Muscarinic receptor subtypes modulating smooth muscle contractility in the urinary bladder

Non-surgical management of BPH: An updated review of current literature and state of the art on natural compounds and medical therapy

INTRODUCTION

Benign prostatic hyperplasia (BPH) is a common urological disease that is strongly associated with the aging process and can lead to lower urinary tract symptoms (LUTS). LUTS due to BPH can significantly affect the quality of life of many patients. Among the treatments available for BPH to improve symptoms and functional outcomes, drug therapy and surgical therapy are the options of choice. However, for most patients with symptomatic BPH, medical management remains the cornerstone of treatment. Pharmacologic interventions are often preferred as a first approach, being less invasive compared to surgery. Although the medical treatment of BPH is currently defined by the algorithms of international guidelines, the need for a more personalized approach is increasingly recognized given the wide and heterogeneous range of therapeutic options available.

MATERIALS AND METHODS

A review of medical therapy for BPH was conducted using relevant articles in PubMed, Scopus, and the Cochrane Central Register of Controlled Trials. In this review, all drug treatments currently available on the international market whose efficacy is scientifically proven are reviewed and described (phytotherapy, alpha-blockers, muscarinic receptor antagonists, 5-alpha-reductase inhibitors, combination therapies, etc.).

RESULTS

A total of 17 randomized clinical trials were selected for review. Further, 75 studies were included for analysis and discussion.

CONCLUSIONS

As the treatment landscape continues to evolve, tailoring therapy to individual patient needs and preferences is likely to become increasingly important to ensure that treatment strategies are both effective and meet patient expectations.

A Brief Overview of Cholinergic and Phosphodiesterase-5 Inhibitors in Diabetic Bladder Dysfunction

Diabetic bladder dysfunction (DBD) comprises a wide spectrum of lower urinary tract symptoms that impact diabetic patients' lives, including urinary frequency, urgency, incontinence, and incomplete bladder emptying. To relieve symptoms, anticholinergics have been widely prescribed and are considered an effective treatment. There is increasing evidence that diabetic patients may benefit from the use of phosphodiesterase 5 (PDE5) inhibitors. This narrative review aims to provide a brief overview of the pathophysiology of DBD along with a focus on cholinergic and phosphodiesterase inhibitors as therapies that benefit DBD. An examination of the literature suggests compelling avenues of research and underscores critical gaps in understanding the mechanisms underlying DBD. New tools and models, especially rodent models, are required to further elucidate the mechanisms of action of current therapies in the treatment of DBS.

Dynamic phenotypic shifts and M2 receptor downregulation in bladder smooth muscle cells induced by mirabegron

Introduction

Mirabegron is available for treatment of overactive bladder (OAB). However, mechanisms underlying symptom improvements and long-term effects on bladder smooth muscle cells are uncertain. Contractility and growth of bladder smooth muscle contribute to OAB, and depend on smooth muscle phenotypes, and on muscarinic receptor expression. Here, we examined prolonged exposure to mirabegron (20-48 h) on phenotype markers, muscarinic receptor expression, and phenotype-dependent functions in human bladder smooth muscle cells (hBSMC).

Methods

Expression of markers for contractile (calponin, MYH11) and proliferative (MYH10, vimentin) phenotypes, proliferation (Ki-67), and of muscarinic receptors were assessed by RT-PCR. Proliferation, viability, actin organization and contractions in cultured hBSMC were examined by EdU, CCK-8, phalloidin staining and matrix contraction assays.

Results

Calponin-1 mRNA decreased with 100 nM and 150 nM mirabegron applied for 20 h (0.56-0.6 fold of controls). Decreases were resistant to the β3-AR antagonist L-748,337 (0.34-0.55 fold, 100-150 nM, 20 h). After 40 h, decreases occured in the presence of L-748,337, but not without L-748,337. MYH11 mRNA increased with 150 nM mirabegron (40 h, 1.9 fold). This was partly preserved with L-748,337, but not observed after 20 h mirabegron exposure. Vimentin mRNA reduced with 150 nM mirabegron after 20 h, but not after 40 h, with and without L-748,337 (0.71-0.63 fold). MYH10 mRNA expression remained unaffected by mirabegron. Exposure to 150 nM mirabegron increased Ki-67 mRNA after 20 h in the presence of, but not without L-748,337, and after 40 h without, but not with L-748,337. Proliferation rates and actin organization were stable with 50-150 nM mirabegron (24 h, 48 h). Viability increased significantly after mirabegron exposure for 20 h, and by trend after 40 h, which was fully sensitive to L-748,337. M2 mRNA was reduced by 20 h mirabegron, which was resistant to L-748,337. Carbachol (3 µM) enhanced time-dependent contractions of hBSMC, which was inhibited by mirabegron (150 nM) in late phases (24 h), but not in early phases of contractions. Conclusion: Mirabegron induces dynamic phenotype alterations and M2 downregulation in hBSMC, which is paralleled by time-shifted anticontractile effects. Phenotype transitions may be involved in improvements of storage symptoms in OAB by mirabegron.

In Silico Electrophysiological Investigation of Transient Receptor Potential Melastatin-4 Ion Channel Biophysics to Study Detrusor Overactivity

Enhanced electrical activity in detrusor smooth muscle (DSM) cells is a key factor in detrusor overactivity which causes overactive bladder pathological disorders. Transient receptor potential melastatin-4 (TRPM4) channels, which are calcium-activated cation channels, play a role in regulating DSM electrical activities. These channels likely contribute to depolarizing the DSM cell membrane, leading to bladder overactivity. Our research focuses on understanding TRPM4 channel function in the DSM cells of mice, using computational modeling. We aimed to create a detailed computational model of the TRPM4 channel based on existing electrophysiological data. We employed a modified Hodgkin-Huxley model with an incorporated TRP-like current to simulate action potential firing in response to current and synaptic stimulus inputs. Validation against experimental data showed close agreement with our simulations. Our model is the first to analyze the TRPM4 channel's role in DSM electrical activity, potentially revealing insights into bladder overactivity. In conclusion, TRPM4 channels are pivotal in regulating human DSM function, and TRPM4 channel inhibitors could be promising targets for treating overactive bladder.

Acetylcholine, Another Factor in Breast Cancer

Acetylcholine (ACh) is a neurotransmitter that regulates multiple functions in the nervous system, and emerging evidence indicates that it could play a role in cancer progression. However, this function is controversial. Previously, we showed that organophosphorus pesticides decreased the levels of the enzyme acetylcholinesterase in vivo, increasing ACh serum levels and the formation of tumors in the mammary glands of rats. Furthermore, we showed that ACh exposure in breast cancer cell lines induced overexpression of estrogen receptor alpha (ERα), a key protein described as the master regulator in breast cancer. Therefore, here, we hypothesize that ACh alters the ERα activity through a ligand-independent mechanism. The results here reveal that the physiological concentration of ACh leads to the release of Ca+2 and the activity of MAPK/ERK and PI3K/Akt pathways. These changes are associated with an induction of p-ERα and its recruitment to the nucleus. However, ACh fails to induce overexpression of estrogen-responsive genes, suggesting a different activation mechanism than that of 17ß-estradiol. Finally, ACh promotes the viability of breast cancer cell lines in an ERα-dependent manner and induces the overexpression of some EMT markers. In summary, our results show that ACh promotes breast cancer cell proliferation and ERα activity, possibly in a ligand-independent manner, suggesting its putative role in breast cancer progression.

Nerve transfer for restoration of lower motor neuron-lesioned bladder, urethral, and anal sphincter function in a dog model. Part 3. nicotinic receptor characterization

Very little is known about the physiological role of nicotinic receptors in canine bladders, although functional nicotinic receptors have been reported in bladders of many species. Utilizing in vitro methods, we evaluated nicotinic receptors mediating bladder function in dogs: control (9 female and 11 male normal controls, 5 sham operated), Decentralized (9 females, decentralized 6-21 mo), and obturator-to-pelvic nerve transfer reinnervated (ObNT-Reinn; 9 females; decentralized 9-13 mo, then reinnervated with 8-12 mo recovery). Muscle strips were collected, mucosa-denuded, and mounted in muscle baths before incubation with neurotransmitter antagonists, and contractions to the nicotinic receptor agonist epibatidine were determined. Strip response to epibatidine, expressed as percent potassium chloride, was similar (∼35% in controls, 30% in Decentralized, and 24% in ObNT-Reinn). Differentially, epibatidine responses in Decentralized and ObNT-Reinn bladder strips were lower than controls after tetrodotoxin (TTX, a sodium channel blocker that inhibits axonal action potentials). Yet, in all groups, epibatidine-induced strip contractions were similarly inhibited by mecamylamine and hexamethonium (ganglionic nicotinic receptor antagonists), SR 16584 (α3β4 neuronal nicotinic receptor antagonist), atracurium and tubocurarine (neuromuscular nicotinic receptor antagonists), and atropine (muscarinic receptor antagonist), indicating that nicotinic receptors (particularly α3β4 subtypes), neuromuscular and muscarinic receptors play roles in bladder contractility. In control bladder strips, since tetrodotoxin did not inhibit epibatidine contractions, nicotinic receptors are likely located on nerve terminals. The tetrodotoxin inhibition of epibatidine-induced contractions in Decentralized and ObNT-Reinn suggests a relocation of nicotinic receptors from nerve terminals to more distant axonal sites, perhaps as a compensatory mechanism to recover bladder function.

Cellular mechanotransduction in health and diseases: from molecular mechanism to therapeutic targets

Cellular mechanotransduction, a critical regulator of numerous biological processes, is the conversion from mechanical signals to biochemical signals regarding cell activities and metabolism. Typical mechanical cues in organisms include hydrostatic pressure, fluid shear stress, tensile force, extracellular matrix stiffness or tissue elasticity, and extracellular fluid viscosity. Mechanotransduction has been expected to trigger multiple biological processes, such as embryonic development, tissue repair and regeneration. However, prolonged excessive mechanical stimulation can result in pathological processes, such as multi-organ fibrosis, tumorigenesis, and cancer immunotherapy resistance. Although the associations between mechanical cues and normal tissue homeostasis or diseases have been identified, the regulatory mechanisms among different mechanical cues are not yet comprehensively illustrated, and no effective therapies are currently available targeting mechanical cue-related signaling. This review systematically summarizes the characteristics and regulatory mechanisms of typical mechanical cues in normal conditions and diseases with the updated evidence. The key effectors responding to mechanical stimulations are listed, such as Piezo channels, integrins, Yes-associated protein (YAP) /transcriptional coactivator with PDZ-binding motif (TAZ), and transient receptor potential vanilloid 4 (TRPV4). We also reviewed the key signaling pathways, therapeutic targets and cutting-edge clinical applications of diseases related to mechanical cues.

Spasmolytic and Uroprotective Effects of Apigenin by Downregulation of TGF-β and iNOS Pathways and Upregulation of Antioxidant Mechanisms: In Vitro and In Silico Analysis

Apigenin is a phytochemical obtained from Chamomilla recutita. Its role in interstitial cystitis is not yet known. The present study is aimed at understanding the uroprotective and spasmolytic effects of apigenin in cyclophosphamide-induced interstitial cystitis. The uroprotective role of apigenin was analyzed by qRT-PCR, macroscopic analysis, Evans blue dye leakage, histological evaluation, and molecular docking. The spasmolytic response was measured by adding cumulative concentrations of apigenin to isolated bladder tissue pre-contracted with KCl (80 mM) and carbachol (10^-9-10^-4) on non-incubated and pre-incubated tissues with atropine, 4DAMP, methoctramine, glibenclamide, barium chloride, nifedipine, indomethacin, and propranolol. Apigenin inhibited pro-inflammatory cytokines (IL-6, TNF-α and TGF 1-β) and oxidant enzymes (iNOS) while increasing antioxidant enzymes (SOD, CAT, and GSH) in CYP-treated groups compared to the control. Apigenin restored normal tissue of the bladder by decreasing pain, edema, and hemorrhage. Molecular docking further confirmed the antioxidant and anti-inflammatory properties of apigenin. Apigenin produced relaxation against carbachol-mediated contractions, probably via blockade of M₃ receptors, K_ATP channels, L-type calcium channels, and prostaglandin inhibition. While the blockade of M₂ receptors, K_IR channels, and β-adrenergic receptors did not contribute to an apigenin-induced spasmolytic effect, apigenin presented as a possible spasmolytic and uroprotective agent with anti-inflammatory, antioxidant effects by attenuating TGF-β/iNOS-related tissue damage and bladder muscle overactivity. Thus, it is a potential agent likely to be used in treatment of interstitial cystitis.

Moxibustion attenuates neurogenic detrusor overactivity in spinal cord injury rats by inhibiting M2/ATP/P2X3 pathway

PURPOSE

Activation of muscarinic receptors located in bladder sensory pathways is generally considered to be the primary contributor for driving the pathogenesis of neurogenic detrusor overactivity following spinal cord injury. The present study is undertaken to examine whether moxibustion improves neurogenic detrusor overactivity via modulating the abnormal muscarinic receptor pathway.

MATERIALS AND METHODS

Female Sprague-Dawley rats were subjected to spinal cord injury with T9-10 spinal cord transection. Fourteen days later, animals were received moxibustion treatment for one week. Urodynamic parameters and pelvic afferents discharge were measured. Adenosine triphosphate (ATP) content in the voided cystometry fluid was determined. Expressions of M2, M3, and P2X3 receptors in the bladder mucosa were evaluated.

RESULTS

Moxibustion treatment prevented the development of detrusor overactivity in spinal cord injury rats, with an increase in the intercontraction interval and micturition pressure threshold and a decrease in afferent activity during filling. The expression of M2 was markedly suppressed by moxibustion, accompanied by a reduction in the levels of ATP and P2X3. M2 receptor antagonist methoctramine hemihydrate had similar effects to moxibustion on bladder function and afferent activity, while the M2-preferential agonist oxotremorine methiodide abolished the beneficial effects of moxibustion.

CONCLUSION

Moxibustion is a potential candidate for treating neurogenic bladder overactivity in a rat model of spinal cord injury, possibly through inhibiting the M2/ATP/P2X3 pathway.

Monoclonal Antibody Therapy for the Treatment of Interstitial Cystitis

An emerging theory regarding the potentially autoimmune nature of painful bladder syndrome/interstitial cystitis (PBS/IC) had led to several studies being conducted to assess the possible therapeutic effect of immunotherapeutic options for PBS/IC. This review presents the available evidence regarding the potential autoimmunity-based pathogenesis of PBS/IC and focuses on a main representative of the immunotherapeutic modalities for PBS/IC, aiming to summarize, evaluate, and present available data regarding the potential therapeutic role of monoclonal antibodies for PBS/IC patients. A non-systematic narrative and interpretative literature review was performed. The monoclonal antibodies included in the review were the anti-tumor necrosis factor-α (anti-TNF-α) agents adalimumab, which showed no difference compared to placebo, and certolizumab pegol, which showed statistically important differences in all outcome measures compared to placebo at the 18-week follow-up visit. Anti-nerve growth factor (anti-NGF) agents were also reviewed, including tanezumab, which showed both positive and negative efficacy results compared to placebo, and fulranumab, the study of which was discontinued owing to adverse events. In summary, monoclonal antibody therapy remains to be further researched in order for it to be proposed as a promising future treatment option for PBS/IC.

Does coupling to ADP ribosylation factor 6 explain differences between muscarinic and other receptors in interaction with β-adrenoceptor-mediated smooth muscle relaxation?

Numerous studies in airways, ileum, and urinary bladder have demonstrated that relaxation by β-adrenoceptor agonists has lower potency and/or efficacy when contraction was elicited by muscarinic receptor agonists as compared to other G-protein-coupled receptors, KCl, or basal tone, but the molecular mechanisms behind this relative resistance remain unclear. A paper by Huang et al. in this issue demonstrates that NAV2729, an inhibitor of ADP ribosylation factor 6, inhibits contraction of isolated blood vessels elicited by muscarinic receptor agonists, but not by α₁-adrenoceptor agonists or KCl. Against this background, we discuss the role of ADP ribosylation factor 6 in cellular responses to G-protein-coupled receptor stimulation. While ADP ribosylation factor 6 apparently is the only promising molecular explanation for the relative resistance of smooth muscle contraction elicited by muscarinic agonists, the existing data are insufficient for a robust conclusion.

Identification and Characterization of a Novel Large-Conductance Calcium-Activated Potassium Channel Activator, CTIBD, and Its Relaxation Effect on Urinary Bladder Smooth Muscle

The large-conductance calcium-activated potassium channel (BK_Ca channel) is expressed on various tissues and is involved in smooth muscle relaxation. The channel is highly expressed on urinary bladder smooth muscle cells and regulates the repolarization phase of the spontaneous action potentials that control muscle contraction. To discover novel chemical activators of the BK_Ca channel, we screened a chemical library containing 8364 chemical compounds using a cell-based fluorescence assay. A chemical compound containing an isoxazolyl benzene skeleton (compound 1) was identified as a potent activator of the BK_Ca channel and was structurally optimized through a structure-activity relationship study to obtain 4-(4-(4-chlorophenyl)-3-(trifluoromethyl)isoxazol-5-yl)benzene-1,3-diol (CTIBD). When CTIBD was applied to the treated extracellular side of the channel, the conductance-voltage relationship of the channel shifted toward a negative value, and the maximum conductance increased in a concentration-dependent manner. CTIBD altered the gating kinetics of the channel by dramatically slowing channel closing without effecting channel opening. The effects of CTIBD on bladder muscle relaxation and micturition function were tested in rat tissue and in vivo. CTIBD concentration-dependently reduced acetylcholine-induced contraction of urinary bladder smooth muscle strips. In an acetic acid-induced overactive bladder (OAB) model, intraperitoneal injection of 20 mg/kg CTIBD effectively restored frequent voiding contraction and lowered voiding volume without affecting other bladder function parameters. Thus, our results indicate that CTIBD and its derivatives are novel chemical activators of the bladder BK_Ca channel and potential candidates for OAB therapeutics. SIGNIFICANCE STATEMENT: The novel BK_Ca channel activator CTIBD was identified and characterized in this study. CTIBD directly activates the BK_Ca channel and relaxes urinary bladder smooth muscle of rat, so CTIBD can be a potential candidate for overactive bladder therapeutics.

Alterations in detrusor contractility in rat model of bladder cancer

Urinary incontinence of idiopathic nature is a common complication of bladder cancer, yet, the mechanisms underlying changes in bladder contractility associated with cancer are not known. Here by using tensiometry on detrusor smooth muscle (DSM) strips from normal rats and rats with bladder cancer induced by known urothelial carcinogen, N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN), we show that bladder cancer is associated with considerable changes in DSM contractility. These changes include: (1) decrease in the amplitude and frequency of spontaneous contractions, consistent with the decline of luminal pressures during filling, and detrusor underactivity; (2) diminution of parasympathetic DSM stimulation mainly at the expense of m-cholinergic excitatory transmission, suggestive of difficulty in bladder emptying and weakening of urine stream; (3) strengthening of TRPV1-dependent afferent limb of micturition reflex and TRPV1-mediated local contractility, promoting urge incontinence; (4) attenuation of stretch-dependent, TRPV4-mediated spontaneous contractility leading to overflow incontinence. These changes are consistent with the symptomatic of bladder dysfunction in bladder cancer patients. Considering that BBN-induced urothelial lesions in rodents largely resemble human urothelial lesions at least in their morphology, our studies establish for the first time underlying reasons for bladder dysfunction in bladder cancer.

Functional Characterization of Cholinergic Receptors in Melanoma Cells

In the last two decades, the scientific community has come to terms with the importance of non-neural acetylcholine in light of its multiple biological and pathological functions within and outside the nervous system. Apart from its well-known physiological role both in the central and peripheral nervous systems, in the autonomic nervous system, and in the neuromuscular junction, the expression of the acetylcholine receptors has been detected in different peripheral organs. This evidence has contributed to highlight new roles for acetylcholine in various biological processes, (e.g., cell viability, proliferation, differentiation, migration, secretion). In addition, growing evidence in recent years has also demonstrated new roles for acetylcholine and its receptors in cancer, where they are involved in the modulation of cell proliferation, apoptosis, angiogenesis, and epithelial mesenchymal transition. In this review, we describe the functional characterization of acetylcholine receptors in different tumor types, placing attention on melanoma. The latest set of data accessible through literature, albeit limited, highlights how cholinergic receptors both of muscarinic and nicotinic type can play a relevant role in the migratory processes of melanoma cells, suggesting their possible involvement in invasion and metastasis.

Antispasmodic effect of hydroalcoholic and flavonoids extracts of Dracocephalum kotschyi on rabbit bladder

Introduction: Dracocephalum kotschyi extract has antispasmodic activities on smooth muscle including ileum, uterus and trachea. The objective of this research was to investigate antispasmodic activity of hydroalcoholic and flavonoids extracts of D. kotschyi on rabbit bladder contractions. Methods: Rabbits were euthanized by carbon dioxide asphyxiation and the whole bladder was dissected out and immersed in the Tyrode’s solution. Longitudinal bladder strips were mounted vertically in an organ bath at 37°C and gassed continuously with O2 . Bladder strips were contracted with acetylcholine (ACh), KCl, or electrical field stimulation (EFS). Isotonic tension of the tissue was recorded before and after addition of hydroalcoholic or flavonoids rich extracts of D. kotschyi. Nifedipine and propantheline were used as standard drugs. Results: Standard drug propantheline, prevented bladder phasic contraction induced by ACh (1µM) without affecting KCl response. On the other hand, cumulative addition of nifedipine attenuated the tonic contractions induced by KCl (20mM) on bladder smooth muscle. Hydroalcoholic and flavonoids extracts of D. kotschyiat concentration ranges of 10-320 µg/ mL in a concentration dependent way inhibited bladder tonic contraction induced by KCl (n=6). Both extracts also in a concentration-dependent manner relaxed EFS and ACh-induced contractions (range, 20–1280 µg/mL) of bladder smooth muscle in vitro. Complete inhibition was achieved with the highest used concentrations of the extracts. The inhibitory effect of the extract was reversible following washing the tissues with fresh Tyrode’s solution. Conclusion: This study clearly demonstrated that D. kotschyi extracts were able to prevent contractions induced by ACh, KCl or EFS in isolated rabbit bladder. This means that people consuming this medicinal plant may face urinary retention which could be a problem for patients with prostate hypertrophy. On the other hand, this plant might be useful in patients with urinary incontinence. However, its usefulness must be assessed in the controlled clinical trials.

Effects of combined treatment with fesoterodine and mirabegron in a pelvic congestion rat model: Results from in vitro and in vivo functional studies

Objectives

To examine the effect of combining a nonselective muscarinic receptor antagonist, 5‐hydroxymethyl tolterodine (an active metabolite of fesoterodine), with a β3 adrenoceptor agonist, mirabegron, in a rat model of pelvic congestion.

Methods

The rat pelvic congestion model used female Sprague‐Dawley rats with their bilateral common iliac and uterine veins ligated. Expressions of M2 and M3 receptor subtypes in the urothelium and detrusor were detected by real‐time polymerase chain reaction assays. The effects of both drugs were investigated on isolated bladder strips contracted by electrical field stimulation. in vivo single cystometry was used to assess the effects of 5‐hydroxymethyl tolterodine and mirabegron independently or in combination on bladder capacity, micturition pressure, and threshold pressure.

Results

Pelvic congestion rats showed decreased bladder capacity compared with controls, but micturition pressure and threshold pressure were unchanged. Pelvic congestion model rats also demonstrated an approximately two‐fold increase in expression of both M2 and M3 receptor subtypes in the urothelium. Additive relaxant effects of 5‐hydroxymethyl tolterodine and mirabegron were observed in vitro in the electrical field stimulation‐induced contractions of bladder strips from pelvic congestion rats. In vivo, bladder capacity was increased significantly by a combination of 5‐hydroxymethyl tolterodine and mirabegron, with the combined effect exceeding the sum of the effects of monotherapies. Micturition pressure and threshold pressure did not significantly differ between groups.

Conclusions

The combination of 5‐hydroxymethyl tolterodine with mirabegron suggests the potential of synergistic effects in a rat pelvic congestion model.

Acetylcholine receptors: Key players in cancer development

Acetylcholine (ACh) was first identified as a classic neuromodulator and transmit signals through two subgroups of receptors, namely muscarinic receptors (mAChRs) and nicotinic receptors (nAChRs). Apart from its well-established physiological role in central nervous system (CNS) and peripheral nervous system (PNS), autonomic nervous system and neuromuscular junction, the widely distributed expression of AChRs in different human organs suggests roles in other biological processes in addition to synaptic transmission. Accumulating evidence revealed that cancer cell processes such as proliferation, apoptosis, angiogenesis and even epithelial-mesenchymal transition (EMT) are mediated by overexpression of AChRs in different kinds of tumors. In breast cancer, α7-nAChR and α9-nAChR were reported to be oncogenic. On the other hand, research on the role of mAChRs in breast cancer tumorgenesis is limited and confined to M3 receptor only. Since AChRs distributed in both CNS and PNS even non-neuronal tissues, there is an urgent need for the development of subtype-specific AChR antagonist which inhibits cancer cell progression with minimal intervention on the normal acetylcholine-regulated system within human body.

Impairment of cholinergic bladder contractility in rat model of type I diabetes complicated by cystitis: Contribution of neurotransmitter-degrading ectoenzymes

Parasympathetic regulation of urinary bladder contractions primarily involves acetylcholine release and activation of detrusor smooth muscle (DSM) muscarinic acetylcholine (mACh) receptors. Co-release of ATP and activation of DSM purinergic P2X1-receptors may participate as well in some species. Both types of neuromuscular transmission (NMT) are impaired in diabetes, however, which factors may contribute to such impairment remains poorly understood. Here by using rats with streptozotocin(STZ)-induced type I diabetes (8th week after induction) we show that contribution of atropine-sensitive m-cholinergic component to the contractions of urothelium-denuded DSM strips evoked by electric field stimulation (EFS) greatly increased when diabetic bladders presented overt signs of accompanying cystitis. Modeling of hemorrhagic cystitis alone in control rats by cyclophosphamide injection only modestly increased m-cholinergic component of EFS-contractions. However, exposure of DSM strips from control animals to acetylcholinesterase (AChE) inhibitor, neostigmine (1-10 μM) largely reproduced alterations in EFS contractions observed in diabetic DSM complicated by cystitis. Ellman's assay revealed statistically significant 31% decrease of AChE activities in diabetic vs. control DSM. Changes in purinergic contractility of diabetic DSM were consistent with altered P2X1-receptor desensitization and re-sensitization. They could be mimicked by pharmacological inhibition of ATP-degrading ecto-ATPases with ARL 67156 (50 μM), pointing to compromised extracellular ATP clearance as underlying reason. We conclude that decreased AChE activities associated with diabetes and likely cystitis provide complementary factor to the described in literature altered expression of mACh receptor subtypes linked to diabetes as well as to cystitis to produce dramatic modification of cholinergic NMT.

Effectiveness of intramuscular neostigmine to accelerate bladder emptying after spinal anesthesia

Purpose

Postoperative urinary retention (POUR) is one of the most common complications following spinal anesthesia. Spinal anesthesia may influence urinary bladder function due to interruption of the micturition reflex. Urinary catheterization is the standard treatment of POUR. Urinary catheter insertion is an invasive procedure, which is associated with catheter-related infections, urethral trauma, and patient discomfort. The purpose of this study was to determine the effectiveness of intramuscular (IM) neostigmine to accelerate bladder emptying after spinal anesthesia.

Patients and methods

A total of 36 patients undergoing lower abdominal (except for pelvic, urologic, anorectal, and hernia surgery) and lower extremity surgery under spinal anesthesia were divided into two groups randomly (n=18), to either neostigmine (N) group or control (C) group. Neostigmine 0.5 mg (N group) or NaCl 0.9% (C group) was administered intramuscularly when Bromage score 0 and sensory level sacral two have been achieved. The time to first voiding after IM injection and the time to first voiding after spinal anesthesia were measured.

Results

The time to first voiding after IM injection was significantly faster (P≤0.05) in the N group than that in the C group, with median time as 40 minutes (20–70 minutes) and 75 minutes (55–135 minutes), respectively. Time to first voiding after spinal anesthesia was also significantly faster (P≤0.05) in the N group than that in the C group (mean of 280.8±66.6 minutes and 364.2±77.3 minutes, respectively).

Conclusion

IM neostigmine effectively accelerates bladder emptying after spinal anesthesia.

Fesoterodine: Pharmacological properties and clinical implications

Fesoterodine (as one of three drugs: dutasteride, finasteride and fesoterodine) was classified B (beneficial) by LUTS-FORTA 2014, indicating that it is a medicinal product with proven or obvious efficacy in the elderly, with limited side effects and/or safety concerns. A systematic literature review was undertaken in January 2018 using the PubMed and Google Scholar databases with the following individual and combined keywords: "fesoterodine", "pharmacology", "overactive bladder" and "antimuscarinics". The aim of the review was to determine which of fesoterodine's pharmacological properties explains its clinical benefits in general patient populations with OAB and the elderly in particular. The articles in the results were then selected by publication language (English and French only), methodology (off-topic studies, reported cases and literature reviews were excluded), relevance to the subject matter and publication date prior to 31 January 2018. A total of 205 articles was initially obtained, with 115 read and 45 selected. It appears that the association of four pharmacological properties specific to fesoterodine can explain that this drug has a good balance between efficacy and tolerability. These properties are namely the drug's high and nearly equal affinity for both the M2 and M3 muscarinic receptors, poor penetration of the blood-brain barrier, lack of hepatic first-pass activation -fesoterodine being rapidly and extensively converted to its active metabolite, 5-hydroxymethyl tolterodine, by ubiquitous esterases-, and its extended-release formulation. Fesoterodine's pharmacological profile is optimal for the treatment of overactive bladder. It is now recognized as one of the leading first-line treatment for this indication.

An investigation of factors predicting the type of bladder antimuscarinics initiated in Medicare nursing homes residents

Background

To examine factors predicting type of bladder antimuscarinics (BAM) initiated in nursing home (NH) residents.

Methods

Incident BAM initiators following NH admission were identified by constructing a retrospective cohort from Medicare files and Minimum Data Set (MDS). Participants included all residents 65 years and older admitted in Medicare-certified NH between January 1, 2007 and December 31, 2008 who were prescribed BAM and had continuous Medicare (Part A, B, and D) enrollment. Patient characteristics, medications, and comorbidities were derived from Medicare enrollment and claims. NH characteristics and health status were derived from MDS assessments. The outcome was defined as type of BAM initiated after admission (selective, non-selective extended release, non-selective immediate release). Multinomial logistic regression using generalized estimating equation methodology determined which factors predicted the type of BAM initiated.

Results

Twelve thousand eight hundred ninety-nine NH residents initiating BAM therapy were identified; 13.38% of new users were prescribed selective BAM, 45.56% non-selective extended release, and 41.07% non-selective immediate release medications. In both sexes, significant predictors of BAM included region of nursing home, body mass index, cognitive performance score, frailty measures, activities of daily living, and measures of bladder continence. In women, history of fracture and fall-related injuries were significant predictors of type of BAM use, while race and indicators of balance were significant predictors of type of BAM use in men. Non-pharmacological continence management strategies were not predictive of type of BAM initiation.

Conclusions

Several factors are important in predicting type of BAM initiation in both women and men, but other factors are sex-specific. Some observed factors predicting the type of BAM initiated, such as other medications use, body mass index, or provider-related factors are potentially modifiable and could be used in targeted interventions to help optimize BAM use in this population.

Trial registration

Not applicable.

Electronic supplementary material

The online version of this article (doi:10.1186/s12877-017-0690-2) contains supplementary material, which is available to authorized users.

Anti-cholinergic medications for bladder dysfunction worsen cognition in persons with multiple sclerosis

Bladder dysfunction is common in persons with MS (PwMS), often due to detrusor muscle overactivity. Anticholinergic medications are considered the first line treatment for bladder dysfunction and are known to worsen cognition in healthy older adults and in persons with dementia. Yet, it is not known if these medications have the same effect on PwMS. Thus, the Objective of this prospective matched-cohort study was to determine if anticholinergic medications affect objective measures of cognition in PwMS. We recruited PwMS starting either oxybutynin or tolterodine (cases). Cases and controls were tested with the Brief International Cognitive Assessment for MS (BiCAMS) battery prior to starting anticholinergic medications and 12weeks later. The primary outcome was change on the Symbol Digit Modalities Test (SDMT) between groups; secondary outcomes were changes on the other BiCAMS measures. Analysis of Covariance with baseline measures as covariates to assess the significance of between group differences was performed at 12weeks. Forty eight PwMS starting anticholinergic medications and 21 matched PwMS controls were recruited. There was a significant difference (p<0.001) in the change on the cognitive measures over 12weeks between groups. The controls demonstrated improvement, consistent with practice effect, while the cases remained unchanged. This study demonstrates that anticholinergic medications may have a negative effect on cognition in PwMS; further confirmatory studies are needed.

A Guide to Medications Inducing Salivary Gland Dysfunction, Xerostomia, and Subjective Sialorrhea: A Systematic Review Sponsored by the World Workshop on Oral Medicine VI

BACKGROUND

Medication-induced salivary gland dysfunction (MISGD), xerostomia (sensation of oral dryness), and subjective sialorrhea cause significant morbidity and impair quality of life. However, no evidence-based lists of the medications that cause these disorders exist.

OBJECTIVE

Our objective was to compile a list of medications affecting salivary gland function and inducing xerostomia or subjective sialorrhea.

DATA SOURCES

Electronic databases were searched for relevant articles published until June 2013. Of 3867 screened records, 269 had an acceptable degree of relevance, quality of methodology, and strength of evidence. We found 56 chemical substances with a higher level of evidence and 50 with a moderate level of evidence of causing the above-mentioned disorders. At the first level of the Anatomical Therapeutic Chemical (ATC) classification system, 9 of 14 anatomical groups were represented, mainly the alimentary, cardiovascular, genitourinary, nervous, and respiratory systems. Management strategies include substitution or discontinuation of medications whenever possible, oral or systemic therapy with sialogogues, administration of saliva substitutes, and use of electro-stimulating devices.

LIMITATIONS

While xerostomia was a commonly reported outcome, objectively measured salivary flow rate was rarely reported. Moreover, xerostomia was mostly assessed as an adverse effect rather than the primary outcome of medication use. This study may not include some medications that could cause xerostomia when administered in conjunction with others or for which xerostomia as an adverse reaction has not been reported in the literature or was not detected in our search.

CONCLUSIONS

We compiled a comprehensive list of medications with documented effects on salivary gland function or symptoms that may assist practitioners in assessing patients who complain of dry mouth while taking medications. The list may also prove useful in helping practitioners anticipate adverse effects and consider alternative medications.

Octodon degus, a new model to study the agonist and plexus-induced response in the urinary bladder

Urinary bladder function consists in the storage and controlled voiding of urine. Translational studies require animal models that match human characteristics, such as Octodon degus, a diurnal rodent. This study aims to characterize the contractility of the detrusor muscle and the morphology and code of the vesical plexus from O. degus. Body temperature was measured by an intra-abdominal sensor, the contractility of detrusor strips was evaluated by isometric tension recording, and the vesical plexus was studied by electrical field stimulation (EFS) and immunofluorescence. The animals showed a diurnal chronotype as judged from core temperature. The myogenic contractile response of the detrusor muscle to increasing doses of KCl reached its maximum (31.04 mN/mm²) at 60 mM. In the case of cumulative dose-response of bethanecol, the maximum response (37.42 mN/mm²) was reached at 3.2 × 10^-4 M. The response to ATP was clearly smaller (3.8 mN/mm²). The pharmacological dissection of the EFS-induced contraction identified ACh and sensory fibers as the main contributors to this response. The neurons of the vesical plexus were located mainly in the trigone area, grouped in big and small ganglia. Out of them, 48.1 % of the neurons were nitrergic and 62.7 % cholinergic. Our results show functional and morphological similarities between the urinary bladder of O. degus and that of humans.

Progressive changes in detrusor function and micturition patterns with chronic bladder ischemia

Purpose

Lower urinary tract symptoms (LUTS) are bothersome constellation of voiding symptoms in men and women as they age. Multiple factors and comorbidities are attributed to this problem but underlying mechanisms of nonobstructive nonneurogenic detrusor overactivity, detrusor underactivity and LUTS remain largely unknown. Our goal was to characterize detrusor function and voiding patterns in relation to muscarinic receptors expression, nerve fiber density, and neural ultrastructure in chronic bladder ischemia.

Materials and Methods

Iliac artery atherosclerosis and bladder ischemia were produced in male Sprague-Dawley rats. At 8 and 16 weeks after ischemia, micturition patterns and cystometrograms were recorded in conscious rats then bladder blood flow and nonvoiding spontaneous contractions were measured under general anesthesia. Bladder tissues were processed for Western blotting, immunostaining, and transmission electron microscopy.

Results

Bladder responses to ischemic insult depended on the duration of ischemia. Micturition patterns and cystometric changes at 8-week ischemia suggested detrusor overactivity, while voiding behavior and cystometrograms at 16-week ischemia implied abnormal detrusor function resembling underactivity. Upregulation of muscarinic M2 receptor was found after 8- and 16 weeks of ischemia. Downregulation of M3 and upregulation of M1 were detected at 16-week ischemia. Neural structural damage and marked neurodegeneration were found after 8 and 16 weeks of ischemia, respectively.

Conclusions

Prolonged ischemia may be a mediating variable in progression of overactive bladder to dysfunctional patterns similar to detrusor underactivity. The mechanism appears to involve differential expression of M1, M2, and M3 receptors, neural structural injury, and progressive loss of nerve fibers.

Benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH), which causes lower urinary tract symptoms (LUTS), is a common diagnosis among the ageing male population with increasing prevalence. Many risks factors, both modifiable and non-modifiable, can increase the risk of development and progression of BPH and LUTS. The symptoms can be obstructive (resulting in urinary hesitancy, weak stream, straining or prolonged voiding) or irritative (resulting in increased urinary frequency and urgency, nocturia, urge incontinence and reduced voiding volumes), or can affect the patient after micturition (for example, postvoid dribble or incomplete emptying). BPH occurs when both stromal and epithelial cells of the prostate in the transitional zone proliferate by processes that are thought to be influenced by inflammation and sex hormones, causing prostate enlargement. Patients with LUTS undergo several key diagnostic investigations before being diagnosed with BPH. Treatment options for men with BPH start at watchful waiting and progress through medical to surgical interventions. For the majority of patients, the starting point on the treatment pathway will be dictated by their symptoms and degree of bother.

An update on the use of transdermal oxybutynin in the management of overactive bladder disorder

Antimuscarinic medications are used to treat nonneurogenic overactive bladder refractory to nonpharmacologic therapy. Side effects such as dry mouth, constipation, blurred vision, dizziness, and impaired cognition limit the tolerability of therapy and are largely responsible for high discontinuation rates. Oxybutynin is a potent muscarinic receptor antagonist whose primary metabolite after first-pass hepatic metabolism is considered largely responsible for its associated anticholinergic side effects. Transdermal administration of medications bypasses hepatic processing. Specifically with oxybutynin, whose low molecular weight permits transdermal administration, bioavailability of the parent drug with oral administration is less than 10%, whereas with transdermal delivery is a minimum of 80%. The result has been an improved side effect profile in multiple clinical trials with maintained efficacy relative to placebo; however, the drug may still be discontinued by patients due to anticholinergic side effects and application site reactions. Transdermal oxybutynin is available as a patch that is changed every 3-4 days, a gel available in individual sachets, or via a metered-dose pump that is applied daily. The transdermal patch was briefly available as an over-the-counter medication for adult women, although at this time all transdermal formulations are available by prescription only.

Effects of bladder function by early tamsulosin treatment in a spinal cord injury rat model

Objective

To investigate the effects of early tamsulosin treatment on changes in bladder characteristics after a spinal cord injury.

Methods

We divided 45 rats into three groups: the control (CON) group, the spinal cord injury (SCI) group, and the SCI+tamsulosin treatment (SCI+TAM) group. Spinal cord transection was performed in the SCI and SCI+TAM groups. Tamsulosin was injected for 7 days in the SCI+TAM group. Intravesical and intra-abdominal catheters were implanted before cord injury. Basal pressure (BP), maximal vesical pressure (MVP), micturition volume (MV), and voiding interval time (VIT) were measured at 7 days after SCI. The bladder was then removed and used for an in vitro organ bath study and Western blot analysis. The percentage changes in contractility from baseline after acetylcholine alone, pretreatment with a muscarinic 2 (M2) receptor blocker (AQ-RA741), and pretreatment with a M3 receptor blocker (4-DAMP) were compared among the groups. Western blot analyses were performed to determine expression levels of pERK1/2 and rho-kinase.

Results

In cystometry, MVP, BP, MV, and VIT showed changes in the SCI and SCI+TAM groups versus the CON group (p<0.05). In the organ bath study, acetylcholine-induced contractility in the three groups differed significantly (p<0.05). Additionally, acetylcholine-induced contractility with 4-DAMP pretreatment was reduced significantly in the SCI+TAM group versus the SCI group. In Western blotting, pERK1/2 expression was stronger (p<0.05) and rho-kinase expression was weaker in the SCI+TAM group than the SCI group (p<0.05).

Conclusion

These results suggest that the bladder contraction due to acetylcholine after SCI can be decreased by tamsulosin in the acute stage and this involves changes in pERK1/2 and rho-kinase.

Izalpinin from fruits of Alpinia oxyphylla with antagonistic activity against the rat bladder contractility

BACKGROUND

Alpinia oxyphylla (Zingiberaceae), an herbaceous perennial plant, its capsular fruit is commonly used in traditional Chinese medicine for the treatment of different urinary incontinence symptoms including frequency, urgency and nocturia. These symptoms are similar to the overactive bladder syndrome. In our lab, we found that the 95% ethanol extract of the capsular fruits exhibited significant anti-muscarinic activity. Some constituents in capsular fruits including flavonoids (e.g., izalpinin and tectochrysin), diarylheptanoids (e.g., yakuchinone A and yakuchinone B) and sesquiterpenes (e.g., nootkatone), are regarded as representative chemicals with putative pharmacological activities.

OBJECTIVE

This study aimed to evaluate the in vitro antagonistic actions of izalpinin on carbachol-induced contraction of the rat detrusor muscle.

MATERIALS AND METHODS

In vitro inhibition of rat detrusor contractile response to carbachol was used to study the functional activity of izalpinin. The isolated detrusor strips of rats were mounted in organ baths containing oxygenated Krebs' solution. The cumulative consecutive concentration-response curves to carbachol-evoked contractions in strips of rat bladder were obtained.

RESULTS

Carbachol induced concentration-dependent contractions of isolated rat bladder detrusor strips. The vehicle DMSO had no impact on the contraction response. The contraction effects were concentration-dependently antagonized by izalpinin, with a mean EC50 value of 0.35 µM. The corresponding cumulative agonist concentration-response curves shifted right-ward.

CONCLUSIONS

Izalpinin exhibits inhibitory role of muscarinic receptor-related detrusor contractile activity, and it may be a promising lead compound to treat overactive bladder.

Contemporary issues with pharmacotherapy for lower urinary tract symptoms

Two articles appeared in the November 2012 edition of the journal evaluating aspects relating to the use of two important pharmacotherapeutic classes for lower urinary tract symptoms (LUTS) in real life clinical practice. LUTS is a non-specific term that encompasses urine storage, voiding and postmicturition symptoms. LUTS is a common bothersome problem affecting both men and women with a comparable prevalence in age-matched patients of both sexes that increases with ageing.

Inflammation induced by mast cell deficiency rather than the loss of interstitial cells of Cajal causes smooth muscle dysfunction in W/W(v) mice

The initial hypothesis suggested that the interstitial cells of Cajal (ICC) played an essential role in mediating enteric neuronal input to smooth muscle cells. Much information for this hypothesis came from studies in W/W^v mice lacking ICC. However, mast cells, which play critical roles in regulating inflammation in their microenvironment, are also absent in W/W^v mice. We tested the hypothesis that the depletion of mast cells in W/W^v mice generates inflammation in fundus muscularis externa (ME) that impairs smooth muscle reactivity to Ach, independent of the depletion of ICC. We performed experiments on the fundus ME from wild type (WT) and W/W^v mice before and after reconstitution of mast cells by bone marrow transplant. We found that mast cell deficiency in W/W^v mice significantly increased COX-2 and iNOS expression and decreased smooth muscle reactivity to Ach. Mast cell reconstitution or concurrent blockade of COX-2 and iNOS restored smooth muscle contractility without affecting the suppression of c-kit in W/W^v mice. The expression of nNOS and ChAT were suppressed in W/W^v mice; mast cell reconstitution did not restore them. We conclude that innate inflammation induced by mast cell deficiency in W/W^v mice impairs smooth muscle contractility independent of ICC deficiency. The impairment of smooth muscle contractility and the suppression of the enzymes regulating the synthesis of Ach and NO in W/W^v mice need to be considered in evaluating the role of ICC in regulating smooth muscle and enteric neuronal function in W/W^v mice.

Pharmacotherapy of overactive bladder syndrome

Urinary incontinence is a common and distressing condition that is known to adversely affect quality of life. Overactive bladder (OAB) is the term used to describe the symptom complex of urgency with or without urge incontinence, usually with frequency and nocturia. Drug therapy, in addition to behavioral modification, remains integral in the management of women with OAB, and the development of new drugs, treatment regimens and methods of delivery should improve patient compliance and acceptability. Developments over the last 10 years have led to the launch of several new drugs for the treatment of OAB that may offer greater efficacy while minimizing adverse effects. This article critically reviews the current pharmacological treatment of OAB in addition to providing a rationale for treatment.

Modulation of nerve-evoked contractions by β3-adrenoceptor agonism in human and rat isolated urinary bladder

Activation of β3-adrenoceptors has been shown to have a direct relaxant effect on urinary bladder smooth muscle from both rats and humans, however there are very few studies investigating the effects of β3-adrenoceptor agonists on nerve-evoked bladder contractions. Therefore in the current study, the role of β3-adrenoceptors in modulating efferent neurotransmission was evaluated. The effects of β3-adrenoceptor agonism on neurogenic contractions induced by electrical field stimulation (EFS) were compared with effects on contractions induced by exogenous acetylcholine (Ach) and αβ-methylene adenosine triphosphate (αβ-meATP) in order to determine the site of action. Isoproterenol inhibited EFS-induced neurogenic contractions of human bladder (pD2=6.79; Emax=65%). The effect of isoproterenol was selectively inhibited by the β3-adrenoceptor antagonist L-748,337 (pKB=7.34). Contractions induced by exogenous Ach (0.5-1μM) were inhibited 25% by isoproterenol (3μM) while contractions to 10Hz in the same strip were inhibited 67%. The selective β3-adrenoceptor agonist CL-316,243 inhibited EFS-induced neurogenic contractions of rat bladder (pD2=7.83; Emax=65%). The effects of CL-316,243 were inhibited in a concentration dependent manner by L-748,337 (pA2=6.42). Contractions induced by exogenous Ach and αβ-meATP were significantly inhibited by CL-316,243, 29% and 40%, respectively. These results demonstrate that the activation of β3-adrenoceptors inhibits neurogenic contractions of both rat and human urinary bladder. Contractions induced by exogenously applied parasympathetic neurotransmitters are also inhibited by β3-agonism however the effect is clearly less than on neurogenic contractions (particularly in human), suggesting that in addition to a direct effect on smooth muscle, activation of prejunctional β3-adrenoceptors may inhibit neurotransmitter release.

Contractile responses of urinary bladder in an experimental model of chronic renal failure

Chronic kidney disease is a public health problem with increasing prevalence caused by diabetes, hypertension and glomerulonephritis. Number of publications investigate the lower urinary tract dysfunction due to CKD is limited. There is a high incidence of bladder dysfunction of different degrees in patients with renal failure. Mechanism of the lower urinary tract dysfunction in these patients is not well known. In this study, we aimed to investigate the effects of CKD on detrusor function in a rat model of CKD. In our study, 20 Wistar Albino rats have been divided into two groups as CKD and control groups. To the experiment group, left partial nephrectomy and right nephrectomy have been applied. CKD confirmation has done with the BUN and creatinin values from the blood of the rats. The bladder strips were prepared from the CKD and control groups and its contractile responses were evaluated in-vitro. There wasn't a considerable difference with the contractile responses caused by carbachol, KCL. There was a considerable increase in the contractile responses caused by ATP, ADP and electrical field stimulation on the behalf of the CKD group. The present study demonstrated that isolated DSM of CKD group showed significantly increased contraction responses to purinergic agonists ADP, ATP and atropine resistant component in electrical field stimulation-induced contractions as compared to those of the control group. Bladder overactivity and reduced bladder volume in CKD patients might be due to the change in purinergic system.

Overactive bladder syndrome: Current pathophysiological concepts and therapeutic approaches

Objectives

The overactive bladder syndrome (OAB) is a highly prevalent and bothersome symptom complex. We review contemporary reports to provide an update of the key aspects of its pathogenesis and the therapeutic approaches.

Methods

The PUBMED database was searched for relevant publications in the period from 1 January 1985 to 1 May 2013, using the keywords ‘overactive bladder’, ‘anti-muscarinics’, ‘β-3 agonists’, ‘intravesical botulinum toxin’, ‘tibial nerve stimulation and ‘sacral neuromodulation’.

Results

In all, 33 articles were selected for this review. OAB is very common, affecting 10–20% of the population. It is often bothersome and frequently affects the quality of life. The current definition of OAB remains a source of controversy. Anti-muscarinic agents remain the mainstay of pharmacotherapy. The new β-3 agonists have some efficacy whilst avoiding anti-cholinergic effects, and so might benefit patients who are unable to tolerate anti-muscarinic agents. Intravesical botulinum toxin is recommended for patients in whom oral pharmacotherapy fails, although the optimal parameters in terms of dosing, number of injections and injection site are yet to be fully established. Sacral neuromodulation is another option that has a good response in about half of patients.

Conclusions

OAB remains an incompletely understood problem that presents a significant management challenge. A range of therapeutic options is now available for clinicians managing this problem.

HEF-19-induced relaxation of colonic smooth muscles and the underlying mechanisms

AIM: To investigate the relaxant effect of chromane HEF-19 on colonic smooth muscles isolated from rabbits, and the underlying mechanisms.

METHODS: The relaxant effect and action mechanisms of HEF-19 were investigated using descending colon smooth muscle of the rabbits. Preparations 1 cm long were mounted in 15-mL tissue baths containing Tyrode’s solution, maintained at 37 ± 0.5 °C and aerated with a mixture of 5% CO₂ in oxygen (Carbogen). The tension and amplitude of the smooth muscle strips were recorded after adding HEF-19 (10^-6, 10^-5 and 10^-4 mol/L). After cumulative administration of four antispasmodic agents, including acetylcholine chloride (Ach) (10^-4 mol/L), histamine (10^-4 mol/L), high-K⁺ (60 mmol/L) and BaCl₂ (8.2 mmol/L), HEF-19 (3 × 10^-7-3 × 10^-4 mol/L) was added to investigate the relaxant effect of HEF-19. CaCl₂ (10^-4-2.5 × 10^-3 mol/L) was added cumulatively to the smooth muscle preparations pretreated with and without HEF-19 (1 × 10^-6 or 3 × 10^-6 mol/L) and verapamil (1 × 10^-7 mol/L) to study the mechanisms involved. Finally, phasic contraction was induced with ACh (15 × 10^-6 mol/L), and CaCl₂ (4 × 10^-3 mol/L) was added to the smooth muscle preparations pretreated with and without HEF-19 (3 × 10^-6 mol/L or 1 × 10^-5 mol/L) and verapamil (1 × 10^-7 mol/L) in calcium-free medium to further study the underlying mechanisms.

RESULTS: HEF-19 (1 × 10^-6, 1 × 10^-5 and 1 × 10^-4 mol/L) suppressed spontaneous contraction of rabbit colonic smooth muscles. HEF-19 (3 × 10^-7-3 × 10^-4 mol/L) relaxed in a concentration-dependent manner colonic smooth muscle preparations pre-contracted with BaCl₂, high-K⁺ solution, Ach or histamine with respective EC₅₀ values of 5.15 ± 0.05, 5.12 ± 0.08, 5.58 ± 0.16 and 5.25 ± 0.24, thus showing a spasmolytic activity. HEF-19 (1 × 10^-6 mol/L and 3 × 10^-6 mol/L) shifted the concentration-response curves of CaCl₂ to the right and depressed the maximum response to CaCl_2. The two components contracted by Ach were attenuated with HEF-19 (3 × 10^-6 mol/L or 10^-5 mol/L) in calcium-free medium.

CONCLUSION: HEF-19 inhibited rabbit colonic smooth muscle contraction, probably through inhibiting opening of voltage-dependent Ca²⁺ channels. HEF-19 reduced inflow and intracellular release of Ca²⁺ ions.

Cardiovascular effects of antimuscarinic agents in overactive bladder

INTRODUCTION

The potential impact of antimuscarinics (AMs) on cardiac function is a major concern in the treatment of overactive bladder (OAB) patients, especially in older ones who are likely to present cardiovascular (CV) comorbidities and other risk factors that may predispose them to the adverse cardiac effects of this therapy.

AREAS COVERED

This article aims to review the literature on the impact on the CV system of AMs used in the treatment of OAB, giving a comprehensive explanation of the pathogenetic mechanisms of AMs' effects on CV system and the impact of each AM drug on cardiac function.

EXPERT OPINION

Although the CV safety of AM drugs seems to be good, evidence provided in this manuscript does not allow to exclude an increase in HR, QT prolongation or an increase in the CV risk due to drug-drug interactions in OAB patients who are usually elderly and have comorbidities. Clinical and electrocardiographic monitoring may be necessary throughout the administration period in selected populations such as patients aged > 80 years, those with coronary heart disease or congestive heart failure. Further studies are needed to understand whether the most recently developed AM drugs, such as imidafenacin, are safer than the old ones.

[New perspectives of treatment with fesoterodine fumarate in patients with overactive bladder]

OBJECTIVE

Evaluate the effect of the treatment with fesoterodine fumarate in patients with overactive bladder, as an alternative in case of failure of the usual anticholinergic treatment, due to either lack of therapeutic efficacy or due to intolerance to side effects.

MATERIAL AND METHOD

A retrospective review of 158 patients with overactive bladder was carried out. The patients were divided into two groups; the first group; 56 patients where the anticholinergic treatment showed to be ineffective, and the second group; 102 patients who presented intolerance to anticholinergic side effects.

RESULTS

For the first group where fesoterodine fumarate was used to improve effectiveness of the anticholinergics, improvement in the components of urinary urgency (p=0.001), insufficient emptying (p=0.001), incontinence (p=0.009), and in the number of pads/day (p<0.001) was detected. As to the second group where fesoterodine fumarate was used as an alternative to anticholinergics to avoid side effects, a high reduction in the incidence of dry mouth (p<0.001) and constipation (p=0.015) was seen, as well as a significant clinical improvement.

CONCLUSION

Fesoterodine fumarate is an optimal treatment option when the clinical response to anticholinergics has not been satisfactory, either by the lack of therapeutic action or by intolerance to side effects, and especially when the treatment is expected to be long.

Autonomic nervous control of the urinary bladder

The autonomic nervous system plays an important role in the regulation of the urinary bladder function. Under physiological circumstances, noradrenaline, acting mainly on β(3) -adrenoceptors in the detrusor and on α(1) (A) -adrenoceptors in the bladder outflow tract, promotes urine storage, whereas neuronally released acetylcholine acting mainly on M(3) receptors promotes bladder emptying. Under pathophysiological conditions, however, this system may change in several ways. Firstly, there may be plasticity at the levels of innervation and receptor expression and function. Secondly, non-neuronal acetylcholine synthesis and release from the urothelium may occur during the storage phase, leading to a concomitant exposure of detrusor smooth muscle, urothelium and afferent nerves to acetylcholine and noradrenaline. This can cause interactions between the adrenergic and cholinergic system, which have been studied mostly at the post-junctional smooth muscle level until now. The implications of such plasticity are being discussed.

Pharmacokinetics and toxicity of antimuscarinic drugs for overactive bladder treatment in females

INTRODUCTION

Antimuscarinics (AMs) are the mainstay of pharmacological treatment of overactive bladder (OAB), a symptom complex defined by the presence of urinary urgency, usually associated with frequency and nocturia, with or without urgency urinary incontinence. The AMs used to treat OAB differ in their pharmacological profiles, which may affect their potential for causing adverse effects (AEs).

AREAS COVERED

The present article aims to review the literature about pharmacokinetics (PK) of the different AMs used in the treatment of OAB. Furthermore, the AEs related to the use of these drugs and their incidence are presented. This systematic review is based on material searched and obtained via Medline, Pubmed and EMBASE up to March 2012 using the search terms "adverse events, pharmacokinetics, tolerability" in combination with "darifenacin, fesoterodine, imidafenacin, oxybutynin, propiverine, solifenacin, tolterodine, and trospium."

EXPERT OPINION

Antimuscarinics are the first-line pharmacological treatment for OAB. Despite the development of new molecules that improve their efficacy/safety profile, there are some drugs that are pharmacokinetically more appropriate to be prescribed in specific populations such as patients with neurological disease or the elderly. Moreover, research should be encouraged in evaluating antimuscarinics in conjunction with other drugs such as estrogens or beta-agonists. The identification of prognostic criteria for pharmacological therapy would be helpful.