Medical/biological study (experimental study)

Exposure to extremely low frequency magnetic fields induces fos-related antigen-immunoreactivity via activation of dopaminergic D1 receptor med./bio.

By: Shin EJ, Nguyen XK, Nguyen TT, Pham DT, Kim HC

Published in: Exp Neurobiol 2011; 20 (3): 130-136

Aim of study (acc. to author)

To investigate whether exposure to extremely low frequency magnetic fields induces Fos-related antigen (FRA) immunoreactivity in the brain of mice and influences the locomotor activity.

Background/further details

Seven groups of mice were examined (n=30 per group): 1.) no exposure + saline injection (control group), 2.) exposure at 0.3 mT + saline injection, 3.) exposure at 2.4 mT + saline injection, 4.) exposure at 2.4 mT + injection of 0.03 mg SCH (SCH23390 hydrochloride, a dopaminergic D1 receptor antagonist) per kg body weight, 5.) exposure at 2.4 mT + injection of 0.1 mg SCH per kg body weight, 6.) exposure at 2.4 mT + injection of 10 mg Sulp (sulpiride, a dopaminergic D2 receptor antagonist) per kg body weight and 7.) exposure at 2.4 mT + injection of 20 mg Sulp per kg body weight.
The solutions of saline, SCH and Sulp were injected 30 minutes prior to the daily exposure for 14 days. Locomotor behavior was tested directly, 1 day, 1 week, 3 month and 1 year after the exposure period (6 rats per group and point of time, resepectively). Animals were killed for immunohistochemical analyses 90 minutes after measurement of the locomotor activity.

Endpoint

effects on the neurological system: Fos-related antigen immunoreactivity
cognitive/behavioral endpoints: locomotor activity

Exposure

Exposure	Parameters
Exposure 1: 60 Hz Exposure duration: 1 h/day for 14 days	magnetic flux density: 0.3 mT magnetic flux density: 2.4 mT

General information

animals were treated with SCH23390 hydrochloride or sulpiride 30 min before exposure

Exposure 1

Main characteristics

Frequency	60 Hz
Type	magnetic field
Exposure duration	1 h/day for 14 days

Exposure setup

Exposure source	Helmholtz coils
Setup	three Helmholtz coils set parallel to each other in a wooden frame

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	0.3 mT	-	-	-	-
magnetic flux density	2.4 mT	-	-	-	-

Reference articles

Shin EJ et al. (2007): Exposure to extremely low frequency magnetic fields enhances locomotor activity via activation of dopamine D1-like receptors in mice
Lee BC et al. (2001): Prenatal exposure to magnetic field increases dopamine levels in the striatum of offspring

Exposed system:

animal
mouse/C57BL/6
whole body

Methods Endpoint/measurement parameters/methodology

effects on the neurological system: protein expression of Fos related antigen (immunoreactivity, microscopy)
cognitive/behavioral endpoints: locomotor activity (distance traveled was analyzed for 30 min, automated video-tracking system )

Investigated system:

tissue slices
striatum, nucleus accumbens (striatal complex)
investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

after exposure

Main outcome of study (acc. to author)

In the exposure groups (group 2 + 3), the locomotor activity was significantly increased in a field intensity-dependent manner directly and 1 day after the exposure period (with 2.4 mT also after 1 week) in comparison to the control group, but returned near the level of the control group after 3 month. An administration of SCH (group 4 + 5), but not Sulp (group 6 + 7) reduced the locomotor activity significantly compared to the exposure group with saline injection (group 3).
In the striatum and the nucleus accumbens of all exposed mice, the Fos-related antigen immunoreactivity was significantly increased in a field intensity-dependent manner compared to the control group. The highest levels were found directly after the exposure period. They decreased continuously over the year but remained significantly higher than those of the control group. An injection of SCH, but not Sulp significantly lowered the immunoreactivity of the Fos-related antigen compared to the 2.4 mT exposure group with saline injection, however the values remained significantly higher when compared to the control group.
The results indicate that exposure to extremely low frequency magnetic fields induces Fos-related antigen immunoreactivity in the brain of mice and increases the locomotor activity via stimulation of a dopaminergic D1 receptor.

Study character:

medical/biological study
experimental study
full/main study
blind study

Study funded by

BrainKorea21 (BK 21) Project, Korea Research Foundation, Korea
Kangwon National University, Korea
Ministry of Science and Technology (MOST), Korea

Salunke BP et al. (2014): Experimental evidence for involvement of nitric oxide in low frequency magnetic field induced obsessive compulsive disorder-like behavior
Janac B et al. (2012): Temporal patterns of extremely low frequency magnetic field-induced motor behavior changes in Mongolian gerbils of different age
Cui Y et al. (2012): Deficits in water maze performance and oxidative stress in the hippocampus and striatum induced by extremely low frequency magnetic field exposure
Korpinar MA et al. (2012): The 50 Hz (10 mT) sinusoidal magnetic field: effects on stress-related behavior of rats
Strasak L et al. (2009): Effects of ELF-EMF on brain proteins in mice
Balassa T et al. (2009): Effect of short-term 50 Hz electromagnetic field exposure on the behavior of rats
Fu Y et al. (2008): Long-term exposure to extremely low-frequency magnetic fields impairs spatial recognition memory in mice
Shin EJ et al. (2007): Exposure to extremely low frequency magnetic fields enhances locomotor activity via activation of dopamine D1-like receptors in mice
Prolic Z et al. (2005): The effect of extremely low-frequency magnetic field on motor activity of rats in the open field
Lee BC et al. (2001): Prenatal exposure to magnetic field increases dopamine levels in the striatum of offspring