电针对炎性痛大鼠痛行为及颈段脊髓γ-氨基丁酸受体亚型基因表达的影响

Effects of Electroacupuncture of "Futu"(LI 18),etc.on Pain Behavior and Expression of GABA Receptor Subunit Genes in 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γ-氨基丁酸受体(GABAR)表达的影响,分析针麻行甲状腺手术的镇痛机制。方法:将Wistar大鼠随机分为对照组、模型组、足三里-阳陵泉组、合谷-内关组、扶突组,每组10只。甲状软骨处皮下注射2.5%甲醛造成局部炎性疼痛模型,造模后10min给予电针。分别在注药前、后观察动物的行为学(擦面反应、热痛阈值)变化。行为学观察结束后立即取C1-C3段脊髓组织,用逆转录聚合酶链反应法检测大鼠脊髓组织GABAR亚单位A(GABAAR)、B 1(GABABR 1)和B 2(GABABR 2)mRNA表达水平的变化;用H-E染色,观察甲状腺区组织病理形态变化。结果:注射甲醛后5、40、70min,动物擦面次数明显增多(均P<0.05),热痛阈明显降低(均P<0.05)。电针"扶突""合谷-""内关"后,动物的痛阈明显升高(均P<0.05),擦面次数明显减少(均P<0.05)。注射甲醛后80min,模型组脊髓GABABR 1mRNA及GABABR 2mRNA的表达明显增加(均P<0.05),GABAAR mRNA表达稍增加(P>0.05)。与模型组比,足三里-阳陵泉组、合谷-内关组、扶突组GABABR 1mRNA,合谷-内关组、扶突组GABABR 2mRNA及GABAAR mRNA的表达均进一步上调(均P<0.05)。H-E染色结果表明,电针"合谷"-"内关"及"扶突"穴可抑制甲状腺区组织炎性反应的发展。结论:电针"扶突"穴和"合谷"-"内关"可明显抑制颈部甲状腺区注射甲醛诱发的痛行为反应,上调颈段脊髓GABABR 1mRNA、GABABR 2mRNA及GABAAR mRNA的表达,减轻甲状腺区注射甲醛产生的炎性反应。

Objective To observe the effect of electroacupuncture（EA） at different acupoints on the expression of gamma aminobutyric（GABA） receptor（R） subunit genes in the cervical spinal cord in rats with thyroid regional inflammatory pain so as to analyze its analgesic mechanism for thyroid surgery.Methods A total of 50 Wistar rats were randomized into control,model,Futu（LI 18）,Hegu（LI 4）-Neiguan（PC 6,LI 4-PC 6）,Zusanli（ST 36）-Yanglingquan（GB 34,ST 36-GB 34） groups,with 10 rats in each group.Thyroid regional pain model was established by subcutaneous injection of 2.5% formalin（100 μL）.Ten minutes after modeling,EA（2 Hz/15 Hz,1 mA） was applied to LI 18,LI 4-PC 6 and ST 36-GB 34 for 30 min,respectively.The animals＇ face-grooming（FG） times in 5 min and thermal pain threshold（paw withdrawal latency,PWL） were recorded.The expression of GABAAR,GABABR 1,and GABABR 2 genes in the cervical 1-3 segments of the spinal cord 80 min after modeling was detected by using reversed transcription-polymerase chain reaction（RT-PCR）.Histological changes of the tissues of the thyroid region were observed by using H.E.staining.Results After subcutaneous injection of formalin,the animals＇ FG times in 5 min were increased considerably and the thermal pain threshold was decreased obviously in the model group（P0.05）.Concomitantly,the expression levels of GABABR 1,and GABABR 2 genes of the cervical spinal cord were upregulated significantly in the model group（P0.05）,and GABAAR expression was increased slightly（P0.05）.Compared with the model group,the FG times in 5 min in the LI 18 and LI 4-PC 6 groups at 40 min and 70 min after modeling were decreased significantly（P0.05）,and their thermal pain threshold values were increased markedly（P0.05）.The expression levels of GABAB R 1 mRNA,GABAB R 2 mRNA and GABAA R mRNA were significantly higher in the LI 18 and LI 4-PC 6 groups than in the model group（P0.05）.The expression level of GABABR 1 mRNA of the ST 36-GB 34 group was obviously higher than that of the model group（P0.05）.The inflammatory cells in the formalin-injected thyroid region were relatively fewer in the LI 18 and LI 4-PC 6 groups than in the model group.Conclusion Both EA of LI 18 and LI 4-PC 6 can significantly suppress formalin-injection induced pain reactions in the thyroid region,which may be closely associated with its effects in upregulating expression levels of cervico-spinal GABABR 1mRNA,GABABR 2 mRNA and GABAAR mRNA,and reduce regional inflammatory reactions in the thyroid region.