Serial changes in bladder, locomotion, and levels of neurotrophic factors in rats with spinal cord contusion.

The aims of this study were to evaluate the evolution of the neurogenic bladder after spinal cord contusion and to correlate changes in bladder function with locomotor function and levels of neurotrophic factors. The MASCIS impactor was used to cause a mild contusion injury of the lower thoracic spinal cord of Sprague-Dawley rats. Rats were divided into four groups according to the length of time from injury to sacrifice, at 4, 14, 28, and 56 days after injury. Gait analysis was performed each week, and urodynamic study was performed just before sacrifice. Basso, Beattie, and Bresnahan (BBB) and coupling scores showed gradual recovery, as did the urinary voiding pattern and bladder volume; some parameters of micturition reached normal ranges. Brain-derived neurotrophic factor (BDNF) levels in the spinal cord, as detected by enzyme-linked immunosorbent assay, decreased with time, whereas neurotrophin-3 (NT-3) levels remained unchanged. The micturition pattern, bladder volume, and locomotor function continued to recover during the time of observation; BDNF levels in the spinal cord and bladder were inversely correlated with BBB scores and the restoration of bladder volume. We conclude that urodynamic changes in the bladder correlate with locomotion recovery but not with the levels of BDNF or NT-3 after modified mild contusion injury in rats.