Study type: Medical/biological study (experimental study)

Exposure to 2.45 GHz microwave radiation provokes cerebral changes in induction of HSP-90 a/ß.heat shock protein in rat. med./bio.

Published in: Electromagn Waves (Camb) 2010; 100: 351-379

Aim of study (acc. to author)

To analyze the changes of the Hsp90 level and its distribution in the brain of rats, 90 minutes and 24 hours after acute exposure to 2.45 GHz. In addition, further indicators of neuronal insults such as "dark neurons", chromatin condensation and nucleus fragmentation were investigated.

Background/further details

72 female rats were exposed and divided into two main groups: group A (killed 90 minutes after exposure) and group B (killed 24 hours after exposure). Both groups were divided into four subgroups: one control group and three exposure groups (1.5, 3 and 12 W).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: CW
Exposure duration: continuous for 30 min
  • electric field strength: 28.48 V/m
  • power: 1.5 W
  • SAR: 0.034 W/kg mean (brain) (± 0.001 W/kg)
  • SAR: 0.042 W/kg peak value (brain) (± 0.004 W/kg)
  • SAR: 0.02 W/kg mean (whole body) (± 0.002 W/kg)
  • SAR: 0.099 W/kg peak value (whole body) (± 0.001 W/kg)
Exposure 2: 2.45 GHz
Modulation type: CW
Exposure duration: continuous for 30 min
Exposure 3: 2.45 GHz
Modulation type: CW
Exposure duration: continuous for 30 min

General information

72 female rats were divided into two main groups: group A (killed 90 minutes after exposure) group B (killed 24 hours after exposure). Both groups were divided into four subgroups: one control group and three exposure groups (1.5, 3 and 12 W).

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Exposure duration continuous for 30 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Setup 1.25 m x 0.65 m x 0.45 m GTEM cell; animal placed inside the GTEM cell in a methacrylate holder at the location with the maximum field uniformity
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 28.48 V/m - - - -
power 1.5 W - measured - -
SAR 0.034 W/kg mean estimated brain ± 0.001 W/kg
SAR 0.042 W/kg peak value estimated brain ± 0.004 W/kg
SAR 0.02 W/kg mean estimated whole body ± 0.002 W/kg
SAR 0.099 W/kg peak value estimated whole body ± 0.001 W/kg

Exposure 2

Main characteristics
Frequency 2.45 GHz
Type
Exposure duration continuous for 30 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 40.28 V/m - - - -
power 3 W - measured - -
SAR 0.069 W/kg mean estimated brain ± 0.005 W/kg
SAR 0.086 W/kg peak value estimated brain ± 0.007 W/kg
SAR 0.041 W/kg mean estimated whole body ± 0.0034 W/kg
SAR 0.203 W/kg mean estimated whole body ± 0.016 W/kg

Exposure 3

Main characteristics
Frequency 2.45 GHz
Type
Exposure duration continuous for 30 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 80.56 V/m - - - -
power 12 W - measured - -
SAR 0.27 W/kg mean estimated brain ± 0.021 W/kg
SAR 0.337 W/kg peak value estimated brain ± 0.026 W/kg
SAR 0.16 W/kg mean estimated whole body ± 0.0120 W/kg
SAR 0.791 W/kg mean estimated whole body ± 0.061 W/kg

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

In group A, a significant increase in the amount of Hsp90 expressed in the somatosensory cortex and the limbic cortex was found for the 12 W exposure group compared to the control group. There was a non-significant increase of Hsp90 in the hippocampus. For all three exposure groups significant increases in the hypothalamus were detected.
In group B, the Hsp90 amount increased in the somatosensory cortex (significant for the 3 W and 12 W exposure groups) and in the hypothalamus (significant for the 12 W exposure group). In contrast, a significant decrease of the Hsp90 level was found in the limbic cortex for all three exposure groups. In the hippocampus also significant decreases were found except of the group exposed at the lowest specific absorption rate.
No morphological changes, such as chromatin condensation or nucleus fragmentation, were observed in both groups. Some dark neurons were found in group A and B after maximal specific absorption rate exposure.
The results suggest that acute exposure to electromagnetic fields triggered an imbalance in the Hsp90-levels.

Study character:

Study funded by

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