Central nervous system mechanisms involved in inhibition of micturition reflex by gentle mechanical skin stimulation

Abstract

Gentle tactile stimulation of the skin using a roller (somaplane) has an inhibitory effect on micturition contraction of the urinary bladder in anesthetized rat. The stimulation is clinically applied to self-care of overactive bladder. On the other hand, basic and clinical studies on neuromodulation in which electrical stimulation of pudendal nerve or tibial nerve regulates bladder function has been extensively studied recently. These effects are thought to be produced because the excitatory transmission of micturition reflex in the central nervous system is inhibited by segmental somatic afferent input. In order to investigate the action site of opioids mediating this inhibition and the action on descending or ascending transmission related to micturition reflex, we administered naloxone intrathecally, stimulated pontine micturition center or descending pathway therefrom, and recorded response of lumbosacral blood flow during bladder distention and evoked potential by pelvic afferent stimulation using anesthetized rats. In this article, I will introduce the recent findings on the central mechanism of somato-bladder inhibitory reflexes, mainly on our research on gentle skin stimulation.