Medical/biological Study (experimental study)

50-Hz magnetic field exposure influences DNA repair and mitochondrial DNA synthesis of distinct cell types in brain and kidney of adult mice. med./biol.

PubMed Entry

Journal web site

Aim of study (according to author)
To investigate the extent of nuclear DNA repair and the relative amount of nuclear DNA single-strand breaks for different cell types in brain and kidney of adult mice after a 50 Hz magnetic field exposure. The question should be answered whether or not DNA damage occurs.
Background/further details:
Five minutes after ending exposure, the animals received [³H]thymidine (for autoradiographs) and were killed 2 h later. Autoradiographs were prepared from paraffin sections of brains and kidneys.

Endpoint

• genotoxicity/mutation: DNA repair, single-strand breaks, and mitochondrial DNA synthesis

Exposure
General category: magnetic field, 50/60 Hz (AC)

Field characteristics	Parameters
50 Hz exposure duration: continuous for 8 weeks	magnetic flux density: 1.8 mT mean value

Exposed system:
animal (species/strain): mouse/Han:NMRI
whole body exposure

Methods
Endpoint/Measurement parameters/Methodology

• genotoxicity/mutation: extent of nuclear DNA repair (unscheduled DNA synthesis (nuclear grain numbers)); amount of nuclear DNA single-strand breaks (in situ nick translation (nuclear grain numbers)); mitochondrial DNA synthesis (cytoplasmic grain densities) (autoradiographs)

Main outcome of study (according to author)
A significant increase in both unscheduled DNA synthesis and in situ nick translation was only found for epithelial cells of the choroid plexus. Thus, these two independent methods indicate that nuclear DNA damage is produced by long-lasting and strong magnetic field irradiation. The fact that only plexus epithelial cells were affected might point to possible effects of magnetic fields on iron transport across the blood-cerebrospinal fluid (Liquor cerebrospinalis) barrier, but the mechanisms are currently not understood.
Mitochondrial DNA synthesis was exclusively increased in renal epithelial cells of distal convoluted tubules (Tubuli renalis) and collecting ducts, i.e., cells with a very high content of mitochondria, possibly indicating increased metabolic activity of these cells.
In summary, the pilot study has shown that a long-lasting and strong 50 Hz magnetic field exposure with a flux density above 1 mT appears to be able to produce nuclear DNA damage within at least one distinct cell population in the brain.

(Study character: medical/biological study, experimental study, pilot/exploratory/preliminary study)

Study funded by

• RWTH Aachen University, Germany

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