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

Effects of non-invasive brain stimulation on motor function after spinal cord injury: a systematic review and meta-analysis

BACKGROUND

In recent years, non-invasive brain stimulation (NIBS) has been used for motor function recovery. However, the effects of NIBS in populations with spinal cord injury (SCI) remain unclear. This study aims to conduct a meta-analysis of the existing evidence on the effects and safety of NIBS against sham groups for motor dysfunction after SCI to provide a reference for clinical decision-making.

METHODS

Two investigators systematically screened English articles from PubMed, MEDLINE, Embase, and Cochrane Library for prospective randomized controlled trials regarding the effects of NIBS in motor function recovery after SCI. Studies with at least three sessions of NIBS were included. We assessed the methodological quality of the selected studies using the evidence-based Cochrane Collaboration's tool. A meta-analysis was performed by pooling the standardized mean difference (SMD) with 95% confidence intervals (CI).

RESULTS

A total of 14 randomized control trials involving 225 participants were included. Nine studies used repetitive transcranial magnetic stimulation (rTMS) and five studies used transcranial direct current stimulation (tDCS). The meta-analysis showed that NIBS could improve the lower extremity strength (SMD = 0.58, 95% CI = 0.02-1.14, P = 0.004), balance (SMD = 0.64, 95% CI = 0.05-1.24, P = 0.03), and decrease the spasticity (SMD = - 0.64, 95% CI = - 1.20 to - 0.03, P = 0.04). However, the motor ability of the upper extremity in the NIBS groups was not statistically significant compared with those in the control groups (upper-extremity strength: P = 0.97; function: P = 0.56; and spasticity: P = 0.12). The functional mobility in the NIBS groups did not reach statistical significance when compared with the sham NIBS groups (sham groups). Only one patient reported seizures that occurred during stimulation, and no other types of serious adverse events were reported.

CONCLUSION

NIBS appears to positively affect the motor function of the lower extremities in SCI patients, despite the marginal P-value and the high heterogeneity. Further high-quality clinical trials are needed to support or refute the use and optimize the stimulation parameters of NIBS in clinical practice.

Effects of repetitive magnetic stimulation on motor function and GAP43 and 5-HT expression in rats with spinal cord injury

Objectives

Spinal cord injury (SCI) is a disabling central nervous system disorder. This study aimed to explore the effects of repetitive trans-spinal magnetic stimulation (rTSMS) of different spinal cord segments on movement function and growth-associated protein-43 (GAP43) and 5-hydroxytryptamine (5-HT) expression in rats after acute SCI and to preliminarily discuss the optimal rTSMS treatment site to provide a theoretical foundation and experimental evidence for clinical application of rTSMS in SCI.

Methods

A rat T10 laminectomy SCI model produced by transient application of an aneurysm clip was used in the study. The rats were divided into group A (sham surgery), group B (acute SCI without stimulation), group C (T6 segment stimulation), group D (T10 segment stimulation), and group E (L2 segment stimulation).

Results

In vivo magnetic stimulation protected motor function, alleviated myelin sheath damage, decreased NgR and Nogo-A expression levels, increased GAP43 and 5-HT expression levels, and inhibited terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells and apoptosis-related protein expression in rats at 8 weeks after the surgery.

Conclusions

This study suggests that rTSMS can promote GAP43 and 5-HT expression and axonal regeneration in the spinal cord, which is beneficial to motor function recovery after acute SCI.

Effects of high frequency repetitive transcranial magnetic stimulation on KCC2 expression in rats with spasticity following spinal cord injury

The effect of high-frequency repetitive transcranial magnetic stimulation (rTMS) on potassium- chloride cotransporter-2 (KCC2) protein expression following spinal cord injury (SCI) and the action mechanism were investigated. SCI models were established in SD rats. Five groups were set up randomly: normal control group, SCI 7-day (7D) model group, SCI 14-day (14D) model group, SCI-7D rTMS group and SCI-14D rTMS group (n=5 each). The rats in SCI rTMS groups were treated with 10 Hz rTMS from 8th day and 15th day after SCI respectively, once every day, 5 days every week, a total of 4 weeks. After the model establishment, motor recovery and spasticity alleviation were evaluated with BBB scale once a week till the end of treatment. Finally, different parts of tissues were dissected out for detection of variations of KCC2 protein using Western blotting and polymerase chain reaction (PCR) technique. The results showed that the BBS scores after treatment were significantly higher in SCI-7D rTMS group than in SCI-14D rTMS group (P<0.05). As compared with normal control groups, The KCC2 protein in SCI model groups was down-regulated after SCI, and the decrease was much more significant in SCI-14D model group than in SCI-7D group (P<0.05). As compared with SCI model groups, KCC2 protein in rTMS groups was up-regulated after the treatment (P<0.05). The up-regulation of KCC2 protein content and expression was more obvious in SCI-7D rTMS group than in SCI-14D rTMS group (P<0.05). It was concluded that 10 Hz rTMS can alleviate spasticity in rats with SCI, which might be attributed to the up-regulation of KCC2 protein. It was also suggested that the high-frequency rTMS treatment after SCI at early stage might achieve more satisfactory curative effectiveness.

Stereotactic injection of shrna GSK-3β-AAV promotes axonal regeneration after spinal cord injury

Evidence suggested that glycogen synthase kinase-3β (GSK-3β) is involved in Nogo-66 inhibiting axonal regeneration in vitro, but its effect in vivo was poorly understood. We showed that stereotactic injection of shRNA GSK-3β-adeno associated virus (GSK-3β-AAV) diminished syringomyelia and promoted axonal regeneration after spinal cord injury (SCI), using stereotactic injection of shRNA GSK-3β-AAV (tested with Western blotting and RT-PCR) into the sensorimotor cortex of rats with SCI and by the detection of biotin dextran amine (BDA)-labeled axonal regeneration. We also determined the right position to inject into the sensorimotor cortex. Our findings consolidate the hypothesis that downregulation of GSK-3β promotes axonal regeneration after SCI.