大麻素受体2在胫骨癌痛大鼠脊髓的表达及意义

目的探讨大麻素受体2（CB2）在胫骨癌痛大鼠脊髓的表达及其在癌痛产生和维持中的作用。方法 雌性SD大鼠42只,体重160～180g,随机分为5组：对照组（C组）、假手术组（S组）、骨癌痛组（BCP组）、DMSO（二甲基亚砜）组（D组）和CB2选择性拮抗剂AM630组（A组）。采用右侧胫骨干骺端骨髓腔内注射5μlWalker256（4×105）乳腺癌细胞制备大鼠胫骨癌痛模型,于接种后第7d从S组和BCP组分别随机选取6只,同C组的大鼠一起处死取脊髓,采用免疫印迹技术观察脊髓CB2的表达,在接种后的第1、2及第3天按照分组D组和A组分别鞘内注射DMSO0.15μl和溶于1%DMSO的AM63015μg。分别于注射肿瘤前1d、注射后的第1、3、5、7、14、21d（T0～6）测定机械痛阈和热痛阈。结果免疫印迹显示C组大鼠脊髓基本没有CB2的表达,与C组及S组相比,BCP组接种后第7d脊髓CB2表达水平升高。鞘内注射AM630癌细胞后大鼠接种后肢提前出现机械痛觉过敏现象。结论脊髓CB2参与大鼠胫骨癌痛的产生和维持。

The expression and significance of CB2 in the spinal of rat tibial bone cancer pain model

Objective To investigate the expression of CB2 in the spinal of rat tibial bone cancer pain, then to discuss its role in the generation and maintenance of bone cancer pain. Methods Forty-two female Sprague-Dawley rats weighing 160~180g were randomly divided into five groups： naive group （C）, shame group （S）, bone cancer pain group （BCP）, DMSO group （D） and AM630 group（A）. Bone cancer pain was induced by implantation of Syngeneic Walker 256 mammary gland carcinoma cells into the intramedullary space of right tibia. Six rats were killed on the 7th day after inoculation in each group of C, S, BCP and the lumbar segment of the spinal cord were removed for determination of the expression of CB2 in the spinal dorsal horn by western blot. On the 1d, 2d, 3d after inoculations, group D and group A accepted intrathecal injection of DMSO and 15μg AM630 which dissolved in 0.15μl DMSO, respectively. The paw withdrawal threshold to mechanical stimuli and paw withdrawal latency to thermal stimuli were measured before inoculation and at day 1, 3, 5, 7, 14, 21d （T0~6） after inoculation respectively. Results Western blot analysis showed that group C hardly expressed CB2. Compared with group C and group S, CB2 expression in the spinal cord was significantly increased at the 7th after inoculation （P0.05）. Mechanical hyperalgesia would appear early after intrathecal injection AM630. Conclusion CB2 in spinal cord may participate and transmitting algesthesia message and the forming of hyperalgesia in bone cancer pain.