兔伸直型膝关节挛缩模型中肌源性挛缩的病理特征及其机制研究

Pathological characteristics and mechanism of myogenic contracture in rabbit model of knee extension contracture

目的探讨在兔伸直型膝关节挛缩模型中肌源性挛缩的病理特征及其可能机制。方法选取新西兰白兔30只,根据固定时间,随机分为以下5组(n=6):对照组(I-0,不进行任何处理)、固定1周组(I-1,左膝关节伸直位固定1周)、固定2周组(I-2,左膝关节伸直位固定2周)、固定4周组(I-4,左膝关节伸直位固定4周)和固定8周组(I-8,左膝关节伸直位固定8周)。然后通过检测固定后膝关节挛缩角度、股直肌Masson染色、低氧诱导因子(HIF)-1α和转化生长因子(TGF)-β1的蛋白表达水平,分析各组结果差异。结果在固定8周内,固定组的肌源性挛缩角度在4周内随着固定时间的延长而增加,但4周后I-4组和I-8组相比差异无统计学意义。Masson染色结果提示,股直肌横截面积在固定4周内不断降低,而胶原纤维沉积占比在固定4周内不断升高,但固定4周后I-8组与I-4组相比,股直肌横截面积的降低和胶原纤维沉积占比的增加差异均无统计学意义。股直肌HIF-1α蛋白表达水平在固定4周内不断升高,但4周后I-4组和I-8组相比差异无统计学意义;2周内TGF-β1蛋白表达增加差异有统计学意义,2周后每个固定组相比差异无统计学意义。结论在兔伸直型膝关节挛缩模型中肌源性挛缩的病理特征主要为肌纤维化和萎缩的时间依赖性改变,并且其机制可能与HIF-1α和TGF-β1高表达有关。

Objective To explore the pathological characteristics of myogenic contracture and its possible mechanism in rabbit model of knee extension contracture.Methods According to the immobilization time,thirty New Zealand white rabbits were randomly divided into 5 groups(n=6):control group(I-0,without any treatment),1-week immobilization group(I-1,with left knee joint complete extending immobilization for 1 week),2-week immobilization group(I-2,with left knee joint complete extending immobilization for 2 weeks),4-week immobilization group(I-4,with left knee joint complete extending immobilization for 4 weeks)and 8-week immobilization group(I-8,with left knee joint complete extending immobilization for 8 weeks).At the end of each immobilization time point,the rabbits were killed,and then the myogenic contracture and arthrogenic contracture were analyzed by detecting the angle of knee joint contracture after immobilization.The cross-sectional area of rectus femoris muscle fiber was analyzed by Masson staining.The protein expression levels of hypoxia inducible factor-1α(HIF-1α)and transforming growth factor-β1(TGF-β1)were analyzed by Western blot.Results During the 8 weeks,the angle of myogenic contracture in the immobilization group increased with the immobilization time within 4 weeks,but there was no significant difference between I-4 group and I-8 group after 4 weeks.Masson staining results showed that the cross-sectional area of rectus femoris decreased continuously within 4 weeks of immobilization,while the proportion of collagen fiber deposition increased continuously within 4 weeks after immobilization.However,there was no significant difference in the reduction of cross-sectional area of rectus femoris and the increase of collagen fiber deposition between I-8 group and I-4 group after 4 weeks of immobilization.The expression level of HIF-1αprotein increased continuously within 4 weeks after immobilization,but there was no significant difference in the expression level of HIF-1αprotein between I-4 group and I-8 group after 4 weeks immobilization;the expression of TGF-β1 protein increased significantly within 2 weeks,but there was no significant difference between the each group after 2 weeks immobilization.Conclusion The muscle fibrosis and atrophy are mainly pathological features of myogenic contracture in rabbit model of knee extension contracture,which is time-dependent change,and the mechanism may be related to the high expression of HIF-1αand TGF-β1.