Brain DNA damage and 70-kDa heat shock protein expression in CD1 mice exposed to extremely low frequency magnetic fields

Abstract

These results indicate that in vivo ELF-MF induce reversible brain DNA damage while they do not elicit the stress response.

Brain hsp70 expression and DNA damage in mice exposed to extremely low frequency magnetic fields: A dose-response study

“…Neither primary DNA damage nor hsp70 induction was detected in any of the mouse pup brains collected after 7, 14 and 21 days of exposure (15 h/day) (Mariucci et al 2009). Unlike the mouse pups, the adult mice presented reversible DNA strand breaks and no increase in hsp70 expression following exposure to 1 mT ELF-MF for 1 or 7 days (15 h/day) (Mariucci et al 2010). Taken together, our results seemed to indicate that ELF-MF exposure -although causing cerebral DNA damage in an age-dependent way -does not infl uence hsp70 expression in mouse brain.…”

“…During sham-exposure (i.e., in the switched-off exposure system) magnetic fl ux density was 0.06 μ T. Th e design of the exposure system allowed MF uniformity higher than 97% in a volume of 20 ϫ 20 ϫ 10 cm. Other details regarding the exposure system have been described previously (Mariucci et al 2010). Th e exposure apparatus was placed in a temperature-controlled room at 22 ϩ 1 ° C.…”

“…Th e levels of hsp70 were determined by routine methods (Mariucci et al 2007(Mariucci et al , 2010. Tissue samples were homogenized and aliquots of denatured supernatant proteins (20 μ g/well) were loaded, and immunoblotted with mouse monoclonal anti-hsp70 (SPA-810, Stressgen Biotechnologies Corporation, Victoria, BC, Canada; 1:2000) and a peroxidaseconjugated anti-mouse secondary antibody (A4416, 1:5000).…”

“…Indeed, some epidemiological reports and analyses integrating the results of independent studies (such as pooled analyses, meta-analyses and aggregating evidence studies) have shown that residential and/or occupational long-term exposure to ELF-MF is positively associated with childhood leukemia (Wertheimer and Leeper 1979, Dose-dependent stressful and genotoxic eff ects of ELF-MF 563 heat shock protein (hsp70) in the brains of pup and adult CD1 mice (Mariucci et al 2009(Mariucci et al , 2010. Neither primary DNA damage nor hsp70 induction was detected in any of the mouse pup brains collected after 7, 14 and 21 days of exposure (15 h/day) (Mariucci et al 2009).…”

“…Th erefore, we designed the present study in which adult male CD1 mice were exposed to four diff erent densities of 50-Hz MF (i.e., 0.1, 0.2, 1 or 2 mT) for 15 h/day for 7 days. Th e ELF-MF densities were selected keeping in mind that: (i) 0.2 mT and 1 mT are the acceptable reference levels proposed by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) for public environmental and occupational exposure, respectively (ICNIRP 2010), (ii) 1 mT exposure would allow us to confi rm or not our previous study (Mariucci et al 2010), and (iii) 2 mT exposure would enable us to verify whether, within the 1 -3 mT window, the harmful eff ects of exposure are weaker than at lower fl ux densities, as suggested by some experimental evidence (Juutilainen et al 2006). Th e eff ect of ELF-MF exposure was evaluated in terms of hsp70 expression and DNA damage/repair.…”