电针对神经病理性疼痛大鼠脊髓背角神经元突触传递长时程增强的抑制作用

目的:观察电针对神经病理痛大鼠机械痛阈的影响和脊髓背角突触传递长时程增强(LTP)的抑制作用。方法:30只SD大鼠分为假手术组、模型组和电针组,每组10只。制备大鼠坐骨神经分支选择性损伤型神经病理痛(SNI)模型后,电针"环跳"委中"穴30 min,每日1次,共7 d。观察电针对SNI模型大鼠机械痛阈和脊髓背角神经元突触传递LTP的干预作用。结果:造模1 d后,模型组及电针组大鼠机械痛阈较假手术组显著降低,至造模第7天,仍维持较低水平,差异均有统计学意义(P<0.01);电针治疗后,电针组大鼠机械痛阈较模型组显著升高(P<0.01)。假手术组不能诱导出脊髓背角神经元突触传递LTP,其诱导前、诱导后、诱导2 h后的C-纤维诱发场电位变化率与基础平均值比较,差异均无统计学意义(P>0.05);模型组大鼠诱导前、诱导后、诱导2 h后的C-纤维诱发场电位变化率较基础平均值均显著升高(P<0.01);电针组治疗7 d后的诱导前、诱导后、诱导2 h后的C-纤维诱发场电位变化率较模型组显著降低(P<0.01)。电针对造模后第15天的模型组大鼠脊髓背角神经元突触传递LTP仍然有明显的抑制作用。结论:电针可显著改善神经病理痛模型大鼠的疼痛,抑制因脊髓背角神经元中枢敏化现象引起的突触传递异常而致的脊髓背角神经元LTP,并能阻断已发生且持续维持的脊髓背角LTP。

Effects of Electroacupuncture on Long-term Potelltiation of Synaptic Transmission in Spinal Dorsal Horn in Rats with Neuropathic Pain

Objective To observe the effect of electroacupuncture (EA) of "Huantiao" (GB 30) and, "Weizhong" (BL 40) on the mechanical pain threshold and the long-term potentiation (LTP) of the spinal dorsal horn in rats with neuropathicpain. Methods Thirty SD rats were randomized into control (sham-operation), model and electroacupuncture (EA) groups, with 10 cases in each. The neuropathic pain model was established by ligature and transaction of the popliteal nerve and common peroneal nerve. EA (2 Hz, 1 mA) was applied to "Huantiao" (GB 30) and "Weizhong" (BL 40) on the affected side for 30 min, once daily for 7 days. The mechanical pain threshold of the paw was detected before and after modeling and EA. LTP of C-fiber stimulation (2 mA, 0. 5 ms, 100 Hz, interval 10 s, 4 strains) evoked field potentials in spinal dorsal horn (L_4/L_5) was recorded in rats under anesthesia. Results Compared with control group, the pain threshold of model group reduced significantly from the 1~(st) day on after ligature and transaction of the nerve (P<0. 01), while 14 days after EA, it elevated evidently in comparison with model group (P<0. 01), suggesting an increase of the mechanical pain threshold after EA. Comparison of the variance rates of C-fiber induced LTP of the field potential among the 3 groups showed that the variance rate of EA group was significantly lower than that of model group (P<0. 01). Self-comparison of EA group showed that after EA, the variance rate of LTP reduced significantly (P<0. 01). Conclusion EA of "Huantiao" (GB 30) and "Weizhong" (BL 40) can significantly relieve neuropathic pain in rats with nerve injury,and inhibit C-fiber high-frequency-stimulation induced LTP due to central sensitization induced abnormality synaptic transmission.