Department of Medical-Surgical Specialties and Public Health, Perugia, Italy.
Int J Radiat Biol. 2013 Jul;89(7):562-70. doi: 10.3109/09553002.2013.782449. Epub 2013 Apr 16.
To determine whether a dose-response relationship exists among exposure to extremely low frequency magnetic fields (ELF-MF) at different densities and 70-kDa heat shock protein (hsp70) expression and DNA damage in mouse brain.
Male CD1 mice were exposed to ELF-MF (50 Hz; 0.1, 0.2, 1 or 2 mT) for 7 days (15 h/day) and sacrificed either at the end of exposure or after 24 h. Hsp70 expression was determined in cerebral cortex-striatum, hippocampus and cerebellum by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot analysis. Primary DNA damage was evaluated in the same tissues by comet assay. Sham-exposed mice were used as controls.
No changes in both hsp70 mRNA and corresponding protein occurred following exposure to ELF-MF, except for a weak increase in the mRNA in hippocampus of exposed mice to 0.1 mT ELF-MF. Only mice exposed to 1 or 2 mT and sacrificed immediately after exposure presented DNA strand breaks higher than controls in all the cerebral areas; such DNA breakage reverted to baseline in the mice sacrificed 24 h after exposure.
These data show that high density ELF-MF only induce reversible brain DNA damage while they do not affect hsp70 expression.
确定暴露于不同密度的极低频磁场（ELF-MF）与 70kDa 热休克蛋白（hsp70）表达和小鼠大脑 DNA 损伤之间是否存在剂量反应关系。
雄性 CD1 小鼠接受 ELF-MF（50 Hz；0.1、0.2、1 或 2 mT）暴露 7 天（每天 15 小时），并在暴露结束时或暴露后 24 小时处死。通过实时逆转录-聚合酶链反应（RT-PCR）和 Western blot 分析测定大脑皮质-纹状体、海马和小脑中的 hsp70 表达。通过彗星试验评估同一组织中的原发性 DNA 损伤。假暴露小鼠用作对照。
除了暴露于 0.1 mT ELF-MF 的小鼠海马中的 hsp70 mRNA 略有增加外，暴露于 ELF-MF 后 hsp70 mRNA 和相应蛋白均未发生变化。只有暴露于 1 或 2 mT 并在暴露后立即处死的小鼠在所有大脑区域的 DNA 链断裂均高于对照组；暴露后 24 小时处死的小鼠中，这种 DNA 断裂恢复到基线。
这些数据表明，高密度 ELF-MF 仅诱导可逆性脑 DNA 损伤，而不影响 hsp70 表达。
