The adverse effects of perinatal exposure to nonylphenol on carbohydrate metabolism in male offspring rats

Integrated transcriptome and proteome analysis indicates potential biomarkers of prostate cancer in offspring of pregnant rats exposed to a phthalate mixture during gestation and lactation

As the second leading cause of death for cancer among men worldwide, prostate cancer (PCa) prevention and detection remain a critical challenge. One aspect of PCa research is the identification of common environmental agents that may increase the risk of initiation and progression of PCa. Endocrine disrupting chemicals (EDCs) are strong candidates for risk factors, partially because they alter essential pathways for prostate gland development and oncogenesis. Phthalates correspond to a set of commercially used plasticizers that humans are exposed to ubiquitously. Here, we show that maternal exposure to a phthalate mixture interferes with the expression profile of mRNA and proteins in the ventral prostate of offspring and increases the susceptibility to prostate adenocarcinomas in aged animals. The data highlight Ubxn11, Aldoc, Kif5c, Tubb4a, Tubb3, Tubb2, Rab6b and Rab3b as differentially expressed targets in young and adult offspring descendants (PND22 and PND120). These phthalate-induced targets were enriched for pathways such as: dysregulation in post-translational protein modification (PTPM), cell homeostasis, HSP90 chaperone activity, gap junctions, and kinases. In addition, the Kif5c, Tubb3, Tubb2b and Tubb4a targets were enriched for impairment in cell cycle and GTPase activity. Furthermore, these targets showed strong relationships with 12 transcriptional factors (TF), which regulate the phosphorylation of eight protein kinases. The correlation of TF-kinases is associated with alterations in immune system, RAS/ErbB/VEGF/estrogen/HIF-1 signaling pathways, cellular senescence, cell cycle, autophagy, and apoptosis. Downregulation of KIF5C, TUBB3 and RAB6B targets is associated with poor prognosis in patients diagnosed with adenocarcinoma. Collectively, this integrative investigation establishes the post-transcriptional mechanisms in the prostate that are modulated by maternal exposure to phthalate mixture during gestation and lactation.

Nonylphenol exacerbates ovalbumin-induced allergic rhinitis via the TSLP-TSLPR/IL-7R pathway and JAK1/2-STAT3 signaling in a mouse model

Nonylphenol (NP) can be widely used as a plasticizer, surfactant, antioxidant, textile printing, dyeing additive, and pesticide emulsifier. Animal studies have shown that NP aggravates ovalbumin (OVA)-induced allergic rhinitis (AR); however, the exact mechanism underlying its action has not yet been detailed. This study aimed to explore the aggravation of the AR inflammatory response following NP exposure and its possible mechanism. The AR mouse model was constructed using OVA. Under NP exposure, allergic nasal symptoms were observed, eosinophil infiltration was assessed by Sirius red staining, and the levels of IL-4, IL-5, and IL-13 in nasal mucosa samples were detected using cytometric bead array. The mRNA levels of OX40/OX40L and GATA3 in nasal mucosa were detected by qPCR, and the expression levels of the TSLP and JAK1/2-STAT3 signaling pathway components were also identified. Our results suggest that NP exposure exacerbated allergic nasal symptoms and that eosinophils accumulated in nasal mucosa after OVA challenge. The levels of the typical T helper 2 cytokines, as well as the mRNA levels of OX40/OX40L and GATA3, were elevated in the nasal mucosa of OVA-challenged mice exposed to NP. In addition, NP exposure elevated the TSLP, TSLPR, IL-7R, p-JAK1, p-JAK2, and p-STAT3 levels in the nasal mucosa after OVA stimulation. Overall, the present study suggests NP can exacerbate OVA-induced AR inflammatory responses; furthermore, this aggravating effect of NP may be related to the TSLP-TSLPR/IL-7R and JAK1/2-STAT3 signaling pathways.

Emerging concepts and opportunities for endocrine disruptor screening of the non-EATS modalities

Endocrine disrupting chemicals (EDCs) are ubiquitous in the environment and involve diverse chemical-receptor interactions that can perturb hormone signaling. The Organization for Economic Co-operation and Development has validated several EDC-receptor bioassays to detect endocrine active chemicals and has established guidelines for regulatory testing of EDCs. Focus on testing over the past decade has been initially directed to EATS modalities (estrogen, androgen, thyroid, and steroidogenesis) and validated tests for chemicals that exert effects through non-EATS modalities are less established. Due to recognition that EDCs are vast in their mechanisms of action, novel bioassays are needed to capture the full scope of activity. Here, we highlight the need for validated assays that detect non-EATS modalities and discuss major international efforts underway to develop such tools for regulatory purposes, focusing on non-EATS modalities of high concern (i.e., retinoic acid, aryl hydrocarbon receptor, peroxisome proliferator-activated receptor, and glucocorticoid signaling). Two case studies are presented with strong evidence amongst animals and human studies for non-EATS disruption and associations with wildlife and human disease. This includes metabolic syndrome and insulin signaling (case study 1) and chemicals that impact the cardiovascular system (case study 2). This is relevant as obesity and cardiovascular disease represent two of the most significant health-related crises of our time. Lastly, emerging topics related to EDCs are discussed, including recognition of crosstalk between the EATS and non-EATS axis, complex mixtures containing a variety of EDCs, adverse outcome pathways for chemicals acting through non-EATS mechanisms, and novel models for testing chemicals. Recommendations and considerations for evaluating non-EATS modalities are proposed. Moving forward, improved understanding of the non-EATS modalities will lead to integrated testing strategies that can be used in regulatory bodies to protect environmental, animal, and human health from harmful environmental chemicals.

Associations of urinary phenolic environmental estrogens exposure with blood glucose levels and gestational diabetes mellitus in Chinese pregnant women

BACKGROUND

Endocrine-disrupting chemicals (EDCs) are considered to be related to diabetes, but studies of the association between phenolic EDCs and gestational diabetes mellitus (GDM) are limited.

OBJECTIVES

To assess associations of maternal urinary bisphenol A (BPA), nonylphenol (NP), and 2-tert-octylphenol (2-t-OP) with GDM occurrence.

METHODS

A cross-sectional study was performed among 390 Chinese women at 24-28 weeks of gestation. GDM was diagnosed with a 2-h 75-g oral glucose tolerance test (OGTT). BPA, NP, and 2-t-OP concentrations were determined in urine samples. Linear and logistic regression tests evaluated associations of BPA, NP, and 2-t-OP with blood glucose levels and GDM prevalence.

RESULTS

The 2-t-OP concentrations in GDM patients were significantly higher than in non-GDM women with median values of 2.23 μg/g Cr and 1.79 μg/g Cr, respectively. No significant difference was observed in BPA and NP. Urinary 2-t-OP was positively associated with blood glucose levels after adjustment for several confounding factors and urinary BPA and NP. Higher 2-t-OP levels were associated with higher odds of GDM (OR: 5.78; 95% CI: 2.04, 16.37), whereas higher NP levels were associated with lower odds (OR: 0.22; 95% CI: 0.05, 0.85) in the adjusted models. In addition, compared to the first quartile of 2-t-OP, the adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for GDM in the second, third, and fourth quartiles were 2.81 (1.23, 6.42), 3.01 (1.30, 6.93), and 5.49 (2.24, 13.46), respectively.

CONCLUSION

Our study indicates that, for the first time to our knowledge, exposure to 2-t-OP is associated with a higher risk of GDM. However, higher NP exposure is associated with lower GDM risk. Further studies are necessary to affirm the associations of 2-t-OP and NP with GDM, and to elucidate the causality of these findings.

Toxic effects of perinatal maternal exposure to nonylphenol on lung inflammation in male offspring rats

The incidence of asthma and its related allergic diseases has increased dramatically over the last decade. Asthma is a complex disease caused by genetic and environmental factors. Nonylphenol (NP), a typical endocrine disrupting chemical (EDC), is a major current focus in asthma research. Pregnant Sprague-Dawley rats (n = 8-10 per group) were given a consecutive daily dose of NP (25, 50, or 100 mg/kg/day) or an equivalent volume of vehicle by gavage from gestational day 7 until postnatal day (PND) 21. Exposure to 100 mg/kg NP increased the body mass of the offspring on PND 43. Perinatal exposure to NP in maternal rats led to a dose-dependent increase of NP level in the lung tissue of the offspring. The numbers of lymphocytes and neutrophils in bronchoalveolar lavage fluid were significantly higher in the 100 mg/kg NP group than those in the control. Histopathological examination of the lung showed that exposure to high dose NP resulted in a slightly thickened bronchiolar smooth muscles with inflammatory cell infiltration. In the cytoplasm of type II epithelial cells, osmiophilic lamellar bodies were observed, with emptied lamellar bodies. NP significantly increased the expressions of high mobility group box 1 protein (HMGB1) mRNA and nuclear factor κB (NF-κB) mRNA in the lung tissue of the offspring in a dose dependent manner. Similarly, the expressions of HMGB1, NF-κBp65 and estrogen receptor-β (ER-β) proteins increased with an increase of NP dose. NP content was positively correlated with the expressions of HMGB1 and NF-κB mRNA as well as HMGB1, NF-κBp65, and ER-β proteins in the lung tissue of offspring. Perinatal exposure to NP from the maternal rats might induce airway inflammation in the offspring, which may be due to NP-induced infiltration of inflammatory cells into the airway, and pathological alterations in airway structure as well as abnormal expression patterns of inflammation-related genes, proteins (including HMGB1 and NF-κB) and estrogen receptor β.

Defining Parallels between the Salivary Glands and Pancreas to Better Understand Pancreatic Carcinogenesis

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant tumor with a dismal prognosis, largely due to its late presentation. Methods for early detection, the development of reliable screening tools, and the identification of sensitive and specific biomarkers have remained essential research priorities to improve early patient management and outcomes. The pancreas and salivary glands share histological and functional similarities, and the salivary glands have demonstrated a role in oral and systemic health. This review focuses on the similarities and differences between the pancreas and salivary glands and how these can inform our understanding of PDAC genesis and early diagnosis. In particular, chemical exposure, which alters salivary gland gene transcription and morphogenesis, may not only directly impact salivary gland regulation but alter pancreatic function via the systemic secretion of growth hormones. Diabetes and obesity are associated with an increased risk of pancreatic cancer, and a link between chemical exposure and the development of diabetes, obesity, and consequently PDAC genesis is proposed. Possible mechanisms include altering salivary or pancreatic morphology and organ function, disrupting endocrine signaling, or altering pro-inflammatory homeostasis. Finally, saliva contains putative specific biomarkers that show promise as non-invasive diagnostic tools for PDAC.

Review of the Effects of Perinatal Exposure to Endocrine-Disrupting Chemicals in Animals and Humans

Maternal exposure to endocrine-disrupting chemicals (EDCs) is associated with long-term hormone-dependent effects that are sometimes not revealed until maturity, middle age, or adulthood. The aim of this study was to conduct descriptive reviews on animal experimental and human epidemiological evidence of the adverse health effects of in utero and lactational exposure to selected EDCs on the first generation and subsequent generation of the exposed offspring. PubMed, Web of Science, and Toxline databases were searched for relevant human and experimental animal studies on 29 October 29 2018. Search results were screened for relevance, and studies that met the inclusion criteria were evaluated and qualitative data extracted for analysis. The search yielded 73 relevant human and 113 animal studies. Results from studies show that in utero and lactational exposure to EDCs is associated with impairment of reproductive, immunologic, metabolic, neurobehavioral, and growth physiology of the exposed offspring up to the fourth generation without additional exposure. Little convergence is seen between animal experiments and human studies in terms of the reported adverse health effects which might be associated with methodologic challenges across the studies. Based on the available animal and human evidence, in utero and lactational exposure to EDCs is detrimental to the offspring. However, more human studies are necessary to clarify the toxicological and pathophysiological mechanisms underlying these effects.

Influence of nonylphenol exposure on basic growth, development, and thyroid tissue structure in F1 male rats

Objective

Environmental endocrine disruptors (EEDs) with a weak ability to mimic estrogen have been associated with thyroid dysfunction. However, little is known about the effect of nonylphenol (NP), a well-known EED, on thyroid structure. The present study evaluates whether gestational and lactational exposure to NP impacts growth and thyroid structure in F1 male rats.

Methods

A total of 60 rats were gavaged with NP (25, 50, and 100 mg/kg), estradiol (E₂, 30 μg/kg/day), and corn oil alone (vehicle control) from gestational day 6 to postnatal day (PND) 21. Serum thyroid hormones free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone levels were detected by automated chemiluminescence immunoassay analyzer. The NP level in the thyroid was measured using high-performance liquid chromatography. The ultrastructure of follicular epithelial cells was examined using transmission electron microscopy. Histopathology was conducted using hematoxylin and eosin staining.

Results

On PND 0, exposure to 50 and 100 mg/kg/day NP led to a significant decrease in the average litter size, litter weight and number of live pups per litter compared to the control group (P < 0.05). Dams exposed to NP during perinatal period demonstrated decreased serum levels of FT3 and FT4 in F1 male rats, when compared to the control group (P < 0.05). The NP level in the control group was 3.39 ± 0.08 ng/mg, while NP levels in the low, middle, and high dose groups ranged from 5.20 to 11.00 ng/mg. Exposure caused a dose-related increase in NP level in the thyroid of male pups (P < 0.01). The thicknesses of the thyroid follicular epithelium were 2.06 ± 0.37 μm in the control group and 3.97 ± 1.61 μm in the high-dose group. The thickness of the thyroid follicular epithelium increased with an increase in treatment dose in a dose-dependent manner (P < 0.05). The sizes of the thyroid follicles were 1,405.53 ± 866.62 μm² in the control group and 317.49 ± 231.15 μm² in the high-dose group. With increasing NP dosages, animals showed a decreased size of the thyroid follicle (P < 0.01). Thyroid follicular cells of NP-treated rats showed mildly swollen mitochondria and dilated rough endoplasmic reticulum in the cytoplasm.

Conclusion

Nonylphenol can cross the placental barrier and accumulate in the thyroid of F1 male rats. Gestational and lactational exposure to NP in dams impacted both development and growth of pups and damaged the ultrastructure of their thyroid tissue, which may further negatively influence normal thyroid function.

4-Nonylphenol effects on rat testis and sertoli cells determined by spectrochemical techniques coupled with chemometric analysis

Herein, vibrational spectroscopy has been applied for qualitative identification of biomolecular alterations that occur in cells and tissues following chemical treatment. Towards this end, we combined attenuated total reflection Fourier-transform infrared (ATR-FTIR) and Raman spectroscopy to assess testicular toxicology after 4-nonylphenol (NP) exposure, an estrogenic endocrine disruptor affecting testicular function in rats and other species. Rats aged 21, 35 or 50 days received NP at intra-peritoneal doses of 0, 25, 50 or 100 mg/kg for 20 consecutive days. Primary Sertoli cells (SCs) were treated with NP at various concentrations (0, 2.5, 5, 10 or 20 μM) for 12 h. Post-exposure, testicular cells, interstitial tissue and SCs were interrogated respectively using spectrochemical techniques coupled with multivariate analysis. Distinct biomolecular segregation between the NP-exposed samples vs. control were observed based on infrared (IR) spectral regions of 3200-2800 cm^-1 and 1800-900 cm^-1, and the Raman spectral region of 1800-900 cm^-1. For in vivo experiments, the main wavenumbers responsible for segregation varied significantly among the three age classes. The main IR and Raman band differences between NP-exposed and control groups were observed for Amide (proteins), lipids and DNA/RNA. An interesting finding was that the peptide aggregation level, Amide Ӏ-to-Amide II ratio, and phosphate-to-carbohydrate ratio were considerably reduced in ex vivo NP-exposed testicular cells or SCs in vitro. This study demonstrates that ATR-FTIR and Raman spectroscopy techniques can be applied towards analysing NP-induced testicular biomolecular alterations.

The adverse effects of chronic low-dose exposure to nonylphenol on type 2 diabetes mellitus in high sucrose-high fat diet-treated rats

OBJECTIVES

Although it has been shown that exposure to environmental endocrine disruptors (EDCs) has been implicated as a potential risk factor for metabolic disease, information on adverse effect of chronic low-dose exposure to nonylphenol (NP), on the development and progress of type 2 diabetes mellitus (T2DM) is scarce. NP, as an EDC, is a ubiquitous degradation product of nonylphenol polyethoxylate (NPE) that is primarily used in cleaning and industrial processes.

METHOD

Eighty Sprague-Dawley rats were assigned into 8 groups (n = 10 per group): rats fed a normal-diet (ND) as the control (C-ND); rats fed a normal diet and were gavaged with NP at a dose level of 0.02 μg/kg/day (NP-L-ND), 0.2 μg/kg/day (NP-M-ND) or 2 μg/kg/day (NP-H-ND), respectively; rats fed a high-sucrose/high-fat diet (HSHFD) as the HSHFD control (C-HSHFD); rats fed a HSHFD and were gavaged with NP at a dose level of 0.02 μg/kg/day (NP-L-HSHFD), 0.2 μg/kg/day (NP-M-HSHFD) or 2 μg/kg/day (NP-H-HSHFD), respectively.

RESULT

On day 180, the rats in the groups treated with NP-M-HSHFD and NP-H-HSHFD showed significant increases in body weight (p < 0.05) in comparison with the C-ND group. Fast blood glucose (FBG) level in the NP-M-HSHFD and NP-H-HSHFD groups was higher than that in the C-ND group (F = 96.17, p < 0.001). The fast serum insulin (FINS) level of rats was lower in both the NP-M-HSHFD and NP-H-HSHFD groups compared with the C-ND group (F = 145.56, p < 0.001). Serum leptin (LEP) level in both the NP-M-HSHFD and NP-H-HSHFD groups was lower when compared with the C-ND group (F = 34.62, p < 0.001). The effect of NP at the dose level of 0.2 μg/kg/day on FBG, serum FINS and LEP levels in rats was greatest among the treatment groups (p < 0.05). Oral glucose tolerance test showed increased area under the curve (AUC) in treatment groups at week 12 (p < 0.05). A decrease of pancreatic islet numbers and size was exhibited in the pancreatic tissue of NP-M-HSHFD and NP-H-HSHFD treated rats compared with C-ND treated rats. Co-exposure to NP and HSHFD causes inflammatory changes histologically.

CONCLUSION

Chronic low-dose exposure to NP might induce impaired glucose tolerance, which further lead to insulin resistance, and pancreatic β cell insulin secretion deficiency, ultimately increase the risk of T2DM. Moreover, additive toxic effects of NP and HSHFD on pancreatic beta-cell function and glucose metabolism have been identified in rats as well.