Validation of the weight-drop contusion model in rats: A comparative studyof human spinal cord injury

Animal models are widely used for studying the pathophysiology as well as t reatment strategies for injuries of the central nervous system. However, it is still unclear in how far the rat model of spinal cord injury (SCI) is v alid for human SCI. Therefore, comparisons were made among functional, elec trophysiological, and morphological outcome parameters following SCI in rat s and humans. Contusion of the mid-thoracic spinal cord in 27 adult rats wa s induced by a weight-drop, leading to severe deficits in open field locomo tion at a chronic stage. The data of 85 human patients with chronic SCI wer e collected and compared with the rat data. In electrophysiological recordi ngs, prolonged latencies and reduced amplitudes in both motor evoked potent ials (MEP) and somatosensory evoked potentials (SSEP) were closely correlat ed to the impairment of locomotor capacity of lower limbs in rats and human s. The morphological parameters assessed by high-resolution magnetic resona nce imaging (MRI) in both species indicated that the lesion length and spin al cord atrophy were significantly related to the electrophysiological and functional outcome parameters. In rats, histological analysis was performed and showed, in addition to the MRI, a close relationship between spared wh ite matter and locomotor capacity. Our results suggest an analogous relatio nship in rats and humans with respect to functional, electrophysiological, and morphological outcomes. Thus, the techniques for evaluating the extent and severity of SCI in humans and rats are of comparable value. This indica tes that the rat can serve as an adequate animal model for research on func tional and morphological changes after SCI and the effects of new treatment strategies.