Subchronic exposure to fenpyroximate causes multiorgan toxicity in Wistar rats by disrupting lipid profile, inducing oxidative stress and DNA damage.

BACKGROUND: Fenpyroximate (FEN) is an acaricide that inhibits the complex I of the mitochondrial respiratory chain in mites. Data concerning mammalian toxicity of this acaricide are limited; thus the aim of this work was to explore FEN toxicity on Wistar rats, particularly on cardiac, pulmonary, and splenic tissues and in bone marrow cells. METHODS: rats were treated orally with FEN at 1, 2, 4, and 8 mg/Kg bw for 28 days. After treatment, we analyzed lipid profile, oxidative stress and DNA damage in rat tissues. RESULTS: FEN exposure increased creatinine phosphokinase (CPK) and lactate dehydrogenase (LDH) activities, elevated total cholesterol (T-CHOL), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C) concentrations, while decreasing high-density lipoprotein cholesterol (HDL-C). It inhibited acetylcholinesterase (AChE) activity, enhanced lipid peroxidation, protein oxidation, and modulated antioxidant enzymes activities (superoxide dismutase, catalase, glutathione peroxidase, and glutathione S-transferase). Comet assay indicated that FEN induced a dose-dependent DNA damage, contrasting with the micronucleus test showing no micronuclei formation. Nonetheless, FEN exhibited cytotoxicity to bone marrow cells, as evidenced by a reduction in the number of immature erythrocytes among total cells. CONCLUSION: FEN appears to carry out its genotoxic and cytotoxic activities most likely through an indirect pathway that involves oxidative stress.

Oxidative stress-mediated mitochondrial apoptosis induced by the acaricide, fenpyroximate, on cultured human colon cancer HCT 116 cells.

Fenpyroximate (FEN) is an acaricide that inhibits mitochondrial electron transport at the NADH-coenzyme Q oxidoreductase (complex I). The present study was designed to investigate the molecular mechanisms underling FEN toxicity on cultured human colon carcinoma cells (HCT116). Our data showed that FEN induced HCT116 cell mortality in a concentration dependent manner. FEN arrested cell cycle in G0/G1 phase and increased DNA damage as assessed by comet assay. Induction of apoptosis was confirmed in HCT116 cells exposed to FEN by AO-EB staining and Annexin V-FITC/PI double staining assay. Moreover, FEN induced a loss in mitochondrial membrane potential (MMP), increased p53 and Bax mRNA expression and decreased bcl2 mRNA level. An increase in caspase 9 and caspase 3 activities was also detected. All toghether, these data suggest that FEN induce apoptosis in HCT116 cells via mitochondrial pathway. To check the implication of oxidative stress in FEN-induced cell toxicity, we examined the oxidative stress statue in HCT116 cells exposed to FEN and we tested the effect of a powerful antioxidant, N-acetylcystein (NAC), on FEN-caused toxicity. It was observed that FEN enhanced ROS generation and MDA levels and disturbed SOD and CAT activities. Besides, cell treatment with NAC significantly protected cells from mortality, DNA damage, loss of MMP, and caspase 3 activity induced by FEN. To the best of our knowledge, this is the first study showing that FEN induced mitochondrial apoptosis via ROS generation and oxidative stress.

Genotoxic damage and apoptosis in rat glioma (F98) cell line following exposure to bromuconazole.

Bromuconazole, a fungicide from the triazole family, is widely used to protect the crop from various fungal contaminations to increase product quality and productivity. Although the massive use of bromuconazole poses a serious risk to human health, the exact mechanism of bromuconazole toxicity, especially on brain support cells, called glia cells, remains unclear so far. This study aimed to determine the mechanism of cytotoxicity and genotoxicity of bromuconazole via inspection of apoptotic death in rat glioma (F98) cells. We observed that bromuconazole treatment caused concentration-dependent cell death with an IC50 of 60 µM, and disruption of the cytoskeleton was observed via immunocytochemical analysis. Further, bromuconazole inhibits cell proliferation, it arrests the cell cycle in the G0/G1 phase and so inhibits DNA synthesis. Genotoxic analysis showed that bromuconazole exposition causes DNA fragmentation (comet assay) and nuclear condensation (DAPI staining). Apoptotic cell death was confirmed through: positive Annexin-V/FITC-PI dyes, p53 and Bax overexpression, Bcl2 repression, an increase in Bax/BCL-2 ratios of the mRNA, mitochondrial membrane depolarization, and an increase of caspase-3 activity. All these results demonstrate that bromuconazole exerts its cytotoxic and genotoxic effects through apoptotic cell death, which could implicate mitochondria.

Bromuconazole fungicide induces cell cycle arrest and apoptotic cell death in cultured human colon carcinoma cells (HCT116) via oxidative stress process.

BACKGROUND: Bromuconazole, a fungicide belonging to the triazole family, is a plant protection product used to control, repel or destroy fungi that may develop on crops. We investigated the pro-apoptotic effect of bromuconazole and the role of oxidative stress in the death mechanism induced by this fungicide in this study. METHODS: The human colon HCT116 cell line was treated with Bromuconazole (IC50/4, IC50/2, and IC50) for 24 h. Cells were collected and analysed for biomarkers of apoptotic cell death and oxidative stress as well as for the assessment of genotoxic damage. RESULTS: Our study showed that bromuconazole caused a concentration-dependent increase in cell mortality with an IC50 of 180 µM. Bromuconazole induced cell cycle arrest in the G0/G1 phase and DNA synthesis inhibition. The Comet assay showed that bromuconazole caused DNA damage in a concentration-dependent manner. Bromuconazole-induced apoptosis was observed by, Annexin-V/FITC-PI and BET/AO staining, by mitochondrial membrane depolarisation, and by increased caspase-3 activity. In addition, bromuconazole induced a significant increase in ROS and lipid peroxidation levels and a disruption in SOD and CAT activities. N-acetylcysteine (NAC) strongly prevents cytotoxic and genotoxic damage caused by bromuconazole. CONCLUSION: Bromuconazole toxicity was through the oxidative stress process, which causes DNA damage and mitochondrial dysfunction, leading to cell cycle arrest and apoptotic death of HCT116 cells.

Bromuconazole exposure induced cell cycle arrest in the G0/G1 in HCT116 cells.Bromuconazole caused DNA synthesis inhibition and degradation.Bromuconazole-induced Annexin-V/FITC-PI and BET/AO positive staining, increased caspase-3 activity and MMP.Bromuconazole enhances ROS, MDA levels and disruption of CAT and SOD activities.

Evaluation of hepatotoxicity and nephrotoxicity induced by fenpyroximate in subchronic-orally exposed Wistar rats.

BACKGROUNDS: Fenpyroximate (FEN) is an acaricide that inhibits the complex I of the mitochondrial respiratory chain. The aim of this work was to explore the hepatotoxic and nephrotoxic effects of FEN on Wistar rats. METHODS: The study involved five groups: a control group and four groups treated with FEN at 1, 2, 4, and 8 mg/Kg bw for 28 consecutive days. Histological examination and biochemical analysis of hepatic and renal biomarkers were performed. The malondialdehyde (MDA), protein carbonyl levels, and antioxidant enzymes activities were measured. Comet assay was conducted to explore FEN genotoxicity. RESULTS: FEN induced a disturbance of the hepatic and renal functions as evidenced by an increase in AST, ALT, ALP, creatinine, and uric acid levels and histopathological modifications in the two examined tissues. FEN increased hepatic and renal lipid peroxidation and protein oxidation. The activities of liver and kidney SOD, CAT, GPX, and GST are increased significantly in FEN-treated rats at doses of 2 and 4 mg/kg bw. However, with the dose of 8 mg/kg bw of FEN, these activities are decreased. Moreover, FEN increased DNA damage in a dose-dependent manner. CONCLUSION: FEN was hepatotoxic and nephrotoxic very likely through induction of oxidative stress.

Fenpyroximate induced cytotoxicity and genotoxicity in Wistar rat brain and in human neuroblastoma (SH-SY5Y) cells: Involvement of oxidative stress and apoptosis.

Fenpyroximate (FEN) is an acaricide used in agriculture / horticulture to control spider mites and leafhoppers. It inhibits the transport of mitochondrial electrons at the level of NADH-coenzyme Q oxidoreductase (complex I). Despite the implication of inhibition of mitochondrial complex I in neurotoxicity, especially in neurodegenerative diseases, data concerning FEN neurotoxicity remain limited. Thus, the present study was designed to investigate the toxic effect of FEN on rat brain tissue and on human neuroblastoma cells (SH-SY5Y). Rat exposure to FEN at three different doses (4.8, 9.6 and 48 mg / Kg bw) for 28 consecutive days resulted in histopathological modifications in brain tissue and a significant decrease in acetylcholinesterase activity. Further, FEN significantly enhanced lipid peroxidation and protein oxidation in rat brain and disturbed activities of antioxidant enzymes (SOD, CAT, GPx, and GST). Besides, FEN was found to induce DNA damage in a significant and dose-dependent manner in rat brain as assessed by the comet assay. To better understand FEN neurotoxic effect, we monitored our study on SH-SY5Y cells. We confirm our data found in rat brain tissue. In fact, FEN induced cell mortality in a concentration dependent manner. It over-produced intracellular ROS and lipid peroxidation and enhanced SOD and CAT activities. FEN was also found to induce DNA damage in SH-SY5Y cells. Moreover, FEN induced a loss of mitochondrial membrane potential, which confirms FEN mitochondrial impairing activity. Acridine Orange-Bromure Etidium (AO-BE) cell staining indicated that FEN enhanced the percentage of apoptotic cells in a concentration dependent manner. Further, pretreatment with a general caspases inhibitor (ZVAD-FMK), reduced significantly the FEN induced cell mortality. We also shown that FEN increased caspase 3 activity. These findings suggested, for the first time, the possibility of the involvement of mitochondrial pathway in FEN-induced cell apoptosis.

Epoxiconazole caused oxidative stress related DNA damage and apoptosis in PC12 rat Pheochromocytoma.

Epoxiconazole is among the most widely applied pesticides worldwide. The increased use of these products could cause toxic effects on human health which are mainly associated with its residues in food or occupational exposure in agriculture. The brain is the principal target of lipophilic compounds exposure, while the data of brain injury induced by Epoxiconazole remains unclear. The purpose of our investigation was to assess the cytotoxic and genotoxic effects of the epoxiconazole in rat Pheochromocytoma (PC 12). We found that epoxiconazole could reduce the viability and proliferation of PC12 cells, induce the DNA damage, nuclear condensation, cytoskeleton network disruption and enhance the apoptotic cell death. Intracellular biochemical assay proved that EPX induces the loss of mitochondrial membrane potential (ΔΨm) and activates caspase-3. Indeed, EPX instigated ROS generation in neuronal cells, which is accompanied by an increase of lipid peroxidation as confirmed by the high levels of MDA. Interestingly, Pre-treatment of PC12 cells with the ROS scavenger N-acetylcysteine mitigated EPX-provoked DNA fragmentation and enhancement of apoptosis. Our results demonstrate that the genotoxic and cytotoxic outcomes of EPX are mediated through a ROS-dependent pathway in PC12 cells.

The mycotoxin zearalenone enhances cell proliferation, colony formation and promotes cell migration in the human colon carcinoma cell line HCT116.

Zearalenone (ZEN) and Aflatoxin B1 (AFB1) are fungal secondary metabolites produced by Fusarium and Aspergillus genera, respectively. These mycotoxins are found world-wide as corn and wheat contaminants. AFB1 is probably the most toxic and carcinogenic mycotoxin. It has been demonstrated to be mutagenic, genotoxic, and hepatocarcinogenic. ZEN is a non-steroidal estrogenic mycotoxin that displays hepatotoxicity, immunotoxicity and genotoxicity. Its mutagenic and carcinogenic properties have so far remained controversial and questionable. Using the colon carcinoma cell line HCT116, we will show here that ZEN, at low concentrations, enhances cell proliferation, increases colony formation and fastens cell migration after wound healing. The highest effect of ZEN was observed at a concentration 10 times lower as compared to AFB1. Our findings suggest thus that this mycotoxin exhibits carcinogenesis-like properties in HCT116 cells.

Ochratoxin A and T-2 Toxin Induce Clonogenicity and Cell Migration in Human Colon Carcinoma and Fetal Lung Fibroblast Cell Lines.

T-2 toxin and Ochratoxin A (OTA) are toxic secondary metabolites produced by various fungi, and together they contaminate feedstuffs worldwide. T-2 toxin and OTA may exert carcinogenic action in rodent. Despite the various in vivo experiments, carcinogenicity of these two mycotoxins has not yet been proven for human. In this current study, we proposed to investigate, in Human colon carcinoma cells and fetal lung fibroblast-like cells transfected with MYC, the effect of T-2 toxin and OTA on cell clonogenicity and cell migration. Results of the present investigation showed that T2-toxin as well as OTA has an important clonogenic effect in all cell lines, suggesting that these mycotoxins could promote the transcription of c-myc gene. Furthermore, T-2 toxin and OTA enhanced the migration effect of HCT116 cells at very low concentrations, proposing that these mycotoxins may exhibit carcinogenesis-like properties in the studied cells.

Antioxidant and antigenotoxic role of recombinant human erythropoeitin against alkylating agents: cisplatin and mitomycin C in cultured Vero cells.

Cisplatin (CDDP) and mitomycin C (MMC), two alkylating agents used against various solid tumours, are a common source of acute kidney injury. Thus, strategies for minimizing CDDP and MMC toxicity are of a clinical interest. In this study, we aimed to investigate the protective role of recombinant human erythropoietin (rhEPO) against oxidative stress and genotoxicity induced by CDDP and MMC in cultured Vero cells. Three types of treatments were performed: (i) cells were treated with rhEPO 24 h before exposure to CDDP/MMC (pre-treatment), (ii) cells were treated with rhEPO and CDDP/MMC simultaneously (co-treatment), (iii) cells were treated with rhEPO 24 h after exposure to CDDP/MMC (post-treatment). Our results showed that rhEPO decreased the reactive oxygen species levels, the malondialdehyde levels and ameliorated glutathione (reduced and oxidized glutathione) modulation induced by CDDP and MMC in cultured Vero cells. Furthermore, rhEPO administration prevented alkylating agents-induced DNA damage accessed by comet test. Altogether, our results suggested a protective role of rhEPO, against CDDP- and MMC-induced oxidative stress and genotoxicity, especially in pre-treatment condition.

Role of recombinant human erythropoietin in mitomycin C-induced genotoxicity: analysis of DNA fragmentation, chromosome aberrations and micronuclei in rat bone-marrow cells.

Mitomycin C (MMC) is one of the most effective chemotherapeutic agents. However, during clinical use several side effects may occur. Recombinant human erythropoietin (rhEPO), a glycoprotein that regulates haematopoiesis, has been shown to exert an important cyto-protective effect in many tissues. The aim of this study was to explore whether rhEPO protects against MMC-induced genotoxicity in rat bone-marrow cells. Adult male Wistar rats were divided into six groups of 18 animals each: a control group, a 'rhEPO alone' group, an 'MMC alone' group and three 'rhEPO+MMC' groups (pre-, co- and post-treatment conditions). Our results show that MMC induced a noticeable genotoxic effect in rat bone-marrow cells. rhEPO reduced the effects of MMC significantly in every type of experiment conducted, such as the frequency of micronuclei, the percentage of chromosome aberrations and the level of DNA damage measured with the comet assay. The protective effect of rhEPO was more efficient when it was given 24h prior to MMC treatment.

Antioxidative and antigenotoxic effect of vitamin E against patulin cytotoxicity and genotoxicity in HepG2 cells.

Patulin (PAT) is a mycotoxin produced in fruits, mainly in apples, by certain species of Penicillium, Aspergillus, and Byssochlamys. It has been shown that PAT is cytotoxic, genotoxic, and mutagenic in different cell types. Several studies incriminate the oxidative stress as a mechanism of PAT-mediated toxicity. In this context, our aim was to investigate the protective role of Vitamin E (Vit E), an antioxidant agent, against PAT induced cytotoxicity and genotoxicity in cultured HepG2 cells. The obtained results showed that addition of Vit E in cells treated with PAT significantly reduce cell mortality induced by this toxin. In the same conditions, Vit E decreased the intracellular level of ROS, reduced PAT induced p53 expression, and reversed PAT induced DNA damage. In addition, Vit E prevented significantly the percentage of chromosome aberrations induced by PAT in HepG2 cells in a concentration dependant manner. These results suggest that Vit E, an exogenous antioxidant agent, plays an important role in defense against PAT-induced cytotoxicity and genotoxicity, which confirms the involvement of oxidative stress in the induction of DNA damage by PAT in HepG2 cells.

Protective effect of recombinant human erythropoeitin against cisplatin cytotoxicity and genotoxicity in cultured Vero cells.

Cisplatin is an effective agent against various solid tumors. Despite its effectiveness, the dose of cisplatin that can be administered is limited by its nephrotoxicity. Therefore, strategies for minimising the toxicity of cisplatin are of a clinical interest. The aim of this study was to investigate the protective effect of recombinant human erythropoietin (rhEPO) against the cytotoxicity and apoptosis induced by cisplatin in cultured Vero cells. Three types of treatments were performed: (i) cells were treated with rhEPO 24 h before exposure to cisplatin (pre-treatment), (ii) cells were treated with rhEPO and cisplatin simultaneously (co-treatment), (iii) cells were treated with rhEPO 24 h after exposure to cisplatin (post-treatment). Our results showed that rhEPO reduced cisplatin-induced cell mortality. Besides, rhEPO administration prevented cisplatin-induced DNA damage. Furthermore, rhEPO decreased the caspase-3 activity and pro-apoptotic factors levels (p53 and Bax) induced by cisplatin. It increased also the expression of the anti-apoptotic factor Bcl2 in Vero cells. Altogether, our results suggest a protective action of rhEPO against cisplatin cytotoxicity and genotoxicity via an anti-apoptotic process. The most protective effect was observed with rhEPO when it was administrated 24 h before cisplatin treatment.

Induction of DNA fragmentation, chromosome aberrations and micronuclei by cisplatin in rat bone-marrow cells: protective effect of recombinant human erythropoietin.

Cisplatin (Cisp) is one of the most effective chemotherapeutic agents. However, at higher doses several side effects may occur. Recombinant human erythropoietin (rhEPO), a glycoprotein regulating haematopoiesis, has recently been shown to exert an important cyto-protective effects in many tissues. The purpose of this study was to explore whether rhEPO protects against Cisp-induced genotoxicity in rat bone-marrow cells. Adult male Wistar rats were divided into six groups of 18 animals each: control group, rhEPO-alone group, Cisp-alone group and three rhEPO+Cisp-groups (pre-, co- and post-treatment condition, respectively). Our results show that Cisp induced a noticeable genotoxic effect in rat bone-marrow cells. In all types of treatment, rhEPO significantly decreased the frequency of micronuclei, the percentage of chromosome aberrations and the level of DNA damage. The protective effect of rhEPO was more efficient when it was administrated 24h before exposure to Cisp.

Ochratoxin A induces CYP3A4, 2B6, 3A5, 2C9, 1A1, and CYP1A2 gene expression in primary cultured human hepatocytes: a possible activation of nuclear receptors.

Ochratoxin A (OTA) is a mycotoxin produced by fungi of two genera: Penicillium and Aspergillus. OTA has been shown to be nephrotoxic, hepatotoxic, teratogenic, and immunotoxic to several species of animals and to cause kidney and liver tumors in mice and rats. Biotransformation of OTA has not been entirely elucidated. Several metabolites have been characterized in vitro and/or in vivo, whereas other metabolites remain to be characterized. At present, data available regarding OTA metabolism and cytochrome inductions concern only rodents or in vitro systems. The aim of the present study was to explore the effect of OTA on mRNA expression of some cytochromes known to be regulated by pregnane X receptor (PXR), constitutive androstane receptor (CAR), and aryl hydrocarbon receptor (AhR), using primary cultures of human hepatocytes. Our results showed that OTA reduced hepatocyte viability in a dose-dependent manner. Using quantitative real-time reverse-transcription polymerase chain reaction, our study showed that treatment of primary cultured human hepatocytes with noncytotoxic increasing concentrations of OTA for 24 hours caused a significant upregulation of CYP3A4, CYP2B6, and, to a lesser extent, CYP3A5 and CYP2C9. PXR mRNA expression increased in only 1 treated liver, whereas CAR mRNA expression was not affected. OTA was found also to induce an overexpression of CYP1A1 and CYP1A2 genes accompanied by an increase in AhR mRNA expression. These findings suggest that OTA could activate PXR and AhR; however, further investigations are needed to confirm nuclear-receptor activation by OTA.

Recombinant human erythropoietin prevents cisplatin-induced genotoxicity in rat liver and heart tissues via an antioxidant process.

Cisplatin (Cisp) is one of the most effective chemotherapeutic agents. However, at higher doses, liver and heart injuries may occur. Recombinant human erythropoietin (rhEPO) has recently been shown to exert an important cytoprotective effect in many tissues. For that reason, we tried to check the protective effect of rhEPO against Cisp-induced genotoxicity and oxidative stress in liver and heart tissues. Our experiments were performed using six groups of adult male Wistar rats. The control group was treated only with saline solution. The rhEPO group was given a single dose of rhEPO. The Cisp group was given a single injection of Cisp. The rhEPO+Cisp groups were given rhEPO simultaneously, 24 hours before, and 5 days after Cisp injection. Our results clearly showed that Cisp induced noticeable DNA damage in the liver and heart, accompanied by a significant increase in protein carbonyl level, reduced glutathione (GSH) depletion, and a decrease in catalase activity. Rats treated with rhEPO, simultaneously, before, or after Cisp injection, remarkably decreased DNA damage. It decreased also the protein carbonyl level, restored GSH depletion, and enhanced catalase activity. Our results highlight an interesting cytoprotective strategy using rhEPO against Cisp-induced liver and heart injuries.

Protective effect of erythropoietin against cisplatin-induced nephrotoxicity in rats: antigenotoxic and antiapoptotic effect.

Cisplatin (Cisp) is an active cytotoxic agent that was found efficient in the treatment of various types of solid tumors. Its nephrotoxic effect has been very well documented in clinical oncology. Erythropoietin (EPO), a renal cytokine-regulating hematopoiesis, has recently been shown to exert important cytoprotective effects in many experimental injuries. The aim of this study was to explore whether EPO would protect against Cisp-induced apoptosis in rat kidney. Adult Wistar rats were treated with saline solution as the control group, Cisp alone, EPO alone, or EPO with Cisp in different treatments: 1) EPO and Cisp simultaneously administrated to animals as a cotreatment; 2) EPO administered 24 hours before Cisp as a pretreatment; and 3) EPO administered 5 days after Cisp injection as a post-treatment. Our results have shown that Cisp induced renal failure, characterized with a significant increase in serum creatinine and blood urea nitrogen (BUN) concentrations. Cisp promoted kidney DNA fragmentation and apoptotic cell death. Apoptosis was revealed by an enhancement of proapoptotic protein (e.g., p53 and Bax) levels, decrease in antiapoptotic proteins (e.g., Bcl2 and Hsp27), and increase in caspase-3 activity. Treatments with EPO restored creatinine and BUN levels and inhibited Cisp-induced DNA damage in the kidney. Apoptosis was also reduced by the upregulation of antiapoptotic protein expressions, downregulation of proapoptotic protein levels, and reduction of caspase-3 activity.

Genotoxicity associated with oxidative damage in the liver and kidney of mice exposed to dimethoate subchronic intoxication.

BACKGROUND AND AIMS: Because of the widespread use of pesticides for domestic and industrial applications, the evaluation of their toxic effects is of major concern to public health. The aim of the present study was to investigate the propensity of dimethoate (DM), an organophosphorus pesticide, to cause oxidative damage in the liver and kidney of mice and its associated genotoxic effect. METHODS: DM was administered intraperitoneally at doses of 1, 5, 10, 15, and 30 mg/kg body weight for 30 consecutive days in BALB/c mice. Oxidative stress was monitored in the kidney and liver by measuring malondialdehyde level, protein carbonyl concentration, and the catalase activity. The genotoxicity of DM was assessed by the comet assay in vivo. RESULTS AND DISCUSSION: Our results indicated that DM inhibited acetylcholinesterase activities in the liver and kidney of treated mice. DM increased lipid peroxidation and protein carbonyl levels in the liver and kidney in a dose-dependent manner. Catalase activity was found to be significantly increased in the liver and kidney at doses higher than 5 mg/kg body weight. CONCLUSIONS: Our study demonstrated that DM induced DNA damage in the liver and kidney of treated mice in a dose-dependent manner; this induction was associated to DM-induced oxidative stress. Further investigations are needed to prove the implication of oxidative stress in genotoxicity induced by DM.

Effect of aflatoxin B1 on nuclear receptors PXR, CAR, and AhR and their target cytochromes P450 mRNA expression in primary cultures of human hepatocytes.

Aflatoxin B1 (AFB1), one of the most common mycotoxins found in human foods and animal feed, is principally hepatotoxic and hepatocarcinogenic. The aim of the present study was to explore the effect of AFB1 on messenger RNA (mRNA) expression of pregnane X receptor (PXR), constitutive androstane receptor (CAR), and aryl hydrocarbon receptor (AhR) and some of their target cytochromes using primary cultures of human hepatocytes. Our results showed that AFB1, at noncytotoxic increasing concentrations, caused a significant upregulation of cytochrome P 2B6 (CYP2B6), CYP3A5, and to a lesser extent CYP3A4 and CYP2C9. Pregnane X receptor and CAR mRNA expression increased in the 3 treated livers. Aflatoxin B1 was found also to induce an overexpression of CYP1A1 and CYP1A2 genes accompanied by an increase in AhR mRNA expression. These findings suggest that AFB1 could activate PXR, CAR, and AhR; however, further investigations are needed to confirm nuclear receptor activation by AFB1.

Genotoxicity evaluation of dimethoate to experimental mice by micronucleus, chromosome aberration tests, and comet assay.

Dimethoate (DM) is an organophosphate insecticide with numerous uses on field and agricultural crops and ornamentals. Data concerning DM-acute genotoxicity are controversial and knowledge on its delayed effect is limited. For this reason, we aimed to further explore DM genotoxicity resulting from subchronic intoxication of experimental mice. Thus, DM was administered to mice at doses ranging from 1 to 30 mg/kg body weight for a period of 30 consecutive days. There was a significant increase (P < .05) in the frequency of micronucleated bone marrow cells following DM administration. Furthermore, the chromosome aberration assay revealed a significant increase in the percentage of chromosome abnormalities in a dose-dependent manner. Dimethoate was also found to induce significant DNA damage in mouse bone marrow cells as assessed by the comet assay. Altogether, our results showed that, after a subchronic exposure, DM was a genotoxic compound in experimental mice.