Medical/biological study (experimental study)

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

By: Yang XS, He GL, Hao YT, Xiao Y, Chen CH, Zhang GB, Yu ZP

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

effects on the neurological system: gene expression in rat hippocampus

Exposure

- 2.45 GHz
- microwave pulses

Exposure	Parameters
Exposure 1: 2.45 GHz Modulation type: pulsed Exposure duration: continuous for 20 min	power density: 65 mW/cm² average over time SAR: 6 W/kg

Exposure 1

Main characteristics

Frequency	2.45 GHz
Type	electromagnetic field
Exposure duration	continuous for 20 min

Modulation

Modulation type	pulsed
Pulse width	2 ms
Packets per second	500

Exposure setup

Exposure source	horn antenna
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:

animal
rat/Sprague-Dawley
partial body: head

Methods Endpoint/measurement parameters/methodology

effects on the neurological system: gene expression in rat hippocampus (DNA microarray; MGEC-20s, BioStar Genechip); HSP27 and HSP70 expression in the hippocampus (immunohistochemistry, semiquantitative RT-PCR and Western blot)

Investigated system:

Investigated organ system:

brain/CNS

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:

medical/biological study
experimental study
full/main study

Study funded by

National Natural Science Foundation (NSFC), China

Deshmukh PS et al. (2016): Effect of Low Level Subchronic Microwave Radiation on Rat Brain
Dasdag S et al. (2015): Long term and excessive use of 900 MHz radiofrequency radiation alter microRNA expression in brain
Deshmukh PS et al. (2015): Cognitive impairment and neurogenotoxic effects in rats exposed to low-intensity microwave radiation
Dasdag S et al. (2015): Effects of 2.4 GHz radiofrequency radiation emitted from Wi-Fi equipment on microRNA expression in brain tissue
Kesari KK et al. (2014): Effect of 3G Cell Phone Exposure with Computer Controlled 2-D Stepper Motor on Non-thermal Activation of the hsp27/p38MAPK Stress Pathway in Rat Brain
Sepehrimanesh M et al. (2014): Analysis of rat testicular proteome following 30-day exposure to 900 MHz electromagnetic field radiation
Fragopoulou AF et al. (2012): Brain proteome response following whole body exposure of mice to mobile phone or wireless DECT base radiation
Watilliaux A et al. (2011): Effect of exposure to 1,800 MHz electromagnetic fields on heat shock proteins and glial cells in the brain of developing rats
Jorge-Mora T et al. (2010): Exposure to 2.45 GHz microwave radiation provokes cerebral changes in induction of HSP-90 a/ß.heat shock protein in rat
Finnie JW et al. (2009): Heat shock protein induction in fetal mouse brain as a measure of stress after whole of gestation exposure to mobile telephony radiofrequency fields
Nittby H et al. (2008): Exposure to radiation from global system for mobile communications at 1,800 MHz significantly changes gene expression in rat hippocampus and cortex
Belyaev IY et al. (2006): Exposure of rat brain to 915 MHz GSM microwaves induces changes in gene expression but not double stranded DNA breaks or effects on chromatin conformation
Lee JS et al. (2005): Subchronic exposure of hsp70.1-deficient mice to radiofrequency radiation
Fritze K et al. (1997): Effect of global system for mobile communication microwave exposure on the genomic response of the rat brain