In utero exposure to bisphenol A disrupts fetal testis development in rats

Prenatal diethylhexylphthalate exposure disturbs adult Leydig cell function via epigenetic downregulation of METTL4 expression in male rats

Prenatal exposure to diethylhexyl phthalate (DEHP) has been linked with a decline in testosterone levels in adult male rats, but the underlying mechanism remains unclear. We investigated the potential epigenetic regulation, particularly focusing on N6-methyladenosine (m6A) modification, as a possible mechanism. Dams were gavaged with DEHP (0, 10, 100, and 750 mg/kg/day) from gestational day 14 to day 21. The male offspring were examined at the age of 56 days. Prenatal DEHP administration at 750 mg/kg/day caused a decline in testosterone concentrations, an elevation in follicle-stimulating hormone, a downregulated expression of CYP11A1 HSD3B2, without affecting Leydig cell numbers. Interestingly, Methyltransferase Like 4 (METTL4), an m6A methyltransferase, was downregulated, while there were no changes in METTL3 and METTL14. Moreover, CYP11A1 showed m6A reduction in response to prenatal DEHP exposure. Additionally, METTL4 expression increased postnatally, peaking in adulthood. Knockdown of METTL4 resulted in the downregulation of CYP11A1 and HSD3B2 and an increase in SCARB1 expression. Furthermore, the increase in autophagy protection in adult Leydig cells induced by prenatal DEHP exposure was not affected by 3-methyladenosine (3MA) treatment, indicating a potential protective role of autophagy in response to DEHP exposure. In conclusion, prenatal DEHP exposure reduces testosterone by downregulating CYP11A1 and HSD3B2 via m6A epigenetic regulation and induction of autophagy protection in adult Leydig cells as a response to DEHP exposure.

Syringin alleviates bisphenol A-induced spermatogenic defects and testicular injury by suppressing oxidative stress and inflammation in male zebrafish

Syringin (SRG) is a bioactive principle possessing extensive activities including scavenging of free radicals, inhibition of apoptosis, and anti-inflammatory properties. However, its effects on spermatogenic defects and testicular injury as well as the underlying mechanisms are still unclear. This study aims to investigate the protective effect of SRG on testis damage in zebrafish and explore its potential molecular events. Zebrafish testicular injury was induced by exposure to bisphenol A (BPA) (3000 μg/L) for two weeks. Fish were treated with intraperitoneal injection of SRG at different doses (5 and 50 mg/kg bodyweight) for two more weeks under BPA induction. Subsequently, the testis and sperm were collected for morphological, histological, biochemical and gene expression examination. It was found that the administration of SRG resulted in a significant protection from BPA-caused impact on sperm concentration, morphology, motility, fertility rate, testosterone level, spermatogenic dysfunction and resulted in increased apoptotic and reactive oxygen species' levels. Furthermore, testicular transcriptional profiling alterations revealed that the regulation of inflammatory response and oxidative stress were generally enriched in differentially expressed genes (DEGs) after SRG treatment. Additionally, it was identified that SRG prevented BPA-induced zebrafish testis injury through upregulation of fn1a, krt17, fabp10a, serpina1l and ctss2. These results indicate that SRG alleviated spermatogenic defects and testicular injury by suppressing oxidative stress and inflammation in male zebrafish.

Combination treatment of zinc and selenium intervention ameliorated BPA-exposed germ cell damage in SD rats: elucidation of molecular mechanisms

Bisphenol A (BPA) is a commonly used environmental toxicant, is easily exposed to the human body and causes testicular damage, sperm abnormalities, DNA damage and apoptosis, and interferes in the process spermatogenesis and steroidal hormone production along with obstruction in testes and epididymis development. Zinc (Zn), a potent regulator of antioxidant balance, is responsible for cellular homeostasis, enzymes and proteins activities during spermatogenesis for cell defence mechanisms in the testes. Selenium (Se) is required for spermatogenesis, antioxidant action and in the activities of different selenoproteins. Both Zn and Se are essential simultaneously for the proper regulation of spermatogenesis and sperm maturation as well as protection against chemical and disease-associated germ cell toxicity. Thus, the study aimed to understand the importance and beneficial effect of Zn and Se co-treatment against BPA-exposed testicular damage in rats. BPA 100 and 200 mg/kg/day was exposed through an oral gavage. Zn (3 mg/kg/day) i.p. and Se (0.5 mg/kg/day) i.p. were injected for 8 weeks. The testicular toxicity was evaluated by measuring body and organs weight, biochemical investigations, sperm parameters, testicular and epididymal histopathology, quantification DNA damage by halo assay, DNA breaks (TUNEL assay), immunohistochemistry and western blot. Results revealed that Zn and Se co-treatment ameliorated BPA-associated male gonadal toxicity in rat as revealed by decreased SGPT, SGOT and BUN levels in serum, reduced testes and epididymis tissue injury, DNA breaks, apoptosis, expressions of 8-OHdG, γ-H2AX and NFκB with an increased serum testosterone and catalase levels. These findings suggest that Zn and Se co-treatment could be a beneficial and protective option against BPA-exposed testicular and epididymal toxicity.

Mixed probiotics modulated gut microbiota to improve spermatogenesis in bisphenol A-exposed male mice

Bisphenol A (BPA), an environmental endocrine disruptor (EDC), has been implicated in impairing intestinal and male reproductive dysfunction. The efficacy of gut microbiota modulation for BPA-exposed testicular dysfunction has yet to be verified through research. Therefore, this study explored the potential of mixed probiotics in restoring spermatogenesis damage through the gut-testis axis under BPA exposure. We selected two probiotics strains (Lactobacillus rhamnosus and Lactobacillus plantarum) with BPA removal properties in vitro and the BPA-exposed male mice model was established. The probiotics mixture effectively reduced BPA residue in the gut, serum, and testis in mice. Through 16 S rDNA-seq and metabolomics sequencing, we uncovered that vitamin D metabolism and bile acid levels in the gut was abolished under BPA exposure. This perturbation was linked to an increased abundance of Faecalibaculum and decreased abundance of Lachnospiraceae_NK4A136_group and Ligilactobacillus. The probiotics mixture restored this balance, enhancing intestinal barrier function and reducing oxidative stress. This improvement was accompanied by a restored balance of short-chain fatty acids (SCFAs). Remarkably, the probiotics ameliorated testicular dysfunction by repairing structures of seminiferous tubules and reversing arrested spermiogenesis. Further, the probiotics mixture enhanced testosterone-driven increases in spermatogonial stem cells and all stages of sperm cells. Testicular transcriptome profiling linked these improvements to fatty acid degradation and peroxisome pathways. These findings suggest a significant interplay between spermatogenesis and gut microbiota, demonstrating that probiotic intake could be a viable strategy for combating male subfertility issues caused by BPA exposure.

Reproductive toxicity of emerging plasticizers, flame retardants, and bisphenols, using culture of the rat fetal testis†

The use of bis (2-ethylhexyl) phthalate (DEHP), 2,2'4,4'-tetrabromodiphenyl ether (BDE47), and bisphenol A (BPA), as plasticizers, flame retardants, and epoxy resins, respectively, has been regulated due to their endocrine disrupting activities. Replacements for these chemicals are found in human matrices, yet the endocrine disrupting potential of these emerging contaminants is poorly characterized. We compared the effects of legacy chemicals with those of their replacements using fetal rat testis organ culture. Fetal testes sampled at gestation day 15 were grown ex vivo, and the impact was evaluated after a 3-day exposure to 10 μM of each legacy chemical; two BPA analogs (bisphenol M and bisphenol TMC); three replacements for DEHP/MEHP (2,2,4-trimethyl-1,3-pentanediol diisobutyrate, diisononyl-phthalate, and diisodecyl adipate); or two replacements for BDE47 (tributoxyethyl phosphate and isopropylated triphenyl phosphate). We showed that only BPA and MEHP significantly decrease testosterone secretions after 24 h, while BPM and BPTMC have the opposite effect. Luteinizing hormone-stimulated testosterone was reduced by BPA and MEHP but was increased by BPTMC. After exposure, testes were used for immunofluorescent staining of germ cells, Sertoli cells, and Leydig cells. Interestingly, exposures to BPM or BPTMC induced a significant increase in the Leydig cell density and surface area. A decrease in germ cell density was observed only after treatment with MEHP or BDE47. MEHP also significantly decreased Sertoli cell proliferation. These studies show that some replacement chemicals can affect testicular function, while others appear to show little toxicity in this model. These findings provide essential information regarding the need for their regulation.

Untargeted Lipidomics Revealed the Protective Effects of Cyanidin-3-O-glucoside on Bisphenol A-Induced Liver Lipid Metabolism Disorder in Rats

Bisphenol A (BPA) is an estrogenic endocrine disruptor that induces metabolic disorders. Cyanidin-3-O-glucoside (C3G) has multiple functional activities and is the most abundant anthocyanin belonging to the flavonoid subgroup. This study aimed to investigate the protective effect of C3G on BPA-induced liver lipid metabolism disorder and explore its mechanism via lipidomics analysis. The results showed that C3G supplementation significantly ameliorated the serum levels of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, total cholesterol, triacylglycerols (TG), and alanine and aspartate aminotransferase (ALT and AST). Furthermore, liver lipidomics indicated that C3G effectively facilitated the recovery of differential lipid metabolites, including TGs, phosphatidylethanolamines, phosphatidylcholines, lysophosphatidylcholines, phosphatidylinositol, cholesteryl esters, and phosphatidylserine, and reversed the levels of hepatic lipid synthesis-related genes. Our results suggest that C3G has an effective regulatory effect on BPA-induced disorders of lipid metabolism.

Impact of endocrine disrupting chemicals and pharmaceuticals on Sertoli cell development and functions

Sertoli cells play essential roles in male reproduction, from supporting fetal testis development to nurturing male germ cells from fetal life to adulthood. Dysregulating Sertoli cell functions can have lifelong adverse effects by jeopardizing early processes such as testis organogenesis, and long-lasting processes such as spermatogenesis. Exposure to endocrine disrupting chemicals (EDCs) is recognized as contributing to the rising incidence of male reproductive disorders and decreasing sperm counts and quality in humans. Some drugs also act as endocrine disruptors by exerting off-target effects on endocrine tissues. However, the mechanisms of toxicity of these compounds on male reproduction at doses compatible with human exposure are still not fully resolved, especially in the case of mixtures, which remain understudied. This review presents first an overview of the mechanisms regulating Sertoli cell development, maintenance, and functions, and then surveys what is known on the impact of EDCs and drugs on immature Sertoli cells, including individual compounds and mixtures, and pinpointing at knowledge gaps. Performing more studies on the impact of mixtures of EDCs and drugs at all ages is crucial to fully understand the adverse outcomes these chemicals may induce on the reproductive system.

Tetramethyl bisphenol A stimulates proliferation but inhibits fetal Leydig cell function in male rats by targeting estrogen receptor α after in utero exposure

Tetramethyl bisphenol A (TMBPA) is a widely used flame retardant. TMBPA has been a toxic to Leydig cells in puberty, but it remains unclear whether TMBPA has a similar inhibitor effect on fetal Leydig cells (FLCs). This study reported morphological and functional alterations of FLCs in the testes of male offspring at birth after in utero exposure to TMBPA. Pregnant Sprague Dawley rats were dosed via continuous gavage of TMBPA (0, 10, 50, and 200 mg/kg/day) from gestational day 14 to 21. TMBPA markedly raised serum total testosterone level, testicular volume, and FLC number of male offspring at 200 mg/kg dose. The up-regulation of Insl3, Star, and Cyp11a1 mRNAs was observed after 200 mg/kg TMBPA exposure. After normalization to the number of FLCs, TMBPA significantly reduced Lhcgr and Hsd3b1 expressions at 10 mg/kg, and Cyp17a1 at 200 mg/kg paralleling with their protein levels. TMBPA compromised the expression of Esr1, while increased the expression of Cdk2 and Cdk4 as well as their protein levels. TMBPA particularly increased the phosphorylation of AKT1 and AKT2 at 200 mg/kg. In conclusion, the present study suggests that TMBPA may promote FLC proliferation via ESR1-CDK2/4-AKT pathway, while inhibits the function of FLCs by reducing steroidogenic enzyme activity.

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.

In utero bisphenol AF exposure causes fetal Leydig cell dysfunction and induces multinucleated gonocytes by generating oxidative stress and reducing the SIRT1/PGC1α signals

Bisphenol AF (BPAF) is one of the primary alternatives of bisphenol A. It has been ubiquitously detected in the environment and is an emerging endocrine disrupting compound. However, the effects of BPAF exposure on fetal Leydig cells and germ cells and the underlying mechanisms remain largely unknown. To this end, pregnant Sprague-Dawley rats were exposed to 10, 50, and 200 mg/kg/d BPAF by gavage from gestational days 14 to 21. The neonatal rats were sacrificed on day 1 at birth. The results showed that serum testosterone levels were significantly decreased at 50 and 200 mg/kg/d, the expression of Scarb1, Star, Cyp17a1, Hsd17b3, and Dhh and their proteins were markedly down-regulated at 50 and 100 mg/kg/d. BPAF exposure also significantly increased the incidence of multinucleated gonocytes at 200 mg/kg/d. We further detected significant increase of testicular malondialdehyde levels and reduction of antioxidants, including SOD1, SOD2, and CAT at 50 and/or 200 mg/kg/d. Furthermore, BPAF markedly reduced the levels of SIRT1 and PGC1α at 200 mg/kg/d while significantly increased AMPK phosphorylation in the testes at 50 and 200 mg/kg/d. In conclusion, our results provide novel in vivo data that BPAF can induce fetal Leydig cell dysfunction by interfering with steroidogenic networks and induce the formation of multinucleated gonocytes after suppressing the antioxidant defense system and reducing SIRT1 and PGC1α signals and increasing the phosphorylation of AMPK, which highlights the potential health risk of environmental exposure to BPAF in inducing male reproductive tract malformation.

Multi- and transgenerational biochemical effects of low-dose exposure to bisphenol A and 4-nonylphenol on testicular interstitial (Leydig) cells

Bisphenol A (BPA) and 4-nonylphenol (NP) are well-known endocrine-disrupting chemicals (EDCs) that have been proven to affect Leydig cell (LC) functions and testosterone production, but whether BPA and NP have multi- and transgenerational biochemical effects on Leydig cells (LCs) is unknown. Fourier transform infrared (FTIR) spectroscopy is a powerful analytical technique that enables label-free and non-destructive analysis of the tissue specimen. Herein we employed FTIR coupled with chemometrics analysis to identify biomolecular changes in testicular interstitial (Leydig) cells of rats after chronic exposure to low doses of BPA and NP. Cluster segregations between exposed and control groups were observed based on the fingerprint region of 1800-900 cm^-1 in all generations. The main biochemical alterations for segregation were amide I, amide II and nucleic acids. BPA and NP single and co-exposure induced significant differences in the ratio of amide I to amide II compared to the corresponding control group in all generations. BPA exposure resulted in remarkable changes of cellular gene transcription and DNA oxidative damage across all generations. Direct exposure to BPA, NP, and BPA&NP of F0 and F1 generations could significantly decrease lipid accumulation in LCs in the F2 and F3 generations. The overall findings revealed that single or co-exposure to BPA and NP at environmental concentrations affects the biochemical structures and properties of LCs.

Tetramethyl bisphenol a inhibits leydig cell function in late puberty by inducing ferroptosis

Tetramethyl bisphenol A (TMBPA) is a commonly used bisphenol analog, used as a fire retardant. However, whether it inhibits the function of Leydig cells in late puberty remains unclear. In this study, 35-day-old male Sprague-Dawley rats were gavaged with 0, 10, 100, and 200 mg/kg body weight TMBPA for 21 days. TMBPA significantly reduced serum testosterone levels at 10 mg/kg and higher doses without altering serum luteinizing hormone and follicle-stimulating hormone levels. TMBPA significantly increased serum iron concentraion while reducing the ratio of serum glutathione (GSH) and GSH/GSSG (oxidized glutathione disulfide). In addition, TMBPA significantly increased testicular iron amount at 10 mg/kg and higher doses and malondialdehyde level at 200 mg/kg. TMBPA down-regulated the expression of Leydig cell genes, including Nr5a1, Star, Scarb1, Insl3, Cyp11a1, Cyp17a1, Hsd17b3, and Hsd11b1, and their proteins. In addition, TMBPA markedly down-regulated the expression of genes in the ferroptosis pathway (Tp53, Slc7a11, Sod1, Sod2, Cat, Sqstm1, Keap1, and Hmox1). TMBPA significantly reduced the levels of ferroptosis pathway proteins (TP53, SLC7A11, GPX4, SQSTM1, KEAP1, NRF2, and HMOX1) in Leydig cells in vivo. Immature and adult Leydig cell culture in vitro also showed that TMBPA significantly reduced testosterone concentrations in the medium, which can be reversed by a ferroptosis inhibitor. After 24 h of culture in primary Leydig cells at 10 and 50 μM, TMBPA significantly induced reactive oxygen species and lowered the mitochondrial membrane potential. TMBPA also altered protein levels in the ferroptosis pathway in Leydig cells in vitro. In conclusion, TMBPA directly inhibits the activity of rat Leydig cell steroidogenic enzymes and induces the ferroptosis of Leydig cells, thereby inhibiting the testosterone synthesis of Leydig cells in the late puberty.

Pubertal Bisphenol A exposure increases adult rat serum testosterone by resetting pituitary homeostasis

Bisphenol A (BPA) is widely used by manufacturers and in consumer products. Its release in the environment may affect male reproductive function. In this study, we examined the effect of low dose (0.1 mg/kg BW), short term exposure during puberty (PD21-35) on adult rat male reproduction. The results indicated that such exposure reset growth hormone (GH) and follicular stimulating hormone (FSH) homeostasis and resulted in a significantly higher level of serum testosterone without affecting serum luteinizing hormone level. QPCR and Western blot results showed that BPA significantly up-regulated selective genes/proteins in the Leydig cell steroidogenic pathway, including steroidogenic acute regulatory protein, cytochrome P450 11A1, cytochrome P450 17A, and low-density lipoprotein receptor. RNA-Seq analysis of testicular RNAs showed that BPA significantly affected the gene profiles of multiple testicular interstitial populations without affecting germ cells. Also, GO- and KEGG-analysis suggested that IGF1-related PI3K/AKT signaling was activated, which was confirmed by the increased phosphorylation of IRS1, AKT1 and CREB. The results indicated that a low-dose, short-term BPA exposure during puberty affected the adult male rat pituitary (GH and FSH) and testis (testosterone) homeostasis.

Bisphenol AF blocks Leydig cell regeneration from stem cells in male rats

Bisphenol A (BPA) is a ubiquitous environmental pollutant, mainly from the manufacture and use of plastics. The use of BPA is restricted, and its new analogs (including bisphenol AF, BPAF) are being produced to replace it. However, the effect of BPAF on the male reproductive system remains unclear. Here, we report the effect of BPAF on Leydig cell regeneration in rats. Leydig cells were eliminated by ethane dimethane sulfonate (EDS, i.p., 75 mg/kg) and the regeneration began 14 days after its treatment. We gavaged 0, 10, 100, and 200 mg/kg BPAF to rats on post-EDS day 7-28. BPAF significantly reduced serum testosterone and progesterone levels at ≧10 mg/kg. It markedly reduced serum levels of estradiol, luteinizing hormone, and follicle-stimulating hormone at 100 and 200 mg/kg. BPAF significantly reduced Leydig cell number at 200 mg/kg. BPAF significantly down-regulated the expression of Cyp17a1 at doses of 10 mg/kg and higher and the expression of Insl3, Star, Hsd17b3, Hsd11b1 in Leydig cells at 100 and 200 mg/kg, while it induced a significant up-regulation of Fshr, Dhh, and Sox9 in Sertoli cells at 200 mg/kg. BPAF induced oxidative stress and reduced the level of SOD2 at 200 mg/kg. It induced apoptosis and autophagy by increasing the levels of BAX, LC3B, and BECLIN1 and lowering the levels of BCL2 and p62 at 100 and 200 mg/kg. It induced autophagy possibly via decreasing the phosphorylation of AKT1 and mTOR. BPAF also significantly induced ROS production and apoptosis at a concentration of 10 μM, and reduced testosterone synthesis in rat R2C Leydig cells at a concentration of 10 μM in vitro, but did not affect cell viability after 24 h of treatment. In conclusion, BPAF is a novel endocrine disruptor, inhibiting the regeneration of Leydig cells.

Effects of endocrine disrupting chemicals on gonad development: Mechanistic insights from fish and mammals

Over the past century, evidence has emerged that endocrine disrupting chemicals (EDCs) have an impact on reproductive health. An increased frequency of reproductive disorders has been observed worldwide in both wildlife and humans that is correlated with accidental exposures to EDCs and their increased production. Epidemiological and experimental studies have highlighted the consequences of early exposures and the existence of key windows of sensitivity during development. Such early in life exposures can have an immediate impact on gonadal and reproductive tract development, as well as on long-term reproductive health in both males and females. Traditionally, EDCs were thought to exert their effects by modifying the endocrine pathways controlling reproduction. Advances in knowledge of the mechanisms regulating sex determination, differentiation and gonadal development in fish and rodents have led to a better understanding of the molecular mechanisms underlying the effects of early exposure to EDCs on reproduction. In this manuscript, we review the key developmental stages sensitive to EDCs and the state of knowledge on the mechanisms by which model EDCs affect these processes, based on the roadmap of gonad development specific to fish and mammals.

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 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.

Elucidation of the Effects of Bisphenol A and Structural Analogs on Germ and Steroidogenic Cells Using Single Cell High-Content Imaging

Concerns about the potential adverse effects of bisphenol A (BPA) have led to an increase in the use of replacements, yet the toxicity data for several of these chemicals are limited. Using high-content imaging, we compared the effects of BPA, BPAF, BPF, BPS, BPM, and BPTMC in germ (C18-4 spermatogonial) and steroidogenic (MA-10 Leydig and KGN granulosa) cell lines. Effects on cell viability and phenotypic markers were analyzed to determine benchmark concentrations (BMCs) and estimate administered equivalent doses (AEDs). In all 3 cell lines, BPA was one of the least cytotoxic bisphenol compounds tested, whereas BPM and BPTMC were the most cytotoxic. Interestingly, BPF and BPS were cytotoxic only in MA-10 cells. Effects on phenotypic parameters, including mitochondria, lysosomes, lipid droplets, and oxidative stress, were both bisphenol- and cell-line specific. BPA exposure affected mitochondria (BMC: 1.2 μM; AED: 0.09 mg/kg/day) in C18-4 cells. Lysosome numbers were increased in MA-10 cells exposed to BPA or BPAF but decreased in KGN cells exposed to BPAF or BPM. Lipid droplets were decreased in C18-4 cells exposed to BPF and in MA-10 cells exposed to BPTMC but increased in BPF, BPM, and BPTMC-exposed KGN cells. BPA and BPM exposure induced oxidative stress in MA-10 and KGN cells, respectively. In summary, structurally similar bisphenols displayed clear cell-line-specific differences in BMC and AED values for effects on cell viability and phenotypic endpoints. This approach, together with additional data on human exposure, may aid in the selection and prioritization of responsible replacements for BPA. .

Fighting Bisphenol A-Induced Male Infertility: The Power of Antioxidants

Bisphenol A (BPA), a well-known endocrine disruptor present in epoxy resins and polycarbonate plastics, negatively disturbs the male reproductive system affecting male fertility. In vivo studies showed that BPA exposure has deleterious effects on spermatogenesis by disturbing the hypothalamic–pituitary–gonadal axis and inducing oxidative stress in testis. This compound seems to disrupt hormone signalling even at low concentrations, modifying the levels of inhibin B, oestradiol, and testosterone. The adverse effects on seminal parameters are mainly supported by studies based on urinary BPA concentration, showing a negative association between BPA levels and sperm concentration, motility, and sperm DNA damage. Recent studies explored potential approaches to treat or prevent BPA-induced testicular toxicity and male infertility. Since the effect of BPA on testicular cells and spermatozoa is associated with an increased production of reactive oxygen species, most of the pharmacological approaches are based on the use of natural or synthetic antioxidants. In this review, we briefly describe the effects of BPA on male reproductive health and discuss the use of antioxidants to prevent or revert the BPA-induced toxicity and infertility in men.

Exposure to 4-bromodiphenyl ether during pregnancy blocks testis development in male rat fetuses

4-Bromodiphenyl ether (BDE3) is a photodegradation product of higher polybrominated diphenyl ether flame retardants and is known as an endocrine disruptor. However, it is unclear whether and how BDE3 affects the development of fetal testes. This study aimed to investigate the effect of in utero exposure to BDE3 on fetal testicular development in rats. From gestational day (GD) 12-21, BDE3 (0, 50, 100, and 200 mg/kg) was daily gavaged to female pregnant Sprague Dawley rats. BDE3 significantly reduced serum testosterone levels of male pups starting at 50 mg/kg. BDE3 reduced fetal Leydig cell number at a dose of 200 mg/kg without affecting fetal Leydig cell cluster frequency and Sertoli cell number. In addition, BDE3 down-regulated the expression of fetal Leydig cell genes (Cyp11a1, Hsd3b1, Cyp17a1, and Hsd17b3) and their proteins at 100 and/or 200 mg/kg. RNA-seq analysis showed that genes responsive to cAMP (Ass1, Gpd1, Rpl13a) were down-regulated and hypoxia-related genes (Egln3 and P4ha1) were up-regulated at 200 mg/kg. In utero exposure to BDE3 can promote autophagy and apoptosis of fetal Leydig cells via increasing the levels of Beclin1, LC3-II, BAX, and by decreasing the levels of p62 and BCL2. In conclusion, in utero exposure to BDE3 blocks the development of fetal rat testes.

Gestational exposure to tebuconazole affects the development of rat fetal Leydig cells

Tebuconazole is a triazole fungicide, used in agriculture to treat phytopathogenic fungi, and as a biocide, has been reported to be related to reproductive and developmental toxicity. The purpose of this study was to investigate the effect of tebuconazole exposure on rat fetal Leydig cells and fetal testis during pregnancy. Pregnant Sprague-Dawley rats were randomly divided into 4 groups, daily gavaged with corn oil (as a control), 25, 50, and 100 mg/kg body weight tebuconazole for 10 days (from the 12th day of pregnancy). Tebuconazole increased fetal serum testosterone and progesterone levels at a dose of 100 mg/kg. Exposure to 100 mg/kg tebuconazole significantly caused an increase in the number of fetal Leydig cells per testis without inducing cell aggregation. Tebuconazole up-regulated the expression of Star, Cyp11a1, Hsd17b3, and Fshr and their proteins. Further investigation found that tebuconazole caused increased phosphorylation of AKT1, ERK1/2, and mTOR, the level of BCL2, as well as the decrease of Beclin1, LC3B, and BAX, which may contribute to the fetal Leydig cell autophagy and proliferation. In conclusion, in utero exposure of tebuconazole causes the proliferation of fetal Leydig cells.

Exogenous Oestrogen Impacts Cell Fate Decision in the Developing Gonads: A Potential Cause of Declining Human Reproductive Health

The increasing incidence of testicular dysgenesis syndrome-related conditions and overall decline in human fertility has been linked to the prevalence of oestrogenic endocrine disrupting chemicals (EDCs) in the environment. Ectopic activation of oestrogen signalling by EDCs in the gonad can impact testis and ovary function and development. Oestrogen is the critical driver of ovarian differentiation in non-mammalian vertebrates, and in its absence a testis will form. In contrast, oestrogen is not required for mammalian ovarian differentiation, but it is essential for its maintenance, illustrating it is necessary for reinforcing ovarian fate. Interestingly, exposure of the bi-potential gonad to exogenous oestrogen can cause XY sex reversal in marsupials and this is mediated by the cytoplasmic retention of the testis-determining factor SOX9 (sex-determining region Y box transcription factor 9). Oestrogen can similarly suppress SOX9 and activate ovarian genes in both humans and mice, demonstrating it plays an essential role in all mammals in mediating gonad somatic cell fate. Here, we review the molecular control of gonad differentiation and explore the mechanisms through which exogenous oestrogen can influence somatic cell fate to disrupt gonad development and function. Understanding these mechanisms is essential for defining the effects of oestrogenic EDCs on the developing gonads and ultimately their impacts on human reproductive health.

Cisatracurium stimulates testosterone synthesis in rat and mouse Leydig cells via nicotinic acetylcholine receptor

As a cis-acting non-depolarizing neuromuscular blocker through a nicotinic acetylcholine receptor (nAChR), cisatracurium (CAC) is widely used in anaesthesia and intensive care units. nAChR may be present on Leydig cells to mediate the action of CAC. Here, by Western blotting, immunohistochemistry and immunofluorescence, we identified that CHRNA4 (a subunit of nAChR) exists only on rat adult Leydig cells. We studied the effect of CAC on the synthesis of testosterone in rat adult Leydig cells and mouse MLTC-1 tumour cells. Rat Leydig cells and MLTC-1 cells were treated with CAC (5, 10 and 50 μmol/L) or nAChR agonists (50 μmol/L nicotine or 50 μmol/L lobeline) for 12 hours, respectively. We found that CAC significantly increased testosterone output in rat Leydig cells and mouse MLTC-1 cells at 5 μmol/L and higher concentrations. However, nicotine and lobeline inhibited testosterone synthesis. CAC increased intracellular cAMP levels, and nicotine and lobeline reversed this change in rat Leydig cells. CAC may increase testosterone synthesis in rat Leydig cells and mouse MLTC-1 cells by up-regulating the expression of Lhcgr and Star. Up-regulation of Scarb1 and Hsd3b1 expression by CAC was also observed in rat Leydig cells. In addition to cAMP signal transduction, CAC can induce ERK1/2 phosphorylation in rat Leydig cells. In conclusion, CAC binds to nAChR on Leydig cells, and activates cAMP and ERK1/2 phosphorylation, thereby up-regulating the expression of key genes and proteins in the steroidogenic cascade, resulting in increased testosterone synthesis in Leydig cells.

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.

Transcriptomic analysis identifies early cellular and molecular events by which estrogen disrupts testis differentiation and causes feminization in Xenopus laevis

Extensive studies have shown that estrogenic endocrine-disrupting chemicals (EDCs) can disrupt testis differentiation and even cause feminization in vertebrates. However, little is known about the mechanisms by which estrogenic EDCs disrupt testis differentiation. Here, we employed Xenopus laevis, a model amphibian species sensitive to estrogenic EDCs, to explore the molecular and cellular events by which 17β-estradiol (E2) disrupts testis differentiation and causes feminization. Following waterborne exposure to E2 from stage 45/46, genetically male X. laevis were confirmed to undergo testis differentiation inhibition and ovary differentiation activation at stages 52 and 53, ultimately displaying gonadal feminization at stage 66. Using a time-course RNA sequencing approach, we then identified thousands of differentially expressed transcripts (DETs) in genetically male gonad-mesonephros complexes at stages 48, 50 and 52 (the window for testis differentiation) between E2 treatment and the control. Enrichment analysis suggests alterations in cell proliferation, extracellular matrix, and cell motility following E2 exposure. Further verification by multiple methods demonstrated that E2 inhibited cell proliferation, disrupted extracellular matrix, and altered cell motility in the genetically male gonads compared with controls, implying that these events together contributed to testis differentiation disruptions and feminization in X. laevis. This study for the first time uncovered some of the early molecular and cellular events by which estrogen disrupts testicular differentiation and causes feminization in X. laevis. These new findings improve our understanding of the mechanisms by which estrogenic EDCs disrupt testicular differentiation in vertebrates.

Taxifolin attenuates the developmental testicular toxicity induced by di-n-butyl phthalate in fetal male rats

Di-n-butyl phthalate (DBP) is widely used in consumer products as a plasticizer. Here, we report a natural product taxifolin that can attenuate developmental and reproductive toxicity of DBP. Pregnant rats were daily gavaged with 500 mg/kg DBP alone or together with taxifolin (10 and 20 mg/kg) from gestational day (GD) 12-21. At GD21, sera and testes of male fetus were collected. DBP significantly lowered serum testosterone level at 500 mg/kg and taxifolin can completely reverse its action. DBP caused abnormal aggregation of fetal Leydig cells and taxifolin can reverse it. DBP down-regulated the expression of the genes of cholesterol side-chain cleavage enzyme (Cyp11a1), 17β-hydroxysteroid dehydrogenase 3 (Hsd17b3), and insulin-like 3 (Insl3) and taxifolin can reverse its action. DBP increased malondialdehyde levels and decreased superoxide dismutase and glutathione peroxidase expression and taxifolin can reverse it. DBP increased incidence of multinucleated gonocytes and taxifolin can prevent it. Moreover, DBP lowered sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) and phosphorylated AMP-activated protein kinase (pAMPK) signalling and taxifolin antagonized DBP. In conclusion, in utero exposure to DBP caused developmental/reproductive toxicity of male offspring via increasing reactive oxygen species and taxifolin is an effective food component that completely reverses DBP-mediated action.

The Effect of Exposure to Bisphenol A on Spermatozoon and the Expression of Tight Junction Protein Occludin in Male Mice

Although bisphenol A (BPA) has been associated with impaired spermatogenesis, the mechanisms remain unclear. Tight junction occludin plays important roles in spermatogenesis. The objective of the present study was to explore the effects of BPA exposure in adolescent mice. Male mice were orally treated with low-dose (0.05 mg/kg/d), middle-dose (5.0 mg/kg/d), or high-dose (50 mg/kg/d) BPA in corn oil from postnatal day (PND) 35 to 65. Animals were killed on PND 65 and PND 125. On PND 65, the sperm count, sperm motility, and the expression of occludin showed a dose-related decline. On PND 125, the sperm count, sperm motility, and the expression of occludin were in recovery. However, there remained significant decreases in these parameters in the 50 mg/kg/d group on PND 125 compared with the control. The dose-related effects on the measured parameters and occludin expression suggest an early suppressive or damaging effect on the blood–testis barrier followed by recovery after dosing ceased. At a BPA dose of 50 mg/kg/d, recovery did not occur, suggesting that higher doses of BPA may cause irreversible damage to reproduction in male mice.

Mechanisms of Testicular Disruption from Exposure to Bisphenol A and Phtalates

Great attention has been paid in recent years to the harmful effects of various chemicals that interfere with our natural hormone balance, collectively known as endocrine-disrupting chemicals (EDCs) or endocrine disruptors. The effects on the reproductive system of bisphenol A (BPA) and phthalates have received particular attention: while they have a short half-life, they are so widespread that human exposure can be considered as continuous. Evidence is often limited to the animal model, disregarding the likelihood of human exposure to a mixture of contaminants. Data from animal models show that maternal exposure probably has harmful effects on the male fetus, with an increased risk of urogenital developmental abnormalities. After birth, exposure is associated with changes in the hypothalamic-pituitary-testicular axis, hindering the development and function of the male genital pathways through the mediation of inflammatory mechanisms and oxidative stress. The epidemiological and clinical evidence, while generally confirming the association between reproductive abnormalities and some phthalate esters and BPA, is more contradictory, with wildly different findings. The aim of this review is therefore to provide an update of the potential mechanisms of the damage caused by BPA and phthalates to reproductive function and a review of the clinical evidence currently available in the literature.

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

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

Bisphenols and Leydig Cell Development and Function

Bisphenol A (BPA) is a ubiquitous environmental pollutant, mainly from the production and use of plastics and the degradation of wastes related to industrial plastics. Evidence from laboratory animal and human studies supports the view that BPA has an endocrine disrupting effect on Leydig cell development and function. To better understand the adverse effects of BPA, we reviewed its role and mechanism by analyzing rodent data in vivo and in vitro and human epidemiological evidence. BPA has estrogen and anti-androgen effects, thereby destroying the development and function of Leydig cells and causing related reproductive diseases such as testicular dysgenesis syndrome, delayed puberty, and subfertility/infertility. Due to the limitation of BPA production, the increased use of BPA analogs has also attracted attention to these new chemicals. They may share actions and mechanisms similar to or different from BPA.

Hepatoprotective effects of curcumin and taurine against bisphenol A-induced liver injury in rats

Bisphenol A (BPA) is an estrogenic endocrine disrupting chemical to which humans are frequently exposed during routine daily life. Curcumin and taurine are natural products that have also been used as antioxidants against different environmental toxin-induced hepatotoxicity. Furthermore, they have protective and therapeutic effects against various diseases. The present investigation has been conducted to evaluate the therapeutic potential of curcumin (100 mg kg^-1) and taurine (100 mg kg^-1) for their hepatoprotective efficacy against BPA (130 mg kg^-1)-induced liver injury in rat. BPA significantly elevated the levels of malondialdehyde (MDA), while it reduced the activities of catalase (CAT), total glutathione S-transferase (GST), total glutathione peroxidase (GPx), and total superoxide dismutase (SOD). Besides, these biochemical changes were accompanied by histopathological alterations marked by the destruction of normal liver structure. The histological examinations showed that exposure of BPA caused dilatation of sinusoids, inflammatory cell infiltration, congestion, and necrosis in liver parenchyma. The BPA-induced histopathological alterations in liver were minimized by curcumin and taurine treatment. Furthermore, no necrosis was observed in the liver tissues of curcumin plus BPA and taurine plus BPA-treated rats. Oral administration of curcumin and taurine to BPA-exposed rats significantly reversed the content of lipid peroxidation products, as well as enhanced the activities of GPx and GST, CAT, and SOD enzymes. These findings have indicated that curcumin and taurine might have a protective effect against BPA-induced hepatotoxicity in rats.