强力霉素治疗兔实验性骨关节炎的疗效及其作用机制的研究

Effects and mechanisms of intraarticular injection of doxycycline on experimental osteaarthritis in rabbits

目的:研究强力霉素局部给药对骨关节炎软骨的影响及其作用机制。方法:通过关节内注射木瓜蛋白酶,建立家兔膝关节炎模型。每日关节穿刺给予2、4 mg强力霉素,共4周,观察指标包括软骨大体形态,软骨Mankin's评分,软骨细胞基质金属蛋白酶-13(MMP-13)表达,关节液中NO含量和一氧化氮合酶(NOS)活性。结果:与正常对照组相比,模型对照组软骨面粗糙,见大量裂隙,局部纤维覆盖,边缘骨赘多,Mankin's评分显著增高,MMP-13表达、NO含量和NOS活性均显著升高(P<0.01)。给予2 mg强力霉素后,软骨面粗糙稍好转,裂隙数量减少,边缘骨赘小而少,Mankin's评分显著降低,MMP-13表达、NO含量和NOS活性均显著降低(P<0.01)。给予4 mg强力霉素后,上述改变更加显著。结论:强力霉素关节腔内给药对家兔骨关节炎软骨退变起到明显缓解效果,且其作用有剂量相关性,作用机制与抑制NO产生、NOS活性和MMP-13表达有关。

AIM: To investigate the effects and mechanisms of intraarticular injection of doxycycline on experimental osreoarthritis in rabbits. METHODS: An animal model of osteoarthritis in knee of rabbits was established by intraarticular injection of papain. 2 mg or 4 mg of doxycycline was injected (intraarticular) once a day in four weeks. The degeneration of articular cartilage, Mankin s marks of the cartilage tissue, the expression of MMP-13, the release of nitricoxide (NO) and the activity of total nitricoxide synthase (NOS) and inducible nitricoxide synthase (iNOS) of the joint fluid were tested subsequently . RESULTS: In the osteoarthritis model group, the Mankin s marks and the expression of MMP-13 observably increased, and spectrophotometric analysis showed the high concentration of the release of NO and high activity of NOS and iNOS in the joint fluid (P < 0.01) . The cartilage surface was irregular with an abun-dance of fissures visibly by the naked eye, and the wear and degeneration of cartilage including osteophytes were found. Injection of 0.2 mg·d-1 doxycycline obviously decreased the Mankin's marks, the expression of MMP-13, the contents of NO and the activity of NOS and iNOS (P < 0.01) , and it alleviated the wear and degeneration of cartilage including the fissures and the formation of the osteophyte in the same time. Injection of 0.4 mg·d-1 doxycycline more obviously strengthened the changes above. CONCLUSION: Intraarticular injection of doxycycline can delay the process of osteoarthritis, and the effect is related to the dosage of the doxycycline: better effect followed larger dosage. The mechanisms are related to inhibiting the level of NO, the activity of total NOS and iNOS activity and the expression of MMP-13.