Effect of tibial nerve stimulation on bladder afferent nerve activity in a rat detrusor overactivity model

ObjectivesTo study the post-stimulation effect of tibial nerve stimulation on rat bladder afferent activity, and urodynamic parameters in normal and acetic acid-induced detrusor overactivity conditions. MethodsIn urethane anesthetized male Wistar rats, the tibial nerve was stimulated for 30min at 5Hz, pulse width 200s and amplitude approximately threefold the threshold to induce a slight toe movement. The post-stimulation effect was studied by measuring afferent nerve activity of postganglionic pelvic nerve branches and various urodynamic parameters under two different conditions: (i) in physiological saline filling experiments (simulating normal bladder condition); and (ii) in acetic acid irritated bladders (simulating detrusor overactivity). ResultsAfter 30min of tibial nerve stimulation in saline filling experiments, the bladder capacity, threshold pressure and afferent nerve activity were not significantly different from the prestimulation measurements. The instillation of 0.5% acetic acid significantly reduced the bladder capacity and increased the afferent nerve activity. Tibial nerve stimulation significantly improved the bladder capacity and suppressed the afferent nerve activity compared with prestimulation acetic acid measurements. ConclusionsTibial nerve stimulation is able to significantly restore the bladder capacity by inhibiting afferent nerve activity in chemically irritated rat bladders. The present study provides important basic electrophysiological evidence to substantiate the clinical use of tibial nerve stimulation for treatment of symptoms related to detrusor overactivity.