Effects of Tramadol on Rat Detrusor Overactivity Induced by Experimental Cerebral Infarction

Urodynamic Parameters in Spinal Cord Injury-Induced Neurogenic Bladder Rats after Stem Cell Transplantation: A Narrative Review

Neurogenic bladder (NGB) secondary to spinal cord injury (SCI) is accompanied with several complications such as urinary tract deterioration, urinary incontinence, and consequently lower quality of life (QoL), significant morbidities, and occasionally death. Current therapeutic methods have some side effects and there is no treatment for the upper urinary tract injuries. Stem cell therapy is a promising method for treating this condition. However, the best timing and the best route of its transplantation have not yet been determined. Animal models of SCI, especially in rats, are the most commonly used method for evaluating the efficacy of cell therapy in NGB improvement, and the most common assessment method is the urodynamic studies (UDS). However, there are variations in the range of UDS parameters among the published studies. The current review aimed to discuss the effect of stem cell transplantation on bladder dysfunction recovery based on urodynamic parameters after SCI in rats. For this purpose, the cell source, doses, the route of administration, and the complete UDS equipment and its parameters were summarized in SCI models in rats. In some urodynamic test results, to some extent, an improvement in the lower urinary system function was observed in each treatment group. However, this improvement was far from full functional recovery. The average cell dose was about 1 million cells in every injected site. In most studies, the stem cells (SCs) were transplanted 9 days after the injury using PE-50 and PE-60. Many researchers have recommended further experimental and clinical studies to confirm this treatment modality.

Association between Female Urinary Incontinence and Geriatric Health Problems: Results from Korean Longitudinal Study of Ageing (2006)

Background

Urinary incontinence (UI) is highly prevalent in the aging population. UI is one of the most common geriatric syndromes and affects overall health, quality of life, and economical burden in patients. The aims of this study were to investigate the characteristics of patients with UI and to assess its association with other geriatric health problems.

Methods

We used data from the Korean Longitudinal Study of Ageing obtained in 2006. Among the 10,254 individuals aged 45 years and older, we analyzed data from 2,418 women aged 65 years and older. Data were obtained using questionnaires for UI, comorbidities, and lifestyle factors.

Results

Among the 2,418 women aged 65 years and older, 506 (20.9%) had UI. Cerebrovascular disease (odds ratio [OR], 2.02; 95% confidence interval [CI], 1.26 to 3.23), arthritis (OR, 1.44; 95% CI, 1.18 to 1.77), and fear of falling (OR, 1.62; 95% CI, 1.18 to 2.22) were significantly associated with UI, while chronic lung disease, psychiatric disease, difficulty in daily living due to visual and hearing problems, and experiencing a fall in the last 2 years were not associated with UI.

Conclusion

Cerebrovascular disease, arthritis, and especially fear of falls were significantly associated with UI in elderly Korean women.

Investigational Drug Therapies for Overactive Bladder Syndrome: The Potential Alternatives to Anticolinergics

Background

Overactive bladder is a high prevalent and quality of life affecting disease. The mainstay of the medical therapy is represented by antimuscarinic drugs, but their side effects markedly affect patient compliance and prompt studies on novel investigational drugs.

Methods

A systematic literature search of peer-reviewed papers and meeting abstracts published by December 2008 was performed. PubMed databank was searched for original English articles, by using the following search terms: “overactive bladder” or “detrusor overactivity” or “urinary incontinence” and “treatment”, alone and linked to any potential molecular target or novel drug cited in the literature.

Results

Effective alternative pharmacological treatments are currently scarce, but many new promising compounds are emerging which target key molecular pathways involved in micturition control. The most promising potential therapeutic targets include central nervous system GABAergic inhibitory pathway, dopaminergic and serotoninergic systems, b-adrenoceptors and cAMP metabolism, nonadrenergic-noncholinergic mechanisms such as purinergic and neuropeptidergic systems, vanilloid receptor, bladder sensory nervous terminals, nonneuronal bladder signalling systems including urothelium and interstitial cells, prostanoids, Rho-kinase and different subtypes of potassium and calcium channels.

Conclusions

Despite the enormous amount of new biologic insight, very few novel pharmacological therapies seems to have passed the proof-of-concept clinical stage. The ultimate clinical utility of new drugs will depend on the ability to exploit tissue-specific differences and disease-related changes in molecular expression/function and to improve storage phase dysfunctions without interfering with the emptying phase. Further preclinical investigations and controlled clinical trials are urgently needed in this challenging field.

Pathophysiology, Clinical Importance, and Management of Neurogenic Lower Urinary Tract Dysfunction Caused by Suprasacral Spinal Cord Injury

Management of persistent lower urinary tract dysfunction resulting from severe thoracolumbar spinal cord injury can be challenging. Severe suprasacral spinal cord injury releases the spinal cord segmental micturition reflex from supraspinal modulation and increases nerve growth factor concentration in the bladder wall, lumbosacral spinal cord, and dorsal root ganglion, which subsequently activates hypermechanosensitive C-fiber bladder wall afferents. Hyperexcitability of bladder afferents and detrusor overactivity can cause urine leaking during the storage phase. During urine voiding, the loss of supraspinal control that normally coordinates detrusor contraction with sphincter relaxation can lead to spinal cord segmental reflex-mediated simultaneous detrusor and sphincter contractions or detrusor-sphincter dyssynergia, resulting in inefficient urine voiding and high residual volume. These disease-associated changes can impact on the quality of life and life expectancy of spinal-injured animals. Here, we discuss the pathophysiology and management considerations of lower urinary tract dysfunction as the result of severe, acute, suprasacral spinal cord injury. In addition, drawing from experimental, preclinical, and clinical medicine, we introduce some treatment options for neurogenic lower urinary tract dysfunction that are designed to: (1) prevent urine leakage arising because of detrusor overactivity during bladder filling, (2) preserve upper urinary tract integrity and function by reducing intravesical pressure and subsequent vesicoureteral reflux, and (3) prevent urinary tract and systemic complications by treating and preventing urinary tract infections.

Urodynamic characteristics of awake rats under retrained versus freely moving condition: Using a novel model

Urodynamic investigation in conscious rats is widely employed to explore functional bladder disorders of various etiologies and pathogeneses. Rats can be placed in restraining cages or wide cabinets where they are allowed to move freely during cystometry. However, the requirements of special devices hampered the application of urodynamic test in freely moving rats, and whether the restraint has any effects on urodynamic parameters in conscious rats remains obscure. In the present study, we described a novel approach for urodynamic investigation in both restrained and freely moving conscious rats. In addition, we for the first time systematically compared the urodynamic parameters of rats in the two conditions. With the current method, we successfully recorded stable and repeatable intravesical pressure traces and collected expected reliable data, which supported the idea that the restraint does not affect the activity of the micturition reflex in rats, provided sufficient and appropriate measures could be applied during cystometry. Fewer technique problems were encountered during urodynamic examination in restrained rats than in freely moving ones. Taken together, conscious cystometry in rats placed in restraining cages with proper managements is a reliable and practical approach for evaluating the detrusor activity and bladder function.

In vitro and in vivo pharmacological profile of the selective β3-adrenoceptor agonist mirabegron in rats

To investigate the pharmacological properties of mirabegron in in vitro and in vivo, the effects on cAMP accumulation in Chinese hamster ovary (CHO) cells expressing rat β-adrenoceptors, the relaxant activity in isolated rat bladder smooth muscle, and the voiding effects in cerebral infarcted rats were evaluated. Mirabegron increased cAMP accumulation with EC(50) value and intrinsic activity of 19 nmol/L and 1.0, respectively, in CHO cells expressing rat β(3)-adrenoceptors. The EC(50) values and the intrinsic activities of mirabegron were 610 nmol/L and 0.6 for rat β(1)-adrenoceptors and were sumless and 0.1 for β(2)-adrenoceptors, respectively. Mirabegron showed concentration-dependent relaxant and full agonistic effects in rat bladder strips under passive tension with EC(50) value of 290 nmol/L. The concentration-response curve of mirabegron was affected neither by the β(1)-adrenoceptor selective antagonist CGP-20712A nor by the β(2)-adrenoceptor selective antagonist ICI-118,551. In in vivo studies with cerebral infarcted rats, a significant decrease in the volume voided per micturition compared with sham-operated rats was observed. Mirabegron dose-dependently increased the volume voided per micturition. In conclusion, we have extended the selectivity profile of mirabegron to rats and demonstrated that it is effective via stimulation of β(3)-adrenoceptors in a rat cerebral infarction model of detrusor overactivity.

Combination of foot stimulation and tramadol treatment reverses irritation induced bladder overactivity in cats

PURPOSE

We determined whether transcutaneous electrical foot stimulation combined with a low dose of tramadol (Sigma-Aldrich®) could completely suppress bladder overactivity.

MATERIALS AND METHODS

Repeat cystometrograms were performed in 18 α-chloralose anesthetized cats by infusing the bladder with saline or 0.25% acetic acid. Transcutaneous electrical stimulation (5 Hz) of the cat hind foot at 2 to 4 times the threshold intensity needed to induce observable toe movement was applied to suppress acetic acid induced bladder overactivity. Tramadol (1 to 3 mg/kg intravenously) was administered to enhance foot inhibition.

RESULTS

Acetic acid irritated the bladder, induced bladder overactivity and significantly decreased bladder capacity to a mean ± SE of 26% ± 5% of saline control capacity (p <0.01). Without tramadol, foot stimulation at 2 and 4 threshold intensity applied during acetic acid cystometrograms significantly increased bladder capacity to a mean of 47% ± 5% and 62% ± 6% of saline control capacity, respectively (p <0.05). Without foot stimulation, tramadol (1 mg/kg) only slightly changed bladder capacity to a mean of 39% ± 2% of saline control capacity (p >0.05), while 3 mg/kg significantly increased capacity to 85% ± 14% that of control (p <0.05). However, 1 mg/kg tramadol combined with foot stimulation increased bladder capacity to a mean of 71% ± 18% (2 threshold intensity) and 84% ± 14% (4 threshold intensity), respectively, which did not significantly differ from saline control capacity. In addition, long lasting (greater than 1.5 to 2 hours) post-stimulation inhibition was induced by foot stimulation combined with 3 mg/kg tramadol treatment.

CONCLUSIONS

This study suggests a new treatment strategy for overactive bladder by combining foot stimulation with a low dose of tramadol, which is noninvasive and has potentially high efficacy and fewer adverse effects.

Inhibition of bladder overactivity by a combination of tibial neuromodulation and tramadol treatment in cats

Our recent study in cats revealed that inhibition of bladder overactivity by tibial nerve stimulation (TNS) depends on the activation of opioid receptors. TNS is a minimally invasive treatment for overactive bladder (OAB), but its efficacy is low. Tramadol (an opioid receptor agonist) is effective in treating OAB but elicits significant adverse effects. This study was to determine if a low dose of tramadol (expected to produce fewer adverse effects) can enhance the TNS inhibition of bladder overactivity. Bladder overactivity was induced in α-chloralose-anesthetized cats by an intravesical infusion of 0.25% acetic acid (AA) during repeated cystometrograms (CMGs). TNS (5 Hz) at two to four times the threshold intensity for inducing toe movement was applied during CMGs before and after tramadol (0.3-7 mg/kg iv) to examine the interaction between the two treatments. AA irritation significantly reduced bladder capacity to 24.8 ± 3.3% of the capacity measured during saline infusion. TNS alone reversibly inhibited bladder overactivity and significantly increased bladder capacity to 50-60% of the saline control capacity. Tramadol administered alone in low doses (0.3-1 mg/kg) did not significantly change bladder capacity, whereas larger doses (3-7 mg/kg) increased bladder capacity (50-60%). TNS in combination with tramadol (3-7 mg/kg) completely reversed the effect of AA. Tramadol also unmasked a prolonged (>2 h) TNS inhibition of bladder overactivity that persisted after termination of the stimulation. The results suggest a novel treatment strategy for OAB by combining tibial neuromodulation with a low dose of tramadol, which is minimally invasive with a potentially high efficacy and fewer adverse effects.

Rodent models for urodynamic investigation

Rodents, most commonly rats, mice, and guinea pigs are widely used to investigate urinary storage and voiding functions, both in normal animals and in models of disease. An often used methodology is cystometry. Micturitions in rodents and humans differ significantly and this must be considered when cystometry is used to interpret voiding in rodent models. Cystometry in humans requires active participation of the investigated patient (subject), and this can for obvious reasons not be achieved in the animals. Cystometric parameters in rodents are often poorly defined and do not correspond to those used in humans. This means that it is important that the terminology used for description of what is measured should be defined, and that the specific terminology used in human cystometry should be avoided. Available disease models in rodents have limited translational value, but despite many limitations, rodent cystometry may give important information on bladder physiology and pharmacology. The present review discusses the principles of urodynamics in rodents, techniques, and terminology, as well as some commonly used disease models, and their translational value.

Ameliorating effects of cloperastine on dysfunction of the urinary bladder caused by cerebral infarction in conscious rats

We investigated the effects of the centrally acting antitussives dextromethorphan and cloperastine on urinary bladder dysfunction 24 h after cerebral infarction in rats using the cystometry technique. First, cystometrography was performed in conscious male Sprague-Dawley rats. Cerebral infarction was then induced by occlusion of the left middle cerebral artery. Twenty-four hours after cerebral infarction, the effect of each drug on micturition disorder was estimated for 5 parameters: bladder capacity, maximum voiding pressure, micturition latency, flow rate, and urethral resistance. Cerebral infarction markedly reduced bladder capacity, micturition latency, and flow rate and increased urethral resistance. After cerebral infarction, intravenous dosing of saline had no effect on these parameters. Dextromethorphan (20 mg/kg) and cloperastine (2.5 and 5.0 mg/kg) at antitussive effective doses significantly increased bladder capacity and micturition latency. Unlike dextromethorphan, cloperastine ameliorated decreases in flow rate and increases in urethral resistance caused by cerebral infarction. These results suggest that cloperastine may have therapeutic value for the treatment of disorders of the micturition reflex associated with cerebral infarction, and that the drug may become a base compound from which to develop more active drugs for such disorders.

Prospective pharmacologic therapies for the overactive bladder

Lower urinary tract symptoms (LUTS), overactive bladder syndrome (OAB) and detrusor overactivity (DO) are all conditions that can have major effects on quality of life and social functioning. Antimuscarinic drugs are first-line treatment-they often have good initial response rates, but adverse effects and decreasing efficacy cause long-term compliance problems, and alternatives are needed. The recognition of the functional contribution of the urothelium, the spontaneous myocyte activity during bladder filling, and the diversity of nerve transmitters has sparked interest in both peripheral and central modulation of LUTS/OAB/DO pathophysiology. There may be several new possibilities to treat LUTS/OAB/DO. β(3)-AR agonists (YM178), PDE 5 inhibitors (sildenafil, tadalafil, vardenafil), vitamin D analogs (elocalcitol), combinations (α(1)-AR antagonist + antimuscarinic), and drugs with a central mode of action (tramadol, aprepitant) all have Randomized controlled trial (RCT) documented efficacy. Which of these therapeutic principles will be developed to clinically useful treatments remains to be established.

Effect of lumbar-epidural administration of tramadol on lower urinary tract function

AIMS

Intrathecal and epidural administration of micro-agonist opioids is associated with urinary retention, a potentially serious adverse-event. In animal studies tramadol has been found not to affect voiding function. We evaluated urodynamic effects of epidural tramadol in humans.

METHODS

Fifteen adults planned for cystoscopy under local-anesthesia underwent urodynamics (UDS) at baseline and 30 min after administration of 100 mg tramadol in lumbar-epidural space. UDS consisted of filling cystometry, pressure-flow study and pelvic floor electromyography (EMG). Subsequently, all underwent cystoscopy and were observed for 6 hr.

RESULTS

After injection of tramadol, a significant rise was observed in bladder capacity (391.8 +/- 179.6 ml vs. 432.7 +/- 208.8 ml; P = 0.019) and compliance (60.1 +/- 51.5 ml/cm H(2)O vs. 83.0 +/- 63.0 ml/cm H(2)O; P = 0.011) without a significant change in filling pressure (22.5 +/- 13.2 cm H(2)O vs. 24.1 +/- 15.1 cm H(2)O; P = 0.576). Filling sensations were delayed significantly (P < or = 0.05). EMG during filling phase showed a significant fall (P = 0.027). Peak flow-rate (Q(max)), average flow-rate, postvoid residue and detrusor pressure-at-Q(max) did not show significant change from baseline (P > 0.05). Three patients had bladder outlet obstruction which did not worsen after the injection. Guarding reflex was inhibited in seven out of 12 patients who had it at baseline (P = 0.016).

CONCLUSIONS

Epidural tramadol increases the bladder capacity and compliance and delays filling-sensations, without ill effect on voiding. This seems true even for patients with obstructed outflow; however, due to small number of patients a definite conclusion cannot be derived. These results will guide clinician to avoid catheterization in cases where epidural tramadol is used for postoperative pain. The inhibitory effects of tramadol on EMG activity are intriguing and need further studies.

Emerging pharmacological targets in overactive bladder therapy: experimental and clinical evidences

Antimuscarinics are the mainstay of the medical therapy for overactive bladder, but their side effects and often modest success have prompted studies on novel pharmacological approaches. In this paper, we give a systematic literature review of peer-reviewed papers on the subject. Effective nonantimuscarinic treatments are currently scarce, but many new promising compounds are emerging, which target key molecular pathways involved in micturition control. The most promising potential therapeutic targets include: nervous GABAergic, glycinergic, dopaminergic, and serotonergic systems; b-adrenoceptors and cAMP metabolism; nonadrenergic-noncholinergic mechanisms such as purinergic and neuropeptidergic systems; vanilloid receptors; bladder afferent nerves; nonneuronal bladder signaling systems including urothelium and interstitial cells; prostanoids; Rho-kinase; and different subtypes of potassium and calcium channels. Despite the enormous amount of new biologic insight, very few drugs with mechanism of action other than antimuscarinics have passed as yet the proof-of-concept stage. Further preclinical and clinical studies are urgently needed in this rapidly moving field.

LUTS treatment: Future treatment options

Lower urinary tract symptoms (LUTS) are commonly divided into storage, voiding, and postmicturition symptoms, and may occur in both men and women. Male LUTS have historically been linked to benign prostatic hyperplasia (BPH), but are not necessarily prostate related. The focus of treatment for LUTS has thus shifted from the prostate to the bladder and other extraprostatic sites. LUTS include symptoms of the overactive bladder (OAB), which are often associated with detrusor overactivity. Treatment for LUTS suggestive of BPH has traditionally involved the use of alpha(1)-adrenoceptor (AR) antagonists; 5alpha-reductase inhibitors; and phytotherapy-however, several new therapeutic principles have shown promise. Selective beta(3)-adrenoceptor agonists and antimuscarinics are potentially useful agents for treating LUTS, particularly for storage symptoms secondary to outflow obstruction. Other agents of potential or actual importance are antagonists of P2X(3) receptors, botulinum toxin type A, endothelin (ET)-converting enzyme inhibitors, and drugs acting at vanilloid, angiotensin, and vitamin D(3) receptor sites. Drugs interfering with the nitric oxide/cGMP-cAMP pathway, Rho-kinase and COX inhibitors, as well as drugs targeting receptors and mechanisms within the CNS, are also of interest and deserving of further study for the treatment of LUTS.

Safety and efficacy of tramadol in the treatment of idiopathic detrusor overactivity: a double-blind, placebo-controlled, randomized study

AIM

To evaluate the efficacy and safety of tramadol in patients with idiopathic detrusor overactivity (IDO).

METHODS

A total of 76 patients 18 years or older with IDO were randomly assigned to receive 100 mg tramadol sustained release (group 1, n = 38) or placebo (group 2, n = 38) every 12 h for 12 weeks. Clinical evaluation was performed at baseline and every 2 weeks during treatment. All patients underwent urodynamics and ice water test at baseline and 12-week treatment. Main outcome measures were number of voids per 24 h, urine volume per void and episodes of urge incontinence per 24 h on a frequency volume chart and detailed recording of adverse effect.

RESULTS

After 12 weeks of treatment mean number of voids per 24 h +/- SD decreased from 9.3 +/- 3.2 to 5.1 +/- 2.1 (P < 0.001 vs. placebo) [95% confidence interval (CI) -5.1--0.4]. At that time mean urine volume per void increased from 158 +/- 32 to 198 +/- 76 ml (P < 0.001 vs. placebo) (95% CI 8-22), while mean number of incontinence episodes per 24 h decreased from 3.2 +/- 3.3 to 1.6 +/- 2.8 (P < 0.001 vs. placebo) (95% CI -2-0.3). Tramadol induced significant improvements in urodynamic parameters. More adverse effects were associated with tramadol treatment than with placebo (P < 0.05). The main adverse event with tramadol was nausea.

CONCLUSIONS

In patients with non-neurogenic IDO tramadol provided beneficial clinical and urodynamic results. Further studies are required to draw final conclusions on the efficacy of this drug in IDO.

Effects of solifenacin succinate (YM905) on detrusor overactivity in conscious cerebral infarcted rats

Solifenacin succinate [YM905, (+)-(1S,3'R)-quinuclidin-3'-yl 1-phenyl-1,2,3,4-tetrahydroisoquinoline-2-carboxylate monosuccinate] is a novel muscarinic receptor antagonist. We examined the effects of solifenacin and two other muscarinic receptor antagonists, tolterodine and propiverine, on detrusor overactivity in cerebral infarcted rats. Evaluation was done under conscious conditions using cystometry 1 day after middle cerebral artery occlusion. The cerebral infarcted rats showed decreases in bladder capacity and voided volume and an increase in residual volume, but no change in micturition pressure. Solifenacin increased bladder capacity and voided volume at doses of 0.03 mg/kg i.v. or more. Tolterodine increased bladder capacity and voided volume at 0.03 and 0.1 mg/kg i.v., while propiverine increased bladder capacity and voided volume at 1 mg/kg i.v. and at 0.3 and 1 mg/kg i.v., respectively. In contrast, none of the three drugs affected residual volume or micturition pressure. These results suggest that solifenacin may improve detrusor overactivity without causing urinary retention and may be a promising drug in the treatment of patients with overactive bladder syndrome.

Pharmacology of the lower urinary tract: basis for current and future treatments of urinary incontinence

The lower urinary tract constitutes a functional unit controlled by a complex interplay between the central and peripheral nervous systems and local regulatory factors. In the adult, micturition is controlled by a spinobulbospinal reflex, which is under suprapontine control. Several central nervous system transmitters can modulate voiding, as well as, potentially, drugs affecting voiding; for example, noradrenaline, GABA, or dopamine receptors and mechanisms may be therapeutically useful. Peripherally, lower urinary tract function is dependent on the concerted action of the smooth and striated muscles of the urinary bladder, urethra, and periurethral region. Various neurotransmitters, including acetylcholine, noradrenaline, adenosine triphosphate, nitric oxide, and neuropeptides, have been implicated in this neural regulation. Muscarinic receptors mediate normal bladder contraction as well as at least the main part of contraction in the overactive bladder. Disorders of micturition can roughly be classified as disturbances of storage or disturbances of emptying. Failure to store urine may lead to various forms of incontinence, the main forms of which are urge and stress incontinence. The etiology and pathophysiology of these disorders remain incompletely known, which is reflected in the fact that current drug treatment includes a relatively small number of more or less well-documented alternatives. Antimuscarinics are the main-stay of pharmacological treatment of the overactive bladder syndrome, which is characterized by urgency, frequency, and urge incontinence. Accepted drug treatments of stress incontinence are currently scarce, but new alternatives are emerging. New targets for control of micturition are being defined, but further research is needed to advance the pharmacological treatment of micturition disorders.

New objective measures to quantify stress urinary incontinence in a novel durable animal model of intrinsic sphincter deficiency

Existing animal models of stress urinary incontinence (SUI) are limited because of the low rate of incontinence seen in the animals and to their relatively low durability. In addition, most methods described to measure incontinence are operator-dependent. The aim of this study was to develop a new durable animal model of SUI and establish objective measures to quantify SUI. We subjected female rats to transabdominal urethrolysis. At baseline and at 1, 4, 8, 12, and 24 wk after intervention, animals underwent cystometry and evaluation with abdominal leak point pressure (ALPP). Urethral resistance was evaluated by retrograde urethral perfusion pressure (RUPP). Tissues were obtained for histology and immunohistochemistry. Normal female rats had an average ALPP of 19.4 cmH2O and RUPP of 22.6 cmH2O at baseline. More than 93% of the animals had significantly decreased ALPP and RUPP after the procedure. The mean ALPP and RUPP decreased to 9.8 cmH2O and 11.2 cmH2O, respectively, by 1 wk after urethrolysis. These changes were maintained for up to 24 wk. Changes seen in urethral resistance and ALPP appear to be mediated by apoptosis, decreased neuronal mass, and smooth muscle atrophy. These results indicate that transabdominal urethrolysis is a reliable method of achieving durable decreased urethral resistance in a SUI model. RUPP and ALPP are objective and reproducible methods of assessing urethral resistance. Changes in continence and urethral resistance appear to be mediated by denervation and smooth muscle atrophy, which are seen in both elderly incontinent patients and in patients with intrinsic sphincter dysfunction.

CNS involvement in overactive bladder: pathophysiology and opportunities for pharmacological intervention

The pathophysiology of overactive bladder (OAB) syndrome is complex, and involves both peripheral and CNS factors. Several CNS disorders are associated with OAB, e.g. stroke, spinal cord injury, Parkinson's disease and multiple sclerosis, and in each disorder the pathophysiology of OAB can be multifactorial. Irrespective of cause or pathophysiology of OAB, antimuscarinic drugs are the first line of pharmacological treatment. However, adverse effects and limited efficacy makes alternative therapeutic principles desirable. Most alternative drugs used for the treatment of OAB have a peripheral site of action, mainly affecting efferent or afferent neurotransmission or the detrusor muscle itself. New targets for pharmacological intervention may be found in the CNS. Several CNS transmitters/transmitter systems are known to be involved in micturition control, but few drugs with a defined CNS site of action (e.g. baclofen, imipramine and duloxetine) have been used for the treatment of voiding disorders. GABA, glutamate, opioid, serotonin, noradrenaline (norepinephrine), and dopamine receptors and mechanisms are known to influence micturition, and drugs influencing these systems could potentially be developed for the treatment of OAB. Preclinical studies in different animal models have shown that modulation of normal micturition and detrusor overactivity by drugs acting within the spinal cord or supraspinally is possible. Promising results have been obtained in such models, e.g. with drugs interfering with GABA mechanisms, serotonin 5-HT1A receptors, mu-opioid receptors and alpha-adrenoreceptors. However, considering the limited predictability of existing animal models for efficacy in humans, positive proof of concept studies in humans are mandatory. Such studies are scarce and further investigations are needed.

New pharmacologic targets for the treatment of the overactive bladder: an update

Although currently available antimuscarinic agents are the standard of care for overactive bladder (OAB), they are limited by certain side effects, particularly dry mouth and constipation. Research aimed at discovering new therapies for OAB has resulted in the identification of some promising drugs. Investigations of pharmacologic targets in the central nervous system (CNS) have yielded encouraging results with several agents, including tramadol and gabapentin. Further investigation may show that drugs acting at serotonergic and noradrenergic CNS sites are clinically useful as therapies for OAB. Some peripherally acting drugs, such as resiniferatoxin and botulinum toxin, have already been proved to be of clinical value. However, development of other agents that block afferent or efferent nerve impulses in the bladder through activity at vanilloid, purinergic, or opioid-like receptor sites may result in clinically useful drugs.