Study type: Medical/biological study (experimental study)

Effect of 50 Hz Extremely Low-Frequency Electromagnetic Fields on the DNA Methylation and DNA Methyltransferases in Mouse Spermatocyte-Derived Cell Line GC-2 med./bio.

By: Liu Y, Liu WB, Liu KJ, Ao L, Zhong JL, Cao J, Liu JY
Published in: Biomed Res Int 2015: 237183
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Aim of study (acc. to author)

The epigenetic effects of exposure of mouse spermatocyte-derived cells to a 50 Hz magnetic field should be investigated by means of DNA methylation and gene expression analysis.

Background/further details

Mouse spermatocyte-derived cells were investigated to explore the mechanisms of action of possible adverse effects of magnetic fields on the male reproductive system.
Cells were divided into 4 groups: exposure to a magnetic field of 1) 1 mT, 2) 2 mT, 3) 3 mT and 4) sham exposure.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: intermittent (5 min on, 10 min off) for 72 h
Exposure 2: 50 Hz
Exposure duration: intermittent (5 min on, 10 min off) for 72 h
Exposure 3: 50 Hz
Exposure duration: intermittent (5 min on, 10 min off) for 72 h

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Exposure duration intermittent (5 min on, 10 min off) for 72 h
Exposure setup
Exposure source
Chamber 90 mm petri dishes
Setup cell dishes were placed in an incubator (constant 37°C, 5% CO2); the exposure system generated a vertical field via two four-coil systems (two coils with 56 windings, two coils with 50 windings) and two rectangular waveguides placed in a metal chamber
Sham exposure A sham exposure was conducted.
Additional info the temperature difference between sham exposure and exposure never exceeded 0.3°C
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - measured - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Exposure duration intermittent (5 min on, 10 min off) for 72 h
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 2 mT - measured - -

Exposure 3

Main characteristics
Frequency 50 Hz
Type
Exposure duration intermittent (5 min on, 10 min off) for 72 h
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 3 mT - measured - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The global DNA methylation was significantly lower in cells exposed to 1 mT (group 1) compared to the sham exposure group and significantly higher in cells exposed to 2 mT and 3 mT (groups 2 and 3).
In the mRNA and protein expression of DNA methyl-transferases, a trend towards decreased expression rates in groups 1 and 2 and increased expression rates in group 3 in comparison to the sham exposure group was observed.
In the genome wide differential promoter DNA methylation analysis, 296 differentially methylated sites (higher percentage of enhanced methylation) compared to the sham exposure were found in group 1 and 70 differentially methylated sites (higher percentage of decreased methylation) were found in group 3. Comparing the promoter methylation of selected genes with their mRNA expression in both groups, genes with decreased methylation showed a significantly increased mRNA expression and genes with increased methylation showed a significantly decreased mRNA expression.
The genome wide mRNA expression showed 84 differentially expressed genes in group 1 and 324 differentially expressed genes in group 3 compared to the sham exposure group. In both groups, most affected genes belonged to olfactory transduction pathway but different target genes were identified in each group.
The authors conclude that exposure of mouse spermatocyte-derived cells to a 50 Hz magnetic field might have epigenetic effects via DNA methylation with consequential altered gene expression, although the consequences for health remain unknown.

Study character:

Study funded by

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