Therapeutic Effect Of Posterior Tibial Nerve Stimulation On Neurogenic Bladder In Rats With Spinal Cord Injury

Objective:To observe the effect of posterior tibial nerve stimulation on neurogenic bladder in rats with spinal cord injury and to study the expression of TRP channel protein and P2X receptor in dorsal root ganglion and bladder tissue,so as to explore its possible mechanism and provide theoretical basis for the clinical application of electrical stimulation of tibial nerve.Methods:64 adult SD rats were randomly divided into four groups,16 rats in each group:normal group,sham group,SCI group and PTNS group.Modified Allen’s striking method was used to establish spinal cord injury model in the rats of SCI group and PTNS group.BBB scores were measured at 1 week,2 weeks,3 weeks,4 weeks,5 weeks and 6 weeks after modeling to evaluate whether the SCI model was successfully established.At the same time,the rats of PTNS group was given tibial nerve electrical stimulation at two weeks after modeling（20 minutes twice a day,5 days a week,lasting for 4 weeks）and given urodynamic examination at the 6th week to observe the bladder compliance of each group.Then HE staining was used to observe the degree of bladder tissue damage under light microscope.RT-PCR was used to detect the gene transcription levels of TRPV1,TRPA1,P2X2 and P2X3 in bladder and dorsal root ganglion.Western blot was used to detect the protein expression levels of TRPV1,TRPA1,P2X2 and P2X3 in bladder and dorsal root ganglion.Results:（1）One week after modeling,the BBB scores of SCI group and PTNS group were significantly lower than those of normal group and sham group（p<0.05）.After 6 weeks of modeling,BBB scores of SCI group and PTNS group increased,but there was no significant difference between the two groups（p>0.05）.（2）The results of urodynamics showed that the residual urine volume increased,the voiding efficiency decreased and the bladder showed a low compliance state in the SCI group.And the bladder compliance of the PTNS group was 0.05±0.01(m L·cm H₂O^-1),and the bladder compliance of the SCI group was 0.03±0.01(m L·cm H₂O^-1),which was significantly improved in the PTNS group compared with the SCI group（p<0.05）.（3）Compared with the SCI group,the number of epithelial cells in the PTNS group increased slightly and arranged more orderly.The inflammatory degree of lamina propria was improved.The infiltration of neutrophils and monocytes was reduced.Meanwhile the tissue edema and vascular rupture were reduced and the inflammatory cell infiltration in bladder tissue was significantly reduced.（4）The results of RT-PCR showed that the transcriptional levels of TRPA1,TRPV1,P2X2and P2X3 in bladder and dorsal root ganglion in PTNS group were significantly higher than those in SCI group（p<0.05）.（5）The results of Western blot showed that the protein expression levels of TRPA1,TRPV1,P2X2 and P2X3 in bladder and dorsal root ganglion in PTNS group were significantly higher than those in SCI group（p<0.05）.Conclusion:（1）The results of urodynamics showed that the bladder function of rats was significantly improved,which proved that PTNS could effectively improve the low compliance of neurogenic bladder.（2）PTNS effectively promoted the expression of TRPA1,TRPV1,P2X2 and P2X3 in dorsal root ganglion and bladder tissue of rats with SCI.The improvement of neurogenic bladder may be related to the activation of TRP channel.In other words,PTNS can reactivate the expression of TRP channel protein in the bladder of rats with SCI and improve the low compliance of bladder and promote the recovery of urination function.