Indian
J Physiol Pharmacol 2002;46 (4);
Treadmill Training Accelerates
Restoration of Locomotion after Complete Spinal Cord Transition
in the Rat
T. MOSHONKINA*, V. AVELEV, Yu. GERASIMENKO,
R. MATHUR** AND R. L. BIJLANI**
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.
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METHODS
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.
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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.
Fig.1
  |
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.
Fig.1
click for full view |
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DISCUSSION
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).
ACNOWLEDGEMENTS
Authors
thank Dr. E.G. Gilerovitch for histological analysis and A. I.
Shakisheva for excellent care of the animals.
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