Study type: Medical/biological study (experimental study)

The effects of long-term exposure to extremely low-frequency magnetic fields on bone formation in ovariectomized rats med./bio.

Published in: Bioelectromagnetics 2012; 33 (7): 543-549

Aim of study (acc. to author)

To study the effects of 50 Hz extremely low frequency magnetic fields on rat bone metabolism.

Background/further details

60 rats were divided into four different groups (each group n=15): 1) unexposed control group; 2) ovariectomized only; 3) non-ovariectomized, exposed; and 4) ovariectomized, exposed. Bilateral ovariectomies were performed four days before the beginning of the experiments.



Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 4 h/day during 6 months, starting on the fifth day after surgery

General information

rats were divided into the following four groups: i) control ii) ovariectomized iii) non-ovariectomized + EMF exposure iv) ovaiectomized + EMF exposure

Exposure 1

Main characteristics
Frequency 50 Hz
Exposure duration continuous for 4 h/day during 6 months, starting on the fifth day after surgery
Exposure setup
Exposure source
Setup two pairs of Helmholtz coils with a diameter of 70 cm, each consisting of 125 turns of insulated copper wire with a diameter of 1.5 mm; coils placed vertically facing each other at a distance of 47 cm; methacrylate cages (43 cm x 42 cm x 15 cm) placed between the coils; rats could move freely inside the cage; exposure system placed inside a 130 cm x 65 cm x 80 cm Faraday cage
Sham exposure A sham exposure was conducted.
Measurand Value Type Method Mass Remarks
magnetic flux density 1.5 mT - measured - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • before exposure
  • after exposure

Main outcome of study (acc. to author)

Although there was no significant difference in bone mineral density values among the groups before magnetic field exposure, the bone mineral density values increased significantly after six months in the groups 3 (non-ovariectomized, exposed) and 4 (ovariectomized, exposed) and were reduced in group 2 (ovariectomized only) compared to the control group. The concentrations of bone-specific alkaline phosphatase, osteocalcin, and osteoprotogerin in the three groups also changed in a significant way compared to the control group (increase in the exposed groups 3 and 4 indicating increased osteoblast growth and activity and decrease in group 2). The N-telopeptide level decreased in the exposed groups 3 and 4 (indicating a decrease in osteoclast activity) and increased in group 2 compared with the control group.
The data suggest that osteoporosis can be inhibited by extremely low frequency magnetic fields treatments. Extremely low frequency magnetic fields may be useful in the prevention of osteoporosis in ovariectomized rats.

Study character:

Study funded by

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