中文摘要：

目的动态观察脊髓损伤（SCI）后大鼠腓肠肌（GM）的病理特征变化及Young’s模量的改变，为腓肠肌硬度评估提供新方法。方法54只sD雄性大鼠（体质量260～280g）按随机数字表法分配至正常对照组（6只），SCI模型组（2、4、8及12周亚组，各12只）。各组大鼠在相应时间点完成踝关节肌张力（MAS）评估、下肢运动功能（BBB）评估、GM硬度评估（Young’s模量）、GM的一般病理项目测量（肌重）、ATP酶染色及MyHC电泳分析。结果造模后除去死亡与体质量过轻过重的老鼠，每组均为6只。与正常对照组（0周）相比，SCI模型组各亚组（2、4、8及12周）大鼠踝关节MAS评分增高[（1．5±0．8）分～（0．8±0．7）分]（P≤0．05），BBB评分下降[（3．2±1．0）分～（7．2±1．3分）]（P≤O．05）；踝背伸时GM的Young’s模量明显增高[（25．1±2．4）kPa-（37．4±5．5）kPa]，P≤0．05）；GM肌重明显下降[（0．9±0．2）g～（1．2±0．1）g]，P≤0．05），ATP酶染色后I型纤维占比明显下降，Ⅱ型肌纤维占比明显升高（P≤O．05），MyHC电泳显示MyHC—II型比例增多，MyHC—I型比例下降（P≤0．05）。结论SCI大鼠GM不仅发生病理特征显著性改变，其肌肉硬度也发生明显改变。超声弹性成像技术可用来评估SCI大鼠痉挛GM硬度改变。

英文摘要：

Objective To investigate the pathological characteristic of gastrocnemius （GM） and quantitatively assess GM tissue stiffness in spinal cord injury （SCI） rat models; to explore the novel method in evaluation of GM stiffness. Methods A total of 54 SD male rats （ weight 260 - 280 g） were allocated into normal control group （0 w） and model groups （2, 4, 8 and 12 w） in this study. Complete SCI （T10 level） was applied in model groups. At the above different time points, Modified Ashworth Scale （MAS） was used to assess the GM spasticity ; Basso, Beattie, and Bresnaban Locomotor Rating Scale （BBB） was used to assess the movement ability of lower limb. GM stiffness was assessed with shear wave sonoelastography technology in these groups. All GM at right side of rats was further checked by pathological examinations （ muscle weight, ATP staining, myosin heavy chain （ MyHC ） electrophoretic analysis ） after sonoelastography imaging examinations. Results After removing the overweight and underweight rat models which were alive, six rats were included in each group. There were some pathologic changes in GM in SCI rat models. Compared with normal control group, data from model groups showed ankle dorsiflexors MAS （ 1.5 ± 0. 8 - 0. 8 ± 0. 7 score） was increased （ P ≤ 0. 05 ） , BBB scores of lower limb （ 3.2 ± 1.0 - 7.2 ± 1.3score） were decreased （P≤0. 05）. The GM elastic modulus was increased at dorsiflexion location in model group （25.1 ± 2.4 - 37.4 ± 5.5 kPa, P ≤0. 05 ） ; GM weights were decreased, ratio of type I fibers was decreased and ratio of type Ⅱ fibers was increased in GM. Compared with normal control group, MyHC- Ⅰ was decreased, while MyHC-Ⅱ was increased according electrophoretie analysis. Conclusions Both pathological characteristic and muscle stiffness of GM change after SCI. Shear-wave sonoelastography technology can be used to assess the GM stiffness in SCI rat models.