RESUMO
The prevalence of fragrances in various hygiene products contributes to their sensorial allure. However, fragrances can induce sensitization in the skin or respiratory system, and the mechanisms involved in this process are incompletely understood. This study investigated the intricate mechanisms underlying the fragrance's effects on sensitization response, focusing on the interplay between CYP450 enzymes, a class of drug-metabolizing enzymes, and the adaptive immune system. Specifically, we assessed the expression of CYP450 enzymes and cytokine profiles in culture of BEAS-2B and mature dendritic cells (mDC) alone or in co-culture stimulated with 2 mM of a common fragrance, cinnamyl alcohol (CA) for 20 h. CYP1A1, CYP1A2, CYP1B1, CYP2A6, and CYP2A13 were analyzed by RT-PCR and IL-10, IL-12p70, IL-18, IL-33, and thymic stromal lymphopoietin (TSLP) by Cytometric Bead Array (CBA). Through RT-PCR analysis, we observed that CA increased CYP1A2 and CYP1B1 expression in BEAS-2B, with a further increased in BEAS-2B-mDC co-culture. Additionally, exposure to CA increased IL-12p70 levels in mDC rather than in BEAS-2B-mDC co-culture. In regards to IL-18, level was higher in BEAS-2B than in BEAS-2B-mDC co-culture. A positive correlation between the levels of IL-10 and CYP1B1 was found in mDC-CA-exposed and between IL-12p70 and CYP1A1 was found in BEAS-2B after CA exposure. However, IL-12p70 and CYP1A2 as well as IL-18, IL-33, and CYP1A1 levels were negative, correlated mainly in co-culture control. These correlations highlight potential immunomodulatory interactions and complex regulatory relationships. Overall, exposure to CA enhances CYP450 expression, suggesting that CA can influence immune responses by degrading ligands on xenosensitive transcription factors.
Assuntos
Técnicas de Cocultura , Sistema Enzimático do Citocromo P-450 , Citocinas , Células Dendríticas , Propanóis , Humanos , Citocinas/metabolismo , Células Dendríticas/efeitos dos fármacos , Células Dendríticas/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Propanóis/toxicidade , Propanóis/metabolismo , Linhagem Celular , Citocromo P-450 CYP1A1/metabolismo , Citocromo P-450 CYP1A1/genética , Citocromo P-450 CYP1B1/genética , Citocromo P-450 CYP1B1/metabolismo , Perfumes/toxicidade , Receptores de Hidrocarboneto Arílico/metabolismo , Receptores de Hidrocarboneto Arílico/genética , Citocromo P-450 CYP1A2/metabolismo , Citocromo P-450 CYP1A2/genéticaRESUMO
3-Monochloropropane-1,2-diol (3-MCPD), glycidol, together with their fatty acid esters are commonly presented in various food and have shown carcinogenicity in various laboratory animals. Public health risk assessment of 3-MPCD and glycidol exposure relies on quantitative tools that represent their in vivo toxicokinetics. In order to better understand the absorption, distribution, metabolism, and excretion profiles of 3-MCPD and glycidol in male rats, a physiologically based pharmacokinetic (PBTK) model was developed. The model's predictive power was evaluated by comparing in silico simulations to in vivo time course data obtained from experimental studies. Results indicate that our PBTK model successfully captured the toxicokinetics of both free chemicals in key organs, and their metabolites in accessible biological fluids. With the validated PBTK model, we then gave an animal-free example on how to extrapolate the toxicological knowledge acquired from a single gavage to a realistic dietary intake scenario. Three biomarkers, free compound in serum, urinary metabolite DHPMA, and glycidol-hemoglobin adduct (diHOPrVal) were selected for in silico simulation following constant dietary intakes, and their internal levels were correlated with proposed external daily exposure via reverse dosimetry approaches. Taken together, our model provides a computational approach for extrapolating animal toxicokinetic experiments to biomonitoring measurement and risk assessment.
Assuntos
alfa-Cloridrina , Masculino , Ratos , Animais , alfa-Cloridrina/toxicidade , Toxicocinética , Propanóis/toxicidade , Propanóis/metabolismo , Compostos de Epóxi/toxicidade , Modelos BiológicosRESUMO
3-chloropropane-1,2-diol (3-MCPD) and its toxic metabolite glycidol were classified by the International Agency for Research on Cancer (IARC) as belonging to group 2B and 2A for humans. This study aimed to determine the sub-acute toxicity of these agents. Rats were exposed to 3-MCPD at 0.87 and 10 mg/kg/bw and glycidol (2,4 and 37,5 mg/kg/bw) for 90 days. miR-21 gene expression levels significantly decreased in all group's cerebellar tissues compared with control. Exposure to 10 mg/kg/bw 3-MCPD showed significant increases in PTEN in brain as compared to control group. The Akt gen expressions were significantly decreased in 3-MCPD and glycidol groups when compared to control group brains. Additionally, Caspase 3 and AIF immunopositivity significantly increased in 3-MCPD high dose and glycidol high dose groups in cerebellum granular layers compared to control. The results of the present study conclude that 3-MCPD and glycidol can induce apoptosis in rat brain tissue.
Assuntos
Apoptose/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Esterilizantes Químicos/toxicidade , Compostos de Epóxi/toxicidade , Propanóis/toxicidade , alfa-Cloridrina/toxicidade , Animais , Fator de Indução de Apoptose/metabolismo , Encéfalo/citologia , Encéfalo/metabolismo , Caspase 3/metabolismo , Masculino , MicroRNAs , PTEN Fosfo-Hidrolase/genética , Proteínas Proto-Oncogênicas c-akt/genética , Ratos WistarRESUMO
Prion disease is a neurodegenerative disorder with progressive neurologic symptoms and accelerated cognitive decline. The causative protein of prion disease is the prion protein (PrP), and structural transition of PrP from the normal helix rich form (PrPC) to the abnormal ß-sheet rich form (PrPSc) occurs in prion disease. While so far numerous therapeutic agents for prion diseases have been developed, none of them are still useful. A fluorinated alcohol, hexafluoro isopropanol (HFIP), is a precursor to the inhalational anesthetic sevoflurane and its metabolites. HFIP is also known as a robust α-helix inducer and is widely used as a solvent for highly aggregated peptides. Here we show that the α-helix-inducing activity of HFIP caused the conformational transformation of the fibrous structure of PrP into amorphous aggregates in vitro. HFIP added to the ScN2a cell medium, which continuously expresses PrPSc, reduced PrPSc protease resistance after 24-h incubation. It was also clarified that ScN2a cells are more susceptible to HFIP than any of the cells being compared. Based on these findings, HFIP is expected to develop as a therapeutic agent for prion disease.
Assuntos
Proteínas Priônicas/metabolismo , Propanóis/farmacologia , Multimerização Proteica/efeitos dos fármacos , Animais , Células COS , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Chlorocebus aethiops , Camundongos , Propanóis/toxicidadeRESUMO
The environmental and food contaminant, benzo[a]pyrene {B[a]P, a polycyclic aromatic hydrocarbon (PAH)}, is classified as a human carcinogen by the International Agency for Research on Cancer. The carcinogenicity of B[a]P is linked to the formation of electrophilic metabolites, namely B[a]P-diol epoxides (BPDEs) occurring as stereoisomers. In this work, we quantified the metabolic formation of BPDE isomers and the genotoxic effect in B[a]P-exposed mice, with an aim to estimate the genotoxic potency of B[a]P per in vivo dose of its most potent metabolite [i.e. (+)-anti-BPDE]. The increase in frequency of micronuclei (fMN) in erythrocytes was measured as a biomarker for genotoxic effect. Covalent adducts to serum albumin (SA) and those to DNA from the BPDEs were analysed using liquid chromatography tandem mass spectrometry (LC-MS/MS), as adducts to histidine (BPDE-His-Pro) and deoxyguanosine (BPDE-dG), respectively. For the first time in animal experiments it was possible to resolve adducts to SA from (+)-anti-, (-)-anti- and (±)-syn-BPDE isomers by LC-MS/MS. The adduct levels in the protein were about 16â¯fmol/mg SA, which was orders of magnitude lower than that in the nucleic acid, 28â¯pmol/mg DNA, in mice exposed to 100â¯mg B[a]P per kg body weight (bw). Using SA adduct levels, the in vivo dose of (+)-anti-BPDE was calculated to be approximately 50â¯nM·h per mg B[a]P per kg bw. This allowed to make a preliminary estimate of the genotoxic potency as 2 fMN per µM·h of (+)-anti-BPDE. This estimate was compared to that from another food toxicant, glycidol, studied with similar methods, which indicated that the BPDE has several orders of magnitude higher genotoxic potency. The demonstrated approach on integrating biomarkers of internal dose of a causative agent and that of genotoxic effect for assessing genotoxic potency, using B[a]P as a model, has a potential for improving cancer risk assessment procedures for PAHs.
Assuntos
Benzo(a)pireno/toxicidade , Carcinógenos/toxicidade , Adutos de DNA/química , Micronúcleos com Defeito Cromossômico/estatística & dados numéricos , Albumina Sérica/química , Animais , Biotransformação , Compostos de Epóxi/química , Compostos de Epóxi/toxicidade , Injeções Intraperitoneais , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Testes para Micronúcleos , Propanóis/toxicidadeRESUMO
In order to estimate the potential risk of chemicals including drug in patients with type 2 diabetes mellitus (T2DM), we investigated allyl alcohol induced liver injury using SD rats and Spontaneously Diabetic Torii-Leprfa (SDT fatty) rats as a model for human T2DM. The diabetic state is one of the risk factors for chemically induced liver injury because of lower levels of glutathione for detoxification by conjugation with chemicals and environmental pollutants and their reactive metabolites. Allyl alcohol is metabolized to a highly reactive unsaturated aldehyde, acrolein, which is detoxified by conjugation with glutathione. Therefore, we used allyl alcohol as a model compound. Our investigations showed that SDT fatty rats appropriately mimic the diabetic state in humans. The profiles of glucose metabolism, hepatic function tests and glutathione synthesis in the SDT fatty rats were similar to those in patients with T2DM. Five-week oral dosing with allyl alcohol to the SDT fatty rats revealed that the allyl alcohol induced liver injury was markedly enhanced in the SDT fatty rats when compared with the SD rats and the difference was considered to be due to lower hepatic detoxification of acrolein, the reactive metabolite of allyl alcohol, by depleted hepatic glutathione synthesis. Taking all the results of the present study into consideration, the potential for allyl alcohol to induce liver injury is considered to be higher in diabetic patients than in healthy humans.
Assuntos
Doença Hepática Crônica Induzida por Substâncias e Drogas , Diabetes Mellitus Tipo 2 , Propanóis/toxicidade , Animais , Doença Hepática Crônica Induzida por Substâncias e Drogas/patologia , Modelos Animais de Doenças , Glucose/metabolismo , Glutationa/metabolismo , Humanos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Masculino , Ratos Sprague-Dawley , RiscoRESUMO
Here we evaluate a multiplicative (relative) risk model for improved cancer risk estimation of genotoxic compounds. According to this model, cancer risk is proportional to the background tumor incidence and to the internal dose of the genotoxic compound. Furthermore, the relative risk coefficient per internal dose is considered to be approximately the same across tumor sites, sex, and species. In the present study, we demonstrate that the relative risk model is valid for cancer risk estimation of glycidol, a common food contaminant. Published tumor data from glycidol carcinogenicity studies in mice and rats were evaluated in combination with internal dose estimates from hemoglobin adduct measurements in blood from mice and rats treated with glycidol in short-term studies. A good agreement between predicted and observed tumor incidence in responding sites was demonstrated in the animals, supporting a relative risk coefficient that is independent of tumor site, sex, and species. There was no significant difference between the risk coefficients for mice (5.1% per mMh) and rats (5.4% per mMh) when considering internal doses of glycidol. Altogether, this mechanism-based risk model gives a reliable risk coefficient, which then was extrapolated to humans considering internal dose, and background cancer incidence.
Assuntos
Carcinógenos/toxicidade , Compostos de Epóxi/toxicidade , Modelos Teóricos , Neoplasias Experimentais/induzido quimicamente , Propanóis/toxicidade , Animais , Área Sob a Curva , Carcinógenos/administração & dosagem , Carcinógenos/farmacocinética , Relação Dose-Resposta a Droga , Compostos de Epóxi/administração & dosagem , Compostos de Epóxi/farmacocinética , Feminino , Hemoglobinas/metabolismo , Masculino , Camundongos , Propanóis/administração & dosagem , Propanóis/farmacocinética , Ratos , Ratos Sprague-Dawley , Medição de RiscoRESUMO
Fatty acid esters of glycidol (glycidyl esters) are heat-induced food contaminants predominantly formed during industrial deodorization of vegetable oils and fats. After consumption, the esters are digested in the gastrointestinal tract, leading to a systemic exposure to the reactive epoxide glycidol. The compound is carcinogenic, genotoxic and teratogenic in rodents, and rated as probably carcinogenic to humans (IARC group 2A). Assessment of exposure from occurrence and consumption data is difficult, as lots of different foods containing refined oils and fats may contribute to human exposure. Therefore, assessment of the internal exposure using the hemoglobin adduct of glycidol, N-(2,3-dihydroxypropyl)-valine (2,3-diHOPr-Val), may be promising, but a proof-of-principle study is needed to interpret adduct levels with respect to the underlying external exposure. A controlled exposure study was conducted with 11 healthy participants consuming a daily portion of about 36 g commercially available palm fat with a relatively high content of ester-bound glycidol (8.7 mg glycidol/kg) over 4 weeks (total amount 1 kg fat, individual doses between 2.7 and 5.2 µg/kg body weight per day). Frequent blood sampling was performed to monitor the 2,3-diHOPr-Val adduct levels during formation and the following removal over 15 weeks, using a modified Edman degradation and ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Results demonstrated for the first time that the relatively high exposure during the intervention period was reflected in corresponding distinct increases of 2,3-diHOPr-Val levels in all participants, following the expected slope for hemoglobin adduct formation and removal over time. The mean adduct level increased from 4.0 to 12.2 pmol 2,3-diHOPr-Val/g hemoglobin. By using a nonlinear mixed model, values for the adduct level/dose ratio (k, mean 0.082 pmol 2,3-diHOPr-Val/g hemoglobin per µg glycidol/kg body weight) and the adduct lifetime (τ, mean 104 days, likely the lifetime of the erythrocytes) were determined. Interindividual variability was generally low. 2,3-DiHOPr-Val was therefore proven to be a biomarker of the external dietary exposure to fatty acid esters of glycidol. From the background adduct levels observed in our study, a mean external glycidol exposure of 0.94 µg/kg body weight was estimated. This value is considerably higher than current estimates for adults using occurrence and consumption data of food. Possible reasons for this discrepancy are discussed (other oral or inhalational glycidol sources, endogenous formation, exposure to other chemicals also forming the adduct 2,3-diHOPr-Val). Further research is necessary to clarify the issue.
Assuntos
Biomarcadores/sangue , Exposição Dietética/análise , Compostos de Epóxi/toxicidade , Hemoglobinas/efeitos dos fármacos , Óleo de Palmeira/administração & dosagem , Propanóis/toxicidade , Valina/análogos & derivados , Adulto , Cromatografia Líquida de Alta Pressão , Exposição Dietética/efeitos adversos , Eritrócitos/química , Eritrócitos/efeitos dos fármacos , Feminino , Fluoresceína-5-Isotiocianato/química , Hemoglobinas/química , Humanos , Masculino , Pessoa de Meia-Idade , Extração em Fase Sólida , Espectrometria de Massas em Tandem , Valina/sangue , Valina/químicaRESUMO
The production and preparation of foodstuffs may entail at high temperatures the generation of undesirable, potentially harmful compounds. Among the best investigated heat-induced contaminants are acrylamide, furan, and the fatty acid esters of glycidol and the monochloropropanediols. This article presents the main insights into the formation, toxicology, and exposure of these compounds. Acrylamide and glycidol were characterized as carcinogens with a genotoxic mechanism in animal experiments. Their content in foods should be minimized. For 3monochloropropanediol (3-MCPD), a tolerable daily intake can be derived. In contrast, a complete risk assessment is currently not possible for furan and 2MCPD owing to insufficient data.Many other heat-induced substances in foodstuffs were identified in addition to the compounds mentioned above, but for most no data on their toxicological properties and human exposure is available. Therefore, no risk assessment can currently be undertaken for these compounds. To prioritize this large number of compounds according to their possible hazard potential, it is reasonable to utilize computer modeling programs for the prediction of defined toxicological endpoints based on the molecular chemical structures. However, substances classed as a priority must be further investigated with regard to the toxicology and quantification of the food content of these compounds to allow a meaningful risk assessment.
Assuntos
Carcinógenos/análise , Carcinógenos/toxicidade , Culinária , Contaminação de Alimentos/análise , Contaminação de Alimentos/prevenção & controle , Calefação/efeitos adversos , Acrilamida/análise , Acrilamida/toxicidade , Simulação por Computador , Compostos de Epóxi/análise , Compostos de Epóxi/toxicidade , Furanos/análise , Furanos/toxicidade , Propanóis/análise , Propanóis/toxicidade , Medição de Risco , alfa-Cloridrina/análise , alfa-Cloridrina/toxicidadeRESUMO
3-Monochloropropane-1,2-diol (3-MCPD) is a well-known food processing contaminant that has been regarded as a rat carcinogen, which is known to induce Leydig-cell and mammary gland tumors in males, as well as kidney tumors in both genders. 3-MCPD is highly suspected to be a non-genotoxic carcinogen. 2,3-Epoxy-1-propanol (glycidol) can be formed via dehalogenation from 3-MCPD. We aimed to investigate the cytotoxic effects of 3-MCPD and glycidol, then to demonstrate the possible epigenetic mechanisms with global and gene-specific DNA methylation in rat kidney epithelial cells (NRK-52E). IC50 value of 3-MCPD was determined as 48 mM and 41.39 mM, whereas IC50 value of glycidol was 1.67 mM and 1.13 mM by MTT and NRU test, respectively. Decreased global DNA methylation at the concentrations of 100 µM and 1000 µM for 3-MCPD and 100 µM and 500 µM for glycidol were observed after 48 h exposure by using 5-methylcytosine (5-mC) ELISA kit. Methylation changes were detected in promoter regions of c-myc and Rassf1a in 3-MCPD and glycidol treated NRK-52E cells by using methylation-specific PCR (MSP), whereas changes on gene expression of c-myc and Rassf1a were observed by using real-time PCR. However, e-cadherin, p16, VHL and p15 genes were unmethylated in their CpG promoter regions in response to treatment with 3-MCPD and glycidol. Alterations in DNA methylation might be key events in the toxicity of 3-MCPD and glycidol.
Assuntos
Carcinógenos/toxicidade , Esterilizantes Químicos/toxicidade , Metilação de DNA/efeitos dos fármacos , Epigênese Genética/efeitos dos fármacos , Compostos de Epóxi/toxicidade , Túbulos Renais/efeitos dos fármacos , Propanóis/toxicidade , alfa-Cloridrina/toxicidade , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Ilhas de CpG/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Genes myc/efeitos dos fármacos , Concentração Inibidora 50 , Túbulos Renais/metabolismo , Regiões Promotoras Genéticas , Ratos , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismoRESUMO
Glycidol is a genotoxic animal carcinogen that has raised concern due to its presence in food, as glycidyl fatty acid esters. Here we investigated the genotoxicity of glycidol in BalbC mice (0-120 mg/kg) by monitoring the induction of micronuclei in peripheral blood as a marker of chromosomal damage. The scoring of the micronuclei was assessed by flow cytometry. In the treated mice, the internal dose of glycidol, expressed as area under the concentration-time curve, AUC (mol × L-1 × h; Mh), was measured by dihydroxypropyl adducts to hemoglobin (Hb). The study showed that glycidol induced linear dose-dependent increases of Hb adducts (20 pmol/g Hb per mg/kg) and of micronuclei frequencies (12 per mMh). Compared to calculations based on administered dose, an improved dose-response relationship was observed when considering internal dose, achieved through the applied combination of sensitive techniques used for the scoring of micronuclei and AUC estimation of glycidol in the same mice. By comparing with earlier studies on micronuclei induction in mice exposed to ionizing radiation we estimated the radiation dose equivalent (rad-eq.) of glycidol to be ca 15 rad-eq./mMh.
Assuntos
Carcinógenos/toxicidade , Compostos de Epóxi/toxicidade , Hemoglobinas/metabolismo , Micronúcleos com Defeito Cromossômico/efeitos dos fármacos , Propanóis/toxicidade , Animais , Dano ao DNA/efeitos dos fármacos , Relação Dose-Resposta a Droga , Citometria de Fluxo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Testes para MicronúcleosRESUMO
Glycidol (Gly) is an electrophilic low-molecular weight epoxide that is classified by IARC as probably carcinogenic to humans. Humans might be exposed to Gly from food, e.g. refined vegetable oils, where Gly has been found as a food process contaminant. It is therefore important to investigate and quantify the genotoxicity of Gly as a primary step towards cancer risk assessment of the human exposure. Here, quantification of the mutagenic potency expressed per dose (AUC: area under the concentration-time curve) of Gly has been performed in Chinese hamster ovary (CHO) cells, using the HPRT assay. The dose of Gly was estimated in the cell exposure medium by trapping Gly with a strong nucleophile, cob(I)alamin, to form stable cobalamin adducts for analysis by LC-MS/MS. Gly was stable in the exposure medium during the time for cell treatment, and thus the dose in vitro is the initial concentration×cell treatment time. Gly induced mutations in the hprt-gene at a rate of 0.08±0.01 mutations/10(5) cells/mMh. Through comparison with the effect of ionizing radiation in the same system a relative mutagenic potency of 9.5rad-eq./mMh was obtained, which could be used for comparison of genotoxicity of chemicals and between test systems and also in procedures for quantitative cancer risk assessment. Gly was shown to induce strand breaks, that were repaired by base excision repair. Furthermore, Gly-induced lesions, present during replication, were found to delay the replication fork elongation. From experiments with repair deficient cells, homologous recombination repair and the ERCC1-XPF complex were indicated to be recruited to support in the repair of the damage related to the stalled replication elongation. The type of DNA damage responsible for the mutagenic effect of Gly could not be concluded from the present study.
Assuntos
Compostos de Epóxi/toxicidade , Propanóis/toxicidade , Animais , Células CHO , Cricetinae , Cricetulus , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/genética , Óxido de Etileno/toxicidade , Mutagênicos/toxicidade , Espectrometria de Massas em TandemRESUMO
IARC has classified glycidol and 3-monochloropropane-1,2-diol (3-MCPD) as group 2A and 2B, respectively. Their esters are generated in foodstuffs during processing and there are concerns that they may be hydrolyzed to the carcinogenic forms in vivo. Thus, we conducted two studies. In the first, we administered glycidol and 3-MCPD and associated esters (glycidol oleate: GO, glycidol linoleate: GL, 3-MCPD dipalmitate: CDP, 3-MCPD monopalmitate: CMP, 3-MCPD dioleate: CDO) to male F344 rats by single oral gavage. After 30 min, 3-MCPD was detected in serum from all groups. Glycidol was detected in serum from the rats given glycidol or GL and CDP and CDO in serum from rats given these compounds. In the second, we examined if metabolism occurs on simple reaction with rat intestinal contents (gastric, duodenal and cecal contents) from male F344 gpt delta rats. Newly produced 3-MCPD was detected in all gut contents incubated with the three 3-MCPD fatty acid esters and in gastric and duodenal contents incubated with glycidol and in duodenal and cecal contents incubated with GO. Although our observation was performed at 1 time point, the results showed that not only 3-MCPD esters but also glycidol and glycidol esters are metabolized into 3-MCPD in the rat.
Assuntos
Compostos de Epóxi/administração & dosagem , Compostos de Epóxi/metabolismo , Ésteres/administração & dosagem , Ésteres/metabolismo , Ácidos Graxos/administração & dosagem , Ácidos Graxos/metabolismo , Propanóis/administração & dosagem , Propanóis/metabolismo , alfa-Cloridrina/administração & dosagem , alfa-Cloridrina/metabolismo , Administração Oral , Animais , Biotransformação , Ceco/metabolismo , Duodeno/metabolismo , Compostos de Epóxi/sangue , Compostos de Epóxi/toxicidade , Ésteres/sangue , Ésteres/toxicidade , Ácidos Graxos/sangue , Ácidos Graxos/toxicidade , Mucosa Gástrica/metabolismo , Hidrólise , Masculino , Propanóis/sangue , Propanóis/toxicidade , Ratos Endogâmicos F344 , alfa-Cloridrina/sangue , alfa-Cloridrina/toxicidadeRESUMO
The in vivo comet assay has been used for the evaluation of DNA damage and repair in various tissues of rodents. However, it can give false-positive results due to non-specific DNA damage associated with cell death. In this study, we examined whether the in vivo comet assay can distinguish between genotoxic and non-genotoxic DNA damage in urinary bladder cells, by using the following seven chemicals related to urinary bladder carcinogenesis in rodents: N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN), glycidol, 2,2-bis(bromomethyl)-1,3-propanediol (BMP), 2-nitroanisole (2-NA), benzyl isothiocyanate (BITC), uracil, and melamine. BBN, glycidol, BMP, and 2-NA are known to be Ames test-positive and they are expected to produce DNA damage in the absence of cytotoxicity. BITC, uracil, and melamine are Ames test-negative with metabolic activation but have the potential to induce non-specific DNA damage due to cytotoxicity. The test chemicals were administered orally to male Sprague-Dawley rats (five per group) for each of two consecutive days. Urinary bladders were sampled 3h after the second administration and urothelial cells were analyzed by the comet assay and subjected to histopathological examination to evaluate cytotoxicity. In the urinary bladders of rats treated with BBN, glycidol, and BMP, DNA damage was detected. In contrast, 2-NA induced neither DNA damage nor cytotoxicity. The non-genotoxic chemicals (BITC, uracil, and melamine) did not induce DNA damage in the urinary bladders under conditions where some histopathological changes were observed. The results indicate that the comet assay could distinguish between genotoxic and non-genotoxic chemicals and that no false-positive responses were obtained.
Assuntos
Carcinógenos/toxicidade , Ensaio Cometa/métodos , Dano ao DNA/efeitos dos fármacos , Bexiga Urinária/efeitos dos fármacos , Bexiga Urinária/patologia , Animais , Butilidroxibutilnitrosamina/toxicidade , Relação Dose-Resposta a Droga , Compostos de Epóxi/toxicidade , Isotiocianatos/toxicidade , Masculino , Propanóis/toxicidade , Propilenoglicóis/toxicidade , Ratos , Ratos Sprague-Dawley , Triazinas/toxicidade , Uracila/toxicidadeRESUMO
We previously found that the 28-day oral toxicity study of glycidol at 200mg/kg/day in rats resulted in axonopathy in both the central and peripheral nervous systems and aberrations in the late-stage of hippocampal neurogenesis targeting the process of neurite extension. To capture the neuronal parameters in response to glycidol toxicity, these animals were subjected to region-specific global gene expression profiling in four regions of cerebral and cerebellar architectures, followed by immunohistochemical analysis of selected gene products. Expression changes of genes related to axonogenesis and synaptic transmission were observed in the hippocampal dentate gyrus, cingulate cortex and cerebellar vermis at 200mg/kg showing downregulation in most genes. In the corpus callosum, genes related to growth, survival and functions of glial cells fluctuated their expression. Immunohistochemically, neurons expressing gene products of immediate-early genes, i.e., Arc, Fos and Jun, decreased in their number in the dentate granule cell layer, cingulate cortex and cerebellar vermis. We also applied immunohistochemical analysis in rat offspring after developmental exposure to glycidol through maternal drinking water. The results revealed increases of Arc(+) neurons at 1000ppm and Fos(+) neurons at ≥300ppm in the dentate granule cell layer of offspring only at the adult stage. These results suggest that glycidol suppressed neuronal plasticity in the brain after 28-day exposure to young adult animals, in contrast to the operation of restoration mechanism to increase neuronal plasticity at the adult stage in response to aberrations in neurogenesis after developmental exposure.
Assuntos
Encéfalo/efeitos dos fármacos , Compostos de Epóxi/toxicidade , Genes Precoces , Plasticidade Neuronal/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Propanóis/toxicidade , Fatores Etários , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Relação Dose-Resposta a Droga , Regulação para Baixo , Feminino , Perfilação da Expressão Gênica/métodos , Imuno-Histoquímica , Masculino , Exposição Materna , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Neurogênese/efeitos dos fármacos , Neurogênese/genética , Plasticidade Neuronal/genética , Neurônios/metabolismo , Neurônios/patologia , Análise de Sequência com Séries de Oligonucleotídeos , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Proteínas Proto-Oncogênicas c-fos/genética , Proteínas Proto-Oncogênicas c-fos/metabolismo , Proteínas Proto-Oncogênicas c-jun/genética , Proteínas Proto-Oncogênicas c-jun/metabolismo , Ratos , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/genética , Fatores de TempoRESUMO
Hemoglobin adducts have been used as biomarkers of exposure to reactive chemicals. Glycidol, an animal carcinogen, has been reported to form N-(2,3-dihydroxy-propyl)valine adducts to hemoglobin (diHOPrVal). To support the use of these adducts as markers of glycidol exposure, we investigated the kinetics of diHOPrVal formation and its elimination in vitro and in vivo. Five groups of rats were orally administered a single dose of glycidol ranging from 0 to 75mg/kg bw, and diHOPrVal levels were measured 24h after administration. A dose-dependent increase in diHOPrVal levels was observed with high linearity (R(2)=0.943). Blood sampling at different time points (1, 10, 20, or 40days) from four groups administered glycidol at 12mg/kg bw suggested a linear decrease in diHOPrVal levels compatible with the normal turnover of rat erythrocytes (life span, 61days), with the calculated first-order elimination rate constant (kel) indicating that the diHOPrVal adduct was chemically stable. Then, we measured the second-order rate constant (kval) for the reaction of glycidol with N-terminal valine in rat and human hemoglobin in in vitro experiments with whole blood. The kval was 6.7±1.1 and 5.6±1.3 (pmol/g globin per µMh) in rat and human blood, respectively, indicating no species differences. In vivo doses estimated from kval and diHOPrVal levels were in agreement with the area under the (concentration-time) curve values determined in our earlier toxicokinetic study in rats. Our results indicate that diHOPrVal is a useful biomarker for quantification of glycidol exposure and for risk assessment.
Assuntos
Carcinógenos/toxicidade , Compostos de Epóxi/toxicidade , Hemoglobinas/metabolismo , Propanóis/toxicidade , Valina/análogos & derivados , Administração Oral , Animais , Biomarcadores/sangue , Carcinógenos/administração & dosagem , Carcinógenos/metabolismo , Carcinógenos/farmacocinética , Relação Dose-Resposta a Droga , Compostos de Epóxi/administração & dosagem , Compostos de Epóxi/sangue , Compostos de Epóxi/farmacocinética , Eritrócitos/metabolismo , Humanos , Modelos Lineares , Masculino , Taxa de Depuração Metabólica , Modelos Biológicos , Propanóis/administração & dosagem , Propanóis/sangue , Propanóis/farmacocinética , Ratos , Ratos Sprague-Dawley , Medição de Risco , Valina/sangue , Valina/farmacocinéticaRESUMO
Developmental exposure to glycidol induces aberrations of late-stage neurogenesis in the hippocampal dentate gyrus of rat offspring, whereas maternal animals develop axonopathy. To investigate the possibility whether similar effects on adult neurogenesis could be induced by exposure in a framework of 28-day toxicity study, glycidol was orally administered to 5-week-old male Sprague-Dawley rats by gavage at 0, 30 or 200 mg/kg for 28 days. At 200 mg/kg, animals revealed progressively worsening gait abnormalities as well as histopathological and immunohistochemical changes suggestive of axonal injury as evidenced by generation of neurofilament-L(+) spheroids in the cerebellar granule layer and dorsal funiculus of the medulla oblongata, central chromatolysis in the trigeminal nerve ganglion cells and axonal degeneration in the sciatic nerves. At the same dose, animals revealed aberrations in neurogenesis at late-stage differentiation as evidenced by decreases of both doublecortin(+) and dihydropyrimidinase-like 3(+) cells in the subgranular zone (SGZ) and increased reelin(+) or calbindin-2(+) γ-aminobutyric acid-ergic interneurons and neuron-specific nuclear protein(+) mature neurons in the dentate hilus. These effects were essentially similar to that observed in offspring after maternal exposure to glycidol. These results suggest that glycidol causes aberrations in adult neurogenesis in the SGZ at the late stage involving the process of neurite extension similar to the developmental exposure study in a standard 28-day toxicity study.
Assuntos
Axônios/patologia , Carcinógenos/toxicidade , Diferenciação Celular/efeitos dos fármacos , Compostos de Epóxi/toxicidade , Hipocampo/citologia , Hipocampo/efeitos dos fármacos , Neurogênese/efeitos dos fármacos , Propanóis/toxicidade , Animais , Antígenos Nucleares/metabolismo , Apoptose/efeitos dos fármacos , Contagem de Células , Giro Denteado/efeitos dos fármacos , Giro Denteado/crescimento & desenvolvimento , Proteína Duplacortina , Feminino , Transtornos Neurológicos da Marcha/induzido quimicamente , Transtornos Neurológicos da Marcha/patologia , Hipocampo/crescimento & desenvolvimento , Hormônios/sangue , Imuno-Histoquímica , Interneurônios/efeitos dos fármacos , Interneurônios/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase em Tempo Real , Proteína Reelina , Células-Tronco/efeitos dos fármacos , Hormônios Tireóideos/sangueRESUMO
Fatty acid esters of 3-monochloropropanediol (3-MCPD) and glycidol are processing contaminants found in a wide range of edible oils. While both 3 MCPD and glycidol have toxicological properties that at present has concerns for food safety, the published occurrence data are limited. Occurrence information is presented for the concentrations of 3-MCPD and glycidyl esters in 116 retail and/or industrial edible oils and fats using LC-MS/MS analysis of intact esters. The concentrations for bound 3-MCPD ranged from below the limit of quantitation (Assuntos
Carcinógenos/análise
, Compostos de Epóxi/análise
, Contaminação de Alimentos
, Glicerol/análogos & derivados
, Mutagênicos/análise
, Óleos de Plantas/química
, Propanóis/análise
, Carcinógenos/química
, Carcinógenos/toxicidade
, Cromatografia Líquida de Alta Pressão
, Compostos de Epóxi/química
, Compostos de Epóxi/toxicidade
, Esterificação
, Ácidos Graxos/análise
, Ácidos Graxos/química
, Manipulação de Alimentos
, Glicerol/análise
, Glicerol/química
, Glicerol/toxicidade
, Temperatura Alta/efeitos adversos
, Limite de Detecção
, Maryland
, Estrutura Molecular
, Mutagênicos/química
, Mutagênicos/toxicidade
, Óleo de Palmeira
, Óleos de Plantas/efeitos adversos
, Óleos de Plantas/economia
, Propanóis/química
, Propanóis/toxicidade
, Extração em Fase Sólida
, Espectrometria de Massas por Ionização por Electrospray
, Espectrometria de Massas em Tandem
, Estados Unidos
, alfa-Cloridrina