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Medical/biological study (experimental study)

Extremely low-frequency magnetic fields modulate nitric oxide signaling in rat brain.

Published in: Bioelectromagnetics 2012; 33 (7): 568-574

Aim of study (acc. to author)

The study was designed to confirm that an extremely low frequency magnetic field affects neuronal nitric oxide synthase (nNOS) in several brain regions and to investigate the correlation between nitric oxide and nNOS activation.
Background/further details: A previous study showed that an extremely low frequency magnetic field induces nitric oxide synthesis by Ca2+-dependent NO synthase in the rat brain (Jeong et al. 2006). In the central nervous system, nitric oxide derived from nNOS acts as a neuromodulator or neurotransmitter for the regulation of synaptic plasticity, the sleep-wake cycle and hormone secretion.
10 rats were exposed and 10 rats were sham exposed.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 60 Hz
Exposure duration: continuous for 5 days
Exposure 1
Main characteristics
Frequency 60 Hz
Type
Exposure duration continuous for 5 days
Exposure setup
Exposure source
Setup pair of Helmholtz coils, consisting of 200 turns of insulated copper wire with a diameter of 1 mm, wound on a 140 cm x 85 cm x 70 cm rectangular wooden frame; each winding was split; maximum magnetic field in the center of the coil system; non-magnetic cage placed in the center
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 2 mT effective value measured - at the center of the cage
magnetic flux density 1.8 mT effective value measured - at the corner of the cage
Additional parameter details
ambient horizontal field: B =18 µT ambient vertical field: B = 22 µT total ambient field: B = 23 µT ambient AC field: B < 2 µT
Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The exposure of the rats to the magnetic field for 5 days resulted in significant increases of the nitric oxide level in the cerebral cortex, striatum, and hippocampus and in a significant elevation of the cGMP level in the striatum in comparison to the control group. There were no significant differences in the morphology and number of neurons in the cerebral cortex, striatum, and hippocampus. However, the number of nNOS-immunoreactive neurons were significantly increased in those cerebral areas in exposed rats.
These data suggest that the increase in nitric oxide could be due to the increased expression and activation of nNOS. In conclusion, the extremely low frequency magnetic field exposure was able to increase the nitric oxide production via nNOS activation in the brain of the rats.
Study character:

Study funded by

  • Ministry of Education, Science and Technology (MEST), Korea
  • National Research Foundation (NRF) of Korea

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