鞘内注射肿瘤坏死因子-α单克隆抗体缓解大鼠骨癌痛的机制

Intrathecal injection of TNF-α antibodies attenuates bone cancer pain in rats

目的:探讨肿瘤坏死因子-α(TNF-α)单克隆抗体对胫骨癌痛模型大鼠痛觉过敏的影响及其可能的机制。方法:选取180~200 g健康雌性SD大鼠32只,随机分成4组(n=8):假手术组、骨癌痛组、TNF-α单克隆抗体组、肿瘤对照组。于左侧胫骨近端骨髓腔注射Walker256肿瘤细胞悬液10μL(2×109)制备大鼠骨癌痛模型,假手术组注射10μL生理盐水。建模后第11天,TNF-α单克隆抗体组连续7 d鞘内注射TNF-α单克隆抗体依那西普8μL,肿瘤对照组连续7 d鞘内注射生理盐水8μL,其余两组不进行鞘内注射。分别于注射肿瘤细胞前,注射后第1、4、7、10、14、17天时测定假手术组和骨癌痛组的机械痛阈。于接种细胞后第17天取大鼠左侧背根神经节(dorsal root ganglion,DRG,腰2-腰5段)测定电压门控钠离子通道1.8(NaV1.8)的蛋白表达。结果:与假手术组相比,骨癌痛组种瘤后第7天,机械痛阈开始下降,第10天出现明显下降(P<0.05),第17天骨癌痛组DRG NaV1.8表达较假手术组明显升高(P<0.05);第11天TNF-α单克隆抗体组大鼠鞘内给药后机械痛阈明显升高,2 h达最高峰,8 h后恢复到给药前水平(P<0.01);重复给药7 d,行为学变化类似一次给药,但机械痛阈值升高程度较单次给药降低。第17天TNF-α单克隆抗体组DRG NaV1.8的表达较肿瘤对照组明显降低(P<0.01)。结论:TNF-α单克隆抗体可能通过抑制DRG神经元上的NaV1.8的高表达从而抑制骨癌疼痛。

Objective: To investigate the analgesic effect of TNF-α monoantibodies on the development of bone cancer pain in rats and its possible mechanism involved. Methods: Thirty-two( n = 32) normal female Sprague-Dawley rats weighting 180- 200 g were randomly divided into 4 groups( n = 8 for each group) : sham operation group,bone cancer pain group,TNF-α monoantibody group and vehicle group.The rat model of bone cancer pain was induced by injection of breast cancer cells( Walker 256) 10 μL( 2× 107cell) into the left proximal tibia bone marrow cavity. Sham operation group was injected by 10 μL normal saline. On the 11 thday after inoculation,TNF-α monoantibody group received intrathecal injection of 8 μL TNF-α monoantibodies( etanercept) once daily for consecutive 7 days. The vehicle group received 8 μL intrathecal injection of normal saline solution for consecutive 7 days,while the rest two groups without intrathecal injection. Mechanical pain threshold was measured before inoculation and on day 1,4,7,10,14,17 after inoculation. On day 17 after inoculation,the left side dorsal root ganglion( DRG,L2 to L5) were harvested to detect the expression of voltage-gated sodium channel NaV1. 8. Results: Compared with sham operation group,the mechanical pain threshold began to decline on day 7 after inoculation andsignificantly decreased on day 10 after inoculation in bone cancer pain group( P < 0. 05). On day 17,NaV1. 8 in the DRGs of bone cancer pain group expressed significantly higher than it in sham operation group( P < 0. 05); On day 11 the mechanical pain threshold increased dramatically in TNF-α antibody group,reached peak at 2 h after drug injection and returned to baseline level at 8 h( P < 0. 01). The behavioristics change was similar to the first dose,but the increase of the mechanical pain threshold was decreased after repeated injection for 7 days. On day 17 the expression of NaV1. 8 in TNF-α monoantibody group was much lower than it in the control group( P < 0. 01). Conclusion: The TNF-α monoantibody reduced bone cancer pain which may be through inhibiting the high expression of NaV1. 8 in DRG.