Abstract
Objective The rate of neuronal apoptosis increases after spinal cord injury (SCI). Anastomosing the normal nerve roots above the SCI level to the injured sacral nerve roots can enhance the functional recovery of neurons. Therefore, we evaluated the effect of sacral nerve root transfer after SCI on pontine neuronal survival. Methods Sprague–Dawley rats were randomly divided into three groups: Group A, reconstruction of afferent and efferent nerve pathways of the bladder after SCI; Group B, SCI only; and Group C, control group. We examined pontine neuronal morphology using hematoxylin and eosin (H&E) staining after SCI and nerve transfer. Bcl-2 and Bax protein expression changes in the pontine micturition center were quantified by immunohistochemistry. The number of apoptotic neurons was determined by TUNEL staining. We examined pontine neuronal apoptosis by transmission electron microscopy (TEM) at different time points. Results H&E staining demonstrated that the number of neurons had increased in Group A, but more cells in Group B displayed nuclear pyknosis, with the disappearance of the nucleus. Compared with Group B, Group A had significantly higher Bcl-2 expression, significantly lower Bax expression, and a significantly higher Bcl-2/Bax ratio. The number of apoptotic neurons and neuron bodies in Group A was significantly lower than that in Group B, as indicated by TUNEL staining and TEM. Conclusions These findings demonstrate that lumbosacral nerve transfer can reduce neuronal apoptosis in the pontine micturition center and enhance functional recovery of neurons. This result further suggests that lumbosacral nerve transfer can be used as a new approach for reconstructing bladder function after spinal cord injury.
Highlights
After spinal cord injury (SCI), atrophy appears in the corresponding functional areas of the brain as neurons gradually disappear and become fibrotic or is replaced by the surrounding functional area [1,2,3]
The rats were randomly divided into three groups, with 30 rats in each of the following groups: Group A, reconstruction of afferent and efferent nerve pathways of the bladder performed after SCI; Group B, SCI only; and Group C, control group
The conus medullaris was exposed at the level of L4 (Figure 1(a)), and the spinal cord was completely cut below L4 with surgical scissors
Summary
After SCI, atrophy appears in the corresponding functional areas of the brain as neurons gradually disappear and become fibrotic or is replaced by the surrounding functional area [1,2,3]. The recovery of nerve function below the level of spinal injury has always been a conundrum. Animal experiments and clinical cases have demonstrated that anastomosing the anterior and posterior nerve roots above the injury level to the anterior and posterior sacral nerve roots controlling the bladder can simultaneously reconstruct the afferent and efferent pathways of the bladder and improve bladder function [4,5,6,7]. The structural changes in the brain after reconstruction of the bladder afferent and efferent pathways remain unclear. Few studies focus on changes that occur in the brain after nerve transfer. In this study, anastomosis of the dorsal and ventral roots of the nerves above the injury level and the dorsal and ventral sacral nerve roots
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