Automated noninvasive measurement of cyclophosphamide-induced changes in murine voiding frequency and volume

Lack of expression of miR-29a/b1 impairs bladder function in male mice

Lower urinary tract symptoms (LUTS) refer to various urological diseases, and incomplete bladder emptying is common among affected patients. The etiology of LUTS is largely unknown, and investigations of LUTS suggest that bladder fibrosis contributes to pathogenesis of LUTS. MicroRNAs (miRNAs) are short (∼22 nucleotides), non-coding RNAs that repress target gene expression by a combination of mRNA degradation and translation inhibition. The miR-29 family is best known for its anti-fibrotic role in various organs. miR-29 was decreased in bladders of patients with outlet obstruction and a rat model of bladder outlet obstruction, suggesting that miR-29 may contribute to impaired bladder function subsequent to tissue fibrosis. We characterized bladder function in male mice lacking expression of Mir29a and Mir29b-1 (miR-29a/b1). Lack of miR-29a/b1 resulted in severe urinary retention, increased voiding duration and reduced flow rate, and these mice failed to void or voided irregularly during anesthetized cytometry. Collagens and elastin were increased in bladders of mice lacking miR-29a/b1. These findings reveal an important role for miR-29 in bladder homeostasis and suggest the therapeutic potential of miR-29 to improve symptoms in patients with LUTS.

Bladder outlet obstruction disrupts circadian bladder function in mice

The circadian clock programs daily rhythms and coordinates multiple behavioural processes, including micturition. Partial bladder outlet obstruction (pBOO) in mice produces hyperactive voiding. However, long-term effects of pBOO on bladder function have not been clarified. In this study, we investigated micturition under conditions of impaired circadian bladder function by inducing long-term pBOO by tying the proximal urethra. Micturition behavior was evaluated at 1, 3, 6 and 12 months after surgery. We used automated voided stain on paper method for a precise micturition recording for mice. And quantitative assessment of gene expression was performed at 24 months after pBOO surgery using qRT-PCR procedure. The micturition frequencies in the pBOO group were significantly decreased at 3, 6, and 12 months compared to those at 1 month after operation in the same group (p < 0.05). Body weight of pBOO mice was significantly increased compared to sham operated mice at 12 months. The expression level of mRNA was exhibited a 3.4-fold nominal increased for a 5-HT2B receptor in the pBOO group compared to the sham group. The current study found that long-term pBOO led to disruption of the circadian bladder function (the day/night cycle) in mice, similar to those observed in human as nocturia. This disruption is possible involvement of the gain of body weight and/or serotonergic alteration after pBOO.

High-definition ultrasound characterization of acute cyclophosphamide-induced cystitis in the mouse

Purpose

To examine associations if any between changes in voiding function, hematuria, and bladder ultrasonography metrics in murine cyclophosphamide-induced chemical cystitis.

Materials and Methods

Cystitis was induced in 6 female mice by an intraperitoneal injection of cyclophosphamide (300 mg/kg). Voiding frequency, void volume, hematuria assessment, and ultrasonographic measurements of the bladder were obtained at baseline, days 1 to 5, and days 9, 11, and 13. Voiding was induced with preferred sweet drinking solution and voiding data collected using an automated data collection system in 135 minute sessions. Bladder wall thickness, lumen volume, and vascular Doppler were acquired using a high definition ultrasound system. Spearman's correlation was used to analyze the association between the voiding changes, hematuria, and ultrasound findings.

Results

Hematuria was present 24 hours after cyclophosphamide injection. All animals displayed increased bladder vascularity, bladder wall thickness, and void frequency that was associated with concurrent decreased total and average void volumes. Increased bladder wall vascularity was correlated with the presence of hematuria (r=0.59, p<0.01) and bladder wall thickness (r=0.79, p<0.01). Hematuria correlated with increased void frequency (r=0.34, p<0.01). Average void volume was negatively correlated with hematuria (r=−0.50, p<0.01) and frequency (r=−0.38, p<0.01).

Conclusions

High-definition ultrasound imaging permits in vivo monitoring of changes in bladder morphology associated with voiding function in relation to cyclophosphamide-induced cystitis. Ultrasound imaging of the bladder may assist in differential diagnosis of bladder dysfunction.

Non-invasive voiding assessment in conscious mice

OBJECTIVE

To review available options of assessing murine bladder function and to evaluate a non-invasive technique suitable for long-term recording.

METHODS

We reviewed previously described methods to record rodent bladder function. We used modified metabolic cages to capture novel recording tracings of mouse micturition. We evaluated our method in a pilot study with female mice undergoing partial bladder outlet obstruction or sham operation, respectively; half of the partial obstruction and sham group received treatment with an S6K-inhibitor, targeting the mTOR pathway, which is known to be implicated in bladder response to obstruction.

RESULTS

Our non-invasive method using continuous urine weight recording reliably detected changes in murine bladder function resulting from partial bladder outlet obstruction or treatment with S6K-inhibitor. We found obstruction as well as treatment with S6K-inhibitor to correlate with a hyperactive voiding pattern.

CONCLUSIONS

While invasive methods to assess murine bladder function largely disturb bladder histology and intrinsically render post-cystometry gene expression analysis of questionable value, continuous urine weight recording is a reliable, inexpensive, and critically non-invasive method to assess murine bladder function, suitable for a long-term application.

Evaluating the voiding spot assay in mice: a simple method with complex environmental interactions

The voiding spot assay (VSA) on filter paper is an increasingly popular method for studying lower urinary tract physiology in mice. However, the ways VSAs are performed differ significantly between laboratories, and many variables are introduced compared with the mouse's normal housing situation. Rodents are intelligent social animals, and it is increasingly understood that social and environmental stresses have significant effects on their physiology. Surprisingly, little is known about whether change of environment during VSA affects mouse voiding and what the best methodologies are for retaining "natural" micturition patterns. It is well known that stress-related neuropeptide corticotropin-releasing factor is significantly elevated and induces dramatic voiding changes when rodents encounter stresses. Therefore we hypothesized that changes in the environmental situation could potentially alter voiding during VSA. We have examined multiple factors to test whether they affect female mouse voiding patterns during VSA, including cage type, cage floor, water availability, water bottle location, single or group housing, and different handlers. Our results indicate that mice are surprisingly sensitive to changes in cage type and floor surface, water bottle location, and single/group housing, each of which induces significant changes in voiding patterns, indicative of a stress response. In contrast, neither changing handler nor 4 h of water deprivation affected voiding patterns. Our data indicate that VSA should be performed under conditions as close as possible to the mouse's normal housing. Optimizing VSA methodology will be useful in uncovering voiding alterations in both genetic and disease models of lower urinary dysfunctions.

Trpm7 Protein Contributes to Intercellular Junction Formation in Mouse Urothelium

Trpm7 is a divalent cation-permeable channel that has been reported to be involved in magnesium homeostasis as well as cellular adhesion and migration. We generated urothelium-specific Trpm7 knock-out (KO) mice to reveal the function of Trpm7 in vivo. A Trpm7 KO was induced by tamoxifen and was confirmed by genomic PCR and immunohistochemistry. By using patch clamp recordings in primary urothelial cells, we observed that Mg(2+)-inhibitable cation currents as well as acid-inducible currents were significantly smaller in Trpm7 KO urothelial cells than in cells from control mice. Assessment of voiding behavior indicated a significantly smaller voided volume in Trpm7 KO mice (mean voided volume 0.28 ± 0.08 g in KO mice and 0.36 ± 0.04 g in control mice, p < 0.05, n = 6-8). Histological analysis showed partial but substantial edema in the submucosal layer of Trpm7 KO mice, most likely due to inflammation. The expression of proinflammatory cytokines TNF-α and IL-1β was significantly higher in Trpm7 KO bladders than in controls. In transmission electron microscopic analysis, immature intercellular junctions were observed in Trpm7 KO urothelium but not in control mice. These results suggest that Trpm7 is involved in the formation of intercellular junctions in mouse urothelium. Immature intercellular junctions in Trpm7 knock-out mice might lead to a disruption of barrier function resulting in inflammation and hypersensitive bladder afferent nerves that may affect voiding behavior in vivo.

Changes in voiding behavior in a mouse model of Alzheimer's disease

Besides cognitive decline and behavioral alteration, urinary incontinence often occurs in patients suffering from Alzheimer's disease (AD). To determine whether the transgenic mouse model of AD, APP/PS1 (APP(SL)/PS1(M146L)) mouse, shows alteration of the urinary bladder function and anxiety, as for patients with AD, we examined the urinary marking behavior in relation to affective behavior. At 18 months of age voiding behavior of APP/PS1 and wild type (WT) mice was assessed by using a modified filter paper assay in combination with video tracing, with the cage divided into a center and corner zones. Anxiety-related behavior and locomotion were respectively tested in an elevated zero maze (EZM) and an open field (OF). The APP/PS1 mice urinated more in the center zone than the WT mice. The total volume of markings was significantly lower in the APP/PS1 mice. In both groups, the average volume of a marking in the corner zone was larger than in the center zone. In the EZM, the APP/PS1 mice spent less time in the open arms of the arena, considered as anxiogenic zones, than the WT mice. During the OF task, the APP/PS1 mice covered a longer distance than the WT mice. These findings show that the APP/PS1 mice have a different voiding behavior compared to the WT mice, i.e., urinating with small volumes and voiding in the center of the cage, and suggest that increased locomotor activity and anxiety-related behaviors are factors in the change in voiding pattern in the APP/PS1 mouse.

Inhibition of nitric oxide synthase prevents muscarinic and purinergic functional changes and development of cyclophosphamide-induced cystitis in the rat

Nitric oxide (NO) has pivotal roles in cyclophosphamide- (CYP-) induced cystitis during which mucosal nitric oxide synthase (NOS) and muscarinic M5 receptor expressions are upregulated. In cystitis, urothelial muscarinic NO-linked effects hamper contractility. Therefore we wondered if a blockade of this axis also affects the induction of cystitis in the rat. Rats were pretreated with saline, the muscarinic receptor antagonist 4-DAMP (1 mg/kg ip), or the NOS inhibitor L-NAME (30 mg/kg ip) for five days. 60 h before the experiments the rats were treated with saline or CYP. Methacholine-, ATP-, and adenosine-evoked responses were smaller in preparations from CYP-treated rats than from saline-treated ones. Pretreatment with 4-DAMP did not change this relation, while pretreatment with L-NAME normalized the responses in the CYP-treated animals. The functional results were strengthened by the morphological observations; 4-DAMP pretreatment did not affect the parameters studied, namely, expression of muscarinic M5 receptors, P1A1 purinoceptors, mast cell distribution, or bladder wall enlargement. However, pretreatment with L-NAME attenuated the differences. Thus, the current study provides new insights into the complex mechanisms behind CYP-induced cystitis. The NO effects coupled to urothelial muscarinic receptors have a minor role in the development of cystitis. Inhibition of NOS may prevent the progression of cystitis.

Effects of Saw Palmetto Extract on Urodynamic Parameters, Bladder Muscarinic and Purinergic Receptors and Urinary Cytokines in Rats with Cyclophosphamide-Induced Cystitis

OBJECTIVES

To clarify the effect of saw palmetto extract (SPE), a phytotherapeutic agent, on urodynamic parameters, bladder muscarinic and purinergic receptors, and urinary cytokines in rats with cystitis induced by cyclophosphamide (CYP).

METHODS

Saw palmetto extract (60 mg/kg per day) was administered orally twice a day for 7 days to rats. The urodynamic parameters in CYP (150 mg/kg i.p.)-treated rats were monitored by a cystometric method under anesthesia. The muscarinic and purinergic receptors in the bladder and submaxillary gland were measured by radioreceptor assays using [N-methyl-(3) H] scopolamine chloride([(3) H]NMS) and αβ-methylene-ATP [2,8-(3) H] tetrasodium salt ([(3) H]αβ-MeATP), respectively. Urinary cytokines (interleukin-1β [IL-1β], IL-6 and L-17) were measured with enzyme linked immunosorbent assay kits.

RESULTS

Micturition interval and micturition volume were significantly decreased and the frequency of micturition and basal pressure were significantly increased in the CYP-treated rats compared with sham-operated rats. Orally administered SPE significantly increased the micturition interval and micturition volume and decreased the frequency of micturition and basal pressure. The maximal number of sites (Bmax ) for the specific binding of [(3) H]NMS and [(3) H]αβ-MeATP was significantly decreased in the bladder. The decrease in receptors was attenuated by repeated treatment with SPE. An elevation in urinary cytokine (IL-1β and IL-17) levels were seen, and this increase was effectively suppressed by SPE treatment.

CONCLUSIONS

Saw palmetto extract attenuates the alteration of urodynamic parameters, pharmacologically relevant receptors, and urinary cytokines in CYP-treated rats. Therefore, SPE may be a potential therapeutic agent for improving the clinical symptoms of cystitis.

Involvement of urinary bladder Connexin43 and the circadian clock in coordination of diurnal micturition rhythm

Nocturnal enuresis in children and nocturia in the elderly are two highly prevalent clinical conditions characterized by a mismatch between urine production rate in the kidneys and storage in the urinary bladder during the sleep phase. Here we demonstrate, using a novel method for automated recording of mouse micturition, that connexin43 (Cx43), a bladder gap junction protein, is a negative regulator of functional bladder capacity. Bladder Cx43 levels and functional capacity show circadian oscillations in wild-type mice, but such rhythms are completely lost in Cry-null mice having a dysfunctional biological clock. Bladder muscle cells have an internal clock, and show oscillations of Cx43 and gap junction function. A clock regulator, Rev-erbα, upregulates Cx43 transcription as a co-factor of Sp1 using Sp1 cis-elements of the promoter. Therefore, circadianoscillation of Cx43 is associated with the biological clock and contributes to diurnal changes in bladder capacity, which avoids disturbance of sleep by micturition.

Local activation of cannabinoid CB₁ receptors in the urinary bladder reduces the inflammation-induced sensitization of bladder afferents

Background

Systemic administration of cannabinoid agonists is known to reduce pain induced by bladder inflammation and to modulate cystometric parameters in vivo. We have previously reported that intravesical administration of a cannabinoid agonist reduces the electrical activity of bladder afferents under normal conditions. However, the effects of local activation of bladder cannabinoid receptors on afferent activity during inflammation are unknown. This study was aimed to assess the effects of intravesical administration of a cannabinoid agonist on the discharges of afferent fibers in inflamed bladders ex vivo. We also characterized the expression of CB₁ receptors in the bladder and their localization and co-expression with TRPV1, a marker of nociceptive afferents.

Results

Compared to untreated animals, afferent fiber activity in inflamed bladders was increased for intravesical pressures between 10 and 40 mmHg. Local treatment with a non selective cannabinoid agonist (AZ12646915) significantly reduced the afferent activity at intravesical pressures above 20 mmHg. This effect was blocked by AM251 but not by AM630 (selective for CB₁ and CB₂ respectively). Finally, CB₁ was co-expressed with TRPV1 in control and inflamed bladders.

Conclusion

These results demonstrate that sensitization of bladder afferents induced by inflammation is partly suppressed by intravesical activation of cannabinoid receptors, an effect that appears to be mediated by CB₁ receptors. Also, TRPV1 positive fibers were found to co-express CB₁, supporting the hypothesis of a direct action of the cannabinoid agonist on nociceptive afferents. Taken together, these results indicate a peripheral modulation by the cannabinoid system of bladder hypersensitivity during inflammation.

Urodynamic measurements by radiotelemetry in conscious, freely moving beagle dogs

PURPOSE

Urodynamics have been traditionally recorded in anesthetized or conscious animals implanted with a bladder catheter that is used to artificially fill the bladder while measuring intravesicular bladder pressure. Anesthesia alters the urodynamics and in the conscious state this methodology requires that the dogs be tethered/restrained, which evokes stress and limits the period of continuous urodynamic assessment. A more physiological and chronic method of evaluating pharmacological responses on urodynamics is necessary.

MATERIALS AND METHODS

Adult female beagle dogs were surgically instrumented with radiotelemetry transmitters enabling urodynamic/hemodynamic recordings. Telemetered urodynamics were compared to those measured in anesthetized dogs receiving bladder infusion of saline. The response to diuresis with furosemide (Intervet, Millsboro, Delaware) and the M3 selective antimuscarinic darifenacin (Matrix Laboratories, Hyderabad, India) were evaluated.

RESULTS

Saline infused, anesthetized dogs demonstrated lower peak micturition pressure and higher threshold pressure than conscious, freely moving telemetered dogs. In telemetered dogs a single dose of furosemide increased voiding frequency and average urine volume per void. Darifenacin decreased peak voiding pressure without affecting voiding frequency.

CONCLUSION

Telemetry provides the potential to significantly decrease animal use while enabling the continuous monitoring of urodynamics under more physiological conditions without tethering or artificial filling. In addition, this new model facilitates evaluation of the chronic efficacy of new urological therapies.

Multiplex analysis of urinary cytokine levels in rat model of cyclophosphamide-induced cystitis

OBJECTIVES

The urinary proteome is a potential easily accessible source of biomarkers for inflammatory bladder diseases, including interstitial cystitis. In the present study, we subjected rat urine to multiplex cytokine analysis in an attempt to identify an inflammatory signature of the temporal course of cyclophosphamide (CYP)-induced cystitis.

METHODS

Rat urine was collected for 12 hours after CYP injection (150 mg/kg) for multiplex analysis of 14 cytokines by a multiple antigen bead assay (Luminex 100 IS). Urine from each void was collected, and the voiding frequency was determined. The bladder tissue was analyzed for cytokines levels and histologic evidence of inflammation.

RESULTS

Significant changes were noted in the urine levels of all cytokines with respect to baseline at 2, 4, 6, and 10 hours after CYP injection. Elevation was noted at all times for most cytokines, except for monocyte chemotactic protein-1, which had a 5-fold decrease at 2 hours. The urine and tissue levels of interleukin (IL)-1beta, IL-4, and growth-related oncogene/keratinocyte-derived chemokine correlated significantly, with a positive Spearman correlation also noted for granulocyte-macrophage colony-stimulating factor, monocyte chemotactic protein-1-1, IL-18, and interferon-gamma. The tissue levels for most cytokines, except for IL-2, and urinary frequency were significantly elevated in the CYP-treated rats compared with the control vehicle-treated rats. The hints of severe inflammation in the bladder indicated by the urinary cytokines were confirmed by bladder histologic examination and the tissue cytokine levels at necropsy.

CONCLUSIONS

The progression of CYP-induced cystitis was clearly reflected in the urine matrix by the temporal and quantitative changes in the cytokine levels. Additional delineation of urine and bladder tissue cytokine expression might yield biomarkers for cystitis.

Acute acrolein-induced cystitis in mice

OBJECTIVE

To develop a method of direct intravesical administration of acrolein and evaluate the severity of cystitis in response to increasing doses of acrolein in female C57BL/6N (C57) mice, with further studies to compare the severity of acute acrolein-induced cystitis among C57, C3H/HeJ (HeJ), and C3H/OuJ (OuJ) strains of mice, as chemical cystitis produced by the systemic administration of cyclophosphamide is thought to result from renal excretion of hepatic metabolites, particularly acrolein.

MATERIALS AND METHODS

Doses of acrolein (0-1000 microg, 15 microL total volume) were instilled into the bladders of C57 female mice; the bladders were removed 4 or 24 h later, weighed, and processed for histology. Acrolein (6 or 10 microg; 15 microL) was instilled into the bladders of C57, HeJ and OuJ female mice, the bladders removed 4 or 24 h later, weighed, and processed for standard histology and immunohistochemical detection of uroplakin.

RESULTS

Increasing doses of acrolein up to 100-200 microg caused a linear increase in bladder weight and greater histological evidence of inflammation. Doses of >200 microg caused submaximal increases in bladder weight, apparently due to structural damage of the bladder. Bladder weight and submucosal oedema were consistently greater in C57 and HeJ than OuJ mice. Treatment with acrolein caused loss of urothelium along with uroplakin in some areas of all bladder sections 4 h after treatment. Bladders from C57 mice had some loss of urothelium 24 h after instillation of 6 or 10 microg acrolein, but urothelium and uroplakin covered nearly all the surface of bladders of HeJ and OuJ mice 24 h after treatment. There were significantly more white blood cells in bladders from C57 or HeJ mice than in bladders from OuJ mice 24 h after an instillation of 6 or 10 microg acrolein.

CONCLUSIONS

Intravesical instillation of acrolein produces dose-dependent cystitis in mice. OuJ mice appear relatively more resistant to irritant effects of intravesical acrolein than C57 or HeJ mice, and future studies will be directed at identifying genetic causes for these differences.

Initial observations of reduced uroflow in transgenic adenocarcinoma of murine prostate

OBJECTIVES

To characterize the voiding function in a transgenic adenocarcinoma of murine prostate (TRAMP) mouse of advanced age, because it might provide a useful model of slow-onset bladder outlet obstruction. Spontaneous death from urinary outlet obstruction occurs in the TRAMP mouse.

METHODS

A metabolic cage without a fecal separation screen was placed above a precision balance that reported the mass of the excreta pan every 100 ms. A computational algorithm identified voids suitable for uroflow assessment from other excretory events. A series of images were obtained automatically before and during the excretory events.

RESULTS

The TRAMP mouse displayed a pulsatile voiding pattern characterized by a reduction in uroflow, prolongation of voiding, and droplet formation at the tip of the prepuce. Postmortem histologic examination revealed gross enlargement of the prostate, a suburethral tumor, dilation of the lumen of the urethra, and proteinaceous debris in the urethra and bladder.

CONCLUSIONS

The observed changes were consistent with urethral obstruction induced by prostate enlargement and/or suburethral tumor. Additional studies are required to ascertain whether prostate enlargement per se is sufficient to produce urethral obstruction in the TRAMP mouse. This transgenic mouse strain may provide a model of slow-onset outlet obstruction that is more representative of bladder outlet obstruction caused by benign prostatic hyperplasia than is the obstruction produced by urethral ligation.

Early detection and measurement of urothelial tumors in mice

OBJECTIVES

To establish reliable noninvasive in vivo methods to detect, measure, and monitor experimentally induced urothelial tumors in mice.

METHODS

UPII-SV40T transgenic mice reliably develop bladder tumors by expression of simian virus 40 large T antigen specifically in bladder urothelium through the use of the uroplakin II promoter. Two wild-type and 10 UPII-SV40T transgenic mice were monitored for microhematuria two to three times weekly using dipstick analysis. A unique flat panel detector-based cone beam computed tomography (FPD-CBCT) system imaged the urinary tracts of anesthetized mice after tail vein injection of an iodinated contrast agent (Omnipaque) that is excreted in urine. Within 10 seconds, the FPD-CBCT system acquired 290 two-dimensional images, which produced three-dimensional volumes with true isotropic resolution (180 microm)3 using a filtered back projection-based modified Feldkamp reconstruction algorithm. Amira, version 3.1.1-1, for MacOSX was used for data analysis and advanced visualization of the three-dimensional reconstructed FPD-CBCT images.

RESULTS

Hematuria was present in UPII-SV40T transgenic mice at 32 days of age; the wild-type animals exhibited no hematuria. Filling defects, associated with histologically confirmed tumors, in the bladders of the UPII-SV40T transgenic mice were visualized in the reconstructed FPD-CBCT images 1 to 45 minutes after contrast agent injection. Longitudinal FPD-CBCT imaging sessions showed the tumor position, volume, and growth.

CONCLUSIONS

The combination of early detection of hematuria and high-resolution in vivo FPD-CBCT imaging of murine bladder tumors enabled accurate longitudinal assessment of tumor growth and progression in individual animals. This approach could provide an important alternative to serial sacrifice experimental designs, while refining statistical power and reducing animal use.

Peptidergic sensory and parasympathetic fiber sprouting in the mucosa of the rat urinary bladder in a chronic model of cyclophosphamide-induced cystitis

In this study, we used a well-established animal model to investigate changes in the peptidergic and parasympathetic innervation of the bladder following chronic bladder inflammation. Adult female Sprague-Dawley rats were injected with either 70 mg/kg cyclophosphamide diluted in saline, i.p., once every 3 days or saline. After 10 days, all animals were tested for urinary frequency and number of low volume voids, as well as symptoms of spontaneous pain. At the end of 12 days, all animals were perfused with histological fixatives and the urinary bladders processed for immunofluorescence using antibodies against calcitonin gene-related peptide and the vesicular acetylcholine transporter as markers, respectively, of peptidergic primary afferent fibers and parasympathetic efferent fibers. We show that animals treated with cyclophosphamide had inflamed bladders and displayed high urinary frequency as well as some indicators of spontaneous pain, such as piloerection and a rounded-back posture. Furthermore, they had a significant increase in the density of both parasympathetic and peptidergic sensory fibers in the bladder mucosa and an increase in peptidergic sensory fibers in the detrusor muscle. Based on these results, we suggest that peripheral sprouting of parasympathetic and peptidergic fibers could be a mechanism responsible for sensitization of the bladder, leading to urinary symptoms. Since we observed that the parasympathetic and peptidergic fibers often wrapped around one another and that their varicosities were very close, these two fiber populations may be interacting with each other to lead to and maintain sensitization. Future studies are required to establish the role of this fiber sprouting in bladder symptoms.

Peptidergic sensory and parasympathetic fiber sprouting in the mucosa of the rat urinary bladder in a chronic model of cyclophosphamide-induced cystitis

In this study, we used a well-established animal model to investigate changes in the peptidergic and parasympathetic innervation of the bladder following chronic bladder inflammation. Adult female Sprague-Dawley rats were injected with either 70 mg/kg cyclophosphamide diluted in saline, i.p., once every 3 days or saline. After 10 days, all animals were tested for urinary frequency and number of low volume voids, as well as symptoms of spontaneous pain. At the end of 12 days, all animals were perfused with histological fixatives and the urinary bladders processed for immunofluorescence using antibodies against calcitonin gene-related peptide and the vesicular acetylcholine transporter as markers, respectively, of peptidergic primary afferent fibers and parasympathetic efferent fibers. We show that animals treated with cyclophosphamide had inflamed bladders and displayed high urinary frequency as well as some indicators of spontaneous pain, such as piloerection and a rounded-back posture. Furthermore, they had a significant increase in the density of both parasympathetic and peptidergic sensory fibers in the bladder mucosa and an increase in peptidergic sensory fibers in the detrusor muscle. Based on these results, we suggest that peripheral sprouting of parasympathetic and peptidergic fibers could be a mechanism responsible for sensitization of the bladder, leading to urinary symptoms. Since we observed that the parasympathetic and peptidergic fibers often wrapped around one another and that their varicosities were very close, these two fiber populations may be interacting with each other to lead to and maintain sensitization. Future studies are required to establish the role of this fiber sprouting in bladder symptoms.

Mechanism of action by which aspirin alleviates detrusor hyperactivity in rats

We examined the effect of aspirin on urodynamic parameters in normal and cyclophosphamide-induced cystitic rats and compared them in rats with or without sensory denervation. Cystometry was performed under urethane anesthesia; and volume threshold for micturition (VT), micturition frequency (MF), micturition pressure (MP), and micturition volume (MV) were determined. Cystitis was induced by pretreatment with cyclophosphamide and sensory denervation was performed by pretreating animals with a large dose of capsaicin. PGE(2) and 6-keto-PGF(1alpha) contents in the bladder were determined by ELISA. Sensory intact, cystitic rats showed decrement of VT and increment of MF. Aspirin increased VT and decreased MF in the cystitic condition. Both PGE(2) and 6-keto-PGF(1alpha) contents in the bladder were significantly increased in cystitic rats, but such increases were completely inhibited by aspirin. In sensory denervated rats, aspirin showed a marginal tendency of increment of VT. Cystitic rats showed overflow micturition in the sensory denervated condition, but VT was the same as that of normal rats. Furthermore, following capsaicin pretreatment, aspirin had no effect on the cystometrogram in cystitic rats. From these findings, it is concluded that suppression of sensory C-fiber via inhibition of PGs synthesis in the bladder is involved in the pharmacological action of aspirin in the detrusor hyperactivity.

Uroflow in murine urethritis

OBJECTIVES

To develop a noninvasive method to measure urinary flow rate in the mouse. This could be useful for the study of bladder outlet obstruction, as well as processes affecting detrusor function in the awake animal. Genetically engineered mice can improve our understanding of a variety of human bladder diseases.

METHODS

A metabolic cage without a fecal separation screen was placed above a precision balance that reported the mass of the excreta pan every 100 ms. A computational algorithm identified voids suitable for assessment of uroflow from other excretory events. These algorithms were verified by comparison with a series of images obtained automatically before and during the excretory events. Intraurethral acetic acid was used to induce urethritis and to verify the sensitivity of the measurement technique.

RESULTS

Automatic categorization and characterization of uroflow was successful. Brief exposures of the urethra of the female C57BL6/J mouse to 2% acetic acid decreased uroflow and increased the void duration without a change in the voided volume.

CONCLUSIONS

This method will enable studies of urologic function in mice of differing age, sex, strain, and genetic constitution. Murine urethritis can be differentiated from cystitis, known to be associated with a decrease in voided volume. The observed changes were consistent with urethral obstruction induced by local swelling and inflammation.

Up-regulation of phosphorylated CREB but not c-Jun in bladder afferent neurons in dorsal root ganglia after cystitis

We examined the changes of two transcription factors, CREB and c-Jun, in dorsal root ganglia (DRG) after acute (8 or 48 hours) or chronic (10 days) cyclophosphamide (CYP)-induced cystitis. Results showed an increase in the number of p-CREB-immunoreactive (-IR) cells in the L1 and L2 DRG (5-7-fold; P < or = 0.05) as well as L6 and S1 DRG (2-4-fold; P < or = 0.05) after acute and chronic cystitis. The number of p-CREB-IR cells in the L4-L5 DRG was not altered with cystitis. The number of c-Jun-IR cells increased in the L1-L2 DRG (L1: 10-fold; L2: 8-fold; P < or = 0.05) only with chronic cystitis, although it increased in the L6-S1 DRG with CYP-induced cystitis of acute (2-3-fold; P < or = 0.05) and chronic (6-10-fold; P < or = 0.05) duration. After CYP treatment, the percentage of bladder afferent cells expressing p-CREB immunoreactivity (3-7-fold; P < or = 0.05) increased in L1, L2, L6, and S1 DRG. The increase occurred 8 hours post-CYP injection and was maintained with chronic cystitis. There were few c-Jun-IR cells in the bladder afferent population. These results demonstrate that CYP induces p-CREB and c-Jun expression in DRG in a time-dependent manner. However, c-Jun expression is not associated with bladder afferent neurons. Resiniferatoxin reduced CYP-induced up-regulation of p-CREB in DRG, suggesting that cystitis can reveal an altered CREB phosphorylation that may be mediated by capsaicin-sensitive bladder afferents. Colocalization of p-CREB and Trk receptor(s) showed that a subpopulation of p-CREB-IR cells expressed p-Trk with cystitis. These results suggest that up-regulation of p-CREB may be mediated by a neurotrophin/Trk signaling pathway.

Continuous bladder infusion methods for studying voiding function in the ambulatory mouse

OBJECTIVES

To develop a method for chronic cannulation of the mouse bladder that would enable repeated intravesical drug delivery and measurement of voiding patterns in unrestrained mice under controlled infusion conditions.

METHODS

Fifteen female mice were anesthetized with halothane and implanted with a 3F polyurethane bladder catheter. The catheter exited from the back through mesh and a polysulfone button into a spring coil that protected the catheter and tethered the mouse. A counterbalanced swivel and infusion pump permitted unencumbered mobility during continuous intravesical perfusion.

RESULTS

Patent catheterization was consistently achieved for at least 5 weeks. The voiding patterns produced with an infusion pump were stable not only within a study session but also during the course of several weeks. The catheters remained patent but eventually withdrew from the bladder in 9 mice, at which point the mice were killed. The mesh eventually emerged from the skin in 4 animals without evidence of infection and was associated with catheter leakage at the level of mesh exposure. The subcutaneous placement of the mesh and tether assembly adequately transferred torque to the swivel without catheter obstruction. One mouse died unexpectedly during anesthesia; another was killed 1 week after catheter implantation because of an intraperitoneal leak. No bladder stones were identified. The results of the urine cultures were inconclusive.

CONCLUSIONS

Continuous, patent catheterization of the murine bladder can be achieved consistently for a period of 5 weeks. When used in combination with counterbalanced swivel assemblies and electronic balance technology, these methods permit prolonged evaluation of micturition patterns in the awake, ambulatory mouse.

Interstitial cystitis: an update

PURPOSE OF REVIEW

Interstitial cystitis is a chronically progressive, severely debilitating, heterogeneous syndrome affecting the urinary bladder, mainly associated with urgency, frequency and pain. Though known for over a century, its etiology is poorly understood and universally effective treatments are lacking. This review focuses on recently published literature on the disorder.

RECENT FINDINGS

Appropriate diagnostic tests for interstitial cystitis remain uncertain. The diagnostic criteria developed by the US National Institutes of Health represent research definitions which are subject to controversial debate for their overenthusiastic clinical application. The diagnosis is made clinically and by cystoscopy with hydrodistention and sometimes biopsy when other pathologies have been excluded. In symptomatic patients, glomerulations upon bladder distension are indicative but not pathognomonic for nonulcerative interstitial cystitis. Patients with ulcerative disease represent a separate subgroup with distinct characteristics and treatment implications. The role of bladder permeability tests remains controversial. Promising noninvasive markers for interstitial cystitis have been described but are not yet clinically available. Validated symptom scores are appropriate to assist in diagnostics and to monitor disease course and treatment efficacy. Lately investigated hypotheses for causative factors include occult or resistant microorganisms, urothelial hyperpermeability, neurogenic or hormonal pathomechanisms, and mast cell activation. Increasing evidence for a genetic susceptibility is emerging.

SUMMARY

Among the multitude of oral, intravesical, interventional and complementary treatments suggested few studies have high levels of evidence. Newly proposed agents must await further controlled studies. Treatment remains empiric until radical surgical procedures should ultimately be considered for severe refractory cases.

In vivo models of interstitial cystitis

PURPOSE

We systematically identified and evaluated various animal models that have been studied to help identify the underlying mechanisms of and possible treatment options for interstitial cystitis.

MATERIALS AND METHODS

Models of interstitial cystitis published between 1983 and 2001 were obtained by searching MEDLINE and other Internet databases using cystitis and model as the primary key words. Models with characteristics of interstitial cystitis similar to those defined by National Institutes of Arthritis, Diabetes, Digestive and Kidney Diseases criteria were reviewed. Some articles describing animal models with similar pathological conditions in other organs were also included to enlarge the base of potentially relevant material.

RESULTS

We identified and evaluated some 16 animal models of interstitial cystitis, which we categorized as bladder inflammation induced by intravesical administration of an irritant or immune stimulant, systemic and environmentally induced inflammation, and a naturally occurring model of interstitial cystitis that occurs in cats. Some abnormalities identified in humans and cats with interstitial cystitis can be reproduced in healthy animals using luminal, systemic or environmental stimuli. At the level of the bladder the source of stimulation cannot be discriminated. Variability in the extent of bladder distention complicated the interpretation of some studies. In addition, the noxious stimuli used can affect many epithelial surfaces as well as the urothelium, suggesting they are nonspecific responses to injury rather than specific to interstitial cystitis.

CONCLUSIONS

No model in bladder injury in healthy animals currently reproduces as many features of interstitial cystitis as the naturally occurring disease in cats. While induced models of relative injury may help to provide insight into the bladder response to injury, feline interstitial cystitis follows a similar chronic waxing and waning time course as does interstitial cystitis in humans, which may be more suitable for studying the effects of stressors on the severity of clinical signs as well as newly proposed therapies.

Assessment of murine bladder permeability with fluorescein: validation with cyclophosphamide and protamine

OBJECTIVES

Bladder hyperpermeability should result in elevated blood levels of intravesically administered agents. Reabsorption from a hyperpermeable bladder should result in prolonged urinary excretion of an agent after parenteral administration. To test these hypotheses, urinary clearance and plasma levels of sodium fluorescein (NaF) were measured in mice before and during cyclophosphamide (CYP) and protamine-induced hemorrhagic cystitis.

METHODS

To measure the plasma uptake of NaF from the bladder, 10 mg/mL NaF was instilled, either by catheter or retrograde urethral infusion, 15 minutes before retro-orbital or ventricular sampling. The plasma levels were measured 24 hours and 14 days after exposure to CYP 300 mg/kg or 15 minutes after instillation of protamine 10 mg/mL. Hourly urine concentrations were measured immediately after intraperitoneal administration of 10 mg/kg NaF. Pretreatment samples were compared with those obtained 24 hours after intraperitoneal administration of 300 mg/kg CYP.

RESULTS

Urinary NaF excretion was delayed in CYP-exposed mice. A bi-exponential model provided an appropriate fit of the data, both before and after CYP administration. The plasma levels of NaF were significantly elevated at 24 hours and 14 days after CYP exposure when sampled by ventricular nick or retro-orbitally. The median concentration of fluorescein in the protamine-treated mice was significantly higher than in the control mice.

CONCLUSIONS

Fluorescein can be used to measure alterations in bladder permeability after bladder mucosal injury in mice. Urinary excretion of NaF is a bi-exponential process that is delayed after bladder mucosal injury, presumably because of increased mucosal permeability and resorption from the urine into the bloodstream.