Experimental evidence for a central nervous system site of action in the effect of alpha-adrenergic blockers on the external urinary sphincter

TAS-303, a Novel Selective Norepinephrine Reuptake Inhibitor that Increases Urethral Pressure in Rats, Indicating Its Potential as a Therapeutic Agent for Stress Urinary Incontinence

Stress urinary incontinence (SUI) is characterized by involuntary leakage associated with exertion, effort, sneezing, coughing, or lifting. Duloxetine, a serotonin norepinephrine reuptake inhibitor, is approved for the treatment of patients with SUI in some European countries, but not in the United States. There is currently no globally approved pharmacological drug for the treatment of patients with SUI. Therefore, a new pharmacological treatment option is required. TAS-303 [4-piperidinyl 2,2-diphenyl-2-(propoxy-1,1,2,2,3,3,3-day₇ )acetate hydrochloride] is a novel small-molecule selective norepinephrine reuptake inhibitor that displays significant norepinephrine transporter (NET) inhibitory activity toward the serotonin or dopamine transporters. In this report, we describe the pharmacological properties of TAS-303 and its effects on urethral function, using preclinical in vitro and in vivo studies. Radioligand-binding studies showed that TAS-303 selectively and potently inhibited [³H]norepinephrine binding to the human NET. Oral administration of TAS-303 (3 mg/kg) significantly increased norepinephrine levels in the plasma, whereas it did not significantly affect epinephrine, dopamine, and serotonin levels. TAS-303 (0.3, 1, and 3 mg/kg) dose-dependently increased basal urethral pressure in normal rats and leak point pressure in vaginal distention rats, exhibiting a maximal effect comparable to duloxetine. In the forced swimming test, TAS-303 (100 mg/kg) showed no significant effects on immobility time in rats, raising the possibility that this agent would have minimal central nervous system side effects at an effective dose for urethral function. These results demonstrate that TAS-303 has therapeutic potential for the treatment of patients with SUI.

Role of poor urethral sphincter relaxation in men with voiding dysfunction refractory to α-blocker therapy: Clinical characteristics and predictive factors

OBJECTIVES

This study evaluates the diagnostic value of poorly relaxed external sphincter (PRES) in men with voiding dysfunction. We analyzed clinical and video-urodynamic characteristics to identify predictive factors of PRES in patients with lower urinary tract symptoms (LUTS) refractory to α-1 adrenoceptor blocker (α-blocker) therapy.

METHODS

This retrospective study included 3379 men with LUTS in whom the initial 1-month α-blocker therapy failed. Clinical parameters and video-urodynamic results were analyzed. Patients with bladder outlet disorders including bladder neck obstruction (BNO), benign prostatic obstruction (BPO), urethral stricture (US), or PRES were categorized according to video-urodynamic findings. Predictive factors for PRES were analyzed.

RESULTS

A total of 3379 men were included in this study. Among the patients with voiding dysfunction, 905 (43.6%) had BPO, 624 (30.0%) had BNO, 487 (23.4%) had PRES, and 62 (3.0%) had US. Patients with PRES were younger and had a higher maximum flow rate, larger bladder capacity, smaller total prostate volume (TPV) and transition zone index, and a lower rate of LUTS of urgency or urge urinary incontinence (UUI) than other groups. On multivariate analysis, only small TPV and lower urgency/UUI rate were predictive factors of PRES. A scale composed of voided volume, TPV, and urgency/UUI predicted PRES with high specificity.

CONCLUSIONS

PRES was the etiology of voiding dysfunction in 23.4% of the men with LUTS refractory to α-blocker therapy. A simple scale composed of voiding volume, TPV, and urgency/UUI was useful in predicting the presence of PRES before video-urodynamic studies.

Neural control of the lower urinary tract

This article summarizes anatomical, neurophysiological, pharmacological, and brain imaging studies in humans and animals that have provided insights into the neural circuitry and neurotransmitter mechanisms controlling the lower urinary tract. The functions of the lower urinary tract to store and periodically eliminate urine are regulated by a complex neural control system in the brain, spinal cord, and peripheral autonomic ganglia that coordinates the activity of smooth and striated muscles of the bladder and urethral outlet. The neural control of micturition is organized as a hierarchical system in which spinal storage mechanisms are in turn regulated by circuitry in the rostral brain stem that initiates reflex voiding. Input from the forebrain triggers voluntary voiding by modulating the brain stem circuitry. Many neural circuits controlling the lower urinary tract exhibit switch-like patterns of activity that turn on and off in an all-or-none manner. The major component of the micturition switching circuit is a spinobulbospinal parasympathetic reflex pathway that has essential connections in the periaqueductal gray and pontine micturition center. A computer model of this circuit that mimics the switching functions of the bladder and urethra at the onset of micturition is described. Micturition occurs involuntarily in infants and young children until the age of 3 to 5 years, after which it is regulated voluntarily. Diseases or injuries of the nervous system in adults can cause the re-emergence of involuntary micturition, leading to urinary incontinence. Neuroplasticity underlying these developmental and pathological changes in voiding function is discussed.

A 12-Week, Open Label, Multi-Center Study to Evaluate the Clinical Efficacy and Safety of Silodosin on Voiding Dysfunction in Patients with Neurogenic Bladder

OBJECTIVES

The purpose of this study is to evaluate clinical effect and safety of α1A -adrenoceptor blocker, silodosin, in patients with voiding dysfunction caused by neurogenic bladder.

METHODS

From April 2011 to January 2012, patients who were diagnosed as potential voiding dysfunction associated with neurogenic bladder, aged ≥ 20 years were enrolled. Silodosin (8 mg/day) was administered once daily in the morning with food. The efficacy was assessed at the baseline and after 12 weeks of the treatment having following parameters of international prostate symptom score and other measures including the maximum flow rate and the postvoid residual urine volume.

RESULTS

A total of 97 patients were screened and 95 were enrolled. Of these 95 patients, 82 patients were completed and included in analysis. After 12-weeks of treatment, mean total international prostate symptom score decreased significantly from 22.23 ± 6.80 to 14.98 ± 9.48 (P = 0.0002). Voiding symptoms and storage symptoms were also improved by decreasing in international prostate symptom score-QoL from 4.62 ± 0.92 to 3.48 ± 1.63 (P < 0.0001). Maximum flow rate increased significantly from 10.72 ± 2.66 to 15.14 ± 6.63 (P < 0.0001). The main adverse event was ejaculation disorder. No serious adverse events related to silodosin were noted.

CONCLUSIONS

This study indicates that silodosin was significantly effective, well tolerated and safe in patients who have voiding dysfunction associated with neurogenic bladder.

Neural control of the female urethral and anal rhabdosphincters and pelvic floor muscles

The urethral rhabdosphincter and pelvic floor muscles are important in maintenance of urinary continence and in preventing descent of pelvic organs [i.e., pelvic organ prolapse (POP)]. Despite its clinical importance and complexity, a comprehensive review of neural control of the rhabdosphincter and pelvic floor muscles is lacking. The present review places historical and recent basic science findings on neural control into the context of functional anatomy of the pelvic muscles and their coordination with visceral function and correlates basic science findings with clinical findings when possible. This review briefly describes the striated muscles of the pelvis and then provides details on the peripheral innervation and, in particular, the contributions of the pudendal and levator ani nerves to the function of the various pelvic muscles. The locations and unique phenotypic characteristics of rhabdosphincter motor neurons located in Onuf's nucleus, and levator ani motor neurons located diffusely in the sacral ventral horn, are provided along with the locations and phenotypes of primary afferent neurons that convey sensory information from these muscles. Spinal and supraspinal pathways mediating excitatory and inhibitory inputs to the motor neurons are described; the relative contributions of the nerves to urethral function and their involvement in POP and incontinence are discussed. Finally, a detailed summary of the neurochemical anatomy of Onuf's nucleus and the pharmacological control of the rhabdosphincter are provided.

Characterization of a spinal, urine storage reflex, inhibitory center and its regulation by 5-HT1A receptors in female cats

Urine storage is facilitated by somatic (pudendal nerve) and sympathetic [hypogastric nerve (HgN)] reflexes to the urethral rhabdosphincter (URS) and urethral smooth muscle, respectively, initiated by primary afferent fibers in the pelvic nerve (PelN). Inhibition of storage reflexes is required for normal voiding. This study characterizes a urine storage reflex inhibitory network that can be activated by PelN afferent fibers concurrently with the reflexes themselves. Electrical stimulation of PelN produced evoked potentials recorded by URS EMG electrodes (10-ms latency) or HgN electrodes (60-ms latency) in chloralose-anesthetized cats. When a second (i.e., paired) pulse of the same stimulus intensity was applied to the PelN 50-500 ms after the first, the reflexes evoked by the second stimulus were inhibited. The inhibition was maximal at paired-pulse intervals of 50-100 ms and remained after acute spinal transection at T10, confirming that the inhibitory center is located in the spinal cord. The 5-HT(1A) receptor agonist 8-hydroxy-2-(di-n-propylamino)tertralin (8-OH-DPAT; 3-300 mug/kg iv) consistently reduced the paired-pulse inhibition from 20% to 60% of control in spinal-intact animals but had no effect in acute spinal animals (i.e., supraspinal site of action). N-{2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl}-N-2-pyridinylcyclohexanecarboxamide maleate (300 mug/kg iv) completely reversed 8-OH-DPAT's effects. The PelN-HgN reflex paired-pulse inhibition was not affected by 8-OH-DPAT. These results indicate the presence of a spinal, urine storage reflex, inhibitory center (SUSRIC) that is activated within 50 ms after activation of the reflexes themselves. SUSRIC is inhibited (disfacilitated) by supraspinal 5-HT(1A) receptors.

Neural control of the lower urinary tract: peripheral and spinal mechanisms

This review deals with individual components regulating the neural control of the urinary bladder. This article will focus on factors and processes involved in the two modes of operation of the bladder: storage and elimination. Topics included in this review include: (1) The urothelium and its roles in sensor and transducer functions including interactions with other cell types within the bladder wall ("sensory web"), (2) The location and properties of bladder afferents including factors involved in regulating afferent sensitization, (3) The neural control of the pelvic floor muscle and pharmacology of urethral and anal sphincters (focusing on monoamine pathways), (4) Efferent pathways to the urinary bladder, and (5) Abnormalities in bladder function including mechanisms underlying comorbid disorders associated with bladder pain syndrome and incontinence.

The effect of duloxetine on urethral sphincter morphology

OBJECTIVES

This was a pilot study to identify whether a course of duloxetine had any effect on urethral sphincter morphology.

METHODS

Fifteen women with urodynamic stress incontinence were treated with duloxetine. The pretreatment condition of the bladder was assessed with the Patient Global Impression of Severity scale. A transperineal ultrasound scan was performed before therapy and again after 4-8 weeks of treatment. The urethral length and the width of the hypoechogenic core (longitudinal smooth muscle, vascular plexus and urothelium) were assessed.

RESULTS

Baseline incontinence symptoms were moderate or severe in 87% of women and an improvement following treatment was reported in 80% of women. Poor views were obtained of the striated muscle. There was a statistically significant increase in the mean width of the hypoechogenic core of the urethra from 5.0 mm to 6.3 mm (P < 0.01). There was no statistically significant change in the length of the urethra (mean 29.4 mm before and 28.0 mm after treatment).

CONCLUSIONS

Duloxetine appears to result in an alteration of the smooth muscle component of the urethral sphincter.

Duloxetine versus placebo for the treatment of women with stress predominant urinary incontinence in Taiwan: a double-blind, randomized, placebo-controlled trial

BACKGROUND

This manuscript compares the efficacy and safety of duloxetine with placebo in Taiwanese women with SUI.

METHODS

Taiwanese women with SUI were were randomly assigned to placebo (n = 61) or duloxetine 80 mg/day (n = 60) in this double-blind, 8-week, placebo-controlled study. Outcome variables included: incontinence episode frequency (IEF), Incontinence Quality of Life questionnaire (I-QOL) scores, and Patient Global Impression of Improvement rating (PGI-I).

RESULTS

Decrease in IEF was significantly greater in duloxetine-treated than placebo-treated women (69.98% vs 42.56%, P < .001). No treatment differences in I-QOL scores were significant. There were significant differences in PGI-I rating. Treatment-emergent adverse events (TEAEs) were experienced by more duloxetine-treated than placebo-treated women (80.0% vs 44.3%; P < .001). Discontinuations due to adverse events were significantly greater for duloxetine-treated than placebo-treated women (26.7% vs 6.6%; P = .003).

CONCLUSION

Data provide evidence for the safety and efficacy of duloxetine for the treatment for Taiwanese women with SUI.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00475358.

Role of noradrenergic pathways in sneeze-induced urethral continence reflex in rats

To clarify the role of noradrenergic pathways in preventing stress urinary incontinence (SUI) during sneezing, we investigated the effect of the norepinephrine reuptake inhibitor nisoxetine and α-adrenoceptor antagonists phentolamine (nonspecific blocker) and prazosin (α1-receptor-selective blocker) on the neurally evoked urethral continence reflex induced by sneezing in rats. The amplitude of urethral pressure responses during sneezing (A-URS), urethral baseline pressure (UBP) at the midurethra, and sneeze-induced leak point pressure (S-LPP) were measured in normal female adult rats and rats with SUI induced by vaginal distention (VD). In normal rats, intrathecal (it) phentolamine (0.02 nmol) and prazosin (0.02 nmol) decreased A-URS by 11.9 and 15.7%, respectively, without affecting UBP. In both normal and VD rats, intravenous (iv) application of nisoxetine (1 mg/kg) increased A-URS by 17.2 and 18.3% and UBP by 23.7 and 32.7%, respectively. Phentolamine or prazosin (both it) eliminated nisoxetine-induced increases in A-URS, but not the increases in UBP, which were, however, suppressed by iv phentolamine (5 mg/kg) or prazosin (1 mg/kg). Sneezing induced fluid leakage from the urethral orifice in VD rats, but not in normal rats. In VD rats, S-LPP was increased by 30.2% by iv nisoxetine. Application of phentolamine and prazosin (both it) decreased S-LPP by 15.7 and 20.6%, respectively, and nisoxetine induced increases in S-LPP to 13.2 and 12.3%, respectively. These results indicate that activation of the noradrenergic system by a norepinephrine reuptake inhibitor can prevent SUI via α1-adrenoceptors by enhancing the sneeze-induced active urethral closure mechanism at the spinal level and augmenting UBP at the periphery.

Placebo-controlled study of the effects of atomoxetine on bladder control in children with nocturnal enuresis

INTRODUCTION

Nocturnal enuresis is a condition in which children at least 5 years of age are incontinent of urine at night. Atomoxetine, a potent inhibitor of the presynaptic norepinephrine transporter, is used to treat attention-deficit/hyperactivity disorder (ADHD). This study tested the hypothesis that atomoxetine will provide significant therapeutic benefit for nocturnal enuresis in patients with the diagnosis of nocturnal enuresis.

METHODS

Atomoxetine's efficacy for improving nocturnal enuresis was studied in 87 pediatric subjects using an outpatient, multicenter, randomized, double-blind, parallel, placebo-controlled study. Efficacy was determined by measuring the mean number of dry nights per week using an intent-to-treat analysis of the primary outcome measure, the Dry Night Log-Parent Report (DNL-PR), a daily parent diary.

RESULTS

Baseline and end point DNL-PR data were available from 42 atomoxetine-treated and 41 placebo-treated subjects. Atomoxetine increased the average number of dry nights per week by 1.47 compared with .60 for placebo (F = 7.06; df = (1, 75); p = 0.01). Fifteen atomoxetine-treated subjects (35.7%) had an increase of at least 2 dry nights per week compared with only 6 (14.6%) placebo-treated subjects (Fisher's exact test; p = 0.042). There were no significant differences in adverse events between the groups.

CONCLUSIONS

Compared with placebo, atomoxetine treatment was associated with a significant increase in dry nights in children with nocturnal enuresis.

Facilitatory Neuromodulative Effect of Duloxetine on Pudendal Motor Neurons Controlling the Urethral Pressure: A Functional Urodynamic Study in Healthy Women

OBJECTIVE

The aim of this functional urodynamic experiment in healthy women was to study the effect of duloxetine, which is a combined serotonin and norepinephrine (5-HT/NE) reuptake inhibitor, on urethral resting pressure, excitability of pudendal motor neurons, and urethral sphincter contractility.

METHODS

In 11 healthy female subjects three baseline urethral pressure profiles (UPPs) were obtained to study resting pressure. Afterward the individual motor threshold (MT) for external urethral sphincter (EUS) contraction in response to transcranial magnetic stimulation (TMS) was determined to study the excitability of pudendal motor neurons. Another three UPPs were recorded while sacral root magnetic stimulation (SMS) was performed to evoke reproducible urethral contractions to study urethral sphincter contractility. Then the women received 40 mg duloxetine and the protocol was repeated 4 h after drug administration. The resting pressure values, MT values following TMS, and the EUS pressure amplitudes in response to SMS obtained at baseline were statistically compared to the corresponding values at follow-up after duloxetine.

RESULTS

Oral administration of duloxetine significantly lowered MT for EUS contraction in response to TMS (p=0.013). In addition, duloxetine significantly increased EUS pressure amplitudes in response to SMS (p=0.0007, 5 of 11 subjects evaluated) but did not change urethral resting pressures.

CONCLUSIONS

This is the first functional, urodynamic controlled study to show that the combined 5-HT/NE reuptake inhibitor duloxetine has a significant effect on the excitability of pudendal motor neurons and on urethral sphincter contractility in healthy women in vivo but no significant effect on urethral resting tone. Our data confirm a facilitatory neuromodulative effect of duloxetine on sphincter motor neurons in humans.

Preview of new drugs for overactive bladder and incontinence: darifenacin, solifenacin, trospium, and duloxetine

This year, the US Food and Drug Administration will approve four new drugs indicated for the treatment of lower urinary tract dysfunction. Darifenacin, solifenacin, and trospium are antimuscarinic agents aimed at relieving the symptoms of overactive bladder and urge incontinence in men and women. Duloxetine will be the first drug approved for the treatment of female stress urinary incontinence. This article presents current data on the efficacy and tolerability of these new agents and invites the reader to decide whether they offer any potential advantages over existing therapies.

Impact of duloxetine on quality of life for women with symptoms of urinary incontinence

The objective of this study was to evaluate the effectiveness of duloxetine in improving quality of life among women with stress and mixed urinary incontinence. The study included 451 women with self-reported stress incontinence episodes (>or=1/week) who were randomized to duloxetine (40 mg BID) or placebo in a double-blind, usual care design. Patients and physicians were allowed to titrate, augment, and/or discontinue treatment. Concomitant treatments were permitted. The primary outcome was the Incontinence Quality of Life Questionnaire (I-QOL) score, with assessments at 3, 6, and 9 months. Other measures included the Patient Global Impression of Improvement (PGI-I) and adverse events. The adjusted mean change in I-QOL total score was greater in the duloxetine group than in the placebo group and at a level comparable to that found in previous clinical trials, but the difference between placebo and duloxetine was not statistically significant in the intent-to-treat, last observation carried forward (LOCF) analysis. The difference approached statistical significance in favor of duloxetine at 3 months (p=0.07). PGI-I ratings did not demonstrate significant superiority for duloxetine in LOCF analysis; however, study completers taking duloxetine were significantly more likely to rate themselves as "better" (70.2%) than completers taking placebo (50.8%, p<0.05). Women utilized a variety of treatment methods including pelvic floor muscle training, estrogen, anticholinergic medication, weight reduction, and smoking cessation. In this study, while mean I-QOL change scores were numerically higher for the duloxetine group than mean change scores for the placebo group, this difference was not statistically significant. Among women who completed the study on study drug, a significantly greater proportion of duloxetine women versus placebo women rated their condition to be better.

Targeting serotonin and norepinephrine receptors in stress urinary incontinence

Stress urinary incontinence (SUI) in women is prevalent, and there are no globally developed or widely approved drugs for the disease. One strategy for improving urinary continence is to augment the function of the urethral rhabdosphincter through neuropharmacology. The present review describes the innervation of the urethra, and the role of the central nervous system in controlling nerve activity. Targeting serotonin and norepinephrine (or noradrenaline) receptors in Onuf's nucleus is shown to augment the function of the urethral rhabdosphincter by increasing pudendal nerve efferent activity. It is proposed that the ability of serotonin and norepinephrine to enhance the effects of glutamate (the primary excitatory neurotransmitter for pudendal sphincter motor neurons) while having no direct effects of their own, allow facilitation of rhabdosphincter activity during urine storage while allowing complete relaxation during micturition. Duloxetine, a potent and balanced dual serotonin (5-HT)-norepinephrine reuptake inhibitor (SNRI), potentiates these physiological effects of endogenous serotonin and norepinephrine (by inhibiting the reuptake of these neurotransmitters in the pre-synaptic element) and thereby enhances the central nervous system's natural continence control mechanisms.

Pharmacotherapy for stress urinary incontinence : present and future options

Stress urinary incontinence (SUI) is the accidental leakage of urine associated with physical activities such as running, jumping or lifting, or with sneezing and coughing. Worldwide, SUI is a highly prevalent condition, both in young and elderly women, and is a condition fraught with social isolation, loss of self-esteem and significant financial burden. Most women with SUI assume that it is an inevitable part of aging and "suffer in silence", relying on absorbent pads or lifestyle changes to cope with their condition.Unfortunately, for those who do seek medical treatment, the absence of effective and well tolerated pharmacological treatments for SUI limits the clinician's choices to behavioural modification, biofeedback and surgery. Many of the nonsurgical approaches have low success rates, particularly in the elderly and more severely afflicted. Although most continence surgeries have been reported to produce very high cure rates, many women are willing to live with their condition rather than undergo such invasive options. In an attempt to help these patients, some physicians prescribe off-label agents, including tricyclic antidepressants such as imipramine, alpha- and beta-adrenoceptor agonists, and estrogen replacement therapy. The use of these therapies has been limited by unpredictable results and adverse reactions. In addition, acetylcholine receptor antagonists are often prescribed for SUI, despite the fact that these medications have never been shown to be effective in this condition. This lack of a reliable pharmaceutical agent led to the development of duloxetine, a balanced dual reuptake inhibitor of serotonin and norepinephrine that is also being studied for the treatment of major depressive disorder. Based on in vivo data in animals, duloxetine is believed to increase the strength of urethral sphincter contractions and, thereby, prevent accidental urine leakage by increasing urethral closure forces. In clinical trials in women with SUI, duloxetine has demonstrated efficacy in reducing incontinence episodes and increasing the quality of life with no serious adverse effects. Nausea was the most common adverse event; however, in most patients it was reported early in treatment, mild-to-moderate in severity and transient. A medication such as duloxetine, if approved, would go a long way towards expanding the available treatment options for patients with SUI.

Central nervous system control of the lower urinary tract: new pharmacological approaches to stress urinary incontinence in women

PURPOSE

Despite the prevalence of stress urinary incontinence in women there are no approved drugs for the disease.

MATERIALS AND METHODS

Designing medical therapies requires a comprehensive understanding of how the internal and external sphincters are neurologically controlled. In this review recent advances in mapping storage and micturition reflexes, and the association of serotonergic and noradrenergic systems with these reflexes are discussed.

RESULTS

Urine storage and micturition are controlled by a series of hard wired reflexes that are under the modulatory influence of serotonin and norepinephrine. Augmentation of the serotonergic and noradrenergic systems with duloxetine increases bladder capacity and urethral rhabdosphincter activity. The increase in sphincter activity is mediated by alpha1 adrenergic receptors and 5-hydroxytryptamine receptors.

CONCLUSIONS

Increasing rhabdosphincter activity with duloxetine may offer a therapeutic benefit in women with stress urinary incontinence.

Duloxetine vs placebo in the treatment of stress urinary incontinence: a four-continent randomized clinical trial

OBJECTIVES

To further assess, in a phase 3 study, treatment with duloxetine for women with stress urinary incontinence (SUI) in other geographical regions, including Argentina, Australia, Brazil, Finland, Poland, South Africa and Spain, as previous trials in North America and Europe provided evidence for the safety and efficacy of duloxetine as a pharmacological treatment for SUI in women.

PATIENTS AND METHODS

The study included 458 women aged 27-79 years enrolled in a double-blind, placebo-controlled trial. The patients with predominantly SUI were identified using a validated clinical algorithm. They were randomly assigned to receive placebo (231) or duloxetine 40 mg twice daily (227) for 12 weeks. The primary outcome variables included the incontinence episode frequency (IEF) and the Incontinence Quality of Life (I-QOL) questionnaire. Van Elteren's test was used to analyse the percentage changes in IEF where the stratification variable was weekly baseline IEF (IEF < 14 and > or = 14). Analysis of covariance was used to analyse I-QOL scores.

RESULTS

The mean baseline IEF was 18.4/week; 55% of patients had a baseline IEF of > or = 14. There was a significantly greater median decrease in IEF with duloxetine with placebo (54% vs 40%, P = 0.05), with comparable significant improvements in quality of life (I-QOL score increases of 10.3 vs 6.4, P = 0.007). The improvements with duloxetine were associated with significantly greater increases in voiding intervals than with placebo (20.4 vs 8.5 min, P < 0.001). The placebo response was 10.7% and 12.5% higher than those reported in two European and North American phase 3 trials. This may have been related to more patients being naïve for incontinence management in the current trial. Discontinuation rates for adverse events were 1.7% for placebo and 17.2% for duloxetine (P < 0.001), with nausea being the most common reason for discontinuation (3.1%); it was the most common adverse event with duloxetine, but was mild or moderate in most (81%), did not worsen in any patient and resolved within 7 days in 60% and within 1 month in 86% of continuing patients; 88% of women who experienced nausea while taking duloxetine completed the trial.

CONCLUSIONS

These results show improvements in incontinence and quality of life with duloxetine 40 mg twice daily for 12 weeks that are in keeping with those reported in two other recently completed phase 3 trials in Europe and North America.

Duloxetine versus placebo in the treatment of European and Canadian women with stress urinary incontinence

OBJECTIVE

To assess the efficacy and safety of duloxetine in women with stress urinary incontinence.

DESIGN

Randomised double-blind, placebo-controlled clinical trial.

SETTING

Fort-six centres in seven European countries and Canada.

POPULATION

Four hundred and ninety-four women aged 24-83 years identified as having predominant symptoms of stress urinary incontinence using a clinical algorithm that was 100% predictive of urodynamic stress urinary incontinence in a subgroup of 34 women.

METHODS

The case definition included a predominant symptom of stress urinary incontinence with a weekly incontinence episode frequency > or =7, the absence of predominant symptoms of urge incontinence, normal diurnal and nocturnal frequencies, a bladder capacity > or =400 mL and both a positive cough stress test and positive stress pad test. Subjects completed two urinary diaries prior to randomisation and three diaries during the active treatment phase of the study, each completed during the week prior to monthly visits. Subjects also completed quality of life questionnaires at each visit. Safety was assessed by the evaluation of treatment-emergent adverse events, discontinuation of treatment because of adverse events, serious adverse events, vital sign measurements, electrocardiograms (ECG) and clinical laboratory tests.

INTERVENTION

After a two-week placebo lead-in, women received placebo or duloxetine 40 mg BD for 12 weeks.

MAIN OUTCOME MEASURES

The percentage decrease in incontinence episode frequency and the change in the Incontinence Quality of Life (I-QOL) questionnaire total score were prespecified as co-primary outcome variables in the protocol.

RESULTS

Incontinence episode frequency decreased significantly with duloxetine compared with placebo (median decrease of 50%vs 29%; P= 0.002) with comparable improvements in the more severely incontinent subgroup (those experiencing at least 14 incontinence episodes per week at baseline; 56%vs 27% decreases; P < 0.001). The primary analysis of I-QOL scores did not reveal a significant difference between treatment groups, due primarily to the carrying forward of low scores from patients who discontinued treatment very early due to duloxetine-associated adverse events. The increase in I-QOL scores was significantly greater for duloxetine than for placebo at each of the three postrandomisation visits after 4, 8, and 12 weeks of treatment. Discontinuation rates for adverse events were higher for duloxetine (22%vs 5%; P < 0.001) with nausea being the most common reason for discontinuation (5.3%). Nausea tended to be mild to moderate, not progressive, and transient.

CONCLUSIONS

The findings support duloxetine as a potential treatment for women with stress urinary incontinence.

Duloxetine versus placebo for the treatment of North American women with stress urinary incontinence

PURPOSE

Duloxetine, a selective serotonin and norepinephrine reuptake inhibitor, increases rhabdosphincter contractility via the stimulation of pudendal motor neuron alpha-1 adrenergic and 5-hydroxytryptamine-2 receptors. In this first phase 3 study we assessed the efficacy and safety of duloxetine in women with stress urinary incontinence (SUI).

MATERIALS AND METHODS

A total of 683 North American women 22 to 84 years old were enrolled in this double-blind, placebo controlled study. The case definition included a predominant symptom of SUI with a weekly incontinence episode frequency (IEF) of 7 or greater, the absence of predominant symptoms of urge incontinence, normal diurnal and nocturnal frequency, a bladder capacity of 400 ml or greater, and a positive cough stress test and stress pad test. After a 2-week placebo lead-in period subjects were randomly assigned to receive placebo (339) or 80 mg duloxetine daily (344) as 40 mg twice daily for 12 weeks. Primary outcome variables included IEF and an incontinence quality of life questionnaire. Van Elteren's test was used to analyze percent changes in IEF with a stratification variable of weekly baseline IEF (less than 14 and 14 or greater). ANCOVA was used to analyze incontinence quality of life scores.

RESULTS

Mean baseline IEF was 18 weekly and 436 subjects (64%) had a baseline IEF of 14 or greater. There was a significant decrease in IEF with duloxetine compared with placebo (50% vs 27%, p <0.001) with comparably significant improvements in quality of life (11.0 vs 6.8, p <0.001). Of subjects on duloxetine 51% had a 50% to 100% decrease in IEF compared with 34% of those on placebo (p <0.001). These improvements with duloxetine were associated with a significant increases in the voiding interval compared with placebo (20 vs 2 minutes, p <0.001) and they were observed across the spectrum of incontinence severity. The discontinuation rate for adverse events was 4% for placebo and 24% for duloxetine (p <0.001) with nausea the most common reason for discontinuation (6.4%). Nausea, which was also the most common side effect, tended to be mild to moderate and transient, usually resolving after 1 week to 1 month. Of the 78 women who experienced treatment emergent nausea while taking duloxetine 58 (74%) completed the trial.

CONCLUSIONS

These phase 3 data are consistent with phase 2 data and they provide further evidence for the safety and efficacy of duloxetine as a pharmacological agent for the treatment of women with SUI.

Urodynamic effects of alpha1-blocker tamsulosin on voiding dysfunction in patients with neurogenic bladder

BACKGROUND

The therapeutic role of alpha-blockers in the treatment of voiding disorders due to benign prostatic hyperplasia has been extensively examined. To investigate a possible effect of alpha1-blocker on urodynamic voiding parameters in patients with neurogenic bladder, we conducted a clinical trial using tamsulosin.

METHODS

Twenty-four patients (14 men and 10 women) ranging from 24 to 82 years of age (mean age 61 years) with neurogenic bladder were analyzed. Urodynamic studies were performed before and after treatment with 0.4 mg tamsulosin daily for 4 weeks.

RESULTS

On uroflowmetry, the average flow rate (from 4.6 +/- 3.3 to 6.7 +/- 3.0 mL/s, P = 0.04), maximum flow rate (from 9.4 +/- 6.8 to 14.1 +/- 7.0 mL/s, P = 0.016) and residual urine rate (from 46 +/- 29 to 32 +/- 21%, P = 0.02) improved significantly. In patients with detrusor contraction during voiding, detrusor opening pressure and detrusor pressure at maximum flow decreased significantly from 69.0 +/- 36.2 to 49.2 +/- 26.4 cmH2O (P = 0.046) and from 66.7 +/- 34.6 to 53.6 +/- 26.5 cmH2O (P = 0.007), respectively. On the other hand, in patients with detrusor areflexia, vesical opening pressure (from 78.2 +/- 23.4 to 61.6 +/- 25.2 cmH2O), or vesical pressure at maximum flow (from 68.6 +/- 23.2 to 62.9 +/- 25.2 cmH2O) did not change significantly after treatment.

CONCLUSION

Tamsulosin reduces functional urethral resistance during voiding and improves flow rate in patients with neurogenic bladder. It has more beneficial urodynamic effects in patients with detrusor contraction during voiding than in patients with detrusor areflexia.

alpha(2a) and alpha(2c) adrenoceptors on spinal neurons controlling penile erection

The thoracolumbar and lumbosacral spinal cord contain respectively sympathetic and parasympathetic preganglionic neurons that supply the organs of the pelvis including the penis. These neurons are influenced by supraspinal information and receive aminergic projections from the brainstem. The presence of the alpha(1)- and alpha(2)-adrenoceptor subtypes has been demonstrated in the rat spinal cord. In this species, we looked for the presence of alpha(2a)- and alpha(2c)-adrenoceptor subtypes in the sympathetic and parasympathetic preganglionic neurons controlling erection. In adult male rats, transsynaptic axonal transport of pseudorabies virus injected into the penis was combined with immunohistochemistry against alpha(2a)- and alpha(2c)-adrenoceptor subtypes. At 4 days survival time, neurons infected with the pseudorabies virus were solely found in the intermediolateral cell column and dorsal gray commissure of segment T12-L2 and in the intermediolateral cell column of segment L6-S1. Neurons and fibers immunoreactive for alpha(2a)- and alpha(2c)-adrenoceptor subtypes were mainly present in the intermediolateral cell column, the dorsal gray commissure and the ventral horn of the T12-L2 and L5-S1 spinal cord, the dorsal horn displayed only immunoreactive fibers. Pseudorabies virus-infected neurons in the autonomic nuclei were both immunoreactive for alpha(2a)- and alpha(2c)-adrenoceptor subtypes and closely apposed by alpha(2a)- and alpha(2c)-immunoreactive fibers. The results suggest an intraspinal modulation of the noradrenergic and adrenergic control of the autonomic outflow to the penis by pre- and postsynaptic alpha(2) adrenoceptors.

Alfuzosin in the treatment of high leak-point pressure in children with neurogenic bladder

OBJECTIVE

To decrease the detrusor leak-point pressure (LPP) of > 40 cmH2O in children with a neurogenic bladder, using the alpha1-adrenergic blocking agent alfuzosin.

PATIENTS AND METHODS

Videocystometry was used to measure the detrusor LPP and several other variables before and 3 weeks after the oral administration of alfuzosin (2.5-7.5 mg/day) in 17 children (mean age 6.3 years) with an upper motor neurone lesion.

RESULTS

The mean (sd) detrusor LPP decreased from 68 (37) to 46 (31) cmH2O (P < 0.01), reflex volume (defined as the volume at the first uninhibited bladder contraction of > 15 cmH2O) increased from 78 (69) to 112 (118) mL (+ 44%), bladder compliance increased from 9.3 (6.1) to 19.6 (14.6) mL/cmH2O (+ 111%), maximal vesical pressure decreased from 84 (40) to 70 (47) cmH2O (- 17%), and the mean number of uninhibited bladder contractions decreased from 6.3 to 3.5 (- 44%). The therapy was well tolerated; side-effects were rare and not severe. Intermittent catheterization could be avoided in six children.

CONCLUSION

Alfuzosin decreases the detrusor LPP in children with a neurogenic bladder caused by an upper motor neurone lesion, significantly and therapeutically, and should be considered as an alternative or addition to intermittent catheterization and anticholinergic drugs in selected patients.

Duloxetine versus placebo in the treatment of stress urinary incontinence

OBJECTIVE

The purpose of this study was to assess the efficacy and safety of duloxetine, a selective inhibitor of serotonin and norepinephrine reuptake, in the treatment of stress urinary incontinence.

STUDY DESIGN

A double-blind, randomized, placebo-controlled study was conducted in 553 women aged 18 to 65 years with a predominant symptom of stress urinary incontinence. Subjects were randomized to placebo (n = 138 women) or duloxetine at one of three doses (20 mg/d, n = 138 women; 40 mg/d, n = 137 women; or 80 mg/d, n = 140 women). Outcome variables that were assessed after 12 weeks of treatment included incontinence episode frequency recorded in a real-time diary and answers provided to the Patient Global Impression of Improvement scale and the Incontinence Quality of Life questionnaire.

RESULTS

Duloxetine was associated with significant and dose-dependent decreases in incontinence episode frequency that paralleled improvements that were observed in the Patient Global Impression of Improvement scale and the Incontinence Quality of Life questionnaire. The median incontinence episode frequency decrease with the use of the pooled diary analysis with placebo was 41% compared with 54% for duloxetine 20 mg per day (P =.06), 59% for duloxetine 40 mg per day (P =.002), and 64% for duloxetine 80 mg per day (P <.001). One half of the subjects at the 80 mg per day dose had a > or = 64% reduction in incontinence episode frequency (P <.001 vs placebo); 67% had > or = 50% reduction (P =.001 vs placebo). These improvements were observed despite significant concurrent dose-dependent increases in the average voiding interval in the duloxetine groups compared with the placebo group. Similar statistically significant improvements were demonstrated in a subgroup of 163 subjects who had more severe stress urinary incontinence (> or = 14 incontinence episode frequency per week; 49%-64% reduction in incontinence episode frequency in the duloxetine groups compared with 30% in the placebo group). Discontinuation rates for adverse events were 5% for placebo and 9%, 12%, and 15% for duloxetine 20, 40, and 80 mg per day, respectively (P =.04). Nausea was the most common symptom that led to discontinuation. None of the adverse events that were reported were considered to be clinically severe.

CONCLUSION

This trial provides evidence for the efficacy and safety of duloxetine as a pharmacologic agent for the treatment of stress urinary incontinence.

Catecholaminergic projections onto spinal neurons destined to the pelvis including the penis in rat

In rats, the spinal cord contains proerectile autonomic motoneurons destined to the penile tissue and its vasculature, and somatic motoneurons destined to the perineal striated muscles. It receives dense catecholaminergic projections issued from the medulla and pons. In adult male rats, we evidenced the catecholaminergic innervation of spinal neurons controlling lower urogenital tissues and regulating penile erection. We combined retrograde tracing techniques and immunohistochemistry against synthetic enzymes of noradrenaline and adrenaline. Both sympathetic and parasympathetic preganglionic neurons, labeled from the major pelvic ganglion or from the corpus cavernosum, were apposed by catecholaminergic immunoreactive fibers. Motoneurons, retrogradely labeled from the striated muscles, were also apposed by catecholaminergic immunoreactive fibers. Synapses between these motoneurons and fibers were suggested by confocal microscopy and confirmed by electron microscopy in some cases. The results reinforce the hypothesis of a catecholaminergic control of autonomic and somatic motoneurons regulating penile erection at the spinal level.

Central effects of clozapine in regulating micturition in anesthetized rats

BACKGROUND

We previously showed that systemic administration of the atypical neuroleptic clozapine in the rat altered a number of urodynamic variables and inhibited the external urethral sphincter. Since clozapine acts at several receptor types both at the periphery and the central nervous system, the site of action remained uncertain. Therefore, the purpose of this study was to determine the effects of central administration of clozapine on the bladder and the external urethral sphincter during cystometry and to examine differences in spinal versus supraspinal administration. We extended our observations by delivering clozapine centrally in anesthetized rats instrumented with either an intrathecal (L6-S1 spinal segment) or an intracerebroventricular (lateral ventricle) catheter.

RESULTS

Clozapine decreased micturition volume and increased residual volume possibly by acting at a supraspinal site. Expulsion time and amplitude of the high frequency oscillations were reduced by clozapine possibly by acting at a spinal site. Bladder capacity was increased after central clozapine but probably due to a peripheral effect. Clozapine acting at spinal and supraspinal sites increased pressure threshold. Contraction time and peak pressure were not affected by clozapine. The EMG from the external urethral sphincter was also reduced following clozapine centrally and suggests a spinal and a supraspinal site of action.

CONCLUSIONS

The results from the present study suggest that spinal and supraspinal central sites mediate clozapine's action in inhibiting expulsion parameters and the external urethral sphincter of the rat. Therefore, the reduction in the voiding efficiency observed after clozapine appears to be mediated by spinal and supraspinal sites.

Effects of the atypical neuroleptic clozapine on micturition parameters in anesthetized rats

Clozapine, an atypical antipsychotic, has resulted in a number of reports of urinary disturbances in the clinical literature. We examined the effects of clozapine on urodynamic parameters in the anesthetized rat and compared the effects to those of the typical antipsychotic haloperidol and the selective D2 and D4 antagonists, raclopride and L-745,870, respectively. Clozapine abolished high-frequency oscillations (HFO) during the expulsion phase, and profoundly altered a number of other parameters (e.g., intercontraction interval and resting pressure). Clozapine did not affect the peak contraction pressure during cystometrograms but displayed peripheral inhibition of bladder contractions elicited by electrical stimulation of the pelvic nerve (possibly mediated via clozapine's anti-muscarinic effects). Haloperidol had less potent effects than clozapine since it reduced the amplitude of HFO to 25% of control and also affected several other parameters but without peripheral bladder inhibition. Raclopride only resulted in a modest decrease (approximately 70% of control) in the HFO and no alteration in other parameters. L-745,870 was effective only at highest dose tested suggesting that it might not be acting selectively at D4 receptors. Therefore, we propose that clozapine primarily interferes with the function of the external urethral sphincter. These effects can only be partly explained through antagonism of D2 receptors. Since both clozapine and haloperidol have interactions with other transmitter systems beside dopamine, we suggest that central antagonism of D2 receptors, coupled to central antagonism of another receptor system and peripheral muscarinic receptor blockade, may account for clozapine's potent effects on micturition.

Effects of two atypical neuroleptics, olanzapine and risperidone, on the function of the urinary bladder and the external urethral sphincter in anesthetized rats

BACKGROUND

A previous report showed that the atypical neuroleptic clozapine resulted in marked changes in urodynamic parameters and greatly inhibited the activity of the external urethral sphincter in anesthetized rats. Such findings may help explain the high incidence of urinary disturbances reported during clozapine therapy. In an effort to extend our observations to other atypical neuroleptic agents, the present study investigated the effects of two newer atypical antipsychotics, olanzapine and risperidone, on the bladder and external urethral sphincter during cystometry in anesthetized rats.

RESULTS

At a dose of 0.1 mg/kg (i.v.), olanzapine decreased the micturition volume and increased the residual volume. In addition, olanzapine decreased the expulsion time and the amplitude of the high frequency oscillations observed during the expulsion phase. Larger doses (1 mg/kg) had a greater effect. Olanzapine also reduced the activity recorded from the external urethral sphincter, and the bursting observed during the expulsion phase was abolished by 1.0 mg/kg. Risperidone had similar effects although the maximal effects were smaller than those observed with olanzapine. The amplitude of bladder contractions elicited by electrical stimulation of the pelvic nerve was reduced by olanzapine but not risperidone suggesting a possible anti-muscarinic peripheral effect of olanzapine.

CONCLUSIONS

Olanzapine and risperidone significantly altered several voiding parameters and decreased the activity of the external urethral sphincter in the anesthetized rat. We propose that these effects are due to the central action of these drugs and not to peripheral effects. These findings may explain some of the clinical reports of urinary incontinence with risperidone and may predict similar occurrences with olanzapine therapy.

Contrasting effects of phentolamine and nitroprusside on neural and cardiovascular variability

The relative contributions of a central neural oscillator and of the delay in alpha-adrenergic transmission within the baroreflex loop in the predominance of low-frequency (LF) cardiovascular variability during sympathetic activation in humans are unclear. We measured R-R interval (RR), muscle sympathetic nerve activity (MSNA), blood pressure (BP), and their variability in 10 normal subjects during sympathetic activation achieved by BP lowering with sodium nitroprusside (SNP) and alpha-adrenergic blockade using phentolamine. SNP and phentolamine induced comparable reductions in BP (P > 0.25). Despite tachycardia and sympathetic activation with both SNP and phentolamine, LF variability in RR, MSNA, and BP increased during SNP and decreased during phentolamine (SNP: RR +20 +/- 6%, MSNA +3 +/- 5%, systolic BP +9 +/- 6%, diastolic BP +7 +/- 5%; phentolamine: RR -2 +/- 7%, MSNA -34 +/- 6%, systolic BP -16 +/- 8%, diastolic BP -13 +/- 4%, P < 0.05 except systolic BP, where P = 0.09). Thus LF variability is reduced when sympathetic activation is induced by alpha-adrenergic blockade. This suggests that alpha-adrenergic transmission within the baroreflex loop may contribute importantly to the predominance of LF cardiovascular variability associated with sympathetic excitation in humans.

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.

The role of alpha(1)-adrenoceptors and 5-HT(1A) receptors in the control of the micturition reflex in male anaesthetized rats

1. The effects of the alpha(1)-adrenoceptor antagonists doxazosin (0.1 -- 2 mg kg(-1)), RS-100329 (alpha(1A); 0.01 -- 1 mg kg(-1)), RS-513815 (Ro 151-3815, alpha(1B); 0.3 -- 3 mg kg(-1)) and BMY 7378 (alpha(1D); 0.1 -- 1 mg kg(-1)), the 5-HT(1A) receptor agonist, 8-OH-DPAT (0.03 -- 0.3 mg kg(-1)) and antagonist WAY-100635 (0.03 -- 0.3 mg kg(-1)) were investigated (i.v.) on the 'micturition reflex' in the urethane anaesthetized male rat. 2. Reflex-evoked urethra contractions were most sensitive to the inhibitory action of RS-100329, followed by doxazosin, BMY 7378 and WAY-100635 and then RS-513815. The maximum inhibition was 66, 63, 54, 46 and 22% at doses of 0.3, 0.5, 0.3, 0.3 and 3 mg kg(-1) respectively. 3. BMY 7378 and 8-OH-DPAT decreased, while WAY-100635 increased, the pressure threshold to induce bladder contraction. WAY-100635 (0.01 mg kg(-1)) blocked the effects of BMY 7378 (1 mg kg(-1)) on bladder pressure and volume threshold. 4. Doxazosin, RS-100329 and BMY 7378 had a similar potency in inducing a fall in arterial blood pressure while WAY-100635 only caused a fall at the highest dose. 5. Therefore, reflex-evoked urethral contraction involves the activation of alpha(1A/1D)-adrenoceptors, as BMY 7378 and RS-100329 are similarly potent in attenuating this effect. The ability of WAY-100635 to attenuate this contraction may suggest that 5-HT(1A) receptors are also involved. However, as this inhibition occurred at the highest dose of WAY-100635, which also caused a fall in arterial blood pressure; this effect is considered to be due to blockade of alpha(1)-adrenoceptors not 5-HT(1A) receptors. Nevertheless the initiation of the 'micturition reflex' involves the activation of 5-HT(1A) receptors.

Clozapine inhibits micturition parameters and the external urethral sphincter during cystometry in anesthetized rats

Clozapine therapy has been associated with a high degree of urinary disturbances. The purpose of this study is to examine the effect of clozapine on urodynamic parameters and on the activity of the external urethral sphincter in anesthetized rats. Single cystometrograms (CMG) were performed on urethane-anesthetized female Sprague-Dawley rats, while also recording the EMG from the external urethral sphincter. Clozapine (0, 0.1, 1, 10 mg/kg) was administered intravenously. In addition, the peripheral end of the pudendal nerve was stimulated in order to determine if clozapine was exerting peripheral effects directly on the external urethral sphincter. Clozapine increased the bladder capacity while reducing the micturition volume thus resulting in a marked increase in the residual volume. The pressure threshold was increased but the peak pressure during contraction remained unchanged. The expulsion time and contraction time were decreased and the amplitude of the high frequency oscillations (HFO) seen during the expulsion phase were markedly reduced and even abolished. The EMG from the external urethral sphincter also showed marked decreases after clozapine, and the bursting pattern seen during HFO was abolished. Clozapine had no effect on the activity elicited from electrical stimulation of the pudendal nerve. Clozapine inhibits several urodynamic parameters and inhibits the activity of the external urethral sphincter in anesthetized rats. These effects may help explain the urinary disturbances reported in the clinical literature.

Effects of adrenergic alpha2-receptor agonists on urinary bladder contraction in conscious rats

We investigated the effects of the adrenergic alpha2-receptor agonists clonidine, oxymetazoline and tizanidine on bladder contractions induced by infusing fluid into the bladders of conscious male rats. I.v. clonidine and oxymetazoline (both 0.01 to 0.1 mg/kg) caused bladder hyperactivity, expressed by shortening of the intercontraction interval. Tizanidine (0.1 mg/kg, i.v.) caused slight shortening of the intercontraction interval. The rank order of potency was clonidine = oxymetazoline >> tizanidine. Intrathecal (i.t.) injection of 10 microg clonidine and oxymetazoline, and intracerebroventricular (i.c.v) injection at 15 microg, produced almost the same pattern of bladder hyperactivity as that observed after i.v. injection of these drugs (0.03 mg/kg, i.v.). For all three administration routes of clonidine and oxymetazoline, i.v. idazoxan (0.3 mg/kg) exerted an inhibitory effect on the bladder hyperactivity induced by these drugs, except i.c.v injection of oxymetazoline. I.t. phenylephrine (30 microg) did not change the intercontraction interval. Although i.c.v. phenylephrine (15 microg) shortened the intercontraction interval, the potency was weaker than those of i.c.v. clonidine and oxymetazoline (15 microg). These results suggest that clonidine and oxymetazoline cause bladder hyperactivity by acting at adrenergic alpha2 receptors in the micturition centers of the lumbosacral and supraspinal regions.

Contractile properties of urethral smooth muscles of young and aged female dogs: morphological and pharmacological aspects

BACKGROUND

Alpha1-adrenoceptors are highly concentrated in the urethral smooth muscles and may play an important role in the contraction of this area. However, detailed examinations of age-related changes of the properties of urethral smooth muscle have rarely been undertaken.

METHODS

The contractile properties of urethras from young non-parous and old parous female beagles were determined with a urethral function study, macroscopic autoradiography for urethras using [3H]-labeled tamsulosin and morphometry of the urethral muscles.

RESULTS

The antagonistic effect (pA2) of prazosin for norepinephrine was 7.76+/-0.13 in young dogs and 7.62+/-0.06 in aged dogs. The specific binding of [3H]-tamsulosin (a relatively selective alpha1A-adrenoceptor antagonist) was recognized diffusely in proximal urethras with in vitro autoradiography. The density of binding in smooth muscles was approximately 60 and 40% in circular longitudinal layers, respectively, for both dogs.

CONCLUSIONS

The female canine urethra had alpha1A, and alpha1L-adrenoceptors. No age-related changes were seen in the function of the proximal urethra, distribution of alpha1-adrenoceptor binding sites and smooth muscle densities.

Effects of spinal alpha 1-adrenoceptor antagonism on bladder activity induced by apomorphine in conscious rats with and without bladder outlet obstruction

To test the hypothesis that the spinal control of micturition involves alpha 1-adrenoceptors, the urodynamic effects of intrathecal and intraarterial alpha 1-adrenoceptor blockade on apomorphine-induced bladder activity in rats were studied. Continuous cystometry was performed in conscious female Sprague-Dawley rats with and without bladder outflow obstruction. In normal rats, subcutaneous apomorphine, 30 micrograms/kg, induced bladder activity that was abolished or attenuated by the alpha 1-adrenoceptor antagonists indoramin and doxazosin given intrathecally or intra-arterially. In rats with outlet obstruction, apomorphine 30 micrograms/kg caused no change in cystometric parameters. However, at a dose of 100 micrograms/kg the drug induced bladder activity, which was attenuated by intrathecal indoramin or doxazosin. These results suggest that the bladder activity evoked by apomorphine-stimulation of bulbospinal pathways can be influenced by alpha 1-adrenoceptors at the spinal and peripheral levels, both in normal rats and in rats with bladder hypertrophy secondary to outlet obstruction.

Diagnosis and management of urinary retention

Failure to empty the urinary bladder completely can be attributed to failure of detrusor contractile function, inappropriate outlet resistance, or both. For each of these mechanisms, anatomic, neurogenic, and end-organ (myogenic or idiopathic) abnormalities are possible. The approach to urinary retention involves systematic consideration of neurogenic, obstructive, and functional causes and requires understanding of the neurophysiology and pharmacology of micturation.

Serotonergic modulation of spinal ascending activity and sacral reflex activity evoked by pelvic nerve stimulation in cats

Serotonin (5-HT) may be inhibitory to micturition at a spinal level. A potential mechanism of action for serotonergic inhibition of bladder function is a depression of the ascending limb of the supraspinal reflex mediating micturition. Ascending activity evoked by pelvic nerve stimulation was recorded in the thoracic spinal cord of anesthetized cats. For comparison, spinal reflex activity evoked by pelvic nerve stimulation was recorded on the pudendal nerve. The effects of intrathecal administration of serotonergic agents were examined to determine whether spinal and supraspinal responses to bladder afferent activation were modulated by 5-HT. Methysergide (60 nmol), a non-selective serotonergic antagonist, increased ascending activity by 61+/-7% and depressed spinal reflex activity by 38+/-6%. Zatosetron (10 nmol), a 5-HT3 antagonist had a similar effect on both activities (increased by 93+/-24% and decreased by 77+/-7%, respectively). The effect on ascending activity of blocking 5-HT3 receptors was also confirmed with ICS 205930 and MDL 72222. 2-Methyl-5-HT (800 nmol), a 5-HT3 agonist, depressed ascending activity to 46+/-9% of control, but enhanced spinal reflex activity by 73+/-92%. These results demonstrate that stimulation of 5-HT3 and methysergide-sensitive 5-HT receptors can inhibit ascending activity and facilitate spinal reflex activity elicited by activation of bladder afferents. It is suggested that descending serotonergic pathways may participate in the spinal coordination of urinary continence.

Evidence for supraspinal nervous control of external anal sphincter motility in the cat

The aim of this study was to investigate the role of noradrenergic descending nervous pathways in external anal sphincter motility. For this purpose, the effects of intravenously injected adrenoceptor antagonist and agonist on the tonic electrical activity of this sphincter were studied in anesthetized cats. The effects of stimulating the region of the locus coeruleus and the effects of intravenous, intracerebroventricular and intrathecal injection of the above drugs on the electromyographic responses of this muscle to pudendal nerve stimulation were also investigated. The tonic sphincteric activity and the reflex response triggered by electrically stimulating pudendal afferent nerve fibers were inhibited by alpha1-adrenoceptor antagonist nicergoline and enhanced by alpha1-adrenoceptor agonist phenylephrine. Stimulation of the locus coeruleus area either inhibited or enhanced the reflex responses. Intracerebroventricular and intrathecal injection of the alpha2-adrenoceptor agonists, morphine and leu-enkephalin decreased the amplitude of these reflex responses. All the effects of opioids were blocked by naloxone and by spinalization performed at the cervical and lumbar levels. The direct response elicited by stimulating the sphincteric motor axons was not affected either by these drugs or by the brainstem stimulation. These results suggests the existence of a pontine neuronal network controlling the motility of the external anal sphincter via noradrenergic and opioid neurons.

Idiopathic detrusor-urethral dyssynergia in dogs: a retrospective analysis of 22 cases

Results of a retrospective study of 22 dogs with signs of dysuria and/or stranguria in which a diagnosis of idiopathic detrusor-urethral dyssynergia was made are presented. The diagnosis was based on the exclusion of detectable pathological conditions which could also cause urine outflow obstruction. The affected cases were 22 middle-aged male dogs (mean age 4.9 years) of large and giant breeds (mean bodyweight 36.7 kg). Nine dogs had had periodic clinical signs for longer than one year, one for seven months and eight for two to five weeks, while in four dogs signs had begun four to five days before referral. All dogs received the alpha-sympatholytic agent prazosin as an initial treatment and in 11 it remained the only therapy. There was a good effect in seven and a moderate response in the other four dogs. In one dog, prazosin was ineffective and was replaced by diazepam, which markedly reduced the signs. Three other dogs required frequent catheterisation and antibiotics were administered. These dogs responded favourably. Another three dogs with evidence of impaired bladder contractility were also treated with the parasympathomimetic agent carbachol. One did not improve and was euthanased. Four dogs developed bladder paralysis and severe infectious cystitis. Only one of these could be managed satisfactorily by long-term administration of prazosin, carbachol and antibiotics, and the others had to be euthanased.

Neurophysiology of micturition and continence

This article reviews the neuroanatomy, neurophysiology, and neuropharmacology involved in micturition and continence. Knowledge of these topics helps the clinician diagnose and treat voiding disorders that are caused by disease, trauma, drugs, and aging.