Medical/biological study (experimental study)

Melatonin and a spin-trap compound block radiofrequency electromagnetic radiation-induced DNA strand breaks in rat brain cells med./bio.

By: Lai H, Singh NP

Published in: Bioelectromagnetics 1997; 18 (6): 446-454

Aim of study (acc. to author)

To study the effects of microwave exposure on DNA strand breaks in rat brain cells and to investigate whether free radicals play a role.

Background/further details

Rats were treated with the free scavengers melatonin and N-tert-butyl-alpha-phenylnitrone (PBN) to see whether they can block radiofrequency-induced DNA single-strand breaks and double-strand breaks (animals were treated before and after exposure).

Endpoint

genotoxicity/mutation: DNA damage

Exposure

- microwaves

Exposure	Parameters
Exposure 1: 2.45 GHz Modulation type: pulsed Exposure duration: continuous for 2 h	power density: 2 mW/cm² spatial average SAR: 1.2 W/kg average over mass (whole body)

General information

rats were treated with melatonin or spin-trap compound N-tert-butyl-alpha-phenylnitrone (PBN) brfore or after exposure to EMF; experiments were done in four groups: i) EMF + drug ii) EMF only iii) sham exposure + drug iv) sham exposure

Exposure 1

Main characteristics

Frequency	2.45 GHz
Type	electromagnetic field
Polarization	circular
Exposure duration	continuous for 2 h

Modulation

Modulation type	pulsed
Pulse width	2 µs
Packets per second	500

Exposure setup

Exposure source	cylindrical waveguide system in TE₁₁ mode
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power density	2 mW/cm²	spatial average	-	-	-
SAR	1.2 W/kg	average over mass	calculated	whole body	-

Reference articles

Chou CK et al. (1984): SAR in rats exposed in 2,450-MHz circularly polarized waveguides
Guy AW et al. (1979): Circularly polarized 2450 MHz waveguide system for chronic exposure of small animals to microwaves

Exposed system:

Methods Endpoint/measurement parameters/methodology

genotoxicity/mutation: DNA damage (single-strand breaks; double-strand breaks; microgel electrophoresis assay (length of DNA migration))

Investigated system:

DNA/RNA
cell lysates

Investigated organ system:

brain/CNS

Time of investigation:

after exposure

Main outcome of study (acc. to author)

Treatment of rats immediately before and after radiofrequency irradiation with either melatonin or the spin-trap compound N-tert-butyl-alpha-phenylnitrone (PBN) blocks the effects of radiofrequency irradiation (increase in DNA single-strand breaks and double-strand breaks). Since both melatonin and PBN are efficient free radical scavengers it is hypothesized that free radicals are involved in radiofrequency-induced DNA damage.
Since cumulated DNA strand breaks in brain cells can lead to neurodegenerative diseases and cancer and since an excess of free radicals has been suggested to be the cause of various human diseases, results from this study could have important implications for the health effects of radiofrequency exposure.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

not stated/no funding

Deshmukh PS et al. (2013): Detection of Low Level Microwave Radiation Induced Deoxyribonucleic Acid Damage Vis-a-vis Genotoxicity in Brain of Fischer Rats
Xu S et al. (2010): Exposure to 1800 MHz radiofrequency radiation induces oxidative damage to mitochondrial DNA in primary cultured neurons
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
Lai H et al. (1997): Melatonin and N-tert-butyl-alpha-phenylnitrone block 60-Hz magnetic field-induced DNA single and double strand breaks in rat brain cells