被动运动对脊髓损伤大鼠后肢运动功能及骨骼肌的影响

目的　观察被动运动促进脊髓损伤（Spinal cord injury, SCI）大鼠后肢运动功能恢复和改善骨骼肌萎缩的影响；探讨脑源性神经营养因子（BDNF）对被动运动促进功能恢复和延缓肌萎缩的作用。 方法　将36只健康成年雌性SD大鼠随机分假手术组、对照组（未行运动）,被动运动组（损伤1周后开始被动运动，共4 周）。采用改良的Allen’s法制备SCI模型。术后1 d和1、2、3、4 周通过大鼠Basso-Beattie-Bresnahan(BBB)行为学评分检测各组大鼠的运动功能；术后5周，采用HE染色比较各组大鼠脊髓组织病理变化，观察大鼠后肢腓肠肌的横断面积、直径和形态变化。测量腓肠肌湿重、体重和肌湿重/体重，评价肌萎缩情况；采用Western blots检测腓肠肌中BDNF的表达变化。 结果　被动运动组运动功能明显高于对照组（P<0.05）。损伤5周后，对照组和被动运动组的脊髓组织失去正常形态，神经元数量减少，损伤区大量空洞形成，而被动运动组的变化较对照组轻。对照组腓肠肌湿重、肌湿重/体重、横断面积和直径下降，被动运动组改善上述肌萎缩情况（P<0.05）。与假手术组相比，对照组和被动运动组BDNF表达量增加（P<0.05），其中被动运动组高于对照组（P<0.05）。 结论　被动运动可能是通过增加SCI后BDNF表达促进损伤后运动功能的恢复，并能有效改善失神经性肌萎缩。

Effect of passive movement on hind limb motor function and skeletal muscle in rats with spinal cord injury

Objective　To observe the effect of passive motion on the recovery of the motor function of the hind limbs and the improvement of the skeletal muscle atrophy in the rats with spinal cord injury(SCI), and to explore the effect of brain derived neurotrophic factor (BDNF) on the functional recovery of passive motion and the treatment of muscular atrophy.　Methods　36 healthy adult female SD rats were randomly divided into a sham operation group, a control group (no exercise), and a passive exercise group (1 week after injury, passive motion, for 4 weeks). A modified Allen’s method was used to establish the spinal cord injury model. The rats' motor function was detected by the Basso-Beattie-Bresnahan (BBB) behavior score of rats at 1 d, 1, 2, 3, 4, 5 week after SCI. HE staining was used to compare the pathological changes of spinal cord tissue in each group, and the cross section area, diameter and morphology of the gastrocnemius muscle in the hind limbs of the rats were observed. The wet weight of gastrocnemius, weight, and muscle weight / weight were measured. The expression of BDNF in the gastrocnemius muscle was detected by Western blots. Results　The motor function of passive movement group was significantly higher than the control group (P<0.05). After SCI 5 weeks, the spinal cord tissue of the control group and passive movement group lost normal morphology, the number of neurons were reduced, a large number of cysts were formed in lesion area, but passive movement group were better than the control group when it came to the above mentioned parameters. The gastrocnemius muscle weight, muscle weight / body weight, cross-sectional area and diameter were smaller in the control group. Therefore the passive movement group improved the situation of muscle atrophy (P<0.05). Compared with sham operation group, the expression of BDNF in control group and passive movement group gastrocnemius muscle were increased (P<0.05), and it was higher in gastrocnemius muscle of the passive movement group than that of the control group (P<0.05).　Conclusion　Passive motion might promote the recovery of motor function and improve the atrophy of denervated muscle by increasing BDNF in the gastrocnemius muscle after SCI.