External Urethral Sphincter Electromyography Research Articles

Contribution of pudendal nerve injury to stress urinary incontinence in a male rat model

Urinary incontinence is a common complication following radical prostatectomy, as the surgery disturbs critical anatomical structures. This study explored how pudendal nerve (PN) injury affects urinary continence in male rats. In an acute study, leak point pressure (LPP) and external urethral sphincter electromyography (EMG) were performed on six male rats with an intact urethra, the urethra exposed (UE), the PN exposed (NE), and after PN transection (PNT). In a chronic study, LPP and EMG were tested in 67 rats 4 days, 3 weeks, or 6 weeks after sham PN injury, PN crush (PNC), or PNT. Urethras were assessed histologically. Acute PNT caused a significant decrease in LPP and EMG amplitude and firing rate compared to other groups. PNC resulted in a significant reduction in LPP and EMG firing rate 4 days, 3 weeks, and 6 weeks later. EMG amplitude was also significantly reduced 4 days and 6 weeks after PNC. Neuromuscular junctions were less organized and less innervated after PNC or PNT at all timepoints compared to sham injured animals. Collagen infiltration was significantly increased after PNC and PNT compared to sham at all timepoints. This rat model could facilitate preclinical testing of neuroregenerative therapies for post-prostatectomy incontinence.

Sex differences in lower urinary tract function in mice with or without spinal cord injury.

We examined sex differences of lower urinary tract function and molecular mechanisms in mice with and without spinal cord injury (SCI). SCI was induced by Th8-9 spinal cord transection in male and female mice. We evaluated cystometrograms (CMG) and electromyography (EMG) of external urethral sphincter (EUS) at 6 weeks after SCI in spinal intact (SI) and SCI mice. The mRNA levels of Piezo2 and TRPV1 were measured in L6-S1 dorsal root ganglia (DRG). Protein levels of nerve growth factor (NGF) in the bladder mucosa was evaluated using an enzyme-linked immunosorbent assay. Sex differences were found in the EUS behavior during voiding as voiding events in female mice with or without SCI occurred during EUS relaxation periods without EUS bursting activity whereas male mice with or without SCI urinated during EUS bursting activity in EMG recordings. In both sexes, SCI decreased voiding efficiency along with increased tonic EUS activities evident as reduced EUS relaxation time in females and longer active periods of EUS bursting activity in males. mRNA levels of Piezo2 and TRPV1 of DRG in male and female SCI mice were significantly upregulated compared with SI mice. NGF in the bladder mucosa showed a significant increase in male and female SCI mice compared with SI mice. However, there were no significant differences in Piezo2 or TRPV1 levels in DRG or NGF protein levels in the bladder mucosa between male and female SCI mice. We demonstrated that female and male mice voided during EUS relaxation and EUS bursting activity, respectively. Also, upregulation of TRPV1 and Piezo2 in L6-S1 DRG and NGF in the bladder could be involved in SCI-induced lower urinary tract dysfunction in both sexes of mice.

Reflex voiding in rat occurs at consistent bladder volume regardless of pressure or infusion rate.

The central nervous system (CNS) regulates lower urinary tract reflexes using information from sensory afferents; however, the mechanisms of this process are not well known. Pressure and volume were measured at the onset of the guarding and micturition reflexes across a range of infusion rates to provide insight into what the CNS is gauging to activate reflexes. Female Sprague Dawley rats were anesthetized with urethane for open outlet cystometry. A set of 10 infusion rates (ranging 0.92-65.5 mL/h) were pseudo-randomly distributed across 30 single-fill cystometrograms. Bladder pressure and external urethral sphincter electromyography were used for the determination of the onset of the micturition and guarding reflexes, respectively. The bladder volume at the onset of both reflexes was estimated from the total infusion rate during a single fill. In response to many single-fill cystometrograms, there was an increased volume the bladder could store without a significant increase in pressure. Volume was adjusted for this effect for the analysis of how pressure and volume varied with infusion rate at the onset of the micturition and guarding reflexes. In 25 rats, the micturition reflex was evoked at similar volumes across all infusion rates, whereas the pressure at micturition reflex onset increased with increasing infusion rates. In 11 rats, the guarding reflex was evoked at similar pressures across infusion rates, but the volume decreased with increasing infusion rates. These results suggest that the CNS is interpreting volume from the bladder to activate the micturition reflex and pressure from the bladder to activate the guarding reflex.

Brain-Derived Neurotrophic Factor Is Indispensable to Continence Recovery after a Dual Nerve and Muscle Childbirth Injury Model.

In women, stress urinary incontinence (SUI), leakage of urine from increased abdominal pressure, is correlated with pudendal nerve (PN) injury during childbirth. Expression of brain-derived neurotrophic factor (BDNF) is dysregulated in a dual nerve and muscle injury model of childbirth. We aimed to use tyrosine kinase B (TrkB), the receptor of BDNF, to bind free BDNF and inhibit spontaneous regeneration in a rat model of SUI. We hypothesized that BDNF is essential for functional recovery from the dual nerve and muscle injuries that can lead to SUI. Female Sprague-Dawley rats underwent PN crush (PNC) and vaginal distension (VD) and were implanted with osmotic pumps containing saline (Injury) or TrkB (Injury + TrkB). Sham Injury rats received sham PNC + VD. Six weeks after injury, animals underwent leak-point-pressure (LPP) testing with simultaneous external urethral sphincter (EUS) electromyography recording. The urethra was dissected for histology and immunofluorescence. LPP after injury and TrkB was significantly decreased compared to Injury rats. TrkB treatment inhibited reinnervation of neuromuscular junctions in the EUS and promoted atrophy of the EUS. These results demonstrate that BDNF is essential to neuroregeneration and reinnervation of the EUS. Treatments aimed at increasing BDNF periurethrally could promote neuroregeneration to treat SUI.

Molecular Characterization of Non-Neurogenic and Neurogenic Lower Urinary Tract Dysfunction (LUTD) in SCI-Induced and Partial Bladder Outlet Obstruction Mouse Models.

We examined bladder function following spinal cord injury (SCI) by repeated urodynamic investigation (UDI), including external urethral sphincter (EUS) electromyography (EMG) in awake restrained mice and correlated micturition parameters to gene expression and morphological changes in the bladder. A partial bladder outlet obstruction (pBOO) model was used for comparison to elucidate both the common and specific features of obstructive and neurogenic lower urinary tract dysfunction (LUTD). Thirty female C57Bl/6J mice in each group received an implanted bladder catheter with additional electrodes placed next to the EUS in the SCI group. UDI assessments were performed weekly for 7 weeks (pBOO group) or 8 weeks (SCI group), after which bladders were harvested for histological and transcriptome analysis. SCI mice developed detrusor sphincter dyssynergia (DSD) one week after injury with high-pressure oscillations and a significantly increased maximal bladder pressure Pmax and were unable to void spontaneously during the whole observation period. They showed an increased bladder-to-bodyweight ratio, bladder fibrosis, and transcriptome changes indicative of extracellular matrix remodeling and alterations of neuronal signaling and muscle contraction. In contrast, pBOO led to a significantly increased Pmax after one week, which normalized at later time points. Increased bladder-to-bodyweight ratio and pronounced gene expression changes involving immune and inflammatory pathways were observed 7 weeks after pBOO. Comparative transcriptome analysis of SCI and pBOO bladders revealed the activation of Wnt and TGF-beta signaling in both the neurogenic and obstructive LUTD and highlighted FGF2 as a major upregulated transcription factor during organ remodeling. We conclude that SCI-induced DSD in mice leads to profound changes in neuronal signaling and muscle contractility, leading to bladder fibrosis. In a similar time frame, significant bladder remodeling following pBOO allowed for functional compensation, preserving normal micturition parameters.

Evaluation Methods of Detrusor Sphincter Dyssynergia in Spinal Cord Injury Patients: A Literature Review

Detrusor sphincter dyssynergia (DSD) is defined as an external urethral sphincter anomalous contraction concomitant to detrusor contraction during voiding, due to a neurological disease. It commonly occurs in suprasacral spinal cord-injured (SCI) patients and can be associated with autonomic dysreflexia. DSD generates risks to the urinary system and overall health; hence, it should be promptly diagnosed and managed. Bladder neck dyssynergia is a condition that should be integrated in DSD assessment. We reviewed the literature indexed in PubMed/Medline on the evaluation methods of DSD in SCI patients. Urodynamics is the mainstay evaluation method and has a prognostic value for the progression of upper urinary tract structural degradation and renal function decline. We found a lack of consensus on the optimal urodynamics configuration when evaluating DSD, especially in obtaining and measuring the signal from external urethral sphincter (EUS) activity. It appears that a combination of recordings of voiding cystourethrography and EUS electromyography, either with or without EUS pressure measurement, is the most accurate method available for evaluating DSD. While gathering articles, we came across an interesting approach in evaluating DSD in the past: urodynamics coupled with ultrasound imaging. Despite being considered valuable from a diagnostic standpoint by some prominent authors, it is no longer represented in the current literature. In addition to the instrumental diagnosis, health professionals should consider additional clinical features when evaluating and managing DSD in SCI patients, to design a customized plan to achieve the best compromise between quality of life and urinary system protection.

Early Transcutaneous Tibial Nerve Stimulation Acutely Improves Lower Urinary Tract Function in Spinal Cord Injured Rats.

Despite the fact that a majority of patients with an injury to the spinal cord develop lower urinary tract dysfunction, only few treatment options are available currently once the dysfunction arises. Tibial nerve stimulation has been used in pilot clinical trials, with some promising results. Hence, we investigated whether the early application of transcutaneous tibial nerve stimulation in the animal model of spinal cord injured rats can prevent the development of detrusor overactivity and/or detrusor-sphincter-dyssynergia. Rats were implanted with a bladder catheter and external urethral sphincter electromyography electrodes. A dorsal over-hemisection, resulting in an incomplete spinal cord injury at the T8/9 spinal level, induced immediate bladder paralysis. One week later, the animals received daily tibial nerve or sham stimulation for 15 days. Effects of stimulation on the lower urinary tract function were assessed by urodynamic investigation. Measurements showed improvements of several key parameters of lower urinary tract function—in particular, non-voiding bladder contractions and intravesical pressure—immediately after the completion of the stimulation period in the stimulated animals. These differences extinguished one week later, however. In the dorsal horn of the lumbosacral spinal cord, a small significant increase of the density of C-fiber afferents layers I-II was found in the stimulated animals at four weeks after spinal cord injury. Tibial nerve stimulation applied acutely after spinal cord injury in rats had an immediate beneficial effect on lower urinary tract dysfunction; however, the effect was transitory and did not last over time. To achieve more sustainable, longer lasting effects, further studies are needed looking into different stimulation protocols using optimized stimulation parameters, timing, and treatment schedules.

Slow development of bladder malfunction parallels spinal cord fiber sprouting and interneurons' loss after spinal cord transection

Neurogenic lower urinary tract dysfunction typically develops after spinal cord injury. We investigated the time course and the anatomical changes in the spinal cord that may be causing lower urinary tract symptoms following injury. Rats were implanted with a bladder catheter and external urethral sphincter electromyography electrodes. Animals underwent a large, incomplete spinal transection at the T8/9 spinal level. At 1, 2–3, and 4 weeks after injury, the animals underwent urodynamic investigations. Urodynamic investigations showed detrusor overactivity and detrusor-sphincter-dyssynergia appearing over time at 3–4 weeks after injury. Lower urinary tract dysfunction was accompanied by an increase in density of C-fiber afferents in the lumbosacral dorsal horn. CRF-positive Barrington's and 5-HT-positive bulbospinal projections drastically decreased after injury, with partial compensation for the CRF fibers at 3–4 weeks. Interestingly, a decrease over time was observed in the number of GABAergic neurons in the lumbosacral dorsal horn and lamina X, and a decrease of glutamatergic cells in the dorsal horn. Detrusor overactivity and detrusor-sphincter-dyssynergia might therefore arise from a discrepancy in inhibitory/excitatory interneuron activity in the lumbosacral cord as well as input changes which develop over time after injury. The processes point to spinal plastic changes leading to malfunction of the important physiological pathway of lower urinary tract control.

Transurethral versus suprapubic catheterization to test urethral function in rats

Transurethral and suprapubic catheterization have both been used to test urethral function in rats; however, it is unknown whether these methods affect urethral function or if the order of catheterization affects the results. The aim of this cross-over designed experiment was to compare the effects of catheterization methods and order on leak point pressure (LPP) testing. LPP and simultaneous external urethral sphincter electromyography (EUS EMG) were recorded in anesthetized female virgin Sprague-Dawley rats in a cross-over design to test the effects of transurethral and suprapubic catheterization. There was no significant difference in peak bladder pressure during LPP testing whether measured with a transurethral or suprapubic catheter. There was no significant difference in peak bladder pressure between the first and second catheter insertions. However, peak EMG firing rate, as well as peak EMG amplitude and EMG amplitude difference between peak and baseline were significantly higher after the first catheter insertion compared to the second insertion, regardless of the catheter method. Our results suggest that route of catheterization does not alter urethral function, e.g. create a functional partial outlet obstruction. Either catheterization method could be used for LPP and/or EUS EMG testing in rats.

Deciphering Spinal Endogenous Dopaminergic Mechanisms That Modulate Micturition Reflexes in Rats with Spinal Cord Injury.

Spinal neuronal mechanisms regulate recovered involuntary micturition after spinal cord injury (SCI). It was recently discovered that dopamine (DA) is synthesized in the rat injured spinal cord and is involved in lower urinary tract (LUT) activity. To fully understand the role of spinal DAergic machinery in micturition, we examined urodynamic responses in female rats during pharmacological modulation of the DA pathway. Three to four weeks after complete thoracic SCI, the DA precursor L-DOPA administered intravenously during bladder cystometrogram (CMG) and external urethral sphincter (EUS) electromyography (EMG) reduced bladder overactivity and increased the duration of EUS bursting, leading to remarkably improved voiding efficiency. Apomorphine (APO), a non-selective DA receptor (DR) agonist, or quinpirole, a selective DR2 agonist, induced similar responses, whereas a specific DR2 antagonist remoxipride alone had only minimal effects. Meanwhile, administration of SCH 23390, a DR1 antagonist, reduced voiding efficiency by increasing tonic EUS activity and shortening the EUS bursting period. Unexpectedly, SKF 38393, a selective DR1 agonist, increased EUS tonic activity, implying a complicated role of DR1 in LUT function. In metabolic cage assays, subcutaneous administration of quinpirole decreased spontaneous voiding frequency and increased voiding volume; L-DOPA and APO were inactive possibly because of slow entry into the CNS. Collectively, tonically active DR1 in SCI rats inhibit urine storage and enhance voiding by differentially modulating EUS tonic and bursting patterns, respectively, while pharmacologic activation of DR2, which are normally silent, improves voiding by enhancing EUS bursting. Thus, enhancing DA signaling achieves better detrusor-sphincter coordination to facilitate micturition function in SCI rats.

Brain derived neurotrophic factor mediates accelerated recovery of regenerative electrical stimulation in an animal model of stress urinary incontinence

ObjectiveStress urinary incontinence (SUI) is prevalent among older women and can result from insufficient regeneration of the pudendal nerve (PN). Electrical stimulation (ES) of the PN upregulates brain derived neurotrophic factor (BDNF) and accelerates regeneration. Using tyrosine kinase B (TrkB) to reduce the availability of free BDNF, the aim of this study was to determine if BDNF is necessary for accelerated recovery via ES in a model of SUI. MethodsOur SUI model consists of Female Sprague-Dawley rats, whose PNs were crushed bilaterally twice for 30 s, followed by insertion of a modified Foley catheter into the vagina with balloon inflation for 4 h. These rats were divided into 4 groups: 1) Sham PN crush and sham vaginal distension without electrode implantation and with saline treatment (sham injury); 2) SUI with sham stimulation and saline treatment (SUI); 3) SUI and ES with saline treatment (SUI&ES); and 4) SUI and ES with TrkB treatment (SUI&ES&TrkB). Animals underwent ES or sham stimulation four times a week for two weeks. Four weeks after injury, animals underwent functional testing consisting of leak point pressure (LPP) with simultaneous external urethral sphincter (EUS) electromyography (EMG) and pudendal nerve recordings. Data was analyzed using ANOVA with Holm-Sidak posthoc test (p < 0.05). EUS and PN specimen were sectioned and stained to semi-quantitatively evaluate morphology, regeneration, and reinnervation. ResultsLPP and EUS EMG firing rate were significantly increased in the sham injury and SUI&ES groups compared to the SUI and SUI&ES&TrkB groups. EUS of SUI rats showed few innervated neuromuscular junctions compared to sham injured rats, while both treatment groups showed an increase in reinnervated neuromuscular junctions. ConclusionES accelerates functional recovery via a BDNF-mediated pathway in a model of SUI. These findings suggest ES could be used as a potential regenerative therapy for women with SUI.

Bladder and bowel responses to lumbosacral epidural stimulation in uninjured and transected anesthetized rats

Spinal cord epidural stimulation (scES) mapping at L5-S1 was performed to identify parameters for bladder and bowel inhibition and/or contraction. Using spinally intact and chronic transected rats of both sexes in acute urethane-anesthetized terminal preparations, scES was systematically applied using a modified Specify 5–6–5 (Medtronic) electrode during bladder filling/emptying cycles while recording bladder and colorectal pressures and external urethral and anal sphincter electromyography activity. The results indicate frequency-dependent effects on void volume, micturition, bowel peristalsis, and sphincter activity just above visualized movement threshold intensities that differed depending upon neurological intactness, with some sex-dependent differences. Thereafter, a custom-designed miniature 15-electrode array designed for greater selectivity was tested and exhibited the same frequency-dependent urinary effects over a much smaller surface area without any concurrent movements. Thus, select activation of autonomic nervous system circuitries with scES is a promising neuromodulation approach for expedient translation to individuals with SCI and potentially other neurologic disorders.

Spinal Dopaminergic Mechanisms Regulating the Micturition Reflex in Male Rats with Complete Spinal Cord Injury.

Traumatic spinal cord injury (SCI) often causes micturition dysfunction. We recently discovered a low level of spinally-derived dopamine (DA) that regulates recovered bladder and sphincter reflexes in SCI female rats. Considering substantial sexual dimorphic features in the lower urinary tract, it is unknown if the DA-ergic mechanisms act in the male. Histological analysis showed a similar distribution of tyrosine hydroxylase (TH)+ neurons in the lower cord of male rats and the number increased following thoracic SCI. Subsequently, focal electrical stimulation in slices obtained from L6/S1 spinal segments of SCI rats elicited detectable DA release with fast scan cyclic voltammetry. Using bladder cystometrogram and external urethral sphincter (EUS) electromyography in SCI male rats, intravenous (i.v.) administration of SCH 23390, a D1-like receptor (DR1) antagonist, induced significantly increased tonic EUS activity and a trend of increased residual volume, whereas activation of these receptors with SKF 38393 did not influence the reflex. Meanwhile, blocking spinal D2-like receptors (DR2) with remoxipride had no effect but stimulating these receptors with quinpirole elicited EUS bursting to increase voiding volume. Further, intrathecal delivery of SCH 23390 and quinpirole resulted in similar responses to those with i.v. delivery, respectively, which indicates the central action regardless of delivery route. In addition, metabolic cage assays showed that quinpirole increased the voiding frequency and total voiding volume in spontaneous micturition. Collectively, spinal DA-ergic machinery regulates recovered micturition reflex following SCI in male rats; spinal DR1 tonically suppress tonic EUS activity to enable voiding and activation of DR2 facilitates voiding.

Delivery of the 5-HT2A Receptor Agonist, DOI, Enhances Activity of the Sphincter Muscle during the Micturition Reflex in Rats after Spinal Cord Injury.

Simple SummarySpinal cord injury often disrupts connections between the brain and spinal cord leading to a plethora of health complications, including bladder dysfunction. Spinal cord injured patients are left with symptoms such as a leaky bladder (the inability to hold their urine), frequent urinary tract infections, and potential kidney failure. However, previous studies have shown that manipulation of serotoninergic receptors can improve urinary performance following spinal cord injury. In the current study, we sought to explore how stimulation of a specific serotonergic receptor subtype can significantly enhance bladder function in spinal cord injured rats. To do so, we utilized spinal cord injured female rats that underwent various bladder performance evaluations combined with pharmacological intervention of a specific serotonergic subtype. Additionally, the primary site of action was investigated to determine effects elicited during various administration routes (e.g., directly into the cord, into the femoral vein, or into the skin). Stimulation of this receptor subtype, regardless of delivery route, improved activity of the external urethral sphincter and detrusor-sphincter coordination in spinal cord injured rats. Collectively, the results of these experiments have the potential to provide vital guidance for the development of therapeutic strategies to alleviate urinary dysfunction following spinal cord injury.Traumatic spinal cord injury (SCI) interrupts spinobulbospinal micturition reflex pathways and results in urinary dysfunction. Over time, an involuntary bladder reflex is established due to the reorganization of spinal circuitry. Previous studies show that manipulation of serotonin 2A (5-HT2A) receptors affects recovered bladder function, but it remains unclear if this receptor regulates the activity of the external urethral sphincter (EUS) following SCI. To elucidate how central and peripheral serotonergic machinery acts on the lower urinary tract (LUT) system, we employed bladder cystometry and EUS electromyography recordings combined with intravenous or intrathecal pharmacological interventions of 5-HT2A receptors in female SCI rats. Three to four weeks after a T10 spinal transection, systemic and central blockage of 5-HT2A receptors with MDL only slightly influenced the micturition reflex. However, delivery of the 5-HT2A receptor agonist, DOI, increased EUS tonic activity and elicited bursting during voiding. Additionally, subcutaneous administration of DOI verified the enhancement of continence and voiding capability during spontaneous micturition in metabolic cage assays. Although spinal 5HT2A receptors may not be actively involved in the recovered micturition reflex, stimulating this receptor subtype enhances EUS function and the synergistic activity between the detrusor and sphincter to improve the micturition reflex in rats with SCI.

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

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

Efficacy of Deep Brain Stimulation on the Improvement of the Bladder Functions in Traumatic Brain Injured Rats

Objective: Traumatic brain injuries (TBIs) are a prime public health challenge with a high incidence of mortality, and also reflect severe economic impacts. One of their severe symptoms is bladder dysfunction. Conventional therapeutic methods are not effective in managing bladder dysfunction. Henceforth, a research endeavor was attempted to explore a new therapeutic approach for bladder dysfunction through deep brain stimulation (DBS) procedures in a TBI animal model. Methods: TBI in this animal model was induced by the weight-drop method. All rats with an induced TBI were housed for 4 weeks to allow severe bladder dysfunction to develop. Subsequently, an initial urodynamic measurement, the simultaneous recording of cystometric (CMG) and external urethral sphincter electromyography (EUS-EMG) activity was conducted to evaluate bladder function. Further, standard DBS procedures with varying electrical stimulation parameters were executed in the target area of the pedunculopontine tegmental nucleus (PPTg). Simultaneously, urodynamic measurements were re-established to compare the effects of DBS interventions on bladder functions. Results: From the variable combinations of electrical stimulation, DBS at 50 Hz and 2.0 V, significantly reverted the voiding efficiency from 39% to 69% in TBI rats. Furthermore, MRI studies revealed the precise localization of the DBS electrode in the target area. Conclusions: The results we obtained showed an insightful understanding of PPTg-DBS and its therapeutic applications in alleviating bladder dysfunction in rats with a TBI. Hence, the present study suggests that PPTg-DBS is an effective therapeutic strategy for treating bladder dysfunction.

Combined Treatment With CCR1-Overexpressing Mesenchymal Stem Cells and CCL7 Enhances Engraftment and Promotes the Recovery of Simulated Birth Injury-Induced Stress Urinary Incontinence in Rats.

Objective: To observe whether urethral injection of chemokine (c-c motif) ligand 7 (CCL7) and overexpressing CC receptor 1 (CCR1) in mesenchymal stem cells (MSCs) can promote their homing and engraftment to the injured tissue, and improve the recovery of simulated birth injury-induced stress urinary incontinence (SUI) in rats.Methods: Female rats underwent a dual injury consisting of vaginal distension (VD) and pudendal nerve crush (PNC) to induce SUI. Bone marrow-derived MSCs were transduced with lentivirus carrying CCR1 (MSC-CCR1) and green fluorescent protein (GFP). Forty virgin Sprague–Dawley rats were evenly distributed into four groups: sham SUI + MSC-CCR1+CCL7, SUI + MSCs, SUI + MSC-CCR1, and SUI + MSC-CCR1+CCL7 group. The engrafted MSCs in urethra were quantified. Another three groups of rats, including sham SUI + sham MSC-CCR1+CCL7 treatment, SUI + sham MSC-CCR1+CCL7 treatment, and SUI + MSC-CCR1+CCL7 treatment group, were used to evaluate the functional recovery by testing external urethral sphincter electromyography (EUS EMG), pudendal nerve motor branch potentials (PNMBP), and leak point pressure (LPP) 1 week after injury and injection. Urethra and vagina were harvested for histological examination.Results: The SUI + MSC-CCR1+CCL7 group received intravenous injection of CCR1-overexpressing MSCs and local injection of CCL7 after simulated birth injury had the most engraftment of MSCs to the injured tissues and best functional recovery from SUI compared to other groups. Histological examination showed a partial repair in the SUI + MSC-CCR1+CCL7 group.Conclusions: Our study demonstrated combined treatment with CCR1-overexpressing MSCs and CCL7 can increase engraftment of MSCs and promote the functional recovery of simulated birth trauma-induced SUI in rats, which could be a new therapeutic strategy for SUI.

Therapeutic potential of muscle growth promoters in a stress urinary incontinence model.

Weakness of urinary sphincter and pelvic floor muscles can cause insufficient urethral closure and lead to stress urinary incontinence. Bimagrumab is a novel myostatin inhibitor that blocks activin type II receptors, inducing skeletal muscle hypertrophy and attenuating muscle weakness. β2-Adrenergic agonists, such as 5-hydroxybenzothiazolone derivative (5-HOB) and clenbuterol, can enhance muscle growth. We hypothesized that promoting muscle growth would increase leak point pressure (LPP) by facilitating muscle recovery in a dual-injury (DI) stress urinary incontinence model. Rats underwent pudendal nerve crush (PNC) followed by vaginal distension (VD). One week after injury, each rat began subcutaneous (0.3 mL/rat) treatment daily in a blinded fashion with either bimagrumab (DI + Bim), clenbuterol (DI + Clen), 5-HOB (DI + 5-HOB), or PBS (DI + PBS). Sham-injured rats underwent sham PNC + VD and received PBS (sham + PBS). After 2 wk of treatment, rats were anesthetized for LPP and external urethral sphincter electromyography recordings. Hindlimb skeletal muscles and pelvic floor muscles were dissected and stained. At the end of 2 wk of treatment, all three treatment groups had a significant increase in body weight and individual muscle weight compared with both sham-treated and sham-injured rats. LPP in DI + Bim rats was significantly higher than LPP of DI + PBS and DI + Clen rats. There were more consistent urethral striated muscle fibers, elastin fibers in the urethra, and pelvic muscle recovery in DI + Bim rats compared with DI + PBS rats. In conclusion, bimagrumab was the most effective for increasing urethral pressure and continence by promoting injured external urethral sphincter and pelvic floor muscle recovery.

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.

Role of p38 MAP kinase signaling pathways in storage and voiding dysfunction in mice with spinal cord injury.

To investigate the role of p38 MAP kinase in lower urinary tract dysfunction in mice with spinal cord injury (SCI). Cystometry and external urethral sphincter-electromyography were performed under an awake condition in 4-week SCI female mice. Two weeks after SCI, a catheter connected to an osmotic pump filled with a p38 mitogen-activated protein kinase (MAPK) inhibitor or artificial cerebrospinal fluid (CSF) was implanted into the intrathecal space of L6-S1 spinal cord for continuous intrathecal instillation at infusion rate of 0.51 μL/h for 2 weeks before the urodynamic study. L6 dorsal root ganglia were then removed from CSF and p38 MAPK inhibitor-treated SCI mice as well as from CSF-treated normal (spinal intact) mice to evaluate the levels of transient receptor potential cation channel subfamily V member 1 (TRPV1), tumor necrosis factor-α (TNF-α), and inducible nitric oxide synthase (iNOS) transcripts by real-time polymerase chain reaction. In p38 MAPK inhibitor-treated SCI mice, nonvoiding contractions during bladder filling, bladder capacity, and post-void residual volume were significantly reduced while micturition pressure and voiding efficiency were significantly increased in comparison to these measurements in CSF-treated SCI mice. The expression of TRPV1, TNF-α, and iNOS messenger RNA was increased in SCI mice compared with expression in spinal intact mice and significantly decreased after p38 MAPK inhibitor treatment. The p38 MAPK signaling pathway in bladder sensory neurons or in the spinal cord plays an important role in storage and voiding problems such as detrusor overactivity and inefficient voiding after SCI.