Davis B M, Ayers J L, Koran L, Carlson J, Anderson M C, Simpson S B
University of Illinois, Department of Biological Sciences and Committee on Neuroscience, Chicago 60680.
Exp Neurol. 1990 Jun;108(3):198-213. doi: 10.1016/0014-4886(90)90124-b.
The time course of regeneration of supraspinal and descending brachial intraspinal axons was studied using HRP retrograde tracing and kinematic analysis. Five groups of salamanders (10 salamanders/group) received complete thoracic transection 1.0 cm rostral to the hind limbs abolishing swimming. Groups 1-4 recovered for 2, 4, 6, and 8 weeks, respectively, before being filmed to record the animal's ability to swim. After filming, a second transection was made 1.0 cm caudal to the first (at the level of the lumbar enlargement) and HRP was used to label descending axons which had grown past the first lesion. The fifth group was filmed every 2 weeks for 12 weeks before the second transection was made for HRP application. The films were used to perform frame by frame computer analysis of the amplitude and timing of cyclic lateral flexion waves which make up swimming behavior. The earliest return of coordinated swimming behavior was seen 4 weeks after transection (1 of 20 animals). At 6 weeks post-transection, 5 of 10 animals exhibited coordinated swimming. However, the behavior in these animals was subnormal. In the group surviving 8 weeks post-transection, 5 of 10 animals recovered coordinated swimming behavior. In the group that was filmed every 2 weeks, 5 of the 10 salamanders which did recover, exhibited coordinated swimming behavior by the eighth week post-transection. Kinematic analysis of salamanders that exhibited a return of coordinated swimming revealed quantitative differences compared to normal salamanders. While continuous head to tail undulatory waves were present, the propagation time and period were faster than those in normal salamanders. Retransection of the spinal cord abolished coordinated swimming. The numbers and distribution of HRP-labeled supraspinal neurons varied greatly among the animals that displayed recovery of locomotor abilities. In the salamanders examined 6 weeks post-transection the majority of labeled cells were found in medullary nuclei. In recovered salamanders examined 8 and 12 weeks post-transection, HRP-labeled neurons were found in the red nucleus, in the interstitial nucleus of the fasciculus longitudinalis medialis, and in the mesencephalic as well as the medullary reticular neurons. Recovery of coordinated swimming was only observed in salamanders in which descending supraspinal and intraspinal axons were present at the level of the lumbar enlargement (as demonstrated by HRP retrograde labeling). These results indicate that recovery of locomotion is dependent on the reestablishment of descending input and is not a result of changes in spinal reflexes or propagation of electrical activity through the body wall.
采用辣根过氧化物酶（HRP）逆行追踪法和运动学分析方法，研究了脊髓上和臂部脊髓内下行轴突再生的时间进程。将五组蝾螈（每组10只蝾螈）在距离后肢头端1.0厘米处进行完全胸段横断，以消除游泳能力。第1 - 4组分别恢复2、4、6和8周，然后进行拍摄，记录动物的游泳能力。拍摄后，在第一次横断部位尾端1.0厘米处（腰膨大水平）进行第二次横断，并使用HRP标记越过第一个损伤部位生长的下行轴突。第五组在进行第二次横断以应用HRP之前，每2周拍摄一次，共拍摄12周。这些影片用于对构成游泳行为的周期性侧屈波的幅度和时间进行逐帧计算机分析。横断后4周最早出现了协调游泳行为的恢复（20只动物中有1只）。横断后6周，10只动物中有5只表现出协调游泳。然而，这些动物的行为仍不正常。在横断后存活8周的组中，10只动物中有5只恢复了协调游泳行为。在每2周拍摄一次的组中，10只恢复的蝾螈中有5只在横断后第8周表现出协调游泳行为。对表现出协调游泳恢复的蝾螈进行运动学分析发现，与正常蝾螈相比存在数量上的差异。虽然存在从头到尾的连续波动波，但传播时间和周期比正常蝾螈更快。脊髓再次横断消除了协调游泳。在显示运动能力恢复的动物中（通过HRP逆行标记证明），HRP标记的脊髓上神经元的数量和分布差异很大。在横断后6周检查的蝾螈中，大多数标记细胞位于延髓核中。在横断后8周和12周检查的恢复蝾螈中，在红核、内侧纵束间质核、中脑以及延髓网状神经元中发现了HRP标记的神经元。仅在腰膨大水平存在脊髓上和脊髓内下行轴突的蝾螈中观察到了协调游泳的恢复（如HRP逆行标记所示）。这些结果表明，运动恢复依赖于下行输入的重新建立，而不是脊髓反射变化或电活动通过体壁传播的结果。
