Reddy Siddharth B, Weller Julie, Desjardins-Holmes Dawn, Winters Tara, Keenliside Lynn, Prato Frank S, Prihoda Thomas J, Thomas Vijayalaxmi, Thomas Alex W
Lawson Health Research Institute, London, Ontario, Canada.
Bioelectromagnetics. 2010 Sep;31(6):445-53. doi: 10.1002/bem.20576.
For 8 weeks, adult CD-1 male mice were continuously exposed to complex time-varying pulsed magnetic fields (PMF) generated in the horizontal direction by a set of square Helmholtz coils. The PMF were <1000 Hz and delivered at a peak flux density of 1 mT. Sham-exposed mice were kept in a similar exposure system without a PMF. Positive control animals exposed to 1 Gy gamma radiation were also included in the study. Blood samples were collected before (time 0) and at 2, 4, 6, and 8 weeks. All mice were euthanized at the end of 8 weeks and their bone marrow was collected. From each blood and bone marrow sample, smears were prepared on microscope slides, fixed in absolute methanol, air-dried, and stained with acridine orange. All slides were coded and examined using a fluorescence microscope. The extent of genotoxicity and cytotoxicity was assessed from the incidence of micronuclei (MN) and percent polychromatic erythrocytes (PCE) in the blood and bone marrow, respectively. The data indicated that both indices in PMF-exposed mice were not significantly different from those observed in sham-exposed animals. In contrast, positive control mice exhibited significantly increased MN, and decreased percentages of PCE in both tissues. Thus, the overall data suggested that 8 weeks of continuous exposure to PMF did not induce significantly increased genotoxicity and cytotoxicity in experimental mice. Further investigations are underway using other genotoxicity assays (comet assay, gamma-H2AX foci, and chromosomal aberrations) to assess genotoxicity following PMF exposure.
8周内，成年CD-1雄性小鼠持续暴露于由一组方形亥姆霍兹线圈在水平方向产生的复杂时变脉冲磁场（PMF）中。该脉冲磁场频率<1000Hz，峰值通量密度为1mT。假暴露小鼠饲养在类似的暴露系统中，但无脉冲磁场。研究中还纳入了接受1Gyγ辐射的阳性对照动物。在暴露前（时间0）以及暴露2、4、6和8周时采集血样。8周结束时对所有小鼠实施安乐死并采集其骨髓。从每份血液和骨髓样本中制备涂片，固定于无水甲醇中，空气干燥后用吖啶橙染色。所有玻片均编码并使用荧光显微镜检查。分别根据血液和骨髓中微核（MN）的发生率和多染红细胞（PCE）的百分比评估遗传毒性和细胞毒性程度。数据表明，暴露于脉冲磁场的小鼠的这两个指标与假暴露动物中观察到的指标无显著差异。相比之下，阳性对照小鼠在两个组织中的微核均显著增加，多染红细胞百分比降低。因此，总体数据表明，连续8周暴露于脉冲磁场并未在实验小鼠中诱导显著增加的遗传毒性和细胞毒性。目前正在使用其他遗传毒性检测方法（彗星试验、γ-H2AX焦点和染色体畸变）进行进一步研究，以评估脉冲磁场暴露后的遗传毒性。
