Silver Needle Thermal Therapy Relieves Pain, Repairs the Damaged Myofascial Fiber, and Reduces the Expression of 5-HT3 Receptors in the Spinal Cord of Rats with Myofascial Pain Syndrome

Background: There is an urgent clinical need to provide a theoretical basis for silver needle thermal therapy to Myofacial pain syndrome (MPS). Objective: This study was conducted to explore the effect of silver needle thermal therapy on myofascial pain syndrome in rats. Methods: MPS rat models were duplicated, and the rats were subsequently divided into model and treatment groups. A normal control group was synchronously set up. No treatment was given to the model group, whereas silver needle thermal therapy was administered to the treatment group. The thermal and mechanical pain threshold, the morphological structure as well as the expression of 5-HT3 receptors in the spinal cord were observed. Results: Rats from the treatment group presented with a significantly higher pain threshold compared to the untreated model group. The myofascial arrangement of the affected part of the model group was disordered, and some muscle fibers were atrophied and deformed. Meanwhile, the myofascial arrangement of the treatment group became more regular than that of the model group. The expression levels of 5-HT3 receptor in the spinal cord of the untreated model group were significantly increased, while being markedly decreased in the treatment group. Conclusions: Silver needle thermal therapy can augment the pain threshold of rats with MPS, repair the damaged myofascial membrane in the rats, and further reduce the expression of 5-HT3 receptors in the spinal cord of the MPS rats.