Precise assessment of motor deficits after traumatic spinal cord injury (SCI) in rodents is crucial for understanding the mechanisms of functional recovery and testing therapeutic approaches. Here we analyzed the applicability to a rat SCI model of an objective approach, the single-frame motion analysis, created and used for functional analysis in mice. Adult female Wistar rats were subjected to graded compression of the spinal cord. Recovery of locomotion was analyzed using video recordings of beam walking and inclined ladder climbing. Three out of four parameters used in mice appeared suitable: the foot-stepping angle (FSA) and the rump-height index (RHI), measured during beam walking, and for estimating paw placement and body weight support, respectively, and the number of correct ladder steps (CLS), assessing skilled limb movements. These parameters, similar to the Basso, Beattie, and Bresnahan (BBB) locomotor rating scores, correlated with lesion volume and showed significant differences between moderately and severely injured rats at 1-9 weeks after SCI. The beam parameters, but not CLS, correlated well with the BBB scores within ranges of poor and good locomotor abilities. FSA co-varied with RHI only in the severely impaired rats, while RHI and CLS were barely correlated. Our findings suggest that the numerical parameters estimate, as intended by design, predominantly different aspects of locomotion. The use of these objective measures combined with BBB rating provides a time- and cost-efficient opportunity for versatile and reliable functional evaluations in both severely and moderately impaired rats, combining clinical assessment with precise numerical measures.

Following spinal cord injury (SCI), loss of spinal and supraspinal control results in desynchronisation of detrusor vesicae (parasympathicus) and external urethral sphincter (sympathicus) activity. Despite recovery of lower urinary tract function being a high priority in patients with SCI, effective treatment options are unavailable largely because mechanisms are poorly understood. Purpose and methods: We used a clinically relevant model of thoracic SCI compression injury in adult female Wistar rats and confirmed that lesion volumes following severe injuries were significantly greater compared to moderate injuries (p < 0.05). Between 1–9 weeks, we assessed recovery of bladder function as well as return of locomotor function using the Basso, Beattie and Bresnahan (BBB) score. Bladder morphometrics and overall intramural innervation patterns, as assessed with ß-III tubulin immunohistochemistry, were also examined. Results: Despite variability, bladder function was significantly worse following severe compared to moderate compression injury (p < 0.05); furthermore, the degree of bladder and locomotor dysfunction were significantly correlated (r = 0.59; p < 0.05). In addition, at 9 weeks after SCI we saw significantly greater increases in bladder dry weight (p < 0.05) and wall thickness following severe compared to moderate injury as well as increases in intramural axon density (moderate: 3× normal values; severe 5×; both p < 0.05) that also correlated with injury severity (r = 0.89). Conclusion: The moderate and severe compression models show consistent and correlated deficits in bladder and locomotor function, as well as in gross anatomical and histopathological changes. Increased intramural innervation may contribute to neurogenic detrusor overactivity and suggests the use of therapeutic agents which block visceromotoric efferents.

Whole-body vibration (WBV) is a relatively novel form of exercise used to improve neuromuscular performance in healthy individuals. Its usefulness as a therapy for patients with neurological disorders, in particular spinal cord injury (SCI), has received little attention in clinical settings and, surprisingly, even less in animal SCI models. We performed severe compression SCI at a low-thoracic level in Wistar rats followed by daily WBV starting 7 (10 rats) or 14 (10 rats) days after injury (WBV7 and WBV14, respectively) and continued over a 12-week post-injury period. Rats with SCI but no WBV training (sham, 10 rats) and intact animals (10 rats) served as controls. Compared to sham-treated rats, WBV did not improve BBB score, plantar stepping, or ladder stepping during the 12-week period. Accordingly, WBV did not significantly alter plantar H-reflex, lesion volume, serotonergic input to the lumbar spinal cord, nor cholinergic or glutamatergic inputs to lumbar motoneurons at 12 weeks after SCI. However, compared to sham, WBV14, but not WBV7, significantly improved body weight support (rump-height index) during overground locomotion and overall recovery between 6-12 weeks and also restored the density of synaptic terminals in the lumbar spinal cord at 12 weeks. Most remarkably, WBV14 led to a significant improvement of bladder function at 6-12 weeks after injury. These findings provide the first evidence for functional benefits of WBV in an animal SCI model and warrant further preclinical investigations to determine mechanisms underpinning this noninvasive, inexpensive, and easily delivered potential rehabilitation therapy for SCI.