Introduction of the earlier 5-point Tarlov scale [46,47]. Another method
Brain Research 883 2000 165–177 www.elsevier.com locate bres
Research report
Efficient testing of motor function in spinal cord injured rats
a , a
b a
a
Gerlinde A.S. Metz , Doron Merkler , Volker Dietz , Martin E. Schwab , Karim Fouad
a
Brain Research Institute , University and ETH Zurich, 8057 Zurich, Switzerland
b
Swiss Paraplegic Center , University Hospital Balgrist, University of Zurich, 8008 Zurich, Switzerland
Accepted 2 August 2000
Abstract
In experimental spinal cord injury studies, animal models are widely used to examine anatomical and functional changes after different treatments and lesion types. A variety of behavioral paradigms exists in the literature, but definitions and criteria for motor performance
vary considerably. In this study, we examined the outcome and relation of tests such as the BBB open field locomotion score, footprint analysis, kinematic analysis, placing response, grid walk and narrow beam crossing following two different lesion types. The information
obtained was used to design an efficient and reliable testing strategy, which includes a broad spectrum of parameters to enhance sensitivity. This approach should help to standardize modular testing procedures across different laboratories working on spinal cord
injury.
2000 Elsevier Science B.V. All rights reserved.
Theme : Motor systems and sensorimotor integration
Topic : Control of posture and movement
Keywords : Testing strategy; Combined motor score; Motor deficit
1. Introduction of the earlier 5-point Tarlov scale [46,47]. Another method
is the footprint analysis, which quantifies gait coordination In spinal cord injury research, the rat has become the
and placement of the feet [16,32]. Kinematic analysis of favorite animal model for testing various treatment strate-
video recordings during walking allows the qualitative and gies. Several lesion techniques in rodents have been
quantitative evaluation of joint and limb movements established to model human spinal cord injuries. A popular
[12,34,35,50]. All these tests focus mainly on stereotyped method is the contusion of the spinal cord, which mimics
movements controlled by networks and reflex pathways the situation in humans relatively closely [15,21,54].
within the spinal cord i.e., the central pattern generator; However, with this approach it is not possible to fully
CPG [24,43]. The CPG network is driven by excitatory ablate defined spinal tracts, which can be achieved by
input mainly from the ventrally located reticulospinal tract sectioning the spinal cord at specific locations [33,44,49].
[30]. Tests that reflect the integrity of the dorsal spinal To quantify the residual function in the different animal
motor tracts cortico- or rubrospinal tract, should focus on models, a variety of motor and sensory tests has been
voluntary aspects of limb movements or balance [52]. One developed. Most paradigms assessing the integrity of
possible paradigm is the grid walk test in which animals spinal pathways focus on hindlimb function such as
have to traverse a horizontal grid elevated above the locomotor capacity and reflexes. A frequently used test to
ground [23,32,45,55]. Testing the performance during assess the severity of spinal cord injury is the 21-point
crossing of elevated narrow beams is another possibility to open field locomotion score BBB scale [4], a refinement
evaluate descending motor control as well as body balance of spinal cord injured animals [29]. A reflex which is
thought to be an indicator of corticospinal tract integrity is
Corresponding author. Present address: Department of Psychology
the contact placing response [7,8,17].
and Neuroscience, University of Lethbridge, 4401 University Drive,
This study investigated the functional outcome of two
Lethbridge, Alberta, Canada T1K 3M4. Tel.: 11-403-329-2366; fax:
widely used spinal cord injury models in adult rats, dorsal
11-403-329-2555. E-mail address
: gerlinde.metzuleth.ca G.A.S. Metz.
hemisection and contusion injuries of varying severity. By
0006-8993 00 – see front matter
2000 Elsevier Science B.V. All rights reserved. P I I : S 0 0 0 6 - 8 9 9 3 0 0 0 2 7 7 8 - 5
166 G
using tests like the BBB score, footprint analysis, fixative 4 paraformaldehyde in 0.1 M phosphate buffer
kinematic gait analysis, grid walk, narrow beam, open field with 5 sucrose. The spinal cords were removed and
exploration and placing response we covered a broad postfixed overnight. After immersion for 2–3 days in a
spectrum of behavioral and physiological parameters. The 30 sucrose solution, the spinal cords were embedded in a
outcome of these paradigms was correlated in order to protein matrix [28]. The spinal cords were frozen in
define their relationship and the validity of the individual isopentane at 2408C and 50-mm sections were cut in the
tests. Based on these results we developed a testing sagittal plane. The sequential series of sections were
strategy for functional outcome, optimized for efficiency, mounted on slides.
reliability and comparability between different lesion types To visualize axons, a monoclonal antibody against the
and severities. neurofilament 200 kDa subunit Boehringer Mannheim,
Germany was used. Slides were treated with ethanol 95–acetic acid 5 for 25 min at 48C, rehydrated in