Current Research in Toxicology最新文献

{"title":"Protective effects of amphetamine and methylphenidate against dopaminergic neurotoxicants in SH-SY5Y cells","authors":"Patrícia Carneiro ,&nbsp;Mariana Ferreira ,&nbsp;Vera Marisa Costa ,&nbsp;Félix Carvalho ,&nbsp;João Paulo Capela","doi":"10.1016/j.crtox.2024.100165","DOIUrl":"https://doi.org/10.1016/j.crtox.2024.100165","url":null,"abstract":"<div><p>Full treatment of the second most common neurodegenerative disorder, Parkinson’s disease (PD), is still considered an unmet need. As the psychostimulants, amphetamine (AMPH) and methylphenidate (MPH), were shown to be neuroprotective against stroke and other neuronal injury diseases, this study aimed to evaluate their neuroprotective potential against two dopaminergic neurotoxicants, 6-hydroxydopamine (6-OHDA) and paraquat (PQ), in differentiated human dopaminergic SH-SY5Y cells.</p><p>Neither cytotoxicity nor mitochondrial membrane potential changes were seen following a 24-hour exposure to either therapeutic concentration of AMPH or MPH (0.001–10 μM). On the other hand, a 24-hour exposure to 6-OHDA (31.25–500 μM) or PQ (100–5000 μM) induced concentration-dependent mitochondrial dysfunction, assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and lysosomal damage, evaluated by the neutral red uptake assay. The lethal concentrations 25 and 50 retrieved from the concentration-toxicity curves in the MTT assay were 99.9 µM and 133.6 µM for 6-OHDA, or 422 µM and 585.8 µM for PQ. Both toxicants caused mitochondrial membrane potential depolarization, but only 6-OHDA increased reactive oxygen species (ROS). Most importantly, PQ-induced toxicity was partially prevented by 1 μM of AMPH or MPH. Nonetheless, neither AMPH nor MPH could prevent 6-OHDA toxicity in this experimental model.</p><p>According to these findings, AMPH and MPH may provide some neuroprotection against PQ-induced neurotoxicity, but further investigation is required to determine the exact mechanism underlying this protection.</p></div>","PeriodicalId":11236,"journal":{"name":"Current Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666027X24000185/pdfft?md5=e8feb0868f6d3c35be317d1482d07e68&pid=1-s2.0-S2666027X24000185-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140209355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating open access new approach methods (NAM) to assess biological points of departure: A case study with 4 neurotoxic pesticides","authors":"Marilyn H. Silva","doi":"10.1016/j.crtox.2024.100156","DOIUrl":"10.1016/j.crtox.2024.100156","url":null,"abstract":"<div><p>Open access new approach methods (NAM) in the US EPA ToxCast program and NTP Integrated Chemical Environment (ICE) were used to investigate activities of four neurotoxic pesticides: endosulfan, fipronil, propyzamide and carbaryl. Concordance of <em>in vivo</em> regulatory points of departure (POD) adjusted for interspecies extrapolation (AdjPOD) to modelled human Administered Equivalent Dose (AED_Human) was assessed using 3-compartment or Adult/Fetal PBTK <em>in vitro</em> to <em>in vivo</em> extrapolation. Model inputs were from Tier 1 (High throughput transcriptomics: HTTr, high throughput phenotypic profiling: HTPP) and Tier 2 (single target: ToxCast) assays. HTTr identified gene expression signatures associated with potential neurotoxicity for endosulfan, propyzamide and carbaryl in non-neuronal MCF-7 and HepaRG cells. The HTPP assay in U-2 OS cells detected potent effects on DNA endpoints for endosulfan and carbaryl, and mitochondria with fipronil (propyzamide was inactive). The most potent ToxCast assays were concordant with specific components of each chemical mode of action (MOA). Predictive adult IVIVE models produced fold differences (FD) &lt; 10 between the AED_Human and the measured <em>in vivo</em> AdjPOD. The 3-compartment model was concordant (i.e., smallest FD) for endosulfan, fipronil and carbaryl, and PBTK was concordant for propyzamide. The most potent AED_Human predictions for each chemical showed HTTr, HTPP and ToxCast were mainly concordant with <em>in vivo</em> AdjPODs but assays were less concordant with MOAs. This was likely due to the cell types used for testing and/or lack of metabolic capabilities and pathways available <em>in vivo</em>. The Fetal PBTK model had larger FDs than adult models and was less predictive overall.</p></div>","PeriodicalId":11236,"journal":{"name":"Current Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666027X24000094/pdfft?md5=31c931d7a1bcb728b57343cdc6471724&pid=1-s2.0-S2666027X24000094-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139873916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Alzheimer's disease: In silico study of rosemary diterpenes activities","authors":"Zakariae Abbaoui ,&nbsp;Mohammed Merzouki ,&nbsp;Imane Oualdi ,&nbsp;Abdelhamid Bitari ,&nbsp;Abdelouhed Oussaid ,&nbsp;Allal Challioui ,&nbsp;Rachid Touzani ,&nbsp;Belkheir Hammouti ,&nbsp;Wilson Agerico Diño","doi":"10.1016/j.crtox.2024.100159","DOIUrl":"https://doi.org/10.1016/j.crtox.2024.100159","url":null,"abstract":"<div><p>The global surge in Alzheimer's disease poses a significant public health concern. In response, we study the efficacy of carnosic acid and related abietane-type diterpenes extracted from rosemary as acetylcholinesterase (AChE) inhibitors. Our analyses, using in silico techniques, encompassed all the compounds within this extract. Through molecular docking, we explored how these compounds interact with the active site of the AChE protein. The docking scores, ranging from −5.560 Kcal/mol to −7.270 Kcal/mol, indicate robust binding affinities. Assessment of the ADME/T (Adsorption, Distribution, Metabolism, Excretion, and Toxicity) properties and pharmacokinetics of these compounds reveal favorable profiles for all the tested substances. These encouraging results suggest the potential of these compounds as candidates for further development to prevent and/or treat Alzheimer's disease. Among these compounds, we find rosmanol as the most likely candidate for further research and clinical trials to validate their efficacy.</p></div>","PeriodicalId":11236,"journal":{"name":"Current Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666027X24000124/pdfft?md5=a81cfe8a39de5357800a7a007141150a&pid=1-s2.0-S2666027X24000124-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140030287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Subcellular expression of CYP2E1 in HepG2 cells impacts response to free oleic and palmitic acid","authors":"","doi":"10.1016/j.crtox.2024.100195","DOIUrl":"10.1016/j.crtox.2024.100195","url":null,"abstract":"<div><h3>Aims</h3><div>Cytochrome P450 2E1 (CYP2E1) is a mammalian monooxygenase expressed at high levels in the liver that metabolizes low molecular weight pollutants and drugs, as well as endogenous fatty acids and ketones. Although CYP2E1 has been mainly studied in the endoplasmic reticulum (ER, microsomal fraction), it also localizes in significant amounts to the mitochondria, where it has been far less studied. We investigated the effects of CYP2E1 expression in mitochondria, endoplasmic reticulum, or both organelles in transgenic HepG2 cells exposed to free oleic and palmitic acid, including effects on cytotoxicity, lipid storage, respiration, and gene expression.</div></div><div><h3>Results</h3><div>We found that HepG2 cells expressing CYP2E1 in both the ER and mitochondria have exacerbated levels of palmitic acid cytotoxicity and inhibited respiration. CYP2E1 expression did not impact lipid accumulation from fatty acid exposures, but mitochondrial CYP2E1 expression promoted lipid droplet depletion during serum starvation. In contrast to HepG2 cells, differentiated HepaRG cells express abundant CYP2E1, but they are not sensitive to palmitic acid cytotoxicity. Oleic acid exposure prompted less cytotoxicity, and CYP2E1 expression in the ER prevented an oleic-acid-induced increase in respiration. HepG2 cells exposed to mixtures of palmitic and oleic acid are protected from palmitic acid cytotoxicity. Additionally, we identified that CYP2E1 was decreased at the gene and protein level in hepatocellular carcinoma. Moreover, patients with tumors that had higher CYP2E1 expression had a better prognosis compared to patients with lower CYP2E1 expression.</div></div><div><h3>Innovation</h3><div>This study has demonstrated that transgenic CYP2E1 subcellular localization plays an important role in sensitivity to cytotoxicity, lipid storage, and respiration in the hepatoma cell line HepG2 exposed to palmitic and oleic acid. HepaRG cells, in contrast, were insensitive to palmitic acid. This work demonstrates the clear importance of CYP2E1 in dictating lipotoxicity and differential roles for the mitochondrial and ER forms of the enzyme. Additionally, our data supports a potentially unique role for CYP2E1 in cancer cells.</div></div><div><h3>Conclusion</h3><div>There lies a role for CYP2E1 in altering lipotoxicity, and since CYP2E1 is known to be upregulated in both liver disease and hepatocellular carcinoma, it is important to better define how the role of CYP2E1 changes during disease progression.</div></div>","PeriodicalId":11236,"journal":{"name":"Current Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142423220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ethylene dimethanesulfonate effects on gene promoter activities related to the endocrine function of immortalized Leydig cell lines R2C and MA-10","authors":"Jorge W.F. de Barros ,&nbsp;Kenley Joule Pierre ,&nbsp;Wilma De G. Kempinas ,&nbsp;Jacques J. Tremblay","doi":"10.1016/j.crtox.2023.100147","DOIUrl":"https://doi.org/10.1016/j.crtox.2023.100147","url":null,"abstract":"<div><p>Ethylene dimethanesulfonate (EDS) is a molecule with known selective cytotoxicity on adult Leydig cells. A single intraperitoneal injection in rats but not mice, leads to male androgen deprivation and infertility. <em>In vitro</em> studies using rat and mouse immortalized Leydig cell lines, showed similar effects of cell death promoted by EDS in rat cells as seen <em>in vivo</em>, and suggest that EDS affects gene transcription, which could firstly compromise steroidogenesis before the apoptosis process. Using gene reporter assay, this study aimed to investigate EDS effects on the promoter activity of genes important for endocrine function (<em>Star</em>, <em>Insl3</em>) and response to toxic agents (<em>Gsta3</em>) in immortalized Leydig cell lines (rat R2C and mouse MA-10 cells), as well as identify possible EDS-responsive elements in the <em>Star</em> gene promoter. EDS exposure of R2C and MA-10 Leydig cells increased <em>Gsta3</em> promoter activity after 4 h of treatment and decreased <em>Insl3</em> promoter activity only in R2C cells after 24 h of treatment. EDS also decreased <em>Star</em> promoter activity in both Leydig cell lines. Using R2C cells, the EDS-responsive region in the <em>Star</em> promoter was located between −400 and −195 bp. This suggests that this region and the associated transcription factors, which include MEF2, might be targeted by EDS. Additional somatic gonadal cell lines expressing <em>Star</em> were used and EDS did not affect <em>Star</em> promoter activity in DC3 granulosa cells while <em>Star</em> promoter activity was increased in MSC-1 Sertoli cells after 24 h of treatment. This study contributes to the knowledge regarding the mechanism of EDS action in Leydig cells, and in other gonadal cell lineages, and brings new light regarding the rats and mice differential susceptibility to EDS effects, in addition to providing new avenues for experimental approaches to better understand Leydig cell function and dynamics in different rodent species.</p></div>","PeriodicalId":11236,"journal":{"name":"Current Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666027X23000452/pdfft?md5=7638e3700b61387d77ad30d1e6ae81c8&pid=1-s2.0-S2666027X23000452-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139108115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acceleration of benzo(a)pyrene-induced colon carcinogenesis by Western diet in a rat model of colon cancer","authors":"Kelly L. Harris ,&nbsp;Kenneth J. Harris ,&nbsp;Leah D. Banks ,&nbsp;Samuel E. Adunyah,&nbsp;Aramandla Ramesh","doi":"10.1016/j.crtox.2024.100162","DOIUrl":"https://doi.org/10.1016/j.crtox.2024.100162","url":null,"abstract":"<div><p>Colorectal cancer (CRC) is the third leading cause of cancer-related mortalities in the USA and around 52,550 people were expected to die from this disease by December 2023. The objective of this study was to investigate the effect of diet type on benzo(a)pyrene [B(a)P]-induced colon cancer in an adult male rat model, the Polyposis In the Rat Colon (PIRC) kindred type. Groups of PIRC rats (n = 10) were fed with AIN-76A regular diet (RD) or Western diet (WD) and received 25, 50 and 100 µg B(a)P/kg body wt. via oral gavage for 60 days. Rats fed diets alone, but no B(a)P, served as controls. After exposure, rats were euthanized; colon and liver samples were analyzed for activation of drug metabolizing enzymes (DMEs) CYP1A1, CYP1B1, SULT and GST. Plasma and tissue samples were analyzed by reverse phase-HPLC for B(a)P metabolites. In addition to these studies, DNA isolated from colon and liver tissues was analyzed for B(a)P-induced DNA adducts by the ³²P-postlabeling method using a thin-layer chromatography system. Western diet consumption resulted in a marked increase in DME expression and B(a)P metabolite concentrations in rats that were administered 100 µg/kg B(a)P + WD (p &lt; 0.05) compared to other treatment groups. Our findings demonstrate that WD accelerates the development of colon tumors induced by B(a)P through enhanced biotransformation, and the products of this process (metabolites) were found to bind with DNA and form B(a)P-DNA adducts, which may have given rise to colon polyps characterized by gain in tumor number, sizes, and dysplasia.</p></div>","PeriodicalId":11236,"journal":{"name":"Current Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666027X2400015X/pdfft?md5=fa6e9e7a98636748599bec26e093a373&pid=1-s2.0-S2666027X2400015X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140096236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tests for learning and memory in rodent regulatory studies","authors":"Charles V. Vorhees ,&nbsp;Michael T. Williams","doi":"10.1016/j.crtox.2024.100151","DOIUrl":"https://doi.org/10.1016/j.crtox.2024.100151","url":null,"abstract":"<div><p>For decades, regulatory guidelines for safety assessment in rodents for drugs, chemicals, pesticides, and food additives with developmental neurotoxic potential have recommended a single test of learning and memory (L&amp;M). In recent years some agencies have requested two such tests. Given the importance of higher cognitive function to health, and the fact that different types of L&amp;M are mediated by different brain regions assessing higher functions represents a step forward in providing better evidence-based protection against adverse brain effects. Given the myriad of tests available for assessing L&amp;M in rodents this leads to the question of which tests best fit regulatory guidelines. To address this question, we begin by describing the central role of two types of L&amp;M essential to all mammalian species and the regions/networks that mediate them. We suggest that the tests recommended possess characteristics that make them well suited to the needs in regulatory safety studies. By brain region, these are (1) the hippocampus and entorhinal cortex for spatial navigation, which assesses explicit L&amp;M for reference and episodic memory and (2) the striatum and related structures for egocentric navigation, which assesses implicit or procedural memory and path integration. Of the tests available, we suggest that in this context, the evidence supports the use of water mazes, specifically, the Morris water maze (MWM) for spatial L&amp;M and the Cincinnati water maze (CWM) for egocentric/procedural L&amp;M. We review the evidentiary basis for these tests, describe their use, and explain procedures that optimize their sensitivity.</p></div>","PeriodicalId":11236,"journal":{"name":"Current Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666027X24000045/pdfft?md5=4cdf122e9c38230165b1676d856c4200&pid=1-s2.0-S2666027X24000045-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139549244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"RNA sequencing analysis of early-stage atherosclerosis in vascular-on-a-chip and its application for comparing combustible cigarettes with heated tobacco products","authors":"Kazuhiro Ohashi ,&nbsp;Ayaka Hayashida ,&nbsp;Atsuko Nozawa,&nbsp;Shigeaki Ito","doi":"10.1016/j.crtox.2024.100163","DOIUrl":"10.1016/j.crtox.2024.100163","url":null,"abstract":"<div><p>Our previous study showed promising results in replicating early-stage atherosclerosis when vascular endothelial cells (VECs) were exposed to cigarette smoke (CS) extract via M0 macrophages. We used an organ-on-a-chip system as an alternative to animal testing to model atherosclerosis, which is a complex disease involving endothelial and immune cell communications. By incorporating macrophages into the vascular-on-a-chip system, we aimed to mimic the indirect effects of inhalable substances, such as CS, on VECs. In the current study, we further examined the suitability of our <em>in vitro</em> system for mimicking early-stage atherosclerosis by transcriptomic analyses of VECs exposed to CS directly or indirectly via macrophages. We also incorporated M1 macrophages to replicate a preexisting inflammatory state. We found a greater number of differentially expressed genes (DEGs) in direct exposure methods than indirect exposure methods. However, a pathway analysis showed that the direct exposure of CS to VECs primarily caused cell death-related pathway alterations, and the “Atherosclerosis Signaling” pathway was predicted to be negatively regulated. Indirect exposure via M0 macrophages similarly showed that the identified DEGs were related to cell death, while the “Atherosclerosis Signaling” pathway was predicted to be activated. In contrast, cell death-related pathway alterations were not observed by indirect exposure of CS to VECs via M1 macrophages, but the pathway perturbations were similar to a pro-inflammatory positive control. In addition, the “Atherosclerosis Signaling” pathway was predicted to be activated in VECs that were indirectly exposed to CS via M1 macrophages. These results suggest that M0 or M1 macrophages contribute to atherogenic transcriptomic changes in VECs, although they affect cell death-related pathways differently. We also used indirect exposure methods to compare the effects of CS and heated tobacco product (HTP) aerosol. Notably, gene expression changes related to atherosclerosis were less pronounced in HTP aerosol-exposed VECs than CS. Our study highlights the utility of the vascular-on-a-chip system with indirect exposure of CS extract via macrophages for replicating atherogenesis and suggests a reduced risk potential of the HTP. This research contributes to advancing alternatives to animal testing for toxicological and disease modeling studies.</p></div>","PeriodicalId":11236,"journal":{"name":"Current Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666027X24000161/pdfft?md5=d9dbee79c936851f77c5e3c234823928&pid=1-s2.0-S2666027X24000161-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140272549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prenatal test cohort of a modified rat comparative thyroid assay adding brain thyroid hormone measurements and histology but lowering group size appears able to detect disruption by sodium phenobarbital","authors":"Kenta Minami ,&nbsp;Akira Sato ,&nbsp;Naruto Tomiyama ,&nbsp;Keiko Ogata ,&nbsp;Tadashi Kosaka ,&nbsp;Hitoshi Hojo ,&nbsp;Naofumi Takahashi ,&nbsp;Hidenori Suto ,&nbsp;Hiroaki Aoyama ,&nbsp;Tomoya Yamada","doi":"10.1016/j.crtox.2024.100168","DOIUrl":"https://doi.org/10.1016/j.crtox.2024.100168","url":null,"abstract":"<div><p>The Comparative Thyroid Assay (CTA, USEPA) is a screening test for thyroid hormone (TH) disruption in peripheral blood of dams and offspring. Recently, we began investigating feasible improvements to the CTA by adding examination of offspring brain TH concentrations and brain histopathology. In addition, we hypothesize that the number of animals required could be reduced by 50 % while still maintaining sensitivity to characterize treatment related changes in THs. Previously, we showed that the prenatal test cohort of the modified CTA could detect 1000 ppm sodium phenobarbital (NaPB)-induced suppression of brain T3 (by 9 %) and T4 (by 33 %) with no significant changes in serum T3 and T4 (less than 8 %). In the current study we expanded the dose response in a prenatal test cohort. Pregnant SD rats (N = 10/group) were exposed to 0, 1000 or 1500 ppm NaPB in the diet from gestational days (GD) 6 to GD20. Serum THs concentrations in GD20 dams together with serum/brain THs concentrations and brain histopathology in the GD20 fetuses were examined. NaPB dose-dependently suppressed serum T3 (up to −26 %) and T4 (up to −44 %) in dams, with suppression of T3 in serum (up to −26 %) and brain (up to −18 %) and T4 in serum (up to −26 %) and brain (up to −29 %) of fetuses but without clear dose dependency. There were no remarkable findings that deviated significantly from controls in GD20 fetal brain by qualitative histopathology. Overall, the present study suggests that the prenatal test cohort of this modified CTA is able to detect the expected fetal TH disruptions by prenatal exposure to NaPB, while also reducing the number of animals used by 50 %, consistent with the results of our previous study. These findings add to the suggestion that lowering group sizes and adding endpoints may be a useful alternative to the original CTA design.</p></div>","PeriodicalId":11236,"journal":{"name":"Current Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666027X24000215/pdfft?md5=7499a0ae4c5a9041672a636569a69cfb&pid=1-s2.0-S2666027X24000215-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140633208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing developmental toxicity and non-CYP mediated biotransformation of two anti-epileptics and their human metabolites in zebrafish embryos and larvae","authors":"","doi":"10.1016/j.crtox.2024.100186","DOIUrl":"10.1016/j.crtox.2024.100186","url":null,"abstract":"<div><p>Zebrafish embryo-based assays are a promising alternative for animal testing to screen new compounds for developmental toxicity. However, recent studies in zebrafish embryos showed an immature intrinsic cytochrome P450 (CYP)-mediated biotransformation capacity, as most CYPs were only active at the end of the organogenesis period. Data on other phase I enzymes involved in the biotransformation of xenobiotics in zebrafish embryos is limited. This information is pivotal for proteratogens needing bioactivation to exert their teratogenic potential. Therefore, this study aimed to investigate whether carbamazepine (CBZ) and levetiracetam (LTC), two anti-epileptic drugs that require bioactivation to exert their teratogenic potential, are biotransformed into non-CYP mediated metabolites in the zebrafish embryo and whether one or more of these metabolites cause developmental toxicity in this species. In the first step, zebrafish embryos were exposed to LTC and CBZ and their non-CYP mediated human metabolites, etiracetam carboxylic acid (ECA) and 9-acridine carboxaldehyde (9ACA), acridine (AI), and acridone (AO), respectively, from 5.25 to 120 hpf and morphologically evaluated. Next, the uptake of all compounds and the formation of the metabolites were assessed using LC-MS methods. As LTC and ECA were, respectively, poorly or not taken up by zebrafish larvae during the exposure experiments, we could not determine if LTC and ECA are teratogenic. However, biotransformation of LTC into ECA was observed at 24 hpf and 120 hpf, which indicates that the special type of B-esterase is already active at 24 hpf. CBZ and its three metabolites were teratogenic, as a significant increase in malformed embryos was observed for all of them. All three metabolites were more potent teratogens than CBZ, with AI being the most potent, followed by 9ACA and AO. The myeloperoxidase (MPO) homologue is already active at 24 hpf, as CBZ was biotransformed into 9ACA and AO in 24 hpf zebrafish embryos, and into 9ACA in 120 hpf larvae. Moreover, 9ACA was also found to be biotransformed into AI and AO, and AI into AO. As such, one or more of these metabolites probably contribute to the teratogenic effects observed in zebrafish larvae after exposure to CBZ.</p></div>","PeriodicalId":11236,"journal":{"name":"Current Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666027X24000392/pdfft?md5=14a59dc81d0aa75c48d98d92747ceecd&pid=1-s2.0-S2666027X24000392-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141703758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}