左旋多巴干预激素性股骨头坏死中骨细胞凋亡的实验研究

An experimental study of anti-apoptotic effect of Levodopa on steroid-induced osteonecrosis of the femoral head in rabbits

目的探讨左旋多巴对激素性股骨头坏死中骨细胞凋亡的影响。方法健康成年中国大耳白兔44只，随机分为三组。模型组，15只，经耳缘静脉注射10μg／kg脂多糖，24h后于右侧臀肌注射20mg／kg甲基泼尼松龙，共3次，每次间隔24h。治疗组，15只，与模型组相同方法建模，注射完成后当13开始口服左旋多巴，剂量0．4g·kg^-1·d。对照组，14只，于相同时间点注射等量生理盐水。制模后6、8周，各组分别处死7只，处死前行双髋关节X线摄片及MR检查，处死后取双侧股骨头标本，行HE染色并用TUNEL法测定细胞凋亡，观察组织病理学改变并进行细胞凋亡分析。制模后8周，采血测定3组兔子血清中胰岛素样生长因子-1（insulin-like growth factor-1，IGF-1）水平。结果模型组X线片显示股骨头骨密度不均匀，可见有囊性变或硬化骨；HE染色显示骨小梁变细、稀疏、连续性中断，骨髓组织脂肪变性，空骨陷窝明显增多；TUNEL检测显示骨小梁内存在大量凋亡骨细胞。而治疗组X线片显示股骨头接近正常，骨密度均匀增高；组织病理学显示骨小梁连续性完整，制模后6、8周的空骨陷窝率分别为13．33％±3．06％及25．97％±6．29％，低于模型组的21．44％±4．77％及33．86％±8．38％（P〈0．01）；骨细胞凋亡指数分别为74．93‰±14．32‰及120．67‰±13．13％0，低于模型组的102．56‰±18．96‰及202．02‰±18．99‰（P〈0．01）；制模后8周治疗组动物血清IGF-1含量为（14．78±2．37）ng／ml，高于模型组的（10．12±2．49）ng／ml（P〈0．01）；统计学分析显示模型组骨细胞凋亡指数与空骨陷窝率呈明显正相关（r=0．74，P〈0．01）。结论左旋多巴可以减少激素诱导的骨细胞凋亡，减少股骨头坏死的发生。而左旋多巴通过体内代谢促进IGF-1的合成及释放可能是其预防及治疗激素性股骨头坏死的生物学途径之一。

Objective To study the anti-apoptotie effects of Levodopa on osteonecrosis of the femoral head induced by methylprednisolone （MPS）. Methods Forty-four rabbits were randomly divided into 3 groups. The model group （n=15） was injected with lipopolysaceharide （LPS, 10μg/kg） and then MPS （20 mg/kg） was given 3 times with 24 h interval. The treatment group （n=15） was firstly treated by the same methods as the model group, then was administered Levodopa （0.4 g·kg^-1· d^-1） orally after the last injection of MPS. The control group （n=14） was injected with sodium chloride alone. On the 6th and 8th week after mod- eling, radiography and MR images were taken in 7 rabbits of each group, specimens taken from the femoral heads were obsm＇ved by HE stain and TUNEL analysis was made. Blood samples were taken for detection of insulin-like growth factor-1（IGF-1） on the 8th week. Results On the 6th and 8th week, the average percentage of empty osteocyte lacunae in the treatment group （13.33%±3.06%, 25.97%±6.29%） was significantly lower than that of the model group （21.44%±4.77%, 33.86%±8.38%, P〈0.01）, and the average apoptosis index in the treatment group （74.93‰±14.32‰, 120.6‰±13.13‰） was significantly lower than that of the model group （102.56‰±18.96‰, 202.02‰±18.99‰, P〈0.01）. On the 8th week, the level of IGF-1 in the treatment group was （14.78±2.37） ng/ml, which was higher than that of the model group obviously （10.12± 2.49） ng/ml （P〈0.01）. Conclusion The Levodopa can decrease apoptosis of osteoeytes and effectively prevent the progress of steroid-induced osteoneerosis of the femoral head.