Effect of partial and complete blockade of vanilloid (TRPV1-6) and ankyrin (TRPA1) transient receptor potential ion channels on urinary bladder motor activity in an experimental hyperosmolar overactive bladder rat model

The study investigated the mechanisms through which the hyperosmolarity might induce detrusor overactivity (DO). We compared the bladder activity in response to partial and complete blockade of TRPV1-6 and TRPA1 receptors. Experiments were performed on 42 rats. DO was induced by using hyperosmolar saline. All animals were randomly divided into six groups. The measurements represent the average of five bladder micturition cycles. Hyperosmolar saline induced DO. The complete blockade of TRPV1-6 and TRPA1 prevented DO. The partial blockade of TRPV1 didn't prevented DO. In the voiding phase periodical bladder contractions complexes occurred leading to slow urine flow due to bladder distension. Ruthenium red and capsaicin resulted in complete disorganisation of detrusor muscle contractility impairing urine voiding and leading to constantly lasting urine retention in healthy rats. Conclusions: hyperosmolar-induced DO is mediated by TRPV and TRPA1 channels; the hyperosmolar stimuli of urinary bladder might be transmitted mostly via ruthenium red sensitivity pathway.     

Pathophysiology of overactive bladder and urge urinary incontinence

Storage symptoms such as urgency, frequency, and nocturia, with or without urge incontinence, are characterized as overactive bladder (OAB). OAB can lead to urge incontinence. Disturbances in nerves, smooth muscle, and urothelium can cause this condition. In some respects the division between peripheral and central causes of OAB is artificial, but it remains a useful paradigm for appreciating the interactions between different tissues. Models have been developed to mimic the OAB associated with bladder instability, lower urinary tract obstruction, neuropathic disorders, diabetes, and interstitial cystitis. These models share the common features of increased connectivity and excitability of both detrusor smooth muscle and nerves. Increased excitability and connectivity of nerves involved in micturition rely on growth factors that orchestrate neural plasticity. Neurotransmitters, prostaglandins, and growth factors, such as nerve growth factor, provide mechanisms for bidirectional communication between muscle or urothelium and nerve, leading to OAB with or without urge incontinence.     

Expression of cyclooxygenase-2 in urinary bladder in rats with cyclophosphamide-induced cystitis

These studies examined the expression of cyclooxygenase-2 (COX-2) expression in the urothelium and suburothelial space and detrusor from rats treated with cyclophosphamide (CYP) to induce acute (4 h), intermediate (48 h), or chronic (10-day) cystitis. Western blot analysis and immunohistochemistry were used to demonstrate COX-2 expression. In whole mount preparations of urinary bladder, nerve fibers in the suburothelial plexus, and inflammatory cell infiltrates were characterized for COX-2 expression after CYP-induced cystitis. COX-2 expression significantly (P 相似文献   

Phosphorylation of extracellular signal-regulated kinases in urinary bladder in rats with cyclophosphamide-induced cystitis

Phosphorylated ERK expression has been demonstrated in the central and peripheral nervous system after various stimuli, including visceral stimulation. Changes in the activation (i.e., phosphorylation) of extracellular signal-regulated kinases (pERK) were examined in the urinary bladder after 4 h (acute), 48 h (intermediate), or chronic (10 day) cyclophosphamide (CYP) treatment. CYP-induced cystitis significantly (P < or = 0.01) increased pERK expression in the urinary bladder with intermediate (48 h) and chronic CYP treatment. Immunohistochemistry for pERK immunoreactivity revealed little pERK-IR in control or acute (4 h) CYP-treated rat urinary bladders. However, pERK expression was significantly (P < or = 0.01) upregulated in the urothelium after 48 h or chronic CYP treatment. Whole mount preparations of urothelium/lamina propria or detrusor smooth muscle from control (noninflamed) rats showed no pERK-IR in PGP9.5-labeled nerve fibers in the suburothelial plexus. However, with CYP-treatment (48 h, chronic), a few pERK-IR nerve fibers in the suburothelial plexus of whole mount preparations of bladder and at the serosal edge of urinary bladder sections were observed. pERK-IR cells expressing the CD86 antigen were also observed in urinary bladder from CYP-treated rats (48 h, chronic). Treatment with the upstream inhibitor of ERK phosphorylation, U0126, significantly (P < or= 0.01) increased bladder capacity in CYP-treated rats (48 h). These studies suggest that therapies targeted at pERK pathways may improve urinary bladder function in CYP-treated rats.     

Association of overactive bladder and stress urinary incontinence in rats with pudendal nerve ligation injury

Approximately one-third of patients with stress urinary incontinence (SUI) also suffer from urgency incontinence, which is one of the major symptoms of overactive bladder (OAB) syndrome. Pudendal nerve injury has been recognized as a possible cause for both SUI and OAB. Therefore, we investigated the effects of pudendal nerve ligation (PNL) on bladder function and urinary continence in female Sprague-Dawley rats. Conscious cystometry with or without capsaicin pretreatment (125 mg/kg sc), leak point pressures (LPPs), contractile responses of bladder muscle strips to carbachol or phenylephrine, and levels of nerve growth factor (NGF) protein and mRNA in the bladder were compared in sham and PNL rats 4 wk after the injury. Urinary frequency detected by a reduction in intercontraction intervals and voided volume was observed in PNL rats compared with sham rats, but it was not seen in PNL rats with capsaicin pretreatment that desensitizes C-fiber-afferent pathways. LPPs in PNL rats were significantly decreased compared with sham rats. The contractile responses of detrusor muscle strips to phenylephrine, but not to carbachol, were significantly increased in PNL rats. The levels of NGF protein and mRNA in the bladder of PNL rats were significantly increased compared with sham rats. These results suggest that pudendal nerve neuropathy induced by PNL may be one of the potential risk factors for OAB, as well as SUI. Somato-visceral cross sensitization between somatic (pudendal) and visceral (bladder) sensory pathways that increases NGF expression and alpha(1)-adrenoceptor-mediated contractility in the bladder may be involved in this pathophysiological mechanism.     

Neuromodulation in a rat model of the bladder micturition reflex

A rat model of bladder reflex contraction (BRC) was used to determine the optimal frequency and intensity of spinal nerve (SN) stimulation to produce neuromodulation of bladder activity and to assess the therapeutic mechanisms of this neuromodulation. In anesthetized female rats (urethane 1.2 g/kg ip), a wire electrode was used to produce bilateral stimulation of the L6 SN. A cannula was placed into the bladder via the urethra, and the urethra was ligated to ensure an isovolumetric bladder. Saline infusion induced BRC. Electrical stimulation of the SN produced a frequency- and intensity-dependent attenuation of the frequency of bladder contractions. Ten-herz stimulation produced maximal inhibition; lower and higher stimulation frequency produced less attenuation of BRC. Attenuation of bladder contraction frequency was directly proportional to the current intensity. At 10 Hz, stimulation using motor threshold pulses (T(mot)) produced a delayed inhibition of the frequency of bladder contractions to 34 ± 11% of control. Maximal bladder inhibition appeared at 10 min poststimulation. High current intensity at 0.6 mA (～6 * T(mot)) abolished bladder contraction during stimulation, and the inhibition was sustained for 10 min poststimulation (prolonged inhibition). Furthermore, in rats pretreated with capsaicin (125 mg/kg sc), stimulation produced a stronger inhibition of BRC. The inhibitory effects on bladder contraction may be mediated by both afferent and efferent mechanisms. Lower intensities of stimulation may activate large, fast-conducting fibers and actions through the afferent limb of the micturition reflex arc in SN neuromodulation. Higher intensities may additionally act through the efferent limb.     

Exogenous overexpression of nerve growth factor in the urinary bladder produces bladder overactivity and altered micturition circuitry in the lumbosacral spinal cord

Background  

Exogenous NGF or saline was delivered to the detrusor smooth muscle of female rats for a two-week period using osmotic mini-pumps. We then determined: (1) bladder function using conscious cystometry; (2) organization of micturition reflexes using Fos protein expression in lumbosacral (L5-S1) spinal cord neurons; (3) calcitonin gene-related peptide (CGRP)-immunoreactivity (IR) in lumbosacral spinal cord segments.     

Mouse models of short- and long-term foreign body in the urinary bladder: analogies to the bladder segment of urinary catheters.

Catheter-associated bacteriuria is the most common infection occurring in hospitals, where urethral catheters are generally in place for a few days, and in nursing homes, where catheters may be in place for months or years. We developed murine models with intrabladder urinary catheters for studying complications of bacteriuria in short- and long-term catheterization. In the short-term model, a catheter segment was inserted transurethrally and lay free within the bladder lumen. Half of the animals expelled segments during a 2-to-7-day period, durations similar to catheterizations in hospitalized patients. For studies of long-term catheter use, the catheter segment was secured within the bladder by a single suture for up to 12 months. Antibiotics administered for 7 days after catheter placement and housing mice in cages with wire screen floors reduced spontaneous bacteriuria to an acceptably low incidence rate of only 7%. Proteus mirabilis bacteriuria of high concentration provoked the same complications that are common in patients with long-term catheters: acute pyelonephritis, chronic renal inflammation, and struvite stone formation. These models allow inoculation of the bacteria of interest and are suitable for studies of short- and long-term foreign body-associated bacteriuria and its complications.     

Alpha1 adrenoceptor subtypes in human urinary bladder: sex and regional comparison

A detailed study of the presence of alpha1 AR binding sites and alpha1 AR subtype mRNA expression in human urinary bladder areas involved in the micturition (i.e. detrusor, trigone and neck) is reported here, investigating whether or not there are differences between sexes. Results obtained indicated that alpha1 AR proteins were detectable in each bladder area. In both sexes, the detrusor and the neck expressed similar levels of alpha1 ARs: respectively, detrusor: 14.6 +/- 1.2 in men and 13.1 +/- 1.1 fmol/mg prot in women; neck: 16.9 +/- 3.2 in men and 17.5 +/- 4.1 fmol/mg prot in women. In the trigone, significantly higher alpha1ARs were found in women compared to men (20.6 +/- 1.1 vs 11.7 +/- 0.7 fmol/mg prot). Subtype analysis indicated that in women, each area was endowed with mRNA encoding for each alpha1 AR subtype. The men detrusor expressed alpha1a and alpha1d ARs, while in the trigone and the neck, each subtype was present. Since the detrusor muscle hypertrophy is a marker of bladder obstructive outlet, the selective alpha1 AR subtype targeting arouses much interest, as evidence indicates that there are differences in signalling pathways among the subtypes. Furthermore, the significance of the alpha1 ARs coexpression is still unknown; interestingly, recent papers demonstrate that alpha1 AR subtypes could dimerize. Thus, in the human urinary bladder it may be suggested a potential level of alpha1 AR complexity that could have an impact on drug development.     

Modulation of spontaneous activity in the overactive bladder: the role of P2Y agonists

Spinal cord transection (SCT) leads to an increase in spontaneous contractile activity in the isolated bladder that is reminiscent of an overactive bladder syndrome in patients with similar damage to the central nervous system. An increase in interstitial cell number in the suburothelial space between the urothelium and detrusor smooth muscle layer occurs in SCT bladders, and these cells elicit excitatory responses to purines and pyrimidines such as ATP, ADP, and UTP. We have investigated the hypothesis that these agents underlie the increase in spontaneous activity. Rats underwent lower thoracic spinal cord transection, and their bladder sheets or strips, with intact mucosa except where specified, were used for experiments. Isometric tension was recorded and propagating Ca(2+) and membrane potential (E(m)) waves were recorded by fluorescence imaging using photodiode arrays. SCT bladders were associated with regular spontaneous contractions (2.9 ± 0.4/min); ADP, UTP, and UDP augmented the amplitude but not their frequency. With strips from such bladders, a P2Y(6)-selective agonist (PSB0474) exerted similar effects. Fluorescence imaging of bladder sheets showed that ADP or UTP increased the conduction velocity of Ca(2+)/E(m) waves that were confined to regions of the bladder wall with an intact mucosa. When transverse bladder sections were used, Ca(2+)/E(m) waves originated in the suburothelial space and propagated to the detrusor and urothelium. Analysis of wave propagation showed that the suburothelial space exhibited properties of an electrical syncitium. These experiments are consistent with the hypothesis that P2Y-receptor agonists increase spontaneous contractile activity by augmenting functional activity of the cellular syncitium in the suburothelial space.     

Overview of overactive bladder, prostatitis, and lower urinary tract symptoms for the primary care physician

As an increasing number of treatment options for urologic disorders become available, patients with these conditions are more often able to be managed in the primary care setting. Primary care physicians, therefore, must become more knowledgeable of the proper urologic terminology and the screening tools that have traditionally been used by urologists. To that end, this article reviews the terminology associated with lower urinary tract symptoms and describes the evaluation and treatment of patients presenting with these symptoms. The diagnoses of overactive bladder and prostatitis are discussed, as well as the therapeutic options available for these patients.     

Treatment of overactive bladder and incontinence in the elderly

The prevalence of urinary incontinence (UI) and overactive bladder rises with age, and elderly people are the fastest-growing segment of the population. Many elderly people assume UI is a normal part of the aging process and do not report it to their doctors, who must therefore make the effort to elicit the information from them. Coexisting medical problems in older patients and the multiple medications many of them take make diagnosis and treatment more complex in this population. Just as the etiology of incontinence is often multifactorial, the treatment approach may need to be multipronged, with behavioral, environmental, and medical components; in any case, it must be targeted to the individual patient. New, less-invasive surgical techniques and devices make surgery more feasible if other therapy fails.     

Caldesmon ablation in mice causes umbilical herniation and alters contractility of fetal urinary bladder smooth muscle

The actin-, myosin-, and calmodulin-binding protein caldesmon (CaD) is expressed in two splice isoforms: h-CaD, which is an integral part of the actomyosin domain of smooth muscle cells, and l-CaD, which is widely expressed and is involved in many cellular functions. Despite extensive research for many years, CaD''s in vivo function has remained elusive. To explore the role of CaD in smooth muscle contraction in vivo, we generated a mutant allele that ablates both isoforms. Heterozygous animals were viable and had a normal life span, but homozygous mutants died perinatally, likely because of a persistent umbilical hernia. The herniation was associated with hypoplastic and dysmorphic abdominal wall muscles. We assessed mechanical parameters in isometrically mounted longitudinal strips of E18.5 urinary bladders and in ring preparations from abdominal aorta using wire myography. Ca²⁺ sensitivity was higher and relaxation rate was slower in Cald1^−/− compared with Cald1^+/+ skinned bladder strips. However, we observed no change in the content and phosphorylation of regulatory proteins of the contractile apparatus and myosin isoforms known to affect these contractile parameters. Intact fibers showed no difference in actin and myosin content, regardless of genotype, although KCl-induced force tended to be lower in homozygous and higher in heterozygous mutants than in WTs. Conversely, in skinned fibers, myosin content and maximal force were significantly lower in Cald1^−/− than in WTs. In KO abdominal aortas, resting and U46619 elicited force were lower than in WTs. Our results are consistent with the notion that CaD impacts smooth muscle function dually by (1) acting as a molecular brake on contraction and (2) maintaining the structural integrity of the contractile machinery. Most importantly, CaD is essential for resolution of the physiological umbilical hernia and ventral body wall closure.     

Autophagic activity in the mouse urinary bladder urothelium as a response to starvation

The urinary bladder urothelium is subjected to mechanical forces during cycles of distension and contraction, and its superficial cells are constantly flushed by toxic urine. Yet, the urothelium shows a very slow turnover of cells and superficial cells are extremely long lived. Autophagy has a well-known role in tissue homeostasis and serves as a protective mechanism against cellular stress. Therefore, the presence of autophagy as one of possible processes of survival in an unpleasant environment and during long lifetime of superficial cells was examined in mouse urothelium. We detected and evaluated autophagic activity of superficial urothelial cells under normal and stress conditions, caused by short-term starvation of newborn and 24-h-starved adult mice. Immunolabeling and Western blotting of essential effectors of autophagy, LC3 and Beclin 1, showed a weak signal in superficial urothelial cells. On the other hand, ultrastructural analysis, which proved to be the most reliable method in our study, revealed the presence of autophagic vacuoles, some of them containing specific urothelial structures, fusiform vesicles. Quantitative analysis showed increased autophagy in newborn and starved mice in comparison to a low basic level of autophagy in the urothelium of normal mice. Interestingly, some superficial cells of adults and neonates exhibit intense immunoreactions against LC3 and Beclin 1 and the typical ultrastructural characteristics of autophagy-dependent cell death. We conclude that autophagy, despite low basic activity under physiological conditions, plays an important role in urothelial homeostasis and stability under stress.     

New frontiers in the treatment of overactive bladder and incontinence

In this article the author tries to forecast how urologists will treat the overactive bladder (OAB) in the next decade. He reviews drugs currently under development and also logical and exciting pharmacological targets that would be suitable targets for treating OAB in the future. The author also discusses intravesical therapy and alternative drug delivery methods, such as intravesical capsaicin and botulinum toxin. There are many advantages to advanced drug delivery systems, including the achievement of long-term therapeutic efficacy, decreased incidence and severity of side effects, and improved patient compliance. Special emphasis is placed on approaches to modulating bladder afferent nerve function to prevent OAB. Speculation on future techniques such as gene therapy can also be considered for treating OAB, because they may make it possible to access all of the genitourinary organs via minimally invasive techniques. Traditional anticholinergic therapies are limited in their effectiveness. There is great hope for future research and therapy for OAB and urinary incontinence.     

Effect of taxifolin on cyclophosphamide-induced oxidative and inflammatory bladder injury in rats

The role of oxidative stress and inflammation in the pathogenesis of cyclophosphamide-related side effects has been demonstrated in previous studies. This study aimed to investigate the effect of taxifolin, due to its antioxidant and anti-inflammatory properties, on cyclophosphamide-induced oxidative and inflammatory bladder injury in albino Wistar rats. The taxifolin+cyclophosphamide (TCYC) group was given 50 mg/kg of taxifolin orally by gavage. Normal saline was used as a solvent for the cyclophosphamide (CYC) group and the healthy control (HC) group. One hour after taxifolin administration, 75 mg/kg of cyclophosphamide was intraperitoneally injected in the TCYC and CYC groups. This procedure was repeated once a day for 30 days. At the end of this period, biochemical markers were studied in the excised bladder tissues and histopathological evaluations were conducted. In the histopathological evaluation of the CYC group, severe epithelial irregularity, dilatation, congestion, and polymorphonuclear leukocyte accumulation in the vascular structures were observed. Additionally, the malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) levels, the total oxidant status (TOS), and the oxidative stress index (OSI) values were significantly higher, and the total glutathione (tGSH) levels and total antioxidant status (TAS) were significantly lower in the CYC group in comparison to the HC group (P<0.001). Taxifolin reduced the cyclophosphamide-induced increases in the MDA, TNF-α, IL-1β, and IL-6 levels and the TOS and OSI values; it decreased the tGSH and TAS levels and reduced histopathological damage (P<0.001). Taxifolin may be useful in the treatment of cyclophosphamide-induced bladder damage.     

Toad carbonic anhydrase: purification of the enzyme from erythrocytes of Bufo marinus and comparison with the enzyme activity in the urinary bladder.

1. Two forms of carbonic anhydrase, having isoelectric points of 6.1 and 5.8, were purified from erythrocytes of the toad, Bufo marinus, and the presence of a third form, pI = 5.4, was demonstrated. 2. Each of the two purified isozymes catalyzed the hydration of CO2 and the hydrolysis of nitrophenyl acetate esters at rates characteristic of Type C (or high-activity) forms of carbonic anhydrase. 3. Both forms of the erythrocyte enzyme have similar molecular weights (approx 29,000), amino acid composition, sensitivity to acetazolamide, and kinetic properties. 4. The epithelium of the toad's urinary bladder also was found to contain significant amounts of carbonic anhydrase, which appears by isoelectric focusing to be indistinguishable from the enzyme isolated from the erythrocyte.