Sun Jing, Fang Jian-Qiao, Shen Zui, Zhu Yi-Lin, Chen Qin, Fang Fang, Wang Jia-Ling, Li Fei, Shao Xiao-Mei
Third Clinical Medical College of Zhejiang Chinese Medical University, Hangzhou 310005, China; Zhejiang Key Laboratory of Acupuncture-Moxibustion and Neurology, Hangzhou 310053.
Third Clinical Medical College of Zhejiang Chinese Medical University, Hangzhou 310005, China.
Zhongguo Zhen Jiu. 2020 Apr 12;40(4):397-404. doi: 10.13703/j.0255-2930.20190130-k0002.
To observe the direct intervention effects of electroacupuncture (EA) and non-steroid anti-inflammatory drugs (NSAIDs) on pain memory, and to explore their effects on cAMP/PKA/cAMP pathway in anterior cingulate gyrus (ACC).
Fifty clean healthy male SD rats were randomly divided into a control group, a model group, an indomethacin group, an EA group and a sham EA group, 10 rats in each group. Except the control group, the pain memory model was established in the remaining four groups by twice injection of carrageenan at foot; 0.1 mL of 2%λ-carrageenan was subcutaneously injected at the left foot of rats; 14 days later, when the pain threshold of rats of each group returned to the basic level, the second injection was performed with the same procedure. The rats in the EA group were treated with EA at bilateral "Zusanli" (ST 36) for 30 min; the rats in the indomethacin group was treated with indomethacin intragastric administration with the dose of 3 mg/kg; the rats in the sham EA group was treated with EA without electricity at the point 0.3 mm forward "Zusanli" (ST 36) with the depth of 2 mm for 30 min; the rats in the control group was not given any invention. All the above interventions were performed 5 h, 1 d, 2 d and 3 d after the second injection of 2% λ-carrageenan. The left-side paw withdrawal thresholds (PWT) were observed before the first injection, 4 h, 3 d, 5 d after the first injection, before the second injection and 4 h, 1 d, 2 d, 3 d after the second injection. Three days after the second injection, the number of positive cells of cAMP, p-PKA, p-CREB and the number of positive cells of protein co-expression in the right ACC brain area were detected by immunofluorescence, and the relative protein expression of p-PKA and p-CREB were detected by Western blot.
Compared with the control group, the PWTs in the model group decreased significantly 4 h, 3 d and 5 d after the first injection and 1 d, 2 d and 3 d after the second injection (<0.05); compared with the control group, the positive expression of cAMP, p-PKA and p-CREB in the right ACC brain area in the model group increased significantly (<0.05), and the number of positive cells of the co-expression of cAMP/p-PKA and p-PKA/p-CREB also increased significantly (<0.05). Compared with the model group, indomethacin group and sham EA group, the PWTs in the EA group were increased significantly 1 d, 2 d and 3 d after the second injection (<0.05); compared with the model group, indomethacin group and sham EA group, the positive expression of p-PKA and p-CREB in the right ACC brain area in the EA group decreased significantly (<0.05), and the number of positive cells of co-expression of cAMP/p-PKA and p-PKA/p-CREB was decreased significantly (<0.05). Compared with the model group and sham EA group, the positive expression of cAMP in the right ACC brain area was decreased in the EA group (<0.05).
EA have a direct intervention effect on pain memory, which have significant advantage over NSAIDs in the treatment of chronic pain. The advantage effect of EA on pain memory may be related to the inhibition of cAMP/PKA/CREB pathway in ACC area.
观察电针（EA）与非甾体类抗炎药（NSAIDs）对疼痛记忆的直接干预作用，并探讨其对前扣带回（ACC）中cAMP/PKA/cAMP通路的影响。
将50只清洁级健康雄性SD大鼠随机分为对照组、模型组、吲哚美辛组、电针组和假电针组，每组10只。除对照组外，其余四组通过两次足跖注射角叉菜胶建立疼痛记忆模型；于大鼠左足跖皮下注射0.1 mL 2% λ-角叉菜胶；14天后，当各组大鼠疼痛阈值恢复至基础水平时，按相同程序进行第二次注射。电针组大鼠于双侧“足三里”（ST 36）行电针治疗30分钟；吲哚美辛组大鼠以3 mg/kg剂量灌胃给予吲哚美辛；假电针组大鼠于“足三里”（ST 36）向前0.3 mm、深度2 mm处行无电针刺激30分钟；对照组大鼠不给予任何干预。上述所有干预均在第二次注射2% λ-角叉菜胶后5小时、1天、2天和3天进行。观察首次注射前、首次注射后4小时、3天、5天、第二次注射前及第二次注射后4小时、1天、2天、3天大鼠左侧足跖的缩足阈值（PWT）。第二次注射后3天，采用免疫荧光法检测右侧ACC脑区cAMP、p-PKA、p-CREB阳性细胞数及蛋白共表达阳性细胞数，采用蛋白质免疫印迹法检测p-PKA和p-CREB的相对蛋白表达。
与对照组比较，模型组首次注射后4小时、3天和5天及第二次注射后1天、2天和3天PWT显著降低（<0.05）；与对照组比较，模型组右侧ACC脑区cAMP、p-PKA和p-CREB阳性表达显著增加（<0.05），cAMP/p-PKA和p-PKA/p-CREB共表达阳性细胞数也显著增加（<0.05）。与模型组、吲哚美辛组和假电针组比较，电针组第二次注射后1天、2天和3天PWT显著升高（<L0.05）；与模型组、吲哚美辛组和假电针组比较，电针组右侧ACC脑区p-PKA和p-CREB阳性表达显著降低（<0.05），cAMP/p-PKA和p-PKA/p-CREB共表达阳性细胞数显著减少（<0.05）。与模型组和假电针组比较，电针组右侧ACC脑区cAMP阳性表达降低（<0.05）。
电针对疼痛记忆有直接干预作用，在慢性疼痛治疗中较NSAIDs具有显著优势。电针在疼痛记忆方面的优势作用可能与抑制ACC区cAMP/PKA/CREB通路有关。
