电针对甲状腺区炎性痛大鼠痛行为反应及脊髓N-甲基-D-天门冬氨酸受体亚型NR 2 B表达和磷酸化水平的影响

Effects of Electroacupuncture at Different Acupoints on the Pain Behavior and NMDA Receptor 2 B Subunit mRNA and Protein Expression and Phosphorylation Level in the Cervical Spinal Cord in Rats with Thyroid Regional Pain

目的:观察电针对甲状腺区甲醛致痛大鼠脊髓N-甲基-D-天门冬氨酸(NMDA)受体亚单位NR2B表达的影响,分析针麻行甲状腺手术的作用机制。方法:将50只Wistar大鼠随机分为对照组、模型组、合谷-内关组、扶突组、足三里-阳陵泉组,每组10只。给大鼠甲状软骨处皮下注射2.5%甲醛100μL造成局部炎性疼痛模型。各治疗组在造模后10min给予电针(2Hz/100Hz,1mA,30min)。分别在注药前0～5min,注药后5～10min、40～45min、70～75min观察动物的行为学变化。行为学观察结束后立即取C1～C3段脊髓组织,分别用RT-PCR和Westernblot法检测NMDA受体亚单位NR2BmRNA及蛋白的表达,以及NR2B的磷酸化水平。结果:注射甲醛后大鼠出现典型的二相疼痛反应,动物擦面反射明显增多,注射侧前肢辐射热测痛显示出现痛觉过敏(P<0.05);电针"扶突""合谷"-"内关"30min后,动物的痛阈明显升高,擦面次数明显减少(P<0.05);足三里-阳陵泉组的痛阈和擦面次数与模型组比差异无统计学意义(P>0.05)。各组NMDA受体NR2BmRNA和蛋白表达变化比较差异均无统计学意义(P>0.05)。与对照组比,模型组NMDA受体亚单位NR2B磷酸化水平显著增加(P<0.05),电针"扶突"和"合谷"-"内关"穴能明显逆转这种反应(P<0.05),而电针"足三里"-"阳陵泉"的作用不明显(P>0.05)。结论:电针"扶突"和"合谷"-"内关"能明显抑制大鼠甲状腺区皮下注射甲醛诱导产生的擦面及缩腿痛反应,该作用可能与其下调脊髓C1～C3段NMDA受体NR2B亚基磷酸化的水平有关。与"足三里"-"阳陵泉"的作用相比,电针"扶突"和"合谷"-"内关"的镇痛作用具有相对特异性。

Objective To observe the effect of electroacupuncture （EA） of different acupoint groups on the expression of NR 2 B subunit of N-methyI-D-aspartate （NMDA） receptor in the cervical spinal cord in rats with thyroid regional pain so as to analyze the analgesic mechanism of acupuncture for performing thyroid surgery. Methods A total of 50 Wistar rats were randomized into control, model, EA-Futu（ST 32）, EA-Hegu（LI 4）-Neiguan（PC 6, EA-LI 4-PC 6）, EA-Zusanli （ST 36）-Yanglingquan （GB 34, EA-ST 36-GB 34） groups, with 10 cases in each. Thyroid regional pain model was established by subcutaneous injection of 2.5% formaldehyde. Ten minutes after modeling, EA （2 Hz/100 Hz, 1 mA） was applied to ST 32, LI 4-PC 6 and ST 36-GB 34 for 30 min respectively. The animals＇ face, grooming （FG） times and paw withdrawal latency （PWL） of radiant heat irradiation were recorded. The spinal cord tissues of the cervical 1 - 3 segments were removed for detecting the expression of NR 2 B mRNA and protein of NMDA receptor with reversed transcription-polymerase chain reaction and Western blotting techniques separately. Results After subcutaneous injection of 2.5% formaldehyde, the animals＇ FG times increased considerably and the PWL was shortened obviously （P〈0.05）. Compared with model group, the FG times of EA-ST 32 and EA-LI 4-PC 6 groups at 40-45 rain and 70- 75 min after modeling decreased significantly, and their PWL prolonged markedly （ P〈0. 05）. The effect of EA-ST 32 was apparently superior to that of EA-LI 4-PC 6 group in reducing FG times. No significant differences were found between EA-ST 32 and EA-LI 4-PC 6 groups in PWL, and between model and EA-ST 36-GB 34 groups （P〉0.05）. Results of NR 2 B mRNA and protein detections showed no significant differences among the 5 groups in their expression （P〉0.05）. Comparison of the phosphorylated NR 2 B among 5 groups showed that EA-ST 32 and EA-LI 4-PC 6 could effectively down-regulate 2.5 % formaldehyde in- duced increase of NR 2 B phosphorylation levels （ P〈0.05）, while EA-ST 36-GB 34 had no obvious effect on it （P〉0.05）. Conclu- sien Both EA-ST 32 and EA-LI 4-PC 6 can significantly suppress thyroid regional pain induced behavior reactions, which may be closely associated with their effects in down-regulating NR 2 B phosphorylated level. The analgesic effect of EA-ST 32 and EA-LI 4-PC 6 for thyroid surgery is relatively more effective in comparison with EA-ST 36-GB 34.