Micronucleus Formation In Mice Research Articles

In Vitro and In Vivo Genotoxicity Analysis of Gold Nanoparticles

Gold nanoparticles have been well recognized for biomedical applications, especially cancer therapeutics. As a preliminary step, it is necessary to investigate the genotoxicity of gold nanoparticles under in vitro and in vivo conditions. In vitro, chromosomal aberration study results showed that gold nanoparticles of 5 mg/ml concentration did not increase the percentage of chromosomal aberration in human peripheral blood lymphocyte cells compared to the negative control. Gold nanoparticles were evaluated erythrocyte micronucleus formation by in vivo micronucleus assay, and results showed no apparent micronucleus formation in mice after 42h exposure of gold nanoparticles. Gold nanoparticles of 600 mg/kg (body weight) were non-clastogenic in swiss albino mice.

Diallyl Disulfide Mitigates DNA Damage and Spleen Tissue Effects After Irradiation.

BackgroundSeveral factors found in foods are beneficial to human health and they may contribute to radiation protection. Taking food factors could be an easy way to reduce the effects of radiation after nuclear accidents, as well as secondary radiation risks after cancer radiotherapy or space missions. Here, diallyl disulfide (DADS), a component of garlic oil, was studied for its ability to mitigate radiation damage.Material/MethodsWe investigated the effects of DADS on micronucleus (MN) formation and apoptosis in HepG2 cells by use of 4-Gy X-ray irradiation. We also assessed the effects of DADS on radiation damage in vivo by evaluating MN formation in bone marrow cells in mice (BALB/c, 8-week-old females) after oral intake of DADS prior to irradiation with 4 Gy. Several tissue effects were also investigated.ResultsThe presence of DADS inhibited MN formation, whereas DADS had no influence on the radiation-induced inhibition of cell cycle progression in HepG2 cells. An increase in apoptosis in HepG2 cells was induced after irradiation, and this effect was stronger in the presence of DADS than in its absence. In mice, when DADS was administered daily for 3 days prior to irradiation, MN formation in irradiated mice was decreased. The decrease in MN formation in mice was greater with 0.5% DADS compared to 1% DADS. Moreover, an increase in spleen weight observed 3 weeks after irradiation was suppressed in mice administered DADS.ConclusionsDADS is a potential radiation-protective agent that effectively mitigates DNA damage, and its effects in the spleen observed after irradiation may be related to inflammation and carcinogenesis.

A Genome-Wide Association Study for Regulators of Micronucleus Formation in Mice.

In mammals the regulation of genomic instability plays a key role in tumor suppression and also controls genome plasticity, which is important for recombination during the processes of immunity and meiosis. Most studies to identify regulators of genomic instability have been performed in cells in culture or in systems that report on gross rearrangements of the genome, yet subtle differences in the level of genomic instability can contribute to whole organism phenotypes such as tumor predisposition. Here we performed a genome-wide association study in a population of 1379 outbred Crl:CFW(SW)-US_P08 mice to dissect the genetic landscape of micronucleus formation, a biomarker of chromosomal breaks, whole chromosome loss, and extranuclear DNA. Variation in micronucleus levels is a complex trait with a genome-wide heritability of 53.1%. We identify seven loci influencing micronucleus formation (false discovery rate <5%), and define candidate genes at each locus. Intriguingly at several loci we find evidence for sexual dimorphism in micronucleus formation, with a locus on chromosome 11 being specific to males.

Impact of Anthocyanidins on Mitoxantrone-Induced Cytotoxicity and Genotoxicity: An In Vitro and In Vivo Analysis.

Hypothesis. Anthocyanins possess well-known biological effects and suppress DNA damage induced by therapeutic topoisomerase poisons. Our study focusses on the modulatory effects of anthocyanidins—malvidin (MAL) and pelargonidin (PEL)—on topoisomerase II poison mitoxantrone (MXT)-induced cytotoxicity and genotoxicity in in vitro and in vivo conditions. Study design. HepG2 cells were treated with MXT (1-10 µM), MAL (10-100 µM,) and PEL (5-640 µM) to determine cell viability. Further, experiments on cytotoxicity and apoptosis induction by single agents or combinations were performed. In vitro and in vivo antigenotoxic effect of MAL/PEL against MXT was evaluated in human lymphocytes and mouse bone marrow cells. Methods. Cytotoxicity of test agents and apoptosis induction in HepG2 cells was assessed by MTT assay, trypan blue dye exclusion assay and Hoechst 33258 staining. Antigenotoxic effects of MAL/PEL against MXT were assessed in co-treated human lymphocytes and bone marrow from mice that received MXT intraperitoneally 30 minutes post MAL/PEL oral administration Results. Dose-dependent cytotoxicity was observed with all 3 test agents in HepG2 cells. Highest test concentration of 100 µM MAL, 640 µM PEL, and 10 µM MXT decreased HepG2 cell viability by 80%, 30%, and 90%, respectively. The combination of 1 µM MXT + 80 µM MAL reduced cell viability better than single agents. MAL/PEL treatment significantly reduced MXT-induced genotoxicity in human lymphocytes and micronuclei formation in mice. Conclusion. Combination of MAL/PEL with lower doses of MXT, especially MAL+MXT increases the cytotoxicity in cancer cells. In addition, MXT treatment with MAL/PEL reduced MXT-induced genotoxicity and protected normal cells during chemotherapy.

Acute toxicity and genotoxicity study of fermented traditional herb formula Guibi-tang

Ethnopharmacology relevanceGuibi-tang (Guipi-tang in Chinese and Kihi-to in Japanese) is a multi-herb traditional medicine commonly prescribed to treat psychoneurosis in East Asia. Although this medicine has been widely used, there is little available information on the safety and toxicity of Guibi-tang, especially on the fermented one. Materials and methodsGuibi-tang, composed of 12 herbs, was fermented with bacteria and lyophilized. Single dose acute toxicity in rats was observed for 14 days after administration. Genetic toxicity of fermented Guibi-tang was evaluated on bacterial reverse mutation in Salmonella and Escherichia spp., chromosome aberrations in Chinese hamster ovary cells, and micronucleus formation in mice. Ingredients in FGBT were identified and quantified by high performance liquid chromatography–mass spectrometry. ResultsIn acute oral toxicity study, behavior, clinical signs and body weight changes were normal observing in all experimental animals. No revertant colonies were found in any bacterial cultures examined. Morphological or numerical anomalies and significant increased number of aberrant metaphases were not observed. Micronucleus assay showed no significant increases in the frequency of inducing micronuclei in any dose examined. Decursinol, decursin, glycyrrhizin, and 6-gingerol in fermented Guibi-tang were identified and quantitated. As a whole, no acute and genotoxic effects were found in all the assays and parameters analyzed. ConclusionFermented Guibi-tang was recognized as safe and non-toxic, and therefore can be used for applications of traditional medicine in modern complementary and alternative therapeutics and health care.

Effects of Petroselinum crispum and Coriandrum sativum on Oral Cadmium-induced Micronucleus Formation in Mice

Effects of Petroselinum crispum and Coriandrum sativum on Oral Cadmium-induced Micronucleus Formation in Mice

Chloroacetaldehyde Induces Chromosome Aberrations and Micronucleus Formation but Not 2-chloroethanol

2-Chloroethanol (2-CE) has been used on grapevines to accelerate grape growth, and its metabolite, chloroacetaldehyde (CAA), accumulated in the liver and blood from rats intoxicated with 2-CE. Chronic occupational injury might be a possible reason for the 2-CE intoxication. In this study, we used the in vitro and in vivo tests to examine the genotoxicity of 2-CE and CAA. First, 2-CE did not induce chromosome aberration formation in Chinese ovary hamster cells, but CAA did induce chromosome aberration formation, especially the chromosome gap-type aberration after S9 activation. Second, 2-CE at high doses (1/2 LD50), but not at low doses, induced peripheral blood micronucleus formation in mice. CAA induced micronucleus formation at low and high dosages (1/8-1/2 LD50). These results indicated that CAA plays an important role in 2-CE chronic intoxication, and the genotoxic mechanisms of CAA require further study.

Antimutagenic Effect of Phenethyl Isothiocyanate

Using the Ames bacterial mutagenicity test, the comet assay, and an in vivo micronucleus test, we investigated the effect of the chemoprotective substance phenethyl isothiocyanate (PEITC) on the mutagenic activity of indirect-acting mutagens and carcinogens aflatoxin B1 (AFB1) and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), and direct-acting mutagen and carcinogen N-nitroso-N-methylurea (MNU). In the Ames test, the antimutagenic activity of PEITC was studied in the concentration range 0.3-300 microg/plate. PEITC at concentrations of 0.3, 3 and 30 microg/plate reduced dose-dependently mutagenicity of AFB1 and IQ in both S. typhimurium TA98 and TA100 strains. In the case of the direct mutagen MNU, the antimutagenic effect of PEITC was detected only at concentration of 30 microg/plate in the strain TA100. The PEITC concentration 300 microg/plate was toxic in the Ames test. The 24 h pre-treatment of HepG2 cells with PEITC at concentration 0.15 microg/ml resulted in a significant decrease of DNA breaks induced by MNU at concentrations 0.25 and 0.5 mM. Although a trend towards reduced strand break level were determined also at PEITC concentrations 0.035 and 0.07 microg/ml it did not reach the statistical significance. No effect, however, of PEITC on IQ-induced DNA breaks was observed. Chemopreventive effect of PEITC was revealed also in vivo. Pretreatment of mice with PEITC concentrations of 25 and 12.5 mg/kg b.w. administered to mice in three daily doses resulted in reduction of micronucleus formation in mice exposed to all three mutagens under study, with statistically significant effect at concentration of 25 mg/kg. Results of this study indicate that the strong PEITC antimutagenic properties may have an important role in the prevention of carcinogenesis and other chronic degenerative diseases that share some common pathogenetic mechanisms.

Hypoxia-Induced Micronucleus Formation in Mice

The effect of hypoxia on micronucleus formation in mice was evaluated using special “shoebox” cages containing a silicone rubber membrane that effectively excludes the replacement of cage oxygen as it is spent by group-housed mice. In five separate trials using between 13 and 17 mice per cage, the oxygen level in the cage was reduced from the normal 21% to an average of 7.5% in 3–7 days. Compared to control animals, which exhibited a spontaneous micronuclei (MN) frequency of 0.08%, mice living under hypoxic conditions exhibited a statistically significant (p ≤ 0.01) elevation in MN frequency of 0.15%. These findings may be relevant to in vivo studies in which drug or chemical treatment results in hypoactivity or complete sedation accompanied by varying degrees of hypoxia. It is proposed that structurally unexpected positive clastogenicity findings in animals exposed to these conditions may be due to hypoxia rather than to drug–DNA interaction. The likely mechanistic basis for this effect, decreased fidelity of cell division under conditions of elevated erythropoiesis, is discussed.

Genotoxicity and toxicological effects of acrylamide on reproductive system in male rats

The toxicity of acrylamide was evaluated through mutagenicity of Salmonella, chromosome aberration of Chinese hamster lung fibroblasts, micronucleus formation in mice and reproductive toxicity in rats. Based on Ames test, acrylamide showed mutagenic potency for strains TA98 and TA100. Moreover, both chromosomal aberration assay and micronucleus assay indicated that acrylamide might have genotoxic potency; the chromosomal aberration frequencies were observed to be proportional to acrylamide concentrations of 5-50 mM, and acrylamide significantly increased micronuclei in peripheral blood cells of mice at doses of higher than 72.5 mg/kg. Male rats were treated with acrylamide at doses of 0, 5, 15, 30, 45, or 60 mg/kg/day for 5 consecutive days, and the toxicity of acrylamide was observed. In the group treated with the highest dose of acrylamide (60 mg/kg/day), the loss of body weight and reduced testis weight were observed. Also the epididymides weights were reduced significantly in all the groups treated with acrylamide. The number of sperms in cauda epididymidis decreased significantly in an acrylamide dose-dependent manner. Rats treated with 60 mg/kg/day of acrylamide showed several histopathological lesions in the seminiferous tubules. There were thickening and multiple layering of the tubular endothelium, and the formation of many multinucleated giant cells in seminiferous tubules. Taken together, acrylamide not only causes the genotoxicity of eukaryotic cells and mice but also shows the toxicological effects on reproductive system in male rats.

3-Nitrobenzanthrone (3-NBA) induced micronucleus formation and DNA damage in human hepatoma (HepG2) cells

3-Nitrobenzanthrone (3-NBA), identified in diesel exhaust and in airborne particulate matter, is a potent mutagen in Salmonella, induces micronuclei formation in mice and in human cells and DNA adducts in rats. In the present study, we investigated the genotoxic potency of 3-NBA in human HepG2 cells using the micronucleus (MN) assay and the single cell gel electrophoresis (SCGE). 3-NBA caused a genotoxic effect at concentrations ≥12 nM in both assays. In the micronucleus assay, we found 98.7±10.3 MN/1000 BNC at a concentration of 100 nM 3-NBA in comparison to 27.3±0.6 MN/1000 BNC with the negative control. At the same concentration, the DNA-migration (SCGE) showed an Olive tail moment (OTM) of 2.7±0.45 and %DNA in the tail of 8.28±0.76; OTM and %DNA in the tail of cells treated with the negative control were 0.73±0.08 and 2.81±0.30, respectively. The results are discussed under consideration of former studies.

INHALATION TOXICITY STUDIES OF THE α,β-UNSATURATED KETONES: Ethyl Vinyl Ketone

The National Toxicology Program is conducting a chemical class study to investigate the structure-activity relationships for the toxicity ofα,β -unsaturated ketones. Ethyl vinyl ketone (EVK) was selected for study because it is a representative straight-chain aliphaticα,β -unsaturated ketone with extensive use and widespread exposure. Short-term inhalation studies of EVK were conducted to provide toxicity data for comparison with the relatedα,β -unsaturated ketones 2-cyclohexene-1-one (CHX) and methyl vinyl ketone (MVK). These data will be used in designing chronic toxicity and carcinogenicity studies of these ketones. Male and female F344 rats and B6C3F1 mice were exposed to 0, 2, 4, or 8 ppm EVK 6 h/day, 5 days/wk for 13 wk. The nasal cavity was the major target organ of EVK in both rats and mice. Pathologic findings in both the olfactory and respiratory epithelium were observed. Lesions consisted primarily of olfactory epithelial necrosis, atrophy and regeneration, and/or hyperplasia and squamous metaplasia of the respiratory epithelium. Squamous metaplasia of the respiratory epithelium was present in all rats and mice exposed to 4 and 8 ppm EVK, and these lesions were more severe in rats than in mice. Few systemic effects were observed in rats and mice exposed to EVK. A transient decrease in total leukocytes due to decrements in lymphocyte and monocyte populations was present in male rats after exposure to 8 ppm for 3 and 21 days; however, this effect was not present after exposure for 13 wk. There were no chemicalrelated effects on micronucleus formation in mice, or on sperm motility and vaginal cytology in either species. EVK, like otherα,β -unsaturated ketones, is a reactive, directacting gaseous irritant with toxicity limited primarily to the upper respiratory tract.

Evaluation of Thimet 10-G for mutagenicity by 4 different genetic systems

The insecticide Thimet 10-G was tested for mutagenic activity by 4 different genetic systems. It was unable to induce gene mutation in Salmonella, transfection inhibition in Mycobacterium, micronuclei formation in mice, and sister-chromatid exchange (SCE) in human lymphocytes were evaluated. It caused in mice an increase in the ratio of normochromatic to polychromatic erythrocytes and in human lymphocytes a decrease in mitotic index and delay in cell cycle. The results indicate that the insecticide is not mutagenic in the 4 test systems used at present.

Mutagenic studies on the insecticide Metasystox-R with different genetic systems

The insecticide Metasystox-R was tested for mutagenic activity by a multiple bioassay. Its potential ability to induce gene mutation in Salmonella, micronuclei formation in mice, and sister-chromatid exchange (SCE) in human lymphocytes was evaluated. The insecticide induced detectable genotoxic effects in these tests. The results support the view that the insecticide is genotoxic.