Preliminary investigation into the impact of BPA on osteoblast activity and bone development: In vitro and in vivo models.

Bisphenol A (BPA), an ingredient in consumer products, has been suggested that it can interfere with bone development and maintenance, whereas the molecule mechanism remains unclear. The objective of this study is to investigate the effect of BPA on early bone differentiation and metabolism, and its potential molecule mechanism by employing hFOB1.19 cell as an in vitro model, as well as larval zebrafish as an in vivo model. The in vitro experiments indicated that BPA decreased cell viability, inhibited osteogenic activity (such as ALP, RUNX2), increased ROS production, upregulated transcriptional or protein levels of apoptosis-related molecules (such as Caspase 3, Caspase 9), while suppressed transcriptional or protein levels of pyroptosis-specific markers (TNF-α, TNF-ß, IL-1ß, ASC, Caspase 1, and GSDMD). Moreover, the evidences from in vivo model demonstrated that exposure to BPA distinctly disrupted pharyngeal cartilage, craniofacial bone development, and retarded bone mineralization. The transcriptional level of bone development-related genes (bmp2, dlx2a, runx2, and sp7), apoptosis-related genes (bcl2), and pyroptosis-related genes (cas1, nlrp3) were significantly altered after treating with BPA in zebrafish larvae. In summary, our study, combining in vitro and in vivo models, confirmed that BPA has detrimental effects on osteoblast activity and bone development. These effects may be due to the promotion of apoptosis, the initiation of oxidative stress, and the inhibition of pyroptosis.

Astaxanthin activates the Nrf2/Keap1/HO-1 pathway to inhibit oxidative stress and ferroptosis, reducing triphenyl phosphate (TPhP)-induced neurodevelopmental toxicity.

Triphenyl phosphate (TPhP) serves as a major organophosphorus flame retardant, and its induced neurodevelopmental toxicity has attracted widespread attention, but the mechanism remains unclear. In this study, we involved zebrafish to explore the new mechanism of TPhP inducing oxidative stress and ferroptosis to promote neurodevelopmental toxicity. The results suggested that TPhP affected the embryonic development, reduced the number of new neurons, and led to abnormal neural behavior in zebrafish larvae. TPhP also induced ROS accumulation, activated the antioxidant defense signal Nrf2 and Keap1, and significantly changed the activities of Acetylcholinesterase (AChE), Adenosine triphosphatase (ATPase) and glutathione S-transferase (GST). In addition, TPhP induced ferroptosis in zebrafish, which was reflected in the increase of Fe2+ content, the abnormal expression of GPX4 protein and genes related to iron metabolism (gpx4a, slc7a11, acsl4b, tfa, slc40a1, fth1b, tfr2, tfr1a, tfr1b and ncoa4). Astaxanthin intervention specifically inhibited ROS levels, and reversed SLC7A11 and GPX4 expression levels and Fe2+ metabolism thus alleviating ferroptosis induced by TPhP. Astaxanthin also partially reversed the activity of AChE, GST and the expression of neurodevelopmental-related genes (gap43, gfap, neurog1 and syn2a), so as to partially rescue the embryonic developmental abnormalities and motor behavior disorders induced by TPhP. More interestingly, the expression of mitochondrial apoptosis-related protein BAX, anti-apoptotic protein BCL-2, Caspase3 and Caspase9 was significantly altered in the TPhP exposed group, which could be also reversed by Astaxanthin intervention. In summary, our results suggested that TPhP exposure can induce oxidative stress and ferroptosis, thereby causing neurodevelopment toxicity to zebrafish, while Astaxanthin can partially reverse oxidative stress and reduce the neurodevelopmental toxicity of zebrafish larvae by activating Nrf2/Keap1/HO-1 signaling pathway.

Exposure of male adult zebrafish (Danio rerio) to triphenyl phosphate (TPhP) induces eye development disorders and disrupts neurotransmitter system-mediated abnormal locomotor behavior in larval offspring.

Triphenyl phosphate (TPhP) is a widely used organophosphorus flame retardant, which has become ubiquitous in the environment. However, little information is available regarding its transgenerational effects. This study aimed to investigate the developmental toxicity of TPhP on F1 larvae offspring of adult male zebrafish exposed to various concentrations of TPhP for 28 or 60 days. The findings revealed significant morphological changes, alterations in locomotor behavior, variations in neurotransmitter, histopathological changes, oxidative stress levels, and disruption of Retinoic Acid (RA) signaling in the F1 larvae. After 28 and 60 days of TPhP exposure, the F1 larvae exhibited a myopia-like phenotype with pathological alterations in the lens and retina. The genes involved in the RA signaling pathway were down-regulated following parental TPhP exposure. Swimming speed and total distance of F1 larvae were significantly reduced by TPhP exposure, and long-term exposure to environmental levels of TPhP had more pronounced effects on locomotor behavior and neurotransmitter levels. In conclusion, TPhP induced histological and morphological alterations in the eyes of F1 larvae, leading to visual dysfunction, disruption of RA signaling and neurotransmitter systems, and ultimately resulting in neurobehavioral abnormalities. These findings highlight the importance of considering the impact of TPhP on the survival and population reproduction of wild larvae.

Developmental hazards of 2,2',4,4'-tetrabromodiphenyl ether induced endoplasmic reticulum stress on early life stages of zebrafish (Danio rerio).

Polybrominated diphenyl ether flame retardants are known to have adverse effects on the development of organisms. We investigated the molecular mechanisms associated with the developmental hazards of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in zebrafish, as well as the behavioral and morphological alterations involved, focusing on endoplasmic reticulum stress (ERS), oxidative stress, and apoptosis. Our study revealed behavioral alterations in zebrafish exposed to BDE-47, including impaired motor activity, reduced exploration, and abnormal swimming patterns. In addition, we observed malformations in craniofacial regions and other developmental abnormalities that may be associated with ERS-induced cellular dysfunction. BDE-47 exposure showed apparent changes in ERS, oxidative stress, and apoptosis biomarkers at different developmental stages in zebrafish through gene expression analysis and enzyme activity assays. The study indicated that exposure to BDE-47 results in ERS, as supported by the upregulation of ERS-related genes and increased activity of ERS markers. In addition, oxidative stress-related genes showed different expression patterns, suggesting that oxidative stress is involved in the BDE-47 toxic effects. Moreover, an assessment of apoptotic biomarkers revealed an imbalance in the expression levels of pro- and anti-apoptotic genes, suggesting that BDE-47 exposure activated the apoptotic pathway. These results highlight the complex interactions between ERS, oxidative stress, apoptosis, behavioral alterations, and morphological malformations following BDE-47 exposure in zebrafish. Understanding the mechanisms of toxicity of developmental hazards is essential to elucidate the toxicological effects of environmental contaminants. The knowledge can help develop strategies to mitigate their adverse effects on the health of ecosystems and humans.

Transgenerational effects of BDE-47 to zebrafish based on histomorphometry and toxicogenomic analyses.

Exposure to 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47) has been found to have an impact on reproductive output and endocrine function in female zebrafish (Danio rerio). However, the transgenerational effects of BDE-47 have not been fully explored in previous reports. In this study, female zebrafish were exposed to BDE-47 for three consecutive weeks. The oogenesis, sex hormones, reproductive histology, and transcriptional profiles of genes along the hypothalamus-pituitary-gonad (HPG) axis were assessed in the exposed-F0 generation. After mating with unexposed males, the transgenerational effects of BDE-47 were evaluated on the basis of histopathology, morphometry and toxicogenome of the unexposed F1 generations at the larval stage. Results indicated that exposure to BDE-47 impaired reproductive capacity, disrupted endocrine system in F0 zebrafish, and compromised craniofacial skeletons and vertebrae development in F1 generations. In addition, through the use of toxicogenomics approach, immune-responsive pathways were found to be significantly enriched, and the transcript expression profiling of immune-related DEGs (IRDs) were dramatically inhibited in F1 generations following maternal BDE-47 exposure, indicating its immunotoxicity to offspring larvae. These findings advance our understanding of the transgenerational toxicity of BDE-47 and advocate for a more comprehensive assessment of other PBDE congeners through histomorphometry and toxicogenomic approaches.

Neurodevelopmental toxicity of organophosphate flame retardant triphenyl phosphate (TPhP) on zebrafish (Danio rerio) at different life stages.

As a substitute for polybrominated diphenyl ethers (PBDEs), organophosphate flame retardant triphenyl phosphate (TPhP) is widely used in our daily products and diffusely exists in our living surroundings, but there is a paucity of information concerning its neurodevelopmental toxicity. Herein, we investigated the effects of TPhP exposure on developmental parameters, locomotor behavior, oxidative stress, apoptosis and transcriptional levels in zebrafish at different developmental stages, so as to explore the effects of TPhP exposure on zebrafish neural development and the underlying molecular mechanisms. TPhP concentration gradient exposure reduced the survival rate, hatchability, heart rate, body length and eye distance of zebrafish embryos/larvae, and caused malformations of zebrafish larvae. TPhP also leads to abnormal locomotor behaviors, such as reduced swimming distance and swimming speed, and impaired panic avoidance reflex to high light stimulation. TPhP caused ROS accumulation in 96 hpf larvae and induced Nrf2-antioxidant response in zebrafish. In addition, TPhP further activated mitochondrial signaling pathways, which affected apoptosis in the zebrafish eye region, resulting in visual impairment. Neurodevelopmental (mbpa, syn2a, foxo3a and pax6a), Retinoid acid metabolism (cyp26a1, raraa, rbp5, rdh1, crabp1a and rbp2a) and apoptosis-related genes (bcl2a, baxa and casp9) revealed the molecular mechanism of abnormal behavior and phenotypic symptoms, and also indicated that 96 hpf larvae are more sensitive than 7 dpf larvae. Thus, in the present study, we revealed the neurotoxic effects of TPhP at different early life stages in zebrafish, and zebrafish locomotor behavior impairments induced by TPhP exposure are attributed to co-regulation of visuomotor dysfunction and neuro-related genes. These results suggest that the safety of TPhP in organisms and even in humans needs to be further studied.