title: Brain hsp70 expression and DNA damage in mice exposed to extremely low frequency magnetic fields: a dose-response study.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  These data show that high density ELF-MF only induce reversible brain DNA damage while they do not affect hsp70 expression.
authors.affiliation: Department of Medical-Surgical Specialties and Public Health, Perugia, Italy.
authors.forename: Milena
authors.initials: M
authors.lastname: Villarini
authors.forename: Maria Vittoria
authors.initials: MV
authors.lastname: Ambrosini
authors.forename: Massimo
authors.initials: M
authors.lastname: Moretti
authors.forename: Luca
authors.initials: L
authors.lastname: Dominici
authors.forename: Elena
authors.initials: E
authors.lastname: Taha
authors.forename: Danilo
authors.initials: D
authors.lastname: Piobbico
authors.forename: Cristiana
authors.initials: C
authors.lastname: Gambelunghe
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Mariucci
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology* / Q000528:radiation effects*; D004247:DNA / Q000235:genetics* / Q000528:radiation effects*; D004249:DNA Damage / Q000502:physiology*; D004307:Dose-Response Relationship, Radiation; D004560:Electricity; D004574:Electromagnetic Fields; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D008297:Male; D051379:Mice; D011829:Radiation Dosage
chemical_list: D018840:HSP70 Heat-Shock Proteins; D004247:DNA