Time-dependent progress of lower urinary tract dysfunction in streptozotocin-induced diabetic rats with or without low-dose insulin treatment.

Objectives: To examine time-dependent functional and structural changes of the lower urinary tract in streptozotocin-induced diabetic rats with or without low-dose insulin treatment and explore the pathophysiological characteristics of insulin therapy on lower urinary tract dysfunction (LUTD) caused by diabetes mellitus (DM). Methods: Female Sprague-Dawley rats were divided into five groups: normal control (NC) group, 4 weeks insulin-treated DM (4-DI) group, 4 weeks DM (4-DM) group, 8 weeks insulin-treated DM (8-DI) group and 8 weeks DM (8-DM) group. DM was initially induced by i.p. injection of streptozotocin (65 mg/kg), and then the DI groups received subcutaneous implantation of insulin pellets under the mid dorsal skin. Voiding behavior was evaluated in metabolic cages. The function of bladder and urethra in vivo were evaluated by simultaneous recordings of the cystometrogram and urethral perfusion pressure (UPP) under urethane anesthesia. The function of bladder and urethra in vitro were tested by organ bath techniques. The morphologic changes of the bladder and urethra were investigated using Hematoxylin-Eosin and Masson's staining. Results: Both 4-and 8-weeks diabetic rats have altered micturition patterns, including increased 12-h urine volume, urinary frequency/12 hours and voided volume. In-vivo urodynamics showed the EUS bursting activity duration is longer in 4-DM group and shorter in 8-DM group compared to NC group. UPP change in 8-DM were significantly lower than NC group. While none of these changes were found between DI and NC groups. Organ bath showed the response to Carbachol and EFS in bladder smooth muscle per tissue weights was decreased significantly in 4- and 8-weeks DM groups compared with insulin-treated DM or NC groups. In contrast, the contraction of urethral muscle and maximum urethral muscle contraction per gram of the tissue to EFS stimulation were significantly increased in 4- and 8-weeks DM groups. The thickness of bladder smooth muscle was time-dependently increased, but the thickness of the urethral muscle had no difference. Conclusions: DM-induced LUTD is characterized by time-dependent functional and structural remodeling in the bladder and urethra, which shows the hypertrophy of the bladder smooth muscle, reduced urethral smooth muscle relaxation and EUS dysfunction. Low-dose insulin can protect against diuresis-induced bladder over-distention, preserve urethral relaxation and protect EUS bursting activity, which would be helpful to study the slow-onset, time-dependent progress of DM-induced LUTD.

Nitrergic inhibition of sympathetic arteriolar constrictions in the female rodent urethra.

During the urine storage phase, tonically contracting urethral musculature would have a higher energy consumption than bladder muscle that develops phasic contractions. However, ischaemic dysfunction is less prevalent in the urethra than in the bladder, suggesting that urethral vasculature has intrinsic properties ensuring an adequate blood supply. Diameter changes in rat or mouse urethral arterioles were measured using a video-tracking system. Intercellular Ca2+ dynamics in arteriolar smooth muscle (SMCs) and endothelial cells were visualised using NG2- and parvalbumin-GCaMP6 mice, respectively. Fluorescence immunohistochemistry was used to visualise the perivascular innervation. In rat urethral arterioles, sympathetic vasoconstrictions were predominantly suppressed by α,ß-methylene ATP (10 µM) but not prazosin (1 µM). Tadalafil (100 nM), a PDE5 inhibitor, diminished the vasoconstrictions in a manner reversed by N-ω-propyl-l-arginine hydrochloride (l-NPA, 1 µM), a neuronal NO synthesis (nNOS) inhibitor. Vesicular acetylcholine transporter immunoreactive perivascular nerve fibres co-expressing nNOS were intertwined with tyrosine hydroxylase immunoreactive sympathetic nerve fibres. In phenylephrine (1 µM) pre-constricted rat or mouse urethral arterioles, nerve-evoked vasodilatations or transient SMC Ca2+ reductions were largely diminished by l-nitroarginine (l-NA, 10 µM), a broad-spectrum NOS inhibitor, but not by l-NPA. The CGRP receptor antagonist BIBN-4096 (1 µM) shortened the vasodilatory responses, while atropine (1 µM) abolished the l-NA-resistant transient vasodilatory responses. Nerve-evoked endothelial Ca2+ transients were abolished by atropine plus guanethidine (10 µM), indicating its neurotransmitter origin and absence of non-adrenergic non-cholinergic endothelial NO release. In urethral arterioles, NO released from parasympathetic nerves counteracts sympathetic vasoconstrictions pre- and post-synaptically to restrict arteriolar contractility. KEY POINTS: Despite a higher energy consumption of the urethral musculature than the bladder detrusor muscle, ischaemic dysfunction of the urethra is less prevalent than that of the bladder. In the urethral arterioles, sympathetic vasoconstrictions are predominately mediated by ATP, not noradrenaline. NO released from parasympathetic nerves counteracts sympathetic vasoconstrictions by its pre-synaptic inhibition of sympathetic transmission as well as post-synaptic arteriolar smooth muscle relaxation. Acetylcholine released from parasympathetic nerves contributes to endothelium-dependent, transient vasodilatations, while CGRP released from sensory nerves prolongs NO-mediated vasodilatations. PDE5 inhibitors could be beneficial to maintain and/or improve urethral blood supply and in turn the volume and contractility of urethral musculature.

Real-World Data Regarding Satisfaction to Botulinum Toxin A Injection into the Urethral Sphincter and Further Bladder Management for Voiding Dysfunction among Patients with Spinal Cord Injury and Voiding Dysfunction.

PURPOSE: This study aimed to investigate improvement in voiding condition after the initial botulinum toxin A (BoNT-A) injection into the urethral sphincter among patients with chronic spinal cord injury (SCI) and voiding dysfunction. Moreover, subsequent surgical procedures and bladder management were evaluated. MATERIALS AND METHODS: From 2011 to 2020, 118 patients with SCI and dysuria who wanted to void spontaneously received their first BoNT-A injection at a dose of 100 U into the urethral sphincter. Improvement in voiding and bladder conditions after BoNT-A treatment were assessed. Next, patients were encouraged to continually receive BoNT-A injections into the urethral sphincter, convert to other bladder managements, or undergo surgery. After undergoing bladder management and surgical procedures, the patients were requested to report improvement in voiding condition and overall satisfaction to bladder conditions. Then, data were compared. RESULTS: In total, 94 male and 24 female participants were included in this analysis. Among them, 51 presented with cervical, 43 with thoracic, and 24 with lumbosacral SCI. After BoNT-A injections into the urethral sphincter, 71 (60.2%) patients, including 18 (15.3%) with excellent, and 53 (44.9%) with moderate improvement, had significant improvement in voiding condition. Patients with cervical SCI (66.6%), detrusor overactivity and detrusor sphincter dyssynergia (72.0%), partial hand function (80.0%), and incomplete SCI (68.4%) had a better improvement rate than the other subgroups. Only 42 (35.6%) patients continually received treatment with BoNT-A injections into the urethral sphincter. Meanwhile, more than 60% of patients who converted their treatment to augmentation enterocystoplasty (n = 5), bladder outlet surgery (n = 25), BoNT-A injections into the detrusor muscle (n = 20), and medical treatment (n = 55) had moderate and marked improvement in voiding dysfunction and overall satisfaction. DISCUSSION: Although BoNT-A injections into the urethral sphincter could improve voiding condition, only patients with SCI who presented with voiding dysfunction were commonly satisfied. Those whose treatments were converted to other bladder managements, which can promote urinary continence, or to surgical procedures, which can facilitate spontaneous voiding, had favorable treatment outcomes.

Satisfaction with Detrusor OnabotulinumtoxinA Injections and Conversion to Other Bladder Management in Patients with Chronic Spinal Cord Injury.

This study investigated the satisfaction with continued detrusor Botox injections for urinary incontinence and conversion to other surgical procedures and bladder management procedures for neurogenic detrusor overactivity (NDO) in patients with chronic spinal cord injury (SCI). A total of 223 patients with chronic SCI underwent detrusor Botox 200U for urodynamically confirmed NDO and urinary incontinence. After initial detrusor Botox injections, patients opted to either continue detrusor Botox injections every six to nine months and on clean intermittent catheterization (CIC), switch to other bladder management procedures, or receive surgical procedures to improve their urinary incontinence, correct emergent complications, or have better voiding conditions without CIC. Urinary incontinence improvement rates and satisfaction with bladder management were assessed and compared between different subgroups, urodynamic parameters, and bladder management procedures. Finally, a total of 154 male and 69 female patients were included, among whom 56 (25.1%), 81 (36.3%), 51 (22.9%), and 35 (15.7%) showed a marked, moderate, mild, and no reduction in urinary incontinence, respectively. However, only 48.4% of the patients continued detrusor Botox injections over the mean follow-up period of seven years. Patients with cervical or thoracic SCI had fair incontinence improvement rates. The presence of high detrusor pressure and higher-grade bladder outlet resistance also predicted a decrease in incontinence. Although more than 50% of the patients switched to other bladder management procedures or received surgical treatment, 69.1% expressed satisfaction with their current status. This large cohort of patients with chronic SCI who received initial detrusor Botox injections revealed that only 48.4% continued with Botox injections. Those who received surgical procedures due to urological complications or demanded change in bladder management could achieve high satisfaction rates.

Therapeutic Efficacy of Urethral Sphincteric Botulinum Toxin Injections for Female Sphincter Dysfunctions and a Search for Predictive Factors.

External urethral sphincter (EUS) dysfunction is a common, bothersome female voiding dysfunction. This study aims to analyze the characteristics of different types of female EUS dysfunction, as well as to determine the outcome predictors of sphincteric botulinum toxin A (BoNT-A) injection. Women receiving sphincteric BoNT-A injections for refractory EUS dysfunction were retrospectively reviewed. A comparison of the baseline clinical, urodynamic parameters and the treatment responses were made for patients with different EUS dysfunctions. A total of 106 females were included. Significantly increased detrusor overactivity, detrusor contracting pressure and the bladder outlet obstruction index with decreased urge sensation were noted in patients diagnosed with dysfunctional voiding or detrusor sphincter dyssynergia comparing to those diagnosed with poor relaxation of the external urethral sphincter. The average subjective improvement rate was 67% for the injection. The therapeutic effect was not affected by the type of EUS dysfunction. The multivariate analysis revealed that bladder neck narrowing and catheterization history were predictive of negative outcomes. There is a distinct urodynamic presentation for each type of female EUS dysfunction. Sphincteric BoNT-A injection provides a good therapeutic outcome for refractory EUS dysfunction. A narrowing bladder neck and a history of catheterization suggest poor therapeutic outcomes.

Testosterone and Estrogen Repletion in a Hypogonadal Environment Improves Post-operative Angiogenesis.

OBJECTIVE: To determine the effects of perioperative hormone supplementation on postoperative periurethral angiogenesis in the setting of hypogonadism, we analyzed the urethral tissue of castrated Sprague Dawley rats supplemented with testosterone or estrogen who underwent a urethral surgery and compared it to those that did not. MATERIALS AND METHODS: 48 Sprague-Dawley rats were divided into 4 groups: (1) non-castrate (NC) controls; (2) castrate (C) unsupplemented rats; (3) castrate rats that received testosterone (T), or (4) castrate rats that received estradiol (E). Half of each group underwent urethroplasty surgery (S) while the other half were nonsurgical controls (C). With immunohistochemistry, we measured vessel density (endothelial cell marker CD31), expression levels of androgen receptor (AR), TIE-2, and estrogen receptor GPER1. RESULTS: Periurethral vascularity was significantly increased postoperatively with both testosterone and estrogen supplementation (TC vs TS: 8.92% vs 10.80%, P<.001; EC vs ES: 7.66 vs 8.73%, P = .009) as well as in noncastrated rats (NCC vs NCS: 5.86% vs 8.19%, P<.001) whereas in the absence of hormones, CD31 expression significantly decreased after surgery (CC vs CS: 3.62% vs 2.76%, P= .003). CD31 expression was strongly correlated with AR, TIE-2, and GPER1 expression indicating a mechanistic relationship. CONCLUSION: Both testosterone and estrogen supplementation increase periurethral vascularity in castrated (hypogonadal) rats undergoing urethroplasty surgery, contrary to decreased periurethral vascularity observed in the castrated non-supplemented rats. This suggests that hormonal resupplementation benefits post-operative regeneration in rats and may provide a basis for perioperative hormone supplementation in hypogonadal men prior to urethral surgery.

A uro-protective agent with restorative actions on urethral and striated muscle morphology.

PURPOSE: Aging increases oxidative stress, which can have delirious effects on smooth and striated muscle resulting in bladder dysfunction. Consequently, in women aged over 60 years, urinary incontinence (UI) is a prevalent health problem. Despite the prevalence and consequences, UI continues to be undertreated simply because there are few therapeutic options. METHODS: Here we investigated whether 8-aminoguanine (8-AG), a purine nucleoside phosphorylase (PNPase inhibitor), would restore urethra and external sphincter (EUS) muscle morphology in the aged rat. Aged (> 25 months) female Fischer 344 rats were randomized to oral treatment with 8-AG (6 weeks) or placebo, and the urethra and EUS were evaluated by electron microscopy and protein expression (western immunoblotting). RESULTS: Aging was associated with mitochondrial degeneration in smooth and striated muscle cells as compared to young rats. We also observed a significant increase in biomarkers such as PARP, a downstream activator of oxidative/nitrosative stress. Treatment of aged rats with 8-AG normalized all abnormalities to that of a younger state. CONCLUSIONS: 8-AG, a potent inhibitor of PNPase, reverses age-related lower urinary tract morphological and biochemical changes. Our observations support the concept that 8-AG will reverse age-induced lower urinary tract disorders such as UI. These initial findings could have therapeutic implications for the prevention and treatment of age-related UI.

Medical Management of Penile and Urethral Lichen Sclerosus with Topical Clobetasol Improves Long-Term Voiding Symptoms and Quality of Life.

PURPOSE: We evaluated the success of minimally invasive management of lichen sclerosus with topical and intraurethral clobetasol, as defined by improvement in patient reported outcome measures and nonprogression to surgery. MATERIALS AND METHODS: We conducted a review of our prospective ongoing quality improvement study to determine outcomes of our current standard practice for males with penile and urethral biopsy proven lichen sclerosus. Data were collected between 2011 and 2019, and included patient demographic information, medical and surgical histories, and location and extent of lichen sclerosus related pathology. The primary outcomes for this study were voiding function and voiding related quality of life, and were assessed using the AUASS (American Urological Association Symptom Score) and quality of life bother index, respectively. RESULTS: We identified 42 patients with biopsy proven lichen sclerosus related urethral stricture disease. Of these patients 85.7% were treated with intraurethral steroids alone and did not require surgical intervention. Median AUASS significantly improved from 12 to 8, and median quality of life bother index improved from 4 ("mostly dissatisfied") to 2 ("mostly satisfied"). Average stricture length of those with penile urethral disease and bulbar urethral disease was 4.8 cm (SD 3.0) and 16.2 cm (SD 6.5), respectively. Median followup was 8.4 months (IQR 2.6-26.4). CONCLUSIONS: Lichen sclerosus related urethral stricture disease can be effectively managed with intraurethral steroids. This minimally invasive management strategy improves patient reported voiding symptoms and voiding quality of life.

Data integration, analysis, and interpretation of eight academic CLARITY-BPA studies.

"Consortium Linking Academic and Regulatory Insights on BPA Toxicity" (CLARITY-BPA) was a comprehensive "industry-standard" Good Laboratory Practice (GLP)-compliant 2-year chronic exposure study of bisphenol A (BPA) toxicity that was supplemented by hypothesis-driven independent investigator-initiated studies. The investigator-initiated studies were focused on integrating disease-associated, molecular, and physiological endpoints previously found by academic scientists into an industry standard guideline-compliant toxicity study. Thus, the goal of this collaboration was to provide a more comprehensive dataset upon which to base safety standards and to determine whether industry-standard tests are as sensitive and predictive as molecular and disease-associated endpoints. The goal of this report is to integrate the findings from the investigator-initiated studies into a comprehensive overview of the observed impacts of BPA across the multiple organs and systems analyzed. For each organ system, we provide the rationale for the study, an overview of methodology, and summarize major findings. We then compare the results of the CLARITY-BPA studies across organ systems with the results of previous peer-reviewed studies from independent labs. Finally, we discuss potential influences that contributed to differences between studies. Developmental exposure to BPA can lead to adverse effects in multiple organs systems, including the brain, prostate gland, urinary tract, ovary, mammary gland, and heart. As published previously, many effects were at the lowest dose tested, 2.5µg/kg /day, and many of the responses were non-monotonic. Because the low dose of BPA affected endpoints in the same animals across organs evaluated in different labs, we conclude that these are biologically - and toxicologically - relevant.

Verification and Defined Dosage of Sodium Pentobarbital for a Urodynamic Study in the Possibility of Survival Experiments in Female Rat.

OBJECTIVES: To evaluate the effects of pentobarbital dosages on lower urinary tract function and to define an appropriate dosage of sodium pentobarbital that would be suitable for urodynamic studies in which recovery from anesthesia and long term survive were needed for subsequent experiment. METHODS: Twenty-four 8-week-old, female, virgin, Sprague-Dawley rats (200-250 g) were used in this study. Rats in study groups received gradient doses of pentobarbital intraperitoneally, and those in the control group received urethane intraperitoneally. External urethral sphincter electromyography (EUS-EMG) was recorded simultaneously during cystometry and leak point pressure tests. The toe-pinch reflex was used to determine the level of anesthesia. RESULTS: Micturition was normally induced in both the urethane group and 32 mg/kg pentobarbital group. However, in groups of 40 mg/kg or 36 mg/kg pentobarbital, micturition failed to be induced; instead, nonvoiding contractions accompanied by EUS-EMG tonic activity were observed. There were no significant differences in leak point pressure or EUS-EMG amplitude or frequency between the urethane and 32 mg/kg pentobarbital groups. CONCLUSIONS: This study confirmed significant dose-dependent effects of pentobarbital on lower urinary tract function and 32 mg/kg pentobarbital as an appropriate dosage for recovery urodynamic testing, which enable the achievement of expected essential micturition under satisfactory anesthesia in female rats.

Improvement of lower urinary tract function by a selective serotonin 5-HT1A receptor agonist, NLX-112, after chronic spinal cord injury.

Spinal cord injury (SCI) above the lumbosacral level results in lower urinary tract dysfunction, including (1) detrusor hyperreflexia, wherein bladder compliance is low, and (2) a lack of external urethral sphincter (EUS) control, leading to detrusor-sphincter dyssynergia (DSD) with poor voiding efficiency. Experimental studies in animals have shown a dense innervation of serotonergic (5-HT) fibers and multiple 5-HT receptors in the spinal reflex circuits that control voiding function. Here, we investigated the efficacy of NLX-112 (a.k.a. befiradol or F13640), in regulating lower urinary tract function after T8 contusive SCI in rats. NLX-112 is a very potent, highly-selective, and fully efficacious 5-HT1A receptor agonist, which has been developed for the treatment of L-DOPA-induced dyskinesia in Parkinson's disease patients. We performed urodynamics tests and external urethral sphincter electromyogram recordings to assess lower urinary tract function while NLX-112 was infused through the femoral vein in rats with chronic complete SCI or contusive SCI. The dose response studies indicated that NLX-112 was able to improve voiding behavior by regulating both detrusor and EUS activity. These included improvements in voiding efficiency, reduction of detrusor hyperactivity, and phasic activity of EUS during the micturition period. In addition, the application of a selective 5-HT1A receptor antagonist, WAY100635, reversed the improved detrusor and EUS activity elicited by NLX-112. In summary, the current data suggest that pharmacological activation of 5-HT1A receptors by NLX-112 may constitute a novel therapeutic strategy to treat neurogenic bladder after SCI.

Long-term tadalafil administration can prevent functional and structural changes of the urinary bladder in male rats with partial bladder outlet obstruction.

AIMS: There have been few reports on whether long-term oral phosphodiesterase 5 inhibitor administration can ameliorate bladder changes due to bladder outlet obstruction (BOO). Therefore, we clarified the chronological changes of the bladder using male BOO rats and evaluated the effects of tadalafil on these changes. METHODS: Eight-week-old male Sprague-Dawley rats were used. BOO was created by placing a polyethylene catheter around the urethra. Then, the rats were orally treated with a vehicle, or tadalafil 2 or 10 mg/kg until each evaluation period. Cystometric measurements were performed and the degree of fibrosis in the smooth muscle layer was evaluated at 2, 4, and 16 weeks. RESULTS: In BOO rats, a significant increase in the number of non-voiding contractions (NVCs) and a shortened intercontraction interval (ICI) were observed in the earlier phase (2 and 4 weeks) compared to Sham rats. In the chronic phase (16 weeks), markedly increased residual urine volume and an extended ICI were observed accompanied by enhanced smooth muscle fibrosis. These results indicated that the bladder in BOO rats represented the overactive phenotype in the earlier phase and changed into the underactive phenotype in the chronic phase. Even in Sham rats, an increased number of NVCs and enhanced fibrosis were observed with time. Tadalafil administration significantly prevented these bladder changes in both BOO and Sham rats. CONCLUSIONS: Long-term oral administration of tadalafil can prevent functional and histological changes in the BOO rat bladder. This agent is also effective for the bladder functional change even in non-obstructed rats.

Sustained release of stromal cell-derived factor-1 alpha from silk fibroin microfiber promotes urethral reconstruction in rabbits.

We developed a stromal cell-derived factor-1 alpha (SDF-1α)-aligned silk fibroin (SF)/three-dimensional porous bladder acellular matrix graft (3D-BAMG) composite scaffold for long-section ventral urethral regeneration and repair in vivo. SDF-1α-aligned SF microfiber/3D-BAMG, aligned SF microfiber/3D-BAMG, and nonaligned SF microfiber/3D-BAMG scaffolds were prepared using electrostatic spinning and wet processing. Adipose-derived stem cell (ADSC) and bone marrow stromal cell (BMSC) migration was assessed in the SDF-1α-loaded scaffolds. Sustained SDF-1α release in vitro and vivo was analyzed using enzyme-linked immunosorbent assay (ELISA) and western blotting, respectively. The scaffolds were used to repair a 1.5 × 1 cm2 ventral urethral defect in male rabbits in vivo. General observation and retrograde urinary tract contrast assessment were used to examine urethral lumen patency and continuity at 1 and 3 months post-surgery. Postoperative rehabilitation was evaluated using histological detection. The composite scaffolds sustained SDF-1α release for over 16 days in vitro. SDF-1α-aligned SF nanofiber promoted regeneration of urethral mucosa, submucosal smooth muscles, and microvasculature, increased cellular proliferation, and reduced collagen deposition. SDF-1α expression was increased in reconstructed urethra at 3 months post-surgery in SDF-1α-aligned SF group. SDF-1α-aligned SF microfiber/3D-BAMG scaffolds may be used to repair and reconstruct long urethral defects because they accelerate urethral regeneration.

Use of Botulinum Toxin A (BoNT-A) in Detrusor External Sphincter Dyssynergia (DESD): A Systematic Review and Meta-analysis.

We performed a systematic review to examine the efficacy and outcomes of Botulinum Toxin A (BoNT-A) as the primary intervention strategy for patients with detrusor external sphincter dyssynergia. Eleven studies were included in the analysis (n = 353; 16% female, 84% male). BoNT-A was effective in 60%-78% of patients for reducing postvoid residual, mean detrusor pressure, detrusor leak point pressure, and mean urethral pressure 1 month after injection. Most patients required reinjection after an average of 4-9 months. BoNT-A was not associated with any significant adverse events, and may improve quality of life, as well as urodynamic parameters for detrusor external sphincter dyssynergia.

Urethral Instillation of Povidone-Iodine Reduces Post-Cystoscopy Urinary Tract Infection in Males: A Randomized Controlled Trial.

Office cystoscopy may be associated with urinary tract infection (UTI) in up to 10-20% of patients. Current practice of surgical part preparation in males with povidone-iodine excludes distal urethra in males, leaving a possibility for resident intra-urethral flora to cause post-procedural UTI. We designed this randomized study to assess whether additional cleaning of distal urethra with povidone-iodine solution can help reduce post-procedural incidence of UTIs in this setting. Additionally, urethral swab culture was done in the entire cohort to identify the prevalent microflora in the distal male urethra and to evaluate its role in causation of post-procedural UTI. Using a specialized urethral swab culture methodology, 85% males demonstrated some bacteria and 16% showed common uro-pathogens. 28 (14.5%) cases had post-procedure culture positive UTI. The incidence of UTI in control group (22%) was significantly more than the intervention group (7%) (p value <0.007). This result strongly supports inclusion of distal urethral irrigation with povidone-iodine in males before office cystoscopy, even when pre-procedure mid-stream urine culture is sterile.

Urethral dysfunction and therapeutic effects of a PDE 5 inhibitor (tadalafil) in a rat model of detrusor underactivity induced by pelvic nerve crush injury.

AIMS: The urethral dysfunction produced by a rat model of peripheral neurogenic detrusor underactivity (DU) using pelvic nerve crush (PNC) injury was characterized and then tested with the administration of tadalafil, a phosphodiesterase type 5 (PDE 5) inhibitor. METHODS: Ten days after producing PNC rats, awake cystometrograms (CMGs) and isovolumetric cystometrograms with urethral perfusion pressure (IC-UPP) measurements were performed. Also, in control rats, IC-UPP was recorded before and after intravenous atropine administration to determine if the reduction of bladder contraction pressure affects urethral relaxation during voiding. Then, CMG and IC-UPP measurements in PNC rats were recorded after intravenous administration of tadalafil. Lastly, real-time polymerase chain reaction was used to measure transcript levels of neuronal nitric oxide synthases (nNOS), endothelial nitric oxide synthases, and PDE 5 in urethral specimens from PNC and control rats. RESULTS: PNC rats demonstrated the characteristics of DU in CMG. Also, PNC rats exhibited significant decreases in isovolumetric bladder contraction amplitudes and urethral relaxation. Atropine attenuated the amplitude of isovolumetric bladder contractions; however, atropine did not affect urethral relaxation in control rats. Tadalafil decreased postvoid residual and increased voiding efficiency without changing bladder contraction amplitude in PNC rats. Also, tadalafil improved the amplitude of urethral relaxation during bladder contraction in PNC rats. Urethral nNOS transcript levels were upregulated in PNC rats compared to control rats. CONCLUSIONS: PNC rats revealed both DU and impaired urethral relaxation. PDE 5 inhibition in PNC rats enhanced urethral relaxation during voiding, resulting in improved voiding efficiency. Thus, urethral dysfunction could be a potential target for the treatment of inefficient voiding associated with neurogenic DU.

Contribution of Cav1.2 Ca2+ channels and store-operated Ca2+ entry to pig urethral smooth muscle contraction.

Urethral smooth muscle (USM) generates tone to prevent urine leakage from the bladder during filling. USM tone has been thought to be a voltage-dependent process, relying on Ca2+ influx via voltage-dependent Ca2+ channels in USM cells, modulated by the activation of Ca2+-activated Cl- channels encoded by Ano1. However, recent findings in the mouse have suggested that USM tone is voltage independent, relying on Ca2+ influx through Orai channels via store-operated Ca2+ entry (SOCE). We explored if this pathway also occurred in the pig using isometric tension recordings of USM tone. Pig USM strips generated myogenic tone, which was nearly abolished by the Cav1.2 channel antagonist nifedipine and the ATP-dependent K+ channel agonist pinacidil. Pig USM tone was reduced by the Orai channel blocker GSK-7975A. Electrical field stimulation (EFS) led to phentolamine-sensitive contractions of USM strips. Contractions of pig USM were also induced by phenylephrine. Phenylephrine-evoked and EFS-evoked contractions of pig USM were reduced by ~50-75% by nifedipine and ~30% by GSK-7975A. Inhibition of Ano1 channels had no effect on tone or EFS-evoked contractions of pig USM. In conclusion, unlike the mouse, pig USM exhibited voltage-dependent tone and agonist/EFS-evoked contractions. Whereas SOCE plays a role in generating tone and agonist/neural-evoked contractions in both species, this dominates in the mouse. Tone and agonist/EFS-evoked contractions of pig USM are the result of Ca2+ influx primarily through Cav1.2 channels, and no evidence was found supporting a role of Ano1 channels in modulating these mechanisms.

Impact of sex, androgens, and prostate size on C57BL/6J mouse urinary physiology: urethral histology.

The National Institutes of Health leveled new focus on sex as a biological variable with the goal of understanding sex-specific differences in health and physiology. We previously published a functional assessment of the impact of sex, androgens, and prostate size on C57BL/6J mouse urinary physiology (Ruetten H, Wegner KA, Zhang HL, Wang P, Sandhu J, Sandhu S, Mueller B, Wang Z, Macoska J, Peterson RE, Bjorling DE, Ricke WA, Marker PC, Vezina CM. Am J Physiol Renal Physiol 317: F996-F1009, 2019). Here, we measured and compared five characteristics of urethral histology (urethral lumen diameter and area, epithelial cell count, epithelial and rhabdosphincter thickness, epithelial cell area, and total urethral area) in male and female 9-wk-old C57BL/6J mice using hematoxylin and eosin staining. We also compared male mice with castrated male mice, male and female mice treated with the steroid 5α-reductase inhibitor finasteride or testosterone, or male mice harboring alleles (Pbsn4cre/+; R26RDta/+) that reduce prostate lobe mass. The three methods used to reduce prostate mass (castration, finasteride, and Pbsn4cre/+; R26RDta/+) changed urethral histology, but none feminized male urethral histology (increased urethral epithelial area). Exogenous testosterone caused increased epithelial cell count in intact females but did not masculinize female urethral histology (decrease epithelial area). Our results lay a critical foundation for future studies as we begin to parse out the influence of hormones and cellular morphology on male and female urinary function.

Mirabegron causes vesical and urethral relaxation in rats with spinal cord injury.

The effects of solifenacin and mirabegron on vesical and urethral function were compared in rats with or without spinal cord injury (SCI). Isovolumetric cystometry and urethral pressure recording were initially performed in intact rats. Then, the bladder neck was ligated under urethane anesthesia, after which a catheter was inserted through the bladder dome for isovolumetric cystometry and another catheter was inserted into the urethra to measure urethral pressure. Solifenacin (0.03-3 mg/kg) or mirabegron (0.03-3 mg/kg) was injected intravenously, and bladder and urethral activity were recorded. To create rats with SCI, the spinal cord was transected at the lower thoracic level under isoflurane anesthesia. After 2 weeks, a catheter was inserted through the bladder dome for single cystometry and bladder activity was recorded without anesthesia following intravenous injection of solifenacin or mirabegron. Isovolumetric cystometry revealed a larger decrease in maximum bladder contraction pressure after injection of solifenacin, whereas prolongation of the interval between bladder contractions was greater with mirabegron. In SCI rats, single cystometry showed that solifenacin and mirabegron both increased bladder volume at the first non-voiding bladder contraction and decreased the maximum bladder contraction pressure. Mirabegron also increased the voided volume and decreased the percentage residual volume without altering bladder capacity. Solifenacin and mirabegron both inhibited bladder contractility, and mirabegron possibly also induced urethral relaxation. Mirabegron may be suitable for patients with overactive bladder and residual urine.

Further characterization of a novel EP2 and EP3 receptor dual agonist, ONO-8055, on lower urinary tract function in normal and lumbar canal stenosis rats.

AIMS: To further explore the effects of a novel EP2 and EP3 dual agonist, ONO-8055, on detrusor contractility, we investigated the responses of bladder strips from sham and lumbar canal stenosis (LCS) rats to this agonist, its effects on lower urinary tract function in normal rats, and mRNA expression of EP2 and EP3 receptors in the sham and LCS rats. METHODS: The responses of bladder strips from sham and LCS rats to ONO-8055 were measured. The effects of ONO-8055 on LUT function of normal rats were investigated with awake cystometry and intraurethral perfusion pressure (Pura) measurements. The relative mRNA of bladder and urethral tissue of the sham and LCS rats was quantified using specific probes for EP1, EP2, EP3, and EP4 genes. RESULTS: Compared with the vehicle, the muscle tensions of both the sham and LCS rats were significantly increased after adding this agonist. On awake cystometry of normal rats, bladder capacity and Pura were decreased in the ONO-8055 groups, but a statistically significant difference in mean changes was demonstrated only between the vehicle group and the group receiving the highest dose. Compared with the sham rats, mRNA expressions of the four EP receptors in the lower urinary tract of the LCS rats did not show a statistically significant difference. CONCLUSIONS: This agonist did not augment bladder contractility or urethral relaxation in normal rats.