骨癌痛大鼠脊髓背角MEK/ERK信号转导通路与CX3CR1的关系

Relationship between MEK/ERK signal transduction pathway and CX3CR1 in spinal dorsal horns in a rat model of bone cancer pain

目的 评价骨癌痛大鼠脊髓背角丝裂原活化蛋白激酶激酶/细胞外信号调节激酶（MEK/ERK）信号转导通路与CX3C趋化因子受体1（CX3CR1）的关系.方法 雌性未交配SD大鼠50只,体重150～ 180 g,采用随机数字表法分为5组（n=10）：假手术组（Ⅰ组）、骨癌痛组（Ⅱ组）、假手术＋ MEK抑制剂U0126组（Ⅲ组）、骨癌痛组＋5％二甲基亚砜（DMSO）组（Ⅳ组）和骨癌痛＋MEK抑制剂U0126组（Ⅴ组）.左侧胫骨骨髓腔内接种Walker 256乳腺癌肿瘤细胞制备大鼠骨癌痛模型.Ⅲ组和Ⅴ组于接种后第10 ～ 12天鞘内注射U0126 10 μg/10 μl,1次/d,Ⅳ组鞘内注射等体积5％DMSO,于接种前及接种后第3、6、9、10天和第11、12天给药后测定机械痛阈.接种后第12天给药后处死大鼠,取L4-6脊髓背角,分别采用免疫组化法和Western blot法检测CX3CR1的表达.结果 与Ⅰ组和Ⅲ组比较,Ⅱ组、Ⅳ组和Ⅴ组大鼠接种后第6～ 12天机械痛阈降低,脊髓背角CX3CR1表达上调（P＜0.01）；与Ⅱ组和Ⅳ组比较,Ⅴ组接种后第10 ～ 12天机械痛阈升高,脊髓背角CX3CR1表达下调（P＜0.01）.结论 脊髓背角MEK/ERK信号转导通路可能通过调节CX3CR1表达参与大鼠骨癌痛的发生和发展.

Objective To evaluate the relationship between MEK/extracellular signal-regulated kinase （ERK） signal transduction pathway and CX3CR1 in the spinal dorsal horns in a rat model of bone cancer pain （BCP）.Methods Fifty female Sprague-Dawley rats,weighing 150-180 g,were randomly divided into 5 groups （n =10 each）：sham operation group （group Ⅰ）,BCP group （group Ⅱ）,sham operation ＋ U0126 group （group Ⅲ）,BCP＋ 5％ dimethyl sulfoxide （DMSO） group （group Ⅳ）,BCP ＋ U0126 （MEK inhibitor） group （group Ⅴ）.BCP was induced by inoculating Walker 256 mammary gland carcinoma cells into the medullary cavity of the left tibia.In Ⅲ and Ⅴ groups,U0126 10 μg/10 μl was injected intrathecally once a day starting from day 10 after inoculation to day 12 after inoculation,while the equal volume of 5％ DMSO was injected in group Ⅳ.Mechanical paw withdrawal threshold （MWT） was measured at 1 day before inoculation （baseline）,3,6,9,and 10 days after inoculation,and after administration on 11 and 12 days after inoculation.The rats were sacrificed after administration on day 12 after inoculation and the L4.6 segments of the spinal cord were removed for determination of CX3CR1 expression in spinal dorsal horns （by Western blot and immunohistochemistry）.Results Compared with Ⅰ and Ⅲ groups,MWT was significantly decreased at 6-12 days after inoculation,and the expression of CX3CR1 in spinal dorsal horns was up-regulated in Ⅱ,Ⅳ and Ⅴ groups （P ＜0.01）.Compared with Ⅱ and Ⅳ groups,MWT was significantly increased at 10-12 days after inoculation,and the expression of CX3CR1 in spinal dorsal horns was down-regulated （P ＜ 0.01）.Conclusion MEK/ERK signal transduction pathway in the spinal dorsal horns is involved in the development and maintenance of BCP in rats possibly through regulating the expression of CX3CR1.