Vodicka P, Koskinen M, Vodicková L, Stetina R, Smerák P, Bárta I, Hemminki K
Institute of Experimental Medicine, Academy of Sciences of Czech Republic, Videnska 1083, 14220 4, Prague, Czech Republic.
Chem Biol Interact. 2001 Sep 28;137(3):213-27. doi: 10.1016/s0009-2797(01)00253-8.
Genotoxic and clastogenic effects of styrene were studied in mice. Male NMRI mice were exposed by inhalation to styrene in concentrations of 750 and 1500 mg/m3 for 21, 7, 3 and 1 days (6 h/day, 7 days/week). Followed parameters included styrene in blood, specific styrene oxide (SO) induced DNA adducts, DNA strand breaks and micronuclei. The formation of SO induced 7-SO-guanines and 1-SO-adenines in DNA was analysed from lung tissues by two versions of the 32P-postlabeling technique. In lungs after 21 days of exposure to 1500 mg/m3 the level of 7-SO-guanine was 23.0+/-11.9 adducts/10(8) normal nucleotides, while 1-SO-adenine was detected at the levels of 0.6+/-0.2 adducts/10(8) normal nucleotides. Both 7-SO-guanines and 1-SO-adenines strongly correlated with exposure parameters, particularly with styrene concentration in blood (r=0.875, P=0.0002 and r=0.793, P=0.002, respectively). DNA breaks were measured in peripheral lymphocytes, bone marrow cells and liver cells using comet assay. To discern oxidative damage and abasic sites, endonuclease III was used. In bone marrow of exposed mice slight increase of strand breaks can be detected after 7 days of inhalation. A significant increase was revealed in the endonuclease III-sensitive sites after 21 days of inhalation in bone marrow. In the liver cells inhalation exposure to both concentrations of styrene did not virtually affect either levels of DNA single-strand breaks or endonuclease III-sensitive sites. The inhalation of 1500 mg/m3 of styrene induced significant increase of micronuclei after 7 days of exposure (10.4+/-2.5/1000 cells, i.e. twice higher micronuclei frequency than in controls). After 21 days of inhalation no significant difference between the control group and the two exposed groups was observed. Whether the decrease of micronuclei after 21 days of inhalation was due to the inhibition of cell proliferation caused by styrene or due to the natural elimination of chromatide fragments, remains to be clarified. An interesting link has been found between DNA single-strand breaks in bone marrow and frequencies of micronuclei (r=0.721, P=0.028).
研究了苯乙烯对小鼠的遗传毒性和致断裂效应。雄性NMRI小鼠通过吸入浓度为750和1500 mg/m³的苯乙烯，分别暴露21天、7天、3天和1天（每天6小时，每周7天）。监测的参数包括血液中的苯乙烯、特定的环氧苯乙烯（SO）诱导的DNA加合物、DNA链断裂和微核。采用两种版本的³²P后标记技术，从肺组织中分析DNA中SO诱导的7-SO-鸟嘌呤和1-SO-腺嘌呤的形成。在暴露于1500 mg/m³ 21天后的肺组织中，7-SO-鸟嘌呤的水平为23.0±11.9个加合物/10⁸个正常核苷酸，而检测到的1-SO-腺嘌呤水平为0.6±0.2个加合物/10⁸个正常核苷酸。7-SO-鸟嘌呤和1-SO-腺嘌呤均与暴露参数密切相关，特别是与血液中的苯乙烯浓度显著相关（r分别为0.875，P = 0.0002和r = 0.793，P = 0.002）。使用彗星试验检测外周血淋巴细胞、骨髓细胞和肝细胞中的DNA断裂。为了区分氧化损伤和无碱基位点，使用了核酸内切酶III。在暴露小鼠的骨髓中，吸入7天后可检测到链断裂略有增加。吸入21天后，骨髓中核酸内切酶III敏感位点显著增加。在肝细胞中，吸入两种浓度的苯乙烯实际上对DNA单链断裂水平或核酸内切酶III敏感位点均无影响。吸入1500 mg/m³的苯乙烯7天后，微核显著增加（10.4±2.5/1000个细胞，即微核频率比对照组高两倍）。吸入21天后，对照组与两个暴露组之间未观察到显著差异。吸入21天后微核减少是由于苯乙烯抑制细胞增殖还是由于染色单体片段的自然消除，仍有待阐明。已发现骨髓中的DNA单链断裂与微核频率之间存在有趣的联系（r = 0.721，P = 0.028）。
