Smart-seq2 Technology Reveals a Novel Mechanism That Zearalenone Inhibits the In Vitro Maturation of Ovine Oocytes by Influencing TNFAIP6 Expression

Zearalenone (ZEN), a non-steroidal estrogenic fungal toxin widely present in forage, food, and their ingredients, poses a serious threat to animal and human reproductive health. ZEN also threatens ovine, a major source of human food and breeding stock. However, the mechanisms underlying the impact of ZEN on the in vitro maturation (IVM) of ovine oocytes remain unclear. This study aimed to elucidate these mechanisms using the Smart-seq2 technology. A total of 146 differentially expressed genes were obtained, using Smart-seq2, from sheep oocytes cultured in vitro after ZEN treatment. ZEN treatment inhibited RUNX2 and SPP1 expression in the PI3K signaling pathway, leading to the downregulation of THBS1 and ultimately the downregulation of TNFAIP6; ZEN can also decrease TNFAIP6 by reducing PTPRC and ITGAM. Both inhibit in vitro maturation of ovine oocytes and proliferation of cumulus cells by downregulating TNFAIP6. These findings provide data and a theoretical basis for elucidating ZEN's toxicity mechanisms, screening therapeutic drugs, and reducing ZEN-related losses in the ovine industry.

Bisphenol-A analogs induce lower urinary tract dysfunction in male mice

Bisphenol-A (BPA), an estrogenic endocrine disrupting chemical, significantly impacts numerous diseases and abnormalities in mammals. Estrogens are known to play an important role in the biology of the prostate; however, little is known about the role of bisphenols in the etiology of prostate pathologies, including benign prostate hyperplasia (BPH) and associated lower urinary tract dysfunction (LUTD). Bisphenol-F (BPF) and bisphenol-S (BPS) are analogs often used as substitutes for BPA; they are both reported to have in vitro and in vivo estrogenic effects similar to or more potent than BPA. The objective of this study was to assess the role of these bisphenols in the development of LUTD in adult male mice. In adult mice exposed to BPA, BPS or BPF, we examined urinary tract histopathology and physiological events associated with urinary dysfunction. Mice treated with bisphenols displayed increased bladder (p < 0.005) and prostate (p < 0.0001) mass, and there was an increased number of prostatic ducts in the prostatic urethra (p < 0.05) and decreased size of the urethra lumen (p < 0.05) compared to negative controls. After two months of bisphenol exposure, mice displayed notable differences in cystometric tracings compared to controls, consistent with LUTD. Treatment of male mice with all bisphenols also induced voiding dysfunction manifested by detrusor instability and histologic changes in the prostatic urethra of male rodents, consistent with LUTD. Our results implicate BPA and its replacements in the development and progression LUTD in mice and provide insights into the development and progression of BPH/LUTS in men.

Association between urinary bisphenol A concentrations and semen quality: a meta-analytic study

Although preclinical research has revealed disrupting effects on male reproductive functions of bisphenol A (BPA), as yet clinical studies have led to inconsistent results. The present meta‑analysis aims to establish the existence and the extent of the association between BPA exposure and semen quality. A thorough search of PubMed, Scopus and Web of Science databases was carried out. Only studies reporting data from multivariable linear regression analyses (β-coefficients with 95% CI), assessing the association between urinary levels of BPA and standard semen parameters were included. Nine studies provided information about an overall sample of 2,399 men. Only the negative association between urinary BPA levels and sperm motility reached statistical significance (pooled β-coefficient = -0.82; 95% CI: -1.51 to -0.12, p = 0.02; P_{for heterogeneity} = 0.1, I² = 42.9%). Yet, such a significance was lost after data adjustment for publication bias, as well as at the sensitivity analysis, when each of the two studies that contributed most to the overall estimate was excluded. In conclusion, the overall estimates of data produced by clinical studies point to a clinically negligible, if any, association between urinary BPA concentrations and semen quality. Further studies in workers at high risk of occupational exposure are warranted to corroborate the herein revealed weak correlation with a worse sperm motility.

Effects of Bacillus subtilis ZJ-2019-1 on Zearalenone Toxicosis in Female Gilts

The purpose of this research was to investigate the toxicity of zearalenone (ZEN) on the growth performance, genital organs, serum hormones, biomarkers, and histopathological changes of female gilts and to evaluate the efficacy of Bacillus subtilis ZJ-2019-1 in alleviating ZEN toxicosis in gilts. Twenty-four female gilts were randomly allocated to four groups with six replicates per group and one gilt per replicate, fed on four feeds prepared previously, which were basic diet (control group, C group), ZEN diet (Z group), Zlb diet (Zlb group) containing B. subtilis ZJ-2019-1 in liquid form, and Zdb diet (Zdb group) containing B. subtilis ZJ-2019-1 in dehydrated form. The results showed that the vulva size and relative weight of reproductive organs had no significant difference in the control group, Zlb group, and Zdb group, but were significantly lower than in the Z group (p < 0.05); the relative weight of the liver was lower in the C group, Zlb group, and Zbd group than in the Z group (0.05 < p < 0.1). The concentration of serum glutamate dehydrogenase (GLDH) was lower, but follicle-stimulating hormone (FSH) was higher in the Z group, Zlb group, and Zdb group than in the Z group (0.05 < p < 0.1). Additionally, serum luteinizing hormone (LH) concentration had no significant difference in the C group, Zlb group, and Zdb group but was significantly lower than in the Z group (p < 0.05); estradiol (E2) was significantly lower in the Zlb group and Zdb group than that in C group, but significantly higher than that in Z group (p < 0.05); PRL was significantly higher in the Zlb group and Zdb group than in the C group, but was significantly lower than in Z group (p < 0.05). ZEN and its reduced metabolites were measured in biological samples after enzymatic hydrolysis of the conjugated forms. The concentration of serum ZEN and its metabolite, α-zeralenol (α-ZOL), had no significant difference in Zlb, Zdb, and control groups but was significantly lower than in the Z group (p < 0.05); urine ZEN and its metabolites, α-ZOL and β-zeralenol (β-ZOL), had no significant difference in Zlb, Zdb, and control groups but was significantly lower than in the Z group (p < 0.05). Cell damages were observed in the liver, uterus, and ovary of gilts in the Z group and alleviated in Zlb and Zdb groups, but the loss of oocytes was irreversible in the ovary. The ZEN-contaminated diet caused serious changes in female hormones and brought harm to the livers and reproductive organs, but B. subtilis ZJ-2019-1 could naturally remove the ZEN significantly, which ameliorated the reproductive impairment in gilts caused by ZEN. The addition of B. subtilis ZJ-2019-1 to ZEN-contaminated feeds could ameliorate the toxic effects effectively, regardless of liquid or dry culture. Therefore, the B. subtilis ZJ-2019-1 strain has great potential industrial applications.

Bisphenol A affects the pulse rate of Lumbriculus variegatus via an estrogenic mechanism

Invertebrates are recognized as important species in endocrine disrupting chemical (EDC) testing. However, it is poorly understood whether the effects of EDCs in invertebrates are mediated by hormonal mechanisms. Previously, we showed that bisphenol A (BPA) affected the physiology of the freshwater oligochaete Lumbriculus variegatus. In the present study, we examined the mechanism of the impact of BPA on L. variegatus, using pulse rate of the dorsal blood vessel (DBV) as an endpoint. Both long term and acute exposures to BPA increased the pulsing rate of DBV. The former had a distinct inverted-U dose response relationship with a most efficacious dose of 10^-9 M, which increased the pulse rate from 8.97 to 10.9 beats/min. The effects of BPA were mimicked by the synthetic estrogen ethinylestradiol with a most efficacious dose of 10^-12 M. Interestingly E₂ had no effect on pulsing rate, either acute or long term. The sensitivity of L. variegatus to estrogens were exquisite, with detectable effects at 10^-14 to 10^-10 M range. Both the long term and acute effects of BPA were partially or fully blocked by various vertebrate estrogen receptor (ER) antagonists, including ICI 182,780, MPP and G15. Our results suggest that the impact of BPA on pulsing rate of L. variegatus is likely mediated by an estrogenic mechanism instead of general toxicity. The exceptionally high sensitivity of L. variegatus to some estrogens makes it a possible tool for estrogenic EDC screening.

Chitosan nanoparticles alleviated endocrine disruption, oxidative damage, and genotoxicity of Bisphenol-A- intoxicated female African catfish

Bisphenol-A (BPA) is widely used in production of plastic products. It can reach the ecosystems affecting aquatic organisms most likely fishes. The purpose of this study was to study the toxic effects of BPA on the biochemical variables and oxidative stress in female African catfish, Clarias gariepinus and to estimate the protective role of chitosan nanoparticles (CSNPs) against BPA toxicity. Five groups in triplicates of fish were divided as follows: group I was control, group II was treated with CSNPs (0.66 ml/L), group III was exposed to BPA (1.43 μg/L), group IV was treated with BPA (1.43 μg/L) plus CSNPs (0.33 ml/L), and group V was treated with BPA (1.43 μg/L) plus CSNPs (0.66 ml/L) for 30 days. Blood and liver tissue samples were collected at the end of experiment for the biochemical and oxidative stress biomarkers analyses. Results exhibited that serum Follicle Stimulating Hormone (FSH) and 17-β Estradiol (E2) were significantly decreased in female catfish. While, serum Testosterone (T.) and Luteinizing Hormone (LH) were increased after exposure to BPA. Marked increment in superoxide dismutase (SOD) and malondialdehyde (MDA) levels of hepatic tissue of catfish exposed to BPA. Furthermore, significant reduction in hepatic catalase (CAT), glutathione peroxidase (GSH-px), total antioxidant capacity (TAC), reduced glutathione (GSH), and glutathione S-transferase (GST) levels were decreased significantly in BPA-exposed catfish compared to the control group. However, administration of female C. gariepinus with the low and high doses (0.33 ml/L and 0.66 ml/L) of CNPs restored the biochemical parameters to be close to the normal values of the control group and also, reduced oxidative stress induced by BPA toxicity. This improvement was evident in fish administrated with the high CSNPs dose (0.66 ml/L) compared to catfish exposed to BPA in group (III). Furthermore, the percentage of hepatic DNA damage was detected in group III exposed to BPA alone. However, it was declined after co- administration with both the low and high doses of CSNPs. The study has revealed that treatment with CSNPs has antagonistic functions against the toxicity of BPA in female African catfish.

The combined toxicity of ultra-small SiO2 nanoparticles and bisphenol A (BPA) in the development of zebrafish

The complex combined effects of nanoparticles and environmental pollutants in the aqueous environment will inevitably affect aquatic ecosystem and human life. Bisphenol A (BPA) is listed as a typical kind of endocrine disruptors, there is little research about the joint toxicity of co-exposure of SiO₂ nanoparticles (NPs) and BPA. In this study, fluorescent ultra-small SiO₂ NPs (US-FMSNs) around 6.3 nm were synthesized and investigated for their combined effects with BPA on zebrafish during the early developmental stages within 4-168 h post fertilization (hpf). The results showed that US-FMSNs could accumulate in the chorion, abdomen and intestine in zebrafish. In addition, the different concentration (0.1, 1, 10 μg/mL) of BPA and US-FMSNs (200 μg/mL) demonstrated strong impact on multiple toxic endpoints at four periods (72, 96, 120, 168 hpf). We found US-FMSNs had no significant toxic effect on zebrafish, while BPA (10 μg/mL) showed a degree of developmental toxicity. Compared with single BPA (10 μg/mL) exposure, combined exposure enhanced the developmental toxicity of zebrafish, including increased mortality, decreased hatching rate and body length, and decreased activity of total superoxide dismutase (T-SOD) and increased malondialdehyde (MDA) levels. Our results indicated that US-FMSNs and BPA induced oxidative stress, and the effect of the co-exposure was less than that of single exposure (10 μg/mL). This study hereby provides a basis for the potential ecological and health risks of SiO₂ NPs and BPA exposure.

Activated AMPK promoted the decrease of lactate production in rat Sertoli cells exposed to Zearalenone

Zearalenone, which is ubiquitous in grains and animal feed, is a mycotoxin that can cause serious damage to animals and humans. Sertoli cells (SCs) can be used to study ZEA male reproductive toxicity in vitro. SCs provide energy for germ cells, where AMPK regulates intracellular energy. In order to explore the regulatory effect of AMPK on ZEA-induced lactate decline, we activated AMPK by AICAR and then inhibited AMPK by Compound C with ZEA-treated SCs for 24 h to detect intracellular lactate production-related indicators. Cell viability in the presence of 20 μmol/L ZEA and either 50 μmol/L AICAR or 5 μmol/L Compound C, respectively, did not damage SCs, and could effectively either activate or inhibit AMPK. Inhibition of AMPK promoted the production of pyruvate and lactate via increased expression of the glycolysis-related genes Pgam1 and the lactate production-related proteins GLUT1, LDHA, and MCT4. Activating AMPK inhibited the production of lactate and pyruvate by suppressing the expression of glycolysis-related genes HK1, Pgam1, and Gpi1 and that of lactate production-related proteins LDHA and MCT4. Zearalenone destroys the energy balance in SCs, activates P-AMPK, which inhibit the production of lactate and pyruvate in SCs. This also leads to the decrease of energy supply of SCs to spermatogenic cells, damages to reproductive system.

Impact of Fusarium-Derived Mycoestrogens on Female Reproduction: A Systematic Review

Contamination of the world’s food supply and animal feed with mycotoxins is a growing concern as global temperatures rise and promote the growth of fungus. Zearalenone (ZEN), an estrogenic mycotoxin produced by Fusarium fungi, is a common contaminant of cereal grains and has also been detected at lower levels in meat, milk, and spices. ZEN’s synthetic derivative, zeranol, is used as a growth promoter in United States (US) and Canadian beef production. Experimental research suggests that ZEN and zeranol disrupt the endocrine and reproductive systems, leading to infertility, polycystic ovarian syndrome-like phenotypes, pregnancy loss, and low birth weight. With widespread human dietary exposure and growing experimental evidence of endocrine-disrupting properties, a comprehensive review of the impact of ZEN, zeranol, and their metabolites on the female reproductive system is warranted. The objective of this systematic review was to summarize the in vitro, in vivo, and epidemiological literature and evaluate the potential impact of ZEN, zeranol, and their metabolites (commonly referred to as mycoestrogens) on female reproductive outcomes. We conducted a systematic review (PROSPERO registration CRD42020166469) of the literature (2000–2020) following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The data sources were primary literature published in English obtained from searching PubMed, Web of Science, and Scopus. The ToxR tool was applied to assess risk of bias. In vitro and in vivo studies (n = 104) were identified and, overall, evidence consistently supported adverse effects of mycoestrogens on physiological processes, organs, and tissues associated with female reproduction. In non-pregnant animals, mycoestrogens alter follicular profiles in the ovary, disrupt estrus cycling, and increase myometrium thickness. Furthermore, during pregnancy, mycoestrogen exposure contributes to placental hemorrhage, stillbirth, and impaired fetal growth. No epidemiological studies fitting the inclusion criteria were identified.

Bisphenol B stimulates Leydig cell proliferation but inhibits maturation in late pubertal rats

Bisphenol B (BPB) has been used as a substitute for bisphenol A (BPA) in plastic materials. Whether BPB disrupts the male reproductive system remains unknown. Here, we report the effect of BPB on Leydig cell maturation in late puberty. Male Sprague-Dawley (35 days old) rats were gavaged with BPB at 0, 10, 100, and 200 mg/kg/day for 21 days. BPB significantly reduced body and epididymis weight at 200 mg/kg. BPB markedly decreased serum testosterone levels at 100 and 200 mg/kg and serum luteinizing hormone and follicle-stimulating hormone levels at 200 mg/kg. BPB significantly increased Leydig cell number at 100 and 200 mg/kg, while down-regulating the expression of Leydig cell genes (Cyp11a1 and Hsd3b1) at ≥100 mg/kg and up-regulating the expression of Sertoli cell genes (Pdgfra, Fshr, Sox9) and cell cycle regulators (Pcna, Ccnb1, Cdk2, and Cdk4) at 10-200 mg/kg. BPB markedly increased the phosphorylation of AKT1, AKT2, and ERK1/2 at 200 mg/kg. BPB increased the proliferation of rat immature Leydig cells via promoting the S/M2 phase shift at 100 and 1000 nM after 24-h culture in vitro. In conclusion, BPB disrupts Leydig cell maturation in late puberty by increasing Leydig cell number while inhibiting its maturation.

G protein-coupled estrogen receptor 1 mediates estrogen effect in red common carp (Cyprinus carpio)

G protein-coupled estrogen receptor 1 (GPER1) plays a crucial role in the regulation of non-genomic estrogen effect. However, the research about fish GPER1 is still limited. The present study aims to obtain the full-length sequence of gper1 from red common carp (Cyprinus carpio) and characterize its expression pattern, and to further explore its potential role in regulating the environmental estrogen induced immunotoxicity. We first cloned the full-length mRNA and genomic sequences of gper1 in C. carpio by PCR, and obtained a 1908 bp sequence with a 1062 bp open reading frame encoding GPER1 protein with 353 amino acids. Additionally, qRT-PCR showed that gper1 was expressed across different tissues in C. carpio, with the highest expression in the brain, which is similar to that in zebrafish. Moreover, applying a luciferase reporter system, we found that the promotor sequence of gper1 has strong activity, and similar to GPER1 in other animals, carp GPER1 also has seven-transmembrane domains, indicating its potential functions. We confirmed the binding ability of GPER1 with G1 and G15 in primary macrophages of C. carpio by testing the related gene expression levels after 6 h exposure, and similar to G1, bisphenol A (BPA), a typical environmental estrogen, could interact with GPER1 to increase the Ca²⁺ concentration in macrophages treated for 30 min. Furthermore, inhibition of GPER1 with GPER1 antagonist G36 rescued the cellular immunotoxicity caused by BPA, which further suggested that carp GPER1 could mediate the estrogen effect. Our findings contribute to better understanding of the role of carp GPER1.

Resveratrol alleviates zea-induced decidualization disturbance in human endometrial stromal cells

Decidualization, which endows the endometrium competency to adopt developing embryo and maintain appropriate milieu for following growth, is a pivotal process for human pregnancy. The delicate collaboration between ovarian steroid hormones estrogen and progesterone governs the process of decidualization and subsequent establishment of embryo implantation. Mycotoxin zearalenone (ZEA) is well known as endocrine disruptor due to its potent estrogenic activity. In this study, we investigated effects of ZEA on decidualization of human endometrial stromal cells. Results indicated that ZEA exhibited its inhibitory action through nuclear translocation of ERα. ZEA exposure led to dampened progress of decidualization, which could be attenuated by estrogen receptor antagonist. Notably, resveratrol (RSV) administration restored impaired decidualization process by induction of anti-oxidative gene glutathione peroxidase 3 (GPX3). This study provides novel insights into the mechanism underlying adverse effects of ZEA in human decidual stromal cells and suggests RSV a potential therapeutic candidate to alleviate ZEA-induced cytotoxicity during decidualization.

Insight into the microbial communities associated with first larval stages of Mytilus galloprovincialis: Possible interference by estrogenic compounds

The microbiota, the host-associated community of microbes, play important roles in health status and whole body homeostasis of all organisms, including marine species. In bivalves, the microbiota composition has been mainly investigated in adults, whereas little information is available during development. In this work, the microbiota composition of the first larval stages of Mytilus galloprovincialis was evaluated by 16S rRNA gene-based profiling, at 24 and 48 hours post fertilization in comparison with those of eggs and sperm. The main genera detected in both larvae (Vibrio, Pseudoalteromonas, Psychrobium, Colwellia) derived from eggs. However, a clear shift in microbiota was observed in developing larvae compared to eggs, both in terms of core microbiome and relative abundance of different genera. The results provide a first insight into the composition of the microbial communities associated with gametes and early larvae of mussels. Moreover, the impact on larval microbiome of estrogenic chemicals that potentially affect Mytilus early development, 17βestradiol-E₂, Bisphenol A-BPA and Bisphenol F-BPF (10 μg/L), was investigated. Exposure to estrogenic chemicals leads to changes in abundance of different genera, with distinct and common effects depending on the compound and larval stage. Both potential pathogens (Vibrio, Arcobacter, Tenacibaculum) and genera involved in xenobiotic biotransformation (Oleispira, Shewanella) were affected. The effects of estrogenic compounds on larval microbiome were not related to their developmental effects: however, the results address the importance of evaluating the impact of emerging contaminants on the microbiota of marine invertebrates, including larval stages, that are most sensitive to environmental perturbations.

Molecular Aspects of Mycotoxins-A Serious Problem for Human Health

Mycotoxins are toxic fungal secondary metabolities formed by a variety of fungi (moulds) species. Hundreds of potentially toxic mycotoxins have been already identified and are considered a serious problem in agriculture, animal husbandry, and public health. A large number of food-related products and beverages are yearly contaminated by mycotoxins, resulting in economic welfare losses. Mycotoxin indoor environment contamination is a global problem especially in less technologically developed countries. There is an ongoing effort in prevention of mould growth in the field and decontamination of contaminated food and feed in order to protect human and animal health. It should be emphasized that the mycotoxins production by fungi (moulds) species is unavoidable and that they are more toxic than pesticides. Human and animals are exposed to mycotoxin via food, inhalation, or contact which can result in many building-related illnesses including kidney and neurological diseases and cancer. In this review, we described in detail the molecular aspects of main representatives of mycotoxins, which are serious problems for global health, such as aflatoxins, ochratoxin A, T-2 toxin, deoxynivalenol, patulin, and zearalenone.

Zearalenone affects reproductive functions of male offspring via transgenerational cytotoxicity on spermatogonia in mouse

Previous studies have demonstrated that Zearalenone (ZEA) affects not only maternal reproductive function but also that of the offspring. However, the transgenerational toxic effects of ZEA on the spermatogonia of male F1 mice are not clear. The present study was thus designed to determine whether the fertility of male F1 mice was affected following exposure of F0 pregnant mice to ZEA. In present study, 32 pregnant female mice were divided into 4 groups and exposed to ZEA of 0, 2.5 and 5.0 mg/kg, respectively, and the testis development and reproductive performance of 96 male F1 mice were analyzed. The results demonstrated that the F0 pregnant mice treated with ZEA resulted in increased anogenital distances in the newborn male F1 mice. Moreover, ZEA caused abnormal vacuole structures and loose connections in the testes of male F1 offspring, compared with the controls. Further ultramicrostructural analysis showed that the mitochondria appeared to be vacuolated with ablated membranes and cristae, and this was accompanied by the presence of large lipid droplets in the spermatogonia. Further, the semen quality and sperm counts declined significantly, and increased malformation rates and decreased testosterone levels were observed in the male F1 offspring from experimental groups. Our results reveal the toxic effects of ZEA on F0 pregnant mice is transgenerational, and affects the fertility of male F1 mice by damaging the spermatogonial cells. This offers a new viewpoint of ZEA-induced reproductive toxicity in male animals and provides a new potential direction for the treatment and prevention of ZEA-induced cytotoxicity.

Impairment of learning and memory induced by perinatal exposure to BPA is associated with ERα-mediated alterations of synaptic plasticity and PKC/ERK/CREB signaling pathway in offspring rats

The effect of bisphenol A (BPA) on learning and memory has attracted much attention recently, but its underlying mechanism remains unclear. We aimed to investigate whether the impairment of learning and memory induced by perinatal exposure to BPA was associated with the hippocampal estrogen receptor α (ERα)-mediated synaptic plasticity and PKC/ERK/CREB signaling pathway in different sex offspring rats. Pregnant Sprague-Dawley rats were treated with BPA (1 and 10 μg/mL) through drinking water from gestational day (GD) 6 to postnatal day (PND) 21. After weaning, offspring drank BPA-free water until PND 56. Morris water maze, placement and object recognition, and step-down passive avoidance task were performed. The serum estradiol (E2) levels, histopathology of hippocampus, and the expression of learning and memory related proteins were measured. The results showed that spatial and recognition memory were impaired in BPA-exposed female and male offspring, but the impaired passive avoidance memory presented only in males, not in females. The serum E2 levels were increased in BPA-exposed females and males. BPA altered the morphology and quantity of hippocampal neurons. The levels of ERα, NMDA receptor subunit 2B (NR2B), p-NR2B, AMPA receptor 1 (GluA1), p-GluA1, PSD-95, synapsin I, PKC, p-ERK and p-CREB protein expression were decreased in BPA exposed females and males, and there were interactions of sex × BPA exposure in ERα, p-NR2B and p-ERK levels. These findings suggested that perinatal exposure to BPA has sex-specific effects on learning and memory, which is associated with ERα-mediated impairment of synaptic plasticity and down-regulation of PKC/ERK/CREB signaling pathway.

Environmental estrogen exposure converts lipid metabolism in male fish to a female pattern mediated by AMPK and mTOR signaling pathways

Environmental estrogens, including bisphenol A (BPA) and 17β-estradiol (E2), which are widely used in industries and medicine, pose a severe ecological threat to fish due to feminization induction. However, the related metabolic basis for reproductive feminization in male fish has not been well addressed. We first found that female zebrafish exhibited higher lipid accumulation and lipogenesis activity than males. Next, we exposed male and female zebrafish to E2 (200 ng/L) or BPA (100 μg/L) for six weeks, and observed an early-phase reproductive feminization in males, accompanied with reduced spermatids, significant fat deposition and lipogenic gene expressions that mimicked female patterns. Cellular signaling assays revealed that, E2 or BPA modulated lipid metabolism in males mainly through lowering 5' AMP-activated protein kinase (AMPK) and upregulating the lipogenic mechanistic target of rapamycin (mTOR) pathways. For the first time, we show that environmental estrogens could alter lipid metabolism in male fish to a female pattern (metabolic feminization) prior to gonad feminization in male fish, to allows males to accumulate efficiently lipids to harmonize with the feminized gonads. This study suggests that negative effects of environmental estrogens, as hazardous materials, on vertebrate health are more complicated than originally thought.

Diethylstilbestrol exposure disrupts mouse oocyte meiotic maturation in vitro through affecting spindle assembly and chromosome alignment

An adverse tendency induced by the environmental estrogens in female reproductive health is one serious problem worldwide. Diethylstilbestrol (DES), as a synthetic estrogen, is still used as an animal growth stimulant in terrestrial livestock and aquaculture illegally. It has been reported to negatively affect ovarian function and oogenesis. Nevertheless, the mechanism and toxicity of DES on oocyte meiotic maturation are largely unknown. Herein, we found that DES (40 μM) intervened in mouse oocyte maturation and first polar body extrusion (PBE) was decreased in vitro. Cell cycle analysis showed meiotic process was disturbed with oocytes arrested at metaphase I (MI) stage after DES exposure. Further study showed that DES exposure disrupted the spindle assembly and chromosome alignment, which then continuously provoke the spindle assemble checkpoint (SAC). We also observed that the acetylation levels of α-tubulin were dramatically increased in DES-treated oocytes. In addition, the dynamics of actin were also affected. Moreover, the distribution patterns of estrogen receptor α (ERα) were altered in DES-treated oocyte, as indicated by the significant signals accumulation in the spindle area. However, ERα inhibitor failed to rescue the defects of oocyte maturation caused by DES. Of note, the same phenomenon was observed in estrogen-treated oocytes. Collectively, we showed that DES exposure lead to the oocyte meiotic failure via impairing the spindle assembly and chromosome alignment. Our research is helpful to understand how environmental estrogen affects female germ cells and contribute to design the potential therapies to preserve fertility especially for occupational exposure.

Inhibition of pancreatic lipase by environmental xenoestrogens

Environmental xenoestrogens are the most accessible endocrine disrupting chemicals that have been reported with harmful effects on human health. Although the influences of xenoestrogens on the endocrine system have been extensively studied, it remains unclear whether these xenoestrogens can affect the digestive system in mammals. This study aimed to investigate the inhibitory effects and the underlying mechanism of six non-steroidal synthetic estrogens (including hexestrol, diethylstilbestrol, dienestrol, bisphenol A, bisphenol AF and bisphenol Z) on pancreatic lipase (PL), a key digestive enzyme responsible for lipid digestion and absorption in mammals. The results clearly demonstrated that hexestrol, diethylstilbestrol and dienestrol exhibited strong inhibition on PL, with the IC₅₀ values of less than 1.0 μM. Further investigations elucidated that these three synthetic estrogens functioned as mixed inhibitors of PL, with the K_i values of less than 1 μM. Moreover, molecular dynamics simulations showed that diethylstilbestrol and its analogues might block the binding of substrate on PL via occupying the portal to the active site of PL and thereby inhibit the hydrolytic activity of this key enzyme. Collectively, these results suggested that diethylstilbestrol and its analogues were potent PL inhibitors, which might play a profound role in lipid absorption and weight gain in mammals.

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.

Correlations between exposure to deoxynivalenol and zearalenone and the immunohistochemical expression of estrogen receptors in the intestinal epithelium and the mRNA expression of selected colonic enzymes in pre-pubertal gilts

Plant-based materials used in the production of pig feed are very often contaminated with deoxynivalenol and zearalenone. Daily intake of small amounts of these mycotoxins with feed induces various subclinical states in gilts and influences different biological processes. The aim of this preclinical study was to determine the correlation between monotonic doses of zearalenone and deoxynivalenol (40 μg/kg body weight and 12 μg/kg body weight, respectively, administered over a period of 42 days) and the immunohistochemical expression of estrogen receptors in the intestinal tract and the mRNA expression of selected colonic enzymes. The immunohistochemical expression of estrogen receptor alpha was observed in the colon, but its intensity varied in different weeks of exposure. A minor increase in estrogen receptor beta expression was noted only in the colon, whereas the expression of cytochrome P450 1A1 enzyme mRNA and mRNA isoform of the glutathione S-transferase π gene decreased. The observed correlations suggest that the risk of loss of control over the biotransformation and biological activity of the parent compounds in distal intestinal mucosa is delayed.

Persistent vs Transient Alteration of Folliculogenesis and Estrous Cycle After Neonatal vs Adult Exposure to Bisphenol A

Exposure to bisphenol A (BPA), a ubiquitous endocrine-disrupting chemical (EDC), is known to produce variable effects on female puberty and ovulation. This variability of effects is possibly due to differences in dose and period of exposure. Little is known about the effects of adult exposure to environmentally relevant doses of this EDC and the differences in effect after neonatal exposure. This study sought to compare the effects of neonatal vs adult exposure to a very low dose or a high dose of BPA for 2 weeks on ovulation and folliculogenesis and to explore the hypothalamic mechanisms involved in such disruption by BPA. One-day-old and 90-day-old female rats received daily subcutaneous injections of corn oil (vehicle) or BPA (25 ng/kg/d or 5 mg/kg/d) for 15 days. Neonatal exposure to both BPA doses significantly disrupted the estrous cycle and induced a decrease in primordial follicles. Effects on estrous cyclicity and folliculogenesis persisted into adulthood, consistent with a disruption of organizational mechanisms. During adult exposure, both doses caused a reversible decrease in antral follicles and corpora lutea. A reversible disruption of the estrous cycle associated with a delay and a decrease in the amplitude of the LH surge was also observed. Alterations of the hypothalamic expression of the clock gene Per1 and the reproductive peptide phoenixin indicated a disruption of the hypothalamic control of the preovulatory LH surge by BPA.

Nonylphenol causes shifts in microbial communities and nitrogen mineralization in soil microcosms

The aims of this work was to investigate, in soil microcosms, the effects on soil microbial community structure and function of increasing concentrations of 4-Nonylphenol (NP). The lasts is a product of degradation of NPEOs (Nonylphenol polyethoxylates) with a known toxic and estrogenic capacity able to disrupt animal's hormonal systems. The effect of increasing concentrations of NP (0, 10, 30, 90, and 270 mg NP kg^-1 of dry soil) in soil microcosms in three sampling dates (28, 56, and 112 days) over soil microbial activity and function were assessed. Soil microbial activity was estimated by microbial ATP content, and both bacterial and fungal communities composition were estimated using the terminal restriction fragment length polymorphism technique (T-RFLP). Abundance of ammonia-oxidizing bacteria (AOB) was estimated by qPCR of gene encoding for the bacterial ammonia-monoxygenase (amoA). Changes in biologically mediated soil properties were also assessed, namely water-soluble NH⁺₄, NO^-₂ and NO^-₃ content, the two last allowing the assessment of mineralization rates. NP-spiking had some unexpected impacts on microbial community structure and functions, since (i) impacted both bacterial and fungal communities structure at the highest NP concentration tested, bacterial communities were resistant to lower concentrations, while fungal communities were increasingly impacted until the end of the incubation at day 112; (ii) no community structure resilience was observed in bacteria at the highest NP concentration nor for fungi at any concentration; (iii) microbial activity decreased with NP after 28 and 56 d, but increased in the last sampling at the highest concentrations tests, coupled to an enrichment in AOB taxa after 56 and 112 days, that at least partly explain also explain the observed speed up of nitrification rates.

Effect of grape seed extract on maternal toxicity and in utero development in mice treated with zearalenone

The aims of this study were to determine the polyphone content of grape seed extract (GSE) and to assess their protective effects against zearalenone (ZEN)-induced maternal toxicity and in utero development defects in mice. Five groups of pregnant mice were treated orally during days 6-13 of gestation as follows: control group, corn oil as vehicle (0.1 ml/mice)-treated group, ZEN-treated group (25 mg/kg b.w), GSE-treated group (150 mg/kg b.w.), and ZEN plus GSE-treated group. All animals were sacrificed on the 19th day of gestation and samples of bone marrow were collected for the micronucleus assay. The maternal and developmental toxicity were carried out. The HPLC analyses revealed that GES is rich in gallic acid, syringic acid, vanillin, quercetin, and coumaric acid. ZEN administration resulted in severe maternal and developmental toxicity which included an increase of micronuclei formation in bone marrow, decreased maternal weight gain, and litter weight. It also induces fetal growth retardation, increased number of the aborted dams and resorbed fetuses, abnormality of fetal bone ossification, and number of fetuses with a hematoma. GSE showed positive effects on the pregnant mice and the developing fetuses. Moreover, it counteracted the detrimental effects of ZEN in dams and fetuses. It could be concluded that polyphenols in GSE are a promising candidate to protect against ZEN toxicity in highly endemic areas.

Modulation of brain kisspeptin expression after bisphenol-A exposure in a teleost fish, Catla catla

Endocrine-disrupting chemicals (EDCs) affect the neuroendocrine system which in turn influences the reproductive regulation. Neuronal genes disrupted by EDCs are the gonadotropin-releasing hormone (gnrh2), the Kiss/GPR54 system that regulates gonadotropin release and cyp19b gene encoding brain aromatase. In the present study, pubertal Catla catla expected to spawn for first the time in the coming season were exposed to graded concentration of bisphenol-A (10, 100, 1000 μg/l) for 14 days. Messenger RNA (mRNA) levels of neuroendocrine genes, i.e., kisspeptins and their receptors, gonadotropin-releasing hormone type II and brain aromatase were studied after 14 days exposure. Results showed that bisphenol-A (BPA) strongly upregulated expression of kiss1, kiss2, gpr54a, and gnrh2 in fish exposed to 10 μg/l BPA. Fish exposed to 1000 μg/l BPA, expression of kiss1 and gnrh2 were comparable to control while kiss2 mRNA increased compared to controls. Brain aromatase (cyp19b) mRNA expression increased in fish exposed to both 10 and 1000 μg/l BPA. These results indicate that BPA exposure can disrupt organization of the kisspeptin signaling pathways. This neuroendocrine disruption may be the underlying mechanism by which a suite of reproductive abnormalities are induced.

Perinatal High-Fat Diet and Bisphenol A: Effects on Behavior and Gene Expression in the Medial Prefrontal Cortex

Both high-fat diets (HFD) and bisphenol A (BPA), an environmental endocrine disruptor, are prevalent in industrialized societies. Previous studies have detected separate effects of BPA and HFD; however, none have assessed possible interactive effects. Here, pregnant dams consumed 0, 40, or 400 µg BPA/kg/day and were fed either a control (CON; 15.8% kcal fat) or HFD (45% kcal fat) from gestational day 2 through parturition. The pups were individually dosed with BPA from postnatal days (P) 1-10, while the dams continued to consume one of the two diets. Maternal behavior increased with the HFD while the offspring's periadolescent social play decreased with BPA, but no interactive effects were observed. Neither HFD nor BPA exposure changed performance on a social recognition task, and only BPA had an effect on the elevated plus maze. BPA increased several cytokines in the medial prefrontal cortex (mPFC) of P10 males but not females. Expression of several genes related to hormone synthesis and receptors, inflammation, oxidative stress, and apoptosis in the mPFC on P10 and P90 were altered due to BPA and/or HFD exposure with rare interactive effects. BPA resulted in an increase in the gene expression of Esr1 in the mPFC of females on both P10 and P90. Epigenetic analysis on P90 did not show a change in methylation or in the levels of pre-mRNA or microRNA. Thus, perinatal BPA and HFD have separate effects but rarely interact.

Bisphenol A as an environmental pollutant with dual genotoxic and DNA-protective effects

OBJECTIVES

Bisphenol A (BPA) is an endocrine disruptor which has been shown to be a harmful compound for living organisms. It is the main component of the most commonly used plastic products such as plastic bottles, food cans and containers or dental fillings, and other medical aids. Recently, it has become a new environmental pollutant. The current knowledge about the BPA effects (including genotoxic one) on different cells is in many cases contradictory. Thus, the aim of the paper is to study the potential genotoxic effect of BPA.

METHODS

An observation of the genotoxic activity of BPA on human lymphocytes was evaluated by using the alkaline comet assay and a modified comet assay with bacterial DNA repair enzyme Fpg. The potential DNA-protective effect of BPA was tested by using the DNA-topology assay.

RESULTS

The results show that rising concentrations of BPA increase the risk of DNA double-strand breaks and modified purines in human lymphocytes. Interestingly, BPA shows an ability to protect plasmid DNA from the damage of iron ions in cell-free system.

CONCLUSIONS

BPA itself does not induce genotoxic effect to DNA. However, BPA treatment of human lymphocytes leads to the induction of DNA damage. The proposed mechanism of BPA action in the human lymphocytes could be mediated by cell metabolism that induces an oxidative stress and ROS formation. ROS subsequently attack DNA and thus induce DNA damage. According to our results, BPA can be included in the group of substances with dual effects involving genotoxic and DNA-protective activity.

Influence of gastrointestinal tract on metabolism of bisphenol A as determined by in vitro simulated system

Oral exposure is a major route of human bisphenol A (BPA) exposure. However, influence of gastrointestinal tract on BPA metabolism is unavailable. In this study, in vitro simulator of the human intestinal microbial ecosystem (SHIME) was applied to investigate the changes in bioaccessibility and metabolism of BPA in different parts of gastrointestinal tract (stomach, small intestine and colon). Then the human hepatoma cell line HepG2 was employed to compare toxic effects of BPA itself and effluents of SHIME system on hepatic gene expression profiles. Results showed that level of bioaccessible BPA decreased with the process of gastrointestinal digestion. But the gastrointestinal digestion could not completely degrade BPA. Then, BPA exposure significantly changed microbial community in colons and increased the percentage of microbes shared in ascending, transverse and descending colons. Abundances of BPA-degradable bacteria, such as Microbacterium and Alcaligenes, were up-regulated. Further, SHIME effluents significantly up-regulated expressions of genes related to estrogenic effect and oxidative stress compared to BPA itself, but reduced or had little change on the risk of cell apoptosis and fatty deposits. This study sheds new lights on influence of gastrointestinal digestion on bioaccessibility and toxic effects of BPA.

Effects of bisphenol A (BPA) on brain-specific expression of cyp19a1b gene in swim-up fry of Labeo rohita

Estrogen regulates numerous developmental and physiological processes and effects are mediated mainly by estrogenic receptors (ERs), which function as ligand-regulated transcription factor. ERs can be activated by many different types endocrine disrupting chemicals (EDCs) and interfere with behaviour and reproductive potential of living organism. Estrogenic regulation of membrane associated G protein-coupled estrogen receptor, GPER activity has also been reported. Bisphenol A (BPA), a ubiquitous endocrine disruptor is present in many household products, has been linked to many adverse effect on sexual development and reproductive potential of wild life species. The present work is aimed to elucidate how an environmentally pervasive chemical BPA affects in vivo expression of a known estrogen target gene, cyp19a1b in the brain, and a known estrogenic biomarker, vitellogenin (Vg) in the whole body homogenate of 30 days post fertilization (dpf) swim-up fry of Labeo rohita. We confirm that, like estrogen, the xenoestrogen BPA exposure for 5-15 days induces strong overexpression of cyp19a1b, but not cyp19a1a mRNA in the brain and increase concentration of vitellogenin in swim-up fry. BPA also induces strong overexpression of aromatase B protein and aromatase activity in brain. Experiments using selective modulators of classical ERs and GPER argue that this induction is largely through nuclear ERs, not through GPER. Thus, BPA has the potential to elevate the levels of aromatase and thereby, levels of endogenous estrogen in developing brain. These results indicate that L. rohita swim-up fry can be used to detect environmental endocrine disruptors either using cyp19a1b gene expression or vitellogenin induction.

Diethylstilbestrol arrested spermatogenesis and somatic growth in the juveniles of yellow catfish (Pelteobagrus fulvidraco), a fish with sexual dimorphic growth

In fish, spermatogenesis and somatic growth are mainly regulated by hypothalamic-pituitary-gonadal (HPG) and hypothalamic-pituitary-somatic (HPS) axes, respectively. Xenoestrogens have been reported to impair spermatogenesis in some fishes, and arrest somatic growth in some others, whereas, whether xenoestrogens are capable of disrupting spermatogenesis and somatic growth simultaneously in fish that exhibits sexual dimorphic growth is little known, and the underlying mechanisms remain poorly understood. In this study, male juveniles of yellow catfish (Pelteobagrus fulvidraco), which exhibits a sexual dimorphic growth that favors males, were exposed to diethylstilbestrol (DES) for 28 days. After exposure, DES significantly disrupted the spermatogenesis (decreased gonadal-somatic index (GSI) and germ cell number) and arrested the somatic growth (declined body weight) of the catfish juveniles. Gene expression and plasma steroid analyses demonstrated the suppressed mRNA levels of genes in HPG axis (gnrh-II, fshβ, and lhβ in the brain and dmrt1, sf1, fshr, cyp17a1, cyp19a1a, and cyp11b2 in the testis) and decreased 17β-estrodial (E2) and 11-ketotestosterone (11-KT) levels in plasma. Further analysis revealed the arrested germ cell proliferation (cyclin d1), meiosis (dmc1, sycp3), and enhanced apoptosis (decreased bcl-2 and elevated bax/bcl-2 ratio) in the testis. Besides, DES also suppressed the mRNA levels of genes in HPS axis (ghrh, gh, and prl in the brain and ghr, igf1, igf2a, and igf2b in the liver). The suppressed HPG and HPS axes were thus supposed to disturb spermatogenesis and arrest somatic growth in yellow catfish. The present study greatly extended our understanding on the mechanisms underlying the toxicity of DES on spermatogenesis and somatic growth of fish.

The “Low Dose” Hypothesis: Validity and Implications for Human Risk

In the late 1990s, a “low dose” hypothesis was proposed based on studies that purported to show that hormonally active environmental agents were causing a variety of effects, mainly reproductive and developmental, at “low doses.” The supporters of this hypothesis claim that traditional “high-dose” toxicity studies are not adequate to assess adverse effects from these hormonally active agents in that they do not detect effects that are occurring at “low doses.” In addition, it is claimed that these “low dose” effects are occurring at levels comparable to those to which humans are being exposed. These claims have been controversial and expert panels evaluated the evidence behind them in the early 2000s. Although these panels generally concluded that such “low dose” effects were not conclusively established, proponents of the “low dose” hypothesis assert that a large number of more recent studies now provide clear support for their hypothesis. This review carefully examines both recent and older studies that have been cited to support the “low dose” hypothesis, including their relevance for the human population. These include in vivo and in vitro laboratory studies as well as a very limited number of epidemiological investigations. Based on the evidence, it is concluded that these “low dose” effects have yet to be established, that the studies purported to support these cannot be validly extrapolated to humans, and the doses at which the studies have been performed are significantly higher than the levels to which humans are exposed.

The dose-dependent effect of zearalenone on mitochondrial metabolism, plasma membrane permeabilization and cell cycle in human prostate cancer cell lines

Zearalenone (ZEA) is a nonsteroidal mycotoxin produced by several fungi of the genus Fusarium spp. It is known to play various roles in the regulation of the prostate cancer cell cycle, including carcinogenesis. The present study evaluates the influence of ZEA on the mitochondrial metabolism, plasma membrane permeabilization and cell cycle of prostate cancer cells. At concentrations of 100 nM and 0.3 nM, ZEA caused a decrease in the oxidative activity of mitochondria, as well as increases in LDH release, apoptosis induction and the number of cells in the G0/G1 phase. The opposite effect was observed for lower concentrations (0.1 nM and 0.001 nM). These in vitro studies indicate that ZEA might have pro- and antiproliferative properties in prostate cancer cells, at concentrations 0.1 nM, 0.001 nM and 0.3 nM, 100 nM, respectively.

Bile Acids and Tryptophan Metabolism Are Novel Pathways Involved in Metabolic Abnormalities in BPA-Exposed Pregnant Mice and Male Offspring

Increasing evidence has demonstrated that exposure to endocrine-disrupting chemicals impacts maternal and fetal health, but the underlying mechanisms are still unclear. We previously showed that dietary exposure to 10 µg/kg body weight (bw)/d and 10 mg/kg bw/d of bisphenol A (BPA) during pregnancy induced metabolic abnormalities in F1 male offspring and gestational glucose intolerance in F0 pregnant mice. The aim of this study was to elucidate the underlying etiologies of BPA exposure-induced metabolic disease by analyzing the male fetal liver metabolome. Using the Metabolon Discover HD4 Platform, our laboratory identified metabolic pathways that were altered by BPA exposure, including biochemicals in lipid and amino acid metabolism. Specifically, primary and secondary bile acids were increased in liver from BPA-exposed embryonic day 18.5 male fetuses. We subsequently showed that increased bile acid was associated with a defective farnesoid X receptor-dependent negative feedback mechanism in BPA-exposed fetuses. In addition, through metabolomics, we observed that BPA-exposed fetuses had elevated tryptophan levels. Independent liquid chromatography and mass spectrometry measurement revealed that BPA-exposed dams also had increased tryptophan levels relative to those of controls. Because several key enzymes in tryptophan catabolism are vitamin B6 dependent and vitamin B6 deficiencies have been linked to gestational diabetes, we tested the impact of vitamin B6 supplementation and showed that it rescued gestational glucose intolerance in BPA-exposed pregnant mice. Our study has therefore identified two pathways (bile acid and tryptophan metabolism) that potentially underlie BPA-induced maternal and fetal metabolic disease.

Bisphenol A promotes hepatic lipid deposition involving Kupffer cells M1 polarization in male mice

Bisphenol A (BPA), one of the most common environmental endocrine disruptors, is considered to promote hepatic lipid deposition. However, the mechanism has not been fully elucidated. The polarization of Kupffer cells (KCs) plays an important role in hepatic inflammation by promoting pro-inflammatory M1 phenotype (M1KCs), which contributes to dysregulated lipid metabolism. The purpose of this study is to investigate the role of KC polarization in BPA-induced hepatosteatosis in male mice. In this study, we examined hepatic lipid contents and quantified M1KC in BPA-treated CD1 mice, and further explored the interaction between KCs and hepatocytes using conditional HepG2 cell culture. BPA treatment significantly increased hepatic fat contents in CD1 mice, accompanied by increased number of pro-inflammatory M1KCs and enhanced secretion of inflammatory cytokines. Increased lipid contents were also observed in HepG2 cells treated with BPA. Interestingly, higher TG contents were observed in HepaG2 cells treated with conditional media from BPA-treated KCs, compared with those treated with BPA directly. Incubation of KCs with BPA promoted the polarization of KCs to pro-inflammatory M1 dominant subtypes, which was blocked by estrogen antagonist ICI182780. Taken together, our results revealed that M1KCs polarization is involved in BPA-induced hepatic fat deposition, which is possibly associated with the estrogen receptor signaling pathway.

Regulation of oncogenes and gap junction intercellular communication during the proliferative response of zearalenone in TM3 cells

Zearalenone (ZEA) is a nonsteroidal estrogenic mycotoxin produced by Fusarium species. The exposure risk to humans and animals is the consumption of contaminated food and animal feeds. The aim of this study was to investigate ZEA-induced effects and its tumorigenic mechanism in TM3 cells (mouse Leydig cells). Cell proliferation, apoptosis, and gap junction intercellular communication (GJIC) were assessed in this study. Results showed that low concentrations of ZEA could significantly promote the growth of TM3 cells. The percentage of cell distribution was decreased significantly in G1/G0 phase and was increased significantly in S phase with 10 and 20 μg/L of ZEA for 72 h ( p < 0.05, p < 0.01). The expressions of cyclin D1 and Cdk4 were significantly increased in the exposure groups compared with the control group ( p < 0.05, p < 0.01). Compared with the control group, the apoptosis was significantly decreased in 10 and 20 μg/L groups ( p < 0.01), and the ratio of Bax/Bcl-2 protein level was significantly decreased in a dose-dependent manner. The protein levels of proto-oncogene c-Myc, c-Jun, and c-Fos were significantly elevated and the protein levels of anti-oncogene p53 and phosphatase and tensin homolog (PTEN) were decreased obviously compared with the control group ( p < 0.05, p < 0.01). ZEA affected the expressions of connexins and inhibited the activity of GJIC. These results demonstrated that ZEA can disturb the dynamic balance between proliferation and apoptosis and causes abnormal regulation of oncogenes, GJIC, and connexins in TM3 cells, which may easily induce the translation of normal cells into tumor cells.

Diethylstilbestrol induces oxidative DNA damage, resulting in apoptosis of spermatogonial stem cells in vitro

) in SSCs was detected using p-Nitro Blue Tetrazolium (NBT) assay. The viability of cells after DES treatment was examined in the CCK8 (cell counting kit-8) cytotoxicity assay. The results showed that DES-induced DNA damage causes an increase in intracellular superoxide anions which are reduced by the flavonoid, quercetin. Investigating the molecular mechanisms and biology of SSCs provides a better understanding of spermatogonial stem cell regulation in the testis.

Acute exposure to bisphenol A and cadmium causes changes in the morphology of gerbil ventral prostates and promotes alterations in androgen-dependent proliferation and cell death

Bisphenol A (BPA) and cadmium (Cd) are environmental pollutants that are implicated in potential reproductive effects, including damage to the prostate gland. Their action during puberty requires analysis to determine the relationship of these compounds with the testosterone peak that occurs during this phase. This study evaluated whether exposure to BPA and Cd during puberty can cause changes in the morphology, proliferation and cell death and androgen receptor (AR) immunostaining of the ventral prostates of normal and castrated male gerbils (Meriones unguiculatus), considering an acute exposure to the chemicals and evaluation after short (52d) and long (120d) periods. Generally, morphometric-stereological results demonstrated that administration of BPA and Cd (individually or in combination) increased epithelial height, smooth muscle layer (SML) thickness and nuclear area and perimeter, and that these parameters were reduced in castrated animals. In addition, these groups showed important inflammatory processes but not prostate lesions. The proliferation/death rates of prostatic cells obtained by PCNA and TUNEL immunostaining demonstrated increased cell death in the 52d groups; in contrast, the gland acquired a more proliferative nature in the 120d groups. AR immunostaining showed that BPA and Cd compounds interact with ARs in different ways depending on the evaluated period and the hormonal profile of the animal. We conclude that BPA and cadmium are important agents in changing the morphology, proliferation and death of prostatic cells, in addition to interacting with ARs in different patterns. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 48-61, 2017.

Concurrent administration of diethylhexyl phthalate reduces the threshold dose at which bisphenol A disrupts blastocyst implantation and cadherins in mice

Many people are repeatedly exposed to both bisphenol A (BPA) and diethylhexyl phthalate (DEHP), but there has been little research concerning their effects in combination. Both can disrupt blastocyst implantation in inseminated females, albeit at high doses. We exposed mice on gestation days (GD) 1-4 to combinations of BPA and DEHP in doses below the threshold necessary to disrupt implantation on their own. On GD 6, there were fewer normally-developed implantation sites and more underdeveloped implantation sites in females given the combined subthreshold doses. Uterine epithelial cadherin (e-cadherin), a protein that assists in blastocyst adhesion to the uterine epithelium, was significantly reduced by these combined doses, but not by the individual doses. A similar trend was seen in integrin αvβ3, another uterine adhesion molecule. Cadherin-11 was disrupted by BPA but not DEHP. These data are consistent with competition of BPA and DEHP for conjugating enzymes.

Exploration of intrinsic and extrinsic apoptotic pathways in zearalenone-treated rat sertoli cells

Zearalenone (ZEA) is a nonsteroidal estrogenic mycotoxin produced mainly by Fusarium. ZEA causes reproductive disorders and is both cytotoxic and genotoxic in animals; however, little is known regarding the molecular mechanism(s) leading to ZEA toxicity. Sertoli cells are somatic cells that support the development of spermatogenic cells. The objective of this study was to explore the effects of ZEA on the proliferation, apoptosis, and necrosis of rat Sertoli cells to uncover signaling pathways underlying ZEA cytotoxicity. ZEA reduced the proliferation of rat Sertoli cells in a dose-dependent manner, as indicated by a CCK8 assay, while flow cytometry revealed that ZEA caused both apoptosis and necrosis. Immunoblotting revealed that ZEA treatment increased the ratio of Bax/Bcl-2, as well as the expression of FasL and caspases-3, -8, and -9, in a dose-dependent manner. Collectively, these data suggest that ZEA induced apoptosis and necrosis in rat Sertoli cells via extrinsic and intrinsic apoptotic pathways. This study provides new insights into the molecular mechanisms by which ZEA exhibits cytotoxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1731-1739, 2016.

Development of an in vitro test battery for the screening of the receptor-mediated mechanism and the spindle-poison mode of action of estrogenic compounds

The implementation of the REACH regulation has imposed the urgent need of developing alternative testing methods to screen large number of compounds more quickly and at lower costs. In this study, a battery of tests, suitable for reproductive toxicology testing, was developed with the objective of detecting the mechanism of action of estrogenic and xenoestrogenic compounds. With this aim, two compounds known for their estrogenic activity, diethylstilbestrol and 17β-estradiol, were used to set up four different in vitro tests: 1) bovine oocyte in vitro maturation assay, 2) bovine preimplantation embryo in vitro culture assay and 3) MCF-7 and 4) BALB/3T3 cell lines proliferation and cytotoxicity assay, respectively. The results show that this battery of tests allows to identify and to distinguish between two major mechanisms of action of (xeno)estrogenic compounds: the receptor-mediated mechanism and the spindle-poison effect on microtubules polimerization.

Assessing placental corticotrophin-releasing hormone disruption by hexestrol in a cell model

Studies have shown that corticotrophin-releasing hormone (CRH) and relaxin are associated with early delivery. Our lab previously has shown the mycotoxin zeranol increases placental CRH expression. The mycotoxin is used in the farming industry to promote cattle growth, and some synthetic hormones are also used for the same purposes. In order to complete the picture of these growth promoting agents, we attempted to examine the synthetic hormones on the placental gene expression in the current study. Among the tested compounds, hexestrol induced the CRH mRNA and protein expression at 100nM in JEG-3 cells. As signal transduction pathways have been described in the transcriptional control previously, the activations of several protein kinases were determined. P38, PKCβ and JNK were activated upon hexestrol treatment. Since the P38-inhibitor SB203580 prevented hexestrol from inducing CRH in a subsequent experiment, P38 was likely involved in the transcriptional regulation. Electrophoretic mobility shift assay revealed an increase in the CRE binding activity in CRH promoter. This study showed that hexestrol exposure might be a concern for pregnant women.

Neonatal isoflavone exposure interferes with the reproductive system of female Wistar rats

There is increasing concern about possible adverse effects of soy based infant formulas (SBIF) due to their high amount of isoflavones (ISO). The aim of the present study was to investigate effects of neonatal exposure to ISO on reproductive system of female Wistar rats. Animals were exposed to an ISO depleted diet or a diet enriched with an ISO extract (IRD; 508mg ISO/kg) during embryogenesis and adolescence. Pups of each group were fed daily by pipette with ISO-suspension (ISO+; 32mg ISO/kg bw) or placebo from postnatal day (PND) 1 until PND23 resulting in plasma concentrations similar to levels reported in infants fed SBIF. The visceral fat mass was reduced by long-term IRD. Vaginal epithelial height was increased at PND23 and vaginal opening was precocious in ISO+ groups. Later in life, more often irregular estrus cycles were observed in rats of ISO+ groups. In addition, FSH levels and uterine epithelial heights were increased at PND80 in ISO+ groups. In summary, the results indicate that neonatal ISO intake, resulting in plasma concentrations achievable through SBIF, has an estrogenic effect on prepubertal rats and influences female reproductive tract later in life.

Impact of bisphenol A (BPA) on early embryo development in the marine mussel Mytilus galloprovincialis: Effects on gene transcription

Bisphenol A (BPA), a monomer used in plastic manufacturing, is weakly estrogenic and a potential endocrine disruptor in mammals. Although it degrades quickly, it is pseudo-persistent in the environment because of continual inputs, with reported concentrations in aquatic environments between 0.0005 and 12 μg/L. BPA represents a potential concern for aquatic ecosystems, as shown by its reproductive and developmental effects in aquatic vertebrates. In invertebrates, endocrine-related effects of BPA were observed in different species and experimental conditions, with often conflicting results, indicating that the sensitivity to this compound can vary considerably among related taxa. In the marine mussel Mytilus galloprovincialis BPA was recently shown to affect early development at environmental concentrations. In this work, the possible effects of BPA on mussel embryos were investigated at the molecular level by evaluating transcription of 13 genes, selected on the basis of their biological functions in adult mussels. Gene expression was first evaluated in trocophorae and D-veligers (24 and 48 h post fertilization) grown in physiological conditions, in comparison with unfertilized eggs. Basal expressions showed a general up-regulation during development, with distinct transcript levels in trocophorae and D-veligers. Exposure of fertilized eggs to BPA (10 μg/L) induced a general upregulation at 24 h pf, followed by down regulation at 48 h pf. Mytilus Estrogen Receptors, serotonin receptor and genes involved in biomineralization (Carbonic Anydrase and Extrapallial Protein) were the most affected by BPA exposure. At 48 h pf, changes in gene expression were associated with irregularities in shell formation, as shown by scanning electron microscopy (SEM), indicating that the formation of the first shelled embryo, a key step in mussel development, represents a sensitive target for BPA. Similar results were obtained with the natural estrogen 17β-estradiol. The results demonstrate that BPA and E₂ can affect Mytilus early development through dysregulation of gene transcription.

Increased levels of bisphenol A (BPA) in Thai girls with precocious puberty

BACKGROUND

Reports on the secular trend of pubertal onset indicate a recent earlier start especially in girls. Bisphenol A (BPA), which posses estrogenic activity, might be a cause of advanced puberty. The objective of the study was to determine the association between BPA and advanced puberty.

METHODS

A cross-sectional study was conducted in patients with advanced puberty (n=41) compared to age-matched controls (n=47). Anthropometric measurements, estradiol, basal and gonadotropin releasing hormone (GnRH)-stimulated follicle stimulating hormone (FSH) and luteinizing hormone (LH) levels, uterine sizes, ovarian diameters and bone ages were obtained. Urinary BPA concentrations were analyzed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC/MSMS) with the lower limit of quantification (LLOQ) of 0.05 ng/mL.

RESULTS

The median adjust-BPA concentration in advanced puberty group was higher than in control groups [1.44 vs. 0.59 μg/g creatinine (Cr): p<0.05]. We also found that the median adjust-BPA concentration in girls with advanced puberty who were overweight/obese, was greater than in the normal pubertal overweight/obese girls (1.74 vs. 0.59 μg/g Cr: p<0.05), and was in the same trend among normal weight girls with advanced and normal puberty (0.83 vs. 0.49 μg/g Cr: p=0.09), but not statistically significant.

CONCLUSIONS

The present findings suggest that BPA exposure appears to be related to an earlier age at onset of puberty especially in obese girls.

Impact of Low Dose Oral Exposure to Bisphenol A (BPA) on the Neonatal Rat Hypothalamic and Hippocampal Transcriptome: A CLARITY-BPA Consortium Study

Bisphenol A (BPA) is an endocrine disrupting, high volume production chemical found in a variety of products. Evidence of prenatal exposure has raised concerns that developmental BPA may disrupt sex-specific brain organization and, consequently, induce lasting changes on neurophysiology and behavior. We and others have shown that exposure to BPA at doses below the no-observed-adverse-effect level can disrupt the sex-specific expression of estrogen-responsive genes in the neonatal rat brain including estrogen receptors (ERs). The present studies, conducted as part of the Consortium Linking Academic and Regulatory Insights of BPA Toxicity program, expanded this work by examining the hippocampal and hypothalamic transcriptome on postnatal day 1 with the hypothesis that genes sensitive to estrogen and/or sexually dimorphic in expression would be altered by prenatal BPA exposure. NCTR Sprague-Dawley dams were gavaged from gestational day 6 until parturition with BPA (0-, 2.5-, 25-, 250-, 2500-, or 25 000-μg/kg body weight [bw]/d). Ethinyl estradiol was used as a reference estrogen (0.05- or 0.5-μg/kg bw/d). Postnatal day 1 brains were microdissected and gene expression was assessed with RNA-sequencing (0-, 2.5-, and 2500-μg/kg bw BPA groups only) and/or quantitative real-time PCR (all exposure groups). BPA-related transcriptional changes were mainly confined to the hypothalamus. Consistent with prior observations, BPA induced sex-specific effects on hypothalamic ERα and ERβ (Esr1 and Esr2) expression and hippocampal and hypothalamic oxytocin (Oxt) expression. These data demonstrate prenatal BPA exposure, even at doses below the current no-observed-adverse-effect level, can alter gene expression in the developing brain.

Bisphenol A exposure alters release of immune and developmental modulators and expression of estrogen receptors in human fetal lung fibroblasts

Bisphenol A (BPA) has been shown to exert biological effects through estrogen receptor (ER)-dependent and ER-independent mechanisms. Recent studies suggest that prenatal exposure to BPA may increase the risk of childhood asthma. To investigate the underlying mechanisms in the actions of BPA, human fetal lung fibroblasts (hFLFs) were exposed to varying doses of BPA in culture for 24hr. Effects of BPA on localization and uptake of BPA, cell viability, release of immune and developmental modulators, cellular localization and expression of ERα, ERβ and G-protein coupled estrogen receptor 30 (GPR30), and effects of ERs antagonists on BPA-induced changes in endothelin-1 (ET-1) release were examined. BPA at 0.01-100μmol/L caused no changes in cell viability after 24hr of exposure. hFLFs expresses all three ERs. BPA had no effects on either cellular distribution or protein expression of ERα, however, at 100μmol/L (or 23μmol/L intracellular BPA) increased ERβ protein levels in the cytoplasmic fractions and GPR30 protein levels in the nuclear fractions. These paralleled with increased release of growth differentiation factor-15, decreased phosphorylation of nuclear factor kappa B p65 at serine 536, and decreased release of ET-1, interleukin-6, and interferon gamma-induced protein 10. ERs antagonists had no effects on BPA-induced decrease in ET-1 release. These data suggest that BPA at 100μmol/L altered the release of immune and developmental modulators in hFLFs, which may negatively influence fetal lung development, maturation, and susceptibility to environmental stressors, although the role of BPA in childhood asthma remains to be confirmed in in vivo studies.

Identification of a Sensitive Period for Developmental Programming That Increases Risk for Uterine Leiomyoma in Eker Rats

Epidemiological and experimental animal studies have shown that exposure to xenoestrogens during reproductive tract development reprograms target tissues, leading to increased disease risk later in adult life. To understand what defines the critical risk period for this effect, termed developmental programming, the authors assess the sensitivity of the female reproductive tract to developmental programming during various stages of neonatal development. Eker rats, which are predisposed to develop uterine leiomyoma because of a germ-line defect in the tuberous sclerosis complex 2 (Tsc-2) tumor suppressor gene, were exposed to the xenoestrogen diethylstilbestrol (DES) on either postnatal days 3 to 5, 10 to 12, or 17 to 19, 3 important periods of reproductive tract development and differentiation. Developmental programming was observed in both carrier (Tsc-2(Ek/+)) and wild-type (Tsc-2(+/+)) rats exposed to DES at days 3 to 5 and days 10 to 12 but not in rats exposed at days 17 to 19. Developmental programming resulted in increased tumor suppressor gene penetrance in Tsc-2(Ek/+) females relative to vehicle controls. In contrast, DES exposure at days 17 to 19 did not significantly increase the incidence of uterine leiomyoma in carrier females, indicating that the window of susceptibility had closed by this time. Gene expression analysis to determine what defined the susceptible (days 3-5 and days 10-12) versus resistant (days 17-19) periods revealed that in adult myometrium, expression of the estrogen-responsive genes calbindin D(9)K and progesterone receptor had been reprogrammed in females exposed to DES at days 3 to 5 and days 10 to 12 but not in those exposed at days 17 to 19. Reprogramming in response to DES exposure resulted in a hyperresponsiveness to ovarian hormones and could be prevented by ovariectomy prior to sexual maturity. Furthermore, in the neonatal uterus, DES was equally effective at inducing transcription of estrogen-responsive genes during both sensitive and resistant periods, indicating that resistance to developmental programming was not due to an inability of the estrogen receptor to transactivate gene expression. Interestingly, the resistant period coincided with the time at which reproductive tract tissues are exposed to endogenous estrogen, suggesting that target tissues are most vulnerable to developmental programming during the period in which they would normally be maintained in an estrogen-naïve state.