Bisphenol A-induced oxidative stress, hepatotoxicity and altered estrogen receptor expression in Labeo bata: impact on metabolic homeostasis and inflammatory response

Multi-mechanistic effects of bisphenol A on testicular dysfunction and endocrine disruption in adult male Labeo bata: oxidative stress, inflammation, and dysregulated energy sensors

Leaching of BPA, a potent endocrine disruptor, from microplastics in aquatic environments has garnered renewed interest in its impact on male reproduction. However, the mechanisms underlying BPA modulation of testicular metabolic, endocrine, and autocrine-paracrine axes in teleost remained relatively unexplored, prompting us to examine BPA-induced testicular dysfunction in adult male Labeo bata. Present results demonstrate that congruent with reduced gonadosomatic index (GSI), chronic BPA treatment at environmentally relevant concentrations enhanced ROS synthesis, oxidative stress, and testicular histopathology characterized by reduced diameter of seminiferous tubules, a sharp decline in spermatozoa, and elevated fibrosis during the spawning season. Elevated NO levels, pro-inflammatory cytokines and NLRP3-inflammasome activation correlated with cleaved caspase -8, -9, -3 activation, altered Bax/Bcl-2 ratio, heightened caspase -3 immunolocalization and TUNEL staining, suggesting DNA damage and apoptosis in BPA-treated testis. Besides, BPA attenuation of cyclin B synthesis and p-p34cdc2 (Thr161) phosphorylation (activation), markers associated with altered meiotic cell cycle progression, corresponded with heightened apoptosis and loss of spermatogenic cells. Importantly, disrupted estrogen and membrane progestin receptor (ERα, ERβ, mPRα-PGRMC1) homeostasis, alteration in gonadotropin receptor (LHCGR) and steroidogenic markers and elevated P450 aromatase immunolocalization indicate endocrine disruption and heightened estrogenic influence of BPA, inducing testicular dysfunction. Congruently, BPA modulation of cellular energy sensors (SIRT1/p-AMPKα/PGC-1α), factors influencing testicular endocrine, paracrine and prostaglandin signalling, and MAPK modulation might indicate pleiotropic regulation by BPA triggering reproductive toxicity. While Pearson's correlation and elevated multi-biomarker IBR indices support testicular dysfunction, present findings highlight the need for further research initiatives and strict regimens to combat ecological risks posed by BPA contamination.

Exploring the ecotoxicological impacts of microplastics on freshwater fish: A critical review

Microplastics (MPs) have become ubiquitous in the environment, prompting significant concern among ecotoxicologists due to their potential toxic effects. These particles originate from various sources, including the fragmentation of larger plastic debris (secondary microplastics) and consumer products such as liquid soaps, exfoliants, and cleaning agents. The widespread use of plastics, coupled with inadequate waste management, poses a growing threat to ecosystem health worldwide. MPs are plastic particles composed of high-molecular-weight polymers that exhibit biochemical stability. Plastics break down into MPs and even smaller nanoplastics through various degradation mechanisms, such as exposure to UV radiation from sunlight and other environmental factors. Due to their resemblance to certain types of zooplankton and food particles, MPs are often ingested by fish, entering their digestive systems. Once inside, they do not remain solely in the gut; rather, they infiltrate the fish's circulatory and lymphatic systems, eventually distributing throughout various tissues and organs. Microplastics have been found in fish gills, muscles, liver, heart, swim bladders, ovaries, spinal cords, and even brains. The presence of MPs in these organs has been linked to significant adverse effects, including reproductive, neurological, hormonal, and immune system disruptions. This toxicity extends beyond fish, as bioaccumulation and biomagnification of MPs affect other organisms as well, marking MPs as a major anthropogenic stressor that impacts ecosystems at multiple levels. Research indicates that nearly all aquatic environments globally are at risk of MP contamination. Laboratory and field studies highlight fish as particularly susceptible to MP ingestion, though freshwater species have been less extensively studied than marine counterparts. After exposure, fish may suffer various health issues, either directly from MPs or from their interaction with other contaminants. The broader environmental implications of these laboratory findings and the specific role of MPs in increasing fish exposure to harmful chemicals remain topics of ongoing debate. This review aims to contribute to ecotoxicological insights on fish contamination by MPs and outline areas for future investigation.

Maternal exposure to chronic, low-dose nonylphenol in zebrafish: Disruption of ovarian health, reproductive function, and embryogenesis

Nonylphenol (NP), a non-ionic surfactant and potent endocrine disruptor, is known for its environmental persistence, biotic accumulation potential and toxicity. Nonetheless, mechanisms underlying NP modulation of female fertility with potential impact on embryogenesis in the unexposed offspring remain elusive. This study investigates the effects and toxic mechanisms of maternal exposure to NP at varying concentrations (50 and 100 μg/L) on zebrafish (Danio rerio), specifically focusing on ovarian health, reproductive parameters, and early developmental potential in the F1 generation. Our findings indicate a higher accumulation of NP in the ovaries compared to muscle tissue. Further, chronic (28 days) NP exposure promotes ovarian reactive oxygen species (ROS) accumulation, activates the MAPK (JNK, p38 MAPK, ERK1/2) pathways, AP-1 induction, and elevated expression of pro-inflammatory cytokines (Tnf-α, Il-1β, Il-6) triggering inflammation. Besides, heightened follicular atresia in NP-treated ovaries relates to increased Bax/Bcl2 ratio, cleaved caspase 3 and Parp1 activation prompting apoptosis. While it showed higher affinity to zebrafish ERα (in silico analysis), NP exposure in vivo promotes a robust increase in ovarian ERα but abrogated ERβ expression and a significant alteration in fshr and lhcgr transcripts. While attenuated StAR and P450 aromatase expression at both mRNA and protein levels and reduced igf3 expression reveal impaired ovarian microenvironment, NP-induced dysregulated NO/NOS/cyclooxygenase signaling and attenuation of hCG-induced p34cdc2 activation and oocyte maturation correspond well with decreased fecundity and fertilization efficiency. Intriguingly, maternal exposure to NP resulted in delayed embryogenesis, developmental aberrations, and reduced hatching rates in the unexposed offspring, risking F1 generation. Collectively, this study provides mechanistic insights into the detrimental influence of maternal exposure to NP on ovarian dysfunction, reproductive insufficiency and embryotoxicity.

DINCH Exposure Triggers Inflammatory, Oxidative, and Apoptotic Pathways in the Liver of Long-Evans Lactating Rats and Their Offspring

1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) is a non-phthalate plasticizer used as a replacement of di(2-ethylhexyl) phthalate (DEHP) in daily usage items. It is not known whether continuous exposure to low doses of DINCH can lead to hepatic alterations, the liver being the organ responsible for its metabolism. The aim of this study was to evaluate the activation of inflammatory and apoptotic pathways in the liver of lactating dams after DINCH exposure, and whether these effects may be observed on postnatal day 6 (PND6) offspring. Two doses of DINCH were tested by oral administration to the following three groups of Long-Evans rats: control, DINCH-lower dose (LDINCH, 30 mg/kg b.w./day), and DINCH-high dose (HDINCH, 300 mg/kg b.w./day). Inflammatory mediators (IL-1β, TNF-α, NF-κB), mitochondrial transcriptional factors (PPARγ and PGC-1α), oxidative stress markers (SOD, CAT, GSSG/GSH), and components of the mitochondrial apoptotic pathway (PUMA, BAX, BAD, Bcl-2, Bcl-xL, Cytochrome c, APAF-1, Caspase-3, AIF) were assessed by the gene and protein expression in the liver of lactating dams and offspring. Exposure to LDINCH promoted the release of pro-inflammatory cytokines such as IL-1β and TNF-α and raised oxidative stress levels (GSSG/GSH), as well as increased Caspase-3 levels and reduced anti-apoptotic proteins (Bcl-2 and Bcl-xL), both in lactating dams and PND6 offspring. Thus, constant exposure to lower doses of DINCH can disrupt inflammatory and oxidant/antioxidant homeostasis, leading to hepatic tissue damage in lactating dams and having a perinatal effect in PND6 offspring.

Unravelling bisphenol A-induced hepatotoxicity: Insights into oxidative stress, inflammation, and energy dysregulation

Bisphenol A (BPA), a prevalent plastic monomer and endocrine disruptor, negatively impacts metabolic functions. This study examines the chronic effects of eco-relevant BPA concentrations on hepatotoxicity, focusing on redox balance, inflammatory response, cellular energy sensors, and metabolic homeostasis in male Swiss albino mice. Chronic BPA exposure resulted in reactive oxygen species (ROS) accumulation, altered hepatic antioxidant defense, lipid peroxidation, and NOX4 expression, leading to reduced cell viability. Additionally, BPA exposure significantly upregulated hepatic pro-inflammatory cytokine genes (Tnf-α, Il-1β, Il-6), NOS2, and arginase II, correlating with increased TLR4 expression, NF-κB phosphorylation, and a dose-dependent decrease in IκBα levels. BPA-induced NF-κB nuclear localization and inflammasome activation (NLRP3, cleaved caspase-1, IL-1β) established an inflammatory milieu. Perturbations in hepatic AMPKα phosphorylation, SIRT1, and PGC-1α, along with elevated p38 MAPK phosphorylation and ERα expression, indicated BPA-induced energy dysregulation. Furthermore, increased PLA2G4A, COX1, COX2, and PTGES2 expression in BPA-treated liver correlated with hyperlipidemia, hepatic FASN expression, steatosis, and visceral adiposity, likely due to disrupted energy sensors, oxidative stress, and inflammasome activation. Elevated liver enzymes (ALP, AST, ALT) and apoptotic markers indicated liver damage. Notably, N-acetylcysteine (NAC) priming reversed BPA-induced hepatocellular ROS accumulation, NF-κB-inflammasome activation, and intracellular lipid accumulation, while upregulating cellular energy sensors and attenuating ERα expression, suggesting NAC's protective effects against BPA-induced hepatotoxicity. Pharmacological inhibition of the NF-κB/NLRP3 cascade in BAY11-7082 pretreated, or NLRP3 immunodepleted hepatocytes reversed BPA's negative impact on SIRT1/p-AMPKα/PGC-1α and intracellular lipid accumulation, providing mechanistic insights into BPA-induced metabolic disruption.

Mechanisms insights into bisphenol S-induced oxidative stress, lipid metabolism disruption, and autophagy dysfunction in freshwater crayfish

Bisphenol S (BPS) is widely used in plastic products, food packaging, electronic products, and other applications. In recent years, BPS emissions have increasingly impacted aquatic ecosystems. The effects of BPS exposure on aquatic animal health have been documented; however, our understanding of its toxicology remains limited. This study aimed to explore the mechanisms of lipid metabolism disorders, oxidative stress, and autophagy dysfunction induced in freshwater crayfish (Procambarus clarkii) by exposure to different concentrations of BPS (0 µg/L, 1 µg/L, 10 µg/L, and 100 µg/L) over 14 d. The results indicated that BPS exposure led to oxidative stress by inducing elevated levels of reactive oxygen species (ROS) and inhibiting the activity of antioxidant-related enzymes. Additionally, BPS exposure led to increased lipid content in the serum and hepatopancreas, which was associated with elevated lipid-related enzyme activity and increased expression of related genes. Furthermore, BPS exposure decreased levels of phosphatidylcholine (PC) and phosphatidylinositol (PI), disrupted glycerophospholipid (GPI) metabolism, and caused lipid deposition in the hepatopancreatic. These phenomena may have occurred because BPS exposure reduced the transport of fatty acids and led to hepatopancreatic lipid deposition by inhibiting the transport and synthesis of PC and PI in the hepatopancreas, thereby inhibiting the PI3K-AMPK pathway. In conclusion, BPS exposure induced oxidative stress, promoted lipid accumulation, and led to autophagy dysfunction in the hepatopancreas of freshwater crayfish. Collectively, our findings provide the first evidence that environmentally relevant levels of BPS exposure can induce hepatopancreatic lipid deposition through multiple pathways, raising concerns about the potential population-level harm of BPS and other bisphenol analogues.

Safe concentration, unsafe effects: Impact of BPA on antioxidant function in the hepatopancreas and ovarian gene expression in oriental river prawns (Macrobrachium nipponense)

This study investigated the effects of Bisphenol A (BPA), a common endocrine-disrupting chemical, on the antioxidant enzyme activities in the hepatopancreas and the expression of genes related to ovarian development in oriental river prawns (Macrobrachium nipponense). The 24hLC50 and 48hLC50 values for BPA were 80.59 mg/L and 63.90 mg/L, respectively, with a safe concentration of 12.06 mg/L. Prawns were exposed to low (4.85 mg/L), safe (12.06 mg/L), and high (30.00 mg/L) concentrations of BPA for 10 days to measure enzyme activities, and for 20 days followed by 7 days in BPA-free water to measure gene expression. Short-term exposure (12 h, 1d, 3d) to low concentration BPA did not significantly affect superoxide dismutase (SOD) activity in the hepatopancreas (P > 0.05), but long-term exposure (6d, 10d) significantly reduced SOD activity (P < 0.05). Catalase (CAT) activity showed no significant changes throughout the low concentration exposure period (P > 0.05). At safe and high concentrations, SOD and CAT activities significantly decreased after 12 h of exposure (P < 0.05). BPA affected heat shock protein 90 (HSP90) expression in the ovary, with low concentration BPA significantly upregulating HSP90 after 1 day (P < 0.05), but returning to normal levels after 10 and 20 days. At the safe concentration, HSP90 was significantly upregulated at all three sampling points (1d, 10d, 20d) (P < 0.05), while high concentration exposure led to significant upregulation only on day 10 (P < 0.05). Low concentration BPA had no significant effect on Cathepsin B (CB) and Cathepsin L (CL) gene expression in the ovaries (P > 0.05). However, safe concentration exposure promoted CB expression on days 1, 10, and 20 (P < 0.05), while high concentration exposure significantly increased CB expression on day 1 (P < 0.05), with levels returning to normal on days 10 and 20. CL expression significantly increased after 20 days of exposure to both safe and high concentrations (P < 0.05). Gene expression levels in the ovaries returned to normal after transfer to BPA-free water, with HSP90 and CB normalizing by day 1, and CL by day 7. These results indicate that even safe concentrations of BPA impose stress on the hepatopancreas and increase the expression of HSP90, CB, and CL genes in the ovaries, affecting ovarian development. And, these effects are reversible within a certain period after the removal of BPA.

Determination of Bisphenol Compounds and the Bioaccumulation after Co-Exposure with Polyethylene Microplastics in Zebrafish

Knowledge regarding the combined toxicity mechanism of bisphenol compounds and microplastics (MPs) on organisms remains limited. In this study, we first developed an accurate and sensitive method to simultaneously quantify two bisphenol compounds and evaluate their accumulation and tissue distribution after co-exposure with MPs in zebrafish. Then, we determined the bioaccumulation potential of bisphenol A (BPA) and bisphenol S (BPS) in adult zebrafish in the absence and presence of MPs. Bisphenol compounds were found to accumulate in different tissues of zebrafish, with BPS showing lower accumulation levels compared to BPA. Importantly, we discovered that the presence of MPs could exacerbate the accumulation of bisphenol compounds in biological tissues. These findings highlight the enhanced bioavailability and risk posed by the co-exposure of bisphenol compounds and MPs, underscoring the need for further investigation into their combined environmental and biological health impacts.

TDMPP activation of estrogen receptor 2a regulates smc2 and p53 signaling to interfere with liver development in zebrafish (Danio rerio)

Tris (2,6-dimethylphenyl) phosphate (TDMPP), a novel organic phosphorus flame retardant (OPFR), has been found to have estrogenic activity. Estrogens are critical in regulating various biological responses during liver development. However, the effects of TDMPP on zebrafish liver development remain largely unexplored. Here, we utilized a chemical genetic screening approach to assess the estrogenic effects of TDMPP on liver development and to elucidate the underlying molecular mechanism. Our findings revealed that zebrafish larvae exposed to environmentally relevant concentrations of TDMPP (0.05 and 0.5 μM) exhibited concentration-dependent liver impairments, including reduced liver size, histopathological changes, and hepatocyte apoptosis. In addition, E2 caused similar adverse effects to TDMPP, but the pharmacological blockade of estrogen synthesis alleviated the effects on liver development. Chemical inhibitors and morpholino knockdown assays indicated that the reduction of esr2a blocked TDMPP-induced liver impairments, which was further confirmed in the esr2a-/- mutant line. Subsequently, transcriptomic analysis showed that the estrogen receptor activated by TDMPP inhibited the expression of smc2, which was linked to the suppression of liver development through p53 activation. Consistently, overexpression of smc2 and inhibition of p53 evidently rescued hepatic damages induced by TDMPP. Taken together, the above findings identified esr2a, downstream smc2, and p53 as important regulators for the estrogenic effects of TDMPP on liver development. Our work fills crucial gaps in the current knowledge of TDMPP's hepatotoxicity, providing new insights into the adverse effects of TDMPP and the molecular mechanisms of action. These findings underscore the need for further ecological risk assessment and regulatory considerations.

Participation of follicular superoxides, inflammatory modulators, and endocrine factors in zebrafish (Danio rerio) ovulation: Cross-talk between PKA and MAPK signaling in Pgr regulation of ovulatory markers

The ovulatory response involves diverse molecular determinants, the interplay between which remains less investigated in fish. This study explores the temporal changes in the follicular microenvironment, regulatory factors, and underlying signaling events during ovulation in female zebrafish subjected to 14L:10D at 28 ± 1 °C in vivo vis-à-vis in hCG-stimulated full-grown (FG) follicles in vitro. Congruent with reduced GSH levels, SOD, and GPx activity, a graded increase in follicular free radicals, Nox4, and p38 MAPK phosphorylation in the morning hour groups (05:00 and 06:30) correlates positively with the ovulatory surge in inflammatory mediators (Tnf-α, Il-1β, Il-6, Nos2, and Cox-2). Further, elevated Pgr expression and its nuclear translocation, congruent with follicular lhcgr, star, and hsd20b2 upregulation in vivo, corroborates well with the transcriptional activation of genes (pla2g4aa, ptgesl, ptger4b, mmp9, adamts9), triggering ovulation in this species. Mechanistically, an elevated ovulatory response in hCG-treated FG follicles in vitro involves the upregulation of inflammatory mediators, pgr and ovulation-associated genes in a manner sensitive to PKA- and MAPK3/1-mediated signaling.

Ecotoxicological responses of juvenile Sparus aurata to BDE-99 and BPA exposure: A multi-biomarker approach integrating immune, endocrine and oxidative endpoints

Pentabromodiphenyl ether (BDE-99) and bisphenol A (BPA) are synthetic organic compounds present in several daily use products. Due to their physicochemical properties, they are ubiquitously present in aquatic ecosystems and considered highly persistent. Recent evidence has confirmed that both emerging compounds are toxic to humans and terrestrial mammals eliciting a wide range of detrimental effects at endocrine and immune levels. However, the ecotoxicological responses that they can trigger in vertebrate marine species have not yet been established. Hence, this study aimed to investigate the ecotoxicological responses of juvenile Sparus aurata upon chronic (28 days) dietary exposure to BDE-99 and BPA (alone and combined) following an integrated multi-biomarker approach that combined fitness indicators (Fulton's K and splenosomatic indexes) with endocrine [cortisol, 17β-estradiol (E2), 11-ketotestosterone (11-KT) concentrations] and immune (peroxidase and antiprotease activities) endpoints in fish plasma, and oxidative stress [superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) activities, and lipid peroxidation (LPO)] endpoints in the fish spleen. The mixture of BDE-99 and BPA yielded the highest IBR index value in both plasma and spleen biomarkers, therefore, suggesting that the effects of these compounds are more severe when they act together. Endocrine biomarkers were the most responsive in the three contaminated treatments. Fitness indicators were not affected by the individual nor the interactive effects of BDE-99 and BPA. These findings highlight the relevance of accounting for the interactive effects of emerging chemical contaminants and integrating responses associated with distinct biological pathways when investigating their impacts on marine life, as such a multi-biomarker approach provides a broader, more realistic and adequate perspective of challenges faced by fish in a contaminated environment.

Reproductive toxicity of bisphenol A, at environmentally relevant concentrations, on ovarian redox balance, maturational response, and intra-oocyte signalling events in Labeo bata

Bisphenol A (BPA) is a widely used plastic monomer that potentially interferes with ovarian neuroendocrine, endocrine, and autocrine/paracrine factors, causing reproductive dysfunction. However, the influence of BPA on redox balance, estrogen receptor (ER) expression vis-à-vis meiotic cell cycle progression, and intra-oocyte signalling events has not been extensively investigated. The present study examines the impact of BPA on reproductive toxicity in female Labeo bata (Order Cypriniformes, Family Cyprinidae), a freshwater teleost preferred as a food fish in the Indian subcontinent. Our results show that while ovarian weight (gonadosomatic index, GSI) and dynamics of follicular growth undergo pronounced changes during the annual reproductive cycle, chronic BPA exposure at environmentally relevant concentrations promotes follicular atresia concomitant with reduced GSI during the spawning phase, the highest response being observed due to low-dose (0.1 μg/L, 0.438 nM) BPA exposure in vivo. Furthermore, BPA perturbation of ovarian StAR expression and ERα/ERβ homeostasis corroborates with elevated oxidative stress in BPA-treated ovary, FG follicles, and follicular cells. A sharp increase in ROS accumulation and nitric oxide (NO) levels in BPA-treated full-grown (FG) follicles coupled with loss of redox balance, elevated follicular cell death, and activation of apoptotic markers (caspase -8, -9, -3, Bax) indicate poor oocyte health and reproductive toxicity. Importantly, maturational steroid (MIS, 17,20β-P)-induced cyclin B-p34cdc2 activation and elevated GVBD (germinal vesicle breakdown) response require protein kinase A (PKA) inhibition and participation of Mos/MAPK- and cdc25-mediated signalling events. While the adenylate cyclase activator forskolin (FK) abrogates, priming with a PKA inhibitor (H89) promotes the meiotic G2-M1 transition, confirming the role of PKA in meiotic cell cycle progression in this species. Furthermore, the negative influence of BPA priming on 17,20β-P-induced oocyte maturation involves elevated PKAc phosphorylation (activation) and significant alteration in Mos/MAPK signalling, indicating derailed meiotic maturational competence and disrupted oocyte quality.

Bisphenol AF Induces Prostatic Dorsal Lobe Hyperplasia in Rats through Activation of the NF-κB Signaling Pathway

Bisphenol AF (BPAF) represents a common environmental estrogenic compound renowned for its capacity to induce endocrine disruptions. Notably, BPAF exhibits an enhanced binding affinity to estrogen receptors, which may have more potent estrogenic activity compared with its precursor bisphenol A (BPA). Notwithstanding, the existing studies on BPAF-induced prostate toxicity remain limited, with related toxicological research residing in the preliminary stage. Our previous studies have confirmed the role of BPAF in the induction of ventral prostatic hyperplasia, but its role in the dorsal lobe is not clear. In this study, BPAF (10, 90 μg/kg) and the inhibitor of nuclear transcription factor-κB (NF-κB), pyrrolidinedithiocarbamate (PDTC, 100 mg/kg), were administered intragastrically in rats for four weeks. Through comprehensive anatomical and pathological observations, as well as the assessment of PCNA over-expression, we asserted that BPAF at lower doses may foster dorsal prostatic hyperplasia in rats. The results of IHC and ELISA indicated that BPAF induced hyperplastic responses in the dorsal lobe of the prostate by interfering with a series of biomarkers in NF-κB signaling pathways, containing NF-κB p65, COX-2, TNF-α, and EGFR. These findings confirm the toxic effect of BPAF on prostate health and emphasize the potential corresponding mechanisms.

Effects of developmental exposures to Bisphenol-A and Bisphenol-S on hepatocellular function in male Long-Evans rats

Bisphenol-S (BPS) is a current substitute for Bisphenol-A (BPA) in various commercial products (paper, plastics, protective can-coatings, etc.) used by all age groups globally. The current literature indicates that a drastic surge in pro-oxidants, pro-apoptotic, and pro-inflammatory biomarkers in combination with diminished mitochondrial activity can potentially decrease hepatic function leading to morbidity and mortality. Consequently, there are increasing public health concerns that substantial Bisphenol-mediated effects may impact hepatocellular functions, particularly in newborns exposed to BPA and BPS postnatally. However, the acute postnatal impact of BPA and BPS and the molecular mechanisms affecting hepatocellular functions are unknown. Therefore, the current study investigated the acute postnatal effect of BPA and BPS on the biomarkers of hepatocellular functions, including oxidative stress, inflammation, apoptosis, and mitochondrial activity in male Long-Evans rats. BPA and BPS (5 and 20 microgram/Liter (μg/L) of drinking water) were administered to 21-day-old male rats for 14 days. BPS had no significant effect on apoptosis, inflammation, and mitochondrial function but significantly reduced the reactive oxygen species (51-60 %, **p < 0.01) and nitrite content (36 %, *p < 0.05), exhibiting hepatoprotective effects. As expected, based on the current scientific literature, BPA induced significant hepatoxicity, as seen by significant glutathione depletion (50 %, *p < 0.05). The in-silico analysis indicated that BPS is effectively absorbed in the gastrointestinal tract without crossing the blood-brain barrier (whereas BPA crosses the blood-brain barrier) and is not a substrate of p-Glycoprotein and Cytochrome P450 enzymes. Thus, the current in-silico and in vivo findings revealed that acute postnatal exposure to BPS had no significant hepatotoxicity.

Neurotoxicity of bisphenol A exposure on Caenorhabditis elegans induced by disturbance of neurotransmitter and oxidative damage

Bisphenol A (BPA) is putatively regarded as an environmental neurotoxicant found in everyday plastic products and materials, however, the possible neurobehavioral adverse consequences and molecular mechanisms in animals have not been clearly characterized. The nematode Caenorhabditis elegans has become a promising animal model for neurotoxicological researches. To investigate the dose-effect relationships of BPA-induced neurotoxicity effects, the locomotion behavior and developmental parameters of the nematode were determined after BPA exposure. The present data demonstrated that BPA caused neurobehavioral toxicities, including head thrashes and body bends inhibition. In addition, when C. elegans was exposed to BPA at a concentration higher than 2 μM, growth and survival rate were decreased. The serotonergic, dopaminergic and GABAergic neurons were damaged by BPA. Furthermore, lower levels of mRNA expression related to dopamine, serotonin and GABA were detected in the worms exposed to 50 μM BPA. Increased SOD-3 expression might be adaptive response to BPA exposure. Moreover, oxidative damage triggered by BPA was manifested by changes in GST-4 expression, accompany with abnormity of ATP synthesis, but not nuclear localization of DAF-16/FOXO. Finally, we showed that epigallocatechin-3-gallate partially rescued BPA-induced reactive oxygen species (ROS) production and neurobehavioral toxicity. Altogether, the neurobehavioral and developmental toxicity of BPA may be induced by neurotransmission abnormity and oxidative damage. The present data imply that oxidative stress is linked to neuronal damage and neurobehavioral harm resulting from developmental BPA exposure.

Hematological changes, redox imbalance, and changes in Na+/K+-ATPase activity caused by bisphenol-A and the integrated biomarker responses in Labeo rohita (Hamilton, 1822)

Bisphenol-A (BPA) is a plasticizer commonly used in the plastics industry to manufacture plastic materials. It is abundant in aquatic ecosystems, resulting in increased contamination and lower concentrations that may represent a significant threat to the aquatic system. Hence in the present study, an Indian major carp, Labeo rohita, was exposed to two different BPA concentrations (1 and 10 μg/L) for 30 days. Compared to control, the chronic effects resulted in significant alterations in red blood cell (RBC) and white blood cells (WBC) count. The exposure to BPA caused significant changes in antioxidant activity in gill, liver, and kidney tissues (inferred by catalase, glutathione peroxidase, and glutathione S-transferase activity) in L. rohita. Regarding lipid peroxidation (LPO), we observed an increase in liver and kidney alteration, while LPO was noted in gill tissue compared to the control. Furthermore, increased Na+/K+-ATPase activity was observed in gills at the end of the 10th day and a gradual decrease at the end of the 30th day. These results indicated that exposure to BPA alters the RBC and WBC levels, antioxidant enzyme activity (gills, liver, and kidney), and Na+/K+-ATPase activity in the gill of L. rohita exposed to BPA (at 1 and 10 μg/L). Therefore, our findings will help us gain better insight into the toxicity of BPA in freshwater ichthyofauna.

Exposure to Bisphenol A Substitutes, Bisphenol S and Bisphenol F, and Its Association with Developing Obesity and Diabetes Mellitus: A Narrative Review

Bisphenol A, a well-known endocrine-disrupting chemical, has been replaced with its analogs bisphenol S (BPS) and bisphenol F (BPF) over the last decade due to health concerns. BPS and BPF are present in relatively high concentrations in different products, such as food products, personal care products, and sales receipts. Both BPS and BPF have similar structural and chemical properties to BPA; therefore, considerable scientific efforts have investigated the safety of their exposure. In this review, we summarize the findings of relevant epidemiological studies investigating the association between urinary concentrations of BPS and/or BPF with the incidence of obesity or diabetes. The results showed that BPS and BPF were detected in many urinary samples at median concentrations ranging from 0.03 to 0.4 µg·L-1. At this exposure level, BPS median urinary concentrations (0.4 µg·L-1) were associated with the development of obesity. At a lower exposure level (0.1-0.03 µg·L-1), two studies showed an association with developing diabetes. For BPF exposure, only one study showed an association with obesity. However, most of the reported studies only assessed BPS exposure levels. Furthermore, we also summarize the findings of experimental studies in vivo and in vitro regarding our aim; results support the possible obesogenic effects/metabolic disorders mediated by BPS and/or BPF exposure. Unexpectedly, BPS may promote worse obesogenic effects than BPA. In addition, the possible mode of action underlying the obesogenic effects of BPS might be attributed to various pathophysiological mechanisms, including estrogenic or androgenic activities, alterations in the gene expression of critical adipogenesis-related markers, and induction of oxidative stress and an inflammatory state. Furthermore, susceptibility to the adverse effects of BPS may be altered by sex differences according to the results of both epidemiological and experimental studies. However, the possible mode of action underlying these sex differences is still unclear. In conclusion, exposure to BPS or BPF may promote the development of obesity and diabetes. Future approaches are highly needed to assess the safety of BPS and BPF regarding their potential effects in promoting metabolic disturbances. Other studies in different populations and settings are highly suggested.

Urinary concentrations of phenols, oxidative stress biomarkers and thyroid cancer: Exploring associations and mediation effects

Phenols have been shown to influence the cellular proliferation and function of thyroid in experimental models. However, few human studies have investigated the association between phenol exposure and thyroid cancer, and the underlying mechanisms are also poorly understood. We conducted a case-control study by age- and sex-matching 143 thyroid cancer and 224 controls to investigate the associations between phenol exposures and the risk of thyroid cancer, and further to explore the mediating role of oxidative stress. We found that elevated urinary triclosan (TCS), bisphenol A (BPA) and bisphenol S (BPS) levels were associated with increased risk of thyroid cancer (all P for trends < 0.05), and the adjusted odds ratios (ORs) comparing the extreme exposure groups were 3.52 (95% confidence interval (CI): 2.08, 5.95), 2.06 (95% CI: 1.06, 3.97) and 7.15 (95% CI: 3.12, 16.40), respectively. Positive associations were also observed between urinary TCS, BPA and BPS and three oxidative stress biomarkers measured by 8-hydroxy-2'-deoxyguanosine (8-OHdG), 8-iso-prostaglandin F_2α (8-isoPGF_2α) and 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA), as well as between urinary 8-isoPGF_2α and HNE-MA and the risk of thyroid cancer. Mediation analysis showed that urinary 8-isoPGF_2α mediated 28.95%, 47.06% and 31.08% of the associations between TCS, BPA and BPS exposures and the risk of thyroid cancer, respectively (all P < 0.05). Our results suggest that exposure to TCS, BPA and BPS may be associated with increased risk of thyroid cancer and lipid peroxidation may be an intermediate mechanism. Further studies are warranted to confirm the findings.

Impact of Mycotoxin Contaminations on Aquatic Organisms: Toxic Effect of Aflatoxin B1 and Fumonisin B1 Mixture

(1) Background: Multiple contaminations of several mycotoxins have been detected in human and veterinary food and feed worldwide. To date, a number of studies on the combined effects of mycotoxins have been conducted on cell and animal models, but very limited studies have been done on aquatic organisms. (2) The purpose of the present study was to evaluate the combined toxic effects of Aflatoxin B1 (AFB1) and Fumonisin B1 (FB1) on zebrafish (Danio rerio) embryos. (3) Results: Our results showed that the combination of AFB1 and FB1 at nontoxic concentrations exerted a negative effect on the lethal endpoints analyzed, such as survival, hatching, and heart rate. In addition, the mixture of mycotoxins caused an increase in the levels of enzymes and proteins involved in the antioxidant process, such as superoxide dismutase (SOD) and catalase (CAT), both in terms of protein levels and gene expression, as well as an increase in the levels of the detoxification enzymes glutathione s-transferases (GST) and cytochromes P450 (CYP450). Furthermore, we showed that the mycotoxin mixture induced an increase in pro-apoptotic proteins such as bax and caspase 3, and at the same time reduced the gene expression of the anti-apoptotic bcl-2 protein. Finally, a significant decrease in thyroid function was observed in terms of triiodothyronine (T3), thyroxine (T4), and vitellogenin (VTG) levels. (4) Conclusion: We can say that the mixture of mycotoxins carries a greater risk factor than individual presences. There is a greater need for effective detoxification methods to control and reduce the toxicity of multiple mycotoxins and reduce the toxicity of multiple mycotoxins in feed and throughout the food chain.

Covalent Protein Modification: An Unignorable Factor for Bisphenol A-Induced Hepatotoxicity

Covalent modification of proteins by reactive pollutants/metabolites might trigger various toxicities resulting from the disruption of protein structures and/or functions, which is critical for understanding the mechanism of pollutants-induced toxicity. However, this mechanism has rarely been touched on due to the lack of a methodology. In this research, the protein modification of bisphenol A (BPA) in rats was characterized using a series of liquid chromatography-tandem mass spectrometry (LC-MS) approaches. BPA-modified cysteine (Cys1) was first released from proteins via enzymatic hydrolysis and identified using LC-MS. Moreover, the positive correlation between Cys1 and hepatotoxicity indicated the involvement of protein modification in BPA toxicity. Then, in vitro incubation of BPA with amino acids and protein confirmed that BPA could specifically modify cysteine residues of proteins after bioactivation and provided four additional modification patterns. Finally, 24 BPA-modified proteins were identified from the liver of BPA-exposed rats using proteomic analysis, and they were mainly enriched in oxidative stress-related pathways. The modification on superoxide dismutases, catalase, and glutathione S-transferases disrupted their enzymatic functions, leading to oxidative damage. These results revealed that the covalent protein modification is an unignorable factor for BPA hepatotoxicity. Moreover, the workflow can be applied to identify protein adducts of other emerging contaminants and possible risk.

Assessment of the impact of aquaculture facilities on transplanted mussels (Mytilus galloprovincialis): Integrating plasticizers and physiological analyses as a biomonitoring strategy

The growing plastic production and its continuous use is a significant problem. In addition, aquaculture practices have experienced a considerable growth and plastic is widely used in these activities, hence plasticizers must be considered due to their potential ecotoxicological impacts on species. Mussels placed inside an Integrated Multi-Trophic Aquaculture (IMTA) system and at two control locations were employed to quantify the ingestion of anthropogenic particles and associated chemical plasticizers, such as bisphenol A (BPA) jointly to bisphenol F (BPF) and bisphenol S (BPS), and phthalates represented by diethyl phthalate (DEP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). In addition, some metabolism and oxidative stress related parameters were measured in mussels' whole soft tissue. Anthropogenic particle ingestion of mussels increased over time at the three locations and the following order of abundance of pollutants was observed: BPA> BPF> DEHP> DBP> BPS> DEP. Even though no differences according to location were found for pollutants' occurrence, time trends were evidenced for BPA and DEHP. On the other hand, a location effect was observed for biomarkers with highest values detected in mussels located at the vicinities of the aquaculture facility. In addition, a reduced detoxification activity was observed over time parallel to BPA decrease.

New insights into potential estrogen agonistic activity of triazole fungicides and coupled metabolic disturbance

Triazole fungicides are highly effective pesticides widely used in plant protection, which has caused potential hazards to human health and ecological safety. To fully understand their potential hepatotoxicity, we first analyzed the transcriptome profiles in HepG2 cells treated with five triazole fungicides (hexiconazole (HEX), tebuconazole (TEB), propiconazole (PRO), cyproconazole (CYP), and difenoconazole (DIF)), and found that these pesticides remarkably affected estrogen signaling pathways, especially estrogen synthesis. Furthermore, we found that TEB, CYP, PRO and DIF had agonistic activity towards estrogen receptor alpha (ERα) and elucidated the binding mode of triazole ligands with ERα using the reporter gene assay and molecular docking. Four triazole fungicides regulated eight major genes involved in estrogen synthesis (StAR, CYP11A1, 3βHSD2, CYP17, CYP19, CYP3A4, CYP1A2 and SCP2) and stimulated the secretion of 17β-estradiol (E₂). Finally, we assessed possible metabolic outcomes caused by abnormal estrogen synthesis, and found that triazole fungicides affected the metabolism of various macromolecules (such as lipid, amino acid, and carbohydrate) and signal transduction. These findings will provide new insights into endocrine-disrupting effects of triazole fungicides and highlight their potential ecological and health risks.

Chronic exposure to nonylphenol induces oxidative stress and liver damage in male zebrafish (Danio rerio): Mechanistic insight into cellular energy sensors, lipid accumulation and immune modulation

Nonylphenol (NP), an environmentally persistent and toxic endocrine-disrupting chemical with estrogenic properties, has severe implications on humans and wildlife. Accumulating evidence demonstrates the toxic response of NP on the developmental process, nervous system, and reproductive parameters. Although NP exposure has been implicated in chronic liver injury, the underlying events associated with hepatic pathophysiology remain less investigated. Using male zebrafish (Danio rerio) as the model, the present study investigates the impact of environmentally relevant concentrations of NP (50 and 100 μg/L, 21 days) on hepatic redox homeostasis vis-à-vis cellular energy sensors, inflammatory response, and cell death involving a mechanistic insight into estrogen receptor (ER) modulation. Our results demonstrate that congruent with significant alteration in transcript abundance of antioxidant enzymes (SOD1, SOD2, Catalase, GPx1a, GSTα1), chronic exposure to NP promotes ROS synthesis, more specifically superoxide anions and H₂O₂ levels, and lipid peroxidation potentially through elevated NOX4 expression. Importantly, NP perturbation of markers associated with fatty acid biosynthesis (srebf1/fasn) and cellular energy-sensing network (sirt1/ampkα/pgc1α) indicates dysregulated energy homeostasis, metabolic disruption, and macrovesicular steatosis, albeit with differential sensitivity at the dose level tested. Besides, elevated p38-MAPK phosphorylation (activation) together with loss of ER homeostasis at both mRNA (esr1, esr2a, esr2b) and protein (ERα, ERβ) levels suggest that NP modulation of ER abundance may have a significant influence on hepatic events. Elevated expression of inflammatory markers (TLR4, p-NF-κB, TNF-α, IL-6, IL-1β, and NOS2) and pro-apoptotic and necrotic regulators, e.g., Bax, caspase- 8, -9 and cleaved PARP1 (50 kDa), indicate chronic inflammation and hepatotoxicity in NP-exposed males. Collectively, elevated oxidative stress, metabolic dysregulation and immune modulation may lead to chronic liver injury in organisms exposed to metabolic disrupting chemicals.

Assessing the combinatorial cytotoxicity of the exogenous contamination with BDE-209, bisphenol A, and acrylamide via high-content analysis

Food is often exposed to multiple types of contaminants, and the coexistence of contaminants may have antagonistic, additive or synergistic effects. This study investigated the combinatorial toxicity of the three most widespread exogenous contaminants, decabrominated diphenyl ether (BDE-209), bisphenol A (BPA), and acrylamide (ACR) to HepG2 cells. A mathematical model (Chou-Talalay) and high-content analysis (HCA) were used to probe the nature of the contaminants' interactions and their cytotoxicity mechanisms, respectively. The results highlighted that for the individual pollutants, the cytotoxicity order was BDE-209> BPA > ACR, and varying combinations of contaminants exhibited additive/synergistic effects. In general, combining multiple contaminants significantly increased intracellular reactive oxygen species (ROS), Ca²⁺ flux, DNA damage and Caspase-3, and decreased mitochondrial membrane potential (MMP) and nucleus roundness, indicating that the additive or synergistic mechanism of the combined contaminations was disturbance to multiple organelles. This study emphasizes the complexity of human exposure to food contaminants and provides a scientific basis for formulating strict regulatory standards.

Variations of enzymatic activity and gene expression in zebrafish (Danio rerio) embryos co-exposed to zearalenone and fumonisin B1

The natural co-occurrence of multiple mycotoxins has been reported in cereals and cereal products worldwide. Even though the dietary exposure to mycotoxins constitutes a serious human health, most reports are limited to the toxic effect of individual mycotoxins. The purpose of the present study was to assess the combined toxic effects of zearalenone (ZEN) and fumonisin B1 (FB1) and the potential interaction of their mixture on zebrafish (Danio rerio) embryos. Our results showed that ZEN possessed the higher toxicity to embryonic zebrafish (7-day LC₅₀ value of 0.78 mg a.i. L^-1) compared with FB1 (7-day LC₅₀ value of 227.7 mg a.i. L^-1). The combination of ZEN and FB1 exerted an additive effect on zebrafish embryos. Meanwhile, the activities of antioxidant CAT, caspase-3, and detoxification enzyme CYP450, as well as the expressions of six genes (Mn-sod, cas9, bax, cc-chem, ERα, and crh) associated with oxidative stress, cellular apoptosis, immune system, and endocrine system were prominently altered in the mixture exposure compared with the corresponding single treatment group of ZEN or FB1. Taken together, the regulatory standards of mycotoxins in food and feed should be updated based on the mixture effects of mycotoxins, and there is an increased need on effective detoxification methods for controlling and reducing the toxicity of multiple mycotoxins in animal feed and throughout the food supply chain.

Alteration of lipid metabolism, autophagy, apoptosis and immune response in the liver of common carp (Cyprinus carpio) after long-term exposure to bisphenol A

Bisphenol A (BPA), as a phenolic compound, is harmful to human health, and its residue in the aquatic environment also threatens the health of aquatic animals. In this research, the toxicity effects of BPA on liver tissues were evaluated in common carp (Cyprinus carpio) after long-term exposure. Fish were exposed to five concentrations of BPA (0, 0.01, 0.1, 0.5 and 2 mg/L) for 30 days. The blood and liver tissues were gathered to analyze biochemical indices and genes transcription levels. The data related to lipid metabolism showed that BPA exposure increased serum total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) levels, upregulated the expressions of fatp1, pparγ, fas, atgl, hsl, pparα, cpt1b, acox-1, and downregulated the expression of dgat1 in liver. Antioxidative parameters displayed a reduced antioxidant ability and increased lipid peroxidation after BPA exposure. Meanwhile, the upregulations of nrf2, ho-1, cyp1a and cyp1b genes revealed an adaptive response mechanism against oxidative stress-induced adverse effects. After 30 days of exposure, BPA induced apoptosis and endoplasmic reticulum stress (ERS) via upregulating the expression levels of apoptosis and ERS-related genes and increasing Ca²⁺ concentration in liver. Moreover, the downregulation of mtor and the upregulation of atg3, atg7, tfeb, uvrag and mcoln1 indicated that BPA could influence the normal process of autophagy. Furthermore, BPA exposure activated toll like receptors (TLRs) pathway to mediate the inflammatory response. Our results demonstrated that BPA exposure disturbed lipid metabolism, and induced oxidative stress, ERS, apoptosis, autophagy and inflammatory response in the liver of common carp. These findings contributed to the understanding of hepatotoxicity mechanism induced by BPA in fish.

Bisphenol A impairs reproductive fitness in zebrafish ovary: Potential involvement of oxidative/nitrosative stress, inflammatory and apoptotic mediators

Bisphenol A (BPA) is a highly pervasive chemical in consumer products with its ascribed endocrine-disrupting properties. Several studies have shown the cytotoxic, genotoxic, and carcinogenic property of BPA over a multitude of tissues. Although BPA exposure has earlier been implicated in female infertility, the underlying molecular mechanisms explaining the toxicity of BPA in the ovary remains less understood. In the present study, a plausible correlation between redox balance or inflammatory signaling and reproductive fitness upon BPA exposure has been examined in zebrafish (Danio rerio) ovary. Congruent with significant alteration of major antioxidant enzymes (SOD1, SOD2, catalase, GPx1α, GSTα1) at the transcript level, 30 d BPA exposure at environmentally relevant concentrations (1, 10 and 100 μg L^-1) promotes ovarian ROS/RNS synthesis, lipid peroxidation but attenuates catalase activity indicating elevated stress response. BPA promotes a sharp increase in ovarian p38 MAPK, NF-κB phosphorylation (activation), inducible nitric oxide synthase (Nos2a), and pro-inflammatory cytokines (TNF-α and IL-1β) expression, the reliable markers for inflammatory response. Congruent to an increased number of atretic follicles, BPA-exposed zebrafish ovary reveals elevated Bax/Bcl2 ratio, activation of caspase-8, -3 and DNA breakdown suggesting heightened cell death. Importantly, significant alteration in nuclear estrogen receptor (ER) transcripts (esr1, esr2a, and esr2b) and proteins (ERα, ERβ), gonadotropin receptors, and markers associated with steroidogenesis and growth factor gene expression in BPA-exposed ovary correlates well with impaired ovarian functions and maturational response. Collectively, elevated oxidative/nitrosative stress-mediated inflammatory response and altered ER expression can influence ovarian health and reproductive fitness in organisms exposed to BPA environment.