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

Data-driven detection of age-related arbitrary monotonic changes in single-cell gene expression distributions

Identification of genes whose expression increases or decreases with age is central to understanding the mechanisms behind aging. Recent scRNA-seq studies have shown that changes in single-cell expression profiles with aging are complex and diverse. In this study, we introduce a novel workflow to detect changes in the distribution of arbitrary monotonic age-related changes in single-cell expression profiles. Since single-cell gene expression profiles can be analyzed as probability distributions, our approach uses information theory to quantify the differences between distributions and employs distance matrices for association analysis. We tested this technique on simulated data and confirmed that potential parameter changes could be detected in a set of probability distributions. Application of the technique to a public scRNA-seq dataset demonstrated its potential utility as a straightforward screening method for identifying aging-related cellular features.

Impaired nitric oxide mechanisms underlying lower urinary tract dysfunction in aging rats

The study aimed to investigate the bladder and urethral activity and nitric oxide (NO)-related molecular changes in aging rats. Rats were divided into two groups: Group Y (young rats; 12 wk) and Group A (aging rats; 15 mo). A 24-h voiding assay was performed, and the urodynamic parameters were evaluated using awake cystometry (CMG) and urethral perfusion pressure (UPP) recordings under urethane anesthesia. The mRNA expression levels of NO-, ischemia-, and inflammation-related markers in urethra and bladder tissues and cGMP levels in the urethra were assessed. Body weight was significantly higher in Group A than in Group Y. Voiding assay results (24 h) were insignificant. In the CMG, the number of non-voiding contractions per voiding cycle and post-void residual volume were significantly higher in Group A than in Group Y; voiding efficiency was significantly lower in Group A than in Group Y. In the UPP recordings, the urethral pressure reduction and high-frequency oscillation (HFO) amplitude were significantly lower in Group A than in Group Y. The mRNA expression levels of Hif-1α, Vegf-a, and Tgf-β1 in the bladder were significantly higher in Group A than in Group Y. The mRNA expression levels of Nos1 and Prkg1 and the cGMP concentrations in the urethra were significantly lower in Group A than in Group Y. Aging rats can be useful models for studying the natural progression of age-related lower urinary tract dysfunctions, for which impaired NO-mediated transmitter function is likely to be an important mechanism.NEW & NOTEWORTHY Aging rats can be useful models for studying the natural progression of age-related lower urinary tract dysfunctions, for which impaired nitric oxide-mediated transmitter function is likely to be an important mechanism.

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.

Human amniotic fluid stem cell therapy can help regain bladder function in type 2 diabetic rats

BACKGROUND

Diabetes mellitus (DM) is a serious and growing global health burden. It is estimated that 80% of diabetic patients have micturition problems such as poor emptying, urinary incontinence, urgency, and urgency incontinence. Patients with diabetic bladder dysfunction are often resistant to currently available therapies. It is necessary to develop new and effective treatment methods.

AIM

To examine the therapeutic effect of human amniotic fluid stem cells (hAFSCs) therapy on bladder dysfunction in a type 2 diabetic rat model.

METHODS

Sixty female Sprague-Dawley rats were divided into five groups: Group 1, normal-diet control (control); group 2, high-fat diet (HFD); group 3, HFD plus streptozotocin-induced DM (DM); group 4, DM plus insulin treatment (DM + insulin); group 5, DM plus hAFSCs injection via tail vein (DM + hAFSCs). Conscious cystometric studies were done at 4 and 12 wk after insulin or hAFSCs treatment to measure peak voiding pressure, voided volume, intercontraction interval, bladder capacity, and residual volume. Immunoreactivities and/or mRNA expression of muscarinic receptors, nerve growth factor (NGF), and sensory nerve markers in the bladder and insulin, MafA, and pancreatic-duodenal homeobox-1 (PDX-1) in pancreatic beta cells were studied.

RESULTS

Compared with DM rats, insulin but not hAFSCs treatment could reduce the bladder weight and improve the voided volume, intercontraction interval, bladder capacity, and residual volume (P < 0.05). However, both insulin and hAFSCs treatment could help to regain the blood glucose and bladder functions to the levels near controls (P > 0.05). The immunoreactivities and mRNA expression of M2- and M3-muscarinic receptors (M2 and M3) were increased mainly at 4 wk (P < 0.05), while the number of beta cells in islets and the immunoreactivities and/or mRNA of NGF, calcitonin gene-related peptide (CGRP), substance P, insulin, MafA, and PDX-1 were decreased in DM rats (P < 0.05). However, insulin and hAFSCs treatment could help to regain the expression of M2, M3, NGF, CGRP, substance P, MafA, and PDX-1 to near the levels of controls at 4 and/or 12 wk (P > 0.05).

CONCLUSION

Insulin but not hAFSCs therapy can recover the bladder dysfunction caused by DM; however, hAFSCs and insulin therapy can help to regain bladder function to near the levels of control.

E-cadherin deficiency promotes prostate macrophage inflammation and bladder overactivity in aged male mice

Decreased E-cadherin immunostaining is frequently observed in benign prostatic hyperplasia (BPH) and was recently correlated with increased inflammation in aging prostate. Homozygous E-cadherin deletion in the murine prostate results in prostate inflammation and bladder overactivity at 6 months of age. However, this model is limited in that while E-cadherin is significantly reduced in BPH, it is not completely lost; BPH is also strongly associated with advanced age and is infrequent in young men. Here, we examined the functional consequences of aging in male mice with prostate luminal epithelial cell-specific E-cadherin heterozygosity. In control mice, aging alone resulted in an increase in prostate inflammation and changes in bladder voiding function indicative of bladder underactivity. At 24 months of age, mice with prostate-specific Cre-mediated heterozygous deletion of E-cadherin induced at 7 weeks of age developed additional prostatic defects, particularly increased macrophage inflammation and stromal proliferation, and bladder overactivity compared to age-matched control mice, which are similar to BPH/LUTS in that the phenotype is slow-progressing and age-dependent. These findings suggest that decreased E-cadherin may promote macrophage inflammation and fibrosis in the prostate and subsequent bladder overactivity in aging men, promoting the development and progression of BPH/LUTS.

Sarcopenia and Visceral Obesity are Significantly Related to Severe Storage Symptoms in Geriatric Female Patients

Purpose

This study aimed to elucidate the relationship of psoas muscle atrophy and visceral obesity with lower urinary tract symptoms in geriatric female patients.

Patients and Methods

We retrospectively reviewed the medical records of female patients aged ≥65 years. The psoas muscle index was defined, using computed tomography, as the cross-sectional area of the psoas muscle at the third lumbar vertebral level divided by the body surface area. We also measured visceral fat area at the umbilical level using computed tomography. We used logistic regression analysis to examine the relationships between the International Prostate Symptom Score (total score, voiding subscore, and storage subscore) and variables, such as age, body mass index, psoas muscle index, and visceral fat area. The International Prostate Symptom Score was categorized as mild, moderate, or severe.

Results

One hundred thirty-nine patients were included in our study. In the logistic regression analysis, we found statistically significant relationships between severe (versus mild-to-moderate) International Prostate Symptom Score storage subscore and variables, including low and high levels of psoas muscle index and visceral fat area, respectively. We could not find any significant relationships between the International Prostate Symptom Score total score and voiding subscore and the variables.

Conclusion

Psoas muscle atrophy and visceral fat accumulation are potential risk factors for severe storage symptoms in female patients aged ≥65 years.

Rodent models of ketamine-induced cystitis

AIMS

Long-term or recreational use of ketamine affects the urinary system and can result in ketamine-induced cystitis (KIC). Rodent models of KIC are important to study KIC pathophysiology and are paramount to the future development of therapies for this painful condition. This review aims to provide a summary of rodent models of KIC, focusing on disease induction, experimental methods, and pathological features of the model.

METHOD

A literature search was performed using the National Center for Biotechnology Information (NCBI) Pubmed database up to March 2021. 20 articles met the inclusion criteria and were finally selected.

RESULTS

There are considerable variations in the rodent models used for studying KIC in terms of the strain of the animal being used; dose, duration, and route of ketamine administration to induce KIC, and assessment of pathological features.

CONCLUSION

KIC remains difficult to fully recapitulate in humans. Improved characterization of KIC models and the experimental parameters and meticulous discussion on translational limitations are required to improve the translational value of research using rodent models of KIC.

Recurrent Urinary Tract Infection: A Mystery in Search of Better Model Systems

Urinary tract infections (UTIs) are among the most common infectious diseases worldwide but are significantly understudied. Uropathogenic E. coli (UPEC) accounts for a significant proportion of UTI, but a large number of other species can infect the urinary tract, each of which will have unique host-pathogen interactions with the bladder environment. Given the substantial economic burden of UTI and its increasing antibiotic resistance, there is an urgent need to better understand UTI pathophysiology - especially its tendency to relapse and recur. Most models developed to date use murine infection; few human-relevant models exist. Of these, the majority of in vitro UTI models have utilized cells in static culture, but UTI needs to be studied in the context of the unique aspects of the bladder's biophysical environment (e.g., tissue architecture, urine, fluid flow, and stretch). In this review, we summarize the complexities of recurrent UTI, critically assess current infection models and discuss potential improvements. More advanced human cell-based in vitro models have the potential to enable a better understanding of the etiology of UTI disease and to provide a complementary platform alongside animals for drug screening and the search for better treatments.

NTPDase1 Modulates Smooth Muscle Contraction in Mice Bladder by Regulating Nucleotide Receptor Activation Distinctly in Male and Female

Nucleotides released by smooth muscle cells (SMCs) and by innervating nerve terminals activate specific P2 receptors and modulate bladder contraction. We hypothesized that cell surface enzymes regulate SMC contraction in mice bladder by controlling the concentration of nucleotides. We showed by immunohistochemistry, enzymatic histochemistry, and biochemical activities that nucleoside triphosphate diphosphohydrolase-1 (NTPDase1) and ecto-5′-nucleotidase were the major ectonucleotidases expressed by SMCs in the bladder. RT-qPCR revealed that, among the nucleotide receptors, there was higher expression of P2X1, P2Y₁, and P2Y₆ receptors. Ex vivo, nucleotides induced a more potent contraction of bladder strips isolated from NTPDase1 deficient (Entpd1^−/−) mice compared to wild type controls. The strongest responses were obtained with uridine 5′-triphosphate (UTP) and uridine 5′-diphosphate (UDP), suggesting the involvement of P2Y₆ receptors, which was confirmed with P2ry6^−/− bladder strips. Interestingly, this response was reduced in female bladders. Our results also suggest the participation of P2X1, P2Y₂ and/or P2Y₄, and P2Y₁₂ in these contractions. A reduced response to the thromboxane analogue U46619 was also observed in wild type, Entpd1^−/−, and P2ry6^−/− female bladders showing another difference due to sex. In summary, NTPDase1 modulates the activation of nucleotide receptors in mouse bladder SMCs, and contractions induced by P2Y₆ receptor activation were weaker in female bladders.

Pathogenesis evidence from human and animal models of detrusor underactivity

Detrusor underactivity (DU) is a common urodynamic diagnosis in patients with lower urinary tract symptoms and large post-voiding residual volume. Animal and human studies showed the possible etiologies of DU include central or peripheral nerve injury, bladder outlet obstruction, chronic ischemia, aging, diabetes mellitus, and sympathetic inhibition of micturition reflex. Evidence from animal and human DU studies with various etiologies revealed highly similar gross and histological characteristics in the bladders, including increased bladder weight, bladder wall thickening, inflammation, collagen deposition, and fibrosis. In electron microscopy, smooth muscle destruction, swollen mitochondria, decreased nerve innervation, caveolae, and umbrella cell fusiform vesicles were noted in the DU bladders. Most animal DU models demonstrate detrusor contractility changes from compensatory to the decompensatory stage, and the change was compatible with human DU observation. The cystometry in the DU animal studies is characterized by impaired contractility, prolong intercontraction interval, and hyposensation, while in vitro bladder muscle strips experiment may exhibit normal detrusor contractility. Decreased bladder blood flow and increased oxidative stress in bladders had been proved in different animal DU models, suggesting they should be important in the DU pathogenesis pathway. Sensory receptors mRNA and protein expression changes in DU bladders had been observed in both animal and human studies, including muscarinic receptors M2, M3, adrenergic receptor β3, purinergic receptor P2X1, P2X3, and transient receptor potential vanilloid (TRPV) 1 and TRPV4. Although some of the sensory receptors changes remain controversial, it might be the target for further pharmacologic treatments.

Lacking transient receptor potential melastatin 2 attenuates lipopolysaccharide-induced bladder inflammation and its associated hypersensitivity in mice

OBJECTIVE

To study the role of transient receptor potential melastatin 2 in bladder function and inflammation-associated hypersensitivity.

METHODS

We evaluated physiological function of the bladder and intravesical lipopolysaccharide-induced inflammatory nociceptive responses in female wild-type and transient receptor potential melastatin 2-knockout mice. In vivo frequency/volume and decerebrated unanesthetized cystometry measurements, as well as in vitro detrusor strip functional studies, were carried out to evaluate bladder function. Mice received intravesical lipopolysaccharide (2.0 mg/mL) or saline instillation to evaluate responses to bladder inflammation. Voiding and bladder pain-like behaviors, cystometry measurements and histological evaluation were carried out before and after intravesical lipopolysaccharide instillation.

RESULTS

Few phenotypic differences in in vivo and in vitro physiological function were found between the two genotypes. Comparison of measurements taken before and 24-48 h after intravesical lipopolysaccharide instillation showed that voiding parameters did not change in transient receptor potential melastatin 2-knockout mice, whereas an increased voiding frequency was observed in wild-type mice. At 24 h after intravesical lipopolysaccharide instillation, the numbers of bladder pain-like behaviors and of infiltrated inflammatory cells in the bladder submucosal layer were significantly increased, and the voided volume and the intercontraction interval were significantly decreased on cystometry measurements in wild-type mice compared with those in both transient receptor potential melastatin 2-knockout mice and in wild-type mice treated with saline instillation.

CONCLUSIONS

Although the physiological roles of transient receptor potential melastatin 2 channels in the bladder might be limited, inflammation and associated hypersensitivity of the bladder caused by intravesical lipopolysaccharide instillation are attenuated in transient receptor potential melastatin 2-knockout mice, suggesting pathophysiological roles of transient receptor potential melastatin 2 channels in these processes.

Micturition defects and altered bladder function in the klotho mutant mouse model of aging

INTRODUCTION AND OBJECTIVES

Symptoms associated with detrusor underactivity (DU) or underactive bladder (UAB) can severely impact a person's quality of life, and growing old is the main etiological factor of DU and UAB. The gene Klotho has been associated with suppression of several aging phenotypes, and there is moderate klotho expression in the bladder. Given this, we hypothesized that the klotho gene is involved in regulation of bladder function. Thus, we examined a premature aging rodent genetic model with hypomorphic klotho expression for alterations in bladder function.

METHODS

Klotho mutant mice are established as a preclinical model of aging. Male and female klotho mice had micturition measured at weeks 4, 6, and 8 through metabolic cage and void spot assays. Histology was assessed at 4, 6, and 8 weeks. Lastly, bladder contraction was assessed using bladder strip tissue bath. All animals were gender- and age-matched with wild-type littermates for analysis.

RESULTS

Void spot and bladder contraction assays revealed that klotho mutant mice, similar to other aging models, have increased voiding frequency and decreased voiding volume per micturition event. The in vitro contractile response to electrical stimulation was weaker and muscarinic receptor subtype expression was reduced in the in klotho mutant mouse bladders. These data suggest that klotho mutant mouse bladders had impaired bladder function.

CONCLUSIONS

Klotho mutant mice recapitulate many characteristics of an older dysfunctional bladder, including altered bladder function. Given the short time frame to bladder dysfunction and robustness of the model, this model will provide new insights to drive aging bladder research.

Stretch- and carbachol-induced ATP release from bladder wall preparations of young and aged mice

AIMS

Bladder wall stretch increases tissue tension and releases adenosine 5'-triphosphate (ATP) as part of a transduction process to sense bladder filling. Aging is associated with bladder fibrosis to produce a stiffer bladder wall: this may augment ATP release and contribute to age-dependent urgency. Muscarinic agonists also release ATP and present a potential target for antimuscarinic agents, but its age-dependency is unknown. This study aimed, in young and old mice, to: (a) quantify the relationship between bladder wall stiffness and stretch-dependent ATP release and; (b) characterize muscarinic agonist-dependent release.

METHODS

ATP release from young (9-12 weeks) and aged (24 months) mouse bladder wall was measured in vitro, with a luciferin-luciferase assay, after stretch or carbachol exposure. Bladder wall stiffness, measured simultaneously during stretch, was compared to histological proportions of connective tissue and detrusor muscle.

RESULTS

With young mice, stretch-activated ATP release required an intact mucosa and was positively associated with wall stiffness. ATP release by carbachol was about four-fold greater compared to stretch. With aged mice: ATP release varied a hundred-fold and no association with stiffness; carbachol release diminished; connective tissue and mucosa thickness increased.

CONCLUSIONS

With young mice, stretch, or muscarinic agonists potently induce bladder wall ATP release. Stretch-dependent release is proportional to bladder wall stiffness, independent of the extent of stretch. With aged mice dependence of stretch-activated ATP release with stiffness was lost. The huge variability of release suggests that aged mice do not form a homogenous cohort and may underlie the heterogeneity in bladder filling sensations.

Microbiota Alters Urinary Bladder Weight and Gene Expression

We studied the effect of microbiota on the transcriptome and weight of the urinary bladder by comparing germ-free (GF) and specific pathogen-free (SPF) housed mice. In total, 97 genes were differently expressed (fold change > ±2; false discovery rate (FDR) p-value < 0.01) between the groups, including genes regulating circadian rhythm (Per1, Per2 and Per3), extracellular matrix (Spo1, Spon2), and neuromuscular synaptic transmission (Slc18a3, Slc5a7, Chrnb4, Chrna3, Snap25). The highest increase in expression was observed for immunoglobulin genes (Igkv1-122, Igkv4-68) of unknown function, but surprisingly the absence of microbiota did not change the expression of the genes responsible for recognizing microbes and their products. We found that urinary bladder weight was approximately 25% lighter in GF mice (p = 0.09 for males, p = 0.005 for females) and in mice treated with broad spectrum of antibiotics (p = 0.0002). In conclusion, our data indicate that microbiota is an important determinant of urinary bladder physiology controlling its gene expression and size.

Change of Detrusor Contractility in Patients with and without Bladder Outlet Obstruction at Ten or More Years of follow-up

To analyze the change of detrusor contractility by investigating urodynamic characteristics with long term follow-up. This study retrospectively reviewed 166 lower urinary tract symptoms patients without bladder outlet obstruction (BOO) and 63 patients with BOO who underwent repeated urodynamic studies at the first time and more than 10 years later. The urodynamic parameters, bladder contractility index (BCI), and BOO index (BOOI) were compared before and after. As time goes by, detrusor pressure at maximum flow rate (PdetQmax) significantly decreased and post-void residual (PVR) volume significantly increased in both men and women. Full sensation, urge sensation, voided volume, and BCI significantly decreased. We also compared men with and without BOO, PdetQmax, maximum flow rate (Qmax), voided volume, and BCI all significantly decreased in both groups without difference. PVR increased greater in men with BOO after >10 years significantly (p = 0.036). Women with detrusor overactivity (DO) under antimuscarinic showed no significant BCI change compared to patients without DO (p = 0.228). Detrusor contractility decreases in men and women after >10 years of follow-up. However, this finding suggests that patients with BOO or DO under adequate medical treatment, detrusor contractility is not aggravated over 10 or more years of follow-up.

Void sorcerer: an open source, open access framework for mouse uroflowmetry

Observational and experimental studies of rodent voiding behaviors have greatly contributed to our understanding of lower urinary tract function including the complex social, environmental, and internal stimuli that affect voiding in health and models of disease. Void spot assays (VSA), cystometry (awake or anesthetized), and uroflowmetry are techniques commonly used in rodent models to assess voiding. Uroflowmetry is non-invasive and can be performed multiple times in the same freely moving animals and can be used to generate synchronized video corresponding to each void to characterize micturition patterns (e.g., droplets versus solid stream). However, approaches to evaluate uroflowmetry in rodent models vary widely across laboratories. Most importantly, an open access software to run these tests is not freely available (although complete systems are commercially available), limiting use of this important assay. We developed the Void Sorcerer, an uroflowmetry system for mice for reliable determination of frequency, voided volume, voiding duration, interval times between micturitions, and flow rate. This report provides a detailed description of how to build this system and includes open access software for developing uroflowmetry capability in their laboratories and improve upon it in a cost-effective manner. Our goals are to improve access, increase reproducibility among laboratories, and facilitate standardizing testing procedures.

Influence of sildenafil on the purinergic components of nerve-mediated and urothelial ATP release from the bladder of normal and spinal cord injured mice

Background and purpose

PDE inhibitors such as sildenafil alleviate lower urinary tract symptoms; however, a complete understanding of their action on the bladder remains unclear. We are investigating the effects of sildenafil, on post and preganglionic nerve‐mediated contractions of the mouse bladder, and neuronal and urothelial ATP release.

Experimental approach

Bladders were used from young (12 weeks), aged (24 months), and spinal cord transected (SCT), mice, for in vitro contractility experiments. An arterially perfused in situ whole mouse model was used to record bladder pressure. Nerve‐mediated contractions were generated by electrical field stimulation (EFS) of postganglionic nerve terminals or the pelvic nerve. ATP release during EFS in intact detrusor strips, and during stretch of isolated mucosa strips, was measured using a luciferin‐luciferase assay.

Key results

Sildenafil (20 μM) inhibited nerve‐mediated contractions in young mice, with an increase in f_1/2 values in force–frequency relationships, demonstrating a greater effect at low frequencies. Sildenafil reduced the atropine‐resistant, purinergic component of nerve‐mediated contractions, and suppressed neuronal ATP release upon EFS in vitro. Sildenafil reduced the preganglionic pelvic nerve stimulated bladder pressure recordings in situ; comparable to in vitro experiments. Sildenafil reduced stretch‐induced urothelial ATP release. Sildenafil also relaxed nerve‐mediated contractions in aged and SCT mice.

Conclusion and implications

Sildenafil has a greater effect on the low‐frequency, purinergic‐mediated contractions and suppresses neuronal ATP release. In addition, sildenafil reduces stretch‐induced urothelial ATP release. These results demonstrate a novel action of sildenafil to selectively inhibit ATP release from nerve terminals innervating detrusor smooth muscle and the urothelium.

Autonomic dysregulation at multiple sites is implicated in age-associated underactive bladder in female mice

AIMS

To evaluate the functional and molecular alterations of contractile and relaxant machinery in the bladder and urethra that lead to the underactive bladder (UAB) in old female mice.

METHODS

Female young (3-months) and old (18-months) C57BL/6 mice were used. Urodynamic was assessed in awake and anaesthetized mice. Electrical-field stimulation (EFS) and concentration-response curves to contractile and relaxing agents in isolated bladders and urethras were performed. Messenger RNA (mRNA) expressions of muscarinic, adrenergic, and transient receptor potential vanilloid-4 (TRPV4), and of the enzymes tyrosine hydroxylase and neuronal nitric oxide synthase (nNOS) were determined. Bladder cyclic adenosine monophosphate (cAMP) levels were measured.

RESULTS

Cystometry in old mice showed incapacity to produce bladder emptying. On filter paper, old mice showed reduced urinary spots. Compared to the young group, bladder contractions induced by EFS and carbachol were lower in old mice. The β₃ -adrenoceptor agonist mirabegron promoted higher bladder relaxation and elevation of cAMP levels in old mice. In old mice urethras, the α_1a -adrenoceptor agonist phenylephrine produced higher contractions, but no differences were found for the NO donor sodium nitroprusside-induced relaxations. In old mice, increased mRNA expressions of β₃ - and α_1a -adrenoceptors in bladder and urethra were found, respectively, whereas the muscarinic M₂ and M₃ receptors and β₂ -adrenoceptors did not change between groups. Reduced mRNA expressions of tyrosine hydroxylase and nNOS were found in old mouse urethras. Additionally, TRPV4 expression was reduced in bladder urothelium from old mice.

CONCLUSION

Age-associated mouse UAB is the result of autonomic dysfunction at multiple levels leading to the less sensitive and overrelaxed bladder, along with urethral hypercontractility.

Attenuated lipopolysaccharide-induced inflammatory bladder hypersensitivity in mice deficient of transient receptor potential ankilin1

Transient receptor potential ankyrin 1 (TRPA1) channel expressed by urothelial cells and bladder sensory nerve fibers might act as a bladder mechanosensor and nociceptive transducer. To disclose the role of TRPA1 in bladder function and inflammation-associated hypersensitivity, we evaluated in vitro and in vivo bladder function and inflammatory mechanosensory and nociceptive responses to intravesical lipopolysaccharide (LPS)-instillation in wild type (WT) and TRPA1-knock out (KO) mice. At baseline before treatment, no significant differences were observed in frequency volume variables, in vitro detrusor contractility, and cystometric parameters between the two groups in either sex. LPS-instillation significantly increased voiding frequency and decreased mean voided volume at 24-48 hours after instillation in WT but not in TRPA1-KO mice. LPS-instillation also significantly increased the number of pain-like behavior at 24 hours after instillation in WT mice, but not in TRPA1-KO mice. Cystometry 24 hours after LPS-instillation revealed shorter inter-contraction intervals in the WT mice compared with TRPA1-KO mice. In contrast, inflammatory cell infiltration in the bladder suburothelial layer was not significantly different between the two groups. These results indicate that TRPA1 channels are involved in bladder mechanosensory and nociceptive hypersensitivity accompanied with inflammation but not in physiological bladder function or development of bladder inflammation.