Abstract: ObjectiveTo determine the effect of acute and chronic spinal cord injury (SCI) resulted from thoracic cord transection on the urinary bladder spinal neural pathway.Methods76 adult Sprague-Dawley rats were randomly divided into 4 groups, non-SCI, SCIa, SCIb and SCIc respectively. The non-SCI rats underwent no surgical procedure except Pseudorabies virus (PRV) tracer injection into the bladder tissue, while the rats of other groups were spinalized and given PRV injection at different time after SCI. Transcardiac perfusion fixation was done in appropriate survival periods after PRV injection. Then sections of dorsal root ganglion (DRG) and spinal cord were processed for visualization of virus by the Streptavidin-Peroxidase (SP) immunohistochemical procedure. All sections were measured with the Olympus Cue-2 image analysis system.ResultsThe bladder weights in SCI_b and SCI_c groups markedly increased (P<0.001). The time-ordered flow charts of PRV tracing were similar in the non-SCI rats and in the SCI rats. The cross-sectional area of the labeled DRG cell profiles increased significantly after SCI (P<0.001). The number of labeled cells in dorsal horn in L₆ and S₁ segments 3 days after PRV injection markedly increased in chronic SCI rats, and so did the number of labeled motor neurons 4 days post-injection. ConclusionThe acute and chronic SCI have little effect on the process of virus transneuronal transport below the level of lesion. Subsequent to chronic SCI, marked reorganization of the micturition reflex pathways occurs.

Key words: spinal cord injury, bladder, micturition reflex pathways, pseudorabies virus, transneuronal tracing