The present study was systematically carried out to observe the effects of elect roacupuncture on neuropathic pain and to investigate the preliminary molecular m echanisms of electroacupuncture analgesia in neuropathic pain by using behaviora l and in situ hybridization methods. The results were as follows: In CCI (chronic constriction injury) rats

hyperalgesia score is used as the sig n of neuropathic pain. Pain threshold after immediate electroacupuncture(EA) and the next day after repeated electroacupuncture was observed to investigate effe ct of electroacupuncture on hyperalgesia score of neuropathic pain. It showed th at on day 7 after CCI operation

controlateral EA of "Huantiao"(GB 30) and "Y anglingquan"(GB 34) acupoints (4 and 20 Hz alternately

2.5 sec and 5 sec respe ctively

≤1 mA

30 min) immediately and significantly increased hyperalge sia score in neuropathic pain rats. When EA was given (the same as the former) o n day 9

11

13

16

18

20

23

25

27 after CCI operation

hyperalgesia score was obse rved the following day. The more EA was given

the higher the hyperalgesia score became

which showed an accumulative effect. It is thus suggested that EA ca n produce immediate analgesia in neuropathic pain rats

and have ac cumulative effects. Based on these

we will continue to investigate the expression of POMC mRNA in arcuate hypothalamic nucleus and the expression of ppOFQ mRNA in dorsal horn in neuropathic pain rats after EA treatment. Results showed that the expression of POMC mRNA in arcuate hypothalamic nucleus was increased significantly on day 7 a fter CCI operation

and had downward trend later. On day 7 after operation

the POMC mRNA expression was enhanced immediately and markedly 8 hours after one E A treatment. After repeated EA stimulation in neuropathic pain rats

the POMC mRN A expression was continually and obviously increased. These results suggested th at the continual increase of brain POMC mRNA expression might be one of the impo rtant factors involving EA analgesia in ne uropathic pain. Results also showed that the expression of ppOFQ mRNA in ipsilateral dorsal horn was decreased significantly on day 7 after CCI operation

and recovered a littl e later on. On day 7 after CCI operation

the ppOFQ mRNA expression in ipsilater al dorsal horn was immediately and markedly enhanced 8 hours after one EA treatm ent. After repeated EA stimulation in neuropathic pain rats

the ppOFQ mRNA expr ession was continually and obviously increased to normal. These results suggeste d that the recovery of spinal ppOFQ mRNA might be another important mechanism of EA analgesia in neuropathic pain.