Peripheral Blood Micronucleus Test Research Articles

Micronuclei analysis in mice peripheral blood exposed to polarized polychromatic noncoherent light (Bioptron® Light)

The increase in cancer in recent years suggests an inadvertent exposure to agents that cause genetic damage. The polarized polychromatic noncoherent light Bioptron® lamp is used to accelerate healing, among other therapeutic applications and its potential carcinogenic effects as a mitogenic agent have not been explored. The objective was to evaluate the genotoxicity of the Bioptron light therapy by means of the micronucleus assay in mouse erythrocytes. Male SKH1 hairless mice were randomly divided into six groups (5 mice/group); Group 1: negative control received ambient light; Group 2: positive control was exposed to ultraviolet light lamp A (UV-A) for 80 min; Experimental Groups 3–6 were exposed to the Bioptron lamp light for 10, 20, 40 and 80 min, respectively. Exposures in all groups were once a day for 4 days and blood smears were performed daily for 5 days and subsequently read with a microscope equipped with epifluorescence. The values of micronucleated erythrocytes (MNE), micronucleated polychromatic erythrocytes (MNPCE) and the proportion of polychromatic erythrocytes (PCE) were determined. The study group that received the UV-A light was the only one that increased MNE and MNPCE values, while in the groups exposed to the Bioptron lamp and the negative control did not show increases in any of the sampling days. In conclusion, under the conditions presented here, our results suggest that the light of the Bioptron lamp does not cause damage to the genetic material of SKH1 mice, by means of the micronucleus test in peripheral blood.

Safety Assessment of Lactiplantibacillus plantarum TWK10 Based on Whole-Genome Sequencing, Phenotypic, and Oral Toxicity Analysis.

Lactiplantibacillus plantarum TWK10 (TWK10), isolated from Taiwanese pickled cabbage, has been demonstrated to exert beneficial probiotic effects in both mice and humans. Here, we comprehensively assessed the safety of TWK10 using both in vivo and in vitro approaches, including whole-genome sequence analysis, an assessment of hemolytic activity, and performing an antimicrobial susceptibility test, the Ames bacterial reverse mutation assay, the chromosomal aberration test, a rodent peripheral blood micronucleus test, and the 28-day subacute oral toxicity assay. The results showed that there was no significant increase in the incidence of reverse mutations or chromosomal aberrations following exposure to TWK10. Moreover, no significant changes were detected either in the number of reticulocytes or the incidence of micronuclei in ICR mice, and no subacute toxicity was recorded in SD rats at the oral TWK10 dosage of 2000 mg/kg body weight/day repeated for 28 days. Additionally, TWK10 exhibited no hemolytic activity and was susceptible to all the antibiotics tested, except kanamycin. However, no antimicrobial resistance genes, virulence factors, or genes involved in biogenic amine synthesis were found in the genome of TWK10. Our findings demonstrated that TWK10 has high potential of being safe for human consumption as a probiotic.

Toxicological and chemoprevention studies of Dalbergia ecastaphyllum (L.) Taub. stem, the botanical source of Brazilian red propolis.

Dalbergia ecastaphyllum (L.) Taub. is a semi-prostrate species associated with estuaries, mangroves and dunes. This plant species has great ecological and economic importance, especially concerning apiculture pasture and Brazilian red propolis production. In this study, non-clinical toxicological evaluations of the hydroalcoholic extract of D. ecastaphyllum stems (DEHE), the resin production source, were conducted. In addition, the action of DEHE on genomic instability and colon carcinogenesis was investigated. The extract's chemical profile was analysed by HPLC, and medicarpin, vestitol and neovestitol were found as major compounds. DEHE showed an IC50 equivalent to 373.2 µg/ml and LC50 equal 24.4mg/L, when evaluated using the XTT colorimetric test and the zebrafish acute toxicity assay, respectively. DEHE was neither genotoxic nor cytotoxic at the highest dose, 2000mg/kg, by peripheral blood micronucleus test. The treatments DEHE (6 and 24mg/kg) led to the reduction of micronuclei induced by doxorubicin (DXR) in mice. Furthermore, significantly higher serum levels of reduced glutathione were observed in animals treated with DEHE plus DXR, revealing an antioxidant effect. Treatments with DEHE (48mg/kg) led to a significant reduction in pre-neoplastic lesions induced by the 1,2-dimethylhydrazine (DMH) carcinogen in the rat colon. Immunohistochemical analysis revealed significantly lower levels of expression of COX-2 (86%) and PCNA (83%) in the colon of rats treated with DEHE plus DMH, concerning those treated with the carcinogen. These results indicate the involvement of anti-inflammatory and antiproliferative pathways in the protective effect of DEHE.

In vivo assessment of antioxidant, antigenotoxic, and antimutagenic effects of bark ethanolic extract from Spondias purpurea L

ABSTRACT Medicinal plants have always been used for therapeutic purposes; however, some plants may contain toxic and mutagenic substances. The aim of this study was to assess the cytotoxic, genotoxic, mutagenic, antioxidant, antigenotoxic, and antimutagenic effects of the bark ethanolic extract of Spondias purpurea L. using male and female Swiss albino mice. To determine the protective effects of the extract, benzo[a]pyrene (B[a]P) and cyclophosphamide (CP) were selected as cell damage inducers. The extract was examined at doses of 500, 1000, or 1500 mg/kg body weight (BW)via gavage alone or concomitant with B[a]P or CP. Oxidative stress was measured by quantification of blood catalase activity (CAT), reduced glutathione (GSH) levels in total blood, liver, and kidney, and concentrations of malondiadehyde (MDA) in liver and kidney. Genotoxicity and antigenotoxicity were evaluated by the comet assay using peripheral blood. Cytotoxicity, mutagenicity, and antimutagenicity were determined utilizing the micronucleus test in bone marrow and peripheral blood. The S. purpurea L extract increased CAT activity and GSH levels accompanied by a decrease in MDA levels after treatment with B[a]P and CP. No genotoxic, cytotoxic, or mutagenic effects were found in mice exposed only to the extract. These results indicate that the extract of S. purpurea exhibited protective effects against oxidative and DNA damage induced by B[a]P and CP.

Assessment of Pig-a, Micronucleus, and Comet Assay Endpoints in Tg.RasH2 Mice Carcinogenicity Study of Aristolochic Acid I.

A newly developed in vivo Pig-a gene mutation assay displays great potential for integration into genotoxicity tests. To obtain more evidence for application of the Pig-a assay, we integrated this assay, micronucleus test in peripheral blood (MN-pb test) and bone marrow (MN-bm test), as well as a Comet assay into a transgenic RasH2 mice carcinogenicity study. Fourteen male RasH2 mice and five wild-type (WT) mice were treated with a strong mutagen aristolochic acid I at a dose of 5 mg/kg/day for 4 consecutive weeks. Mice recovered in 5 weeks. Peripheral bloods were collected for Pig-a assay, MN-pb test, and Comet assay at several time points, while bone marrow and target organs were harvested for the MN-bm test and pathological diagnosis after mice were euthanized. Finally, 13 of the 14 RasH2 mice developed squamous cell carcinomas in the forestomach, while there were no carcinomas in the WT mice. Pig-a mutant frequencies (MFs) consecutively increased throughout the study to a maximum value of approximately 63-fold more than background. These frequencies were relative to the incidence, size, and malignant degree of tumors. Micronucleated reticulocytes increased from Day 1 to Day 49, before returning to background levels. No positive responses were observed in either the MN-bm test or the Comet assay. Results suggested that, when compared with the other two tests, the Pig-a assay persistently contributed to sustaining MFs, enhanced detection sensitivity due to the accumulation of Pig-a mutations, and demonstrated better predictability for tumorigenicity. Environ. Mol. Mutagen. 61:266-275, 2020. © 2019 Wiley Periodicals, Inc.

Protective effects of bark ethanolic extract from Spondias dulcis Forst F. against DNA damage induced by benzo[a]pyrene and cyclophosphamide.

This study evaluated the genotoxicity, mutagenicity, antigenotoxicity, and antimutagenicity effects on biochemical parameters of oxidative stress of the Spondias dulcis bark ethanolic extract on mice. The extract was evaluated in the doses of 500, 1000, and 1500 mg/kg bw via gavage. To evaluate the protective effects of the extract, benzo[a]pyrene (B[a]P) and cyclophosphamide (CP) were chosen as DNA damage inducers. Genotoxicity and antigenotoxicity were evaluated by the comet assay. Cytotoxicity, mutagenicity, and antimutagenicity were evaluated by the micronucleus test in bone marrow and peripheral blood. The biochemical parameters of oxidative stress were evaluated by the quantification of catalase activity (CAT) and reduced glutathione (GSH) in total blood, liver and kidney, and malondialdehyde (MDA), in liver and kidney. No genotoxic, cytotoxic, or mutagenic effect was found on mice exposed to the extract. The extract depleted the number of damaged nucleoids in total blood and the number of micronucleus (MN) in both cell types. The extract was able to increase CAT activity and GSH levels and decrease MDA levels after treatment with B[a]P and CP. The results indicate that the S. dulcis extract has potential to be used as preventive compound against DNA damage caused by CP and B[a]P.

Inhibitory effect of Salvadora persica (Miswak) against cigarette smoke-induced mutagenicity and sperm abnormalities in rats

Pharmacognosy Research,2019,11,4,384-388.DOI:10.4103/pr.pr_65_19Published:November,2019Type:Original ArticleAuthors:Syed Imam Rabbani, Sultan Sajid, Vasudevan Mani, Omar Khan, and M. A. A. Salman Author(s) affiliations:Syed Imam Rabbani1, Sultan Sajid1, Vasudevan Mani1, Omar Khan2, M A. A. Salman1 1Department of Pharmacology, College of Pharmacy, Qassim University, Buraidah, Kingdom of Saudi Arabia. 2Department of Pharmaceutics, College of Pharmacy, Qassim University, Buraidah, Kingdom of Saudi Arabia. Abstract:Objective: The objective of the study is to evaluate the inhibitory effect of Salvadora persica against the cigarette smoke‑induced mutagenicity and sperm damages in rats. Materials and Methods: Young male Wistar rats of weight 120–140 g were exposed to the cigarette smoke for 8 weeks. The lyophilized decoction of S. persica was administered daily for 4 weeks by oral route at the doses 50, 100, and 200 mg/kg. The somatic and germinal cells damages were determined by peripheral blood micronucleus and sperm abnormalities tests, respectively. In vitro antioxidant activity of the decoction was determined by hydrogen peroxide scavenging assay. Ginseng was used as a standard herbal agent. The results were analyzed statistically by one‑way ANOVA followed by Tukey test. P <0.05 was considered to indicate the significance of results. Results: The data from the present study indicated that cigarette smoke exposure significantly (P < 0.01) increased the population of micronucleated erythrocytes and sperm shape abnormalities and, reduced the polychromatic: normochromatic (P/N) ratio, and total sperm count compared to control. The administration of S. persica produced a dose‑dependent inhibition on somatic and male germinal cell damages induced by cigarette smoke and the significant (P < 0.05) activity was observed at 200 mg/kg. However, none of the tested doses enhanced significantly the P/N ratio. Ginseng at 100 mg/kg significantly (P < 0.01) prevented the cigarette smoke‑mediated damages. The in‑vitro antioxidant activity indicated both S. persica and ginseng possess scavenging activity against the hydrogen peroxide free radicals. Conclusion: The observation suggests that the decoction of S. persica can prevent the somatic and germinal cell nuclear damages induced by cigarette smoke exposure. These actions could be related to its antioxidant property. Keywords:Antioxidant, Cigarette smoke, Micronuclei, Salvadora persica, Sperm abnormalities.View:PDF (854.28 KB)

In vivo antimutagenic and antiatherogenic effects of the (1 → 3)(1 → 6)-β-d- glucan botryosphaeran

The antimutagenic effect of botryosphaeran, an exocellular (1 → 3)(1 → 6)-β-d-glucan, from the ascomyceteous and plant-borne endophytic fungus, Botryosphaeria rhodina MAMB-05, was evaluated in young (6–8 weeks) and elderly (18 months) Swiss albino mice of both genders. The hypolipidemic, hypoglycemic and antiatherogenic potential was also evaluated in 18-month old male LDL receptor knockout (LDLr−/−) mice. Administration of botryosphaeran by gavage (doses: 7.5, 15, 30 mg/kg b.w./day) in a 30-day pretreatment protocol (young mice), or 15-day protocol (older mice), did not cause genotoxicity as assessed by the micronucleus test in peripheral blood (PB) and bone marrow cells (BMCs). Furthermore, there was no cytotoxic effect of this β-d-glucan in the treatments. A lower frequency of micronuclei was observed in BMCs from young and old mice that received botryosphaeran, indicating its antimutagenic effect. Botryosphaeran (30 mg/kg b.w./day) promoted 102.22% (young) and 103.45% (elderly) reductions in cyclophosphamide-induced damage in male mice. Botryosphaeran also exerted chemoprotective effects in LDLr−/− and wild-type (C57BL/6) mice. Botryosphaeran treatment for 15 days at a dose of 30 mg/kg b.w./day improved the lipidic profile (reductions of 53.8–84.3%), and decreased aortic lipid deposition (32.8%) in the LDLr−/− atherosclerotic mice. The results indicate botryosphaeran has relevant biologic effects, making it a promising candidate for the development of new therapeutic agents.

Copaifera multijuga oleoresin and its constituent diterpene (−)-copalic acid: Genotoxicity and chemoprevention study

Copaiba oleoresins are used in alternative medicine as anti-inflammatory, antitumoral, and antimicrobial treatments. (−)-Copalic acid (CA) is the major diterpene found in exudates from Copaifera species. We have examined the genotoxicity and the chemopreventive potential of Copaifera multijuga oleoresin (CM) and CA. Genotoxicity assessment was examined with the peripheral blood micronucleus test and the comet assay (male Swiss mouse hepatocytes). In the chemoprevention study, we evaluated the effects of CM and CA on the formation of 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) in male Wistar rat colon. Neither agent caused a significant increase in micronucleus frequency relative to controls, but the highest CM dose tested (400mg/kg b.w.) caused DNA damage in the comet assay. Both agents significantly reduced the frequency of DMH-induced ACF. Both CM and CA suppressed ACF formation and may have a protective effect against colon carcinogenesis.

Genotoxic and cytotoxic evaluation of Jatropha dioica Sessé ex Cerv. by the micronucleus test in mouse peripheral blood

Jatropha dioica Sessé ex Cerv. is a medicinal plant credited with low cytotoxicity in vitro. Thus, the objective of this work was to evaluate the possible genotoxic and cytotoxic effect in vivo of the J. dioica aqueous extract by means of micronucleus assay in mouse peripheral blood. Four different J. dioica aqueous extract dose-units were evaluated (30, 60, 100, and 300 mg/kg). The extract was administered orally to male Balb-C-strain mice every 24 h during 5 days. Blood samples were taken at 0, 24, 48, 72, 96, and 120 h from the mouse's tail and were performed in duplicate extensions. The number of Polychromatic Erythrocytes (PCE), Polychromatic Micronucleus Erythrocytes (PCEMN), and Micronucleus Erythrocytes (MNE) was determined at the different sampling times in the different study groups. Our results showed that the group that received 60 mg/kg of cyclophosphamide (positive control) presented a significant decrease in the PCE (p = 0.044) proportion and a significant increase in MNE (p = 0.032, p = 0.0001). The groups that received the different J. dioica aqueous extract doses did not present either a PCE decrease or an increase in PCEMN and MNE. J. dioica exerts neither a genotoxic nor a cytotoxic effect on mouse peripheral blood at high doses.

Vitamin D3 deficiency increases DNA damage and the oxidative burst of neutrophils in a hypertensive rat model

Deficiency of vitamin D3, a lipophilic micronutrient, plays a role in the development of some chronic diseases. Vitamin D3 deficiency affects 25–50% of the human population and has been associated with increased risk for development of hypertension. DNA damage induced by reactive oxygen species (ROS) occurs more often in hypertensive than in normotensive individuals, and vitamin D3 status can influence this relationship. The aim of this study was to evaluate whether a diet supplemented with (10,000IU/kg) or deficient in (0IU/kg) vitamin D3, compared to a vitamin D3 control diet (1000IU/kg), would modulate DNA damage and ROS production in spontaneously hypertensive rats (SHR) and normotensive control Wistar-Kyoto (WKY) rats after 12 weeks of treatment. ROS production was assessed by measuring the oxidative burst of neutrophils. DNA damage was evaluated using the comet assay in peripheral blood and the micronucleus test in bone marrow and peripheral blood. Vitamin D3 supplementation did not induce DNA damage and did not change neutrophil ROS production in SHR and WKY rats. Vitamin D3 deficiency induced neutrophil ROS production and a high frequency of micronucleus formation in the bone marrow and peripheral blood of SHR rats only, and induced DNA damage (comet) in peripheral blood of both SHR and WKY rats. In conclusion, vitamin D3 deficiency showed a more pronounced effect on hypertensive animals. Population studies are needed to test whether this relationship also exists in humans.

Safety studies conducted on pecan shell fiber, a food ingredient produced from ground pecan shells.

Use of pecan shell fiber in human food is presently limited, but could increase pending demonstration of safety. In a 91-day rat study, pecan shell fiber was administered at dietary concentrations of 0 (control), 50 000, 100 000 or 150 000 ppm. There was no effect of the ingredient on body weight of males or females or food consumption of females. Statistically significant increases in food consumption were observed throughout the study in 100 000 and 150 000 ppm males, resulting in intermittent decreases in food efficiency (150 000 ppm males only) that were not biologically relevant. All animals survived and no adverse clinical signs or functional changes were attributable to the test material. There were no toxicologically relevant changes in hematology, clinical chemistry or urinalysis parameters or organ weights in rats ingesting pecan shell fiber. Any macroscopic or microscopic findings were incidental, of normal variation and/or of minimal magnitude for test substance association. Pecan shell fiber was non-mutagenic in a bacterial reverse mutation test and non-clastogenic in a mouse peripheral blood micronucleus test. Based on these results, pecan shell fiber has an oral subchronic (13-week) no observable adverse effect level (NOAEL) of 150 000 ppm in rats and is not genotoxic at the doses analyzed.

Diaryl sulfide analogs of combretastatin A-4: Toxicogenetic, immunomodulatory and apoptotic evaluations and prospects for use as a new chemotherapeutic drug.

Combretastatin A-4 exhibits efficient anti-cancer potential in human tumors, including multidrug-resistant tumors. We evaluated the mutagenic, apoptotic and immunomodulatory potential of two diaryl sulfide analogs of combretastatin A-4, 1,2,3-trimethoxy-5-([4-methoxy-3-nitrophenyl]thio)benzene (analog 1) and 1,2,3-trimethoxy-5-([3-amino-4-methoxyphenyl]thio)benzene (analog 2), as well as their association with the anti-tumor agent cyclophosphamide, in Swiss mice. Such evaluation was achieved using the comet assay, peripheral blood micronucleus test, splenic phagocytosis assay, and apoptosis assay. Both analogs were found to be genotoxic, mutagenic and to induce apoptosis. They also increased splenic phagocytosis, although this increase was more pronounced for analog 2. When combined with cyclophosphamide, analog 1 enhanced the mutagenic and apoptotic effects of this anti-tumor agent. In contrast, analog 2 did not enhance the effects of cyclophosphamide and prevented apoptosis at lower doses. These data suggest that analog 1 could be an adjuvant chemotherapeutic agent and possibly improve the anti-neoplastic effect of cyclophosphamide. Additionally, this compound could be a candidate chemotherapeutic agent and/or an adjuvant for use in combined anti-cancer therapy.

Curcumin prevents perfluorooctane sulfonate-induced genotoxicity and oxidative DNA damage in rat peripheral blood

Perfluorooctane sulfonate (PFOS) is a man-made fluorosurfactant and global pollutant. PFOS a persistent and bioaccumulative compound, and it is widely distributed in humans and wildlife. Therefore, it was added to Annex B of the Stockholm Convention on Persistent Organic Pollutants in May 2009. Curcumin is a natural polyphenolic compound abundant in the rhizome of the perennial herb turmeric. It is commonly used as a dietary spice and coloring agent in cooking and anecdotally as an herb in traditional Asian medicine. In this study, male rats were treated with three different PFOS doses (0.6, 1.25, and 2.5 mg/kg) and one dose of curcumin, from Curcuma longa (80 mg/kg), and combined three doses of PFOS with 80 mg/kg dose of curcumin by gavage for 30 d at 48 h intervals. Here, we investigated the DNA damage via single-cell gel electrophoresis/comet assay and micronucleus test in rat peripheral blood in vivo. It is found that all doses of PFOS increased micronucleus frequency (p < 0.05) and strongly induced DNA damage in peripheral blood in two different parameters; the damaged cell percent and genetically damage index, and curcumin prevented the formation of DNA damage induced by PFOS. Results showed that curcumin inhibited DNA damage including GDI at certain levels at statistical manner, 30.07%, 54.41%, and 36.99% for 0.6 mg/kg, 1.25 mg/kg, and 2.5 mg/kg.

In vivo assessment of genotoxic, antigenotoxic and anticarcinogenic activities of Solanum lycocarpum fruits glycoalkaloidic extract.

The fruits of Solanum lycocarpum, known as wolf-fruit, are used in folk medicine, and because of that we have evaluated both the genotoxic potential of its glycoalkaloidic extract (SL) and its influence on the genotoxicity induced by methyl methanesulfonate. Furthermore, the potential blocking effect of SL intake in the initial stage of colon carcinogenesis in Wistar rats was investigated in a short-term (4-week) bioassay using aberrant crypt foci (ACF) as biomarker. The genotoxic potential was evaluated using the Swiss mice peripheral blood micronucleus test. The animals were treated with different doses of SL (15, 30 and 60 mg/kg b.w.) for 14 days, and the peripheral blood samples were collected at 48 h, 7 days and 14 days after starting the treatment. For antigenotoxicity assessment, MMS was administered on the 14th day, and after 24 h the harvesting of bone marrow and liver cells was performed, for the micronucleus and comet assays, respectively. In the ACF assay, male Wistar rats were given four subcutaneous injections of the carcinogen 1,2-dimethylhydrazine (DMH, 40 mg/kg b.w.), twice a week, during two weeks to induce ACF. The treatment with SL (15, 30 and 60 mg/kg b.w.) was given for four weeks during and after carcinogen treatment to investigate the potential beneficial effects of SL on DMH-induced ACF. The results demonstrated that SL was not genotoxic in the mouse micronucleus test. In animals treated with SL and MMS, the frequencies of micronucleus and extensions of DNA damage were significantly reduced in comparison with the animals receiving only MMS. Regarding the ACF assay, SL significantly reduced the frequency of ACF induced by DMH.

Cytogenetic biomonitoring in mucopolyssacharosis I, II and IV patients treated with enzyme replacement therapy

Background and objectives: The aim of this study was to evaluate genotoxicity and mutagenicity in peripheral blood and buccal mucosal cells in mucopolysaccharidosis (MPS) I, II or VI patients.Methods: A total of 12 patients with MPS type I, II and VI attended at the Institute of Genetics and Inborn Errors of Metabolism treated with enzyme replacement therapy (ERT) and 10 healthy control volunteers were included in this study. Mechanically exfoliated cells from cheek mucosa (left and right side) were used to micronucleus test and single cell gel (comet) assay in peripheral blood cells.Results: The results of this study detected the presence of genetic damage in peripheral blood for all individuals with MPS treated with ERT, regardless of type of MPS as depicted by tail moment results. In addition, an increased number of micronucleated cells were found in buccal cells of MPS type II patients. It was also observed an increase of other nuclear alterations closely related to cytotoxicity as depicted by the frequency of pyknosis, karyolysis and karyorrhexis in buccal mucosa cells of MPS VI patients (p < 0.05).Conclusion: Taken together, such results demonstrate that metabolic alterations induced by the enzymatic deficiency characteristic of MPS associated with ERT therapy can induce genotoxicity and mutagenicity in peripheral blood and buccal mucosa cells, respectively. This effect appears to be more pronounced to MPS II.

In vivo genotoxicity of a novel heterocyclic amine, aminobenzoazepinoquinolinone-derivative (ABAQ), produced by the Maillard reaction between glucose and l-tryptophan

We recently demonstrated that a novel heterocyclic amine, 5-amino-6-hydroxy-8H-benzo[6,7]azepino[5,4,3-de]quinolin-7-one (ABAQ), is produced from glucose and l-tryptophan by the Maillard reaction at physiological temperature and pH, and that ABAQ was strongly mutagenic for Salmonella strains in the presence of S9 mix. Here, we present the results of three in vivo genotoxicity assays of ABAQ. The comet assay revealed that DNA damage was significantly increased in the livers, kidneys, lungs, and bone marrows of ICR mice, 3h after i.p. injection of ABAQ (50mg/kg body weight (bw)). To evaluate clastogenicity, the peripheral blood micronucleus test was performed, also in ICR mice. ABAQ induced micronucleated reticulocytes (MNRETs) in a dose-dependent manner; the frequency of MNRETs was significantly elevated at all i.p. doses (12.5, 25, and 50mg/kg bw) after 48h. To investigate the mutagenicity of ABAQ in vivo, gpt delta transgenic mice were treated with five consecutive administrations of ABAQ by gavage at doses of 25 or 50mg/kg per week for 3 weeks. The frequencies of gpt mutations (MF) in the liver of mice increased significantly compared with controls, in a dose-dependent manner. No significant increase of gpt MF was detected in the kidneys. Base substitutions predominated; both G:C→A:T and A:T→C:G mutations were significantly increased by ABAQ. The Spi− MF was also significantly increased in the liver after ABAQ treatment. If formed in vivo, ABAQ may give rise to adverse genotoxic effects.

Erythromycin‐induced genotoxicity and hepatotoxicity in mice pups treated during prenatal and postnatal period

The main aim of this study was to investigate the oxidative stress, genotoxicity and cytotoxicity of erythromycin (EMC) in pups of treated dams in gestation as well as the lactation period (LP). The two doses of EMC were compared using intraperitoneal (i.p.) route in two different periods, that is, in gestation period and in the LP. The rationale behind selection of i.p. route is because of the fact that EMC gets degrades in acidic pH of the stomach. The doses of EMC used were clinically equivalent dose (CED; EMC 14.2 mg/kg, i.p.) and a lower dose (EMC 10 mg/kg, i.p.) than CED. EMC toxicities in mice pups were evaluated using various parameters such as micronucleus (MN) test in peripheral blood and bone marrow, malondialdehyde (MDA) assay, glutathione (GSH reduced) assay and histopathological assessment in liver tissue. The CED of EMC led to a significant increase in MDA and decreased in GSH concentration in pups' liver tissue in both gestation and LPs and also to a significant increase in MN frequency in both peripheral blood and bone marrow cells of pups. There were no significant toxicities at a lower dose than CED. There were also some chronic findings with liver histopathological examination at CED. It is thus concluded that EMC accentuates the oxidative stress, cytotoxicity and DNA damage in pups of their postnatal life; hence, EMC should be avoided in the pregnancy and also in the LP.

Genotoxicity of doxorubicin in F344 rats by combining the comet assay, flow‐cytometric peripheral blood micronucleus test, and pathway‐focused gene expression profiling

Doxorubicin (DOX) is an antineoplastic drug effective against many human malignancies. DOX's clinical efficacy is greatly limited because of severe cardiotoxicity. To evaluate if DOX is genotoxic in the heart, ~7-week-old, male F344 rats were administered intravenously 1, 2, and 3 mg/kg bw DOX at 0, 24, 48, and 69 hr and the Comet assays in heart, liver, kidney, and testis and micronucleus (MN) assay in the peripheral blood (PB) erythrocytes using flow cytometry were conducted. Rats were euthanized at 72 hr and PB was removed for the MN assay and single cells were isolated from multiple tissues for the Comet assays. None of the doses of DOX induced a significant DNA damage in any of the tissues examined by the alkaline Comet assay. Contrastingly, the glycosylase enzymes-modified Comet assay showed a significant dose dependent increase in the oxidative DNA damage in the cardiac tissue (P ≤ 0.05). In the liver, only the top dose induced significant increase in the oxidative DNA damage (P ≤ 0.05). The histopathology showed no severe cardiotoxicity but non-neoplastic lesions were present in both untreated and treated samples. A severe toxicity likely occurred in the bone marrow because no viable reticulocytes could be screened for the MN assay. Gene expression profiling of the heart tissues showed a significant alteration in the expression of 11 DNA damage and repair genes. These results suggest that DOX is genotoxic in the heart and the DNA damage may be induced primarily via the production of reactive oxygen species.

Assessment of the Genotoxic Potential of Azidothymidine in the Comet, Micronucleus, and Pig-a Assay

The genotoxic potential of azidothymidine (Zidovudine, AZT), chosen as a model compound for nucleotide analogs, was comprehensively assessed in vivo for gene mutation, clastogenicity, and DNA breakage endpoints. Male Wistar rats were treated by oral gavage over 7 days with AZT at dose levels of 2×0 (control), 2×250, 2×500, and 2×1000mg/kg/day with a final single dose given on day 8. DNA damage was then evaluated with the comet assay in liver, stomach, and peripheral blood and with the micronucleus test in bone marrow and peripheral blood (by flow cytometry) in the same animals. After a treatment-free period of upto 42 days, the Pig-a gene mutation assay was performed in peripheral blood of the high-dose animals. In the comet assay as well as the micronucleus test, AZT caused a considerable dose-dependent increase in DNA damage in all tissues evaluated and was highly cytotoxic to bone marrow and peripheral blood cells. These data are well in line with published results. Surprisingly, AZT did not significantly increase the number of Pig-a mutant cells. We speculate that two factors likely contributed to this negative result: a predominance of large deletions caused by AZT, and the relatively low statistical power of the first-generation scoring method used for this study.