Impact of prenatal exposure to bisphenol A on pregnant rats: Fetal bone development and immunohistochemistry implications

Effects of prenatal single and mixed bisphenol exposure on bone mineral density in preschool children: A population-based prospective cohort study

Exposure to bisphenols can affect bone mineral density (BMD) in animals and humans. However, the effects of maternal exposure to bisphenols during pregnancy on bone health in preschool children remain unknown. We aimed to assess the effects of prenatal exposure to single and multiple bisphenols on bone health in preschool children. A total of 230 mother-child pairs were included in this study. Generalized linear regression, restricted cubic spline (RCS), principal component analysis (PCA), and Bayesian kernel machine regression (BKMR) were utilized to assess the relationship between bisphenol levels and bone health in preschool children. Each natural log (Ln) unit increase in tetrabromobisphenol A was related to a 0.007 m/s (95 % CI: -0.015, 0.000) decrease in Ln-transformed speed of sound (SOS) among girls. Decreased BMD Z scores in preschool children were found only in the high bisphenol S exposure group (β = -0.568; 95 % CI: -1.087, -0.050) in boys. The risk of low BMD (BMDL) was significantly higher in the middle-exposure group (OR = 4.695; 95 % CI: 1.143, 24.381) and high-exposure group of BPS (OR = 6.165, 95 % CI: 1.445, 33.789) compared with the low-exposure group in boys. In girls, the risk of BMDL decreased with increasing bisphenol A concentration (OR = 0.413, 95 % CI: 0.215, 0.721). RCS analysis revealed a U-shaped nonlinear correlation between BPB concentration and BMDL in girls (P-overall = 0.011, P-nonlinear = 0.009). In PCA, a U-shaped dose-response relationship was found between PC2 and the risk of BMDL (P-overall = 0.048, P-nonlinear = 0.032), and a significant association was only noted in girls when stratified by sex. The BKMR model revealed a horizontal S-shaped curve relationship between bisphenol mixtures and BMDL in girls. The results indicated that prenatal exposure to single and mixed bisphenols can affect BMD in preschool children, exerting nonmonotonic and child sex-specific effects.

Bone development in offspring of pregnant rats treated with carbamazepine: Evaluation by three different methods

OBJECTIVE

This study was carried out to determine the effect of intrauterine carbamazepine (CBZ) exposure on fetal bone development during pregnancy.

METHODS

In the study, 24 female Wistar pregnant rats were used. Rats were 20 weeks old. They had an average body weight of 150-200 g. Pregnant rats were randomly selected and divided (n = 6) into a control group, low-dose CBZ (10 mg/kg/day) group, medium-dose CBZ (25 mg/kg/day) group, and high-dose CBZ (50 mg/kg/day) group. The ossification length (mm) and ossification area (mm² ) of the long bones of the fetuses in the experimental and control groups were calculated. The densities of alkaline phosphatase (AP) and tartrate-resistant acid phosphatase (TRAP) were analyzed. The ossification regions of the femurs of the fetuses were examined under a light microscope. Microstructural images of the femurs were evaluated with scanning electron microscope photographs. The densities of minerals involved in the ossification process were analyzed.

RESULTS

According to the results of the study, all three doses of CBZ caused loss of ossification areas, and it was observed that this bone loss also increased statistically significantly depending on the dose increase (p < .05). Calcium concentration decreased in the CBZ groups. When the electron microscope images were examined, it was determined that the cartilage matrix of the CBZ groups was thinned. In the histological evaluation of the groups, narrowing of the primary bone collar and smaller bone spicules in the ossification region compared to the control group were noted due to the increase in dose in the CBZ groups. In immunohistochemical staining, it was observed that the TRAP and AP expression values of the femurs were the lowest in the CBZ groups. These decreases were also statistically significant when compared with the control group.

SIGNIFICANCE

It was revealed with both microscopic and macroscopic findings that exposure to intrauterine CBZ negatively affected ossification and bone growth.

Long-term BPA exposure leads to bone malformation and abnormal expression of MAPK/Wnt/FoxO signaling pathway genes in zebrafish offspring

Bisphenol A (BPA) is one of the world's most widely used plasticizer, and its hazardous impacts have been well studied. However, few studies focused on the effects of parental long-term BPA exposure on the bone development of offspring. In the present study, the bone development of offspring was studied following long-term exposure of parental zebrafish to environmentally relevant 15 and 225 µg/L BPA. The results showed that BPA increased the mortality and deformity rate of offspring and caused craniofacial deformities characterized by changes in various cartilage angles and lengths. The alizarin red and calcein staining showed that BPA could delay bone mineralization and reduce bone mass accumulation. The results of acridine orange staining indicated that BPA induced apoptosis of the skull. The degree of harm of BPA presented a dose-dependent pattern. The results of the comparative transcriptome showed that there were 380 different expression genes (DEGs) in the 15 µg/L BPA group, and 645 DEGs in the 225 µg/L BPA group. MAPK/Wnt/FoxO signaling pathway-related genes were significantly down-regulated in the BPA-exposed groups. The present study demonstrates that long-term parental BPA exposure would severely affect cartilage development and bone mineralization of fish offspring, and MAPK/Wnt/FoxO signaling pathways may be involved in this process.

Developmental programming of macrophages by early life adversity

Macrophages are central elements of all organs, where they have a multitude of physiological and pathological functions. The first macrophages are produced during fetal development, and most adult organs retain populations of fetal-derived macrophages that self-maintain without major input of hematopoietic stem cell-derived monocytes. Their developmental origins make macrophages highly susceptible to environmental perturbations experienced in early life, in particular the fetal period. It is now well recognized that such adverse developmental conditions contribute to a wide range of diseases later in life. This chapter explores the notion that macrophages are key targets of environmental adversities during development, and mediators of their long-term impact on health and disease. We first briefly summarize our current understanding of macrophage ontogeny and their biology in tissues and consider potential mechanisms by which environmental stressors may mediate fetal programming. We then review evidence for programming of macrophages by adversities ranging from maternal immune activation and diet to environmental pollutants and toxins, which have disease relevance for different organ systems. Throughout this chapter, we contemplate appropriate experimental strategies to study macrophage programming. We conclude by discussing how our current knowledge of macrophage programming could be conceptualized, and finally highlight open questions in the field and approaches to address them.

The protective role of curcumin against toxic effect of nonylphenol on bone development

INTRODUCTION

In the study, it was aimed to investigate the possible protective effects of curcumin, a potent antioxidant, against the toxic effect of nonylphenol on bone development.

METHODS

Thirty pregnant female Wistar albino rats were used. The rats were randomly divided into the following five groups; the control group, corn oil group (150 µl/kg/day), nonylphenol group (50 µl/kg/day), curcumin group (100 mg/kg/day) and curcumin + nonylphenol group (100 mg/kg/day + 50 µl/kg/day). The doses were given by gavage from the 5th day to the 20th day of gestation. The fetuses were removed out on the 20th day of pregnancy by cesarean at the end of the study. After the sacrifice of the animals, double skeletal staining in front extremity (clavicula, scapula, humerus, radius, ulna) and hind extremity (femur, tibia, fibula), additionally histological and immunohistochemical examinations in femur bone were performed.

RESULTS

The nonylphenol group offspring have the lowest weights of fetuses and placenta, head-to-hip lengths, biparietal and occipitofrontal length, and also, bone length percentage and percentage of the ossification area in all measurements of the front extremity and hind extremity Interestingly, the groups treated with curcumin showed close to the control group in terms of double skeletal staining, histological, and immunohistochemical examinations.

CONCLUSIONS

Our findings demonstrated an association between bone development and exposure to nonylphenol. The findings suggest that curcumin treatments may be effective in accelerating bone formation.

Bisphenol A exposure prenatally delays bone development and bone mass accumulation in female rat offspring via the ERβ/HDAC5/TGFβ signaling pathway

Previous studies have suggested that bisphenol A (BPA) has a toxic effect on bone development; however, its pathological mechanism has not been fully elucidated. In the present study, pregnant Wistar rats were intragastrically administered BPA (10 μg/kg per day) during gestational days 14-21. Then, bone tissues were obtained from neonatal rats on postnatal day 1 for histological analysis, and the bone mass of adult rat offspring was analyzed by micro-CT at postnatal week 10. Furthermore, osteoprogenitors from neonatal rats were obtained and treated with various concentrations of BPA in vitro to clarify the associated mechanism. In vivo, we found that prenatal BPA exposure reduced body weight and body length in female neonatal rats but not in male neonatal rats. Meanwhile, BPA exposure during pregnancy delayed bone development and reduced bone mass only in female rat offspring. Moreover, BPA exposure during pregnancy inhibited osteogenic function and downregulated the transforming growth factor β (TGF β) signaling pathway in the bone tissue of female neonatal rats. Our in vitro findings further indicated that various concentrations of BPA suppressed the osteogenic function of osteoprogenitors by downregulating the TGFβ signaling pathway. Meanwhile, BPA downregulated H3K9ac and expression levels of TGFβ via the ERβ/HDAC5 signaling pathway. Collectively, this research revealed that prenatal BPA exposure impairs bone development and bone mass accumulation in female rat offspring, which was attributed to inhibitory osteogenic function via the ERβ/HDAC5/TGFβ signaling pathway.

The effects of in ovo administered bisphenol A on tibial growth plate histology in chicken

OBJECTIVES

The aim of this study was to determine of the effects of in ovo administered BPA on embryonic development of the tibial growth plate using histological methods in chickens.

METHODS

Three hundred and ten fertile eggs of Isa Brown laying parent stock were divided into five groups as untreated control, vehicle-injected control, 50, 100, and 250 μg/egg BPA. At the 13th, 18th, and 21st days of incubation, eggs were randomly opened from each group until 10 live embryos were obtained. Embryos were weighed and crown-rump length was measured. Tibial tissue samples were taken from embryos. Tibia weight, relative tibia weight and tibia length were determined. Tissue samples were fixed in 10% buffered formalin solution. Sections were stained with Safranin O staining methods and zones in the growth plate were measured. Also, proliferating cell nuclear antigen (PCNA) was stained immunohistochemically.

RESULTS

The mortality in the BPA treated groups was higher than untreated control group. The results have revealed that mean relative embryo weights, crown-rump length, mean tibia weight, relative tibia weight, and tibia length of BPA treated groups were significantly lower when compared to the untreated control and vehicle-injected control groups. Also, proliferative zone get significantly narrowed, whereas the transitional and hypertrophic zone thickened and PCNA positive chondrocytes increased in growth plate of BPA treated groups.

CONCLUSION

These results have suggested that developmental exposure to BPA adversely affected development of the tibial growth plate.