不同间隔时间电针对炎症痛大鼠下丘脑阿片肽基因表达的影响

Effects of Repeated Electroacupuncture with Different Intervals on Hypothalamic Opioid Peptide Gene Expression in Inflammatory-pain Rats

目的：观察累加电针对炎症痛大鼠模型不同间隔时间的镇痛效果，从而探讨针刺镇痛的最佳治疗间隔时间。方法：96只雄性SD大鼠随机分为正常组、模型组和电针组，以佐剂性关节炎大鼠作为炎症痛模型。分别以3、6、12、24h作为电针治疗间隔时间。选用“昆仑”和“悬钟”穴，电针频率15～100Hz，疏密波，电压2～4V，留针20min。连续治疗6d后观测大鼠疼痛级别、痛阈、下丘脑前阿黑皮素和前脑啡肽原mRNA的表达。结果：电针组的疼痛级别明显低于模型组（P〈0．05），24h电针组的痛阈高于模型组（P〈0．01），各电针组下丘脑前阿黑皮素和前脑啡肽原mRNA表达的细胞数均明显高于模型组。在不同间隔时间电针治疗中，以间隔24h治疗更能明显降低炎症痛大鼠的疼痛级别并提高其痛阈，促进下丘脑前阿黑皮素和前脑啡肽原mRNA表达（P〈0．05或0．01）。结论：电针对炎症痛大鼠模型具有非常明显的镇痛作用，间隔24h重复治疗可显著提高其镇痛效果。

Objective： To observe the analgesic effect of repeated electroaoupuncture （EA） with different intervals in a day in adjuvant arthritis （AA） rats so as to find the best time interval of EA for analgesia. Methods： A total of 96 SD rats were evenly randomized into normal, model and EA groups which were further divided into 3 h, 6 h, 12 h and 24 h subgroups, with 8 cases in each subgroup. AA model was established by subcutaneous injection of Freund＇s Complete Adjuvant （0.1 mL） into the right hind paw. EA （ 15/100 Hz, dense-sparse waves, 2-4 V） was applied to the right ＂Kunlun＂ （BL 60）-＂Xuanzhong＂ （GB 39） for 20 min every time, with intervals of 3 h,6 h, 12 h and 24 h everyday and continuously for 6 days. The pain grade （according to Xu＇s method） and pain threshold （PT, the latency of radiant heat irradiation induced leg withdrawal reaction） of AA rats were determined after EA treatment. The rat＇s hypothalamus tissue was sampled to cut into sections （5-6 μm） to be stained with insitu hybridization histcohemistry for detecting proopiornelanocortin （POMC） and prcenkephalin （PENK） mRNA expression. Resuits： Contrasted with 3 h, 6 h, 12 h and 24 h of control group, the pain grades of both model and EA groups were apparently higher than those of normal control group, while those of EA group were lower than those of model group. Compared with control group, the PT values of model group （3 h, 6 h, 12 h and 24 h subgroups） and EA group （3 h and 6 h subgroups） were significant lower （P 〈 0.01, 0.05）, while comparison between model group and EA group showed that the PT values of EA group were higher （3 h, 6 h and 12 h subgroups） or significantly higher （24 h subgroup） than those of model group （P〈0.01）. In EA group, the PT value of 24 h subgroup was significantly higher than those of 3 h, 6 h and 12 h subgroups （P〈0.05, 0.01）. The POMC mRNA and PENK mRNA expression-positive cells of the 4 subgroups of both model and EA groups were significantly more than those of control group （P〈0.01）; and those of the 4 subgroups of EA group were significantly more than those of model group （P〈0.01）. In EA group, the POMC mRNA and PENK mRNA expression-positive cells of 24 h subgroup were significantly more than those of 3h, 6 h and 12 h subgroups （P〈0.01, 0.05）. Conclusion： Repeated EA has a definite analgesic effect and can obviously promote POMC mRNA and PENK mRNA expression in AA rats, and the effects of 24 h subgroup is the best.