Chemoprotective effects of carnosine against genotoxicity induced by cyclophosphamide in mice bone marrow cells

The protective effects of carnosine as a natural dipeptide were investigated in mouse bone marrow cells against genotoxicity induced by cyclophosphamide. Mice were injected with solutions of carnosine at three different doses (10, 50 and 100?mg kg(-1) bw) for five consecutive days. On the fifth day of treatment, mice were injected cyclophosphamide and killed after 24?h. The frequency of micronuclei in polychromatic erythrocytes and the ratio of polychromatic erythrocyte/polychromatic erythrocyte?+?normochromatic erythrocyte [PCE/(PCE?+?NCE)] were evaluated by May-Grunwald/Giemsa staining. Histopathology of bone marrow was examined in mice treated with cyclophosphamide and carnosine. Carnosine significantly reduced micronucleated polychromatic erythrocytes (MnPCEs) induced by cyclophosphamide at all three doses. Carnosine at dose of 100?mg kg(-1) bw reduced MnPCEs 3.76-fold and completely normalized the PCE/(PCE?+?NCE) ratio. Administration of carnosine inhibited bone marrow toxicity induced by cyclophosphamide. It appeared that carnosine with protective activity reduced the oxidative stress and genotoxicity induced by cyclophosphamide in bone marrow cells of mice. Copyright ? 2012 John Wiley & Sons, Ltd.     

Anticlastogenicity of two derivatives of 1,4-dihydroisonicotinic acid in mouse micronucleus test

Effects of two derivatives of 1,4-dihydroisonicotinic acid (1,4-DHINA) against the monofunctional alkylating agent ethyl methanesulfonate (EMS) were studied in the micronucleus test in (CBA x C57Bl/6(j)) mice. Adult males and pregnant females were treated with an antimutagen (i.p.) and 12h later they were exposed to EMS (i.p.). The frequencies of micronucleated (MN) polychromatic erythrocytes (PCEs) in mouse bone marrow and foetal liver were analysed 6, 12, 18, 24, 30, 36, 48 or 24, 48 and 72 h after the mutagen injection. In adults, the maximum number of MNPCEs was observed 36 or 24h after the EMS administration. In foetuses, which were treated in a maternal organism, such peak was found at 24h. Pre-treatment of mice with the antimutagens 2,6-dimethyl-3,5-diethoxycarbonyl-4-(Na carboxylate)-1,4-dihydropyridine (DHP) and glutapyrone (GP) decreased the yield of MNPCEs in male bone marrow. Having been observed at a peak of MN induction, the anticlastogenic effect of DHP (1/10 LD(50) or 340 mg/kg) reached 30%. DHP at the doses of 0.5-1mM/kg did not affect the EMS-induced frequency of MNPCEs in bone marrow, whereas GP inhibited it at the similar millimolar concentrations. Simultaneously with maternal bone marrow, foetal liver cells were analysed for MNs in the transplacental test. The anticlastogenic effect of DHP (1/10 LD(50)) was found to be more prolonged and higher in females than in males and to average 50%, but this antimutagen was not efficient in foetuses. Both antimutagens did not change the polychromatic/normochromatic erythrocyte (PCE/NCE) ratio as compared with EMS action.Results presented indicate a peak of EMS-induced micronucleated cells in mouse bone marrow 24 or 36 h and in foetal liver 24h after animal treatment. Two 1,4-DHINA derivatives exhibited anticlastogenic activity in adults, but not in foetuses.     

Captopril protects mice bone marrow cells against genotoxicity induced by gamma irradiation

The radioprotective effects of captopril were investigated by using the micronucleus test for anticlastogenic and cell proliferation activity. A single intraperitoneal administration of captopril at doses of 10, 25 and 50 mg/kg 1 h prior to gamma irradiation (2 Gy) reduced the frequencies of micronuleated polychromatic erythrocytes (MnPCEs). All three doses of captopril significantly reduced the frequencies of MnPCEs and increased polychromatic erythrocytes (PCE)/PCE+NCE (normochromatic erythrocyte) ratio in mice bone marrow compared to the non-drug-treated irradiated control (p < 0.001). The optimum dose for protection in mouse was 10 mg/kg to protect mice bone marrow 2.18-fold against the clastogenic effects of gamma-irradiation with respect to the non-drug-treated irradiated control. There was a drug dose-response effect of captopril in increasing the PCE/PCE+NCE ratio in bone marrow cells. The maximum protective effect of captopril was at a dose of 25 mg/kg for increasing the PCE/PCE + NCE ratio. Captopril exhibited concentration-dependent antioxidant activity, scavenging > 96% of the 1,1-diphenyl-2-picryl hydrazyl free radicals when used at a concentration of 0.2 mM. In this study captopril reduced lipid peroxidation induced by hydrogen peroxide in mice liver. It appears that captopril, due to its free radical scavenging properties, protects mice bone marrow cells from radiation-induced DNA damage and genotoxicity.     

Induction of micronuclei and nuclear abnormalities in erythrocytes of mosquito fish (Gambusia affinis) following exposure to the pyrethroid insecticide lambda-cyhalothrin

In the present study the induction of micronuclei (MN) and nuclear abnormalities (NA) in erythrocytes of mosquitofish (Gambusia affinis) (Baird & Girard 1853) was studied. Fish were exposed to three different concentrations of lambda-cyhalothrin (LCT) (1×10(-4)μg/l, 2×10(-4)μg/l, 4×10(-4)μg/l) for periods of 6, 12, 24, and 48h. NA (notched, lobed, blebbed nuclei), MN, bi-nucleated cells, and the ratio of polychromatic erythrocytes (PCEs) to normochromatic erythrocytes (NCEs) were evaluated to assess genotoxicity and cytotoxicity. LCT significantly induced MN and NA in erythrocytes of G. affinis. The PCE/NCE ratio was also decreased after 24- and 48-h treatments of 4×10(-4)μg/l LCT. The results show that LCT has genotoxic and cytotoxic potential on G. affinis.     

Genotoxicity, cytotoxicity and toxicological evaluation of whole plant extracts of the medicinal plant Phyllanthus niruri (Phyllanthaceae)

Phyllanthus niruri is a medicinal plant (commonly known as stone breaker) found in the tropics and other parts of the world. It is known for its capacity to block the formation of calcium oxalate crystals and kidney stone formation in urolithiasis. This plant has been used to treat hyperglycemia, hypertension, pain, and mild cases of malaria. We examined the geno-, cyto- and overall toxicity of P. niruri whole plant ethanolic extract. The extract was administered as a single dose of 30 or 300 mg/kg to laboratory rats by gavage, accompanied by negative (0.9% saline) and positive (10 mg/mL N-ethyl-N-nitrosourea) controls that were injected intramuscularly 48 h after extract administration. The ratio of polychromatic (PCE)/normochromatic erythrocytes (NCE) from femur bone marrow was scored for genotoxicity. Cytotoxicity was determined using descending concentrations (0.2-0.0125 g/mL) of the extract incubated with peripheral blood mononuclear cells. Lactate dehydrogenase release from damaged cells was determined and the CC(50) calculated. Subchronic administration of the extract at 30 or 300 mg/kg was done for 90 days to determine general toxicity. PCE:NCE (%) for the extract and negative control was 63, compared to 168 (positive control). The CC(50) was 26.3 mg/mL and hepato-renal toxicity after subchronic extract administration was nil. We conclude that ethanol extract of P. niruri is not cytotoxic or genotoxic, and is generally non-toxic on subchronic administration.     

Genotoxic,Cytotoxic, Antigenotoxic,and Anticytotoxic Effects of Sulfonamide Chalcone Using the Ames Test and the Mouse Bone Marrow Micronucleus Test

Chalcones present several biological activities and sulfonamide chalcone derivatives have shown important biological applications, including antitumor activity. In this study, genotoxic, cytotoxic, antigenotoxic, and anticytotoxic activities of the sulfonamide chalcone N-{4-[3-(4-nitrophenyl)prop-2-enoyl]phenyl} benzenesulfonamide (CPN) were assessed using the Salmonella typhimurium reverse mutation test (Ames test) and the mouse bone marrow micronucleus test. The results showed that CPN caused a small increase in the number of histidine revertant colonies in S. typhimurium strains TA98 and TA100, but not statistically significant (p > 0.05). The antimutagenicity test showed that CPN significantly decreased the number of His⁺ revertants in strain TA98 at all doses tested (p < 0.05), whereas in strain TA100 this occurred only at doses higher than 50 μg/plate (p < 0.05). The results of the micronucleus test indicated that CPN significantly increased the frequency of micronucleated polychromatic erythrocytes (MNPCE) at 24 h and 48 h, revealing a genotoxic effect of this compound. Also, a significant decrease in polychromatic/normochromatic erythrocyte ratio (PCE/NCE) was observed at the higher doses of CPN at 24 h and 48 h (p < 0.05), indicating its cytotoxic action. CPN co-administered with mitomycin C (MMC) significantly decreased the frequency of MNPCE at almost all doses tested at 24 h (p < 0.05), showing its antigenotoxic activity, and also presented a small decrease in MNPCE at 48 h (p > 0.05). Additionally, CPN co-administered with MMC significantly increased PCE/NCE ratio at all doses tested, demonstrating its anticytotoxic effect. In summary, CPN presented genotoxic, cytotoxic, antigenotoxic, and anticytotoxic properties.     

Technical aspects of automatic micronucleus analysis in rodent bone marrow assays

The mouse bone marrow micronucleus assay is anin vivo test commonly used in the pharmaceutical industry to evaluate the genotoxic potential of new compounds. The test detects agent-induced chromosomal damage or damage of the mitotic spindle apparatus. In this paper the state-of-the-art in automated rodent micronucleus evaluation using computerized image analyis in combination with high-quality slides obtained by the cellulose column fractionation technique is reviewed. The latter allows the effective removal of nucleated cells from rodent bone marrow. It has been found that automatic micronucleus scoring with the Leitz MIAC image analyzer is substantially faster than labor-intensive manual analysis. Automatic scoring can be performed overnight for up to 16 slides. We have been successfully using automatic micronucleus analysis for the testing of new pharmaceutical drugs for more than 3 years.Abbreviations MNE NCE containing micronuclei - MPE PCE containing micronuclei - NCE normochromatic erythrocyte - PCE polychromatic erythrocyte deceased on 25 May 1994     

Multi-endpoint biological monitoring of phosphine workers

5-Aminosalicylic acid (5ASA), a prescribed drug for ulcerative colitis, is a potent scavenger of oxygen-derived free radicals. The present study was undertaken to ascertain its ability to protect against radiation-induced damage. The drug dose-dependent effect, optimum time of drug administration and radiation dose-dependent effect (0-4 Gy) on in vivo radiation protection against micronuclei induction in polychromatic erythrocytes (PCE) and normochromatic erythrocytes (NCE) were studied in the bone marrow of mice. Intraperitoneal injection of 10-125 mg/kg of the drug 30 min before whole body irradiation with 3 Gy produced a significant reduction in the frequency of micronucleated erythrocytes at 24 h after exposure. The optimum dose for protection without drug toxicity was 25 mg/kg body weight. Injection of 25 mg/kg of the drug 60 or 30 min before or within 15 min after 3 Gy whole body gamma-irradiation resulted in a significant decrease in the radiation-induced PCE and NCE with micronuclei (MPCE and MNCE) and an increase in the ratio of PCE to NCE (P/N), at 24 h post-irradiation. Maximum effect was seen when the drug was administered 30 min before irradiation. Therefore, to study the radiation dose-response, mice were pre-treated with 25 mg/kg of 5ASA 30 min before 1-4 Gy of gamma-irradiation. Radiation increased the MN frequency linearly (r(2)=0.99) with dose. Pre-treatment with 5ASA significantly reduced the MN counts to 40-50% of the radiation (RT) alone values, giving a dose modification factor (DMF) of 2.02 (MPCE) and 2.53 (MNCE). Irradiation resulted in a dose-dependent decline in the P/N ratio at all the doses of radiation studied. 5ASA produced a significant increase in the P/N ratio from that of irradiated controls, at all doses of radiations tested. These results show that 5ASA protect mice against radiation-induced MN formation and mitotic arrest.     

Effects of long term low dose acrylamide exposure on rat bone marrow polychromatic erythrocytes

Abstract

I investigated whether long term low dose exposure to acrylamide increased micronucleus frequency in rat bone marrow polychromatic erythrocytes (PCEs). Twenty-five male and 25 female Wistar rats were used. Animals of each sex were segregated into two treatment groups and one control group. Each treatment group consisted of ten animals and each control group consisted of five animals. Acrylamide, 2 or 5 mg/kg/day, was administered to the treatment groups in their drinking water for 90 days. Twenty-four hours after the last treatment, bone marrow samples were obtained and analyzed for the frequency of micronucleated polychromatic erythrocytes (MNPCEs). The cytotoxic effect of acrylamide on bone marrow also was tested by assessing the polychromatic erythrocyte/normochromatic erythrocyte (PCE/NCE) ratio. Both doses of acrylamide significantly increased the frequency of MNPCEs in both male and female rats. Acrylamide also decreased the PCE/NCE ratio in both sexes compared to the control group. My study showed that chronic low dose exposure to acrylamide increased the formation of micronuclei in PCEs of male and female rat bone marrow.     

Genotoxic and Cytotoxic Effects of Antiretroviral Combinations in Mice Bone Marrow

Commonly used guidelines for the management of human immunodeficiency virus (HIV) infection (highly active antiretroviral therapy, HAART) include drug combinations such as tenofovir disoproxil fumarate (TDF) + lamivudine (3TC) and combivir [zidovudine (AZT) + 3TC] + efavirenz (EFV). These combinations may enhance the genotoxic effects induced by such drugs individually, since the therapy requires lifelong adherence and the drugs have unknown effects during treatment. Thus, the evaluation of the benefits and risks of HAART is of great importance. In order to assess the cytotoxic and genotoxic potential of three concentrations of each of the antiretroviral combinations TDF + 3TC (800 + 400, 1600 + 800, and 3200 + 1600 mg/kg body weight, BW) and combivir + EFV (200 + 100 + 400, 400 + 200 + 800, and 800 + 400 + 1600 mg/kg BW) after two exposure periods (24 h and 48 h), in the present study the in vivo comet assay (single-cell gel electrophoresis) and the mouse bone marrow micronucleus test were used. Neither TDF + 3TC nor combivir + EFV induced DNA damage at any concentrations tested after 24 h or 48 h using the comet assay. After 24 h, both combinations increased the micronucleus frequency at all concentrations tested. After 48 h, combivir + EFV increased the micronucleated polychromatic erythrocyte (MNPCE) frequency at the two highest concentrations tested. Polychromatic erythrocytes (PCE)/normochromatic erythrocytes (NCE) ratio was high for both combinations, suggesting that they can be mitogenic. Since genotoxicity may be related to carcinogenesis, it is necessary to conduct further studies to verify the long-term mutagenic effects of these drugs.     

Benzophenone guttiferone A from Garcinia achachairu Rusby (Clusiaceae) Presents Genotoxic Effects in Different Cells of Mice

Benzophenones from natural sources and those of synthetic analogues present several reports of potent biological properties, and Guttiferone A represents a promising medicinal natural compound with analgesic and gastroprotective profiles. Considering that there are no reports that assess the genetic toxicity of Guttiferone A, the present study was undertaken to investigate the genotoxic potential of this benzophenone isolated from seeds of Garcinia achachairu in terms of DNA damage in different cells of Swiss albino mice using the comet assay, and its clastogenic/aneugenic effects in bone marrow cells in vivo by the micronucleus test. Cytotoxicity was assessed by scoring polychromatic (PCE) and normochromatic (NCE) erythrocytes ratio. Guttiferone A was administered by oral gavage at doses of 15, 30 and 60 mg/kg. The results showed that Guttiferone A produced genotoxic effects in leukocytes, liver, bone marrow, brain and testicle cells and clastogenic/aneugenic effects in bone marrow erythrocytes of mice. The PCE/NCE ratio indicated no cytotoxicity. Since guttiferone A is harmful to the genetic material we suggest caution in its use by humans.     

Cytogenetic studies in mice treated with the jet fuels, Jet-A and JP-8

The genotoxic potential of the jet fuels, Jet-A and JP-8, were examined in mice treated on the skin with a single dose of 240 mg/mouse. Peripheral blood smears were prepared at the start of the experiment (t = 0), and at 24, 48 and 72 h following treatment with jet fuels. Femoral bone marrow smears were made when all animals were sacrificed at 72 h. In both tissues, the extent of genotoxicity was determined from the incidence of micronuclei (MN) in polychromatic erythrocytes. The frequency of MN in the peripheral blood of mice treated with Jet-A and JP-8 increased over time and reached statistical significance at 72 h, as compared with concurrent control animals. The incidence of MN was also higher in bone marrow cells of mice exposed to Jet-A and JP-8 as compared with controls. Thus, at the dose tested, a small but significant genotoxic effect of jet fuels was observed in the blood and bone marrow cells of mice treated on the skin.     

Vinblastine treatment induces dose-dependent increases in the frequency of micronuclei in mouse bone marrow.

The effect of various doses (0.005-2.0 mg/kg b.w.) of vinblastine sulfate (VBL) was studied on the induction of micronuclei in polychromatic and normochromatic erythrocytes (PCE, NCE) of the bone marrow of female BALB/c mice. VBL treatment resulted in a dose-dependent increase in the frequency of micronucleated PCE and NCE, while the PCE/NCE ratio and mitotic index declined with increasing drug dose. The dose-effect curves were linear quadratic for all the parameters studied.     

Lack of micronuclei induction by fumonisin B1 mycotoxin in BALB/c mice

The genotoxic potential of fumonisin B₁ (FB₁) in vivo in BALB/c mice (male and female) was assessed by induction of micronuclei (MN) formation in bone marrow polychromatic erythrocytes. The ratio of polychromatic erythrocytes to normochromatic erythrocytes (PCE/NCE) was also determined. Mice were injected intraperitoneally (i.p.) with FB₁ at a low dose (0.1 mg?kg^?1 body mass), middle dose (1.0 mg?kg^?1 body mass) and high dose (10 mg?kg^?1 body mass) as single and multiple doses in normal saline to test the genotoxicity. Mitomycin C, a known clastogen, was used as positive control. The frequency of MN and the PCE/NCE value in animals treated with FB₁ at low, middle, and high doses in single dose studies, and the frequency of MN in multiple dose studies, were statistically non-significant from that of the controls injected with saline only. The multiple dose studies at all doses revealed that the PCE/NCE value was found to be reduced upon exposure to FB₁ as compared to the controls. In animals injected with multiple low doses of FB₁, the PCE/NCE value was found to be 0.66 in males and 0.82 in the females; at multiple middle doses the value was 0.30 in males and 0.41 in the females and was statistically significant (p?<?0.001); however, at multiple high doses, the ratio was found to be 0.36 in both males and females. The present study confirms that FB₁ is non-genotoxic in nature while the reduced ratio of PCE/NCE suggests the cytotoxic nature of FB₁.     

Induction of micronuclei in wild-type and p53(+/-) transgenic mice by inhaled bromodichloromethane

Bromodichloromethane (BDCM) is commonly present in trace amounts in drinking water as a disinfection by-product. BDCM has been shown to be carcinogenic in mice and rats when given by gavage at relatively high doses. Genotoxic activity as well as induced regenerative cell proliferation may contribute to the carcinogenic potential of BDCM. The purpose of the current studies was to evaluate the ability of BDCM to induce micronuclei (MN) in bone marrow and blood of wild-type and p53(+/-) mice on the C57BL/6 and FVB/N genetic backgrounds using the inhalation route of exposure. Toxicity studies were being conducted in this laboratory with inhaled BDCM to select doses for longer-term cancer bioassays using wild-type and p53(+/-) transgenic mice on different genetic backgrounds. Bone marrow samples from these experiments were evaluated for the induction of MN after 1 and 3 weeks of exposure. Accumulation of MN in the peripheral blood was also evaluated at the 13-week time point of a cancer study with the p53(+/-) mice. For the 1-week time point, male C57BL/6 wild-type and p53(+/-) mice and FVB/N wild-type and p53(+/-) mice were exposed daily for 6h per day for 7 consecutive days to atmospheric BDCM concentrations of 0, 1, 10, 30, 100, or 150 ppm. In a second experiment, mice were exposed daily for 6h per day for 3 weeks to atmospheric BDCM concentrations of 0, 0.5, 1, 3, 10, or 30 ppm. Resulting levels of polychromatic erythrocytes (PCE) containing MN were assessed in the bone marrow. For all of the 1- and 3-week exposure groups, the only statistically significant increase in the percentage of bone marrow PCE cells containing MN was in the 1-week 100 ppm BDCM exposure group in the FVB/N wild-type mice (control 0.26% versus exposed 1.16%). C57BL/6 p53(+/-) mice and FVB/N p53(+/-) mice were exposed daily for 6 h per day for 13 weeks to atmospheric BDCM concentrations of 0, 0.5, 3, 10, or 15 ppm. MN were quantified in samples of peripheral blood. Statistically significant increases in the percentage of peripheral blood NCE cells containing MN were seen at the highest BDCM exposure group of 15 ppm in both the C57BL/6 p53(+/-) strain (control 0.36% versus exposed 0.67%) and the FVB/N p53(+/-) strain (control 0.36% versus exposed 0.86%). These data indicate weak induction of MN by BDCM, but only at high atmospheric concentrations relative to normal environmental exposures and with extended periods of exposure. Although comparisons are difficult because responses were negative or marginal, the p53 genotype or the genetic background did not appear to substantially alter susceptibility to the genotoxic effects of BDCM.     

Effect of 6-nonadecyl salicylic acid and its methyl ester on the induction of micronuclei in polychromatic erythrocytes in mouse peripheral blood

The bark of Amphipterygium adstringens is widely used in the traditional Mexican medicine for treating ailments such as gastric ulcers, gastritis and stomach cancer. The 6-nonadecyl salicylic acid (anacardic acid) was isolated from the bark of this species. In previous papers have been informed that the anacardic acids possess anti-tumour, antimicrobial, antiacne, antibacterial and many others medicinal properties. Now we describe cytotoxic and genotoxic effects of this compound and its methyl ester. The cytotoxic and genotoxic effects of 6-nonadecyl salicylic acid (6NDSA) and its methyl ester (ME6NDSA) on CD1 male mice were determined with micronucleus assay at 24, 48 and 72h after oral administration of doses of 0.75, 2.5, 5.0 and 10.0mg/kg. Peripheral blood samples were drawn from the caudal vein and analyzed by Giemsa-stained technique. The results obtained showed that the ratios of polychromatic erythrocytes (PCE) to normochromatic erythrocytes (NCE) in mice treated with 10mg/kg of 6NDSA were statistically lower after 24h compared with its negative control animals, and that after 72h, PCE/NCE ratios were reduced in animals treated with 6NDSA at all tested dose levels. The methyl ester ME6NDSA showed no such cytotoxic activity. Neither of the test compounds increased the frequency of micronucleated polychromatic erythrocytes from which it appears that administration of 6NDSA and ME6NDSA may not lead to chromosome damage at the evaluated doses.     

Genotoxic action of Luna Experience-SC 400 fungicide on rat bone marrow

Abstract

Background: Fungicides describe all chemicals used to control fungi that infect plants. Luna Experience SC-400 is a new line of fungicide that consist of Fluopyram and Tebuconazole.

Objective: In this study, We investigated the genotoxicty and cytotoxicty of Luna Experience-SC 400 using comet assay, micronucleus test and polychromatic erythrocytes number in rat bone marrow. The present study is the first report indicating the effects of genotoxic and cytotoxic of Luna experience SC-400 on rat bone marrow cells.

Material and Methods: We used three different doses (5mg/kg, 10mg/kg, 20mg/kg) of Luna Experience SC 400 at 48 h intervals during 30 days by gavage in rats.Genotoxicity was evaluated using comet assay and micronucleus test and cytotoxicity was measured the PCE/NCE rate in rat bone marrow.

Results: Based on these experimental results, we report that Luna Experience-SC 400 fungicide presents genotoxic and cytotoxic potential on rat bone marrow. There is a significant difference between negative control group and all the doses of Luna Experience-SC 400 (p?<?0.05) for comet assay and micronucleus. Even moderate and high doses of fungicides seem to have reached the values of almost positive control group for Genetic Damage Index (GDI) and Damaged Cell Percentage (DCP). In this study, we also investigated the PCE/NCE rate. Fungicide caused a decrease in the level of significant in the PCE/NCE ratio (p?<?0.05).

Conclusion: Our in vivo study suggests that the gavage exposure to Luna experience SC 400 used in the present investigation may be genotoxic and cytotoxic in rat bone marrow in view of these findings. Because this findings is first report represented in the pesticide biology, it is important to carry out more investigations using various cytogenetic tests under different experimental conditions to definitively resolve the the possible genotoxic and cytotoxic risk associated with new generation pesticides-fungicides.     

Effect of food and water deprivation on the parameters of the mouse bone marrow micronucleus test

This study reports the influence of acute starvation on spontaneous and cyclophosphamide (CP) induced micronucleus (MN) frequencies in the bone marrow polychromatic erythrocytes (PCE) of CD-1 mice. Groups of mice (5/sex) were deprived of either food alone or food and water for 0, 24, 48 and 72 h prior to sacrifice. Although there was no evidence of a significant increase in MN-PCE frequencies among the starved groups, a significant depressant effect of starvation on erythropoietic activity was observed. Peak levels of CP-induced (40 mg/kg b.w.) MN-PCE's appeared later in male mice deprived of food and water after treatment compared to mice given food and water ad libitum. The results indicate that starvation is detrimental to bone marrow erythropoiesis and that starvation may alter the response of mice to clastogens.     

Evaluation of nongenotoxic and genotoxic factors modulating the frequency of micronucleated erythrocytes in the peripheral blood of mice

The hematological micronucleus test is regarded as an indicator of the clastogenic effect of chemicals and acute cytogenetic damage. The test can be carried out in red blood cells of the bone marrow and of the spleen, as well as in peripheral erythrocytes. We have determined the precise background values of micronucleated red blood cells for the peripheral blood of BALB/c, DBA/2, and NMRI mice. Bleeding, phenylhydrazine-induced hemolysis, and splenectomy generated an increase of micronucleated erythrocytes in the peripheral blood of mice. Our data thus demonstrate that such factors should be taken into consideration when the micronucleus test is used for screening the genotoxic potential of chemicals. Furthermore, the micronucleus-inducing effect of cyclophosphamide was studied in normal and splenectomized mice and, in addition, a comparison of the sensitivity of the micronucleus test was carried out in peripheral blood and bone marrow after cyclophosphamide treatment. Our data demonstrate that the kinetics of micronucleus formation were similar in normal and in splenectomized mice in which the micronucleus levels had returned to normal. The comparison of micronucleus formation in bone marrow and peripheral blood after cyclophosphamide treatment revealed the generation of similar quantities of micronucleated red blood cells in both tissues. The physiological mechanisms of micronucleus formation and removal and the potential role of chemically induced spleen damage during this process are discussed; the usefulness of the peripheral micronucleus test as a simple, rapid, and animal-saving modification of the standard bone marrow test is evaluated.Abbreviations CP cyclophosphamide - MN micronuclei - MNCE micronucleated normochromatic erythrocytes - MNPCE micronucleated polychromatic erythrocytes - MNRBC micronucleated red blood cells - NCE normochromatic erythrocytes - PCE polychromatic erythrocytes     

Evaluation of nongenotoxic and genotoxic factors modulating the frequency of micronucleated erythrocytes in the peripheral blood of mice

The hematological micronucleus test is regarded as an indicator of the clastogenic effect of chemicals and acute cytogenetic damage. The test can be carried out in red blood cells of the bone marrow and of the spleen, as well as in peripheral erythrocytes. We have determined the precise background values of micronucleated red blood cells for the peripheral blood of BALB/c DBA/2, and NMRI mice. Bleeding, phenylhydrazine-induced hemolysis, and splenectomy generated an increase of micronucleated erythrocytes in the peripheral blood of mice. Our data thus demonstrate that such factors should be taken into consideration when the micronucleus test is used for screening the genotoxic potential of chemicals. Furthermore, the micronucleus-inducing effect of cyclophosphamide was studied in normal and splenectomized mice and, in addition, a comparison of the sensitivity of the micronucleus test was carried out in peripheral blood and bone marrow after cyclophosphamide treatment. Our data demonstrate that the kinetics of micronucleus formation were similar in normal and in splenectomized mice in which the micronucleus levels had returned to normal. The comparison of micronucleus formation in bone marrow and peripheral blood after cyclophosphamide treatment revealed the generation of similar quantities of micronucleated red blood cells in both tissues. The physiological mechanisms of micronucleus formation and removal and the potential role of chemically induced spleen damage during this process are discussed; the usefulness of the peripheral micronucleus test as a simple, rapid, and animal-saving modification of the standard bone marrow test is evaluated.Abbreviations CP cyclophosphamide - MN micronuclei - MNCE micronucleated normochromatic erythrocytes - MNPCE micronucleated polychromatic erythrocytes - MNRBC micronucleated red blood cells - NCE normochromatic erythrocytes - PCE polychromatic erythrocytes