Study type: Medical/biological study (experimental study)

Enhanced NOR-1 gene expression by exposure of Chinese hamster cells to high-density 50 Hz magnetic fields med./bio.

By: Miyakoshi J, Tsukada T, Tachiiri S, Bandoh S, Yamaguchi K, Takebe H
Published in: Mol Cell Biochem 1998; 181 (1-2): 191-195
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Aim of study (acc. to author)

To investigate the effects on gene expression of CHO cells exposed to extremely low frequency magnetic fields in vitro.

Background/further details

The gene expression of neuron derived orphan receptor (NOR-1) which is suspected to control cell growth and differentiation was observed.
The experiments were repeated twice (5 mT, 50 Hz) or three times (400 mT, 50 Hz).
The exposed cells additionally were treated with forskolin, tetradecanoylphorbol acetate, protein kinase C-inhibitors (calphostin C, crocetin) and calcium channel blockers (nifedipine, dantrolen) in order to examine the effects of these chemical substances in exposed cells.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 1, 3, 6, 12, 24 and 36 h
Exposure 2: 50 Hz
Exposure duration: continuous for 1, 3, 6, 12, 24 and 36 h

General information

4 plates were used for each experiment; the experiment was repeated 2 or 3 times.

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Exposure duration continuous for 1, 3, 6, 12, 24 and 36 h
Additional info The magnetic field was oriented vertically.
Exposure setup
Exposure source
  • a pair of magnetic cores, 240 x 340 mm, 40 mm apart, made of silicon steel plates
Chamber An acrylic CO2 incubator was installed between the space provided by the magnetic cores.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 400 mT unspecified unspecified - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Exposure duration continuous for 1, 3, 6, 12, 24 and 36 h
Additional info The magnetic field was oriented vertically.
Exposure setup
Exposure source
Chamber CO2 incubator with a built-in magnet generator using two Helmholtz coils
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 5 mT unspecified unspecified - -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

Enhanced gene expression of NOR-1 was observed by exposure of CHO cells to an extremely low frequency magnetic field of 50 Hz at 400 mT, but not at 5 mT. The enhanced gene expression, reaching the maximum after 6 hours exposure, was transient and reduced to the control level after exposure to 400 mT extremely low frequency magnetic field for 24 hours.
The NOR-1 expression induced by treatment with forskolin and tetradecanoylphorbol acetate was further enhanced by the simultaneous treatment with 400 mT extremely low frequency magnetic field, in which the maximum response was at 3 hours exposure.
When cells were treated with an inhibitor of the protein kinase C and calcium channel blockers during the 400 mT extremely low frequency magnetic field exposure, the enhanced NOR-1 gene expression was not observed.

Study character:

Study funded by

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