Thoracic Hemisection in Rats Results in Initial Recovery Followed by a Late Decrement in Locomotor Movements, with Changes in Coordination Correlated with Serotonergic Innervation of the Ventral Horn

PLoS One. 2015 Nov 25;10(11):e0143602. doi: 10.1371/journal.pone.0143602. eCollection 2015.


Lateral thoracic hemisection of the rodent spinal cord is a popular model of spinal cord injury, in which the effects of various treatments, designed to encourage locomotor recovery, are tested. Nevertheless, there are still inconsistencies in the literature concerning the details of spontaneous locomotor recovery after such lesions, and there is a lack of data concerning the quality of locomotion over a long time span after the lesion. In this study, we aimed to address some of these issues. In our experiments, locomotor recovery was assessed using EMG and CatWalk recordings and analysis. Our results showed that after hemisection there was paralysis in both hindlimbs, followed by a substantial recovery of locomotor movements, but even at the peak of recovery, which occurred about 4 weeks after the lesion, some deficits of locomotion remained present. The parameters that were abnormal included abduction, interlimb coordination and speed of locomotion. Locomotor performance was stable for several weeks, but about 3-4 months after hemisection secondary locomotor impairment was observed with changes in parameters, such as speed of locomotion, interlimb coordination, base of hindlimb support, hindlimb abduction and relative foot print distance. Histological analysis of serotonergic innervation at the lumbar ventral horn below hemisection revealed a limited restoration of serotonergic fibers on the ipsilateral side of the spinal cord, while on the contralateral side of the spinal cord it returned to normal. In addition, the length of these fibers on both sides of the spinal cord correlated with inter- and intralimb coordination. In contrast to data reported in the literature, our results show there is not full locomotor recovery after spinal cord hemisection. Secondary deterioration of certain locomotor functions occurs with time in hemisected rats, and locomotor recovery appears partly associated with reinnervation of spinal circuitry by serotonergic fibers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anterior Horn Cells / metabolism
  • Disease Models, Animal
  • Electromyography
  • Female
  • Gait
  • Locomotion*
  • Psychomotor Performance*
  • Rats
  • Serotonin / metabolism
  • Spinal Cord / pathology
  • Spinal Cord / physiopathology*
  • Spinal Cord / surgery
  • Spinal Cord Injuries / pathology
  • Spinal Cord Injuries / physiopathology*
  • Spinal Cord Injuries / rehabilitation*
  • Spinal Cord Injuries / surgery


  • Serotonin

Grants and funding

This work was supported by the Nencki Institute statutory donation and grant nr. N N404 584438 from Polish Ministry of Science and High Education ( and a grant from the European Union within the European Regional Development Fund, POIG 01.01.02-00-109/09. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.