Effects of Heating-Conduction Dry Needling Therapy on Rats with Chronic Myofascial Pain Syndrome

Objective: This study aimed to investigate the effect of dry needling (DN) with 44 degrees C heating on the pressure pain threshold (PPT) of rats with chronic myofascial pain syndrome (MPS) by regulating the transient receptor potential V1 channel. Methods: A total of 80 rats were divided into 5 groups: A, B, C, D, and E (16 in each group). The rats in Group A recovered naturally, while those in other groups received the DN treatment. The needles were heated to 40 degrees C for the rats in Groups B and E and 44 degrees C for the rats in Groups C and D. In addition, both Groups D and E received local capsaicin injection. PPTs of the gastrocnemius muscle and tolerance time of the plantar hot plate were measured before modeling, 1 day before the intervention, 24 hours after the intervention, and 7 days after the intervention. Results: PPTs of the gastrocnemius muscle for rats with MPS increased 7 days after DN and heating to 40 degrees C. For the rats receiving DN at 44 degrees C heating, PPTs increased 24 hours and 7 days after the intervention. Further, 44 degrees C heating and capsaicin injection improved PPT. DN and 40 degrees C heating followed by capsaicin injection improved PPT. Conclusion: DN and 44 degrees C heating had therapeutic effects on rats with MPS at 24 hours and at 7 days after the intervention. DN and 40 degrees C heating had therapeutic effects 7 days after the intervention. DN and 44 degrees C heating might exert therapeutic effects by regulating the transient receptor potential V1 channel.