Medical/biological study (experimental study)

Tempol suppresses micronuclei formation in astrocytes of newborn rats exposed to 50-Hz, 10-mT electromagnetic fields under bleomycin administration med./bio.

By: Miyakoshi Y, Kajihara C, Shimizu H, Yanagisawa H

Published in: Mutat Res Genet Toxicol Environ Mutagen 2012; 747 (1): 138-141

Aim of study (acc. to author)

To study the mutagenic effects of co-exposure to 50 Hz magnetic fields and bleomycin. Additionally, it was investigated whether the mutagenic effects of magnetic fields were related to reactive oxygen species by using tempol (4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl), a superoxide radical scavenger.

Background/further details

Three-day-old male rats were sham exposed or co-exposed to 50 Hz magnetic fields and bleomycin (5 or 10 mg/kg body weight) in six groups (n=6 rats each): 1) magnetic field exposure, 2) sham exposure, 3) bleomycin (5 mg) + magnetic field co-exposure, 4) bleomycin (5 mg) + sham exposure, 5) bleomycin (10 mg) + magnetic field co-exposure, 6) bleomycin (10 mg) + sham exposure.
Additionally, four groups of rats (n=4 rats each) were treated with tempol: 7) bleomycin (10 mg/kg) + magnetic field exposure + tempol (200 µmol/kg body weight), 8) bleomycin + sham exposure + tempol, 9) bleomycin + magnetic field exposure + physiological saline solution, 10) bleomycin + sham exposure + physiological saline solution.

Endpoint

genotoxicity/mutation: micronuclei formation in astrocytes

Exposure

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: continuous for 72 h	magnetic flux density: 10 mT

General information

Rats were divided into 10 groups: 1) magnetic field exposure 2) sham exposure 3) bleomycin (5 mg/kg body weight) + magnetic field co-exposure 4) bleomycin (5 mg) + sham exposure 5) bleomycin (10 mg) + magnetic field co-exposure 6) bleomycin (10 mg) + sham exposure 7) bleomycin (10 mg/kg body weight) + magnetic field exposure + tempol (200 µmol/kg body weight) 8) bleomycin + sham exposure + tempol 9) bleomycin + magnetic field exposure + physiological saline solution 10) bleomycin + sham exposure + physiological saline solution

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	continuous for 72 h

Exposure setup

Exposure source	coil(s)
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	10 mT	-	-	-	-

Exposed system:

Methods Endpoint/measurement parameters/methodology

genotoxicity/mutation: micronuclei formation in astrocytes (acridine orange staining of GFAP positive cells; fluorescence microscopy)

Investigated system:

intact cell/cell culture

Investigated organ system:

brain/CNS

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The number of micronucleated astrocytes in the "bleomycin (10 mg) + magnetic field exposure group" (group 5) was 1.6 times higher than that in the appropriate sham exposure group (group 6).
The number of micronuclei in astrocytes of group 7 (co-exposure to magnetic field + bleomycin + tempol) was 40% of that in rats administered with the same dose of bleomycin and physiological saline (group 9) and similar to those of the two sham exposure groups (groups 8 and 10).
The data suggest that the mechanism responsible for the elevated frequency of micronuclei in astrocytes of rats co-exposed to bleomycin and magnetic fields is related to reactive oxygen species.

Study character:

medical/biological study
experimental study
full/main study
Short Communication

Study funded by

not stated/no funding

Luukkonen J et al. (2014): Induction of genomic instability, oxidative processes, and mitochondrial activity by 50Hz magnetic fields in human SH-SY5Y neuroblastoma cells
Jin YB et al. (2014): Absence of DNA damage after 60-Hz electromagnetic field exposure combined with ionizing radiation, hydrogen peroxide, or c-Myc overexpression
Rageh MM et al. (2012): Assessment of genotoxic and cytotoxic hazards in brain and bone marrow cells of newborn rats exposed to extremely low-frequency magnetic field
Jin YB et al. (2012): Effects on micronuclei formation of 60-Hz electromagnetic field exposure with ionizing radiation, hydrogen peroxide, or c-Myc overexpression
Luukkonen J et al. (2011): Pre-Exposure to 50 Hz Magnetic Fields Modifies Menadione-Induced Genotoxic Effects in Human SH-SY5Y Neuroblastoma Cells
Okudan N et al. (2010): Effects of long-term 50 Hz magnetic field exposure on the micro nucleated polychromatic erythrocyte and blood lymphocyte frequency and argyrophilic nucleolar organizer regions in lymphocytes of mice
Reddy SB et al. (2010): Micronuclei in the blood and bone marrow cells of mice exposed to specific complex time-varying pulsed magnetic fields
Vijayalaxmi et al. (2009): Genetic damage in mammalian somatic cells exposed to extremely low frequency electro-magnetic fields: a meta-analysis of data from 87 publications (1990-2007)
Cho YH et al. (2007): Effects of extremely low-frequency electromagnetic fields on delayed chromosomal instability induced by bleomycin in normal human fibroblast cells
Erdal N et al. (2007): Cytogenetic effects of extremely low frequency magnetic field on Wistar rat bone marrow
Simko M (2007): Cell type specific redox status is responsible for diverse electromagnetic field effects
Udroiu I et al. (2006): Clastogenicity and aneuploidy in newborn and adult mice exposed to 50 Hz magnetic fields
Ding GR et al. (2003): Induction of kinetochore-positive and kinetochore-negative micronuclei in CHO cells by ELF magnetic fields and/or X-rays
Cho YH et al. (2003): The effect of extremely low frequency electromagnetic fields (ELF-EMF) on the frequency of micronuclei and sister chromatid exchange in human lymphocytes induced by benzo(a)pyrene
Zeni O et al. (2001): Combined exposure to extremely low frequency (ELF) magnetic fields and chemical mutagens: Lack of genotoxic effects in human lymphocytes
McCann J et al. (1998): The genotoxic potential of electric and magnetic fields: an update
McCann J et al. (1993): A critical review of the genotoxic potential of electric and magnetic fields