Inhibition of astrocytes in the spinal cord by repetitive transcranial magnetic stimulation for relieving neuropathic pain / 中华物理医学与康复杂志

ABSTRACT

Objective To observe the effects of repeated low and high-frequency transcranial magnetic stimulation (rTMS) on neuropathic pain and the expression of specific activation markers of astrocytes and glial fibrillary acidic protein (GFAP) in the lumbar spinal cord.Methods Twenty-eight male Sprague-Dawley rats were randomly divided into a sham-operated group,a sham-rTMS group,a 1 Hz group and a 20 Hz group,with 7 in each group.The rats in the sham-operated group had their sciatic nerve exposed without ligation,while the other groups underwent sciatic nerve ligation to induce neuropathic pain.Three days after the operation,rTMS was applied to the primary motor cortex (M1) contralateral to the pain once a day for 10 consecutive days.Pain-related behavior and thermal pain response were tested before the operation and before and after the course of rTMS therapy.The expression of GFAP in the lumbar spinal cord was examined.Results All of the rats which underwent sciatic nerve ligation showed pain-related behavior and significantly decreasing thermal pain latency compared with the sham-operated group.After the rTMS therapy the thermal hyperalgia was significantly attenuated in the 20 Hz group but not in the 1 Hz group compared with the sham-rTMS group.The expression of GFAP in the dorsal horn of the lumbar spinal cord ipsilateral to the neuropathic pain was significantly increased in the sham-rTMS group and the 1 Hz group compared with the sham-operated group.Compared with the sham-rTMS group,GFAP levels were significantly lower in the 20 Hz group but not in the 1 Hz group.The pain relief in the 20 Hz group was negatively related to the expression of GFAP.Conclusions Neuropathic pain induced by peripheral nerve injury is associated with increased activity and proliferation of astrocytes in the dorsal horns of the spinal cord.High-frequency rTMS can relieve neuropathic pain through inhibiting the activity and proliferation of astrocytes in the dorsal horns,but low-frequency rTMS has no clinically significant effect.