Study type: Medical/biological study

Neuritin reverses deficits in murine novel object associative recognition memory caused by exposure to extremely low-frequency (50 Hz) electromagnetic fields. med./bio.

Published in: Sci Rep 2015; 5: 11768

Aim of study (acc. to author)

The effects of exposure of mice to a 50 Hz magnetic field on the memory and morphology of neurons in the hippocampus as well as the role of neuritin in this process should be investigated.

Background/further details

Neuritin was recently discovered as an important growth factor for neural development, which promotes neuronal outgrowth and arborization in the brain. Mice with an overexpression of neuritin in the hippocampus were experimentally created (transfection with a viral vector) and used beside normal mice.
Mice were divided into the following groups: exposure of normal mice to a magnetic field with 1) 0.4 mT or 2) 0.6 mT for 7 days and 3) with 1 mT for up to 21 days. Moreover, 4) neuritin-viral-transfected, 5) sham-viral-transfected and 6) saline-transfected mice were exposed to a magnetic field with 1 mT for 10 days. Additional sham exposed control groups were used for each experiment. (remark EMF-Portal: not all group sizes were mentioned, but stated sizes were at least n=10).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 12 h/day for 7 days
Exposure 2: 50 Hz
Exposure duration: continuous for 12 h/day for 7 days
Exposure 3: 50 Hz
Exposure duration: continuous for 12 h/day for up to 21 days

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 12 h/day for 7 days
Exposure setup
Exposure source
Chamber glass cage
Setup the glass cage, containing 4 to 5 mice, was placed between the coils; the surfaces of the glass cage were parallel to the force lines of the magnetic field; temperature in glass cage under exposure conditions showed a difference of 0.4 ± 0.1°C compared to the sham exposure
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.4 mT - measured - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 12 h/day for 7 days
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.6 mT - measured - -

Exposure 3

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 12 h/day for up to 21 days
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - measured - -

Reference articles

  • Varani K et al. (2012): Effect of pulsed electromagnetic field exposure on adenosine receptors in rat brain.
  • Ongaro A et al. (2012): Electromagnetic fields (EMFs) and adenosine receptors modulate prostaglandin E(2) and cytokine release in human osteoarthritic synovial fibroblasts.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Exposure to the magnetic field had no effect on the locomotor activity of mice, whereas the object recognition was significantly impaired in mice exposed to a 1 mT magnetic field for 7 days (group 3) compared to the control group.The dendritic spine density of neurons in the hippocampus was significantly reduced after exposure to a 1 mT magnetic field for 7 or 10 (group 3) days compared to the control group. However, all effects were transient and could not be detected after 14 days anymore.
Mice with an overexpression of neuritin in the hippocampus (group 4) showed no significant differences between the exposure and control groups in dendritic spine density and object recognition after 10 days. Moreover, both parameters were significantly increased compared to mice with normal neuritin protein expression (groups 5 and 6).
The authors conclude that exposure of mice to a 50 Hz magnetic field could impair the memory of mice and alter the morphology of neurons in the hippocampus. However, neuritin could attenuate these effects.

Study character:

Study funded by

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