早期运动训练对脊髓损伤大鼠痛觉阈值及脊髓后角胶质细胞活化的影响

Effects of early exercise training on pain threshold and activation of glial cells in spinal dorsal horn in rats with spinal cord injury

目的:观察早期运动训练对T10不完全性SCI大鼠机械性及热刺激痛觉阈值、脊髓后角小胶质细胞和星形胶质细胞活化的影响。方法:将24只成年雌性SD大鼠随机分为:假手术组(Sham组)、SCI-对照组(SCI-Sed组)和SCI-运动组(SCI-TT组)。SCI-Sed组和SCI-TT组使用改良Allen’s法制作T10不完全SCI模型,Sham组只暴露脊髓。SCI-TT组于SCI第8天行减重平板训练。于SCI术前、术后第1、7、14、21、28、35天使用Von Frey单丝及热刺激痛觉测试仪对大鼠的痛觉阈值进行评估。SCI 5周后,使用免疫组化技术对所有大鼠L4—5脊髓进行染色,观察脊髓后角小胶质细胞及星形胶质细胞活化情况,并对大鼠痛觉阈值与胶质细胞活化之间的相关性进行分析。结果:机械性痛觉阈值评估结果显示,SCI术后第1天,SCI-Sed组和SCI-TT组阈值均较Sham组增加(P<0.05);之后两组阈值均低于Sham组(P<0.05);第21—35天,SCI-TT组阈值明显高于SCI-Sed组(P<0.05)。热刺激痛觉阈值结果显示,SCI术后第1天,SCI-Sed组和SCI-TT组痛觉阈值较Sham组均增加(P<0.05);SCI 7天后,两组大鼠痛觉阈值均低于Sham组(P<0.05);术后14—35天,SCI-TT组痛觉阈值明显高于SCI-Sed组(P<0.05)。小角质细胞及星形胶质细胞免疫组化结果显示,SCI-Sed组和SCI-TT组脊髓后角内的阳性细胞数量多于Sham组(P<0.05);而SCI-TT组明显少于SCI-Sed组(P<0.05)。相关性分析显示,SCI后第35天,痛觉阈值与脊髓后角胶质细胞活化数量之间呈负相关(P<0.001)。结论:早期运动训练对缓解SCI大鼠NP的发生有一定作用,其机制可能与抑制脊髓后角胶质活化相关。

Objective:To observe the effect of early exercise training on mechanical and thermal sensitivity,and activation of microglia and astrocyte in dorsal horn of T-10incomplete spinal cord injury (SCI)rats. Method:Totally 24adult female SD rats were randomly divided into three groups,sham operation group (Sham group),SCI-control group (SCI-Sed group)and SCI-exercise group (SCI-TT group).SCI-Sed group and SCI-TT group used modified Allen's method to produce TI0incomplete SCI model,and Sham group only exposed spi- nal cord.SCI-TT group underwent body-weight supported treadmill training from 8th day after SCI.The pain threshold was evaluated by Von Frey monofilament and plantar test device before and I,7,14,21,28and 35 days after SCI.5weeks after SCI,the L4-5spinal cord of all rats was stained by immunohistochemistry,and the number of microglia and astrocyte in the dorsal horn of the spinal cord was observed.The correlation be- tween the threshold of pain and the activation of glial cells in rats were also analyzed. Result:Mechanical pain threshold assessment showed that first days after SCI,the thresholds of SCI-Sed group and SCI-TT group were significantly increased and higher than the Sham group (P<0.05),the two groups in follow-up evaluation were significantly lower than Sham group (P<0.05),at 21--35day,SCI-TT group was significantly higher than SCI-Sed group (P<0.05).Heat pain threshold showed that first days after SCI,SCI- Sed group and SCI-TT group were higher than Sham group (P<0.05),7th day after SCI,the two groups pain thresholds were lower than those in Sham group(P<0.05),14--35days after operation,SCI-TT group pain threshold was significantly higher than that of SCI-Sed group (P<0.05).The immunohistochemistry showed that the number of microglia and astrocyte in the dorsal horn of spinal cord in SCI-Sed group and SCI-TT group was higher than that in Sham group (P<0.001),but that of SCI-TT group was less than that of SCI-Sed group (P<0.001).The correlation analysis showed that,at 35days after SCI,there was a negative correlation between the threshold of pain and the number of activation of glial cells in the dorsal horn of spinal cord (P<0.001). Conclusion:Early exercise training has certain effect on relieving the occurrence of NP in SCI rats,and its mechanism may be related to inhibiting glial activation of spinal dorsal horn.