Integrative control of the lower urinary tract: preclinical perspective

Neural control of the lower urinary tract

This article summarizes anatomical, neurophysiological, pharmacological, and brain imaging studies in humans and animals that have provided insights into the neural circuitry and neurotransmitter mechanisms controlling the lower urinary tract. The functions of the lower urinary tract to store and periodically eliminate urine are regulated by a complex neural control system in the brain, spinal cord, and peripheral autonomic ganglia that coordinates the activity of smooth and striated muscles of the bladder and urethral outlet. The neural control of micturition is organized as a hierarchical system in which spinal storage mechanisms are in turn regulated by circuitry in the rostral brain stem that initiates reflex voiding. Input from the forebrain triggers voluntary voiding by modulating the brain stem circuitry. Many neural circuits controlling the lower urinary tract exhibit switch-like patterns of activity that turn on and off in an all-or-none manner. The major component of the micturition switching circuit is a spinobulbospinal parasympathetic reflex pathway that has essential connections in the periaqueductal gray and pontine micturition center. A computer model of this circuit that mimics the switching functions of the bladder and urethra at the onset of micturition is described. Micturition occurs involuntarily in infants and young children until the age of 3 to 5 years, after which it is regulated voluntarily. Diseases or injuries of the nervous system in adults can cause the re-emergence of involuntary micturition, leading to urinary incontinence. Neuroplasticity underlying these developmental and pathological changes in voiding function is discussed.

The urothelium: anatomy, review of the literature, perspectives for veterinary medicine

Over time, much knowledge has been accumulated about the active role of the urothelium, principally in rodents and human. Far from being a mere passive barrier, this specialized epithelium can alter the ion and protein composition of the urine, is able to sense and respond to mechanical stimuli such as pressure, and react to mechanical stimuli by epithelial cell communication with the nervous system. Most of the specialized functions of the urothelium are linked to a number of morpho-physiologic properties exhibited by the superficial umbrella cells, including specialized membrane lipids, asymmetric unit membrane particles and a plasmalemma with stiff plaques which function as a barrier to most substances found in urine, thus protecting the underlying tissues. Moreover, the entire mucosa lining the low urinary tract, composed of urothelium and sub-urothelium, forms a functional transduction unit, able to respond to eso- and endogenous physical and chemical stimuli in a manner assuring an adequate functional response. This review will summarize the available information on each area of inquiry from a morpho-functional point of view. Possible considerations pertaining to species of veterinary interest are reviewed as well. The review was prepared consulting the electronic databases PubMed and Cab Abstracts and retrieving all pertinent reports and the relative reference lists, in order to identify any potential additional studies that could be included. Full-length research articles and thematic reviews were considered. Information on the urothelium of some domestic animal species was also included.

Effects of lateral funiculus sparing, spinal lesion level, and gender on recovery of bladder voiding reflexes and hematuria in rats

Deficits in bladder function are complications following spinal cord injury (SCI), severely affecting quality of life. Normal voiding function requires coordinated contraction of bladder and urethral sphincter muscles dependent upon intact lumbosacral reflex arcs and integration of descending and ascending spinal pathways. We previously reported, in electrophysiological recordings, that segmental reflex circuit neurons in anesthetized male rats were modulated by a bilateral spino-bulbo-spinal pathway in the mid-thoracic lateral funiculus. In the present study, behavioral measures of bladder voiding reflexes and hematuria (hemorrhagic cystitis) were obtained to assess the correlation of plasticity-dependent recovery to the degree of lateral funiculus sparing and mid-thoracic lesion level. Adult rats received mid-thoracic-level lesions at one of the following severities: complete spinal transection; bilateral dorsal column lesion; unilateral hemisection; bilateral dorsal hemisection; a bilateral lesion of the lateral funiculi and dorsal columns; or a severe contusion. Voiding function and hematuria were evaluated by determining whether the bladder was areflexic (requiring manual expression, i.e., "crede maneuver"), reflexive (voiding initiated by perineal stroking), or "automatic" (spontaneous voiding without caretaker assistance). Rats with one or both lateral funiculi spared (i.e., bilateral dorsal column lesion or unilateral hemisection) recovered significantly faster than animals with bilateral lateral funiculus lesions, severe contusion, or complete transection. Bladder reflex recovery time was significantly slower the closer a transection lesion was to T10, suggesting that proximity to the segmental sensory and sympathetic innervation of the upper urinary tract (kidney, ureter) should be avoided in the choice of lesion level for SCI studies of micturition pathways. In addition, hematuria duration was significantly longer in males, compared to females, despite similar bladder reflex onset times. We conclude that the sparing of the mid-thoracic lateral funiculus on one side is required for early recovery of bladder reflex voiding function and resolution of hematuria.

Lower urinary tract function in dementia with Lewy bodies (DLB)

OBJECTIVES

Dementia with Lewy bodies (DLB) is the second most common degenerative cause of dementia, whereas lower urinary tract (LUT) function in DLB patients has not been fully delineated. We investigated LUT function in DLB by clinical-urodynamic observations.

METHODS

We examined 32 patients with DLB (23 men, 9 women; aged 59-86 [mean, 75.9] years; disease duration, 0.2-17 [3.3] years). All patients underwent an electromyography-cystometry, and 21 patients underwent the sphincter motor unit potential analysis.

RESULTS

Ninety-one percent of patients had LUT symptoms: nighttime frequency (>8 times), 84%, and urinary incontinence (>1 per week), 50%. Detrusor overactivity was revealed in 87.1%, whereas postvoid residual was minimal. Neurogenic changes were shown in 50%.

CONCLUSION

LUT dysfunction is a common feature in DLB, attributable not only to dementia and immobility, but also to central and peripheral types of somato-autonomic dysfunction.

IL22 regulates human urothelial cell sensory and innate functions through modulation of the acetylcholine response, immunoregulatory cytokines and antimicrobial peptides: assessment of an in vitro model

Human urinary disorders are generally studied in rodent models due to limitations of functional in vitro culture models of primary human urothelial cells (HUCs). Current HUC culture models are often derived from immortalized cancer cell lines, which likely have functional characteristics differ from healthy human urothelium. Here, we described a simple explant culture technique to generate HUCs and assessed their in vitro functions. Using transmission electron microscopy, we assessed morphology and heterogeneity of the generated HUCs and characterized their intercellular membrane structural proteins relative to ex vivo urothelium tissue. We demonstrated that our cultured HUCs are free of fibroblasts. They are also heterogeneous, containing cells characteristic of both immature basal cells and mature superficial urothelial cells. The cultured HUCs expressed muscarinic receptors (MR1 and MR2), carnitine acetyltransferase (CarAT), immunoregulatory cytokines IL7, IL15, and IL23, as well as the chemokine CCL20. HUCs also expressed epithelial cell-specific molecules essential for forming intercellular structures that maintain the functional capacity to form the physiological barrier of the human bladder urothelium. A subset of HUCs, identified by the high expression of CD44, expressed the Toll-like receptor 4 (TLR4) along with its co-receptor CD14. We demonstrated that HUCs express, at the mRNA level, both forms of the IL22 receptor, the membrane-associated (IL22RA1) and the secreted soluble (IL22RA2) forms; in turn, IL22 inhibited expression of MR1 and induced expression of CarAT and two antimicrobial peptides (S100A9 and lipocalin-2). While the cellular sources of IL22 have yet to be identified, the HUC cytokine and chemokine profiles support the concept that IL22-producing cells are present in the human bladder mucosa tissue and that IL22 plays a regulatory role in HUC functions. Thus, the described explant technique is clearly capable of generating functional HUCs suitable for the study of human urinary tract disorders, including interactions between urothelium and IL22-producing cells.

Pathophysiology and animal modeling of underactive bladder

While the symptomology of underactive bladder (UAB) may imply a primary dysfunction of the detrusor muscle, insights into pathophysiology indicate that both myogenic and neurogenic mechanisms need to be considered. Due to lack of proper animal models, the current understanding of the UAB pathophysiology is limited, and much of what is known about the clinical etiology of the condition has been derived from epidemiological data. We hereby review current state of the art in the understanding of the pathophysiology of and animal models used to study the UAB.

Detrusor Underactivity: The Current Concept of the Pathophysiology

Based on evidence from available literature, we review the pathophysiology of detrusor underactivity (DU). DU is likely to be multifactorial. Aging reduces detrusor activity, but other concomitant causes may aggravate this condition, resulting in decrease of detrusor contractility. Impaired detrusor contractility has been regarded as a major etiologic factor of DU. However, a more complex pathology has been proposed. As contributing factors to DU, we discuss disturbances of the sensory afferent side of the micturition reflex, the central nervous system (CNS) and the efferent side of the reflex, including nerves and the detrusor muscle. Particularly, dysfunction of afferent nerves in the bladder and urethra may play a crucial role in the pathogenesis of DU. In addition, recent studies suggest that chronic bladder ischemia and resultant oxidative stress cause detrusor overactivity progressing to DU and inability to empty the bladder.

Supraspinal Control of Urine Storage and Micturition in Men--An fMRI Study

Despite the crucial role of the brain in the control of the human lower urinary tract, little is known about the supraspinal mechanisms regulating micturition. To investigate the central regulatory mechanisms activated during micturition initiation and actual micturition, we used an alternating sequence of micturition imitation/imagination, micturition initiation, and actual micturition in 22 healthy males undergoing functional magnetic resonance imaging. Subjects able to micturate (voiders) showed the most prominent supraspinal activity during the final phase of micturition initiation whereas actual micturition was associated with significantly less such activity. Initiation of micturition in voiders induced significant activity in the brainstem (periaqueductal gray, pons), insula, thalamus, prefrontal cortex, parietal operculum and cingulate cortex with significant functional connectivity between the forebrain and parietal operculum. Subjects unable to micturate (nonvoiders) showed less robust activation during initiation of micturition, with activity in the forebrain and brainstem particularly lacking. Our findings suggest that micturition is controlled by a specific supraspinal network which is essential for the voluntary initiation of micturition. Once this network triggers the bulbospinal micturition reflex via brainstem centers, micturition continues automatically without further supraspinal input. Unsuccessful micturition is characterized by a failure to activate the periaqueductal gray and pons during initiation.

Urinary nerve growth factor in patients with detrusor overactivity

Background

Detrusor overactivity (DO) is one of the most frequent bladder dysfunctions in children up to the age of 18. Nowadays, the only way to confirm DO is by urodynamic investigation, which is an invasive procedure. Among the many mediators influencing bladder function, nerve growth factor (NGF) plays an important role. The present study was designed to measure urinary NGF (uNGF) levels in patients with DO diagnosed by urodynamic study in comparison with healthy controls.

Methods

The investigation was conducted on 44 children, divided into two groups (24 patients with DO, 20 healthy children). Uroflowmetry was performed in all enrolled to the study and cystometry only to patients. uNGF levels were estimated in both studied groups.

Results

The median uNGF level in patients with DO before treatment was higher compared with healthy controls. There were no differences between uNGF levels in patients after anticholinergic treatment and the controls. We found differences in uroflowmetry parameters between the reference group and the patients. We found correlations between uroflowmetry parameters and uNGF/cr. level.

Conclusions

The uNGF level could be used for detecting DO in children and adolescents.

Measuring uNGF level is a simple, noninvasive procedure and very useful for choosing therapy in patients with DO in various clinical conditions.

Does our limited knowledge of the mechanisms of neural stimulation limit its benefits for patients with overactive bladder? ICI-RS 2013

INTRODUCTION

Neural stimulation has become an established minimally invasive treatment for various lower urinary tract symptoms. The results both short- and long-term are encouraging, however, there is still a lack of knowledge of obvious risk factors, which may affect the outcome of treatment. Although neural stimulation has been embraced by healthcare professionals and patients, the exact mechanism by which neural stimulation works is still unclear.

DISCUSSION

A condense review of knowledge available on this topic is presented. Several research questions are raised. Outlines of research studies, both clinical and basic science, are suggested.

CONCLUSIONS

Further studies are necessary to understand mechanism of action of neural stimulation and its implications on treatment outcomes.

Cross-sensitization mechanisms between colon and bladder via transient receptor potential A1 stimulation in rats

INTRODUCTION AND HYPOTHESIS

The aim of this study was to analyze the mechanism underlying cross-sensitization between the colon and the bladder via activation of transient receptor potential A1 (TRPA1) channels.

METHODS

Using female Sprague-Dawley rats, polyethylene catheters were inserted into the colon between two ligations at the levels of 40 and 60 mm rostral to the anus and into the bladder. (1) We examined changes in colon and bladder activity after the application of allyl isothiocyanate (AI, 50 mM, 300 μl), a TRPA1 activator, into the colon or the bladder in an awake condition. Inhibitory effects of the pretreatment with HC-030031 (HC, 3 mg/kg), a TRPA1 inhibitor, on colon-to-bladder cross-sensitization induced by AI instilled in the colon were also investigated. (2) We examined Evans blue (EB) dye extravasation after TRPA1 stimulation in the colon or the bladder to evaluate vascular permeability due to tissue inflammation.

RESULTS

(1) Intercontraction intervals during continuous saline infusion into the bladder (0.04 ml/min) were significantly decreased after the intracolonic AI application, which significantly increased mean intracolonic pressure, indicative of colon-to-bladder cross-sensitization. The AI-induced colon-to-bladder cross-sensitization was completely prevented by the pretreatment with intravenous application of HC. On the other hand, mean intracolonic pressure was significantly decreased after the intravesical AI application, which significantly increased mean intravesical pressure. (2) EB dye extravasation was significantly increased in the AI-treated inflamed organs and also in the bladder following intracolonic AI treatment.

CONCLUSIONS

Colon-to-bladder cross-sensitization is mediated via TRPA1 stimulation in the colon, although TRPA1 expressed in the bladder does not seem to participate in bladder-to-colon cross-sensitization.

Response of the human detrusor to stretch is regulated by TREK-1, a two-pore-domain (K2P) mechano-gated potassium channel

The mechanisms of mechanosensitivity underlying the response of the human bladder to stretch are poorly understood. Animal data suggest that stretch-activated two-pore-domain (K2P) K(+) channels play a critical role in bladder relaxation during the filling phase. The objective of this study was to characterize the expression and function of stretch-activated K2P channels in the human bladder and to clarify their physiological role in bladder mechanosensitivity. Gene and protein analysis of the K2P channels TREK-1, TREK-2 and TRAAK in the human bladder revealed that TREK-1 is the predominantly expressed member of the mechano-gated subfamily of K2P channels. Immunohistochemical labelling of bladder wall identified higher levels of expression of TREK-1 in detrusor smooth muscle cells in comparison to bladder mucosa. Functional characterization and biophysical properties of the predominantly expressed member of the K2P family, the TREK-1 channel, were evaluated by in vitro organ bath studies and the patch-clamp technique. Electrophysiological recordings from single smooth muscle cells confirmed direct activation of TREK-1 channels by mechanical stretch and negative pressure applied to the cell membrane. Inhibition of TREK-1 channels in the human detrusor significantly delayed relaxation of the stretched bladder smooth muscle strips and triggered small-amplitude spontaneous contractions. Application of negative pressure to cell-attached patches (-20 mmHg) caused a 19-fold increase in the open probability (NPo) of human TREK-1 channels. l-Methionine (1 mm), a specific TREK-1 inhibitor, dramatically decreased the NPo of TREK-1 channels from 0.045 ± 0.003 to 0.008 ± 0.001 (n = 8, P ≤ 0.01). Subsequent addition of arachidonic acid (10 μm), a channel opener, increased the open probability of methionine-inhibited unitary currents up to 0.43 ± 0.05 at 0 mV (n = 9, P ≤ 0.05). The results of our study provide direct evidence that the response of the human detrusor to mechanical stretch is regulated by activation of mechano-gated TREK-1 channels. Impaired mechanosensation and mechanotransduction associated with the changes in stretch-activated K2P channels may underlie myogenic bladder dysfunction in humans.

Excitatory GABAA receptor in autonomic pelvic ganglion neurons innervating bladder

Major pelvic ganglia (MPG) are relay centers for autonomic reflexes such as micturition and penile erection. MPG innervate the urogenital system, including bladder. γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian central nervous system, and may also play an important role in some peripheral autonomic ganglia, including MPG. However, the electrophysiological properties and function of GABAA receptor in MPG neurons innervating bladder remain unknown. This study examined the electrophysiological properties and functional roles of GABAA receptors in bladder-innervating neurons identified by retrograde Dil tracing. Neurons innervating bladder showed previously established parasympathetic properties, including small membrane capacitance, lack of T-type Ca(2+) channel expression, and tyrosine-hydroxylase immunoreactivity. GABAA receptors were functionally expressed in bladder innervating neurons, but GABAC receptors were not. GABA elicited strong depolarization followed by increase of intracellular Ca(2+) in neurons innervating bladder, supporting the hypothesis GABA may play an important role in bladder function. These results provide useful information about the autonomic function of bladder in physiological and pathological conditions.

Nitrergic relaxations and phenylephrine contractions are not compromised in isolated urethra in a rat model of diabetes

In vivo experiments in a diabetic rat model revealed compromised nitrergic urethral relaxations and increased sensitivity to adrenergic agonists. This study evaluated contractile and relaxation properties of urethral smooth muscle after streptozotocin (STZ)-induced diabetes, in vitro, with the aim of determining whether in vivo deficiencies are related to smooth muscle dysfunction. Urethral tissue was collected from adult female Sprague-Dawley rats naive, STZ-treated, vehicle-treated and sucrose-fed at 9-12 week post treatment. Strips from proximal, mid, and distal urethra were placed in tissue baths and stimulated using electric field stimulation (EFS) and pharmacological agents. nNOS staining was evaluated using immunohistochemistry. Phenylephrine (PE, 10μM) contracted all urethral strips with the highest amplitude in mid urethra, in all treatment groups. Likewise, EFS-induced relaxation amplitudes were larger and were observed more frequently in mid urethra. Relaxations were inhibited by the NOS inhibitor, L-NAME (1-100μM). Sodium nitroprusside (0.01-1μM), an NO donor, reversed PE-induced contractions. No statistical differences were observed between treatment groups with respect to any parameters. Qualitative immunohistochemistry showed no differences in the urethral nNOS innervation patterns across the treatment groups. In summary, nitrergic relaxations and adrenergic-induced contractions in the isolated diabetic rat urethra display similar properties to controls, suggesting no dysfunction on the nitrergic or alpha1 adrenergic receptor function in the smooth muscle. This further implies that compromised urethral relaxation and increased adrenergic agonist sensitivity observed in vivo in this model may be due to the disruption of neural signaling between the urethra and the spinal cord, or within the CNS.

Continence and micturition: an anatomical basis

Urinary incontinence remains an important clinical problem worldwide, having a significant socio-economic, psychological, and medical burden. Maintaining urinary continence and coordinating micturition are complex processes relying on interaction between somatic and visceral elements, moderated by learned behavior. Urinary viscera and pelvic floor must interact with higher centers to ensure a functionally competent system. This article aims to describe the relevant anatomy and neuronal pathways involved in the maintenance of urinary continence and micturition. Review of relevant literature focusing on pelvic floor and urinary sphincters anatomy, and neuroanatomy of urinary continence and micturition. Data obtained from both live and cadaveric human studies are included. The stretch during bladder filling is believed to cause release of urothelial chemical mediators, which in turn activates afferent nerves and myofibroblasts in the muscosal and submucosal layers respectively, thereby relaying sensation of bladder fullness. The internal urethral sphincter is continuous with detrusor muscle, but its arrangement is variable. The external urethral sphincter blends with fibers of levator ani muscle. Executive decisions about micturition in humans rely on a complex mechanism involving communication between several cerebral centers and primitive sacral spinal reflexes. The pudendal nerve is most commonly damaged in females at the level of sacrospinous ligament. We describe the pelvic anatomy and relevant neuroanatomy involved in maintaining urinary continence and during micturition, subsequently highlighting the anatomical basis of urinary incontinence. Comprehensive anatomical understanding is vital for appropriate medical and surgical management of affected patients, and helps guide development of future therapies.

Purinergic signalling in the urinary tract in health and disease

Purinergic signalling is involved in a number of physiological and pathophysiological activities in the lower urinary tract. In the bladder of laboratory animals there is parasympathetic excitatory cotransmission with the purinergic and cholinergic components being approximately equal, acting via P2X1 and muscarinic receptors, respectively. Purinergic mechanosensory transduction occurs where ATP, released from urothelial cells during distension of bladder and ureter, acts on P2X3 and P2X2/3 receptors on suburothelial sensory nerves to initiate the voiding reflex, via low threshold fibres, and nociception, via high threshold fibres. In human bladder the purinergic component of parasympathetic cotransmission is less than 3 %, but in pathological conditions, such as interstitial cystitis, obstructed and neuropathic bladder, the purinergic component is increased to 40 %. Other pathological conditions of the bladder have been shown to involve purinoceptor-mediated activities, including multiple sclerosis, ischaemia, diabetes, cancer and bacterial infections. In the ureter, P2X7 receptors have been implicated in inflammation and fibrosis. Purinergic therapeutic strategies are being explored that hopefully will be developed and bring benefit and relief to many patients with urinary tract disorders.

[Neurology and the bladder: how to assess and manage neurogenic bladder dysfunction. With particular references to neural control of micturition]

Bladder dysfunctions are one of the most common features seen in the failure of the autonomic nervous system. Among those, overactive bladder (urinary urgency and frequency) worsens quality of life of the patients, and a large amount of post-voiding residual urine or urinary retention causes urinary tract infection, kidney dysfunction, and may bring renal failure. In the present paper we discussed neural control of micturition and how to assess it. Also, we proposed appropriate management of bladder dysfunction in elderly white matter lesions (a common cause of OAB) and diabetic neuropathy (a usual pathology underlying urinary retention). For OAB, anti-cholinergics are the mainstay, whereas for the pathological post-voiding residual urine or urinary retention, alpha-blockers, cholinergic agents and clean, intermittent self-catheterization are the choice. Treatment of bladder dysfunctions is the important target for maximizing patients' quality of life.

Functional role of Barrington's nucleus in the micturition reflex: relevance in the surgical treatment of Parkinson's disease

The pontine micturition center or Barrington's nucleus (BN) - besides regulating micturition - co-regulates the activity of other pelvic viscera such as the colon and genitals. At present, this issue is gaining particular importance due to: (i) recent findings of α-synuclein in BN, (ii) known urinary dysfunction in parkinsonian patients (part of the so-called non-motor symptoms), other patients with dementia and as in very old individuals; and (iii) its proximity to the pedunculopontine nucleus, a surgical target in deep brain stimulation for Parkinson's disease (PD). The structural and functional organization of the micturition reflex comprises a coordinating action of somatic motor activity with both divisions of the autonomic nervous system, modulated by trunk encephalic and cortical centers that involve the BN as locus coeruleus and periaqueductal gray matter, among other trunk encephalic structures. The involvement of dopaminergic activity (physiologic inhibition of the micturition reflex mediated by dopaminergic D1 activity) that diminishes in Parkinsonism and leads to overactivity of the micturition reflex is also well known. In this review, the integrating role of the BN in the context of vesical and gastrointestinal behavior is revisited, and the principal morpho-functional findings that associate dysfunction with the urinary disorders that appear during the pre-motor stages of PD are summarized.

A small-animal pharmacokinetic/pharmacodynamic PET study of central serotonin 1A receptor occupancy by a potential therapeutic agent for overactive bladder

Serotonin 1A (5-HT1A) receptors have been mechanistically implicated in micturition control, and there has been a need for an appropriate biomarker surrogating the potency of a provisional drug acting on this receptor system for developing a new therapeutic approach to overactive bladder (OAB). Here, we analyzed the occupancy of 5-HT1A receptors in living Sprague-Dawley rat brains by a novel candidate drug for OAB, E2110, using positron emission tomography (PET) imaging, and assessed the utility of a receptor occupancy (RO) assay to establish a pharmacodynamic index translatable between animals and humans. The plasma concentrations inducing 50% RO (EC50) estimated by both direct and effect compartment models were in good agreement. Dose-dependent therapeutic effects of E2110 on dysregulated micturition in different rat models of pollakiuria were also consistently explained by achievement of 5-HT1A RO by E2110 in a certain range (≥ 60%). Plasma drug concentrations inducing this RO range and EC50 would accordingly be objective indices in comparing pharmacokinetics-RO relationships between rats and humans. These findings support the utility of PET RO and plasma pharmacokinetic assays with the aid of adequate mathematical models in determining the in vivo characteristics of a drug acting on 5-HT1A receptors and thereby counteracting OAB.

Stability of the acetic acid-induced bladder irritation model in alpha chloralose-anesthetized female cats

Time- and vehicle-related variability of bladder and urethral rhabdosphincter (URS) activity as well as cardiorespiratory and blood chemistry values were examined in the acetic acid-induced bladder irritation model in α-chloralose-anesthetized female cats. Additionally, bladder and urethra were evaluated histologically using Mason trichrome and toluidine blue staining. Urodynamic, cardiovascular and respiratory parameters were collected during intravesical saline infusion followed by acetic acid (0.5%) to irritate the bladder. One hour after starting acetic acid infusion, a protocol consisting of a cystometrogram, continuous infusion-induced rhythmic voiding contractions, and a 5 min "quiet period" (bladder emptied without infusion) was precisely repeated every 30 minutes. Administration of vehicle (saline i.v.) occurred 15 minutes after starting each of the first 7 cystometrograms and duloxetine (1mg/kg i.v.) after the 8(th). Acetic acid infusion into the bladder increased URS-EMG activity, bladder contraction frequency, and decreased contraction amplitude and capacity, compared to saline. Bladder activity and URS activity stabilized within 1 and 2 hours, respectively. Duloxetine administration significantly decreased bladder contraction frequency and increased URS-EMG activity to levels similar to previous reports. Cardiorespiratory parameters and blood gas levels remained consistent throughout the experiment. The epithelium of the bladder and urethra were greatly damaged and edema and infiltration of neutrophils in the lamina propria of urethra were observed. These data provide an ample evaluation of the health of the animals, stability of voiding function and appropriateness of the model for testing drugs designed to evaluate lower urinary tract as well as cardiovascular and respiratory systems function.

Beneficial effects of Gosha-jinki-gan and green tea extract in rats with chemical cystitis

The aim of this study was to characterize pharmacological effects of gosha-jinki-gan (GJG) and green tea extract (GTE), on urodynamic parameters, bladder receptors, and urinary cytokines in rats with cyclophosphamide (CYP)-induced cystitis. Urodynamic parameters in CYP-treated rats were measured using the cystometric method. Muscarinic and purinergic receptors in rat tissues were measured by radioreceptor assays. Urinary cytokine levels were measured with ELISA kits. GJG and GTE were orally administered to rats once a day for 7 days. The GJG treatment significantly ameliorated changes in urodynamic parameters in CYP-treated rats. Similar treatment with GTE slightly attenuated changes in urodynamic parameters. The maximal number of binding sites for [³H]NMS and [³H]αβ-MeATP in the bladder was significantly lower in CYP-treated rats than in sham rats. Such a reduction in receptor density was significantly attenuated by the GJG treatment. GTE treatment also significantly attenuated the down-regulation of muscarinic receptors, but not P2X receptors in bladders of rats with CYP-induced cystitis. The elevation in urinary cytokine levels in CYP-treated rats was effectively attenuated by GJG treatment. The elevation in cytokine levels in CYP-treated rats was alleviated by GTE treatment. In conclusion, GJG may be a pharmacologically useful plant extract for cystitis.

Effective management of lower urinary tract dysfunction in idiopathic Parkinson's disease

Parkinson's disease, also known as paralysis agitans, is a progressive degenerative disorder of the central nervous system, with onset usually between the ages of 50 and 65 years, and is associated with loss of dopaminergic neurons in the subsantia nigra and the presence of Lewy bodies. It is characterized by the triad of resting tremor, muscular rigidity and bradykinesia. Often-accompanying abnormalities include disorders of equilibrium, posture and autonomic function, including micturition. Symptoms from the lower urinary tract add a significant comorbidity factor in these patients. The incidence and prevalence of lower urinary tract dysfunction rise with increasing progression of the underlying neurological disease. They present a troublesome and difficult to treat health issue with a profound impact on the patient's quality of life. Storage symptoms seem to predominate. In the long term, renal function might be compromised, mainly as a result of elevated intravesical pressure. Various conservative, minimally-invasive and surgical treatment options are available to prevent harmful sequelae, and to improve the quality of life of these patients. We present an overview of current and prospective treatment strategies.

Synaptic connections between endomorphin 2-immunoreactive terminals and μ-opioid receptor-expressing neurons in the sacral parasympathetic nucleus of the rat

The urinary bladder is innervated by parasympathetic preganglionic neurons (PPNs) that express μ-opioid receptors (MOR) in the sacral parasympathetic nucleus (SPN) at lumbosacral segments L6-S1. The SPN also contains endomorphin 2 (EM2)-immunoreactive (IR) fibers and terminals. EM2 is the endogenous ligand of MOR. In the present study, retrograde tract-tracing with cholera toxin subunit b (CTb) or wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) via the pelvic nerve combined with immunohistochemical staining for EM2 and MOR to identify PPNs within the SPN as well as synaptic connections between the EM2-IR terminals and MOR-expressing PPNs in the SPN of the rat. After CTb was injected into the pelvic nerve, CTb retrogradely labeled neurons were almost exclusively located in the lateral part of the intermediolateral gray matter at L6-S1 of the lumbosacral spinal cord. All of the them also expressed MOR. EM2-IR terminals formed symmetric synapses with MOR-IR, WGA-HRP-labeled and WGA-HRP/MOR double-labeled neuronal cell bodies and dendrites within the SPN. These results provided morphological evidence that EM2-containing axon terminals formed symmetric synapses with MOR-expressing PPNs in the SPN. The present results also show that EM2 and MOR might be involved in both the homeostatic control and information transmission of micturition.

Bladder health across the life course

Influences on bladder health begin during infancy and continue throughout the lifespan. Bladder anatomy and physiology change as individuals age, and the risk and propensity for bladder conditions, including lower urinary tract symptoms, throughout life are related to factors specific to age, sex, and life events. Bladder habits and dysfunctions at one stage of life may affect bladder health in subsequent stages. However, bladder problems are neither a normal part of aging nor inevitable at any stage of life. Many of the factors that negatively impact bladder health at all ages may be modifiable, and healthy bladder habits may prevent or reverse bladder dysfunctions that can occur naturally or in response to life events. There are opportunities to further define and promote healthy bladder habits through focused research and heightened public awareness of the importance of bladder health, which may lead to improvements in overall health and quality of life. It is our hope that this paper will inform and encourage public health initiatives and research programs aimed at this goal.

Mathematical modelling of the lower urinary tract

The lower urinary tract is one of the most complex biological systems of the human body as it involved hydrodynamic properties of urine and muscle. Moreover, its complexity is increased to be managed by voluntary and involuntary neural systems. In this paper, a mathematical model of the lower urinary tract it is proposed as a preliminary study to better understand its functioning. Furthermore, another goal of that mathematical model proposal is to provide a basis for developing artificial control systems. Lower urinary tract is comprised of two interacting systems: the mechanical system and the neural regulator. The latter has the function of controlling the mechanical system to perform the voiding process. The results of the tests reproduce experimental data with high degree of accuracy. Also, these results indicate that simulations not only with healthy patients but also of patients with dysfunctions with neurological etiology present urodynamic curves very similar to those obtained in clinical studies.

Organization of the neural switching circuitry underlying reflex micturition

The functions of the lower urinary tract to store and periodically eliminate urine are regulated by a complex neural control system in the brain and spinal cord that coordinates the activity of the bladder and urethral outlet. Experimental studies in animals indicate that urine storage is modulated by reflex mechanisms in the spinal cord, whereas voiding is mediated by a spinobulbospinal pathway passing through a coordination centre in the rostral brain stem. Many of the neural circuits controlling micturition exhibit switch-like patterns of activity that turn on and off in an all-or-none manner. This study summarizes the anatomy and physiology of the spinal and supraspinal micturition switching circuitry and describes a computer model of these circuits that mimics the switching functions of the bladder and urethra at the onset of micturition.

Spinal cord FAAH in normal micturition control and bladder overactivity in awake rats

PURPOSE

We assessed whether spinal inhibition of the cannabinoid degrading enzyme FAAH would have urodynamic effects in normal rats and rats with bladder overactivity induced by partial urethral obstruction or prostaglandin E2. We also determined the expression of FAAH, and the cannabinoid receptors CB1 and CB2 in the sacral spinal cord.

MATERIALS AND METHODS

We used 44 rats for functional (cystometry) and Western blot experiments. The FAAH inhibitor oleoyl ethyl amide (3 to 300 nmol) was administered intrathecally (subarachnoidally) or intravenously. The expression of FAAH and CB1/CB2 receptors was determined by Western blot.

RESULTS

Oleoyl ethyl amide given intrathecally affected micturition in normal rats and rats with bladder overactivity but effects were more pronounced in the latter. In normal rats oleoyl ethyl amide only decreased micturition frequency, while it decreased frequency and bladder pressures in rats with bladder overactivity. Intravenous oleoyl ethyl amide (3 to 300 nmol) had no urodynamic effect. FAAH and CB1/CB2 receptors were expressed in the rat sacral spinal cord. The expression of CB1/CB2 receptors but not FAAH was higher in obstructed than in normal rats.

CONCLUSIONS

FAAH inhibition in the sacral spinal cord by oleoyl ethyl amide resulted in urodynamic effects in normal rats and rats with bladder overactivity. The spinal endocannabinoid system may be involved in normal micturition control and it appears altered when there is bladder overactivity.

Pathophysiology of urinary incontinence in murine models

Urethral closure mechanisms under stress conditions consist of passive urethral closure involving connective tissues, fascia and/or ligaments in the pelvis and active urethral closure mediated by hypogastric, pelvic and pudendal nerves. Furthermore, we have previously reported that the active urethral closure mechanism might be divided into two categories: (i) the central nervous control passing onto Onuf's nucleus under sneezing or coughing; and (ii) the bladder-to-urethral spinal reflex under Valsalva-like stress conditions, such as laughing, exercise or lifting heavy objects. There are over 200 million people worldwide with urinary incontinence, a condition that is associated with a significant social impact and reduced quality of life. Therefore, basic research for urinary continence mechanisms in response to different stress conditions can play an essential role in developing treatments for stress urinary incontinence. It has been clinically shown that the etiology of stress urinary incontinence is divided into urethral hypermobility and intrinsic sphincter deficiency, which could respectively correspond to passive and active urethral closure dysfunction. In this review, we summarize the representative stress urinary incontinence animal models and the methods to measure leak point pressures under stress conditions, and then highlight stress-induced urinary continence mechanisms mediated by active urethral closure mechanisms, as well as future pharmacological treatments of stress urinary incontinence. In addition, we introduce our previous reports including sex differences in urethral closure mechanisms under stress conditions and urethral compensatory mechanisms to maintain urinary continence after pudendal nerve injury in female rats.

Nitric oxide modulates bladder afferent nerve activity in the in vitro urinary bladder-pelvic nerve preparation from rats with cyclophosphamide induced cystitis

Effects of a nitric oxide (NO) donor (SNAP), NO substrate (l-arginine), and NO synthase inhibitor (l-NAME) on bladder afferent nerve (BAN) activity were studied in an in vitro bladder-pelvic nerve preparation from untreated or cyclophosphamide (CYP) treated rats. Distension of the bladder induced phasic bladder contractions (PBC) that were accompanied by multiunit afferent firing. Intravesical administration of SNAP (2mM) which did not change the amplitude of PBC significantly decreased peak afferent firing from 79 ± 15 spikes/s to 44 ± 8 spikes/s in CYP pretreated but not untreated preparations. In CYP treated preparations SNAP also decreased by 33-55% BAN firing induced by isotonic distension of the bladder at 10-40 cmH(2)O pressures. Electrical stimulation on the surface of the bladder elicited action potentials (AP) in BAN. SNAP significantly increased the voltage threshold by 75% (p<0.05) and decreased by 45% (p<0.05) the area of the AP evoked at submaximal stimulus intensity. Bath application of SNAP (2mM) or l-arginine (50mM) elicited similar inhibitory effects on the distension evoked BAN firing. The effects of l-arginine were blocked by bath application of l-NAME (20mM). l-NAME alone did not alter BAN firing. In preparations from normal rats SNAP or l-arginine did not alter BAN activity. These results suggest that exogenous as well as endogenously generated NO depresses the excitability of sensitized but not normal BAN and that NO may have an antinociceptive function and modulate bladder hyperactivity induced by pathological conditions.

Selective inhibition of phosphodiesterase 1 relaxes urinary bladder smooth muscle: role for ryanodine receptor-mediated BK channel activation

The large conductance voltage- and Ca(2+)-activated K(+) (BK) channel is a major regulator of detrusor smooth muscle (DSM) excitability and contractility. Recently, we showed that nonselective phosphodiesterase (PDE) inhibition reduces guinea pig DSM excitability and contractility by increasing BK channel activity. Here, we investigated how DSM excitability and contractility changes upon selective inhibition of PDE type 1 (PDE1) and the underlying cellular mechanism involving ryanodine receptors (RyRs) and BK channels. PDE1 inhibition with 8-methoxymethyl-3-isobutyl-1-methylxanthine (8MM-IBMX; 10 μM) increased the cAMP levels in guinea pig DSM cells. Patch-clamp experiments on freshly isolated DSM cells showed that 8MM-IBMX increased transient BK currents and the spontaneous transient hyperpolarization (STH) frequency by ∼2.5- and ∼1.8-fold, respectively. 8MM-IBMX hyperpolarized guinea pig and human DSM cell membrane potential and significantly decreased the intracellular Ca(2+) levels in guinea pig DSM cells. Blocking BK channels with 1 μM paxilline or inhibiting RyRs with 30 μM ryanodine abolished the STHs and the 8MM-IBMX inhibitory effects on the DSM cell membrane potential. Isometric DSM tension recordings showed that 8MM-IBMX significantly reduced the spontaneous phasic contraction amplitude, muscle force integral, duration, frequency, and tone of DSM isolated strips. The electrical field stimulation-induced DSM contraction amplitude, muscle force integral, and duration were also attenuated by 10 μM 8MM-IBMX. Blocking BK channels with paxilline abolished the 8MM-IBMX effects on DSM contractions. Our data provide evidence that PDE1 inhibition relaxes DSM by raising cellular cAMP levels and subsequently stimulates RyRs, which leads to BK channel activation, membrane potential hyperpolarization, and decrease in intracellular Ca(2+) levels.

Management of lower urinary tract dysfunction in patients with neurological disorders

The proper performance of the lower urinary tract is dependent on an intact neural innervation of the individual structures involved. Therefore, any congenital neurological anomalies, diseases, or lesions of the central, peripheral, or autonomic nervous systems can result in lower urinary tract symptoms. Lower urinary tract dysfunction (LUTD) secondary to neurological disorders can significantly reduce quality of life (QoL) and may also give rise to serious complications and psychological and social sequelae. The goals of management of LUTD in patients with neurological disorders are to prevent serious complications and to improve the patient's QoL. Understanding the physiology and pathophysiology of micturition is critical to selecting appropriate treatment options. This article provides an overview of the clinical characteristics, diagnosis, and management of LUTD in patients with certain central and peripheral neuropathies and common lesions.

Do Sacral/Peripheral Lesions Contribute to Detrusor-Sphincter Dyssynergia?

OBJECTIVES

While detrusor-sphincter dyssynergia (DSD) occurs in conjunction with lesions between the brainstem and the sacral cord, it is not well known whether sacral/peripheral lesions contribute to DSD. We studied the relationship between DSD and sacral/peripheral lesions.

METHODS

One hundred and forty-four patients with diverse neurologic etiologies underwent urodynamic study and analysis of motor unit potentials in the external sphincter muscles, 117 of whom were able to void during a urodynamic test. Sacral/peripheral lesion (SPL) is defined as neurogenic change in motor unit potentials. Detrusor overactivity (DO) is defined as involuntary detrusor contractions during the filling phase, which commonly occurs in lesions above the sacral cord. We considered DO as a putative indicator of supra-sacral lesion.

RESULTS

DSD was found in 44 (30.6%), SPL in 71 (49.3%), and DO in 83 (57.6%) of 144 patients, respectively. The incidence of DSD was the same in the SPL positive group (31%) and the SPL negative group (30.1%). By contrast, within the subgroup of patients without DO, the incidence of DSD was significantly more common in the SPL positive group (41.4%) than in the SPL negative group (25.0%) (P < 0.05). In 53 of the SPL positive group who were able to void, postvoid residual >100 mL was more common in patients with DSD (not statistically significant).

CONCLUSION

The results of the present study suggest that not only suprasacral pathology, but also sacral/peripheral lesions can produce DSD. In light of the previous reports, DSD might also result from partial lesions in peripheral branches of the sphincter circuit.

The impact of gestational diabetes mellitus on postpartum urinary incontinence: a longitudinal cohort study on singleton pregnancies

OBJECTIVE

To determine whether gestational diabetes mellitus (GDM) is an independent risk factor for postpartum urinary incontinence in singleton pregnancies.

DESIGN

A longitudinal cohort study.

SETTING

A single tertiary-care hospital in Taiwan.

POPULATION

Pregnant women with term deliveries between 2002 and 2007 (n = 6653) were consecutively recruited.

METHODS

Logistic regression models were fitted based on generalised estimating equation methods to derive odds ratios for occurrences of type-specific urinary incontinence in the third trimester and at four time-points over 2 years during the postpartum period.

MAIN OUTCOME MEASURES

Evaluation of whether GDM is an independent risk factor for postpartum urinary incontinence.

RESULTS

The full model analysis revealed that GDM was an independent risk factor for all type-specific urinary incontinence (odds ratio [95% confidence interval]: 1.97 [1.56-2.51], 3.11 [2.18-4.43] and 2.73 [1.70-4.40] for stress, urge and mixed incontinence, respectively]. Compared with women without GDM, women with GDM tended to exhibit more severe symptoms of stress incontinence for up to 2 years postpartum, whereas for urge or mixed incontinence, more severe symptoms were found only for 6 months postpartum. Evaluation of quality of life using the Incontinence Impact Questionnaire 7 suggested that women with GDM requiring insulin treatment had a higher likelihood of functional impairment than women with GDM requiring conservative treatment only or women without GDM (P < 0.05, by the chi-square test for trend).

CONCLUSIONS

GDM was found to be an independent risk factor for postpartum urinary incontinence and had a significant impact on quality of life. Women with GDM should be provided with timely consultation and support once urinary incontinence occurs.

Overexpression of corticotropin-releasing factor in Barrington's nucleus neurons by adeno-associated viral transduction: effects on bladder function and behavior

The stress-related neuropeptide, corticotropin-releasing factor (CRF), is prominent in neurons of the pontine micturition center, Barrington's nucleus. These neurons co-innervate spinal preganglionic neurons that control the bladder, and locus coeruleus (LC) neurons that provide norepinephrine innervation throughout the brain. Adeno-associated viral (AAV) vector-mediated transfer of CRF cDNA was used to increase CRF expression in Barrington's nucleus neurons and investigate the impact of a gain of function in Barrington's nucleus spinal and LC projections. AAV transfer of the reverse CRF cDNA sequence served as the control. Bladder urodynamics and behavior were assessed 4 weeks after vector injection into Barrington's nucleus. Rats with bilateral injections of AAV-CRF cDNA into Barrington's nucleus had immunohistochemical evidence of CRF overexpression in neurons and transport to the spinal cord and LC. The bladder : body weight ratio was greater and micturition pressure was less in these rats compared with controls, consistent with an inhibitory influence on bladder function. Other indices of urodynamic function were not altered. CRF innervation of the LC was increased in rats with bilateral Barrington's nucleus injections of AAV-CRF cDNA, and this was associated with increased burying behavior, an endpoint of LC activation by CRF. The results provide immunohistochemical evidence for viral vector-induced CRF overexpression in Barrington's nucleus neurons and underscore the ability of AAV vector-mediated transfer to increase CRF function in selective circuits. The findings support an inhibitory influence of CRF in Barrington's nucleus regulation of the bladder and an excitatory influence on the brain norepinephrine system that translates to behavioral activation.

Dorsal root ganglion neurons innervating pelvic organs in the mouse express tyrosine hydroxylase

Previous studies in rat and mouse documented that a subpopulation of dorsal root ganglion (DRG) neurons innervating non-visceral tissues express tyrosine hydroxylase (TH). Here we studied whether or not mouse DRG neurons retrogradely traced with Fast Blue (FB) from colorectum or urinary bladder also express immunohistochemically detectable TH. The lumbar sympathetic chain (LSC) and major pelvic ganglion (MPG) were included in the analysis. Previously characterized antibodies against TH, norepinephrine transporter type 1 (NET-1) and calcitonin gene-related peptide (CGRP) were used. On average, ∼14% of colorectal and ∼17% of urinary bladder DRG neurons expressed TH and spanned virtually all neuronal sizes, although more often in the medium-sized to small ranges. Also, they were more abundant in lumbosacral than thoracolumbar DRGs, and often coexpressed CGRP. We also detected several TH-immunoreactive (IR) colorectal and urinary bladder neurons in the LSC and the MPG, more frequently in the former. No NET-1-IR neurons were detected in DRGs, whereas the majority of FB-labeled, TH-IR neurons in the LSC and MPG coexpressed this marker (as did most other TH-IR neurons not labeled from the target organs). TH-IR nerve fibers were detected in all layers of the colorectum and the urinary bladder, with some also reaching the basal mucosal cells. Most TH-IR fibers in these organs lacked CGRP. Taken together, we show: (1) that a previously undescribed population of colorectal and urinary bladder DRG neurons expresses TH, often CGRP but not NET-1, suggesting the absence of a noradrenergic phenotype; and (2) that TH-IR axons/terminals in the colon or urinary bladder, naturally expected to derive from autonomic sources, could also originate from sensory neurons.

Importance of relieving the most bothersome symptom for improving quality of life in male patients with lower urinary tract symptoms

OBJECTIVE

To highlight the importance of relieving the most bothersome symptom for improving quality of life (QoL) in male patients with lower urinary tract symptoms.

METHODS

From January 2010 to March 2011, 242 men with lower urinary tract symptoms visited our clinic, and 194 finished this study. At first visit, the most bothersome symptom was selected as the "core symptom." The sum of other symptoms except the core symptom was defined as "peripheral symptoms." All patients underwent empirical medical treatment for male lower urinary tract symptoms during an 8- to 12-week period, thereafter, recorded a follow-up International Prostate Symptom Score (I-PSS) questionnaire. We multivariately analyzed the patients' data after medical treatment to assess the influence of relieving their core symptom on the improvement of QoL.

RESULTS

The patients' mean age was 64.7 years and the mean total I-PSS was 19.7 points. Nocturia was the most common core symptom (29.9%), followed by weak stream (16.5%). Multiple logistic regression revealed that relieving the core symptom (odds ratio [OR] = 39.163, 95% confidence interval [CI] = 13.536-113.309) was significantly associated with QoL improvement. Improvement of peripheral symptoms (OR = 4.849, 95% CI = 1.629-14.433) and the inclusion of the moderate symptom group at first visit (OR = 2.622, 95% CI = 1.009-6.811) were also significant factors in predicting QoL improvement.

CONCLUSION

In treating benign prostatic hyperplasia or lower urinary tract symptoms, we should focus more on relieving the individual patient's most bothersome symptom to help improve patient QoL.