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Judice SA, Sussman HE, Walker DM, O’Neill JP, Albertini RJ, Walker VE. Clonality, trafficking, and molecular alterations among Hprt mutant T lymphocytes isolated from control mice versus mice treated with N-ethyl-N-nitrosourea. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2023; 64:432-457. [PMID: 37957787 PMCID: PMC10842105 DOI: 10.1002/em.22579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 11/03/2023] [Accepted: 11/10/2023] [Indexed: 11/15/2023]
Abstract
Mutations in T lymphocytes (T-cells) are informative quantitative markers for environmental mutagen exposures, but risk extrapolations from rodent models to humans also require an understanding of how T-cell development and proliferation kinetics impact mutagenic outcomes. Rodent studies have shown that patterns in chemical-induced mutations in the hypoxanthine-guanine phosphoribosyltransferase (Hprt) gene of T-cells differ between lymphoid organs. The current work was performed to obtain knowledge of the relationships between maturation events during T-cell development and changes in chemical-induced mutant frequencies over time in differing immune compartments of a mouse model. A novel reverse transcriptase-polymerase chain reaction based method was developed to determine the specific T-cell receptor beta (Tcrb) gene mRNA expressed in mouse T-cell isolates, enabling sequence analysis of the PCR product that then identifies the specific hypervariable CDR3 junctional region of the expressed Tcrb gene for individual isolates. Characterization of spontaneous Hprt mutant isolates from the thymus, spleen, and lymph nodes of control mice for their Tcrb gene expression found evidence of in vivo clonal amplifications of Hprt mutants and their trafficking between tissues in the same animal. Concurrent analyses of Hprt mutations and Tcrb gene rearrangements in different lymphoid tissues of control versus N-ethyl-N-nitrosourea-exposed mice permitted elucidation of the localization and timing of mutational events in T-cells, establishing that mutagenesis occurs primarily in the pre-rearrangement replicative period in pre-thymic/thymic populations. These findings demonstrate that chemical-induced mutagenic burden is determined by the combination of mutagenesis and T-cell clonal expansion, processes with roles in immune function and in the pathogenesis of autoimmune disease and cancer.
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Affiliation(s)
- Stephen A. Judice
- Genetic Toxicology Laboratory, University of Vermont, Burlington, Vermont
- EnviroLogix, Portland, Maine
| | - Hillary E. Sussman
- School of Public Health, University at Albany − SUNY, Albany, NY
- Wadsworth Center, New York State Department of Health, Albany, NY
- Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY
| | - Dale M. Walker
- Experimental Pathology Laboratories, Sterling, VA
- The Burlington HC Research group, Inc., Jericho, Vermont
| | - J. Patrick O’Neill
- Genetic Toxicology Laboratory, University of Vermont, Burlington, Vermont
| | - Richard J. Albertini
- Genetic Toxicology Laboratory, University of Vermont, Burlington, Vermont
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Vernon E. Walker
- Wadsworth Center, New York State Department of Health, Albany, NY
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
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Revollo JR, Pearce MG, Dad A, Petibone DM, Robison TW, Roberts D, Dobrovolsky VN. Analysis of mutation in the rat Pig-a assay: I) studies with bone marrow erythroid cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2018; 59:722-732. [PMID: 30091272 DOI: 10.1002/em.22211] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/08/2018] [Accepted: 05/10/2018] [Indexed: 06/08/2023]
Abstract
We have established a flow cytometry-based Pig-a assay for rat bone marrow erythroid cells (BMEs). The BME Pig-a assay uses a DNA-specific stain and two antibodies: one against the transmembrane transferrin receptor (CD71 marker) and the other against the GPI-anchored complement inhibitory protein (CD59 marker). In F344 male rats treated acutely with a total of 120 mg/kg of N-ethyl-N-nitrosourea (ENU) the frequency of CD59-deficient phenotypically mutant BMEs increased approximately 24-fold compared to the rats concurrently treated with the vehicle. Such an increase of mutant BMEs coincides with increases of CD59-deficient reticulocytes measured in rats treated with similar doses of ENU. Sequence analysis of the endogenous X-linked Pig-a gene of CD59-deficient BMEs revealed that they are Pig-a mutants. The spectrum of ENU-induced Pig-a mutations in these BMEs was consistent with the in vivo mutagenic signature of ENU: 73% of mutations occurred at A:T basepairs, with the mutated T on the nontranscribed strand of the gene. T→A transversion was the most frequent mutation followed by T→C transition; no deletion or insertion mutations were present in the spectrum. Since BMEs are precursors of peripheral red blood cells, our findings suggest that CD59-deficient erythrocytes measured in the flow cytometric erythrocyte Pig-a assay develop from BMEs containing mutations in the Pig-a gene. Thus, the erythrocyte Pig-a assay detects mutation in the Pig-a gene. Environ. Mol. Mutagen. 59:722-732, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Javier R Revollo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas
| | - Mason G Pearce
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas
| | - Azra Dad
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas
| | - Dayton M Petibone
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas
| | - Timothy W Robison
- Division of Pulmonary, Allergy, and Rheumatology Products, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland
| | - Daniel Roberts
- Charles River Laboratories, Skokie, Illinois; Joint Graduate Program of Toxicology, Rutgers University, Piscataway, New Jersey
| | - Vasily N Dobrovolsky
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, Arkansas
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Bajpayee M, Pandey AK, Parmar D, Dhawan A. Current Status of Short-Term Tests for Evaluation of Genotoxicity, Mutagenicity, and Carcinogenicity of Environmental Chemicals and NCEs. Toxicol Mech Methods 2012; 15:155-80. [PMID: 20021080 DOI: 10.1080/15376520590945667] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The advent of the industrial revolution has seen a significant increase in the number of new chemical entities (NCEs) released in the environment. It becomes imperative to check the toxic potential of NCEs to nontarget species before they are released for commercial purposes because some of these may exert genotoxicity, mutagenicity, or carcinogenicity. Exposure to such compounds produces chemical changes in DNA, which are generally repaired by the DNA repair enzymes. However, DNA damage and its fixation may occur in the form of gene mutations, chromosomal damage, and numerical chromosomal changes and recombination. This may affect the incidence of heritable mutations in man and may be transferred to the progeny or lead to the development of cancer. Hence, adequate tests on NCEs have to be undertaken for the risk assessment and hazard prediction. Compounds that are positive in tests that detect such damages have the potential to be human mutagens/carcinogens. Only long-term animal bioassays, involving lifetime studies on animals, were used earlier to classify substances as mutagens/carcinogens. These tests were cumbersome and time consuming and required a lot of facilities and personnel. Short-term tests, therefore, were brought into practice. A "battery" of three to four of these short-term tests has been proposed now by a number of regulatory authorities for the classification of compounds as mutagenic or carcinogenic. This review deals with the current status of these short-term tests.
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Affiliation(s)
- Mahima Bajpayee
- Developmental Toxicology Division, Industrial Toxicology Research Center, M.G. Marg, LucknowIndia
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Kimoto T, Chikura S, Suzuki-Okada K, Kobayashi XM, Itano Y, Miura D, Kasahara Y. Effective use of the Pig-a gene mutation assay for mutagenicity screening: measuring CD59-deficient red blood cells in rats treated with genotoxic chemicals. J Toxicol Sci 2012; 37:943-55. [DOI: 10.2131/jts.37.943] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Bhalli JA, Shaddock JG, Pearce MG, Dobrovolsky VN, Cao X, Heflich RH, Vohr HW. Report on stage III Pig-a mutation assays using benzo[a]pyrene. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2011; 52:731-737. [PMID: 22052432 DOI: 10.1002/em.20675] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 07/15/2011] [Accepted: 07/15/2011] [Indexed: 05/31/2023]
Abstract
Genotoxicity assays were conducted on rats treated with benzo[a]pyrene (BaP) as part of Stage III of a validation study on the Pig-a gene mutation assay. Assays were performed at the U.S. FDA-NCTR and Bayer-Germany. Starting on Day 1, groups of five 6- to 7-week-old male Fischer 344 (F344, used at FDA-NCTR) and Han Wistar rats (Bayer) were given 28 daily doses of 0, 37.5, 75, or 150 mg/kg BaP; blood was sampled on Days -1, 4, 15, 29, and 56. Pig-a mutant frequencies were determined on Days -1, 15, 29, and 56 in total red blood cells (RBCs) and reticulocytes (RETs) as RBC(CD59-) and RET(CD59-) frequencies; percent micronucleated-RETs (%MN-RET) were measured on Days 4 and 29. RBC(CD59-) and RET(CD59-) frequencies increased in a dose- and time-dependent manner, producing significant increases by Day 29 in both rat models. The responses for RETs were stronger than those for RBCs, and the responses in F344 rats were stronger than in Han Wistar rats. BaP also produced significant increases in %MN-RET frequency at Days 4 and 29, with the responses being greater in F344 than Han Wistar rats. The overall findings were consistent with those of the reference laboratory using Han Wistar rats. Finally, mutation assays performed on splenocytes from Day 56 F344 rats indicated that BaP mutant frequencies were three to fivefold higher for the Hprt gene than the Pig-a gene. The results indicate that the Pig-a RET and RBC assays are reproducible, transferable, and show promise for integrating gene mutation into 28-day repeat-dose studies.
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Affiliation(s)
- Javed A Bhalli
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas 72079, USA
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van Zeeland AA, de Groot AJL, Mohn GR, van Steeg H, van Oostrom C, van Duijn-Goedhart AM, Mullenders LFH, Jansen JG. Reduced methylation-induced mutagenesis in rat splenocytes in vivo by sub-chronic low dose exposure to N-metyl-N-nitrosourea. Mutat Res 2007; 640:131-8. [PMID: 18249417 DOI: 10.1016/j.mrfmmm.2007.12.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Revised: 12/18/2007] [Accepted: 12/19/2007] [Indexed: 10/22/2022]
Abstract
Estimates of genotoxic effects of mutagens at low and protracted doses are often based on linear extrapolation of data obtained at relatively high doses. To test the validity of such an approach, a comparison was made between the mutagenicity of N-methyl-N-nitrosourea (MNU) in T-lymphocytes of the rat following two treatment protocols, i.e. sub-chronic exposure to a low dose (15-45 repeated exposures to 1mg/kg of MNU) or acute exposure to a single high dose (15, 30 or 45 mg/kg of MNU). Mutation induction appeared dramatically lower following sub-chronic treatment compared to treatment with a single high exposure. Furthermore, DNA sequence analysis of the coding region of the hprt gene in MNU-induced mutants showed that acute high dose treatment causes mainly GC-->AT base pair changes, whereas sub-chronic treatment results in a significant contribution of AT base pair changes to mutation induction. We hypothesize that O(6)-methylguanine-DNA methyltransferase is saturated after acute treatments, while after sub-chronic treatment most O(6)-methylguanine is efficiently repaired. These data suggest (i) that risk estimations at low and protracted doses of MNU on the basis of linear extrapolation of effects measured at high dose are too high and (ii) that the protective effects of DNA repair processes are relatively strong at low sub-chronic exposure.
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Affiliation(s)
- Albert A van Zeeland
- Department of Toxicogenetics, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
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Walker DM, Seilkop SK, Scott BR, Walker VE. Hprt mutant frequencies in splenic T-cells of male F344 rats exposed by inhalation to propylene. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2004; 43:265-272. [PMID: 15141366 DOI: 10.1002/em.20020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Propylene is a major industrial intermediate and atmospheric pollutant to which humans are exposed by inhalation. In this study, 6-week-old male F344 rates were exposed to 0, 200, 2000, or 10,000 ppm propylene by inhalation for 4 weeks (6 h/day, 5 days/week), and mutant frequencies were determined in the Hprt gene of splenic T-lymphocytes. Twenty milligrams of cyclophosphamide monohydrate (CPP)/kg bw, given on the penultimate day of propylene exposure, was used as a positive control mutagen. Rats (n = 8/group) were necropsied for isolation of T-cells 8 weeks after the last dose, a sampling time that produced peak spleen Hprt mutant frequencies (Mfs) in a preliminary mutant manifestation study using CCP treatment. Hprt Mfs were measured via the T-cell cloning assay, which was performed without knowledge of the animal treatment groups. Mean Hprt Mfs were significantly increased over control values (mean Mf = 5.24 +/- 1.55 (SD) x 10(-6)) in CPP-treated rats (10.37 +/- 4.30 x 10(-6), P = 0.007). However, Hprt Mfs in propylene-exposed rats were not significantly increased over background, with mean Mfs of 4.90 +/- 1.84 x 10(-6) (P = 0.152), 5.05 +/- 3.70 x 10(-6) (P = 0.895), and 5.95 +/- 2.49 x10(-6) (P = 0.500) for animals exposed to 200, 2000, or 10,000 ppm propylene, respectively. No significant increase in F344 rat or B6C3F1 mouse cancer incidence was reported in the National Toxicology Program carcinogenicity studies of propylene across this same exposure range. Taken together, these findings support the conclusion that inhalation exposure of rats to propylene does not cause mutations or cancer.
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Affiliation(s)
- Dale M Walker
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
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Liu SX, Cao J, An H, Shun HM, Yang LJ, Liu Y. Analysis of spontaneous, gamma ray- and ethylnitrosourea-induced hprt mutants in HL-60 cells with multiplex PCR. World J Gastroenterol 2003; 9:578-83. [PMID: 12632522 PMCID: PMC4621586 DOI: 10.3748/wjg.v9.i3.578] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To explore the molecular spectra and mechanism of human hypoxanthine guanine phosphoribosyl transferase (hprt) gene mutation induced by ethyluitrosourea (ENU) and 60Co γ-rays.
METHODS: Independent human promyelocytic leukemia cells (HL-60) mutants at the hprt locus were isolated from untreated, ethyluitrosourea (ENU) and 60Co γ-ray-exposed cells, respectively, and verified by two-way screening. The genetic changes underlying the mutation were determined by multiplex polymerase chain reaction (PCR) amplification and electrophoresis technique.
RESULTS: With dosage increased, survival rate of plated cell reduced (in the group with dosage of ENU with 100-200 μg/mL, P < 0.01; in the group with dosage of 60Co γ-ray with 2-4 Gy, P < 0.05) and mutational frequency increased (in the group of ENU 12.5-200.0 μg/mL, P < 0.05; in the group of 60Co γ-ray with 1-4 Gy, P < 0.05) significantly. In the 13 spontaneous mutants analyzed, 92.3% of mutant clones did not show any change in number or size of exon, a single exon was lost in 7.7%, and no evidence indicated total gene deletion occurred in nine hprt exons. However, deletions were found in 79.7% of ENU-induced mutations (62.5%-89.4%, P < 0.01) and in 61.7% of gamma-ray-induced mutations (28.6%-76.5%, P < 0.01). There were deletion mutations in all 9 exons of hprt gene and the most of induced mutations were chain deletion with multiplex exons (97.9% in gamma-ray-induced mutants, 88.1% in ENU-induced mutants).
CONCLUSION: The spectra of spontaneous mutations differs completely from that induced by EUN or 60Co γ-ray. Although both ENU and γ-ray can cause destruction of genetic structure, mechanism of mutagenesis between them may be different.
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Affiliation(s)
- Sheng-Xue Liu
- Department of Healath Toxicology, Preventive Medical College, Third Military Medical University, Chongqing 400038, China
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AOKI Y, SATO H, AMANUMA K. Analytical Chemistry related to Biofunctional Research. Detection of environmental mutagens using transgenic animals. BUNSEKI KAGAKU 2002. [DOI: 10.2116/bunsekikagaku.51.373] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Yasunobu AOKI
- Research Center for Environmental Risk, National Institute for Environmental Studies
| | - Hiromi SATO
- Research Center for Environmental Risk, National Institute for Environmental Studies
| | - Kimiko AMANUMA
- Research Center for Environmental Risk, National Institute for Environmental Studies
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Khaidakov M, Bishop ME, Manjanatha MG, Lyn-Cook LE, Desai VG, Chen JJ, Aidoo A. Influence of dietary antioxidants on the mutagenicity of 7,12-dimethylbenz[a]anthracene and bleomycin in female rats. Mutat Res 2001; 480-481:163-70. [PMID: 11506810 DOI: 10.1016/s0027-5107(01)00180-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Studies on agents that modulate carcinogen-induced genotoxic effects in experimental animals provide end points that can be used for assessing the antimutagenic or anticarcinogenic properties of putative chemopreventive compounds and for predicting their protective efficacy in humans. In this study, we investigated the ability of the dietary antioxidant Vitamins C, E, beta-carotene and the mineral selenium to inhibit the mutant frequency (MF) induced by treatment of rats with 7,12-dimethylbenz[a]anthracene (DMBA), a mammary carcinogen and bleomycin (BLM), an anti-tumor agent that can damage DNA by free radical mechanisms. Both chemicals have been previously shown to be mutagenic in the rat lymphocyte Hprt assay. Adult female Fischer 344 rats were given the antioxidants singly or in a combination 2 weeks prior to mutagen treatment. Antioxidant intake continued for an additional 4 weeks post-mutagen treatment. At sacrifice, spleens were aseptically removed for the isolation of lymphocytes to conduct the mutagenesis assay at the Hprt locus. The DMBA and BLM treatment induced a marked increase in MF, 52.8 x 10(-6) and 19.2 x 10(-6), respectively, over the controls. The MFs seen in the individual antioxidants alone (single or mixture) were relatively similar to the controls, with the exception of Vitamins C and E, that had 1.7- and 1.5-fold increase, respectively. The degree of inhibitory response was dependent on the type of mutagen and the particular antioxidant. BLM/antioxidant combination had inhibitions ranging from 44 to 80%, while DMBA/antioxidant system ranged from 60 to 93%, with Vitamins C and E achieving the highest inhibition in both systems. The mixture displayed low inhibitory responses, 44.6% for BLM/mix and 47% DMBA/mix. On the whole, the results indicate that the dietary constituents tested are antimutagenic; however, because of the gradations seen with the responses, the protective efficacy of these antioxidants may depend on the type of mutagen/carcinogen they encounter. Pending molecular analysis of mitochondrial DNA mutations will also indicate whether there is a shift in the mutational spectra produced by the carcinogens in the presence of antioxidants.
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Affiliation(s)
- M Khaidakov
- Division of Genetic & Reproductive Toxicology, National Center for Toxicological Research, FDA Jefferson Laboratories, Jefferson, AR 72079, USA
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Tates AD, van Dam FJ, Natarajan AT, van Teylingen CM, de Zwart FA, Zwinderman AH, van Sittert NJ, Nilsen A, Nilsen OG, Zahlsen K, Magnusson AL, Törnqvist M. Measurement of HPRT mutations in splenic lymphocytes and haemoglobin adducts in erythrocytes of Lewis rats exposed to ethylene oxide. Mutat Res 1999; 431:397-415. [PMID: 10636004 DOI: 10.1016/s0027-5107(99)00182-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Young adult male Lewis rats were exposed to ethylene oxide (EO) via single intraperitoneal (i.p.) injections (10-80 mg kg-1) or drinking water (4 weeks at concentrations of 2, 5, and 10 mM) or inhalation (50, 100 or 200 ppm for 4 weeks, 5 days week-1, 6 h day-1) to measure induction of HPRT mutations in lymphocytes from spleen by means of a cloning assay. N-ethyl-N-nitrosourea (ENU) and N-(2-hydroxyethyl)-N-nitrosourea (HOENU) were used as positive controls. Levels of N-(2-hydroxyethyl)valine (HOEtVal) adducts in haemoglobin (expressed in nmol g-1 globin) were measured to determine blood doses of EO (mmol kg-1 h, mM h). Blood doses were used as a common denominator for comparison of mutagenic effects of EO administered via the three routes. The mean HPRT mutant frequency (MF) of the historical control was 4.3 x 10(-6). Maximal mean MFs for ENU (100 mg kg-1) and HOENU (75 mg kg-1) were 243 x 10(-6) and 93 x 10(-6), respectively. In two independent experiments, EO injections led to a statistically significant dose-dependent induction of mutations, with a maximal increase in MF by 2.3-fold over the background. Administration of EO via drinking water gave statistically significant increases of MFs in two independent experiments. Effects were, at most, 2.5-fold above the concurrent control. Finally, inhalation exposure also caused a statistically significant maximal increase in MF by 1.4-fold over the background. Plotting of mutagenicity data (i.e., selected data pertaining to expression times where maximal mutagenic effects were found) for the three exposure routes against blood dose as common denominator indicated that, at equal blood doses, acute i.p. exposure led to higher observed MFs than drinking water treatment, which was more mutagenic than exposure via inhalation. In the injection experiments, there was evidence for a saturation of detoxification processes at the highest doses. This was not seen after subchronic administration of EO. The resulting HPRT mutagenicity data suggest that EO is a relatively weak mutagen in T-lymphocytes of rats following exposure(s) by i.p. injection, in drinking water or by inhalation.
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Affiliation(s)
- A D Tates
- Department of Radiation Genetics and Chemical Mutagenesis, Leiden University Medical Centre, Netherlands.
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