活化诱导胞嘧啶核苷脱氨酶在骨癌痛-吗啡耐受大鼠脊髓中的表达变化

The expression of activation induced cytidine deaminase in spinal cord of bone cancer pain-morphine tolerance rats

目的测定活化诱导胞嘧啶核苷脱氨酶(AI-CDA)在骨癌痛-吗啡耐受大鼠脊髓中的表达,探讨骨癌痛-吗啡耐受的可能机制。方法选取健康雌性Wistar大鼠30只,体重160~180 g,采用随机数字表法将其分为3组,每组10只(n=10):对照组(Ⅰ组)、骨癌痛组(Ⅱ组)和骨癌痛-吗啡耐受组(Ⅲ组)。在左后肢胫骨上端骨髓腔内接种鼻咽癌HONE1细胞,制备大鼠骨癌痛模型。术后每天测大鼠机械刺激回缩阈值(MWT),于术后第14天对大鼠后肢进行影像学检查。术后第15~21天,上午8:00和下午16:00,Ⅱ组皮下注射等剂量生理盐水,Ⅲ组皮下注射吗啡10 mg/kg。术后第21天取后肢胫骨标本观察病理切片,并取L4~6脊髓组织。采用RT-PCR法测定脊髓组织中AI-CDA mRNA的表达。结果 (1)Ⅲ组大鼠应用吗啡治疗的前3 d MWT值明显高于Ⅱ组,差异有统计学意义(P<0.05),Ⅲ组大鼠应用吗啡的3 d后与前3 d相比MWT值下降,差异有统计学意义(P<0.05);(2)与Ⅰ组比较,Ⅱ组和Ⅲ组术侧胫骨X线片均出现不同程度的骨破坏;(3)两组大鼠术侧胫骨病理切片可见骨髓腔中癌细胞浸润;(4)与Ⅱ组比较,Ⅲ组大鼠脊髓组织中的AI-CDA mRNA表达升高,差异有统计学意义(P<0.05)。结论 AI-CDA在骨癌痛-吗啡耐受组大鼠脊髓中表达增加,可能参与骨癌痛-吗啡耐受机制的形成。

Objective To investigate the possible mechanism of bone cancer pain - morphine tolerance by evaluating spinal cord activation induced cytidine deaminase （ AI - CDA） in rats with bone cancer pain - morphine tolerance. Methods Thirty healthy female Wistar rats （weighing 160 - 180 g） were randomly divided into 3 groups （ n = 10） , control group （ Group Ⅰ ）, bone cancer pain group （ Group Ⅱ ） and bone cancer pain - morphine tolerance group （ Group Ⅲ ）. Nasopharyngeal carcinoma HONE1 cells were inoculated in the left hind tibia bone marrow cavity for rat model of bone cancer pain. After operation, the withdraw mechanical threshold （MWT） was assessed every day, and the damage of bone was assessed with X - Ray on the 14th day after operation. The model rats in Group Ⅲ received subcutaneous injection of morphine （ 10 mg/kg） from the 15th to the 21st day after operation, whereas equal dose of normal saline was applied as placebo in Group Ⅱ. The inoculated tibia and the spinal cord specimen （L4-6） were obtained on 21st day. The AI - CDA mRNA expression was assessed by RT - PCR. Results Compared with Group Ⅱ, during the first 3 days of morphine therapy （15th to 17th day）, the MWT in Group m was significantly reduced （P 〈0. 05）. The MWT in Group m during the first 3 days of morphine therapy （ 15th to 17th day） was significantly higher than that during the last 3 days of morphine therapy （ 18th to 21st day） （P 〈 0. 05 ）. Bone lesions and carcinoma cell inoculation were observed in both Group Ⅱ and Ⅲ according to radiography and pathological study, respectively. Compared with Group Ⅱ , the expression of AI - CDA mRNA was increased in Group Ⅲ （P 〈 0. 05 ）. Conclusion The expression of AI - CDA is increased in spinal cord and may participate in development of bone cancer pain - morphine tolerance.