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

Abstract

Purpose: The question of whether exposure to extremely low frequency magnetic fields (ELF-MF), may contribute to cerebral cancer and neurodegeneration is of current interest. In this study we investigated whether exposure to ELF-MF (50 Hz-1 mT) harms cerebral DNA and induces expression of 70-kDa heat shock protein (hsp70).

Materials and methods: CD1 mice were exposed to a MF (50 Hz-1 mT) for 1 or 7 days (15 h/day) and sacrificed either at the end of exposure or after 24 h. Unexposed and sham-exposed mice were used as controls. Mouse brains were dissected into cerebral cortex-striatum, hippocampus and cerebellum to evaluate primary DNA damage and hsp70 gene expression. Food intake, weight gain, and motor activity were also evaluated.

Results: An increase in primary DNA damage was detected in all cerebral areas of the exposed mice sacrificed at the end of exposure, as compared to controls. DNA damage, as can be evaluated by the comet assay, appeared to be repaired in mice sacrificed 24 h after a 7-day exposure. Neither a short (15 h) nor long (7 days) MF-exposure induced hsp70 expression, metabolic and behavioural changes.

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

Keywords:

• 50 Hz electromagnetic fields
• stress response
• comet assay

Acknowledgements

We gratefully acknowledge Prof. Ermanno Cardelli and his staff (Dept. of Industrial Engineering, Section of Electrotechnics, University of Perugia) for the useful discussion about the experimental set-up. Similarly, we thank Dr Fabrizio Stracci for his valuable statistical advice. This work was supported by University of Perugia and by Fondazione Cassa di Risparmio di Perugia with the found for Scientific and Technological Research, Grant no. 20006.0274.020.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.