Bisphenol A Exposure during Pregnancy Alters the Mortality and Levels of Reproductive Hormones and Genes in Offspring Mice

An Overview of the Health Effects of Bisphenol A from a One Health Perspective

Bisphenol A (BPA) is a chemical compound, considered as an "emerging pollutant", that appears ubiquitously, contaminating the environment and food. It is an endocrine disruptor, found in a multitude of consumer products, as it is a constituent of polycarbonate used in the manufacture of plastics and epoxy resins. Many studies have evaluated the effects of BPA, using a wide range of doses and animal models. In this work, we carried out a review of relevant research related to the effects of BPA on health, through studies performed at different doses, in different animal models, and in human monitoring studies. Numerous effects of BPA on health have been described; in different animal species, it has been reported that it interferes with fertility in both females and males and causes alterations in their offspring, as well as being associated with an increase in hormone-dependent pathologies. Similarly, exposure to BPA has been related to other diseases of great relevance in public health such as obesity, hypertension, diabetes, or neurodevelopmental disorders. Its ubiquity and nonmonotonic behavior, triggering effects at exposure levels considered "safe", make it especially relevant when both animal and human populations are constantly and inadvertently exposed to this compound. Its effects at low exposure levels make it essential to establish safe exposure levels, and research into the effects of BPA must continue and be focused from a "One Health" perspective to take into account all the factors that could intervene in the development of a disease in any exposed organism.

Different types of bisphenols alter ovarian steroidogenesis: Special attention to BPA

Endocrine disruptors such as bisphenol A (BPA) and some of its analogues, including BPS, BPAF, and BPE, are used extensively in the manufacture of plastics. These synthetic chemicals could seriously alter the functionality of the female reproductive system. Although the number of studies conducted on other types of bisphenols is smaller than the number of studies on BPA, the purpose of this review study was to evaluate the effects of bisphenol compounds, particularly BPA, on hormone production and on genes involved in ovarian steroidogenesis in both in vitro (human and animal cell lines) and in vivo (animal models) studies. The current data show that exposure to bisphenol compounds has adverse effects on ovarian steroidogenesis. For example, BPA, BPS, and BPAF can alter the normal function of the hypothalamic-pituitary-gonadal (HPG) axis by targeting kisspeptin neurons involved in steroid feedback signals to gonadotropin-releasing hormone (GnRH) cells, resulting in abnormal production of LH and FSH. Exposure to BPA, BPS, BPF, and BPB had adverse effects on the release of some hormones, namely 17-β-estradiol (E2), progesterone (P4), and testosterone (T). BPA, BPE, BPS, BPF, and BPAF are also capable of negatively altering the transcription of a number of genes involved in ovarian steroidogenesis, such as the steroidogenic acute regulatory protein (StAR, involved in the transfer of cholesterol from the outer to the inner mitochondrial membrane, where the steroidogenesis process begins), cytochrome P450 family 17 subfamily A member 1 (Cyp17a1, which is involved in the biosynthesis of androgens such as testosterone), 3 beta-hydroxysteroid dehydrogenase enzyme (3β-HSD, involved in the biosynthesis of P4), and cytochrome P450 family 19 subfamily A member 1 (Cyp19a1, involved in the biosynthesis of E2). Exposure to BPA, BPB, BPF, and BPS at prenatal or prepubertal stages could decrease the number of antral follicles by activating apoptosis and autophagy pathways, resulting in decreased production of E2 and P4 by granulosa cells (GCs) and theca cells (TCs), respectively. BPA and BPS impair ovarian steroidogenesis by reducing the function of some important cell receptors such as estrogens (ERs, including ERα and ERβ), progesterone (PgR), the orphan estrogen receptor gamma (ERRγ), the androgen receptor (AR), the G protein-coupled estrogen receptor (GPER), the FSHR (follicle-stimulating hormone receptor), and the LHCGR (luteinizing hormone/choriogonadotropin receptor). In animal models, the effects of bisphenol compounds depend on the type of animals, their age, and the duration and dose of bisphenols, while in cell line studies the duration and doses of bisphenols are the matter.

Effects of perfluorododecanoic acid on testicular function in mice

Perfluorodecanoic acid (PFDoA) is a widely distributed environmental pollutant that can affect the functions of many organs. However, systematic evaluations of the effects of PFDoA on testicular functions are lacking. The aim of this study was to investigate the effects of PFDoA on mouse testicular functions, including spermatogenesis, testosterone synthesis, and stem Leydig cells (SLCs) in the interstitial tissue of the testis. PFDoA (0, 2, 5, 10 mg/kg/d) was administered via gavage to 2-month-old mice for 4 weeks. Serum hormone levels and sperm quality were assayed. Furthermore, to investigate the mechanisms by which PFDoA affects testosterone synthesis and spermatogenesis in vivo, the expression of StAR and P450scc in testicular tissue was measured by immunofluorescence staining and quantitative real-time PCR. In addition, the levels of SLC markers, including nestin and CD51, were studied. PFDoA decreased the luteinizing hormone concentration and sperm quality. Although the difference was not statistically significant, mean testosterone levels showed a downward trend. The expression of StAR, P450scc, CD51, and nestin was also suppressed in the PFDoA-treated groups compared with the control group. Our study suggested that PFDoA exposure can decrease testosterone biosynthesis, and even reduce the number of SLCs. These results indicated that PFDoA suppressed the main functions of testis, and further researches are required to identify strategies for preventing or reducing the effect of PFDoA on testicular function.

Early programming of reproductive health and fertility: novel neuroendocrine mechanisms and implications in reproductive medicine

BACKGROUND

According to the Developmental Origins of Health and Disease (DOHaD) hypothesis, environmental changes taking place during early maturational periods may alter normal development and predispose to the occurrence of diverse pathologies later in life. Indeed, adverse conditions during these critical developmental windows of high plasticity have been reported to alter the offspring developmental trajectory, causing permanent functional and structural perturbations that in the long term may enhance disease susceptibility. However, while solid evidence has documented that fluctuations in environmental factors, ranging from nutrient availability to chemicals, in early developmental stages (including the peri-conceptional period) have discernible programming effects that increase vulnerability to develop metabolic perturbations, the impact and eventual mechanisms involved, of such developmental alterations on the reproductive phenotype of offspring have received less attention.

OBJECTIVE AND RATIONALE

This review will summarize recent advances in basic and clinical research that support the concept of DOHaD in the context of the impact of nutritional and hormonal perturbations, occurring during the periconceptional, fetal and early postnatal stages, on different aspects of reproductive function in both sexes. Special emphasis will be given to the effects of early nutritional stress on the timing of puberty and adult gonadotropic function, and to address the underlying neuroendocrine pathways, with particular attention to involvement of the Kiss1 system in these reproductive perturbations. The implications of such phenomena in terms of reproductive medicine will also be considered.

SEARCH METHODS

A comprehensive MEDLINE search, using PubMed as main interface, of research articles and reviews, published mainly between 2006 and 2021, has been carried out. Search was implemented using multiple terms, focusing on clinical and preclinical data from DOHaD studies, addressing periconceptional, gestational and perinatal programming of reproduction. Selected studies addressing early programming of metabolic function have also been considered, when relevant.

OUTCOMES

A solid body of evidence, from clinical and preclinical studies, has documented the impact of nutritional and hormonal fluctuations during the periconceptional, prenatal and early postnatal periods on pubertal maturation, as well as adult gonadotropic function and fertility. Furthermore, exposure to environmental chemicals, such as bisphenol A, and maternal stress has been shown to negatively influence pubertal development and gonadotropic function in adulthood. The underlying neuroendocrine pathways and mechanisms involved have been also addressed, mainly by preclinical studies, which have identified an, as yet incomplete, array of molecular and neurohormonal effectors. These include, prominently, epigenetic regulatory mechanisms and the hypothalamic Kiss1 system, which likely contribute to the generation of reproductive alterations in conditions of early nutritional and/or metabolic stress. In addition to the Kiss1 system, other major hypothalamic regulators of GnRH neurosecretion, such as γ-aminobutyric acid and glutamate, may be targets of developmental programming.

WIDER IMPLICATIONS

This review addresses an underdeveloped area of reproductive biology and medicine that may help to improve our understanding of human reproductive disorders and stresses the importance, and eventual pathogenic impact, of early determinants of puberty, adult reproductive function and fertility.

Maternal and developmental toxicity of Bisphenol-A in SWR/J mice

Bisphenol-A (BPA), an organic compound with two phenol functional groups, is a widely used industrial plasticizer with known estrogenic properties. It is used in the manufacture of epoxy resins and polycarbonate plastics. This study was designed to evaluate and assess the possible toxicity arising from the oral administration of BPA to pregnant mice. Pregnant SWR/J mice (15 mice/group) were administrated oral doses of BPA (125, 250 and 500 mg/kg/day) over the course of five-day intervals during gestation (D1-5, D6-10 and D11-15), while control groups received only corn oil. The results indicated that BPA was associated with a reduction in the body weight of the pregnant mice from around 2–3 days after administration until the end of gestation. The greatest effects were evident when the BPA was given during the later stages of pregnancy, and with higher doses. They also showed marked reduction in food intake and, to a lesser extent, in water intake. Furthermore, doses of BPA induced a reduction in implantation sites, lower foetal body weight and increased mortality rates. Abortion and foetal resorption rates were not affected by BPA administration, however. The above findings were concluded by discussing the possible mechanisms involved in producing these effects.

Bisphenol A induced apoptosis via oxidative stress generation involved Nrf2/HO-1 pathway and mitochondrial dependent pathways in human retinal pigment epithelium (ARPE-19) cells

Bisphenol A (BPA) is an estrogen-like compound, and an environmental hormone, that is commonly used in daily life. Therefore, it may enter the human body through food or direct contact, causing BPA residues in blood and urine. Because most studies focused on the analysis of BPA in reproductive cells or tissues, regarding evidence the effect of BPA on human retinal pigment epithelium (ARPE-19) cells unavailable. Accordingly, the present study explored the cytotoxicity of BPA on ARPE-19 cells. After BPA treatment, the expression of Bcl-XL an antiapoptotic protein, in the mitochondria decreased, and the expression of Bax, a proapoptotic protein increased. Then the mitochondrial membrane potential was affected. BPA changed in mitochondrial membrane potential led to the release of cytochrome C, which activated caspase-9 to promote downstream caspase-3 leading to cytotoxicity. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase 1 (HO-1) pathway play a major role in age-related macular degeneration. Our results showed that expression of HO-1 and Nrf2 suppressed by BPA. Superoxide dismutase and catalase, which Nrf2 downstream antioxidants, were degraded by BPA. AMP-activated kinase (AMPK), which can regulate the phosphorylation of Nrf2, and the phosphorylation of AMPK expression was reduced by BPA. Finally, BPA-induced ROS generation and cytotoxicity were reduced by N-acetyl-l-cysteine. Taken together, these results suggest that BPA induced ARPE-19 cells via oxidative stress, which was associated with down regulated Nrf2/HO-1 pathway, and the mitochondria dependent apoptotic signaling pathway.

Bisphenol A and its effects on the systemic organs of children

For the past two decades, growing research has been pointing to multiple repercussions of bisphenol A (BPA) exposure to human health. BPA is a synthetic oestrogen which primarily targets the endocrine system; however, the compound also disturbs other systemic organ functions, in which the magnitude of impacts in those other systems is as comparable to those in the endocrine system. To date, the discoveries on the association between BPA and health outcomes mainly came from animal and in vitro studies, with limited human studies which emphasised on children's health. In this comprehensive review, we summarised studies on human, in vivo and in vitro models to understand the consequences of pre-, post- and perinatal BPA exposure on the perinatal, children and adult health, encompassing cardiovascular, neurodevelopmental, endocrine and reproductive effects.Conclusion: Evidence from in vitro and animal studies may provide further support and better understanding on the correlation between environmental BPA exposure and its detrimental effects in humans and child development, despite the difficulties to draw direct causal relations of BPA effects on the pathophysiology of the diseases/syndromes in children, due to differences in body system complexity between children and adults, as well as between animal and in vitro models and humans. What is known: • Very limited reviews are available on how BPA adversely affects children's health. • Previous papers mainly covered two systems in children. What is new: • Comprehensive review on the detrimental effects of BPA on children health outcomes, including expectations on adult health outcomes following perinatal BPA exposure, as well as covering a small part of BPA alternatives. • Essentially, BPA exposure during pregnancy has huge impacts on the foetus in which it may cause changes in foetal epigenetic programming, resulting in disease onsets during childhood as well as adulthood.

Insights into the Regulation on Proliferation and Differentiation of Stem Leydig Cells

Male hypogonadism is a clinical syndrome caused by testosterone deficiency. Hypogonadism can be caused by testicular disease (primary hypogonadism) or hypothalamic-pituitary dysfunction (secondary hypogonadism). The present strategy for treating hypogonadism is the administration of exogenous testosterone. But exogenous testosterone is reported to have negative side effects including adverse cardiovascular events and disruption of physiological spermatogenesis probably due to its inability to mimic the physiological circadian rhythm of testosterone secretion in vivo. In recent years, a growing number of articles demonstrated that stem Leydig cells (SLCs) can not only differentiate into functional Leydig cells (LCs) in vivo to replace chemically disrupted LCs, but also secrete testosterone in a physiological pattern. The proliferation and differentiation of SLCs are regulated by various factors. However, the mechanisms involved in regulating the development of SLCs remain to be summarized. Factors involved in the regulation of SLCs can be divided into environmental pollutants, growth factors, cytokine and hormones. Environmental pollutants such as Perfluorooctanoic acid (PFOA) and Triphenyltin (TPT) could suppress SLCs proliferation or differentiation. Growth factors including FGF1, FGF16, NGF and activin A are essential for the maintenance of SLCs self-renewal and differentiation. Interleukin 6 family could inhibit differentiation of SLCs. Among hormones, dexamethasone suppresses SLCs differentiation, while aldosterone suppresses their proliferation. The present review focuses on new progress about factors regulating SLC's proliferation and differentiation which will undoubtedly deepen our insights into SLCs and help make better clinical use of them. Different factors affect on the proliferation and differentiation of stem Leydig cells. Firstly, each rat was intraperitoneally injected EDS so as to deplete Leydig cells from the adult testis. Secondly, the CD51+ or CD90+ cells from the testis of rats are SLCs, and the p75+ cells from human adult testes are human SLCs. These SLCs in the testis start to proliferate and some of them differentiate into LCs. Thirdly, during the SLCs regeneration period, researchers could explore different function of those factors (pollutants, growth factors, cytokines and hormones) towards SLCs.

Combined effects of di (2-ethylhexyl) phthalate and bisphenol A on thyroid hormone homeostasis in adolescent female rats

Phthalates and bisphenols are two typical classes of endocrine-disrupting chemicals (EDCs) which cause endocrine disorder in humans and animals. Phthalates and bisphenols are suggested to be associated with thyroid dysfunction. However, the effects of combined exposure and the detailed mechanisms are yet poorly understood. We investigated the combined effects of di (2-ethylhexyl) phthalate (DEHP) and bisphenol A (BPA) on thyroid function during puberty. Female Sprague Dawley rats were gavaged from postnatal 28 to 70 days with a single or combined exposure of DEHP (0, 150, and 750 mg/kg/day) and BPA (0, 20, and 100 mg/kg/day) according to a 3 × 3 factorial design. The thyroid weights reduced after combined exposure to the highest dose of DEHP and BPA, which noted their adverse effects on thyroid. Additionally, DEHP could increase the number of follicular epithelial cells in thyroid. Both DEHP and in combination with BPA could disturb the levels of thyroid hormones in serum, such as TT3 and TT4. Meanwhile, the possible mechanism was also discussed in the present study. DEHP treatment induced a significant increase of phosphorylation of cAMP-response element binding protein (Creb) via estrogen receptor α (Esr1), while the upregulation was nullified by the concomitant presence of BPA. In conclusion, the complex action of DEHP/BPA mixture may disturb the thyroid hormone homeostasis, which ultimately would affect the development of thyroid during puberty.

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.

Maternal exposure to bisphenol A during pregnancy interferes ovaries development of F1 female mice

This study was conducted to investigate the effects of maternal exposure bisphenol A (BPA) on ovaries development of F1 female mice. The BPA exposure model of pregnant mice was prepared by intragastric administration of BPA at the doses of 0, 2.5, 5, 10, 20, 40 mg kg^-1 d^-1 at gestation day (GD) 0.5-17.5. The ovarian index of the offspring mice was calculated at postnatal day (PND) 21 and PND 56. The results showed that BPA at 5 mg/kg, 10 mg/kg, 20 mg/kg and 40 mg/kg significantly increased the abortion rate of the pregnant mice, and each dose of BPA significantly reduced the survival rate of the pups (P < 0.01 or P < 0.05). Besides, there was a non-monotonic dose-response relationship between serum hormone, ovarian receptor levels and BPA in F1 females at both PND 21 and 56. BPA increased the ovarian/uterine index in F1 females at both PND 21 and 56, increased the mRNA relative transcript levels of ovarian ERα, PgR and DNA methyltransferase (DNMT) in F1 females at PND 21, while decreased at PND 56 (P < 0.01 or P < 0.05). BPA also increased the relative expression of caspase-7, caspase-9, bax, inhibited the relative expression of bcl-2 in F1 females at both PND 21 and 56, and increased the apoptosis rate in the ovaries in F1 mice at PND 56 (P < 0.01). The number of follicles in the ovary was increased in F1 females at PND 21, and the ovaries were significantly atrophied when sexual maturity (PND 56). Our results indicated that BPA could disturb the contents of DNMT and make reproductive injury to the offspring females.

Maternal exposure to bisphenol A during pregnancy interferes testis development of F1 male mice

This study was conducted to investigate the effects of maternal exposure to bisphenol A (BPA) on testis development of F1 male mice. The BPA exposure model of pregnant mice was prepared by intragastric administration of BPA at the doses of 0, 2.5, 5, 10, 20, and 40 mg/kg/day at gestation day (GD) 0.5-17.5. The testis index of the offspring mice was calculated at postnatal day (PND) 21 and PND 56. The results showed that maternal exposure to 20 mg/kg BPA during pregnancy significantly increased the testicular index of F1 males at PND 21, and 40 mg/kg BPA significantly decreased the testicular index of F1 males at PND 56 (P < 0.01). BPA significantly reduced serum testosterone (T) and estradiol (E2) levels, and improved testicular ERα and ERβ levels in F1 males at both PND 21 and PND 56. BPA exposure also upregulated transcription of testicular Dnmt1 and inhibited the transcription of testicular Dnmt3A and Dnmt3B in F1 mice at PND 21. BPA reduced the transcriptional level of testicular DNA methyltransferase (Dnmt), increased the expression of testicular caspase-7, caspase-9, and bax, and decreased the expression of bcl-2 in F1 mice at PND 56. Consistent with that, BPA improved the apoptosis rate in the testis at PND 56 (P < 0.01 or P < 0.05). Our study indicates that BPA disrupts the secretion of testosterone, estradiol, and estrogen receptors by interfering with the transcription of testicular DNA methyltransferase (Dnmt) in offspring males, which damages testicular tissues and affects the potential reproductive function.

Comparative study of environmental pollutants bisphenol A and bisphenol S on sexual differentiation of anteroventral periventricular nucleus and spermatogenesis

BACKGROUND

Bisphenol A is well known endocrine-disrupting chemical while Bisphenol S was considered a safe alternative. The present study aims to examine the comparative effects of xenobiotic bisphenol-A (BPA) and its substitute bisphenol-S (BPS) on spermatogenesis and development of sexually dimorphic nucleus population of dopaminergic neurons in the anteroventral periventricular nucleus (AVPV) of the hypothalamus in male pups.

METHODS

Sprague Dawley rat's pups were administered subcutaneously at the neonatal stage from postnatal day PND1 to PND 27. Thirty animals were divided into six experimental groups (6 animals/group). The first group served as control and was provided with normal olive oil. The four groups were treated with 2 μg/kg and 200 μg/kg of BPA and BPS, respectively. The sixth group was given with 50 μg/kg of estradiol dissolved in olive oil as a standard to find the development of dopaminergic tyrosine hydroxylase neurons in AVPV regions. Histological analysis for testicular tissues and immunohistochemistry for brain tissues was performed.

RESULTS

The results revealed adverse histopathological changes in testis after administration of different doses of BPA and BPS. These degenerative changes were marked by highly significant (p < 0.001) decrease in tubular and luminal diameters of seminiferous tubule and epithelial height among bisphenols treated groups as compared to control. Furthermore, significantly increased (p < 0.001) TH-ir cell bodies in the AVPV region of the brain with 200 μg/kg dose of BPA and BPS was evident.

CONCLUSION

It is concluded that exposure of BPA and BPS during a critical developmental period can structural impairments in testes and affects sexual differentiation of a dimorphic dopaminergic population of AVPV region of hypothalamus in the male brain.

Do prenatal exposures pose a real threat to ovarian function? Bisphenol A as a case study

Fetal development represents a time of potential vulnerability due to rapid cell division, organ development and limited fetal kidney/liver activity for detoxification and metabolism of exposures. Health effects of prenatal toxicant exposure have previously been described, but there is little cohesive evidence surrounding effects on ovarian function. Using bisphenol A (BPA) as a case study, we seek to examine whether a prominent prenatal environmental exposure can pose a real threat to human ovarian function. To do so, we broadly review human oogenesis and menstrual cycle biology. We then present available literature addressing prenatal bisphenol A and diverse outcomes at the level of the ovary. We highlight relevant human cohorts and mammalian models to review the existing data on prenatal exposures and ovarian disruption. Doing so suggests that while current exposures to BPA have not shown marked or consistent results, there is data sufficient to raise concerns regarding ovarian function. Challenges in the examination of this question suggest the need for additional models and pathways by which to expand these examinations in humans.

Bisphenol A stimulates differentiation of rat stem Leydig cells in vivo and in vitro

Bisphenol A (BPA) is widely used in consumer products and a potential endocrine disruptor linked with sexual precocity. However, its action and underlying mechanisms on male sexual maturation is unclear. In the present study, we used a unique in vivo ethane dimethane sulfonate (EDS)-induced Leydig cell regeneration model that mimics the pubertal development of Leydig cells and an in vitro stem Leydig cell differentiation model to examine the roles of BPA in Leydig cell development in rats. Intratesticular exposure to doses (100 and 1000 pmol/testis) of BPA from post-EDS day 14-28 stimulated Leydig cell developmental regeneration process by increasing serum testosterone level and Leydig cell-specific gene (Lhcgr, Star, Cyp11a1, Hsd3b1, Cyp17a1, Hsd17b3, and Hsd11b1) and their protein expression levels. BPA did not alter serum luteinizing hormone and follicle-stimulating hormone levels as well as the proliferative capacity of Leydig cells in vivo. In vitro study demonstrated that BPA (100 nmol/L) stimulated the differentiation of stem Leydig cells by increasing medium testosterone levels and up-regulating Leydig cell-specific gene (Lhcgr, Cyp11a1, Hsd3b1, Cyp17a1, and Hsd17b3) and their proteins but did not affect their proliferation measured by EdU incorporation. In conclusion, BPA stimulates the differentiation of stem Leydig cells in rat testes, thus possibly causing sexual precocity in the male.

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

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

Lycopene reduces in utero bisphenol A exposure-induced mortality, benefits hormones, and development of reproductive organs in offspring mice

This study was conducted to investigate the protective effect of lycopene on reproductive toxicity induced by in utero exposure to bisphenol A (BPA) in offspring mice. Pregnant mice in the BPA model group were given orally 500 mg/kg/day BPA from pregnant day (PD)8 to PD14. Mice of lycopene group were gavaged with 20 mg/kg/day lycopene from PD1 to PD7 and then given 500 mg/kg/day BPA from PD8 to PD14. Results showed that lycopene reduced the elevated mortality in offspring mice of the mother exposed to BPA. BPA lowered the levels of testosterone, luteinizing hormone, and follicle-stimulating hormone while lycopene treatment increased the levels significantly. BPA elevated estradiol while lycopene lowered estradiol in the offspring. BPA caused testicular damage as shown by less Leydig cells and ovarian injury as shown by less corpus granules in adult offspring, while lycopene decreased the damages. Maternal exposure to BPA increased Bax and decreased Bcl-2 in testicular and ovary tissues in the offspring mice. Lycopene decreased Bax in testis and ovary and increased Bcl-2 in ovary tissues in the offspring mice. These findings suggest lycopene has protective effects on in utero BPA exposure-induced reproductive toxicity in offspring mice.

Decreased H3K9ac level of StAR mediated testicular dysplasia induced by prenatal dexamethasone exposure in male offspring rats

Prenatal dexamethasone exposure (PDE) could induce testicular developmental toxicity in adults. The present study aims to confirm its intrauterine origination, and to explore its potential intrauterine programming mechanism. The pregnant rats were respectively injected subcutaneously with 0.2 and 0.8 mg/kg d dexamethasone during gestational days (GD) 9 to 20. The testes and serum of offspring rats were collected on GD20 and postnatal week (PW) 12. In vivo, PDE significantly induced the abnormal testicular morphology in offspring from GD20 to PW12. Moreover, the serum and intratesticular testosterone levels and the expression of testicular steroidogenic acute regulatory protein (StAR) were reduced by PDE. The expression levels of glucocorticoid receptor (GR) and histone deacetylase 7 (HDAC7) were increased in fetal testes. Furthermore, the histone 3 lysine 9 acetylation (H3K9ac) level in the StAR promoter was decreased by PDE from GD20 to PW12. In vitro, mouse Leydig tumour cell line (MLTC-1) cells were treated with dexamethasone (20, 100 and 500 nM), and the testosterone production and StAR expression were reduced. Moreover, dexamethasone increased the expression of HDAC7 by activating GR, which decreased the H3K9ac level in the StAR promoter. Taken together, PDE caused testicular dysplasia before and after birth in male offspring rats, and its mechanism was related to the low-expressional programming of StAR mediated by decreasing H3K9ac level.