Detection of chemically induced DNA lesions in multiple mouse organs (liver, lung, spleen, kidney, and bone marrow) using the alkaline single cell gel electrophoresis (Comet) assay

Mechanistic insights into acetamiprid-induced genotoxicity on the myocardium and potential ameliorative role of resveratrol

The current study aimed to explore the genotoxic impacts of the insecticide acetamiprid (ACP) on the myocardium and assess the ameliorative role of resveratrol (RSV). Male rats (10/group) were treated via oral route for 90 days: control; ACP (25 mg/kg); RSV (20 mg/kg); ACP+RSV. Peripheral blood micronucleus test, oxidative stress analysis, comet assay, 8-hydroxydeoxyguanosine and gene expression assessment were performed. The findings revealed that ACP has myocardial genotoxic effects, as demonstrated by increased micronucleus and 8-hydroxydeoxyguanosine formation and increased all comet parameters. Oxidative stress analysis demonstrated that ACP elevated H2O2 and NO levels while decreasing catalase and GST activities. Acetamiprid dysregulated the expression of genes related to oxidative stress and DNA damage response. However, RSV co-treatment resulted in significant protection against these genotoxic impacts. Resveratrol reduced DNA damage and restored the oxidative balance in the myocardium. Moreover, RSV modulated the Nrf2/HO-1 and Atm/P53 pathways, potentiating antioxidant defense and DNA repair.

Determination of genoprotection against cyclophosphamide induced toxicity in bone marrow of Swiss albino mice by Moringa oleifera leaves and Tinospora cordifolia stem

The present study aimed to determine the genoprotective activity and safety of Moringa oleifera leave and Tinospora cordifolia stem extracts against cyclophosphamide (CP)-induced genotoxicity utilizing Swiss albino mice. Animals were divided into 14 groups for subacute treatment with either M. oleifera or T. cordifolia extracts daily for 28 days. The extract doses selected were 100, 200 or 400 mg/kg b.w administered orally alone or combined with CP (50 mg/kg b.w. intraperitoneally daily for 5 days). Analyses performed included the comet assay, micronucleus test (MN) in bone marrow cells and sperm head abnormality assay (SHA). M. oleifera and T. cordifolia extracts induced no significant genotoxic effects on somatic and germ cells. In contrast, for all cells examined M. oleifera and T. cordifolia extracts inhibited DNA damage initiated by CP. Taken together data demonstrated that both plant extracts did not exhibit marked genotoxic effects but displayed potential chemoprotective properties against CP-induced genotoxicity in Swiss mice.

Anti-radiation effect of MRN-100: a hydro-ferrate fluid, in vivo

Ionizing radiation (IR) severely harms many organs, especially the hematopoietic tissue, mandating the development of protective nutraceuticals. MRN-100, a hydro-ferrate fluid, has been shown to protect γ-radiated fish against hematopoietic tissue damage and lethality. The current study aimed to examine MRN-100's protective effect against irradiated mice and explore the mechanisms underlying its effect. Mice received a single acute, sub-lethal, 5 Gy, whole body dose of X-ray IR. MRN-100 treatment was administered daily for 2-weeks pre-irradiation until 1-week post-irradiation. Spleen and blood were analysed for oxidative stress, hematological, histological and biochemical parameters. Radiation exposure markedly decreased complete blood count (CBC) parameters including hemoglobin, hematocrit, red blood cells, platelets, white blood cells and lymphocytes, and significantly increased neutrophils. In contrast, MRN-100 supplementation to irradiated mice ameliorated all CBC parameters and protected against DNA damage in both splenic cells and serum. It also had an antioxidant effect, increasing the levels of glutathione, superoxide dismutase, catalase and total antioxidant capacity, which were otherwise decreased by irradiation. MRN-100 intake reduced the oxidative stress biomarker levels of nitric oxide, protein carbonyl, malondialdehyde, reactive oxygen species and 8-hydroxydeoxyguanosine, a marker specific to DNA damage. Furthermore, MRN-100 enhanced serum iron and reversed the radiation-induced elevations of liver enzymes. Finally, MRN-100 protected splenic tissue from irradiation as observed by histology. We conclude that MRN-100 consumption may protect against oxidative stress generated by radiation exposure, suggesting that it may be employed as an adjuvant treatment to prevent radiation's severe damage to important organs.

Antitumor activity of solamargine in mouse melanoma model: relevance to clinical safety

Melanoma is the most aggressive type of skin cancer, and thus it is important to develop new drugs for its treatment. The present study aimed to examine the antitumor effects of solamargine a major alkaloid heteroside present in Solanum lycocarpum fruit. In addition solamargine was incorporated into nanoparticles (NP) of yttrium vanadate functionalized with 3-chloropropyltrimethoxysilane (YVO₄:Eu³⁺:CPTES:SM) to determine antitumor activity. The anti-melanoma assessment was performed using a syngeneic mouse melanoma model B16F10 cell line. In addition, systemic toxicity, nephrotoxic, and genotoxic parameters were assessed. Solamargine, at doses of 5 or 10 mg/kg/day administered subcutaneously to male C57BL/6 mice for 5 days, decreased tumor size and frequency of mitoses in tumor tissue, indicative of a decrease in cell proliferation. Treatments with YVO₄:Eu³⁺:CPTES:SM significantly reduced the number of mitoses in tumor tissue, associated with no change in tumor size. There were no apparent signs of systemic toxicity, nephrotoxicity, and genotoxicity initiated by treatments either with solamargine alone or plant alkaloid incorporated into NP. The animals treated with YVO₄:Eu³⁺:CPTES:SM exhibited significant increase in spleen weight accompanied by no apparent histological changes in all tissues examined. In addition, animals treated with solamargine (10 mg/kg/day) and YVO₄:Eu³⁺:CPTES:SM demonstrated significant reduction in hepatic DNA damage which was induced by tumor growth. Therefore, data suggest that solamargine may be considered a promising candidate in cancer therapy with no apparent toxic effects.

Anti-melanoma effect of ruthenium(II)-diphosphine complexes containing naphthoquinone ligand

The use of natural products as potential ligands has been explored as a strategy in the development of metal-based chemotherapy. Since ruthenium complexes are promising alternatives to traditional antitumor agents, this study evaluated the anti-melanoma potential of two ruthenium(II) complexes containing the naphthoquinone ligands lapachol (lap), [Ru(lap)(dppm)2]PF6, and lawsone (law), [Ru(law)(dppm)2]PF6, in addition to the bis(diphenylphosphino)methane (dppm) ligand, referred to as complexes (1) and (2), respectively, using a syngeneic murine melanoma model. Activation of the apoptotic pathway by the treatments was assessed by immunohistochemistry in tumor tissue. Additionally, toxicity of the treatments was evaluated by variation in body and organ weight, quantification of biochemical indicators of renal damage, and genotoxicity in bone marrow and hepatocytes. First, the antiproliferative activity of (1) and (2) was observed in B16F10 cells, with IC50 values of 2.78 and 1.68 μM, respectively. The results obtained in mice showed that, unlike complex (1), (2) possesses significant anti-melanoma activity demonstrated by a reduction in tumor volume and mass (88.42%), as well as in mitosis frequency (83.86%). Additionally, complex (2) increased the levels of cleaved caspase-3, inducing tumor cell apoptosis. When compared to the metallodrug cisplatin, complex (2) exhibited similar anti-melanoma activity and lower toxicity considering all parameters evaluated. In silico studies demonstrated no difference in the binding energy of the naphthoquinone complex between complexes (1) and (2). However, the complex containing the lawsone ligand has a lower molar volume, which may be important for interactions with minor DNA grooves. The present results demonstrate the antitumor efficiency of complex (2) and a significantly lower systemic toxicity compared to cisplatin.

Preventive activity of Copaifera langsdorffii Desf. leaves extract and its major compounds, afzelin and quercitrin, on DNA damage in in vitro and in vivo models

Copaifera langsdorffii Desf. is a plant found in South America, especially in Brazil. Oleoresin and the leaves of this plant is used as a popular medicinal agent. However, few studies on the chemical composition of aerial parts and related biological activities are known. This study aimed to examine the cytotoxic, genotoxic, and antigenotoxic potential of C. langsdorffii aerial parts hydroalcoholic extract (CLE) and two of its major compounds afzelin and quercitrin. The cytotoxic and antigenotoxic potential of CLE was determined as follows: 1) against genotoxicity induced by doxorubicin (DXR) or methyl methanesulfonate (MMS) in V79 cells; 2) by direct and indirect-acting mutagens in Salmonella typhimurium strains; and 3) by MMS in male Swiss mice. The protective effects of afzelin and quercitrin against DXR or MMS were also evaluated in V79 and HepG2 cells. CLE was cytotoxic as evidenced by clonogenic efficiency assay. Further, CLE did not induce a significant change in frequencies of chromosomal aberrations and micronuclei; as well as number of revertants in the Ames test demonstrating absence of genotoxicity. In contrast, CLE was found to be antigenotoxic in mammalian cells. The results also showed that CLE exerted inhibitory effect against indirect-acting mutagens in the Ames test. Afzelin and quercitrin did not reduce genotoxicity induced by DXR or MMS in V79 cells. However, treatments using afzelin and quercitrin decreased MMS-induced genotoxicity in HepG2 cells. The antigenotoxic effect of CLE observed in this study may be partially attributed to the antioxidant activity of the combination of major components afzelin and quercitrin.

Evaluation of genoprotection against malathion induced toxicity by Orthosiphon thymiflorus Sleesen

BACKGROUND

Pesticide toxicity is considered to be one of the significant reason for increased incidence of cancer. Plants are treasure troves of active phytochemical compounds which are used as herbal medicine as well as nutraceuticals.

OBJECTIVE

To evaluate the genoprotective potential of Orthosiphon thymiflorus (Roth) Sleesen, (Lamiaceae) against the toxicity induced by malathion by a battery of four in vivo assays in Swiss albino mice.

MATERIALS AND METHODS

Micronucleus assay was performed for analyzing the micronuclei induction and ratio of polychromatic and normochromatic erythrocytes (PCE/NCE). Anticlastogenic and mito depressive effect of the methanol and hexane extracts of O.thymiflorus were evaluated by chromosome aberration assay. Alkali comet assay was performed to assess double strand DNA repair. DNA damage sensing ability of the bone marrow cells were assessed by γ-H2AX foci formation. Phytochemical screening of hexane and methanol extract was done by GC-MS analysis.

RESULT

O. thymiflorus extracts showed a dose dependant protective effect in all assays. It significantly decreased the frequency of micronuclei and improved PCE/NCE value in post treated groups of animals. Malathion induced clastogenic aberrations were effectively attenuated by methanol and hexane extracts. DNA comet assay showed that malathion induced damage can be protected by O. thymiflorus extracts. Multiple foci formation in γ-H2AX assay confirmed the activation of DNA repair proteins in post treated animals.

CONCLUSION

Genoprotective effect of O. thymiflorus against malathion induced toxicity was confirmed. This study would be helpful to initiate more research including clinical using O. thymiflorus extract against pesticide induced toxicity.

Synergistic effects of pomegranate juice and atorvastatin for improving cerebellar structure and function of breast-feeding rats maternally fed on a high cholesterol diet

A highly cholesterol-diet is associated with atherosclerosis and little about the development of cerebellar cortex disorder. The study illustrated the changes of cerebellar cortex of rat neonate maternally fed on high cholesterol diet and the capacity of pomegranate alone or in combination with atorvastatin to improve it. Eighty-eight pregnant Wister rats were divided into eight groups (n = 11); control, pomegranate supplemented group (daily orally 0.4 mL (20 %), atorvastatin (10 mg/kg BT), hypercholesterolemia (dietary consumption 3% cholesterol for 6 weeks prior to conception and throughout gestation and lactation period), hypercholesterolemia and pomegranate or atorvastatin, hypercholesterolemia and atorvastatin and pomegranate. Dams and their offspring were sacrificed at 21 days post-partum. Sera of mother and cerebellum of offspring were investigated biochemically as well as histo-cytological changes of cerebellar cortex of offspring. Offspring maternally fed on high cholesterol diet showed damage of the cerebellar Purkinje and granular cells associated with demyelination, increased caspase 3 immunohistochemistry and increased DNA damage. These were associated with decreased brain neurotransmitters and increase apoptic markers. Dams supplemented pomegranate and/or atorvastatin improved the assayed parameters more than that of atorvastatin alone. The authors concluded that pomegranate juice contains potent antioxidant nutrients capable of reducing the cytotoxicity of hypercholesterolemia and atorvastatin, and enhancing the structure and function of the cerebellar cortex.

Antigenotoxicity properties of Copaifera multijuga oleoresin and its chemical marker, the diterpene (-)-copalic acid

In view of the biological activities and growing therapeutic interest in oleoresin obtained from Copaifera multijuga, this study aimed to determine the genotoxic and antigenotoxic potential of this oleoresin (CMO) and its chemical marker, diterpene (-)-copalic acid (CA). The micronucleus (MN) assay in V79 cell cultures and the Ames test were used for in vitro analyses, as well as MN and comet assays in Swiss mice for in vivo analyses. The in vitro genotoxicity/mutagenicity results showed that either CMO (30, 60, or 120 µg/ml-MN assay; 0.39-3.12 mg/plate-Ames test) or CA (2.42; 4.84, or 9.7 µg/ml-MN assay; 0.39-3.12 mg/plate-Ames test) did not induce a significant effect on the frequency of MN and number of revertants, demonstrating an absence of genotoxic and mutagenic activities, respectively, in vitro. In contrast, these natural products significantly reduced the frequency of MN induced by methyl methanesulfonate (MMS), and exerted a marked inhibitory effect against indirect-acting mutagens in the Ames test. In the in vivo test system, animals treated with CMO (6.25 mg/kg b.w.) exhibited a significant decrease in rate of MN occurrence compared to those treated only with MMS. An antigenotoxic effect of CA was noted in the MN test (1 and 2 mg/kg b.w.) and the comet assay (0.5 mg/kg b.w.). Data suggest that the chemical marker of the genus Copaifera, CA, may partially be responsible for the observed chemopreventive effect attributed to CMO exposure.

ABBREVIATIONS

2-AA, 2-anthramine; 2-AF, 2-aminofluorene; AFB₁, aflatoxin B₁; B[a]P, benzo[a]pyrene; BOD, biological oxygen demand; BPDE, benzo[a]pyrene-7,8-diol-9,10-epoxide; CA, (-)-copalic acid; CMO, oleoresin of Copaifera multijuga, DMEM, Dulbecco`s Modified Eagles`s Medium; DMSO, dimethylsulfoxide; EMBRAPA, Brazilian agricultural research corporation; GC-MS, gas chromatography-mass spectrometry; HAM-F10, nutrient mixture F-10 Ham; HPLC, high performance liquid chromatography; LC-MS, liquid chromatography-mass spectrometry; MI, mutagenic index; MMC, mitomycin C; MMS, methyl methanesulfonate; MN, micronucleus; MNPCE, micronucleated polychromatic erythrocyte; NCE, normochromatic erythrocyte; NDI, nuclear division index; NMR, nuclear magnetic resonance; NPD, 4-nitro-o-phenylenediamine; PBS, phosphate-buffered saline; PCE, polychromatic erythrocyte; SA, sodium azide; V79, Chinese hamster lung fibroblast.

Combination of NAD+ and NADPH Offers Greater Neuroprotection in Ischemic Stroke Models by Relieving Metabolic Stress

Both reduced nicotinamide adenine dinucleotide phosphate (NADPH) and β-nicotinamide adenine dinucleotide hydrate (NAD⁺) have been reported to have potent neuroprotective effects against ischemic neuronal injury. Both NADPH and NAD⁺ are essential cofactors for anti-oxidation and cellular energy metabolism. We investigated if combined NADPH and NAD⁺ could offer better neuroprotective effects on cellular and animal models of ischemic stroke. In vitro studies with primary cultured neurons demonstrated that NAD⁺ was effective in protecting neurons against oxygen-glucose deprivation/reoxygenation (OGD/R) injury when given during the early time period of reoxygenation. In vivo studies in mice also suggested that NAD⁺ was effective for ameliorating ischemic brain damage when administered within 2 h after reperfusion. The combination of NADPH and NAD⁺ provided not only greater beneficial effects but also larger therapeutic window in both cellular and animal models of stroke. The combination of NADPH and NAD⁺ significantly increased the levels of adenosine triphosphate (ATP) and reduced the levels of reactive oxygen species (ROS) and oxidative damage of macromolecules. Furthermore, the combined medication significantly reduced long-term mortality, improved the functional recovery, and inhibited signaling pathways involved in apoptosis and necroptosis after ischemic stroke. The present study indicates that the combination of NAD⁺ and NADPH can produce greater therapeutic effects with smaller dose of NADPH; on the other hand, NADPH can significantly prolong the therapeutic window of NAD⁺. The current results suggest that the combination of NADPH and NAD⁺ may provide a novel effective therapy for ischemic stroke.

Laccase-Mediated Enhancement of the Antioxidant Activity of Propolis and Poplar Bud Exudates

The treatment of propolis and poplar bud exudates with laccase from Trametes versicolor and 2,2,6,6-tetramethyl-1-piperidinyloxy free radical increased the antioxidant activity, as evaluated by the 2,2'-diphenyl picrylhydrazyl (DPPH)- and t-butyl-OOH-induced DNA breakage comet assay analyses. The effect was highest for shorter reaction times. Propolis showed the highest antioxidant activity in the DPPH test, whereas poplar bud exudates were more active in reducing the t-butyl-OOH-induced lesions in the Chinese hamster ovary cell line. Even if the concentration of polyphenols decreased during the oxidation, the formation of low-molecular-weight phenols phloroglucinol 4 (1,3,5-trihydroxy benzene), hydroquinone 5 (1,4-dihydroxy benzene), and catechol 6 (1,2-dihydroxy benzene), characterized by the radical-scavenging activity, can account for the observed increase in the antioxidant activity.

The caspase-3/p120 RasGAP stress-sensing module reduces liver cancer incidence but does not affect overall survival in gamma-irradiated and carcinogen-treated mice

Activation of oncogenes is the initial step in cellular transformation. Oncogenes favor aberrant proliferation, which, at least initially, induces cellular stress. This oncogenic stress can act as a safeguard mechanism against further transformation by inducing senescence or apoptosis. Yet, the few premalignant cells that tolerate and escape these senescent or apoptotic responses are those that will ultimately generate tumors. The caspase-3/p120 RasGAP module is a stress-sensing device that promotes survival under mild stress conditions. A point mutation in RasGAP that prevents its cleavage by caspase-3 inactivates the pro-survival capacity of the device. When the mice homozygous for this mutation (D455A knock-in mice) are patho-physiologically challenged, they experience much stronger cellular damage than their wild-type counterparts and the affected organs rapidly lose their functionality. We reasoned that the caspase-3/p120 RasGAP module could help premalignant cells to cope with oncogenic stress and hence favor the development of tumors. Using gamma-irradiation and N-ethyl-N-nitrosourea (ENU) as tumor initiators, we assessed the survival advantage that the caspase-3/p120 RasGAP module could provide to premalignant cells. No difference in overall mortality between wild-type and D455A knock-in mice were observed. However, the number of ENU-induced liver tumors in the knock-in mice was higher than in control mice. These results indicate that the caspase-3/p120 RasGAP stress-sensing module impacts on carcinogen-induced liver cancer incidence but not sufficiently so as to affect overall survival. Hence, gamma irradiation and ENU-induced tumorigenesis processes do not critically rely on a survival mechanism that contributes to the maintenance of organ homeostasis in stressed healthy tissues.

Testing of Schefflera vinosa extract in mammalian cells in vitro and in vivo for potential toxicity, genetic damage, and role of oxidation

The aim of this study was to examine the cytotoxic and genotoxic potential of a hydroethanolic extract of Schefflera vinosa (SV), a plant with schistosomicidal activity, as well as its influence on DNA damage induced by different mutagens, methyl methane sulfonate (MMS) and hydrogen peroxide (H₂O₂), in V79 cells and Swiss mice. Schefflera vinosa extract produced cytotoxicity at concentrations of 312.5 µg/ml or higher using the XTT cell proliferation assay kit. Treatment of V79 cell cultures with the highest SV concentration tested (150 µg/ml) significantly increased the frequency of micronuclei (MN) compared to controls. All SV concentrations significantly reduced the frequency of MN induced by hydrogen peroxide in V79 cell cultures. Further, SV was able to scavenge free radicals in the DPPH assay. In the in vivo test system, treatment with the highest dose tested (1,000 mg/kg body weight) induced a significant rise in frequency of DNA damage using the comet assay. However, animals treated with different doses of SV demonstrated absence of genotoxicity in the bone marrow MN test. For assessment of modulatory effects, the lower concentration of SV (250 mg/kg body weight) administered to MMS-treated mice significantly reduced frequency of DNA damage compared to the positive control (MMS alone). In contrast, the highest concentration tested (1,000 mg/kg body weight) significantly increased the rate of MN induced by MMS. The lack of genotoxic damage at biologically relevant SV concentrations, as well as the SV-mediated antigenotoxic and antioxidant activities, indicate the potential therapeutic usefulness of this plant extract. These activities may be attributed, at least in part, to the flavonoid quercitrin, its major component.

Protective effects of Solanum cernuum extract against chromosomal and genomic damage induced by methyl methanesulfonate in Swiss mice

Solanum cernuum Vell is a Brazilian shrub or small tree, restricted to Southeast states of the country. The leaves are commercialized as "panacéia" and indicated for the treatment of urinary disorders, gonorrhea, scabies, skin diseases and as desobstruent, diuretic and antiarrhythmic. The hydroalcholic extract is active in the treatment of gastric ulcer. The aim of this study was to evaluate the genotoxic and antigenotoxic potential of S. cernuum hydroalcoholic extract (SC) in Swiss mice by micronucleus and comet assays. The animals were treated by gavage with the doses of 500, 1000 and 2000mg/kg body weight (b.w.). For antigenotoxicity assessment, the doses of 15, 30, 60, 120 and 240mg/kg b.w SC were administered simultaneously with the mutagen methyl methanesulfonate (MMS, 40mg/kg b.w., i.p.). The results showed that the SC was not genotoxic in both micronucleus and comet assays. On the other hand, the treatment with the lowest dose of SC (15mg/kg b.w.) plus MMS showed a statistically significant reduction in the frequency of micronuclei compared to treatment only with MMS. For the comet assay, significant reduction in extensions of DNA damage was observed in all treatments with SC combined with MMS in comparison with only MMS. The antigenotoxic activity observed for the SC may be due to the antioxidant potential of the compounds present in the extract such as guanidine alkaloids and flavonoids.

8-Hydroxy-2'-deoxyguanosine as a biomarker of oxidative DNA damage induced by perfluorinated compounds in TK6 cells

8-Hydroxy-2'-deoxyguanosine (8-OHdG) is the most common biomarker of oxidative DNA damage, it is formed by chemical carcinogens and can be measured in any species. Perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) are suspected genotoxic carcinogens through induction of reactive oxygen species that are responsible for oxidative DNA damage. This study was conducted to investigate the in vitro genotoxicity of PFOA and PFNA in human lymphoblastoid (TK6) cell line. TK6 cells were exposed to PFOA at 0, 125, 250, and 500 ppm and PFNA at 125 and 250 ppm for 2 h. Single cell gel electrophoresis (comet assay) was used to measure DNA damage; at least 50 cells per sample were analyzed using comet Assay Software Project (CASP). 8-OHdG was measured in DNA of exposed cells using high-performance liquid chromatography (HPLC)-mass spectrometry (MS)/MS. Results showed that both PFOA and PFNA induced DNA damage indicated by increased tail length (DNA migration). The level of 8-OHdG was increased in a dose-dependent manner in both PFOA and PFNA exposure. We concluded that PFOA and PFNA induced DNA damage and the biomarker of oxidative DNA damage (8-OHdG) could be measured by HPLC-MS/MS. In addition, PFNA produced high level of 8-OHdG at concentrations lower than PFOA, this may indicate that PFNA is more potent genotoxicant for TK6 cells than PFOA.

Preventive effects of metallothionein against DNA and lipid metabolic damages in dyslipidemic mice under repeated mild stress

The effects of repeated mild stress on DNA and lipid metabolic damages in multiple organs of dyslipidemic mice, and the preventive role of metallothionein (MT) were investigated. Female adult wild-type and MT-null mice fed high-fat diet (HFD) or standard diet (STD) were repeatedly subjected to fasting or restraint for three weeks. The liver, pancreas, spleen, bone marrow and serum samples were taken for evaluating DNA damage, MT, glutathione (GSH), corticosterone, carnitine and adiponectin. Body weights of restraint groups were reduced with the intensity of stress increased, even if the energy intakes were higher than those of STD group. Hepatic GSH levels were reduced in HFD control group and were further reduced in stress groups, especially in restraint groups, while the hepatic MT and serum corticosterone levels were increased in concert with the intensity of stress. Cellular DNA damages were generally increased by the restraint stress, especially in MT-null mice. Hepatic carnitine levels of MT-null mice were markedly lower than those of wild-type mice. The data suggest that MT plays a preventive role by acting as an antioxidant in corporation with GSH decreased by repeated stress and that MT may be an essential factor for inducing carnitine under the stress.

Titanium dioxide nanoparticle-induced oxidative stress triggers DNA damage and hepatic injury in mice

BACKGROUND

The use of metal oxide nanoparticles (titanium dioxide) in consumer and industrial products improves their quality but also underscores the possible adverse effects to human and environmental health.

MATERIALS & METHODS

Mice were exposed orally for 14 consecutive days and analyzed for alteration in different hepatic enzymes, histopathological changes, oxidative stress, DNA damage, tumor suppressor and proapoptotic protein expression in liver cells.

RESULTS

We observed a significant alteration in the level of hepatic enzymes and liver histopathology at a dose of 100 mg/kg body weight. Significant oxidative DNA damage was observed in liver cells, which could be attributed to oxidative stress. In addition, the increased expression of p53, BAX, caspase-3 and -9 proteins and decreased expression of antiapoptotic protein Bcl-2, suggest activation of the intrinsic pathway of apoptosis.

CONCLUSION

High accumulation of titanium dioxide nanoparticles in the liver tissue would cause DNA damage and apoptosis through the intrinsic pathway.

Genotoxic effects of the herbicide Roundup(®) in the fish Corydoras paleatus (Jenyns 1842) after short-term, environmentally low concentration exposure

The glyphosate-based herbicide, Roundup(®), is one of the most used pesticides worldwide. In concert with the advent of transgenic crops resistant to glyphosate, the use of this pesticide has led to an increase in agricultural yields. The objective of this study was to evaluate the genotoxic effect that the herbicide Roundup(®) (at a concentration of 6.67 μg/L, corresponding to 3.20 μg/L glyphosate) can have on the fish Corydoras paleatus. Treatment groups were exposed for 3, 6, and 9 days, and effects were analyzed using the piscine micronucleus test (PMT) and comet assay. A group subjected to filtered water only was used as a negative control. The PMT did not show differences between the control and exposed groups for any of the treatment times. In contrast, the comet assay showed a high rate of DNA damage in group exposed to Roundup(®) for all treatment times, both for blood and hepatic cells. We conclude that for the low concentration used in this research, the herbicide shows potential genotoxic effects. Future research will be important in evaluating the effects of this substance, whose presence in the environment is ever-increasing.

Biomarkers for oxidative stress in acute lung injury induced in rabbits submitted to different strategies of mechanical ventilation

Oxidative damage has been said to play an important role in pulmonary injury, which is associated with the development and progression of acute respiratory distress syndrome (ARDS). We aimed to identify biomarkers to determine the oxidative stress in an animal model of acute lung injury (ALI) using two different strategies of mechanical ventilation. Rabbits were ventilated using either conventional mechanical ventilation (CMV) or high-frequency oscillatory ventilation (HFOV). Lung injury was induced by tracheal saline infusion (30 ml/kg, 38°C). In addition, five healthy rabbits were studied for oxidative stress. Isolated lymphocytes from peripheral blood and lung tissue samples were analyzed by alkaline single cell gel electrophoresis (comet assay) to determine DNA damage. Total antioxidant performance (TAP) assay was applied to measure overall antioxidant performance in plasma and lung tissue. HFOV rabbits had similar results to healthy animals, showing significantly higher antioxidant performance and lower DNA damage compared with CMV in lung tissue and plasma. Total antioxidant performance showed a significant positive correlation (r = 0.58; P = 0.0006) in plasma and lung tissue. In addition, comet assay presented a significant positive correlation (r = 0.66; P = 0.007) between cells recovered from target tissue and peripheral blood. Moreover, antioxidant performance was significantly and negatively correlated with DNA damage (r = -0.50; P = 0.002) in lung tissue. This study indicates that both TAP and comet assay identify increased oxidative stress in CMV rabbits compared with HFOV. Antioxidant performance analyzed by TAP and oxidative DNA damage by comet assay, both in plasma, reflects oxidative stress in the target tissue, which warrants further studies in humans.

Differential genotoxic effects of subchronic exposure to ethyl tertiary butyl ether in the livers of Aldh2 knockout and wild-type mice

Ethyl tertiary butyl ether (ETBE) is used as an additive to gasoline to reduce carbon monoxide emissions in some developed countries. So far, ETBE was not found with positive results in many genotoxic assays. This study is undertaken to investigate the modifying effects of deficiency of aldehyde dehydrogenase 2 (ALDH2) on the toxicity of ETBE in the livers of mice. Eight-week-old wild-type (WT) and Aldh2 knockout (KO) C57BL/6 mice of both sexes were exposed to 0, 500, 1,750, and 5,000 ppm ETBE for 6 h/day with 5 days per weeks for 13 weeks. Histopathology assessments and measurements of genetic effects in the livers were performed. Significantly increased accidences of centrilobular hypertrophy were observed in the livers of WT and KO mice of both sexes in 5,000 ppm group; there was a sex difference in centrilobular hypertrophy between male and female KO mice, with more severe damage in the males. In addition, DNA strand breaks, 8-hydroxyguanine DNA-glycosylase (hOGG1)-modified oxidative base modification, and 8-hydroxydeoxyguanosine as genetic damage endpoints were significantly increased in three exposure groups in KO male mice, while these genotoxic effects were only found in 5,000 ppm group of KO female mice. In WT mice, significant DNA damage was seen in 5,000 ppm group of male mice, but not in females. Thus, sex differences in DNA damage were found not only in KO mice, but also in WT mice. These results suggest that ALDH2 polymorphisms and sex should be taken into considerations in predicting human health effects of ETBE exposure.

Toxicity of cyanobacterial bloom extracts from Taihu Lake on mouse, Mus musculus

The acute and sub-chronic toxicities of cyanobacterial extract from Taihu Lake (PR China) on mouse (Mus musculus) were investigated in this study via intraperitoneal (i.p.) injection. Increases in liver/body weight ratios and pathological changes in mouse liver showed adverse effects at the organ level. Images from transmission electron microscopy (TEM) indicated that abnormal membrane structure occurred and that the organelles were damaged severely in the cells of liver and testis. The high dose group received i.p. injection of 12 mg lyophilized algae cells/kg body weight. Malondialdehyde (MDA) levels increased significantly in the livers of this group, along with a significant decrease in catalase (CAT) activity. These results revealed the existence of obvious oxidative stress. Comet assay results also suggested a dose-dependent relationship between DNA damage in hepatocytes/testicular cells and the amount of bloom extract administered to the mice. There was a significant increase in DNA damage compared to the control group and the genotoxicity of the cyanobacterial bloom to testicular cells was higher than in hepatocytes.

Transplacental genotoxicity evaluation of cypermethrin using alkaline comet assay

Transplacental genotoxic effect of cypermethrin technical was investigated. Three doses (25, 50 and 75 mg/kg body weight) were administered to groups of pregnant Wistar rats during 6-15 days of gestation. Animals were killed on gestation day 20. Fetal blood and liver samples were evaluated for DNA damage using alkaline comet assay. A marginal increase in the mean percentage of DNA damage was recorded in both blood and liver samples of fetuses from cypermethrin-treated dams, but the values were not statistically significant. No skeletal or visceral fetal abnormalities were recorded in treated groups. Nevertheless, the results lead to an understanding that transplacental exposure to cypermethrin can induce low levels of DNA damage in fetuses. This observation could be an explanation for the teratogenic effect exhibited by this chemical in many other studies. The results indicate that cypermethrin may be transplacentally genotoxic. The authors propose more detailed investigations for validating the current findings.

Differential colon DNA damage induced by azo food additives between rats and mice

Azo dyes, amaranth, allura red and new coccine, which are currently used as food color additives in Japan, have been reported to cause colon specific DNA damage in mice. To examine species difference in the DNA damage between rats and mice, each of dyes was administered to male mice (1 and 10 mg/kg) and male rats (10, 100 and 1,000 mg/kg) by gavage. Brain, lung, liver, kidney, glandular stomach, colon, urinary bladder and bone marrow were sampled 3 hr (for mice) and 3, 6, 12 and 24 hr (for rats) after the treatment. The alkaline comet assay showed DNA damage in the mouse colon 3 hr after the administration of all of the dyes at 10 mg/kg. In rats, however, none of the dyes damaged DNA. Azo dyes should undergo metabolic reduction in the colon to be adducted to DNA. To determine transit time of the dyes to the colon after their administration, gastric emptying and intestinal transport in mice and rats were examined using brilliant blue FCF (BB) as an indicator. The half times of gastric emptying were 70 and 80 min for mice and rats, respectively; and about 60% of the BB was removed from the stomach 1 hr after the gastric intubation in both mice and rats. BB reached the mouse and rat colon 1 and 3 hr after the administration, respectively. Considering the wide dose range and sampling times well covering the transit time to the colon, rats may be insensitive to these azo dye-induced DNA damage.

DNA strand breakage and lipid peroxidation after exposure to welding fumes in vivo

A remarkable number of complex aerosols are generated from welding processes. The objective of this study was to compare DNA damage and lipid peroxidation in plasma and in lung and in liver tissue of rats exposed to welding fumes in an exposure chamber with those of control animals. Three air samples from the chamber were also collected to assess the exposure dose for each exposure (total samplings = 18). Eight male Sprague-Dawley rats were exposed to welding fumes at a concentration of 1540.76 mg/m(3) for 10 min/day six times on day 1, day 3, day 7, day 15, day 30 and day 40. Lung, liver and kidney injury was measured following exposure, as well as in unexposed control rats (n = 4 at the beginning of the study). DNA strand breakage [tail moment (TMOM)] in exposed animals showed significant differences at day 1, day 4, day 7 and day 15 relative to the levels in control animals. Malondialdehyde (MDA, a lipid peroxidation product) levels increased gradually post-welding to 0.4 microM at 7 days. MDA and TMOM both reached maximum levels 7 days after the first exposure. At the start, an increasing trend in DNA strand breakage was more obvious than increases in MDA levels; MDA seemed to reflect long-term effects of exposure to welding fumes since it increased after 7 days and was sustained to 40 days in vivo. Significant differences in both MDA levels and DNA strand breakage were seen in lung, liver and kidney 40 days after the first fume inhalation. We conclude that acute exposure of rats to welding fumes causes noticeable oxidative damage and lipid peroxidation effects and that DNA damage may recover after long and repeat exposure. More chronic inhalation and low-dose studies are needed in order to further assess the effects of inhalation of welding fumes on DNA and to elucidate the possible causal mechanisms associated with the biologically damaging effects of welding fumes.

Genotoxicity of nano/microparticles in in vitro micronuclei, in vivo comet and mutation assay systems

BACKGROUND

Recently, manufactured nano/microparticles such as fullerenes (C60), carbon black (CB) and ceramic fiber are being widely used because of their desirable properties in industrial, medical and cosmetic fields. However, there are few data on these particles in mammalian mutagenesis and carcinogenesis. To examine genotoxic effects by C60, CB and kaolin, an in vitro micronuclei (MN) test was conducted with human lung cancer cell line, A549 cells. In addition, DNA damage and mutations were analyzed by in vivo assay systems using male C57BL/6J or gpt delta transgenic mice which were intratracheally instilled with single or multiple doses of 0.2 mg per animal of particles.

RESULTS

In in vitro genotoxic analysis, increased MN frequencies were observed in A549 cells treated with C60, CB and kaolin in a dose-dependent manner. These three nano/microparticles also induced DNA damage in the lungs of C57BL/6J mice measured by comet assay. Moreover, single or multiple instillations of C60 and kaolin, increased either or both of gpt and Spi- mutant frequencies in the lungs of gpt delta transgenic mice. Mutation spectra analysis showed transversions were predominant, and more than 60% of the base substitutions occurred at G:C base pairs in the gpt genes. The G:C to C:G transversion was commonly increased by these particle instillations.

CONCLUSION

Manufactured nano/microparticles, CB, C60 and kaolin, were shown to be genotoxic in in vitro and in vivo assay systems.

Assessment of environmental stress in Parablennius sanguinolentus (Pallas, 1814) of the Sicilian Ionian coast

The blenny Parablennius sanguinolentus was selected as a useful bioindicator of environmental pollution. Chemical parameters in water and sediments from three different sampling sites along the Sicilian Ionian coast were determined and metal concentrations in fish muscle were measured. DNA fragmentation and oxidation in erythrocytes and hepatocytes was determined by the Comet assay and HSP70 expression levels were evaluated in the liver. The results show an increased level of chromium in sediments and high polycyclic aromatic hydrocarbon (PAH) concentrations in water at one site. The bioaccumulation of metals in muscle tissue shows high concentrations of lead in some samples. A high percentage of DNA damage in blood and liver cells, as well as high hepatic levels of HSP70, were found in all the sites. The results demonstrate the usefulness of an integrated chemical and biological approach for the determination of environmental stress.

In vivo genotoxic potential of microcystin-LR: a cyanobacterial toxin, investigated both by the unscheduled DNA synthesis (UDS) and the comet assays after intravenous administration

Microcystin-LR (MC-LR) is a toxin produced by freshwater cyanobacteria and is a potential threat to human health. MC-LR has been shown to be both a specific inhibitor of serine/threonine protein phosphatases PP1 and PP2A and a potent tumor promoter in rat liver. However, the genotoxic potential of MCs remains unclear. In this article, we investigated the ability of MC-LR to induce DNA damage on rat hepatocytes following intravenous (iv) administration by using two in vivo genotoxicity assays: the unscheduled DNA synthesis (UDS) and the comet assays. The UDS assay measures DNA synthesis induced from the excision repair of DNA damaged regions and the comet assay is a very sensitive technique for detecting various forms of DNA damage. After an exposure time of 2-4 h or 12-16 h and a dose ranging from 12.5 to 50 microg/kg bw, no DNA damage could be observed in both assays on rat hepatocytes following iv administration. These findings have been discussed and compared with recently published genotoxic results obtained in other organs from mice after oral and intraperitoneal treatments to better understand the mechanism of action of this toxin in relation with its cancerogenicity potential.

Genotoxicity studies of a desealant solvent mixture, SR-51

The Royal Australian Air Force (RAAF) has reported that personnel involved in F-111 fuel tank maintenance were concerned that exposure to a range of chemicals during the period 1977 to mid-1990s was the cause of health problems, including cancer. Particular concern was directed at SR-51, a desealant chemical mixture containing the following four solvents: aromatic 150 solvent (Aro150), dimethylacetamide, thiophenol (TP), and triethylphosphate. The present study examined the mutagenic potential of SR-51 using a range of well-known mutagen and genotoxin assays. The tests used were i) a modified version of the Ames test, ii) the mouse lymphoma assay, iii) the comet assay (a single-cell gel electrophoresis assay), and iv) a mouse micronucleus test. The modified Ames test used mixed bacterial strains in liquid suspension media. The Ames test results showed that SR-51 (tested up to the cytotoxic concentration of 36 microg/ml, 30 min incubation) in the presence and absence of S9 metabolic activation was not mutagenic. The mouse lymphoma assay used cultured mouse lymphoma cells in a microwell suspension method. The mouse lymphoma assay was also negative with SR-51 (tested up to the cytotoxic concentration of 22.5 microg/ml, 3 h incubation) in the presence and absence of S9 metabolic activation. The Comet assay, using cultured mouse lymphoma cells, showed no evidence of DNA damage in cells exposed up to the cytotoxic concentration of SR-51 at 11.25 microg/ml. The in-vivo mouse micronucleus test was undertaken in wild-type C57Bl6J male mice dosed orally with SR-51for 14 days with a single daily dose up to 360 mg/kg/day (the maximum-tolerated dose). No increases were observed in micronuclei (MN) frequency in bone marrow collected (24 h after final dose) from SR-51-treated mice compared to the number of MN observed in bone marrow collected from untreated mice. Tissues collected from treated mice at necropsy demonstrated a significant increase in spleen weights in the high dose mice. Gas chromatography analysis of SR-51 identified more than 40 individual components and an oxidation product, diphenyldisulfide derived from TP under conditions of mild heating. In conclusion, there was no evidence that SR-51 is mutagenic.

Tissue-dependent preventive effect of metallothionein against DNA damage in dyslipidemic mice under repeated stresses of fasting or restraint

AIMS

To investigate the effect of repeated stress on DNA damage in seven organs of dyslipidemic mice, and the preventive role of metallothionein (MT).

MAIN METHODS

Female adult 129/Sv wild-type and MT-null mice fed high-fat diet (HFD) were repeatedly subjected to mild stress of fasting or restraint in weeks 2 to 4 of 4-week study period. Serum cholesterol level, DNA damage in the liver, pancreas, spleen, bone marrow, kidney, lung and gastric mucosa, and other parameters were determined.

KEY FINDINGS

Body weights were increased in both types of mice fed HFD compared to those fed standard diet (STD), and further increased by 12 h-fasting, while they were markedly decreased by 1-3 h-restraint. Fasting accelerated accumulation of fat in the liver, and increase in serum cholesterol of both types of mice fed HFD. Feeding of HFD increased DNA damage in the pancreas, spleen and bone marrow of both types of mice, compared with those fed STD. In the wild-type mice fed HFD, 24 h-fasting increased DNA damage in the liver and spleen, while restraint increased the damage in the liver, pancreas, spleen and bone marrow. DNA damage in the cells of organs was markedly increased in the MT-null mice. Specifically, damage in the liver, pancreas, spleen and bone marrow was greatly increased with the intensity of stress increased, and the damage was much greater in the restraint mice than in the fasting mice.

SIGNIFICANCE

MT plays a tissue-dependent preventive role against DNA damage in various murine organs induced by repeated stress.

Effect of glutathione (GSH) depletion on DNA damage and blood chemistry in aged and young rats

DNA is damaged by reactive oxygen species (ROS) and such damage is age-dependent. Blood chemical parameters also change age-dependently. Glutathione (GSH) plays an important role as an antioxidant. However, the effects of GSH on DNA damage and blood chemistry are unclear. Therefore, this study was aimed to evaluate GSH contribution to DNA damage and changes of blood chemical parameters in aged and young rats. The GSH content in the livers and kidneys of aged rats (20 months) were lower than that in young rats (9 weeks of age) with higher DNA damage detected by a comet assay. There was a negative correlation between the GSH content and the DNA damage in the liver and kidney. L-buthionine (S,R)-sulfoximine (BSO; 0, 5, 20 mM), which inhibits GSH synthesis, was administered in drinking water for 28 days to young and aged rats (8 weeks and 19 months of age at the start of the administration). The treatment significantly decreased GSH levels in the heart, liver, lung and kidney of either the young or aged rats without causing DNA damage in those organs. When compared with young rats, aged rats showed higher levels in aspartate aminotransferase, alanine aminotransferase, total bilirubin, total cholesterol, globulin, creatinine, sodium and chloride and lower levels in alkaline phosphatase, triglyceride, albumin/globulin and inorganic phosphorus. However, BSO did not change these parameters in young or aged rats. These results showed that there was a negative correlation between GSH and DNA damage during aging, but the BSO-induced GSH depletion did not affect DNA damage or blood chemistry levels in young and aged rats under these study conditions.

Modulatory activity of a Lactobacillus casei strain on 1,2-dimethylhydrazine-induced genotoxicity in rats

The present study was designed to investigate the putative antigenotoxic effects of supplementing the diet of rats treated with the colon carcinogen 1,2-dimethylhydrazine hydrochloride (DMH) with a Lactobacillus casei strain using an in vivo approach. The antigenotoxic response was evaluated in colon and liver cells using the alkaline comet assay. Since the balance between the bioactivation and detoxification metabolic pathways is crucial for the formation of toxic and genotoxic metabolites, alterations in the level of some xenobiotic metabolizing enzymes (XME) were studied in liver preparations. In the challenge group (L. casei + DMH), lactobacilli-supplemented diet, there was a decrease in the extent of DMH-induced DNA damage, especially in colon cells. Compared with control rats, there was less basal DNA damage in colon cells of rats fed on a lactobacilli-supplemented diet. These findings are the first to give clear evidence of DNA-protective effects of lactobacilli against basal DNA damage. Moreover, the chemopreventive effects were accompanied by changes in the activities of several XME. The observed decrease in the concentration of nonenzymatic antioxidants (i.e. GSH) and the reduced activity of enzymatic antioxidants (i.e., GST, GPx, and SOD) in liver could reflect an overall reduction in the level of oxidative stress in rats on a diet supplemented with the L. casei suspension compared with control rats (basal state). Thus, the concentrations of GSH and the activities of GST, GPx, and SOD could be downregulated by supplementing the diet with L. casei as a response to an improved antioxidant status.

Effect of Safranal, a Constituent of Crocus sativus (Saffron), on Methyl Methanesulfonate (MMS)–Induced DNA Damage in Mouse Organs: An Alkaline Single-Cell Gel Electrophoresis (Comet) Assay

The influence of safranal, a constituent of Crocus sativus L. stigmas, on methyl methanesulfonate (MMS)-induced DNA damage was examined using alkaline single-cell gel electrophoresis (SCGE), or comet, assay in multiple organs of mice (liver, lung, kidney, and spleen). NMRI mice were divided into five groups, each of which contained five mice. The animals in different groups were received the following chemicals: physiological saline (10 mL/kg, ip), safranal (363.75 mg/kg, ip), MMS (120 mg/kg, ip), safranal (72.75 mg/kg, ip) 45 min prior to MMS administration, and safranal (363.75 mg/kg, ip) 45 min prior to MMS administration. Mice were sacrificed about 3 h after the administration of direct mutagen MMS, safranal, or saline, and the alkaline comet assay was used to evaluate the influence of safranal on DNA damage in different mouse organs. Increase in DNA migration was varied between 9.08 times (for spleen) and 22.12 times (for liver) in nuclei of different organs of MMS-treated mice, as compared with those of saline-treated animals (p < 0.001). In control groups, no significant difference was found in the DNA migration between safranal- and saline-pretreated mice. The MMS-induced DNA migration in safranal-pretreated mice (363.75 mg/kg) was reduced between 4.54-fold (kidney) and 7.31-fold (liver) as compared with those of MMS-treated animals alone (p < 0.001). This suppression of DNA damage by safranal was found to be depended on the dose, and pretreatment with safranal (72.75 mg/kg) only reduced DNA damage by 25.29%, 21.58%, 31.32%, and 25.88% in liver, lung, kidney, and spleen, respectively (p < 0.001 as compared with saline-treated group). The results of the present study showed that safranal clearly repressed the genotoxic potency of MMS, as measured by the comet assay, in different mouse organs, but the mechanism of this protection needs to be more investigated using different in vitro system assays and different experimental designs.