电针对慢性坐骨神经缩窄损伤大鼠脊髓谷氨酸与NMDA受体表达的影响

目的 探讨电针对神经病理性痛大鼠痛觉过敏及其脊髓谷氨酸(Glu)与NMDA R1表达的影响.方法 雄性SD大鼠,逐一行基础痛阈测定,剔除痛阈过高和过低者后,随机分出假手术组(n=16)和模型动物组.模型动物组实施慢性坐骨神经缩窄损伤(CCI)手术.待模型成功后将模型动物随机分为手术组和电针组(n=16).电针"委中"和"环跳"穴,观察其对大鼠机械痛阈和热痛阈的影响,并以OPA柱前衍生+HPLC荧光检测及免疫组化等方法分别测定脊髓Glu水平以及背角Glu和NMAR1阳性表达的变化.结果 CCI手术可明显降低大鼠机械痛阈和热痛阈,手术组10d时分别为(12.10±2.25)g和(10.09±1.23)s,与假手术组相比,差异有显著性(P<0.01);并且手术组脊髓Glu水平明显升高,为(23.66±4.37)μmoL/mg,其损伤侧背角Glu阳性终末表达减少(0.16±0.01),NMAR1的阳性表达升高(0.12±0.03),与假手术组相比,均差异有显著性(P<0.01,P<0.05);电针连续7次十预后,脊髓Glu水平以及背角Glu终末和NMAR1阳性表达均被逆转,与手术组各项比较差异有显著性(P<0.01,P<0.05);与此同时明显改善CCI大鼠的痛敏状态与痛行为.结论 电针减轻神经病理性痛的脊髓机制之一,可能与其有效地抑制大鼠脊髓相应节段Glu的释放、调整NMDA受体的功能状态有关.

The effects of electroacupuncture on glutamic acid and expression of NMD receptor on spinal cord of neuropathic pain model rats with chronic constriction injury of the sciatic nerve

Objective To investigate the effect of electroacupuncture(EA) on hyperalgia and glutamic acid (Glu) and expression of NMDA receptor in rats with neuropathic pain. Methods SD rats, healthy and male, were tested the base mechanical pain threshold by dynamic plantar aesthesiometer. After removed the rats with high or low pain threshold, randomly divided into sham operation group ( n = 16 ) and model group ( n = 32) with chronic constriction injury of the sciatic nerve(CCI). After the CCI model of rats was established, the rats divided into model group( n= 16) and EA group( n= 16) continusly. The CCI rats were treated by EA (2Hz, onset 1mA, enhance 1mA each 10 min) on Huan tiao ( GB 30) and Wei zhong ( BL 40) , and the effects of EA was observed by tested the mechanical and thermal pain thresholds. The contents of Glu in spinal cord was tested by HPLC with OPA derivatized, and the expressions of Glu positive neurons, the NR1 and NR2B receptor subunits were measured by immunohistochemistry. Results At 10th day, the mechanical and thermal pain thresholds were reduced on CCI rats markedly, and showed (12.10 ±2.25)g and ( 10.09 ± 1.23) s respectively. There were significantly difference compared with the sham operation group (P<0.01).The contents of Glu was significantly increased (23.66 ±4.37)μmol/mg, and the expressions of Glu positive neurons was reduced markedly in spinal cord(0.16 ±0.01 ) , the significant difference was existed. The expressions of NR1 also increased in spinal cord (0.12 ±0:03) , and existed significantly difference compared with the sham operation group (P < 0.05). After CCI rats treated by 2Hz EA, 7 day, the contents of Glu, the expressions of Glu positive neurons, and NR1 subunits were all significantly reversed in rats with CCI(P<0.01, P<0.05). Same times, the behavior of pain was improved. Conclusion EA could efficaciously inhibited releasing of Glu, and adjusted the function and the conditions of NMDA receptor in related segment of spinal cord. It is the analgesia mechanisms of EA on neuropathic pain in spinal cord.