Study type: Medical/biological study (experimental study)

Effects of extremely low-frequency electric fields at different intensities and exposure durations on mismatch negativity. med./bio.

Published in: Neuroscience 2014; 272: 154-166

Aim of study (acc. to author)

To investigate the effect of exposure to a 50 Hz-electric field on mismatch negativity component of event-related potentials as well as on apoptosis and oxidative stress in the rat brain.

Background/further details

6 groups of rats were examined (n= 15 per group): 1.) sham exposure for 2 weeks, 2.) sham exposure for 4 weeks, 3.) exposure to an electric field, 12 kV/m for 2 weeks, 4.) exposure to an electric field, 18 kV/m for 2 weeks, 5.) exposure to an electric field, 12 kV/m for 4 weeks and 6.) exposure to an electric field, 18 kV/m for 4 weeks.
At the end of the exposure/sham exposure period mismatch negativity responses were recorded in anesthetized rats. Afterwards, rats were killed and brain tissues were removed.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: 1 hour/day for 2 or 4 weeks
Exposure 2: 50 Hz
Exposure duration: 1 hour/day for 2 or 4 weeks

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Exposure duration 1 hour/day for 2 or 4 weeks
Exposure setup
Exposure source
  • monopole
  • parallel plate capacitor
Chamber rats were exposed in plastic cages
Setup parallel copper plates (50 x 80 cm) were plated with zinc (2-mm thickness); corners of parallel plates were rounded to produce an uniform electric field; plates were placed upright on wooden stands and positioned parallel to each other; plastic cage was placed between plates; plates were spaced at 50 cm distance
Sham exposure A sham exposure was conducted.
Additional info maximum background magnetic field was 0.1 µT (measured), homogeneity and uniformity of electric field was measured (maximum variation less than 1 %)
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 12 kV/m - measured and calculated - -
magnetic flux density 1 µT maximum - - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Exposure duration 1 hour/day for 2 or 4 weeks
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 18 kV/m - measured and calculated - -
magnetic flux density 1 µT maximum - - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

In all exposure groups, the lipid peroxidation was significantly increased compared to the corresponding sham exposure groups. In comparison to the control group, the content of carbonyl groups was significantly increased in group 4 (18 kV/m for 2 weeks), group 5 (12 kV/m for 4 weeks) and group 6 (18 kV/m for 4 weeks). However, no apoptotic cells were found in any of the groups.
In group 6 (18 kV/m for 4 weeks), the mismatch negativity amplitude was significantly decreased in comparison to the 4 weeks sham exposure group. In group 3 (12 kV/m for 2 weeks) and group 4 (18 kV/m for 2 weeks), the mismatch negativity latency was significantly increased compared to the 2 weeks sham exposure group.
The authors conclude that exposure to a 50 Hz-electric field could have an influence on mismatch negativity component of event-related potentials in rats and that these effects could be due to oxidative stress in the rat's brain.

Study character:

Study funded by

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