Study type: Medical/biological study (experimental study)

Benzodiazepine system is involved in hyperalgesia in rats induced by the exposure to extremely low frequency magnetic fields. med./bio.

Published in: Arch Pharm Res 2005; 28 (2): 238-242

Aim of study (acc. to author)

The aim of the present study was to elucidate the interaction between magnetic fields and the benzodiazepine-GABA complex system.

Background/further details

In a previous study (publication 11849), the authors found that exposure of 20 Gauss magnetic fields alone induced a significant reduction of latency of stimulus-reaction in mice (in hot plate test), i.e. an increase of pain threshold. From these investigations, the authors hypothesized that magnetic field-induced hyperalgesia occurs via the benzodiazepine receptor.
In order to further confirm this effect of magnetic fields, diazepam (a benzodiazepine receptor agonist) and/or flumazenil (a benzodiazepine receptor antagonist) combined with magnetic field exposure were used. GABA receptor antogonists were also studied.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 60 Hz
Exposure duration: 1 h, 3 h and 6 h
Exposure 2: 60 Hz
Exposure duration: 1 h, 3 h and 6 h
Exposure 3: 60 Hz
Exposure duration: 1 h, 3 h and 6 h

Exposure 1

Main characteristics
Frequency 60 Hz
Type
Waveform
Exposure duration 1 h, 3 h and 6 h
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 500 µT unspecified unspecified - -

Exposure 2

Main characteristics
Frequency 60 Hz
Type
Waveform
Exposure duration 1 h, 3 h and 6 h
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT unspecified unspecified - -

Exposure 3

Main characteristics
Frequency 60 Hz
Type
Waveform
Exposure duration 1 h, 3 h and 6 h
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 2 mT unspecified unspecified - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

When testing the pain threshold magnetic fields or diazepam induced hyperalgesic effects with the reduction of latency. These effects were blocked by a pretreatment of flumazenil.
When the rats were exposed simultaneously to magnetic fields and diazepam, the latency tended to decrease without statistical significance. The induction of hyperalgesia by co-exposure to magnetic fields and diazepam was also blocked by flumazenil.
However, the pretreatment of GABA receptor antagonists did not antagonize the hyperalgesic effect of magnetic fields.
These data suggest that the benzodiazepine system may be involved in magnetic fields-induced hyperalgesia.

Study character:

Study funded by

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