脉冲射频对坐骨神经慢性压迫模型大鼠的痛觉过敏及脊髓背角NR2B亚基表达的作用

Effects of Pulsed Radiofrequency on Hyperalgesia and Expression of NR2B Subunit in Spinal Dorsal Horn in Chronic Constriction Injury Rats

目的观察脉冲射频(PRF)对坐骨神经慢性压迫(CCI)后神经病理性疼痛模型大鼠疼痛行为学、损伤坐骨神经结组织病理学的影响,检测脊髓背角NR2B亚基的表达。方法 48只Sprague-Dawley大鼠随机等分为Sham-Sham(SS)组、Sham-PRF(SP)组、CCI-Sham(CS)组和CCI-PRF(CP)组。CS、CP组大鼠结扎右侧坐骨神经干,制作CCI模型;SS、SP组只分离坐骨神经而不结扎。术后15 d,CP、SP组于坐骨神经干结扎处行PRF,SS、CS组仅放置电极针不通电。造模前,造模后3 d、7 d、11 d、15 d,治疗后1 d、3 d、7 d、11 d、15 d测量大鼠右后足机械缩足阈值(HWT);治疗后15 d光镜下行右侧坐骨神经干评分;Western blotting测定L4-6脊髓背角中NR2B亚基蛋白表达。结果造模后CS、CP组HWT较SS、SP组降低;治疗后,CP组HWT高于CS组。光镜下CP组较CS组神经轴索直径、髓鞘厚度明显增加(P<0.01)。CP组大鼠脊髓背角NR2B表达低于CS组(F=10.769,P<0.05)。结论PRF能降低CCI模型脊髓背角NR2B亚基表达,修复受损神经,降低机械痛敏。

Objective To observe the behavioral and the histopathology changes and expression of NR2B subunit in spinal dorsal horn in chronic constriction injury （CCI） rats after pulsed radiofrequency （PRF）. Methods Forty-eight adult Sprague-Dawley rats were randomly divided into Sham-Sham （SS）, Sham-PRF （SP）, CCI-Sham （CS） and CCI-PRF （CP） groups. The right sciatic nerves （SNs） of the CS and CP groups were ligated to create the CCI model. For the SS and SP groups, the right SNs were separated without ligation. The CP and SP groups accepted PRF at the ligation site 15 days after modeling, while the electrode was placed in rats in the SS and CS groups without elec-tricity. The hindpaw withdrawal threshold （HWT） was measured before and 3, 7, 11, 15 days after modeling, and 1, 3, 7, 11, 15 days after treatment. The right SNs at ligation sites were assessed with optical microscopic score 15 days after treatment, and the NR2B expression in the L4-6 spinal dorsal horn were determined with Western blotting. Results HWT was significantly shorter in the CS and CP groups than in the SS and SP groups after modeling, and was more in the CP group than in the CS group. Under the optical microscope, the axonal diame-ter and myelin sheath thickness increased in the CP group compared to those in the CS group （P〈0.01）, the NR2B expression was less in the CP group than in the CS group after treatment （F=10.769, P〈0.05）. Conclusion PRF may reduce hyperalgesia and repair damaged SNs in CCI-induced neuropathic pain, which may associate with inhibition of the NR2B subunit expression in spinal dorsal horn.