Study type: Medical/biological study (experimental study)

Involvement of NMDA receptor in low-frequency magnetic field-induced anxiety in mice. med./bio.

Published in: Electromagn Biol Med 2014; 33 (4): 312-326

Aim of study (acc. to author)

To investigate the effects of extremely low frequency magnetic fields on anxiety-related behavior in mice and associated neurochemical alterations the brain.

Background/further details

Mice were exposed for up to 120 days under the following conditions (n=6-8 for every condition and point in time: 1.) sham exposure, 2.) sham exposure + muscimol (GABAA receptor agonist, 0.25 mg per kg body weight), 3.) sham exposure + bicuculline (1 mg per kg body weight), 4.) sham exposure + N-methyl-D-aspartate (15 mg per kg body weight) 5.) sham exposure + MK-801 (NMDA receptor antagonist, 0.03 mg per kg body weight), 6.) exposure, 7.) exposure + muscimol, 8.) exposure + bicuculline, 9.) exposure + N-methyl-D-aspartate and 10.) exposure + MK-801.
Anxiety-related behavior was tested on the 7th, 30th, 60th, 90th, and 120th day of exposure, while biochemical analyses were only performed after 120 days.
Optimal concentrations of the injected substances were examined in a dose-dependent behavioral study (remark EMF-Portal: Results are presented in the study but not in our summary because no magnetic field exposure was performed).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 8 hours/day for 7, 30, 60, 90, or 120 days

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Exposure duration continuous for 8 hours/day for 7, 30, 60, 90, or 120 days
Exposure setup
Exposure source
Setup pair of round Helmholtz coils, spaced apart at a distance equal to their radii (45 cm); coils were constructed of glaze-insulated copper wire (d=1.2 mm) on wooden frame and had 100 turns; for exposure, mice stayed in their home cages with grid plastic covers which were placed on a platform settled in the center of the coils
Sham exposure A sham exposure was conducted.
Additional info control mice were exposed to the local geomagnetic field of 1 µT (!?)
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - measured - -

Reference articles

  • Liu T et al. (2008): Anxiogenic effect of chronic exposure to extremely low frequency magnetic field in adult rats.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The open field test and observations in the elevated plus maze indicated that exposure induced anxiety-related behavior in mice: In exposed mice, the time spent in open areas was significantly decreased compared to the sham exposure. Additionally, the number of defecation and rearing was significantly increased compared to the sham exposure group.
The social interaction was significantly decreased in the exposure group compared to the sham exposure group.
An administration of N-methyl-D-aspartate to exposed mice significantly deteriorated the exposure induced anxiety compared to exposure alone while the NMDA receptor antagonist MK-801 significantly attenuated anxiety-related behavior. No significant behavioral alterations were observed due to the administration of muscimol and bicuculline.
In the hippocampus and hypothalamus of exposed mice, the levels of gamma aminobutyric acid and glutamate were significantly increased compared to the sham exposed ones.
The authors conclude that extremely low frequency magnetic fields could induce anxiety-related behavior in mice. Furthermore, the results indicated an involvement of the NMDA receptor.

Study character:

Study funded by

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