Study design: Experimental training model of rats with spinal cord injury (SCI).
Setting: Osaka, Japan
Objective: To investigate the effect of forced treadmill training by plantar placement (PP), as compared with dorsal placement (DP), of the dorsal paws on the locomotor behaviors of spinal cord-injured rats.
Methods: The spinal cord was contusion-injured at the thoracic level. Rats were divided into three groups: forced training involving stepping by PP and DP and non-forced training/assistance (nT). Training began 1 week after injury and was conducted for 4 weeks. Locomotor behaviors were estimated using Basso-Beattie-Bresnahan (BBB) scores, dorsiflexion of the hind paws and footprints of the hind paws. Histological and immunohistochemical examinations of the spinal cord lesions were conducted after 4 weeks of training.
Results: The values, respectively, of PP, DP and nT groups at 4 weeks of training were as follows: BBB scores were 15.6 +/- 0.8, 7.7 +/- 1.3 and 10.3 +/- 0.4. The paw dorsiflexion angles were 34.1 +/- 5.2, 16.4 +/- 2.4 and 23.6 +/- 3.0 degrees, respectively. The stride angles were 5.1 +/- 0.9, 13.7 +/- 4.9 and 17.8 +/- 4.0 degrees for the left paws. Cavity volumes were 10.3 +/- 2.1, 31.0 +/- 2.0 and 28.2 +/- 4.9%. In addition to cavities, there were astrocyte-devoid areas containing some loose tissues, through which many axons extended longitudinally.
Conclusions: The BBB score, dorsiflexion angle and stride angle were consistently improved in the PP group. Cavity formation was more reduced, and many axons extended through coarse tissues formed in astrocyte-devoid areas at the lesion in the PP group. Forced training by PP of the hind paws promoted the behavioral and histological improvement of rats with SCI.