To evaluate the analgesic effect of salvianolic acid C on bone cancer pain (BCP) and the role of spinal astrocytes and inflammatory responses in rats.

Thirty female Sprague-Dawley rats, weighing 180-200 g, were divided into 3 groups (n=10 each) using a random number table method: sham operation group (group S), group BCP and salvianolic acid C group (group SalC). BCP was induced by inoculating Walker 256 mammary gland caicinoma cell suspension (about 4×10⁷ cells) 10 μl into the medullary cavity of the right tibia.The equal volume of sterile phosphate buffer solution was injected instead in group S. On 12-21 days after beginning of establishing the model, 1 mg/ml SalC solution 20 mg·kg^-1·d^-1 were intraperitoneally injected in group SalC, while the equal volume of normal saline was injected in group BCP.The mechanical paw withdrawal threshold (MWT) and walking score were measured on 1 day before establishing the model (T₀), on 3th, 6th and 9th days after beginning of establishing the model (T_1-3), and at 6 h after administration on 12th, 15th, 18th and 21st days after beginning of establishing the model (T_4-7). The animals were sacrificed after the last measurement of pain threshold, and the L_4-6 segments of the spinal cord were removed for determination of the expression of glial fibrillary acidic protein (GFAP) protein (by Western blot) and expression of GFAP, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and IL-1β mRNA (by fluorescent quantitative real-time polymerase chain reaction).

Compared with group S, the MWT at T_2-7 and walking score at T_3-7 were significantly decreased, and the expression of GFAP protein and mRNA was up-regulated, and the expression of TNF-α, IL-6 and IL-1β mRNA was up-regulated in BCP and SalC groups (P<0.05). Compared with group BCP, the MWT at T_4-7 and walking score at T_5-7 were significantly increased, and the expression of GFAP protein and mRNA was down-regulated, and the expression of TNF-α, IL-6 and IL-1β mRNA was down-regulated in group SalC (P<0.05).

Salvianolic acid C can alleviate BCP in rats, and the mechanism may be related to inhibiting activation of spinal astrocytes and attenuating inflammatory responses.

Salviol; Pain; Bone neoplasms; Astrocytes; Inflammation