Medical/biological study (experimental study)

Electromagnetic fields at 2.45 GHz trigger changes in heat shock proteins 90 and 70 without altering apoptotic activity in rat thyroid gland.

Published in: Biol Open 2012; 1 (9): 831-838

Aim of study (acc. to author)

To examine whether exposure to a 2.45 GHz electromagnetic field modifies the level of the heat shock proteins Hsp70 and Hsp90 and damages the morphological structure in the thyroid gland as well as to investigate whether apoptosis occurs.
Background/further details: Female rats were distributed equally into two groups: 1.) sacrificed 90 min after exposure with different specific absorption rates: 1 a) 0 W, 1 b) 1.5 W, 1 c) 3 W and 1 d) 12 W (n= 6 per subgroup). 2.) sacrificed 24 h after exposure with different absorption rates: 2 a) 0 W, 2 b) 1.5 W, 2 c) 3 W and 2 d) 12 W (n= 6 per subgroup).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Exposure duration: continuous for 30 min
Exposure 2: 2.45 GHz
Exposure duration: continuous for 30 min
Exposure 3: 2.45 GHz
Exposure duration: continuous for 30 min
General information
rats were treated in the following groups and subgroups: group I: killed after 90 min a) sham exposure b) exposure to 1.5 W c) exposure to 3 W d) exposure to 12 W group II: killed after 24 h a) sham exposure b) exposure to 1.5 W c) exposure to 3 W d) exposure to 12 W
Exposure 1
Main characteristics
Frequency 2.45 GHz
Type
Exposure duration continuous for 30 min
Exposure setup
Exposure source/structure
Setup details 1.25 m x 0.65 m x 0.45 m GTEM cell; rat placed inside the GTEM cell at the region of maximum field uniformity
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Remarks
power 1.5 W - measured -
electric field strength 28.48 V/m - measured -
SAR 0.046 W/kg mean measured and calculated in the thyroid
SAR 0.041 W/kg peak value measured and calculated in the thyroid
SAR 0.017 W/kg mean measured and calculated -
SAR 0.089 W/kg peak value measured and calculated in the body
Exposure 2
Main characteristics
Frequency 2.45 GHz
Type
Exposure duration continuous for 30 min
Exposure setup
Exposure source/structure
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Remarks
power 3 W - measured -
electric field strength 40.28 V/m - - -
SAR 0.104 W/kg mean measured and calculated in the thyroid
SAR 0.076 W/kg peak value measured and calculated in the thyroid
SAR 0.036 W/kg mean measured and calculated -
SAR 0.18 W/kg peak value measured and calculated in the body
Exposure 3
Main characteristics
Frequency 2.45 GHz
Type
Exposure duration continuous for 30 min
Exposure setup
Exposure source/structure
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Remarks
power 12 W - measured -
electric field strength 80.56 V/m - - -
SAR 0.482 W/kg mean measured and calculated in the thyroid
SAR 0.34 W/kg peak value measured and calculated in the thyroid
SAR 0.161 W/kg mean measured and calculated -
SAR 0.795 W/kg peak value measured and calculated in the body
Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

90 minutes after the exposure to 1.5 W, a significant decrease in Hsp70 levels occurred in comparison to the control. Hsp90 levels were significantly decreased 90 minutes after the exposure at power levels of 1.5 W and 3 W, as well as 24 hours after the exposure at a power level of 3 W compared to the control. Tissue slices of the thyroid gland of exposed animals (1.5 W and 3 W) did not show any morphological alterations when compared to unexposed animals. 90 minutes and 24 hours after the exposure at 12 W, only a slight loss of cell adhesion was observed in some thyroid gland follicles. No indication for apoptosis was observed in tissue slices from exposed (all groups and different specific absorption rates) or sham exposed animals.
The results suggest that exposure to a 2.45 GHz electromagnetic field may alter levels of cellular stress in rat thyroid gland.
Study character:

Study funded by

  • Xunta de Galicia, Spain

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