Effects of Sacral Nerve Stimulation on Neuronal Nitric Oxide Synthase in the Colon and Sacral Cord of Rats With Defecation Disorder After Spinal Cord Injury

OBJECTIVE: This study aimed to determine the effects of sacral nerve electrical stimulation (SNS) on neuronal nitric oxide synthase (nNOS) in the colon and sacral cord of rats with defecation disorder after spinal cord injury (SCI). METHODS: Rats with severe SCI (T10) were used as models and randomly divided into an SCI group and an SNS group. After 14 days of treatment, the intestinal transport function was assessed. Finally, the differences in nNOS immunoreactive cells, protein levels, nNOS mRNA, and NO content in the colon and sacral cord tissues were estimated using immunohistochemistry, Western blot, real-time polymerase chain reaction, and nitrate reductase method. RESULTS: The intestinal transport function of the SNS group was superior to that of the SCI group (P < 0.05). The average optical density of nNOS immunoreactive positive cells in the SCI group were significantly increased compared with those in the sham group. The content of NO of the SCI group significant increased compared with those of the sham group and the SNS group (both P < 0.01). The nNOS mRNA and protein expression was higher in the SCI group than in the sham group (P < 0.01), while that in the SNS group was significantly lower than that in the SCI group. CONCLUSIONS: SNS could reduce nNOS expression in the colon and sacral cord of SCI rats. This reduction may be an important neuromodulation mechanism for SNS to improve defecation reflex and promote the recovery of intestinal transit function.