Changes in bladder tone during filling: pharmacological aspects

Small Fiber Polyneuropathy May Be a Nexus Between Autonomic Nervous System Dysregulation and Pain in Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a highly heterogeneous chronic and debilitating condition which effects millions of women and men in the United States. While primarily defined by urinary symptoms and pain perceived to be emanating from the bladder, IC/BPS patients frequently have co-occurring conditions and symptoms, many of which affect diverse body systems related to autonomic nervous system function. The impact on the autonomic system appears to stem from increased sympathetic innervation of the urinary tract, along with increased systemic sympathetic tone and decreased parasympathetic tone. Concurrent with these findings is evidence for destruction of peripheral sympathetic innervation to the sweat glands which may relate to small fiber polyneuropathy. It is unknown to what degree the wider alterations in autonomic function are also related to destruction/alterations in the small fibers carrying autonomic innervation. This potential nexus is an important point of investigation to better understand the unclarified pathophysiology of interstitial cystitis/bladder pain syndrome, the numerous co-occurring symptoms and syndromes, and for the identification of novel targeted therapeutic strategies.

Best practices for cystometric evaluation of lower urinary tract function in muriform rodents

AIMS

Rodent cystometry has provided valuable insights into the impact of the disease, injury, and aging on the cellular and molecular pathways, neurologic processes, and biomechanics of lower urinary tract function. The purpose of this white paper is to highlight the benefits and shortcomings of different experimental methods and strategies and to provide guidance on the proper interpretation of results.

METHODS

Literature search, selection of articles, and conclusions based on discussions among a panel of workers in the field.

RESULTS

A range of cystometric tests and techniques used to explore biological phenomena relevant to the lower urinary tract are described, the advantages and disadvantages of various experimental conditions are discussed, and guidance on the practical aspects of experimental execution and proper interpretation of results are provided.

CONCLUSIONS

Cystometric evaluation of rodents comprises an extensive collection of functional tests that can be performed under a variety of experimental conditions. Decisions regarding which approaches to choose should be determined by the specific questions to be addressed and implementation of the test should follow standardized procedures.

Regulation of urinary bladder function by protein kinase C in physiology and pathophysiology

BACKGROUND

Protein kinase C (PKC) is expressed in many tissues and organs including the urinary bladder, however, its role in bladder physiology and pathophysiology is still evolving. The aim of this review was to evaluate available evidence on the involvement of PKC in regulation of detrusor contractility, muscle tone of the bladder wall, spontaneous contractile activity and bladder function under physiological and pathophysiological conditions.

METHODS

This is a non-systematic review of the published literature which summarizes the available animal and human data on the role of PKC signaling in the urinary bladder under different physiological and pathophysiological conditions. A wide PubMed search was performed including the combination of the following keywords: "urinary bladder", "PKC", "detrusor contractility", "bladder smooth muscle", "detrusor relaxation", "peak force", "detrusor underactivity", "partial bladder outlet obstruction", "voltage-gated channels", "bladder nerves", "PKC inhibitors", "PKC activators". Retrieved articles were individually screened for the relevance to the topic of this review with 91 citations being selected and included in the data analysis.

DISCUSSION

Urinary bladder function includes the ability to store urine at low intravesical pressure followed by a subsequent release of bladder contents due to a rapid phasic contraction that is maintained long enough to ensure complete emptying. This review summarizes the current concepts regarding the potential contribution of PKC to contractility, physiological voiding, and related signaling mechanisms involved in the control of both the storage and emptying phases of the micturition cycle, and in dysfunctional voiding. Previous studies linked PKC activation exclusively with an increase in generation of the peak force of smooth muscle contraction, and maximum force generation in the lower urinary tract. More recent data suggests that PKC presents a broader range of effects on urinary bladder function including regulation of storage, emptying, excitability of the detrusor, and bladder innervation. In this review, we evaluated the mechanisms of peripheral and local regulation of PKC signaling in the urinary bladder, and their impact on different phases of the micturition cycle under physiological and pathophysiological conditions.

Local receptors as novel regulators for peripheral clock expression

Mammalian circadian control is determined by a central clock in the brain suprachiasmatic nucleus (SCN) and synchronized peripheral clocks in other tissues. Increasing evidence suggests that SCN-independent regulation of peripheral clocks also occurs. We examined how activation of excitatory receptors influences the clock protein PERIOD 2 (PER2) in a contractile organ, the urinary bladder. PERIOD2::LUCIFERASE-knock-in mice were used to report real-time PER2 circadian dynamics in the bladder tissue. Rhythmic PER2 activities occurred in the bladder wall with a cycle of ∼24 h and peak at ∼12 h. Activation of the muscarinic and purinergic receptors by agonists shifted the peak to an earlier time (7.2±2.0 and 7.2±0.9 h, respectively). PER2 expression was also sensitive to mechanical stimulation. Aging significantly dampened PER2 expression and its response to the agonists. Finally, muscarinic agonist-induced smooth muscle contraction also exhibited circadian rhythm. These data identified novel regulators, endogenous receptors, in determining local clock activity, in addition to mediating the central control. Furthermore, the local clock appears to reciprocally align receptor activity to circadian rhythm for muscle contraction. The interaction between receptors and peripheral clock represents an important mechanism for maintaining physiological functions and its dysregulation may contribute to age-related organ disorders.—Wu, C., Sui, G., Archer, S. N., Sassone-Corsi, P., Aitken, K., Bagli, D., Chen, Y. Local receptors as novel regulators for peripheral clock expression.

Overactive bladder syndrome and the potential role of prostaglandins and phosphodiesterases: an introduction

In this paper, a general introduction is given, presenting the overactive bladder syndrome (OAB) and its impact on the quality of life and economical burden in patients affected. Moreover, the anatomy, physiology and histology of the lower urinary tract are discussed, followed by a brief overview on the possible role of prostaglandin (PG) and phosphodiesterase type 5 (PDE5) in the urinary bladder. The current literature on the role and distribution of PGE2 and its receptors in the urinary bladder is discussed. In both animal models and in human studies, high levels of signaling molecules such as PG and cGMP have been implicated, in decreased functional bladder capacity and micturition volume, as well as in increased voiding contraction amplitude. As a consequence, inhibition of prostanoid production, the use of prostanoid receptor antagonists, or PDE inhibitors might be a rational way to treat patients with detrusor overactivity. Similarly, prostanoid receptor agonists, or agents that stimulate their production, might have a function in treating bladder underactivity.

Elevated steady-state bladder preload activates myosin phosphorylation: detrusor smooth muscle is a preload tension sensor

In rabbit bladder wall (detrusor) muscle, the degree of tone induced during physiological filling (filling tone) is the sum of adjustable preload tension and autonomous contractile tension. The present study was designed to determine whether the level of filling tone is dependent on detrusor muscle length. Maximum active tension induced by KCl was parabolic in relation to length [tension increased from 70% to 100% of a reference length ( Lref) and decreased at longer muscle lengths]. Filling tone, however, increased in a linear fashion from 70% to 120% Lref. In the presence of ibuprofen to abolish autonomous contraction and retain adjustable preload tension, tension was reduced in strength but remained linearly dependent on length from 70% to 120% Lref. In the absence of autonomous contraction, stretching detrusor muscle from 80% to 120% Lref still caused an increase in tone during PGE2-induced rhythmic contraction, suggesting that muscle stretch caused increases in detrusor muscle contractile sensitivity rather than in prostaglandin release. In the absence of autonomous contraction, the degree of adjustable preload tension and myosin phosphorylation increased when detrusor was stretched from 80% to 120% Lref, but also displayed length-hysteresis, indicating that detrusor muscle senses preload rather than muscle length. Together, these data support the hypothesis that detrusor muscle acts as a preload tension sensor. Because detrusor muscle is in-series with neuronal mechanosensors responsible for urinary urgency, a more thorough understanding of detrusor muscle filling tone may reveal unique targets for therapeutic intervention of contractile disorders such as overactive bladder.

Effect of silymarin on bladder overactivity in cyclophosphamide-induced cystitis rat model

The purpose of this study was to investigate the effects of silymarin, a phytotherapeutic agent, on bladder overactivity in a cyclophosphamide (CYP)-induced cystitis rat model. Female Wistar Albino rats received a single intraperitoneal injection of CYP (150 mg/kg) or saline and after 72 h, bladder function was evaluated by in vitro preparations of whole bladders and cystometry with continuous saline infusion under urethane anesthesia. Silymarin or a vehicle was orally given for 7 days in rats. CYP was injected on the 5th day of silymarin or vehicle treatment and then the animals were killed on the 8th day. CYP-treatment dramatically potentiated the basal spontaneous contractions of isolated whole bladders compared to control rats. In anesthetized rats, during continuous infusion cystometry, intercontraction interval (ICI) was significantly shorter, but bladder voiding pressure was not significantly changed in CYP-injected rats compared to control rats. In the CYP-injected group, silymarin treatment significantly decreased the amplitude, frequency (contractions/min) and area under the curve of spontaneous contractions, but failed to change carbachol-induced contraction in isolated whole bladder. Also, silymarin treatment significantly increased the ICI in comparison to the vehicle treatment. In the saline-injected group, no significant changes in the bladder function were observed between the silymarin and vehicle-treated groups. Histopathological examination showed that CYP-induced bladder inflammation tended to be lower in the silymarin+CYP-treated group. In conclusion, the oral administration of silymarin suppressed CYP-induced bladder overactivity. Silymarin may be considered as an attractive treatment for CYP-induced bladder overactivity.

Coupled nitric oxide and autonomic receptor functional responses in the normal and inflamed urinary bladder of the rat

Both divisions of the autonomic nervous system are involved in regulation of urinary bladder function. Several substances, other than noradrenaline and acetylcholine, seem to play important roles in physiology and pathophysiology of lower urinary tract. In the current study, we aimed to examine if there exist interplays between nitric oxide (NO) and autonomic transmitters and if such interactions vary in different parts of the urinary bladder in healthy and cyclophosphamide (CYP)-induced cystitic rats; when administered to the animals (100 mg/kg; i.p.), the cytotoxic CYP metabolite acrolein induces bladder inflammation. In the current study a series of in vitro functional studies were performed on detrusor muscle strip preparations. Stimulation with electrical field stimulation (EFS), methacholine, adenosine 5´-triphosphate (ATP), and adrenaline evoked contractile responses in isolated bladder preparations that were significantly reduced in cyclophosphamide (CYP)-treated rats. While the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine (L-NNA; 10(-4) M) did not affect contractile responses in normal, healthy strip preparations, it significantly increased the contractile responses to EFS, methacholine and adrenaline, but not to ATP, in the bladders from the CYP-treated rats. In the CYP-treated rats, the ATP-evoked relaxatory part of its dual response (an initial contraction followed by a relaxation) was 6-fold increased in comparison with that of normal preparations, whereas the isoprenaline relaxation was halved in the CYP-treated. While L-NNA (10(-4) M) had no effect on the isoprenaline-evoked relaxations, it reduced the ATP-evoked relaxations in strip preparations from the bladder body of CYP-treated rats. Stimulation of beta(2)- and beta(3)-adrenoceptors evoked relaxations and both responses were reduced in cystitis, the latter to a larger extent. In the trigone, the reduced ATP-evoked contractile response in the inflamed strips was increased by L-NNA, while L-NNA had no effect on the ATP-evoked relaxations, neither on the relaxations in healthy nor on the larger relaxations in the inflamed trigone. The study shows that both contractile and relaxatory functions are altered in the state of inflammation. The parasympathetic nerve-mediated contractions of the body of the bladder, evoked by the release of ATP and acetylcholine, were substantially reduced in cystitis. The relaxations to beta-adrenoceptor and purinoceptor stimulation were also reduced but only the ATP-evoked relaxation involved NO.

The forefront for novel therapeutic agents based on the pathophysiology of lower urinary tract dysfunction: pathophysiology of voiding dysfunction and pharmacological therapy

Normal lower urinary tract function consists of voiding and storage. During voiding, the pontine micturition reflex center orders the sacral parasympathetic nucleus to increase parasympathetic activity, resulting in urinary bladder detrusor contraction via activation of post-synaptic muscarinic receptors (M2/3) and in the relaxation of both urethral and prostatic smooth muscle by nitric oxide (NO). In addition, the rhabdosphincter relaxes by inhibition of the pudendal nucleus at the sacral portion. During the storage phase, increase in sympathetic activity relaxes the urinary bladder via activation of post-synaptic beta(3)-receptors and in the contraction of both urethral and prostatic smooth muscles via alpha(1)-adrenoceptor. Many factors influence voiding function, including lower urinary tract disorders (benign prostatic hyperplasia in males, urethral stricture) and neurological disorders (central and peripheral). Theories of pharmacotherapy for voiding dysfunction are 1) increase detrusor contractility and 2) decrease urethral resistance. The former includes agonists for muscarinic receptors and cholinesterase inhibitor; and the latter includes alpha(1)-adrenoceptor antagonists, NO donors, benzodiazepines, baclofen, dantrolene, and boturinum toxin.

Urodynamic Effects of Propiverine on Detrusor Overactivity and Abdominal Straining during Voiding in Awake Rats with Intravesical Prostaglandin E2Instillation

Purpose

We investigated the effect of propiverine on cystometric parameters based on intraabdominal pressure (IAP) in awake rats in an overactive bladder (OAB) model induced by intravesical instillation of prostaglandin E₂ (PGE₂).

Materials and Methods

Twenty-two female Sprague-Dawley rats were used. Polyethylene catheters were implanted into the bladder to record the intravesical pressure (IVP) and into the femoral artery to administer medication. A balloon-fitted catheter was positioned in the abdominal cavity to record the IAP. Awake cystometries were performed before and after intraarterial administration of propiverine 1 mg/kg (n=6), intravesical administration of 50µM PGE₂ only (n=6), or intravesical PGE₂ plus 1 mg/kg (n=4) or 3 mg/kg (n=6) of intraarterial propiverine. Cystometric pressure and volume parameters and variables related to detrusor overactivity (DO) were investigated.

Results

Rats administered intravesical PGE₂ showed increased pressure parameters and decreased volume parameters comparable to the DO model, which was effectively prevented by propiverine (1 or 3 mg/kg). Typical DO shown during the filling phase was decreased by intraarterial propiverine (3 mg/kg) injection. After propiverine (3 mg/kg) injection, IAP was increased at the time of micturition pressure with or without threshold pressure (p<0.05, p<0.01) depending on the dose administered.

Conclusions

Propiverine improved pressure- and volume-related parameters in an OAB model. Furthermore, it also decreased the frequency of DO. However, higher concentrations of propiverine induced straining voiding.

Trospium and cognition in patients with late onset Alzheimer disease

OBJECTIVES

Cholinesterase inhibitors for the treatment of Alzheimer's Disease (AD) and antimuscarinic agents for the treatment of urge urinary incontinence (UUI) may reduce the potential effect of each other in the patients with both diseases. Trospium has a relatively low lipophilicity and low CNS penetration, and galantamine, a cholinesterase inhibitors, has also allosterically modulates nicotinic cholinergic receptors. This study was designed to evaluate the effects of dual use of trospium and galantamine for 6 months in the elderly patients with AD and UUI.

SETTING/PARTICIPANTS

One hundred and seventy eight elderly patients: 99 UUI patients (Group I, treated with trospium), 43 AD patients (Group II, treated with galantamine) and 36 AD and UUI patients (Group III, treated with galantamine and trospium) were evaluated by geriatric assessments, the Global Perception Index (GPI), Patients' Satisfaction Question (PSQ), Estimated Patients' Improvement (EPI), nocturia and pads/day at baseline and in the 6th month.

RESULTS

Trospium increased the satisfaction of the patients in Groups I and III according to the EPI, PSQ, GPI, number of nocturia and pads/day. Decreasing in the GDS score was significant in the Group I and III (p < 0.05). Decreasing in the ADL score was significant in the Group III (p < 0.05). The MMSE scores were not significantly changed in the all groups during the 6 months.

CONCLUSION

Consequently, we have thought that a combination of trospium and galantamine could be recommended for the management of the elderly patients with UUI and AD, which are common problems in the elderly.

Effect of phosphodiesterase type 4 inhibitor rolipram on cyclophosphamide-induced cystitis in rats

Cyclophosphamide induces a severe haemorrhagic cystitis characterized by bladder overactivity. The study was conducted to examine effects of a phosphodiesterase 4 (PDE4) inhibitor rolipram on bladder overactivity in rats with cyclophosphamide treatment. 42 female Wistar rats were used. 30 rats received a single i.p. injection of cyclophosphamide, and after 72 h, bladder function was evaluated by (1) in vitro preparations of whole bladders and (2) cystometry with continuous saline infusion under urethane anesthesia. Cyclophosphamide-treatment dramatically potentiated the basal spontaneous contractions of isolated whole bladders compared to control rats. Atropine, guanethidine or suramin was ineffective on the spontaneous contractions whereas nifedipine completely abolished. Rolipram (5-80 microM) induced a significant concentration-dependent decrease on the amplitude, frequency (contractions/min) and area under the curve of spontaneous contractions. Carbachol elicited phasic contractions superimposed on a tonic contraction. Rolipram caused a relaxation on the tonic contraction whereas it could not affect the phasic contractions induced by carbachol. In anesthetized rats, during continuous infusion cystometry, intercontraction interval was significantly shorter in cyclophosphamide-injected rats than in control rats. Rolipram at 5-40 microM has no significant effect on the intercontraction interval and contraction pressure while it significantly decreased pressure threshold. At 80 microM, it significantly decreased the intercontraction interval and contraction pressure. In conclusion, PDE4 inhibitor rolipram caused a significant decrease on the amplitude, frequency and area under the curve of basal spontaneous contractions in cyclophosphamide-treated rats, at doses that have no effect on the carbachol-induced phasic contractions and cystometric parameters. PDE4 inhibitors may be considered as an attractive strategy for the treatment of cyclophosphamide-induced bladder overactivity.

The effects of a type 4 phosphodiesterase inhibitor and the muscarinic cholinergic antagonist tolterodine tartrate on detrusor overactivity in female rats with bladder outlet obstruction

OBJECTIVE

To investigate the effects of the selective phosphodiesterase (PDE) type 4 inhibitor IC485 and the widely used antimuscarinic drug tolterodine tartrate on bladder activity in rats with bladder outlet obstruction (BOO), as inhibition of PDE4 leads to elevation of intracellular cAMP levels and relaxation of smooth muscle.

MATERIALS AND METHODS

BOO was induced in female Sprague-Dawley rats by tying a silk ligature around the urethra. Six weeks after inducing BOO, conscious rats were assessed by cystometry with the urethral ligature intact. The effects of IC485 (5, 10 and 50 mg/kg intravenous, i.v.) were examined and compared with those of tolterodine (0.01, 0.1 and 1 mg/kg i.v.).

RESULTS

IC485 (5-50 mg/kg i.v.) decreased the number and amplitude of non-voiding contractions during the storage phase by 63-88% and 49-83%, respectively; IC485 also increased bladder capacity by 28-37%. There was no change in blood pressure after applying IC485. Tolterodine tartrate (0.1 and 1.0 mg/kg) significantly decreased the number and amplitude of non-voiding contractions by 38-74% and 29-44%, respectively, and increased bladder capacity by 19-51%. Whereas voiding efficiency and maximum voiding pressure were not altered by IC485 at any dose, tolterodine significantly reduced both, by 35-67% and 19-34%, respectively.

CONCLUSION

Both IC485 and tolterodine tartrate reduced detrusor overactivity in rats with BOO. In addition, doses of IC485 that suppressed non-voiding contractions had no effect on voiding function. Therefore, selective PDE4 inhibitors deserve further study as potential agents for treating detrusor overactivity in patients with BOO.

Muscarinic receptors in the bladder: from basic research to therapeutics

Muscarinic receptor antagonists (antimuscarinics) serve as the cornerstone in the pharmacological management of overactive bladder (OAB) by relieving the symptoms of urgency, frequency and incontinence. These drugs operate primarily by antagonizing post-junctional excitatory muscarinic receptors (M(2)/M(3)) in the detrusor. The combination of pharmacological and gene knockout studies has greatly advanced our understanding of the functional role of muscarinic receptors in the bladder. M(3) receptors produce direct smooth muscle contraction by a mechanism that relies on entry of extracellular calcium through L-type channels and activation of a rho kinase. M(2) receptors, which predominate in number, appear to facilitate M(3)-mediated contractions. M(2) receptors can also produce bladder contractions indirectly by reversing cAMP-dependent beta-adrenoceptor-mediated relaxation, although the physiological role of beta-adrenoceptors in detrusor relaxation is controversial. Emerging evidence suggests that muscarinic receptors in the urothelium/suburothelium can modulate the release of certain factors, which in turn may affect bladder function at the efferent or afferent axis. Currently, oxybutynin, tolterodine, darifenacin, solifenacin and trospium are the five major antimuscarinics approved for the treatment of OAB. Comparative clinical studies have shown that oxybutynin and solifenacin may be marginally more effective than tolterodine, although the latter seems to be better tolerated. Pharmacokinetic-pharmacodynamic analyses using plasma concentrations of 'total drug' indicate that, at therapeutic doses, the clinical efficacy of darifenacin and solifenacin may be driven primarily by selective M(3) receptor occupation, whereas the pharmacodynamic effects of pan-selective molecules (such as tolterodine, trospium) may potentially involve multiple receptors, including M(2) and M(3). Furthermore, high M(3) receptor occupation is the likely explanation for the greater propensity of darifenacin and oxybutynin to cause dry mouth and/or constipation. Although the recently introduced drugs represent a significant improvement over older drugs, especially with respect to the convenience of dosing schedule, their overall efficacy and tolerability profile is still less than optimal and patient persistence with therapy is low. Recent advances in basic research have not yet offered a clear discovery path for improving the therapeutic index of antimuscarinic molecules. There is still an unmet need for an antimuscarinic medicine with superior clinical effectiveness that can translate into better persistence on therapy.

Suppression of detrusor overactivity in rats with bladder outlet obstruction by a type 4 phosphodiesterase inhibitor

OBJECTIVE

To investigate the effects of a selective type 4 cyclic nucleotide phosphodiesterase (PDE4) inhibitor, IC486051, on bladder activity in normal rats and those with and bladder outlet obstruction (BOO), as inhibition of PDE4 leads to elevation of intracellular cAMP levels and relaxation of smooth muscle.

MATERIALS AND METHODS

BOO was induced in female Sprague-Dawley rats by tying a silk ligature around the urethra. At 4 or 6 weeks after inducing BOO, conscious rats were assessed by cystometry with the urethral ligature intact. In unobstructed rats, blood pressure was also measured.

RESULTS

In unobstructed rats, IC486051 (0.1 mg/kg intravenously) produced no significant changes in cystometric variables, while at a dose of 0.5 mg/kg maximum voiding pressure was reduced by 34%. At both doses, there was a small, transient increase in blood pressure. In both 4- and 6-week BOO rats IC486051 dose-dependently decreased the number and amplitude of non-voiding bladder contractions by up to 80%, relative to pre-treatment values. At doses of 0.1 and 0.5 mg/kg IC486051 had no significant effect on voiding variables. In the 4-week BOO rats, a dose of 1.0 mg/kg decreased bladder capacity, voided volume and residual volume by 21%, 32% and 18%, respectively. In 6-week BOO rats, a dose of 1.0 mg/kg decreased maximal voiding pressure by 17% and pressure threshold for voiding by 28%. In both groups of rats with BOO, voiding efficiency was unchanged.

CONCLUSIONS

A selective PDE4 inhibitor can effectively suppress detrusor overactivity in rats with BOO, at doses that have no effect on voiding bladder contractions. Thus, selective PDE4 inhibitors should be considered for the treatment of overactive bladder in patients with BOO.

Antimuscarinic drugs for the treatment of female urinary incontinence

Overactive bladder syndrome, urge syndrome or urgency-frequency syndrome is defined as 'urgency with or without urge incontinence, usually with frequency and nocturia'. Although this definition indicates that these symptoms are suggestive of detrusor overactivity (the observation of involuntary detrusor contractions during the filling phase of cystometry), a urodynamic demonstration of detrusor overactivity is not necessary in order to make the diagnosis. Nevertheless, patients with overactive bladder syndrome represent a substantial proportion of patients suffering with urinary symptomatology, and approximately a third of individuals with overactive bladder suffer from incontinence. Furthermore, as compared with those patients with stress urinary incontinence, women with urge incontinence have a poorer overall quality of life, perhaps related to both the volume of urine lost as well as the unpredictable nature of the leakage. When combined with behavioral modification, antimuscarinic pharmacotherapy remains the mainstay of treatment for this condition. A number of these agents are available for the treatment of overactive bladder-related incontinence, each with unique pharmacokinetic and pharmacodynamic properties. In order to optimize therapy for patients suffering from this type of incontinence, it is necessary to understand the mechanism of action of these agents, as well as to be familiar with the differences between them with respect to efficacy, safety and tolerability.

The Rationale of Dual Serotonin/Noradrenaline Reuptake Inhibitors in the Management of Stress Urinary Incontinence

This paper aims at evaluating the role of serotonin (5-HT) and noradrenaline in the nervous control of urinary continence. Both α1-adrenergic and 5-HT2 receptors in the Onuf's nucleus help the guarding reflex; therefore the pharmacologic agents enhancing the effects of 5-HT and noradrenaline represent a promising choice in treating stress urinary incontinence. Duloxetine, a dual 5-HT/noradrenaline reuptake inhibitor, improves the external urethral sphincter contractility while increasing the activation of 5-HT2 and α1-adrenergic receptors thanks to the high concentrations of these monoamines in the Onuf's nucleus; it also plays a significant role in the management of stress urinary incontinence.

Changes in neuropeptide y tissue concentration in the wall of the rat urinary bladder after acute distension

Neuropeptide Y (NPY) is known to be associated with the adrenergic system. The relationship among the late micturition disorders following acute urinary distension, the adrenergic system and NPY was investigated. A total of 90 rats were included in the study of which 30 acted as the control group. Acute urinary distension was created in 60 rats. The NPY concentration within their bladders was assessed by the use of radioimmunoassay (RIA) at 3 h after distension and subsequently on days 2, 7 and 21, then the third and sixth months. The NPY concentrations assessed in the third and sixth months were compared with the control group in the same age group. By means of the RIA method, a substantial decline of NPY concentration was observed at 2 days after distension, while the concentration started to increase after day 7 (P = 0.003). This increase continued until the twenty first day (P = 0.004). However, a significant decline was maintained when compared to the concentration before distension. In the third and sixth months, a significant decline were observed in the NPY concentration in comparison to the control group (P = 0.004 and P = 0.005, respectively). Early and late micturition disorders experienced after acute urinary distension may be the result of adrenergic denervation which may be related to NPY.

Pharmacologic management of urinary incontinence in women

This article summarizes current thought regarding the efficacy of various types of drug therapy for incontinence in women, borrowing liberally from similar previous presentations. Space limitations for this chapter necessitate some simplification and condensation of these subjects. References have generally been chosen because of their informational or review content and not because of originality or initial publication on a particular subject.

Pharmacology of the lower urinary tract

The functions of the lower urinary tract, to store and periodically release urine, are dependent on the activity of smooth and striated muscles in the urinary bladder, urethra, and external urethral sphincter. This activity is in turn controlled by neural circuits in the brain, spinal cord, and peripheral ganglia. Various neurotransmitters, including acetylcholine, norepinephrine, dopamine, serotonin, excitatory and inhibitory amino acids, adenosine triphosphate, nitric oxide, and neuropeptides, have been implicated in the neural regulation of the lower urinary tract. Injuries or diseases of the nervous system, as well as drugs and disorders of the peripheral organs, can produce voiding dysfunctions such as urinary frequency, urgency, and incontinence or inefficient voiding and urinary retention. This chapter will review recent advances in our understanding of the pathophysiology of voiding disorders and the targets for drug therapy.