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

Abstract

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.

Keywords

spinal cord injury / spasticity / repetitive transcranial magnetic stimulation / potassium-chloride cotransporter-2

References

[1] AdamsMM, HicksAL. Spasticity after spinal cord injury. Spinal Cord, 2005, 43(10): 577-586 PMID: 15838527

[2] ElbasiounySM, MorozD, BakrMM, et al. . Management of spasticity after spinal cord injury: current techniques and future directions. Neurorehabil Neural Repair, 2010, 24(1): 23-33 PMID: 19723923

[3] KumruH, BenitoJ, MurilloN, et al. . Effects of high-frequency repetitive transcranial magnetic stimulation on motor and gait improvement in incomplete spinal cord injury patients. Neurorehabil Neural Repair, 2013, 27(5): 421-429 PMID: 23322551

[4] BenitoJ, KumruH, MurilloN, et al. . Motor and gait improvement in patients with incomplete spinal cord injury induced by high-frequency repetitive transcranial magnetic stimulation. Top Spinal Cord Inj Rehabil, 2012, 18(2): 106-112 PMID: 23459246

[5] RoyFD, ZewdieET, GorassiniMA, et al. . Short-interval intracortical inhibition with incomplete spinal cord injury. Clin Neurophysiol, 2011, 122(7): 1387-1395 PMID: 21295518

[6] SaturnoE, BonatoC, MiniussiC, et al. . Motor cortex changes in spinal cord injury: a TMS study. Neurol Research, 2008, 30(10): 1084-1085

[7] GaoW, YuLG, LiuYL, et al. . Mechanism of GABA receptors involved in spasticity inhibition induced by transcranial magnetic stimulation following spinal cord injury. J Huazhong Univ Sci Technol Med Sci, 2015, 35(2): 241-245 PMID: 25877359

[8] KoflerM, PoustkaK, SaltuariL. Intrathecal baclofen for autonomic instability due to spinal cord injury. Auton Neurosci, 2009, 146(1): 106-110 PMID: 19157992

[9] KahleKT, StaleyKJ, NahedBV, et al. . Roles of the cation-chloride cotransporters in neurological disease. Nat Clin Pract Neurol, 2008, 4(9): 490-503 PMID: 18769373

[10] RiveraC, VoipioJ, PayneJA, et al. . The K+/Clco-transporter KCC2 renders GABA hyperpolarizing during neuronal maturation. Nature, 1999, 397(6716): 251-255 PMID: 9930699

[11] PoirrierAL, NyssenY, ScholtesF, et al. . Repetitive transcranial magnetic stimulation improves open field locomotor recovery after low but not high thoracic spinal cord compression-injury in adult rats. J Neurosci Res, 2004, 75(2): 253-261 PMID: 14705146

[12] BoulenguezP, LiabeufS, BosR, et al. . Down-regulation of the potassium-chloride cotransporter KCC2 contributes to spasticity after spinal cord injury. Nat Med, 2010, 16(3): 302-307 PMID: 20190766

[13] BoyceVS, JihyeP, GageFH, et al. . Differential effects of brain-derived neurotrophic factor and neurotrophin-3 on hindlimb function in paraplegic rats. Eur J Neurosci, 2012, 35(2): 221-232 PMID: 22211901 PMCID: 3509221

[14] BoyceVS, TumoloM, FischerI, et al. . Neurotrophic factors promote and enhance locomotor recovery in untrained spinalized cats. J Neurophysiol, 2007, 98(4): 1988-1996 PMID: 17652412

[15] LuP, BleschA, GrahamL, et al. . Motor axonal regeneration after partial and complete spinal cord transection. J Neurosci, 2012, 32(24): 8208-8218 PMID: 22699902 PMCID: 3407545

[16] WangHY, CrupiD, LiuJ, et al. . Repetitive transcranial magnetic stimulation enhances BDNF–TrkB signaling in both brain and lymphocyte. J Neurosci, 2011, 31(30): 11044-11054 PMID: 21795553 PMCID: 3161730

[17] ShulgaA, Thomas-CrusellsJ, SiglT, et al. . Posttraumatic GABA(A)-mediated [Ca2+]i increase is essential for the induction of brain-derived neurotrophic factor-dependent survival of mature central neurons. J Neurosci, 2008, 28(27): 6996-7005 PMID: 18596173