Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, USA.
J Neurotrauma. 2011 Feb;28(2):299-309. doi: 10.1089/neu.2010.1594. Epub 2011 Jan 9.
Activity-based therapies such as passive bicycling and step-training on a treadmill contribute to motor recovery after spinal cord injury (SCI), leading to a greater number of steps performed, improved gait kinematics, recovery of phase-dependent modulation of spinal reflexes, and prevention of decrease in muscle mass. Both tasks consist of alternating movements that rhythmically stretch and shorten hindlimb muscles. However, the paralyzed hindlimbs are passively moved by a motorized apparatus during bike-training, whereas locomotor movements during step-training are generated by spinal networks triggered by afferent feedback. Our objective was to compare the task-dependent effect of bike- and step-training after SCI on physiological measures of spinal cord plasticity in relation to changes in levels of neurotrophic factors. Thirty adult female Sprague-Dawley rats underwent complete spinal transection at a low thoracic level (T12). The rats were assigned to one of three groups: bike-training, step-training, or no training. The exercise regimen consisted of 15 min/d, 5 days/week, for 4 weeks, beginning 5 days after SCI. During a terminal experiment, H-reflexes were recorded from interosseus foot muscles following stimulation of the tibial nerve at 0.3, 5, or 10 Hz. The animals were sacrificed and the spinal cords were harvested for Western blot analysis of the expression of neurotrophic factors in the lumbar spinal cord. We provide evidence that bike- and step-training significantly increase the levels of brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and NT-4 in the lumbar enlargement of SCI rats, whereas only step-training increased glial cell-derived neurotrophic factor (GDNF) levels. An increase in neurotrophic factor protein levels that positively correlated with the recovery of H-reflex frequency-dependent depression suggests a role for neurotrophic factors in reflex normalization.
基于活动的疗法，如被动骑自行车和在跑步机上进行踏步训练，有助于脊髓损伤（SCI）后的运动功能恢复，从而增加了完成的步数、改善了步态运动学、恢复了与相位相关的脊髓反射调制，并防止了肌肉质量的下降。这两个任务都包括交替的运动，这些运动有节奏地拉伸和缩短后肢肌肉。然而，在自行车训练中，瘫痪的后肢是由电动设备被动移动的，而在踏步训练中，运动是由触发传入反馈的脊髓网络产生的。我们的目标是比较 SCI 后自行车和踏步训练对与神经营养因子水平变化相关的脊髓可塑性的任务依赖性影响。三十只成年雌性 Sprague-Dawley 大鼠在低胸水平（T12）进行完全脊髓横断。大鼠被分为三组：自行车训练组、踏步训练组或不训练组。运动方案包括 15 分钟/天，每周 5 天，在 SCI 后 5 天开始，持续 4 周。在终末实验中，在 0.3、5 或 10 Hz 刺激胫神经后，从骨间足部肌肉记录 H 反射。处死动物，收获脊髓，用于腰椎脊髓神经营养因子表达的 Western blot 分析。我们提供的证据表明，自行车和踏步训练显著增加了 SCI 大鼠腰骶部脑源性神经营养因子（BDNF）、神经营养因子-3（NT-3）和 NT-4 的水平，而只有踏步训练增加了胶质细胞源性神经营养因子（GDNF）的水平。神经生长因子蛋白水平的增加与 H 反射频率依赖性抑制的恢复呈正相关，这表明神经营养因子在反射正常化中起作用。
