis dysfunction is discussed by focusing on the steroid hormone biosynthesis pathway, which is targeted by EDCs. Last, the reportedly destructive role of reactive oxygen species (ROS) on sperm function is discussed. Spermatogenesis is a remarkably complex process, hence multiple studies point out various dysfunctions depending on the development state at which the exposure occurred. Collected data show the need to account for critical windows of exposure such as fetal, perinatal and pubertal periods as well as effects of mixtures of several compounds in future research.

Gestational Exposure to Bisphenol A Affects the Function and Proteome Profile of F1 Spermatozoa in Adult Mice

BACKGROUND

Maternal exposure to the endocrine disruptor bisphenol A (BPA) has been linked to offspring reproductive abnormalities. However, exactly how BPA affects offspring fertility remains poorly understood.

OBJECTIVES

The aim of the present study was to evaluate the effects of gestational BPA exposure on sperm function, fertility, and proteome profile of F1 spermatozoa in adult mice.

METHODS

Pregnant CD-1 mice (F0) were gavaged with BPA at three different doses (50 μg/kg bw/day, 5 mg/kg bw/day, and 50 mg/kg bw/day) on embryonic days 7 to 14. We investigated the function, fertility, and related processes of F1 spermatozoa at postnatal day 120. We also evaluated protein profiles of F1 spermatozoa to monitor their functional affiliation to disease.

RESULTS

BPA inhibited sperm count, motility parameters, and intracellular ATP levels in a dose-dependent manner. These effects appeared to be caused by reduced numbers of stage VIII seminiferous epithelial cells in testis and decreased protein kinase A (PKA) activity and tyrosine phosphorylation in spermatozoa. We also found that BPA compromised average litter size. Proteins differentially expressed in spermatozoa from BPA treatment groups are known to play a critical role in ATP generation, oxidative stress response, fertility, and in the pathogenesis of several diseases.

CONCLUSIONS

Our study provides mechanistic support for the hypothesis that gestational exposure to BPA alters sperm function and fertility via down-regulation of tyrosine phosphorylation through a PKA-dependent mechanism. In addition, we anticipate that the BPA-induced changes in the sperm proteome might be partly responsible for the observed effects in spermatozoa. Citation: Rahman MS, Kwon WS, Karmakar PC, Yoon SJ, Ryu BY, Pang MG. 2017. Gestational exposure to bisphenol-A affects the function and proteome profile of F1 spermatozoa in adult mice. Environ Health Perspect 125:238-245; http://dx.doi.org/10.1289/EHP378.

High-Content Analysis Provides Mechanistic Insights into the Testicular Toxicity of Bisphenol A and Selected Analogues in Mouse Spermatogonial Cells

Bisphenol A (BPA), an endocrine-disrupting compound, was found to be a testicular toxicant in animal models. Bisphenol S (BPS), bisphenol AF (BPAF), and tetrabromobisphenol A (TBBPA) were recently introduced to the market as alternatives to BPA. However, toxicological data of these compounds in the male reproductive system are still limited so far. This study developed and validated an automated multi-parametric high-content analysis (HCA) using the C18-4 spermatogonial cell line as a model. We applied these validated HCA, including nuclear morphology, DNA content, cell cycle progression, DNA synthesis, cytoskeleton integrity, and DNA damage responses, to characterize and compare the testicular toxicities of BPA and 3 selected commercial available BPA analogues, BPS, BPAF, and TBBPA. HCA revealed BPAF and TBBPA exhibited higher spermatogonial toxicities as compared with BPA and BPS, including dose- and time-dependent alterations in nuclear morphology, cell cycle, DNA damage responses, and perturbation of the cytoskeleton. Our results demonstrated that this specific culture model together with HCA can be utilized for quantitative screening and discriminating of chemical-specific testicular toxicity in spermatogonial cells. It also provides a fast and cost-effective approach for the identification of environmental chemicals that could have detrimental effects on reproduction.