The role of mitochondrial and oxidative injury in BDE 47 toxicity to human fetal liver hematopoietic stem cells.

The polybrominated diphenyl ethers (PBDEs) are a group of flame retardants whose residues have markedly increased in the environment and in human tissues during the last decade. Of the various congeners, BDE 47 (2,2',4,4'-tetrabromodiphenyl ether) is typically the predominant congener observed in fish and wildlife samples, as well as in human tissues. Several studies indicate in utero transfer of PBDEs during pregnancy with residues accumulating in fetal tissues, and thus the potential for BDE 47-mediated injury in utero is of concern. In this study, we examined the mechanisms of BDE 47-mediated injury to primary human fetal liver hematopoietic stem cells (HSCs), which comprise a large proportion of fetal hepatic cells and play a key role in hematopoiesis during fetal development. Incubation of fetal liver HSCs with BDE 47 led to a loss of mitochondrial membrane potential and the onset of apoptosis. These effects were observed in the low micromolar range of BDE 47 exposures. At higher concentrations, BDE 47 elicited a loss of viability, which was accompanied by the generation of reactive oxygen species and peroxidation of HSC lipids. Preincubation of fetal liver HSCs with N-acetylcysteine, a glutathione (GSH) precursor, caused an increase in cellular GSH concentrations, restored mitochondrial redox status, and ameliorated the toxicity of BDE 47. BDE 47-mediated cytotoxicity or oxidative injury was not evident at the lower concentrations (< 1microM). Collectively, these data support a role for oxidative stress in the cytotoxicity of BDE 47 and indicate that oxidative stress-associated biomarkers may be useful in assessing the sublethal effects of BDE 47 toxicity in other models. However, the fact that BDE 47 undergoes a concentration-dependent accumulation in other primary cells in media that can underestimate cellular concentrations (W. R. Mundy et al., 2004, Toxicol. Sci. 82, 164-169) suggests that the HSC cell injury observed in our study may be of less relevance to human in utero PBDE exposures.     

慢性铅暴露对大鼠脑组织 XRCC1 mRNA 表达的影响及其与氧化应激的关系

目的 观察饮水铅暴露对大鼠大脑皮质、 小脑、 海马组织中 X 线交错互补修复基因 1（XRCC1）mRNA 表达的影响及其与氧化应激的关系。方法 40 只 SD 大鼠根据体质量按随机区组法分对照组和 4 个铅暴露组： 最低剂量组、 低剂量组、 中剂量组、 高剂量组, 对照组自由饮用去离子水, 4 个铅暴露组分别饮用 100、 200、 400、 800 mg/L 的醋酸铅溶液, 连续染毒 60 d 后取大脑皮质、 小脑和海马。RT-PCR 技术检测脑组织 XRCC1 mRNA 的表达量, 并测定脑组织铅、 过氧化氢酶 （CAT）、 谷胱甘肽 （GSH） 和过氧化氢 （H2O2） 的含量。结果 与对照组比较, 铅暴露组大鼠大脑皮质、 小脑和海马中 XRCC1 mRNA 表达量、 脑铅的含量和 H2O2水平均升高(P＜0.05); 而 CAT、 GSH 含量基本低于对照组 （P < 0.05）; 相关性分析显示铅暴露组大鼠大脑皮质、 小脑和海马中 XRCC1 mRNA 表达量与脑组织铅含量呈正相关(r 分别为 0.608、 0.438、 0.470, P＜0.01), 与 CAT、 GSH 呈负相关 （r 分别为-0.343、 -0.465、 -0.423, -0.383、 -0.489、 -0.366, P＜0.05）, 与 H2O2 呈正相关(r 分别为 0.455、 0.517、 0.342, P＜0.05)。结论 铅可通过诱导细胞氧化应激而影响 XRCC1 mRNA 的表达。     

Role of glutathione redox cycle and catalase in defense against oxidative stress induced by endosulfan in adrenocortical cells of rainbow trout (Oncorhynchus mykiss)

The role of antioxidants in maintaining the functional integrity of adrenocortical cells during in vitro exposure to endosulfan, an organochlorine pesticide, was investigated in rainbow trout (Oncorhynchus mykiss). Aminotriazole (ATA), an inhibitor of catalase (CAT), L-buthionine sulfoximine (L-BSO), an inhibitor of glutathione (GSH) synthesis, and N-acetyl cysteine (NAC), a glutathione precursor, were used to investigate the role of CAT and GSH redox cycle in protection against the adrenal toxicity of endosulfan, a pesticide that impairs cell viability (LC50 366 microM) and cortisol secretion (EC50 19 microM) in a concentration-related manner. Pretreatment with ATA and L-BSO enhanced the toxicity of endosulfan (LC50 and EC50, respectively, 302 and 2.6 microM with ATA, 346 and 3.1 microM with L-BSO), while pretreatment with NAC had no significant effect on cell viability and increased the EC50 of endosulfan to 51 microM. CAT activity was significantly reduced following exposure to endosulfan when cells were pretreated with ATA. Pretreatment with L-BSO significantly decreased glutathione peroxidase (GPx) activity and reduced glutathione (GSH) levels in a concentration-related manner following exposure to endosulfan, while GSH levels were significantly higher in NAC pretreated cells compared to untreated cells. Finally, pretreatment with ATA and L-BSO increased, while pretreatment with NAC decreased, lipid hydroperoxides (LOOH) levels. CAT, GPx, and GSH were identified as important antioxidants in maintaining the function and integrity of rainbow trout adrenocortical cells and ATA, L-BSO, and NAC were identified as effective modulators of CAT and GSH redox cycle. Moreover, this study suggests that the glutathione redox cycle may be more efficient than catalase in protecting adrenocortical cells against endosulfan-induced oxidative stress.     

Epigenetic modification of H3K4 and oxidative stress are involved in MC‐LR‐induced apoptosis in testicular cells of SD rats

Microcystin‐leucine arginine (MC‐LR) is a cyclic heptapeptide, produced by aquatic cyanobacteria such as microcystis, with strong reproductive toxicity which poses greater threat to the reproductive abilities of humans and animals. By exploring the role of trimethylation of histone H3 at lysine 4 (H3K4me3) and the role of oxidative stress in MC‐LR‐induced apoptosis in testicular Sertoli cells in Sprague‐Dawley (SD) rats, this study indicated that MC‐LR increased the expression levels of apoptosis‐related genes by raising the levels of H3K4me3. 5′‐Deoxy‐5′‐methylthioadenosine (MTA), the inhibitor of H3K4me3, reduced apoptosis, indicating for the first time that epigenetic modification is closely related to the testicular reproductive toxicity induced by MC‐LR. MC‐LR also induced oxidative stress by stimulating the generation of reactive oxygen species (ROS), and subsequently triggering mitochondria‐mediated apoptotic pathway by decreasing mitochondrial membrane potential and increasing the levels of Bax, Bcl‐2, Caspase‐3, and so on. MC‐LR‐induced apoptosis of testicular cells could be decreased after pretreatment with oxidative stress inhibitor N‐acetyl‐cysteine (NAC). Furthermore, the pathological damage to mitochondria and testes were observed in SD rats. These results show that MC‐LR can induce apoptosis by raising the levels of H3K4me3, and pretreatment with MTA can ameliorate the MC‐LR‐induced apoptosis of cocultured cells by lowering the levels of H3K4me3. Furthermore, NAC has a protective effect on MC‐LR‐induced apoptosis of testicular cells in SD rats by inhibiting the oxidative stress.     

Cytoprotective effects of CSTMP, a novel stilbene derivative, against H2O2-induced oxidative stress in human endothelial cells

A novel stilbene derivative, (E)-2-(2-chlorostyryl)-3,5,6-trimethylpyrazine (CSTMP), was designed and synthesized based on the pharmacophores of tetramethylpyrazine (TMP) and resveratrol (RES). In the present study, we investigated the protective effects of CSTMP on vascular endothelial cells under oxidative stress and elucidated its molecular mechanisms. The radical scavenging activity of CSTMP was assessed by the DPPH test. Human Umbilical Vein Endothelial Cells (HUVECs) were exposed to 150 μM hydrogen peroxide (H(2)O(2)) for 12 h, resulting in a decrease of cell viability assessed by the MTT assay and an increase of apoptotic cells assessed by the nuclear staining assay and flow cytometry. The activities of lactate dehydrogenase (LDH), superoxide dismutase (SOD) and nitric oxide synthase (NOS) and the contents of malondialdehyde (MDA), reduced glutathione (GSH) and nitric oxide (NO) in cells were determined by commercial kits. The expression levels of pro-apoptotic factor caspase-3 and anti-apoptotic signal ERK1/2 were detected by western blot. The results showed that CSTMP had a moderate anti-oxidative effect against the DPPH test, which was less than RES. Co-incubation with CSTMP increased the cell viability, markedly reduced the LDH leakage from the cells and decreased the lipid peroxidation. These effects of CSTMP were accompanied by increasing activity of the endogenous antioxidant enzyme SOD, the level of GSH, the production of NO and cNOS activity. Moreover, CSTMP showed stronger effects on the inhibition of apoptosis, caspase-3 expression, and the activation of phosphorylated ERK1/2 compared to RES. Furthermore, CSTMP could inhibit the expression of phospho-JNK and phospho-p38 induced by H(2)O(2). These results suggest that CSTMP prevents H(2)O(2)-induced cell injury through anti-oxidation and anti-apoptosis via the MAPK and caspase-3 pathways.     

Platinum nanoparticles induced genotoxicity and apoptotic activity in human normal and cancer hepatic cells via oxidative stress‐mediated Bax/Bcl‐2 and caspase‐3 expression

Platinum nanoparticles (PtNPs) attract much attention due to their excellent biocompatibility and catalytic properties, but their toxic effects on normal (CHANG) and cancerous (HuH‐7) human liver cells are meagre. The cytotoxic and apoptotic effects of PtNPs (average size, 3 nm) were determined in CHANG and HuH‐7 cells. After treating these cells were with PtNPs (10, 50, 100, 200, and 300 μg/mL) for 24 and 48 hours, we observed dose‐ and time‐dependent cytotoxicity, as evaluated by using (3‐[4, 5‐dimethylthiazol‐2‐yl]‐2, 5‐diphenyltetrazolium bromide, a tetrazole) (MTT) and neutral red uptake (NRU) assays. The production of reactive oxygen species (ROS) was increased in both cells after treatment with the above dose of PtNPs for 24 and 48 hours. Determination of morphological changes of cells, chromosome condensation, mitochondrial membrane potential, and caspase‐3 assays showed that PtNPs induce cytotoxicity and apoptosis in CHANG and HuH‐7 cells by altering the cell morphology and density, increasing cell population in apoptosis, and causing chromosome condensation. Furthermore, we have studied fragmentation of DNA using alkaline single cell gel electrophoresis and expression of apoptotic genes by real‐time PCR (RT‐PCR). The percentage of DNA fragmentation was more at 300 μg/mL for 48 hours in both cells, but slightly more fragmentation was found in HuH‐7 relative to CHANG cells. Considering all of the above parameters, PtNPs elicited cytotoxicity on CHANG and HuH‐7 cells by blocking cell proliferation and inducing apoptosis. Thus this study may be useful in in vitro laboratory studies using cell lines for screening the genotoxic and apoptotic potential of nanoparticles.     

Di(2-ethylhexyl)phthalate-induced renal oxidative stress in rats and protective effect of selenium

This study was designed to examine the oxidative stress potential of di(2-ethylhexyl)phthalate (DEHP) on rat kidney and to evaluate possible protective effect of selenium (Se) status. Se deficiency (SeD) was produced in 3-week old Sprague?Dawley rats by feeding them ≤ 0.05 Se mg/kg diet for 5 weeks; Se supplementation group (SeS) was on 1 mg Se/kg diet. DEHP treated groups received 1000 mg/kg dose by gavage during the last 10 days of the feeding period. Activities of antioxidant selenoenzymes [glutathione peroxidase 1 (GPx1), glutathione peroxidase 4 (GPx4), thioredoxin reductase (TrxR)], catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST); concentrations of total glutathione (GSH), thiols and thiobarbituric acid reactive substance (TBARS) levels were measured. DEHP treatment was found to induce oxidative stress in rat kidney, as evidenced by significant decreases in GPx1 (~20%) and SOD (~30%) activities and GSH levels (~20%), along with marked decrease in thiol content (~40%) and increase in TBARS (~30%) levels. The effects of DEHP was more pronounced in SeD rats, whereas Se supplementation was protective by providing substantial elevations of GPx1 and GPx4 activities and GSH levels. These findings emphasized the critical role of Se as an effective redox regulator and the importance of Se status in protecting renal tissue from the oxidant stressor activity of DEHP.     

Liv.52 attenuate copper induced toxicity by inhibiting glutathione depletion and increased antioxidant enzyme activity in HepG2 cells

Altered copper metabolism plays a pivotal role in the onset of several hepatic disorders and glutathione (GSH) plays an important role in its homeostasis. Hepatic diseases are often implicated with decreased content of intracellular GSH. GSH depleted cells are prone to increased oxidative damage eventually leading to its death. Liv.52 is used to treat hepatic ailments since long time. Hence, in the present study the potential cytoprotective effect of Liv.52 against toxicity induced by copper (Cu²⁺) was evaluated in HepG2 cells. Cu²⁺ at 750 μM induced cytotoxicity to HepG2 cells as determined by MTT assay. The toxicity was brought about by increased lipid peroxidation, DNA fragmentation and decreased GSH content. But, upon treatment with Liv.52 cell death induced by Cu²⁺ was significantly abrogated by inhibition of lipid peroxidation by 58% and DNA fragmentation by 37%. Liv.52 increased the GSH content by 74%. Activities of the antioxidant enzymes catalase, glutathione peroxidase and superoxide dismutase were increased by 46%, 22% and 81% respectively in Liv.52 treated cells. Thus, it is apparent from these results that Liv.52 abrogates Cu²⁺ induced cytotoxicity in HepG2 cells by inhibiting lipid peroxidation and increased GSH content and antioxidant enzyme activity.     

In Vitro Studies on the Antioxidant and Protective Effect of 2-Substituted -8-Hydroxyquinoline Derivatives Against H2O2-Induced Oxidative Stress in BMSCs

Novel 2-vinyl-8-hydroxyquinoline derivatives as potential antioxidants and regulators of H₂O₂-induced oxidative stress in rat bone marrow mesenchymal stem cells (MSCs) are first reported. The antiradical properties and the reducing power of these compounds were assessed using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and auto-oxidation of pyrogallol method, respectively. The activity against lipid peroxidation was determined using ammonium thiocyanate method. The results revealed that introduction of electron-donating groups at 2nd position decreased the antioxidant activities of 8-hydroxyquinoline derivatives. In addition, compound 4 , the structure of which is similar to melatonin, exhibited superior antioxidant activities in scavenging DPPH free radical, ˙O₂ free radical, and anti-LPO activities. Except for compounds 7 , 12 , and 15 , the other compounds exhibited a stimulatory effect on MSCs growth. Using hydrogen peroxide (H₂O₂), we also investigated the protective efficacy of 2-vinyl-8-hydroxyquinoline derivatives against oxidative stress-induced cell death of MSCs. Cell viability assayed by MTT method indicated that exposure of MSCs cultures to hydrogen peroxide resulted in a concentration-dependent decrease in cell viability, and compounds 4 and 5 at given concentration (2.62 × 10⁻³ m ) could protect MSCs against H₂O₂-induced oxidative stress in bone mesenchymal stem cell (BMSCs).     

Development of enzyme-linked immunosorbent assay for 8-iso-prostaglandin F2α, a biomarker of oxidative stress in vivo, and its application to the quantification in aged rats

8-iso-Prostaglandin F_2α (8-iso-PGF_2α) is one of the isoprostanes that are mainly generated nonenzymatically in vivo from arachidonic acid through free radical-induced lipid peroxidation. To assess oxidative stress in vivo, we developed a quantitative enzyme-linked immunosorbent assay (ELISA) for 8-iso-PGF_2α. A sensitive calibration curve allowed the quantification of the amounts from 0.23 pg to 98.4 pg with 4.7 pg of 50% displacement in one assay. The ELISA method was applied to the measurement of the plasma levels of 8-iso-PGF_2α in young rats (4–8 weeks of age) and aged rats (106–123 weeks). The average level of esterified form in the plasma from aged rats was 30.6-fold higher than that in the plasma from young rats, reflecting the enhanced status of oxidative stress in aged animals. In addition, the aged rats exhibited higher levels of this F₂-isoprostane esterified to lipids from liver and kidney, suggesting local oxidative injury in specific organs. These results indicate the utility and accuracy of our ELISA for 8-iso-PGF_2α as a biomarker in vivo to assess systemic oxidative stress in animals or humans as well as oxidative injury at local sites.     

Effects of di(2‐ethylhexyl)phthalate on testicular oxidant/antioxidant status in selenium‐deficient and selenium‐supplemented rats

Di(ethylhexyl)phthalate (DEHP), the most widely used plasticizer, was investigated to determine whether an oxidative stress process was one of the underlying mechanisms for its testicular toxicity potential. To evaluate the effects of selenium (Se), status on the toxicity of DEHP was further objective of this study, as Se is known to play a critical role in testis and in the modulation of intracellular redox equilibrium. Se deficiency was produced in 3‐weeks‐old Sprague–Dawley rats feeding them ≤0.05 mg Se /kg diet for 5 weeks, and Se‐supplementation group was on 1 mg Se/kg diet. DEHP‐treated groups received 1000 mg/kg dose by gavage during the last 10 days of the feeding period. Activities of antioxidant selenoenzymes [glutathione peroxidase 1 (GPx1), glutathione peroxidase 4 (GPx4), thioredoxin reductase (TrxR)], catalase (CAT), superoxide dismutase (SOD), and glutathione S‐transferase (GST); concentrations of reduced glutathione (GSH), oxidized glutathione (GSSG), and thus the GSH/GSSG redox ratio; and thiobarbituric acid reactive substance (TBARS) levels were measured. DEHP was found to induce oxidative stress in rat testis, as evidenced by significant decrease in GSH/GSSG redox ratio (>10‐fold) and marked increase in TBARS levels, and its effects were more pronounced in Se‐deficient rats with ～18.5‐fold decrease in GSH/GSSG redox ratio and a significant decrease in GPx4 activity, whereas Se supplementation was protective by providing substantial elevation of redox ratio and reducing the lipid peroxidation. These findings emphasized the critical role of Se as an effective redox regulator and the importance of Se status in protecting testicular tissue from the oxidant stressor activity of DEHP. © 2011 Wiley Periodicals, Inc. Environ Toxicol 29: 98–107, 2014.     

Involvement of oxidative stress-mediated ERK1/2 and p38 activation regulated mitochondria-dependent apoptotic signals in methylmercury-induced neuronal cell injury

Methylmercury (MeHg) is well-known for causing irreversible damage in the central nervous system as well as a risk factor for inducing neuronal degeneration. However, the molecular mechanisms of MeHg-induced neurotoxicity remain unclear. Here, we investigated the effects and possible mechanisms of MeHg in the mouse cerebrum (in vivo) and in cultured Neuro-2a cells (in vitro). In vivo study showed that the levels of LPO in the plasma and cerebral cortex significantly increased after administration of MeHg (50 μg/kg/day) for 7 consecutive weeks. MeHg could also decrease glutathione level and increase the expressions of caspase-3, -7, and -9, accompanied by Bcl-2 down-regulation and up-regulation of Bax, Bak, and p53. Moreover, treatment of Neuro-2a cells with MeHg significantly reduced cell viability, increased oxidative stress damage, and induced several features of mitochondria-dependent apoptotic signals, including increased sub-G1 hypodiploids, mitochondrial dysfunctions, and the activation of PARP, and caspase cascades. These MeHg-induced apoptotic-related signals could be remarkably reversed by antioxidant NAC. MeHg also increased the phosphorylation of ERK1/2 and p38, but not JNK. Pharmacological inhibitors NAC, PD98059, and SB203580 attenuated MeHg-induced cytotoxicity, ERK1/2 and p38 activation, MMP loss, and caspase-3 activation in Neuro-2a cells. Taken together, these results suggest that the signals of ROS-mediated ERK1/2 and p38 activation regulated mitochondria-dependent apoptotic pathways that are involved in MeHg-induced neurotoxicity.     

4-hydroxynonenal induces mitochondrial oxidative stress, apoptosis and expression of glutathione S-transferase A4-4 and cytochrome P450 2E1 in PC12 cells

An excessive and sustained increase in reactive oxygen species (ROS) production and oxidative stress have been implicated in the pathogenesis of many diseases. In the present study, we have demonstrated that 4-hydroxynonenal (4-HNE), a product of lipid peroxidation, alters glutathione (GSH) pools and induces oxidative stress in PC12 cells in culture. This increase was accompanied by alterations in subcellular ROS and glutathione (GSH) metabolisms. The GSH homeostasis was affected as both mitochondrial and extramitochondrial GSH levels, GSH peroxidase and glutathione reductase activities were inhibited and glutathione S-transferase (GST) activity was increased after 4-HNE treatment. A concentration- and time-dependent increase in cytochrome P450 2E1 (CYP 2E1) activity in the mitochondria and postmitochondrial supernatant was also observed. 4-HNE-induced oxidative stress also caused an increase in the expression of GSTA4-4, CYP2E1 and Hsp70 proteins in the mitochondria. Increased oxidative stress in PC12 cells initiated apoptosis as indicated by the release of mitochondrial cytochrome c, activation of poly-(ADP-ribose) polymerase (PARP), DNA fragmentation and decreased expression of antiapoptotic Bcl-2 proteins. Mitochondrial respiratory and redox functions also appeared to be affected markedly by 4-HNE treatment. These results suggest that HNE-induced oxidative stress and apoptosis might be associated with altered mitochondrial functions and a compromised GSH metabolism and ROS clearance.     

Endocytosis, oxidative stress and IL-8 expression in human lung epithelial cells upon treatment with fine and ultrafine TiO2: role of the specific surface area and of surface methylation of the particles

Inhaled ultrafine particles show considerably stronger pulmonary inflammatory effects when tested at equal mass dose with their fine counterparts. However, the responsible mechanisms are not yet fully understood. We investigated the role of particle size and surface chemistry in initiating pro-inflammatory effects in vitro in A549 human lung epithelial cells on treatment with different model TiO(2) particles. Two samples of TiO(2), i.e. fine (40-300 nm) and ultrafine (20-80 nm) were tested in their native forms as well as upon surface methylation, as was confirmed by Fourier transformed infrared spectroscopy. Radical generation during cell treatment was determined by electron paramagnetic resonance with 5,5-dimethyl-1-pyrroline-N-oxide or 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl. Interleukin-8 mRNA expression/release was determined by RT-PCR and ELISA, whereas particle uptake was evaluated by transmission electron microscopy. TiO(2) particles were rapidly taken up by the cells, generally as membrane bound aggregates and large intracellular aggregates in vesicles, vacuoles and lamellar bodies. Aggregate size tended to be smaller for the ultrafine samples and was also smaller for methylated fine TiO(2) when compared to non-methylated fine TiO(2). No particles were observed inside nuclei or any other vital organelle. Both ultrafine TiO(2) samples but not their fine counterparts elicited significantly stronger oxidant generation and IL-8 release, despite their aggregation state and irrespective of their methylation. The present data indicate that ultrafine TiO(2), even as aggregates/agglomerates, can trigger inflammatory responses that appear to be driven by their large surface area. Furthermore, our results indicate that these effects result from oxidants generated during particle-cell interactions through a yet to be elucidated mechanism(s).     

Protective effect of zinc supplementation against cadmium-induced oxidative stress and the RANK/RANKL/OPG system imbalance in the bone tissue of rats

It was investigated whether protective influence of zinc (Zn) against cadmium (Cd)-induced disorders in bone metabolism may be related to its antioxidative properties and impact on the receptor activator of nuclear factor (NF)-κΒ (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system. Numerous indices of oxidative/antioxidative status, and Cd and Zn were determined in the distal femur of the rats administered Zn (30 and 60 mg/l) or/and Cd (5 and 50 mg/l) for 6 months. Soluble RANKL (sRANKL) and OPG were measured in the bone and serum. Zn supplementation importantly protected from Cd-induced oxidative stress preventing protein, DNA, and lipid oxidation in the bone. Moreover, Zn protected from the Cd-induced increase in sRANKL concentration and the sRANKL/OPG ratio, and decrease in OPG concentration in the bone and serum. Numerous correlations were noted between indices of the oxidative/antioxidative bone status, concentrations of sRANKL and OPG in the bone and serum, as well as the bone concentrations of Zn and Cd, and previously reported by us in these animals (Brzóska et al., 2007) indices of bone turnover and bone mineral density. The results allow us to conclude that the ability of Zn to prevent from oxidative stress and the RANK/RANKL/OPG system imbalance may be implicated in the mechanisms of its protective impact against Cd-induced bone damage. This paper is the first report from an in vivo study providing evidence that beneficial Zn impact on the skeleton under exposure to Cd is related to the improvement of the bone tissue oxidative/antioxidative status and mediating the RANK/RANKL/OPG system.     

Assessment of oxidative stress responses and the cytotoxic and genotoxic potential of the herbicide tembotrione in HepG2 cells

Tembotrione is a triketone herbicide, usually used for post-emergence weed control in corn. Currently, there is little or no published data on its genotoxicity to human cells either in vitro or in vivo. This study evaluated the impact of acute (4 and 24 h) exposure to low concentrations of tembotrione [corresponding to the acceptable daily intake (0.17 μg/mL), residential exposure level (0.002 μg/mL) and acceptable operator exposure level (0.0012 μg/mL)] on human hepatocellular carcinoma cell line HepG2, using biomarkers of oxidative stress, CCK-8 colorimetric assay for cell viability, alkaline comet assay, and cytokinesis-block micronucleus “cytome” assay. Tembotrione applied at concentrations likely to be encountered in occupational and residential exposures induced cytogenetic outcomes in non-target cells despite non-significant changes in the values of oxidative stress biomarkers. We assume that the observed effects were mainly the consequence of impaired metabolic pathways in HepG2 cells due to the inhibition of the enzyme 4-hydroxyphenyl-pyruvate-dioxygenase by tembotrione, which possibly caused a depletion of folate levels leading to excess formation of nuclear buds in the affected cells. Regardless of the fact that tembotrione was previously reported negative for mutations and chromosome aberrations in vitro, our findings call for more precaution in its use.     

Toxicity and oxidative stress induced by T-2 toxin and HT-2 toxin in broilers and broiler hepatocytes

T-2 and HT-2 toxins belong to mycotoxins which are found in human foods and animal chow. We investigated the toxicity and oxidative stress induced by T-2/HT-2 in broilers and chicken hepatocytes. Maize cultures of Fusarium poae was fed to broilers for 42 d, and the physiological index, biochemical index and expression of mRNAs related to oxidative stress were analyzed. Chicken hepatocytes were treated with different levels of T-2/HT-2, and the following parameters were detected: cell viability, GSH and MDA concentration, LDH leakage, activities of ALT/AST, ROS, GSH-PX, SOD and CAT, and expression of mRNA related to oxidative stress. In vivo, high levels of mycotoxins (4 mg/kg T-2 and 0.667 mg/kg HT-2) in feed caused significant reductions in body weight, weight gain, and serum total protein, and significant increases in feed conversion ratio, ALP, ALT/AST activities, and expression of mRNA related to oxidative stress. In vitro, cells treated with T-2/HT-2 showed reductions of GSH concentration and significant increases in LDH leakage, ALT/AST ROS, GSH-PX, SOD and CAT activities, MDA concentration, and expression of mRNA related to oxidative stress. Consequently, F. poae culture material and T-2/HT-2 induced toxicity and oxidative stress in vivo and in vitro, respectively.