The afferent system and its role in lower urinary tract dysfunction

Lower urinary tract disorders such as overactive bladder syndrome (OABS) and interstitial cystitis/painful bladder syndrome (IC/PBS) are debilitating conditions with serious adverse effects on quality of life. Common to both OABS and IC/PBS are the sensory symptoms of urgency and frequency, implicating the afferent system in the aetiology of these disorders. Thus, understanding the role that afferent pathways play in the function of the lower urinary tract is the focus of much current research. This review aims to provide an insight into the recent advances in this field.

Sensory transduction in the bladder is not only mediated by direct activation of the afferents via a host of receptors and ion channels located on the afferent terminal but also may be attributed to the interplay between the urothelium and the release of urothelially derived mediators. Recent studies provide compelling evidence to support this concept and highlight the complex nature of the bladder afferent system.

Recent studies provide further evidence that afferent control of the bladder may be dependent on integration of excitatory and inhibitory mediators from the urothelium such as ATP and nitric oxide. A number of studies have examined the role cholinergic and adrenergic mechanisms play in bladder afferent function, and several new potential mechanisms involving the cannabinoid receptors and transient receptor potential channels have emerged as areas which warrant further investigation. A better understanding of afferent mechanisms in the bladder will hopefully lead to more effective treatments of lower urinary tract disorders.