Pressure manipulation at trigger points is a recognized and effective therapeutic approach for pain relief, reflecting the muscle-relaxing and analgesic effects of traditional Chinese tuina. However, its underlying mechanism of action has not yet been fully elucidated.

To investigate whether the effect of pressure manipulation on myofascial trigger points is associated with the regulation of intracellular Ca²⁺ by the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA)/ryanodine receptor 1 (RyR1) pathway.

Sixty Sprague-Dawley rats were assigned, according to a random number table, to a blank group not subjected to modeling (n=10) and a modeling cohort subjected to trigger-point modeling (n=50). Rats in the modeling cohort underwent blunt-strike modeling. After modeling, rats that met the model evaluation criteria were randomly allocated to the model group, pressure manipulation group, pressure manipulation+agonist group, and pressure manipulation+vehicle group. The pressure manipulation group received intervention using a pressure manipulation stimulation device. The pressure manipulation+agonist group received intraperitoneal injection of 8-Bromo-cAMP solution at 20 mg/kg, whereas the pressure manipulation+vehicle group received an equivalent volume of 0.9% sodium chloride solution. Mechanical pain threshold, soft-tissue tension, and electromyography were assessed in each group. After the final electromyographic assessment, the rats were anesthetized and euthanized. The taut bands or nodular regions of the left medial thigh muscle were collected. cAMP content was measured using enzyme-linked immunosorbent assay. Protein expression levels of PKA, phosphorylated RyR1 (P-RyR1), and 12-kDa FK506-binding protein (FKBP12) were determined by Western blotting. P-RyR1 was detected by immunohistochemistry, and intracellular Ca²⁺ concentration was assessed by fluorescence staining.

A total of 40 successfully modeled rats were ultimately included, with 10 rats each in the model group, pressure manipulation group, pressure manipulation+agonist group, and pressure manipulation+vehicle group. Before intervention, the mechanical pain thresholds in the model group, pressure manipulation group, pressure manipulation+agonist group, and pressure manipulation+vehicle group were lower than those in the blank group (P<0.05). After intervention, the mechanical pain thresholds in the model group and pressure manipulation+agonist group remained lower than those in the blank group; the thresholds in the pressure manipulation group, pressure manipulation+agonist group, and pressure manipulation+vehicle group were higher than those in the model group; and the threshold in the pressure manipulation+agonist group was lower than those in the pressure manipulation group and pressure manipulation+vehicle group (P<0.05). Within-group comparisons before and after intervention showed that the mechanical pain thresholds in the pressure manipulation group, pressure manipulation+agonist group, and pressure manipulation+vehicle group were higher after intervention than before intervention (P<0.05).

Local manual stimulation of trigger points may alleviate pain through the downregulation of intracellular Ca²⁺ concentrations mediated by inhibition of the cAMP/PKA/P-RyR1 pathway, resulting in the relaxation of abnormally contracted muscle nodules.

按法干预触发点是公认有效的缓解疼痛的治疗方法，这体现了中医推拿的舒筋止痛作用，但是目前其作用机制尚未完全阐明。

探讨按法对肌筋膜触发点的作用是否与环磷酸腺苷（cAMP）/蛋白激酶A（PKA）/雷诺丁受体1（RyR1）对胞内Ca²⁺的调节有关。

将60只SD大鼠按照随机数字表法分为无需造模的空白组大鼠10只和参与触发点造模的大鼠50只，造模大鼠采用钝性击打造模，造模后将符合模型评价标准者随机分配入模型组、按法组、按法+激动剂组与按法+溶剂组。按法组采用按法刺激仪器干预，按法+激动剂组通过腹腔注射8-Bromo-cAMP溶液20 mg/kg，按法+溶剂组注射等量0.9%氯化钠溶液。检测各组大鼠机械痛阈值、软组织张力、肌电图检测。末次肌电图检测结束后麻醉并处死大鼠，收集左侧大腿内侧肌的肌肉紧张带或结节区域，酶联免疫吸附试验检测cAMP含量，蛋白质印迹法检测PKA、P-RyR1和12kDa FK506结合蛋白（FKBP12）蛋白表达，免疫组化法检测磷酸化雷诺丁受体1（P-RyR1），荧光染色法检测胞内Ca²⁺浓度。

最终纳入造模成功大鼠40只，模型组、按法组、按法+激动剂组和按法+溶剂组各10只。干预前模型组、按法组、按法+激动剂组和按法+溶剂组机械痛阈值低于空白组（P<0.05），干预后模型组、按法+激动剂组机械痛阈值低于空白组，按法组、按法+激动剂组和按法+溶剂组机械痛阈值高于模型组，按法+激动剂组机械痛阈值低于按法组、按法+溶剂组（P<0.05）。干预前后组内比较结果显示，干预后按法组、按法+激动剂组、按法+溶剂组机械痛阈值高于干预前（P<0.05）。干预前模型组、按法组、按法+激动剂组和按法+溶剂组软组织张力D0.2低于空白组（P<0.05），干预后模型组、按法+激动剂组软组织张力D0.2低于空白组（P<0.05），按法组、按法+激动剂组、按法+溶剂组软组织张力D0.2高于模型组（P<0.05），按法+激动剂组、按法+溶剂组软组织张力D0.2高于按法+激动剂组（P<0.05）。干预前后组内比较结果显示，干预后按法组、按法+溶剂组软组织张力D0.2高于干预前（P<0.05）。肌电图检测结果显示，模型组、按法组、按法+激动剂组、按法+溶剂组肌电图振幅与频率均高于空白组（P<0.05），按法组、按法+激动剂组、按法+溶剂组肌电图振幅与频率均低于模型组（P<0.05），按法+激动剂组肌电图振幅与频率均高于按法组、按法+溶剂组（P<0.05）。酶联免疫吸附试验结果显示，模型组、按法+激动剂组cAMP高于空白组（P<0.05），按法组、按法+激动剂组、按法+溶剂组cAMP低于模型组（P<0.05），按法+激动剂组cAMP高于按法组、按法+溶剂组（P<0.05）。蛋白质印迹法结果显示，模型组、按法+激动剂组PKA、P-RyR1和FKBP12高于空白组（P<0.05），按法组、按法+溶剂组PKA、P-RyR1和FKBP12低于模型组（P<0.05），按法+激动剂组PKA、P-RyR1和FKBP12高于按法组、按法+溶剂组（P<0.05）。免疫组化染色结果显示，模型组、按法+激动剂组P-RyR1 IOD高于空白组（P<0.05），按法组、按法+溶剂组P-RyR1 IOD低于模型组（P<0.05），按法+激动剂组P-RyR1 IOD高于按法组、按法+溶剂组（P<0.05）。免疫荧光检测结果显示，模型组、按法组、按法+激动剂组、按法+溶剂组平均荧光强度高于空白组（P<0.05），按法组、按法+激动剂组、按法+溶剂组平均荧光强度低于模型组（P<0.05），按法+激动剂组平均荧光强度高于按法组、按法+溶剂组（P<0.05）。

触发点局部按法干预可能通过抑制cAMP/PKA/P-RyR1，促使胞内Ca²⁺浓度下降，从而舒展异常收缩肌节缓解疼痛。