Pharmacology of the lower urinary tract: basis for current and future treatments of urinary incontinence

Cells and ionic conductances contributing to spontaneous activity in bladder and urethral smooth muscle

Smooth muscle organs of the lower urinary tract comprise the bladder detrusor and urethral wall, which have a reciprocal contractile relationship during urine storage and micturition. As the bladder fills with urine, detrusor smooth muscle cells (DSMCs) remain relaxed to accommodate increases in intravesical pressure while urethral smooth muscle cells (USMCs) sustain tone to occlude the urethral orifice, preventing leakage. While neither organ displays coordinated regular contractions as occurs in small intestine, lymphatics or renal pelvis, they do exhibit patterns of rhythmicity at cellular and tissue levels. In rabbit and guinea-pig urethra, electrical slow waves are recorded from USMCs. This activity is linked to cells expressing vimentin, c-kit and Ca2+-activated Cl- channels, like interstitial cells of Cajal in the gastrointestinal tract. In mouse, USMCs are rhythmically active (firing propagating Ca2+ waves linked to contraction), and this cellular rhythmicity is asynchronous across tissues and summates to form tone. Experiments in mice have failed to demonstrate a voltage-dependent mechanism for regulating this rhythmicity or contractions in vitro, suggesting that urethral tone results from an intrinsic ability of USMCs to 'pace' their own Ca2+ mobilization pathways required for contraction. DSMCs exhibit spontaneous transient contractions, increases in intracellular Ca2+ and action potentials. Consistent across numerous species, including humans, this activity relies on voltage-dependent Ca2+ influx in DSMCs. While interstitial cells are present in the bladder, they do not 'pace' the organ in an excitatory manner. Instead, specialized cells (PDGFRα+ interstitial cells) may 'negatively pace' DSMCs to prevent bladder overexcitability.

Pharmacological Modulation of Intrarenal Pressure in a Porcine Model Using a Novel Isoprenaline-Eluting Guidewire

Introduction: Several complications of retrograde intrarenal surgery have been attributed to inadvertent increases in intrarenal pressure. We recently described the development of an innovative isoprenaline-eluting guidewire (IsoWire). The objective of this study was to investigate the impact of this IsoWire on the intrarenal pressure and evaluate its safety. Materials and Methods: This study was performed in 17 renal units using a porcine model. As controls, the intrarenal pressure, heart rate, and mean arterial pressure were measured for a duration of six minutes with a standard guidewire placed in the renal pelvis. For the experiment, the conventional guidewire was substituted with the IsoWire and the same parameters were measured. Blood samples were taken at one-minute intervals to measure plasma isoprenaline levels. This procedure was repeated on the opposite side. Results: The mean intrarenal pressure reduction was 29% (95% CI: 13%-53%). The mean isoprenaline effect time was 174 seconds. No changes in heart rate (p = .908) or mean arterial pressure (p = .749) were recorded after IsoWire insertion. Plasma isoprenaline levels were below the quantitation threshold. Isoprenaline concentrations in the plasma were below the quantification threshold. Ureteroscopy revealed no ureteral lesions. Conclusions: The IsoWire demonstrated a safe and effective reduction of intrarenal pressure. Additional research is necessary to determine whether ureteral smooth muscle relaxation generated by isoprenaline facilitates easier insertion of a ureteral access sheath, decreases the incidence of ureteral access sheath related ureteral lesions, or even encourage the practice of sheathless retrograde intrarenal surgery.

Introducing an lsoprenaline Eluting Guidewire: Report on its Design and the Results of the Dose-Determining Pilot Study

Introduction: Retrograde intrarenal surgery (RIRS) is associated with complications, many of which are related to the intrarenal pressure (IRP). We aim to describe the design of a novel isoprenaline-eluting guidewire ("IsoWire") and present the results from the first in vitro release studies and the first animal studies showing its effect on IRP. Materials and Methods: The IsoWire comprises a Nitinol core surrounded by a stainless-steel wire wound into a tight coil. The grooves created by this coil provided a reservoir for adding a hydrogel coating into which isoprenaline, a beta-agonist, was loaded. Animal studies were performed using a porcine model. For the control, IRP, heart rate (HR), and mean arterial pressure (MAP) were measured continuously for 6 minutes with a standard guidewire in place. For the experiment, the standard hydrophilic guidewire was removed, the IsoWire was inserted into the renal pelvis, and the same parameters were measured. Results: In vitro analysis of the isoprenaline release profile showed that most (63.9 ± 5.9%) of the loaded drug mass was released in the 1st minute, and almost all of the drug was released in the first 4 minutes exponentially. Porcine studies showed a 25.1% reduction in IRP in the IsoWire that released 10 μg in the 1st minute; however, there was a marked increase in HR. The average percentage reduction in IRP was 8.95% and 21.3% in the IsoWire that released 5 and 7.5 μg of isoprenaline, respectively, with no changes in HR or MAP. Conclusions: The IsoWire, which releases 5 and 7.5 μg of isoprenaline in the 1st minute, appears to be safe and effective in reducing the IRP. Further studies are needed to establish whether the isoprenaline-induced ureteral relaxation will render easier insertion of a ureteral access sheath, reduce IRP during sheathless RIRS, or even promote the practice of sheathless RIRS.

Transperineal pelvic floor ultrasound in male

INTRODUCTION

The pelvic floor (PF) is a highly complex structure which may be affected by various stimulating factors like decreased PF support. As ultrasound can dynamically observe the position and mobility of anatomical structures, However, there are very few studies on PF ultrasound in males.

MATERIALS AND METHODS

Twenty-one male patients with normal conditions underwent transperineal pelvic floor ultrasound (TPFU) examination. Ultrasound was performed in a supine lithotomy position. The probe was pressed on the sagittal plane of the perineum and adjusted till the anorectal angle, as well as bladder, were located and the median prostate and pubic symphysis were visible on the sagittal plane. TPFU was carried out to observe the patterns of pelvic floor movement during different phases, measure ultrasound parameters of the PF in men, and assess the potential applications and prospects of the male PF.

RESULTS

Two-dimensional male PF ultrasound can detect the bladder, prostate, male urethra, anus, rectum. Resting, Valsalva, and contraction phases of the PF are clearly shown, the pelvic organs in the Valsalva phase shift to the dorsal foot side, and shift to the cephalic ventral side when the levator ani muscle (LAM) contracts. Three-dimensional male PF ultrasound can visually show the shape and structure of the levator ani muscle hiatus.

CONCLUSION

It is a feasible examination tool for detecting PF disorders. However, there are still many fields to explore in the future.

Does multiple-component intensive pelvic floor muscle training decrease muscle fatigue and symptoms in women with urinary incontinence?

INTRODUCTION AND HYPOTHESIS

A multiple-component intensive pelvic floor muscle training (MCI-PFMT) protocol was developed as a neurophysiological-based rehabilitation model to improve neuroplasticity. This study aimed to investigate the effects of the MCI-PFMT protocol on muscle fatigue and symptoms in women with urinary incontinence.

METHODS

This randomized controlled trial included 49 female patients with mixed urinary incontinence. Participants were divided into the MCI-PFMT group and the control group. The MCI-PFMT group performed supervised intensive pelvic floor muscle training, while the control group received bladder training and standard pelvic floor muscle training as a home program. Both training sessions were conducted 5 days a week for a single week. Participants' symptoms were evaluated with questionnaires, bladder diary, and pad tests. Superficial electromyography, ultrasonography, and the PERFECT scale were used to evaluate pelvic floor and abdominal muscle functions.

RESULTS

In the post-treatment evaluation, symptoms were decreased in both groups, with a significant decrease in the MCI-PFMT group (p < 0.05). While average and peak work values of pelvic floor muscles, transversus abdominus, and internal oblique muscles increased in both groups, maximum voluntary contraction values of these muscles decreased (p < 0.05). A 12.7% decrease was observed in the maximum voluntary contraction values of pelvic floor muscles in the control group, while a 9.6% decrease was observed in the MCI-PFMT group.

CONCLUSIONS

The MCI-PFMT protocol can lead to pelvic floor and abdominal muscle fatigue. However, it may be effective at decreasing symptoms in women with urinary incontinence. Additional studies on this issue are needed.

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.

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 differences in the adrenergic receptors of proximal urethra between sexes

Objectives

The bladder and urethra work as a physiologically functional unit to facilitate continence in the storage and voiding phase. Sex differences have been found in the urethral contraction in response to α-adrenergic receptor activation. This study aimed to investigate the role of adrenergic receptors in the proximal urethra of male and female mice.

Materials and Methods

Urinary bladder and proximal urethral smooth muscle (USM) samples from male and female C57BL/6 mice were isolated and mounted in an organ bath.

Results

Acetylcholine-induced contraction of the urinary bladder was compared in male and female mice. Phenylephrine and norepinephrine (NE) induced little contraction at a lower concentration, but a relaxing phase of female proximal USM was observed at a higher concentration. This contraction profile was inhibited by NG-nitro-L-arginine, lidocaine, and capsaicin. In addition, the NE-induced contraction was greater in the incubation of propranolol than that of L-NNA or lidocaine. These results suggested that the β-adrenoceptor may be the dominant receptor of female proximal USM, and the activity of calcitonin gene-related peptide sensory nerves and nitrergic nerves may pose an anti-contraction effect on the proximal urethra in female mice.

Conclusion

β-adrenoceptor may be the dominant receptor of female proximal USM. The use of β-adrenergic receptor blocker agents might have the potential for the treatment of female voiding dysfunction.

Urological Aspects of Spinal Dysraphism

Micturition requires complex interplay involving bladder, peripheral neural network, spinal cord, and brain. Spinal dysraphism presents variety of neural lesions that may affect this interplay leading to neurogenic bladder. However, the diagnosis of neurogenic bladder in those with spinal dysraphism is often difficult and contrasted to other types of neurogenic bladder caused by complete neural lesions such as spinal cord injury or brain tumor. Typically, neurogenic bladder caused by spinal dysraphism shows lower motor neuron lesion and partial neural injury. However, upper motor signs can be seen with the occurrence of tethered cord syndrome and developmental immaturity of bladder control often complicated by fecal impaction. Thus, the diagnosis of tethered cord syndrome should be made cautiously. Several invasive and noninvasive diagnostic modalities could be applied for accurate diagnosis, preventing renal damage and controlling urinary incontinence. However, it should be borne in mind that no single study is definitive for accurate diagnosis, so it requires careful scrutiny in interpretation. The follow-up scheme of these patients should be determined to detect urological deterioration due to the development of tethered cord syndrome. Since the development of tethered cord syndrome shows diverse nature implicating urological and orthopedic issues, multidisciplinary collaboration is essential for comprehensive care.

Effect of Bladder Injection of OnabotulinumtoxinA on the Central Expression of Genes Associated with the Control of the Lower Urinary Tract: A Study in Normal Rats

To investigate a possible central mechanism of action of Botulinum toxin A (BoNT/A) following injection in the bladder, complementary to the acknowledged peripheral bladder effect, we studied changes in the expression of neuropeptides and receptors involved in lower urinary tract function in the spinal cord (SC) and dorsal root ganglia (DRG) of normal rats following BoNT/A bladder injection. Thirty-six Sprague-Dawley rats, divided into three groups of n = 12, received bladder injections of 2U or 5U OnabotulinumtoxinA (BOTOX^®), or saline. Six animals from each group were sacrificed on days 7 and 14. Expression of Tachykinin 1 (Tac1), capsaicin receptor (TRPV1), neuropeptide Y (NPY), proenkephalin (PENK) and muscarinic receptors M1, M2, M3, was evaluated in the bladder, L6-S1 DRG, and SC segments using real-time PCR and Western blotting. Real-time PCR revealed increased expression of NPY in all tissues except for SC, and increased TRPV1 and PENK expression in DRG and SC, whereas expression of Tac1, M1 and M2 was decreased. Less significant changes were noted in protein levels. These findings suggest that bladder injections of OnabotulinumtoxinA may be followed by changes in the expression of sensory, sympathetic and cholinergic bladder function regulators at the DRG/SC level.

Daidzein attenuates urinary bladder dysfunction in streptozotocin-induced diabetes in rats by NOX-4 and RAC-1 inhibition

Reactive oxygen species via NADPH oxidase (NOX) activation are involved in the pathogenesis of many disease conditions such as diabetes and its complications. In the present study, we have examined the effect of daidzein in the management of diabetic cystopathy. Diabetes was induced in male Sprague Dawley rats via intraperitoneal injection of streptozotocin (STZ) at a dose of 55 mg/kg. After 6 weeks of diabetes induction, animals were treated with daidzein orally at a dose of 25, 50, and 100 mg/kg for 4 weeks. Diabetic animals showed increase (p < 0.001) in bladder capacity (4.32 ± 0.43 mL) and residual volume (2.53 ± 0.19 mL) when compared with normal control animals (2.10 ± 0.40 mL and 0.51 ± 0.12 mL res). Treatment with daidzein at dose of 50 and 100 mg/kg significantly reduced the elevated bladder capacity (2.91 ± 0.11 mL, p < 0.01 and 2.65 ± 1.13 mL, p < 0.001) and residual volume (1.40 ± 0.15 mL, p < 0.001 and 1.15 ± 0.05 mL, p < 0.001). Daidzein-treated animals also showed improvement in voiding efficiency. Elevated threshold and baseline pressure were also found to be reduced in diabetic animals after 4 weeks of daidzein treatment. Daidzein treatment also prevented the loss of antioxidant enzymes in the urinary bladder and also reduced the expression of NOX-4 and RAC-1 in the bladder. From the results, it can be concluded that daidzein showed a beneficial effect on urinary bladder dysfunction in diabetic animals.

The Efficacy and Safety of Transurethral 2 μm Laser Bladder Lesion Mucosal En Bloc Resection in the Treatment of Cystitis Glandularis

Objective

To study the safety and feasibility of transurethral bladder lesion mucosal en bloc resection with 2 μm laser for cystitis glandularis.

Methods

From July 2018 to July 2019, 58 patients with cystitis glandularis received surgical treatment were selected. All patients in this study were randomly divided into experimental group (transurethral 2 μm laser bladder lesion mucosal en bloc resection) and control group (traditional transurethral resection of bladder lesion mucosal). By analyzing the perioperative and follow-up clinical data of these two operation procedures, we discuss the efficacy and safety of transurethral 2 μm laser bladder lesion mucosal en bloc resection in the treatment of cystitis glandularis.

Results

Patients of two groups received operation successfully without serious complications such as bladder perforation. Compared with the experimental group, the laser treated group hadless bleeding in operation, shorter post-operative catheter indwelling time. These differences were statistically significant. No significant difference existed between two groups in terms of operative time, Bladder flushing time, irritation symptoms of bladder.

Conclusion

Transurethral 2 μm laser bladder lesion mucosal en bloc resection is safe and effective for the treatment of cystitis glandularis, and it is worthy of further clinical application.

Bladder diverticulum caused by primary bladder neck obstruction

Here, we report a case of a patient in their mid 30s who presented with an elevated creatinine and was found to have a massive bladder diverticulum. The patient underwent a robotic-assisted diverticulectomy. They were later found to have a primary bladder neck obstruction on video urodynamics, and subsequently, underwent bladder neck incision, leading to significant improvement in urinary symptoms. Primary bladder neck obstruction is an overlooked cause of bladder diverticulum. While cystoscopy and cross-sectional imaging are frequently used in the initial evaluation of bladder diverticula, in the absence of an anatomic obstruction such as prostate enlargement, video urodynamics should be performed to assess for primary bladder neck obstruction.

Treatment strategies for clozapine-induced nocturnal enuresis and urinary incontinence: a systematic review

BACKGROUND

Clozapine is the most effective medication for treatment-refractory schizophrenia but is associated with significant adverse drug reactions, including nocturnal enuresis and urinary incontinence. This side effect can be burdensome and lead to medication nonadherence and psychotic relapse. Evidence to guide treatment of clozapine-induced nocturnal enuresis and urinary incontinence is sparse. We therefore aimed to synthesize the evidence base to guide management for clinicians, patients, and their carers.

METHODS

We systematically searched PubMed, Embase, PsycInfo, CINAHL, and the Cochrane Trial Registry databases from inception to May 2021 for publications on management of clozapine-induced nocturnal enuresis and urinary incontinence using a PROSPERO preregistered search strategy.

RESULTS

We identified 22 case reports and case series describing 74 patients. Interventions included clozapine dose reduction, nonpharmacological treatment, and pharmacological treatments. Among pharmacological treatments, desmopressin, oxybutynin, trihexyphenidyl, tolterodine, imipramine, amitriptyline, ephedrine, pseudoephedrine, aripiprazole, and verapamil were associated with complete resolution of nocturnal enuresis and urinary incontinence. Balancing evidence for effectiveness against risk of adverse effects, we developed a management framework for clozapine-induced nocturnal enuresis and urinary incontinence.

CONCLUSIONS

Following assessment of urological, psychiatric, pharmacological, and common comorbid medical issues, first-line treatments should be nonpharmacological, including bathroom alarms, voiding before bedtime, and nocturnal fluid restriction. If these interventions do not provide adequate relief, aripiprazole should be trialed. Desmopressin may be considered for severe refractory cases, but monitoring for hyponatremia is essential.

Current knowledge and novel frontiers in lower urinary tract dysfunction after spinal cord injury: Basic research perspectives

This review article aims to summarize the recent advancement in basic research on lower urinary tract dysfunction (LUTD) following spinal cord injury (SCI) above the sacral level. We particularly focused on the neurophysiologic mechanisms controlling the lower urinary tract (LUT) function and the SCI-induced changes in micturition control in animal models of SCI. The LUT has two main functions, the storage and voiding of urine, that are regulated by a complex neural control system. This neural system coordinates the activity of two functional units in the LUT: the urinary bladder and an outlet including bladder neck, urethra, and striated muscles of the pelvic floor. During the storage phase, the outlet is closed and the bladder is quiescent to maintain a low intravesical pressure and continence, and during the voiding phase, the outlet relaxes and the bladder contracts to promote efficient release of urine. SCI impairs voluntary control of voiding as well as the normal reflex pathways that coordinate bladder and sphincter function. Following SCI, the bladder is initially areflexic but then becomes hyperreflexic due to the emergence of a spinal micturition reflex pathway. However, the bladder does not empty efficiently because coordination between the bladder and urethral sphincter is lost. In animal models of SCI, hyperexcitability of silent C-fiber bladder afferents is a major pathophysiological basis of neurogenic LUTD, especially detrusor overactivity. Reflex plasticity is associated with changes in the properties of neuropeptides, neurotrophic factors, or chemical receptors of afferent neurons. Not only C-fiber but also Aδ-fiber could be involved in the emergence of neurogenic LUTD such as detrusor sphincter dyssynergia following SCI. Animal research using disease models helps us to detect the different contributing factors for LUTD due to SCI and to find potential targets for new treatments.

Sophisticated regulation of micturition: review of basic neurourology

The neurological regulation of the lower urinary tract can be viewed separately from the perspective of sensory neurons and motor neurons. First, in the receptors of the bladder and urethra of sensory nerves, sensations are transmitted through the periaqueductal gray matter of the midbrain to the cerebral cortex, and the cerebrum goes through the process of decision-making. Motor neurons are divided into upper motor neurons (UMNs) and lower motor neurons (LMNs). UMNs coordinate storage and micturition in the brain stem so that synergic voiding can occur. LMNs facilitate muscle contractions in the spinal cord. The muscles involved in urinary storage and micturition are innervated by the somatic branches of sympathetic, parasympathetic, and peripheral nerves. Sympathetic nerves are responsible for contractions of urethral smooth muscles, while parasympathetic nerves originate from S2–S4 and are in charge of contractions of the bladder muscle. Somatic nerves originate from the motor neurons in Onuf’s nucleus, which is a specific part of somatic nerves. In this review, we will investigate the structures of the nervous systems related to the lower urinary tract and the regulatory system of innervation for the urinary storage and micturition and discuss the clinical significance and future prospects of neurourological research.

Psychiatric History and Overactive Bladder Symptom Severity in Ambulatory Urogynecological Patients

Introduction and hypothesis: A link between psychiatric comorbidities and overactive bladder symptomatology has been suggested by preclinical and clinical studies. Given this, we hypothesized that a psychiatric history and current treatment with psychotropic medications could be related to the severity of overactive bladder and incontinence symptoms in patients referred to a tertiary care urogynecological center. Methods: One hundred and twenty-seven female patients diagnosed with an overactive bladder were screened for a lifetime history of psychiatric disorders and the type and number of psychotropic medications currently taken. The overall severity of overactive bladder symptoms was assessed using the Indevus Urgency Severity Scale. The severity and impact of urinary incontinence on the quality of life were quantified with the International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form. Urinary incontinence was further quantified with the aid of the Urinary Distress Inventory-6. The patients were screened for stress urinary incontinence using the Stamey Incontinence Score. Results: A psychiatric history, as well as current use of at least two psychotropic medications, was associated with increased severity of overactive bladder symptoms. A history of depression and current treatment with any selective serotonin reuptake inhibitor was associated with increased severity of stress urinary incontinence symptoms. Current treatment with other psychotropic medications, including sedative-hypnotics and drugs with anticholinergic properties was not related to the severity of overactive bladder and incontinence symptoms.

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.

ATP as a cotransmitter in sympathetic and parasympathetic nerves - another Burnstock legacy

Geoff Burnstock created an outstanding scientific legacy that includes identification of adenosine 5'-triphosphate (ATP) as an inhibitory neurotransmitter in the gut, the discovery and characterisation of a large family of purine and uridine nucleotide-sensitive ionotropic P2X and metabotropic P2Y receptors and the demonstration that ATP is as an excitatory cotransmitter in autonomic nerves. The evidence for cotransmission includes that: 1) ATP is costored with noradrenaline in synaptic vesicles in postganglionic sympathetic nerves innervating smooth muscle tissues, including the vas deferens and most arteries. 2) When coreleased with noradrenaline, ATP acts at postjunctional P2X1 receptors to elicit depolarisation, Ca²⁺ influx, Ca²⁺ sensitisation and contraction. 3) ATP is also coreleased with acetylcholine from postganglionic parasympathetic nerves innervating the urinary bladder, where it stimulates postjunctional P2X1 receptors, and a second, as yet unidentified site to evoke contraction of detrusor smooth muscle. In both systems membrane-bound ecto-enzymes and soluble nucleotidases released from postganglionic nerves dephosphorylate ATP and so terminate its neurotransmitter actions. Currently, the most promising potential area of therapeutic application relating to cotransmission is treatment of dysfunctional urinary bladder. This family of disorders is associated with the appearance of a purinergic component of neurogenic contractions. This component is an attractive target for drug development and targeting it may be a rewarding area of research.

NMDAR in bladder smooth muscle is not a pharmacotherapy target for overactive bladder in mice

Overactive bladder (OAB) is a common condition that affects a significant patient population. The N-methyl-D-aspartate receptor (NMDAR) has a role in developing bladder overactivity, pharmacological inhibition of which inhibits bladder overactivity. The common pathogenesis of OAB involves bladder smooth muscle (BSM) overactivity. In this study, a smooth muscle-specific NMDAR knockout (SMNRKO) mouse model was generated. The bladders from SMNRKO mice displayed normal size and weight with an intact bladder wall and well-arranged BSM bundles. Besides, SMNRKO mice had normal voiding patterns and urodynamics and BSM contractility, indicating that NMDAR in BSM was not essential for normal physiological bladder morphology and function. Unexpectedly, cyclophosphamide (CYP)-treated SMNRKO and wild-type (WT) mice had similar pathological changes in the bladder. Furthermore, SMNRKO mice displayed similar altered voiding patterns and urodynamic abnormalities and impaired BSM contractility compared with WT mice after CYP treatment. MK801 partially reversed the pathological bladder morphology and improved bladder dysfunction induced by CYP, but did not cause apparent differences between WT mice and SMNRKO mice, suggesting that NMDAR in BSM was not involved in pathological bladder morphology and function. Moreover, the direct instillation of NMDAR agonists or antagonists into the CYP-induced OAB did not affect bladder urodynamic function, indicating that NMDAR in BSM was not the pharmacotherapy target of MK801 for CYP-induced cystitis. The findings indicated that NMDAR in BSM was not essential for normal physiological or pathological bladder morphology and function, and MK801 improving pathological bladder function was not mediated by an action on NMDAR in BSM.

Age-dependent decrease in TRPM4 channel expression but not trafficking alters urinary bladder smooth muscle contractility

During development, maturation, or aging, the expression and function of urinary bladder smooth muscle (UBSM) ion channels can change, thus affecting micturition. Increasing evidence supports a novel role of transient receptor potential melastatin‐4 (TRPM4) channels in UBSM physiology. However, it remains unknown whether the functional expression of these key regulatory channels fluctuates in UBSM over different life stages. Here, we examined TRPM4 channel protein expression (Western blot) and the effects of TRPM4 channel inhibitors, 9‐phenanthrol and glibenclamide, on phasic contractions of UBSM isolated strips obtained from juvenile (UBSM‐J, 5–9 weeks old) and adult (UBSM‐A, 6–18 months old) male guinea pigs. Compared to UBSM‐J, UBSM‐A displayed a 50–70% reduction in total TRPM4 protein expression, while the surface‐to‐intracellular expression ratio (channel trafficking) remained the same in both age groups. Consistent with the reduced total TRPM4 protein expression in UBSM‐A, 9‐phenanthrol showed lower potencies and/or maximum efficacies in UBSM‐A than UBSM‐J for inhibiting amplitude and muscle force of spontaneous and 20 mM KCl‐induced phasic contractions. Compared to 9‐phenanthrol, glibenclamide also attenuated both spontaneous and KCl‐induced contractions, but with less pronounced differential effects in UBSM‐A and UBSM‐J. In both age groups, regardless of the overall reduced total TRPM4 protein expression in UBSM‐A, cell surface TRPM4 protein expression (~80%) predominated over its intracellular fraction (~20%), revealing preserved channel trafficking mechanisms toward the cell membrane. Collectively, this study reports novel findings illuminating a fundamental physiological role for TRPM4 channels in UBSM function that fluctuates with age.

The urethra in continence and sensation: Neural aspects of urethral function

AIMS

Traditionally, the urethra has been considered a mere conduit to guide urine from the bladder to the external side of the body. Building evidence indicates that the urethra may directly influence bladder function via mechanisms restricted to the lower urinary tract (LUT).

METHODS

Here, we discuss the tissue arrangement of the urethra and addressed the contribution of new paraneuronal cells to LUT function. We also briefly reviewed two frequent LUT pathologies associated with urethral dysfunction.

RESULTS

Continence depends on an intact and functional urethral sphincter, composed of smooth, and striated muscle fibers and regulated by somatic and autonomic fibers. Recent studies suggest the existence of an urethro-vesical reflex that also contributes to normal LUT function. Indeed, the urethral lumen is lined by a specialized epithelium, the urothelium, in the proximal urethra. In this region, recent evidence demonstrates the presence of specific paraneuronal cells, expressing the neurotransmitters acetylcholine and serotonin. These cells are in close proximity of nerve fibers coursing in the lamina propria and are able to release neurotransmitters and rapidly induce detrusor contractions, supporting the existence of an urethro-vesical crosstalk.

CONCLUSION

The mechanism underlying the fast communication between the urethra and thebladder are beginning to be understood and should involve the interaction between specificepithelial cells and fibres innervating the urethral wall. It is likely that this reflex should bealtered in pathological conditions, becoming an attractive therapeutic target.

Role of Ano1 Ca2+-activated Cl- channels in generating urethral tone

Urinary continence is maintained in the lower urinary tract by the contracture of urethral sphincters, including smooth muscle of the internal urethral sphincter. These contractions occlude the urethral lumen, preventing urine leakage from the bladder to the exterior. Over the past 20 years, research on the ionic conductances that contribute to urethral smooth muscle contractility has greatly accelerated. A debate has emerged over the role of interstitial cell of Cajal (ICC)-like cells in the urethra and their expression of Ca²⁺-activated Cl^- channels encoded by anoctamin-1 [Ano1; transmembrane member 16 A (Tmem16a) gene]. It has been proposed that Ano1 channels expressed in urethral ICC serve as a source of depolarization for smooth muscle cells, increasing their excitability and contributing to tone. Although a clear role for Ano1 channels expressed in ICC is evident in other smooth muscle organs, such as the gastrointestinal tract, the role of these channels in the urethra is unclear, owing to differences in the species (rabbit, rat, guinea pig, sheep, and mouse) examined and experimental approaches by different groups. The importance of clarifying this situation is evident as effective targeting of Ano1 channels may lead to new treatments for urinary incontinence. In this review, we summarize the key findings from different species on the role of ICC and Ano1 channels in urethral contractility. Finally, we outline proposals for clarifying this controversial and important topic by addressing how cell-specific optogenetic and inducible cell-specific genetic deletion strategies coupled with advances in Ano1 channel pharmacology may clarify this area in future studies.NEW & NOTEWORTHY Studies from the rabbit have shown that anoctamin-1 (Ano1) channels expressed in urethral interstitial cells of Cajal (ICC) serve as a source of depolarization for smooth muscle cells, increasing excitability and tone. However, the role of urethral Ano1 channels is unclear, owing to differences in the species examined and experimental approaches. We summarize findings from different species on the role of urethral ICC and Ano1 channels in urethral contractility and outline proposals for clarifying this topic using cell-specific optogenetic approaches.

Catheter-Related Bladder Discomfort: How Can We Manage It?

The urethral catheter is used in various clinical situations such as diagnosing urologic disease, urine drainage in patients after surgery, and for patients who cannot urinate voluntarily. However, catheters can cause numerous adverse effects, such as catheter-associated infection, obstruction, bladder stones, urethral injury, and catheter-related bladder discomfort (CRBD). CRBD symptoms vary among patients from burning sensation and pain in the suprapubic and penile areas to urinary urgency. CRBD significantly reduces patient quality of life and can lead to several complications. CRBD is caused by catheter-induced bladder irritation due to muscarinic receptor-mediated involuntary contractions of bladder smooth muscle and also can be caused by mechanical stimulus of the urethral catheter. Various pharmacologic studies for managing CRBD, including antimuscarinic and antiepileptic agents and botulinum toxin injections have been reported. If urologists can reduce patients’ CRBD, their quality of life and recovery can improve.

PGE2 receptors in detrusor muscle: Drugging the undruggable for urgency

Overactive bladder (OAB) syndrome is a prevalent condition of the lower urinary tract that causes symptoms, such as urinary frequency, urinary urgency, urge incontinence, and nocturia, and disproportionately affects women and the elderly. Current medications for OAB merely provide symptomatic relief with considerable limitations, as they are no more than moderately effective, not to mention that they may cause substantial adverse effects. Identifying novel molecular targets to facilitate the development of new medical therapies with higher efficacy and safety for OAB is in an urgent unmet need. Although the molecular mechanisms underlying the pathophysiology of OAB largely remain elusive and are likely multifactorial, mounting evidence from preclinical studies over the past decade reveals that the pro-inflammatory pathways engaging cyclooxygenases and their prostanoid products, particularly the prostaglandin E2 (PGE₂), may play essential roles in the progression of OAB. The goals of this review are to summarize recent progresses in our knowledge on the pathogenic roles of PGE₂ in the OAB and to provide new mechanistic insights into the signaling pathways transduced by its four G-protein-coupled receptors (GPCRs), i.e., EP1-EP4, in the overactive detrusor smooth muscle. We also discuss the feasibility of targeting these GPCRs as an emerging strategy to treat OAB with better therapeutic specificity than the current medications.

Light-controlled calcium signalling in prostate cancer and benign prostatic hyperplasia

Background

Identifying ways to reduce the burden of prostate cancer (Pca) or benign prostatic hyperplasia (BPH) is a top research priority. It is a typical entanglement seen in men which is portrayed by trouble in micturition. It stands as a significant problem in our society. Different molecular biomarker has high potential to treat Pca or BPH but also causes serious side effects during treatment.

Main text

The role of calcium signalling in the alteration of different biomarkers of Pca or BPH is important. Therefore, the photoswitch drugs may hold the potential to rebalance the altered calcium signaling cascade and the biomarker levels. Thereby play a significant role in the management of Pca and BPH. Online literature searches such as PubMed, Web of Science, Scopus, and Google Scholar were carried out. The search terms used for this review were photo-pharmacology, photo-switch drug, photodynamic therapy, calcium signalling, etc. Present treatment of Pca or BPH shows absence of selectivity and explicitness which may additionally result in side effects. The new condition of the calcium flagging may offer promising outcomes in restoring the present issues related with prostate malignancy and BPH treatment.

Conclusion

The light-switching calcium channel blockers aim to solve this issue by incorporating photo-switchable calcium channel blockers that may control the signalling pathway related to proliferation and metastasis in prostate cancer without any side effects.

Graphical abstract

Schematic diagram explaining the proposed role of photo-switch therapy in curbing the side effects of active drugs in Pca (prostate cancer) and BPH (benign prostatic hyperplasia). a) Delivery of medication by ordinary strategies and irreversible phototherapy causes side effects during treatment. Utilization of photo-switch drug to control the dynamic and inert condition of the medication can cause the medication impacts as we required in prostate cancer and BPH. b) Support of harmony between the calcium signaling is essential to guarantee ordinary physiology. Increment or abatement in the dimensions of calcium signaling can result in changed physiology. c) Major factors involved in the pathogenesis of BPH; downregulation of vitamin D receptor (VDR) and histone deacetylase (HDAC) can prevent BPH. Similarly, downregulation of α-1 adrenoceptor can reduce muscle contraction, while overexpression of β-3 adrenoceptor in BPH can promote further muscle relaxation in BPH treatment therapy. Inhibition of overexpressed biomarkers in BPH TRPM2-1: transient receptor potential cation channel subfamily M member 1; TRPM2-2: transient receptor potential cation channel subfamily M member 2; Androgens; CXCL5: C-X-C motif chemokine ligand 5; TGFβ-1: transforming growth factor β-1; TXA2; thromboxane-2; NMDA: N-methyl-d-aspartate can be the potential target in BPH therapy.

Effects of various catheter fix sites on catheter-associated lower urinary tract symptoms

The present study aimed to compare the effects of various catheter fix sites on catheter-associated lower urinary tract symptoms (CALUTS) in 450 patients who underwent surgical removal of upper urinary calculi 24 h earlier. All patients had 16 French Foley catheters inserted and the balloons were filled. In group A, the catheters were fixed on the top one-third of the thigh. In group B, the catheters were fixed on the abdominal wall. Patients in whom the catheters were neither fixed on the thigh nor abdominal wall were designated as controls. There were 150 patients in each group. CALUTS, such as frequency, urgency, burning during micturition, odynuria, bladder pain and other symptoms, including urethral discharge, a red and swollen external urethral orifice, catheter traction or blockage and catheter-associated discomfort were recorded. Patients in group A compared with the control group had a significantly lower incidence of frequency, urgency, odynuria, urethral discharge, catheter traction and catheter-associated discomfort (P<0.05). Patients in group B were observed to have a significantly lower incidence of urgency, urethral discharge, catheter traction and catheter-associated discomfort compared with the control group (P<0.05), but a higher incidence of odynuria, urethral pain, urethral discharge and a red and swollen external urethral orifice compared with group A (P<0.05). An additional catheter fixation site for bedridden patients was necessary and an additional fix site on the thigh was preferred to the abdominal wall, which may further reduce catheter-associated lower urinary tract symptoms.

The intracellular Ca2+ release channel TRPML1 regulates lower urinary tract smooth muscle contractility

TRPML1 (transient receptor potential mucolipin 1) is a Ca²⁺-permeable, nonselective cation channel that is localized to late endosomes and lysosomes. Here, we investigated the function of TRPML1 channels in regulating lower urinary tract (LUT) smooth muscle cell (SMC) contractility. We found that TRPML1 forms a stable signaling complex with ryanodine receptors (RyRs) in the sarcoplasmic reticulum (SR). We further showed that TRPML1 channels are important for initiating an essential Ca²⁺-signaling negative feedback mechanism between RyRs on SR membranes and K⁺ channels on the plasma membrane. Knockout of TRPML1 channels in mice impaired this pathway, resulting in LUT smooth muscle hypercontractility and symptoms of overactive bladder. Our findings demonstrate a critical role for TRPML1 in LUT function.

TRPML1 (transient receptor potential mucolipin 1) is a Ca²⁺-permeable, nonselective cation channel that is predominantly localized to the membranes of late endosomes and lysosomes (LELs). Intracellular release of Ca²⁺ through TRPML1 is thought to be pivotal for maintenance of intravesicular acidic pH as well as the maturation, fusion, and trafficking of LELs. Interestingly, genetic ablation of TRPML1 in mice (Mcoln1^−/−) induces a hyperdistended/hypertrophic bladder phenotype. Here, we investigated this phenomenon further by exploring an unconventional role for TRPML1 channels in the regulation of Ca²⁺-signaling activity and contractility in bladder and urethral smooth muscle cells (SMCs). Four-dimensional (4D) lattice light-sheet live-cell imaging showed that the majority of LELs in freshly isolated bladder SMCs were essentially immobile. Superresolution microscopy revealed distinct nanoscale colocalization of LEL-expressing TRPML1 channels with ryanodine type 2 receptors (RyR2) in bladder SMCs. Spontaneous intracellular release of Ca²⁺ from the sarcoplasmic reticulum (SR) through RyR2 generates localized elevations of Ca²⁺ (“Ca²⁺ sparks”) that activate plasmalemmal large-conductance Ca²⁺-activated K⁺ (BK) channels, a critical negative feedback mechanism that regulates smooth muscle contractility. This mechanism was impaired in Mcoln1^−/− mice, which showed diminished spontaneous Ca²⁺ sparks and BK channel activity in bladder and urethra SMCs. Additionally, ex vivo contractility experiments showed that loss of Ca²⁺ spark–BK channel signaling in Mcoln1^−/− mice rendered both bladder and urethra smooth muscle hypercontractile. Voiding activity analyses revealed bladder overactivity in Mcoln1^−/− mice. We conclude that TRPML1 is critically important for Ca²⁺ spark signaling, and thus regulation of contractility and function, in lower urinary tract SMCs.

Detrusor Smooth Muscle KV7 Channels: Emerging New Regulators of Urinary Bladder Function

Relaxation and contraction of the urinary bladder smooth muscle, also known as the detrusor smooth muscle (DSM), facilitate the micturition cycle. DSM contractility depends on cell excitability, which is established by the synchronized activity of multiple diverse ion channels. K+ channels, the largest family of channels, control DSM excitability by maintaining the resting membrane potential and shaping the action potentials that cause the phasic contractions. Among the members of the voltage-gated K+ (KV) channel superfamily, KV type 7 (KV7) channels - KV7.1-KV7.5 members encoded by KCNQ1-KCNQ5 genes - have been recently identified as functional regulators in various cell types including vascular, cardiac, and neuronal cells. Their regulatory roles in DSM, however, are just now emerging and remain to be elucidated. To address this gap, our research group has initiated the systematic investigation of human DSM KV7 channels in collaboration with clinical urologists. In this comprehensive review, we summarize the current understanding of DSM Kv7 channels and highlight recent discoveries in the field. We describe KV7 channel expression profiles at the mRNA and protein levels, and further elaborate on functional effects of KV7 channel selective modulators on DSM excitability, contractility, and intracellular Ca2+ dynamics in animal species along with in vivo studies and the limited data on human DSM. Within each topic, we highlight the main observations, current gaps in knowledge, and most pressing questions and concepts in need of resolution. We emphasize the lack of systematic studies on human DSM KV7 channels that are now actively ongoing in our laboratory.

Urinary bladder smooth muscle ion channels: expression, function, and regulation in health and disease

Urinary bladder smooth muscle (UBSM), also known as detrusor smooth muscle, forms the bladder wall and ultimately determines the two main attributes of the organ: urine storage and voiding. The two functions are facilitated by UBSM relaxation and contraction, respectively, which depend on UBSM excitability shaped by multiple ion channels. In this review, we summarize the current understanding of key ion channels establishing and regulating UBSM excitability and contractility. They include excitation-enhancing voltage-gated Ca2+ (Cav) and transient receptor potential channels, excitation-reducing K+ channels, and still poorly understood Cl- channels. Dynamic interplay among UBSM ion channels determines the overall level of Cav channel activity. The net Ca2+ influx via Cav channels increases global intracellular Ca2+ concentration, which subsequently triggers UBSM contractility. Here, for each ion channel type, we describe UBSM tissue/cell expression (mRNA and protein) profiles and their role in regulating excitability and contractility of UBSM in various animal species, including the mouse, rat, and guinea pig, and, most importantly, humans. The currently available data reveal certain interspecies differences, which complicate the translational value of published animal research results to humans. This review highlights recent developments, findings on genetic knockout models, pharmacological data, reports on UBSM ion channel dysfunction in animal bladder disease models, and the very limited human studies currently available. Among all gaps in present-day knowledge, the unknowns on expression and functional roles for ion channels determined directly in human UBSM tissues and cells under both normal and disease conditions remain key hurdles in the field.

Pharmacology of the lower urinary tract: update on LUTS treatment

The number of compounds used in the pharmacological treatment of lower urinary tract symptoms (LUTS) of patients who do not respond to conservative measures has been relatively stable during the last decade, with the exception of the introduction of the new class of β3 adrenoceptor agonists. However, different combinations have been investigated, and the long-term use of these compounds has raised new concerns about adherence and safety. This review summarizes the current state of pharmacology for LUTS, and presents a thorough discussion of the possible challenges concerning their future use. In this narrative review, we analyze the most recent articles related to LUTS pharmacotherapy, after an initial review of mechanisms of bladder function relevant in present clinical practice. The main problems with pharmacotherapy in LUTS are associated with its moderate efficacy, low persistence on treatment, and the incidence of short- and long-term adverse events (AE) associated with some compounds. The long-term AE, such as cognitive impairment in the elderly vulnerable patients associated with antimuscarinic drugs or persistent erectile dysfunction in sexually active men after treatment with 5-α-reductase inhibitors (5-ARI), are some of the problems addressed in this review. Combination therapy taking advantage of the synergistic mechanisms of action between some classes of compounds may overcome AE associated with dose escalation. LUTS pharmacotherapy offers moderate results to most patients but not a full cure. The use of combination drugs to achieve better clinical results, reduce AE and improve both efficacy and adherence, will be used more frequently in the future. The recently raised concern on potential long-term irreversible AE associated with some of these drugs, like antimuscarinics and 5-ARI, are critically important and require further investigation.

Dysregulated NO/PDE5 signaling in the sickle cell mouse lower urinary tract: Reversal by oral nitrate therapy

AIMS

Nitric oxide (NO) has a critical, but not well understood, influence in the physiology of the lower urinary tract. We evaluated the effect of NO/phosphodiesterase (PDE)5 signaling in voiding dysfunction in the sickle cell disease (SCD) mouse, characterized by low NO bioavailability.

MAIN METHODS

Adult SCD (Sickle) and wild-type (WT) male mice were treated daily with sodium nitrate (10 mM) or vehicle. After 18 days, blood was obtained for nitrite measurement, urethra was collected for organ bath study, and bladder and urethra were collected for Western blot analysis of PDE5 phosphorylation (Ser-92) (activated form). Non-anesthetized mice underwent evaluation of urine volume by void spot assay. eNOS phosphorylation (Ser-1177) and nNOS phosphorylation (Ser-1412) (positive regulatory sites) were evaluated in the bladder and urethra of untreated mice.

KEY FINDINGS

Sickle mice exhibited decreased eNOS, nNOS, and PDE5 phosphorylation in the bladder and urethra, decreased plasma nitrite levels, increased relaxation of phenylephrine-contracted urethral tissue to an NO donor sodium nitroprusside, and increased total urine volume, compared with WT mice. Nitrate treatment normalized plasma nitrite levels, relaxation of urethra to sodium nitroprusside, PDE5 phosphorylation in the urethra and bladder, and urine volume in Sickle mice.

SIGNIFICANCE

Derangement in PDE5 activity associated with basally low NO bioavailability in the bladder and urethra contributes to the molecular basis for voiding abnormalities in Sickle mice. Inorganic nitrate supplementation normalized voiding in Sickle mice through mechanisms likely involving upregulation of PDE5 activity. These findings suggest that interventions targeting dysregulatory NO/PDE5 signaling may ameliorate overactive bladder in SCD.

Which molecular targets do we need to focus on to improve lower urinary tract dysfunction? ICI-RS 2017

AIMS

Update on some molecular targets for new drugs to improve lower urinary tract (LUT) dysfunction.

METHODS

Using PubMed, a search for literature on molecular targets in the LUT was performed to identify relevant clinical and animal studies. Keywords were entered as Medical Subject Headings (MeSH) or as text words. The Mesh terms were used in various combinations and usually included the terms lower urinary AND pharmacology. Other Mesh term included: bladder, urethra, CNS, physiology, afferent activity, ATP, prostanoids, cannabinoids, fibrosis. Search results were assessed for their overall relevance to this review.

RESULTS

In a normal bladder, ATP contributes little to detrusor contraction, but in a diseased bladder ATP may contribute to OAB. Selective decrease of ATP release via adenosine A1 receptor stimulation offers a potential treatment possibility. Candidates for relaxation of the smooth muscle of the urethra can be found among, for example, the receptor subtypes of PGE₂ , and PGD₂ . Drugs for relaxation of the striated sphincter can target the muscle directly or the spinal sphincter control. Fibrosis is a major problem in LUT dysfunction and agents with an inhibitory effect on the TGFβ pathway, for example relaxin and BMP7, may be promising avenues. Available drugs with a CNS site of action are often limited by low efficacy or adverse effects. Inhibitors of the glycine receptor Gly-T2 or antagonists of the adenosine A2 receptor may be new alternatives.

CONCLUSION

New molecular targets for drugs aiming at improvement of voiding function can be identified, but their translational impact remains to be established.

The role of prostaglandin and E series prostaglandin receptor type 4 receptors in the development of bladder overactivity in a rat model of chemically induced prostatic inflammation

OBJECTIVES

To evaluate, using a rat model of non-bacterial prostatic inflammation, the prostaglandin production and expression profiles of E-series prostaglandin (EP) receptor subtypes, which are reportedly implicated in the development of overactive bladder, in the bladder mucosa, and to investigate the effect of EP receptor type 4 (EP4) blockade on bladder overactivity after prostatic inflammation.

METHODS

Male Sprague-Dawley rats were used. Prostatic inflammation was induced by formalin injection (5%; 50 μL per lobe) into the bilateral ventral lobes of the prostate. At 10 days after induction of prostatic inflammation or vehicle injection, bladder tissues from the deeply anaesthetized rats were harvested and separated into mucosal and detrusor layers. Then, prostaglandin E2 (PGE2) concentrations and protein levels of PGE2 receptors (EP1-4) in the bladder mucosa and detrusor were measured by ELISA and Western blotting, respectively. In separate groups of control and formalin-treated rats, awake cystometry was performed to evaluate the changes in bladder activity after prostatic inflammation. In addition, the effect of intravesical administration of a selective EP4 antagonist (ONO-AE3-208; 30 μm) on bladder activity was evaluated in control rats and rats with prostatic inflammation.

RESULTS

PGE2 concentration and protein levels of EP4, but not other EP receptor subtypes, in the bladder mucosa and detrusor layers were significantly increased in formalin-injected rats vs vehicle-injected control rats. In cystometry, rats with prostatic inflammation exhibited a significant decrease in intercontraction intervals (ICIs) compared with control rats. Intravesical application of ONO-AE3-208 (30 μm), but not vehicle application, significantly increased ICIs in rats with prostatic inflammation, whereas ONO-AE3-208 at this concentration did not significantly affect any cystometric values in control rats.

CONCLUSIONS

Because intravesical administration of an EP4 antagonist effectively improved bladder overactivity after prostatic inflammation, EP4 activation, along with increased PGE2 production in the bladder mucosa, seems to be an important contributing factor to bladder overactivity induced by prostatic inflammation. Thus, blockade of EP4 in the bladder could be a therapeutic approach to male lower urinary tract symptoms attributable to benign prostatic hyperplasia with prostatic inflammation.

Progression of micturition dysfunction associated with the development of heart failure in rats: Model of overactive bladder

Heart failure (HF) has a strong association with the development of lower urinary tract symptoms, especially overactive bladder (OAB); although this condition remains poorly investigated. In this study, we assess the aortocaval fistula (ACF) model as a novel experimental model of micturition dysfunction, associated with HF, focused on the molecular and functional studies to evaluate the autonomic nervous system and urinary bladder remodeling. Male rats were submitted to ACF for HF induction. Echocardiography, cystometric, histomorphometry and molecular analysis, as well as concentration-response curves to carbachol and ATP and frequency-response curves to electrical field stimulation (EFS) were evaluated in Sham and HF (4- and 12-weeksendpoint) groups. Compared to SHAM, HF groups exhibited progressive increases in the left ventricle (LV) mass and fractional shortening which indicates cardiac dysfunction, although HF was characterized only after 12 weeks by the reduced ejection fraction. For micturition function, HF groups presented increased non-voiding contractions (NVC) and decreased bladder capacity; however, when comparing HF groups, these urinary parameters were significantly impaired over the weeks (12-weeks). The contractile responses induced by CCh, ATP and EFS were greater in detrusor muscle (DSM) from HF rats. mRNA expression for muscarinic receptors (M2 and M3) was higher in DSM only after 12 weeks of ACF, in addition to MMP9 and TGF-beta. Histomorphometric revealed increased urothelium thickness in both HF groups, whereas DSM thickness occurred only after 12 weeks. Thus, the ACF model induced cardiac dyfunction with progressive micturition dysfunction over the weeks, characterized by increased DSM contractile mechanisms as well as extracellular matrix remodeling in the urinary bladder, representing a useful tool to evaluate the OAB associated with HF.

Histamine modulation of urinary bladder urothelium, lamina propria and detrusor contractile activity via H1 and H2 receptors

The mechanisms underlying bladder contractile disorders such as overactive bladder are not fully understood, and there is limited understanding of the receptor systems modulating spontaneous bladder contractions. We investigated the potential for histamine to have a role in mediating contractility of the urothelium with lamina propria (U&LP) or detrusor via the H1-H4 histamine receptor subtypes. Isolated strips of porcine U&LP or detrusor smooth muscle were mounted in gassed Krebs-bicarbonate solution and responses to histamine obtained in the absence and presence of selective receptor antagonists. The presence of histamine increases the frequency of U&LP spontaneous phasic contractions and baseline tensions. In response to histamine, H1-antagonists pyrilamine, fexofenadine and cyproheptadine were effective at inhibiting contractile responses. Cimetidine (H2-antagonist) enhanced increases in baseline tension in response histamine, whereas amthamine (H2-agonist) induced relaxation. Although thioperamide (H3/H4-antagonist) increased baseline tension responses to histamine, selective H1/H2-receptor antagonism revealed no influence of these receptors. In detrusor preparations, pyrilamine, fexofenadine and cyproheptadine were effective at inhibiting baseline tension increases in response to histamine. Our findings provide evidence that histamine produces contractile responses both in the U&LP and detrusor via the H1-receptor, and this response is significantly inhibited by activation of the H2-receptor in the U&LP but not the detrusor.

Involvement of transient receptor potential melastatin 4 channels in the resting membrane potential setting and cholinergic contractile responses in mouse detrusor and ileal smooth muscles

Here, we investigated the effects of 9-hydroxyphenanthrene (9-phenanthrol), a potent and selective transient receptor potential melastatin 4 (TRPM4) channel blocker, on the resting membrane potential and cholinergic contractile responses to elucidate the functional role of TRPM4 channels in the contractile activities of mouse detrusor and ileal longitudinal smooth muscles. We observed that, 9-phenanthrol (3-30 µM) did not significantly inhibit high K⁺-induced contractions in both preparations; however, 9-phenanthrol (10 µM) strongly inhibited cholinergic contractions evoked by electrical field stimulation in detrusor preparations compared to inhibitions in ileal preparations. 9-Phenanthrol (10 µM) significantly inhibited the muscarinic agonist, carbachol-induced contractile responses and slowed the maximum upstroke velocities of the contraction in detrusor preparations. However, the agent (10 µM) did not inhibit the contractions due to intracellular Ca²⁺ release evoked by carbachol, suggesting that the inhibitory effect of 9-phenanthrol may primarily be due to the inhibition of the membrane depolarization process incurred by TRPM4 channels. On the other hand, 9-phenanthrol (10 µM) did not affect carbachol-induced contractile responses in ileal preparations. Further, 9-phenanthrol (10 µM) significantly hyperpolarized the resting membrane potential and decreased the basal tone in both detrusor and ileal muscle preparations. Taken together, our results suggest that TRPM4 channels are constitutively active and are involved in setting of the resting membrane potential, thereby regulating the basal tone in detrusor and ileal smooth muscles. Thus, TRPM4 channels play a significant role in cholinergic signaling in detrusor, but not ileal, smooth muscles.

Tissue Distribution of Active Principles from Alpiniae Oxyphyllae Fructus Extract: An Experimental Study in Rats

Background:

Alpiniae Oxyphyllae Fructus (Yizhi in Chinese) have been widely used as an herbal medicine for the treatment of diuresis, enuresis and diarrhea in China. Many studies have deciphered some potential underlying mechanisms for its anti-diarrheal effects. However, tissue distribution of Yizhi constituents is warranted because pharmacological receptors are frequently located in tissues. Moreover, it is also interesting to know about the potential correlation between behavior in drug distribution and the observed pharmacological response. The aim of this study is to investigate tissue distribution behaviors of Yizhi constituents after oral administration of Yizhi extract to rats, focusing on 10 active principles.

Methods:

Twenty four male Sprague Dawley rats were given orally the Yizhi extract and fourteen tissue samples were collected after being killed by bleeding from the abdominal aorta under ether anesthesia at different time-points. The resulting tissues were excised and homogenized. Based on our previous reports, liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was used to quantify the target analytes, as well as phase II metabolites, in the various biosamples.

Results:

Almost all the targeted Yizhi active principles and some glucuronidated metabolites were qualitatively measured in rat stomach, small intestine, large intestine, as well as liver. Nootkatone, yakuchinone A and tectochrysin were observed in the rat brain. In other rat tissues, these analytes had lower exposure or could not be detected. Consistently, quantitative analysis revealed that the Yizhi active principles dominantly distributed into gastrointestinal tissues followed by liver, the overall exposure levels ranking as follows: stomach > small intestine > large intestine > liver. Tissue concentrationtime profiles of the test active principles in rat stomach, small intestine, and large intestine were bimodal with two concentration peaks occurring at 0.5 and 4h after oral administration, respectively. The exposure levels in rat kidney and bladder were quite low.

Conclusion:

The active principles of Yizhi were specially distributed into gastrointestinal tissues after oral administration of its ethanol extract to rats. The tissue distribution behaviors partly supported its anti-diarrheal effects from a pharmacokinetic opinion. This paper will be useful as the starting point for studying the pharmacological activities of this traditional herb.

Use of baclofen in children with dysfunctional voiding: a preliminary report

Introduction

The aims of the present study were to examine the effectiveness and safety of baclofen in children with dysfunctional voiding (DV).

Material and methods

Thirty children with primary DV were enrolled. Patients underwent history taking, complete physical examination, urine analysis and culture, ultrasonography of the urinary system, a uroflowmetry study and post urine residue analysis. The Dysfunctional Voiding Symptom Score (DVSS) questionnaire was completed and other related symptoms were recorded. Oral baclofen was started for the study group at a dose of 1 mg/kg in 3 divided doses. Ultrasonography, a uroflowmetry study and questionnaire were repeated 3 months later.

Results

We observed a mean decrease of 14.67 ml in post void residual urine (PVRU) after 3 months. After usage of baclofen, increase in Qmax (5.74), increase in mean flow rate (8.2 vs. 11.3), and an average decrease of 12.3 in the DVSS questionnaire (p <0.001) were also observed. The number of voluntary voiding and wetting episodes were significantly decreased after treatment with baclofen (p = 0.001). Three main complaints of the patients were urgency (p = 0.001), dysuria (p = 0.004) and straining (p = 0.004) and all were significantly decreased after medical therapy with baclofen.

Conclusions

Baclofen may be useful in treatment of pediatric dysfunctional voiding. It was well tolerated among our patients with a remarkable reduction in their symptoms.

Involvement of TRPM4 in detrusor overactivity following spinal cord transection in mice

Transient receptor potential cation channel subfamily M member 4 (TRPM4) has been shown to play a key role in detrusor contractility under physiological conditions. In this study, we investigated the potential role of TRPM4 in detrusor overactivity following spinal cord transection (SCT) in mice. TRPM4 expression and function were evaluated in bladder tissue with or without the mucosa from spinal intact (SI) and SCT female mice (T8-T9 vertebra; 1-28 days post SCT) using PCR, western blot, immunohistochemistry, and muscle strip contractility techniques. TRPM4 was expressed in the urothelium (UT) and detrusor smooth muscle (DSM) and was upregulated after SCT. Expression levels peaked 3-7 days post SCT in both the UT and DSM. Pharmacological block of TRPM4 with the antagonist, 9-Phenanthrol (30 μM) greatly reduced spontaneous phasic activity that developed after SCT, regardless of the presence or absence of the mucosa. Detrusor overactivity following spinal cord injury leads to incontinence and/or renal impairment and represents a major health problem for which current treatments are not satisfactory. Augmented TRPM4 expression in the bladder after chronic SCT supports the hypothesis that TRPM4 channels play a role in DSM overactivity following SCT. Inhibition of TRPM4 may be beneficial for improving detrusor overactivity in SCI.

Laboratory practical to study the differential innervation pathways of urinary tract smooth muscle

In the mammalian lower urinary tract, there is a reciprocal relationship between the contractile state of the bladder and urethra. As the bladder fills with urine, it remains relaxed to accommodate increases in volume, while the urethra remains contracted to prevent leakage of urine from the bladder to the exterior. Disruptions to the normal contractile state of the bladder and urethra can lead to abnormal micturition patterns and urinary incontinence. While both the bladder and urethra are smooth-muscle organs, they are differentially contracted by input from cholinergic and sympathetic nerves, respectively. The laboratory practical described here provides an experiential approach to understanding the anatomy of the lower urinary tract. Several key factors in urinary tract physiology are outlined, e.g., the bladder is contracted by activation of the parasympathetic pathway via cholinergic stimulation on muscarinic receptors, whereas the urethra is contracted by activation of the sympathetic pathway via adrenergic stimulation on α₁-adrenoceptors. This is achieved by measuring the force generated by bladder and urethra smooth muscle to demonstrate that acetylcholine contracts the smooth muscle of the bladder, whereas adrenergic agonists contract the urethral smooth muscle. An inhibition of these effects is also demonstrated by application of the muscarinic receptor antagonist atropine and the α₁-adrenergic receptor blocker phentolamine. A list of suggested techniques and exam questions to evaluate student understanding on this topic is also provided.

Basic and clinical aspects of antimuscarinic agents used to treat overactive bladder

Antimuscarinic agents are now widely used as the pharmacological therapy for overactive bladder (OAB) because neuronal (parasympathetic nerve) and non-neuronal acetylcholine play a significant role for the bladder function. In this review, we will highlight basic and clinical aspects of eight antimuscarinic agents (oxybutynin, propiverine, tolterodine, solifenacin, darifenacin, trospium, imidafenacin, and fesoterodine) clinically used to treat urinary dysfunction in patients with OAB. The basic pharmacological characteristics of these eight antimuscarinic agents include muscarinic receptor subtype selectivity, functional bladder selectivity, and muscarinic receptor binding in the bladder and other tissues. The measurement of drug-receptor binding after oral administration of these agents allows for clearer understanding of bladder selectivity by the integration of pharmacodynamics and pharmacokinetics under in vivo conditions. Their central nervous system (CNS) penetration potentials are also discussed in terms of the feasibility of impairments in memory and cognitive function in elderly patients with OAB. The clinical aspects of efficacy focus on improvements in the daytime urinary frequency, nocturia, bladder capacity, the frequency of urgency, severity of urgency, number of incontinence episodes, OAB symptom score, and quality of life (QOL) score by antimuscarinic agents in patients with OAB. The safety of and adverse events caused by treatments with antimuscarinic agents such as dry mouth, constipation, blurred vision, erythema, fatigue, increased sweating, urinary retention, and CNS adverse events are discussed. A dose-dependent relationship was observed with adverse events, because the risk ratio generally increased with elevations in the drug dose of antimuscarinic agents. Side effect profiles may be additive to or contraindicated by other medications.

Therapeutic Approaches of Botulinum Toxin in Gynecology

Botulinum toxins (BoNTs) are produced by several anaerobic species of the genus Clostridium and, although they were originally considered lethal toxins, today they find their usefulness in the treatment of a wide range of pathologies in various medical specialties. Botulinum neurotoxin has been identified in seven different isoforms (BoNT-A, BoNT-B, BoNT-C, BoNT-D, BoNT-E, BoNT-F, and BoNT-G). Neurotoxigenic Clostridia can produce more than 40 different BoNT subtypes and, recently, a new BoNT serotype (BoNT-X) has been reported in some studies. BoNT-X has not been shown to actually be an active neurotoxin despite its catalytically active LC, so it should be described as a putative eighth serotype. The mechanism of action of the serotypes is similar: they inhibit the release of acetylcholine from the nerve endings but their therapeutically potency varies. Botulinum toxin type A (BoNT-A) is the most studied serotype for therapeutic purposes. Regarding the gynecological pathology, a series of studies based on the efficiency of its use in the treatment of refractory myofascial pelvic pain, vaginism, dyspareunia, vulvodynia and overactive bladder or urinary incontinence have been reported. The current study is a review of the literature regarding the efficiency of BoNT-A in the gynecological pathology and on the long and short-term effects of its administration.

Efficacy of Botulinum toxin A for the treatment of Bladder pain syndrome: A systematic review

OBJECTIVES

To determine the efficacy and safety of BTX-A, compared with other interventions for the treatment of BPS to improve quality of life.

METHODS

This systematic review fulfils all the requirements of the Cochrane manual and PRISMA reporting guidelines. The PROSPERO registration number is: CRD42016039480.Clinical trials without language discrimination were included. BPS patients over 18 y/o that were treated with BTX-A were included. Studies were searched in published databases and no published literature from inception to the present day. Risk of bias analysis was done using the Cochrane risk of bias tool.

RESULTS

88 articles were found with the designed search strategies. After exclusions, four studies were included in the qualitative analyses. Kasyan et al., 2012 compared BTX-A with hydrodistention. Manning et al., 2014 compared the injection of BTX-A with the injection of normal saline in previously hydrodistended bladders. In both cases, primary end point was measured by the O'Leary-Sant questionnaire score. El-Bahnasy et al., 2009 compared BTX-A with BCG administration, through Global Response Assessment. Kuo et al., 2015 compared hydrodistention plus suburothelial injections of BTX-A with hydrodistension plus normal saline injections. Reduction in pain was estimated by VAS bladder pain score. A similar efficacy to their controls had been found in Kasyan and Manning studies. El-Bahnasy had found improvement in BTX-A in all parameters. Kuo el al. 2015, found a significantly reduction in pain in the BTX-A group. Regarding the risk of bias, three studies did not have adequate descriptions of selection, performance and detection bias. The study of Manning had low risk of selection, attrition and reporting bias.

CONCLUSION

There is not enough evidence to conclude the efficacy of BTX-A for the treatment of interstitial cystitis to improve quality of life.

Identification of differentially expressed miRNAs and miRNA-targeted genes in bladder cancer

Background

Differentially expressed genes and their post-transcriptional regulator-microRNAs (miRNAs), are potential keys to pioneering cancer diagnosis and treatment. The aim of this study was to investigate how the miRNA-mRNA interactions might affect the tumorigenesis of bladder cancer (BC) and to identify specific miRNA and mRNA genetic markers in the two BC types: non-muscle invasive bladder cancer (NMIBC) and muscle invasive bladder cancer (MIBC).

Results

We identified 227 genes that interacted with 54 miRNAs in NMIBC, and 14 genes that interacted with 10 miRNAs in MIBC. Based on this data, we found extracellular matrix-related genes are highly enriched in NMIBC while genes related to core nuclear division are highly enriched in MIBC. Furthermore, using a transcriptional regulatory element database, we found indirect regulatory transcription factors (TFs) for enriched genes could regulate tumorigenesis with or without miRNAs.

Materials and methods

Tissue samples from 234 patients histologically diagnosed with BC and 83 individuals without BC were analyzed using microarray and next-generation sequencing technology, and we used different cut-offs to identify differentially expressed mRNAs and miRNAs in NMIBC and MIBC. The selected mRNAs and miRNAs were paired using validated target datasets and according to inverse expression relationships. MiRNA interacted genes were compared with the TF-regulating genes in BC. Meanwhile, pathway enrichment analysis was performed to identify the functions of selected miRNAs and genes.

Conclusions

Identification of differential gene expression in specific tumor types could facilitate development of cancer diagnosis and aid in the early detection of BC.