Partial Outlet Obstruction Research Articles

Chronic Cyclic Bladder Over Distention Up-Regulates Hypoxia Dependent Pathways

Bladder over distention secondary to anatomical or functional obstruction can eventually lead to pathological changes, including decreased elasticity and contractile dysfunction. We hypothesized that chronic bladder distention in a murine model would activate hypoxia dependent signaling pathways despite intermittent relief of distention. Female C57Bl/6 mice were oophorectomized at age 5 to 6 weeks and underwent urethral catheterization and 90-minute bladder distention. Acute and chronic time points were evaluated. Bladder tissue was harvested for hematoxylin and eosin, and immunohistochemical staining with the hypoxia markers Glut-1 (EMD Millipore, Merck, Darmstadt, Germany) and Hypoxyprobe™-1. Bladder tissue was also harvested for real-time polymerase chain reaction and oxidative stress measurement. Hypoxia polymerase chain reaction arrays were done to determine changes in gene expression. Oxidative stress was measured using F2-IsoP. Functional bladder changes were evaluated using voided urine blots. After acute distention and 5 consecutive distentions, bladders showed marked inflammatory changes on hematoxylin and eosin staining, and evidence of tissue hypoxia on immunohistochemistry. Quantitative real-time polymerase chain reaction revealed up-regulation of hypoxia and oxidative stress related genes, including Hif1a, Arnt2, Ctgf, Gpx1 and Hmox1. Measurements of oxidative stress with F2-IsoP did not change. Voided urine blots before and after bladder distention showed marked changes with an overactive voiding pattern. Chronic bladder distention is possible in the female mouse. It generates hypoxic injury, as characterized functionally by increased voiding patterns. This bladder injury model might more closely replicate bladder dysfunction in patients with poor bladder emptying due to neurological disease, including those noncompliant with intermittent catheterization.

Partial outlet obstruction in rabbits: Duration versus severity

Oxidative stress is a major etiology of obstructed bladder dysfunction. The major goal of the current study was to correlate the level of oxidative stress with both the severity and duration of obstruction. A total of 32 New Zealand White rabbits were divided into four equal groups. Groups 1-3 received partial bladder outlet obstructions by standard methods and survived for 4, 8 or 12 weeks. Group 4 received sham surgery at the end of each time period, isolated strips were taken for contractility studies and the balance of the bladder was frozen as muscle and mucosa for quantification of nitrotyrosine and carbonyl-oxidized proteins derivatized into dinitrophenyl. For each duration, the eight rabbits were divided into three severity groups: mild, intermediate or severe decompensation. Contractile responses decreased in proportion to both severity and duration. The level of both oxidative products correlated to a much higher degree with the level of severity than the duration. There were significant decreases in the contractile responses in the mild decompensation group, whereas the level of derivatized into dinitrophenyl and nitrotyrosine of the muscle remained at control levels. This was not the case for the 4 weeks obstructed group. These findings suggest that the etiology for the mechanism of contractile dysfunction is not an oxidative stress.

Insights from a novel model of slow-transit constipation generated by partial outlet obstruction in the murine large intestine

The mechanisms underlying slow-transit constipation (STC) are unclear. In 50% of patients with STC, some form of outlet obstruction has been reported; also an elongated colon has been linked to patients with STC. Our aims were 1) to develop a murine model of STC induced by partial outlet obstruction and 2) to determine whether this leads to colonic elongation and, consequently, activation of the inhibitory "occult reflex," which may contribute to STC in humans. Using a purse-string suture, we physically reduced the maximal anal sphincter opening in C57BL/6 mice. After 4 days, the mice were euthanized (acutely obstructed), the suture was removed (relieved), or the suture was removed and replaced repeatedly (chronically obstructed, over 24-31 days). In partially obstructed mice, we observed increased cyclooxygenase (COX)-2 levels in muscularis and mucosa, an elongated impacted large bowel, slowed transit, nonpropagating colonic migrating motor complexes (CMMCs), a lack of mucosal reflexes, a depolarized circular muscle with slow-wave activity due to a lack of spontaneous inhibitory junction potentials, muscle hypertrophy, and CMMCs in mucosa-free preparations. Elongation of the empty obstructed colon produced a pronounced occult reflex. Removal of the obstruction or addition of a COX-2 antagonist (in vitro and in vivo) restored membrane potential, spontaneous inhibitory junction potentials, CMMC propagation, and mucosal reflexes. We conclude that partial outlet obstruction increases COX-2 leading to a hyperexcitable colon. This hyperexcitability is largely due to suppression of only descending inhibitory nerve pathways by prostaglandins. The upregulation of motility is suppressed by the occult reflex activated by colonic elongation.

Modulation of Alpha 1 Adrenergic Receptors on Urinary Bladder in Rat Spinal Cord Injury Model

PurposeWhereas many studies have focused on the vesical changes of the α1 adrenergic receptor (AR) subtypes in partial outlet obstruction, few studies have addressed the modulation of the α1 AR subtypes after spinal cord injury (SCI). Therefore, we studied the modulation of the α1 ARs in urinary bladder in a rat SCI model.MethodsFour weeks after a SCI, the whole vesical bodies from eight female Sprague-Dawley rats and from eight controls were harvested. The total RNA was extracted from the samples and was used to prepare cDNA. We developed standard plasmid constructs of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and three α1 ARs (α1a, α1b, and α1d) to convert the cycle threshold (Ct) values from real-time polymerase chain reaction (RT-PCR) into subtype mRNA concentrations. The detected Ct values of 16 samples from RT-PCR were interpolated into the standard plasmid curves.ResultsAll serially diluted standard samples showed very good linearity. The mRNA expression of GAPDH was higher in the SCI group, whereas the mRNA expression of all α1 ARs was lower in the SCI group than in the control animals. The α1a, α1b, and α1d mRNA expression in the controls was 81.7%, 3.3%, and 15.1%, respectively, whereas the α1a, α1b, and α1d mRNA expression in the SCI group was 33.5%, 5.2%, and 60.9%, respectively.ConclusionsSCI moderates the α1 AR mRNA subtypes in the urinary bladder. The relatively increased α1d or decreased α1a AR mRNA expression may be a therapeutic candidate for controlling the symptoms of neurogenic bladder after SCI.

Effect of solifenacin plus and minus antioxidant supplements on the response to experimental outlet obstruction and overactive bladder dysfunction in rabbits—Part 2

ObjectiveOne of the most common forms of bladder dysfunction is related to the development of unstable bladder contractions (bladder overactivity). Solifenacin is a relatively new, selective, antimuscarinic agent that has been shown to be particularly useful in the treatment of overactive bladder (OAB) dysfunctions in both men and women. Experimentally, we have demonstrated that OAB and obstructive bladder dysfunction are associated with the generation of free radicals and oxidative damage to the bladder. The hypothesis tested was that solifenacin + coenzyme Q10 + α-lipoic acid (CoQ + LA) would be more effective in the treatment of OAB than either would be individually. Materials and methodsForty-eight male White New Zealand rabbits were separated into 8 groups of 6 rabbits each. The following oral treatments were given to each group: Groups 1 and 5, vehicle (saline); Groups 2 and 6, solifenacin; Groups 3 and 7, CoQ + LA; Groups 4 and 8, solifenacin + CoQ + LA. After three weeks of treatment (by oral gavage), the rabbits in Groups 1–4 received partial outlet obstruction as detailed above. The rabbits continued their treatments for four weeks following surgery. At the end of this four-week period, immediately following urodynamic and physiological studies, the bladder was excised and the muscle and mucosa were separated and frozen for biochemical research. ResultsThe following marker enzymes were quantitated: choline acetyltransferase, citrate synthase, catalase, superoxide dismutase, and malondialdehyde (MDA, marker for lipid peroxidation). Solifenacin had no effect on citrate synthase activity of the bladder smooth muscle. However, pretreatment with both the antioxidants or the combination of solifenacin + antioxidants protected the citrate synthase activity such that it remained at control values. Partial outlet obstruction (PBOO) resulted in a 60% decrease in choline acetyltransferase activity (ChAT) activity, while solifenacin had no effect on reduced ChAT activity. Both the antioxidant and combination therapy resulted in maintaining ChAT activity at control values. PBOO resulted in a significant increase in MDA of both the muscle and mucosa. For both tissues, all treatments resulted in a significantly lower MDA content. In general, the results demonstrate the combination of solifenacin + antioxidants was more effective than either solifenacin or antioxidants alone. ConclusionThe addition of the antioxidants CoQ + LA works synergistically with solifenacin in the treatment of obstructive bladder dysfunction and OAB.

Effect of solifenacin with and without antioxidant supplements on the response to experimental outlet obstruction and overactive bladder dysfunction in rabbits: Part 1

ObjectiveOne of the most common forms of urinary dysfunction is related to the development of overactive bladder (OAB) dysfunction. Solifenacin is a relatively new selective antimuscarinic agent that has been shown to be particularly useful in treating OAB dysfunction in both men and women. Experimentally, we have previously demonstrated that OAB is associated with the generation of free radicals and oxidative damage to the bladder. We tested the hypothesis that the combination of solifenacin + coenzyme Q10 (CoQ10) + α-lipoic acid (α-LA) is more effective in treating OAB than the individual compounds. Materials and MethodsIn total, 48 male New Zealand White rabbits were separated into 8 groups of 6 rabbits each. The following oral treatments were given to each group: groups 1 and 5 received vehicle (saline); groups 2 and 6 received solifenacin; groups 3 and 7 received CoQ10 + α-LA; and groups 4 and 8 received solifenacin + CoQ10 + α-LA. After 3 weeks of treatment (by oral gavage), rabbits in groups 1 to 4 received partial outlet obstruction. The rabbits continued their treatments for 4 weeks following surgery. At the end of this 4-week period, each rabbit received cystometry and then underwent an in situ study for OAB. ResultsThe results clearly demonstrated that obstructive bladder dysfunction and the level of OAB were reduced in all three treatment groups, but the combination of solifenacin + antioxidants was significantly more effective than either solifenacin or antioxidants alone. ConclusionThe addition of the antioxidants CoQ10 + α-LA worked synergistically with solifenacin in the treatment of obstructive bladder dysfunction and OAB.

Calcineurin mediates bladder wall remodeling secondary to partial outlet obstruction.

We hypothesized that the calcineurin-nuclear factor of activated T-cells (NFAT) pathway is activated following partial bladder outlet obstruction (pBOO), which would allow for pharmacologic treatment to prevent the ensuing bladder wall hypertrophy. Using a model of pBOO in male mice, we were able to demonstrate increased nuclear importation of the transcription factors NFAT and myocyte enhanching factor 2 both of which are under control of calcineurin in both the whole bladder wall as well as the urothelium. We further confirmed that this pathway was activated using transgenic mice containing an NFAT-luciferase reporter construct. Mice were randomized following pBOO to treatment with or without cyclosporine A (CsA), a known inhibitor of calcineurin. The bladder-to-body mass ratio (mg bladder wt/g body wt) of 0.95 ± 0.03 in shams increased to 3.1 ± 0.35 following pBOO, and it dropped back to 1.7 ± 0.22 in the CsA+ group (P < 0.001). Luciferase values (RLU) of 1,130 ± 133 in shams increased to 2,010 ± 474 following pBOO and were suppressed to 562 ± 177 in the CsA+ group (P < 0.05). The myosin heavy chain mRNA (A/B) isoform ratio of 0.07 ± 0.03 in shams increased to 1.04 ± 0.19 following pBOO but it diminished to 0.24 ± 0.1 in the CsA+ group (P < 0.001). In vitro whole organ physiology studies demonstrated improved responses in those bladders from mice treated with CsA. The mRNAs for all four known calcineurin-responsive NFAT isoforms are expressed in the bladder wall, although NFATc(3) and NFATc(4) predominate. Both NFATc3 and NFATc4 are expressed in urothelial as well as smooth muscle cells. We conclude that pBOO activates the calcineurin-NFAT pathway and that CsA treatment decreased bladder hypertrophy, shifted the pattern of myosin isoform mRNA expression back toward that seen in normal controls, and resulted in improved in vitro whole organ performance.

Nonvoiding Activity of the Guinea Pig Bladder

Detrusor nonvoiding contractions occur in up to 70% of healthy individuals. These contractions increase in those with pathological detrusor function and may be associated with afferent activity. We examined nonvoiding contractions in the urethane anesthetized guinea pig bladder and studied the effect of filling rate and intravesical volume. A total of 14 guinea pigs were anesthetized and underwent bladder catheterization at the dome. In 6 guinea pigs bladder infusion was continuous and 2 physiological filling rates were used, including 25 (0.75 HD) and 50 μl per minute (1.5 HD). In another 8 guinea pigs isovolumetric cystometry was done by filling the bladder incrementally and recording at low, medium and high intravesical volume. Nonvoiding contractions were apparent in all animals. Contractions increased in frequency and amplitude as the bladder filled. Different phases were identified. Immediately after a void no nonvoiding contractions were observed, followed by continuous activity, first with small contractions, and later with small and large contractions. Small nonvoiding contractions showed a phasic pattern in frequency while the frequency of large nonvoiding contractions slowly increased or remained stable. The frequency and amplitude of nonvoiding contractions were higher at a faster filling rate and a higher intravesical volume. Nonvoiding contractions are present in the anesthetized guinea pig. Under normal physiological conditions they increase in amplitude and frequency with the increase in the filling rate and in intravesical volume. Small and large nonvoiding contractions differ in frequency pattern and occur at different bladder filling periods. This may illustrate different afferents functioning during bladder filling, which could be important for understanding bladder pathology.

Regulation of Connexin 43 by Basic Fibroblast Growth Factor in the Bladder: Transcriptional and Behavioral Implications

Basic fibroblast growth factor is a candidate causative factor of detrusor overactivity in bladder outlet obstruction cases through up-regulation of the gap junction protein connexin 43. We addressed the transcriptional and behavioral implications of this axis. Cx43 and Cx45 mRNA expression was assessed by real-time reverse transcriptase-polymerase chain reaction in the bladder of a rat bladder outlet obstruction model and in cultured rat bladder smooth muscle cells with and without basic fibroblast growth factor treatment. Involvement of the extracellular signal regulated kinase 1/2-activator protein-1 pathway was evaluated by immunofluorescence study and a promoter-reporter assay in bladder smooth muscle cells. The effect of basic fibroblast growth factor on micturition behavior was measured in unrestrained rats under a 12-hour light/dark cycle using a controlled release system from gelatin hydrogels fixed on the bladder. The expression of extracellular signal regulated kinase 1/2 and connexin 43 protein was assessed by Western blotting of rat bladder protein. Cx43 but not Cx45 mRNA expression was increased in the bladder of the obstruction model and in bladder smooth muscle cells treated with basic fibroblast growth factor. The mitogen-activated and extracellular signal-regulated kinase kinase inhibitor PD98059 blocked the stimulatory effect of basic fibroblast growth factor on connexin 43 protein expression and promoter activity, which was also decreased by mutation or deletion of an activator protein-1 cis-element of the connexin 43 promoter. In vivo application of basic fibroblast growth factor on the bladder increased urinary frequency during the latter half of the dark phase, ie the late active phase of rats (F = 5.1, 2-way ANOVA p <0.05). The expression of phospho-extracellular signal regulated kinase 1/2 and connexin 43 protein was increased in the bladder. The extracellular signal regulated kinase 1/2-activator protein-1-connexin 43 axis could be a potential therapeutic target for increased urinary frequency.

Role of Nitric Oxide Synthase in Bladder Pathologic Remodeling and Dysfunction Resulting From Partial Outlet Obstruction

To investigate the relationship between nitric oxide synthase (NOS) and oxidative stress and pathologic remodeling in the partial obstructed bladder of a rat model. We surgically established partial bladder outlet obstruction (PBOO) in 2 groups of rats and allowed it to persist for 3-6 weeks. Normal and sham-operated rats served as the controls. Each group contained 6 rats for a total of 24 rats. Cystometry was used to evaluate the bladder function. The bladders were removed, and histopathologic measurements were performed to evaluate bladder hypertrophy and fibrosis and NOS immunolocalization. Biochemical measurements were used to evaluated NOS mRNA and activity and the oxidative stress level. The obstructed rats experienced significant increases in bladder weight, muscle hypertrophy, and deposits of collagen fibers compared with the normal and sham-operated groups. PBOO debilitated bladder contractibility, increased the residual urine volume and voiding interval, decreased the voiding volume, and caused poor bladder emptying, with an increased residual urine volume and decompensated bladder in the PBOO rats at 6 weeks. The elevation in malondialdehyde and reduction in superoxide dismutase activity in the PBOO rats suggested that oxidative stress injury occurred in the obstructed bladder. Lower inducible NOS and endothelial NOS (eNOS) mRNA expression was demonstrated through quantitative polymerase chain reaction. In particular, eNOS was significantly downregulated in the PBOO rats compared with the normal and sham-operated rats. The normal and PBOO bladder tissues did not express detectable levels of neuronal NOS mRNA or exhibit neuronal NOS immunoreactivity. The total NOS activity had decreased progressively in the PBOO groups in conjunction with the significantly decreased eNOS activity compared with that in the normal and sham-operated groups. These findings suggest that decreases in NOS activity and expression (mainly of eNOS) concomitant with increases in reactive oxygen species generation represent the underlying pathogenic mechanism of obstructed bladder remodeling and dysfunction.

A giant trichobezoar causing rapunzel syndrome in a 12-year-old female

Bezoar is a tightly packed collection of undigested material that is unable to exit the stomach. Most bezoars are of indigestible organic matter such as hair-trichobezoars; or vegetable and fruit–phytobezoars; or a combination of both. Trichobezoars commonly occur in patients with psychiatric disturbances who chew and swallow their own hair. In very rare cases, the Rapunzel syndrome hair extends through the pylorus into the small bowel causing symptom and sign of partial or complete gastric outlet obstruction. A case report of trichobezoar in the stomach causing Rapunzel syndrome in a 12-year-old female is reported.

Role of antioxidants in the treatment of obstruction-mediated rabbit urinary bladder dysfunction

Benign prostatic hyperplasia (BPH) is a common medical problem; more than 80% of males 50 years of age and older have some degree of bladder outlet obstruction secondary to BPH. In order to understand the effects of outlet obstruction on bladder structure and function, animal models have been developed using several species including rat, rabbit, guinea pig, and pig. Although there are marked differences in bladder size, capacity, compliance, physiology and pharmacology among these species, their responses to outlet obstruction have many common characteristics. Recent reviews have enumerated these responses of animal bladders to partial outlet obstruction; their relevance to progressive bladder dysfunction secondary to BPH in men. We have found that the rabbit is most similar to man in that the rabbit urinates between 3 and 5 times per day, we can evaluate bladder function through urodynamics performed similar to that used in man, and cystoscopy can be performed using a pediatric cystiscope.

Oxidative Modification of Mitochondrial Integrity and Nerve Fiber Density in the Ischemic Overactive Bladder

To our knowledge the mechanism of neurodegeneration in the overactive bladder remains unknown. We examined mitochondrial integrity and searched for markers of oxidative neural injury in the ischemic overactive bladder. A rabbit model of overactive bladder was developed by inducing moderate pelvic ischemia. After 16 weeks cystometrograms and blood flow recordings from overactive bladders were compared with those in age matched controls. Bladder tissues were processed to assess oxidative products, oxidative stress sensitive genes and nerve fiber density using enzyme immunoassay, quantitative real-time polymerase chain reaction and immunohistochemical staining, respectively. Tissue ultrastructure was examined by transmission electron microscopy. Ischemia increased spontaneous bladder contractions and led to cyclic ischemia-reperfusion. Tissue levels of oxidative and nitrosative products, and oxidative stress sensitive genes encoding superoxide dismutase and aldose reductase were up-regulated in the overactive bladder. Transmission electron microscopy of overactive bladder tissues showed mitochondria with distinctive morphological features, characterized by swollen membranes, decreased granules, a total loss of granules and sporadic membrane damage. These changes were associated with sporadic loss of epithelial mucosal membrane, twisted smooth muscle cells, diffused vacuolization and marked neurodegeneration. Our findings suggest free radical mediated ultrastructural damage and neurodegeneration in the overactive bladder. Overactivity associated mitochondrial stress may have a central role in epithelial damage, smooth muscle cell injury and neurodegeneration. Superoxide dismutase and aldose reductase up-regulation in the overactive bladder imply intrinsic defensive reaction against free radicals that apparently fails to prevent oxidative damage and neurodegeneration. Therapeutic strategies targeting basic mitochondrial processes such as energy metabolism or free radical generation may help better manage wall degeneration and neuropathy in the overactive bladder.

Bladder outlet obstruction in male cystinuria mice

Cystinuria is the most common inherited cause of urinary tract stones in children. It can lead to obstructive uropathy, which is a major cause of renal failure. Genetic studies have identified two genes, SLC3A1 and SLC7A9, to be directly involved in cystine stone formation. Slc3a1 knockout male mice develop cystine stones in the bladder and, to a lesser extent, in the kidney. Slc3a1 knockout female mice also develop cystinuria, but they do not form stones. The specific aim of this study was to characterize bladder function in cystinuria mice. Eight control (4 male, 4 female) and 16 Slc3a1 knockout (9 male, 7 female) mice of mixed strain background (C57B/129, age 4-5 months) were evaluated. Each mouse was anesthetized and the bladder dome catheterized for cystometry. Immediately following cystometry, the bladder was excised, weighed, and separated into three full thickness strips for contractile studies. Bladders from cystinuria male mice had significantly increased weight, all of them had stones, decreased compliance, and decreased contractile responses to field stimulation, ATP, carbachol, and KCl. Compared with controls, female knockout mice showed normal bladder weight, decreased voiding pressure, slightly decreased compliance, and slightly decreased contractile responses. These studies clearly demonstrate that the bladder stones that developed in the male cystinuria mice resulted in a partial outlet obstruction. Although the female cystinuria mice did not have bladder stones, bladder function was mildly impaired; presumably by the presence of cystine crystals.

Differential Expression of Vascular Endothelial Growth Factor, and Angiopoietin 1 and 2 in Functionally Divergent Experimental Rabbit Models of Bladder Hypertrophy

Partial bladder outlet obstruction or ovariectomy with subsequent estrogen replenishment induces bladder hypertrophy in rabbits and yet the functional outcomes of these procedures differ. We investigated whether these models might be distinguished by differential expression of the genes controlling angiogenesis. Groups of male rabbits underwent sham surgery or partial bladder outlet obstruction for 1 or 2 weeks. Groups of females underwent sham surgery, ovariectomy or ovariectomy plus estrogen for 1 or 2 weeks. Bladders from each group were weighed and assayed for the contractile response, smooth muscle content and vascular density. Mucosa and muscle layers were separated and RNA from the fractions was assayed by quantitative real-time polymerase chain reaction to measure the relative expression of vascular endothelial growth factor, and angiopoietin 1 and 2 mRNA. Male bladders with partial outlet obstruction had attributes that typified hypertrophy with a loss of contractile function. Vascular endothelial growth factor expression was up-regulated in the mucosa and muscle layers but the effect was most pronounced in mucosa. Angiopoietin 1 expression was significantly up-regulated in muscle. Female bladders with ovariectomy plus estrogen had attributes that typified bladder hypertrophy with increased contractile function. Vascular endothelial growth factor expression was up-regulated early in mucosa but more highly and consistently increased in muscle. Angiopoietin 1 and 2 expression was not significantly affected. Although these models have similar outcomes with regard to bladder hypertrophy, they have opposite functional outcomes that coincide with compartmental differences in the expression of genes involved in the regulation of angiogenesis. The disparity in gene expression might explain the difference in the functional outcomes.

Biochemical Alterations in Partial Bladder Outlet Obstruction in Mice: Up-Regulation of the Mitogen Activated Protein Kinase Pathway

We evaluated the effect of partial bladder outlet obstruction on bladder weight, protein synthesis, mitotic markers and the mitogen activated protein kinase pathway in a mouse model. Mice were divided into 3 groups, including control, sham treated and partially obstructed. Bladders were harvested from the mice in the partially obstructed group 12, 24, 48, 72 and 168 hours after surgical partial outlet obstruction, respectively. Partially obstructed bladders were compared to bladders in the control and sham treated groups by weight, protein content, and expression of proliferating cellular nuclear antigen, cyclin D3, HsP 70, c-jun and phosphorylated c-jun. Bladders were examined histologically for changes occurring with partial obstruction. We tested 3 groups of mice, including control, sham treated and partially obstructed mice, to understand the pathophysiology of the bladder response to partial obstruction. We found no statistical difference in body weight among the groups. Furthermore, there was a significant increase in bladder weight and protein content in partially obstructed mice compared to those in controls and sham operated mice. There was up-regulation of proliferating cellular nuclear antigen, cyclin D3, HsP70, c-jun and phosphorylated c-jun with partial obstruction. Fibrosis was prominent at 168 hours compared to that in controls. Bladder weight and protein content increase with partial bladder outlet obstruction in mice. Cell cycle proteins and elements of the mitogen activated protein kinase pathway are up-regulated during this process.

Partial bladder outlet obstruction reduces the tissue antioxidant capacity and muscle nerve density of the guinea pig bladder

Reactive nitrogen and oxygen species (RNOS) likely play a role in the development of bladder dysfunction related to bladder outlet obstruction. Antioxidants protect against these free radicals. The aim of our study was to investigate the effect of bladder outlet obstruction on the endogenous antioxidant status of the bladder and to correlate this to bladder structure and function. In 16 guinea pigs either a partial outlet obstruction or a sham operation was induced. The contractile responses of detrusor strips to electrical field stimulation (EFS), acetylcholine, potassium, and ATP were monitored 4 weeks after the operation. The nerve density in bladder tissue was determined by using the non-specific nerve marker PGP 9.5. Separate antioxidants and the total antioxidant status were assessed using the trolox equivalent antioxidant capacity (TEAC) test. Contractile responses of detrusor strips to EFS were for the greater part based on neurogenic stimulation. The nerve-mediated responses in strips from obstructed bladders were lower compared to the sham group. Obstructed bladders showed a patchy denervation and the nerve density was significantly lower compared to the sham group. The total antioxidant capacity, the glutathione and the glutathione reductase (GR) levels significantly decreased in obstructed bladders compared to the sham group. This study demonstrates that the antioxidant status of guinea pig bladders exposed to outlet obstruction decreased which might be associated with the observed reduction in nerve density. The results strengthen the hypothesis that oxidative stress is involved in the pathophysiology of bladder dysfunction related to obstructed bladders. Neurourol. Urodynam. 28:461-467, 2009. (c) 2008 Wiley-Liss, Inc.

Expression of Parathyroid-Hormone- Related Protein in the Partially Obstructed Rabbit Bladder

Introduction: Parathyroid-hormone-related protein (PTHrP) is considered as an autocrine/paracrine regulator of growth and/or differentiation in normal and malignant tissues. We determined the distribution and density of the expression of PTHrP in the rabbit bladder during growth in response to partial outlet obstruction and its relation with the smooth muscle/collagen ratio. Materials and Methods: A total of 30 male New Zealand White rabbits were studied. After 7, 14, 28 or 56 days of obstruction, 6 rabbits per group were sacrificed and the bladder extracted. Six sham-operated rabbits served as controls. The expression and localization of PTHrP or collagen type III were detected by immunohistochemistry using specific antibodies. Results: The levels of PTHrP were progressively increased by 14 days of obstruction, whereas they decreased after 14 days, although the PTHrP positivity was higher than in sham controls by 28 and 56 days of obstruction. PTHrP staining was related to the smooth muscle/collagen ratio, both showing a peak in rabbits obstructed for 14 days. Conclusions: These data indicate that PTHrP may play an important regulatory role in the cellular and vascular response to partial outlet obstruction.

Partial outlet obstruction of the rabbit urinary bladder induces selective protein oxidation

Oxidation of proteins is presumed to contribute to contractile dysfunction associated with partial outlet obstruction (PBOO) of the urinary bladder. The objective of this study was to determine the acute and chronic effects of PBOO on protein oxidation in urinary bladder detrusor smooth muscle (DSM) and mucosa, and to correlate these findings with in vitro contractile function. Urinary bladders of New Zealand White (NZW) rabbits were obstructed for 1, 3, 7 and 14 days. Proteins were extracted from the bladder tissues and protein carbonyl formation was assessed using immunoblot assays. In vitro contractile response to field stimulation (32 Hz) and carbachol was evaluated in whole bladder strips at the same time points. Significant elevations in oxidation of DSM proteins were observed in the MW range of 29-65 kDa after 3 days and 14 days of obstruction. No changes in the oxidative status of mucosal proteins were detected as a result of short or long term obstruction. The intermediate filament protein, desmin (53-55 kDa) was detected in obstructed DSM samples in the same MW range as oxidized proteins. A significant decrease in contractile response to field stimulation and carbachol was observed after 1 day and 3-days respectively, and continued to deteriorate through 14 days. The increase in protein oxidation at 14-days of obstruction correlates with impaired bladder contractility, suggesting that oxidatively modified proteins may contribute to the contractile and biochemical dysfunction associated with PBOO.

Kohki Tea Protects the Rabbit Bladder from Ischemia/Reperfusion-Induced Contractile Dysfunction

Objectives: Results of several studies indicated that ischemia/reperfusion is an etiological factor in obstructive bladder dysfunction. Kohki tea pretreatment was shown to reduce the dysfunctions induced by partial outlet obstruction in rabbits. The current study was designed to determine if pretreatment of rabbits with Kohki tea could prevent the contractile dysfunctions induced by bilateral ischemia followed by reperfusion. Methods: New Zealand white rabbits were separated into several groups; one half of each group was pretreated by oral gavage for 3 weeks with Kohki tea and the other half was treated with vehicle (water). Experimental groups were subjected to bilateral ischemia for either 1 or 3 h followed by reperfusion for either 1 h or 1 week (4 groups). The results from the experimental groups were compared to the groups of rabbits receiving sham operations. Results: Under all experimental conditions, Kohki tea significantly reduced the contractile dysfunctions induced by ischemia and ischemia followed by reperfusion. Conclusions: This data is consistent with the concept that Kohki tea acts by protecting the bladder smooth muscle and mucosa from cellular damage caused by ischemia/reperfusion.