Gestational Bisphenol A Exposure Research Articles

Gestational exposure to BPA alters the expression of glucose and lipid metabolic mediators in the placenta: Role in programming offspring for obesity

Bisphenol A (BPA) exposure during pregnancy is known to predispose offspring to obesity in later life. Our previous studies demonstrated obesogenic effects in BPA-exposed offspring, including excess body fat, increased feed efficiency, adipocyte hypertrophy, and altered leptin signaling. However, the role of the placenta in mediating these effects remained unclear. This study investigates the mechanisms by which BPA exposure affects placental glucose and lipid transporters and their impact on offspring adiposity in Wistar rats. Dams were orally gavaged with BPA [0.4 (low dose-LD) and 4.0 (high dose-HD) μg/kg body weight] from gestational day (gD) 4–14. Gestational exposure to LD BPA increased the expression of 11β hydroxysteroid dehydrogenase 1 (11β HSD1) and estrogen receptor alpha (ERα) proteins (p<0.05) in the placenta compared to control and HD BPA. Similar changes were observed in the expression of mTOR signaling mediators, fatty acid transporters, and intracellular fatty acid-binding proteins. There were no changes in the dam's body weight or lipid and glucose profiles. However, there was a dose dependent increase in glucose transporter (GLUT1) expression in the placenta. While LD BPA increased hexokinase 2 expression in the placenta, HD BPA had no effect. Both doses of BPA increased IL6 expression, but only LD BPA exposure increased PPAR-gamma expression. Additionally, BPA exposure induced ADRP expression and localization, suggesting potential lipid overload in the placenta. Furthermore, BPA exposure altered the placental epigenetic profile, with increased expression of DNA methyltransferases (DNMTs). Overall, gestational BPA exposure led to dose-specific alterations in placental glucose and lipid metabolic activities, possibly playing an role in increasing the supply of these macronutrients to the fetus and predisposing the offspring to obesity.

Developmental programming: An exploratory analysis of pancreatic islet compromise in female sheep resulting from gestational BPA exposure

Developmental exposure to endocrine disruptors like bisphenol A (BPA) are implicated in later-life metabolic dysfunction. Leveraging a unique sheep model of developmental programming, we conducted an exploratory analysis of the programming effects of BPA on the endocrine pancreas. Pregnant ewes were administered environmentally relevant doses of BPA during gestational days (GD) 30–90, and pancreata from female fetuses and adult offspring were analyzed. Prenatal BPA exposure induced a trend toward decreased islet insulin staining and β-cell count, increased glucagon staining and α-cell count, and increased α-cell/β-cell ratio. Findings were most consistent in fetal pancreata assessed at GD90 and in adult offspring exposed to the lowest BPA dose. While not assessed in fetuses, adult islet fibrosis was increased. Collectively, these data provide further evidence that early-life BPA exposure is a likely threat to human metabolic health. Future studies should corroborate these findings and decipher the molecular mechanisms of BPA's developmental endocrine toxicity.

Gestational bisphenol A exposure advances puberty onset in female offspring: Critical time window identification

Increasing evidence shows that the early onset of puberty in female offspring may be caused by maternal prenatal exposure to bisphenol A (BPA) during pregnancy; however, the critical time window of maternal prenatal BPA exposure remains unknown. Here, we identify the critical time window of gestational BPA exposure that induces early onset of puberty in female offspring. Pregnant CD-1 mice were gavaged with BPA (8 mg/kg) daily during the early gestational stage (GD1–GD6), middle gestational stage (GD7–GD12) or late gestational stage (GD13–GD18). We show that maternal BPA exposure during the early and middle gestational stages could advance the vaginal opening time and increase the serum levels of kisspeptin-10 and GnRH in the female offspring at PND 34. Mechanistically, maternal BPA exposure during early and middle gestation could significantly increase CpG island methylation in the Eed gene promoters but reduce the mRNA expression of Eed in the hypothalamus tissues of the female offspring. In conclusion, the critical period of maternal BPA exposure-induced early onset of puberty in female offspring is early and middle gestation; this BPA-induced early onset of puberty might be partly attributed to epigenetic programming of the Eed gene in the hypothalamus. This study provides important insights regarding the relationship and the mechanisms between BPA and offspring pubertal development.

ODP269 Impacts of Gestational Bisphenol A Exposure on Adult Hypothalamic Neurogenesis

Abstract Regulation of physiological homeostasis by the hypothalamus is influenced by low basal levels of adult neurogenesis arising from proliferative cell populations in various hypothalamic regions. Adult hypothalamic neurogenesis is involved in maintenance of energy homeostasis and is responsive to energy balance disruptions. Hormones such as oestradiol interact with energy balance disruptions to alter rates of prenatal and adult neurogenesis, demonstrating sensitivity of hypothalamic neural progenitor cells to endogenous hormones. We previously showed that gestational exposure to the hormone mimic bisphenol A (BPA) accelerates embryonic hypothalamic neurogenesis with lasting effects on hypothalamic function into adulthood (1). The impact of gestational exposure to BPA on hypothalamic progenitors that contribute to adult neurogenesis has not been explored. The present study examines the interaction between energy balance disruptions via high-fat diet and the lasting impact of gestational BPA exposure on adult hypothalamic neurogenesis. Pregnant dams were either fed a control diet or chow laced with a low dose of BPA (50 μg per kg diet), then offspring were placed on low-fat or high-fat diet throughout adolescence (postnatal day (P) 5-35) and weighed every 5 days to assess physical changes. Intraperitoneal injections of BrdU were conducted twice a day from P45-53 to mark proliferating cells. To identify changes in the number and/or type of proliferating cells as a result of gestational BPA exposure and diet changes, brains from mice sacrificed at P54 and P75 were co-stained for BrdU and cell type specific markers to label neurons, oligodendrocytes, or astrocytes. Results showed that in adolescent animals on low-fat diet, BPA exposure decreased weight gain compared to controls (7.68±4.22 g vs. 8.50±3.98g;p&amp;lt; . 0001; n≥20 per group). Similarly, in adolescent animals on high-fat diet, BPA exposure decreased weight gain compared to controls (8.54±2. 02 g vs. 9.97±4.89g;p&amp;lt; . 0001; n≥20 per group). There was no impact on weight gain in adult male mice, however in adult female mice on low-fat diet, BPA exposure decreased weight gain compared to controls (18.33±1.45 g vs. 18.97±1.50 g;p=. 019; n≥7 per group). The opposite effect was seen in adult female mice on high-fat diet, where BPA exposure increased weight gain compared to controls (20. 07±1.51 g vs. 19.62±1.478 g;p=. 050; n≥7 per group). Preliminary data demonstrate a trending increase in hypothalamic neurogenesis in adult P54 females on low-fat diet exposed to BPA compared to controls (200.15±34.85 BrdU+/NeuN+ cells vs. 69. 00±6. 00 BrdU+/NeuN+ cells, n=2) and on high-fat diet exposed to BPA compared to controls (169.65±101.65 BrdU+/NeuN+ cells vs. 50.15±17.85 BrdU+/NeuN+ cells, n=2). These data suggest BPA may have an estrogenic effect on hypothalamic neural progenitors, resulting in disruptions to adult hypothalamic neurogenesis and energy balance homeostasis. Reference: (1) Nesan et al., Science Adv. 2021 May 28;7(22): eabd1159 . Presentation: No date and time listed

RF22 | PMON11 Non-coding RNA Signatures of Prenatal BPA Exposure in Liver and Muscle of Female Sheep

Abstract Prenatal exposure to bisphenol-A (BPA), an ubiquitously present endocrine-disrupting chemicals, induces peripheral insulin resistance as well as lipotoxicity and oxidative stress in the liver and muscle along with tissue-specific transcriptional changes in female sheep. To gain a mechanistic understanding of contributors to these liver and muscle-specific transcriptional changes, we hypothesized that prenatal BPA exposure impacts non-coding RNA (ncRNA), regulators of transcriptional and post-transcriptional control of coding RNAs. We sequenced ncRNA (including lncRNA, microRNA, snoRNA, and snRNA) in the liver and muscle obtained during the late follicular phase from 21-month-old control and prenatal BPA-treated (0.5mg/kg/day from days 30 to 90 of gestation; Term: 147days) female sheep (n=4 control and 4 prenatal BPA treated). The sequence data were subjected to differential expression analysis and multivariate modeling to identify specific ncRNA signatures. In the liver, 77 lncRNA (49 down, 28 up), 14 microRNAs (6 down, 8 up), 127 snoRNAs (63 down, 64 up) and 55 snRNAs (15 down, 40 up) were dysregulated (FDR&amp;lt;0.1, absolute log2FC&amp;gt;0.5) with BPA exposure. In the muscle 6 lncRNA were upregulated and 65 snoRNAs (47 down, 18 up) were dysregulated (FDR&amp;lt;0.1, absolute log2FC&amp;gt;0.5). Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) plots identified microRNAs MIR200B, MIR409, MIR30B, and MIR154A in the liver and miRNAs MIR26B, MIR29A, MIR125B, and MIR127 in muscle and several uncharacterized ncRNAs as signatures of prenatal BPA exposure. Multiple ncRNA signatures correlated with coding genes including LCORL, MED17, and ZNF41 in the liver, but none were correlated in the muscle. Among the coding genes which correlated with ncRNA, LCORL is reported to be related to steatosis of the liver in geese, a feature also observed in livers from prenatal BPA-treated female sheep. Since lipid accumulation in the liver may result from increased fatty acid biosynthesis, MED17 which is involved in transcriptional activation of lipogenic genes that correlated with multiple ncRNA in the liver may be a contributor to the steatosis observed in this model. In addition, MIR200B and MIR30B in the liver and MIR26B and MIR29A in the muscle are linked to lipid dysfunction, endoplasmic reticulum stress, and fibrosis. These findings provide mechanistic clues into the role of ncRNA in the prenatal BPA-induced lipid accumulation and oxidative stress in the liver and muscle, contributors to metabolic dysfunction observed in this female sheep model of gestational BPA exposure. In addition, findings from this precocial model of human translational relevance is a step towards gaining mechanistic insights in the programming of metabolic dysfunctions from environmental exposure to BPA, an endocrine disruptor of public health relevance. Presentation: Sunday, June 12, 2022 1:06 p.m. - 1:11 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Sex-specific extracellular matrix remodeling during early adipogenic differentiation by gestational bisphenol A exposure.

Bisphenol A (BPA) is an endocrine disrupting chemical known to promote adipose tissue mass in vivo and adipogenesis in vitro. Whether BPA can affect and reprogram early adipogenic differentiation signals that trigger adipogenic differentiation, remains unknown. We hypothesized that gestational BPA exposure results in a preadipocyte phenotype that leads to accelerated adipogenic differentiation, and that this phenotype is sex specific. Primary ovine fetal preadipocytes were derived from control (C) and BPA-exposed during pregnancy and differentiated in vitro. Gestational BPA enhanced lipid accumulation at early stages of differentiation (48h) and this was evident in females but not male-derived fetal preadipocytes. After an RNA sequencing approach, samples were compared as follows: 2 groups (C vs. BPA); 2 sexes (female (F) vs. male (M)); and 2 time points (0h vs. 48 h). Before differentiation, 15 genes were differentially expressed between the C and the BPA-exposed preadipocytes within sex. In BPA-F, extracellular matrix remodeling genes cathepsin K and collagen 5α3 were upregulated compared to C-F. At 48h, BPA-F had 154 genes differentially expressed vs. C-F and BPA-M had 487 genes differentially expressed vs. C-M. Triglyceride and glycerophospholipid metabolism were the most upregulated pathways in BPA-F. Downregulated pathways were associated with extracellular matrix organization in BPA-exposed preadipocytes. These findings are among the first to demonstrate that gestational BPA can modify the fate of adipocyte precursors by altering pathways associated to extracellular matrix components, an often-disregarded, but required aspect of adipogenic differentiation. This work highlights the need to investigate early adipogenic differentiation changes in other obesogenic chemicals.

Gestational exposure to bisphenol analogues and kisspeptin levels in pregnant women and their children: A pregnancy-birth cohort study

Gestational exposure to bisphenol analogues (BPs)，especially bisphenol A (BPA), has been associated with adverse pregnancy-related outcomes and altered reproductive development of offspring, but the underlying mechanisms are not well documented. Kisspeptin, a key regulator of reproductive health, could be the potential target for endocrine disrupting compounds like BPs. Among 528 mother-child pairs, we investigated the associations of gestational BPs exposure with kisspeptin levels in two critical life stages, pregnancy and pre-puberty. Maternal BPs and kisspeptin concentrations were measured in urine samples collected in the third trimester. Children's urine samples were collected at 6-year visit and analyzed for kisspeptin levels. Associations were observed between BPA and its alternatives and lower kisspeptin in pregnant women but higher kisspeptin in their children. In contrast, TCBPA was suggestively associated with higher kisspeptin in pregnant women but lower kisspeptin in children. Our study provides the first epidemiologic evidence that gestational exposure to selected BPs may be associated with altered kisspeptin system in both pregnant women and their children, sheds some light on the potential mechanisms underlying the various reproductive health outcomes following gestational BPA exposure, and suggests potential reproductive toxicities of other BPs in humans.

Developmental programming: Impact of prenatal bisphenol-A exposure on liver and muscle transcriptome of female sheep

Gestational Bisphenol A (BPA) exposure leads to peripheral insulin resistance, and hepatic and skeletal muscle oxidative stress and lipotoxicity during adulthood in the female sheep offspring. To investigate transcriptional changes underlying the metabolic outcomes, coding and non-coding (nc) RNA in liver and muscle from 21-month-old control and prenatal BPA-treated (0.5 mg/kg/day from days 30 to 90 of gestation; Term: 147 days) female sheep were sequenced. Prenatal BPA-treatment dysregulated: expression of 194 genes (138 down, 56 up) in liver and 112 genes (32 down, 80 up) in muscle (FDR < 0.05 and abs log2FC > 0.5); 155 common gene pathways including mitochondrial-related genes in both tissues; 1415 gene pathways including oxidative stress and lipid biosynthetic process specifically in the liver (FDR < 0.01); 192 gene pathways including RNA biosynthetic processes in muscle (FDR < 0.01); 77 lncRNA (49 down, 28 up), 14 microRNAs (6 down, 8 up), 127 snoRNAs (63 down, 64 up) and 55 snRNAs (15 down, 40 up) in the liver while upregulating 6 lncRNA and dysregulating 65 snoRNAs (47 down, 18 up) in muscle (FDR < 0.1, abs log2FC > 0.5). Multiple ncRNA correlated with LCORL, MED17 and ZNF41 mRNA in liver but none of them in the muscle. Discriminant analysis identified (p < 0.05) PECAM, RDH11, ABCA6, MIR200B, and MIR30B in liver and CAST, NOS1, FASN, MIR26B, and MIR29A in muscle as gene signatures of gestational BPA exposure. These findings provide mechanistic clues into the development and/or maintenance of the oxidative stress and lipid accumulation and potential for development of mitochondrial and fibrotic defects contributing to the prenatal BPA-induced metabolic dysfunctions.

Gestational Bisphenol A Exposure Impacts Embryonic Hypothalamic Microglia Numbers, Ramification, and Phagocytic Cups.

Microglia are a resident population of phagocytic immune cells that reside within the central nervous system (CNS). During gestation, they are highly sensitive to their surrounding environment and can alter their physiology to respond to perceived neural insults, potentially leading to adverse influences on nearby neural progenitors. Given that bisphenol A (BPA) itself can impact developing brains, and that microglia express estrogen receptors to which BPA can bind, here we asked whether fetal microglia are responsive to gestational BPA exposure. Accordingly, we exposed pregnant dams to control or 50 mg of BPA per kg diet during gestation to investigate the impact of maternal BPA on embryonic hypothalamic microglia. Gestational BPA exposure from embryonic day 0.5 (E0.5) to E15.5 resulted in a significant increase in the number of microglia present in the hypothalamus of both male and female embryos. Staining for microglial activation using CD68 showed no change between control and prenatal BPA-exposed microglia, regardless of sex. Similarly, analysis of cultured embryonic brains demonstrated that gestational BPA exposure failed to change the secretion of cytokines or chemokines, regardless of embryo sex or the dose (50 μg of BPA per kg or 50 mg of BPA per kg maternal diet) of BPA treatment. In contrast, live-cell imaging of microglia dynamics in E15.5 control and gestationally-exposed BPA hypothalamic slices showed increased ramification of microglia exposed to BPA. Moreover, live-cell imaging also revealed a significant increase in the number of microglial phagocytic cups visible following exposure to gestational BPA. Together, these results suggest that gestational BPA exposure impacts embryonic hypothalamic microglia, perhaps leading them to alter their interactions with developing neural programs.

Gestational bisphenol A exposure impairs hepatic lipid metabolism by altering mTOR/CRTC2/SREBP1 in male rat offspring.

Lipid metabolism is an important biochemical process in the body. Recent studies have found that environmental endocrine disruptors play an important role in the regulation of lipid metabolism. Bisphenol A (BPA), a common environmental endocrine disruptor, has adverse effects on lipid metabolism, but the mechanism is still unclear. This study aimed to investigate the effects of gestational BPA exposure on hepatic lipid metabolism and its possible mechanism in male offspring. The pregnant Sprague-Dawley rats were exposed to BPA (0, 0.05, 0.5, 5mg/kg/day) from day 5 to day 19 of gestation to investigate the levels of triglyceride (TG) and total cholesterol (TC), and the expression of liver lipid metabolism-related genes in male offspring rats. The results showed that compared with the control group, the TG and TC levels in serum and liver in BPA-exposed groups was increased. And the expressions of liver fatty acid oxidation related genes, such as peroxisome proliferators-activated receptor α (PPARα) and carnitine palmitoyl transferase 1α (CPT1α), were down-regulated. However, the expressions of fatty acid synthesis related genes, such as sterol regulatory element binding proteins 1 (SREBP-1), acetyl-CoA carboxylase 1 (ACC1), fatty acid synthase (FAS) and stearoyl-CoA desaturase 1 (SCD-1), were up-regulated. The increased protein levels of mTOR and p-CRTC2 suggested that CREB-regulated transcription coactivator 2 (CRTC2) might be an important mediator in the mTOR/SREBP-1 pathway. In conclusion, these results demonstrated that mTOR/CRTC2/SREBP-1 could be affected by gestational BPA exposure, which may involve in the lipid metabolic disorders in later life.

Gestational and lactational exposure to BPA, but not BPS, negatively impacts trabecular microarchitecture and cortical geometry in adult male offspring

Bisphenol-A (BPA) and bisphenol-S (BPS) are endocrine disrupting chemicals (EDCs) found primarily in plastics. Estrogen is a primary hormonal regulator of skeletal growth and development; however, the impact of gestational BPA or BPS exposure on skeletal health of offspring remains relatively unknown. Here, adult female mice were randomized into three treatment groups: 200 μg BPA/kg BW (BPA), 200 μg BPS/kg BW (BPS) or control (CON). Animals were then further randomized to exercising (EX) or sedentary (SED) groups. Treatment continued through mating, gestation, and lactation. One male offspring from each dam (n = 6–8/group) was assessed at 16 weeks of age to evaluate effects of EDC exposure on the adult skeleton. Cortical geometry of the mid-diaphysis and trabecular microarchitecture of the distal femur were assessed via micro-CT. Biomechanical strength and mineral apposition rate of the femoral diaphysis were assessed via three-point bending and dynamic histomorphometry, respectively. Two-factor ANOVA or ANCOVA were used to determine the effects of maternal EX and BPA or BPS on trabecular and cortical bone outcomes. Maternal EX led to a significant decrease in body fat percentage and bone stiffness, independent of EDC exposure. Offspring exposed to BPA had significantly lower trabecular bone volume, trabecular number, connectivity density, cortical thickness, and greater trabecular spacing compared to BPS or CON animals. In conclusion, gestational BPA, but not BPS, exposure negatively impacted trabecular microarchitecture and cortical geometry in adult male offspring. If these findings translate to humans, this could have significant public health impacts on expecting women or those seeking to become pregnant.

Gestational and lactational exposure to BPA or BPS has minimal effects on skeletal outcomes in adult female mice

Bisphenol-A (BPA) and bisphenol-S (BPS) are estrogen disrupting chemicals (EDCs) found in the environment and common household items. Estrogen is a primary hormonal regulator of bone growth and development; however, the impact of gestational BPA or BPS exposure on skeletal health of offspring remains relatively unknown. In this longitudinal study, adult female mice were randomized into three groups: 200 μg BPA/kg BW (BPA), 200 μg BPS/kg BW (BPS) or control (CON). Animals in each group were further randomized to exercise treatment (EX) or sedentary (SED) control, resulting in six overall groups. BPA/BPS/CON and EX/SED treatment were initiated prior to mating and continued through mating, gestation, and lactation. One female offspring from each dam (n = 6/group) was assessed at 17 weeks of age to evaluate effects of EDC exposure on the adult skeleton. Cortical geometry of the mid-diaphysis and trabecular microarchitecture of the distal femur were assessed via micro-computed tomography. Biomechanical strength and mineral apposition rate of the femoral diaphysis were assessed via three-point bending and dynamic histomorphometry, respectively. Sclerostin expression was measured using immunohistochemistry. Two-factor ANOVA or ANCOVA were used to determine the effects of maternal exercise and BPA or BPS exposure on trabecular and cortical bone outcomes, respectively. Consistent with prior studies, there were no significant differences in body weight, femoral length, cortical geometry, trabecular microarchitecture, or biomechanical strength between groups in female offspring. In conclusion, gestational BPA exposure and maternal exercise have minimal impact on skeletal outcomes in female adult offspring.

Gestational bisphenol A exposure induces fatty liver development in male offspring mice through the inhibition of HNF1b and upregulation of PPAR\u03b3

Bisphenol A (BPA) is an endocrine-disrupting chemical (EDC) associated with non-alcoholic fatty liver disease (NAFLD). The effects of gestational BPA exposure on hepatic lipid accumulation in offspring are not fully understood. Here, we investigate the sex-dependent effects of gestational BPA exposure on hepatic lipid and glucose metabolism in the offspring of mice to reveal the mechanisms underlying gestational BPA exposure-associated NAFLD. Pregnant mice were administered gavage with or without 1 μg kg−1 day−1 BPA at embryonic day 7.5 (E7.5)–E16.5. Hepatic glucose and lipid metabolism were evaluated in these models. Both male and female offspring mice exhibited hepatic fatty liver after BPA treatment. Lipid accumulation and dysfunction of glucose metabolism were observed in male offspring. We revealed abnormal expression of lipid regulators in the liver and that inhibition of peroxisome proliferator-activated receptor γ (PPARγ) repressed hepatic lipid accumulation induced by gestational BPA exposure. We also found a sex-dependent decrease of hepatocyte nuclear factor 1b (HNF1b) expression in male offspring. The transcriptional repression of PPARγ by HNF1b was confirmed in L02 cells. Downregulation of HNF1b, upregulation of PPARγ, and subsequent upregulation of hepatic lipid accumulation were essential for NAFLD development in male offspring gestationally exposed to BPA as well as BPA-exposed adult male mice. Dysregulation of the HNF1b/PPARγ pathway may be involved in gestational BPA exposure-induced NAFLD in male offspring. These data provide new insights into the mechanism of gestational BPA exposure-associated sex-dependent glucose and lipid metabolic dysfunction.Graphical abstractSchematic of the mechanism of gestational BPA exposure-induced glucose and lipid metabolic dysfunction.

OR23-4 Low-Dose Gestational BPA Exposure Alters Circadian Rhythms in Mice

Bisphenol A (BPA) is a well-characterized endocrine disruptor known to act via multiple steroid signaling pathways. Previously we have shown that the hypothalamus, a key regulator of neuroendocrine activity, is particularly susceptible to endocrine disruption by BPA, with low-dose gestational exposure resulting in accelerated neurogenesis and altered behavior, including hyperactivity, in both zebrafish and mice. The suprachiasmatic nucleus (SCN) of the hypothalamus is the regulator of the circadian clock, and we hypothesize a link between altered SCN function and the observed hyperactivity in BPA exposed animals. Here we present the effects of low-dose, environmentally relevant gestational BPA exposure on circadian rhythms in mice. We characterized mice exposed to BPA (50 μg/kg via diet) in utero by measuring their activity levels during a normal 12:12 light/dark (l/d) cycle, followed by entrainment to a 24h dark (d/d) period. We observed significant alterations in circadian rhythms as a result of gestational BPA exposure. BPA mice were significantly more active than control mice in l/d conditions, specifically in the late stages of the dark phase when control mice had usually completed their daily bouts of activity. BPA-exposed mice also exhibited less of an anticipatory onset of activity just prior to the start of the dark phase, and we observed a slight, female-specific increase in circadian period (tau). BPA-mediated disruptions of circadian rhythms were exaggerated under d/d conditions. BPA mice again showed significantly higher activity than control mice, and both male and female mice exhibited a significant decrease in tau. Finally, we observed that BPA-exposed mice appear to entrain more quickly to new conditions, both in the shift from l/d to d/d, and in response to short-term light exposure during the d/d testing. Overall, we conclude that low-dose gestational BPA exposure alters circadian rhythms under various conditions, the first such finding in a mammalian model in vivo, and that this may be a contributing factor to the observed hyperactivity in BPA-exposed mice.

SAT-203 Gestational Bisphenol A Exposure Induces Inflammatory, Oxidative Stress and Lipotoxic Changes in the Placenta of Female Sheep

Widespread exposure to environmental endocrine disrupting chemicals (EDC) has been attributed in part to the rise in non-communicable diseases. Pregnant women and their developing fetuses are vulnerable to exposure from EDC leading to adult onset disorders in the offspring in accordance with the developmental origin of health and disease (DOHAD) hypothesis. Bisphenol A (BPA) is one such EDC with estrogenic, anti-androgenic, and metabolism disrupting properties. BPA has been detected in >90% of US population. Gestational BPA exposure has been found to be associated with low birth weight, a risk factor for adult onset diseases in both human and sheep. The low birth weight may be the consequence of reduced placental efficiency stemming from disruption in inflammatory, oxidative stress and metabolic homeostasis, such as that reported in pregnancies accompanying maternal obesity and gestational diabetes. We hypothesized that gestational BPA treatment at environmentally relevant levels leads to placental inflammation, oxidative stress and lipid accumulation during early pregnancy accounting for the poor birth outcome observed. Gestational day 65 placentae were collected from pregnant Suffolk treated with 0.5mg/kg/day BPA sc starting from day 30 of gestation. Controls received equal volume of corn oil (vehicle).This BPA dose produces 1.6 ng/mL BPA concentration in the umbilical artery, levels close to that observed in the maternal circulation in US. Inflammatory markers and antioxidant expression were determined by real time RT-PCR, byproducts of lipid peroxidation (index of oxidative damage) measured using thiobarbituric acid reactive substances (TBARS) assay, and lipid accumulation as an index of lipotoxicity by oil red O staining. Data were analyzed by Student’s t-test and Cohen’s effect size analysis. Prenatal BPA treatment induced a significant (p < 0.05) increase in antioxidants glutathione reductase, and superoxide dismutase 1 and 2. While Cohen’s effect size analysis showed (1) large magnitude increase in macrophage marker CD68 and medium magnitude increase in proinflammatory cytokines chemokine ligand 2 and interleukin 1 beta; (2) large magnitude increase in TBARS, and (3) medium magnitude increase in oil red O staining in placenta from prenatal BPA. These preliminary findings indicate that gestational BPA exposure induces early disruptions in placental milieu via increased inflammation, oxidative stress and lipid accumulation. The increase in antioxidant expression evidenced in placentae of prenatal BPA treated sheep may reflect a compensatory response to overcome the oxidative stress state. The altered placental milieu may lead to reduced placental efficiency thus contributing to the low birth weight and the cardio-metabolic defects seen in prenatal BPA-treated sheep. Supported by NIH ES-016541.

Prenatal Bisphenol A Exposure Alters Epithelial Cell Composition in the Rhesus Macaque Fetal Oviduct.

Bisphenol A (BPA) is an endocrine disrupting compound that is a pervasive environmental contaminant. Although it has been reported to affect the development of a variety of fetal reproductive tissues, data on the effect of fetal BPA exposure on oviducts were extremely limited and were only available in mice. To determine if there are adverse effects of gestational BPA exposure on fetal oviduct, we exposed pregnant rhesus macaques with female fetuses to oral or nonoral BPA during the last trimester of gestation (day 100 to term). After the treatment, fetal oviducts were collected for morphology evaluation. BPA exposure altered the percentages of different cell types (ciliated, nonciliated, and secretory) in the fetal oviduct and resulted in a significant high ciliated cell population in the BPA-exposed fetal oviduct. The distribution of ciliated cells on the epithelium in the BPA-exposed fetal oviduct was also altered. Gestational BPA exposure reduced the expression of mucosubstance and uteroglobin in secretory cells in the fetal oviduct. A comparison of the outcome of the fetal oviduct studies with similar outcomes previously reported in the lung from the same fetuses demonstrates that BPA exhibits opposite effects in these two organs. In conclusion, the BPA-associated alterations in the fetal oviduct could potentially affect the oviduct morphology and function later in life with a negative impact on fertility. The mechanisms of action of the differential response in the oviduct and the lung to BPA exposure require further investigation.

Functional and Proteomic Alterations of F1 Capacitated Spermatozoa of Adult Mice Following Gestational Exposure to Bisphenol A.

Studies regarding bisphenol A (BPA) exposure and male (in)fertility have conventionally focused on modifications in ejaculated spermatozoa function from exposed individuals. However, mammalian spermatozoa are incapable of fertilization prior to achieving capacitation, the penultimate step in maturation. Therefore, it is necessary to investigate BPA-induced changes in capacitated spermatozoa and assess the consequences on subsequent fertilization. Here, we demonstrate the effect of gestational BPA exposure (50 μg/kg bw/day, 5 mg/kg bw/day, and 50 mg/kg bw/day) on the functions, biochemical properties, and proteomic profiles of F1 capacitated spermatozoa from adult mice. The data showed that high concentrations of BPA inhibited motility, motion kinematics, and capacitation of spermatozoa, perhaps because of increased lipid peroxidation and protein tyrosine nitration, and decreased intracellular ATP levels and protein kinase-A activity in spermatozoa. We also found that BPA compromised the rates of fertilization and early embryonic development. Differentially expressed proteins identified between BPA-exposed and control groups play a critical role in energy metabolism, stress responses, and fertility. Protein function abnormalities were responsible for the development of several diseases according to bioinformatics analysis. On the basis of these results, gestational exposure to BPA may alter capacitated spermatozoa function and the proteomic profile, ultimately affecting their fertility potential.

Effects of maternal or paternal bisphenol A exposure on offspring behavior

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

Sex-Specific Modulation of Fetal Adipogenesis by Gestational Bisphenol A and Bisphenol S Exposure.

The endocrine-disrupting chemical bisphenol A (BPA) increases adipose tissue mass in vivo and promotes adipogenesis in vitro; however, mechanisms explaining BPA's obesogenic effect remain unknown. We investigated the effects of gestational BPA and its analog, bisphenol S (BPS), exposure on the adipogenic differentiation ability of fetal preadipocytes and the role of endoplasmic reticulum stress in regulating this process. Pregnant sheep (n = 7 to 8 per group) mated to the same male were exposed to BPA or BPS from days 30 to 100 of gestation; pregnancies were terminated 20 days later. Adipose tissue was harvested and fetal preadipocytes isolated. Adipose tissue gene expression, adipocyte size, preadipocyte gene expression, adipogenic differentiation, and dynamic expression of genes involved in adipogenesis and endoplasmic reticulum stress were assessed. Gestational BPA enhanced adipogenic differentiation in female, but not male, preadipocytes. The unfolded protein response (UPR) pathway was upregulated in BPA-exposed female preadipocytes supportive of a higher endoplasmic reticulum stress. Increased expression of estradiol receptor 1 and glucocorticoid receptor in female preadipocytes suggests that this may be a potential cause behind the sex-specific effects observed upon BPA exposure. Gestational BPS affected adipogenic terminal differentiation gene expression in male preadipocytes, but not adipogenic differentiation potential. We demonstrate that gestational BPA exposure can modulate the differentiation ability of fetal preadipocytes. UPR upregulation in gestationally BPA-exposed female preadipocytes may contribute to the increased preadipocyte's adipogenic ability. The marked sex-specific effect of BPA highlights higher susceptibility of females to bisphenol A and potentially, a higher risk to develop obesity in adulthood.

Abstract 4826: Maternal high butter fat intake heightens mammary cancer risk in offsprings gestationally exposed to bisphenol A at environmentally relevant dose

Abstract In utero exposure to bisphenol A (BPA) at 250ug/kg BW was shown to augment mammary cancer risk in rodent models. High fat diet is widely believed to be a major risk of breast cancer (BCa). It is therefore important to investigate whether maternal high fat intake could potentially heighten mammary cancer risk associated to gestational BPA exposure. In this study, we exposed Sprague Dawley rats with different doses of BPA (2.5-2500ug/kg BW) mixed with high butter-based diet (HBF) in the period from preconception to birth. DMBA-PND50 protocol was followed. In the presence of HBF, we observed non-monotonic effects of BPA in cancer incidence as well as in the number of terminal end buds of PND21 mammary glands. Both results were peaked at a dosage of 25ug/kg BW BPA and the effects were significant when compared with HBF alone group. We further analyzed transcriptomic data of microdissected epithelia of PND21 mammary glands from BPA (25ug/kg BW) group as well as HBF group and revealed that two specific cancer networks involving ERK and androgen receptor signaling were dysregulated. DNA methylation is one of the key mechanisms to dysregulate and impair the transcription of two selected top genes, Car7 and Kcnv2, as supported by our bisulfite-sequencing data. These data suggest that in utero BPA exposure could epigenetically modify gene expression and predispose cancer risk during early development. More importantly, some BPA genes are of high human relevance because seven selected BPA genes could dichotomize patients into two groups with significant difference in overall survival in a TCGA cancer cohort. The prognostic power of the genes was further enhanced in the survival analysis of Caucasian with ER positive patients. In conclusion, our data strongly suggest that BPA predisposes higher cancer risk by dysregulating gene expression during early mammary gland development in the presence of HBF, which could facilitate cancer development later in life. Citation Format: Yuet-Kin Leung, Vinothini Govindarajah, Ana Cheong, Dan Song, Xuegong Zhu, Jun Ying, Ady Kendler, Mario Medvedovic, Scott Belcher, Shuk-Mei Ho. Maternal high butter fat intake heightens mammary cancer risk in offsprings gestationally exposed to bisphenol A at environmentally relevant dose [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4826. doi:10.1158/1538-7445.AM2017-4826