| Loss of bladder control is one of the most common and most important consequences of a spinal cord injury (SCI), but is rarely assessed in animal studies of SCI. In these experiments, we use a simple outcome measure (volume of retained urine) to assess the level of function of the bladder over time after injury.;Female Sprague-Dawley rats received moderate contusion injuries at one of three thoracic levels, T1, T4, or T9; complete crush injuries at T1 or T9; lateral hemisections (left or right) at T9; bilateral ethidium bromide (EB) lesions in one of four locations at T9; unilateral EB lesions in one of four locations with a left lateral hemisection; or sham laminectomies at T9. Bladder impairment, as reported by increased amounts of retained urine, was observed following all contusion, crush, and lateral hemisection injuries at T9. Bladder impairment was also observed after contusion injuries at T4, but not at T1. Additionally, the EB lesions yielded no bladder dysfunction.;The contusion animals at T1, T4, or T9 all had equivalent lesions, based on their amount of tissue sparing at the injury epicenter and their performance on the BBB hindlimb locomotor rating scale. The T1 animals did, however, have a greater number of retrogradely labeled cells in the pontine micturition center (PMC) than did the T4 or T9 injured animals. This suggests that there was in fact greater sparing of fibers following the T1 contusions, and that this was responsible for the preservation of bladder function following injury.;Young female C57/B16 mice received moderate contusion injuries, crush injuries, or sham laminectomies at T9. Older female mice also received moderate contusion injuries at T9. Both the crush and contusion mice (younger and older) yielded significantly different urine volumes when compared to the control mice across all time points. Interestingly, mice that received contusion injuries at 30 weeks of age exhibited significantly higher urine volumes than mice that were injured at 12 weeks, despite demonstrating a higher level of functioning on the BBB scale. |
