RESUMO
OBJECTIVE: To observe the effect of medicated-catgut embedding at "Changqiang"(GV 1) on regional pain reaction and expression of p 38 MAPK in the dorsal horn of spinal cord in anus incisional pain rats, so as to explore its analgesic mechanism. METHODS: Forty male SD rats were randomly divided into control, model, GV 1-embedding and sham acupoint embedding groups (n=10 rats in each group). The anus incisional pain model was established by making a radial incision (about 10 mm length) at the left lithotomy position of the anus with a surgical knife, and the mechanical pain threshold (PT) was measured by using a Von Frey before and 4, 8, 12, 24 h after operation. The medicated-catgut (about 12.5 mm length/kg body weight) was implanted in the subcutaneous tissue of GV 1 region. The immunoactivity of p 38 MAPK was determined by immunohistochemistry. RESULTS: Compared with the control group, the mechanical PTs were significantly decreased 4, 8, 12 and 24 h after operation both at the site of incision and about 15 mm proximal to the site of incision in the model group (P<0.05), and the immunoactivity of phosphorylated (p)-p 38 MAPK in the superficial layer of dorsal horns of lumbar spinal cord was significantly increased(24 h)after operation(P<0.05). Compared with the model group, the PTs were significantly increased 8, 12 and 24 h after operation at the site of incision, and 12 h and 24 h at the site about 15 mm proximal to the incision region (P<0.05), and the immunoactivity level of p-p 38 MAPK was significantly down-regulated in the GV 1-embedding group (P<0.05). No significant changes were found in the PT and p-p 38 MAPK immunoactivity levels in the sham acupoint embedding group (P<0.05). CONCLUSIONS: Medicated-catgut embedding at "Changqiang"(GV 1) has an analgesic effect in anus incisional pain model rats, which may be related to its effect in down-regulating the expression of p 38 MAPK in the dorsal horn of lumbar spinal cord.
