Changes in urethral smooth muscle and external urethral sphincter function with age in rats.

To confirm changes in urethral activity with age, both intravesical pressure and urethral perfusion pressure (UPP) were recorded and external urethral sphincter electromyography (EUS-EMG) was performed. A total of 33 female Sprague Dawley rats aged 3 months (young rats), 12 months (middle-aged rats), and 24 months (aged rats) were used. Bladder activity was evaluated using continuous cystometry. Urethral activity was evaluated by simultaneously recording intravesical pressure and UPP in isovolumetric conditions under urethane anesthesia in each group. Additionally, EUS-EMG activity was monitored under the same conditions. In continuous cystometry, the amplitude of bladder contractions was not different among the three groups; nevertheless, residual urine volume was significantly increased in middle-aged and aged rats, as compared in young rats. With respect to UPP, the change in UPP was significantly smaller in aged rats (60%) and middle-aged rats (64%) than in young rats. Furthermore, the mean amplitude of high-frequency oscillations of the EUS was significantly lower in aged (61%) and middle-aged rats (70%) than in young rats. EUS-EMG revealed EUS bursting activity during voiding with clear active and silent phases in young rats but unclear active and silent phases in aged rats. Masson's trichrome staining of the urethra showed EUS atrophy in aged rats compared to young and middle-aged rats. The results indicate that aging induces two urethral dysfunctions in the urethral smooth muscle and EUS, which may lead to dyscoordination between the urinary bladder and urethra.

Current and Future Directions of Stem Cell Therapy for Bladder Dysfunction.

Stem cells are capable of self-renewal and differentiation into a range of cell types and promote the release of chemokines and progenitor cells necessary for tissue regeneration. Mesenchymal stem cells are multipotent progenitor cells with enhanced proliferation and differentiation capabilities and less tumorigenicity than conventional adult stem cells; these cells are also easier to acquire. Bladder dysfunction is often chronic in nature with limited treatment modalities due to its undetermined pathophysiology. Most treatments focus on symptom alleviation rather than pathognomonic changes repair. The potential of stem cell therapy for bladder dysfunction has been reported in preclinical models for stress urinary incontinence, overactive bladder, detrusor underactivity, and interstitial cystitis/bladder pain syndrome. Despite these findings, however, stem cell therapy is not yet available for clinical use. Only one pilot study on detrusor underactivity and a handful of clinical trials on stress urinary incontinence have reported the effects of stem cell treatment. This limitation may be due to stem cell function loss following ex vivo expansion, poor in vivo engraftment or survival after transplantation, or a lack of understanding of the precise mechanisms of action underlying therapeutic outcomes and in vivo behavior of stem cells administered to target organs. Efficacy comparisons with existing treatment modalities are also needed for the successful clinical application of stem cell therapies. This review describes the current status of stem cell research on treating bladder dysfunction and suggests future directions to facilitate clinical applications of this promising treatment modality, particularly for bladder dysfunction.

Mesenchymal stromal cells modulate the molecular pattern of healing process in tissue-engineered urinary bladder: the microarray data.

BACKGROUND: Molecular mechanisms underlying the regenerative process induced by stem cells in tissue-engineered urinary bladder are poorly explained. The study was performed to explore the pathways associated with regeneration process in the urinary bladder reconstructed with adipose tissue-derived mesenchymal stromal cells (ASCs). METHODS: Rat urinary bladders were reconstructed with bladder acellular matrix (BAM) (n = 52) or BAM seeded with adipose tissue-derived mesenchymal stromal cells (ASCs) (n = 52). The process of bladder healing was analyzed at 7, 30, 90, and 180 days postoperatively using macroscopic histologic and molecular techniques. Gene expression was analyzed by microarrays and confirmed by real-time PCR. RESULTS: Numerous differentially expressed genes (DEGs) were identified between the bladders augmented with BAM seeded with ASCs or BAM only. Pathway analysis of DEGs allows to discover numerous pathways among them Hedgehog, TGF-ß, Jak-STAT, PI3-Akt, and Hippo modulated by ASCs during the healing process of tissue-engineered urinary bladder. Real-time PCR analysis confirmed upregulation of genes involved in the Hedgehog signaling pathway including Shh, Gli1, Smo, Bmp2, Bmp4, Wnt2, Wnt2b, Wnt4, Wnt5a, and Wnt10 in urinary bladders reconstructed with ASC-seeded grafts. CONCLUSION: The study provided the unequivocal evidence that ASCs change the molecular pattern of healing in tissue-engineered urinary bladder and indicated which signaling pathways triggered by ASCs can be associated with the regenerative process. These pathways can be used as targets in the future studies on induced urinary bladder regeneration. Of particular interest is the Hedgehog signaling pathway that has been upregulated by ASCs during healing of tissue-engineered urinary bladder.

Age-related changes in function and gene expression of the male and female mouse bladder.

We investigated age-related changes in in vivo and in vitro functions and gene expression of the bladder of male and female mice. Mature and aged (12 and 27-30 month old) C57BL/6 mice of both sexes were used. Frequency volume, conscious free-moving cystometry and detrusor contractile and relaxant properties in in vitro organ bath were evaluated. mRNA expression level of muscarinic, purinergic, and ß-adrenergic receptors and gene expression changes by cDNA microarray analysis of the bladder were determined. Cystometry demonstrated storage and voiding dysfunctions with ageing in both sexes. Detrusor strips from aged mice showed weaker contractile responses particularly in the cholinergic component and weaker relaxant responses to isoproterenol. These age-related impairments were generally severer in males. mRNA expression of bladder tissue was decreased for M3 muscarinic receptors in aged males and ß2-adrenoceptors in aged females. cDNA microarray analysis results, albeit substantial sex difference, indicated "cell-to-cell signaling and interaction" as the most common feature of age-related gene expression. In summary, aged mice demonstrated voiding and storage dysfunctions resembling to detrusor hyperactivity with impaired contractility (DHIC), which were more pronounced in males. Genomic changes associated with aging may contribute to the age-related bladder functional deterioration in mice.

Mode of Surgical Injury Influences the Source of Urothelial Progenitors during Bladder Defect Repair.

The bladder urothelium functions as a urine-blood barrier and consists of basal, intermediate, and superficial cell populations. Reconstructive procedures such as augmentation cystoplasty and focal mucosal resection involve localized surgical damage to the bladder wall whereby focal segments of the urothelium and underlying submucosa are respectively removed or replaced and regeneration ensues. We demonstrate using lineage-tracing systems that urothelial regeneration following augmentation cystoplasty with acellular grafts exclusively depends on host keratin 5-expressing basal cells to repopulate all lineages of the de novo urothelium at implant sites. Conversely, repair of focal mucosal defects not only employs this mechanism, but in parallel host intermediate cell daughters expressing uroplakin 2 give rise to themselves and are also contributors to superficial cells in neotissues. These results highlight the diversity of urothelial regenerative responses to surgical injury and may lead to advancements in bladder tissue engineering approaches.

Bladder regeneration in a canine model using a bladder acellular matrix loaded with a collagen-binding bFGF.

Bladder reconstruction remains challenging for urological surgery due to lack of suitable regenerative scaffolds. In a previous study, we had used a collagen-binding basic fibroblast growth factor (CBD-bFGF) to bind bFGF to the collagen scaffold, which could promote bladder regeneration in rats. However, the limited graft size in rodent models cannot provide enough evidence to demonstrate the repair capabilities of this method for severely damaged bladders in humans or large animals. In this study, the CBD-bFGF was used to activate a bladder acellular matrix (BAM) scaffold, and the CBD-bFGF/BAM functional scaffold was assessed in a canine model with a large segment defect (half of the entire bladder was resected). The results demonstrated that the functional biomaterials could promote bladder smooth muscle, vascular, and nerve regeneration and improve the function of neobladders. Thus, the CBD-bFGF/BAM functional scaffold may be a promising biomaterial for bladder reconstruction.

Fibroblast growth factor receptor signaling in kidney and lower urinary tract development.

Fibroblast growth factor receptors (FGFRs) and FGF ligands are highly expressed in the developing kidney and lower urinary tract. Several classic studies showed many effects of exogenous FGF ligands on embryonic renal tissues in vitro and in vivo. Another older landmark publication showed that mice with a dominant negative Fgfr fragment had severe renal dysplasia. Together, these studies revealed the importance of FGFR signaling in kidney and lower urinary tract development. With the advent of modern gene targeting techniques, including conditional knockout approaches, several publications have revealed critical roles for FGFR signaling in many lineages of the kidney and lower urinary tract at different stages of development. FGFR signaling has been shown to be critical for early metanephric mesenchymal patterning, Wolffian duct patterning including induction of the ureteric bud, ureteric bud branching morphogenesis, nephron progenitor survival and nephrogenesis, and bladder mesenchyme patterning. FGFRs pattern these tissues by interacting with many other growth factor signaling pathways. Moreover, the many genetic Fgfr and Fgf animal models have structural defects mimicking numerous congenital anomalies of the kidney and urinary tract seen in humans. Finally, many studies have shown how FGFR signaling is critical for kidney and lower urinary tract patterning in humans.

Age-related changes in bladder function with altered angiotensin II receptor mechanisms in rats.

AIMS: To examine alterations in expression of angiotensin II type 1 receptors (AT1R) which induce organ tissue remodeling, angiotensin II type 2 receptors (AT2R) which protect against it, and related molecules in the bladder of matured rats with bladder dysfunction. METHODS: Female SD rats of three different ages were used: 8 weeks old (8W; n = 5), 9 months old (9M; n = 5), and 15 months old (15M; n = 5). After cystometry, the expression levels of AT1R, connexin43 (Cx43), MAP kinase (MAPK), collagen1, AT2R, PPAR-γ, adiponectin (Adipo), and adiponectin receptor (Adipo-R) were investigated in the bladder. RESULTS: Pressure threshold, post-void residual volume and the number of non-voiding contractions were significantly increased in 15M versus 8W rats (P < 0.01). Maximum voiding pressure was significantly decreased in 15M versus 8W rats (P < 0.05). There was no significant difference in CMG parameters between 8W and 9M rats. In the bladder, the mRNA expression of AT1R, Cx43, MAPK, collagen 1, AT2R, PPAR-γ, Adipo, and Adipo-R were significantly higher in 15M than in 8W rats. The relative expression ratio of AT1R protein against AT2R protein in the mucosa and detrusor was significantly increased in 15M versus 8W rats. CONCLUSIONS: These results indicate that matured rats exhibit not only bladder overactivity but also impaired voiding, which are associated with upregulation of AT1R. The upregulation of AT2R also may play a significant role in the suppressing of AT1R induced remodelling. However, because AT1R upregulation is more dominant than AT2R increases, AT2R activation may not be sufficient to suppress AT1R stimulation in matured rats. Neurourol. Urodynam. 35:908-913, 2016. © 2015 Wiley Periodicals, Inc.

Time-dependent bladder tissue regeneration using bilayer bladder acellular matrix graft-silk fibroin scaffolds in a rat bladder augmentation model.

With advances in tissue engineering, various synthetic and natural biomaterials have been widely used in tissue regeneration of the urinary bladder in rat models. However, reconstructive procedures remain insufficient due to the lack of appropriate scaffolding, which should provide a waterproof barrier function and support the needs of various cell types. To address these problems, we have developed a bilayer scaffold comprising a porous network (silk fibroin [SF]) and an underlying natural acellular matrix (bladder acellular matrix graft [BAMG]) and evaluated its feasibility and potential for bladder regeneration in a rat bladder augmentation model. Histological (hematoxylin and eosin and Masson's trichrome staining) and immunohistochemical analyses demonstrated that the bilayer BAMG-SF scaffold promoted smooth muscle, blood vessel, and nerve regeneration in a time-dependent manner. At 12weeks after implantation, bladders reconstructed with the BAMG-SF matrix displayed superior structural and functional properties without significant local tissue responses or systemic toxicity. These results demonstrated that the bilayer BAMG-SF scaffold may be a promising scaffold with good biocompatibility for bladder regeneration in the rat bladder augmentation model.

Isothiocyanate metabolism, distribution, and interconversion in mice following consumption of thermally processed broccoli sprouts or purified sulforaphane.

SCOPE: Broccoli sprouts are a rich source of glucosinolates, a group of phytochemicals that when hydrolyzed, are associated with cancer prevention. Our objectives were to investigate the metabolism, distribution, and interconversion of isothiocyanates (ITCs) in mice fed thermally processed broccoli sprout powders (BSPs) or the purified ITC sulforaphane. METHODS AND RESULTS: For 1 wk, mice were fed a control diet (n = 20) or one of four treatment diets (n = 10 each) containing nonheated BSP, 60°C mildly heated BSP, 5-min steamed BSP, or 3 mmol purified sulforaphane. Sulforaphane and erucin metabolite concentrations in skin, liver, kidney, bladder, lung, and plasma were quantified using HPLC-MS/MS. Thermal intensity of BSP processing had disparate effects on ITC metabolite concentrations upon consumption. Mild heating generally resulted in the greatest ITC metabolite concentrations in vivo, followed by the nonheated and steamed BSP diets. We observed interconversion between sulforaphane and erucin species or metabolites, and report that erucin is the favored form in liver, kidney, and bladder, even when only sulforaphane is consumed. CONCLUSION: ITC metabolites were distributed to all tissues analyzed, suggesting the potential for systemic benefits. We report for the first time tissue-dependent ratio of sulforaphane and erucin, though further investigation is warranted to assess biological activity of individual forms.

Age-related changes in afferent pathways and urothelial function in the male mouse bladder.

The prevalence of lower urinary tract storage disorders such as overactive bladder syndrome and urinary incontinence significantly increase with age. Previous studies have demonstrated age-related changes in detrusor function and urothelial transmitter release but few studies have investigated how the urothelium and sensory pathways are affected. The aim of this study was to investigate the effect of ageing on urothelial-afferent signalling in the mouse bladder. Three-month-old control and 24-month-old aged male mice were used. In vivo natural voiding behaviour, sensory nerve activity, urothelial cell function, muscle contractility, transmitter release and gene and protein expression were measured to identify how all three components of the bladder (neural, contractile and urothelial) are affected by ageing. In aged mice, increased voiding frequency and enhanced low threshold afferent nerve activity was observed, suggesting that ageing induces overactivity and hypersensitivity of the bladder. These changes were concurrent with altered ATP and acetylcholine bioavailability, measured as transmitter overflow into the lumen, increased purinergic receptor sensitivity and raised P2X3 receptor expression in the urothelium. Taken together, these data suggest that ageing results in aberrant urothelial function, increased afferent mechanosensitivity, increased smooth muscle contractility, and changes in gene and protein expression (including of P2X3). These data are consistent with the hypothesis that ageing evokes changes in purinergic signalling from the bladder, and further studies are now required to fully validate this idea.

Delayed exstrophy repair (DER) does not compromise initial bladder development.

OBJECTIVE: Delayed exstrophy repair (DER) represents an alternative to early neonatal bladder closure. This study aims to define the consequence of DER on bladder growth in bladder exstrophy patients who underwent routine DER, compared with those who underwent immediate postnatal reconstruction. METHODS: Between 2000 and 2005, classic bladder exstrophy patients referred to the authors' institution underwent early neonatal bladder closure (group 1). Subsequently, classic bladder exstrophy patients referred to the authors' institution were treated with an elective DER (group 2). Bladder capacity was assessed between the age of 1 and 4 years with an unconscious cystogram. When dilating VUR was present, the volume of the contrast migrated into the ureter was calculated and subtracted. RESULTS: Sixty patients were treated between 2000 and 2012. Complete follow-up data were available for 45 patients and they were included in the study: 21 in group 1 (11 males) and 24 in group 2 (14 males). The mean (SD) bladder volumes were 72.85 (28.5) ml in group 1 and 72.87 (34.9) in group 2 (p = 0.99). CONCLUSION: In the authors' experience, DER does not reduce the subsequent bladder capacities compared with neonatal exstrophy closure.

Nanostructured polyurethane-poly-lactic-co-glycolic acid scaffolds increase bladder tissue regeneration: an in vivo study.

Although showing much promise for numerous tissue engineering applications, polyurethane and poly-lactic-co-glycolic acid (PLGA) have suffered from a lack of cytocompatibility, sometimes leading to poor tissue integration. Nanotechnology (or the use of materials with surface features or constituent dimensions less than 100 nm in at least one direction) has started to transform currently implanted materials (such as polyurethane and PLGA) to promote tissue regeneration. This is because nanostructured surface features can be used to change medical device surface energy to alter initial protein adsorption events important for promoting tissue-forming cell functions. Thus, due to their altered surface energetics, the objective of the present in vivo study was to create nanoscale surface features on a new polyurethane and PLGA composite scaffold (by soaking the polyurethane side and PLGA side in HNO3 and NaOH, respectively) and determine bladder tissue regeneration using a minipig model. The novel nanostructured scaffolds were further functionalized with IKVAV and YIGSR peptides to improve cellular responses. Results provided the first evidence of increased in vivo bladder tissue regeneration when using a composite of nanostructured polyurethane and PLGA compared with control ileal segments. Due to additional surgery, extended potentially problematic healing times, metabolic complications, donor site morbidity, and sometimes limited availability, ileal segment repair of a bladder defect is not optimal and, thus, a synthetic analog is highly desirable. In summary, this study indicates significant promise for the use of nanostructured polyurethane and PLGA composites to increase bladder tissue repair for a wide range of regenerative medicine applications, such as regenerating bladder tissue after removal of cancerous tissue, disease, or other trauma.

Lack of nicotinamide mononucleotide adenylyltransferase 2 (Nmnat2): consequences for mouse bladder development and function.

AIMS: To describe the morphological and functional consequences for bladder development and function when nicotinamide mononucleotide adenylyltransferase 2 (Nmnat2) is lacking or reduced. METHODS: The Bloated Bladder (Blad) mouse, lacking Nmnat2, and heterozygotes were utilized for this investigation. Morphology and development of the bladder were studied using immunohistochemistry against urothelial, smooth muscle, and nerve markers. Functional effects were assessed by organ bath experiments and cystometry. RESULTS: Homozygote mutants were malformed and died at birth, whereas heterozygotes survived and morphologically did not differ from wild-type controls. Morphological bladder changes appeared in the Blad mutants as early as embryonic day 15.5 (E15.5) with an extremely distended bladder at E18.5. Staining revealed that all the bladder layers were present and expressed mature markers in all three genotypes. No nerves could be demonstrated by immunohistochemistry in the Blad mutant bladder at E18.5. Organ bath analysis showed that bladders from Blad mutant showed signs of denervation supersensitivity in response to carbachol, and no response to electrical stimulation of nerves at E18.5. Adult heterozygotes, which have a reduced expression of Nmnat2 at E18.5, showed decreased responses to carbachol and electrical stimulation compared to wild-type controls. The latter also retained their ability to empty their bladders, but showed increased micturition pressures compared to controls. CONCLUSIONS: Complete loss of Nmnat2 leads to a mature but distended bladder in utero and is not compatible with survival. Moderate loss of Nmnat2 has no effect on bladder development, survival, and has only modest effects on bladder function later in life.

Coadministration of platelet-derived growth factor-BB and vascular endothelial growth factor with bladder acellular matrix enhances smooth muscle regeneration and vascularization for bladder augmentation in a rabbit model.

Tissue-engineering techniques have brought a great hope for bladder repair and reconstruction. The crucial requirements of a tissue-engineered bladder are bladder smooth muscle regeneration and vascularization. In this study, partial rabbit bladder (4×5 cm) was removed and replaced with a porcine bladder acellular matrix (BAM) that was equal in size. BAM was incorporated with platelet-derived growth factor-BB (PDGF-BB) and vascular endothelial growth factor (VEGF) in the experimental group while with no bioactive factors in the control group. The bladder tissue strip contractility in the experimental rabbits was better than that in the control ones postoperation. Histological evaluation revealed that smooth muscle regeneration and vascularization in the experimental group were significantly improved compared with those in the control group (p<0.05), while multilayered urothelium was formed in both groups. Muscle strip contractility of neobladder in the experimental group exhibited significantly better than that in the control (p<0.05) assessed with electrical field stimulation and carbachol interference. The activity of matrix metalloproteinase-2 (MMP-2) and MMP-9 in the native bladder tissue around tissue-engineered neobladder in the experimental group was significantly higher than that in the control (p<0.05). This work suggests that smooth muscle regeneration and vascularization in tissue-engineered neobladder and recovery of bladder function could be enhanced by PDGF-BB and VEGF incorporated within BAM, which promoted the upregulation of the activity of MMP-2 and MMP-9 of native bladder tissue around the tissue-engineered neobladder.

Characterization of the early proliferative response of the rodent bladder to subtotal cystectomy: a unique model of mammalian organ regeneration.

Subtotal cystectomy (STC; surgical removal of ∼75% of the rat urinary bladder) elicits a robust proliferative response resulting in complete structural and functional bladder regeneration within 8-weeks. The goal of these studies was to characterize the early cellular response that mediates this regenerative phenomenon, which is unique among mammalian organ systems. STC was performed on eighteen 12-week-old female Fischer F344 rats. At 1, 3, 5 and 7-days post-STC, the bladder was harvested 2-hours after intraperitoneal injection of bromodeoxyuridine (BrdU). Fluorescent BrdU labeling was quantified in cells within the urothelium, lamina propria (LP), muscularis propria (MP) and serosa. Cell location was confirmed with fluorescently co-labeled cytokeratin, vimentin or smooth muscle actin (SMA), to identify urothelial, interstitial and smooth muscle cells, respectively. Expression of sonic hedgehog (Shh), Gli-1 and bone morphogenic factor-4 (BMP-4) were evaluated with immunochemistry. Three non-operated rats injected with BrdU served as controls. Less than 1% of cells in the bladder wall were labeled with BrdU in control bladders, but this percentage significantly increased by 5-8-fold at all time points post-STC. The spatiotemporal characteristics of the proliferative response were defined by a significantly higher percentage of BrdU-labeled cells within the urothelium at 1-day than in the MP and LP. A time-dependent shift at 3 and 5-days post-STC revealed significantly fewer BrdU-labeled cells in the MP than LP or urothelium. By 7-days the percentage of BrdU-labeled cells was similar among urothelium, LP and MP. STC also caused an increase in immunostaining for Shh, Gli-1 and BMP-4. In summary, the early stages of functional bladder regeneration are characterized by time-dependent changes in the location of the proliferating cell population, and expression of several evolutionarily conserved developmental signaling proteins. This report extends previous observations and further establishes the rodent bladder as an excellent model for studying novel aspects of mammalian organ regeneration.

Delayed primary repair of bladder exstrophy: ultimate effect on growth.

PURPOSE: Late referrals or unsuitable bladder templates often require delayed primary repair of bladder exstrophy. We investigated longitudinal bladder growth rates and eventual outcomes following this approach. MATERIALS AND METHODS: After institutional review board approval, we reviewed the medical records of patients with classic bladder exstrophy who underwent neonatal or delayed (more than 30 days) primary closure at our institution between 1970 and 2006. Clinical characteristics and annual cystographic bladder capacity before the continence procedure were compared. Failed primary exstrophy repairs were excluded. RESULTS: A total of 33 patients with available bladder capacity measurements underwent delayed exstrophy closure due to small bladder template in 18 (88% male) and late referral in 15 (80% male) at respective median ages of 305 days (range 86 to 981) and 172 days (31 to 676). They were compared to 82 patients (71% male) undergoing neonatal closure at a median of 2 days of life (range 0 to 27). Pelvic osteotomy was performed in 32 of 33 delayed closures. Longitudinal analysis of the bladder capacities demonstrated that, compared to neonatally closed cases, bladder capacities were on average 36 ml smaller in those with delayed repair due to small templates (p = 0.01) and 29 ml smaller in those with late referrals (p = 0.13). However, the rate of bladder growth did not differ significantly among the 3 groups. CONCLUSIONS: Delayed primary repair of exstrophy does not compromise the rate of bladder growth. However, children born with smaller templates will have overall smaller capacities and are less likely to undergo bladder neck reconstruction.

Transcriptional and translational plasticity in rodent urinary bladder TRP channels with urinary bladder inflammation, bladder dysfunction, or postnatal maturation.

These studies examined the transcriptional and translational plasticity of three transient receptor potential (TRP) channels (TRPA1, TRPV1, TRPV4) with established neuronal and non-neuronal expression and functional roles in the lower urinary tract. Mechanosensor and nociceptor roles in either physiological or pathological lower urinary tract states have been suggested for TRPA1, TRPV1, and TRPV4. We have previously demonstrated the neurochemical, organizational, and functional plasticity in micturition reflex pathways following induction of urinary bladder inflammation using the antineoplastic agent, cyclophosphamide. More recently, we have characterized similar plasticity in micturition reflex pathways in a transgenic mouse model with chronic urothelial overexpression (OE) of nerve growth factor (NGF) and in a transgenic mouse model with deletion of vasoactive intestinal polypeptide (VIP). In addition, the micturition reflex undergoes postnatal maturation that may also reflect plasticity in urinary bladder TRP channel expression. Thus, we examined plasticity in urinary bladder TRP channel expression in diverse contexts using a combination of quantitative, real-time PCR and western blotting approaches. We demonstrate transcriptional and translational plasticity of urinary bladder TRPA1, TRPV1, and TRVP4 expression. Although the functional significance of urinary bladder TRP channel plasticity awaits further investigation, these studies demonstrate context- (inflammation, postnatal development, NGF-OE, VIP deletion) and tissue-dependent (urothelium + suburothelium, detrusor) plasticity.

Urinary bladder function in conscious rat pups: a developmental study.

Cystometric studies of bladder function in anesthetized neonatal rats have suggested specific changes in urodynamic parameters that coincide with the development of a mature bladder-to-bladder micturition reflex. Here, we used a conscious cystometry model that avoids the potentially confounding effects of anesthesia to characterize voiding patterns and urodynamic parameters during early postnatal development in healthy rat pups. Cystometry was performed on postnatal day (P)0, 3, 7, 14, and 21 rats with continuous intravesical instillation of NaCl via a bladder catheter. Micturition cycles were analyzed with respect to voiding pattern, nonvoiding contractions, infused volume, and basal, filling, threshold, and micturition pressures. Reproducible micturition patterns were obtained from all age groups. The time from stimulation to contraction was significantly longer (P ≤ 0.001) in ≤1-wk-old rats (∼10 s) than that in older rats (∼3 s). An interrupted voiding pattern was observed in ≤10-day-old subgroups. Micturition pressure progressively increased with age (from 21.77 ± 1.92 cmH(2)O at P0 to 35.47 ± 1.28 cmH(2)O at P21, P ≤ 0.001), as did bladder capacity. Nonvoiding contractions were prominent in the P3 age group (amplitude: 4.6 ± 1.3 cmH(2)O, frequency: ∼4.0 events/100 s). At P7, the pattern of spontaneous contractions became altered, acquiring a volume-related character that persisted in a less prominent manner through P21. Bladder compliance increased with age, i.e., maturation. In conclusion, conscious cystometry in rat pups resulted in reproducible micturition cycles that yielded consistent data. Our results revealed immature voiding and prolonged micturition contractions during the first 10 neonatal days and provide evidence for age-related changes in urodynamic parameters.