OBJECTIVETo observe the dose-effect relationship of electroacupuncture of different current intensities combined with Morphine of different dosage on alleviating the rats' tibial cancer pain, and explore the possible mechanism, which could provide the experiment basis for alleviating the tibial cancer pain by electroacupuncture combined with Morphine.

METHODSOne hundred female Wistar rats were randomly divided into a normal group, a model group and eight treatment groups, 10 cases in each group. The rats in the treatment groups were treated by combined therapies of electroacupuncture of different intensities with 2 Hz /100 Hz dense-disperse wave on "Jiaji"(EX-B 2)and different dosage Morphine in 2 factor 3 level conditions, once a day for 6 days. The pain thresholds were observed before the treatment and 0 min, 1 h, 2 h and 5 h after the first treatment as well as after 3 and 6 times of treatments. The glial fibrillary acidic protein (GFAP) expression was determined by immunohistochemical method.

RESULTSThe rats' pain thresholds were significantly increased with electroacupuncture of 2 mA and 1 mA (all P < 0.01) on the 0 min, 1 h and 2 h of the first treatment, between which there were no significant differences (all P > 0.05). The pain threshold was still increased by electroacupuncture of 2 mA on the 5 h of the treatment (P < 0.01), while that of 1 mA failed to take effect (P > 0.05). After 3 and 6 times of treatments, both electroacupuncture of 2 mA and 1 mA had the effect of increasing the pain threshold (all P < 0.01), and the effect of 2 mA was superior to that of 1 mA (P < 0.05), had the synergistic effect with 5 mg/(kg x d) Morphine (P < 0.05). After 6 times of treatments, both electroacupuncture of 2 mA and 1 mA could inhibit the expression of GFAP (both P < 0.01), and there was no significant difference between them (P > 0.05). Both of 5 mg/(kg x d) and 2.5 mg/(kg x d) of Morphine, however, didn't bring about inhibition effect (P > 0.05).

CONCLUSIONThere is a does-effect relationship on electroacupuncture of different current intensity for alleviating the tibial cancer pain in rats. The electroacupuncture with 2 mA, which is better than that with 1 mA, has the synergistic effect with 5 mg/(kg x d) of Morphine. The electroacupuncture can inhibit the expression of GFAP to cooperate with Morphine for the purpose of alleviating the rats' tibial cancer pain.