Effects of Electroacupuncture Treatment on Bone Cancer Pain Model with Morphine Tolerance

Objective. To explore the efficacy of electroacupuncture treatment in cancer induced bone pain (CIBP) rat model with morphine tolerance and explore changes of calcitonin-gene related peptide (CGRP) expression in dorsal root ganglion (DRG). Methods. Forty SD rats were divided into five groups: sham, CIBP (B), CIBP + morphine (BM), CIBP + electroacupuncture (BE), and CIBP + morphine + electroacupuncture (BME). B, BM, BE, and BME groups were prepared CIBP model. The latter three groups then accepted morphine, electroacupuncture, and morphine combined electroacupuncture, separately, nine days consecutively (M1 to M9). Mechanical withdraw threshold (MWT) was evaluated. Results. BE group only had differences in M1, M2, and M3 compared to B group (P < 0.01). From M5, BM group showed significantly decreased MWT. Electroacupuncture could obtain analgesic effects only at early stage (M1 to M5). From M5 to M9, BME had the differences with BM group (P < 0.01). IOD value of CGRP in BM and BME was substantially less than in B group. CGRP in BME was significantly lower than that in BM group (P < 0.01). Conclusion. When used in combination with electroacupuncture, morphine could result in improving analgesic effects and reducing tolerance. CGRP may be associated with pain behaviors.