Optimal dose selection of N-methyl-N-nitrosourea for the rat comet assay to evaluate DNA damage in organs with different susceptibility to cytotoxicity

Kitamoto, Sachiko; Matsuyama, Ryoko; Uematsu, Yasuaki; Ogata, Keiko; Ota, Mika; Yamada, Tōru; Miyata, Kaori; Funabashi, Hitoshi; Saito, Koichi

doi:10.1016/j.mrgentox.2015.05.001

Cited by 7 publications

(9 citation statements)

References 26 publications

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“…Zulliger et al showed retinal changes to be MNU concentrationdependent, a relationship that was most obvious with the ONL 43 . Other reports showed a dose-dependent response over the threshold dose as a carcinogen 44,45 .…”

Section: Discussionmentioning

confidence: 92%

An experimental pig model with outer retinal degeneration induced by temporary intravitreal loading of N-methyl-N-nitrosourea during vitrectomy

Choi

Anh

Kim

et al. 2021

Sci Rep

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We aimed to develop an outer retinal degeneration pig model induced by temporary intravitreal loading of N-methyl-N-nitrosourea (MNU) during vitrectomy. In a preliminary experiment involving 5 mini-pig cases to determine the appropriate concentration of MNU, the vitreous cavity of each eye was filled with 4, 8, 10, 12, or 16 mg/mL MNU for 10 min, which was then replaced with a balanced salt solution. Multimodal examinations including spectral-domain optical coherence tomography (OCT) images and full-field electroretinography (ffERG) were obtained at baseline and week 2, week 6, and week 12. The retinal degeneration was classified according to the amplitudes of a dark adaptive (DA) 10.0 a-wave amplitude. The degree of moderate retinal degeneration was defined as DA 10.0 a-wave amplitude ≥ 10% and < 60% of baseline amplitude. The degree of severe degeneration was defined as DA 10.0 a-wave amplitude < 10% of baseline amplitude, noise, or flat signal. Hematoxylin and eosin staining and immunohistochemistry were performed at week 12. The main experiments were conducted first with 10 cases of 5 mg/mL and later with 13 cases of 10 mg/mL. In the preliminary experiment, degree of outer retinal degeneration increased with MNU concentration. Use of 4, 8, 10, 12, and 16 mg/mL MNU showed no, moderate, severe, severe, and atrophic changes, respectively. In the main experiments, there were 9 cases of moderate retinal degeneration and 1 case of severe degeneration in 5 mg/mL MNU group. Two cases of moderate degeneration and 11 of severe degeneration were recorded in 10 mg/mL group. Mean thickness of total retina, inner nuclear layer, and outer nuclear layer decreased at week 2 in both groups. The mean amplitudes on ffERG decreased at week 2. The ffERG and OCT findings did not change from week 2 to week 6 or week 12. The results of staining supported those of ffERG and OCT. Temporal MNU loading in a vitrectomized pig-eye model induced customized outer retinal degeneration with changing the concentration of MNU.

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Section: Discussionmentioning

confidence: 92%

An experimental pig model with outer retinal degeneration induced by temporary intravitreal loading of N-methyl-N-nitrosourea during vitrectomy

Choi

Anh

Kim

et al. 2021

Sci Rep

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“…As shown in Fig. 6, MNU toxicity caused liver damage [15], resulting in AST and ALT levels that were more than double those of normal controls. However, CA-HE50 treatment resulted in a significant inhibition of liver damage due to its cytoprotective effects, similar to normal https://doi.org/10.4162/nrp.2020.14.3.203 control levels.…”

Section: Protective Effect Of Ca-he50 In a Model Of N-methyl-n-nitrosmentioning

confidence: 87%

Centella asiaticaextract prevents visual impairment by promoting the production of rhodopsin in the retina

Park

Jeon

2020

Nutr Res Pract

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BACKGROUND/OBJECTIVE: Centella asiatica, also known as Gotu kola, is a tropical medicinal plant native to Madagascar, Southeast Asia, and South Africa. It is well known to have biological activities, including wound healing, anti-inflammatory, antidiabetic, cytotoxic, and antioxidant effects. The purpose of this study was to determine the efficacy of extracts of C. asiatica against age-related eye degeneration and to examine their physiological activities. MATERIALS/METHODS: To determine the effects of CA-HE50 (C. asiatica 50% EtOH extract) on retinal pigment cells, we assessed the cytotoxicity of CoCl 2 and oxidized-A2E in ARPE-19 cells and observed the protective effects of CA-HE50 against N-methyl-N-nitrosourea (MNU)-induced retinal damage in C57BL/6 mice. In particular, we measured factors related to apoptosis and anti-oxidation and the protein levels of rhodopsin/opsin. We also measured glucose uptake to characterize glucose metabolism, a major factor in cell protection. RESULTS: Induction of cytotoxicity with CoCl 2 and oxidized-A2E inhibited decreases in the viability of ARPE-19 cells when CA-HE50 was administered, and promoted glucose uptake under normal conditions (P < 0.05). In addition, CA-HE50 inhibited degeneration/apoptosis of the retina in the context of MNU-induced toxicity (P < 0.05). In particular, CA-HE50 at 200 mg/kg inhibited the cleavage of pro-caspase-3 and pro-poly (ADP-ribose)-polymerase and maintained the expressions of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 similar to normal control levels. Rhodopsin/opsin expression was maintained at a higher level than in normal controls. CONCLUSION: A series of experiments confirmed that CA-HE50 was effective for inhibiting or preventing age-related eye damage/degeneration. Based on these results, we believe it is worthwhile to develop drugs or functional foods related to age-related eye degeneration using CA-HE50.

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“…These findings referred that MUN can methylate DNA at the O6-position of guanine, causing GC→AT mutations, DNA double-strand breaks, interstrand cross-links, nonrepaired N-methylpurines, and abasic sites [31][32][33][34]. Similarly, MNU produces CAs, MNPCE, and comet tail formation in rodent bone marrow cells, liver, glandular stomach, and peripheral blood lymphocytes of rodents [16,[35][36][37][38]. Surprisingly, the absence of genotoxicity was observed in mouse spermatocytes treated with MNU (80 mg/kg) under experimental conditions.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of the cytotoxic, anticancer, and genotoxic activities of Acacia nilotica flowers and their effects on N-methyl-N-nitrosourea-induced genotoxicity in mice

et al. 2022

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Purpose In this study, two main research objectives were examined: (1) the cytotoxic and anticancer activities of the aqueous methanol extract from Acacia nilotica flowers on three human cancer cells, namely lung A549, breast MCF-7, and leukemia THP-1 cells, and (2) the genotoxic effects of A. nilotica extract and its influence on DNA damage induced by N-methyl-N-nitrosourea (MNU) in mice. Methods Mice were orally treated with A. nilotica extract (200, 500, and 800 mg/kg for 4 days) with or without MNU (80 mg/kg intraperitoneally for 24 h). Results In vitro experiments showed that A549 cells were the most sensitive to A. nilotica extract among the tested cell lines. A. nilotica extract inhibited A549 cell proliferation by blocking the cell cycle at the G2/M phase and accumulating apoptotic cells in the sub-G0/G1 phase in A549 cells. In vivo experiments showed that MNU induced positive and negative genotoxicity in bone marrow cells and spermatocytes, respectively. Negative genotoxicity was observed in A. nilotica extract-treated groups only. However, A. nilotica extract (800 mg/kg) remarkably increased comet tail formation in bone marrow cells. Unexpectedly, the absence of antigenotoxicity was observed in three cotreated groups with A. nilotica extract and MNU compared with the MNU-treated group. Astonishingly, cotreatment with MNU and A. nilotica extract at a dose above 200 mg/kg remarkably increased micronucleus and comet tail formation in bone marrow cells compared with the MNU-treated group. Conclusions A. nilotica extract possessed anticancer activity with relative genotoxic effects at high doses.

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Optimal dose selection of N-methyl-N-nitrosourea for the rat comet assay to evaluate DNA damage in organs with different susceptibility to cytotoxicity

Cited by 7 publications

References 26 publications

An experimental pig model with outer retinal degeneration induced by temporary intravitreal loading of N-methyl-N-nitrosourea during vitrectomy

An experimental pig model with outer retinal degeneration induced by temporary intravitreal loading of N-methyl-N-nitrosourea during vitrectomy

Centella asiaticaextract prevents visual impairment by promoting the production of rhodopsin in the retina

Evaluation of the cytotoxic, anticancer, and genotoxic activities of Acacia nilotica flowers and their effects on N-methyl-N-nitrosourea-induced genotoxicity in mice

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