Attenuation of Spinal Cord Injury-Induced Astroglial and Microglial Activation by Repetitive Transcranial Magnetic Stimulation in Rats

Abstract

Spinal cord injury (SCI) causes not only loss of sensory and motor function below the level of injury but also chronic pain, which is difficult and challenging of the treatment. Repetitive transcranial magnetic stimulation (rTMS) to the motor cortex, of non-invasive therapeutic methods, has the motor and sensory consequences and modulates pain in SCI-patients. In the present study, we studied the effectiveness of rTMS and the relationship between the modulation of pain and the changes of neuroglial expression in the spinal cord using a rat SCI-induced pain model. Elevated expressions of Iba1 and GFAP, specific microglial and astrocyte markers, was respectively observed in dorsal and ventral horns at the L4 and L5 levels in SCI rats. But in SCI rats treated with 25 Hz rTMS for 8 weeks, these expressions were significantly reduced by about 30%. Our finding suggests that this attenuation of activation by rTMS is related to pain modulation after SCI. Therefore, rTMS might provide an alternative means of attenuating neuropathic pain below the level of SCI.

Enhancement of Neural Stem Cell Proliferation in Rats with Spinal Cord Injury by a Combination of Repetitive Transcranial Magnetic Stimulation (rTMS) and Human Umbilical Cord Blood Mesenchymal Stem Cells (hUCB-MSCs)

“…Rats were pre-anesthetized and SCI was induced by laminectomy at T10 using a modification of the Allen method [ 14 , 15 ]. Rats were injected intramuscularly with prophylactic kanamycin (1 mg/kg) once daily and underwent bladder evacuation every other day [ 16 ]. All animal experiments were performed in accordance with institutional guidelines, following a protocol approved by the Ethics Committees of the First Affiliated Hospital of Zhengzhou University, Henan, China.…”

Blocking of BDNF-TrkB signaling inhibits the promotion effect of neurological function recovery after treadmill training in rats with spinal cord injury

“…After 7 days of intrathecal catheter, all rats were administered analgesic and anesthesia as above. The New York University (NYU) Impactor System is the modified Allen's method that was employed to establish a T10 incomplete SCI model by dropping a device rod (10 g) from a vertical distance of 2.5 cm onto the exposed spinal cord [15,18]. The Sham group only exposed the T10 spinal cord.…”

How Does Transcranial Magnetic Stimulation Influence Glial Cells in the Central Nervous System?

“…rTMS has also been shown to induce a transient increase in GFAP expression in vivo , when treatment was applied following ischemic injury (continuous 50 Hz, 0.5 mT exposure for 7 days; Rauš et al, 2013 ) or to a demyelinated lesion (1 Hz for 5 min per day for 14 days; Fang et al, 2010 ). By contrast, rTMS was found to attenuate astrocyte activation at the site of spinal cord (SC) injury in rats (25 Hz, 3 s on/off for 20 min, 5 days a week for 8 weeks; Kim et al, 2013 ). Furthermore rTMS (six trains of 300 pulses daily for 18 days, 20 Hz) did not alter GFAP expression in the dentate gyrus of rats experiencing chronic stress (Czéh et al, 2002 ), or alter the number of GFAP-positive cells in the motor cortex or hippocampus of normal, healthy rats (1000 pulses per day for 5 days at 1 Hz; Liebetanz et al, 2003 ).…”

“…However the application of very low intensity, but high frequency rTMS following an ischemic injury, or the induction of demyelination, appears to activate microglia, leading to increased Iba1 expression (Fang et al, 2010 ; Rauš et al, 2013 ). In contrast, high intensity, high frequency rTMS applied to the injured SC, reportedly attenuates microglial activation (Kim et al, 2013 ). While it is not possible to gauge the effect of TMS on microglia from such a small number of studies, TMS would be expected to affect microglial behavior.…”