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Kakomi S, Nakayama T, Shang Y, Tsuruoka C, Sunaoshi M, Morioka T, Shimada Y, Kakinuma S, Tachibana A. The effects of short-term calorie restriction on mutations in the spleen cells of infant-irradiated mice. JOURNAL OF RADIATION RESEARCH 2020; 61:187-196. [PMID: 31909805 PMCID: PMC7246060 DOI: 10.1093/jrr/rrz078] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 10/03/2019] [Accepted: 10/07/2019] [Indexed: 06/10/2023]
Abstract
The risk of cancer due to exposure to ionizing radiation is higher in infants than in adults. In a previous study, the effect of adult-onset calorie restriction (CR) on carcinogenesis in mice after early-life exposure to X-rays was examined (Shang, Y, Kakinuma, S, Yamauchi, K, et al. Cancer prevention by adult-onset calorie restriction after infant exposure to ionizing radiation in B6C3F1 male mice. Int J Cancer. 2014; 135: 1038-47). The results showed that the tumor frequency was reduced in the CR group. However, the mechanism of tumor suppression by CR is not yet clear. In this study, we examined the effects of CR on radiation-induced mutations using gpt delta mice, which are useful to analyze mutations in various tissues throughout the whole body. Infant male mice (1-week old) were exposed to 3.8 Gy X-rays and fed a control (95 kcal/week/mouse) or CR (65 kcal/week/mouse) diet from adult stage (7-weeks old). Mice were sacrificed at the age of 7 weeks, 8 weeks and 100 days, and organs (spleen, liver, lung, thymus) were harvested. Mutations at the gpt gene in the DNA from the spleen were analyzed by using a gpt assay protocol that detects primarily point mutations in the gpt gene. The results showed that mutation frequencies were decreased in CR groups compared with non-CR groups. Sequence analysis of the gpt gene in mutants revealed a reduction in the G:C to T:A transversion in CR groups. Since it is known that 8-oxoguanine could result in this base substitution and that CR has an effect of reducing oxidative stress, these results indicate that the suppression of oxidative stress by CR is the cause of the reduction of this transversion.
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Affiliation(s)
- Saori Kakomi
- Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
| | - Takafumi Nakayama
- Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
- National Institute of Radiological Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Yi Shang
- National Institute of Radiological Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Chizuru Tsuruoka
- National Institute of Radiological Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Masaaki Sunaoshi
- National Institute of Radiological Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Takamitsu Morioka
- National Institute of Radiological Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Yoshiya Shimada
- National Institute of Radiological Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Shizuko Kakinuma
- Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
- National Institute of Radiological Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Akira Tachibana
- Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
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2
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Pottenger LH, Andrews LS, Bachman AN, Boogaard PJ, Cadet J, Embry MR, Farmer PB, Himmelstein MW, Jarabek AM, Martin EA, Mauthe RJ, Persaud R, Preston RJ, Schoeny R, Skare J, Swenberg JA, Williams GM, Zeiger E, Zhang F, Kim JH. An organizational approach for the assessment of DNA adduct data in risk assessment: case studies for aflatoxin B1, tamoxifen and vinyl chloride. Crit Rev Toxicol 2014; 44:348-91. [DOI: 10.3109/10408444.2013.873768] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Walsh ME, Shi Y, Van Remmen H. The effects of dietary restriction on oxidative stress in rodents. Free Radic Biol Med 2014; 66:88-99. [PMID: 23743291 PMCID: PMC4017324 DOI: 10.1016/j.freeradbiomed.2013.05.037] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 05/22/2013] [Accepted: 05/24/2013] [Indexed: 02/07/2023]
Abstract
Oxidative stress is observed during aging and in numerous age-related diseases. Dietary restriction (DR) is a regimen that protects against disease and extends life span in multiple species. However, it is unknown how DR mediates its protective effects. One prominent and consistent effect of DR in a number of systems is the ability to reduce oxidative stress and damage. The purpose of this review is to comprehensively examine the hypothesis that dietary restriction reduces oxidative stress in rodents by decreasing reactive oxygen species (ROS) production and increasing antioxidant enzyme activity, leading to an overall reduction of oxidative damage to macromolecules. The literature reveals that the effects of DR on oxidative stress are complex and likely influenced by a variety of factors, including sex, species, tissue examined, types of ROS and antioxidant enzymes examined, and duration of DR. Here we present a comprehensive review of the existing literature on the effect of DR on mitochondrial ROS generation, antioxidant enzymes, and oxidative damage. In a majority of studies, dietary restriction had little effect on mitochondrial ROS production or antioxidant activity. On the other hand, DR decreased oxidative damage in the majority of cases. Although the effects of DR on endogenous antioxidants are mixed, we find that glutathione levels are the most likely antioxidant to be increased by dietary restriction, which supports the emerging redox-stress hypothesis of aging.
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Affiliation(s)
- Michael E Walsh
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245, USA
| | - Yun Shi
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245, USA; Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245
| | - Holly Van Remmen
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245, USA; Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245; South Texas Veterans Health Care System, San Antonio, TX, 78229, USA.
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4
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The genetic toxicology of methylphenidate hydrochloride in non-human primates. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2009; 673:59-66. [DOI: 10.1016/j.mrgentox.2008.12.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Revised: 12/09/2008] [Accepted: 12/10/2008] [Indexed: 02/06/2023]
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5
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Garcia AM, Busuttil R, Calder B, Dollé MET, Diaz V, McMahan CA, Bartke A, Nelson J, Reddick R, Vijg J. Effect of Ames dwarfism and caloric restriction on spontaneous DNA mutation frequency in different mouse tissues. Mech Ageing Dev 2008; 129:528-33. [PMID: 18565572 PMCID: PMC2581895 DOI: 10.1016/j.mad.2008.04.013] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 03/28/2008] [Accepted: 04/19/2008] [Indexed: 11/25/2022]
Abstract
Genetic instability has been implicated as a causal factor in cancer and aging. Caloric restriction (CR) and suppression of the somatotroph axis significantly increase life span in the mouse and reduce multiple symptoms of aging, including cancer. To test if in vivo spontaneous mutation frequency is reduced by such mechanisms, we crossed long-lived Ames dwarf mice with a C57BL/6J line harboring multiple copies of the lacZ mutation reporter gene as part of a plasmid that can be recovered from tissues and organs into Escherichia coli to measure mutant frequencies. Four cohorts were studied: (1) ad lib wild-type; (2) CR wild-type; (3) ad lib dwarf; and (4) CR dwarf. While both CR wild-type and ad lib dwarf mice lived significantly longer than the ad lib wild-type mice, under CR conditions dwarf mice did not live any longer than ad lib wild-type mice. While this may be due to an as yet unknown adverse effect of the C57BL/6J background, it did not prevent an effect on spontaneous mutation frequencies at the lacZ locus, which were assessed in liver, kidney and small intestine of 7- and 15-month-old mice of all four cohorts. A lower mutant frequency in the ad lib dwarf background was observed in liver and kidney at 7 and 15 months of age and in small intestine at 15 months of age as compared to the ad lib wild-type. CR also significantly reduced spontaneous mutant frequency in kidney and small intestine, but not in liver. In a separate cohort of lacZ-C57BL/6J mice CR was also found to significantly reduce spontaneous mutant frequency in liver and small intestine, across three age levels. These results indicate that two major pro-longevity interventions in the mouse are associated with a reduced mutation frequency. This could be responsible, at least in part, for the enhanced longevity associated with Ames dwarfism and CR.
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Affiliation(s)
| | | | - Brent Calder
- Buck Institute for Age Research, Novato, CA, USA
| | - Martijn E. T. Dollé
- National Institute of Public Health and the Environment, Bilthoven, The Netherlands
| | - Vivian Diaz
- University of Texas Health Science Center, San Antonio, Texas, USA
| | - C. Alex McMahan
- University of Texas Health Science Center, San Antonio, Texas, USA
| | | | - James Nelson
- University of Texas Health Science Center, San Antonio, Texas, USA
| | - Robert Reddick
- University of Texas Health Science Center, San Antonio, Texas, USA
| | - Jan Vijg
- Buck Institute for Age Research, Novato, CA, USA
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Heydari AR, Unnikrishnan A, Lucente LV, Richardson A. Caloric restriction and genomic stability. Nucleic Acids Res 2007; 35:7485-96. [PMID: 17942423 PMCID: PMC2190719 DOI: 10.1093/nar/gkm860] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Caloric restriction (CR) reduces the incidence and progression of spontaneous and induced tumors in laboratory rodents while increasing mean and maximum life spans. It has been suggested that CR extends longevity and reduces age-related pathologies by reducing the levels of DNA damage and mutations that accumulate with age. This hypothesis is attractive because the integrity of the genome is essential to a cell/organism and because it is supported by observations that both cancer and immunological defects, which increase significantly with age and are delayed by CR, are associated with changes in DNA damage and/or DNA repair. Over the last three decades, numerous laboratories have examined the effects of CR on the integrity of the genome and the ability of cells to repair DNA. The majority of studies performed indicate that the age-related increase in oxidative damage to DNA is significantly reduced by CR. Early studies suggest that CR reduces DNA damage by enhancing DNA repair. With the advent of genomic technology and our increased understanding of specific repair pathways, CR has been shown to have a significant effect on major DNA repair pathways, such as NER, BER and double-strand break repair.
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Affiliation(s)
- Ahmad R Heydari
- Department of Nutrition and Food Science, Wayne State University, Detroit, MI 48202, USA
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Aidoo A, Mittelstaedt RA, Bishop ME, Lyn-Cook LE, Chen YJ, Duffy P, Heflich RH. Effect of caloric restriction on Hprt lymphocyte mutation in aging rats. Mutat Res 2003; 527:57-66. [PMID: 12787914 DOI: 10.1016/s0027-5107(03)00072-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Caloric restriction (CR) reduces tumor incidence and retards aging in laboratory animals, including non-human primates. Because of the relationships among mutation, disease susceptibility, and aging, we investigated whether or not CR affects the accumulation of somatic cell mutations in aging animals. Starting at approximately 2 months of age, male CD rats (Harlan Sprague-Dawley-derived) were placed on different levels of dietary intake: ad libitum (AL) feeding, and 90% (10% CR), 75% (25% CR) and 60% (40% CR) of the total calories consumed by AL animals. At 3, 6, 12, and 24 months after the beginning of CR, Hprt mutant frequencies (MFs) were determined. The MFs measured in spleen lymphocytes from AL and CR rats sacrificed at 3 months of dietary restriction were similar for all dietary groups. However, the MFs at 6, 12, and 24 months of CR were significantly higher in AL-fed rats compared with animals on 40% CR: (4.5+/-0.4)x10(-6) versus (3.3+/-0.3)x10(-6) (P=0.032) in 6 months CR rats; (10.3+/-2.3)x10(-6) versus (7.3+/-1.2)x10(-6) in 12 months CR rats (P=0.04), and (18.3+/-3.2)x10(-6) versus (7.8+/-1.0)x10(-6) (P=0.001) in 24 months CR rats. In addition, rats receiving 25% CR for 24 months had a MF, (10.7+/-2.0)x10(-6), between the 40% CR and AL rats. Multiplex PCR of the Hprt gene in mutant clones from 12 and 24 months 40% CR rats and the corresponding AL rats detected deletions in 42% of CR mutants and 19% of AL mutants. Because of the difference in Hprt MF in the two groups, the estimated MF associated with deletions in CR rats was similar to the deletion MF in AL rats. This observation implies that the lower MF in CR rats is due to a reduction in smaller Hprt mutations (i.e. base substitutions and frameshifts). The pattern of smaller Hprt mutations from AL rats suggests that many were produced by reactive oxygen species (ROS). The results indicate that CR reduces the accumulation of spontaneous somatic cell mutation in aging rats, especially those caused by base substitutions and frameshifts.
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Affiliation(s)
- Anane Aidoo
- U.S. FDA Jefferson Laboratories, Division of Genetic & Reproductive Toxicology, National Center for Toxicological Research, 3900 NCTR Road, Jefferson, AR 72079, USA.
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8
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Donovan PJ, Smith GT, Riggs CW, Alexandrov VA. Effects of glucose on cloning efficiency and mutagenesis of fetal rat cells. TERATOGENESIS, CARCINOGENESIS, AND MUTAGENESIS 2002; 22:329-34. [PMID: 12210495 DOI: 10.1002/tcm.10027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In a previous study, treatment of rats with 10% glucose in the drinking water, as fetuses during gestation and for 1.5 months after delivery, significantly enhanced tumor incidence that resulted from N-methyl-N-nitrosourea (MNU, 20 mg/kg) given transplacentally on gestation day 21, with a 1.6-fold increase in overall tumor incidence. We investigated whether glucose would have an effect on MNU-induced mutation in fetal F-344 rat somatic cells as measured in an in vivo/in vitro assay. Rat fetuses were exposed transplacentally to MNU on gestation day 16 and to a 10% glucose solution from gestation day 7 to day 17. Cells were isolated on gestation day 17 for determination of cloning efficiency and for selection of 6-thioguanine (6-TG)-resistant HGPRT mutants. Cloning efficiency of the fetal cells exposed to MNU alone was 22.6+/-2.3% S.E., while that for cells from fetuses exposed to MNU+glucose was 27.5+/-1.6% S.E., which was a significant difference (P=0.018). This indicates an effect of glucose on cell proliferation and survival. MNU treatment significantly increased the mutation frequency of fetal cells from a spontaneous value of 0.4 x 10(-6) per viable cell to (8.8+/-1.8 S.E.,) x 10(-6) (P=0.0087). The coexposure to MNU and glucose yielded a mutant frequency per plate of 0.62+/-0.05 S.E., which was a 1.5-fold increase compared to MNU alone (0.43+/-0.11 S.E., P=0.075. In summary, the data indicate that glucose during pregnancy increases proliferation/survival of fetal cells and possibly also mutation rate.
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Affiliation(s)
- Paul J Donovan
- Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, National Institutes of Health, Frederick, Maryland 21702-1201, USA.
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Abstract
The evolution of testing strategies and methods for identification of mutagenic agents is discussed, beginning with the concern over potential health and population effects of chemical mutagens in the late 1940s that led to the development of regulatory guidelines for mutagenicity testing in the 1970s and 1980s. Efforts to achieve international harmonization of mutagenicity testing guidelines are summarized, and current issues and needs in the field are discussed, including the need for quantitative methods of mutagenic risk assessment, dose-response thresholds, indirect mechanisms of mutagenicity, and the predictivity of mutagenicity assays for carcinogenicity in vivo. Speculation is offered about the future of mutagenicity testing, including possible near-term changes in standard test batteries and the longer-term roles of expression profiling of damage-response genes, in vivo mutagenicity testing methods, and models that better account for differences in metabolism between humans and laboratory model systems.
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Affiliation(s)
- J T MacGregor
- FDA Center for Drug Evaluation and Research, 5600 Fishers Lane, Rockville, MD 20857, USA.
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10
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Shima N, Swiger RR, Heddle JA. Dietary restriction during murine development provides protection against MNU-induced mutations. Mutat Res 2000; 470:189-200. [PMID: 11027974 DOI: 10.1016/s1383-5718(00)00104-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The developmental stage is the most rapid period for the accumulation of somatic mutations. Epidemiological studies have also suggested a significant role of early life for cancer susceptibility, showing a protective effect of modest dietary restriction early in life. To determine if mutation rate, diet, and cancer risk are related, we have investigated the effect of dietary restriction on somatic mutations early in life. The diet of mouse dams was restricted during pregnancy and lactation by 10% from ad libitum control. F(1) pups (SWRxMutaMouse) were weaned at 3 weeks of age. Pups from dams that were on a restricted diet were kept under dietary restriction (40% until 5 weeks of age and then 20% until sacrifice). Only females from litters of seven or eight were used in this study. A portion of pups from both groups were treated with N-methyl-N-nitrosourea (MNU, 50mg/kg, i.p.) at 5 weeks of age and all mice were sacrificed at 10 weeks of age. The frequency of induced mutations was reduced by about 30% at the three loci studied, lacZ (P=0.028) and cII (P=0.042) and Dlb-1 (P=0.032) in the small intestine in the restricted group. A similar decrease in the lacZ mutant frequency was observed in the bone marrow, but the results did not reach statistical significance (P=0.074). Few differences in the lacZ mutant frequency were observed in the colon and the mammary epithelium, but variability of the mutant frequencies was such that an effect of similar magnitude could not be excluded statistically. Analysis of 47 cII mutants revealed that the majority of MNU-induced mutations were G:C to A:T transition at non-CpG sites, with no difference in the mutation spectrum between the two dietary groups.
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Affiliation(s)
- N Shima
- Department of Biology, York University, 4700 Keele Street, Ont., M3J 1P3, Toronto, Canada
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11
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Aidoo A, Desai VG, Lyn-Cook LE, Chen JJ, Feuers RJ, Casciano DA. Attenuation of bleomycin-induced Hprt mutant frequency in female and male rats by calorie restriction. Mutat Res 1999; 430:155-63. [PMID: 10592326 DOI: 10.1016/s0027-5107(99)00197-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Calorie restriction modulates spontaneous and chemically induced tumors and increases maximal life span in experimental animals; however, the mechanism by which calorie restriction exerts its ameliorating effects is not fully elucidated, although reduced levels of reactive oxygen species (ROS) by calorie restriction has generated much interest. In the present study, we have determined whether or not calorie restriction would affect the mutagenic response in rats treated with bleomycin (BLM) a radiomimetic drug that is associated with DNA damage by a free radical mechanism. Fourteen weeks after weaning, the rats were divided into two groups; ad libitum (AL)-fed and 40% calorie restriction. Both AL and calorie-restricted animals were injected with 2.5, 5.0 and 10.0 mg BLM/kg, or with phosphate-buffered saline (PBS), and they were killed 4 weeks post drug treatment. Lymphocytes from the spleens were seeded in 96-well microtiter plates to determine mutant frequency in the hypoxantine guanine phosphoribosyl transferase (Hprt) gene. The mutant frequency in the BLM-treated rats was higher in AL males (P=0.001), and AL females (P=0.0174) than in their calorie-restricted counterparts. The difference in mutagenic response relative to AL males and AL females appeared unrelated to a low percent cloning efficiency seen in the males, since the mean absolute number of Hprt mutant clones was higher in the AL males compared to the females. A reduction in animal weight by calorie restriction was significant in both sexes (P<0.001), but the dose effect appeared non-significant. The results indicate that calorie intake of 60% reduced the mutagenic response of BLM, a compound known to induce oxidative DNA damage, and suggest a possible decrease in ROS as a function of calorie restriction.
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Affiliation(s)
- A Aidoo
- Division of Genetic and Reproductive Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA.
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12
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Beland FA, Fullerton NF, Smith BA, Mittelstaedt RA, Heflich RH. Hprt lymphocyte mutant frequency in relation to DNA adduct formation in rats fed the hepatocarcinogen 2-acetylaminofluorene. Cancer Lett 1999; 143:249-55. [PMID: 10503913 DOI: 10.1016/s0304-3835(99)00134-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The lymphocyte hypoxanthine-guanine phosphoribosyltransferase (Hprt) assay is frequently used as a biomarker for the exposure of both humans and laboratory animals to potentially carcinogenic agents. To obtain information concerning the sensitivity of the rat Hprt lymphocyte assay toward aromatic amine carcinogens, male F344 rats were fed 0.02% 2-acetylaminofluorene (2-AAF) for 1 month and then returned to control diet for 2 months. At 4, 27, 48, 62, and 90 days after the initiation of 2-AAF-feeding, the frequency of mutants in the Hprt gene was determined. In addition, DNA was isolated from liver nuclei, spleen lymphocytes, bone marrow, and thymus, and DNA adducts were analyzed by 32P-postlabeling. 2-AAF feeding resulted in a significant induction of 6-thioguanine-resistant T-lymphocytes and the mutant frequency continued to increase after the 2-AAF feeding was stopped. The same major DNA adduct, N-(deoxyguanosin-8-yl)-2-aminofluorene, was detected in liver, spleen lymphocytes, bone marrow, and thymus. DNA adduct levels were greatest in the tumor target tissue (liver) but occurred in all T-lymphocyte compartments, being highest in spleen lymphocytes. The DNA adduct levels were highest at the end of the 1-month 2-AAF feeding period and decreased rapidly in all tissues. The data indicate that the Hprt lymphocyte mutagenesis assay detects arylamine carcinogens, but with relatively low sensitivity.
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Affiliation(s)
- F A Beland
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA.
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13
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Morris SM, Aidoo A, Chen JJ, Chou MW, Casciano DA. Aflatoxin B1-induced Hprt mutations in splenic lymphocytes of Fischer 344 rats. Results of an intermittent feeding trial. Mutat Res 1999; 423:33-8. [PMID: 10029671 DOI: 10.1016/s0027-5107(98)00222-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In a previous study, we found an increase in the mutant frequency at the Hypoxanthine phosphoribosyl transferase (Hprt) locus in the splenic lymphocytes of Fischer 344 rats acutely exposed to aflatoxin B1 (AFB1). Because an acute exposure may not reflect the exposure pattern of individuals whose diet may contain AFB1-contaminated foodstuffs, we sought to determine if the feeding regimen affected the induction of Hprt mutations in the rat splenic lymphocyte. Thus, Fischer 344 rats were fed either (A) a control diet, (B) various doses of AFB1 for three four-week periods interspersed with two four-week periods of the control diet, or (C) continuously fed 1.6 ppm of AFB1. Not only was a significant increase in the mutant frequency detected in the lymphocytes of rats fed a dose as low as 0. 01 ppm of AFB1, but the increase in the mutant frequency at the end of the 20-week experimental period was consistent with an accumulation of damage induced by AFB1. These results indicate that the rat lymphocyte/Hprt assay is useful for detecting chronic low level exposures. Further, these data suggest that an intermittent, low-level exposure to AFB1 may present a human health risk.
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Affiliation(s)
- S M Morris
- Division of Genetic and Reproductive Toxicology, National Center for Toxicological Research, Food and Drug Administration, Department of Health and Human Services, 3900 NCTR Road, Jefferson, AR 72079, USA.
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14
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Tates AD, van Dam FJ, van Teylingen CM, de Zwart FA, Zwinderman AH. Comparison of induction of hprt mutations by 1,3-butadiene and/or its metabolites 1,2-epoxybutene and 1,2,3,4-diepoxybutane in lymphocytes from spleen of adult male mice and rats in vivo. Mutat Res 1998; 397:21-36. [PMID: 9463549 DOI: 10.1016/s0027-5107(97)00192-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Induction of hprt mutations by 1,3-butadiene (BD) and its metabolites 1,2-epoxybutene (EB) and 1,2,3,4-diepoxybutane (DEB) was studied in lymphocytes from spleens of 6- to 14-week-old mice and 10- to 11-week-old rats. For unknown reasons, results from experiments with mice that received inhalation exposure to BD were quite variable. In the first experiment, mice were exposed for 5 days to 200, 500 or 1300 ppm and this resulted in a statistically significant, dose-dependent, induction of mutations. When the experiment was repeated and an extra expression time for mutations was included, it was not possible to detect induction of mutations. In a third experiment, a 6-day exposure to 500 ppm was mutagenic when mice with zero mutants were not excluded from the statistical analysis of the data. The monofunctional metabolite EB appeared to be mutagenic in mice (3 x 33 and 3 x 100 mg/kg), but not in rats (3 x 33 and 100 mg/kg or 30 days drinking water with 0.1, 0.3, or 1.0 mM EB). Contrary to expectations, there was no induction of mutations in mice and rats exposed to the bifunctional metabolite DEB (mice, 3 x 7, 21, 3 x 14, or 42 mg/kg; rats, 20 or 40 mg/kg or 30 days drinking water with 0.3 or 1 mM DEB), although in our earlier studies with mice and rats, DEB treatment significantly enhanced frequencies of micronuclei in splenocytes and in early spermatids of mice and rats. Some of these results differ from findings reported by other investigators. It is now becoming evident that these differences are, to a large extent, due to differences in age of the animals at the time of treatment. For example, the mutagenic potency of BD, EB and DEB was stronger in preweanling mice or 4-week-old mice than in 8- to 12-week-old adult mice.
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Affiliation(s)
- A D Tates
- Department of Radiation Genetics and Chemical Mutagenesis, Leiden University, Netherlands.
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Abstract
Much of the recent progress in the field of genetic toxicology has come from an increased understanding of the molecular and cellular biology of the mammalian organism. Most prominent has been the ability to detect and quantify somatic mutation and relate the nature of the mutation to the specific type of chemical damage. Building upon the foundation of the human lymphocyte hypoxanthine guanine phosphoribosyl transferase (hprt) system, and later, the mouse hprt system, methods for the detection and quantification of hprt mutations in rat lymphocytes were developed. These methods are described in this report as is the ongoing validation of the assay. Additionally, the characterization of the recovered mutants and a comparison of the mutation spectrum in the rat lymphocyte system to the spectrum in cancer genes, such as H-ras and p53, and the spectrum in transgenic systems, such as lacI, are included. The development of the rat lymphocyte hprt system and validation of the assay at the molecular level, provide an effective and reliable measure of genetic damage in an in vivo system which is readily comparable to measurement of genetic damage in the human.
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Affiliation(s)
- A Aidoo
- Department of Health and Human Services, Food and Drug Administration, National Center for Toxicological Research, Jefferson, AR 72079, USA.
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16
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Chou MW, Chen W. Food restriction reduces aflatoxin B1 (AFB1)-DNA adduct formation, AFB1-glutathione conjugation, and DNA damage in AFB1-treated male F344 rats and B6C3F1 mice. J Nutr 1997; 127:210-7. [PMID: 9039820 DOI: 10.1093/jn/127.2.210] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The objective of this study was to examine effects of food restriction (FR) on the metabolic activation of aflatoxin B1 (AFB1) in rats and mice, which are AFB1-sensitive and -resistant rodent species, respectively. Forty percent FR [60% of ad libitum (AL) food consumption] reduced the metabolic activation of AFB1 in both rats and mice, causing formation of hepatic AFB1-DNA adducts to be 43% and 31% lower, respectively. The AFB1-DNA adduct 8,9-dihydro-8-(N7-guanyl)-9-hydroxyaflatoxin B1 (AFB1-N7-Gua) was predominantly formed in rat liver DNA; the formation of the ring-open analogue of AFB1-N7-Gua, AFB1-formamidopyrimidine (AFB1-FAP), was predominantly found in mouse liver DNA. In contrast to the in vivo results, the in vitro AFB1-DNA adduct formation mediated by the microsomes of liver, kidney or lung from FR-mice was greater than the formation of AFB1-DNA adducts mediated by the tissue microsomes from the AL-mice. Food restriction induced hepatic glutathione S-transferase (GST) activity, as measured by the formation of AFB1-glutathione conjugates (AFB1-SG), in both rats and mice; AFB1-SG was also formed in mouse kidney. Food restriction-induced GST activity assayed in an in vitro system, using [3H]AFB1-8,9-epoxide and glutathione (GSH) as substrates, was also found when mouse kidney and lung cytosolic fractions were used. Food restriction inhibited the AFB1-induced DNA double strand breaks in mouse kidney. The reduction of levels of AFB1-DNA adduct formation in mouse kidney was comparable to the degree of AFB1-induced DNA strand breakages. The results of this study indicate that the metabolic activation of AFB1 can be modulated by FR through the alteration of the formation of AFB1-DNA adducts and AFB1-SG conjugation. However, species and tissue specificities exist regarding the metabolic activation of AFB1.
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Affiliation(s)
- M W Chou
- Division of Nutritional Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA
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17
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Manjanatha MG, Lyn-Cook LE, Culp SJ, Beland FA, Heflich RH, Aidoo A. Lymphocyte mutant frequency in relation to DNA adduct formation in rats treated with tumorigenic doses of the mammary gland carcinogen 7,12-dimethylbenz[a]anthracene. Mutat Res 1996; 357:89-96. [PMID: 8876684 DOI: 10.1016/0027-5107(96)00086-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The ability of the rat lymphocyte hprt assay to detect tissue-specific carcinogens was evaluated using 7,12-dimethylbenz[a]anthracene (DMBA) administered under conditions that result in mammary gland tumors. Fifty-day-old female Sprague-Dawley rats were given single doses of 5 and 20 mg/kg DMBA by gavage, and the frequency of 6-thioguanine-resistant (TGr) T-lymphocytes was measured over a period of 21 weeks. A time- and dose-dependent increase in mutant frequency was found, with a maximum frequency found 9-15 weeks after treatment with 20 mg/kg of DMBA. Rats were also dosed with 1, 2.5, 5, 10, 15 and 20 mg/kg of DMBA and assayed for TGr mutant frequency 10 weeks after treatment. A significant linear dose-response was found, with all the DMBA doses resulting in significant increases in mutant frequency. To determine whether or not DMBA-induced mutants in rat lymphocytes reflected the DNA damage in the target tissue, rats were treated with 5 and 20 mg/kg of DMBA and spleen lymphocytes and mammary gland tissue were assayed for DNA adduct formation 1, 3 and 7 days later. A similar pattern of 32P- postlabeled adducts, involving both dG and dA nucleotides, was found in DNA from both the target tissue and the surrogate lymphocytes. Adduct formation was dose responsive in both tissues, with a 2.3- to 4-fold higher concentration in mammary gland as compared with lymphocytes. These results indicate that the rat lymphocyte hprt assay is sensitive to a mammary gland carcinogen and that similar types of DNA adducts are associated with both the lymphocyte mutants and the mammary gland tumors induced by DMBA.
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Affiliation(s)
- M G Manjanatha
- Department of Health and Human Services, Food and Drug Administration, Jefferson, AR 72079, USA.
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18
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Heflich RH, Mittelstaedt RA, Manjanatha MG, Lyn-Cook LE, Aidoo A. DNA sequence analysis of hprt mutations in lymphocytes from Sprague-Dawley rats treated with 7,12-dimethylbenz[a]anthracene. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 1996; 28:5-12. [PMID: 8698046 DOI: 10.1002/(sici)1098-2280(1996)28:1<5::aid-em3>3.0.co;2-g] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Treatment of female Sprague-Dawley rats with the potent mammary gland carcinogen 7,12-dimethylbenz[a]anthracene (DMBA) results in the formation of DNA adducts with dG and dA and in the induction of 6-thioguanine-resistant (TGr) lymphocyte mutants. In this study, we have examined the types of mutations induced in TGr lymphocytes from DMBA-treated rats. DNA from 263 TGr lymphocyte clones was screened for mutations in exons 2, 3, and 8 of the hprt gene by polymerase chain reaction (PCR) amplification of the exons followed by heteroduplex analysis using denaturing gradient-gel electrophoresis. Twenty-five of the clones produced heteroduplexes in exon 2, 35 produced heteroduplexes in exon 3, and 36 produced heteroduplexes in exon 8. Direct sequence analysis of the heteroduplexes revealed 96 mutations, and at least 74 of these mutations were produced independently. Eighty-five of the total mutations were simple base pair (bp) substitutions, with A --> T and G --> T transversions being the predominant types. Seven mutations were deletions, three were complex bp substitutions, and one was an insertion. The results suggest that the types of mutations produced by DMBA in rat lymphocytes are specific to the DNA adducts produced by this compound.
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Affiliation(s)
- R H Heflich
- Division of Genetic Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
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