脊髓背角P2Y1受体在大鼠骨癌痛形成中的作用

Role of P2Y1 purinergic receptors in the spinal cord in a rat model of bone cancer pain

：目的 评价脊髓背角P2Y1受体在大鼠骨癌痛形成中的作用.方法 鞘内置管成功的雌性SD大鼠90只,体重150～180 g,随机分为5组（n=18）：假手术组（Ⅰ组）、骨癌痛组（Ⅱ组）、假手术＋P2Y1受体特异性拮抗剂MRS 2179组（Ⅲ组）、骨癌痛＋生理盐水组（Ⅳ组）和骨癌痛＋MRS2179组（Ⅴ组）.采用胫骨骨髓腔内接种Walker256乳腺癌细胞的方法制备骨癌痛模型.Ⅲ组和Ⅴ组术后第7～9天鞘内注射MRS2179 100 pmol/10μl,1次/d,Ⅳ组注射等体积生理盐水.于术前及术后第3、7、9、12、15、18天给药后测定机械痛阈,于术后第9天测定机械痛阈后处死6只大鼠,取L4～6脊髓背角,测定P2Y1受体和磷酸化细胞外信号调节蛋白激酶1/2（p-ERK1/2）的表达.结果 与Ⅰ组和Ⅲ组比较,Ⅱ组、Ⅳ组和Ⅴ组术后第7～18天机械痛阈降低,P2Y1受体和p-ERK1/2表达上调（P＜0.01）;与Ⅱ组和Ⅳ组比较,Ⅴ组术后第9～18天机械痛阈升高,P2Y1受体和p-ERK1/2表达下调（P＜0.01）.结论 脊髓背角P2Y1受体参与了大鼠骨癌痛的形成,可能与ERK1/2的激活有关.

Objective To investigate the role of P2Y1 purinergic receptors in the spinal cord in a rat model of bone cancer pain. Methods Ninety female SD rats weighing 150-180 g were randomly divided into 5 groups （n = 18 each）： Ⅰ group sham operation; Ⅱ group bone cancer pain; Ⅲ group sham operation ＋ MRS2179 （a specific P2Y1 purinergic receptor antagonist）; Ⅳ group BCP ＋ vehicle （group NS）; Ⅴ group BCP＋ MRS2179.Bone cancer pain was induced by inoculating Walker 256 mammary gland carcinoma cells into medullary cavity of tibia. In group Ⅲ, Ⅳ, Ⅴ MRS2179 100 pmol/10 μl or NS 10 μl was injected intrathecally once a day for 3 days starting from the 7th day after operation. Mechanical pain threshold to von Frey stimuli was measured before and every other day after operation. The anirnals were sacrificed on the 9th day after operation. The L4-6 segment of the spinal cord was removed for detection of expression of P2Y1 receptor and phosphorylated extracellular signal-regulated protein kinase 1/2 （p-ERK1/2） in the spinal dorsal horn. Results P2Y1 receptors and p-ERK1/2 coexisted in spinal dorsal horn. Inoculation of cancer cells into tibia significantly decreased mechanical pain threshold at postoperative day 6-18 and increased the expression of P2Y1 receptor and p-ERK1/2 on the 9th day after operation in group Ⅱ and Ⅳ as compared with group Ⅰ . Intrathecal MRS 2179 significantly increased pain threshold and decreased expression of P2Y1 receptor and p-ERK1/2 in group Ⅴ compared with group Ⅱ and Ⅳ. Conclusion P2Y1 receptors in the spinal cord are involved in the development of bone cancer pain, which may be related to the activation of ERK1/2.