Study type: Medical/biological study (experimental study)

Exposure to 2.45 GHz electromagnetic fields elicits an HSP-related stress response in rat hippocampus. med./bio.

Published in: Brain Res Bull 2012; 88 (4): 371-378

Aim of study (acc. to editor)

To study the effects of radiofrequency electromagnetic field exposure on stress-related gene expression in the rat hippocampus.

Background/further details

Rats were divided into the following groups: 1) sham exposure group (for microarray analysis; n=12; investigated 3 h after exposure), 2) exposure group (for microarray analysis; n=12; investigated 3 h after exposure), 3) exposure group (for immunohistochemistry; n=6; investigated 3 h after exposure), 4) sham exposure (for RT-PCR and Western blot; n=6), 5-10) exposure groups, investigated 0 h, 0.5 h, 1 h, 3 h, 6 h, and 12 h after exposure (for RT-PCR and Western blot; n=5 or 6 (contradictory statements)).
RNA was pooled from six exposed/sham exposed hippocampi.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: pulsed
Exposure duration: continuous for 20 min

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Exposure duration continuous for 20 min
Modulation
Modulation type pulsed
Pulse width 2 ms
Packets per second 500
Exposure setup
Exposure source
Distance between exposed object and exposure source 90 cm
Setup radiation trasmitted horizontally from a rectangular horn antenna; using a reflector the radiation was redirected vertically to the exposure chamber; rats placed in Plexiglas restrainers to avoid head movement; restrainers placed inside anechoic chambers at a constant temperature of 25 - 26°C
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 65 mW/cm² average over time - - -
SAR 6 W/kg - - - -

Reference articles

  • Hao Y et al. (2010): STAT3 signalling pathway is involved in the activation of microglia induced by 2.45 GHz electromagnetic fields.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Out of 2048 genes, 23 genes were upregulated and 18 were downregulated. Seven stress-associated heat shock proteins or chaperones were found among the differentially expressed genes, including HSP27 and HSP70 with a markedly increased expression.
The data from immunohistochemistry revealed that the electromagnetic field exposure caused an intensive staining for HSP27 and HSP70 in the hippocampus, especially in the pyramidal cells of cornu ammonis 3 (CA3) and granular cells of dentate gyrus. The gene expression and protein expression profiles of HSP27 and HSP70 were confirmed by RT-PCR and Western blot. Early and long-lasting expression of HSP27 and HSP70 was detected up to 12 h after exposure and exhibited differential expression patterns after exposure.
The authors conclude that the data provide evidence that exposure to electromagnetic fields elicits a stress response in the rat hippocampus. Thermal effects might have contributed to the HSP-related stress response in the rat hippocampus after radiofrequency exposure.

Study character:

Study funded by

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