Developmental Toxicity Research Articles

Embryoid Body Test: A Simple and Reliable Alternative Developmental Toxicity Test

The increasing emphasis on animal welfare and ethics, as well as the considerable time and cost involved with animal testing, have prompted the replacement of many aspects of animal testing with alternative methods. In the area of developmental toxicity, the embryonic stem cell test (EST) has played a significant role. The EST evaluates toxicity using mouse embryonic stem cells and somatic cells and observes the changes in heartbeat after cardiac differentiation. Nevertheless, the EST is a relatively complex testing process, and an in vitro test requires a long duration. Several attempts have been made to develop a more straightforward testing method than the EST, with improved reproducibility and accuracy, leading to the development of the embryoid body test (EBT). Unlike the EST, which involves cardiac differentiation stages, the EBT verifies toxicity by measuring the changes in the area of the embryoid body. Despite its short testing period and simple procedure, the EBT offers high accuracy and reproducibility and is fully validated through two rounds of validation, making it ready for practical application. The EBT is expected to play a crucial role in the rapidly increasing demand for alternative methods to animal testing, particularly for screening early developmental toxicity.

Effects of Flurochloridone on the Developmental Toxicity in Zebrafish (Danio rerio) Embryo.

Flurochloridone (FLC) is a selective herbicide that can cause reproductive toxicity in male rats. However, limited information is available regarding the toxicity of FLC in the developmental stages of aquatic organisms. This study aimed to investigate the effects of FLC exposure during embryonic development and elucidate its potential mechanism of action. Zebrafish embryos were exposed to 6.25, 12.5, 25, and 50 μg/mL FLC for 4-144 hpf. The developmental status of embryos was recorded; the indicators of oxidative stress and embryonic apoptosis were determined. We found that FLC exposure caused severe embryonic malformations, such as pericardial edema, spinal curvature, and growth retardation, accompanied by a decreased hatching and survival rate. After exposure until 144 h postfertilization, the median lethal concentration (LC50) of FLC in zebrafish embryos was 36.9 μg/mL. Subsequently, FLC induced the accumulation of reactive oxygen species and malondialdehyde, enhanced the activity of superoxide dismutase, and activated the Keap1-Nrf2 signaling pathway. Further studies confirmed that FLC can induce apoptosis in zebrafish embryos through the activation of caspase. These results suggest that FLC induced developmental toxicity in zebrafish embryos, which provides new evidence regarding FLC toxicity in aquatic organisms and to assess human health risks.

3-Chloro-1,2-Propanediol Exposure Induces Cardiotoxicity and Behavioural Abnormalities in Zebrafish Embryos.

Numerous contemporary diseases are linked to food contamination. Pathogenic agents might stem from certain food ingredients or result from pollution stemming from food processing or packaging. One such contaminant is 3-Chloro-1,2-propanediol (3-MCPD), it has been previously reported to be produced during the preparation of chemical sauces, as well as during the heating of baked goods. Yet, uncertainty surrounds its potential to induce embryonic developmental toxicity. In this study, zebrafish were employed as the focal point to assess the impact of 3-MCPD on initial embryonic development, heart functionality, and behavior. The research unveiled that exposure of zebrafish embryos to 18, 36, and 54 mM 3-MCPD led to cardiac anomalies, including pericardial edema, reduced heart rate, and elongated SV-BA distance. Additionally, 3-MCPD exposure triggered aberrations in cardiac-related gene expression and an elevation in oxidative stress. Notably, behavioral changes were observed in 3-MCPD-exposed zebrafish embryos, while vascular development appeared unaffected. This study introduces a novel basis for comprehensive exploration of 3-MCPD toxicity.

Developmental Toxicity of Alkylated PAHs and Substituted Phenanthrenes: Structural Nuances Drive Diverse Toxicity and AHR activation

Polycyclic aromatic hydrocarbons (PAHs) are a diverse class of chemicals that occur in complex mixtures including parent and substituted PAHs. To understand the hazard posed by complex environmental PAH mixtures, we must first understand the structural drivers of activity and mode of action of individual PAHs. Understanding the toxicity of alkylated PAHs is important as they often occur in higher abundance in environmental matrices and can be more biologically active than their parent compounds. 104 alkylated PAHs were screened from 11 different parent compounds with emphasis on substituted phenanthrenes and their structurally dependent toxicity differences. Using a high-throughput early life stage zebrafish assay, embryos were exposed to concentrations between 0.1 to 100 μM and assessed for morphological and behavioral outcomes. The aryl hydrocarbon receptor (AHR) is often implicated in the toxicity of PAHs and the induction of cytochrome P4501A (cyp1a) is an excellent biomarker of Ahr activation. Embryos were evaluated for cyp1a induction using a fluorescence reporter line. Alkyl and polar phenanthrene derivatives were further assessed for spatial cyp1a expression and Ahr dependence of morphological effects. In the alkyl PAH screen 35 (33.7%) elicited a morphological or behavioral response and of those 23 (65%) also induced cyp1a. 31 (29.8%) of the chemicals only induced cyp1a. Toxicity varied substantially in response to substitution location, the amount of ring substitutions and alkyl chain length. Cyp1a induction varied by parent compound group and was a poor indicator of morphological or behavioral outcomes. Polar phenanthrenes were more biologically active than alkylated phenanthrene derivatives and their toxicity was not dependent upon the Ahr2, Ahr1a or Ahr1b when tested individually, despite cyp1a induction by 50% of polar phenanthrenes. Our results demonstrated that induction of cyp1a did not always correlate with PAH toxicity or Ahr dependence and that the type and location of phenanthrene substitution determined potency.

Covalent triazine frameworks as particle electrode for three-dimensional photoelectrocatalytic degradation of oxytetracycline: Synergy effects, pathway, and mechanism.

Photoelectrocatalysis has been widely employed for degrading antibiotics due to its high efficiency. However, the application is significantly impeded by the rapid recombination of photogenerated charge carriers and the limited surface areas of photoelectrodes. In the study, high crystallinity covalent triazine frameworks were fabricated at low temperature of 150°C and firstly used as particle photoelectrode in the three-dimensional photoelectrochemical reactor to degrade oxytetracycline (OTC). SEM, TEM, XRD, XPS, and FT-IR confirmed the successful synthesis of high crystallinity covalent triazine frameworks. Compared to CTF-120 (71.2%) and CTF-180 (46.9%), CTF-150 exhibited excellent OTC removal. Electrochemical impedance, UV-vis absorption spectra, and Mott-Schottky tests showed that CTF-150 demonstrated more wide light absorption range of 501nm and narrow bandgap of 2.52eV, and smaller Rct value under illumination, in comparing to CTF-120 and CTF-180. When the initial concentration of OTC was 50mgL-1, the 86.2% of OTC removal and 62.7% of mineralization were obtained under light irradiation (λ>420nm), current of 10mA, pH of 6.4, electrolyte of 0.1M Na2SO4. The synergy effect between photocatalytic and electrocatalytic processes of CTF-150 not only enhanced by 38.5% current efficiency but also reduced energy consumption to 1.90 kWh m-3. CTF-150 had a wide range of acid-base application and displayed resistance on coexisting ions. Electron spin resonance detection, quenching experiments, and probe experiments illustrated that h+, •O2-, 1O2, and •OH contributed to the degradation of OTC and the generation pathways of •O2-, 1O2, and •OH were verified. Moreover, •O2-, 1O2, and h+ were the main reactive species responsible for OTC removal, while 1O2 was for OTC mineralization. Based on high-performance liquid chromatography-tandem mass spectrometry detection, OTC with benzene ring was decomposed to opening ring products. The acute toxicity, developmental toxicity, bioaccumulation factor and mutagenicity of OTC and its intermediates using T.E.S.T. showed the toxicity of 82.35% degradation products decreased.

Early developmental effects of propofol exposure in different stages of zebrafish embryos.

The mechanism of action of propofol, a common intravenous anaesthetic, in early life stages is not well understood with contradictory studies showing neurotoxic and neurogenic effects in the developing brain. Zebrafish early life stages have been established as an alternative model for animal experimentation with propofol toxicological effects reported following chronic exposure. Yet, the acute exposure to other anaesthetics has been shown to induce early life stage-dependent toxicological outcomes. Therefore, the present study aimed to evaluate the teratogenic effects of propofol at the 256-cell, 50% epiboly and 1-4 somite stages following a 20min exposure. Embryos were exposed after primally assessment of propofol acute toxicity (24h-LC50=9.82μgmL-1) and absorption at different developmental stages by chromatography. Embryos (2hours post-fertilization, hpf) were treated with an anaesthetic and toxicological concentration of propofol (2.5 and 10μgmL-1, respectively) for 20-min. Mortality and developmental toxicity were then evaluated until 144 hpf, when the behaviour and oxidative-stress-related biomarkers were assessed. Exposure at the 256-cell stage resulted in a concentration-dependent increased number of abnormalities in head, fins and tail and a decreased body length as well as in changes in ATPase activity for the lowest concentration. On the other hand, exposure at later stages resulted in a decreased survival while no significant malformations were detected. Yet, exposure during the 50% epiboly stage resulted in the increase of ROS levels as well as glutathione (GST and GSSG) levels while exposure at 1-4 somite stage resulted in increased DNA damage and ATPase alterations. The behaviour of zebrafish was similar among treatments. Overall, these findings show highlight the stage-dependent teratogenic potential of short propofol exposures during zebrafish early development. The alterations observed may be linked to the activation of the zygotic transcription in embryos, requiring further studies to delve into the molecular changes underlying the observed effects.

Importance of tailored non-clinical safety testing of novel antimalarial drugs: Industry best-practice

Malaria is an acute, debilitating parasitic illness. There were 249 million cases of malaria in 2022, resulting in 608,000 deaths globally, 76% of which were children ≤5 years. The unique nature of this disease (recurrences leading to re-treatments and numerous organ systems affected), specific clinical treatment regimens, poor compliance, and diversity of affected populations (predominantly pediatrics, women of childbearing potential, pregnant and lactating women), often makes standard testing approaches inadequate, and tailor-made safety assessments are more appropriate.We provide best practice recommendations based on company experience for the non-clinical safety assessment of antimalarial drugs, with a focus on small molecules since they represent the majority of drug candidates for this illness. We focus on specific testing considerations for repeat dose toxicity studies, including combination toxicity assessments, since new drug treatment regimens typically foresee short treatment durations to improve compliance (i.e., 1 day) with combinations of compounds to improve efficacy and limit potential resistance. Due to the target population, the timing of reproductive, developmental, and juvenile toxicity studies may be earlier than general testing roadmaps for other small molecule drugs.In conclusion, key recommendations presented should enable a more effective and efficient development path whilst protecting clinical trial participants and patients.

Flavouring group evaluation 420 (FGE.420): Hesperetin dihydrochalcone.

The EFSA Panel on Food Additives and Flavourings (FAF) was requested to evaluate the safety of hesperetin dihydrochalcone [FL-no: 16.137] as a new flavouring substance, in accordance with Regulation (EC) No 1331/2008. The substance is structurally related to the group of flavonoids evaluated in FGE.32 and is the aglycone of neohesperidine dihydrochalcone. Based on the data provided for [FL-no: 16.137], the Panel considered that a read-across between hesperetin dihydrochalcone and the substances in FGE.32 is not needed. Nevertheless, the flavonoids evaluated in FGE.32 were considered in a cumulative exposure assessment. The information provided on the manufacturing process, the composition and the stability of [FL-no: 16.137] was considered sufficient. The Panel concluded that there is no concern with respect to genotoxicity. No absorption, distribution, metabolism and excretion (ADME) studies on [FL-no: 16.137] were provided, but studies investigating the ADME of neohesperidine dihydrochalcone were submitted. The Panel noted that [FL-no: 16.137] has the same fate in the organism, as that of neohesperidine dihydrochalcone and considered that [FL-no: 16.137] can be anticipated to be metabolised to innocuous products only. In a prenatal developmental toxicity study, no maternal or foetal toxicity was observed. In a 90-day toxicity study, indications were obtained that the substance affects thyroid hormone levels at all doses tested (100-1000 mg/kg bw per day). Since these changes were not accompanied by apical findings indicative of hypothyroidism, the Panel considered these hormonal effects as not adverse. Using 1000 mg/kg bodyweight (bw) per day as reference point, adequate margins of exposure were calculated for adults and children, when considering the chronic added portions exposure technique (APET) dietary exposure estimates. Cumulative chronic exposure estimates to [FL-no: 16.137] and the four structurally related substances evaluated in FGE.32 do not raise a safety concern. The use of [FL-no: 16.137] as food flavouring, under the proposed conditions of use, does not raise a safety concern.

Developmental toxicity and biochemical and biomarker in the zebrafish (Danio rerio) embryo exposed to biosynthesized cadmium oxide nanoparticles

Cadmium oxide nanoparticles (CdO-NPs) play an important role in health applications due to their antibacterial properties. However, ecotoxicological investigations of these NPs and their adverse effects on aquatic organisms are necessary to protect the environment. Zebrafish is widely used as a model organism to explore toxic effects at multiple levels of integration. Hence, the objective of this work was to pursue possible harmful impacts of CdO -NPs that have been produced through biosynthesis, utilizing extract from the lily plant Gloriosa superba leaves, on the growth and biochemical changes in zebrafish (Danio rerio) embryos and larvae. UV, SEM, TEM, FTIR, EDAX, DLS, and ZETA-potential techniques were employed to examine the structure and morphology of the biosynthesized CdO-NPs. The identification of bioactive chemicals from the leaf extract of G. superba was conducted using GC-MS. To study the in vivo toxicity of CdO-NPs, zebrafish embryos and larvae were treated with two different concentrations of G. superba leave extract (0.5 and 1.0 mg/mL) at 96 hours after fertilization (hpf). Bended tail, pericardial edema, shortened yolk sac extension, scoliosis, and damaged eyes were observed in the CdO-NPs treated groups. In addition, there was a considerable decrease in the levels of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferases (GST), and lipid peroxidation (LPO). The CdO-NPs treated groups showed significant alterations in biochemical markers, including protein levels, glucose levels, and acetylcholinesterase (AChE) activity. Overall, our findings indicated that CdO-NPs induced a dose-dependent toxicity in zebrafish embryos. The investigated parameters serve as reliable biomarkers for the surveillance of CdO-NPs in aquatic ecosystems and their impact on living animals.

The effects of disturbance on hypothalamus-pituitary-thyroid axis in zebrafish larvae after exposure to polyvinyl alcohol

In recent years, considerable concerns have been raised regarding environmental pollution caused by water-soluble polymers (WSPs). Polyvinyl alcohol (PVA), used in the textile industry and in the manufacture of medical consumables, is one type of WSPs. After use, PVA is discharged and enters aquatic ecosystems, but most of it cannot be completely biodegraded in the environment. In this study, we investigated the effects of PVA on developmental toxicity and thyroid endocrine disruption using a zebrafish (Danio rerio) model. We treated zebrafish embryos with 10 g/L and 5 mg/L PVA for 96 h and found that the proportion of coagulated embryos significantly increased, resulting in a remarkable decrease in hatching rate and larval survival. The body length of zebrafish larvae in the exposed group was remarkably shorter than that of the control group (Control: 3.64 ± 0.03 mm vs. 10 g/L PVA: 3.46 ± 0.03 mm; p=0.001). Compared to the control group, the levels of T3 and T4 in embryos of the exposed group were significantly lower, while thyroid stimulating hormone (TSH) levels were significantly increased. Notable up-regulation of trh, tshβ, and tshr genes, as well as down-regulation of trα , tg, ttr, dio1, and dio2 genes, were observed in embryos of the exposed group. Collectively, these findings suggest that PVA negatively influences the development and function of the thyroid gland during zebrafish embryogenesis. These effects may be partly attributed to the disruption of hypothalamic-pituitary-thyroid (HPT) axis regulation. Therefore, raising awareness about the possible thyroid toxicity associated with PVA is crucial.

Insights into the relationship between regulation of oxygen vacancy and singlet oxygen generation in peracetic acid activation

Peracetic acid (PAA) has shown good potential in advanced oxidation techniques, but the mechanism regulating the generation of non-radical species in peracetic acid has not been clarified. Herein, Ov-Co3O4/C-x was prepared by pyrolysis of ZIF-L precursors at different temperatures to achieve the regulation of oxygen vacancy concentration and used for the degradation of sulfamethazine (SMT) by activated PAA. When x = 350 °C, the prepared Ov-Co3O4/C-350 with the highest oxygen vacancy content had the highest SMT removal efficiency and the highest rate constant(kobs), which degraded SMT by 99.6 % within 30 min. The role of oxygen vacancies(OVs) on the surface of Ov-Co3O4/C-350 was investigated using quenching experiments, Electron Paramagnetic Resonance (EPR) and X-ray Photoelectron Spectroscopy (XPS) techniques. The results showed that oxygen vacancy on the metal oxide surface can be converted into more reactive oxygen(O*), and surface OVs of Ov-Co3O4/C-350 enable efficient capture of PAA, thus generating 1O2 and R-O•. The higher the content of oxygen vacancies is, the more 1O2 is produced, while concentration of R-O• was not significantly correlated with oxygen vacancy content. Furthermore, the degradation pathway of SMT was predicted through density functional theory (DFT) calculations and identifications of intermediates, indicating that electron-rich sites such as aromatic rings and S-N bonds in the SMT molecule are more easily oxidized by reactive species. Besides, due to the low biotoxicity of the degradation products of the Ov-Co3O4/C-350/PAA system, the reaction can effectively reduce the biotoxicity and developmental toxicity. This study provides a controllable surface property strategy for a new idea in PAA-based AOP.

Exploring the potential of curcumin-loaded PLGA nanoparticles for angiogenesis and antioxidant proficiency in zebrafish embryo (Danio rerio)

BackgroundCurcumin is an age old traditional medicine. Although curcumin has several advantages, its water solubility and bioavailability limit its use as a natural therapeutic agent. Polymeric nano curcumin could be an excellent option to overcome these challenges to augment its therapeutic efficacy. This work aimed to synthesize curcumin-loaded PLGA nanoparticles and assess their angiogenic and antioxidant potential in the zebrafish model.ResultsThe double emulsion solvent evaporation process was employed to make curcumin-loaded PLGA nanoparticles. Curcumin showed ~ 28.23 (± 2.49) encapsulation efficacy with an average diameter of PLGA nanoparticles 168.5 (± 2.5) nm and curcumin nanoparticles about 281.6 (± 17.2) nm, respectively. The curcumin nanoparticles showed no developmental toxicity to the zebrafish embryos while reduced toxicity compared to the native curcumin. Further, the curcumin nanoparticles reduced the generation of reactive oxygen species and improved angiogenesis in the model system. All these results confirmed that the nanoparticle has had higher bio-efficacy than that of native curcumin.ConclusionThis study shows that PLGA curcumin nanoparticles hold an excellent therapeutic promise for wound healing, tissue regeneration and other biomedical applications where angiogenesis and ROS play critical role.

A Combined Fertility and Developmental Toxicity Study with an Antisense Oligonucleotide Targeting Murine Apolipoprotein C-III mRNA in Mice.

Here, we present the reproductive toxicology profile of ISIS 838707, a GalNAc-conjugated antisense oligonucleotide (ASO) targeting mouse Apolipoprotein C-III (ApoC-III) mRNA. ISIS 838707 was subcutaneously administered during the premating, mating, and gestation periods to male and female mice at 0, 5, 10, and 20 mg/kg/week. Key focus areas included fertility, reproductive cell functions, estrus cycle, tubal transport, implantation, embryo development stages, and teratogenic potential. We also investigated the toxicokinetics and target mRNA knockdown effects. The treatment was well-tolerated at all dose levels, with no overt toxicity. Treatment led to decreased total cholesterol and/or triglyceride levels at doses ≥5 mg/kg/week, concordant with effective knockdown of ApoC-III mRNA (>85% reduction at all dose levels). Toxicokinetic analysis revealed predominant distribution to the liver of parental animals and minimally to the placenta, with no detectable transfer to fetal liver. Despite these pharmacological effects, there were no discernible adverse impacts on developmental and reproductive functions. These findings suggest that ISIS 838707, while effective in modulating ApoC-III mRNA and lipid profiles, does not adversely impact on reproductive and developmental functions in mice. The study contributes insights into the safety profile of ASOs and reduction of ApoC-III expression, particularly in the context of reproductive and developmental health.

Singlet oxygen and hydroxyl radical in the transformation of acetaminophen in surface water: The mechanism on the degradation pathways based on DFT calculations

Pharmaceuticals compounds are continuously released into the aquatic environment due to the widely used therapeutically in livestock and humans. These pharmaceuticals and their degradation products accumulate in fish and have potential impacts on human and ecosystems. In this study, acetaminophen (ACE), a pharmaceutical widely used in COVID-19 epidemic, was selected as the research object to study its microscopic transformation mechanism and ecotoxicity using density functional theory and computational toxicology. The research demonstrated that ACE could be degraded by 1O2 in three pathways (2,2-cycloaddition, Ene reaction and 2,4-cycloaddition). The 2,4-cycloaddition mechanism at para-site plays a dominant role in the 1O2 oxidation of ACE. The total rate constant of ACE for •OH-initiated reaction was 1.78×109 M−1s−1 at 298 K. Furthermore, the half-life of ACE was determined as 143 and 3.5 days at ambient temperatures, given the concentration of •OH and 1O2 as 10−16.5 and 10−13 M, respectively. Although the aquatic toxicity of most degradation by-products appears to be not harmful level, some products were identified as very toxic and have developmental toxicity, especially hydroquinone and 1,4-benzoquinone. The systematic mechanism study provides a pathway to understand the transformation and environmental impact of pharmaceutical pollutants containing paracetamol in natural water environment at the molecular level.

Behavioural, Teratogenic and Genotoxic Effects of Antibacterial Compounds, Triclocarban and Triclosan, in Hydra vulgaris.

Triclocarban (TCC) and triclosan (TCS) are antibacterial compounds used in household, veterinary, industrial and personal care products, which are known to be environmental pollutants and also toxic to organisms. The toxicological effects of these antibacterial chemicals on higher organisms have been studied in detail. But in lower invertebrates like hydra, it is still rare and yet to be explored. In this study, the toxicological effects of these two antibacterial compounds in Hydra vulgaris was performed to clearly understand the organismal, developmental, molecular and behavioural changes. Both TCC and TCS are toxic with respective LC50 values of 0.09 and 0.25 mg/L, whereas TCC is comparatively more toxic than TCS. The structural damage of battery cell complexes (BCCs) on the tentacles was observed and ultimately made prey capturing difficult. It was evident that TCC and TCS exposure caused developmental toxicity by affecting reproduction and regeneration in H. vulgaris at higher sublethal doses (0.045 and 0.125 mg/L, respectively). TCC and TCS also caused DNA damage resulting in apoptosis. This study further reveals that these two antibacterial compounds are teratogenic and genotoxic in the organisms.

Carbon dots induce endoplasmic reticulum stress-mediated lipid dysregulation and embryonic developmental toxicity in zebrafish

Carbon dots (CDs) are widely utilized due to their exceptional physical and chemical properties. Nevertheless, there is a paucity of research examining the potential toxicity of carbon dots to human health, particularly with regard to developmental toxicity. The present study demonstrated that exposure to CDs resulted in increased mortality and malformations in zebrafish embryos. Further bioinformatics analyses indicated that CDs-induced lipid metabolism disorders may represent a significant pathway for developmental toxicity in zebrafish embryos. This can result in aberrant expression of genes involved in lipid metabolism, which ultimately leads to endoplasmic reticulum stress (ERS)-induced accumulation of excess lipids in the body. It can therefore be surmised that exposure to CDs in early life ultimately leads to developmental toxicity by inducing ERS-induced lipid metabolism disorders. The findings of this study suggest that there is a risk of long-term exposure to CDs from early life, and provide a theoretical basis and data support for the prevention of potential hazards of CDs.

Enhancing reliability of embryo-fetal developmental toxicity studies: A proposed design of replicate studies

BackgroundThis report addresses the reliability of results from rat Embryo-Fetal Developmental Toxicity (EFDT) studies. Recent literature discusses the roles of reproducibility, replicability, and other influences on scientific reliability. Reproducibility is a re-analysis of the original data, while replicability addresses the same question with a separate study of some type. Concordance of rat and rabbit studies has been addressed previously, but replication of single-species EFDT studies was not found in the literature. A modest modification of the rat study is therefore proposed to assess replicability and possibly enhance reliability. MethodsRegulatory guidelines were consulted and relevant literature was identified through online searches. ResultsEach replicate EFDT (r-EFDT) study in rats would consist of half the mated females of the definitive study. Studies would start at the same or different times in one testing facility. Separate shipments of animals (non-littermates) are required. All other procedures would be protocol-driven. The micro- and macro-environments of the animals would be held as constant as possible. Justification, design options, and interpretation methods are discussed. ConclusionBesides adding reliability, other benefits include reduced animal usage, and potentially reduced cost and time to final reports. By reducing the need for repeated studies due to questionable results, this modified study is viewed as a more efficient use of costly resources. The r-EFDT study design could easily be adapted to assess replicability of rabbit EFDT and some general toxicity studies. Future replicate studies are needed to critically evaluate replicability and the overall impact on study reliability.

Development of hybrid models by the integration of the read-across hypothesis with the QSAR framework for the assessment of developmental and reproductive toxicity (DART) tested according to OECD TG 414

The governing laws mandate animal testing guidelines (TG) to assess the developmental and reproductive toxicity (DART) potential of new and current chemical compounds for the categorization, hazard identification, and labeling. In silico modeling has evolved as a promising, economical, and animal-friendly technique for assessing a chemical's potential for DART testing. The complexity of the endpoint has presented a problem for Quantitative Structure-Activity Relationship (QSAR) model developers as various facets of the chemical have to be appropriately analyzed to predict the DART. For the next-generation risk assessment (NGRA) studies, researchers and governing bodies are exploring various new approach methodologies (NAMs) integrated to address complex endpoints like repeated dose toxicity and DART. We have developed four hybrid computational models for DART studies of rodents and rabbits for their adult and fetal life stages separately. The hybrid models were created by integrating QSAR features with similarities-derived features (obtained from read-across hypotheses). This analysis has identified that this integrated method gives a better statistical quality compared to the traditional QSAR models, and the predictivity and transferability of the model are also enhanced in this new approach.

Protective effect of a novel furan hybrid chalcone against bisphenol A-induced craniofacial developmental toxicity in zebrafish embryos

Bisphenol A (BPA), a pervasive endocrine disruptor, is known to cause significant developmental toxicity, particularly affecting craniofacial structures through oxidative stress and apoptosis. A novel furan hybrid chalcone derivative, 3-(2-hydroxy-5-nitrophenyl)-1-(5-methylfuran-2-yl)prop-2-en-1-one (DK04), specifically with a hydroxyl group for its antioxidant properties and a nitro group for enhanced electron-withdrawing ability, was evaluated for its potential to mitigate these toxic effects. Zebrafish embryos were exposed to BPA and co-treated with various concentrations of DK04. Our results demonstrated that DK04 significantly reduced reactive oxygen species (ROS) generation and lipid peroxidation, increased antioxidant enzyme activities (SOD and CAT), and restored the balance between pro-apoptotic (p53) and anti-apoptotic (bcl2) genes. Furthermore, DK04 treatment improved bone mineralization and chondrogenesis by reversing BPA-induced disruptions in osteogenic markers (runx2, sox9a, bmp6, and mmp13a). The locomotion impairments observed in BPA-exposed embryos were also ameliorated by DK04, indicating its potential neuroprotective effects. These findings suggest that DK04 offers a multifaceted approach to counteract BPA toxicity, making it a promising candidate for therapeutic intervention. This research underscores the importance of developing prophylactic compounds to safeguard health against environmental toxicants like BPA. Future studies should focus on long-term safety and efficacy in mammalian models and explore synergistic effects with other protective agents to broaden the applications of DK04 and contribute to public health benefits.

Developmental toxicity and mechanism of dibutyl phthalate on the development of subintestinal vessels in zebrafish

Background: The dibutyl phthalate (DBP) is a member of the phthalate family and is widely used as a plasticizer in daily life and production. However, the influence of DBP on the vascular developmental remains unclear. Methods: In this study, we used zebrafish as a model organism to investigate the effects of DBP on vascular development in vivo. Death curves of zebrafish at different concentrations of DBP exposure and different times incubation were made firstly. Zebrafish embryos after fertilization for 5.5 h were exposed to different concentrations of DBP solution (0, 0.4, 0.8, 1.2 mg/L), the body length, yolk sac absorption area, mortality and heart rate of zebrafish were measured, and the number and area of sprouting of ventral vessels were quantified by transgenic fish system. Reactive oxygen species (ROS) in zebrafish embryos were observed by DCFH-DA staining. Super oxide dimutese (SOD) and catalase (CAT) were determined with ELISA kits. Results: We found that DBP increased the oxidative stress level of zebrafish exposed to DBP, and the genes related to vascular development also increased. Meanwhile, the activities of SOD and CAT were greatly decreased after DBP exposure. In the rescue experiment, we found that the antioxidant astaxanthin and the small molecule VEGF inhibitor ZM-306,416 can reverse the vascular dysplasia caused by DBP. Conclusions: DBP induced vascular developmental toxicity by enhancing oxidative stress levels, activating HIF pathway, and interfering with the expression of vascular development-related pathways in zebrafish, results in the abnormal development of the subintestinal vessels in zebrafish.