Endocrine-disrupting Activity Research Articles

Endocrine Disruptive Activity and Occurrence of Pharmaceuticals and Viral Content in Water Sources in Melusii Informal Settlement, Pretoria

Endocrine Disruptive Activity and Occurrence of Pharmaceuticals and Viral Content in Water Sources in Melusii Informal Settlement, Pretoria

Effects of combined exposure to two bisphenol plasticizers (BPA and BPB) on Xenopus laevis development

Due to its endocrine disruptive activity, the plastic additive Bisphenol A (BPA) is classified as substance of very high concern (EU ECHA 2017). A correlation between environmental exposure to BPA and congenital defects has been described in humans and in experimental species including the amphibian Xenopus laevis, where severe branchial defects were associated to lethality. The exposure of X. laevis embryos to the BPA analogue bisphenol B (BPB) was recently linked to similar teratogenic effects, with BPB having relative potency about 3 times higher than BPA. The combined BPA-BPB exposure is realistic as both BPA and BPB are detected in human samples and environment. Limited experimental data are available on the combined developmental toxicity of BPA and BPB. The aim of the present work is to evaluate the effects of BPA and BPB mixture in the X. laevis development model, using R-FETAX procedure. The exposure was limited to the first day of development (corresponding to the phylotypic developmental period, common to all vertebrates). Samples were monitored for lethal effects during the full six-day test period and the external morphology was evaluated at the end of the test. Mixture effects were described by modelling, using the PROAST software package. Overall data modelling showed that dose-addiction could not be rejected, suggesting a health concern for co-exposure.

A combined in vitro-in silico method for assessing the androgenic activities of bisphenol A and its analogues

Interactions between endocrine-disruptor chemicals (EDCs) and androgen receptor (AR) have adverse effects on the endocrine system, leading to human reproductive dysfunction. Bisphenol A (BPA) is an EDC that can damage both the environment and human health. Although numerous BPA analogues have been produced as substitutes for BPA, few studies have evaluated their endocrine-disrupting abilities. We assessed the (anti)-androgenic activities of BPA and its analogues using a yeast-based reporter assay. The BPA analogues tested were bisphenol S (BPS), 4-phenylphenol (4PP), 4,4′-(9-fluorenyliden)-diphenol (BPFL), tetramethyl bisphenol F (TMBPF), and tetramethyl bisphenol A (TMBPA). We also conducted molecular docking and dynamics simulations to assess the interactions of BPA and its analogues with the ligand-binding domain of human AR (AR-LBD). Neither BPA nor its analogues had androgenic activity; however, all except BPFL exerted robust anti-androgenic effects. Consistent with the in vitro results, anti-androgenic analogues of BPA formed hydrogen bonding patterns with key residues that differed from the patterns of endogenous hormones, indicating that the analogues display in inappropriate orientations when interacting with the binding pocket of AR-LBD. Our findings indicate that BPA and its analogues disrupt androgen signaling by interacting with the AR-LBD. Overall, BPA and its analogues display endocrine-disrupting activity, which is mediated by AR.

Flavouring Group Evaluation 413 (FGE.413): Naringenin.

The EFSA Panel on Food Additives and Flavourings (FAF) was requested to evaluate the safety of naringenin [FL-no: 16.132] as a new flavouring substance, in accordance with Regulation (EC) No 1331/2008. No other substances with sufficient structural similarity have been identified in existing FGEs that could be used to support a read-across approach. The information provided on the manufacturing process, the composition and the stability of [FL-no: 16.132] was considered sufficient. From studies carried out with naringenin, the Panel concluded that there is no concern with respect to genotoxicity. The use of naringenin as a flavouring substance at added portions exposure technique (APET) exposure levels is unlikely to pose a risk for drug interaction. For the toxicological evaluation of naringenin, the Panel requested an extended one-generation toxicity study on naringenin, in line with the requirements of the Procedure and to investigate the consequence of a possible endocrine-disrupting activity. The Panel considered that changes in thymus weight, litter size, post-implantation loss and a consistent reduced pup weight in the high-dose F2 generation could not be dismissed and selected therefore, the mid-dose of 1320 mg/kg body weight (bw) per day for the parental males as the no observed adverse effect level (NOAEL) of the study. The exposure estimates for [FL-no: 16.132] (31,500 and 50,000 μg/person per day for children and adults, respectively) were above the threshold of toxicological of concern (TTC) for its structural class (III). Using the NOAEL of 1320 mg/kg bw per day at step A4 of the procedure, margins of exposure (MoE) of 1590 and 630 could be calculated for adults and children, respectively. Based on the calculated MoEs, the Panel concluded that the use of naringenin as a flavouring substance does not raise a safety concern.

Multiplex analysis platform for evaluation of endocrine disruption of emerging contaminants against human steroid hormone receptors using autobioluminescent yeast bioassay: Application to bisphenols

Emerging synthetic or derivative chemicals have drawn global concern due to their potential endocrine-disrupting effects, either as agonists or antagonists or through indirect effects on enzymes of signal transduction pathways. Currently, in vitro screening models are limited to poor tolerance, robustness, high cost and need for sphisticated equipment or complex procedures that require high levels of expertise. Herein, a multiplex analysis platform based on autobioluminescent yeast strains, including BLYhERαS, BLYhERβS, BLYhPRS, BLYhARS, BLYhMRS, and BLYhGRS, was developed for use in easy, rapid, robust, and sensitive screening for potential modulation of endocrine systems. Methods were applied to assess endocrine-disrupting effects of Bisphenol A (BPA) and its alternatives. Disrupting activities of bisphenols (BPs) varied greatly, and some BPA substitutes exerted more potent activities than those of BPA. Most BPs were primarily agonists of ERα and ERβ, while others were antagonists to AR, PR, GR, and MR. BPP and BPM exhibited non-monotonic dose-response relationships toward ERα and ERβ, and BHPF and BPG displayed converse disrupting activities to ERα and ERβ. Overall, the bioassay system provides an efficient tool for comprehensive evaluation of endocrine-disrupting activities of emerging contaminants.

Dimethylcyclosiloxanes in Mobile Smart Terminal Devices: Concentrations, Distributions, Profiles, and Environmental Emissions.

Dimethylcyclosiloxanes (DMCs) are utilized as vital monomers in the synthesis of organosilicon compounds, integral to the manufacture of mobile smart terminal devices. Toxicological studies have revealed potential endocrine-disrupting activity, reproductive toxicity, neurotoxicity, and other toxicities of the DMCs. This study investigated the concentrations and composition profiles of seven DMCs, including hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), and tetradecamethylcycloheptasiloxane (D7), hexadecamethylcyclooctasiloxane (D8), and octadecamethylcyclononasiloxane (D9) in three types of mobile smart terminal device components (silicone rubber, adhesive, and plastics). Environmental emissions of DMCs from silicone rubber materials were also estimated to improve the recognition of their potential fate within the environment. D5-D9 were widely present in silicone rubber and adhesives with detection rates ranging from 91-95.5% and 50-100%, respectively, while D3 and D4 were more frequently detected in plastics, both showing a detection rate of 61.1%. Silicone rubber had the highest total DMCs (∑7DMCs) and a concentration of 802.2 mg/kg, which were dominated by D7, D8, and D9. DMCs detected in adhesives were dominated by D4, D5, and D6. The estimated emission of ∑DMCs released into the environment in China from silicone rubber used in mobile smart terminal devices exceeds 5000 tons per year. Further studies are needed on the presence of DMCs in various commodities and environmental media to assess their ecological and human health impacts, as well as the toxicological effects of D7-D9 for the appropriate regulation of these chemicals.

An Integrated Approach of Bioassays and Non-Target Screening for the Assessment of Endocrine-Disrupting Activities in Tap Water and Identification of Novel Endocrine-Disrupting Chemicals.

The safety of drinking water is a significant environmental issue of great concern for human health since numerous contaminants are often detected in drinking water and its sources. Boiling is a common household method used to produce relatively high-quality drinking water in some countries and regions. In this study, with the aid of an integrated approach of in vitro bioassays and non-target analysis based on high-resolution mass spectrometry coupled with liquid chromatography, alterations in endocrine-disrupting activities in tap water samples without and with boiling were revealed, as well as the potential endocrine-disrupting chemicals (EDCs) contributing to these alterations were identified. The organic extracts of tap water had no significant (ant)agonistic activities against an estrogen receptor (ER), progesterone receptor (PR), glucocorticoid receptor (GR), and mineralocorticoid receptor (MR) at enrichment concentrations of ≤10 times, posing no immediate or acute health risk to humans. However, the presence of agonistic activities against PR and MR and antagonistic activities against ER, PR, GR, and MR in OEs of tap water at relatively higher enrichment concentrations still raise potential health concerns. Boiling effectively reduced antagonistic activities against these steroid hormone receptors (SHRs) but increased estrogenic and glucocorticoid activities in drinking water. Four novel potential EDCs, including one UV filter (phenylbenzimidazole sulfonic acid, PBSA) and three natural metabolites of organisms (beta-hydroxymyristic acid, 12-hydroxyoctadecanoic acid, and isorosmanol) were identified in drinking water samples, each of which showed (ant)agonistic activities against different SHRs. Given the widespread use of UV filters in sunscreens to prevent skin cancer, the health risks posed by PBSA as an identified novel EDC are of concern. Although boiling has been thought to reduce the health risk of drinking water contamination, our findings suggest that boiling may have a more complex effect on the endocrine-disrupting activities of drinking water and, therefore, a more comprehensive assessment is needed.

Predicting the Activity of Unidentified Chemicals in Complementary Bioassays from the HRMS Data to Pinpoint Potential Endocrine Disruptors.

The majority of chemicals detected via nontarget liquid chromatography high-resolution mass spectrometry (HRMS) in environmental samples remain unidentified, challenging the capability of existing machine learning models to pinpoint potential endocrine disruptors (EDs). Here, we predict the activity of unidentified chemicals across 12 bioassays related to EDs within the Tox21 10K dataset. Single- and multi-output models, utilizing various machine learning algorithms and molecular fingerprint features as an input, were trained for this purpose. To evaluate the models under near real-world conditions, Monte Carlo sampling was implemented for the first time. This technique enables the use of probabilistic fingerprint features derived from the experimental HRMS data with SIRIUS+CSI:FingerID as an input for models trained on true binary fingerprint features. Depending on the bioassay, the lowest false-positive rate at 90% recall ranged from 0.251 (sr.mmp, mitochondrial membrane potential) to 0.824 (nr.ar, androgen receptor), which is consistent with the trends observed in the models' performances submitted for the Tox21 Data Challenge. These findings underscore the informativeness of fingerprint features that can be compiled from HRMS in predicting the endocrine-disrupting activity. Moreover, an in-depth SHapley Additive exPlanations analysis unveiled the models' ability to pinpoint structural patterns linked to the modes of action of active chemicals. Despite the superior performance of the single-output models compared to that of the multi-output models, the latter's potential cannot be disregarded for similar tasks in the field of in silico toxicology. This study presents a significant advancement in identifying potentially toxic chemicals within complex mixtures without unambiguous identification and effectively reducing the workload for postprocessing by up to 75% in nontarget HRMS.

A review: Exposure to bisphenol a analogues in non-human primates as a potential cause of endometriosis

Introduction: Bisphenol A is a synthetic compound widely used in the production of polycarbonate plastics and epoxy resins worldwide. As an environmental toxin, it has been reported in plastic equipment and utensils, water bottles and bottle tops, water supply pipes and epoxy resins that coat most of the metal food cans. It is a known endocrine-disrupting chemical and has been progressively replaced by its derivatives including bisphenol S, bisphenol F, bisphenol E, bisphenol AF, bisphenol B and tetramethyl bisphenol F. Bisphenol A and its analogues can bind to estrogen receptors and trigger multiple cellular responses at the organism level. Methods: A comprehensive literature review was done utilising electronic databases of PubMed, Google Scholar, Hinari, Connected papers and Science Direct from 1991 onwards. The articles were only included if they reported original relevant research and were limited to articles written in English. Results: Animal models, including non-human primates, have been used to study their effects on the endocrine system. Its endocrine disruption activity is reported to be the most studied effect in reproductive biology indicating that it may potentially cause endometriosis in females. Though non-human primates are closely related to humans, limited data exists on their associations between Bisphenol A exposure and its analogues and the pathophysiology of endometriosis. Conclusion: Given the current multifaceted knowledge/theory on endometriosis etiology, there is a strong necessity to conduct further biomedical research that utilises non-human primates to study the link between endocrine-disrupting chemicals and its effects on endometriosis.

Advancing Endocrine Disruptors via In Vitro Evaluation: Recognizing the Significance of the Organization for Economic Co-Operation and Development and United States Environmental Protection Agency Guidelines, Embracing New Assessment Methods, and the Urgent Need for a Comprehensive Battery of Tests.

Efforts are being made globally to improve the evaluation and understanding of endocrine-disrupting chemicals. Recognition of their impact on human health and the environment has stimulated attention and research in this field. Various stakeholders, including scientists, regulatory agencies, policymakers, and industry representatives, are collaborating to develop robust methodologies and guidelines for assessing these disruptors. A key aspect of these efforts is the development of standardized testing protocols and guidelines that aim to provide consistent and reliable methods for identifying and characterizing endocrine disruptors. When evaluating the potential endocrine-disrupting activity of chemicals, no single test is capable of detecting all relevant endocrine-disrupting agents. The test battery approach is designed to reduce the risk of false negative results for compounds with toxic potential. A weight-of-evidence approach is therefore necessary for endocrine disruptor evaluation. This approach considers various types of data from multiple sources, assessing the overall strength, consistency, and reliability of the evidence. OECD guidelines are highly regarded for their scientific rigor, transparency, and consensus-based development process. It is crucial to explore and develop new methodologies that can effectively evaluate the risks associated with potential endocrine disruptors. Integrating these methods into a comprehensive weight-of-evidence framework will enhance risk assessments and facilitate informed decisions regarding the regulation and management of these substances, ensuring the protection of human health and the environment from their adverse effects.

Altered Igf2 imprint leads to accelerated adipogenesis and early onset of metabolic syndrome in male mice following gestational arsenic exposure

Developmental exposure to environmental pollutants has been shown to promote adverse health outcomes in offspring. Exposure to heavy metals such as arsenic which also has endocrine-disrupting activity is being increasingly linked with cancers, diabetes, and lately with Metabolic Syndrome (MetS). In this work, we have assessed the effects of preconceptional plus gestational arsenic exposure on the developmental programming of MetS in offspring. In our study, only gestational arsenic exposure led to reduced birth weight, followed by catch-up growth, adiposity, elevated serum triglycerides levels, and hyperglycemia in male offspring. Significant adipocyte dysfunction was observed in offspring with increased hypertrophy, insulin resistance, and chronic inflammation in epididymal white adipose tissue. Adipose tissue regulates the metabolic health of individuals and its dysfunction resulted in elevated serum levels of metabolism-regulating adipokines (Leptin, Resistin) and pro-inflammatory cytokines (PAI-1, TNFα). The progenitor adipose-derived stem cells (AdSCs) from exposed progeny had increased proliferation and adipogenic potential with excess lipid accumulation. We also found increased activation of Akt, ERK1/2 & p38 MAPK molecules in arsenic-exposed AdSCs along with increased levels of phospho-Insulin-like growth factor-1 receptor (p-IGF1R) and its upstream activator Insulin-like growth factor-2 (IGF2). Overexpression of Igf2 was found to be due to arsenic-mediated DNA hypermethylation at the imprinting control region (ICR) located -2kb to −4.4 kb upstream of the H19 gene which caused a reduction in the conserved zinc finger protein (CTCF) occupancy. This further led to persistent activation of the MAPK signaling cascade and enhanced adipogenesis leading to the early onset of MetS in the offspring.

Physiological responses on the reproductive, metabolism and stress endpoints of Astyanax lacustris females (Teleostei: Characiformes) after diclofenac and ibuprofen exposure

Diclofenac (DCF) and ibuprofen (IBU) are pharmaceutical compounds frequently detected in aquatic compartments worldwide. Several hazard effects including developmental abnormalities and redox balance impairment have been elucidated in aquatic species, but multiple endocrine evaluations are scarce. Therefore, the present study aimed to assess the disruptive physiological effects and toxicity of DCF and IBU isolated and combined, using females of the native freshwater teleost Astyanax lacustris. In regards to NSAIDs bioavailability, the results showed absence of degradation of IBU and DCF after 7 days of exposure. IBU LC50 for A. lacustris was 137 mgL−1 and females exposed to IBU isolated increased thyroxine (T4) concentration at 24 h and decreased after 96 h; DCF exposure decreased triiodothyronine (T3) concentration at 96 h. Circulating levels of 17β-estradiol (E2), cortisol (F) and testosterone (T) were not affected by any treatment. HPG and HPI axis genes fshβ, pomc and vtg were upregulated after 24 h of IBU exposure, and dio2 was downregulated in DCF fish exposed group after 96 h compared to the mixture. Protein concentration was reduced in muscle and increased in the liver by DCF and mixtures exposures at 24 h; while liver lipids were increased in the mixture groups after 96 h. The study point out the capacity of NSAIDs to affect endocrine endpoints in A. lacustris females and induce changes in energetic substrate content after acute exposure to isolated and mixed NSAIDs treatments. Lastly, the present investigation brings new insights into the toxicity and endocrine disruptive activity of NSAIDs in Latin America teleost species and the aquatic environment.

Effect of diisobutyl adipate on the expression of biomarker genes that respond to endocrine disruption and on gonadal sexual differentiation in Japanese medaka (Oryzias latipes)

Phthalate and non-phthalate plasticizers are used in polymer materials, such as plastic and rubber. It has recently been found that diisobutyl adipate (DIBA), which is considered an environmentally safe non-phthalate plasticizer, potentially acts as a thyroid disruptor in fish. Here, we investigated the sexual hormone effects of DIBA based on the expression levels of genes that respond to endocrine disruption and sexual hormone activity in the livers and gonads, and on gonadal sexual differentiation in Japanese medaka. Compared with the control group, the mRNA expression of chgH, vtg1, vtg2, and esr1 was significantly suppressed in the livers of DIBA exposed XX individuals. Furthermore, the mRNA expression of gsdf was significantly upregulated and downregulated in the gonads of XX and XY individuals, respectively. The mRNA expressions of esr1 and esr2b were significantly suppressed by DIBA exposure in the gonads of both XX and XY individuals. These observations suggest that DIBA has potential androgenic activity in Japanese medaka. However, normal testes and ovaries were observed in respective XY and XX medaka after DIBA exposure; therefore, these results suggest that DIBA may have weak androgenic activity.

Investigating the endocrine disruption effects of four disinfection byproducts on zebrafish estrogen receptor-α

Reports have shown an increase in the use of disinfectants in wastewater treatment plants, prompted by the detection of residual viruses in sewage. However, the release of disinfection byproducts (DBPs) in final effluents has raised concerns about their potential adverse effects, such as endocrine disruption, on aquatic environments. Despite these concerns, few studies have examined the endocrine-disrupting effects of DBPs on fish, which may be vulnerable to DBPs. The aim of this case study was to investigate the endocrine-disrupting properties of four commonly formed DBPs: chloroiodomethane (CIM), dibromochloromethane (DBCM), bromodichloromethane (BDCM), and trichloroacetic acid (TCA) on the estrogen receptor-α in zebrafish (zERα). The results indicated that all four DBPs have high anti-estrogenic activity against zERα; with CIM, BDCM, DBCM, and TCA yielding 80.8%, 78.4%, 49.0%, and 64.1% anti-estrogenic effects on zERα, respectively. Moreover, all DBPs demonstrated negligible estrogenic effects on zERα. Our study sheds new light on the adverse effects of DBPs, particularly the endocrine-disrupting activity of CIM, which, as part of the dihalomethanes group, has received limited research attention in the past. This study shows the molecular interactions in terms of the endocrine disruption of DBP on zERα, warranting further studies to understand the overall impact of fish in affected aquatic ecosystems.

Gene expression and trace elements in Greenlandic ringed seals (Pusa hispida)

Marine top predators such as ringed seals biomagnify environmental contaminants; and with the increasing human activities in the Arctic, ringed seals are exposed to biologically significant concentrations of trace elements resulting in reproductive impairment, immunosuppression, and neurological damages. Little is known about the molecular effects of heavy metals on these vulnerable apex predators suffering from a rapidly changing Arctic with significant loss of sea-ice. In the present study, concentrations of cadmium (Cd), mercury (Hg) and selenium (Se) were measured in liver of sixteen Greenlandic ringed seals (nine adults and seven subadults) together with molecular biomarkers involved in bio-transformation, oxidative stress, endocrine disruption and immune activity in blood and blubber. The concentrations of trace elements increased in the following order: Hg > Se > Cd with levels of mercury and selenium being highest in adults. Aryl hydrocarbon receptor nuclear translocator (ARNT), peroxisome proliferator activated receptor alpha (PPARα, estrogen receptor alpha (ESR1), thyroid hormone receptor alpha (TRα) and interleukin – 2 (IL-2) mRNA transcript levels were highest in blubber, while heat shock protein 70 (HSP70) and interleukin – 10 (IL-10) were significantly higher in blood. There were no significant correlations between the concentrations of trace elements and mRNA transcript levels suggesting that stressors other than the trace elements investigated are responsible for the changes in gene expression levels. Since Hg seems to increase in Greenlandic ringed seals, there is a need to re-enforce health monitoring of this ringed seal population.

Ochratoxin A triggers endoplasmic reticulum stress through PERK/NRF2 signaling and DNA damage during early embryonic developmental competence in pigs

Ochratoxin A (OTA), a mycotoxin found in foods, has a deleterious effect on female reproduction owing to its endocrine-disrupting activity mediated through endoplasmic reticulum (ER) stress and reactive oxygen species (ROS) production. However, the mechanisms of OTA-induced ER stress in pig embryos during in vitro culture (IVC) are not yet fully understood. In the present study, porcine embryos were cultured for two days in an IVC medium supplemented with 0.5, 1.0, and 5.0 μM OTA, which led to an OTA-induced reduction in the developmental rate of blastocysts. The mRNA-seq transcriptome analysis revealed that the reduced blastocyst development ability of OTA-exposed porcine embryos was caused by ER stress, ultimately resulting in the accumulation of ROS and the occurrence of apoptosis. The expression levels of some UPR/PERK signaling-related genes (DDIT3, EIF2AK3, EIF2S1, NFE2L2, ATF4, EIF2A, and KEAP1) were found to differ in OTA-exposed pig embryos. OTA induces DNA damage by triggering an increase in RAD51/γ-H2AX levels and suppressing p-NRF2 activity. This effect is mediated through intracellular ROS and superoxide accumulation in the nuclei of porcine embryos. The cytotoxicity of OTA increased the activation of the PERK signal pathways (p-PERK, PERK, p-eIF2α, eIF2α, ATF4, and CHOP) in porcine embryos, with abnormal distribution of the ER observed around the nucleus. Collectively, our findings indicate that ER stress is a major cause of decline in the development of porcine embryos exposed to OTA. Therefore, OTA exposure induces ER stress and DNA damage via oxidative stress by disrupting PERK/NRF2 signaling activity in the developmental competence of porcine embryos during IVC.

Endocrine disruptors as promoters of biosphere carcinogenic background

The main aim of the study is to analyze modern knowledge on endocrine disruptors, non-genotoxic carcinogens, contributing significantly to the total level of contamination of the biosphere by anthropogenic blastomogens.Material and Methods. For the review preparation, we analyzed articles on molecular mechanisms of the effects of endocrine disruptors, available at biomedical literature databases sciVerse scopus, pubmed, Web of science, Rsci. The review cited 65 recent publications, 21 of them being published over the past three years, 3 papers being the official documents on hazards associated with the use of endocrine disruptors, and 10 papers presenting a background to separate endocrine disruptors into the group of compounds with specific functional activity.Results. The role of endocrine disruptors involves the development of the tumors of reproductive organs. They may reveal the properties of strong agonists or antagonists disrupting the hormonal balance by inhibition of the synthesis of natural hormones, their secretion, transport, metabolism, binding or degradation. In addition, they activate alternative proliferation signaling pathways by activating g-proteincoupled receptors, estrogen-bound eRRγ or/and β-adrenergic receptors. The main mechanism of action of endocrine disruptors is the induction of epigenetic modifications, in particular, methylation/demethylation of cpg dNa islands, histone modifications and changes in expression of non-coding RNa. since the effects of endocrine disruptors are nonlinear, they can be caused by concentrations corresponding to the real content in the biosphere and detected in the umbilical blood and breast milk. In addition, they contribute to the metabolic activation of the procarcinogens, the main component of air pollution, by activation of the cytochrome p450 isoforms.Conclusion. Endocrine disruptors can underlie the development of tumors of hormone-dependent organs both at direct and transplacental exposure.

IN VITRO BISPHENOL A EFFECT ON TFAM AND SIRT1 GENE EXPRESSION IN PORCINE OOCYTE MITOCHONDRIA

"Mitochondria are the main cellular organelle responsible for energy production, having an essential role in maintaining cellular homeostasis. In this study, the gene expression of TFAM (Transcription Factor A Mitochondrial) and SIRT1 (Silent Information Regulator) in sow oocytes cultured in vitro was assessed using the RT-qPCR reaction. The primers were tailored after our own design. The groups were: V1 (matured oocytes, control group), V2 (matured oocytes with hormones), V3 (medium supplemented with Bisphenol A), V4 (medium supplemented with Bisphenol A and hormones). Our findings reveal a reduction in SIRT1 activity following maturation in all experimental groups, while TFAM activity displayed more elevated levels, seemingly independent of the SIRT1 gene expression. The highest values of gene expression for TFAM and SIRT1 were obtained in V2 (supplemented with FSH and LH, - 0.277 and 0.010) and V4 (FSH, LH and bisphenol A - 0.272 and 0.015) without significant differences (p=0.941). Bisphenol A alone generated low values, presumably due to its endocrine disruptor action. We concluded that FSH/LH addition might rescue some of the TFAM expression during bisphenol treatment, but the mechanism might be independent of SIRT1."

Teratogenic and neuro-behavioural toxic effects of bisphenol A (BPA) and B (BPB) on Xenopus laevis development

Bisphenol A (BPA) is a plastic additive with endocrine disruptive activity, classified in 2017 by EU ECHA as substance of very high concern. A correlation between environmental exposure to BPA and congenital defects has been described in humans and in experimental species, including the amphibian Xenopus laevis. Among BPA analogues, bisphenol B (BPB) is used as alternative in different not-EU countries, including US, but seems to share with BPA its endocrine disruptor properties. Aim of the present work is the evaluation of the effects of BPB versus BPA exposure in a X. laevis developmental model. A windowed exposure (R-FETAX method) was applied covering the developmental phylotypic period (teratogenicity window), or the late tailbud stages (neuro-behavioural toxicity window, corresponding to the spontaneous swimming acquisition period). Samples were monitored for lethal effects during the full test period. External morphology evaluation and deglutition functional test were applied in any group. Abnormal tadpoles were also processed for cartilage staining. In groups exposed during neuro-behavioural toxicity window the swimming test was also applied. Lethality and malformations were obtained only in samples exposed during the teratogenicity window; these data were modelled using PROAST software and BPB relative potency resulted about 3 times higher than BPA. The day-by-day evaluation revealed that lethality was correlated to embryonic abnormal development of gills and apoptosis in gill primordia. Teratogenicity was never detected in groups exposed during the neuro-behavioural toxicity window, where some significant neuro-behavioural deficits were detected in tadpoles exposed to the highest tested concentrations of BPA and BPB.

Heavy Metals in Follicular Fluid Affect the Ultrastructure of the Human Mature Cumulus-Oocyte Complex.

It is known that exposure to heavy metal such as lead (Pb) and cadmium (Cd) has several adverse effects, particularly on the human reproductive system. Pb and Cd have been associated with infertility in both men and women. In pregnant women, they have been associated with spontaneous abortion, preterm birth, and impairment of the development of the fetus. Since these heavy metals come from both natural and anthropogenic activities and their harmful effects have been observed even at low levels of exposure, exposure to them remains a public health issue, especially for the reproductive system. Given this, the present study aimed to investigate the potential reproductive effects of Pb and Cd levels in the follicular fluid (FF) of infertile women and non-smokers exposed to heavy metals for professional reasons or as a result of living in rural areas near landfills and waste disposal areas in order to correlate the intrafollicular presence of these metals with possible alterations in the ultrastructure of human cumulus-oocyte complexes (COCs), which are probably responsible for infertility. Blood and FF metals were measured using atomic absorption spectrometry. COCs corresponding to each FF analyzed were subjected to ultrastructural analyses using transmission electron microscopy. We demonstrated for the first time that intrafollicular levels of Pb (0.66 µg/dL-0.85 µg/dL) and Cd (0.26 µg/L-0.41 µg/L) could be associated with morphological alterations of both the oocyte and cumulus cells' (CCs) ultrastructure. Since blood Cd levels (0.54 µg/L-1.87 µg/L) were above the current reference values established by the guidelines of the Agency for Toxic Substances and Disease Registry (ATSDR) and the Environmental Protection Agency (EPA) (0.4 µg/L), whereas blood Pb levels (1.28 µg/dL-3.98 µg/dL) were below the ATSDR reference values (≤5 µg/dL), we believe that these alterations could be due especially to Cd, even if we cannot exclude a possible additional effect of Pb. Our results highlighted that oocytes were affected in maturation and quality, whereas CCs showed scarcely active steroidogenic elements. Regressing CCs, with cytoplasmic alterations, were also numerous. According to Cd's endocrine-disrupting activity, the poor steroidogenic activity of CCs might correlate with delayed oocyte cytoplasmic maturation. So, we conclude that levels of heavy metals in the blood and the FF might negatively affect fertilization, embryo development, and pregnancy, compromising oocyte competence in fertilization both directly and indirectly, impairing CC steroidogenic activity, and inducing CC apoptosis.