关键词: 按法, 触发点, 疼痛, 钙离子, cAMP/PKA/P-RyR1

Abstract: Background The application of pressing intervention on myofascial trigger points (MTrPs) is widely acknowledged as an efficacious approach for alleviating pain, thereby highlighting the therapeutic potential of Chinese medicine massage in pain management and muscle relaxation. Nevertheless, its mechanism has not been fully revealed. Objective Investigate the correlation between the effect of pressing on MTrPs and the regulatory influence of cAMP/PKA/RyR1 on intracellular Ca2+ levels. Methods Sixty male SD rats were randomly divided into two parts: a control group comprising 10 rats that did not undergo modeling, and an experimental group of 50 rats subjected to MTrPs modeling through blunt striking and eccentric exercise targeted at the medial muscle of the left thigh. Conforming to assessment criteria, the experimental group of rats was further subdivided into the model group, press group, press + agonist group, and press + NS group. The model group and the control group of rats received no intervention, while the remaining three groups were subjected to a self-made pressing stimulator. Pressing interventions were performed locally on the MTrPs, once every other day, for a total of seven sessions. Prior to each intervention, rats in the press + agonist group received an abdominal cavity injection of PKA agonist 8-Bromo-cAMP solution, while rats in the press + NS group received an equivalent volume of physiological saline. Before and after interventions, electromyography (EMG), mechanical pain threshold, and soft tissue tension changes on MTrPs were assessed using an electrophysiological apparatus, a soft tissue tension measurement device, and a mechanical pain threshold measurement device, respectively. After assessments, tissue from the medial aspect of the left thigh muscle was extracted from the control group rats, whereas MTrPs tissues were procured from rats in the remaining groups. P-RyR1 expression was evaluated through immunohistochemistry, cAMP levels were quantified using ELISA, and the concentrations of PKA, P-RyR1, and FKBP12 were assessed by Western blotting. Intracellular Ca2+ concentrations were measured employing fluorescence staining. Results (1) Compared to the control group, the model group showed a reduction in mechanical pain threshold, an elevation in soft tissue tension, increased amplitude and frequency of spontaneous electrical activity, elevated levels of cAMP, PKA, and P-RyR1, decreased FKBP12 levels, and an increase in average fluorescence intensity in Ca2+ staining (P < 0.05). (2) Compared to the model group, the press group exhibited an increase in mechanical pain threshold, a decrease in soft tissue tension, a reduction in the amplitude and frequency of spontaneous electrical activity, decreased levels of cAMP, PKA, and P-RyR1, increased FKBP12 levels, and a decrease in average fluorescence intensity in Ca2+ staining (P < 0.05). (3) Compared to the press group, the press + agonist group showed a decrease in mechanical pain threshold, an increase in soft tissue tension, heightened amplitude and frequency of spontaneous electrical activity, elevated levels of cAMP, PKA, and P-RyR1, decreased FKBP12 levels, and an increase in average fluorescence intensity in Ca2+ staining (P < 0.05). Conclusion: Pressing intervention on MTrPs may inhibit cAMP/PKA/P-RyR1, leading to a decrease in intracellular Ca2+ concentration, thereby relaxing abnormal contractile sarcomeres and alleviating pain.

Key words: Pressing, Myofascial trigger points (MTrPs), Pain, Ca2+, cAMP/PKA/P-RyR1