The swimming test is effective for evaluating spasticity after contusive spinal cord injury.
Spasticity is a frequent chronic complication in individuals with spinal cord injury (SCI). However, the severity of spasticity varies in patients with SCI. Therefore, an evaluation method is needed to determine the severity of spasticity. We used a contusive SCI model that is suitable for clinical translation. In this study, we examined the feasibility of the swimming test and an EMG for evaluating spasticity in a contusive SCI rat model. Sprague-Dawley rats received an injury at the 8th thoracic vertebra. Swimming tests were performed 3 to 6 weeks after SCI induction. We placed the SCI rats into spasticity-strong or spasticity-weak groups based on the frequency of spastic behavior during the swimming test. Subsequently, we recorded the Hoffman reflex (H-reflex) and examined the immunoreactivity of serotonin (5-HT) and its receptor (5-HT2A) in the spinal tissues of the SCI rats. The spasticity-strong group had significantly decreased rate-dependent depression of the H-reflex compared to the spasticity-weak group. The area of 5-HT2A receptor immunoreactivity was significantly increased in the spasticity-strong group. Thus, both electrophysiological and histological evaluations indicate that the spasticity-strong group presented with a more severe upper motor neuron syndrome. We also observed the groups in their cages for 20 hours. Our results suggest that the swimming test provides an accurate evaluation of spasticity in this contusive SCI model. We believe that the swimming test is an effective method for evaluating spastic behaviors and developing treatments targeting spasticity after SCI.
Department of Veterinary Surgery, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.|Department of Rehabilitation for the Movement Functions, Research Institute, National Rehabilitation Center, Saitama, Japan.
Youngjae
Y
Ryu
Department of Rehabilitation for the Movement Functions, Research Institute, National Rehabilitation Center, Saitama, Japan.
Toru
T
Ogata
Department of Rehabilitation for the Movement Functions, Research Institute, National Rehabilitation Center, Saitama, Japan.
Motoshi
M
Nagao
Department of Rehabilitation for the Movement Functions, Research Institute, National Rehabilitation Center, Saitama, Japan.
Taku
T
Kitamura
Department of Rehabilitation for the Movement Functions, Research Institute, National Rehabilitation Center, Saitama, Japan.|Department of Neurosurgery, Brain and Spinal Injury Center, University of California, San Francisco, California, United States of America.
Kazuhito
K
Morioka
Department of Rehabilitation for the Movement Functions, Research Institute, National Rehabilitation Center, Saitama, Japan.
Yoshinori
Y
Ichihara
Department of Rehabilitation for the Movement Functions, Research Institute, National Rehabilitation Center, Saitama, Japan.
Toru
T
Doi
Department of Rehabilitation for the Movement Functions, Research Institute, National Rehabilitation Center, Saitama, Japan.
Yasuhiro
Y
Sawada
Department of Rehabilitation for the Movement Functions, Research Institute, National Rehabilitation Center, Saitama, Japan.|Graduate School, International University of Health and Welfare, Tokyo, Japan.
Masami
M
Akai
Department of Veterinary Surgery, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
Ryohei
R
Nishimura
Department of Veterinary Surgery, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
Naoki
N
Fujita
D000818:Animals; D005260:Female; D006181:H-Reflex; D009046:Motor Neurons / Q000378:metabolism / Q000502:physiology; D009128:Muscle Spasticity / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044402:Receptor, Serotonin, 5-HT2A / Q000378:metabolism; D013119:Spinal Cord Injuries / Q000150:complications / Q000503:physiopathology*; D013550:Swimming
D044402:Receptor, Serotonin, 5-HT2A