Medical/biological study (experimental study)

Pre-Exposure to 50 Hz Magnetic Fields Modifies Menadione-Induced Genotoxic Effects in Human SH-SY5Y Neuroblastoma Cells med./bio.

By: Luukkonen J, Liimatainen A, Hoyto A, Juutilainen J, Naarala J

Published in: PLoS One 2011; 6 (3): e18021

Aim of study (acc. to author)

To study the extent of chemically induced genetic damage in human SH-SY5Y neuroblastoma cells pre-exposed to 50 Hz magnetic fields.

Background/further details

Two different chemical agents were used for inducing DNA damage (for 3 h following exposure): menadione as a free radical-producing and methyl methanesulfonate as an alkylating agent. Menadione and methyl methanesulfonate were also used for positive controls (but in higher concentrations).

Endpoint

genotoxicity/mutation: DNA damage and DNA repair rate (comet assay and micronuclei formation)

Exposure

- co-exposure

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: continuous for 24 h	magnetic flux density: 100 µT

General information

Cells were exposed in four groups: i) sham exposure ii) MF exposure iii) sham exposure + chemical treatment iv) pre-exposure to MF + chemical treatment chemical treatment either with menadione or with methyl methanesulfonate

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	continuous for 24 h

Exposure setup

Exposure source	Helmholtz coils
Setup	pair of 340 mm x 460 mm Helmholtz coils, 220 mm apart, housed inside a temperature-controlled incubator with 5% CO₂; cells placed in 55 mm plastic Petri dishes or 48 well plates (micronuclei experiments) in the center of the coil system
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	100 µT	-	measured	-	-

Reference articles

Markkanen A et al. (2008): Pre-exposure to 50 Hz magnetic fields modifies menadione-induced DNA damage response in murine L929 cells

Exposed system:

intact cell/cell culture
SH-SY5Y (human neuroblastoma cell line)

Methods Endpoint/measurement parameters/methodology

genotoxicity/mutation: DNA damage and DNA repair rate (0-15 minutes after treatments): comet assay and micronuclei formation
cell viability/cell division/proliferation: realtive survival (double staining method and flow cytometry)

Investigated system:

Time of investigation:

after exposure

Main outcome of study (acc. to author)

Pre-exposure to the magnetic field enhanced the menadione-induced DNA damage, DNA repair rate (reduced level of DNA damage), and micronucleus formation in human SH-SY5Y neuroblastoma cells. Although the findings with methyl methanesulfonate indicated similar effects, the differences were not statistically significant. No effects were found after magnetic field exposure alone.
The authors conclude that the data confirmed their previous findings (Markkanen et al. 2008) showing that pre-exposure to magnetic fields as low as 100 µT altered cellular responses to menadione, and showed that increased genotoxicity results from such interaction.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Ministry of Education, Finland
SYTYKE, Graduate School in Environmental Health, Finland
University of Eastern Finland, Finland

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