Effects of electroacupuncture intervention on expression of cyclooxygenase 2 and microglia in spinal cord in rat model of neuropathic pain.

OBJECTIVE: To investigate the effect of electroacupuncture (EA) treatment on the expression of cyclooxygenase (COX) 2 and microglia in spinal cord by using rat model of neuropathic pain, and to probe into the relationship between COX 2 and microglia.

METHODS: The rats were randomly divided into 6 groups, including normal control group, model group, sham group, EA 1 group (distant acupoints + local acupoints), EA 2 group (local acupoints), and EA 3 group (distant acupoints). Thermal withdrawal latencies were evaluated at 1 day preoperatively and 3, 5 and 7 days postoperatively. At 7 days postoperatively, the spinal COX 2 mRNA was detected by reverse-transcription polymerase chain reaction. Double immunofluorescent staining technology was applied to screen and verify the relationship between altered COX 2 and microglia.

RESULTS: Compared with the model group, thermal withdrawal latencies increased after EA treatment (P<0.01). The expressions of COX 2 mRNA were up-regulated in spinal cord of rat on day 7 after surgery (P<0.05). Compared with the model group, EA stimulation (EA 1 and EA 2 groups) reversed the up-regulation of COX 2 mRNA expression (P<0.05). EA 1 and EA 2 groups might have better treatment effect compared with the EA 3 group. Fluorescent images displayed COX 2 and microglia expressed at common areas.

CONCLUSIONS: EA was effective in analgesic and anti-inflammatory. EA has decreased the expression of spinal COX 2 mRNA in the trend of the therapeutic effect of "distant acupoints + local acupoints", and "local acupoints" intervention may be superior to that of "distant acupoints" intervention. Microglia may be related to the formation of COX 2.