RESUMO
Objective:To observe any effect of dry needling of myofascial trigger points on substance P and synaptophysin expression in the spinal dorsal horn.Methods:Sixty-four Sprague-Dawley rats were randomly divided into a control group ( n=16) and a model group ( n=48). Myofascial trigger points were induced in the model group by a blunt strike and eccentric running. That group was then randomly divided into a no-treatment group ( n=15), a massage group ( n=16), and a dry needling group (16 rats). The rats in the two treatment groups received 4 weeks of dry needling or Chinese massage. Pressure pain thresholds were recorded before the experiment and after the 4 weeks. The content of substance P and synaptophysin in the spinal dorsal horn were measured using immunoblotting and immunohistochemistry. Results:After the treatment 14 rats (93%) in the model group had trigger points, significantly higher than the 8 rats (50%) in the massage group and the 7 rats (44%) in the dry needling group. After treatment, the average pressure pain thresholds of the no-treatment and massage groups was significantly lower than the control group′s average, while the difference between the dry needling group and the control group was not significant. The average pressure pain threshold had improved significantly in the no-treatment group, the massage group and the dry needling group, and the averages of the massage group and the dry needling group were significantly higher than that of the no-treatment group. The level of substance P was significantly higher in the no-treatment group than in the other three groups and the ratio of substance P to Glyceraldehyde 3-phosphate dehydrogenase (GAPDH)was significantly higher. The substance P: GAPDH ratio of the massage group was significantly higher than that of the control group.Conclusions:Dry needling and massage are effective in relieving myofascial pain, at least in rats. Both can reduce the content of substance P in the spinal dorsal horn.