Raj H G, Gupta K, Rohil V, Bose M, Biswas G, Singh S K, Jain S C, Parmar V S, Olsen C E, Wengel J
Department of Biochemistry, V.P. Chest Institute, Delhi, India.
Teratog Carcinog Mutagen. 1998;18(5):249-61.
Aflatoxin B, (AFB1) is a clastogen that causes cellular damage by covalent modification of nucleic acids. In this investigation, male rats were injected i.p. with AFB1 (8 mg/kg b.w.) in DMSO and the same dose of AFB1 was also administered intratracheally (i.t.) to the animals separately. The animals were killed after 26 h of the carcinogen treatment, femur bone was removed, and bone marrow cells were isolated and stained with Mayer's hematoxylin and eosin. Micronuclei (Mn) were scored by using light microscopy. Bronchoalveolar lavage (BAL) was prepared from rats administered AFB1 i.t. A part of BAL was fixed with 70% ethanol, stained with the fluorochrome DAPI, and analysed for cell cycle variations; the other part of the lavage was used for making slides to record Mn with a fluorescent microscope. A significantly greater proportion of lung cells were found to enter cell cycle with extended S-phase due to AFB1 treatment. Mn were induced in polychromatic erythrocytes (PCE) as compared to normochromatic erythrocytes (NCE) in the bone marrow of AFB1-treated rats, where there was nearly a three-fold increase in the number of Mn of bone marrow cells. The administration of AFB1 resulted in a two-fold rise in the Mn in the lung cells. The effect of BSO, DEM, and PB, the modulators of AFB1 metabolism, was studied on AFB1-induced Mn formation. A significant increase in the Mn score in PCEs of BSO- and DEM-treated rats was noted, while a slight reduction in the Mn score was noted in the case of PB-treated rats. The administration of the methanol extract of the leaves of Piper argyrophyllum (taken up in DMSO) to rats for a week exhibited normalising effect on AFB1-induced Mn in bone marrow cells. These observations record the induction of Mn in lung cells due to AFB1 for the first time. We propose the utility of AFB1-induced Mn as a model for screening plant extracts as inhibitors of genotoxicity. Prevention of genotoxic changes described above by phytochemicals is being pursued in our Laboratories.
黄曲霉毒素B1（AFB1）是一种断裂剂，可通过对核酸进行共价修饰而导致细胞损伤。在本研究中，给雄性大鼠腹腔注射溶于二甲基亚砜的AFB1（8毫克/千克体重），并将相同剂量的AFB1分别经气管内（i.t.）给予动物。在致癌物处理26小时后处死动物，取出股骨，分离骨髓细胞，并用梅耶苏木精和伊红染色。通过光学显微镜对微核（Mn）进行计数。从经气管内给予AFB1的大鼠制备支气管肺泡灌洗（BAL）液。将一部分BAL液用70%乙醇固定，用荧光染料DAPI染色，并分析细胞周期变化；灌洗液的另一部分用于制作载玻片，用荧光显微镜记录微核。发现由于AFB1处理，有显著更高比例的肺细胞进入细胞周期且S期延长。与AFB1处理大鼠骨髓中的正色素红细胞（NCE）相比，多染性红细胞（PCE）中诱导产生了微核，其中骨髓细胞微核数量增加了近三倍。AFB1的给药导致肺细胞中微核数量增加了两倍。研究了AFB1代谢调节剂BSO、DEM和PB对AFB1诱导的微核形成的影响。注意到经BSO和DEM处理的大鼠的PCE中微核评分显著增加，而经PB处理的大鼠的微核评分略有降低。给大鼠连续一周给予银叶胡椒叶的甲醇提取物（溶于二甲基亚砜）对AFB1诱导的骨髓细胞微核有正常化作用。这些观察首次记录了AFB1诱导肺细胞产生微核。我们提出将AFB1诱导的微核作为筛选植物提取物作为遗传毒性抑制剂的模型。我们实验室正在研究植物化学物质对上述遗传毒性变化的预防作用。
