Neuropeptides in lower urinary tract function

The role of sodium hyaluronate and sodium chondroitin sulphate in the management of bladder disease

Bladder epithelium is not only a simple defence against infections, but it is also a specialized tissue regulating complex bladder functions and playing an active role in the pathogenesis of many bladder diseases. There is strong evidence that different chronic inflammatory bladder diseases, such as recurrent urinary tract infection (UTI), chemical or radiation cystitis and painful bladder syndrome/interstitial cystitis (PBS/IC), can be pathophysiologically linked in the first step of the disease to the loss of the glycosaminoglycan (GAG) mucous layer independently of the original cause of the inflammatory process. The aim of this article is to review the current evidence on the clinic applications of GAGs in urology, with particular emphasis on the therapeutic use of hyaluronic acid (HA) and chondroitin sulphate (CS). A comprehensive electronic literature search was conducted in May 2011 using the Medline database. Three studies supported the decrease of the rate of recurrent UTIs by restoring the GAG layer, showing a significant reduction of UTI rates and a prolonged median time to recurrence after HA intravesical instillations in women with recurrent UTI. We provide higher level evidence by reporting a prospective, randomized, double-blind, placebo-controlled study on the use of intravesical HA and CS in women with recurrent UTIs. A significant reduction of 77% in the UTI rate per patient per year versus placebo was observed at the end of the study. Nine studies were published between 2002 and 2011 on the use of HA and CS to treat PBS/IC. Three of them evaluated the use of GAGs bladder instillation to prolong the effects of bladder hydrodistension. In the other six studies the efficacy of HA bladder instillations to reduce symptoms score was assessed. Preliminary studies support data on the role of HA-CS in detrusor overactivity, nonbacterial cystitis and urological malignancies. Few data are available regarding the mode of action of HA-CS or its effectiveness in the management of bladder diseases. The major issue in interpreting the available evidence regarding HA-CS is that most of the reported studies are nonrandomized and without a control arm. HA-CS may be considered for further studies, including randomized, controlled trials with adequate power.

Bladder outlet physiology in the context of lower urinary tract dysfunction

Physiological function of the bladder outlet is complex and symptomatic consequences can result from outlet dysfunction. Within the outlet, smooth, and skeletal muscles constitute the contractile apparatus, but additional cell types include interstitial cells and neuroendocrine cells, and various transmitters are present in the innervation, raising the possibility of unrecognized functional subtleties. Key outlet functions are; maintained closure for urine storage, increased closure (guarding) during exertion, sustained opening for voiding, transient opening for territorial marking in animals and orthograde male ejaculation. These are co-ordinated by several spinal and higher CNS centers, with overlap of the somatic, sympathetic and parasympathetic nervous systems. During voiding, urethral afferents may be important in maintaining detrusor contraction until completion of bladder emptying. Some of the bladder outlet afferents may be shared with the anal sphincter. Dysfunction of the outlet leads to conditions such as retrograde ejaculation, Fowler's syndrome, and detrusor sphincter dyssynergia. Urethral relaxation during urine storage may lead to urinary urgency, which may be misleadingly labeled as overactive bladder. Research priorities are numerous, including; peripheral cellular integrative physiology, interactions with other pelvic organs, interconnectivity of the CNS centers at all levels of the neuraxis, and standardized animal models of outlet functions such as reflex-driven voiding.