Rats were divided into three groups for behavioral and neurochemical experiments: 1.) sham operated group (n=8), 2.) spinal cord injury group (n=6) and 3.) spinal cord injury + magnetic field exposure group (n=6). The same number and groups of rats were used for the histological experiment.
After the spinal cord injury, rats were exposed or kept without exposure for 8 weeks. Locomotor activity was assessed weekly while nociception was only recorded at the end of the 8 weeks before rats were sacrified wfor histological and neurotransmitter concentration examination.
|Exposure duration||2 h/day for 7 days/week for 8 weeks|
|Chamber||rats were exposed in a non-metal box|
|Setup||box was placed at the center of four coils connected in series to 50 Hz power supply; coils were wound on circular formers at a diameter of 1000 mm; two outer coils were wound with 18 turns each and two inner coils were wound with 8 turns, respectively; coils produced a uniform magnetic field|
Rats with spinal cord injury showed a significantly reduced locomotor activity compared to the sham group. However, locomotor activity was significantly higher in the "spinal cord injury with magnetic field exposure group" than in the group with spinal cord injury alone.
Pain after formalin injection was significantly decreased in rats with spinal cord injury compared to the sham group, while magnetic field exposure in spinal cord injured rats significantly increased the level of pain compared to rats with spinal cord injury alone.
In spinal cord injured rats, the concentration of serotonin was significantly lower in the cortex and in the rest of the brain in comparison to the sham group, while the concentrations of gamma aminobutyric acid and norepinephrine in the brain stem were significantly increased. A magnetic field exposure diminished these effetcs.
Morphological analysis revealed clear lesions in the spinal cord of spinal cord injured rats with and without magnetic field exposure. However, lesion volume was significantly less in the spinal cord injury group with magnetic field exposure.
The authors conclude that the neurotransmitter changes contribute toward the decreased pain in spinal cord injured rats which is restored by long-term exposure to extremely low frequency magnetic fields.