ROLE OF OVARIAN HORMONES IN THE PATHOGENESIS OF IMPAIRED DETRUSOR CONTRACTILITY: EVIDENCE IN OVARIECTOMIZED RODENTS

Prevalence and urodynamic characteristics of detrusor overactivity with impaired contractility in the community-dwelling elderly with non-neurogenic lower urinary tract symptoms: Is it from a single or two independent bladder dysfunctions?

Purpose

To identify the prevalence of detrusor overactivity with impaired contractility (DOIC) in the community-dwelling elderly and explore whether it is from a single or two independent bladder dysfunctions.

Materials and Methods

Based on a 10-year urodynamic database of the SEOUL Study Group, elderly patients who met inclusion criteria were selected. Bladder sensation, capacity, and compliance were designated as evaluation elements for storage function, and free maximal flow rate (Q_max) and post void residual volume, detrusor pressure at maximal flow (P_detQmax), and bladder voiding efficiency for voiding function.

Results

The prevalence rate of DOIC was 18.8% and 5.5% among 2,571 men and 688 women, respectively, and increased significantly with age. In men, patients with DOIC showed no differences in storage parameters and significantly lower free Q_max and P_detQmax among voiding parameters, compared to those with detrusor overactivity (DO) only. Compared to men with detrusor underactivity (DU) only, those with DOIC had worse parameters in the majority of storage and voiding functions. In women, most of the storage and voiding functions were worse in patients with DOIC than in those with DO only. On the other hand, women with DU showed lower P_detQmax and worse voiding functions than those with DOIC, although some parameters did not reach statistical significance.

Conclusions

It seems that DOIC is developed from a coincidental combination of two independent DO and DU in men. In contrast, DOIC is likely to be an intermediate step during the process of progression from DO to DU in women.

Administration of leuprolide acetate, a GnRH agonist, improves urodynamic parameters in ovariectomized rats

AIM

To evaluate the effects of a treatment with leuprolide acetate (LA) on bladder overactivity as well as the expression of gonadotropin releasing hormone receptor (GnRH-R), and neurofilaments NF68 and NF200 in female rats with overactive bladder induced by castration.

METHODS

Changes in the urodynamic parameters were determined in SHAM, ovariectomized (OVX) and ovariectomized rats treated with LA (OVX-LA). A semi-quantitative analysis for the expression pattern of GnRH-R and neurofilaments NF68 and NF200 were determined.

RESULTS

Forty-three days after ovariectomy, rats from the OVX group have significant lower values for intercontractile interval (ICI) and compliance (C); as well as higher values for basal bladder pressure (BP) and frequency of non-voiding contractions (NVC). The systemic application of LA increased voiding volume (Vv) and pressure threshold (ThP) in the OVX-LA animals. The application of LA reduced the high frequency of NVC in the OVX rats. No significant differences were found for Vv and NVCs between the OVX-LA vs SHAM groups. At the mid part of the bladder, the presence of GnRH-R was evidenced in the urothelium of the SHAM group. The OVX animals showed different pattern of immunolabeling for GnRH-R as well as for neurofilaments NF200 and NF68, whereas in the OVX-LA group the immunofluorescence pattern was similar to the one seen in SHAM bladders (P < 0.05 for OVX vs OVX + LA).

CONCLUSIONS

the results suggest that systemic application of LA can improve bladder dysfunction in castrated rats, and perhaps considered as a treatment for overactive bladder conditions secondary to menopause.

New therapeutic directions to treat underactive bladder

Underactive bladder (UAB) is a term used to describe a constellation of symptoms that is perceived by patients suggesting bladder hypocontractility. Urodynamic measurement that suggest decreased contractility of the bladder is termed detrusor underactivity (DUA). Regulatory approved specific management options with clinically proven ability to increase bladder contractility do not currently exist. While DUA specific treatments presumably will focus on methods to increase efficiency of bladder emptying capability relying on augmenting the motor pathway in the micturition reflex, other approaches include methods to augment the sensory (afferent) contribution to the micturition reflex which could result in increased detrusor contractility. Another method to induce more efficient bladder emptying could be to induce relaxation of the bladder outlet. Using cellular regenerative techniques, the detrusor smooth muscle can be targeted so the result is to increase detrusor smooth muscle function. In this review, we will cover areas of potential new therapies for DUA including: drug therapy, stem cells and regenerative therapies, neuromodulation, and urethral flow assist device. Paralleling development of new therapies, there also needs to be clinical studies performed that address how DUA relates to UAB.

Sacral neuromodulation for detrusor hyperactivity with impaired contractility

INTRODUCTION

Detrusor hyperactivity with impaired contractility (DHIC) is a challenging condition to manage. Sacral neuromodulation (SNM) is a proven treatment modality for both the individual aspects of DHIC. To date, data reporting the outcome of SNM for DHIC are lacking.

MATERIALS AND METHODS

Consecutive patients undergoing SNM for DHIC were followed prospectively, from April 2013 to October 2016. Patient demographics, bladder diaries, subjective response rates, ICIQ-OAB, and PGI-I scores were recorded. Success was defined as greater than 50% improvement in storage symptoms and a 50% improvement in voided volume or reduction of post-void residual volumes.

RESULTS

Twenty patients underwent stage 1 trial of SNM for DHIC. Median age was 68.5, IQR (54.25-76.25). Thirteen (65%) patients were female. A total of 14/20 (70%) of patients had a significant treatment response, 9/20 had a response to both elements of DHIC, 4/20 patients had a response to the detrusor overactivity (DO) alone, and 1/20 had a response to the voiding component alone. A total of 12/20 (60%) patients proceeded to insertion of an IPG. At mean follow-up of 17 months, IQR (1.5-35), 11/12 (91.7%) of patients are still using the SNM for DHIC. Median PGI score is 2, IQR (2-4). SNM for DHIC resulted in statistically significant improvements in voided volume (P = 0.016), PVR (P = 0.0296), ICIQ-OAB score (P < 0.0001), and ICIQ-OAB bother score (P = 0.016) CONCLUSION: This is the first study we know of to report the results of SNM for DHIC. SNM is associated with satisfactory success rates, treating both the detrusor hyperactivity, and impaired contractility components of this condition.

Association of 17-β Estradiol with Adipose-Derived Stem Cells: New Strategy to Produce Functional Myogenic Differentiated Cells with a Nano-Scaffold for Tissue Engineering

The increased incidence of stress urinary incontinence (SUI) in postmenopausal women has been proposed to be associated with a reduction in the level of 17-β estradiol (E2). E2 has also been shown to enhance the multi-differentiation ability of adipose-derived stem cells (ASCs) in vitro. However, studies on the potential value of E2 for tissue engineering in SUI treatment are rare. In the present study, we successfully fabricated myogenically differentiated ASCs (MD-ASCs), which were seeded onto a Poly(l-lactide)/Poly(e-caprolactone) electrospinning nano-scaffold, and incorporated E2 into the system, with the aim of improving the proliferation and myogenic differentiation of ASCs. ASCs were collected from the inguinal subcutaneous fat of rats. The proliferation and myogenic differentiation of ASCs, as well as the nano-scaffold biocompatibility of MD-ASCs, with or without E2 supplementation, were investigated. We demonstrated that E2 incorporation enhanced the proliferation of ASCs in vitro, and the most optimal concentration was 10-9 M. E2 also led to modulation of the MD-ASCs phenotype toward a concentrated type with smooth muscle-inductive medium. The expression of early (alpha-smooth muscle actin), mid (calponin), and late-stage (myosin heavy chain) contractile markers in MD-ASCs was enhanced by E2 during the different differentiation stages. Furthermore, the nano-scaffold was biocompatible with MD-ASCs, and cell proliferation was significantly enhanced by E2. Taken together, these results demonstrate that E2 can enhance the proliferation and myogenic differentiation of ASCs and can be used to construct a biocompatible cell/nano-scaffold. These scaffolds with desirable differentiation cells show promising applications for tissue engineering.

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.

Voiding dysfunction due to detrusor underactivity: an overview

Detrusor underactivity (DUA) is defined as a voiding contraction of reduced strength and/or duration, which prolongs urination and/or prevents complete emptying of the bladder within a 'normal' period of time. This issue is associated with voiding and postmicturition urinary symptoms, and can predispose to urinary infections and acute urinary retention. The aetiology of DUA is influenced by multiple factors, including ageing, bladder outlet obstruction, neurological disease, and autonomic denervation. The true prevalence of this condition remains unknown, as most data come from referral populations. Urodynamic testing is used to diagnose the condition, either by assessing the relationship between bladder pressures and urinary flow, or by interrupting voiding to measure detrusor pressure change under isovolumetric conditions. Current treatments for DUA have poor efficacy and tolerability, and often fail to improve quality of life; muscarinic receptor agonists, in particular, have limited efficacy and frequent adverse effects. Bladder emptying might be achieved through Valsalva straining, and intermittent or indwelling catheterization, although sacral nerve stimulation can reduce dependency on catheterization. Novel stem-cell-based therapies have been attempted; however, new drugs that increase contractility are currently largely conceptual, and the complex pathophysiology of DUA, difficulty achieving organ specificity of treatment, the limited availability of animal models, and the subjective nature of current outcome measures must be addressed to facilitate the development of such agents.

Effects of agonists for estrogen receptor α and β on ovariectomy-induced lower urinary tract dysfunction in the rat

The postmenopausal hypoestrogen status induces various lower urinary tract dysfunctions. Ovariectomized (OVX) rats exhibit voiding abnormalities, including increased postvoiding residual urine (PVR), decreased voiding efficiency (VE), and altered coordination between the detrusor and external urethral sphincter (EUS). Estradiol replacement partially normalizes voiding function in OVX rats. We determined if selective agonists for estrogen receptor (ER)α and/or ERβ can reverse lower urinary tract dysfunction in OVX rats. Cystometry and EUS electromyograms (EMGs) were recorded 6 wk after bilateral OVX in urethane-anesthetized female Sprague-Dawley rats. Animals received daily subcutaneous injections of selective ERα [propylpyrazole triol (PPT)] or ERβ [diarylpropionitrile (DPN)] agonists or vehicle for 1 wk starting on the fifth week after OVX. PPT (1 mg·kg(-1)·day(-1)) decreased PVR, improved VE, and shortened the EUS EMG active period (AP) during voiding. DPN (2 or 5 mg·kg(-1)·day(-1)) did not alter cystometric parameters or EUS EMG activity. Combined PPT + DPN treatment elicited changes in PVR, VE, and AP, similar to those induced by PPT alone, but also increased the EUS EMG silent period and volume threshold for triggering micturition. PPT increased uterine weight fourfold and decreased body weight by 11%. DPN increased uterine weight 30-45% but decreased body weight by 3-5%. Reduced voiding efficiency in OVX rats can be reversed by 1-wk drug treatment that selectively targets ERα and reduces AP during EUS bursting. Combined pharmacological activation of ERα and ERβ further enhanced EUS bursting by increasing the EUS EMG silent period and also facilitated bladder storage mechanisms by increasing the volume threshold.

Voiding dysfunction in women: How to manage it correctly

INTRODUCTION

Of women aged >40 years, 6% have voiding dysfunction (VD), but the definition for VD in women with respect to detrusor underactivity (DU) and bladder outlet obstruction (BOO) is not yet clear. In this review we address the current literature to define the diagnosis and treatment of VD more accurately.

METHODS

We used the PubMed database (1975-2012) and searched for original English-language studies using the keywords 'female voiding dysfunction', 'detrusor underactivity', 'acontractile detrusor' and 'bladder outlet obstruction and urinary retention in women'. We sought studies including the prevalence, aetiology, pathogenesis, diagnosis and treatment of female VD.

RESULTS

In all, 20 original studies were identified using the selected search criteria, and another 45 were extracted from the reference lists of the original papers. All studies were selected according to their relevance to the current topic and the most pertinent reports were incorporated into this review.

CONCLUSION

Female VD might be related to DU or/and BOO. Voiding and storage symptoms can coexist, making the diagnosis challenging, with the need for a targeted clinical investigation, and further evaluation by imaging and urodynamics. To date there is no universally accepted precise diagnostic criterion to diagnose and quantify DU and BOO in women. For therapy, a complete cure might not be possible for patients with VD, therefore relieving the symptoms and minimising the long-term complications associated with it should be the goal. Treatment options are numerous and must be applied primarily according to the underlying pathophysiology, but also considering disease-specific considerations and the abilities and needs of the individual patient. The treatment options range from behavioural therapy, intermittent (self-)catheterisation, and electrical neuromodulation and neurostimulation, and up to urinary diversion in rare cases.

Pathophysiology of overactive bladder

Overactive bladder (OAB) is a common disorder that negatively affects the quality of life of our patients and carries a large socioeconomic burden. According to the International Continence Society, it is characterized as urinary urgency, with or without urge incontinence, usually, with frequency and nocturia in the absence of causative infection. The pathophysiology of this disease entity varies between neurogenic, myogenic, or idiopathic factors. This paper provides a review of the contemporary theories behind the pathophysiology of OAB.

Detrusor underactivity: a plea for new approaches to a common bladder dysfunction

AIMS

Detrusor underactivity (DU) is defined by the International Continence Society as a contraction of reduced strength and/or duration resulting in prolonged or incomplete emptying of the bladder but has yet received only little attention. The purpose of this report is to summarize the ICI-RS meeting in Bristol in 2010 exploring current knowledge on DU and outline directions for future research.

METHODS

A think tank discussion was held and the summary of discussions was presented to all ICI-RS participants. This report is based on the final discussions.

RESULTS

The understanding of the pathophysiology, epidemiology, assessment, and treatment of DU remains rudimentary. DU is defined by pressure-flow analysis but no consensus exists regarding which of the available formulae should be used for quantification of detrusor work. DU is likely to be multifactorial. Aging causes a decay in detrusor activity but other concomitant causes, either myogenic or neurogenic, may aggravate the problem resulting in decrease of detrusor contractility. No effective pharmacotherapy for the condition exists. Only a few surgical therapeutic strategies have been explored, such as neuromodulation and skeletal muscle myoplasties. Consequently, the management of affected individuals remains unsatisfactory.

CONCLUSIONS

Future directions recommended by the ICI-RS panel include assessment of pathogenesis by developing novel animal models in addition to new non-invasive tests allowing longitudinal trials. Furthermore, optimizing the existing evaluation algorithms to support standard testing for DU and further epidemiological studies to quantify the size of the problem are required for the development of future treatment modalities.

Effects of endogenous ovarian estrogen versus exogenous estrogen replacement on blood flow and ERβα and ERβ levels in the bladder

OBJECTIVE

Determine the effect of endogenous estrogen versus estrogen replacement therapy (ERT) on bladder blood flow (BBF) and estrogen receptors (ERs).

METHODS

BBF was determined with radiolabeled microspheres in luteal, follicular, pregnant, oophorectomized (Ovx) sheep, and Ovx sheep with ERT. Estrogen receptors (ERalpha, ERbeta) were quantified using Western blot analysis.

RESULTS

Compared to luteal and follicular ewes, BBF was reduced in pregnancy and following oophorectomy. Estrogen replacement therapy in Ovx sheep restored BBF to luteal levels. Estrogen receptor alpha predominated, whereas ERbeta was not detectable. Estrogen receptor-alpha levels were unaffected by the ovarian cycle and increased in pregnancy, as well as in Ovx sheep with and without chronic ERT.

CONCLUSION

The combination of diminished BBF and elevated ERalpha levels in both pregnant and Ovx sheep suggests an inverse relationship between BBF and ERalpha in the bladder. Although chronic ERT in Ovx sheep restored BBF, it did not restore ERalpha back to luteal levels.

Effect of the gonadal status and the gender on glycosaminoglycans profile in the lower urinary tract of dogs

Glycosaminoglycans (GAGs) form a functional component of connective tissues that affect the structural and functional integrity of the lower urinary tract (LUT). The specific GAGs of physiological relevance are both nonsulfated (hyaluronan) and sulfated GAGs (chondroitin sulphate [CS], dermatan sulphate [DS], keratan sulphate [KS], and heparan sulphate [HS]). As GAG composition in the LUT is hormonally regulated, we postulated that gonadectomy-induced endocrine imbalance alters the profile of GAGs in the canine LUT. Four regions of the LUT (body and neck of the bladder as well as the proximal and distal urethra) from 20 clinically healthy dogs (5 intact males, 5 intact anoestrus females, 4 castrated males, and 6 spayed females) were collected, wax-embedded and sectioned. Alcian blue staining at critical electrolyte concentrations was performed on the sections to determine total GAGs, hyaluronan, total sulfated GAGs, combined components of CS and DS, as well as KS and HS. The amount of staining was evaluated in 3 tissue layers, i.e., epithelium, subepithelial stroma and muscle within a region. Overall, hyaluronan (67.1%) was the predominant GAG in the LUT. Among sulfated GAGs, a combined component of KS and HS was found to be 61.8% and 38.2% for CS and DS. Gonadal status significantly affected GAG profiles in the LUT (P < 0.01). All GAG components were lower (P < 0.05) in body of the bladder of gonadectomized dogs. Total sulfated GAGs and a combined component of KS and HS were lower (P < 0.05) in all 4 regions of gonadectomized dogs. Except for a combined component of CS and DS, decreases in all GAGs were found more consistently in the muscle compared to other tissue layers. Differences between genders became obvious only when considered along with the effect of gonadal status. In gonadectomized dogs, changes in GAG components in the LUT were more consistent in females compared to males; this may partly explain different levels of risk in the development of urinary incontinence between genders. Quantitative differences in GAG profiles found between intact and gonadectomized dogs indicate a potential role of gonadectomy-induced endocrine imbalance in modifying GAG composition in the canine LUT. Profound alteration in the pattern of GAGs in gonadectomized dogs may compromise structural and functional integrity of the LUT and is possibly involved in the underlying mechanism of urinary incontinence post neutering.

Urothelial signaling

The urinary bladder "mucosa" or innermost portion of the bladder is composed of transitional epithelium, basement membrane, and the lamina propria. This chapter reviews the specialized anatomy of the bladder epithelium (urothelium) and speculates on possible communication mechanisms from urothelial cells to various cell types within the bladder wall. For example, beyond serving as a simple barrier, there is growing evidence that the urinary bladder urothelium exhibits specialized sensory properties and plays a key role in the detection and transmission of both physiological and nociceptive stimuli. Findings from a number of studies suggest that the urothelium exhibits both "sensor" (expressing receptors/ion channels capable of responding to thermal, mechanical, and chemical stimuli) and "transducer" (ability to release chemicals) properties. Thus, urothelial cells exhibit the ability to sense changes in their extracellular environment including the ability to respond to chemical, mechanical, and thermal stimuli that may communicate the state of the urothelial environment to the underlying nervous and muscular systems.

Comparison of the effects of oestrogen deficiency and old age on primary bladder afferent activity and voiding behaviour in the ageing female rat

OBJECTIVE

To determine if a decrease in oestrogen (E) levels increases activity in bladder afferent nerves, by investigating the effects of E loss on afferent nerve activity in ovariectomized (OVX) rats, and making comparisons with findings in ageing female rats.

MATERIALS AND METHODS

Female Sprague-Dawley rats were divided into four groups: ageing; OVX+ E; OVX+ vehicle (V); and sham-operated (SHAM) + V. The E (250 µg/kg) or V (cottonseed oil) was injected s.c. once a week for 8 weeks. Frequency-volume recordings were performed with the rats in metabolic cages, and single Aδ- or C-fibre activities from the bladder were measured. After measurements, the blood serum was collected and the estradiol (E2) level was measured.

RESULTS

The C-fibre activity of OVX + V rats was significantly lower than in the other groups. Aδ-fibre activity was unchanged. Despite low E2 levels, ageing rats showed high afferent activity and voiding frequency.

CONCLUSION

Although a low E level may affect storage function, it is unlikely that it is the main cause of the high afferent activity and voiding frequency observed in the ageing female rat.

Urothelial signaling

Beyond serving as a simple barrier, there is growing evidence that the urinary bladder urothelium exhibits specialized sensory properties and play a key role in the detection and transmission of both physiological and nociceptive stimuli. These urothelial cells exhibit the ability to sense changes in their extracellular environment including the ability to respond to chemical, mechanical and thermal stimuli that may communicate the state of the urothelial environment to the underlying nervous and muscular systems. Here, we review the specialized anatomy of the urothelium and speculate on possible communication mechanisms from urothelial cells to various cell types within the bladder wall.

Effects of beta3-adrenergic receptor activation on rat urinary bladder hyperactivity induced by ovariectomy

Voiding dysfunctions, including increased voiding frequency, urgency, or incontinence, are prevalent in the postmenopausal population. Beta(3)-adrenergic receptor (beta(3)AR) agonists, which relax bladder smooth muscle, are being developed to treat these conditions. We utilized the rat ovariectomy (OVX) model to investigate the effect of ovarian hormone depletion on bladder function and the potential for beta(3)AR agonists to treat bladder hyperactivity in this setting. OVX increased voiding frequency and decreased bladder capacity by approximately 25% in awake rats and induced irregular cystometrograms in urethane-anesthetized rats. Reverse transcription-polymerase chain reaction revealed three betaARs subtypes (beta(1,2,3)) in bladder tissue, and immunostaining indicated beta(3)AR localization in urothelium and detrusor. Receptor expression was not different in OVX and SHAM rats. The beta(3)AR agonist selectivity of BRL37344 [(+/-)-(R(*),R(*))-[4-[2-[[2-(3-chlorophenyl)-2-hydroxyethyl]amino]propyl]phenoxy]acetic acid sodium hydrate], TAK-677 [(3-((2R)-(((2R)-(3-chlorophenyl)-2-hydroxyethyl)amino)propyl)-1H-indol-7-yloxy)acetic acid], and FK175 [acetic acid, 2-[[(8S)-8-[[(2R)-2-(3-chlorophenyl)-2-hydroxyethyl]amino]-6,7,8,9-tetrahydro-5H-benzocyclohepten-2-yl]oxy], ethyl ester, hydrochloride] was confirmed by examining the relative potency for elevation of cAMP in CHOK1 cells overexpressing the various rat betaARs. Intravenous injection of each of the beta(3)AR agonists (0.1-500 microg/kg) in anesthetized rats decreased voiding frequency, bladder pressure, and amplitude of bladder contractions. In bladder strips, beta(3)AR agonists (10(-12)-10(-4) M) decreased baseline tone and reduced spontaneous contractions. BRL37344 (5 mg/kg) and TAK-677 (5 mg/kg) injected intraperitoneally in awake rats decreased voiding frequency by 40 to 70%. These effects were not altered by OVX. The results indicate that OVX-induced bladder dysfunction, including decreased bladder capacity and increased voiding frequency, is not associated with changes in beta(3)AR expression or the bladder inhibitory effects of beta(3)AR agonists. This suggests that beta(3)AR agonists should prove effective for the treatment of overactive bladder symptoms in the postmenopausal population.

Increased alpha1D adrenergic receptor activity and protein expression in the urinary bladder of aged rats

OBJECTIVES

A possibility that aging affects (a) expression of the alpha1D-adrenergic receptor (AR1D), (b) AR1D-mediated contractions and (c) sympathetic innervation in the urinary bladder in rats was studied.

MATERIALS AND METHODS

Contraction produced by phenylephrine and inhibition of these contractions by a non-selective alpha1-adrenergic antagonist prazosin and a selective AR1D antagonist BMY7378 were compared between 6- and 24-month-old Fisher rats. Expressions of VMAT and AR1D in the bladder were assessed by immunofluorescence and Western blot.

RESULTS

Phenylephrine-induced contractions were larger and inhibition of these contractions by BMY7378 was significantly greater in 24-month-old rats. Aging increased expression of AR1D in the bladder. Density of VMAT-immunoreactive neurites was decreased in smooth muscle but elevated in the suburothelial region of 24-month-old rats.

CONCLUSIONS

The results suggest that influence of adrenergic activity on bladder contractility increases with aging is due to overexpression of the AR1D. Influence of adrenergic activity on the urothelial function may also be enhanced with aging.

Differences in the expression of luteinizing hormone and follicle-stimulating hormone receptors in the lower urinary tract between intact and gonadectomised male and female dogs

Receptors for LH (LHR) and FSH (FSHR) are expressed in the canine lower urinary tract (LUT). As gonadectomy results in an increase in plasma LH and FSH, the objective of this study was to determine whether there are any differences in the expression of LHR and FSHR in the LUT between intact and gonadectomised dogs. Four regions of the LUT, i.e. body and neck of the bladder as well as proximal and distal urethra, were collected from 20 healthy dogs (5 intact males, 5 intact anoestrous females, 4 castrated males and 6 spayed females). The mRNA and protein expression of receptors was determined by in situ hybridization and immunohistochemistry, respectively, and assessed semi-quantitatively incorporating both the distribution and the intensity of specific staining. Expression of LHR and FSHR was present in all tissue layers (epithelium, sub-epithelial stroma and muscle) of each region with different levels of the expression. Overall mRNA and protein expression for both LHR and FSHR was significantly (P<0.001) lower in gonadectomised dogs. Intact dogs had more (P<0.05) LHR and FSHR mRNA and protein in all tissue layers of the four regions, except for LHR mRNA expression in the sub-epithelial stroma where no differences were observed between the two statuses. Decreases in LHR and FSHR mRNA and protein in gonadectomised dogs appeared to be more consistent in spayed bitches compared to castrated males. Lower expression of LHR and FSHR observed in gonadectomised dogs may adversely affect the normal canine LUT function.

Increased alpha1-adrenergic activity in the rat bladder by depletion of ovarian hormones

PURPOSE

It is possible that postmenopausal loss of ovarian hormones leads to sensitization and/or over expression of alpha1-adrenergic receptors. The objective of this study was to determine whether ovariectomy enhances efferent transmission and, hence, increases contractility in the rat bladder by increasing alpha1-adrenergic receptors.

MATERIALS AND METHODS

This hypothesis was tested in 4 urethane anesthetized groups of female rats, including regularly cycling rats in metestrus and proestrus, and rats 4 months after ovariectomy with and without estradiol replacement, respectively. The bladder was catheterized through the urethra to measure intravesical pressure. The left femoral artery was also catheterized for local delivery of the nonspecific alpha1-adrenergic agonist phenylephrine, the alpha1-adrenergic antagonist prazosin, the specific alpha1A antagonist 5-methylurapidil or dimethyl sulfoxide (Sigma) in saline vehicle. In some rats bladder contractility was assessed by cystometry, followed by treatment with phenylephrine injected via the femoral artery. In other rats the bladder was denervated and a platinum electrode was wrapped around branches of the left pelvic nerve for electrical stimulation. The amplitude of micturition contractions and contractions evoked by phenylephrine or pelvic nerve stimulation was measured.

RESULTS

Micturition and phenylephrine evoked bladder contractions were significantly increased in ovariectomized rats without estradiol replacement. Prazosin significantly decreased contractions evoked by pelvic stimulation in a dose dependent manner. This decrease was significantly larger in ovariectomized rats without estradiol replacement compared to that in the other groups. The inhibition of stimulation evoked contractions by 5-methylurapidil was also greater in ovariectomized rats without estradiol replacement than in rats with estradiol replacement.

CONCLUSIONS

Results suggest that the depletion of ovarian hormones after ovariectomy enhances alpha1-adrenergic activity.

The effect of maturation and age on oestrogen-induced functional hypertrophy of the female rabbit bladder

OBJECTIVE

To evaluate the effect of maturation and ageing on oestrogen-induced functional hypertrophy of the female rabbit bladder.

MATERIALS AND METHODS

Twenty female rabbits were separated into two groups of 10 each by age, young (immature) and old rabbits and each age group was subdivided into three subgroups. The rabbits in subgroup 1 were controls, subgroup 2 were ovariectomized (Ovx) and subgroup 3 were Ovx and received 17-beta oestradiol (1 mg/kg/day) by a subcutaneous slow-release tablet implant. After 15 days of treatment, the rabbits were killed, the bladder was excised, and the body and base separated; two full-thickness longitudinal strips from the ventral surface of the bladder body, and one full-thickness strip from the base, were prepared for contractile studies. The contractile responses to electrical-field stimulation, carbachol, ATP and KCl were determined for both the bladder body and base strips. In addition, full-thickness strips of bladder body and base were fixed in formalin for histological and immunohistological studies.

RESULTS

Ovx plus oestradiol resulted in significant increases in bladder weight and responses to all forms of stimulation in young and old rabbits (except for the response to KCl). Vascular density and the smooth muscle (SM)/collagen ratio significantly increased after oestradiol replacement. Interestingly, the increase in vascular density was greater in the young than in the old rabbits.

CONCLUSIONS

The present study shows that oestrogen supplementation mediates a functional hypertrophy characterized by increased contractile responses to all forms of stimulation in both young and old rabbits. The increased contractile responses might be explained by the increases in vascular density and SM/collagen ratio.

Influence of oxidative stress and alpha tocopherol supplementation on urothelial cells of the urinary bladder in ovariectomised rats

The present study was designed to investigate whether vitamin E supplementation would influence the levels of oxidative stress and the damage to urothelial cell DNA in the bladders of castrated rats. A total of 30 rats of the Wistar breed were divided into 3 groups of 10 animals each. Group 1 underwent a sham procedure and was killed after 30 days; group 2 underwent bilateral oophorectomy and was killed after 30 days without receiving vitamin E supplementation and group 3 underwent bilateral oophorectomy and received vitamin E supplementation at a dose of 1,000 IU/kg once a week intra-muscularly for 30 days. Four weeks after the procedure, the rats were anesthetised and their bladders were rapidly removed, frozen and stored at -70 degrees C for Comet assaying, which was carried out on lymphocytes and vesicular urothelium cells. The 8-isoprostane concentration in plasma was also determined to confirm the presence of oxidative stress. The 8-isoprostane levels found were higher in oophorectomised rats that had not received vitamin E supplementation than in the sham group and the oophorectomised group with vitamin replacement. Tail moment analysis on the urothelial cells demonstrated that the oophorectomised group presented DNA damage that was statistically significant in comparison with the other groups. On the basis of the above data, vitamin E decreased the effects of oophorectomy on lipid peroxidation and avoided the DNA damage observed in urothelial cells.

Luteinizing hormone and follicle-stimulating hormone receptors and their transcribed genes (mRNA) are present in the lower urinary tract of intact male and female dogs

In dogs, one of the side effects of neutering is the development of urinary incontinence. The relationship between neutering and urinary incontinence caused by acquired urethral sphincter mechanism incompetence (USMI) has been reported. Recently, GnRH analogue treatment that suppresses elevated plasma gonadotrophin concentrations post-spaying has been successfully used in incontinent bitches. These data and the fact that non-gonadal tissues may contain receptors for LH (LHR) and FSH (FSHR) suggest that there might be a functional relationship between gonadotrophins and the lower urinary tract in dogs. This study aimed to investigate the presence of LHR and FSHR in the lower urinary tract of intact male and female dogs. Four regions of the lower urinary tract, i.e. (i) body of the bladder, (ii) neck of the bladder, (iii) proximal urethra and (iv) distal urethra were collected from 10 healthy dogs (5 males and 5 anoestrous females). In situ hybridization and immunohistochemistry were performed to characterise the presence of receptor mRNA and receptor protein. Staining was rated semi-quantitatively, incorporating both the distribution and intensity of specific staining. The distribution of receptor expression in different tissue layers (epithelium, subepithelial stroma and muscle) in each region was statistically analyzed. Luteinizing hormone receptor and FSHR mRNA and protein were present in all four regions and in three tissue layers of males and females. Irrespective of region and layer, female dogs expressed significantly higher expression for LHR mRNA (P<0.001), LHR protein (P<0.05) and FSHR protein (P<0.001). The expression of LHR and FSHR mRNA and protein was not uniform and depended on region, tissue layer and gender. The expression of LHR mRNA was higher in the bladder, compared to the urethra (P<0.05). The FSHR mRNA significantly increased from the bladder to the urethra. Protein expression for LHR and FSHR was highest in the proximal urethra (P<0.05). The overall expression for LHR and FSHR at both mRNA and protein levels was highest in the epithelium, intermediate to low in the subepithelial stroma and muscle. A significant interaction between region and tissue layer showed that mRNA and protein expression for LHR and FSHR decreased from the bladder to the urethra in the epithelium and subepithelial stroma. In contrast, it gradually increased from the bladder to the urethra in the muscle. In conclusion, the present study showed that both mRNA and protein for LHR and FSHR were expressed in the canine lower urinary tract, and the expression levels varied between genders and among regions and tissue layers. The presence of these receptors suggests that gonadotrophins have a role in the physiology and/or pathology of the lower urinary tract function in the dog.

The Impact of Detrusor Overactivity on Bladder Function in Younger and Older Women

PURPOSE

We examined the relationship of DO and aging, and bladder function in female volunteers.

MATERIALS AND METHODS

We recruited 85 cognitively competent, fully functional female volunteers who were 22 to 90 years old (median age 54) with and without symptoms suggestive of DO. Comprehensive assessment included a bladder diary, uroflowmetry and videourodynamics. We examined predefined urodynamic and diary variables for associations with DO and age, summarizing results in the 3 subgroups no DO, intermediate DO and clinically relevant DO.

RESULTS

Compared to women without DO those with DO showed a decrease in maximum cystometric capacity (558 vs 448 ml), mean daytime voided volume (260 vs 175 ml) and volume at strong desire to void (363 vs 283 ml) but an increase in maximum isovolumetric pressure (41 vs 64 cm H2O) and maximum detrusor pressure during involuntary contraction (intermediate and relevant DO 22 and 37 cm H2O, respectively). The positive association between increased detrusor contraction strength and DO was present at younger ages but absent in older subjects. Maximum urethral closure pressure and detrusor contraction strength decreased significantly with age.

CONCLUSIONS

From young adulthood to old age DO appears to affect bladder function parameters. It is associated with decreased bladder capacity and increased bladder sensation. Moreover, in younger adults DO is also associated with increased detrusor contraction strength, which is an association not seen in older individuals. This age associated loss of muscle function may be related to sarcopenia, implying that different treatments may be appropriate in older adults.

Agrin becomes concentrated at neuroeffector junctions in developing rodent urinary bladder

The formation of somatic neuromuscular junctions in skeletal muscle is regulated by an extracellular matrix protein called agrin. Here, we have examined the expression and localization of agrin during development of the rodent urinary bladder, as a first step to examining its possible role at autonomic neuroeffector junctions in smooth muscle. We have found that agrin is expressed on the surface of developing smooth muscle cells and in the basement membrane underlying the urothelium. More importantly, agrin is progressively concentrated at parasympathetic varicosities during postnatal development and is present at virtually all junctions in mature muscle. Reverse transcription/polymerase chain reaction analysis has shown that pelvic ganglion neurons that innervate the bladder express LN/z8 agrin, whereas bladder smooth muscle expresses LN/z- agrin. Together, these results demonstrate that nerve and/or muscle agrin becomes localized at cholinergic parasympathetic varicosities in smooth muscle, where it could play a role in the maturation of the neuroeffector junction.

Short-term functional and neuroregenerative response of the urethra to ovariectomy and vaginal distension in female rats

The objective of this study was to investigate the effects of ovariectomy (OVX) and vaginal distension (VD) on leak point pressure (LPP) and pudendal nerve regenerative response in the female rat. Twenty rats underwent OVX 3 days prior to either VD or sham distension. Seventeen rats did not receive OVX but underwent either VD or sham distension. Four days after distension, LPP testing was performed. In situ hybridization for beta(II) tubulin mRNA, an indicator of the neuroregenerative response, was performed on motoneurons of the pudendal nerve. In the non-OVX group, LPP was significantly decreased after VD. After OVX, the difference in LPP between VD and sham rats did not quite reach the level of statistical significance. There was a statistically significant interaction between the effects of OVX and VD on LPP. There was no significant difference in in situ hybridization results between any of the groups. No neuroregenerative response of motoneurons of the pudendal nerve was observed after either VD or OVX.

Estrogen and Postnatal Maturation Increase Caveolar Number and Caveolin-1 Protein in Bladder Smooth Muscle Cells

PURPOSE

Clinical studies indicate that detrusor contractility decreases in old age and the dense band pattern with caveolar depletion represents the ultrastructural norm of the aged human detrusor. We performed animal studies to explore the hypothesis that lowering estrogen induces the dense band pattern with estrogen replacement restoring usual sarcolemmal appearance and increasing caveolar number.

MATERIALS AND METHODS

Newborn, young (1-month-old) and middle-aged (13 to 14-month-old) female rats were studied. Middle-aged animals were evaluated 4 months after sham operation or ovariectomy (OVx) with OVx rats receiving placebo or 25% 17beta-estradiol (E2) capsules for 1 week prior to sacrifice. Electron microscopy was used to evaluate sarcolemmal structure and quantify caveolar numbers in bladder muscle cells. Caveolae were also assessed by measuring caveolin-1 protein.

RESULTS

Alternating electron dense and thinner zones with abundant caveolae were present in bladder sarcolemma from middle-aged animals. Newborn and OVx sarcolemma showed many ultrastructural features of the dense band pattern with fewer caveolae present per micro sarcolemma or per muscle cell compared with sham operated middle-aged controls. E2 replacement decreased the dense band pattern and increased caveolar numbers in OVx animals. Caveolin-1 protein levels underwent similar changes following maturation, OVx and E2 replacement, while alpha-smooth muscle actin remained unchanged.

CONCLUSIONS

Prolonged estrogen withdrawal results in sarcolemmal changes in middle-aged animals, similar to the dense pattern observed in newborns. Estrogen replacement decreases the dense pattern, while increasing caveolar numbers and caveolin-1 protein. It remains to be seen whether estrogen influences caveolar depletion and/or contractility in human bladders.

Analysis of the Modifications in the Composition of Bladder Glycosaminoglycan and Collagen as a Consequence of Changes in Sex Hormones Associated With Puberty or Oophorectomy in Female Rats

PURPOSE

The effects of female sex hormones on rat vesical extracellular matrix were evaluated by analyzing glycosaminoglycan (GAG) and collagen composition under different hormonal conditions.

MATERIALS AND METHODS

Bladders were obtained from Wistar rats, including young prepubertal females at age 30 days (YF), and adult intact females (AF), adult oophorectomized females (AOF), adult males and adult sham operated females at age 120 days. Oophorectomy and sham operation were performed at age 30 days. Bladders were analyzed for total GAG and collagen concentration per mg dry tissue and for the contents of GAG species, as determined by agarose electrophoresis and reported as the percent of total sulfated GAG.

RESULTS

Collagen concentration in AF (54.80 +/- 4.60 microg/mg) was different from that in YF (34.52 +/- 5.29 microg/mg, p <0.001) and AOF (63.25 +/- 3.51 microg/mg, p <0.001). GAG concentration in AF (0.71 +/- 0.18 microg/mg) was different from that in YF (0.45 +/- 0.07 microg/mg, p <0.001) and males (0.46 +/- 0.10 microg/mg, p <0.001). The GAG species detected were dermatan sulfate and heparan sulfate. Dermatan sulfate content in AF (90.9% +/- 2.8%) was different from that in YF (86.6% +/- 2.4%, p <0.005), AOF (87.9% +/- 2.1%, p <0.005) and males (87.7% +/- 4.7%, p <0.005). Heparan sulfate content in AF was 9.1% +/- 2.8%, which differed from that in YF (13.4% +/- 2.4%, p <0.025) and AOF (11.2% +/- 2.9%, p <0.025).

CONCLUSIONS

Extracellular matrix of the female rat bladder undergoes marked remodeling during normal growth up to early adulthood with important consequences for vesical viscoelastic properties. Also, oophorectomy performed at a prepubertal age may lead to greater vesical wall stiffness.

The effect of ovariectomy and estradiol on rabbit bladder smooth muscle contraction and morphology

PURPOSE

The bladder can be considered a target organ for the actions of estrogen. Decreases in circulating estrogen after menopause have been associated with bladder dysfunctions, including incontinence and detrusor instability. We determined the effects of estrogen on rabbit bladder contractile function and morphology.

MATERIALS AND METHODS

Female New Zealand White rabbits were ovariectomized or sham operated and treated with vehicle or estradiol (1 mg/kg weekly) for 5 weeks. Serum estradiol concentration was monitored every 2 weeks. After treatment each rabbit was anesthetized, the bladder was catheterized, cystometry was performed, and the bladder was removed for contractile and morphological studies. Apoptosis in paraffin embedded rabbit bladder tissue was detected using in situ end-labeling, specifically terminal deoxynucleotidyl-transferase nick end labeling or the TUNEL assay.

RESULTS

Ovariectomy resulted in a 50% decrease in circulating estrogen and estradiol treatment resulted in a 5-fold increase. Ovariectomy had no significant effects on bladder capacity, micturition pressure or bladder weight; whereas estradiol treatment resulted in significant increases in bladder capacity and bladder weight. Ovariectomy resulted in a decreased rate of tension generation in response to field stimulation, carbachol and KCl. Estradiol resulted in increased contractile responses to FS and carbachol, and an increased rate of tension generation for carbachol and KCl. Histologically ovariectomy resulted in significant urothelial apoptosis, which was not present in the sham operated or estradiol treated groups. Estradiol treatment resulted in the appearance of large cytoplasmic vacuoles in the urothelium and significant smooth muscle hypertrophy.

CONCLUSIONS

These findings demonstrate that bladder function and structure can be significantly affected by modulating the circulating estrogen level. In addition, estrogen given in pharmacological doses can have a significant hypertrophic effect on bladder smooth muscle, resulting in increased contractile function.

Phytoestrogens for hormone replacement therapy?

Due to some severe side effects "classical" hormone replacement therapy (HRT) is currently being challenged by a therapy with phytoestrogens. Particularly soy and red clover derived isoflavones are advertised as selective estrogen receptor modulators (SERMs) with only desired and no undesired estrogenic effects. Evidence that this is the case however is scarce. Most studies investigating climacteric complaints did not find beneficial effects. A proposed beneficial effect on mammary cancer is unproven. The majority of studies however indicate an antiosteoporotic effect of isoflavones, while putative beneficial effects in the cardiovascular system are questionable due to the fact that estradiol which--like isoflavones--increase HDL and decrease LDL concentrations appear not to prevent arteriosclerosis in the human. In the urogenital tract, including the vagina, soy and red clover derived isoflavones are without effects. Cimicifuga racemosa extracts are traditionally used for the treatment of climacteric complaints. Evidence is now available that the yet unknown compounds in Cimicifuga racemosa extracts prevent climacteric complaints and may also have antiosteoporotic effects.