Frequency Of Micronucleated Polychromatic Erythrocytes Research Articles

Exposure assessment and micronuclei induction in populations exposed to electronic waste in South-West Nigeria

BACKGROUNDInformal electronic waste (e-waste) reprocessing in Nigeria is reportedly substantial in Africa, putting the growing exposed population at high risk of metal toxicity. This study aimed to investigate the existence of chromosomal aberration in the growing e-waste exposed populations in Nigeria, using induction of micronuclei (MN) expression in peripheral blood as an indicator. METHODSIn this cross-sectional study, 632 consenting participants were recruited from South-West Nigeria, consisting of 381 e-waste workers (EWW), 120 environmental e-waste exposed participants (EEP) and 131 age-matched unexposed participants (UP) serving as controls. A validated structured questionnaire was used to assess exposure pattern while frequency of micronucleated polychromatic erythrocytes (MNPCE)/1000PCE in peripheral blood film was determined by modified micronucleus assay. RESULTSA duration of exposure of ³5 years and exposure frequency ³6 hours/day; 6 days/week (9360 hours in any 5-year duration) was observed in both EWW and EEP. Routes of exposure observed in EWW entailed eyes, oral cavity, nasal cavity and skin. EWW that used personal protective equipment (PPE) while working was barely 10.24% while non-PPE users constituted the majority (89.76%) of the studied population. Frequency of MNPCE)/1000PCE in EWW (22.70 ± 0.15) was significantly higher than in EEP (4.17 ± 0.28), which in turn was significantly higher than the lowest frequency (0.99 ± 0.76) observed in UP (p<0.001). CONCLUSIONThe observed exposure pattern and the comparatively higher MN induction in the e-waste populations may suggest risk of significant cytogenetic damage and aberrant chromosomal changes associated with occupational e-waste reprocessing in Nigeria.

Micronuclei in embryos of eight seabird species in northwestern Mexico: A biomarker of exposure to coastal pollution?

The micronucleus (MN) test may be used to evaluate genome instability in birds and the potential of different species to function as biomarkers of genotoxicity. However, little is known regarding genome instability in seabird embryos or the instability present among embryonic development stages. Therefore, the present study aimed to describe the frequencies of micronucleated erythrocytes (MNE) and micronucleated polychromatic erythrocytes (MNPCE) in blood samples collected from the embryos of eight seabird species nesting on the coast of Sinaloa, Mexico. An additional description of blood cell maturation along with embryo development during incubation was conducted based on the proportion of polychromatic erythrocytes (PCE), and the potential relationships between metals (Hg and Cd concentrations in egg content) and the MN frequencies in embryo blood were evaluated. The PCE proportion appears to decline as incubation advances (initial stage > intermediate stage > advanced stage), and the values varied between species (Suliformes/Pelecaniformes < Charadriiformes: Laridae), which may be related to differences among incubation periods and reproductive strategies. Interspecific variation in the MNPCE frequency was found in embryos showing advanced development, which could be related to both variations in life-history traits and ecological factors and not Hg or Cd exposure. The genomic instability values in this study are the first to be reported for embryos of seabird species nesting in a subtropical coastal region.

Inhibitory effects of saeu-jeot extract on NLRP3 inflammasome activation and radiation-induced micronucleus formation.

PurposeSaeu‐jeot, or shrimp paste, is a traditional Korean high‐salt fermented seafood. This study elucidated the effects of saeu‐jeot extract (SJE) on NLRP3 inflammasome activation and radiation‐induced micronucleus formation.MethodWe treated lipopolysaccharide‐primed mouse bone marrow‐derived macrophages with the NLRP3 inflammasome activators ATP and nigericin. We also analyzed the acute effects of ionizing radiation on micronucleated polychromatic erythrocytes (MnPCEs) in whole‐body gamma‐irradiated male BALB/c and C57BL/6 mice after oral administration of SJE.ResultsSJE significantly inhibited NLRP3 inflammasome activation, reducing IL‐1β secretion in vitro. In addition, the frequency of MnPCEs was significantly lower in SJE‐treated mice.ConclusionsSJE has anti‐inflammatory effects and reduces radiation‐induced chromosome damage. Advance in knowledge: There are no reports concerning the effects of SJE on NLRP3 inflammasome activation or radioprotection. This experiment showed the radioprotective effects of saeu‐jeot.

Improved antimutagenic effect of Pyrostegia venusta (Ker Gawl.) Miers nanostructured extract in liposome and polymeric nanoparticle

Pyrostegia venusta (Ker Gawl.) Miers, popularly known as “Cipó-de São-João”, has been used in traditional medicine for its therapeutic properties. Nanotechnology is able to enhance the pharmacological activity of plant extracts. In this context, liposomes and polymeric nanoparticles containing P. venusta ethanolic extract were developed and then physico-chemically characterized to evaluate the mutagenic/antimutagenic effects of P. venusta. In addition, transaminases and serum creatinine were biochemically analyzed for liver and renal damage, respectively. The micronucleus test was performed with male Swiss mice treated orally for 15 consecutive days with free extracts and nanostructured with P. venusta, and then intraperitoneally with N-ethyl-N-nitrosurea (50 mg/kg) on the 15th day of treatment. Micronucleated polychromatic erythrocytes (MNPCE) were evaluated in bone marrow. There was a significant reduction in the frequency of MNPCE (LPEPV = 183% and NPEPV = 114%, p < 0.001), indicating antimutagenic potential of the nanostructured extracts with P. venusta. The groups treated with only nanostructured extract did not show an increase in MNPCE frequency, and biochemical analyzes showed no significant difference between treatments. The liposomes and polymeric nanoparticles containing Pyrostegia venusta ethanolic extract showed biological potential in preventing the first step of carcinogenesis under the experimental conditions.

In vitro and in vivo evaluation of genotoxicity, cytotoxicity, and protective effects of synthetic chalcones (E)-3-(4-chlorophenyl)-1-phenyl-2-propen-1-one (4-CL) and (E)-3-(3,4-dimethoxyphenyl)-1- phenyl-2-propen-1-one (DMF)

The chalcones (E)-3-(4-chlorophenyl)-1-phenyl-2-propen-1-one (4-CL) and (E)-3-(3,4-dimethoxyphenyl)-1-phenyl-2 -propen-1-one (DMF) are versatile and easily synthesized into low-cost compounds that have a wide spectrum of biological activities. In this study, the cytotoxic, genotoxic and modulatory activities of 4-CL and DMF were evaluated using the Ames test and the mouse micronucleus assay. The results of the Ames test revealed that both chalcones did not show mutagenic activity in Salmonella typhimurium strains TA98 and TA100, and demonstrated significant antimutagenicity (p&lt; 0.05) when co-administered with sodium azide (SA) in strain TA100. In the micronucleus assay, both showed a significant increase in the frequency of micronucleated polychromatic erythrocytes (MNPCE) at 24 h and 48 h, revealing a genotoxic effect. In the co-treatment with mitomycin C (MMC) there was a significant decrease (p&lt; 0.05) in the frequency of MNPCE both in chalcones at 24h and in the less concentrated dose of DMF at 48h, demonstrating its antigenotoxic activity. 4-CL showed a significant decrease in the polychromatic/ normochromatic erythrocyte (PCE/ NCE) ratio at 24 and 48 h (p&lt; 0.05), indicating cytotoxicity. However, 4-CL and DMF when co-administered with MMC showed a significant increase in the PCE/NCE ratio within 24 hours, demonstrating anticytotoxicity. Furthermore, a biphasic dose-response behavior was observed in both chalcones, 4-CL in the co-administration with SA, in the Ames Test and DMF in the co-treatment with MMC, at 48 hours of exposure, in the micronucleus assay. In this study, 4-CL and DMF showed genotoxic, cytotoxic, antigenotoxic, anticytotoxic and no mutagenic properties.

Micronucleated erythrocytes in peripheral blood from neonate rats fed by nursing mothers exposed to X-rays.

Most women with breast cancer can become pregnant and give birth while undergoing radiation therapy and breastfeeding is generally not contraindicated. The induction of long-lived reactive species in proteins, such as casein by X-ray radiation and DNA damage to unexposed organisms, has been shown when ingesting irradiated cheese. To determine whether exposing lactating rats to X-rays increases the number of micronucleated erythrocytes (MNEs) in peripheral blood of their unexposed or breastfeeding rat pups, 15 female Wistar rats were divided into three groups: Negative control; Experimental group exposed to X-rays, and group exposed to X-rays plus vitamin C. The mothers of groups 2 and 3 were irradiated for three consecutive days after giving birth, returning them to their respective cages each time to continue lactation. A blood sample was taken from the mothers and pups at 0, 24, and 48 hr. Blood smears were stained with acridine orange to analyze MNEs. In mother rats, the frequency of micronucleated polychromatic erythrocytes (MNPCEs) increased significantly at 24 and 48 hr in both study groups exposed to radiation. Likewise, in rat pups the MNPCE and MNE frequencies increased in both groups with radiation and radiation plus vitamin C at 24 and 48 hr, and a protection from vitamin C was observed. In conclusion, the genotoxic damage produced in rat pups that were lactated by mothers irradiated with X-rays is possibly due to the effect of long-lived reactive species that were formed in the breast milk of female Wistar rats during the irradiation process.

Genotoxicity evaluation using micronucleus test in Rattus norvegicus captured in urban ecosystems of Buenos Aires, Argentina.

The overall goal of the present study was to evaluate and compare the existence of genotoxic damage in Rattus norvegicus captured in sites with different levels of chemical mixtures along the Matanza-Riachuelo river basin(MRRB). For this, thirty-six wild rats (R. norvegicus) were captured from six different sites in the MRRB. Capture sites were characterized with concentrations of 20 parameters in surface water, including concentrations of metals and its soluble state and physicochemical parameters. To evaluate genotoxic damage in the rats, the bone marrow micronucleus test was performed. For this, the frequency of micronucleated polychromatic erythrocytes (MNPCE) was calculated based on the observation of 2000 polychromatic erythrocytes (PCE) per animal. Also, to detect possible cytotoxic effects, the PCE/TE (total erythrocytes) ratio in 1000 erythrocytes/animal was calculated. The frequency of MNPCE was positively associated with the highest concentration of chrome, lead, copper, biological oxygen demand, and chemical oxygen demand. Also, the decrease on PCE/TE ratio in bone marrow was related with increase of practically all metals and physicochemical parameters in surface water. The results of this study reveal that rats that live in the MRRB were exposed to concentrations of pollutants that can cause genotoxic damage, even though the concentrations of these pollutants are mostly below the safety standards. Therefore,this work highlights the importance of using methods that allowto integrate all environmental parametersin risk assessment, such as sentinel species.

Evaluation of Anti-Cytotoxic and Anti-Genotoxic Effects of Nigella sativa through a Micronucleus Test in BALB/c Mice.

Nigella sativa (N. sativa) is a medicinal plant used for its therapeutic pharmacological effects such as anti-inflammatory, antioxidant, anticancer, antidiabetic, and immunomodulation. This study explored the anti-cytotoxic and anti-genotoxic effect of N. sativa through a micronucleus test (MNT) of BALB/c mice peripheral blood. Using 6-to-8-week-old healthy male BALB/c mice, four groups were formed: (1) Control (sterile water), single-dose 2 mg/kg/intraperitoneal (i.p); (2) N. sativa oil, 500 mg/kg/24 h/7 days/i.p; (3) Cisplatin (CP), single-dose 2 mg/kg/subcutaneous (s.c); (4) N. sativa + CP with their respective dosage. When evaluating polychromatic erythrocytes (PCE), a biomarker of cytotoxicity, the group treated with N. sativa + CP experienced an increase in the frequency of PCE, which demonstrated the recovery of bone marrow and modulation of cell proliferation. The analysis of micronucleated polychromatic erythrocytes (MNPCE), an acute genotoxicity biomarker, showed similar frequency of MNPCE within the groups except in CP, but, in the N. sativa + CP group, the frequency of MNPCE decreased and then regulated. Finally, the frequency of micronucleated erythrocytes (MNE), a biomarker of genotoxicity, the supplementation of N. sativa oil did not induce genotoxic damage in this model. Thus, we conclude that N. sativa has both cytoprotective, genoprotective effects and modulates cell proliferation in BALB/c mice.

Evaluation of antimutagenic and cytotoxic activity of skin secretion extract of Rhinella marina and Rhaebo guttatus (Anura, Bufonidae)

ABSTRACT The skin secretion from toads of the Bufonidae family has great potential in the search for new active compounds to be used as drug candidates in treating some diseases, among them cancer. In this context, this study aimed to evaluate the cytotoxic and antimutagenic activity of the parotoid gland secretion extracts of Rhinella marina and Rhaebo guttatus, as well as biochemically analyze transaminases and serum creatinine for liver and renal damage, respectively. Cytotoxicity was performed by the colorimetric method based on MTT (3- [4, 5-dimethyl-2-thiazolyl]-2, 5-diphenyl-2H-tetrazolium bromide) with different concentrations of the extracts in Walker or splenic tumor cell cultures from rats and mice. The micronucleus test was performed with male Swiss mice treated orally with the extracts for 15 days, and then intraperitoneally with N-ethyl-N-nitrosurea (50 mg kg-1). Micronucleated polychromatic erythrocytes (MNPCE) were evaluated in bone marrow. The extracts showed cytotoxic activity in the evaluated cells. There was a significant reduction in the frequency of MNPCE (R. marina = 56% and R. guttatus = 75%, p &lt; 0.001), indicating antimutagenic potential of the extracts. The groups treated only with extract showed an increase in MNPCE frequency, evidencing mutagenic potential. Biochemical analyzes showed no significant difference between treatments. Thus, under our experimental conditions, the extracts of R. marina and R. guttatus skin secretions presented chemopreventive potential for cancer.

Genotoxic evaluation of sibipiruna extract (Caesalpinia peltophoroides Benth) in vivo

Caesalpinia peltophoroides Benth, popularly known as sibipiruna or false brazilwood, is an ornamental species with wood potential and with great distribution in Brazil. The genus Caesalpinia has more than five hundred species, most of which have not yet been studied for their pharmacological potential. Several species of the genus are known for their antioxidant and anti-inflammatory activities. The aim of the present study was to evaluate the effect of sibipiruna leaf and flower extract on Cyclophosphamide (CP) induced DNA damage in male Swiss mice using the micronucleus test. The animals (6 animals/group) were treated for 15 consecutive days with ethanolic extract (via gavage) and on day 15 received intraperitoneally NaCl (0.9%) or CP (25 mg/Kg), being sacrificed 24 hours after treatment to evaluate the frequency of micronucleated polychromatic erythrocytes (MNPCEs). The results showed that pretreatment with the ethanolic flower extract and sibipiruna leaf, under the conditions tested, did not reduce the frequency of MNPCEs induced by CP when compared to the positive control group. However, the groups treated only with the ethanolic extract of sibipiruna flowers and leaves significantly increased the frequency of micronuclei in polychromatic erythrocytes of bone marrow when compared to the negative control group, thus demonstrating a possible mutagenic effect. Therefore, it was possible to verify that sibipiruna did not present antimutagenic activity, but a plant with possible mutagenic action in the concentrations used.

Genetic, reproductive and oxidative damage in mice triggered by co-exposure of nanoparticles: From a hypothetical scenario to a real concern

Humans are potentially exposed to multiple nanoparticles kinds through nanotechnology-based consumer products. There is insufficient data on the in vivo toxicity of nanotechnology products, as well as no data on the possible toxicity, including genotoxicity and reproductive toxicity of co-exposure to different kind of nanoparticles. In this work, solid lipid nanoparticles (SLNs) and superparamagnetic iron oxide nanoparticles (SPIONs) were selected for evaluation of a hypothetical condition of in vivo co-exposure. Genotoxicity of SPIONs and SLNs was performed separately and in 1:1 mixture in mice. Bone marrow micronucleus assay, sperm morphology test, and sperm count were carried out. Also, the serum ALT and AST activities; and hematological parameters of the treated mice were analyzed. The results showed a significant increase (p < 0.05) in micronucleated polychromatic erythrocytes (MNPCE) and nuclear abnormalities (NA) in SPIONs, SLNs and their mixture treated mice. The mixture induced the highest frequency of MNPCE and NA. A similar result was observed in the sperm morphology test, with the mixture inducing the highest sperm abnormalities, followed by SLNs and the least by SPIONs. Significant alteration to RDW, MCHC, MCV, GRAN, and platelets, as well as increased activities of serum AST were observed in the mice treated with a mixture of the two kinds of nanoparticles. Calculation of interaction factor showed a possible synergistic effect between SPIONs and SLNs in MNPCE, NA and sperm morphology studied. Even as a hypothetical scenario of co-exposure to SLNs and SPIONs, this study showed, for the first time, that co-exposure to SPIONs and SLNs is more genotoxic to somatic and germ cells than their individual exposure.

Radioprotective effect of grape seed extract against gamma irradiation in mouse bone marrow cells.

Ionizing radiations produce free radicals which are often responsible for DNA damage or cell death. Grape seed extract (GSE) is a natural compound having an antioxidant that protects DNA, lipids, and proteins from free radical damages. In this study, radioprotective effect of the GSE has been investigated in mouse bone marrow cells using micronucleus test. Four groups of mice were investigated in this study: Mice in Group 1 were subjected to injection of distilled water with no irradiation. Mice in Group 2 were exposed to 3 Gy gamma radiation after the injection of distillated water. Mice in Group 3 were injected with 200 mg/kg of the GSE without any irradiation. In another group, mice were exposed to three gray gamma irradiation after the injection of GSE. Animals were killed, and slides were prepared from the bone marrow cells 24 h after irradiation. The slides were stained with May Grunwald-Giemsa method and analyzed microscopically. The frequency of the micronucleated polychromatic erythrocytes (MnPCEs), micronucleated normochromatic erythrocyte (MnNCEs), and polychromatic erythrocyte/polychromatic erythrocyte + normochromatic erythrocyte (PCE/PCE + NCE) ratios was calculated. Injection of GSE significantly decreased the frequency of MnPCEs (P < 0.0001) and MnNCEs (P < 0.05) and increased the ratio of PCE/PCE + NCE (P < 0.0001) compared to the irradiated control group. GSE could reduce clastogenic and cytotoxic effects of gamma irradiation in mice bone marrow cells; therefore, it can be concluded that the GSE is a herbal compound with radioprotective effects against gamma irradiation. Free radical scavenging and the antioxidant effects of the GSE probably are responsible mechanisms for the GSE radioprotective effects.

Protection Against Radiation-Induced Micronuclei in Rat Bone Marrow Erythrocytes by Curcumin and Selenium L-Methionine.

The search for potent radioprotective agents for the amelioration of radiation side effect is an important aim in radiobiology. The present study aimed to evaluate the effects of curcumin and seleno-L-methionine against radiation-induced micronucleus formation in rat bone marrow. In total, 40 male rats were divided into 8 groups (n=5 each), including control, curcumin or seleno-L-methionine treated alone or in combination, 2 Gy irradiation, irradiation of treated groups with curcumin or seleno-L-methionine or their combination. Curcumin was administrated orally and seleno-L-methionine was injected intraperitoneally 24 hours before irradiation. The frequency of micronucleated normochromatic erythrocytes (MnNCEs) and micronucleated polychromatic erythrocytes (MnPCEs) was scored in 5,000 polychromatic erythrocytes (PCEs) and the cell proliferation ratio [(PCE/(PCE+NCE); NCE=normochromatic erythrocytes] was calculated for each treatment group. Data were analyzed by the SPSS software version 16.0 and P<0.05 was considered as statistically significant differences. Pretreatment with curcumin and seleno-L-methionine before irradiation reduced the frequency of MnPCEs and MnNCEs (P=0.01) and increased the cell proliferation ratio. Moreover, the results showed that this pretreatment reduced the frequency of MnPCEs with a protection factor (PF) of 1.2 and 1.6, respectively. The combination of curcumin and seleno-L-methionine in reducing MnPCEs and MnNCEs was not more effective than each agent alone, while improved cell proliferation ratio. Both curcumin and seleno-L-methionine showed potent protection against radiation induced MN in bone marrow cells. The combination of the two agents further ameliorates this activity, thus leading to improve bone marrow protection.

DNA protective effect of rosmarinus officinalis total extract in mouse peripheral blood

Rosmarinus officinalis is a common household aromatic plant widely used in cosmetic, food and folk medicine. The aim of this study was evaluated rosmarinus total extract (RTE) protective effect on DNA damage induced by cyclophosphamide (CP) and evidence the lack of genotoxicity and cytotoxicity of RTE in peripheral blood erythrocytes of Balb-C mice using the micronucleus assay. To evaluate the DNA protective effect, the dose of 100mg/kg of RTE was used and given orally. Following was the admiration of CP (50mg/kg). To evaluated the lack genotoxic or cytotoxic, three doses (30, 100 and 300mg/kg) of RTE were administered orally. A drop of blood was obtained from the tip of the tail of each mouse 24h for six days. We found no increase of micronucleated erythrocytes (MNE) or micronucleated polychromatic erythrocytes (MNPCE). Nor did polychromatic erythrocytes (PCE) decline in mice treated with one of the three different doses of RTE. RTE extracts were capable of diminished DNA damage caused by CP thus reducing MNE and MNPCE frequencies. The lack of genotoxic and cytotoxic effect of the RTE and reduces the genotoxicity caused by CP, suggest the potential therapeutic usefulness of this plant extract.

Assessment of the antioxidant, cytotoxic, and genotoxic potential of the Annona muricata leaves and their influence on genomic stability

ABSTRACT The popular use of Annona muricata L. is based upon a range of medicinal purposes, and the plant exhibits biological activities including antihyperglycemic, antiparasitic, and antitumor activities. The objectives of this study were to examine the antioxidant, cytotoxic, and genotoxic potential of the hydroalcoholic extract of A. muricata leaves (AMEs), as well as its effects on genotoxicity induced by methyl methanesulfonate (MMS) and hydrogen peroxide (H2O2). The results using 2,2-diphenyl-1-picrylhydrazyl assay showed that AME was able to scavenge 44.71% of free radicals. The extract significantly reduced the viability of V79 cells in the clonogenic assay at concentrations ≥8 µg/ml. No significant differences in micronucleus (MN) frequency were observed between V79 cell cultures treated with different concentrations of the extract (0.125, 0.25, 0.5, and 1 µg/ml) and negative control. When AME concentrations were combined with MMS, data revealed no marked differences from mutagen alone. In contrast, significant reductions in the frequencies of MN were noted in cultures treated with AME combined with H2O2 compared to H2O2 alone. In vivo studies found no significant differences in the frequencies of micronucleated polychromatic erythrocytes (MNPCEs) between animals treated with different AME doses compared to control. Animals treated with AME doses of 125 and 250 mg/kg and MMS exhibited significantly higher frequencies of MNPCE compared to mutagen alone. In conclusion, under current experimental conditions, AME was not genotoxic and exerted a modulatory effect on DNA damage depending upon the experimental conditions. The extract did not influence markedly MMS-induced genotoxicity in in vitro test system. However, the extract increased DNA damage induced by mutagen in mice. In V79 cells, AME reduced the genotoxicity produced by H2O2, and this protective effect was attributed in part to the antioxidant activity of AME.

Genotoxicity kinetics in murine normoblasts as an approach for the in vivo action of difluorodeoxycytidine.

This study analyzed the kinetics of in vivo micronucleus induction in normoblasts by determining the kinetics of difluorodeoxycytidine (dFdC)-induced micronucleated polychromatic erythrocytes (MN-PCEs) in the peripheral blood of mice. The kinetic indexes of MN-PCE induction of dFdC were correlated with the previously reported mechanisms DNA damage induction by this compound. In general, this study aimed to establish an in vivo approach for discerning the processes underlying micronucleus induction by antineoplastic agents or mutagens in general. The frequencies of PCEs and MN-PCEs in the peripheral blood of mice were determined prior to treatment and after treatment using dFdC at doses of 95, 190, or 380µmol/kg at 8h intervals throughout a 72h post-treatment. The area beneath the curve (ABC) for MN-PCE induction as a function of time, which is an index of the total effect, indicated that the dose response was directly proportional and that the effect of dFdC on micronucleus induction was reduced compared with that of aneuploidogens and monofunctional and bifunctional alkylating agents but increased compared with that of promutagens, which is consistent with our previous results. The ABC showed a single peak with a small broadness index, which indicates that dFdC has a single mechanism or concomitant mechanisms for inducing DNA breaks. The time of the relative maximal induction (T rmi) indicated that dFdC requires more time to achieve MN-PCE induction compared with aneugens and monofunctional and bifunctional alkylating agents, although it requires a similar time to achieve MN-PCE induction as azacytidine, which is consistent with evidence showing that both agents must be incorporated into DNA for their action to be realized. The timing of maximal cytotoxicity observed with the lowest dFdC dose was correlated with the timing of the main genotoxic effect. However, early and late cytotoxic effects were detected, and these effects were independent of the genotoxic response. A correlation analysis indicated that dFdC appears to induce MN-PCEs through only one mechanism or mechanisms that occur concomitantly, which could be explained by the previously reported concurrent inhibitory effects of dFdC on DNA polymerase alpha, polymerase epsilon, and/or topoisomerase. The timing of maximal cytotoxicity was correlated with the timing of maximal genotoxicity; however, an early cytotoxic effect that appeared to occur prior to the incorporation of dFdC into DNA was likely related to a previously reported inhibitory effect of dFdC on thymidylate synthase and/or ribonucleotide reductase.

Genotoxicity and Oxidative Stress in Wistar Rats Sub-chronically Exposed to Low Level Atrazine

Background: Atrazine is a common herbicide that is routinely applied on corn farmlands. Although a number of studies have reported toxic effects of atrazine in mammalian systems, there is still limited knowledge about its potential toxic effects at low doses. Objectives: This study is therefore aimed at investigating the toxicity of atrazine at a low dose (25 mg/kg/day; approximately 1% of reported LD 50 in Wistar rats during a sub-chronic exposure. Methods: Adult Wistar rats were exposed to 25 mg/kg/day atrazine for 30 or 80 days, after which the peripheral blood frequency of micronucleated polychromatic erythrocytes (MNPCEs), percentage polychromatic erythrocytes (% PCE), blood levels of reduced glutathione (GSH), thiobarbituric acid reactive substances (TBARS) and the activity of glutathione peroxidase (GPx) were determined. Results: The frequency of MNPCEs and the levels of TBARS increased significantly in the atrazine-treated rats compared to the controls at both 30- and 80-days exposure durations while there was no difference in % PCE between the groups. There was no significant difference in the GSH levels and GPx activity between the groups. Conclusion: This study showed that atrazine even at a low dose is mutagenic and causes oxidative stress in exposed rats.

Origanum vulgare leaf extract protects mice bone marrow cells against ionizing radiation.

Ionizing radiation produces free radicals which induce DNA damage and cell death. Origanum vulgare leaf extract (OVLE) is a natural compound and its capability of scavenging free radicals and its antioxidant activity have been demonstrated by many researchers. In this study, using micronucleus assay, radioprotective effect of OVLE against clastogenic and cytotoxic effect of gamma irradiation has been investigated in mice bone marrow cells. OVLE was injected intraperitoneally to the BALB/c mice 1hr prior to gamma irradiation (3Gy) at the doses of 100 and 200 mg/kg. Twenty four hours after irradiation or treatment, animals were killed and smears were prepared from the bone marrow cells. The slides were stained with May Grunwald-Giemsa method and analyzed microscopically. The frequency of micronucleated polychromatic erythrocytes (MnPCEs), micronucleated normochromatic erythrocyte (MnNCEs) and cell proliferation ratio PCE/PCE+NCE (polychromatic erythrocyte/polychromatic erythrocyte + normochromatic erythrocyte) were calculated. The results showed that gamma irradiation (3Gy) increased the frequency of MnPCEs, MnNCEs and reduced the PCE/PCE+NCE ratio in mice bone marrow compared to the non-irradiated control group (p<0.0001). Injection of OVLE significantly reduced the frequency of MnPCEs (p<0.0001) and MnNCEs (p<0.05) and increased the PCE/PCE+NCE ratio as compared to the irradiated control group (p<0.05). It seems that OVLE with its antioxidant properties and its capability of scavenging free radicals and reactive oxygen species can reduce the cytotoxic effects of gamma irradiation in mice bone marrow cells.

Micronucleated Erythrocytes in Peripheral Blood from Neonate Rats Exposed by Breastfeeding to Cyclophosphamide, Colchicine, or Cytosine-Arabinoside.

Genotoxic exposure to chemical substances is common, and nursing mothers could transmit harmful substances or their metabolites to their offspring through breast milk. We explored the possibility of determining genotoxic effects in the erythrocytes of breastfeeding rat pups whose mothers received a genotoxic compound while nursing. Ten groups of female rats and five pups per dam were studied. The control group received sterile water, and the experimental groups received one of three different doses of cyclophosphamide, colchicine, or cytosine-arabinoside. Blood smears were prepared from samples taken from each dam and pup every 24 h for six days. There were increased numbers of micronucleated erythrocytes (MNEs) and micronucleated polychromatic erythrocytes (MNPCEs) in the samples from pups in the experimental groups (P < 0.02) and increased MNPCE frequencies in the samples from the dams (P < 0.05). These results demonstrate the vertical transmission of the genotoxic effect of the compounds tested. In conclusion, assessing MNEs in breastfeeding neonate rats to assess DNA damage may be a useful approach for identifying genotoxic compounds and/or cytotoxic effects. This strategy could help in screening for therapeutic approaches that are genotoxic during the lactation stage and these assessments might also be helpful for developing preventive strategies to counteract harmful effects.

Modulation of hexavalent chromium-induced genotoxic damage in peripheral blood of mice by epigallocatechin-3-gallate (EGCG) and its relationship to the apoptotic activity

ABSTRACTThis study was conducted to investigate the relationship between modulation of genotoxic damage and apoptotic activity in Hsd:ICR male mice treated with (–)-epigallocatechin-3-gallate (EGCG) and hexavalent chromium [Cr(VI)]. Four groups of 5 mice each were treated with (i) control vehicle only, (ii) EGCG (10 mg/kg) by gavage, (iii) Cr(VI) (20 mg/kg of CrO3) intraperitoneally (ip), and (iv) EGCG in addition to CrO3 (EGCG-CrO3). Genotoxic damage was evaluated by examining presence of micronucleated polychromatic erythrocytes (MN-PCE) obtained from peripheral blood of the caudal vein at 0, 24, 48, and 72 h after treatment. Induction of apoptosis and cell viability were assessed by differential acridine orange/ethidium bromide (AO/EB) staining. EGCG treatment produced no significant changes in frequency of MN-PCE. However, CrO3 treatment significantly increased number of MN-PCE at 24 and 48 h post injection. Treatment with EGCG prior to CrO3 injection decreased number of MN-PCE compared to CrO3 alone. The MN-PCE reduction was greater than when EGCG was administered ip. The frequency of early apoptotic cells was elevated at 48 h following EGCG, CrO3, or EGCG-CrO3 exposure, with highest levels observed in the combined treatment group, while the frequencies of late apoptotic cells and necrotic cells were increased only in EGCG-CrO3 exposure. Our findings support the view that EGCG is protective against genotoxic damage induced by Cr(VI) and that apoptosis may contribute to elimination of DNA-damaged cells (MN-PCE) when EGCG was administered prior to CrO3. Further, it was found that the route of administration of EGCG plays an important role in protection against CrO3-induced genotoxic damage.