Effect of electroacupuncture treatment on pain behavior and calcitonin-gene related peptide expression in cancer induced bone pain-morphine tolerance rat model

Objective To explore the efficacy of electroacupuncture treatment in cancer induced bone pain (CIBP)-morphine tolerance rat model and the expression of calcitonin-gene related peptide(CGRP) immunohistochemisty in dorsal root ganglion (DRG). Methods Forty SD rats were divided into four groups: sham group, CIBP+ morphine tolerance group(BM), CIBP+ electroacupuncture group (BE), and CIBP+ morphine tolerance+ electroacupuncture group (BME). BM, BE and BME groups were prepared CIBP model by carcinoma cell tibia implanted.After six days, the three CIBP groups accepted treatment of morphine, electroacupuncture, and morphine combined electroacupuncture, separately, nine days continuously. Acupoints were selected Zusanli(ST36) and Sanyinjiao(SP6). 50% mechanical withdraw threshold was evaluated by mechanical stimulation.CGRP expression in dorsal root ganglion was detected by immunohistochemisty. Results After five days of electroacupuncture treatment, pain threshold was (10.9±0.8)g in BME group, (8.7±0.6)g in BM group and (6.2±0.9)g in BE group.The results had significant statistic differences (P<0.01, separately). IOD value of CGRP expression in dorsal root ganglion was 9026.5±1827.4 in BME group, compared with 14803.1±2086.7 in BM group and 15730.6±2712.5 in BE group (P<0.01, separately). Results Electroacupuncture can relieve CIBP-morphine tolerance rat pain behavior. The mechanism is related to inhibiting CGRP overdue expression in DRG. Key words: Electroacupuncture; Cancer induced bone pain; Morphine tolerance; Calcitonin-gene related peptide