Alpha1-adrenergic receptor subtypes in human detrusor

Role of α- and β-adrenergic signaling in phenotypic targeting: significance in benign and malignant urologic disease

The urinary tract is highly innervated by autonomic nerves which are essential in urinary tract development, the production of growth factors, and the control of homeostasis. These neural signals may become dysregulated in several genitourinary (GU) disease states, both benign and malignant. Accordingly, the autonomic nervous system is a therapeutic target for several genitourinary pathologies including cancer, voiding dysfunction, and obstructing nephrolithiasis. Adrenergic receptors (adrenoceptors) are G-Protein coupled-receptors that are distributed throughout the body. The major function of α1-adrenoceptors is signaling smooth muscle contractions through GPCR and intracellular calcium influx. Pharmacologic intervention of α-and β-adrenoceptors is routinely and successfully implemented in the treatment of benign urologic illnesses, through the use of α-adrenoceptor antagonists. Furthermore, cell-based evidence recently established the antitumor effect of α1-adrenoceptor antagonists in prostate, bladder and renal tumors by reducing neovascularity and impairing growth within the tumor microenvironment via regulation of the phenotypic epithelial-mesenchymal transition (EMT). There has been a significant focus on repurposing the routinely used, Food and Drug Administration-approved α1-adrenoceptor antagonists to inhibit GU tumor growth and angiogenesis in patients with advanced prostate, bladder, and renal cancer. In this review we discuss the current evidence on (a) the signaling events of the autonomic nervous system mediated by its cognate α- and β-adrenoceptors in regulating the phenotypic landscape (EMT) of genitourinary organs; and (b) the therapeutic significance of targeting this signaling pathway in benign and malignant urologic disease. Video abstract.

Effects of an alpha-1d adrenoreceptor antagonist (naftopidil) on bladder dysfunction after radiotherapy in female rats

PURPOSE

Storage-phase bladder dysfunction can develop after pelvic radiotherapy. As the alpha-1d adrenoreceptor (a1d-AR) is dominant in the human detrusor, we aimed to investigate the effect of an a1d-AR antagonist on bladder dysfunction after pelvic radiotherapy in a rat model.

MATERIALS AND METHODS

Twenty-four female Wistar rats were used. Eight rats (14-15 weeks, 250-300 g) were randomized to three groups (normal reference group, radiation alone group and radiation plus naftopidil group). An 18-Gy dose of radiotherapy was applied to the radiation alone and radiation plus naftopidil groups. Naftopidil (20 mg/kg) was administered daily to the radiation plus naftopidil group. Four weeks after radiation, all rats underwent cystometry and were killed for reverse transcription polymerase chain reaction to detect mRNAs [a1d-AR, brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF)], Western blot to detect proteins (a1d-AR, extracellular-signal-regulated kinase, BDNF and VEGF) and immunohistochemistry.

RESULTS

Compared to the radiation alone group, (1) the decrease in the mRNA and protein expression of a1d-AR and VEGF was ameliorated, (2) the increase in the expression of BDNF mRNA and proteins such as extracellular-signal-regulated kinase and BDNF was suppressed, (3) submucosal thickness and vascularity on immunohistochemistry were improved, and (4) the baseline intravesical pressure and intercontraction interval in cystometry were ameliorated in the radiation plus naftopidil group.

CONCLUSION

Administration of an a1d-AR antagonist could improve storage-phase bladder dysfunction after radiotherapy not only by upregulating a1d-AR, which might decrease bladder compliance, but also by enhancing vascularity, which might protect the urinary bladder from chronic ischemic inflammation.

Drug Repositioning of the α1-Adrenergic Receptor Antagonist Naftopidil: A Potential New Anti-Cancer Drug?

Failure of conventional treatments is often observed in cancer management and this requires the development of alternative therapeutic strategies. However, new drug development is known to be a high-failure process because of the possibility of a lower efficacy than expected for the drug or appearance of non-manageable side effects. Another way to find alternative therapeutic drugs consists in identifying new applications for drugs already approved for a particular disease: a concept named "drug repurposing". In this context, several studies demonstrated the potential anti-tumour activity exerted by α1-adrenergic receptor antagonists and notably renewed interest for naftopidil as an anti-cancer drug. Naftopidil is used for benign prostatic hyperplasia management in Japan and a retrospective study brought out a reduced incidence of prostate cancer in patients that had been prescribed this drug. Further studies showed that naftopidil exerted anti-proliferative and cytotoxic effects on prostate cancer as well as several other cancer types in vitro, as well as ex vivo and in vivo. Moreover, naftopidil was demonstrated to modulate the expression of Bcl-2 family pro-apoptotic members which could be used to sensitise cancer cells to targeting therapies and to overcome resistance of cancer cells to apoptosis. For most of these anti-cancer effects, the molecular pathway is either not fully deciphered or shown to involve α1-adrenergic receptor-independent pathway, suggesting off target transduction signals. In order to improve its efficacy, naftopidil analogues were designed and shown to be effective in several studies. Thereby, naftopidil appears to display anti-cancer properties on different cancer types and could be considered as a candidate for drug repurposing although its anti-cancerous activities need to be studied more deeply in prospective randomized clinical trials.

Efficacy and Safety of Naftopidil in Patients With Neurogenic Lower Urinary Tract Dysfunction: An 8-Week, Active-Controlled, Stratified-Randomized, Double-Blind, Double-Dummy, Parallel Group, Noninferiority, Multicenter Design

Purpose

The aim of this study was to evaluate the efficacy and safety of naftopidil compared with tamsulosin in patients with neurogenic lower urinary tract dysfunction (LUTD).

Methods

This study was conducted as an 8-week, active-controlled, stratified-randomized, double-blind, double-dummy, parallel group, noninferiority, and multicenter clinical trial. After 2 weeks of screening, eligible subjects were randomly assigned to receive naftopidil (25 mg for 1 week followed by 75 mg for 7 weeks) or tamsulosin (0.2 mg for 8 weeks). Primary endpoint was a change of International Prostatic Symptom Score (IPSS) total score after 8 weeks of treatment.

Results

One hundred ninety-four subjects with neurogenic LUTD were included into this trial. There were no differences between the 2 groups in baseline characteristics, including urodynamic study results, subtype of LUTD, pretreatment and concomitant medication, and causes of neurogenic bladder. The medication compliance rate was 94.0% (naftopidil, 93.6%; tamsulosin, 94.4%). There was a statistically significant decrease of IPSS total score at 8 weeks versus baseline in both the naftopidil (-5.64±0.66) and tamsulosin (-6.53±0.65) groups (P<0.0001 each). The mean difference between both groups was 0.89 (upper limit of 95% confidential interval, 2.72), which was lower than the noninferiority limit of 3 points. A subgroup analysis of neurologic lesions and sex found no mean difference of IPSS total score in each group. There was also no difference in safety profiles, including treatment emergent adverse events.

Conclusions

Naftopidil was not inferior to tamsulosin as a therapeutic drug for patients with neurogenic LUTD and had a similar safety profile.

Chiral analogues of (+)-cyclazosin as potent α1B-adrenoceptor selective antagonist

(+)-Cyclazosin [(+)-1] is one of most selective antagonists of the α_1B-adrenoceptor subtype (selectivity ratios, α_1B/α_1A = 13, α_1B/α_1D = 38-39). To improve the selectivity, we synthesized and pharmacologically studied the blocking activity against α₁-adrenoceptors of several homochiral analogues of (+)-cyclazosin featuring different substituents on the carbonyl or amine groups, namely (-)-2, (+)-3, (-)-4-(-)-8, (+)-9. Moreover, we studied the activity of some their opposite enantiomers, namely (-)-1, (-)-3, (+)-6, and (-)-9, to evaluate the influence of stereochemistry on selectivity. The benzyloxycarbonyl and methyl (4aS,8aR) analogues (+)-3 and (-)-6 improved in a significant way the α_1B selectivity of the progenitor compound: 4 and 14 time vs. the α_1D subtype and 35 and 77 times vs. the α_1A subtype, respectively. The study confirmed the importance of the hydrophobic cis-octahydroquinoxaline moiety of these molecules for the establishment of interactions with the α₁-adrenoceptors as well that of their (4aS,8aR) stereochemistry to grant selectivity for the α_1B subtype. Hypotheses on the mode of interaction of these compounds were advanced on the basis of molecular modeling studies performed on compound (+)-3.

Clinical Efficacy and Safety of Naftopidil Treatment for Patients with Benign Prostatic Hyperplasia and Hypertension: A Prospective, Open-Label Study

PURPOSE

To investigate the efficacy and safety of naftopidil for benign prostatic hyperplasia (BPH) patients, mainly focusing on changes in blood pressure (BP).

MATERIALS AND METHODS

Of a total of 118 patients, 90 normotensive (NT) and 28 hypertensive (HT) patients were randomly assigned to be treated with naftopidil 50 mg or 75 mg for 12 weeks, once-daily. Safety and efficacy were assessed by analyzing changes from baseline in systolic/diastolic BP and total International Prostate Symptom Score (IPSS) at 4 and 12 weeks. Adverse events (AEs), obstructive/irritative subscores, quality of life (QoL) score, maximum urinary flow rate (Qmax), and benefit, satisfaction with treatment, and willingness to continue treatment (BSW) questionnaire were also analyzed.

RESULTS

Naftopidil treatment decreased mean systolic BP by 18.7 mm Hg for the HT 50 mg group (p<0.001) and by 18.3 mm Hg for the HT 75 mg group (p<0.001) and mean diastolic BP by 17.5 mm Hg for the HT 50 mg group (p<0.001) and by 14.7 mm Hg for the HT 75 mg group (p=0.022). In the NT groups (both naftopidil 50 mg and 75 mg), naftopidil elicited no significant changes in BP from baseline values. After 12 weeks, naftopidil 50 and 75 mg groups showed significant improvements in IPSS scores (total, obstructive/irritative subscores, QoL score) and Qmax from baseline. AEs were reported in 7.8% (50 mg group) and 2.9% (75 mg group) of patients. In both the 50 mg and 75 mg groups, >86% of all patients agreed to continue their current medications.

CONCLUSION

Our results suggest that naftopidil treatment in BPH patients with hypertension allows for optimal management of BP within the normal range.

The impact and management of sexual dysfunction secondary to pharmacological therapy of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is one of the most common genitourinary complications in men over 50 years of age and typically presents with lower urinary tract symptoms (LUTS). Classes of medications include α1-adrenoceptor blockers, 5α-reductase inhibitors, and phosphodiesterase 5 inhibitors. Today, α1-adrenoceptor blockers and 5α-reductase inhibitors are often combined to give a synergistic effect. A review of the current literature identified several adverse sexual side effects, including erectile dysfunction (ED), decreased libido, orgasmic disorders, and ejaculatory disorders. We believe it is important to know the extent of these side effects, as the clinician and patient will need to decide the cost of improved voiding symptoms. The chief adverse effect is ejaculatory disorders, including the absence of ejaculation. Clinical consideration for BPH should include the elements of male sexual function, patients’ age, and the characteristics and comprehensive effects of each group of drugs. Methodological bias in clinical studies, such as the subjective evaluation of the sexual side effect, makes it difficult to determine the ideal drug for treatment.

[S2e guideline of the German urologists: Conservative and pharmacologic treatment of benign prostatic hyperplasia]

This report summarizes the relevant aspects of the S2e guideline of the German Urologists for the conservative and pharmacological treatment of lower urinary tract symptoms due to benign prostatic hyperplasia. Recommendations are given regarding watchful waiting, behavioral therapy, phytotherapy and pharmacological mono- and combination therapy. The influence of the different therapeutic options on bladder outlet obstruction (BOO) is described in detail.

The drug treatment of delayed ejaculation

Delayed ejaculation (DE) is an uncommon and a challenging disorder to treat. It is often quite concerning to patients and it can affect psychosocial well-being. Here we reviewed how DE is treated pharmacologically .We also highlighted specific settings where drugs could be introduced to medical practice. Electronic databases were searched from 1966 to February 2016, including PubMed MEDLINE, EMBASE, EBCSO Academic Search Complete, Cochrane Systematic Reviews Database, and Google Scholar using key words; delayed ejaculation, retarded ejaculation, inhibited ejaculation, drugs, treatment, or pharmacology. To achieve the maximum sensitivity of the search strategy and to identify all studies, we combined “delayed ejaculation” as Medical Subject Headings (MeSH) terms or keywords with each of “testosterone” or “cabergoline” or “bupropion” or “amantadine” or “cyproheptadine” or “midodrine” or “imipramine” or “ephedrine” or “pseudoephedrine” or “yohimbine” or “buspirone” or “oxytocin” or “bethanechol” as MeSH terms or keywords. There are a number of drugs to treat patients with DE including: testosterone, cabergoline, bupropion, amantadine, cyproheptadine, midodrine, imipramine, ephedrine, pseudoephedrine, yohimbine, buspirone, oxytocin, and bethanechol. Although there are many pharmacological treatment options, the evidence is still limited to small trials, case series or case reports. Review of literature showed that evidence level 1 (Double blind randomized clinical trial) studies were performed with testosterone, oxytocin, buspirone or bethanechol treatment. It is concluded that successful drug treatment of DE is still in its infancy. The clinicians need to be aware of the pathogenesis of DE and the pharmacological basis underlying the use of different drugs to extend better care for these patients. Various drugs are available to address such problem, however their evidence of efficacy is still limited and their choice needs to be individualized to each specific case.

α1-adrenergic receptor antagonists versus placebo for female lower urinary tract symptoms: A meta-analysis

The aim of the present study was to evaluate the effectiveness of α₁-adrenergic receptor antagonists (α₁ARAs) versus placebo for female patients with lower urinary tract symptoms (LUTS). A meta-analysis of randomized controlled trials was conducted. The main outcome indices used to measure the effectiveness were the total International Prostate Symptom Score (I-PSS) and maximum urinary flow rate of female patients receiving treatment for LUTS. The I-PSS quality of life (QOL) and average urinary flow rate (AFR) were also observed and analyzed. Two randomized controlled trials with a total of 213 patients were included. Meta-analysis results were as follows: Following 4 weeks of treatment, patients taking α₁ARAs presented a significant advantage over patients under placebo in terms of total I-PSS [standardized mean difference (SMD), -0.67; 95% confidence interval (CI), -0.94 to -0.39] but no difference was observed in maximum urinary flow rate (SMD, -0.05; 95% CI, -0.32 to 0.22) between the experimental and control groups. The I-PSS QOL post-treatment was lower in the α₁ARA group compared with that in the placebo group (SMD, -0.86; 95% CI, -1.32 to -0.40) according to one study, and in the other study the improvement of AFR was not significant (SMD, 0.09; 95% CI, -0.25 to 0.43). It was concluded that α₁ARAs are more effective than placebo in female patients with LUTS.

Impact of alpha blockers, 5-alpha reductase inhibitors and combination therapy on sexual function

Medical treatments for lower urinary tract symptoms due to benign prostatic hyperplasia are frequently associated with changes in sexual function. While these medications are generally well-tolerated and have both reduced and delayed more invasive surgical options, the ramifications of long-term chronic use are largely unknown. Sexual side effects of these medications are frequently either reported as part of a short-term initial drug study or have inflexible endpoints that are not able to gauge more subtle changes in sexual performance. This review will delineate the currently known effects of these medications on sexual function and will consider mechanisms of dysfunction.

Efficacy and Safety of the Selective α1A-Adrenoceptor Blocker Silodosin for Severe Lower Urinary Tract Symptoms Associated With Benign Prostatic Hyperplasia: A Prospective, Single-Open-Label, Multicenter Study in Korea

Purpose

To evaluate the efficacy and safety of silodosin 8 mg once daily in a 12-week treatment of subjects with severe lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH).

Materials and Methods

A total of 100 subjects from 10 urology centers in Korea were included in this study. The inclusion criteria were as follows: age ≥50 years, International Prostate Symptom Score (IPSS) ≥20, quality of life (QoL) score ≥3, urine volume ≥120 mL and maximal urinary flow rate (Qmax) <15 mL/s, and postvoid residual volume (PVR) <100 mL. We assessed the improvement of LUTS with change in IPSS, QoL score, Qmax, PVR, and adverse events at baseline and 4 and 12 weeks after treatment with silodosin 8 mg once daily.

Results

The IPSS values were 23.27±3.34, 15.89±6.26, and 13.80±6.31 at baseline, 4, and 12 weeks, respectively, with significant improvements (p<0.0001, p=0.0214, respectively). QoL scores were 4.44±0.85, 3.38±1.20, and 3.04±1.20 at baseline, 4, and 12 weeks, respectively, and the differences were statistically significant (p<0.0001). There was a significant difference in Qmax between baseline and 12 weeks (p<0.0001) but not in PVR (p=0.9404) during the clinical trial. The most frequent adverse event in this study was ejaculation failure with 13 cases. However, no subject dropped out because of ejaculation failure, and in 12 of the 13 cases it was fully resolved without further treatment.

Conclusions

Silodosin 8 mg once daily may be effective and safe in Korean patients with severe LUTS associated with BPH.

Non-Hormonal treatment of BPH/BOO

OBJECTIVES

To review the use of non-hormonal pharmacotherapies in the treatment of lower urinary tract symptoms (LUTS) due to presumed benign prostatic hyperplasia (BPH).

MATERIALS AND METHODS

A search of the PUBMED database was conducted for the terms BPH, LUTS, bladder outlet obstruction, alpha-adrenoceptor blockers, anti-muscarinics, and phosphodiesterase-5-inhibitors.

RESULTS

Medical therapy has long been established as the accepted standard of care in the treatment of male LUTS. The aim of treatment is improvement in symptoms and quality of life whilst minimizing adverse effects. The agents most widely used as 1(st) line therapy are alpha-blockers (AB), as a standalone or in combination with 2 other classes of drug; 5-α reductase inhibitors and anti-muscarinics. AB have rapid efficacy, improving symptoms and flow rate in a matter of days, these effects are then maintained over time. AB do not impact on prostate size and do not prevent acute urinary retention or the need for surgery. Anti-mucarinics, alone or in combination with an AB are safe and efficacious in the treatment of bothersome storage symptoms associated with LUTS/BPH. Phosphodiesterase-5 inhibitors are an emerging treatment option that improve LUTS without improving flow rates.

CONCLUSIONS

AB are the most well-established pharmacotherapy in the management of men with LUTS/BPH. The emergence of different classes of agent offers the opportunity to target underlying pathophysiologies driving symptoms and better individualize treatment.

Phenotypic switching induced by damaged matrix is associated with DNA methyltransferase 3A (DNMT3A) activity and nuclear localization in smooth muscle cells (SMC)

Extracellular matrix changes are often crucial inciting events for fibroproliferative disease. Epigenetic changes, specifically DNA methylation, are critical factors underlying differentiated phenotypes. We examined the dependency of matrix-induced fibroproliferation and SMC phenotype on DNA methyltransferases. The cooperativity of matrix with growth factors, cell density and hypoxia was also examined. Primary rat visceral SMC of early passage (0–2) were plated on native collagen or damaged/heat-denatured collagen. Hypoxia was induced with 3% O₂ (balanced 5% CO₂ and 95% N₂) over 48 hours. Inhibitors were applied 2–3 hours after cells were plated on matrix, or immediately before hypoxia. Cells were fixed and stained for DNMT3A and smooth muscle actin (SMA) or smooth muscle myosin heavy chain. Illumina 450 K array of CpG sites was performed on bisulfite-converted DNA from smooth muscle cells on damaged matrix vs native collagen. Matrix exquisitely regulates DNMT3A localization and expression, and influences differentiation in SMCs exposed to denatured matrix +/− hypoxia. Analysis of DNA methylation signatures showed that Matrix caused significant DNA methylation alterations in a discrete number of CpG sites proximal to genes related to SMC differentiation. Matrix has a profound effect on the regulation of SMC phenotype, which is associated with altered expression, localization of DNMTs and discrete changes DNA methylation.

The role of naftopidil in the management of benign prostatic hyperplasia

Naftopidil, which to a certain extent shows an affinity to α1D-adrenoceptor subtype in addition to a high affinity to α1A-adrenoceptor, has been used for the treatment of benign prostatic obstruction and benign prostatic hyperplasia (BPH) associated lower urinary tract symptoms (LUTS). The aim of the present review is to systematically refer to the published studies on this unique agent for BPH. Based on a randomized prazosin-controlled study and another double-blind placebo-controlled study, which verified the dose-dependent effects of naftopidil, the Japanese Ministry of Health, Labor and Welfare approved naftopidil for treating men with BPH in 1996. Several tamsulosin-controlled studies have suggested treatment effects of naftopidil similar to those of tamsulosin and potentially higher efficacy for alleviating storage symptoms by naftopidil. Although well-designed, randomized studies are warranted to confirm the long-term outcomes and effector/target of naftopidil, the α1A-antagonist naftopidil, which also blocks α1D-adrenoceptor, improves voiding symptoms, and may also be useful for the management of men with storage symptoms represented by nocturia, retrieving their quality of life impaired by BPH-associated LUTS.

Experience with the combination of dutasteride and tamsulosin in the long-term management of benign prostatic hyperplasia

Lower urinary tract symptoms (LUTS) caused by benign prostatic hyperplasia (BPH) commonly affect older men. These bothersome symptoms can lead to a decreased quality of life. Currently, two classes of drugs - α-adrenergic blockers and 5α-reductase inhibitors - are prescribed to treat LUTS secondary to BPH. Due to their different mechanisms of action, these medications work in a synergistic manner. Trials of combination therapy have been conducted to assess its effect compared with monotherapy. Current data support combination therapy in men with moderately enlarged prostates and moderate to severe symptoms.

Modulation of alpha 1 adrenergic receptors on urinary bladder in rat spinal cord injury model

Purpose

Whereas many studies have focused on the vesical changes of the α1 adrenergic receptor (AR) subtypes in partial outlet obstruction, few studies have addressed the modulation of the α1 AR subtypes after spinal cord injury (SCI). Therefore, we studied the modulation of the α1 ARs in urinary bladder in a rat SCI model.

Methods

Four weeks after a SCI, the whole vesical bodies from eight female Sprague-Dawley rats and from eight controls were harvested. The total RNA was extracted from the samples and was used to prepare cDNA. We developed standard plasmid constructs of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and three α1 ARs (α1a, α1b, and α1d) to convert the cycle threshold (Ct) values from real-time polymerase chain reaction (RT-PCR) into subtype mRNA concentrations. The detected Ct values of 16 samples from RT-PCR were interpolated into the standard plasmid curves.

Results

All serially diluted standard samples showed very good linearity. The mRNA expression of GAPDH was higher in the SCI group, whereas the mRNA expression of all α1 ARs was lower in the SCI group than in the control animals. The α1a, α1b, and α1d mRNA expression in the controls was 81.7%, 3.3%, and 15.1%, respectively, whereas the α1a, α1b, and α1d mRNA expression in the SCI group was 33.5%, 5.2%, and 60.9%, respectively.

Conclusions

SCI moderates the α1 AR mRNA subtypes in the urinary bladder. The relatively increased α1d or decreased α1a AR mRNA expression may be a therapeutic candidate for controlling the symptoms of neurogenic bladder after SCI.

Phenotype pharmacology of lower urinary tract α(1)-adrenoceptors

α(1)-Adrenoceptors are involved in numerous physiological functions, including micturition. However, the pharmacological profile of the α(1)-adrenoceptor subtypes remains controversial. Here, we review the literature regarding α(1)-adrenoceptors in the lower urinary tract from the standpoint of α(1L) phenotype pharmacology. Among three α(1)-adrenoceptor subtypes (α(1A), α(1B) and α(1D)), α(1a)-adrenoceptor mRNA is the most abundantly transcribed in the prostate, urethra and bladder neck of many species, including humans. In prostate homogenates or membrane preparations, α(1A)-adrenoceptors with high affinity for prazosin have been detected as radioligand binding sites. Functional α(1)-adrenoceptors in the prostate, urethra and bladder neck have low affinity for prazosin, suggesting the presence of an atypical α(1)-adrenoceptor phenotype (designated as α(1L)). The α(1L)-adrenoceptor occurs as a distinct binding entity from the α(1A)-adrenoceptor in intact segments of variety of tissues including prostate. Both the α(1L)- and α(1A)-adrenoceptors are specifically absent from Adra1A (α(1a)) gene-knockout mice. Transfection of α(1a)-adrenoceptor cDNA predominantly expresses α(1A)-phenotype in several cultured cell lines. However, in CHO cells, such transfection expresses α(1L)- and α(1A)-phenotypes. Under intact cell conditions, the α(1L)-phenotype is predominant when co-expressed with the receptor interacting protein, CRELD1α. In summary, recent pharmacological studies reveal that two distinct α(1)-adrenoceptor phenotypes (α(1A) and α(1L)) originate from a single Adra1A (α(1a)-adrenoceptor) gene, but adrenergic contractions in the lower urinary tract are predominantly mediated via the α(1L)-adrenoceptor. From the standpoint of phenotype pharmacology, it is likely that phenotype-based subtypes such as the α(1L)-adrenoceptor will become new targets for drug development and pharmacotherapy.

Effects of Spinal and Peripheral Injection of α1A or α1D Adrenoceptor Antagonists on Bladder Activity in Rat Models with or without Bladder Outlet Obstruction

PURPOSE

Antagonists of α1-adrenergic receptors (α1ARs) relax prostate smooth muscle and relieve voiding and storage symptoms. Recently, increased expression of α1ARs with change of its subtype expression has been proved in bladder outlet obstruction (BOO). To search for the evidence of changes in α1ARs subtype expression and activity in the peripheral and spinal routes, the effects of spinal and peripheral administration of tamsulosin (an α1A/D-selective AR), naftopidil (an α1A/D-selective AR), and doxazosin (non-selective AR) on bladder activity were investigated in a rat model with or without BOO.

METHODS

A total of 65 female Sprague-Dawley rats were divided into the BOO surgery group (n=47) and the sham surgery group (n=18). After 6 weeks, cystometry was assessed before and after intrathecal and intra-arterial administrations of tamsulosin, naftopidil, and doxazosin.

RESULTS

After intra-arterial administrations of all three drugs, bladder capacity (BC) was increased and maximal intravesical pressure (Pmax) was decreased in both BOO and the sham rat models (P<0.05). After intrathecal administration of all three drugs, BC was increased and Pmax was decreased in only the BOO group. The episodes of involuntary contraction in the BOO rat models were decreased by intra-arterial administration (P=0.031). The increase of BC after intrathercal and intra-arterial administrations of α1ARs was significantly greater in the BOO group than in the sham group (P=0.023, P=0.041). In the BOO group, the increase of BC and decrease in Pmax were greater by intra-arterial administration than by intrathecal administration (P=0.035). There were no significant differences of the degrees of changes in the cystometric parameters among the three different α1ARs.

CONCLUSIONS

Up-regulations of the α1ARs in BOO were observed by the greater increases of BC after α1AR antagonist administrations in the BOO group than in the sham group. However, there were no subtype differences of the α1ARs in functional parameters of bladder activity. In addition, α1ARs also act on the lumbosacral cord which implies that the sensitivity of α1ARs is increased in pathologic models such as BOO. Further evaluation including differential expression of α1ARs in BOO models are need.

Effect of 5-alpha Reductase Inhibitor on Storage Symptoms in Patients with Benign Prostatic Hyperplasia

Purpose

Many patients with benign prostatic hyperplasia (BPH) have storage symptoms. The aim of this study was to evaluate the effects of treatment with a 5-alpha reductase inhibitor (5ARI) on storage symptoms in patients with BPH.

Methods

This study was conducted in 738 patients with lower urinary tract symptoms secondary to BPH. Patients with a prostate volume of higher than 30 mL on the transrectal ultrasound were classified into two groups: group A, in which an alpha blocker was solely administered for at least 12 months, and group B, in which a combination treatment regimen of an alpha blocker plus 5ARI was used. This was followed by an analysis of the changes in parameters such as the total International Prostate Symptom Score (IPSS), voiding symptom subscore, and storage symptom subscore between the two groups. In addition, we examined whether there was a significant difference between the two groups in the degree of change in storage symptoms between before and after the pharmacological treatment.

Results

Of the 738 men, 331 had a prostate volume ≥30 mL, including 150 patients in group A and 181 patients in group B. Total IPSS, the voiding symptom subscore, and the storage symptom subscore were significantly lower after treatment than before treatment in both groups (P<0.05). A comparison of the degree of change between before and after treatment, however, showed no significant differences in the storage symptom subscore between the two groups (P>0.05).

Conclusions

Alpha blocker and 5ARI combination treatment is effective for patients with BPH including storage symptoms. However, 5ARI does not exert a significant effect on storage symptoms in BPH patients.

Naftopidil for the treatment of urinary symptoms in patients with benign prostatic hyperplasia

Naftopidil, approved only in Japan, is an α1-adrenergic receptor antagonist (α1-blocker) used to treat lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH). Different from tamsulosin hydrochloride and silodosin, in that it has higher and extremely higher affinity respectively, for the α1A-adrenergic receptor subtype than for the α1D type, naftopidil has distinct characteristics because it has a three times greater affinity for the α1D-adrenergic receptor subtype than for the α1A subtype. Although well-designed large-scale randomized controlled studies are lacking and the optimal dosage of naftopidil is not always completely determined, previous reports from Japan have shown that naftopidil has superior efficacy to a placebo and comparable efficacy to other α1-blockers such as tamsulosin. On the other hand, the incidences of ejaculatory disorders and intraoperative floppy iris syndrome induced by naftopidil may be lower than for tamsulosin and silodosin having high affinity for the α1A-adrenergic receptor subtype. However, it remains unknown if the efficacy and safety of naftopidil in Japanese is applicable to white, black and Hispanic men having LUTS/BPH in western countries.

A novel structural framework for α(1A/D)-adrenoceptor selective antagonists identified using subtype selective pharmacophores

In this study four and five-feature pharmacophores for selective antagonists at each of the three α(1)-adrenoceptor (AR) subtypes were used to identify novel α(1)-AR subtype selective compounds in the National Cancer Institute and Tripos LeadQuest databases. 12 compounds were selected, based on diversity of structure, predicted high affinity and selectivity at the α(1D)- subtype compared to α(1A)- and α(1B)-ARs. 9 out of 12 of the tested compounds displayed affinity at the α(1A) and α(1D) -AR subtypes and 6 displayed affinity at all three α(1)-AR subtypes, no α(1B)-AR selective compounds were identified. 8 of the 9 compounds with α(1)-AR affinity were antagonists and one compound displayed partial agonist characteristics. This virtual screening has successfully identified an α(1A/D)-AR selective antagonist, with low µM affinity with a novel structural scaffold of a an isoquinoline fused three-ring system and good lead-like qualities ideal for further drug development.

Management of benign prostatic hyperplasia with silodosin

It has been reported that blockade of α1A-adrenoceptor (AR) relieves bladder outlet obstruction, while blockade of α1D-AR is believed to alleviate storage symptoms due to detrusor overactivity. Silodosin, (-)-1-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2trifluoroethoxy) phenoxy]ethyl}amino)propyl]-2,3-dihydro-1H-indole-7- carboxamide, is a new α1A-AR selective antagonist. Silodosin is highly selective for the α1A-AR subtype, showing an affinity for the α1A-AR that is 583- and 55.5-fold higher than its affinity for the α1B-and α1D-ARs, respectively. In randomized, double-blind, placebo-controlled phase III studies performed in Japan and the United States, silodosin has been shown to be effective for both storage and voiding symptoms associated with benign prostatic hyperplasia. Early effects of silodosin (after 2-6 hours or day 1) on lower urinary tract symptoms have also been reported. In urodynamic studies, detrusor overactivity disappeared in 40% and improved in 35% of patients after administration. In pressure flow studies, the grade of obstruction on the International Continence Society nomogram showed improvement in 56% of patients. The rate of adverse events in the silodosin, tamsulosin and placebo groups was 88.6%, 82.3%, and 71.6%, respectively. The most common adverse event was (mostly mild) abnormal ejaculation (28.1%). However, few patients (2.8%) discontinued silodosin because of abnormal ejaculation. Orthostatic hypotension showed a similar incidence in the silodosin (2.6%) and placebo (1.5%) groups. In conclusion, silodosin improves detrusor overactivity and obstruction and thus may be effective for both storage and voiding symptoms in patients with benign prostatic hyperplasia.

Subtypes of alpha1-adrenoceptors in BPH: future prospects for personalized medicine

The alpha(1)-adrenoceptors (alpha(1)-ARs) are involved in regulation of prostatic smooth muscle tone, and are a critical mediator of lower urinary tract symptoms and pathophysiology in benign prostatic hyperplasia (BPH). As a result, alpha(1)-AR antagonists are now used as first-line medical treatment for BPH. Three alpha(1)-AR subtypes (alpha(1a)-AR, alpha(1b)-AR, alpha(1d)-AR) have been identified on the basis of results of pharmacological and molecular cloning studies; however, the precise physiological role of individual alpha(1)-AR subtypes remains elusive. The expression levels of alpha(1)-AR subtypes in the prostate differ between patients, and individual differences in the genetic background of patients with BPH might be associated with variation in responses to subtype-selective alpha(1)-AR antagonists. In addition, single nucleotide polymorphism and microarray-based gene expression profiling studies might provide an opportunity to identify markers that predict clinical response and therapeutic tolerance to alpha(1)-AR antagonists. Further genomic studies will refine our knowledge of the functions of alpha(1)-AR subtypes, lead to new strategies for the clinical management of BPH and, perhaps, enable personalized treatment of BPH in the future.

The involvement of urothelial alpha1A adrenergic receptor in controlling the micturition reflex

The current study was undertaken in an attempt to characterize the functional properties of urothelial alpha1A adrenergic receptors, especially in modulating the micturition reflex. The expression of alpha1A receptors in rat bladder was analyzed by immunohistochemistry and Western blotting. As a functional study, we obtained continuous infusion cystometrograms in conscious rats using noradrenaline (NA) and subtype selective alpha1 adrenergic receptor antagonists, tamsulosin (alpha1A/alpha1D selective) and silodosin (alpha1A superselective). Alpha1A receptors were immunohistochemically detected in rat urothelium. Intravesical infusion of NA (60 microM) significantly shortened the intercontraction interval (ICI). Pretreatment with tamsulosin at a dose of 0.4 microg/kg i.v. abolished intravesical NA infusioninduced reduction of ICI. Neither intravesical infusion of tamsulosin (20 microM) nor that of silodosin (0.2 microM) significantly altered ICI. After intravesical infusion of silodosin, intravesical NA infusion did not affect ICI. Urothelial alpha1A receptors might modulate bladder afferent activity under pathophysiological conditions with augmented concentrations of NA in blood or urine.

Common approach to managing lower urinary tract symptoms and erectile dysfunction

The present paper serves as a review of the associations between lower urinary tract symptoms (LUTS) and erectile dysfunction (ED), with a focus on common and combined pathways for treatment. LUTS and ED are common conditions seen in general urologic practice. Research has started to establish epidemiologic and pathophysiologic links between the two conditions and a strong association confirmed across multiple studies. Men seeking care for one condition should always be interviewed for complaints of the other condition. Proposed common pathways include alpha-1 adrenergic receptor imbalance, Rho-kinase overactivity, endothelial cell dysfunction and atherosclerosis-induced ischemia. Medical therapy has replaced surgery as the first-line treatment for LUTS in most patients, with the incorporation of alpha-adrenergic receptor antagonists (alpha-ARAs) and 5-alpha-reductase inhibitors (5-ARIs) into everyday practice. Treatment with alpha-ARAs contributes to some improvement in ED, whereas use of 5-ARIs results in worsened sexual function in some patients. Phosphodiesterase-5 (PDE-5) inhibitors have revolutionized the treatment of ED with a simple oral regimen, and new insights demonstrate a benefit of combined use of PDE-5 inhibitors and alpha-ARAs. The mechanisms of action of these medications support these observed benefits, and they are being studied in the basic science and clinical settings. In addition, novel mechanisms for therapy have been proposed based on clinical and research observations. The minimally invasive and surgical treatments for LUTS are known to have adverse effects on ejaculatory function, while their effects on erectile function are still debated. Much remains to be investigated, but it is clear that the associations between LUTS and ED lay the foundation for future therapies and possible preventative strategies.

Alpha1-adrenoceptor subtypes and lower urinary tract symptoms

Benign prostatic hyperplasia (BPH) is a common cause of urinary outflow obstruction in aging men leading to lower urinary tract symptoms (LUTS). alpha(1)-Adrenoceptors (alpha(1)ARs) antagonists (blockers) have become a mainstay of LUTS treatment because they relax prostate smooth muscle and decrease urethral resistance, as well as relieving bladder LUTS symptoms. A review of key recent clinical trials suggests new insights into the role of specific alpha(1)AR subtypes in the treatment of LUTS.

A randomized double-blind placebo-controlled multicentre study to explore the efficacy and safety of tamsulosin and tolterodine in women with overactive bladder syndrome

OBJECTIVES

To evaluate the efficacy of tamsulosin oral-controlled absorption system (OCAS) vs placebo in overactive bladder (OAB), to evaluate the safety and tolerability of once-daily dosing with tamsulosin OCAS, and to compare the efficacy and safety with tolterodine extended-release (ER).

PATIENTS AND METHODS

A parallel-group, multicentre, multinational study was conducted with a single-blind placebo run-in period of 2 weeks, followed by a randomized, double-blind, double-dummy active and placebo-controlled treatment period of 6 weeks; women (aged 18-70 years) with symptoms of OAB for >/= 3 months were recruited. Women were randomized to receive one of four doses of tamsulosin OCAS (0.25, 0.5, 1.0 or 1.5 mg), 4 mg of tolterodine ER, or placebo once daily for 6 weeks. The primary efficacy variable was the change in the mean number of voids/24 h. Secondary efficacy variables included change from baseline in; mean volume voided per void, mean number of incontinence episodes/24 h, mean number of urgency episodes/24 h and in quality of life (QoL), as assessed using the Kings Health Questionnaire (KHQ).

RESULTS

Overall, 364 women were randomized; the primary efficacy analysis showed that the difference from placebo in the mean number of voids/24 h was not statistically significant for tamsulosin OCAS 1.5 mg (P = 0.189). There was no statistically significant difference for tolterodine ER 4 mg vs placebo in the mean number of voids/24 h (P = 0.353). Similarly, for the secondary outcome variables there was no statistically significant difference between tamsulosin and placebo. Although women taking tolterodine ER 4 mg had a consistently greater increase in mean voided volume/void and consistent decreases in incontinence episodes/24 h, urgency episodes/24 h and episodes of nocturia/24 h, this was not statistically significant. There was no significant improvement in QoL scores across the treatment groups. Tamsulosin OCAS was well tolerated and the proportion of women discontinuing because of adverse events was low (4.7%).

CONCLUSION

Tamsulosin is not effective for treating OAB in women and the evidence from this study does not support its use on an empirical basis.

Epigenetic regulation of human alpha1d-adrenergic receptor gene expression: a role for DNA methylation in Sp1-dependent regulation

A growing body of evidence implicates alpha1-adrenergic receptors (alpha1ARs) as potent regulators of growth pathways. The three alpha1AR subtypes (alpha1aAR, alpha1bAR, alpha1dAR) display highly restricted tissue expression that undergoes subtype switching with many pathological stimuli, the mechanistic basis of which remains unknown. To gain insight into transcriptional pathways governing cell-specific regulation of the human alpha1dAR subtype, we cloned and characterized the alpha1dAR promoter region in two human cellular models that display disparate levels of endogenous alpha1dAR expression (SK-N-MC and DU145). Results reveal that alpha1dAR basal expression is regulated by Sp1-dependent binding of two promoter-proximal GC boxes, the mutation of which attenuates alpha1dAR promoter activity 10-fold. Mechanistically, chromatin immunoprecipitation data demonstrate that Sp1 binding correlates with expression of the endogenous gene in vivo, correlating highly with alpha1dAR promoter methylation-dependent silencing of both episomally expressed reporter constructs and the endogenous gene. Further, analysis of methylation status of proximal GC boxes using sodium bisulfite sequencing reveals differential methylation of proximal GC boxes in the two cell lines examined. Together, the data support a mechanism of methylation-dependent disruption of Sp1 binding in a cell-specific manner resulting in repression of basal alpha1dAR expression.

Alpha1-, alpha2- and beta-adrenoceptors in the urinary bladder, urethra and prostate

1 We have systematically reviewed the presence, functional responses and regulation of alpha(1)-, alpha(2)- and beta-adrenoceptors in the bladder, urethra and prostate, with special emphasis on human tissues and receptor subtypes. 2 Alpha(1)-adrenoceptors are only poorly expressed and play a limited functional role in the detrusor. Alpha(1)-adrenoceptors, particularly their alpha(1A)-subtype, show a more pronounced expression and promote contraction of the bladder neck, urethra and prostate to enhance bladder outlet resistance, particularly in elderly men with enlarged prostates. Alpha(1)-adrenoceptor agonists are important in the treatment of symptoms of benign prostatic hyperplasia, but their beneficial effects may involve receptors within and outside the prostate. 3 Alpha(2)-adrenoceptors, mainly their alpha(2A)-subtype, are expressed in bladder, urethra and prostate. They mediate pre-junctional inhibition of neurotransmitter release and also a weak contractile effect in the urethra of some species, but not humans. Their overall post-junctional function in the lower urinary tract remains largely unclear. 4 Beta-adrenoceptors mediate relaxation of smooth muscle in the bladder, urethra and prostate. The available tools have limited the unequivocal identification of receptor subtypes at the protein and functional levels, but it appears that the beta(3)- and beta(2)-subtypes are important in the human bladder and urethra, respectively. Beta(3)-adrenoceptor agonists are promising drug candidates for the treatment of the overactive bladder. 5 We propose that the overall function of adrenoceptors in the lower urinary tract is to promote urinary continence. Further elucidation of the functional roles of their subtypes will help a better understanding of voiding dysfunction and its treatment.

Clinical implications from studies of alpha1 adrenergic receptor knockout mice

alpha1-Adrenergic receptors (alpha1-ARs) modulate a large number of physiological functions in cardiovascular and noncardiovascular tissues. Because individual members of the alpha1-AR family (alpha1A-, alpha1B-, and alpha1D-ARs) have overlapping expression profiles in most tissues, elucidation of the precise physiological roles of individual alpha1-AR subtypes remains a challenging task. To alleviate this constraint, a gene targeting approach has been employed to generate mutant mice lacking one or two alpha1-AR genes. Recent studies on these mutant mouse strains are discussed in this article, with an emphasis on the role of alpha1-AR in the central nervous system and lower urinary tracts. These are two major tissues of particular interest for the development of new therapeutic strategies targeted to the alpha1-ARs. By combining gene targeting techniques with pharmacological tools, the specific roles of alpha1-AR subtypes could be delineated.

Polymorphisms in the alpha1A-adrenoceptor gene do not modify the short- and long-term efficacy of alpha1-adrenoceptor antagonists in the treatment of benign prostatic hyperplasia

OBJECTIVE To determine whether a common single nucleotide polymorphism (SNP) in the ADRA1A gene encoding the alpha(1A)-adrenoceptor modifies the short- and long-term efficacy of alpha(1)-adrenoceptor antagonists in the treatment of benign prostatic hyperplasia (BPH). PATIENTS AND METHODS For 254 patients with BPH and/or lower urinary tract symptoms who received alpha(1)-adrenergic antagonists for > or = 3 months, the ADRA1A genotype at position 1475 of the coding region was determined. The patients' short-term response to treatment was determined for four outcome measures, i.e. the International Prostate Symptom Score (IPSS), the IPSS quality-of-life score, peak urinary flow rate, and obstruction grade, stratified by genotype. Eventual BPH-related invasive therapy was used as the outcome for assessing the long-term response to treatment. Genetic variants at positions 834, 896, 898 and 1831 were too rare to be considered in the analysis. RESULTS There were no significant differences for the genotype strata in three of the four outcome measures. Patients with the CC genotype responded significantly better in quality-of-life perception than patients with the CT or TT genotype. There were also no significant differences in the risk of BPH-related invasive therapy among the three genotypes. CONCLUSIONS The 1475C-->T SNP in the ADRA1A gene does not modify the short- and long-term efficacy of alpha(1)-adrenoceptor antagonists for treating BPH. There was a small effect on perceived quality of life but this was not reflected in other variables that measured the treatment response more directly.

Comparison of two alpha1-adrenoceptor antagonists, naftopidil and tamsulosin hydrochloride, in the treatment of lower urinary tract symptoms with benign prostatic hyperplasia: a randomized crossover study

OBJECTIVES

To compare the efficacy of two alpha(1)-adrenoceptor antagonists, alpha(1A)-adrenoceptor-selective tamsulosin hydrochloride and alpha(1D)-adrenoceptor-selective naftopidil, in the treatment of lower urinary tract symptoms (LUTS) with benign prostatic hyperplasia (BPH).

PATIENTS AND METHODS

Thirty-four patients (mean age 72.4 years, sd 4.3, range 66-79) with LUTS (International Prostate Symptom Score, IPSS >8) secondary to BPH were enrolled in a randomized crossover study. Seventeen patients were initially prescribed naftopidil 50 mg for 4 weeks, followed by tamsulosin 0.2 mg for 4 weeks (group A); another 17 were initially prescribed tamsulosin 0.2 mg, followed by naftopidil 50 mg (group B). Patients changed to the alternative treatment after a 1-week washout period. Efficacy criteria were improvement in LUTS (IPSS), quality of life (QoL), uroflowmetry, and pressure-flow study (PFS) values based on the treatment with each agent.

RESULTS

At baseline there were no significant differences between the groups in IPSS, QoL, uroflowmetry values or PFS values, except for the volume at maximum desire to void. After treatment with each agent, the IPSS and QoL were significantly improved and the reduction in bladder outlet obstruction confirmed by PFS. Naftopidil was significantly more effective than tamsulosin in relieving nocturia. The increases from baseline (before treatment) to the endpoint (after treatment with each agent) in the volume at first desire and maximum desire to void were significantly higher with naftopidil than with tamsulosin. Involuntary contractions disappeared in two patients with relief of nocturia with naftopidil, but not with tamsulosin. The decrease in other symptoms of the IPSS, QoL, increase in uroflowmetry values and changes in other PFS values were similar for both agents.

CONCLUSIONS

The two agents provided similar efficacy in the treatment of LUTS with BPH. However, naftopidil was better than tamsulosin for nocturia. The disappearance of involuntary contraction and the greater increase in first-desire volume with naftopidil may be associated with the relief of nocturia. The alpha(1D)-adrenoceptor antagonist is effective in alleviating both voiding and storage symptoms. The alpha(1D)-adrenoceptor antagonist may be more effective than the alpha(1A)-adrenoceptor antagonist in LUTS with BPH.

Effects of Selective Alpha-1-Adrenergic Receptor Blockers on Bladder Weight

INTRODUCTION

This study was undertaken to investigate the effects of two different alpha(1)-adrenergic blockers on bladder hypertrophy using ultrasound-estimated bladder weight (UEBW) and to assess the relation between changes in UEBW and other objective and subjective parameters of disease severity in patients with benign prostatic hyperplasia (BPH).

MATERIALS AND METHODS

41 men were enrolled in the study and they were subjected to either watchful waiting (group 1) or alpha(1)-adrenergic receptor blocker therapy (group 2 with alfuzosin; group 3 with tamsulosin). The patients were investigated by symptom evaluation using the International Prostate Symptom Score (IPSS) and quality of life score (QOL), uroflowmetry and UEBW. The parameters were assessed again 3 months after initiation of treatment and compared with the initial values.

RESULTS

While the mean UEBW increased in group 1 (42.2 +/- 10.3 to 52.5 +/- 12.2 g), it decreased in both the other groups that received alpha-blocker therapy (61.3 +/- 18.7 to 41.1 +/- 13.2 and 59.4 +/- 17.2 to 43.5 +/- 17.6 g, respectively). In groups 2 and 3, the mean UEBW, post-void residual urine, IPSS and QOL values decreased, and the mean maximum flow rate increased. All of the changes in group 2 and all except QOL in group 3 were statistically significant (p < 0.05). The changes correlated well with each other with regard to treatment success. The highest decreases in UEBW were encountered in patients with heavier bladders.

CONCLUSIONS

UEBW decreases with alpha(1)-adrenergic receptor blockers. When used together with the other objective and subjective parameters, UEBW is a promising quantitative parameter as a follow-up tool and can be useful in monitoring the therapeutic effects of alpha(1)-adrenergic receptor blockers.

Combined use of alpha-adrenergic and muscarinic antagonists for the treatment of voiding dysfunction

PURPOSE

We provide an overview of the medical literature supporting the combined use of muscarinic and alpha-adrenergic antagonist therapy for the treatment of voiding dysfunction.

MATERIALS AND METHODS

The MEDLINE database (1966 to 2004) of the United States National Library of Medicine was searched for pertinent studies.

RESULTS

Although the mechanism of action of alpha-adrenergic antagonist therapy for voiding dysfunction has traditionally been assumed to be relaxation of the periurethral, prostatic and bladder neck smooth muscle, substantial evidence supports action at extraprostatic sites involved in micturition, including the bladder dome smooth muscle, peripheral ganglia, spinal cord and brain. Likewise the mechanism of action of anticholinergic therapy has been traditionally assumed to be inhibition of the M3 muscarinic receptor subtypes that mediate normal bladder contractions. However, M2 receptor mediates hypertrophied bladder contractions and there is evidence for an M2 component to the suprasacral control of voiding.

CONCLUSIONS

Based on the physiology of alpha-adrenergic and muscarinic receptors the inhibition of each one would be expected to be more beneficial than that of either alone because they would work on 2 components of detrusor function. Patients who would likely benefit from this combination therapy are men with lower urinary tract symptoms, women with urgency/frequency syndrome (overactive bladder), patients with uninhibited bladder contractions due to neurogenic bladder, and patients with pelvic pain and voiding symptoms, ie interstitial cystitis and chronic prostatitis/chronic pelvic pain syndrome.

Comparison of tamsulosin and naftopidil for efficacy and safety in the treatment of benign prostatic hyperplasia: a randomized controlled trial

OBJECTIVES

To compare the efficacy and safety of two alpha1a/alpha1d adrenoceptor (AR) antagonists with different affinity for the alpha1AR subtypes, tamsulosin and naftopidil, in the treatment of benign prostatic hyperplasia (BPH).

PATIENTS AND METHODS

Patients with BPH were randomized to receive either tamsulosin or naftopidil. The primary efficacy variables were the changes in the total International Prostate Symptom Score (IPSS), maximum flow rate on free uroflowmetry, and residual urine volume. The secondary efficacy variables were average flow rate, changes in the IPSS storage score, IPSS voiding score, and quality-of-life (QoL) Index score, from baseline to endpoint (12 weeks). Data on all randomized patients were included in the safety analyses for adverse effects and changes in blood pressure.

RESULTS

Of the 185 patients enrolled data for 144 who were eligible for inclusion in the efficacy analysis were analysed (75 from the tamsulosin and 69 from the naftopidil group). There was no significant difference in any variable at baseline between the groups. There were statistically significant improvements for all primary and secondary variables in both groups, except for residual urine in the tamsulosin group. However, there was no significant intergroup difference in the improvement of any efficacy variable between the groups. The adverse effects were comparable, with no significant differences in systolic and diastolic blood pressure after treatment in both groups.

CONCLUSIONS

This study suggests that naftopidil is as effective and safe as tamsulosin. Both drugs were effective in improving storage and voiding symptoms. However, there was no difference in clinical efficacy or adverse effects between the alpha1 AR antagonists with different affinity to alpha1 subtypes, alpha1a and alpha1d.

Single-blind, randomized controlled study of the clinical and urodynamic effects of an alpha-blocker (naftopidil) and phytotherapy (eviprostat) in the treatment of benign prostatic hyperplasia

AIM

The aim of our study was to examine the efficacy of naftopidil in terms of the international prostate symptom score (IPSS) and urodynamic parameters in the treatment of benign prostatic hyperplasia (BPH). Eviprostat was used as a control to study the efficacy of naftopidil.

METHODS

Forty-nine patients with BPH (mean age 67.9 +/- 7.8 years) were involved in the study. Patients were randomly assigned either to the naftopidil group, which was treated with the alpha-blocker naftopidil (50-75 mg daily, 36 patients), or the eviprostat group, which was treated with phytotherapy (six tablets of eviprostat daily, 13 patients).

RESULTS

The mean total IPSS, the total storage and voiding symptom scores, and the quality of life score decreased significantly (P < 0.0001 for each variable) in the naftopidil group, but not in the eviprostat group. In the naftopidil group, analyses showed significant increases in average and maximum flow rate and bladder capacity at first desire to void (P < 0.001, P = 0.001 and P = 0.024, respectively), and significant decreases in the postvoid residual, the percent of residual and the Abrams-Griffiths number (P = 0.009, P = 0.008 and P = 0.042, respectively). However, in the eviprostat group, no significant changes were noted in terms of these symptomatic and urodynamic parameters. In the pressure/flow study, an improvement in the International Continence Society nomogram grade was noted in 29% of the naftopidil group, but in only 16% of the eviprostat group. Among the 14 patients in the naftopidil group, detrusor overactivity disappeared in 21% and cystometric capacity increased in 36%, but no improvement in detrusor overactivity was noted in the eviprostat group.

CONCLUSIONS

Naftopidil appears to have been effective in this short-term treatment of BPH.

Noradrenaline inhibits autonomous activity in the isolated guinea pig bladder

OBJECTIVE

To investigate the actions of noradrenaline and the specific alpha-adrenergic agonists cirazoline (alpha1) and UK14304 (alpha2), and beta-receptor agonists formoterol (beta2) and BRL37344 (beta3) on the phasic activity induced by muscarinic stimulation on the isolated guinea pig bladder, as the physiological significance of this activity is unknown but it may underlie non-micturition contractions (NMCs, which can be inhibited by sympathetic nerve stimulation) and the generation of bladder sensations.

MATERIALS AND METHODS

All experiments were conducted using whole isolated bladders from female guinea pigs (270-300 g). Bladders were cannulated via the urethra and suspended in a heated chamber containing oxygenated Tyrode's solution at 33-35 degrees C and the intravesical pressure recorded. All drugs were added to the solution bathing the abluminal surface.

RESULTS

Exposure to noradrenaline reduced the amplitude and frequency of the phasic activity. When noradrenaline was washed off there was a transient increase in frequency. There was marked desensitization with repeated applications of noradrenaline. Applying the specific beta3-agonist BRL37344 reduced the amplitude of the phasic activity while formoterol, a specific beta2-agonist, had no effect. Cirazoline, a specific alpha1-agonist, reduced the amplitude of the responses and significantly reduced the frequency of the phasic activity. UK14304, a specific alpha2-agonist, had no effect. Stimulation of the hypogastric nerve to the guinea pig bladder generates contractions. Prolonged nerve stimulation at low frequency (6.5 Hz) generated phasic rises in intravesical pressure which were inhibited by noradrenaline. Using short (5 s) periods of stimulation noradrenaline inhibited nerve-mediated contractions at all frequencies but was more effective at <10 Hz.

CONCLUSION

These experiments show that sympathomimetic stimulation in the isolated whole bladder results primarily in an inhibition of phasic activity, but also a stimulation. Two receptor subtypes appear to be involved in the inhibition, alpha1 and beta3, suggesting that there may be many sites of action. These results are discussed in terms of the possible physiological significance of phasic activity and the potential importance of its inhibition, in the context of the causes of pathological changes in the bladder, particularly those associated with bladder overactivity, and the pharmacological approach to the alleviation of clinical symptoms.

Increased adrenergic contractility and decreased mRNA expression of NOS III in aging rat urinary bladders

Our objective was to study age-related changes in adrenergic contractility and gene expression profile in the rat urinary bladder. Young (3-month old), adult (10-month old) and senescent (30-month old) male WAG/Rij rats were used. Gene expression profile in the rat urinary bladder was defined using Atlas microarray technology. In vitro contractile responses induced by KCl, phenylephrine (PHE) and norepinephrine (NE) were compared in isolated urinary bladders dissected from young, adult and senescent rats. Among a total of 1176 genes present on the arrays, 15 genes showed an increase in expression and 10 genes a decrease with age. Four genes related to nerve growth factor were upregulated whereas NOS type III was downregulated in aging rats. Intrinsic contractility of isolated rat urinary bladders was not changed between adult and aging rats as judged by the response curves to KCl. In contrast, an age-related increase in the maximal contractile responses to NE, but not PHE, was noticed (13 +/- 1, 48 +/- 2% and 59 +/- 2% at 3, 10 and 30 months, respectively). The alpha1D-adrenoceptor antagonist BMY7378 antagonized NE-induced contractions with low potency in both groups suggesting the involvement of the alpha1A-adrenoceptor subtype. This was confirmed by microarray, which demonstrated mRNA expression for the alpha1A-adrenoceptor subtype only. These results suggest that aging of the urinary bladder is associated with an increase in the maximal contractile response to NE which could be due to NO shortage resulting from downregulation of urothelial NOS III.

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.

Smooth muscle and parasympathetic nerve terminals in the rat urinary bladder have different subtypes of alpha(1) adrenoceptors

Neurally evoked contractions and release of (3)H- acetylcholine (ACh) during electrical field stimulation were measured in rat urinary bladder strips. The alpha(1) agonist phenylephrine (PE, 2-8 microM) increased the amplitude of neurally evoked contractions, facilitated the release of ACh and increased the baseline tone of the bladder strips. The PE-induced facilitation of the contractions did not significantly change during a prolonged exposure to PE (120 min), whereas the PE-induced rise in baseline tone gradually decreased to 65% of the initial value. Low concentrations of specific alpha(1A) antagonists, 5-methyl urapidil (5-MU), REC15/2739 and WB-4101 competitively inhibited the facilitation of the neurally-evoked contractions (pA(2:) 8.77; 9.59 and 9.62, respectively), whereas higher concentrations of 5-MU (IC(50): 48 nM) were required to suppress the PE-rise in baseline. WB-4101 (100 microM) inhibited the PE-induced facilitation of ACh release. The irreversible alpha(1B) antagonist chloroethyl-clonidine (CEC, 10-50 microM) inhibited the PE-evoked rise in base line tone, but did not affect the PE-induced facilitation of the neurally evoked contractions nor the facilitation of ACh release. However, CEC increased the area and amplitude of the neurally-evoked contractions by 261+/-33 and 47.2+/-8.4%, respectively. Atropine significantly inhibited the CEC evoked increase in area and amplitude of the electrically evoked contractions (76.5+/-4.8 and 40.8+/-3%, respectively) indicating that CEC facilitated the cholinergic responses of the electrically stimulated bladder strips. It is concluded that alpha(1A) and CEC sensitive alpha(1B) and/or alpha(1D) adrenoceptors are expressed in the rat bladder in different locations. On the cholinergic nerve terminals alpha(1A) adrenoceptors mediate prejunctional facilitation, whereas postjunctional alpha(1B)/alpha(1D) adrenoceptors mediate smooth muscle contraction.