Medical/biological study (experimental study)

Subchronic exposure of hsp70.1-deficient mice to radiofrequency radiation med./bio.

By: Lee JS, Huang TQ, Lee JJ, Pack JK, Jang JJ, Seo JS

Published in: Int J Radiat Biol 2005; 81 (10): 781-792

Aim of study (acc. to author)

To determine whether sub-chronic radiofrequency exposure can cause constitutive induction of a stress response at a cellular and/or molecular level in hsp70.1-deficient mice due to repeated stimulation.

Background/further details

Previously the authors generated hsp70.1-deficient mice to elucidate the in vivo function of HSP70 (heat shock protein 70) in detail. The renal tissues and embryonic fibroblasts of these mice were shown to be more vulnerable to hyperosmotic stress.

Endpoint

molecular biosynthesis: stress response (expression of heat shock proteins)

Exposure

- RF field
- CDMA
- mobile communications

Exposure	Parameters
Exposure 1: 849 MHz Exposure duration: twice daily for 45 min with a 15 min interval, 5 days a week for 4, 8 and 10 weeks	SAR: 0.4 W/kg mean (whole body) power: 60 W maximum
Exposure 2: 849 MHz Exposure duration: one or two 45 min exposures	SAR: 0.4 W/kg mean (whole body)
Exposure 3: 1,763 MHz Exposure duration: twice daily for 45 min with a 15 min interval, 5 days a week for 4, 8 and 10 weeks	SAR: 0.4 W/kg mean (whole body)
Exposure 4: 1,763 MHz Exposure duration: one or two 45 min exposures	SAR: 0.4 W/kg mean (whole body)

Exposure 1

Main characteristics

Frequency	849 MHz
Type	electromagnetic field
Exposure duration	twice daily for 45 min with a 15 min interval, 5 days a week for 4, 8 and 10 weeks

Exposure setup

Exposure source	signal generator
Chamber	Stainless steel reverberation chamber (2293 mm x 2296 mm x 1700 mm) fitted with mode stirrer for field uniformity
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	0.4 W/kg	mean	calculated	whole body	-
power	60 W	maximum	-	-	-

Measurement and calculation details

SAR was computed using FDTD simulation. Electric field was measured at 24 points using an isotropic field strength probe.

Exposure 2

Main characteristics

Frequency	849 MHz
Type	electromagnetic field
Exposure duration	one or two 45 min exposures

Exposure setup

Exposure source	same setup as exposure 1

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	0.4 W/kg	mean	calculated	whole body	-

Exposure 3

Main characteristics

Frequency	1,763 MHz
Type	electromagnetic field
Exposure duration	twice daily for 45 min with a 15 min interval, 5 days a week for 4, 8 and 10 weeks

Exposure setup

Exposure source	not specified

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	0.4 W/kg	mean	calculated	whole body	-

Exposure 4

Main characteristics

Frequency	1,763 MHz
Type	electromagnetic field
Exposure duration	one or two 45 min exposures

Exposure setup

Exposure source	same setup as exposure 1

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	0.4 W/kg	mean	calculated	whole body	-

Exposed system:

animal
mouse/hsp70.1-deficient (hsp70.1 -/-) and wild type (hsp70.1 +/+)
whole body

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: stress response (expression of heat shock proteins (HSP70, HSP90, HSP25) and phosphorylation of the stress-activated kinases (MAPK, extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase 1/2 (JNK1/2), p38 MAPK); Western blot)
cell viability/cell division/proliferation: acitivity of cell proliferation (immunocytochemistry; hematoxylin stain; microscopic examination); apoptosis (TUNEL assay)
morphol./histopathol. changes: histopathological examination of major tissue (hematoxylin and eosin stain)
body weight; food consumption

Investigated system:

isolated bio./chem. substance
intact cell/cell culture
tissue slices
tissue homogenates

Investigated organ system:

brain/CNS
liver, adrenal gland, kidney, spleen, stomach, bladder, lung, heart, thymus, testis or ovary

Time of investigation:

after exposure

Main outcome of study (acc. to author)

No difference was revealed in the histopathological analysis between sham-exposed and radiofrequency exposed mice. There was no evidence of increased proliferative and apoptotic activities.
The levels of the heat shock proteins showed no obvious changes. Radiofrequency irradiation did not affect the phosphorylation status of stress-activated kinases.
The hsp70.1-deficient mice did not show any significant changes in terms of cell proliferation, apoptosis, or stress response due to exposure of 849 MHz or 1763 MHz radiofrequency fields.

Study character:

medical/biological study
experimental study
full/main study
blind study

Study funded by

Ministry of Information and Communication, Korea

Deshmukh PS et al. (2015): Cognitive impairment and neurogenotoxic effects in rats exposed to low-intensity microwave radiation
Yang XS et al. (2012): Exposure to 2.45 GHz electromagnetic fields elicits an HSP-related stress response in rat hippocampus
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
Cherenkov DA et al. (2009): The role of protein kinase SAPK/JNK in cell responses to low-intensity nonionizing radiation
Vanderwaal RP et al. (2006): HSP27 phosphorylation increases after 45°C or 41°C heat shocks but not after non-thermal TDMA or GSM exposures

Subchronic exposure of hsp70.1-deficient mice to radiofrequency radiation med./bio.

Aim of study (acc. to author)

Background/further details

Endpoint

Exposure

Exposure 1

Main characteristics

Exposure setup

Parameters

Measurement and calculation details

Exposure 2

Main characteristics

Exposure setup

Parameters

Exposure 3

Main characteristics

Exposure setup

Parameters

Exposure 4

Main characteristics

Exposure setup

Parameters

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

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