Study type: Medical/biological study (experimental study)

Induction of micronuclei and superoxide production in neuroblastoma and glioma cell lines exposed to weak 50 Hz magnetic fields med./bio.

By: Kesari KK, Juutilainen J, Luukkonen J, Naarala J
Published in: J R Soc Interface 2016; 13 (114): 13-
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Aim of study (acc. to author)

The effects of co-exposure of human neuroblastoma and rat glioma cells to a 50 Hz magnetic field and menadione on DNA damage and oxidative stress should be investigated.

Background/further details

The administration of menadione for co-exposure was based on previous findings indicating that exposure to magnetic fields alters cellular responses to menadione (Markkanen et al. 2008, Luukkonen et al. 2011). Menadione leads to the prodution of superoxide anions and DNA damage.
Neuroblastoma cells were treated with 0, 1, 5, 10 and 20 µM and glioma cells were treated with 0, 1, 5, 10, 15, 20 and 50 µM menadione and were either not exposed to the magnetic field (control groups), sham exposed or exposed to a 10 or 30 µT magnetic field.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 24 hours
Exposure 2: 50 Hz
Exposure duration: continuous for 24 hours

General information

menadione was administered after exposure to the magnetic field and cells were incubated for 3 hours afterwards

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Exposure duration continuous for 24 hours
Exposure setup
Exposure source
Chamber cell culture dishes in coil system in incubator (temperature-controlled and 5% CO2)
Setup horizontal magnetic field was generated by a pair of coils (34 cm x 46 cm) in a Helmholtz-type configuration (22 cm distance between the coils); cell culture dishes were placed at the center of the coil system, where the magnetic field was homogeneous
Sham exposure A sham exposure was conducted.
Additional info control cells were incubated in an identical incubator as exposed and sham exposed cells
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 10 µT - measured - -
Additional parameter details

there were varying background AC magnetic field levels inside the incubators due to the on-off cycle of the heating system; there were also minor differences between the four locations used for cell cultures; the maximum (short peak value in the location with the highest field when heating was switched on by the thermostat) was 2.35 µT in the control incubator and 1.83 µT in the exposure incubator; the minimum values (heater off) were about 0.01 µT in both incubators; the predominant direction of the background AC magnetic field was horizontal, from front to back of the incubator (perpendicular to the experimental 50 Hz field); the static magnetic field in the incubators was almost vertical with 29.5 µT in the control incubator and 27.5 µT in the exposure incubator

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Exposure duration continuous for 24 hours
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 30 µT - measured - -

Reference articles

  • Luukkonen J et al. (2014): Induction of genomic instability, oxidative processes, and mitochondrial activity by 50Hz magnetic fields in human SH-SY5Y neuroblastoma cells
  • Markkanen A et al. (2008): Pre-exposure to 50 Hz magnetic fields modifies menadione-induced DNA damage response in murine L929 cells

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Sham exposure did not show any significant effects in any parameter compared to the control groups in both cell lines.
Micronuclei formation was significantly increased in neuroblastoma cells exposed to the 30 µT magnetic field compared to the control group. It was most pronounced in cells co-exposed to the highest concentration of menadione (20 µM) and a significant interaction of menadione and the magnetic field exposure was detected. That means, that the effect of the magnetic field was dependent on the presence and amount of menadione. In C6 cells, the magnetic field had no significant effect on micronuclei formation compared to the control groups.
Cytosolic and mitochondrial superoxide production were significantly increased only in C6 cells exposed to 10 µT or 30 µT magnetic fields compared to the control groups. No interactions of the magnetic field and menadione were observed.
Cell viability was not affected significantly by the magnetic field or co-exposure to the magnetic field and menadione.
The authors conclude that exposure to a 50 Hz magnetic field might provoke DNA damage in human neuroblastoma cells and oxidative stress in rat glioma cells. In the genotoxic effects, the magnetic field enhanced the effcts of menadione in a co-exposure, while the effects on oxidative stress were independent of co-exposure.

Study character:

Study funded by

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