Inhibitory Effect and Possible Mechanism of Intraurethral Stimulation on Overactive Bladder in Female Rats

PURPOSE To investigate the inhibitory effect and possible mechanism of intraurethral stimulation on overactive bladder (OAB) induced by acetic acid irritation. METHODS Cystometry was performed in 13 urethane-anesthetized female rats. Intravesical infusion of 0.5% acetic acid was used to irritate the bladder and induce OAB. Multiple cystometrograms were performed with mirabegron, continuous stimulation, mirabegron plus continuous stimulation, and β3-adrenoceptor antagonist plus continuous stimulation to determine the mechanism underlying the inhibitory effect by intraurethral stimulation. RESULTS Infusion of acetic acid significantly decreased bladder capacity. Intraurethral stimulation at 2.5 Hz plus mirabegron significantly increased bladder capacity and decreased the nonvoiding contraction count. The changes were strongly inhibited after the β3-adrenoceptor antagonist was administered. CONCLUSIONS Activation of urethral afferent nerves can reverse OAB, which activates C-fiber afferent nerves. This animal study indicates that intraurethral stimulation may interfere with OAB through hypogastric nerve activation and pudendal nerve neuromodulation.