Official organ of the Association of Physiologist and Pharmacologists of India


Short Communication
Volume 46 - No.4:January 2002 index

Indian J Physiol Pharmacol 2002;46 (4);

Treadmill Training Accelerates Restoration of Locomotion after Complete Spinal Cord Transition in the Rat
Laboratory of Movement Physiology, Pavlov Institute of Physiology, St. Petersburg, Russia And
**Department of Physiology, All India Institute of Medical Sciences, New Delhi – 110 029.* Corresponding Author (e-mail: tm@pavlov.infranru)
(Received on March 11, 2002)


Abstract: This short communication is devoted to the problem of the effect of the regular treadmill training on the restoration of motor function after spinal cord interruption. Experiments were out on the full spinalized rats. One group of the operated rats (n=5) received regular treadmill training and another group (n=5) did not receive any training. Motor behavior and activity were investigated weekly up to week 9 after spinalization. It was observed that trained rats restarted motor behavior earlier and demonstrated locomotor hindlimbs movements, and were more active than untrained rats.


Key words:      locomotion, spinal cord transection





It was demonstrated that regular treadmill training of adult cats with a spinal cord trauma improves locomotor capacity (1-3). These studies demonstrated that training to step provokes animals to execute full-weight bearing steps after spinalization. However, Foud et al. (2000) demonstrated that the locomotion, activity and weight bearing of rats with dorsal funiculi dissection (Th9-11) were equally well with and without treadmill training. The problem of animal’s capacity to restart locomotor performance after exercises is important because it defines capacity of the spinal cord after trauma to recover its motor functions by “learning” of this function. We reported preliminary findings (4) that the regular treadmill training in the capacity of rats to restart locomotor activity after complete spinal cord transection. Spanilized rats were divided in two groups: trained and untrained, so that we could compare spontaneously recovered movements and trained movements.


Adult female rats (Sprague-Dawley, n = 10, 180-220 g) were kept at the standard conditions. For the surgery rats were anesthetized (Nembutal, 4 mg/100 g, i.p.) and Th9-10 laminectomy was performed, and spinal cord was transected completely. After surgery rats were placed into warm chambers and cared by bladder expression and antibiotic treatment (gentamicin, 0.2 mg/100g, i.m.) 2 times per day for 5 days. Five rats were included into experimental group, and thus they were trained to walk on a treadmill 5 days per week starting next day after surgery. On the first day training was initiated by manual lifting of the rat’s tail and the treadmill walking was continued for 1.5-2.0 min. After initiation of voluntary training (3-8 days after surgery) rats were trained for 5-10 min per day. Other five operated rats consisted of a control group, and they were not subjected to any training. Animals were weighed once in every week.

Recovery of locomotion activity was recorded every week up to 9th week after spinalization by two ways. (i) The duration of the voluntary walking on the treadmill of the experimental and control rats was measured. This index characterizes rat’s activity. (ii) Type of the hindlimbs movements which were observed during 9-weeks period after spinalization were scaled from 0 to 5. Mark 0 indicates lack of any hindlimbs movement. Mark 1 corresponds to involuntary viscero-somatic reflective movements which are initiated after perineum stimulation. Mark 2 is permanent hip flexion that is usually observed after spinalization. Mark 3 corresponds to voluntary flexion and extension of all hindlimb joints. Often a type of one hindlimb movement was 3 and a type of another hindlimb movement was 2. Mark 4 corresponds to regular periodical movements of both hindlimbs (like locomotion) without body support. Mark 5 indicates taking a jump, or a push during treadmill walking. After 9 weeks of observation, spinal cord was examined by histological methods.


Histological analysis of the spinal cord revealed clear damage to the spinal cord without any neural tissues at the site of dissection in animals of both groups. So hindlimb movements that we observed originated from the isolated part of the spinal cord and without any supraspinal influence on these movements.
Although all operated rats showed hindlimbs movements after spinalization, the quality of the movements and time required for its restoration differed between trained and control animals. Figure 1 shows time profiles of hindlimb movement restoration in trained and untrained rats. Generally, untrained rats frequently did not show any hindlimb movements up to 5-6 weeks after spinalization, while trained rats had different movements after 3-4 weeks. Usually hindlimb movements of the control rats were limited by viscero-somatic movements or hip flexion. Trained rats, on the contrary, demonstrated hindlimb locomotion by week 3 after spinalization, when untrained rats did not show locomotion at all. In other words, trained rats with complete spinal cord interruption began to move by their hindlimbs earlier than untrained rats.


Our observations on the activity of the operated rats with and without training are shown in Fig 2. Trained rats ran longer time than untrained rats. As shown in Fig. 2, all nine points connected with trained rats are higher than points connected with control animals.


click for full view



In the present study we investigated the effect of treadmill training on the hindlimb motion in rats following complete spinal cord section. It appears that regular treadmill training provokes early initiation of the hindlimb movements along with better motor activity in experimental rats. Although it has been demonstrated in rats that the systematic treadmill therapy does not change motor behavior after partial dorsal spinal cord lesion (5), it appears from the present study that rapid restoration of the hindlimb activity in both groups may be connected with the plasticity of the intact structures of the spinal cord.

Regarding the observed differences in the motor behavior in trained and untrained rats in the present study, it appears possible that stimulation of the afferents of the isolated part of the rat’s spinal cord (by activation of the proprioceptive and tactile systems during the training in treadmill) induces starting of the locomotor pattern. Lack of regular inflow of the afferent information to isolated spinal cord part leads to absence of locomotion. Based on our observation in the present study, we propose that total activity of the trained rats is higher than that of the untrained rats due to synthesis of the neuropeptides which are involved in controlling functional and morphological adaptation (6).


Authors thank Dr. E.G. Gilerovitch for histological analysis and A. I. Shakisheva for excellent care of the animals.


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