Mechanism of GABA receptors involved in spasticity inhibition induced by transcranial magnetic stimulation following spinal cord injury.

The effect of high-frequency repetitive transcranial magnetic stimulation (rTMS) on spasticity following spinal cord injury (SCI) and the action mechanism were investigated. SCI models were established in Sprague-Dawley rats. Five groups were set up: normal control group, SCI-7 day (7D) model group, SCI-14D model group, SCI-7D rTMS group and SCI-14D rTMS group (n=10 each). The rats in SCI rTMS groups were treated with 10 Hz rTMS at 8th day and 15th day after SCI respectively. Motor recovery and spasticity alleviation were evaluated by BBB scale once a week till the end of treatment. Finally, different parts of tissues were dissected out for detection of GABA receptors using Western blotting and polymerase chain reaction (PCR) technique. The results showed that the BBB scores after treatment were significantly higher in SCI-7D rTMS group than in SCI-14D rTMS group (P<0.05). The GABA receptors were down-regulated more significantly in SCI-14D model group than in SCI-7D model group (P<0.05). At different time points, rTMS treatment could affect the up-regulation of GABA receptors: The up-regulation of GABA receptors was more obvious in SCI-7D rTMS group than in SCI-14D rTMS treatment group (P<0.05). It was concluded that 10-Hz rTMS could alleviate spasticity following SCI and promote the motor recovery in rats, which might be attributed to the up-regulation of GABA receptors. It was also suggested that early high-frequency rTMS treatment after SCI may achieve more satisfactory curative effectiveness.