Spontaneous functional full recovery from motor and sensory deficits in adult mice after mild spinal cord injury

Yohei Kakuta,Anna Adachi,Marino Yokohama,Toshiki Horii,Tokue Mieda,Yoichi Iizuka,Kenji Takagishi,Hirotaka Chikuda,Haku Iizuka,Kazuhiro Nakamura

doi:10.1016/j.heliyon.2019.e01847

Abstract

The extent of spontaneous recovery in patients with a spinal cord injury (SCI) has not been thoroughly investigated. It is essentially not known whether SCI animals exhibit full recovery from both motor and sensory deficits as well. Here, we developed an appropriate condition to produce a mild SCI in mice. Mice given a mild contusion SCI showed transient low performances in the Basso Mouse Scale for locomotion (BMS), rotarod and beam walking tests after the SCI, which was followed by complete restoration in a short time. The SCI mice also showed functional full recovery from low sensitivity to light touch using dynamic touch test. Nevertheless, the fully-recovered SCI mice still exhibited significant loss of myelin in the spinal cord. These results suggest a high potential of adaptation of motor and sensory systems in mice and might provide insight into the prognoses of SCI patients.

Highlights

Spinal cord injury (SCI) is one of the major traumas worldwide because SCIs can be caused by common traumas such as motor vehicle accidents, sports and falls in mountains as well as tumors and infections [1]
A severe SCI likely leads to extensive neuron loss that results in irreversible motor deficits even after a long-term recovery period, a mild SCI might enable full recovery from initial motor deficits
Steel-Dwass test revealed that the Basso Mouse Scale for locomotion (BMS) scores of moderate SCI and severe SCI were significantly lower than those of mild SCI at 1 week, 2 weeks and 3 weeks after the injury

Summary

Introduction

Spinal cord injury (SCI) is one of the major traumas worldwide because SCIs can be caused by common traumas such as motor vehicle accidents, sports and falls in mountains as well as tumors and infections [1]. The signs and symptoms of an SCI include paralysis, bladder and bowel control failures and sexual dysfunction [2]. Neuronal damages in an adult caused by an SCI persist throughout life [3]. Motor performances are partially recovered spontaneously several weeks after an SCI in adult rodents. The Basso Mouse Scale for locomotion (BMS) [4], rotarod test [5, 6] and beam walking test [7] have been frequently used to evaluate motor functions after SCI in mice. The performances improve over several weeks thereafter. It is not essentially known whether the SCI mice show full recovery from sensory deficits as well

Methods

Results

Conclusion