Medical/biological Study (experimental study)

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

PubMed Entry

Journal web site

Aim of study (according 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

• effects on the neurological system: nitric oxide signaling in the brain

Exposure
General category: magnetic field, low frequency field, 50/60 Hz (AC)

Field characteristics	Parameters
60 Hz exposure duration: continuous for 5 days	magnetic flux density: 2 mT effective value (at the center of the cage) magnetic flux density: 1.8 mT effective value (at the corner of the cage)

Exposed system:
animal (species/strain): rat/Sprague-Dawley
whole body exposure

Methods
Endpoint/Measurement parameters/Methodology

• effects on the neurological system: nitric oxide levels in the cortex, striatum, hippocampus (spectrophotometry), intracellular cyclic guanosine monophosphate (cGMP) activation (cGMP levels in the cortex, striatum, hippocampus; ELISA); morphological assessment of nuclear and mitochondrial damage in hippocampus, cell loss and morphology of the cerebral cortex, striatum and hippocampus (cresyl violet staining, electron microscopy); number of nNOS-immunoreactive neurons in the cortex, striatum, hippocampus (immunohistochemistry and densitometry);

Main outcome of study (according 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: medical/biological study, experimental study, full/main study)

Study funded by

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

• Coskun S et al. (2009): Effects of continuous and intermittent magnetic fields on oxidative parameters...
• Akdag Z et al. (2007): Alteration of nitric oxide production in rats exposed to a prolonged, extremely...
• Jelenkovic A et al. (2006): Effects of extremely low-frequency magnetic field in the brain of rats.
• Jeong JH et al. (2006): Extremely low frequency magnetic field induces hyperalgesia in mice modulated...
• Noda Y et al. (2000): Pulsed magnetic fields enhance nitric oxide synthase activity in rat...
• Bawin SM et al. (1996): Extremely-low-frequency magnetic fields disrupt rhythmic slow activity in rat...