Beta3-adrenoceptors in human detrusor muscle

Inheritance patterns of lower urinary tract symptoms in adults: a systematic review

OBJECTIVE

To compile and evaluate the heritability and inheritance patterns of lower urinary tract symptoms (LUTS) in adult cohorts.

METHODS

Searches of five databases (PubMed, Embase, APA PsycInfo, Global Health, and OVID Medline) commenced on 6 July 2024, resulting in 736 articles retrieved after deduplication. Studies evaluating heritability patterns, gene frequencies, and familial aggregation of symptoms were included for review. Screening and predefined eligibility criteria produced 34 studies for final review. A descriptive analysis of synthesised data was performed, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The Cochrane Risk of Bias in Non-Randomised Studies of Interventions (ROBINS-I) tool and the Johanna Briggs Institute checklist were used to evaluate these studies.

RESULTS

Ten of the 34 studies (29%) described general LUTS, 14 (41%) described symptoms due to benign prostatic enlargement (BPE), nine (26%) described urinary incontinence (UI; urge UI [UUI], stress UI [SUI] and mixed UI [MUI]), four (12%) described nocturia alone, two (6%) described overactive bladder (OAB), and four (13%) described other specific symptoms (frequency, postvoid residual urine volume). BPE symptoms, UI (MUI and UUI), nocturia alone, and frequency alone were associated with genetic predisposition, whilst OAB and SUI had more modest inheritance.

CONCLUSION

The pathogenetic and pharmacological mechanisms fundamental to LUTS manifestation are highly heterogeneous. Further work is required to evaluate the inheritance patterns of LUTS more extensively.

Update on Overactive Bladder Therapeutic Options

BACKGROUND

Millions of Americans are burdened by overactive bladder (OAB) syndrome and the psychogenic and economic hardships that accompany it. Several theories attempt to explain OAB as a neurogenic dysfunction, myogenic dysfunction, urothelial dysfunction, or decreased expression of a channel protein secondary to bladder outlet obstruction. Given that the etiology of OAB is a working theory, the management of OAB is also an evolving subject matter in medicine. There are uncertainties surrounding the pathophysiology of OAB, the strength of a clinical diagnosis, and accurate reporting because of the disease's stigma and decreased use of health care.

DATA SOURCES

This is a narrative review that used PubMed, Google Scholar, Medline, and ScienceDirect to review literature on current and future OAB therapies.

RESULTS

Currently, first-line treatment for OAB is behavioral therapy that uses lifestyle modifications, bladder-control techniques, and psychotherapy. Second-line therapy includes antimuscarinic agents or beta 3 adrenergic agonists, and studies have shown that combination therapy with antimuscarinics and beta 3 adrenergic agonists provides even greater efficacy than monotherapy. Third-line therapies discussed include onabotulinumtoxinA, posterior tibial nerve stimulation, and sacral neuromodulation. OnabotulinumtoxinA has been FDA-approved as a nonpharmaceutical treatment option for refractory OAB with minimal side effects restricted to the urinary tract. Posterior tibial nerve modulation and sacral neuromodulation are successful in treating refractory OAB, but the costs and complication rates make them high-risk procedures. Therefore, surgical intervention should be a last resort. Estrogen therapy is effective in alleviating urinary incontinence in postmenopausal women, consistent with the association between estrogen deficiency and genitourinary syndrome. Potassium channel activators, voltage-gated calcium channel blockers, and phosphodiesterase inhibitors look to be promising options for the future of OAB management. As new therapies are developed, individuals with OAB can better personalize their treatment to maximize their quality of life and cost-effective care.

Therapeutic effectiveness and adverse drug reactions of mirabegron versus solifenacin in the treatment of overactive bladder syndrome

Introduction

Overactive bladder (OAB) syndrome is a chronic disease characterized by urinary urgency with or without urge incontinence, frequency, and nocturia and antimuscarinic drugs such as solifenacin have been the mainstay of treatment. Mirabegron a beta 3 adrenoreceptor agonist has recently gained importance in the management of OAB. The rationale of the study is that mirabegron improves the storage function without affecting voiding which increases the therapeutic effectiveness. The objective was to determine the therapeutic effectiveness of mirabegron versus solifenacin.

Methods

A prospective observational study was conducted on 298 patients with OAB syndrome attending the urology outpatient department of government medical college after obtaining institutional review board clearance. Patients of both genders, belonging to the 18-65 years of age group, attending the urology outpatient department were selected for the study. Patients were evaluated using the OAB-validated 8-question awareness tool (OAB-V8 score) before and after receiving drugs by direct questionnaire method after receiving informed consent. Patients were prescribed either solifenacin 5 mg or mirabegron 25 mg once daily by the urologist. Follow-up was done after 4 and 12 weeks. Adverse drug reactions of the drugs were assessed using the Central Drug Standard Control Organization suspected adverse reaction (ADR) form, and ADRs were notified to the nearest ADR monitoring center.

Results

The mirabegron group showed maximum improvement in the mean OAB-V8 score values from baseline at 4 weeks (12.82 ± 5.86, P < 0.001) and 12 weeks (5.74 ± 3.31, P < 0.001) when compared to solifenacin. OAB-V8 scores of the solifenacin group also showed significant improvement from the baseline at 4 weeks (15.30 ± 5.54, P < 0.001) and 12 weeks (8.05 ± 4.59, P < 0.001). Heart rate, systolic, and diastolic blood pressures did not show significant changes during the follow-up in both the study groups. Thirteen patients developed ADRs such as dry mouth (four patients) and constipation (nine patients) in the solifenacin group. No ADRs were noted in the mirabegron group.

Conclusion

Mirabegron showed maximum improvement in the OAB-V8 scores in patients with OAB syndrome, although the solifenacin group also showed improvement. Adverse effects were less in the mirabegron group when compared to the solifenacin group.

Medicinal plants and natural products for treating overactive bladder

BACKGROUND

Overactive bladder (OAB) presents a high prevalence of 16-18% worldwide. The pathophysiology of OAB is still poorly understood while effective therapy or countermeasure are very limited. On the other hand, medicinal plants and herbal remedies have been utilized for treating lower urinary tract symptoms (LUTS) in both Eastern and Western cultures since ancient times. In recent years, accumulating progress has also been made in OAB treatment research by using medicinal plants.

METHODS

Relevant literature on the studies of medicinal plants and herbs used to treat OAB was reviewed. The medicinal plants were summarized and categorized into two groups, single-herb medications and herbal formulations.

RESULTS

The present review has summarized current understanding of OAB's pathophysiology, its available treatments and new drug targets. Medicinal plants and natural products which have been used or have shown potential for OAB treatment were updated and comprehensively categorized. Studies on a wide variety of medicinal plants showed promising results, although only a few phytochemicals have been isolated and identified. Until now, none of these herbal compounds have been further developed into clinical therapeutics for OAB.

CONCLUSIONS

This review provides the basis for discovering and designing new phytopharmaceutical candidates with effective and well-tolerated properties to treat OAB. Increasing evidences indicate new strategies with alternative herbal treatment for OAB have high efficacy and safety, showing great promise for their clinical use. Future studies in a rigorously designed controlled manner will be beneficial to further support the eligibility of herbal treatment as OAB therapeutics.

Comparison of mirabegron and vibegron for clinical efficacy and safety in female patients with overactive bladder: a multicenter prospective randomized crossover trial

PURPOSE

To compare the efficacy and safety of mirabegron and vibegron in female OAB patients.

METHODS

We conducted a multicenter, prospective, randomized crossover study of female patients with OAB. The patients were assigned to Group MV (mirabegron for 8 weeks, followed by vibegron for 8 weeks) or group VM (vibegron for 8 weeks, followed by mirabegron for 8 weeks). The primary endpoint was the change in OABSS from baseline, and the secondary endpoint was the change in FVC parameters. After completion of the study, each patient was asked which drug was preferable.

RESULTS

A total of 83 patients were enrolled (40 and 43 in groups MV and VM, respectively). At 8th and 16th week, 33 and 29 in Group MV and 34 and 27 in Group VM continued to receive the treatment. The change in PVR was not significantly different between treatment with mirabegron and vibegron. The changes in OABSS, nighttime frequency, mean, and maximum voided volume were similar between mirabegron and vibegron. The mean change in the daytime frequency was greater in the vibegron than in the mirabegron. Of the 56 patients, 15 (27%) and 30 (53%) preferred mirabegron and vibegron, respectively. The remaining 11 patients (20%) showed no preference. The change in the urgency incontinence score during vibegron was better in patients who preferred vibegron to mirabegron.

CONCLUSION

The efficacies of mirabegron and vibegron in female patients was similar. The patients' preference for vibegron could depend on the efficacy of vibegron for urgency incontinence.

Inside the Biology of the β3-Adrenoceptor

Since the first discovery in 1989, the β3-adrenoceptor (β3-AR) has gained great attention because it showed the ability to regulate many physiologic and metabolic activities, such as thermogenesis and lipolysis in brown and white adipose tissue, respectively (BAT, WAT), negative inotropic effects in cardiomyocytes, and relaxation of the blood vessels and the urinary bladder. The β3-AR has been suggested as a potential target for cancer treatment, both in adult and pediatric tumors, since under hypoxia its upregulation in the tumor microenvironment (TME) regulates stromal cell differentiation, tumor growth and metastases, signifying that its agonism/antagonism could be useful for clinical benefits. Promising results in cancer research have proposed the β3-AR being targeted for the treatment of many conditions, with some drugs, at present, undergoing phase II and III clinical trials. In this review, we report the scientific journey followed by the research from the β3-Ars' discovery, with focus on the β3-Ars' role in cancer initiation and progression that elects it an intriguing target for novel antineoplastic approaches. The overview highlights the great potential of the β3-AR, both in physiologic and pathologic conditions, with the intention to display the possible benefits of β3-AR modulation in cancer reality.

Urinary beta 3-adrenoceptor as a diagnostic biomarker for overactive bladder in women

This study was to investigate urinary beta 3-adrenoceptor concentration as a biomarker for overactive bladder (OAB) and predictor of treatment outcomes in women receiving the beta 3-adrenoceptor agonist mirabegron. The study comprised 50 women identified with OAB and 35 women considered as healthy controls. All women with OAB received daily dosage of 50 mg of mirabegron for 12 weeks. Bladder diaries, OAB-related questionnaires, and global response assessment scale (GRAS) data were collected. Urinary beta 3-adrenoceptor concentration was measured through enzyme-linked immunosorbent assay. All OAB-related questionnaires and GRAS indicated improved posttreatment urinary health. After mirabegron treatment, the frequency of micturition and urgency episodes decreased, but the urinary beta 3-adrenoceptor/creatinine (Cr) ratio increased. The urinary beta 3-adrenoceptor/creatinine ratio was identified as a sensitive biomarker for OAB with a confidence interval of 0.656 to 0.856 (p < 0.001). A negative correlation (- 0.431, p = 0.040) between this biomarker and health-related quality of life (HRQL) scores. The Beta 3-adrenoceptor/Cr levels increased significantly in the treatment-responsive group, while they remained unchanged in the unsatisfactory outcome group. This study shows that 12 weeks of mirabegron treatment improves OAB symptoms and HRQL. Furthermore, urinary beta 3-adrenoceptor concentration may be a diagnostic biomarker for OAB.

Overview of current pharmacotherapeutic options in benign prostatic hyperplasia

INTRODUCTION

Benign prostatic hyperplasia (BPH) represents the histological entity of prostate cell proliferation, which inflicts a gradually increasing obstruction of the bladder outlet and is accompanied by a progressing manifestation of lower urinary tract symptoms (LUTS). BPH management algorithm includes conservative measures, pharmaceutical agents, and surgical procedures.

AREAS COVERED

A comprehensive literature review was performed using PubMed, Scopus, and Google Scholar databases to identify publications written in English, analyzing BPH pharmaceutical treatment. The search was conducted from January 2000 to January 2023. Six main drug classes can be administered, either as monotherapy or in combination. Furthermore, the authors provide current direction of research on future medications, which focuses on a more etiological interference to the BPH pathophysiological mechanism.

EXPERT OPINION

The available medications represent an effective first-line step of BPH/LUTS therapy. Currently, the administration of BPH medications is tailored to patient/disease characteristics and entails long-time adherence to therapy. The emergence of new surgical modalities, which combine significantly lower morbidity compared to standard procedures and more durable effects than the available medications, seems to challenge the current treatment algorithm. More direct comparisons and the increasing experience with these surgical modalities will delineate the switch points between various therapy levels along the BPH management sequence.

Inhibition of prejunctional parasympathetic pathways by β3-adrenoceptor agonists in the isolated pig detrusor: comparison with human detrusor studies

Adrenergic receptors of the β₃-subtype (β₃-ADRs) seem to represent a new target for a more effective pharmacological treatment of overactive bladder (OAB), a wide spread urinary disorder. A promising opportunity for OAB therapy might rely on the development of selective β₃-ADR agonists, but an appropriate preclinical screening, as well as investigation of their pharmacological mechanism(s), is limited by poor availability of human bladder samples and of translational animal models. In this study, we used the porcine urinary bladder as experimental tool to ascertain the functions of β₃-ADRs in the control the parasympathetic motor drive. Tritiated acetylcholine ([³H]-ACh), mainly originated from neural stores, was released by electrical field stimulation (EFS) in epithelium-deprived detrusor strips from pigs bred without estrogens. EFS produced simultaneously [³H]-ACh release and smooth muscle contraction allowing to asses neural (pre-junctional) and myogenic (postjunctional) effects in the same experiment. Isoprenaline and mirabegron produced on the EFS-evoked effects a concentration-dependent inhibition antagonized by L-748,337, a high selective β₃-ADR antagonist. The analysis of the resultant pharmacodynamic parameters supports the notion that in pig detrusors, as well as in previously described human detrusors, the activation of inhibitory β₃-ADRs can modulate neural parasympathetic pathways. In such inhibitory control, the involvement of membrane K⁺ channels, mainly of the SK type, seems to play a pivotal role similarly to what previously described in humans. Therefore, the isolated porcine detrusor can provide a suitable experimental tool to study the mechanisms underlying the clinical efficacy of selective β₃-ADR compounds for human use.

Molecular Mechanisms of Neurogenic Lower Urinary Tract Dysfunction after Spinal Cord Injury

This article provides a synopsis of current progress made in fundamental studies of lower urinary tract dysfunction (LUTD) after spinal cord injury (SCI) above the sacral level. Animal models of SCI allowed us to examine the effects of SCI on the micturition control and the underlying neurophysiological processes of SCI-induced LUTD. Urine storage and elimination are the two primary functions of the LUT, which are governed by complicated regulatory mechanisms in the central and peripheral nervous systems. These neural systems control the action of two functional units in the LUT: the urinary bladder and an outlet consisting of the bladder neck, urethral sphincters, and pelvic-floor striated muscles. During the storage phase, the outlet is closed, and the bladder is inactive to maintain a low intravenous pressure and continence. In contrast, during the voiding phase, the outlet relaxes, and the bladder contracts to facilitate adequate urine flow and bladder emptying. SCI disrupts the normal reflex circuits that regulate co-ordinated bladder and urethral sphincter function, leading to involuntary and inefficient voiding. Following SCI, a spinal micturition reflex pathway develops to induce an overactive bladder condition following the initial areflexic phase. In addition, without proper bladder-urethral-sphincter coordination after SCI, the bladder is not emptied as effectively as in the normal condition. Previous studies using animal models of SCI have shown that hyperexcitability of C-fiber bladder afferent pathways is a fundamental pathophysiological mechanism, inducing neurogenic LUTD, especially detrusor overactivity during the storage phase. SCI also induces neurogenic LUTD during the voiding phase, known as detrusor sphincter dyssynergia, likely due to hyperexcitability of Aδ-fiber bladder afferent pathways rather than C-fiber afferents. The molecular mechanisms underlying SCI-induced LUTD are multifactorial; previous studies have identified significant changes in the expression of various molecules in the peripheral organs and afferent nerves projecting to the spinal cord, including growth factors, ion channels, receptors and neurotransmitters. These findings in animal models of SCI and neurogenic LUTD should increase our understanding of pathophysiological mechanisms of LUTD after SCI for the future development of novel therapies for SCI patients with LUTD.

Mechanism of traditional Chinese medicine in treating overactive bladder

Overactive bladder syndrome (OAB) has made increasing progress in mechanism and treatment research. Traditional Chinese medicine (TCM) is a common complementary therapy for OAB, and it has been found to be effective. However, the intervention mechanism of TCM in the treatment of OAB is still unclear. The aim of this review is to consolidate the current knowledge about the mechanism of TCM: acupuncture, moxibustion, herbs in treating OAB, and the animal models of OAB commonly used in TCM. Finally, we put forward the dilemma of TCM treatment of OAB and discussed the insufficiency and future direction of TCM treatment of OAB.

The β3 adrenoceptor in proliferative retinopathies: "Cinderella" steps out of its family shadow

In the retina, hypoxic condition leads to overgrowing leaky vessels resulting in altered metabolic supply that may cause impaired visual function. Hypoxia-inducible factor-1 (HIF-1) is a central regulator of the retinal response to hypoxia by activating the transcription of numerous target genes, including vascular endothelium growth factor, which acts as a major player in retinal angiogenesis. In the present review, oxygen urge by the retina and its oxygen sensing systems including HIF-1 are discussed in respect to the role of the beta-adrenergic receptors (β-ARs) and their pharmacologic manipulation in the vascular response to hypoxia. In the β-AR family, β1- and β2-AR have long been attracting attention because their pharmacology is intensely used for human health, while β3-AR, the third and last cloned receptor is no longer increasingly emerging as an attractive target for drug discovery. Here, β3-AR, a main character in several organs including the heart, the adipose tissue and the urinary bladder, but so far a supporting actor in the retina, has been thoroughly examined in respect to its function in retinal response to hypoxia. In particular, its oxygen dependence has been taken as a key indicator of β3-AR involvement in HIF-1-mediated responses to oxygen. Hence, the possibility of β3-AR transcription by HIF-1 has been discussed from early circumstantial evidence to the recent demonstration that β3-AR acts as a novel HIF-1 target gene by playing like a putative intermediary between oxygen levels and retinal vessel proliferation. Thus, targeting β3-AR may implement the therapeutic armamentarium against neovascular pathologies of the eye.

Vibegron for the treatment of overactive bladder: a comprehensive update

INTRODUCTION

: Overactive bladder (OAB) is associated with physical, emotional and financial burden. After failed conservative measures, second-line therapy includes medications, such as antimuscarinics and beta-3 adrenergic receptor (β3AR) agonists. Antimuscarinics are most commonly prescribed but have systemic side effects that lead to poor compliance. β3AR agonists include mirabegron and vibegron. Mirabegron is a first generation β3AR agonist that has shown to be effective for frequency, urgency urinary incontinence (UUI) and urgency, but has interactions with cytochrome P450 enzymes (CYPs) and cardiovascular sequelae. Vibegron is a second generation β3AR agonist that is highly selective and does not interact with CYPs. It has shown to be very effective for reducing UUI episodes and daily micturition number and has a favorable side effect profile.

AREAS COVERED

: Clinical background, pharmacology, and clinical studies for vibegron.Expert opinion: Vibegron is a welcomed addition to the OAB therapeutic landscape. This single dose, once daily option is effective, especially for patients with wet OAB, with a favorable side effect profile. Sub-analyses of patients ≥ 65 years have shown continued efficacy and safety. The few drug interactions are of benefit, especially for older patients with polypharmacy. As long-term data accrues, vibegron has the potential to drive the OAB therapeutic market.

β3 Relaxant Effect in Human Bladder Involves Cystathionine γ-Lyase-Derived Urothelial Hydrogen Sulfide

It is now well established that the urothelium does not act as a passive barrier but contributes to bladder homeostasis by releasing several signaling molecules in response to physiological and chemical stimuli. Here, we investigated the potential contribution of the hydrogen sulfide (H2S) pathway in regulating human urothelium function in β3 adrenoceptor-mediated relaxation. The relaxant effect of BRL 37344 (0.1–300 µM), a selective β3 adrenoceptor agonist, was evaluated in isolated human bladder strips in the presence or absence of the urothelium. The relaxant effect of BRL 37344 was significantly reduced by urothelium removal. The inhibition of cystathionine-γ-lyase (CSE), but not cystathionine-β-synthase (CBS), significantly reduced the BRL 37344 relaxing effect to the same extent as that given by urothelium removal, suggesting a role for CSE-derived H2S. β3 adrenoceptor stimulation in the human urothelium or in T24 urothelial cells markedly increased H2S and cAMP levels that were reverted by a blockade of CSE and β3 adrenoceptor antagonism. These findings demonstrate a key role for urothelium CSE-derived H2S in the β3 effect on the human bladder through the modulation of cAMP levels. Therefore, the study establishes the relevance of urothelial β3 adrenoceptors in the regulation of bladder tone, supporting the use of β3 agonists in patients affected by an overactive bladder.

Association Between Trp64Arg Polymorphism of Beta-3 Adrenergic Receptor Gene and Susceptibility to Overactive Bladder: A Meta-Analysis

Objective: Some studies have been carried out to investigate the association between Trp64Arg polymorphism in beta-3 adrenergic receptor gene (ADRB3) and susceptibility to overactive bladder (OAB), but the results remain inconsistent. We carried out a meta-analysis to acquire a more accurate estimation.

Methods: All eligible studies were searched in PubMed, Web of Science, Embase, and Cochrane Library. Pooled odds ratios, with 95% confidence intervals, were assessed for the association using fixed and random effects models.

Results: The overall results of this meta-analysis demonstrated that there might be an association between Trp64Arg polymorphism and susceptibility to OAB in allele model, dominant model, and heterozygote comparison with a relative risk of 2.00 (95% CI 1.36–2.93), 2.13 (95% CI 1.20–3.76), and 2.07 (95% CI: 1.13–3.79), respectively. However, in the recessive model and homozygote comparison, no significant association between ESR1 Trp64Arg polymorphism and susceptibility to OAB was observed, with a relative risk of 2.47 (95% CI 0.63–9.73) and 3.12 (95% CI: 0.79–12.35), respectively. Based on trail sequential analysis, the results turned out to be true positive in the allele model, false positive in the dominant model and heterozygote comparison, and negative in the recessive model and homozygote comparison, respectively.

Conclusion: Our analysis indicated that Trp64Arg polymorphisms in ADRB3 might increase the risk of OAB twice in the allele model, but further well-designed studies with large sample sizes are required to confirm the present findings in other modes and comparisons.

Vibegron inhibits enhanced spontaneous contractions induced by anoxia/reoxygenation in isolated whole bladder from rats

It has been recently proposed that repeated bladder ischemia/reperfusion induced by chronic pelvic ischemia may lead to detrusor overactivity, followed by lower urinary tract symptoms. Vibegron is a selective β₃-adrenoceptor agonist approved for the treatment of overactive bladder. Several studies have tested β₃-adrenoceptor agonists using animal models with detrusor overactivity related to bladder ischemia/reperfusion. However, whether β₃-adrenoceptor agonists directly affect ischemia/reperfusion-evoked detrusor overactivity is unclear. Therefore, we examined whether bladder anoxia/reoxygenation could enhance spontaneous bladder contractions (SBCs) and investigated the effect of vibegron on enhanced SBCs. Isolated whole bladders from rats were incubated with Krebs solution aerated with 95% N₂ + 5% CO₂ for 5 h (anoxia). Subsequently, the bathing solution was replaced with an oxygen-saturated solution (reoxygenation). Anoxia/reoxygenation caused enhancement of the amplitude but not the frequency of SBC compared with that before reoxygenation. Vibegron (0.3-30 μM) inhibited this increase in SBC amplitude, but not the frequency, in a dose-dependent manner. The inhibitory effect of vibegron was not affected by pretreatment with the adenylyl cyclase inhibitor SQ22536 (100 μM) or protein kinase A inhibitor KT5720 (1 μM) and was not accompanied by considerable changes in cyclic adenosine monophosphate (cAMP) content in the bladder. In contrast, the large conductance potassium channel inhibitor iberiotoxin (100 nM) suppressed the inhibitory effect of vibegron. These results suggest that bladder ischemia/reperfusion induces SBC enhancement and vibegron directly inhibits detrusor overactivity via the large conductance potassium channel, which involves β₃-adrenoceptor, rather than the cAMP signaling pathway.

Selectivity and Maximum Response of Vibegron and Mirabegron for β3-Adrenergic Receptors

Background

The β3-adrenergic agonists vibegron and mirabegron have shown favorable safety profiles and efficacy for the treatment of overactive bladder. However, β-adrenergic receptors are also found outside the bladder, which could lead to off-target activity.

Objective

This study assessed the selectivity of vibegron and mirabegron for β-adrenergic receptors and the maximal effect and potency for β3-adrenergic receptors.

Methods

Functional cellular assays were performed using Chinese hamster ovary-K1 cells expressing β1-, Chinese hamster ovary cells expressing β2-, and human embryonic kidney 293 cells expressing β3-adrenergic receptors. Cells were incubated with vibegron, mirabegron, or control (β1 and β3, isoproterenol; β2, procaterol). Responses were quantified using homogeneous time-resolved fluorescence of cyclic adenosine monophosphate and were normalized to the respective control. Half-maximal effective concentration and maximum response values were determined by nonlinear least-squares regression analysis.

Results

Activation of β3-adrenergic receptors with vibegron or mirabegron resulted in concentration-dependent β3-adrenergic receptor responses. Mean (SEM) half-maximal effective concentration values at β3-adrenergic receptors were 2.13 (0.25) nM for vibegron and 10.0 (0.56) nM for mirabegron. At a concentration of 10 µM, β3-adrenergic activity relative to isoproterenol was 104% for vibegron and 88% for mirabegron. Maximum response at β3-adrenergic receptors was 99.2% for vibegron and 80.4% for mirabegron. β1-adrenergic activity was 0% and 3% for vibegron and mirabegron, respectively; β2-adrenergic activity was 2% and 15%, respectively.

Conclusions

Vibegron showed no measurable β1 and low β2 activity compared with mirabegron, which showed low β1 and some β2 activity. Both showed considerable selectivity at β3-adrenergic receptors; however, vibegron demonstrated near-exclusive β3 activity and a higher maximum β3 response.

Cryo-EM structures of the β3 adrenergic receptor bound to solabegron and isoproterenol

The β₃-adrenergic receptor (β₃AR) is the most essential drug target for overactive bladder and has therapeutic potentials for the treatments of type 2 diabetes and obesity. Here, we report the cryo-electron microscopy structures of the β₃AR-G_s signaling complexes with the selective agonist, solabegron and the nonselective agonist, isoproterenol. Comparison of the isoproterenol-, mirabegron-, and solabegron-bound β₃AR structures revealed that the extracellular loop 2 changes its conformation depending on the bound agonist and plays an essential role in solabegron binding. Moreover, β₃AR has an intrinsically narrow exosite, regardless of the agonist type. This structural feature clearly explains why β₃AR prefers mirabegron and solabegron, as the narrow exosite is suitable for binding with agonists with elongated shapes. Our study deepens the understanding of the binding characteristics of β₃AR agonists and may pave the way for developing β₃AR-selective drugs.

Effects of vibegron on ambulatory blood pressure in patients with overactive bladder: results from a double-blind, placebo-controlled trial

OBJECTIVES

To characterize the blood pressure (BP) profile of the new β3-adrenergic receptor agonist, vibegron, in patients with overactive bladder.

METHODS

Patients were randomized to once-daily vibegron 75 mg or placebo for 28 days and underwent ambulatory BP monitoring. The primary endpoint was change from baseline (CFB) to day 28 in mean daytime ambulatory systolic BP (SBP). Secondary endpoints were CFB in mean 24-h SBP and in mean daytime and mean 24-h ambulatory diastolic BP (DBP) and heart rate (HR). Safety was assessed through adverse event reporting.

RESULTS

Of 214 patients randomized, 96 receiving vibegron and 101 receiving placebo had evaluable baseline and day 28 measurements. Overall, 39.6 and 30.7% of patients receiving vibegron and placebo, respectively, had preexisting hypertension. The least squares mean difference (LSMD; 90% confidence interval) between vibegron and placebo in CFB in mean daytime SBP was 0.8 (-0.9, 2.5) mmHg. LSMD in CFB in mean daytime DBP and HR was 0.0 mmHg and 0.9 bpm, respectively. No significant differences between treatments were seen in CFB in mean 24-h SBP (LSMD, 0.6 mmHg), DBP (-0.2 mmHg) or HR (1.0 bpm). The most common treatment-emergent adverse event was hypertension, with rates comparable between groups [vibegron: n = 5 (4.7%); placebo: n = 4 (3.7%)]. One patient receiving vibegron took a prohibited medication (phentermine) known to increase BP.

CONCLUSIONS

Once-daily vibegron had no statistically significant or clinically relevant effects on BP or HR.

An Evaluation of the Efficacy and Safety of Vibegron in the Treatment of Overactive Bladder

Pharmacologic treatment for overactive bladder (OAB), which is characterized by bothersome symptoms such as urgency and urge urinary incontinence (UUI), includes anticholinergics and β3-adrenergic receptor agonists. Anticholinergics are associated with adverse effects including dry mouth, constipation, cognitive impairment, and increased risk of dementia. Therefore, the drug class of β3-adrenergic receptor agonists may represent an effective, safe treatment option. Vibegron, a β3-adrenergic receptor agonist, was approved for use in Japan (2018) and the United States (2020). Over the past 3 years, 2 phase 3 trials (EMPOWUR, EMPOWUR extension) have been conducted with once-daily vibegron 75 mg for the treatment of OAB, and additional secondary and subgroup analyses have detailed the efficacy and safety of vibegron. In the international phase 3 EMPOWUR trial, treatment with vibegron was associated with significant improvements compared with placebo in efficacy outcomes of micturition frequency, UUI episodes, urgency episodes, and volume voided as early as week 2 that were sustained throughout the 12-week trial. The 40-week EMPOWUR extension study, following the 12-week treatment period, demonstrated sustained efficacy in patients receiving vibegron for 52 weeks. Treatment with vibegron was also associated with improvements in patient-reported measures of quality of life. Across studies, vibegron was generally safe and well tolerated. A separate, dedicated ambulatory blood pressure monitoring study showed that treatment with vibegron was not associated with clinically meaningful effects on blood pressure or heart rate. Across all studies, vibegron was efficacious, safe, and well tolerated and thus represents a valuable treatment option for patients with OAB. Here, nearly 1 year after US approval, we review the published data on efficacy and safety of vibegron 75 mg for the treatment of OAB.

How to choose appropriate medication for overactive bladder: Findings from the largest integrated clinical trial database analysis of mirabegron studies

Medical treatment of overactive bladder (OAB) includes antimuscarinic agents, beta-3 adrenoceptor agonist (mirabegron), or combination with both drugs. Recently, a meta-analysis reported the integrated clinical trial data from 10 phase 2–4, double-blind, 12-week mirabegron monotherapy studies. The results confirmed that mirabegron is as effective as the previously used antimuscarinic agent to treat OAB. The treatment-emergent adverse events were similar across subgroups. This article comments on this largest integrated clinical trial data analysis, and reviews the recently published literature and tries to reveal how to choose the appropriate medication for OAB. For OAB patients, starting from antimuscarinic agent is feasible. However, if the patients have risk of cognitive dysfunction, a history of constipation, dry mouth, and urinary retention, starting with mirabegron 50 mg might be more safe and appropriate. In the elderly patients with low detrusor contractility, with central nervous system lesion, and men with benign prostatic hyperplasia, starting from 25 mg mirabegron is recommended. If the treatment result is not satisfactory to the 25 mg mirabegron, increase dose to 50 mg mirabegron is appropriate. In patients who have failed from the first OAB medication either with antimuscarinics or mirabegron 50 mg, the exchange of the OAB medication to each other should be tried first. If the treatment result is still not satisfactory, a combination of antimuscarinics and mirabegron is recommended.

Comparison of antimuscarinic drugs to beta adrenergic agonists in overactive bladder: A literary review

BACKGROUND

The purpose of this study was to carry an extended literature review to compare antimuscarnics with beta adrenergic agonists (mirabegron) in treatment of overactive bladder.

MATERIALS AND METHODS

A literature review was carried out, using key words in different databases including MEDLINE, PUBMED, and EMBASE. All relevant published articles during last 5 years with full texts available were included in this review for critical analysis and evaluation. In total, there were 20 studies including 7 systemic reviews, 6 retrospective cohort, 3 prospective cohort, 2 randomized controlled trials, and 2 cross sectional studies.

RESULTS

After critical evaluation the results were considered under parameters of efficacy, adverse effects, adherence and persistence, tolerability, cost-effectiveness. In 9 studies efficacy was evaluated, 5 studies dealt with adverse effects, same number evaluated adherence and persistence. Cost effectiveness was compared in 3 and same number of studies also compared tolerability.

CONCLUSIONS

To conclude, we found mirabegron is as efficacious as any other antimuscarnics, has better tolerability (including elderly), has better adverse effect profile, is cost effective, has better persistence and adherence rates at 12 months.

Beta 3 Adrenoreceptor Agonist for the Management of Lower Urinary Tract Symptoms in Men With Benign Prostatic Hyperplasia: A Systematic Review

Beta-3 adrenoceptor (B3AR) agonist which mediate detrusor relaxation has been tried as a new treatment modality for men with benign prostatic hyperplasia (BPH). However, it remains unclear whether the B3AR agonist has more clinical benefits and fewer adverse effects in men with BPH than in women. We performed a comprehensive search using multiple databases, trials registries, other sources of grey literature, and conference proceedings regardless of language or publication status and included randomized controlled trials. Two review authors independently screened the literature, extracted data, and assessed risk of bias. We performed statistical analyses using a random-effects model and interpreted them according to the Cochrane Handbook for Systematic Reviews of Interventions. Primary outcomes were urologic symptom scores, quality of life (QoL), and overall adverse events. We found 4 randomized controlled trials with 1,105 participants in 3 comparisons. All studies reported short-term outcomes (ranged from 8 weeks to 12 weeks). Mirabegron, tamsulosin, silodosin, fesoterodine, and tadalafil were administrated as intervention. While B3AR agonist can improve the patient-important outcomes within group (before and after treatment), B3AR agonist combination therapy with current standard BPH treatment such as alpha blocker or anticholinergic may not have additional effects on urological symptom scores and QoL compared to alpha blocker or anticholinergic monotherapy. B3AR agonist therapy with phosphodiesterase 5 inhibitor (PDE5I) showed statistical improvement on urological symptom scores or QoL compared to PDE5I monotherapy. For safety profile, B3AR agonist in all 3 comparisons may not increase adverse event rate. While B3AR agonists may be used for the treatment of lower urinary tract symptoms in men with BPH if storage symptoms with standard BPH treatment are insufficient, B3AR agonists appear to have trivial or similar effects compared to current standard BPH treatment.

The efficacy and safety of mirabegron in treating ureteral stent-related symptoms: A systematic review and meta-analysis

OBJECTIVES

This meta-analysis aimed to assess the efficacy and safety of mirabegron in treating ureteral stent-related symptoms.

METHODS

MEDLINE, EMBASE, and the Cochrane Controlled Trials Register were searched to identify randomized controlled trials (RCT) of mirabegron in treating ureteral stent-related symptoms. We conducted a systematic review and meta-analysis based on the eligible RCT.

RESULTS

Five RCT including 546 patients and comparing mirabegron with placebo or blank control were involved in the present research. Regarding efficacy, mirabegron was superior to controls in urinary symptom score (P = .0006) and general health score (P < .0001) of the Ureteral Stent Symptom Questionnaire, total International Prostate Symptom Score (P < .00001), quality of life (P < .0001), analgesic use (P = .008), and readmission or visit to hospital due to discomfort (P = .001). Safety assessments including adverse events (P = .40) suggested that mirabegron was well tolerated.

CONCLUSIONS

The present meta-analysis shows that mirabegron is an effective and safe treatment for relieving ureteral stent-related symptoms with a low occurrence of adverse events.

Cryo-EM structure of the β3-adrenergic receptor reveals the molecular basis of subtype selectivity

The β₃-adrenergic receptor (β₃AR) is predominantly expressed in adipose tissue and urinary bladder and has emerged as an attractive drug target for the treatment of type 2 diabetes, obesity, and overactive bladder (OAB). Here, we report the cryogenic electron microscopy structure of the β₃AR-G_s signaling complex with the selective agonist mirabegron, a first-in-class drug for OAB. Comparison of this structure with the previously reported β₁AR and β₂AR structures reveals a receptor activation mechanism upon mirabegron binding to the orthosteric site. Notably, the narrower exosite in β₃AR creates a perpendicular pocket for mirabegron. Mutational analyses suggest that a combination of both the exosite shape and the amino-acid-residue substitutions defines the drug selectivity of the βAR agonists. Our findings provide a molecular basis for βAR subtype selectivity, allowing the design of more-selective agents with fewer adverse effects.

Efficacy of vibegron, a novel β3-adrenoreceptor agonist, for lower urinary tract dysfunction in mice with spinal cord injury

OBJECTIVES

To investigate the effect of vibegron, a new clinically approved β3-adrenoceptor agonist in lower urinary tract dysfunction in mice with spinal cord injury.

METHODS

Investigators performed cystometry under awake conditions in 4-week spinal cord injury female mice. Two weeks after spinal cord injury, saline or vibegron (30 mg/kg) was orally administered for 2 weeks prior to the urodynamic study. Investigators removed L6-S1 dorsal root ganglia from the saline- or vibegron-treated spinal cord injury mice as well as from saline-treated normal (spinal intact) mice to evaluate the levels of transient receptor potential cation channel subfamily V member 1, transient receptor potential cation channel subfamily A member 1, activating transcription factor 3, and inducible nitric oxide synthase transcripts using real-time polymerase chain reaction.

RESULTS

In vibegron-treated spinal cord injury mice, nonvoiding contractions during bladder filling, which were increased in spinal cord injury compared to spinal intact mice, were significantly decreased. Micturition pressure or voiding efficiency was not significantly increased in comparison to measurements in saline-treated spinal cord injury mice. The expression of transient receptor potential cation channel subfamily V member 1, transient receptor potential cation channel subfamily A member 1, activating transcription factor 3, and inducible nitric oxide synthase messenger RNA was increased in spinal cord injury mice compared to spinal intact mice, but significantly decreased after vibegron treatment.

CONCLUSIONS

Vibegron improves spinal cord injury-induced detrusor overactivity in addition to significantly reducing C-fiber afferent receptors such as transient receptor potential cation channel subfamily V member 1, transient receptor potential cation channel subfamily A member 1, and inflammatory cytokines/markers, such as activating transcription factor 3 and inducible nitric oxide synthase, in spinal cord injury mice. Thus, vibegron might be effective in the treatment of storage lower urinary tract dysfunction induced by C-fiber afferent activation after spinal cord injury.

Association between the Trp64Arg polymorphism of the ADRB3 gene and overactive bladder

BACKGROUND

The β₃ -adrenergic receptor (ADRB3) is very important in the regulation of the human detrusor muscle function. The well-known tryptophan64arginine polymorphism of the ADRB3 gene alters the response of the receptor to various stimuli, including adrenalin and noradrenalin, and may increase the susceptibility to develop overactive bladder (OAB). Therefore, this study was performed to determine whether ADRB3 Trp64Arg polymorphism is associated with the pathophysiology of OAB syndrome.

METHODS

The study group (n = 150) consists of 72 patients with OAB and 78 controls without OAB. Venous blood samples were taken from all participants to analyze the ADRB3 gene Trp64Arg polymorphism using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay. We compared the distribution of Trp64Arg polymorphism and symptom severity in both OAB and non-OAB subjects using χ² test and Mann-Whitney's U test, respectively.

RESULTS

The frequency of the 64Arg variant (heterozygous plus homozygous) in OAB and non-OAB subjects was 15.3% and 14.1%, respectively. There was no statistically significant difference between the OAB and non-OAB groups in regard to the distribution frequency of ADRB3 Trp64Arg polymorphism. The total frequency (OAB + non-OAB, 76 women and 74 men) of the Arg64 variant allele was 5.9% and 10.8% in women and in men, respectively. Although the frequency of the Arg64 variant was nearly twofold higher in men compared to women, the difference was not statistically significant.

CONCLUSIONS

These results demonstrated that the ADRB3 Trp64Arg polymorphism is not significantly associated with OAB syndrome in a sample of Turkish OAB patients.

Efficacy and safety of tamsulosin vs its combination with mirabegron in the management of lower urinary tract non-neurogenic overactive bladder symptoms (OABS) because of Benign Prostatic Enlargement (BPE)-An open label randomised controlled clinical study

PURPOSE

The efficacy and safety of βeta-3 agonists (Mirabegron 50 mg) have been sparingly assessed in the published English literature. We aim to do an efficacy-safety analysis of Mirabegron-Tamsulosin combination therapy vs tamsulosin-placebo monotherapy in a select subset of medication virgin Benign Prostatic Enlargement (BPE) patients with coexisting predominant non-neurogenic overactive bladder symptoms (OABS).

METHODS

After prior written informed consent and IEC, 80 patients of uncomplicated BPE with coexisting non-neurogenic OABS and IPSS of >7 without contraindications to drug therapy were computer randomised/allocated to receive either[50 mg Mirabegron plus Tamsulosin 0.4 mg (Intervention arm-I)]or [Tamsulosin 0.4 mg plus capsule lactobacillus (Comparator arm-II)] once daily for 8 weeks. Efficacy was evaluated using the OABS Score (OABSS), mean change in nocturnal frequency (NF), PVR and IPSS, while safety was assessed by recording treatment emergent adverse events (TEAE). Follow-up visits were performed at second, fourth and eighth week.

RESULTS

Patient data in both groups were generally comparable with the exception of NF and IPSS storage sub score (IPSS-ss). Significant improvements were visualised in the eighth week primary endpoint total OABS sub score (OABSS-ss) in the combination group (P < .001).Similar significant improvements were seen with most secondary parameters such as the mean change in NF, IPSS, IPSS-ss, OABS-ss, voided volume, Qmax, and Quality of life index (QOL) (P < .001). No significant increase in PVR was observed in the Mirabegron arm and no patient developed urinary retention. The TEAE were minor, self-limiting and managed symptomatically without drug discontinuity.

CONCLUSION

Mirabegron can be significantly efficacious and safe in ameliorating non-neurogenic OABS induced by BPE vs placebo by initiating combination therapy from the start as opposed to the usual 'add on therapy' protocol. This combination appeared to be superior in terms of overall safety, minimal side effects, better compliance and tolerability vs Tamsulosin monotherapy in select BPE patients with predominant non-neurogenic OABS.

Cardiovascular safety of vibegron, a new β3-adrenoceptor agonist, in older patients with overactive bladder: Post-hoc analysis of a randomized, placebo-controlled, double-blind comparative phase 3 study

AIMS

To examine the safety and efficacy of vibegron, a new β3-adrenoceptor agonist, in patients aged ≥65 years, with a focus on the effects on cardiovascular system and overactive bladder (OAB) symptoms.

METHODS

A post-hoc subgroup analysis was performed of a randomized, placebo-controlled, double-blind comparative phase 3 study of vibegron, including those assigned to receive either vibegron 50 mg (V50), vibegron 100 mg (V100), or placebo for 12 weeks. Subjects were stratified into two subgroups based on age: a <65-year subgroup and a ≥65-year subgroup. Safety (changes in systolic and diastolic blood pressure, pulse rate, and residual urine volume) and efficacy (changes in the numbers of micturitions, urgency episodes, urgency urinary incontinence [UUI] episodes, and the voided volume/micturition) were assessed in the subgroups treated with vibegron vs. placebo.

RESULTS

There were no significant differences in the cardiovascular outcomes (blood pressure and pulse rate), nor in the changes in residual urine volume, between the V50/100 and placebo groups in the <65-year or ≥65-year subgroup after 12-week treatment. Adverse events were slightly increased in the ≥65-year subgroup. In the efficacy analysis, V50/100 demonstrated similar efficacy in the <65-year and ≥65-year subgroups; an increasing trend in the voided volume/micturition was observed in subjects aged ≥65 years compared to subjects aged <65 years.

CONCLUSIONS

Vibegron was suggested to be similarly effective in patients ≥65 and <65 years and to have minimal influence on cardiovascular parameters.

Effect of amniotic fluid stem cell transplantation on the recovery of bladder dysfunction in spinal cord-injured rats

The effects of human amniotic fluid stem cell (hAFSC) transplantation on bladder function and molecular changes in spinal cord-injured (SCI) rats were investigated. Four groups were studied: sham and SCI plus phosphate-buffered saline (SCI + PBS), human embryonic kidney 293 (HEK293) cells, and hAFSCs transplantation. In SCI + PBS rat bladders, cystometry showed increased peak voiding pressure, voiding volume, bladder capacity, residual volume, and number of non-voiding contractions, and the total elastin/collagen amount was increased but collagen concentration was decreased at days 7 and 28. Immunoreactivity and mRNA levels of IGF-1, TGF-β1, and β3-adrenoceptor were increased at days 7 and/or 28. M2 immunoreactivity and M3 mRNA levels of muscarinic receptor were increased at day 7. M2 immunoreactivity was increased, but M2/M3 mRNA and M3 immunoreactivity levels were decreased at day 28. Brain derived-neurotrophic factor mRNA was increased, but immunoreactivity was decreased at day 7. HEK293 cell transplantation caused no difference compared to SCI + PBS group. hAFSCs co-localized with neural cell markers and expressed BDNF, TGF-β1, GFAP, and IL-6. The present results showed that SCI bladders released IGF-1 and TGF-β1 to stimulate elastin and collagen for bladder wall remodelling, and hAFSC transplantation improved these changes, which involved the mechanisms of BDNF, muscarinic receptors, and β3-adrenoceptor expression.

Effects of methylphenidate on the lower urinary tract in patients with attention deficit hyperactivity disorder and without voiding dysfunction

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is characterised by a range of symptoms, such as excessive mobility, difficulty in maintaining attention and inadequate impulse control. Methylphenidate (MPH) is widely prescribed as a treatment for ADHD. In the literature, studies investigating the effects of MPH on the lower urinary tract (LUT) are limited.

OBJECTIVE

The aim of the study was to evaluate MPH-induced LUT symptoms (LUTSs) in patients with ADHD without a diagnosis of voiding dysfunction (VD).

STUDY DESIGN

After ethical committee approval, volunteers aged 7-17 y were divided into two groups, with group 1 composed of individuals diagnosed with ADHD but not VD and group 2 (control) composed of healthy individuals. Lower urinary tract symptoms and quality of life, in addition to uroflowmetry test results and postvoiding residual volume (PVRV), were evaluated in both groups at baseline and again 4 wk later. The individuals in group 1 were treated with MPH after baseline screening. The dysfunctional voiding scoring system questionnaire was used for scoring LUTSs. Postvoiding residual volume was measured by ultrasound. Bladder capacity (BC) was calculated as the sum of voided volume (VV) and PVRV. The means of the maximum flow rate (Q max), mean flow rate (Q mean), VV, PVRV and BC were recorded.

RESULTS

After exclusions, there were 43 participants in group 1 and 39 participants in group 2. There was no significant difference between the mean age of groups (p = 0.727). Compared with the baseline, VV and BC increased significantly in group 1 (p = 0.001 and p = 0.002, respectively) at the 4-wk follow-up. There was no significant difference in these parameters in group 2.

DISCUSSION

This study demonstrated that VV and BC increased after MPH treatment in patients with ADHD without a diagnosis of VD. The mechanism underlying this effect is unclear, but it may be associated with dopaminergic and noradrenergic effects.

CONCLUSION

The findings of the present study can inform further studies on the mechanism underlying the effect of MPH on the LUT. In a future study, the authors suggest evaluating the effects of MPH in a urodynamic study in patients with ADHD diagnosed with VD.

Overactive Bladder Syndrome Treatments and Their Effect on Female Sexual Function: A Review

Introduction

Overactive bladder (OAB), the most common subtype of urinary incontinence, has a heavy price on quality of life, especially on sexual life. Unfortunately, most women rarely voice the worsening of sexual function, especially those who already suffer from OAB symptoms. It has been demonstrated that patients who suffer from OAB score lower on Pelvic Organ Prolapse/Urinary Incontinence Sexual Questionnaire and Female Sexual Function Index scores, meaning that their sexual function is debilitated. Therapies for OAB begin with traditional pelvic floor physiotherapy, advance to anticholinergic drugs, and become more invasive with intravesical injections of onabotulinumtoxinA (commonly known as Botox). Last, for patients resistant to conservative therapies, sacral neuromodulation is the treatment of choice.

Methods

This article reviews the current literature that sheds light on the above 4 treatments and their effect on sexual function. This topic is of great importance because of the under-reporting of sexual dysfunction in women who suffer from OAB, in hopes of raising awareness of sexual function for clinicians treating patients with OAB.

Results

This review found that the aforementioned 4 treatments for OAB (physiotherapy, anticholinergic drugs, intravesical injections of onabotulinumtoxinA, and sacral neuromodulation) do not have a detrimental affect on sexual function. On the contrary, the little data that do exist show that sexual function increases after these therapies are completed in women with OAB.

Conclusion

This review concludes with a positive outlook: physicians are helping women with OAB syndrome to improve their sexual function. However, not enough data exist, partially due to under-reporting of diminished sexual function.

Levy G, Lowenstein L. Overactive Bladder Syndrome Treatments and Their Effect on Female Sexual Function: A Review. Sex Med 2019;8:1–7.

Single-Cell Transcriptomic Map of the Human and Mouse Bladders

BACKGROUND

Having a comprehensive map of the cellular anatomy of the normal human bladder is vital to understanding the cellular origins of benign bladder disease and bladder cancer.

METHODS

We used single-cell RNA sequencing (scRNA-seq) of 12,423 cells from healthy human bladder tissue samples taken from patients with bladder cancer and 12,884 cells from mouse bladders to classify bladder cell types and their underlying functions.

RESULTS

We created a single-cell transcriptomic map of human and mouse bladders, including 16 clusters of human bladder cells and 15 clusters of mouse bladder cells. The homology and heterogeneity of human and mouse bladder cell types were compared and both conservative and heterogeneous aspects of human and mouse bladder evolution were identified. We also discovered two novel types of human bladder cells. One type is ADRA2A ⁺ and HRH2 ⁺ interstitial cells which may be associated with nerve conduction and allergic reactions. The other type is TNNT1 ⁺ epithelial cells that may be involved with bladder emptying. We verify these TNNT1 ⁺ epithelial cells also occur in rat and mouse bladders.

CONCLUSIONS

This transcriptomic map provides a resource for studying bladder cell types, specific cell markers, signaling receptors, and genes that will help us to learn more about the relationship between bladder cell types and diseases.

Everything You Always Wanted to Know about β3-AR * (* But Were Afraid to Ask)

The beta-3 adrenergic receptor (β₃-AR) is by far the least studied isotype of the beta-adrenergic sub-family. Despite its study being long hampered by the lack of suitable animal and cellular models and inter-species differences, a substantial body of literature on the subject has built up in the last three decades and the physiology of β₃-AR is unraveling quickly. As will become evident in this work, β₃-AR is emerging as an appealing target for novel pharmacological approaches in several clinical areas involving metabolic, cardiovascular, urinary, and ocular disease. In this review, we will discuss the most recent advances regarding β₃-AR signaling and function and summarize how these findings translate, or may do so, into current clinical practice highlighting β₃-AR’s great potential as a novel therapeutic target in a wide range of human conditions.

Long-Term Efficacy of Mirabegron Add-On Therapy to Antimuscarinic Agents in Patients With Spinal Cord Injury

Objective

To evaluate the long-term efficacy of mirabegron add-on therapy in patients with spinal cord injury (SCI) based on an urodynamic study.

Methods

This retrospective study involved a chart audit of individuals with SCI who underwent two consecutive urodynamic studies between April 1, 2015 and April 1, 2018. After adding 50 mg of mirabegron once a day to the pre-existing antimuscarinic therapy for a period of, at least 6 months, the following variables were analyzed: change in cystometric capacity, change in bladder compliance, change in maximal detrusor pressure, change in reflex volume, and presence of significant leakage during filling cystometry.

Results

A total of 31 participants with a mean age of 41±15 years were included in the analysis. A significant increase in cystometric capacity (mean, 362 to 424 mL; p=0.03), reflex volume (mean, 251 to 329 mL; p=0.02), and bladder compliance (median, 12 to 18 mL/cmH₂O; p=0.04) was observed. The presence of leakage during filling cystometry was significantly reduced (29% to 10%; p=0.03). Likewise, a non-significant decrease in the change in maximal detrusor pressure was observed (mean, 31 to 27 cmH₂O; p=0.39).

Conclusion

Adding mirabegron to conventional antimuscarinics further improved urodynamic parameters in patients with chronic SCI, and sustained efficacy was observed in long-term use.

Effect of co-administration of BRL-37344 and tadalafil on reduction of overactive bladder symptoms after induction of detrusor overactivity in mice1

PURPOSE

To evaluate the impact of the combination of BRL 37344 and tadalafil (TDF) on the reduction of overactive bladder (OB) symptoms.

METHODS

Thirty mice were randomized into 5 groups (G) of 6 animals each. L-NAME was used to induce DO. G1: Control; G2: L-NAME; G3: L-NAME + TDF; G4: L-NAME + BRL 37344; G5: L-NAME + TDF + BRL 37344. After 30 days of treatment, the animals were submitted to cystometry to evaluate non-voiding contractions (NVC), threshold pressure (TP), baseline pressure (BP), frequency of micturition (FM) and threshold volume (TV). Differences between the groups were analyzed with ANOVA followed by the Tukey test.

RESULTS

NVC increased in G2 (4.33±2.58) in relation to G1 (1.50±0.55). NVC decreased in G3 (2.00±1.10), G4 (1.50±1.52) and G5 (2.00±1.26) compared to G2 (p<0.05). FM decreased in G3 (0.97±0.71), G4 (0.92±0.38) and G5 (1.05±0.44) compared to G2 (p<0.05). However, the combination of TDF and BRL37344 was not more effective at increasing NVC and improving FM than either drug alone. The five groups did not differ significantly with regard to TV.

CONCLUSION

The combination of BRL 37344 and TDF produced no measurable additive effect on reduction of OB symptoms.

Therapeutic effect and mechanism of polysaccharide from Alpiniae oxyphyllae fructus on urinary incontinence

The purpose of this paper was to investigate the effects and mechanism of polysaccharide (PAOF) from Alpiniae oxyphyllae fructus on urinary incontinence (UI) in old-age hydruric model rats (OHMR). Results suggested that PAOF can significantly reduce the urination volume, Na⁺, Cl^- emission and increase K⁺ excretion of OHMR. In addition, PAOF can increase the content of aldosterone (ALD) and antidiuretic hormone (ADH) in blood of OHMR. The coefficients of spleen, thymus and adrenal of OHMR were improved by PAOF. Furthermore, PAOF can not only elevate significantly the expression of β3-adrenoceptor mRNA in bladder detrusor of OHMR, but also increase the content of adenylate cyclase (AC), cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) in bladder detrusor of OHMR. Meanwhile, PAOF can elevate significantly the expression of PKA protein in bladder detrusor of rats with polyuria. The data implied that PAOF may offer therapeutic potential against UI.

Mirabegron induces relaxant effects via cAMP signaling-dependent and -independent pathways in detrusor smooth muscle

OBJECTIVE

We previously found that mirabegron exerts a relaxant effect in the presence of the β₃ -adrenoceptor antagonist SR58894A during carbachol-induced contraction in human and pig detrusor. The aim of this study was to explore the possible mechanism underlying the relaxant effects of mirabegron using detrusor smooth muscle.

METHODS

Human tissue was obtained from urinary bladders of patients undergoing radical cystectomy at Kyushu University and Harasanshin Hospital. Pig tissue was obtained from an abattoir. Tension force (organ bath experiments) was measured in intact or permeabilised (α-toxin or β-escin) detrusor smooth muscle strips. The contribution of cAMP-dependent signaling and the inhibition of Ca²⁺ sensitization to the relaxant effects of mirabegron were characterized using 1 μM SR58894A, 100 μM SQ22536 (an adenylyl cyclase inhibitor), 10 μM H-89 (a protein kinase [PK] A inhibitor), 10 μM Y-27632 (a selective Rho kinase inhibitor), and 10 μM GF-109203X (a selective PKC inhibitor).

RESULTS

30 μM Mirabegron impaired carbachol (0.03-1 μM)-induced contraction in human detrusor smooth muscle. SR58894A only partially attenuated the relaxant effects of mirabegron in human and pig detrusor strips precontracted with 1 μM carbachol. In α-toxin-permeabilized detrusor strips, tension force at 1 μM [Ca²⁺ ]_i was decreased by mirabegron in a concentration-dependent manner. The relaxant effect of mirabegron was only slightly attenuated by H-89 and not significantly affected by SQ22536. Y-27632 potentiated the relaxation response to mirabegron, but attenuated responses to cAMP; GF-109203X had little effect. Mirabegron but not cAMP had a notable relaxant effect in the pig detrusor smooth muscle permeabilized with β-escin.

CONCLUSIONS

Mirabegron-induced relaxation of pig and human detrusor smooth muscle occurs via both a β₃ -adrenoceptor/cAMP-dependent and -independent pathway.

Mirabegron, alone and in combination, in the treatment of overactive bladder: real-world evidence and experience

Overactive bladder (OAB), the syndrome characterized by urgency, with or without urgency incontinence, usually with frequency and nocturia, in the absence of infection or other pathology, is a common, distressing and often debilitating condition with a high prevalence in the general population. For many years, the only available pharmacological treatment for OAB were the antimuscarinic agents. More recently, mirabegron, a selective agonist of the β3 adrenergic receptor, has become available. In this article we review the current evidence and experience of its use.

The effect of mirabegron, used for overactive bladder treatment, on female sexual function: a prospective controlled study

BACKGROUND

Αim of the study was to determine the effect of mirabegron, used for overactive bladder (OAB) treatment, on female sexual function.

METHODS

Eighty five sexually active women suffering from overactive bladder were prospectively enrolled in this study. Females were divided into two groups. In Group A (control), 48 patients received no treatment and in Group B, 37 patients received mirabegron 50 mg/daily for 3 months. Patients were evaluated with FSFI-Gr at the beginning of the study and again after a period of 3 months.

RESULTS

In Group B, there was a significant increase post-treatment compared to baseline (p < 0.001) in total FSFI (20.3 (3.8) to 26.6 (4.2)) and all domains (desire: 3.0 (1.2) to 4.8 (1.2)), arousal: 3.0 (0.8) to 4.8 (0.9), lubrication: 3.9 (1.1) to 4.8 (1.2), orgasm: 3.6 (0.8) to 4.8 (1.0), satisfaction: 3.2 (0.4) to 4.0 (0.8) and pain: 3.2 (0.8) to 4.4 (1.2)). In Group A, there were no statistically significant changes in pre- and post-observation values.

CONCLUSIONS

This study is one of the few demonstrating that management of OAB with mirabegron improves female sexual function.

TRIAL REGISTRATION

TRN ISRCTN17199301 , 20/10/2017, retrospectively registered.

Beta-3 adrenoceptor expression in the uterosacral ligament in the postmenopausal women with pelvic organ prolapse

AIMS

β3-adrenoceptor (β3-AR) agonist is known to relax the detrusor muscles. Considering that both pelvic organ prolapse (POP) and overactive-bladder (OAB) are frequently seen in the elderly population, the effect of β3-AR agonist on the pelvic floor tissues should be investigated. As a first step, this pilot, experimental, and descriptive study was designed to investigate the presence of β3-AR expression in the uterosacral-ligaments (USLs) in postmenopausal (PMP) women with POP.

METHODS

After informed consent, PMP women undergoing hysterectomy for POP were recruited for the intraoperative collection of distal USL between 5/2016 and 8/2016. H&E analysis for the USLs and immunohistochemistry (IHC) analysis for β3-AR and α-actin smooth muscle (SM) were carried out. Tissue composition and percentage of β3-AR expression in the USLs were subjectively measured and the staining results were expressed as descriptive analysis.

RESULTS

Total 11 USL specimens were collected and nine specimens were included for the final analysis (one specimen: used for antibody concentration adjustment and one specimen: failed proper staining). Under high-power-field, the USLs were composed of SM cells (81.5 ± 7.47%) and connective tissues (16.5 ± 7.9%). On IHC analysis, six out of nine specimens expressed β3-AR with a different level of expression in SM cells in the USLs.

CONCLUSIONS

The majority of distal USLs were composed of SM cells. β3-ARs are expressed in 67% of the study specimens. Considering that both POP and OAB are frequently seen in the elderly population, the effect of β3-AR agonist on the pelvic floor tissues should be investigated further.

Cardiovascular effects of antimuscarinic agents and beta3-adrenergic receptor agonist for the treatment of overactive bladder

INTRODUCTION

Overactive bladder (OAB) syndrome is common in the general population, particularly in elderly patients. Antimuscarinic drugs (AMs) are considered the mainstay pharmaceutical treatment of OAB whereas β3-adrenoceptor agonists, such as mirabegron, represent a good alternative. Owing to the important role of muscarinic and β3 receptors in cardiovascular (CV) tissue and to the fact that OAB patients often have CV comorbidities, the safety-profile of these drugs constitute an important challenge.

AREAS COVERED

The aim of this review is to evaluate the CV effects of AMs and mirabegron in OAB. A systematic literature search from inception until December 2017 was performed on PubMed and Medline.

EXPERT OPINION

AMs are generally considered to have good CV safety profile but, however, they may cause undesirable adverse events, such as dry mouth, constipation. CV AEs are rare but noteworthy, the most common CV consequences related to the use of these drugs are constituted by an increase in HR and QT interval. Mirabegron has similar efficacy and tolerability to AMs but causes less adverse events, with either modest hypertension and modest increase in HR (<5 bpm) being the most commonly reported.

Single onabotulinumtoxinA 200U dose improved clinical symptoms but not urothelial dysfunction in neurogenic detrusor overactivity due to spinal cord injury

OBJECTIVE

To evaluate the changes in urothelial dysfunction protein expressions in bladder after onabotulinumtoxin injection and correlate that with clinical outcomes in spinal cord injury (SCI) patients.

METHODS

Twenty-six patients with neurogenic detrusor overactivity (NDO) and urinary incontinence due to suprasacral SCI were treated with onabotulinumtoxinA 200U detrusor injection. Urodynamic studies and bladder biopsies were obtained at baseline, 3, and 6 months after treatment. Biopsy tissues were investigated for E-cadherin, zonula occludens-1 (ZO-1), mast cell activity, and urothelial cell apoptosis, sensory protein expression including purinergic receptor P2X3, endothelial NOS, inducible NOS, β3-adrenoceptors, and muscarinic receptors M2 and M3. Differences in functional protein expression between controls and SCI patients and between successful and failed treatment groups were analyzed.

RESULTS

SCI patients had significantly lower E-cadherin, higher mast cell activity, increased apoptosis, decreased M3 and eNOS expressions than the controls at baseline. Of the 26 patients, 17 (65%) showed improvement in bladder capacity by >50% at 3 months; however, improvement declined by 6 months after treatment. The urothelial expression of E-cadherin and ZO-1 increased at 3 months but had declined at 6 months. The urothelial sensory protein expression did not change significantly after treatment. M3 receptor density was significantly decreased in SCI patients at baseline and patients with treatment success 3 months after injection (p = 0.01).

CONCLUSION

A single injection of onabotulinumtoxinA 200U improved clinical symptoms but did not significantly alter urothelial sensory protein expression. The results imply that a single 200U onabotulinumtoxinA dose might not be adequate for urothelial dysfunction in NDO. IRB: TCGH 098-53.

Mirabegron: potential off target effects and uses beyond the bladder

The β₃ -adrenoceptor was initially an attractive target for several pharmaceutical companies due to its high expression in rodent adipose tissue, where its activation resulted in decreased adiposity and improved metabolic outputs (such as glucose handling) in animal models of obesity and Type 2 diabetes. However, several drugs acting at the β₃ -adrenoceptor failed in clinical trials. This was thought to be due to their lack of efficacy at the human receptor. Recently, mirabegron, a β₃ -adrenoceptor agonist with human efficacy, was approved in North America, Europe, Japan and Australia for the treatment of overactive bladder syndrome. There are indications that mirabegron may act at other receptors/targets, but whether they have any clinical relevance is relatively unknown. Besides overactive bladder syndrome, mirabegron may have other uses such as in the treatment of heart failure or metabolic disease. This review gives an overview of the off-target effects of mirabegron and its potential use in the treatment of other diseases.

LINKED ARTICLES

This article is part of a themed section on Molecular Pharmacology of GPCRs. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.21/issuetoc.