A myogenic basis for the overactive bladder

Can we predict and manage persistent storage and voiding LUTS following bladder outflow resistance reduction surgery in men? ICI-RS 2023

AIMS

Lower urinary tract symptoms (LUTS) persist in up to 50% of patients after bladder outflow resistance reduction surgery (BORRS) in men. Our think tank aims to address the predictive factors for persistent LUTS after BORRS and to propose the recommendations for future research to enable improved better patient counseling and selection by more accurate prediction of treatment outcome.

METHODS

A think tank of ICI-RS gathered in 2023, Bristol, UK, to discuss the pre and postsurgical clinical and urodynamic evaluation of men undergoing BORRS and whether it is possible to predict which men will have persistent LUTS after BORRS.

RESULTS

Our think tank agrees that due to the multifactorial, and still not fully understood, etiology of male LUTS it is not possible to precisely predict in many men who will have persistent LUTS after BORRS. However, severe storage symptoms (overactive bladder, OAB) in association with low volume and high amplitude detrusor overactivity and low bladder capacity in preoperative urodynamics, increase the likelihood of persistent OAB/storage symptoms after BORRS. Furthermore, patients who are clearly obstructed and have good bladder contractility on preoperative pressure flow studies do better postoperatively compared to their counterparts. However, the benefit of pressure flow studies is decreased in patients who do not acceptably void during the study. Poor voiding after BORRS may occur due to persistent obstruction or detrusor underactivity.

CONCLUSION

Future research is needed to increase our understanding of why male LUTS persist after surgery, and to enable better patient selection and more precise patient counseling before BORRS.

Medicinal plants and natural products for treating overactive bladder

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Pathophysiology of Overactive Bladder and Pharmacologic Treatments Including β3-Adrenoceptor Agonists -Basic Research Perspectives

Overactive bladder (OAB) is a symptom-based syndrome defined by urinary urgency, frequency, and nocturia with or without urge incontinence. The causative pathology is diverse; including bladder outlet obstruction (BOO), bladder ischemia, aging, metabolic syndrome, psychological stress, affective disorder, urinary microbiome, localized and systemic inflammatory responses, etc. Several hypotheses have been suggested as mechanisms of OAB generation; among them, neurogenic, myogenic, and urothelial mechanisms are well-known hypotheses. Also, a series of local signals called autonomous myogenic contraction, micromotion, or afferent noises, which can occur during bladder filling, may be induced by the leak of acetylcholine (ACh) or urothelial release of adenosine triphosphate (ATP). They can be transmitted to the central nervous system through afferent fibers to trigger coordinated urgency-related detrusor contractions. Antimuscarinics, commonly known to induce smooth muscle relaxation by competitive blockage of muscarinic receptors in the parasympathetic postganglionic nerve, have a minimal effect on detrusor contraction within therapeutic doses. In fact, they have a predominant role in preventing signals in the afferent nerve transmission process. β3-adrenergic receptor (AR) agonists inhibit afferent signals by predominant inhibition of mechanosensitive Aδ-fibers in the normal bladder. However, in pathologic conditions such as spinal cord injury, it seems to inhibit capsaicin-sensitive C-fibers. Particularly, mirabegron, a β3-agonist, prevents ACh release in the BOO-induced detrusor overactivity model by parasympathetic prejunctional mechanisms. A recent study also revealed that vibegron may have 2 mechanisms of action: inhibition of ACh from cholinergic efferent nerves in the detrusor and afferent inhibition via urothelial β3-AR.

Pelvic floor dysfunction and obesity

Obesity is a growing condition within the society and more patients, who have underlying obesity, are presenting with lower urinary tract symptoms (LUTS) and pelvic floor dysfunction (PFD). The effect of obesity on general health has been well documented, and its impact on the cardiovascular, endocrine, and musculoskeletal systems has been extensively studied. There is now a growing body of evidence on the effects of obesity on the female urogenital system. It seems to influence the prevalence, presentation, assessment, management, and outcome of various types of LUTS and PFD. A holistic approach is needed to assess and manage these patients. A clear understanding of the functions of the pelvic floor and the way it can be affected by obesity is essential in providing holistic care to this group. A frank discussion about patient weight is required in the clinics handling PFD. A multimodal approach to weight loss would help improve PFD symptoms and progression. Patients with obesity should still be offered standard treatment options for all PFDs and should not be forced to lose weight as a prerequisite before starting treatment. However, they should also be made aware of the impediments that being overweight adds to their care and their expectations should be managed accordingly.

Comparison of early loosening vs delayed section of mid-urethral slings for postoperative voiding dysfunction

INTRODUCTION AND HYPOTHESIS

Bladder outlet obstruction (BOO) is a common occurrence after midurethral sling (MUS) insertion and can result in acute or chronic urinary retention or de novo lower urinary tract symptoms (LUTS). However, the management of BOO after MUS is not standardised. The objective of this study was to compare two therapeutic strategies for suspected BOO after MUS.

METHODS

Patients who had surgical revision for voiding dysfunction with a post-void residual (PVR) ≥100 ml after MUS in five centres between 2005 and 2020 were included in a retrospective study. Patients were divided into two groups: early sling loosening (EL) vs delayed section/excision of the sling (DS).

RESULTS

Seventy patients were included: 38 in the EL group and 32 in the DS group. The postoperative complication rate was comparable in both groups (10.5% vs 12.5%; p = 0.99). At 3 months, the rate of withdrawal from self-catheterisation was similar in the two groups (92.1% vs 100%; p = 0.25) as was the PVR (57.5 vs 63.5 ml; p = 0.09). After a median follow-up of 9 months, there were significantly more patients with resolved voiding dysfunction in the EL group (63.2% vs 31.3%; p = 0.01). The rate of persistent/recurrent stress urinary incontinence (SUI) was higher in the DS group (21% vs 43.7%; p = 0.04). In multivariate analysis, the main predictive factor of recurrent SUI was DS (OR 2.87, 95% CI 1.01-8.60, p = 0.048).

CONCLUSIONS

Early loosening of MUS in the case of postoperative voiding dysfunction offers better efficacy than DS of the sling, with a lower risk of recurrent/persistent SUI.

Key role for Kv11.1 (ether-a-go-go related gene) channels in rat bladder contractility

In addition, to their established role in cardiac myocytes and neurons, ion channels encoded by ether-a-go-go-related genes (ERG1-3 or kcnh2,3 and 6) (kcnh2) are functionally relevant in phasic smooth muscle. The aim of the study was to determine the expression and functional impact of ERG expression products in rat urinary bladder smooth muscle using quantitative polymerase chain reaction, immunocytochemistry, whole-cell patch-clamp and isometric tension recording. kcnh2 was expressed in rat bladder, whereas kcnh6 and kcnh3 expression were negligible. Immunofluorescence for the kcnh2 expression product Kv11.1 was detected in the membrane of isolated smooth muscle cells. Potassium currents with voltage-dependent characteristics consistent with Kv11.1 channels and sensitive to the specific blocker E4031 (1 μM) were recorded from isolated detrusor smooth muscles. Disabling Kv11.1 activity with specific blockers (E4031 and dofetilide, 0.2-20 μM) augmented spontaneous contractions to a greater extent than BKCa channel blockers, enhanced carbachol-driven activity, increased nerve stimulation-mediated contractions, and impaired β-adrenoceptor-mediated inhibitory responses. These data establish for the first time that Kv11.1 channels are key determinants of contractility in rat detrusor smooth muscle.

Relevance of dog as an animal model for urologic diseases

We utilize animal models in urologic research to improve understanding of urinary physiology, determine the etiology of many urologic diseases, and discover and test novel therapeutic interventions. Dogs have a similar urinary tract anatomy and physiology to human and they develop many urologic diseases spontaneously. This chapter offers detailed comparisons of urinary tract anatomy, physiology, and the most common urologic diseases between humans and dogs. Dogs offer a unique opportunity for urologic research because they can be studied in research colonies and in client owned cohorts. Dogs also are among a limited number of non-human species that require continence and socially appropriate urinary behaviors (ex. going to the bathroom outside, training to not have submissive urination, etc.). These features make dogs unique in the animal kingdom and make them an ideal animal model for urologic research.

[Pathophysiology and pharmacotherapy of benign prostatic disorders]

Men with benign prostatic hyperplasia (BPH) often experience symptoms of overactive bladder (OAB), and bladder outlet obstruction (BOO) is one of cause of BPH. It has been suggested that bladder myogenic microcontractions or micromotions may partly contribute to the development of urgency (bladder sensory (afferent) hypersensitivity) in OAB related to BOO. We have investigated the direct effects of drugs (β3-adrenoceptor agonists, α1-adrenoceptor antagonists, PDE type5 inhibitors) on the bladder afferent function in BOO rats. In our results, almost all drugs may act on the bladder afferent function, and mirabegron inhibits the afferent activities through the suppression of the bladder myogenic microcontractions in BOO condition. Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) causes long-standing pain and/or storage symptoms including storage symptoms, such as urgency and frequency. We evaluated the likelihood of deterioration of bladder sensation in a carrageenan-induced CP/CPPS model. In results, the carrageenan-induced CP/CPPS rat model showed edema, ischemia, and inflammatory pain in the prostate, whereas a little change was detected in bladder sensation. These findings demonstrated that the bladder sensation is unlikely deteriorated in this model, suggesting CP/CPPS is possibly overlapping with symptoms in BPH.

The TRPM8 channel as a potential therapeutic target for bladder hypersensitive disorders

In the lower urinary tract, transient receptor potential (TRP) channels are primarily involved in physiological function, especially in cellular sensors responding to chemical and physical stimuli. Among TRP channels, TRP melastatin 8 (TRPM8) channels, responding to cold temperature and/or chemical agents, such as menthol or icilin, are mainly expressed in the nerve endings of the primary afferent neurons and in the cell bodies of dorsal root ganglia innervating the urinary bladder (via Aδ- and C-fibers); this suggests that TRPM8 channels primarily contribute to bladder sensory (afferent) function. Storage symptoms of overactive bladder, benign prostatic hyperplasia, and interstitial cystitis are commonly related to sensory function (bladder hypersensitivity); thus, TRPM8 channels may also contribute to the pathophysiology of bladder hypersensitivity. Indeed, it has been reported in a pharmacological investigation using rodents that TRPM8 channels contribute to the pathophysiological bladder afferent hypersensitivity of mechanosensitive C-fibers. Similar findings have also been reported in humans. Therefore, a TRPM8 antagonist would be a promising therapeutic target for bladder hypersensitive disorders, including urinary urgency or nociceptive pain. In this review article, the functional role of the TRPM8 channel in the lower urinary tract and the potential of its antagonist for the treatment of bladder disorders was described.

Hypothyroidism is prevalent among adult women with chronic lower urinary tract symptoms

OBJECTIVE

To define the prevalence of hypothyroidism in women with chronic lower urinary tract symptoms (LUTS) and to compare the severity of each symptom between patients with hypothyroidism and controls.

SUBJECTS AND METHODS

In this prospective observational study, we screened all adult women who came to the urology clinic between March 2017 and September 2020, and enrolled patients with chronic LUTS in the study. We assessed thyroid function. We evaluated the severity of voiding and storage urinary symptoms by the International Prostate Symptom Score. We also assessed the severity of urge urinary incontinence (UUI) and stress urinary incontinence (SUI). For between-group analysis, we selected age-matched cases and controls and compared them regarding the distribution and severity of urinary symptoms.

RESULTS

Seven hundred and twenty-five women with a mean age of 51.7 ± 14.0 years were included in the final analysis. Two hundred fifty-eight patients (35.6%) had hypothyroidism. Age-matched case and control groups consisting of 210 patients each were selected. There was no significant difference in the severity and distribution of voiding LUTS and UUI between the study groups (P values >0.05). The severity of storage symptoms was lower in patients with hypothyroidism (P = 0.04). Sixty-seven patients with hypothyroidism (31.9%) had SUI, which was significantly higher than controls (23.3%) (P = 0.03).

CONCLUSION

More than one-third of women with chronic LUTS have hypothyroidism which is much more frequent than in the general population. We also suggest a possible relationship between hypothyroidism and the severity of SUI and an inverse relationship between hypothyroidism and storage symptoms.

Trypsin-induced elevated contractile responses in a rat model of interstitial cystitis/bladder pain syndrome: Involvement of PAR2 and intracellular Ca2+ release pathways

AIMS

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic inflammatory disease with unclear etiology. Different receptors play a role in the pathophysiology including protease activated receptors (PARs). The present study aimed to investigate the subtypes and the effects of PARs on contractility using permeabilized detrusor smooth muscle strips in IC/BPS.

MAIN METHODS

IC/BPS was induced by cyclophosphamide injection. Histopathological analysis, PCR for detecting PAR proteins, western blotting for indicating PAR2 protein expression levels and myograph recording for measuring contractile force were used.

KEY FINDINGS

The present study reveals that in rat bladder PAR1 and PAR2 but not PAR4 were found to be expressed. The first evidence was revealed where trypsin-induced contractions in rat permeabilized detrusor were potentiated in CYP-induced cystitis. Moreover, the functional inhibition of trypsin-induced contractions by selective PAR2 antagonist (ENMD-1068) and the supporting immunoblotting results emphasized that the main PAR subtype involved in IC/BPS model in rat bladder is PAR2. Our data emphasize the prominent role of IP₃ in cystitis pathology besides ryanodine channels. Trypsin-induced Ca²⁺sensitization contractions were also higher in cystitis. Both Rho kinase and protein kinase C played a role in this increased Ca²⁺sensitization situation.

SIGNIFICANCE

The present paper highlights the intracellular pathways that are involved in trypsin-induced contractions mainly via PAR2 in permeabilized bladder detrusor smooth muscle in a rat model of IC/BPS.

Urgency and urgency incontinence following stress urinary incontinence surgery: A review of evaluation and management

The presence of urgency urinary incontinence (U/UUI) after sling surgery is a common reason for dissatisfaction and imposition on quality of life. We aimed to evaluate and analyze the pathophysiology, evaluation, and treatment of U/UUI after sling surgery. A MEDLINE review was performed for relevant, English-language articles relating to storage and emptying symptoms after sling surgery. U/UUI may persist, be improved, or worsen in women with preoperative mixed urinary incontinence and may appear de novo in those women originally presenting with pure stress urinary incontinence (SUI). While the exact mechanism is not clear, partial bladder outlet obstruction (BOO) should always be suspected, especially in those women with worsened or de novo symptoms soon after sling surgery. Initial workup should elucidate the temporality, quality, and bother associated with symptoms and to evaluate the woman for urinary tract infection (UTI), pelvic organ prolapse (POP), or perforation of the lower urinary tract. The utility of urodynamics in attaining a definitive diagnosis of BOO is inconclusive. Treatment options include reevaluation of the patient after sling incision or after addressing UTI, POP, and perforation of the bladder or urethra. Women also typically undergo a multitiered approach to storage lower urinary tract symptoms outlined in the American Urological Association/Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction Overactive Bladder Guidelines. While improvement is typically seen with multimodality treatment, all women should be counseled regarding need for additional treatment for U/UUI, BOO, and SUI in the future.

Slow development of bladder malfunction parallels spinal cord fiber sprouting and interneurons' loss after spinal cord transection

Neurogenic lower urinary tract dysfunction typically develops after spinal cord injury. We investigated the time course and the anatomical changes in the spinal cord that may be causing lower urinary tract symptoms following injury. Rats were implanted with a bladder catheter and external urethral sphincter electromyography electrodes. Animals underwent a large, incomplete spinal transection at the T8/9 spinal level. At 1, 2-3, and 4 weeks after injury, the animals underwent urodynamic investigations. Urodynamic investigations showed detrusor overactivity and detrusor-sphincter-dyssynergia appearing over time at 3-4 weeks after injury. Lower urinary tract dysfunction was accompanied by an increase in density of C-fiber afferents in the lumbosacral dorsal horn. CRF-positive Barrington's and 5-HT-positive bulbospinal projections drastically decreased after injury, with partial compensation for the CRF fibers at 3-4 weeks. Interestingly, a decrease over time was observed in the number of GABAergic neurons in the lumbosacral dorsal horn and lamina X, and a decrease of glutamatergic cells in the dorsal horn. Detrusor overactivity and detrusor-sphincter-dyssynergia might therefore arise from a discrepancy in inhibitory/excitatory interneuron activity in the lumbosacral cord as well as input changes which develop over time after injury. The processes point to spinal plastic changes leading to malfunction of the important physiological pathway of lower urinary tract control.

Comparison of Pelvic Floor Muscle Training With Connective Tissue Massage to Pelvic Floor Muscle Training Alone in Women With Overactive Bladder: A Randomized Controlled Study

OBJECTIVE

The purpose of this study was to compare the effects of a 6-week program of pelvic floor muscle training (PFMT) plus connective tissue massage (CTM) to PFMT alone in women with overactive bladder (OAB) symptoms on those symptoms, pelvic floor muscle strength, and quality of life.

METHODS

Thirty-four participants were randomly divided into PFMT+CTM (n = 17) and PFMT (n = 17) groups. PFMT was applied every day and CTM was applied 3 days a week for 6 weeks. Before treatment, at week 3, and after treatment (week 6), we assessed pelvic floor muscle strength (with a perineometer), bladder symptoms (with a urine diary), OAB symptom severity (with the 8-item Overactive Bladder Questionnaire [OAB-V8]), urgency (with the Patient Perception of Intensity of Urgency Scale [PPIUS]), and quality of life (with King's Health Questionnaire [KHQ]). The Mann-Whitney U test, χ² test, Friedman test, and Dunn multiple comparison test were used for analysis.

RESULTS

In both groups, pelvic floor muscle strength increased, whereas OAB symptoms and PPIUS and KHQ scores decreased after treatment (P < .05). Although the OAB-V8, PPIUS, and KHQ scores decreased at week 3, frequency, OAB-V8, and PPIUS scores, in addition to some parameters of the KHQ, decreased after treatment in the PFMT+CTM group compared to the PFMT group (P < .05).

CONCLUSION

Compared to PFMT alone, PFMT+CTM achieved superior outcomes in reducing OAB symptoms in the early and late periods.

Native tissue repair of cardinal/uterosacral ligaments cures overactive bladder and prolapse, but only in pre-menopausal women

INTRODUCTION

The aim of this article was to study the effect of native tissue cardinal/uterosacral ligament repair on overactive bladder (OAB) and pelvic organ prolapse (POP).

MATERIAL AND METHODS

Inclusion criteria included decrease of urge symptoms following insertion of a gauze tampon in the posterior fornix of vagina ('simulated operation'). Exclusion criteria included SUI, POP grades 3-4. The surgery consisted of plication of cardinal/uterosacral ligaments. Post-operative assessment was performed at3, 6, 12 and 18 months after surgery and included evaluation by stage of prolapse, Urinary Distress Inventory Short Form 6 (UDI-6), Overactive Bladder Questionnaire (OAB-q), Pelvic Floor Impact Questionnaire- Short Form 7 (PFIQ-7), and International Consultation on Incontinence Questionnaire - Urinary Incontinence Short Form (ICIQ-SF) questionnaires and voiding diary.

RESULTS

At 3 months, cure rates for frequency, urgency, nocturia and prolapse were comparable. By the 6-month review, catastrophic failure commenced in the postmenopausal group, parallel for all pa-rameters, starkly contrasting with premenopausal group. At 18 months, % cure rates for pre-menopausal (post-menopausal in brackets) were 79.6 (15.4) for POP, 67.3 (20.5) for urgency, 87.7 (20.5) for nocturia and 59.2 (15.4) for frequency.

CONCLUSIONS

We hypothesize the stepwise parallel recurrence of POP and symptoms in the menopausal group was a consequence of collagen deficiency in the plicated ligaments. Nevertheless, plication of uterosacral-cardinal ligament complex is simple, inexpensive, effective, especially applicable pre-menopausally for POP and as an alternative treatment option in that difficult group of pre-menopausal women who have major OAB/nocturia symptoms but only minimal prolapse.

Chronic psychological stress and lower urinary tract symptoms

It is well established that lower urinary tract symptoms (LUTS), particularly urinary urgency and incontinence, cause stress and anxiety for patients. However, there is mounting evidence that the relationship between these two factors is bidirectional and that chronic psychological stress itself can result in the development of symptoms such as urinary frequency, urgency, incontinence, and pelvic pain. This review considers the evidence that such a relationship exists and reviews the literature from clinical and animal studies to identify some of the mechanisms that might be involved. Inflammatory responses induced by chronic stress appear to offer the strongest link to bladder dysfunction. There is overwhelming evidence, both in patients and animal models, for a release of pro-inflammatory cytokines and chemokines during periods of chronic stress. Furthermore, cytokines have been shown to cause bladder dysfunction and pain via actions in the central nervous system and locally in the bladder. In the brain and spinal cord, pro-inflammatory cytokines influence the regulation of micturition pathways by corticotropin-releasing factor (CRF) and its receptors, while peripherally cytokines affect bladder function, directly causing detrusor hypertrophy and afferent nerve hypersensitivity. There is little information on which treatments may have most benefit for stressed/anxious patients with LUTS, but animal studies suggest traditional drugs for overactive bladder (solifenacin, mirabegron) are more effective on LUTS than anxiolytic drugs (fluoxetine, imipramine). The preliminary preclinical data for CRF receptor antagonists is not consistent. A clearer understanding of the mechanisms involved in stress-induced LUTS should provide a basis for improved treatment of this condition.

Drug Delivery Approaches for Managing Overactive Bladder (OAB): A Systematic Review

Overactive bladder syndrome (OAB) is characterised by urgency symptoms, with or without urgency incontinence, usually with frequency and nocturia and severely affects the quality of life. This systematic review evaluates the various drug delivery strategies used in practice to manage OAB. Advanced drug delivery strategies alongside traditional strategies were comprehensively analysed and comparatively evaluated. The present review was conducted according to the preferred reporting items for systematic reviews and meta-analyses guidelines. A total of 24 studies reporting the development of novel formulations for the treatment of OAB were considered eligible and were further categorised according to the route of drug administration. The review found that various drug delivery routes (transdermal, intravesicular, oral, vaginal and intramuscular) are used for the administration of drugs for managing OAB, however, the outcomes illustrated the marked potential of transdermal drug delivery route. The findings of the current review are expected to be helpful for pharmaceutical scientists to better comprehend the existing literature and challenges and is anticipated to provide a basis for designing and fabricating novel drug delivery systems to manage OAB.

Nerve transfer for restoration of lower motor neuron-lesioned bladder function. Part 1: attenuation of purinergic bladder smooth muscle contractions

This study determined the effect of pelvic organ decentralization and reinnervation 1 yr later on the contribution of muscarinic and purinergic receptors to ex vivo, nerve-evoked, bladder smooth muscle contractions. Nineteen canines underwent decentralization by bilateral transection of all coccygeal and sacral (S) spinal roots, dorsal roots of lumbar (L)7, and hypogastric nerves. After exclusions, 8 were reinnervated 12 mo postdecentralization with obturator-to-pelvic and sciatic-to-pudendal nerve transfers then euthanized 8-12 mo later. Four served as long-term decentralized only animals. Controls included six sham-operated and three unoperated animals. Detrusor muscle was assessed for contractile responses to potassium chloride (KCl) and electric field stimulation (EFS) before and after purinergic receptor desensitization with α, β-methylene adenosine triphosphate (α,β-mATP), muscarinic receptor antagonism with atropine, or sodium channel blockade with tetrodotoxin. Atropine inhibition of EFS-induced contractions increased in decentralized and reinnervated animals compared with controls. Maximal contractile responses to α,β-mATP did not differ between groups. In strips from decentralized and reinnervated animals, the contractile response to EFS was enhanced at lower frequencies compared with normal controls. The observation of increased blockade of nerve-evoked contractions by muscarinic antagonist with no change in responsiveness to purinergic agonist suggests either decreased ATP release or increased ecto-ATPase activity in detrusor muscle as a consequence of the long-term decentralization. The reduction in the frequency required to produce maximum contraction following decentralization may be due to enhanced nerve sensitivity to EFS or a change in the effectiveness of the neurotransmission.

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.

Lower urinary tract dysfunction in adult patients with mitochondrial disease

AIMS

Mitochondrial diseases present with a spectrum of clinical features, usually with multiorgan involvement and are often characterized by a loss of smooth muscle function. Hence, we hypothesized that mitochondrial dysfunction may contribute to lower urinary tract (LUT) dysfunction.

METHODS

We performed a prospective cohort study at a single, quaternary, mitochondrial disease referral center, enrolling consecutive adult patients with genetically confirmed mitochondrial disease. Data regarding baseline characteristics and disease burden were gathered. LUT dysfunction was assessed using the International Consultation on Incontinence Modular Questionnaire-Lower Urinary Tract Symptoms (ICIQ-LUTS) questionnaire, bladder voiding efficiency (BVE), and bladder diaries. Patients with one or more features of LUT dysfunction were offered urodynamic testing.

RESULTS

A total of 109 patients were included. Twenty-six percent of patients manifested at least one feature of LUT dysfunction, which was objectively confirmed in all 14 patients who consented to urodynamic investigation. Disease burden, defined by the Newcastle Mitochondrial Disease Adult Scale (NMDAS), demonstrated a linear relationship with ICIQ-LUTS severity (P = .01), with a statistically significant relationship between NMDAS-gastrointestinal scores and LUTS scores (P < .001). Limitations include mutational heterogeneity across the patient cohort.

CONCLUSIONS

This is the largest study exploring LUT in patients with mitochondrial disease and supports previous smaller studies suggesting LUT dysfunction is underrecognized in patients with mitochondrial disease and impacts considerably on their quality of life. We propose a clinical guideline for identifying mitochondrial disease patients at risk of LUT dysfunction.

Overactive bladder syndrome - focus onto detrusor overactivity

INTRODUCTION AND HYPOTHESIS

To determine in patients with overactive bladder (OAB), urodynamic differences as well to compare the characteristics of patient's, with presence of detrusor overactivity on urodynamics with those with absence of detrusor overactivity.

METHODS

Taking into account the urodynamic findings, the patients with OAB symptoms were categorized into one of two groups: group 1 (with detrusor overactivity) or group 2 (without detrusor overactivity), and comparative analyses for both groups were performed (epidemiological data, patient history, urodynamic criteria, bladder diaries, IC-OAB, IC-OABqol - questionnaires).

RESULTS

There was a significant difference in age as well in the disease duration between group 1 and group 2. Although the mean number of micturitions and nocturia episodes was comparable, the numbers of urgency episodes differed significantly. The number of 'wet' patients was significantly higher in the group 1 with the significantly higher number of incontinence episodes. Group 1 demonstrated higher OAB symptom scores and higher impact on the patients' quality of life.

CONCLUSIONS

More than half of the patients complaining of urgency-frequency do not have detrusor overactivity upon urodynamic testing, and only half have detrusor overactivity that correlates with urge perception. The patients with no detrusor overactivity appear to be significantly younger and have fewer symptoms, with a less pronounced impact on quality of life. They also have significantly higher maximal bladder capacity. This data supports the hypothesis that both conditions are different phases (early and late) of the same pathological state, or may be two different subtypes of OAB.

The clinical pharmacology of the medical treatment for overactive bladder in adults

INTRODUCTION

Overactive bladder is a prevalent symptom complex that affects the patient's quality of life. Any disruption between the neuronal micturition pathway can lead to bladder overactivity. Neurogenic causes, myogenic causes, aging, bladder outlet obstruction, sex, and psychological factors are some of the factors contributing to bladder overactivity. The complaint of any symptoms of OAB, which is highly prevalent and affects overall QOL, often needs therapeutic interventions. When conservative therapy methods fail, the addition of medications is recommended. The most commonly used agents for the treatment of OAB are antimuscarinic drugs. New classes of drugs, such as beta-3 agonists, have enriched our pharmacologic armamentarium.

AREAS COVERED

In this review, with a special focus on oral pharmacological treatments, we discussed the definition, etiology, symptoms, diagnosis, and management of OAB.

EXPERT OPINION

OAB is a multifactorial condition with every patient presenting with a different collection of symptoms and signs. Medical therapies should be given in conjunction with behavioral therapies. Using high or low doses, flexible doses, and stopping or changing the medications are interchangeable strategies based on the level of treatment efficacy and patient satisfaction.

Mirabegron in the Treatment of Overactive Bladder: Safety and Efficacy in the Very Elderly Patient

Lower urinary tract symptoms, including urgency, urgency incontinence, frequency, and nocturia, are highly prevalent in older adults and are associated with significant morbidity and impairment in quality of life. When conservative measures such as bladder training fail to improve symptoms, pharmacological management is recommended by national and international guidelines. Mirabegron, an agonist of the β3 adrenergic receptor, demonstrates similar efficacy to the anticholinergic drugs without the risk of anticholinergic effects, but experience and evidence in the very elderly population are limited. This narrative review examines the current evidence base for mirabegron in very elderly adults.

Reduced Ca2+ spark activity contributes to detrusor overactivity of rats with partial bladder outlet obstruction

We tested whether or not altered Ca²⁺ spark activity accounted for detrusor overactivity (DO) of Wistar rats after partial bladder outlet obstruction (PBOO). We constructed a DO model through PBOO and studied the Ca²⁺ spark activity of detrusor. By way of using confocal microscopy and the patch-clamp technique, Ca²⁺ sparks and spontaneous transient outward currents (STOCs) in detrusor myocytes were measured respectively. Our results indicated that Ca²⁺ spark activity and STOCs were significantly reduced in the DO detrusor myocytes compared to unafflicted control cells, and both of these had levels that were remarkably increased by applications of caffeine (10 μM), a RyR agonist, in DO myocytes. In addition, measures of detrusor contractions were also recorded by using freshly isolated detrusor strips. These results indicated that the spontaneous contraction of DO detrusor was significantly enhanced, and that the effect of caffeine (10 μM) upon detrusor contractions was reversed by applications of iberiotoxin (100 nM) which is a BK channel blocker. Western blotting (WB) analyses indicated that the levels of expression of ryanodine receptor type 2 (RyR2) and FK506 binding protein 12.6 (FKBP12.6) in bladder muscle were respectively decreased and increased in the samples from DO rats. Thus, we considered in the rat DO model wherein PBOO, the reduced Ca²⁺ spark activity in detrusor myocytes partly contributed to overactive detrusor contractions. The impaired Ca²⁺ spark activity may have resulted from decreased RyR2 expression and increased FKBP12.6 expression. Such novel findings in our research might help to provide means for better treatment outcomes for patients afflicted by bladder dysfunction.

[Afferent nerve activity in relation to bladder sensation]

Bladder afferent nerves are composed by myelinated Aδ- and unmyelinated C-fibers. During the storage phase of urine, distention of the bladder has long been considered to evoke afferent activity via Aδ-fibers connected in series with the smooth muscle fibers. In contrast, a previous study in cats revealed that more than 90% of C-fibers do not respond to normal bladder distension, being so called 〝silent〟 fibers. However, at least in rats, C-fibers can respond to normal bladder distension like Aδ-fibers, although they may also fulfill a potentially different role in the bladder sensory function in response to abnormal stimuli. The symptoms of overactive bladder (OAB) or interstitial cystitis (IC) are believed to be commonly related to the sensory (afferent) function. In addition, it has been suggested that bladder myogenic microcontractions or micromotions may partly contribute to the development of urgency in OAB related to bladder outlet obstruction (BOO), which is one of cause of benign prostatic hyperplasia (BPH). We have investigated the direct effects of drugs (anticholinergics, β3-adrenoceptor agonists, α1-adrenoceptor antagonists, PDE type5 inhibitors, etc.) on the bladder afferent function in rodents. In our results, almost all drugs may act on the bladder afferent function, and some of drug (e.g. mirabegron) inhibits the afferent activities through the suppression of the bladder myogenic microcontractions in normal or pathophysiological conditions.

Spontaneous synaptic drive in detrusor smooth muscle: computational investigation and implications for urinary bladder function

The detrusor, a key component of the urinary bladder wall, is a densely innervated syncytial smooth muscle tissue. Random spontaneous release of neurotransmitter at neuromuscular junctions (NMJs) in the detrusor gives rise to spontaneous excitatory junction potentials (SEJPs). These sub-threshold passive signals not only offer insights into the syncytial nature of the tissue, their spatio-temporal integration is critical to the generation of spontaneous neurogenic action potentials which lead to focal contractions during the filling phase of the bladder. Given the structural complexity and the contractile nature of the tissue, electrophysiological investigations on spatio-temporal integration of SEJPs in the detrusor are technically challenging. Here we report a biophysically constrained computational model of a detrusor syncytium overlaid with spatially distributed innervation, using which we explored salient features of the integration of SEJPs in the tissue and the key factors that contribute to this integration. We validated our model against experimental data, ascertaining that observations were congruent with theoretical predictions. With the help of comparative studies, we propose that the amplitude of the spatio-temporally integrated SEJP is most sensitive to the inter-cellular coupling strength in the detrusor, while frequency of observed events depends more strongly on innervation density. An experimentally testable prediction arising from our study is that spontaneous release frequency of neurotransmitter may be implicated in the generation of detrusor overactivity. Set against histological observations, we also conjecture possible changes in the electrical activity of the detrusor during pathology involving patchy denervation. Our model thus provides a physiologically realistic, heuristic framework to investigate the spread and integration of passive potentials in an innervated syncytial tissue under normal conditions and in pathophysiology.

Contractile elements and their sympathetic regulations in the pig urinary bladder: a species and regional comparative study

Contractile behaviour of the urinary bladder and its sympathetic inhibition during storage phases are not well understood. Here, we explore muscularis mucosae (MM) as a predominant mucosal contractile element and the capability of sympathetic nerves to relax detrusor smooth muscle (DSM) or MM. Distribution of α-smooth muscle actin (α-SMA)-immunoreactive cells was compared in pig, human, guinea pig, rat and mouse bladders by immunohistochemistry, while contractility of the bladder mucosa was compared in these species by isometric tension recordings. In pig, human and guinea pig bladders, DSM and MM located in the lamina propria expressed α-SMA immunoreactivity, while both rat and mouse bladders lacked a MM. Consistent with this presence or absence of MM, bladder mucosa of pig, human and guinea pig but not rat and mouse developed spontaneous phasic contractions (SPCs). Distribution of tyrosine hydroxylase (TH)-immunoreactive sympathetic nerve fibres was compared in pig DSM, MM, trigone and urethra, as were their sympathetic nerve-evoked contractile/relaxing responses examined. In pig DSM or MM, where TH-immunoreactive sympathetic fibres exclusively projected to the vasculature, sympathetic relaxations were difficult to demonstrate. In contrast, sympathetic contractions were invariably evoked in pig trigone and urethra where the smooth muscle cells receive TH-immunoreactive sympathetic innervations. Thus, SPCs of bladder mucosa appear to predominantly arise from the MM displaying species differences. Despite the currently accepted concept of sympathetic nerve-mediated DSM relaxation during the storage phase, it is unlikely that neurally released noradrenaline acts on β-adrenoceptors to relax either DSM or MM due to the anatomical lack of sympathetic innervation.

Is nocturnal enuresis a predisposing factor for the overactive bladder?

Background/aim

This study aimed to perform a limited observational study to ascertain whether there is statistical support that nocturnal enuresis (NE) is a predisposing factor in the development of overactive bladder (OAB).

Materials and methods

The authors recruited patients diagnosed with OAB over a period of twelve months, and those who declared a history of NE were asked additional questions regarding the features of their NE.

Results

A total of 285 patients were diagnosed with overactive bladder, and 98 (34.38%) of them had previously displayed NE symptoms that had diminished before reaching the median age of 9.83. Separation of patients by sex revealed a male majority (58.16%). Additionally, most patients had urban origins (75.51%). The median time span from remission of NE to diagnosis of OAB was 24.79 years, and the median age at which patients began to suffer was 31.80 years. Behavioral factors (smoking, alcohol consumption) and psychological and infectious factors (past history of urinary tract infection) were identified at varying degrees.

Conclusion

The presence of NE in a third of the patients who developed over time OAB and the earlier onset of OAB for these patients suggests a causal physiopathological relationship between NE and OAB. The preponderance of urban patients confirms the existence of acquired urban triggering factors of OAB (nutritious, social, or professional).

New Diagnostics for Male Lower Urinary Tract Symptoms

PURPOSE OF REVIEW

Lower urinary tract symptoms (LUTS) is a common constellation of symptoms that affect the aging male population with an astonishing prevalence. New technology and new uses of established technology are being used to help further evaluate LUTS in the male population and help guide treatment options. This review focuses on the developments and future directions in diagnostic modalities for evaluation of male LUTS, focusing on evaluation of both the filling and voiding phases of micturition.

RECENT FINDINGS

New techniques in evaluating the voiding phase include penile cuff test, external pressure sensing condom catheter, ultrasound measurement of detrusor wall thickness, ultrasound measurement of intravesical prostatic protrusion, doppler ultrasound and NIRS technology. Evaluation of the filling phase is still undergoing much development and requires additional validation studies. The techniques undergoing evaluation include sensation meters during UDS, assessing bladder micromotion and wall rhythm, assessing detrusor wall biomechanics, ultrasound measurement of detrusor wall thickness, pelvic doppler ultrasound, as well as functional brain imaging including fNIRS and fMRI.

SUMMARY

The development of novel, non-invasive, diagnostic tools have the potential for better evaluation of LUTS with earlier and enhanced treatments. This will likely improve the quality of life for men with LUTS.

Functional changes in low- and high-threshold afferents in obstruction-induced bladder overactivity

Neural mechanisms of lower urinary tract symptoms in obstruction-induced bladder overactivity remain unclear. We made the first single unit recordings from different types of spinal afferents to determine the effects of bladder outlet obstruction in guinea pigs. A model of gradual bladder outlet obstruction in male guinea pigs was used to produce overactive bladder. Conscious voiding was assessed in metabolic cages, and micturition was recorded in anesthetized guinea pigs in vivo. Single unit extracellular recordings were made ex vivo from spinal afferent nerves in flat sheet preparations of the bladder. Guinea pigs with partially obstructed bladders showed a significant increase in conscious voiding frequency compared with sham-operated guinea pigs. Also, nonvoiding contractions increased significantly in both frequency and amplitude. Although spontaneous firing of low-threshold bladder afferents was increased, their stretch-induced firing was reduced. The proportion of capsaicin-sensitive low-threshold afferents increased in obstructed bladders. Interestingly, spontaneous and stretch-induced firing were both significantly increased in high-threshold afferents after obstruction. In summary, sensory signaling increased in the obstructed bladder during the filling phase. This is largely mediated by low-threshold stretch-sensitive afferents that are activated by increased local nonvoiding contractions. Increased spontaneous firing by high-threshold afferents also contributes. Our findings revealed a complex effect of bladder outlet obstruction on different types of bladder afferents that needs consideration for potential therapeutic targeting of lower urinary tract symptoms in obstruction-induced bladder overactivity.

Effect of high-fat diet-induced obesity on the small-conductance Ca2+-activated K+ channel function affecting the contractility of rat detrusor smooth muscle

PURPOSE

Obesity usually induces overactive bladder (OAB) associated with detrusor overactivity, which is related to increased contractility of the detrusor smooth muscle (DSM). Small-conductance Ca²⁺-activated K⁺ (SK) channels play a constitutive role in the regulation of DSM contractility. However, the role of SK channels in the DSM changes in obesity-related OAB is still unknown. Here, we tested the hypothesis that obesity-related OAB is associated with reduced expression and activity of SK channels in DSM and that SK channels activation is a potential treatment for OAB.

METHODS

Female Sprague-Dawley rats were fed a normal diet (ND) or a high-fat diet (HFD) and weighed after 12 weeks. Urodynamic studies, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and isometric tension recording were performed.

RESULTS

Increased average body weights and urodynamically demonstrated OAB were observed in HFD rats. qRT-PCR experiments revealed a decrease in the mRNA expression level of SK channel in DSM tissue of the HFD rats. Isometric tension recordings indicated an attenuated relaxation effect of NS309 on the spontaneous phasic and electrical field stimulation-induced contractions that occurred via SK channel activation in HFD DSM strips.

CONCLUSIONS

Reduced expression and activity of SK channels in the DSM contribute to obesity-related OAB, indicating that SK channels are a potential therapeutic target for OAB.

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

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

Investigation of the Syncytial Nature of Detrusor Smooth Muscle as a Determinant of Action Potential Shape

Unlike most excitable cells, certain syncytial smooth muscle cells are known to exhibit spontaneous action potentials of varying shapes and sizes. These differences in shape are observed even in electrophysiological recordings obtained from a single cell. The origin and physiological relevance of this phenomenon are currently unclear. The study presented here aims to test the hypothesis that the syncytial nature of the detrusor smooth muscle tissue contributes to the variations in the action potential profile by influencing the superposition of the passive and active signals. Data extracted from experimental recordings have been compared with those obtained through simulations. The feature correlation studies on action potentials obtained from the experimental recordings suggest the underlying presence of passive signals, called spontaneous excitatory junction potentials (sEJPs). Through simulations, we are able to demonstrate that the syncytial organization of the cells, and the variable superposition of the sEJPs with the "native action potential", contribute to the diversity in the action potential profiles exhibited. It could also be inferred that the fraction of the propagated action potentials is very low in the detrusor. It is proposed that objective measurements of spontaneous action potential profiles can lead to a better understanding of bladder physiology and pathology.

Automated quantification of low amplitude rhythmic contractions (LARC) during real-world urodynamics identifies a potential detrusor overactivity subgroup

Objectives

Detrusor overactivity (DO) is characterized by non-voiding detrusor smooth muscle contractions during the bladder filling phase and often contributes to overactive bladder. In some patients DO is observed as isolated or sporadic contractions, while in others DO is manifested as low amplitude rhythmic contractions (LARC). The aim of this study was to develop an objective method to quantify LARC frequencies and amplitudes in urodynamic studies (UDS) and identify a subgroup DO of patients with LARC.

Methods

An automated Fast Fourier Transform (FFT) algorithm was developed to analyze a 205-second region of interest of retrospectively collected “real-world” UDS ending 30 seconds before voiding. The algorithm was designed to identify the three largest rhythmic amplitude peaks in vesical pressure (P_ves) in the 1.75–6 cycle/minute frequency range. These peak P_ves amplitudes were analyzed to determine whether they were 1) significant (above baseline P_ves activity) and 2) independent (distinct from any in abdominal pressure (P_abd) rhythm).

Results

95 UDS met criteria for inclusion and were analyzed with the FFT algorithm. During a blinded visual analysis, a neurourologist/urodynamicist identified 52/95 (55%) patients as having DO. The FFT algorithm identified significant and independent (S&I) LARC in 14/52 (27%) patients with DO and 0/43 patients (0%) without DO, resulting in 100% specificity and a significant association (Fischer’s exact test, p<0.0001). The average slowest S&I LARC frequency in this DO subgroup was 3.20±0.34 cycles/min with an amplitude of 8.40±1.30 cm-H₂O. This algorithm can analyze individual UDS in under 5 seconds, allowing real-time interpretation.

Conclusions

An FFT algorithm can be applied to “real-world” UDS to automatically characterize the frequency and amplitude of underlying LARC. This algorithm identified a potential subgroup of DO patients with LARC.

The efficacy of mirabegron in the treatment of urgency and the potential utility of combination therapy

Urgency is the prevalent and most bothersome symptom of overactive bladder (OAB) and the treatment of urgency is the primary objective in the management of OAB. Urgency has a major impact on other symptoms of OAB and culminates in an increased frequency of micturition and reduced volume voided, which may contribute to shorter intervals between the need to void. Antimuscarinic agents and mirabegron, a β3-adrenoceptor agonist, constitute the main oral pharmacotherapeutic options for the treatment of urgency and other OAB symptoms. The reduction of urgency and other OAB symptoms significantly improve health-related quality of life. This review will explore the distinct mechanisms of action and effects of antimuscarinic agents and mirabegron, in relation to their effect on the pathophysiology of urgency. The review will also provide an overview of the various validated measurements of urgency and the numerous clinical trials regarding antimuscarinic agent monotherapy, mirabegron monotherapy, or combination treatment with mirabegron added on to the antimuscarinic agent solifenacin. A narrative review of the literature relating to pathophysiology of urgency, the validated measurements of urgency, and clinical trials relating to the pharmacological treatment of urgency. Antimuscarinic agent monotherapy, mirabegron monotherapy, or combination treatment with mirabegron added on to the antimuscarinic agent solifenacin statistically significantly reduce the symptoms of urgency compared with placebo. Combination therapy with mirabegron added on to solifenacin also statistically significantly reduces the symptoms of severe urgency compared with antimuscarinic agent monotherapy. A critique of the clinical benefits of combination therapy is also provided. Combination therapy provides an alternative treatment in patients with OAB that includes urgency who respond poorly to first-line monotherapy and who may otherwise often move on to more invasive treatments.

Lower Urinary Tract Symptoms in Subjects with Subclinical Cerebral White Matter Lesions

Aim

We assessed the impact of cerebral white matter lesions (WMLs) on lower urinary tract symptoms in subjects with normal neurological and cognitive function.

Methods

A cohort of community-dwelling subjects aged ≥65 years were recruited to undergo MRI brain assessment. WMLs were graded using the Fazekas scale from 0 to 3. A separate telephone interview was carried out to assess the urinary symptoms in these subjects using the questionnaire Overactive Bladder-Validated 8-Question Awareness Tool (OAB-V8).

Results

800 community-dwelling elderly subjects were recruited to undergo MRI brain. In this cohort, 431 subjects responded to the telephone interview concerning their urinary symptoms. Among the respondents, 21.1% did not exhibit any WML on their MRI brain. Most of the subjects (52.6%) exhibited grade 1 WML. On logistic regression, age was found to be positively correlated with the Fazekas score (correlation coefficient 0.203, p ≤ 0.01). Using a cutoff of 8 on OAB-V8, 22% of the respondents experienced OAB. Presence of WML, hypertension, or diabetes mellitus was not found to be correlated with storage urinary symptoms or OAB-V8 total score. Multiple logistic regression analysis did not show the presence of WML to be associated with the diagnosis of OAB (adjusted OR 1.13, 95% CI 0.65–1.96, p=0.659).

Conclusions

WML is associated with age and is common in the elderly population. Mild WML is subclinical, with no obvious neurological and urinary symptoms. Our cohort did not demonstrate a relationship between WML and lower urinary tract symptoms.

Effects of caveolae depletion and urothelial denudation on purinergic and cholinergic signaling in healthy and cyclophosphamide-induced cystitis in the rat bladder

Cholesterol rich membrane invaginations, caveolae, have important roles in various cellular activities, one of them being signal transduction. This signaling pathway seems to be affected during various bladder disorders and the current study aimed to elucidate the plausible involvement of caveolae mediated signal transduction during cyclophosphamide induced cystitis. Furthermore, the urothelial cholinergic part of ATP-evoked contractions and its possible link to caveolae were investigated. Cholinergic, as well as purinergic, contractile responses in rat urinary bladders were examined using a classic organ bath set-up with full-thickness strip preparations or a whole bladder model that enabled luminal administration of substances. Furthermore, sub groups with and without urothelium were examined. The expression of caveolin-1 was also tested using western blot and immunofluorescence. Caveolae cholesterol depletion by methyl-β-cyclodextrin entailed a significant decrease of ATP-evoked bladder contractility. Interestingly, after muscarinic blockade the ATP induced contractions were significantly reduced in the same manner. Furthermore, this atropine-sensitive part of ATP-evoked responses was absent in denuded as well as inflamed bladders. A tendency towards a reduced expression of caveolin-1 was observed in rats with experimental cystitis. The cholinergic part of ATP-induced contractile responses seemed to be affected by urothelium denudation as well as caveolae depletion. Removing one of these structures nullifies the effect of the other, suggesting an important interaction between the urothelium and the caveolar structures. These effects are absent in inflamed animals and might be one pathophysiological aspect behind BPS/IC.

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.

Effect of pregnancy on cooling tone and rhythmic contractions of the rat urinary bladder

OBJECTIVES

Pregnancy is a physiological alteration that can affect urinary bladder. Cooling of urinary bladder smooth muscle is known as a potent stimulus to micturition due to an increase in muscle tone. The current study investigates the effects of pregnancy on cooling tone and on the rhythmic contractions of the urinary bladder.

METHODS

Twenty-four rats were used in this study as control group (non-pregnant) and pregnant group (18-20-day pregnancy). Isolated rat urinary muscle strips were suspended in organ baths containing Krebs' solution for isometric tension recording.

RESULTS

Cooling from 37 to 5 °C induced a rapid and reproducible increase in basal tone, proportional to cooling temperature. Cooling also increased the rhythmic activity (amplitude and frequency) at 30 and 25 °C, then decreased at 20 °C, and abolished at 15-5 °C. These responses were more pronounced in pregnant group than in control group. Rhythmic contractions were abolished in calcium-free, EGTA (1 mM)-containing Krebs' solution and in the presence of nifedipine, while they were not affected by CPA or TTX in both groups. Our investigation showed that the influx of extracellular calcium is important in inducing the rhythmic contractions.

CONCLUSIONS

Pregnancy increases cooling-induced contraction in pregnant rat urinary preparations and its rhythmic contractions including amplitude and frequency than non-pregnant rat. Rhythmic contractions are myogenic in nature and highly extracellular calcium dependent. They may play a crucial role in urinary bladder overactivity and incontinence during pregnancy.

Increased Expression of TREK-1 K+ Channel in the Dorsal Root Ganglion of Rats with Detrusor Overactivity After Partial Bladder Outlet Obstruction

Background

Changes in expression and activity of ion channels are important pathophysiological mechanisms underlying detrusor overactivity (DO) in partial bladder outlet obstruction (PBOO). The objective of this study was to examine the expression of TREK-1 channel in the bladder and central nervous system of DO rats.

Material/Methods

Thirty Sprague-Dawley rats were subjected to PBOO operations and those displaying non-voiding contractions (NVCs) in cystometry were classified as DO. Sham-operated rats without NVCs in cystometry served as controls. The expression and distribution of TREK-1 in the bladder, spinal cord, and dorsal root ganglion (DRG) were detected by real time-PCR, western blot, and immunohistochemistry.

Results

TREK-1 channel expression in the DRG was significantly increased at the mRNA level (11.20±3.762 vs. 3.209±1.505, P<0.01) and protein level (2.195±0.058 vs. 1.713±0.066, P<0.01) in DO rats as compared to control rats. However, the expression of TREK-1 mRNA in the bladder (1.380±0.810 vs. 4.206±3.827, P>0.05) and spinal cord (0.764±0.357 vs. 0.696±0.188, P>0.05) was comparable between the 2 groups. Immunohistochemistry showed enhanced immunoreactive signals of TREK-1 channel in the DRG, but not in the spinal cord and bladder.

Conclusions

TREK-1 channel was upregulated in the DRG of DO rats after chronic PBOO, which might suppress neuronal excitability and play a protective role in bladder overactivity in PBOO.

Regulation of Spontaneous Contractions in Intact Rat Bladder Strips and the Effects of Hydrogen Peroxide

Enhanced spontaneous contractions are associated with overactive bladder. Elevated levels of reactive oxygen species might contribute to enhanced spontaneous contractions. We investigated the regulation of spontaneous contractions and the effects of hydrogen peroxide (H₂O₂) in intact rat bladder strips. The spontaneous contractions were measured using a tissue bath system. The vehicle or the specific activators/blockers were applied and followed by the application of 0.003 g% H₂O₂. The basal tension, amplitude, and frequency of spontaneous contractions were quantified. Nisoldipine and bisindolylmaleimide 1 had no effects on spontaneous contractions. SKF96365 and Y27632 decreased basal tension and amplitude. Ryanodine slightly increased frequency. Both iberiotoxin and NS-1619 increased amplitude. Apamin reduced frequency but increased amplitude. NS-309 inhibited both the amplitude and frequency. The basal tension and amplitude increased when H₂O₂ was applied. Pretreatment with NS-309 inhibited H₂O₂-elicited augmented amplitude and frequency, while pretreatment with Y-27632 inhibited the augmented basal tension. The combined application of NS-309 and Y27632 almost eliminated spontaneous contractions and its augmentation induced by H₂O₂. In conclusion, Ca²⁺ influx, Rho kinase activation, and SK channel inactivation play important roles in spontaneous contractions in intact bladder strips, whereas only latter two mechanisms may be involved in H₂O₂-elicited increased spontaneous contractions.

Is there "brain OAB" and how can we recognize it? International Consultation on Incontinence-Research Society (ICI-RS) 2017

AIMS

In light of mounting evidence supporting the association of brain regions with the control of urine storage and voiding, the high placebo effect in OAB studies as well as certain anecdotal observations from clinical practice with OAB patients, the role of the brain in OAB was explored.

METHODS

At the ICI-RS 2017 meeting, a panel of Functional Urologists and Basic Scientists presented literature data generating a proposal to discuss whether there is "brain OAB" and how we could recognize it.

RESULTS

Existing data point toward organic brain causes of OAB, in particular concerning white matter disease (WMD) and aging, but with currently speculative mechanisms. Imaging techniques have revealed connectivity changes between brain regions which may explain brain-peripheral interactions in OAB patients, further to acknowledged structural and functional changes in the central nervous system (CNS). Furthermore, psychological disorders like stress and depression have been identified as causes of OAB, with animal and human studies proposing a neurochemical and neuroendocrine pathophysiological basis, involving either the serotoninergic system or the hypothalamic-pituitary-adrenal axis. Finally, childhood data suggest that OAB could be a developmental disorder involving the CNS, although childhood OAB could be a different condition than that of adults in many children.

CONCLUSIONS

Future research should aim to identify the pathogenesis of WMD and the aging processes affecting the brain and the bladder, with possible benefits in prevention strategies, as well as connectivity disorders within the CNS, the pathophysiology of OAB in childhood and the neurochemical pathways connecting affective disorders with OAB.

Proteomic Analysis of Urothelium of Rats with Detrusor Overactivity Induced by Bladder Outlet Obstruction

Overactive bladder (OAB) syndrome is a condition that has four symptoms: urgency, urinary frequency, nocturia, and urge incontinence and negatively affects a patient's life. Recently, it is considered that the urinary bladder urothelium is closely linked to pathogenesis of OAB. However, the mechanisms of pathogenesis of OAB at the molecular level remain poorly understood, mainly because of lack of modern molecular analysis. The goal of this study is to identify a potential target protein that could act as a predictive factor for effective diagnosis and aid in the development of therapeutic strategies for the treatment of OAB syndrome. We produced OAB in a rat model and performed the first proteomic analysis on the mucosal layer (urothelium) of the bladders of sham control and OAB rats. The resulting data revealed the differential expression of 355 proteins in the bladder urothelium of OAB rats compared with sham subjects. Signaling pathway analysis revealed that the differentially expressed proteins were mainly involved in the inflammatory response and apoptosis. Our findings suggest a new target for accurate diagnosis of OAB that can provide essential information for the development of drug treatment strategies as well as establish criteria for screening patients in the clinical environment.