The analgesic effect and ATP release at acupuncture points in response to acupuncture with different parameters on arthritis rats

Previous studies indicated a close correlation between manual acupuncture (MA) analgesia and the mobilization of extracellular adenosine triphosphate (ATP) at the acupoints. This study attempted to investigate whether this relationship is altered with the manipulation patterns of MA. Additionally, we further testified whether these two events parallelly varied with different frequencies of electroacupuncture (EA). Male SD rats were randomly divided into four groups: blank group, model group, MA group, and EA group. MA group was further divided into four sub-groups: standard MA, sham MA, lifting-thrusting MA, and shallow MA. Similarly, EA group was categorized based on current frequency into 2 Hz, 2-100 Hz, 100 Hz, and ARL67156+100 Hz sub-groups. For the behavioral tests, each group comprised 4-8 rats; for extracellular ATP assessment, each group consisted of 3-6 rats. Complete Freund’s adjuvant (CFA) was injected into the left ankle joint cavity to create an acute adjuvant arthritis (AA) model. A 20-minute session of either MA at left Zusanli (ST36) or EA at bilateral ST36 was administered on AA rats. Thermal hyperalgesia of the hind paw was determined. Extracellular ATP in the interstitial space at ST36 (inters. ATP) was extracted using microdialysis and quantified via a luciferase-luciferin assay. Modeling induced tenderness at ST36 ( P<0.001 ) and higher ATP mobilization ( P<0.05 ) in response to MA. Both standard MA ( P<0.001 ) and lifting-thrusting manipulation ( P<0.001 ) exhibited a remarkable analgesic effect, which was not observed with sham MA, deep insertion plus retention. Verum MA ( P<0.001 ) rather than sham intervention, significantly elevated inters. ATP levels. Notably, shallow MA, penetrating the skin layer and needling with twirling-rotating, demonstrated analgesia and increasing inters. ATP level ( P<0.05 ). Regarding EA, treatments at frequencies of 2 Hz ( P<0.01 ), 2-100 Hz ( P<0.05 ), and 100 Hz ( P<0.05 ) significantly alleviated pain. Only the 2-100 Hz ( P<0.05 ) and 100 Hz ( P<0.01 ) interventions, particularly in the latter, potentiated ATP mobilization. Preventing ATP hydrolysis dampened the analgesic effects of the standard MA and 100 Hz EA. There is a general correlation between ATP mobilization at the acupoint and the analgesic effect of MA and EA. However, the underlying mechanisms related to shallow MA and 2 Hz EA remain to be elucidated. 前期研究表明, 手针 (manual acupuncture, MA) 镇痛效应与穴区胞外ATP的动员密切相关.本研究试图继续探究这种关联性是否因MA 手法的不同或电针 (electro-acupuncture, EA) 频率的不同而发生改变. 雄性SD大鼠随机分为空白组,模型组,MA组和EA组.其中, MA组再细分为标准手法组,假针刺组,提插手法组和浅刺组;EA组根据频率继续细分为2 Hz组,2-100 Hz, 100 Hz组和ARL67156+100 Hz组.行为学测试中, 每组大鼠4-8只;胞外ATP检测实验中, 每组3-6只.通过向左踝关节腔内注射完全弗氏佐剂 (complete Freund’s adjuvant, CFA) 建立急性踝关节炎性痛模型.各干预组均于患侧足三里穴 (ST 36) 行单次20分钟治疗.利用患侧足底热痛阈评估疼痛状态的指标;利用微透析技术收集ST 36组织液并利用萤光素酶法检对其中ATP (interstitial ATP, inters. ATP) 水平. 与正常对照组相比, 模型组ST36出现显著压痛 ( P <0.001) , 并且MA可动员更多ATP释放至组织间隙内 ( P <0.05) .标准针刺手法 ( P <0.001) 和提插手法 ( P <0.001) 均表现出显著的镇痛效果;但假针组 (仅深刺留针) 未见镇痛效果.并且, 前两种真针刺手法可显著提高inters. ATP水平 ( P <0.001) , 而假针刺不具有该作用.值得注意的是, 浅刺 (仅穿透皮肤层并做捻转手法) 同样具有镇痛效果和上调inters. ATP的作用 ( P <0.05) .2 Hz ( P <0.01) ,2-100 Hz ( P <0.05) 和100 Hz ( P <0.05) 电针均可显著缓解疼痛.但只有2-100 Hz ( P <0.05) 和100 Hz ( P <0.01) 电针干预, 尤其是100 Hz, 显著上调inters. ATP水平.穴区注射ARL67156抑制ATP水解可显著抑制标准手法手针和100 Hz电针的镇痛疗效. 总体而言, 穴区ATP动员与手针和电针的镇痛效果之间存在关联.然而, 浅刺和低频2 Hz电针镇痛的潜在机制仍有待进一步阐明.