Bisphenol A-induced apoptosis of cultured rat Sertoli cells

Bisphenol A and its structural analogues exhibit differential potential to induce mitochondrial dysfunction and apoptosis in human granulosa cells

Bisphenol A (BPA) is an endocrine disruptor strongly associated with ovarian dysfunction. BPA is being substituted by structurally similar chemicals, such as bisphenol S (BPS), bisphenol F (BPF), and bisphenol AF (BPAF). However, the toxicity of these analogues in female reproduction remains largely unknown. This study evaluated the effects of BPA and its analogues BPS, BPF, and BPAF on the mitochondrial mass and function, oxidative stress, and their potential to induce apoptosis of human granulosa cells (KGN cells). BPA and its analogues, especially BPA and BPAF, significantly decreased mitochondrial activity and cell viability. The potential of bisphenols to reduce mitochondrial mass and function differed in the following order: BPAF > BPA > BPF > BPS. Flow cytometry revealed that exposure to bisphenols significantly increased mitochondrial ROS levels and increased mitochondrial Ca2+ levels. Thus, bisphenols exposure causes mitochondrial stress in KGN cells. At the same time, bisphenols exposure significantly induced apoptosis. These results thus emphasize the toxicity of these bisphenols to cells. Our study suggests the action mechanism of BPA and its analogues in damage caused to ovarian granulosa cells. Additionally, these novel analogues may be regrettable substitutes, and the biological effects and potential risks of BPA alternatives must be evaluated.

Comparison of the Effect of BPA and Related Bisphenols on Membrane Integrity, Mitochondrial Activity, and Steroidogenesis of H295R Cells In Vitro

Bisphenol A (BPA) is an endocrine-disruptive chemical that is widely utilized in the production of polycarbonate plastic and epoxy resin, which are used to make a wide range of consumer products, food and drink containers, and medical equipment. When the potential risk of BPA emerged, it was substituted by allegedly less harmful substitutes such as bisphenols S, F, B, and AF. However, evidence suggests that all bisphenols can have endocrine-disruptive effects, while the extent of these effects is unknown. This study aimed to determine effect of BPA, BPAF, BPB, BPF, and BPS on viability and steroidogenesis in human adrenocortical carcinoma cell line in vitro. The cytotoxicity of bisphenols was shown to be considerable at higher doses. However, at low concentrations, it improved viability as well as steroid hormone secretion, indicating that bisphenols have a biphasic, hormetic effect in biological systems. The results are consistent with the hypothesis that bisphenols selectively inhibit some steroidogenic enzymes. These findings suggest that bisphenols have the potential to disrupt cellular steroidogenesis in humans, but substantially more detailed and systematic research is needed to gain a better understanding of the risks associated with bisphenols and their endocrine-disrupting effect on humans and wildlife.

High Content Imaging Analyses of the Effects of Bisphenols and Organophosphate Esters on TM4 Mouse Sertoli Cells

The endocrine disruptive effects of bisphenol A (BPA) and brominated flame retardants (BDE-47) have led to restrictions to their use and increased the pressure to identify safe replacements for these chemicals. Although there is evidence that some of these alternatives may be toxic to spermatogonial and Leydig cells, little is known about the toxicity of emerging replacements on Sertoli cells, one of the major testicular cell types. We used high-content imaging to compare the effects of legacy chemicals, BPA and BDE-47, to their corresponding replacements. TM4 Sertoli cells were exposed for 48 h to each chemical (0.001-100 μM) followed by cytotoxicity and phenotypic endpoint assessment. The benchmark concentration (BMC) potency ranking for bisphenols based on cytotoxicity was BPTMC>BPM > BPAF>BPF > BPS > BPA. Human administered equivalent dose (AED) determination ranked BPS as most potent alternative replacement studied. The BMC potency ranking of BDE-47 and organophosphate esters based on cytotoxicity was TDtBPP>BDMPP>TBOEP>TDCPP>TMPP>TPHP> BDE47 > IPPP=BPDP = TCPP. Additionally, TM4 cell exposure to BDE-47 increased Calcein intensity (57.9 μM) and affected lysosomes (21.6 μM), while exposure to TPHP and TMPP resulted in cellular oxidative stress changes at BMC values as low as 0.01 μM and 0.4 μM, respectively. Overall bioactivity considerations of the chemicals on TM4 via ToxPi analyses and AED modeling further validated emerging replacements as highly potent chemicals in comparison to BPA and BDE-47. These findings demonstrate that many bisphenol and flame retardant replacements are more potent in Sertoli cells than the legacy chemical they are replacing, and that phenotypic parameter assessment is an effective tool in chemical toxicity assessment.

Male reproductive toxicity of zearalenone-meta-analysis with mechanism review

Zearalenone (ZEA) is an oestrogen-like mycotoxin produced by Fusarium fungi, which has a considerable impact on human and animal health and results in substantial economic losses worldwide. This study aimed to demonstrate the reproductive injury induced by ZEA in rodents. We conducted a rigorous meta-analysis of the related literature via PubMed, Embase, and Web of Science. The scope of the study includes the following: development of reproductive organs, serum testosterone, oestradiol, and luteinizing hormone (LH) levels; parameters of Leydig cells; and parameters of semen. In total, 19 articles were reviewed. Compared with the control group, the increased relative epididymis weight, increased serum oestradiol level, and decreased LH levels in the prenatally exposed group were observed. In pubertal and adult rodents, the relative testicular weight, serum oestradiol level, Leydig cell number, and percentage of ST (+) Leydig cells decreased under ZEA exposure. In rodents at all ages, decreased serum testosterone level, sperm concentration, sperm motility rate, and increased serum deformity rate were observed in exposed groups compared with control groups. Although subgroup analysis failed to identify a clear dose-response relationship between ZEA exposure and reproductive system damage in male rodents, we still managed to confirm that zearalenone could decrease the serum testosterone level at the dosage of 50 mg/kg*day, 1.4 mg/kg*day, and 84 mg/kg*day, of prenatal, pubertal, and mature rodents respectively; pubertal zearalenone exposure impairs the quality and quantity of sperms of rodents at the dosage of 1.4 mg/kg*day and mature zearalenone exposure has the same effect at the dosage of 84 mg/kg*day. In conclusion, we found that ZEA exposure can cause considerable damage to the reproductive system of rodents of all ages. While the exact underlying mechanism of ZEA-induced toxicity in the reproductive system remains largely unknown, the theories of oestrogen-like effects and oxidative stress damage are promising.

BPA and BPA alternatives BPS, BPAF, and TMBPF, induce cytotoxicity and apoptosis in rat and human stem cells

Bisphenol A (BPA) is a ubiquitous industrial chemical found in everyday plastic products and materials. Due to scientific findings on the reproductive, developmental, and cellular defects caused by BPA and heightened public awareness, manufacturers have begun to use new chemicals in place of BPA in "BPA-free" products. These alternatives are chemical analogs of BPA and include dozens of new compounds that have undergone relatively little testing and oversight, including: bisphenol S (BPS), bisphenol AF (BPAF), and the recently developed tetramethyl bisphenol F (TMBPF; the monomer of valPure V70). Here, we used adult female rat adipose-derived stem cells (rASCs) and human mesenchymal stem cells (hMSCs) to compare the toxicities and potencies of these BPA alternatives in vitro. Rat and human stem cells were exposed to BPA (1-10 μM), 17β-estradiol (E2; 10 μM), BPS (1-100 μM), BPAF (3×10^-4-30 μM), TMBPF (0.01-50 μM), or control media alone (with 0.01% ethanol) for varying time intervals from 10 min to 24 h. We found significantly decreased cell viability and massive apoptosis in rat and human stem cells treated with each BPA analog, as early as 10 min of exposure, and at low, physiologically relevant doses. BPAF showed extreme cytotoxicity in a dose-dependent manner (LC₅₀ =0.014 μM (rASCs) and 0.009 μM (hMSCs)), whereas TMBPF showed a bimodal response, with low and high concentrations being the most toxic (LC₅₀ =0.88 μM (rASCs) and 0.06 μM (hMSCs)). Activated caspase-6 levels increased in nearly all cells treated with the BPA analogs indicating the majority of cell death was due to caspase-6-mediated apoptosis. These results in both rat and human stem cells underscore the toxicity and potency of these BPA analogs, and establish a rank order of potency of: BPAF>TMBPF>BPA>BPS. Further, these and other recent findings indicate that these newer BPA analogs may be 'regrettable substitutions,' being worse than the original parent compound and lacking proper testing and regulation. This work brings to light the need for further toxicological characterization, better regulation, greater public awareness, and the development of safer, more sustainable chemicals and non-plastic products.

Evaluation of testicular toxicity upon fetal exposure to bisphenol A using an organ culture method

Humans are exposed to a multitude of endocrine disruptor chemicals (EDCs) that can interfere with the action of endogenous hormones and the normal development of reproductive organs. Bisphenol A (BPA) is one of the most common EDCs found in the environment. Here, we evaluated BPA toxicity on fetal testes using an in vitro organ culture system. Mouse fetal testes sampled at 15.5 days post coitus were cultured in a medium containing BPA for 5 days. The number of germ cells was reduced by BPA treatment, whereas the number of Sertoli cells was slightly increased by BPA at the highest dose (100 μM). Consistently, BPA treatment reduced the protein and gene expression levels of germ cell markers, but it increased the expression levels of Sertoli cell markers. The expression levels of fetal Leydig cell markers such as Cyp11a1, Thbs2, Cyp17a1, and Pdgf-α were significantly increased, whereas those of adult Leydig cell markers such as Hsd17b3, Ptgds, Sult1e1, Vcam1, and Hsd11b1 were decreased in the testes exposed to BPA. Generally, Notch signaling restricts Leydig cell differentiation from progenitor cells during fetal testis development. The expression levels of Notch1, Notch2, Notch3, Hes1, Ptch1, Jag1, Jag2, c-Myc, Hey1, and Hey2, which are involved in Notch signaling, were markedly higher in BPA-treated fetal testes than in the controls, indicating that BPA interrupts fetal Leydig cell development. BPA also disrupted steroidogenesis in the fetal testis organ culture system. In conclusion, our study showed that BPA inhibits fetal germ cell growth, Leydig cell development, and steroidogenesis.

Bisphenol A induces apoptosis through GPER-dependent activation of the ROS/Ca2+-ASK1-JNK pathway in human granulosa cell line KGN

Bisphenol A (BPA) is widely distributed in the environment and human surroundings and is closely related to the occurrence of many chronic diseases including female infertility. Although BPA-induced granulosa cell apoptosis has been widely reported, the underlying mechanisms remain unknown. In this study, we evaluated the induction effect of BPA exposure on apoptosis and mechanisms of regulation in KGN cells (a human granulosa-like tumor cell line). Our results indicated that BPA induced apoptosis of KGN cells in a dose- and time-dependent manner. BPA exposure significantly promoted the expression of pro-apoptotic proteins and decreased mitochondrial membrane potential. We also observed that high concentrations of BPA significantly promoted the generation of reactive oxygen species (ROS) and calcium ion (Ca²⁺) accumulation. The involvement of ROS and Ca²⁺ in BPA-induced KGN cell apoptosis was confirmed by pretreatment with NAC (an antioxidant) and BAPTA-AM (a calcium chelator). After inhibitors pretreatment to block the corresponding signaling pathways, it was found that BPA-induced phosphorylation of JNK and ASK1 proteins and apoptosis of KGN cells were significantly inhibited. We pretreated with G15 (a GPER inhibitor) and found that BPA-induced ROS generation and Ca²⁺ accumulation and apoptosis were significantly inhibited. These results suggest that BPA exposure induces KGN cell apoptosis through GPER-dependent activation of the ROS/Ca²⁺-ASK1-JNK signaling pathway. Our study provides mechanisms by which BPA induced apoptosis of granulosa cells and ovarian dysfunction.

Bisphenol A Deranges the Endocannabinoid System of Primary Sertoli Cells with an Impact on Inhibin B Production

Bisphenol A (BPA) is an endocrine disruptor that negatively affects spermatogenesis, a process where Sertoli cells play a central role. Thus, in the present study we sought to ascertain whether BPA could modulate the endocannabinoid (eCB) system in exposed mouse primary Sertoli cells. Under our experimental conditions, BPA turned out to be cytotoxic to Sertoli cells with an half-maximal inhibitory concentration (IC₅₀) of ~6.0 µM. Exposure to a non-cytotoxic dose of BPA (i.e., 0.5 μM for 48 h) increased the expression levels of specific components of the eCB system, namely: type-1 cannabinoid (CB₁) receptor and diacylglycerol lipase-α (DAGL-α), at mRNA level, type-2 cannabinoid (CB₂) receptor, transient receptor potential vanilloid 1 (TRPV1) receptors, and DAGL-β, at protein level. Interestingly, BPA also increased the production of inhibin B, but not that of transferrin, and blockade of either CB₂ receptor or TRPV1 receptor further enhanced the BPA effect. Altogether, our study provides unprecedented evidence that BPA deranges the eCB system of Sertoli cells towards CB₂- and TRPV1-dependent signal transduction, both receptors being engaged in modulating BPA effects on inhibin B production. These findings add CB₂ and TRPV1 receptors, and hence the eCB signaling, to the other molecular targets of BPA already known in mammalian cells.

Early-life exposure to bisphenol A and reproductive-related outcomes in rodent models: a systematic review and meta-analysis

We performed this meta-analysis to elucidate the associations between early-life BPA exposure and reproductive-related outcome indicators. The standardized mean differences (SMDs) and its 95% confidence intervals (CIs) were measured by fixed-effects or random-effects models. The results revealed that BPA exposure at extremely-high dose (>50mg/kg/day) was significantly associated with negative reproductive-related outcomes (Prostate weight: SMD: -4.21; 95% Cl: -5.97, -2.44; Testis weight: SMD: -1.92; 95% Cl: -2.61, -1.23; Epididymis weight: SMD: -2.16; 95% Cl: -3.47, -0.86; Daily sperm production; SMD: -1.90; 95% Cl: -3.27, -0.53; Epididymal sperm count; SMD: -3.42; 95% Cl: -3.87, -2.97). Meanwhile, regardless of the dose, early-life BPA exposure could result in an adverse effect on sperm parameters of F1 generation male rodents at any period. Also, we found the non-monotonic dose response curves of BPA in specific tissues or organs, which may challenge the traditional mindset of "safe dose". This study demonstrated that bisphenol A exposure was relevant to adverse reproductive-related outcomes at specially appointed dose and period of life. Yet the assumption that no adverse effects can occur below the "safe" dose is suspected.

Bisphenols Threaten Male Reproductive Health via Testicular Cells

Male reproductive function and health are largely dependent on the testes, which are strictly regulated by their major cell components, i. e., Sertoli, Leydig, and germ cells. Sertoli cells perform a crucial phagocytic function in addition to supporting the development of germ cells. Leydig cells produce hormones essential for male reproductive function, and germ cell quality is a key parameter for male fertility assessment. However, these cells have been identified as primary targets of endocrine disruptors, including bisphenols. Bisphenols are a category of man-made organic chemicals used to manufacture plastics, epoxy resins, and personal care products such as lipsticks, face makeup, and nail lacquers. Despite long-term uncertainty regarding their safety, bisphenols are still being used worldwide, especially bisphenol A. While considerable attention has been paid to the effects of bisphenols on health, current bisphenol-related reproductive health cases indicate that greater attention should be given to these chemicals. Bisphenols, especially bisphenol A, F, and S, have been reported to elicit various effects on testicular cells, including apoptosis, DNA damage, disruption of intercommunication among cells, mitochondrial damage, disruption of tight junctions, and arrest of proliferation, which threaten male reproductive health. In addition, bisphenols are xenoestrogens, which alter organs and cells functions via agonistic or antagonistic interplay with hormone receptors. In this review, we provide in utero, in vivo, and in vitro evidence that currently available brands of bisphenols impair male reproductive health through their action on testicular cells.

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).

Companion animals get close to the toxic aspects of antropogenic world: cytotoxicity of phthalates and bisphenol A on dog testicular primary cells

Phthalates, which are among the most abundant plasticizers, have detrimental effects on the reproductive system. Similar to human, dogs are prominently exposed to phthalates in daily routines at low concentrations; while toys, training devices and commercial dog foods are considered as the primary sources of exposure. This study aimed to reveal and compare the cytotoxic effects of selected phthalates (Benzyl butyl phthalate (BBP), Diethyl phthalate (DEP), Bis (2-ethylhexyl) phthalate (DEHP), Di-'isobutyl' phthalate (DIBP), Di-'isodecyl' phthalate (-DIDP) Di-'isononyl' phthalate (DINP), Dimethyl phthalate (DMP), Di-n-octyl phthalate (DNOP)), and Bisphenol A (BPA) following 24 h exposure on primary testicular parenchymal cells of dog in vitro at concentrations between 0.001 and 2.5 nM. According to cytotoxicity results, DEHP was found to be the most toxic phthalate with IC₅₀ at 22.53 µM; while DMP was the least (169.17 nM). IC₅₀ of BPA was 161.81 nM, less than the average (61.95 nM) of phthalates. In addition, dog primary testicular cells were found more susceptible to the high molecular weight phthalates (DNOP, DEHP, DINP, DIDP) than low molecular weight phthalates (DMP, DEP, DIBP, BBP). Further studies should focus on morphological, physiological and molecular differences to comprehend the mechanisms involved as well as decreasing the risk for impaired spermatogenesis caused by environmental toxicants in companion animal medicine.

The apoptotic effects of bisphenol A exposure on the rat ovary: an experimental study

Bisphenol A (BPA) is a key endocrine-disrupting chemical (EDC) in the manufacturing industry. It is found in the structure of compounds such as polycarbonate and epoxy in combination with other chemicals. Our objective was to investigate the effect of BPA on rat ovaries. A total of 32 female rats were divided into four equal groups: In group 1 (control), vehicle was administered; in group 2, BPA 50 μg/day was administered intraperitoneally; in group 3, BPA 100 mg/kg/day was administered intraperitoneally; and in group 4, BPA 100 mg/kg/day and vitamin C (50 mg/kg) were administered intraperitoneally, while vitamin E (50 mg/kg) was administered intramuscularly. Thirty days after the treatment, the effects of BPA on the ovaries were evaluated by terminal deoxynucleotidyltransferase [TdT]-mediated dUTP-biotin nick end labeling (TUNEL) assay. There was no difference in the number of apoptotic cells between group 2 and group 4. In addition, there was no significant difference between control group and group 2, 4. However, the number of apoptotic cells per unit area was significantly increased in group 3 compared with all groups (p < 0.01, p < 0.05). In conclusion, this study showed that high doses of BPA (100 mg/kg/day) have a toxic effect on the ovaries. The fact that the number of apoptotic cells in the group administered with high dose of BPA + 50 mg/kg/day vitamin C + 50 mg/kg/day vitamin E was lower than that of the high-dose BPA-administered group shows that these vitamins may have a protective effect.

Sequential testicular atrophy involves changes in cellular proliferation and apoptosis associated with variations in aromatase P450 expression levels in Irs-2-deficient mice

Insulin receptor substrate 2 (Irs-2) is an intracellular protein susceptible to phosphorylation after activation of the insulin receptor. Its suppression affects testis development and its absence induces peripheral resistance to insulin. The aim of this study was to identify changes induced by the deletion of Irs-2 in the testicular structure and by the altered expression of cytochrome P450 aromatase, a protein necessary for the development and maturation of germ cells. Adult knockout (KO) mice (Irs-2^-/- , 6 and 12 weeks old) and age-matched wild-type (WT) mice were used in this study. Immunohistochemistry and Western blot analyses were performed to study proliferation (PCNA), apoptosis (active caspase-3) and P450 aromatase expression in testicular histological sections. Deletion of Irs-2 decreased the number of epithelial cells in the seminiferous tubule and rete testis. Aberrant cells were frequently detected in the epithelia of Irs-2^-/- mice, accompanied by variations in spermatogonia, which were shown to exhibit small hyperchromatic nuclei as well as polynuclear and anuclear structures. The amount of cell proliferation was significantly lower in Irs-2^-/- mice than in WT mice, whereas apoptotic processes were more common in Irs-2^-/- mice. Aromatase P450 reactivity was higher in 6-week-old KO mice than in WT mice of the same age and was even higher at 12 weeks. Our results suggest that Irs-2 is a key element in spermatogenesis because silencing Irs-2 induces the sequential development of testicular atrophy. The effects are observed mainly in germ cells present in the seminiferous tubule, which may be due to changes in cytochrome P450 aromatase expression.

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 effects of lead on porcine neonatal Sertoli cells in vitro

Environmental pollution is one of the main factors responsible for reducing fertility in males. Lead is one of the major heavy metal contaminants that impairs several organs; it preferentially accumulates in male reproductive organs and alters sperm quality both in vivo and in vitro. However, the underlying mechanisms remain unclear. Sertoli cells (SCs) provide structural and physiological support to spermatogenic cells within seminiferous tubules. Therefore, changes in SCs affect the developing germ cells and alter spermatogenesis. This study aimed to assess whether exposure to subtoxic doses of adversely affects SC functioning in higher mammals. Purified and functional porcine neonatal SCs were exposed to lead acetate at three different concentrations. Lead exposure decreased the mRNA expression and protein levels of inhibin B and anti-Mullerian hormone (AMH) compared to control, indicating loss of FSH-r integrity in terms of 17-β-oestradiol production under FSH stimulation. In addition, we observed an increase in the mRNA levels of Akt and mTOR, and the phosphorylation of p38 and Akt in SCs exposed to lead at all concentrations compared to unexposed control SCs. In conclusion, lead is toxic to SCs, even at low concentrations, and is expected to alter spermatogenesis.

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

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

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.

An old culprit but a new story: bisphenol A and "NextGen" bisphenols

The concept that developmental events shape adult health and disease was sparked by the recognition of a link between maternal undernutrition and coronary disease in adults. From that beginning, a new field-the developmental origins of health and disease-emerged, and attention has focused on the effects of a wide array of developmental perturbations. Exposure to endocrine-disrupting chemicals has been of particular interest, and a ubiquitous environmental contaminant bisphenol A (BPA) has become the endocrine-disrupting chemical poster child. Bisphenol A has been the subject of intense investigation for nearly two decades, and exposure effects have been described in hundreds of experimental, epidemiological, and clinical studies. From the standpoint of reproductive health, the findings are particularly important, as they suggest that the ovary, testis, and reproductive tract in both sexes are targets of BPA action. The findings and the media and regulatory attention garnered by them have generated increasing public concern and resulted in legislative bans on BPA in some countries. The subsequent introduction of BPA-free products, although a masterful marketing strategy, is in reality only the beginning of a new and complex chapter of the BPA story. In this review we attempt to summarize what we have learned about the reproductive effects of BPA, present the reasons why studying the effects of this chemical in humans is no longer sufficient, and outline the challenges that the growing array of next generation bisphenols represents to clinicians, researchers, federal agencies, and the general public.

Zearalenone and 17 β-estradiol induced damages in male rats reproduction potential; evidence for ERα and ERβ receptors expression and steroidogenesis

The estrogen receptors (ERs)-dependent effects of Zearalenone (ZEA) on structure and function of the testis as well as sperm parameters were compared with 17-β estradiol as endogenous substance. For this purpose, 30 mature male rats were assigned into five groups as; control (appropriate volume of normal saline, i. p.), ZEA-received (1, 2 and 4 mg/kg, b. w., i. p.) and 17 β-estradiol (E2)-received (appropriate dose of 0.1 mg/kg, i. p.). Following 28 days, the mRNA levels of estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) in the testis and sperms and the expression of them at protein levels in testicles were estimated. Mitochondrial content of germinal epithelium, Leydig cells steroid foci, sperm quality parameters and serum level of testosterone were assessed. Fluorescent techniques were used for analyzing apoptosis and mRNA damage in necrotic cells. ZEA reduced the mRNA and protein levels of ERα in testicles while up-regulated the ERβ expression. The mRNA level of ERα decreased in sperms of ZEA and E2-received animals. No remarkable changes were found for ERβ expression in sperms from ZEA and E2-received animals. ZEA reduced the Leydig cells steroidogenesis, mitochondrial content of germinal cells and elevated cellular apoptosis and necrosis dose-dependently. E2 reduced the testosterone concentration, enhanced the apoptosis and reduced sperm quality. Our data suggest that ZEA-induced detrimental effects in the structure and function of testis, may attribute to changing the ERs expression at mRNA and translational level.

Melatonin controlled apoptosis and protected the testes and sperm quality against bisphenol A-induced oxidative toxicity

Epidemiological reports have indicated a correlation between the increasing bisphenol A (BPA) levels in the environment and the incidence of male infertility. In this study, the protective effects of melatonin on BPA-induced oxidative stress and apoptosis were investigated in the rat testes and epididymal sperm. Melatonin (10 mg/kg body weight (bw)) was injected concurrently with BPA (50 mg/kg bw) for 3 and 6 weeks. The administration of BPA significantly increased oxidative stress in the testes and epididymal sperm. This was associated with a decrease in the serum testosterone level as well as sperm quality, chromatin condensation/de-condensation level, and the percentage of haploid germ cells in the semen. BPA administration caused a significant increase in apoptosis accompanied by a decrease in the expression of the antiapoptotic proteins Bcl-2 in the testes and epididymal sperm. The concurrent administration of melatonin decreased oxidative stress by modulating the levels of glutathione, superoxide dismutase, and catalase as well as the malondialdehyde and hydrogen peroxide concentrations in the testes and sperm. Melatonin sustained Bcl-2 expression and controlled apoptosis. Furthermore, melatonin maintained the testosterone levels, ameliorated histopathological changes, increased the percentages of seminal haploid germ cells, and protected sperm chromatin condensation process, indicating appropriate spermatogenesis with production of functional sperm. In conclusion, melatonin protected against BPA-induced apoptosis by controlling Bcl-2 expression and ameliorating oxidative stress in the testes and sperm. Thus, melatonin is a promising pharmacological agent for preventing the potential reproductive toxicity of BPA following occupational or environmental exposures.

The role of Pten/Akt signaling pathway involved in BPA-induced apoptosis of rat Sertoli cells

Bisphenol-A (BPA), one of endocrine-disrupting chemicals, is a male reproductive toxicant. Previous studies have revealed the direct cytotoxicity of BPA in many cultured cells, such as mitotic aneuploidy in embryonic cells and somatic cells, and apoptosis in neurons and testicular Sertoli cells. To understand the action of BPA and assess its risk, the Pten/Akt pathway was investigated in cultured Sertoli cells to elucidate the mechanism of the reproductive effects of BPA. The results showed that over 50 μM BPA treatment could decrease the viability of Sertoli cells and cause more apoptosis. In addition, BPA could induce the increase in mRNA levels of Pten and Akt. The protein level of Pten was increased; however, the protein levels of phospho-Akt and procaspase-3 were decreased after BPA exposure. Taken together, observed results suggested that the Pten/Akt pathway might be involved in the apoptotic effects of BPA on Sertoli cells.

Sertoli cells are the target of environmental toxicants in the testis - a mechanistic and therapeutic insight

INTRODUCTION

Sertoli cells support germ cell development in the testis via an elaborate network of cell junctions that confers structural, communicating, and signaling support. However, Sertoli cell junctions and cytoskeletons are the target of environmental toxicants. Because germ cells rely on Sertoli cells for the provision of structural/functional/nutritional support, exposure of males to toxicants leads to germ cell exfoliation due to Sertoli cell injuries. Interestingly, the molecular mechanism(s) by which toxicants induce cytoskeletal disruption that leads to germ cell exfoliation is unclear, until recent years, which are discussed herein. This information can possibly be used to therapeutically manage toxicant-induced infertility/subfertility in human males.

AREAS COVERED

In this review, we provide a brief update on the use of Sertoli cell system developed for rodents and humans in vitro, which can be deployed in any research laboratory with minimal upfront setup costs. These systems can be used to collect reliable data applicable to studies in vivo. We also discuss the latest findings on the mechanisms by which toxicants induce Sertoli cell injury, in particular cytoskeletal disruption. We also identify candidate molecules that are likely targets of toxicants.

EXPERT OPINION

We provide two hypothetical models delineating the mechanism by which toxicants induce germ cell exfoliation and blood-testis barrier disruption. We also discuss molecules that are the targets of toxicants as therapeutic candidates.

Implications of Sertoli cell induced germ cell apoptosis to testicular pathology

After exposure to toxicants, degenerating germ cells represents the most common testicular histopathological alteration, regardless of the mechanism of toxicity. Therefore, deciphering the primary toxicant cellular target and mechanism of action can be extremely difficult. However, most testicular toxicants display a cell-specific and a stage-specific pattern of damage, which is the best evidence for identifying the primary cellular target (i.e. germ cell, Sertoli cell, peritubular myoid cell, or Leydig cell). Some toxicant-induced Sertoli cell injury presents with germ cell apoptosis occurring primarily in spermatocytes in rats in stages XI-XIV, I and II. Although some toxicants result in spermatid degeneration and apoptosis, it is still unclear if spermatid apoptosis is a result of Sertoli cell-selective apoptosis or a direct effect of toxicants on spermatids, therefore if this is seen as the earliest change, one cannot infer the mechanism of apoptosis. This review summarizes some of the distinguishing features of Sertoli cell-induced germ cell apoptosis and the associated mechanisms of cell death to provide the toxicologist observing similar cell death, with evidence about a potential mode of action.

BPA-induced apoptosis of rat Sertoli cells through Fas/FasL and JNKs/p38 MAPK pathways

Bisphenol-A was examined for its effects on cultured Sertoli cells established from 18 to 22-day-old rat testes. Results indicated that exposure to BPA (0, 30, 50 and 70 μM) decreased the cell viability in a concentration-dependent manner and induced cell apoptosis. Apoptosis-caused cell death was observed in cells exposed to 50 and 70 μM BPA. The mRNA expressions of Fas, FasL and caspase-3 were all elevated, and the protein expressions of FasL and cleaved caspase-3 were also increased. In addition, levels of phosphorylation of JNKs/p38 MAPK were also increased and then activated JNKs/p38 MAPK up regulated target gene expressions, such as c-jun and CHOP. Translocation of NF-κB into nuclei indicated the activation of NF-κB after treatment with BPA. Taken together, observed results suggest that BPA induces apoptosis of Sertoli cells by the activation of JNKs/p38 MPAK and translocation of NF-κB, and Fas/FasL system plays a critical role in the initiation of apoptosis.

Exposure to low-dose bisphenol A impairs meiosis in the rat seminiferous tubule culture model: a physiotoxicogenomic approach

BACKGROUND

Bisphenol A (BPA) is one of the most widespread chemicals in the world and is suspected of being responsible for male reproductive impairments. Nevertheless, its molecular mode of action on spermatogenesis is unclear. This work combines physiology and toxicogenomics to identify mechanisms by which BPA affects the timing of meiosis and induces germ-cell abnormalities.

METHODS

We used a rat seminiferous tubule culture model mimicking the in vivo adult rat situation. BPA (1 nM and 10 nM) was added to the culture medium. Transcriptomic and meiotic studies were performed on the same cultures at the same exposure times (days 8, 14, and 21). Transcriptomics was performed using pangenomic rat microarrays. Immunocytochemistry was conducted with an anti-SCP3 antibody.

RESULTS

The gene expression analysis showed that the total number of differentially expressed transcripts was time but not dose dependent. We focused on 120 genes directly involved in the first meiotic prophase, sustaining immunocytochemistry. Sixty-two genes were directly involved in pairing and recombination, some of them with high fold changes. Immunocytochemistry indicated alteration of meiotic progression in the presence of BPA, with increased leptotene and decreased diplotene spermatocyte percentages and partial meiotic arrest at the pachytene checkpoint. Morphological abnormalities were observed at all stages of the meiotic prophase. The prevalent abnormalities were total asynapsis and apoptosis. Transcriptomic analysis sustained immunocytological observations.

CONCLUSION

We showed that low doses of BPA alter numerous genes expression, especially those involved in the reproductive system, and severely impair crucial events of the meiotic prophase leading to partial arrest of meiosis in rat seminiferous tubule cultures.

Adverse effects of bisphenol A on male reproductive function

BPA is a ubiquitous environmental contaminant, resulting mainly from manufacturing,use or disposal of plastics of which it is a component, and the degradation of industrial plastic-related wastes. Growing evidence from research on laboratory animals, wildlife, and humans supports the view that BPA produces an endocrine disrupting effect and adversely affects male reproductive function. To better understand the adverse effects caused by exposure to BPA, we performed an up-to-date literature review on the topic, with particular emphasis on in utero exposure, and associated effects on spermatogenesis, steroidogenesis, and accessory organs.BPA studies on experimental animals show that effects are generally more detrimental during in utero exposure, a critical developmental stage for the embryo. BPA has been found to produce several defects in the embryo, such as feminization of male fetuses, atrophy of the testes and epididymides, increased prostate size, shortening of AGD, disruption of BTB, and alteration of adult sperm parameters (e.g.,sperm count, motility, and density). BPA also affects embryo thyroid development.During the postnatal and pubertal periods and adulthood, BPA affects the hypothalamic-pituitary-testicular axis by modulating hormone (e.g., LH and FSH,androgen and estrogen) synthesis, expression and function of respective receptors(ER, AR). These effects alter sperm parameters. BPA also induces oxidative stress in the testis and epididymis, by inhibiting antioxidant enzymes and stimulating lipid peroxidation. This suggests that employing antioxidants may be a promising strategy to relieve BPA-induced disturbances.Epidemiological studies have also provided data indicating that BPA alters male reproductive function in humans. These investigations revealed that men occupationally exposed to BPA had high blood/urinary BPA levels, and abnormal semen parameters. BPA-exposed men also showed reduced libido and erectile ejaculatory difficulties; moreover, the overall BPA effects on male reproduction appear to be more harmful if exposure occurs in utero. The regulation of BPA and BPA-related products should be reinforced, particularly where exposure during the fetal period can occur. The current TDI for BPA is proposed as 25 and 50 1-1g/kg bwt/day (European Food Safety Authority and Health Canada, respectively). Based on the evidence available, we believe that a TDI value of 5 1-1g/kg bwt/day is more appropriate (the endpoint is modulation of rat testicular function). Certain BPA derivatives are being considered as alternatives to BPA. However, certain of these related products display adverse effects that are similar to those of BPA. These effects should be carefully considered before using them as final alternatives to BPA in plastic production.

Degradation of bisphenol A in aqueous solution by persulfate activated with ferrous ion

Degradation of bisphenol A (BPA) in aqueous solution was studied with high-efficiency sulfate radical (SO4(-·)), which was generated by the activation of persulfate (S2O8(2-)) with ferrous ion (Fe(2+)). S2O8(2-) was activated by Fe(2+) to produce SO4(-·), and iron powder (Fe(0)) was used as a slow-releasing source of dissolved Fe(2+). The major oxidation products of BPA were determined by liquid chromatography-mass spectrometer. The mineralization efficiency of BPA was monitored by total organic carbon (TOC) analyzer. BPA removal efficiency was improved by the increase of initial S2O8(2-) or Fe(2+) concentrations and then decreased with excess Fe(2+) concentration. The adding mode of Fe(2+) had significant impact on BPA degradation and mineralization. BPA removal rates increased from 49 to 97% with sequential addition of Fe(2+), while complete degradation was observed with continuous diffusion of Fe(2+), and the latter achieved higher TOC removal rate. When Fe(0) was employed as a slow-releasing source of dissolved Fe(2+), 100% of BPA degradation efficiency was achieved, and the highest removal rate of TOC (85%) was obtained within 2 h. In the Fe(0)-S2O8(2-) system, Fe(0) as the activator of S2O8(2-) could offer sustainable oxidation for BPA, and higher TOC removal rate was achieved. It was proved that Fe(0)-S2O8(2-) system has perspective for future works.

Low dose bisphenol A impairs spermatogenesis by suppressing reproductive hormone production and promoting germ cell apoptosis in adult rats

Bisphenol A (BPA), an estrogenic chemical, has been shown to reduce sperm count; however, the underlying mechanisms remain unknown. Herein, we show that oral administration of BPA (2 µg/kg) for consecutive 14 days in adult rats (BPA rats) significantly reduced the sperm count and the number of germ cells compared to controls. The serum levels of testosterone and follicle-stimulating hormone (FSH), as well as the level of GnRH mRNA in BPA rats were lower than those of control rats. Testosterone treatment could partially rescue the reduction of germ cells in BPA rats. Notably, the number of apoptotic germ cells was significantly increased in BPA rats, which was insensitive to testosterone. Furthermore, the levels of Fas, FasL and caspase-3 mRNA in the testicle of BPA rats were increased in comparison with controls. These results indicate that exposure to a low dose of BPA impairs spermatogenesis through decreasing reproductive hormones and activating the Fas/FasL signaling pathway.

Bisphenol A effect on glutathione synthesis and recycling in testicular Sertoli cells

BACKGROUND AND OBJECTIVE

Controversial effects of bisphenol A (BPA) have been reported on testicular function. These differences might reflect dissimilar exposure conditions. Dose responses to toxicants may be non-linear, e.g. U-shaped, with effects at low and at high levels of exposure and lower or inexistent effects at intermediate levels. Sertoli cells produce high levels of glutathione (GSH) as a cell defense mechanism. In this study, we addressed the question whether the exposure to different doses of BPA could influence Sertoli cell GSH synthesis and recycling.

MATERIALS AND METHODS

Primary Sertoli cell cultures were exposed to various doses of BPA (0.5 nM-100 μM). Cell viability was measured as an outcome of toxic effect. GSH cell content was determined to evaluate cell response to toxicant exposure. Glutamate-cysteine ligase catalytic (GCLC) and modulatory (GCLM) subunit expression were assessed to estimate GSH synthesis, and GSH reductase (GR) expression to estimate GSH recycling.

RESULTS

BPA 100 μM, but not lower doses, decreased cell viability. BPA 10 and 50 μM, but not lower doses, induced an increment in Sertoli cell GSH levels, due to a rapid upregulation of GCLC and GR and a slower upregulation of GCLM.

CONCLUSIONS

High doses of BPA are deleterious for Sertoli cells. Intermediate doses do not affect Sertoli cell viability and increase cell content of GSH owing to increased GSH synthesis and recycling enzyme expression. Lower doses of BPA are not capable of eliciting a cell defense response. These observations may explain a non-linear dose response of Sertoli cells to BPA.

Urinary bisphenol A concentrations in relation to serum thyroid and reproductive hormone levels in men from an infertility clinic

Human exposure to bisphenol A (BPA) is widespread. Animal studies have demonstrated that BPA can alter endocrine function, but human studies are limited. For the present study, we measured urinary BPA concentrations and serum thyroid and reproductive hormone levels in 167 men recruited through an infertility clinic. BPA was detected in 89% of urine samples with a median (range) of 1.3 (<0.4 - 36.4) ng/mL. In multivariable regression models adjusted for potential confounders, BPA concentrations in urine collected on the same day as a blood sample were inversely associated with serum levels of inhibin B and estradiol:testosterone ratio (E(2):T) and positively associated with follicle-stimulating hormone (FSH) and FSH:inhibin B ratio. Because BPA is metabolized quickly and multiple urine measures may better reflect exposure than a single measure, we also considered among a subset of the men the BPA concentrations in repeated urine samples collected weeks or months following serum sample collection. In these analyses, the effect estimates remained consistent for FSH and E(2):T but were somewhat weakened for inhibin B. In addition, we observed inverse relationships between urinary BPA concentrations and free androgen index (ratio of testosterone to sex hormone binding globulin), estradiol, and thyroid stimulating hormone. Our results suggest that urinary BPA concentrations may be associated with altered hormone levels in men, but these findings need to be substantiated through further research.

p,p'-DDE induces mitochondria-mediated apoptosis of cultured rat Sertoli cells

p,p'-Dichlorodiphenoxydichloroethylene (p,p'-DDE), the major metabolite of dichlorodiphenoxytrichloroethane (DDT), is a known persistent organic pollutant and male reproductive toxicant. However, the mechanism underlying male reproductive toxicity of p,p'-DDE remains limited. In the present study, Sertoli cells were used to investigate the molecular mechanism involved in p,p'-DDE's male reproductive toxicity. Results showed that p,p'-DDE exposure at over 30 microM showed induction of apoptotic cell death. p,p'-DDE could induce mitochondria-mediated apoptotic changes including elevation in reactive oxygen species (ROS) generation, decrease in mitochondrial membrane potential (DeltaPsi(m)), and release of cytochrome c into the cytosol, which could be blocked by antioxidant agent N-acetyl-l-cysteine (NAC). In addition, elevated ratios of Bax/Bcl-w and Bak/Bcl-w and cleavages of procaspase-3 and -9 were induced by p,p'-DDE treatment. All of the results suggested that ROS generation may play a critical role in the initiation of p,p'-DDE-induced apoptosis by mediation of the disruption of DeltaPsi(m), the release of cytochrome c into the cytosol and further the activation of caspase cascade.