Cystometric evidence that capsaicin-sensitive nerves modulate the afferent branch of micturition reflex in humans

TRP (transient receptor potential) ion channel family: structures, biological functions and therapeutic interventions for diseases

Transient receptor potential (TRP) channels are sensors for a variety of cellular and environmental signals. Mammals express a total of 28 different TRP channel proteins, which can be divided into seven subfamilies based on amino acid sequence homology: TRPA (Ankyrin), TRPC (Canonical), TRPM (Melastatin), TRPML (Mucolipin), TRPN (NO-mechano-potential, NOMP), TRPP (Polycystin), TRPV (Vanilloid). They are a class of ion channels found in numerous tissues and cell types and are permeable to a wide range of cations such as Ca²⁺, Mg²⁺, Na⁺, K⁺, and others. TRP channels are responsible for various sensory responses including heat, cold, pain, stress, vision and taste and can be activated by a number of stimuli. Their predominantly location on the cell surface, their interaction with numerous physiological signaling pathways, and the unique crystal structure of TRP channels make TRPs attractive drug targets and implicate them in the treatment of a wide range of diseases. Here, we review the history of TRP channel discovery, summarize the structures and functions of the TRP ion channel family, and highlight the current understanding of the role of TRP channels in the pathogenesis of human disease. Most importantly, we describe TRP channel-related drug discovery, therapeutic interventions for diseases and the limitations of targeting TRP channels in potential clinical applications.

The translational implications of the science behind the overactive bladder and the role of OnabotulinumtoxinA

Urinary incontinence (UI) is a very common condition that can affect patients of all ages and the commonest cause is an overactive bladder (OAB). Most patients with OAB were treated with pharmacotherapy and major surgery. Over 25 years ago, Dasgupta, Fowler et al. studied the presence and role of C fibres in the human bladder which are highly sensitive to capsaicin, the active ingredient of chillies. When capsaicin was instilled into patients' bladders as a synthetic solution, it was found to be highly effective in some patients. Capsaicin was later replaced by Resiniferatoxin. Both toxins desensitised C-fibres through the capsaicin receptor, TRPV1, without any lasting damage to the bladder itself. The discovery of botulinum toxin and its use in the treatment of OAB represents a major breakthrough, in the treatment of OAB. Another key innovation was the development of technique to administer the drug under local anaesthesia which allowed numerous patients to benefit from treatment who would otherwise have been precluded because of the need for injection under general anaesthetic. After extensive trials over many years Botox (OnabotulinumtoxinA) is now licensed for use in OAB. Compared to other treatments for overactive bladder, OnabotulinumtoxinA is more cost-effective and less invasive. It is thought to have changed the quality of life of an estimated 5 million patients worldwide.

Acute Intravesical Capsaicin for the Study of TRPV1 in the Lower Urinary Tract: Clinical Relevance and Potential for Innovation

Capsaicin acts on sensory nerves via vanilloid receptors. TRPV1 has been extensively studied with respect to functional lower urinary tract (LUT) conditions in rodents and humans. We aimed to (1) provide background information on capsaicin and TRPV1 and its mechanisms of action and basis for clinical use, (2) review the use of acute intravesical capsaicin instillation (AICI) in rodents to mimic various LUT disorders in which capsaicin sensitive C-fibers are involved and (3) discuss future innovative treatments. A comprehensive search of the major literature databases until June 2022 was conducted. Both capsaicin-sensitive and resistant unmyelinated bladder afferent C-fibers are involved in non-neurogenic overactive bladder/detrusor overactivity (OAB/DO). AICI is a suitable model to study afferent hyperactivity mimicking human OAB. Capsaicin-sensitive C-fibers are also involved in neurogenic DO (NDO) and potential targets for NDO treatment. AICI has been successfully tested for NDO treatment in humans. Capsaicin-sensitive bladder afferents are targets for NDO treatment. TRPV1-immunoreactive nerve fibers are involved in the pathogenesis of interstitial cystitis/painful bladder syndrome (IC/PBS). The AICI experimental model appears relevant for the preclinical study of treatments targeting bladder afferents for refractory IC/BPS. The activity of capsaicin-sensitive bladder afferents is increased in experimental bladder outlet obstruction (BOO). The AICI model may also be relevant for bladder disorders resulting from C-fiber hyperexcitabilities related to BOO. In conclusion, there is a rationale for the selective blockade of TRPV1 channels for various bladder disorders. The AICI model is clinically relevant for the investigation of pathophysiological conditions in which bladder C-fiber afferents are overexcited and for assessing innovative treatments for bladder disorders based on their pathophysiology.

Beyond Neuronal Heat Sensing: Diversity of TRPV1 Heat-Capsaicin Receptor-Channel Functions

Transient receptor potential vanilloid 1 (TRPV1) is a calcium-permeable ion channel best known for its ability to be gated by the pungent constituent of red chili pepper, capsaicin, and related chemicals from the group of vanilloids as well as by noxious heat. As such, it is mostly expressed in sensory neurons to act as a detector of painful stimuli produced by pungent chemicals and high temperatures. Its activation is also sensitized by the numerous endogenous inflammatory mediators and second messengers, making it an important determinant of nociceptive signaling. Except for such signaling, though, neuronal TRPV1 activation may influence various organ functions by promoting the release of bioactive neuropeptides from sensory fiber innervation organs. However, TRPV1 is also found outside the sensory nervous system in which its activation and function is not that straightforward. Thus, TRPV1 expression is detected in skeletal muscle; in some types of smooth muscle; in epithelial and immune cells; and in adipocytes, where it can be activated by the combination of dietary vanilloids, endovanilloids, and pro-inflammatory factors while the intracellular calcium signaling that this initiates can regulate processes as diverse as muscle constriction, cell differentiation, and carcinogenesis. The purpose of the present review is to provide a clear-cut distinction between neurogenic TRPV1 effects in various tissues consequent to its activation in sensory nerve endings and non-neurogenic TRPV1 effects due to its expression in cell types other than sensory neurons.

Current standard of care in treatment of bladder pain syndrome/interstitial cystitis

Bladder pain syndrome/interstitial cystitis (BPS/IC) is a debilitating, systemic pain syndrome with a cardinal symptom of bladder related pain with associated systemic symptoms. It is characterized by an inflammation that partially or completely destroys the mucus membrane and can extend into the muscle layer; however, the etiology and pathogenesis is still enigmatic. It has been suggested that mast cell activation, defects in the glycosaminoglycan layer, non-functional proliferation of bladder epithelial cells, neurogenic inflammation, microvascular abnormalities in the submucosal layer, autoimmunity and infectious causes may cause BPS/IC. Available treatment options include general relaxation techniques, patient education, behavioral treatments, physical therapy, multimodal pain therapy, oral (amitriptyline, cimetidine, hydroxyzine) and intravesical treatments (heparin, lidocaine, hyaluronic acid and chondroitin sulfate), hydrodistension and other more invasive treatments. Available treatments are mostly not based on a high level of evidence. Lack of understanding of disease mechanisms has resulted in lack of targeted therapies on this area and a wealth of empirical approaches with usually inadequate efficacy. The aim of this article is to review the available evidence on the pathophysiological mechanisms of BPS/IC as they relate to available treatment options.

Evaluation of the Sympathetic Skin Response in Men with Chronic Prostatitis: A Case-Control Study

BACKGROUND

Etiological factors involved in chronic prostatitis (CP) type IIIb and chronic pelvic pain are not sufficiently understood; however, the nervous system has a significant role in the generation and maintenance of chronic pelvic pain. This study was designed to evaluate the sympathetic skin response (SSR) in men with CP type IIIb compared to normal population.

PATIENTS AND METHODS

For two years, about 14 patients suffering from CP type IIIb according to NIH-CPSI and 26 healthy control men were enrolled in this study. SSR was performed in all the subjects with a standard method. Bilateral palmar and plantar latency and amplitude of SSR were recorded in response to the median and tibial nerve electrical stimulations. SSR is considered abnormal when the latency is prolonged, and the amplitude reduced.

RESULTS

SSR latency in the left and right median nerve was significantly prolonged in the patient with CP type IIIb group compared to the control group (p=0.039 and 0.006, respectively). Additionally, the amplitude was reduced in patients with CP type IIIb group compared to the control group in the right tibial nerve (p=0.017).

CONCLUSION

Sympathetic skin response may be a helpful diagnostic test for men with chronic prostatitis type IIIb. However, this observation needs to be validated in a large sample cohort study with long-term follow-up.

Modulation of Sensory Nerve Function by Insulin: Possible Relevance to Pain, Inflammation and Axon Growth

Insulin, besides its pivotal role in energy metabolism, may also modulate neuronal processes through acting on insulin receptors (InsRs) expressed by neurons of both the central and the peripheral nervous system. Recently, the distribution and functional significance of InsRs localized on a subset of multifunctional primary sensory neurons (PSNs) have been revealed. Systematic investigations into the cellular electrophysiology, neurochemistry and morphological traits of InsR-expressing PSNs indicated complex functional interactions among specific ion channels, proteins and neuropeptides localized in these neurons. Quantitative immunohistochemical studies have revealed disparate localization of the InsRs in somatic and visceral PSNs with a dominance of InsR-positive neurons innervating visceral organs. These findings suggested that visceral spinal PSNs involved in nociceptive and inflammatory processes are more prone to the modulatory effects of insulin than somatic PSNs. Co-localization of the InsR and transient receptor potential vanilloid 1 (TRPV1) receptor with vasoactive neuropeptides calcitonin gene-related peptide and substance P bears of crucial importance in the pathogenesis of inflammatory pathologies affecting visceral organs, such as the pancreas and the urinary bladder. Recent studies have also revealed significant novel aspects of the neurotrophic propensities of insulin with respect to axonal growth, development and regeneration.

TRP Channels as Lower Urinary Tract Sensory Targets

Several members of the transient receptor potential (TRP) superfamily, including TRPV1, TRPV2, TRPV4, TRM4, TRPM8 and TRPA1, are expressed in the lower urinary tract (LUT), not only in neuronal fibers innervating the bladder and urethra, but also in the urothelial and muscular layers of the bladder and urethral walls. In the LUT, TRP channels are mainly involved in nociception and mechanosensory transduction. Animal studies have suggested the therapeutic potential of several TRP channels for the treatment of both bladder over- and underactivity and bladder pain disorders,; however translation of this finding to clinical application has been slow and the involvement of these channels in normal human bladder function, and in various pathologic states have not been established. The development of selective TRP channel agonists and antagonists is ongoing and the use of such agents can be expected to offer new and important information concerning both normal physiological functions and possible therapeutic applications.

Research progress of capsaicin responses to various pharmacological challenges

Capsaicin, a well known vanilloid, has shown evidence of an ample variety of biological effects which make it the target of extensive research ever since its identification. In spite of the fact that capsaicin causes health hazards in quite a few ways, yet, the verity cannot be ignored that capsaicin has several therapeutic implications. In patients with hypersensitive bladders, vesical instillation of 1 mM capsaicin markedly improved urinary frequency and urge incontinence. Again, administration of capsaicin favors an augmentation in lipid mobilization and a decrease in adipose tissue mass. Topical capsaicin cream as well decreases postsurgical neuropathic pain and is preferred by patients over a placebo among other therapies. Several in vitro studies have revealed that capsaicin results in growth arrest in some transformed cell lines. Furthermore, capsaicin has been proven to be an undeniably exciting molecule and remains a valuable drug for alleviating pain and itch. It has been recognized that capsaicinoids are the most potential agonists of capsaicin receptor (TRPV1). However, vanilloids could exert the beneficial effects not only through the receptor-dependent pathway but also through the receptor-independent one. The involvement of serotonin, neuropeptide Substance P and somatostatin in the pharmacological actions of capsaicin has been expansively investigated. Better understanding of the established TRPV1 receptor mechanism as well as exploring other possible receptor mechanism may publicize other new clinical efficacies of capsaicin. Further, clinical studies are required in several of these conditions to establish the efficacy of capsaicin.

Intravesical vanilloids for treating neurogenic lower urinary tract dysfunction in patients with multiple sclerosis: A systematic review and meta-analysis. A report from the Neuro-Urology Promotion Committee of the International Continence Society (ICS)

AIMS

To systematically assess all available evidence on efficacy and safety of vanilloids for treating neurogenic lower urinary tract dysfunction (NLUTD) in patients with multiple sclerosis (MS).

METHODS

This systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Studies were identified by electronic search of Cochrane register, Embase, Medline, Scopus, (last search January 8, 2016).

RESULTS

After screening of 7848 abstracts, 4 randomized controlled trials (RCTs) and 3 prospective cohort studies were included. Pooled data from three RCTs evaluating intravesical capsaicin showed the standardized mean difference to be -2.16 (95% confidence interval [CI] -2.87 to -1.45) in incontinence episodes per 24 h and -0.54 (95%CI -1.03 to -0.05) in voids per 24 h. There was no statistically significant effect on maximum cystometric capacity and maximum storage detrusor pressure. Overall, adverse events were reported by >50% of the patients, most commonly were pelvic pain, facial flush, worsening of incontinence, autonomic dysreflexia, urinary tract infection and haematuria. Risk of bias and confounding was relevant in both RCTs and non-RCTs.

CONCLUSIONS

Preliminary data suggest that intravesical vanilloids might be effective for treating NLUTD in patients with MS. However, the safety profile seems unfavorable, the overall quality of evidence is low and no licensed substance is currently available warranting well-designed, adequately sampled and properly powered RCTs.

Sex-dependent expression of TRPV1 in bladder arterioles

Transient receptor potential vanilloid type 1 (TRPV1) is a major nociceptive ion channel implicated in bladder physiology and/or pathophysiology. However, the precise expression of TRPV1 in neuronal vs. nonneuronal bladder cells is uncertain. Here we used reporter mouse lines (TRPV1-Cre:tdTomato and TRPV1^PLAP-nlacZ) to map expression of TRPV1 in postnatal bladder. TRPV1 was not detected in the urothelium, however, we found marked expression of TRPV1 lineage in sensory nerves, and surprisingly, in arterial/arteriolar smooth muscle (ASM) cells. Tomato fluorescence was prominent in the vesical arteries and in small-diameter (15-40 μm) arterioles located in the suburothelial layer with a near equal distribution in bladder dome and base. Notably, arteriolar TRPV1 expression was greater in females than in males and increased in both sexes after 90 days of age, suggesting sex hormone and age dependency. Analysis of whole bladder and vesical artery TRPV1 mRNA revealed a similar sex and developmental dependence. Pharmacological experiments confirmed functional TRPV1 protein expression; capsaicin increased intracellular Ca²⁺ in ∼15% of ASM cells from wild-type female bladders, but we observed no responses to capsaicin in bladder arterioles isolated from TRPV1-null mice. Furthermore, capsaicin triggered arteriole constriction that was rapidly reversed by the TRPV1 antagonist, BCTC. These data show that predominantly in postpubertal female mice, bladder ASM cells express functional TRPV1 channels that may act to constrict arterioles. TRPV1 may therefore play an important role in regulating the microcirculation of the female bladder, and this effect may be of significance during inflammatory conditions.

TRPV1: A Potential Drug Target for Treating Various Diseases

Transient receptor potential vanilloid 1 (TRPV1) is an ion channel present on sensory neurons which is activated by heat, protons, capsaicin and a variety of endogenous lipids termed endovanilloids. As such, TRPV1 serves as a multimodal sensor of noxious stimuli which could trigger counteractive measures to avoid pain and injury. Activation of TRPV1 has been linked to chronic inflammatory pain conditions and peripheral neuropathy, as observed in diabetes. Expression of TRPV1 is also observed in non-neuronal sites such as the epithelium of bladder and lungs and in hair cells of the cochlea. At these sites, activation of TRPV1 has been implicated in the pathophysiology of diseases such as cystitis, asthma and hearing loss. Therefore, drugs which could modulate TRPV1 channel activity could be useful for the treatment of conditions ranging from chronic pain to hearing loss. This review describes the roles of TRPV1 in the normal physiology and pathophysiology of selected organs of the body and highlights how drugs targeting this channel could be important clinically.

Bladder cancer and urothelial impairment: the role of TRPV1 as potential drug target

Urothelium, in addition to its primary function of barrier, is now understood to act as a complex system of cell communication that exhibits specialized sensory properties in the regulation of physiological or pathological stimuli. Furthermore, it has been hypothesized that bladder inflammation and neoplastic cell growth, the two most representative pathological conditions of the lower urinary tract, may arise from a primary defective urothelial lining. Transient receptor potential vanilloid channel 1 (TRPV1), a receptor widely distributed in lower urinary tract structures and involved in the physiological micturition reflex, was described to have a pathophysiological role in inflammatory conditions and in the genesis and development of urothelial cancer. In our opinion new compounds, such as curcumin, the major component of turmeric Curcuma longa, reported to potentiate the effects of the chemotherapeutic agents used in the management of recurrent urothelial cancer in vitro and also identified as one of several compounds to own the vanillyl structure required to work like a TRPV1 agonist, could be thought as complementary in the clinical management of both the recurrences and the inflammatory effects caused by the endoscopic resection or intravesical chemotherapy administration or could be combined with adjuvant agents to potentiate their antitumoral effect.

TRP channels in lower urinary tract dysfunction

Lower urinary tract dysfunction (LUTd) represents a major healthcare problem. Although it is mostly not lethal, associated social disturbance, medical costs, loss of productivity and especially diminished quality of life should not be underestimated. Although more than 15% of people suffer from a form of LUTd to some extent, pathophysiology often remains obscure. In the past 20 years, transient receptor potential (TRP) channels have become increasingly important in this field of research. These intriguing ion channels are believed to be the main molecular sensors that generate bladder sensation. Therefore, they are intensely pursued as new drug targets for both curative and symptomatic treatment of different forms of LUTd. TRPV1 was the first of its class to be investigated. Actually, even before this channel was cloned, it had already been targeted in the bladder, with clinical trials of intravesical capsaicin instillations. Several other polymodally gated TRP channels, particularly TRPM8, TRPA1 and TRPV4, also appear to play a prominent role in bladder (patho)physiology. With this review, we provide a brief overview of current knowledge on the role of these TRP channels in LUTd and their potential as molecular targets for treatment.

Transient receptor potential (TRP) channels: a clinical perspective

Transient receptor potential (TRP) channels are important mediators of sensory signals with marked effects on cellular functions and signalling pathways. Indeed, mutations in genes encoding TRP channels are the cause of several inherited diseases in humans (the so-called 'TRP channelopathies') that affect the cardiovascular, renal, skeletal and nervous systems. TRP channels are also promising targets for drug discovery. The initial focus of research was on TRP channels that are expressed on nociceptive neurons. Indeed, a number of potent, small-molecule TRPV1, TRPV3 and TRPA1 antagonists have already entered clinical trials as novel analgesic agents. There has been a recent upsurge in the amount of work that expands TRP channel drug discovery efforts into new disease areas such as asthma, cancer, anxiety, cardiac hypertrophy, as well as obesity and metabolic disorders. A better understanding of TRP channel functions in health and disease should lead to the discovery of first-in-class drugs for these intractable diseases. With this review, we hope to capture the current state of this rapidly expanding and changing field.

Emerging treatments for urinary incontinence

INTRODUCTION

Urinary incontinence (UI) is a common and distressing problem that can adversely affect a patient's quality of life. Medical treatment is integral in the management of UI, of which there are a number of novel therapeutic targets.

AREAS COVERED

In this review, an overview of UI and its associated burden on patients and on the healthcare system is provided. While there are many options for therapy currently available, the focus of this review is emerging therapies that may contribute in the near future to the management of UI.

EXPERT OPINION

Healthcare expenditures for diagnosis, evaluation and treatment are substantial and are increasing as the general population ages and as access to healthcare increases. Pharmacological therapy for stress UI is limited and autologous muscle-derived cell therapy holds great promise. Despite the myriad of antimuscarinics for urge UI, all those presently FDA approved have comparable efficacy and adverse events, despite advertisements that suggest otherwise. Antimuscarinics and β agonists are likely to remain mainstays of treatment as agents that act on novel targets such as transient receptor potential vanilloid type 1 and neurokinin-1 require further study.

New therapies in the treatment of overactive bladder

INTRODUCTION

Overactive bladder (OAB) is a common condition which affects both men and women across many age groups with significant impact on quality of life. There is currently an armamentarium of treatment options available ranging from conservative, medical therapy to radical surgeries. Increasing understanding of OAB is resulting in the rapid development of new therapies today.

AREAS COVERED

The purpose of this article was to summarise the latest developments in non-neurogenic OAB treatment, discuss the evidence and results of current and new treatment modalities available through review of published data and results presented at recent international meetings.

EXPERT OPINION

The ultimate goal in OAB therapy is to provide good clinical efficacy, safe, non-invasive and easy to administer. There is definitely room for development of new therapies in OAB and current progress is encouraging.

Urothelial signaling

The urothelium, which lines the inner surface of the renal pelvis, the ureters, and the urinary bladder, not only forms a high-resistance barrier to ion, solute and water flux, and pathogens, but also functions as an integral part of a sensory web which receives, amplifies, and transmits information about its external milieu. Urothelial cells have the ability to sense changes in their extracellular environment, and respond to chemical, mechanical and thermal stimuli by releasing various factors such as ATP, nitric oxide, and acetylcholine. They express a variety of receptors and ion channels, including P2X3 purinergic receptors, nicotinic and muscarinic receptors, and TRP channels, which all have been implicated in urothelial-neuronal interactions, and involved in signals that via components in the underlying lamina propria, such as interstitial cells, can be amplified and conveyed to nerves, detrusor muscle cells, and ultimately the central nervous system. The specialized anatomy of the urothelium and underlying structures, and the possible communication mechanisms from urothelial cells to various cell types within the bladder wall are described. Changes in the urothelium/lamina propria ("mucosa") produced by different bladder disorders are discussed, as well as the mucosa as a target for therapeutic interventions.

Modulation of TRPV1-dependent contractility of normal and diabetic bladder smooth muscle by analgesic toxins from sea anemone Heteractis crispa

AIMS

TRPV1-expressing, capsaicin (CAP)-sensitive afferent fibers innervating bladder in addition to sensory function also exhibit "efferent" features consisting in TRPV1-dependent release of tachykinins (TAC) affecting detrusor smooth muscle (DSM) contractions. Our aim was to investigate the effects of two novel polypeptide inhibitors of TRPV1 from the venom of tropical sea anemone Heteractis crispa, APHC1 and APHC3, on the contractions of DSM from bladders of normal and diabetic rats.

MAIN METHODS

Experiments were conducted on urothelium-devoid DSM strips from normal rats and rats 8weeks after streptozotocin-induced diabetes by means of contraction force measurements.

KEY FINDINGS

Pre-exposure of DSM strips to APHC1 or APHC3 (200nM) specifically inhibited CAP-induced, TRPV1-dependent contractions. Both peptides also transiently enhanced basal tone and spontaneous contractions of DSM strips followed by delayed suppression of electric field stimulation (EFS)-evoked nonadrenergic-noncholinergic (NANC) contractions. The decrease of the amplitude of EFS-evoked NANC contractions by АРНС1 or АРНС3 reached 38.5±3.4% and 25.1±1.6%, respectively, in normal DSM strips and 46.3±3.3% and 43.9±1.8%, respectively, in diabetic ones. APHC-peptide-induced transient enhancement of basal tone could be mimicked by serine protease inhibitor, 4-(2-aminoethyl)bezenesulfonyl fluoride (300 μM).

SIGNIFICANCE

Our results demonstrate that АРНС1 and АРНС3 may be considered as effective inhibitors of bladder contractility especially during diabetic cystopathy. Modality of action of APHC-polypeptides via the mechanisms involving decreased TRPV1-dependent release of TAC from bladder afferents and suppression of TAC degradation due to their activity as endogenous proteases inhibitors is proposed.

Neurogenic inflammation of Guinea-pig bladder

Capsaicin, substance P, and ovalbumin, instilled into the bladders of naive and ovalbumin (OVA) sensitized guineapigs caused inflammation, as indicated by increased vascular permeability. Histological changes after exposure to these compounds progressed with time from intense vasodilatation to marginalization of granulocytes followed by interstitial migration of leukocytes. In vitro incubation of guinea-pig bladder tissue with substance P and ovalbumin stimulated release of prostaglandin D₂ and leukotrienes. In vitro incubation of bladder tissue with capsaicin, OVA, prostaglandin D₂, leukotriene C₄, histamine, or calcium ionophore A-23587 all stimulated substance P release. These data suggest that bladder inflammation initiated by a variety of stimuli could lead to a cyclic pattern of release of inflammatory mediators and neuropeptides, which could result in amplification and persistence of cystitis after the inciting cause has subsided.

Capsaicin induces cycle arrest by inhibiting cyclin-dependent-kinase in bladder carcinoma cells

OBJECTIVE

Capsaicin is a specialized agonist of transient receptor potential vanilloid type 1 Ca2(+) channel, a member of the vanilloid receptor family of cation channels. We aimed to investigate the effects of capsaicin on the proliferation and cell death of human bladder cancer cells.

METHODS

Human bladder cancer cell line 5637 was cultured and the expression of transient receptor potential vanilloid type 1 verified by immunofluorescence and Western blot. Cells were given different disposals (different capsaicin concentration with/without pre-treating with capsazepine; capsazepine, acting as a competitive antagonist of capsaicin) to observe cell viability, cell cycle and cell death by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay and flow cytometry. The apoptosis indexes, such as intracellular production of reactive oxygen species and mitochondrial membrane potential were assessed to elucidate the potential mechanism of capsaicin effects in the cells.

RESULTS

Capsaicin decreased the viability of 5637 cells in a dose-dependent way. The flow cytometry outcome showed that capsaicin blocked the cell cycle in the G0/G1 period. The Western blot of cyclin-dependent-kinase involved in G1/S transfer verified this. Meanwhile, increased reactive oxygen species production and decreased mitochondrial membrane potential were detected in capsaicin-treated groups.

CONCLUSIONS

Capsaicin induces cell death through increased reactive oxygen species and decreased mitochondrial membrane potential. Furthermore, capsaicin inhibits the proliferation of 5637 bladder carcinoma cells by cycle arrest with the inhibition of CDK2, CDK4 and CDK6.

Standard Pharmacological Treatment and New Therapies for Overactive Bladder

The prevalence of overactive bladder (OAB) in adult males varies from 10.2% to 17.4%, and in females from 7.7 to 31.3. 16.5% of the adult population presents symptoms consistent with OAB; of these, 37.2% are actually affected. The OAB has a significant effect on the quality of life. Initial treatment includes behavioral therapy, physiotherapy and antimuscarinic drugs. In patients where behavioral modifications fail, treatment is associated with antimuscarinics. The antimuscarinic agents used to treat OAB showed some efficacy, but adverse events too, such as dry mouth, constipation, headache and blurred vision. In selected cases unresponsive to antimuscarinic therapy, it is possible to use second-line treatments represented by sacral neuromodulation and botulinum toxin type A both for idiopathic detrusor overactivity, where it is still an experimental treatment, and for neurogenic cases with 2011 FDA approval. Surgical options represent the last choice for selected cases.

From urgency to frequency: facts and controversies of TRPs in the lower urinary tract

The members of transient receptor potential (TRP) superfamily of cationic ion channels represent universal sensors, which convert multiple exogenous and endogenous chemical and physical stimuli into electrical and functional cellular responses. TRPs are widely distributed in many different tissues, and expression of numerous TRP types has been reported in lower urinary tract (LUT) tissues, neuronal fibers innervating the bladder and urethra, and epithelial and muscular layers of the bladder and urethral walls, where they are mainly involved in nociception and mechanosensory transduction. As such, they represent attractive targets for treating LUT disorders. Although information on the functional significance of many of the TRP proteins in the LUT remains very limited, compelling evidence has accumulated for a pivotal role of TRPV1, TRPV2, TRPV4, TRPM8, and TRPA1 in normal and pathological LUT function, mainly as sensors of stretch and chemical irritation. Further studies into these and other TRPs in the LUT will facilitate the development of improved therapeutic strategies to target these channels in LUT disorders.

The role of the transient receptor potential (TRP) superfamily of cation-selective channels in the management of the overactive bladder

• The pathophysiology of lower urinary tract symptoms (LUTS), detrusor overactivity (DO), and the overactive bladder (OAB) syndrome is multifactorial and remains poorly understood. • The transient receptor potential (TRP) channel superfamily has been shown to be involved in nociception and mechanosensory transduction in various organ systems, and studies of the LUT have indicated that several TRP channels, including TRPV1, TRPV2, TRPV4, TRPM8, and TRPA1, are expressed in the bladder, and may act as sensors of stretch and/or chemical irritation. • However, the roles of these individual channels for normal LUT function and in LUTS/DO/OAB, have not been established. • TRPV1 is the channel best investigated. It is widely distributed in LUT structures, but despite extensive information on morphology and function in animal models, the role of this channel in normal human bladder function is still controversial. Conversely, its role in the pathophysiology and treatment of particularly neurogenic DO is well established. • TRPV1 is co-expressed with TRPA1, and TRPA1 is known to be present on capsaicin-sensitive primary sensory neurones. Activation of this channel can induce DO in animal models. • TRPV4 is a Ca(2+)-permeable stretch-activated cation channel, involved in stretch-induced ATP release, and TRPV4-deficient mice exhibit abnormal frequencies of voiding and non-voiding contractions in cystometric experiments. • TRPM8 is a cool receptor expressed in the urothelium and suburothelial sensory fibres. It has been implicated in the bladder-cooling reflex and in idiopathic DO. • The occurrence of other members of the TRP superfamily in the LUT has been reported, but information on their effects on LUT functions is scarce. There seem to be several links between activation of different members of the TRP superfamily and LUTS/DO/OAB, and further exploration of the involvement of these channels in LUT function, normally and in dysfunction, may be rewarding.

Differential vulnerabilities of urethral afferents in diabetes and discovery of a novel urethra-to-urethra reflex

Urethral reflexes are important regulators of micturition, and impairment of urethral afferent neuronal function may disrupt coordinated bladder and urethral activity, thereby contributing to voiding dysfunction in lower urinary tract disorders. Chemical stimulation by intraurethral irritant solution perfusion was used to determine whether urethral afferent neuronal function is altered in diabetes mellitus (DM). Sprague-Dawley rats were studied 10 wk after streptozotocin injection to induce DM or vehicle alone. Escalating doses of capsaicin (0.1-30 microM) or acetic acid (0.01-1%; AA) were perfused intraurethrally while recording isovolumetric bladder activity, urethral perfusion pressure, and electromyography of the external urethral sphincter (EUS-EMG). Some rats were additionally treated with alpha-bungarotoxin, hexamethonium, or bilateral transection of the sensory branches of the pudendal nerves (PudSNx). Intraurethral capsaicin inhibited bladder contractions in six out of seven control rats but not in any of six DM rats. Low-frequency oscillations (LFOs) of intraurethral pressure were observed in five out of six control rats with capsaicin-induced bladder inhibition. In contrast, intraurethral AA inhibited bladder contractions and enhanced tonic EUS-EMG activity in six out of six control and five out of six DM rats. LFOs occurred in four out of six control and three of five DM rats with AA-induced bladder inhibition. Chemically induced bladder inhibition and LFOs were not prevented by alpha-bungarotoxin but were eliminated by PudSNx and hexamethonium. Finally, LFOs were followed by phasic EUS activity. These findings show that DM affects urethral afferent neurons differentially, compromising those expressing TRPV1 receptors. Urethral smooth muscle LFOs are neurogenically mediated and induce EUS activity, revealing the existence of a hitherto undescribed reflex pathway: a smooth-to-striated muscle urethra-to-urethra reflex.

TRP family proteins in the lower urinary tract: translating basic science into new clinical prospective

The lower urinary tract (LUT) is densely innervated by capsaicin-sensitive primary afferent neurons, a sub set of sensory nerves, in a number of species including humans. These fibers exhibit both a sensory (afferent) function, including the regulation of the micturition reflex and the perception of pain, and an 'efferent' function, involved in the detrusor smooth muscle contractility and plasma protein extravasation. The discovery of specific binding sites for capsaicin, the pungent ingredient of red chilli, initiated a rush that ended up with the cloning of the 'vanilloid receptor', which belongs to the TRP (transient receptor potential) family. Here we reviewed the knowledge about the presumable functions of TRP family proteins in the LUT as regulators of bladder reflex activity, pain perception and cell differentiation. This review will focus on experimental evidence and promising clinical applications of targeting these proteins for the treatment of detrusor overactivity and bladder pain syndrome. As TRP receptor ligands may promote cellular death, and inhibit the growth of normal and neoplastic cells, the translation of basic science evidence into new clinical prospective for bladder and prostate cancer will be shown.

The dual function of capsaicin-sensitive sensory nerves in the bladder and urethra

The sensory innervation of the urinary bladder and urethra plays a key role in a variety of reflexes involved in urine storage and voiding. Dysfunction of these systems is a possible cause of many disturbances related to urine continence but basic knowledge in this field has been hampered by the lack of tools for studying sensory nerves. The use of capsaicin, the pungent ingredient of red peppers, allowed us to investigate the anatomical and functional properties of a specific subset of sensory neurons in the lower urinary tract. These 'capsaicin-sensitive' neurons play a dual sensory and 'efferent' function, determined by transmitter release from their central and peripheral nerve endings. Tachykinins, including substance P, and other neuropeptides such as calcitonin gene-related peptide, mediate the functions of these sensory neurons. The 'sensory' function includes regulation of micturition threshold, activation of cardiovascular reflexes and perception of pain from the urinary bladder. The 'efferent' function includes local regulation of muscle cell activity, nerve excitability, blood flow and plasma protein extravasation. Recent data suggest that capsaicin-sensitive sensory nerves could be present in the human bladder.

On the origin of bladder sensing: Tr(i)ps in urology

The mammalian TRP family consists of 28 channels that can be subdivided into 6 different classes: TRPV (vanilloid), TRPC (canonical), TRPM (Melastatin), TRPP (Polycystin), TRPML (Mucolipin), and TRPA (Ankyrin). TRP channels are activated by a diversity of physical (voltage, heat, cold, mechanical stress) or chemical (pH, osmolality) stimuli and by binding of specific ligands, enabling them to act as multifunctional sensors at the cellular level. Currently, a lot of scientific research is devoted to these channels and their role in sensing mechanisms throughout the body. In urology, there's a growing conviction that disturbances in afferent (sensory) mechanisms are highly important in the pathogenesis of functional problems. Therefore, the TRP family forms an interesting new target to focus on. In this review we attempt to summarize the existing knowledge about TRP channels in the urogenital tract. So far, TRPV1, TRPV2, TRPV4, TRPM8, and TRPA1 have been described in different parts of the urogenital tract. Although only TRPV1 (the vanilloid receptor) has been extensively studied so far, more evidence is slowly accumulating about the role of other TRP channels in the (patho)physiology of the urogenital tract.

The challenge of overactive bladder therapy: alternative to antimuscarinic agents

Contemporary, the management of overactive bladder (OAB), a medical condition characterized by urgency, with or without urge urinary incontinence, frequency and nocturia, in absence of genitourinary pathologies or metabolic factors that could explain these symptoms, is complex, and a wide range of conservative treatments has been offered, including bladder training, biofeedback, behavioral changes, oral or intravesical anticholinergic agents, S3 sacral neuromodulation and peripheral electrical stimulation. Clinical efficacy of these treatments remains an open issue and several experimental and clinical studies were carried out in the last years improving the results of medical treatment. Here we review the pathophysiology of micturition reflex, the current therapies for OAB and the rationale for alternative treatments. Furthermore we critically address the potential use of medications targeting the central nervous system (CNS) and the primary sensory nerves of the bladder wall, we review the use of agonists of nociceptin/orphanin protein (NOP) receptor and finally we report the results obtained by intradetrusor injection of botulinum toxin.

TRPs in bladder diseases

This review attempts to provide an overview of the current knowledge of TRP proteins and their possible role in bladder function and disease. At present, there are 28 transient receptor potential (TRP) channels (subdivided into 7 categories or families) which are involved in a number of functions [G.A. Hicks, TRP channels as therapeutic targets: hot property, or time to cool down? Neurogastroenterology and Motility 18, (2006) 590-594., J.D. Levine, N. Alessandri-Haber, TRP channels: targets for the relief of pain, Biochimica et Biophysica Acta 1772, (2007) 989-1003.]. Of those belonging to the group 1 subfamily, a number of TRPV, TRPM and TRPA proteins associated with osmoregulation, thermal, chemical and mechanical signaling mechanisms have been shown to be expressed within the lower urinary tract. Though the biological role of many of these channels in urinary bladder function still remains elusive, TRPV1 is by far the best characterized and is thought to be involved in a number of bladder disorders [A. Szallasi, P.M. Blumberg, Vanilloid (Capsaicin) Receptors and Mechanisms, Pharmacological Reviews 51, (1999) 150-221., I. Nagy, P. Santha, G. Jansco, L. Urban, The role of the vanilloid (capsaicin) receptor (TRPV1) in physiology and pathology, European Journal of Pharmacology 500, (2004) 351-369.].

Intravesical resiniferatoxin for the treatment of women with idiopathic detrusor overactivity and urgency incontinence: A single dose, 4 weeks, double-blind, randomized, placebo controlled trial

AIMS

To assess the hypothesis that resiniferatoxin (RTX) can be useful in women with urgency incontinence and idiopathic detrusor overactivity (IDO), we conducted a prospective, double-blind, randomized, placebo-controlled, parallel trial comparing the effects of RTX and placebo.

MATERIALS AND METHODS

Fifty-eight patients were randomly assigned to receive a single intravesical dose of 100 ml of either RTX 50 nM or placebo. Safety and efficacy were evaluated over 4 weeks. The primary efficacy endpoints were voiding symptoms evaluated through the voiding diary. Secondary efficacy endpoint was urodynamic response. Quality of life was measured by the Kings' Health Questionnaire

RESULTS

Although improving trends were seen in both groups after the instillations, no statistically significant differences were found between the groups in any of the clinical or urodynamic parameters. RTX instillations were well tolerated with few and self-limited side-effects.

CONCLUSION

A single 50 nM intravesical dose of RTX was not better than placebo for the treatment of women with IDO and urgency incontinence.

Neuromodulatory therapies in female pelvic medicine and reconstructive surgery: biological agents

In recent years, important improvements in the management of patients with neurogenic or non-neurogenic detrusor overactivity and urge incontinence have been brought about by the introduction of vanilloids and botulinum toxins in urology. In this review we introduce the new therapeutic options, provides basic information, and summarize the results experienced so far.

TRPV1 (vanilloid receptor) in the urinary tract: expression, function and clinical applications

The transient receptor potential vanilloid subfamily 1 (TRPV1) is an ion channel activated by capsaicin, heat, protons and endogenous ligands such as anandamide. It is largely expressed in the urinary tract of mammals. Structures in which the receptor expression is firmly established include sensory fibers and urothelial cells, although the presence of TRPV1 in other cell types has been reported. As in other systems, pain perception was the first role attributed to TRPV1 in the urinary tract. However, it is now increasingly clear that TRPV1 also regulates the frequency of bladder reflex contractions, either through direct excitation of sensory fibers or through urothelial-sensory fiber cross talk involving the release of neuromediators from the epithelial cells. In addition, the recent identification of the receptor in urothelial and prostatic cancer cells raise the exciting hypothesis that TRPV1 is involved in cell differentiation. Desensitization of the receptor by capsaicin and resiniferatoxin has been investigated for therapeutic purposes. For the moment, lower urinary tract dysfunctions in which some benefit was obtained include painful bladder syndrome and overactive bladder of neurogenic and non-neurogenic origin. However, desensitization may become obsolete when non-toxic, potent TRPV1 antagonists become available.

The Physiological Function of the Urothelium – More than a Simple Barrier

The urothelium, the epithelium lining the surface of the urinary bladder, is a unique cell type with high plasticity and a variety of cellular functions. The urothelium represents the first line of bladder defense and an interface between pathogens and defense mechanisms. Functions of the urothelium include control of permeability, immune responses and cell-cell communication, which seems to play a pivotal role in responding to injuries and infections. The urothelium responds to stretch, during the filling phase of micturition reflex, by increasing the size of apical umbrella cells and by releasing mediators which activate the sensory fibers. For this reason the concept of 'neuron-like properties' was suggested. Finally, despite the fact that the urothelium is a frequent site of cancer formation, few experimental model systems are currently available or well characterized for studying urothelial cancer in the era of genomics and proteomics. The purpose of this review is to give emphasis to urothelial physiology and pathophysiology in different bladder disorders and to offer an up-to-date contribution to the field of urothelial research.

Heat/burning sensation induced by topical application of capsaicin on perineal cutaneous area: New approach in diagnosis and treatment of chronic prostatitis/chronic pelvic pain syndrome?

OBJECTIVES

To investigate the feasibility, safety, and efficacy of perineal cutaneous application of capsaicin as a test for the diagnosis, as well as a potential therapeutic tool, in patients with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS).

METHODS

We recruited 22 patients (mean age 34.5 years, range 19 to 56), who had been diagnosed with CP/CPPS according to the National Institutes of Health criteria, and 6 healthy control subjects. Both groups received a topical application of 5 mL capsaicin at a concentration of 10(-5) M to the perineal body skin. The patients were asked to mark on a visual analogue scale the intensity of any heat or burning sensation. All the patients had completed a National Institutes of Health Chronic Prostatitis Symptom Index before and 1 week after the test. The scores of the two groups were compared using the Mann-Whitney U test.

RESULTS

The patients with CP/CPPS reported a heat/burning sensation intensity that was statistically greater than that of the healthy controls (7.5 versus 4.3, P <0.001) and a shorter time to heat sensation onset and maximal intensity (1.5 versus 3.4 minutes, P <0.001, and 2.5 versus 7 minutes, P <0.001, respectively). Of the 22 patients, 16 reported an improvement of symptoms after 7 days and the mean National Institutes of Health Chronic Prostatitis Symptom Index score decreased from 27 to 16 (P <0.01).

CONCLUSIONS

We found a statistically significant difference in the pain visual analogue scale and interval between topical application and the onset of the heat/burning sensation between patients with CP/CPPS and healthy controls. The small sample size strongly suggests the need for additional larger and more controlled studies.

Contractile mechanisms coupled to TRPA1 receptor activation in rat urinary bladder

TRPA1 is a member of the transient receptor potential (TRP) channel family present in sensory neurons. Here we show that vanilloid receptor (TRPV1) stimulation with capsaicin and activation of TRPA1 with allyl isothiocyanate or cinnamaldehyde cause a graded contraction of the rat urinary bladder in vitro. Repeated applications of maximal concentrations of the agonists produce desensitization to their contractile effects. Moreover, contraction caused by TRPA1 agonists generates cross-desensitization with capsaicin. The TRP receptor antagonist ruthenium red (10-100 microM) inhibits capsaicin (0.03 microM), allyl isothiocyanate (100 microM) and cinnamaldehyde (300 microM)-induced contractions in the rat urinary bladder. The selective TRPV1 receptor antagonist SB 366791 (10 microM) blocks capsaicin-induced contraction, but partially reduces allyl isothiocyanate- or cinnamaldehyde-mediated contraction. However, allyl isothiocyanate and cinnamaldehyde (10-1000 microM) completely fail to interfere with the specific binding sites for the TRPV1 agonist [(3)H]-resiniferatoxin. Allyl isothiocyanate or cinnamaldehyde-mediated contractions of rat urinary bladder, which rely on external Ca(2+) influx, are significantly inhibited by tachykinin receptor antagonists as well as by tetrodotoxin (1 microM) or indomethacin (1 microM). Allyl isothiocyanate-induced contraction is not changed by atropine (1 microM) or suramin (300 microM). The exposure of urinary bladders to allyl isothiocyanate (100 microM) causes an increase in the prostaglandin E(2) and substance P levels. Taken together, these results indicate that TRPA1 agonists contract rat urinary bladder through sensory fibre stimulation, depending on extracellular Ca(2+) influx and release of tachykinins and cyclooxygenase metabolites, probably prostaglandin E(2). Thus, TRPA1 appears to exert an important role in urinary bladder function.

Sacral neuromodulation in lower urinary tract dysfunction

Vesico-urethral dysfunction is a major problem in daily medical practice due to its psychological disturbances, its social costs and its high impact on quality of life. Recently, sacral neuromodulation, namely the electrical stimulation of the sacral nerves, appears to have become an alternative for radical bladder surgery particularly in cases of idiopathic bladder overactivity. The mechanism of action is only partially understood but it seems to involve a modulation in the spinal cord due to stimulation of inhibitory interneurons. Temporary sacral nerve stimulation is the first step. It comprises the temporary application of neuromodulation as a diagnostic test to determine the best location for the implant and to control the integrity of the sacral root. If test stimulation is successful, a permanent device is implanted. This procedure is safe in experienced hands. So-called idiopathic bladder overactivity still the major indication for this technique. Patients not likely to benefit from the procedure were those with complete or almost complete spinal lesions, but incomplete spinal lesions seemed to be a potential indication. This technique is now also indicated in the case of idiopathic chronic retention and chronic pelvic pain syndrome. When selection is performed, more than three-quarters of the patients showed a clinically significant response with 50% or more reduction in the frequency of incontinent episodes, but the results vary according to the author's mode of evaluation. From the economic point of view, the initial investment in the device is amortized in the mid-term by savings related to lower urinary tract dysfunction. Finally, this technique requires an attentive follow-up and adjustments to the electric parameters so as to optimize the equilibrium between the neurological systems.

Recent developments in transient receptor potential vanilloid receptor 1 agonist-based therapies

Capsaicin and other naturally occurring pungent molecules have been used for centuries as topical analgesics and rubefactants to treat a variety of chronically painful conditions. Recently, instillations of high-concentration capsaicin and resiniferatoxin solutions have been found to be useful for the management of persistent bladder pain or overactive bladder. However, only within the last 7 years has it been appreciated that the selective action of these compounds on a subset of sensory nerve fibres is mediated by agonist activity at a ligand-gated ion channel called the transient receptor potential vanilloid receptor 1 (TRPV1). Accordingly, this discovery has fueled intensive research and drug development efforts, mainly in a search for novel analgesic or anti-inflammatory therapies. Two different, but non-mutually exclusive, strategies are being pursued: optimisation of TRPV1 agonist-based therapies, which can functionally inactivate nociceptive nerve fibres, and identification of receptor antagonists, which would prevent nociceptive fibres from being activated by ongoing inflammatory stimuli. Available information on TRPV1 agonists in development and their biological rationale will be summarised in this review.

Transient Receptor Potential Vanilloid Type 1 (TRPV1) Expression Changes from Normal Urothelium to Transitional Cell Carcinoma of Human Bladder

OBJECTIVE

To investigate possible changes in the expression of the transient receptor potential vanilloid type 1 (TRPV1) from normal urothelium to transitional cell carcinoma (TCC) of human bladder.

METHODS

Specimens from normal bladder (n=13, mean age 62 yrs), superficial TCC (n=16, mean age 62,4 yrs) and muscle invasive bladder cancer (n=12, mean age 67 yrs), were obtained by multiple cold cup and full-thickness biopsy during open surgery. All the specimens were processed for H&E staining, immunohistochemistry and Western Blot analysis.

RESULTS

In controls, the urothelium showed a labelling whose intensity was higher in the superficial cells than in the basal and club-shaped ones. In the superficial TCC, the urothelium showed a reduced labelling intensity. In the muscle invasive TCC, a very light labelling was occasionally detected in scattered superficial cells and no labelling was present in the basal cells and in those that had invaded the muscle. In controls, Western Blot analysis recognized two thick, intensely stained bands, with a molecular weight of approximately 100 and 95 kDa. In all superficial TCC there were two bands similar to control ones and in the muscle invasive two very thin, lightly stained bands. No band was detected in the patients staged as pT4.

CONCLUSION

These data demonstrated a progressive loss of TRPV1 expression in the urothelium as TCC stage increased and cell differentiation was lower. Future studies will establish the importance of this loss for TCC differentiation and progression.

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

The lower urinary tract constitutes a functional unit controlled by a complex interplay between the central and peripheral nervous systems and local regulatory factors. In the adult, micturition is controlled by a spinobulbospinal reflex, which is under suprapontine control. Several central nervous system transmitters can modulate voiding, as well as, potentially, drugs affecting voiding; for example, noradrenaline, GABA, or dopamine receptors and mechanisms may be therapeutically useful. Peripherally, lower urinary tract function is dependent on the concerted action of the smooth and striated muscles of the urinary bladder, urethra, and periurethral region. Various neurotransmitters, including acetylcholine, noradrenaline, adenosine triphosphate, nitric oxide, and neuropeptides, have been implicated in this neural regulation. Muscarinic receptors mediate normal bladder contraction as well as at least the main part of contraction in the overactive bladder. Disorders of micturition can roughly be classified as disturbances of storage or disturbances of emptying. Failure to store urine may lead to various forms of incontinence, the main forms of which are urge and stress incontinence. The etiology and pathophysiology of these disorders remain incompletely known, which is reflected in the fact that current drug treatment includes a relatively small number of more or less well-documented alternatives. Antimuscarinics are the main-stay of pharmacological treatment of the overactive bladder syndrome, which is characterized by urgency, frequency, and urge incontinence. Accepted drug treatments of stress incontinence are currently scarce, but new alternatives are emerging. New targets for control of micturition are being defined, but further research is needed to advance the pharmacological treatment of micturition disorders.