Publications by authors named "William C de Groat"

287 Publications

Superficial Peroneal Neuromodulation of Persistent Bladder Underactivity Induced by Prolonged Pudendal Afferent Nerve Stimulation in Cats.

Am J Physiol Regul Integr Comp Physiol 2021 Mar 10. Epub 2021 Mar 10.

University of Pittsburgh.

The purpose of this study is to determine if superficial peroneal nerve stimulation (SPNS) can reverse persistent bladder underactivity induced by prolonged pudendal nerve stimulation (PNS). In 16 α-chloralose anesthetized cats, PNS and SPNS were applied by nerve cuff electrodes. Skin surface electrodes were also used for SPNS. Bladder underactivity consisting of a significant increase in bladder capacity to 157.8±10.9% of control and a significant reduction in bladder contraction amplitude to 56.0±5.0% of control was induced by repetitive (4-16 times) application of 30-min PNS. SPNS (1 Hz, 0.2 ms) at 1.5 to 2 times threshold intensity (T) for inducing posterior thigh muscle contractions was applied either continuously (SPNSc) or intermittently (SPNSi) during a cystometrogram (CMG) to determine if the stimulation can reverse the PNS-induced bladder underactivity. SPNSc or SPNSi applied by nerve cuff electrodes during the prolonged PNS inhibition significantly reduced bladder capacity to 124.4±10.7% and 132.4±14.2% of control, respectively, and increased contraction amplitude to 85.3±6.2% and 75.8±4.7%, respectively. Transcutaneous SPNSc and SPNSi also significantly reduced bladder capacity and increased contraction amplitude. Additional PNS applied during the bladder underactivity further increased bladder capacity, while SPNSc applied simultaneously with the PNS reversed the increase in bladder capacity. This study indicates that a non-invasive superficial peroneal neuromodulation therapy might be developed to treat bladder underactivity caused by abnormal pudendal nerve somatic afferent activation that is hypothesized to occur in patients with Fowler's syndrome.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajpregu.00346.2020DOI Listing
March 2021

Restoring both continence and micturition after chronic spinal cord injury by pudendal neuromodulation.

Exp Neurol 2021 Feb 24;340:113658. Epub 2021 Feb 24.

Department of Urology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA. Electronic address:

Neurogenic bladder management after spinal cord injury (SCI) is very challenging. Daily urethral catheterization is most commonly used to empty the bladder, which causes frequent infections of the lower urinary tract. This study reports a novel idea to restore both continence and micturition after SCI by an implantable pudendal nerve stimulator (PNS). The PNS was surgically implanted in four cats with complete SCI at T9-T10 spinal level and tested weekly for 13-14 weeks under awake conditions. These chronic SCI cats consistently exhibited large residual bladder volumes (average 40-50 ml) due to their inability to void efficiently, while urine leakage also occurred frequently. The PNS which consisted of stimulating the pudendal nerve at 20-30 Hz to trigger a spinal reflex bladder contraction and at the same time blocking the pudendal nerves bilaterally with 10 kHz stimulation to relax the external urethral sphincter and reduce the urethral outlet resistance successfully induced highly efficient (average 80-100%), low pressure (<50 cmHO) voiding. The PNS at 5 Hz also promoted urine storage by inhibiting reflex bladder activity and increasing bladder capacity. At the end of 14-week chronic testing, low pressure efficient voiding induced by PNS was further confirmed under anesthesia by directly measuring voiding pressure using a bladder catheter inserted through the bladder dome. This study demonstrated the efficacy and safety of the PNS in awake chronic SCI cats, suggesting that a novel neuroprosthesis can be developed for humans to restore bladder function after SCI by stimulating and/or blocking the pudendal nerves.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.expneurol.2021.113658DOI Listing
February 2021

Prostate-Specific Deletion of Cdh1 Induces Murine Prostatic Inflammation and Bladder Overactivity.

Endocrinology 2021 01;162(1)

Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.

Benign prostatic hyperplasia (BPH) is an age-related debilitating prostatic disease that is frequently associated with prostatic inflammation and bothersome lower urinary tract symptoms (LUTS). Animal models have shown that formalin- and bacterial-induced prostatic inflammation can induce bladder dysfunction; however, the underlying mechanisms contributing to prostatic inflammation in BPH and bladder dysfunction are not clear. We previously reported that E-cadherin expression in BPH is downregulated in hyperplastic nodules compared with expression in adjacent normal tissues. Here, we explored the potential consequences of prostatic E-cadherin downregulation on the prostate and bladder in vivo using an inducible murine model of prostate luminal epithelial-specific deletion of Cdh1. The prostate-specific antigen (PSA)-CreERT2 transgenic mouse strain expressing tamoxifen-inducible CreERT2 recombinase driven by a 6-kb human PSA promoter/enhancer was crossed with the B6.129-Cdh1tm2Kem/J mouse to generate bigenic PSA-CreERT2/Cdh1-/- mice. Deletion of E-cadherin was induced by transient administration of tamoxifen when mice reached sexual maturity (7 weeks of age). At 21 to 23 weeks of age, the prostate, bladder, and prostatic urethra were examined histologically, and bladder function was assessed using void spot assays and cystometry. Mice with Cdh1 deletion had increased prostatic inflammation, prostatic epithelial hyperplasia, and stromal changes at 21 to 23 weeks of age, as well as changes in bladder voiding function compared with age-matched controls. Thus, loss of E-cadherin in the murine prostate could result in prostatic defects that are characteristic of BPH and LUTS, suggesting that E-cadherin downregulation could be a driving force in human BPH development and progression.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1210/endocr/bqaa212DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7745638PMC
January 2021

Bladder underactivity induced by prolonged pudendal afferent activity in cats.

Am J Physiol Regul Integr Comp Physiol 2021 01 4;320(1):R80-R87. Epub 2020 Nov 4.

Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania.

The purpose of this study was to determine the effects of pudendal nerve stimulation (PNS) on reflex bladder activity and develop an animal model of underactive bladder (UAB). In six anesthetized cats, a bladder catheter was inserted via the urethra to infuse saline and measure pressure. A cuff electrode was implanted on the pudendal nerve. After determination of the threshold intensity (T) for PNS to induce an anal twitch, PNS (5 Hz, 0.2 ms, 2 T or 4 T) was applied during cystometrograms (CMGs). PNS (4-6 T) of 30-min duration was then applied repeatedly until bladder underactivity was produced. Following stimulation, control CMGs were performed over 1.5-2 h to determine the duration of bladder underactivity. When applied during CMGs, PNS (2 T and 4 T) significantly ( < 0.05) increased bladder capacity while PNS at 4 T also significantly ( < 0.05) reduced bladder contraction amplitude, duration, and area under contraction curve. Repeated application of 30-min PNS for a cumulative period of 3-8 h produced bladder underactivity exhibiting a significantly ( < 0.05) increased bladder capacity (173 ± 14% of control) and a significantly ( < 0.05) reduced contraction amplitude (50 ± 7% of control). The bladder underactivity lasted more than 1.5-2 h after termination of the prolonged PNS. These results provide basic science evidence supporting the proposal that abnormal afferent activity from external urethral/anal sphincter could produce central inhibition that underlies nonobstructive urinary retention (NOUR) in Fowler's syndrome. This cat model of UAB may be useful to investigate the mechanism by which sacral neuromodulation reverses NOUR in Fowler's syndrome.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajpregu.00239.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7847056PMC
January 2021

Poststimulation Block of Pudendal Nerve Conduction by High-Frequency (kHz) Biphasic Stimulation in Cats.

Neuromodulation 2020 Aug 5;23(6):747-753. Epub 2019 Nov 5.

Department of Urology, University of Pittsburgh, Pittsburgh, PA, USA.

Objective: To determine the relationship between various parameters of high-frequency biphasic stimulation (HFBS) and the recovery period of post-HFBS block of the pudendal nerve in cats.

Materials And Methods: A tripolar cuff electrode was implanted on the pudendal nerve to deliver HFBS in ten cats. Two hook electrodes were placed central or distal to the cuff electrode to stimulate the pudendal nerve and induce contractions of external urethral sphincter (EUS). A catheter was inserted toward the distal urethra to slowly perfuse the urethra and record the back-up pressure generated by EUS contractions. After determining the block threshold (T), HFBS (6 or 10 kHz) of different durations (1, 5, 10, 20, 30 min) and intensities (1T or 2T) was used to produce the post-HFBS block.

Results: HFBS at 10 kHz and 1T intensity must be applied for at least 30 min to induce post-HFBS block. However, 10 kHz HFBS at a higher intensity (2T) elicited post-HFBS block after stimulation of only 10 min; and 10 kHz HFBS at 2T for 30 min induced a longer-lasting (1-3 h) post-HFBS block that fully recovered with time. HFBS of 5-min duration at 6 kHz produced a longer period (20.4 ± 2.1 min, p < 0.05, N = 5 cats) of post-HFBS block than HFBS at 10 kHz (9.5 ± 2.1 min).

Conclusion: HFBS of longer duration, higher intensity, and lower frequency can produce longer-lasting reversible post-HFBS block. This study is important for developing new methods to block nerve conduction by HFBS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/ner.13060DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7447838PMC
August 2020

Effects of a new β3-adrenoceptor agonist, vibegron, on neurogenic bladder dysfunction and remodeling in mice with spinal cord injury.

Neurourol Urodyn 2020 11 20;39(8):2120-2127. Epub 2020 Aug 20.

Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania.

Aims: To examine vibegron effects on lower urinary tract dysfunction (LUTD) in mice with spinal cord injury (SCI).

Methods: Female mice underwent Th8-9 spinal cord transection and were orally administered vehicle or vibegron after SCI. We evaluated urodynamic parameters at 4 weeks after SCI with or without vibegron. Fibrosis- and ischemia-related messenger RNA (mRNA) and protein levels of collagen and elastin were measured in bladders of vehicle- and vibegron-treated SCI mice, and spinal intact mice.

Results: Non-voiding contractions (NVCs) were significantly fewer (15.3 ± 8.9 vs 29.7 ± 11.4 contractions; P < .05) and the time to the first NVC was significantly longer (1488.0 ± 409.5 vs 782.7 ± 399.7 seconds; P < .01) in vibegron-treated SCI mice vs vehicle-treated SCI mice. mRNAs levels of collagen types 1 and 3, transforming growth factor-β1 (TGF-β1), and hypoxia-inducible factor-1α (HIF-1α) were significantly upregulated in vehicle-treated SCI mice compared with spinal intact and vibegron-treated SCI mice (Col 1: 3.5 vs 1.0 and 2.0-fold; P < .01 and P < .05, Col 3: 2.1 vs 1.0 and 1.2-fold; P < .01 and P < .05, TGF-β1: 1.2 vs 1.0 and 0.9-fold; P < .05 and P < .05, HIF-1α: 1.4 vs 1.0 and 1.0-fold; P < .05 and P < .01). Total collagen and elastin protein levels in vehicle- and vibegron-treated SCI mice did not differ.

Conclusions: Vibegron reduced NVCs, delayed the first NVC, and improved collagen types 1 and 3, TGF-β1, and HIF-1α mRNA expression in SCI mice. Vibegron might be effective for SCI-induced LUTD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/nau.24486DOI Listing
November 2020

Superficial peroneal neuromodulation of nonobstructive urinary retention in cats.

Neurourol Urodyn 2020 08 16;39(6):1679-1686. Epub 2020 Jun 16.

Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania.

Aims: To determine if superficial peroneal nerve stimulation (SPNS) can improve nonobstructive urinary retention (NOUR).

Methods: In α-chloralose anesthetized cats, NOUR was induced by repetitive application (4-16 times) of 30-minute tibial nerve stimulation (TNS: 5 Hz frequency, 0.2 ms pulse width) at 4 to 6 times threshold intensity (T) for inducing toe twitches. SPNS (1 Hz, 0.2 ms) at 2 to 4 times threshold intensity (T) for inducing posterior thigh muscle contractions was applied either continuously (SPNSc) during a cystometrogram (CMG) or during voiding (SPNSv) by a surgically implanted cuff electrode or by skin surface electrodes to determine if the stimulation reduced NOUR induced by prolonged TNS.

Results: During control CMGs, efficient (86.4% ± 5.5%) voiding occurred with a postvoid residual (PVR) volume equal to 14.9% ± 6.2% of control bladder capacity. NOUR elicited by prolonged TNS significantly (P < .05) increased bladder capacity to 168.6% ± 15.5% of control, reduced voiding efficiency to 30.4% ± 4.8%, and increased PVR to 109% ± 9.2% of control. Using the implanted cuff electrode, SPNSc and SPNSv significantly (P < .05) increased voiding efficiency to 66.7% ± 7.4% and 65.0% ± 5.9%, respectively, and reduced PVR to 52.2% ± 11.4% and 64.3% ± 11.6%, respectively. SPNSc but not SPNSv significantly (P < .05) reduced bladder capacity to 133.4% ± 15% of control. Transcutaneous SPNSv but not SPNSc also significantly (P < .05) reversed the TNS-induced NOUR responses.

Conclusions: This study shows that SPNS is effective in reversing NOUR induced by prolonged TNS. Transcutaneous SPNS provides the opportunity to develop a noninvasive neuromodulation therapy for NOUR to treat more patients than current sacral neuromodulation therapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/nau.24438DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7927909PMC
August 2020

LPS-mediated release of ATP from urothelial cells occurs by lysosomal exocytosis.

Neurourol Urodyn 2020 06 6;39(5):1321-1329. Epub 2020 May 6.

Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.

Background: While numerous studies have confirmed ATP's importance in bladder physiology/pathophysiology, the literature is still conflicted regarding the mechanism of ATP release from the urothelium. Multiple mechanisms have been identified including non-vesicular release via pannexin channels as well as vesicular release via a mechanism blocked by botulinum toxin. Recently, it has been shown that lysosomes contain significant stores of ATP which can be released extracellularly in response to Toll-like receptor (TLR) stimulation.

Objective: The goal of the current study was to determine if lysosomal exocytosis occurs in urothelial cells in response to TLR4 stimulation by its agonist, bacterial lipopolysaccharide (LPS).

Materials And Methods: Human urothelial cells from an immortalized cell line (TRT-HU1) were treated with bacterial LPS (100 μg/ml) or the nicotinic agoinist cytisine (100 μM) and extracellular release of ATP and lysosomal acid phosphatase were measured. Pannexin-mediated ATP release and lysosomal ATP release were differentiated using Brilliant Blue FCF to inhibit pannexin channels and glycyl-l-phenylalanine-β-naphthylamide (GPN) to destroy lysosomes. The mechanisms controlling lysosomal exocytosis were examined using lysosomal pH measurements using LysoSensor dye and intracellular calcium signaling using Fura-2.

Results: Stimulation of TRT-HU1 cells with LPS significantly increased ATP release, which was inhibited by GPN, but not by Brilliant Blue FCF. Conversely, stimulation with cytisine induced ATP release that was sensitive to Brilliant Blue FCF but not GPN. LPS stimulation also induced the release of the lysosomal acid phosphatases. LPS increased lysosomal pH and direct alkalization of lysosomal pH using chloroquine or bafilomycin A1 induced ATP and acid phosphatase release, indicating an important role for pH in lysosomal exocytosis. Additionally, stimulation of lysosomal transient receptor potential mucolipin 1 calcium channels evoked intracellular calcium transients as well as ATP release.

Conclusion: These data indicate that LPS-induced ATP release from urothelial cells is mediated by lysosomal exocytosis, a vesicular mechanism distinctly separate from non-vesicular release via pannexin channels.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/nau.24377DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7304540PMC
June 2020

Thermal block of mammalian unmyelinated C fibers by local cooling to 15-25°C after a brief heating at 45°C.

J Neurophysiol 2020 06 6;123(6):2173-2179. Epub 2020 May 6.

Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania.

The purpose of this study was to examine the changes in cold block of unmyelinated C fibers in the tibial nerve by preconditioning with heating and to develop a safe method for thermal block of C-fiber conduction. In seven cats under α-chloralose anesthesia, C-fiber-evoked potentials elicited by electrical stimulation were recorded on the tibial nerve during block of axonal conduction induced by exposing a small segment (9 mm) of the nerve to cooling (from 35°C to ≤5°C) or heating (45°C). Before heating, partial, reproducible, and reversible cold block was first detected at a threshold cold block temperature of 15°C and complete cold block occurred at a temperature of ≤5°C. After the nerve was heated at 45°C for 5-35 min, the threshold cold block temperature significantly ( < 0.05) increased from 15°C to 25°C and the complete cold block temperature significantly ( < 0.05) increased from ≤5°C to 15°C on average. The increased cold block temperatures persisted for the duration of the experiments (30-100 min) while the amplitude of the C-fiber-evoked potential measured at 35°C recovered significantly ( < 0.05) to ~80% of control. This study discovered a novel thermal method to block mammalian C fibers at an elevated temperature (15-25°C), providing the opportunity to develop a thermal nerve block technology to suppress chronic pain of peripheral origin. The interaction between heating and cooling effects on C-fiber conduction indicates a possible interaction between different temperature-sensitive channels known to be present in the mammalian C fibers. Our study discovered that the temperature range for producing a partial to complete cold block of mammalian C-fiber axons can be increased from 5-15°C to 15-25°C on average after a preheating at 45°C. This discovery raises many basic scientific questions about the influence of temperature on nerve conduction and block. It also raises the possibility of developing a novel implantable nerve block device to treat many chronic diseases including chronic pain.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/jn.00133.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7311731PMC
June 2020

Response of hypogastric afferent fibers to bladder distention or irritation in cats.

Exp Neurol 2020 07 3;329:113301. Epub 2020 Apr 3.

Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA. Electronic address:

The goal of this study in anesthetized cats was to identify silent hypogastric nerve (HGN) afferent fibers that do not respond to bladder distention but become responsive after chemical irritation of the bladder. The HGN was split into multiple filaments small enough for recording action potentials from single or multiple afferent fibers. The bladder was distended by infusion of either saline or 0.5% acetic acid (AA) through a urethral catheter while recording intravesical pressure. A total of 90 HGN filaments from 17 cats responded to bladder distention with saline or AA. Three types of HGN afferents were identified. The first type was non-nociceptive mechano-sensitive that responded to bladder distention at normal physiological pressures (10-40 cmHO). The second type was nociceptive mechano-sensitive that only responded to high-pressure (50-80 cmHO) bladder distention with saline but responded to low-pressure bladder distention after sensitization with AA. The third type was chemo-sensitive nociceptive that was silent even during high-pressure bladder distention but after sensitization with AA did respond to low-pressure bladder distention. These results indicate that HGN afferents as well as pelvic nerve afferents may play a role in bladder nociception. The HGN afferent fibers that are silent during bladder distention at normal physiological pressures but become responsive after chemical irritation are important for understanding the possible pathophysiological mechanism underlying bladder allodynia in painful bladder syndrome.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.expneurol.2020.113301DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7237284PMC
July 2020

Additive Inhibition of Reflex Bladder Activity Induced by Bilateral Pudendal Neuromodulation in Cats.

Front Neurosci 2020 7;14:80. Epub 2020 Feb 7.

Department of Urology, University of Pittsburgh, Pittsburgh, PA, United States.

Objective: To determine the inhibitory effect on bladder activity induced by bilateral pudendal neuromodulation.

Methods: In 10 cats under anesthesia, two tripolar cuff electrodes were implanted bilaterally on the pudendal nerves for stimulation. A double lumen catheter was inserted into the bladder through the urethra to infuse saline and measure bladder pressure. During repeated cystometrograms (CMGs) pudendal nerve stimulation (PNS: 5 Hz, 0.2 ms, 5-15 min) was applied unilaterally or bilaterally at 1- or 2-times intensity threshold () for inducing anal sphincter twitching. PNS inhibition was indicated by the increase in bladder capacity measured by CMGs.

Results: Unilateral PNS at 1T did not significantly increase bladder capacity, but at 2T significantly ( < 0.05) increased bladder capacity by about 30%. Bilateral PNS at 1T also failed to increase bladder capacity, but at 2T significantly ( < 0.05) increased bladder capacity by about 60%, indicating an additive effect induced by the bilateral 2T PNS. Unilateral 1T PNS did not enhance the inhibitory effect induced by contra-lateral 2T PNS.

Conclusion: This study in anesthetized cats reveals that an additive inhibition of reflex bladder activity can be induced by bilateral pudendal neuromodulation, indicating that bilateral PNS might achieve better therapeutic efficacy in treating overactive bladder (OAB) than unilateral PNS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fnins.2020.00080DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7020809PMC
February 2020

Prolonged nonobstructive urinary retention induced by tibial nerve stimulation in cats.

Am J Physiol Regul Integr Comp Physiol 2020 02 8;318(2):R428-R434. Epub 2020 Jan 8.

Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania.

Nonobstructive urinary retention (NOUR) is a medical condition without an effective drug treatment, but few basic science studies have focused on this condition. In α-chloralose-anesthetized cats, the bladder was cannulated via the dome and infused with saline to induce voiding that could occur without urethral outlet obstruction. A nerve cuff electrode was implanted for tibial nerve stimulation (TNS). The threshold (T) intensity for TNS to induce toe twitch was determined initially. Repeated (6 times) application of 30-min TNS (5 Hz, 0.2 ms, 4-6T) significantly ( < 0.05) increased bladder capacity to 180% of control and reduced the duration of the micturition contraction to 30% of control with a small decrease in contraction amplitude (80% of control), which resulted in urinary retention with a low-voiding efficiency of 30% and a large amount of residual volume equivalent to 130% of control bladder capacity. This NOUR condition persisted for >2 h after the end of repeated TNS. However, lower frequency TNS (1 Hz, 0.2 ms, 4T) applied during voiding partially reversed the NOUR by significantly ( < 0.05) increasing voiding efficiency to 60% and reducing residual volume to 70% of control bladder capacity without changing bladder capacity. These results revealed that tibial nerve afferent input can activate either an excitatory or an inhibitory central nervous system mechanism depending on afferent firing frequencies (1 vs. 5 Hz). This study established the first NOUR animal model that will be useful for basic science research aimed at developing new treatments for NOUR.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajpregu.00277.2019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7052595PMC
February 2020

Propriospinal Neurons of L3-L4 Segments Involved in Control of the Rat External Urethral Sphincter.

Neuroscience 2020 01 27;425:12-28. Epub 2019 Nov 27.

Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15213, United States.

Coordination of activity of external urethral sphincter (EUS) striated muscle and bladder (BL) smooth muscle is essential for efficient voiding. In this study we examined the morphological and electrophysiological properties of neurons in the L3/L4 spinal cord (SC) that are likely to have an important role in EUS-BL coordination in rats. EUS-related SC neurons were identified by retrograde transsynaptic tracing following injection of pseudorabies virus (PRV) co-expressing fluorescent markers into the EUS of P18-P20 male rats. Tracing revealed not only EUS motoneurons in L6/S1 but also interneurons in lamina X of the L6/S1 and L3/L4 SC. Physiological properties of fluorescently labeled neurons were assessed during whole-cell recordings in SC slices followed by reconstruction of biocytin-filled neurons. Reconstructions of neuronal processes from transverse or longitudinal slices showed that some L3/L4 neurons have axons projecting toward and into the ventro-medial funiculus (VMf) where axons extended caudally. Other neurons had axons projecting within laminae X and VII. Dendrites of L3/L4 neurons were distributed within laminae X and VII. The majority of L3/L4 neurons exhibited tonic firing in response to depolarizing currents. In transverse slices focal electrical stimulation (FES) in the VMf or in laminae X and VII elicited antidromic axonal spikes and/or excitatory synaptic responses in L3/L4 neurons; while in longitudinal slices FES elicited excitatory synaptic inputs from sites up to 400 μm along the central canal. Inhibitory inputs were rarely observed. These data suggest that L3/L4 EUS-related circuitry consists of at least two neuronal populations: segmental interneurons and propriospinal neurons projecting to L6/S1.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.neuroscience.2019.11.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6955099PMC
January 2020

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

Neurourol Urodyn 2020 01 3;39(1):108-115. Epub 2019 Oct 3.

Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania.

Aim: To investigate the role of p38 MAP kinase in lower urinary tract dysfunction in mice with spinal cord injury (SCI).

Methods: 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.

Results: 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.

Conclusions: 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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/nau.24170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7528979PMC
January 2020

Therapeutic effects of inhibition of brain-derived neurotrophic factor on voiding dysfunction in mice with spinal cord injury.

Am J Physiol Renal Physiol 2019 11 30;317(5):F1305-F1310. Epub 2019 Sep 30.

Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.

We investigated the involvement of brain-derived neurotrophic factor (BDNF) in bladder and urethral dysfunction using spinal cord-injured mice. We evaluated bladder and urethral function of female mice with 4-wk spinal cord injury (SCI) by filling cystometry and electromyography (EMG) of the external urethral sphincter (EUS) under a conscious condition. Anti-BDNF antibodies (10 μg·kg·h) were administered in some mice for 1 wk before the evaluation. Bladder and spinal (L6-S1) BDNF protein levels were examined by ELISA. Transcript levels of transient receptor potential channels or acid-sensing ion channels (Asic) in L6-S1 dorsal root ganglia were evaluated by RT-PCR. Voided volume and voiding efficiency were significantly increased without any changes in nonvoiding contractions, and the duration of reduced EMG activity during the voiding phase was significantly prolonged in anti-BDNF antibody-treated SCI mice. Compared with spinal cord-intact mice, SCI mice showed increased concentrations of bladder and spinal BDNF. Anti-BDNF antibody treatment decreased bladder and spinal BDNF protein concentrations of SCI mice. Asic2 and Asic3 transcripts were significantly increased after SCI but decreased after anti-BDNF antibody administration. These results indicate that upregulated expression of bladder and spinal BDNF is involved in the emergence of inefficient voiding in SCI mice. Thus, BDNF-targeting treatment could be an effective modality for the treatment of voiding problems, including inefficient voiding and detrusor sphincter dyssynergia after SCI.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajprenal.00239.2019DOI Listing
November 2019

Analysis of continence reflexes by dynamic urethral pressure recordings in a rat stress urinary incontinence model induced by multiple simulated birth traumas.

Am J Physiol Renal Physiol 2019 10 17;317(4):F781-F788. Epub 2019 Jul 17.

Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.

The present study evaluated real-time changes in urethral pressure during the storage phase using a rat model with stress urinary incontinence (SUI) induced by simulated multiple birth traumas and investigated the relationship between urethral continence function and dynamic parameters associated with the changes in urethral pressure. Sprague-Dawley rats were divided into the following two groups: the sham group, which underwent three catheterizations of the vagina without distension at 2-wk intervals, and the vaginal distension (VD) group, which underwent three VDs at 2-wk intervals. After transection of the T8-T9 spinal cord, simultaneous bladder and urethral pressure recordings were performed during intravesical pressure elevation. Urodynamic parameters such as leak point pressure (LPP), urethral baseline pressure (UBP), maximum urethral pressure (MUP), the MUP-UBP differential (dUP) during intravesical pressure elevation, the bladder pressure when urethral contraction begins (Puc), and the bladder pressure at bladder neck opening (Pno) were then measured and compared. Compared with the sham group, LPP, UBP, dUP, MUP, Puc, and Pno were significantly decreased in the VD group. Pressure differences between LPP and Pno and between LPP and UBP (LPP-UBP) were also significantly different in the two groups. However, difference values of LPP and MUP or Pno and UBP were not altered after VD. Our new methods of simultaneous recordings of dynamic changes in bladder and urethral pressures are useful to fully evaluate the functional alterations in urethral continence function in the SUI model induced by multiple VDs. Moreover, LPP-UBP values, which correspond to the difference between Valsalva LPP and maximum urethral closure pressure in clinical urodynamics, would be useful to evaluate the impaired urethral continence function after simulated birth traumas in animal models.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajprenal.00197.2019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6843045PMC
October 2019

Low pressure voiding induced by a novel implantable pudendal nerve stimulator.

Neurourol Urodyn 2019 06 4;38(5):1241-1249. Epub 2019 Apr 4.

Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania.

Aim: To validate the functionality of an implantable pudendal nerve stimulator under development for Food and Drug Administration approval to restore bladder function after spinal cord injury.

Methods: In nine cats under anesthesia, two tripolar cuff electrodes were implanted bilaterally on the pudendal nerves and one bipolar cuff electrode was implanted on the right pudendal nerve central to the tripolar cuff electrode. The pudendal nerve stimulator was implanted subcutaneously on the left lower back along the lumbosacral spine and connected to the cuff electrodes. In five cats, a double lumen catheter was inserted into the bladder through the urethra to infuse saline and measure bladder pressure and another catheter was inserted into the distal urethra to perfuse and measure the back pressure caused by urethral contraction. In four cats, a bladder catheter was inserted into the bladder dome and the urethra was left open so that voiding could occur without urethral outlet obstruction.

Results: The implantable pudendal nerve stimulator was controlled wirelessly and successfully provided the required stimulation waveforms to different cuff electrodes. Pudendal nerve stimulation (PNS) at 5 Hz increased bladder capacity to about 200% of control capacity. PNS at 20 to 30 Hz induced large (80-100 cmH O) bladder contractions under isovolumetric conditions. When combined with ipsilateral or bilateral pudendal nerve block induced by 6 to 10 kHz stimulation, PNS at 20 to 30 Hz elicited low pressure (<40 cmH O) efficient (70%) voiding.

Conclusions: The implantable stimulator generated the required stimulation waveforms and successfully induced low pressure efficient voiding in anesthetized cats.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/nau.23994DOI Listing
June 2019

Sympathetic afferents in the hypogastric nerve facilitate nociceptive bladder activity in cats.

Am J Physiol Renal Physiol 2019 04 23;316(4):F703-F711. Epub 2019 Jan 23.

Department of Urology, University of Pittsburgh , Pittsburgh, Pennsylvania.

This study in α-chloralose-anesthetized cats revealed a role of hypogastric nerve afferent axons in nociceptive bladder activity induced by bladder irritation using 0.25% acetic acid (AA). In cats with intact hypogastric and pelvic nerves, AA irritation significantly ( P < 0.05) reduced bladder capacity to 45.0 ± 5.7% of the control capacity measured during a saline cystometrogram (CMG). In cats with the hypogastric nerves transected bilaterally, AA irritation also significantly ( P < 0.05) reduced bladder capacity, but the change was significantly smaller (capacity reduced to 71.5 ± 10.6% of saline control, P < 0.05) than that in cats with an intact hypogastric nerve. However, application of hypogastric nerve stimulation (HGNS: 20 Hz, 0.2 ms pulse width) to the central end of the transected nerves at an intensity (16 V) strong enough to activate C-fiber afferent axons facilitated the effect of AA irritation and further ( P < 0.05) reduced bladder capacity to 48.4 ± 7.4% of the saline control. This facilitation by HGNS was effective only at selected frequencies (1, 20, and 30 Hz) when the stimulation intensity was above the threshold for activating C-fibers. Tramadol (an analgesic agent) at 3 mg/kg iv completely blocked the nociceptive bladder activity and eliminated the facilitation by HGNS. HGNS did not alter non-nociceptive bladder activity induced by saline distention of the bladder. These results indicate that sympathetic afferents in the hypogastric nerve play an important role in the facilitation of the nociceptive bladder activity induced by bladder irritation that activates the silent C-fibers in the pelvic nerve.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajprenal.00522.2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6483026PMC
April 2019

Bladder overactivity and afferent hyperexcitability induced by prostate-to-bladder cross-sensitization in rats with prostatic inflammation.

J Physiol 2019 04 12;597(7):2063-2078. Epub 2019 Feb 12.

Departments of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA.

Key Points: There is clinical evidence showing that prostatic inflammation contributes to overactive bladder symptoms in male patients; however, little is known about the underlying mechanisms In this study, we investigated the mechanism that prostatic inflammation causes detrusor overactivity by using a rat model of chemically induced prostatic inflammation. We observed a significant number of dorsal root ganglion neurons with dichotomized afferents innervating both prostate and bladder. We also found that prostatic inflammation induces bladder overactivity and urothelial NGF overexpression in the bladder, both dependent on activation of the pelvic nerve, as well as changes in ion channel expression and hyperexcitability of bladder afferent neurons. These results indicate that the prostate-to-bladder cross-sensitization through primary afferent pathways in the pelvic nerve, which contain dichotomized afferents, could be an important mechanism contributing to bladder overactivity and afferent hyperexcitability induced by prostatic inflammation.

Abstract: Prostatic inflammation is reportedly an important factor inducing lower urinary tract symptoms (LUTS) including urinary frequency, urgency and incontinence in patients with benign prostatic hyperplasia (BPH). However, the underlying mechanisms inducing bladder dysfunction after prostatic inflammation are not well clarified. We therefore investigated the effects of prostatic inflammation on bladder activity and afferent function using a rat model of non-bacterial prostatic inflammation. We demonstrated that bladder overactivity, evident as decreased voided volume and shorter intercontraction intervals in cystometry, was observed in rats with prostatic inflammation versus controls. Tissue inflammation, evident as increased myeloperoxidase activity, and IL-1α, IL-1β, and IL-6 levels inside the prostate, but not in the bladder, following intraprostatic formalin injection induced an increase in NGF expression in the bladder urothelium, which depended on activation of the pelvic nerve. A significant proportion (18-19%) of dorsal root ganglion neurons were double labelled by dye tracers injected into either bladder or prostate. In rats with prostatic inflammation, TRPV1, TRPA1 and P2X2 increased, and Kv1.4, a potassium channel α-subunit that can form A-type potassium (K ) channels, decreased at mRNA levels in bladder afferent and double-labelled neurons vs. non-labelled neurons, and slow K current density decreased in association with hyperexcitability of these neurons. Collectively, non-bacterial inflammation localized in the prostate induces bladder overactivity and enhances bladder afferent function. Thus, prostate-to-bladder afferent cross-sensitization through primary afferents in the pelvic nerve, which contain dichotomized afferents, could underlie storage LUTS in symptomatic BPH with prostatic inflammation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1113/JP277452DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6441933PMC
April 2019

Positive Association of Male Overactive Bladder Symptoms and Androgen Deprivation: A Nationwide Population-based Cohort Study.

Anticancer Res 2019 Jan;39(1):305-311

Division of Urology, Department of Surgery, Taichung Veterans General Hospital, Taichung, Taiwan, R.O.C.

Background/aim: The role of androgen in the modulation of voiding function is still uncertain. The aim of this study was to evaluate the association of androgen deprivation therapy (ADT) and overactive bladder (OAB) in men in a population-based cohort.

Materials And Methods: This study examined the records of newly-diagnosed prostate cancer subjects receiving ADT only in the Taiwan National Health Insurance Research Database in the years between 2001 and 2007. As controls men without cancer were selected and divided into three groups, 1) benign prostate hyperplasia treated with an alpha-blocker (BPH-alpha blocker), 2) BPH treated with a 5-alpha reductase inhibitor (BPH-5ARI) and 3) healthy controls. OAB events were censored by definition of drug prescriptions for more than one month and risk analysis among each group was performed.

Results: The healthy control group had decreased risk of OAB compared to the prostate cancer group and the BPH-5ARI group showed a higher risk of OAB than the prostate cancer group. Subgroup analysis showed that independently of age or comorbidities, the prevalence of OAB was significantly lower in the healthy control group. Moreover, the cumulative incidence of OAB showed a time-dependent pattern with a significant increase after ADT for 5 years.

Conclusion: Androgen deprivation in prostate cancer patients was associated with an increased risk of OAB that was treatment duration-dependent. This result is consistent with an inhibitory role of androgen in the modulation of male voiding function.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.21873/anticanres.13112DOI Listing
January 2019

Involvement of TRPM4 in detrusor overactivity following spinal cord transection in mice.

Naunyn Schmiedebergs Arch Pharmacol 2018 11 27;391(11):1191-1202. Epub 2018 Jul 27.

Department of Medicine/Renal and Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15261, USA.

Transient receptor potential cation channel subfamily M member 4 (TRPM4) has been shown to play a key role in detrusor contractility under physiological conditions. In this study, we investigated the potential role of TRPM4 in detrusor overactivity following spinal cord transection (SCT) in mice. TRPM4 expression and function were evaluated in bladder tissue with or without the mucosa from spinal intact (SI) and SCT female mice (T8-T9 vertebra; 1-28 days post SCT) using PCR, western blot, immunohistochemistry, and muscle strip contractility techniques. TRPM4 was expressed in the urothelium (UT) and detrusor smooth muscle (DSM) and was upregulated after SCT. Expression levels peaked 3-7 days post SCT in both the UT and DSM. Pharmacological block of TRPM4 with the antagonist, 9-Phenanthrol (30 μM) greatly reduced spontaneous phasic activity that developed after SCT, regardless of the presence or absence of the mucosa. Detrusor overactivity following spinal cord injury leads to incontinence and/or renal impairment and represents a major health problem for which current treatments are not satisfactory. Augmented TRPM4 expression in the bladder after chronic SCT supports the hypothesis that TRPM4 channels play a role in DSM overactivity following SCT. Inhibition of TRPM4 may be beneficial for improving detrusor overactivity in SCI.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00210-018-1542-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6186176PMC
November 2018

Reduced bladder responses to capsaicin and GSK-1016790A in retired-breeder female rats with diminished volume sensitivity.

Am J Physiol Renal Physiol 2018 11 18;315(5):F1217-F1227. Epub 2018 Jul 18.

Department of Urology, the Second Hospital of Shandong University, Jinan, Shandong, Peoples Republic of China.

Literature documents an age-related reduction of bladder sensory function. Transient receptor potential vanilloid (TRPV)1 or TRPV4 channels have been implicated in bladder mechanotransduction. To investigate contributions of TRPV1 or TRPV4 to the age-related reduction of bladder sensory function, bladder responses to capsaicin (CAP; TRPV1 agonist) and GSK-1016790A (GSK; TRPV4 agonist) in retired breeder (RB; 12-15 mo) and young adult (2-3 mo) female rats were compared using multiple methods. Metabolic cage and continuous infusion cystometry [cystometrogram (CMG)] recordings revealed that RB rats exhibit larger bladder capacity and lower voiding frequency. RB rats also have a greater intravesical pressure threshold for micturition; however, the voiding contraction strength was equivalent to that in young rats. CAP (1 μM) or GSK (20 nM) administered intravesically evoked smaller changes in all CMG parameters in RB rats. In vitro, CAP (1 μM) or GSK (20 nM) evoked smaller enhancement of bladder strip contractions, while the muscarinic receptor agonist carbachol (at 100, 300, and 1,000 nM) elicited greater amplitude contractions in RB rats. Patch-clamp recording revealed smaller CAP (100 nM) induced inward currents in bladder primary sensory neurons, and Ca imaging revealed smaller GSK (20 nM) evoked increases in intracellular Ca concentration in urothelial cells in RB rats. These results suggest that RB rats have a decreased bladder sensory function commonly observed in elderly women, and could be used as an animal model to study the underling mechanisms. Reduced functional expression of TRPV1 in bladder afferents or reduced functional expression of urothelial TRPV4 may be associated with the diminished sensory function.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajprenal.00198.2018DOI Listing
November 2018

Effects of nerve growth factor neutralization on TRP channel expression in laser-captured bladder afferent neurons in mice with spinal cord injury.

Neurosci Lett 2018 09 28;683:100-103. Epub 2018 Jun 28.

Department of Urology, University of Pittsburgh, Pittsburgh, PA, 15213, United States; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, 15213, United States. Electronic address:

Nerve growth factor (NGF) is reportedly involved in the changes in C-fiber bladder afferent pathways that induce detrusor overactivity (DO) following spinal cord injury (SCI). This study examined the roles of NGF in TRP channel expression in bladder afferent neurons in mice with SCI using laser-capture microdissection (LCM) methods. Spinal intact (SI) and SCI mice were divided into 3 groups: (1) SI with vehicle treatment; (2) SCI with vehicle treatment; and (3) SCI with anti-NGF antibody. Two weeks after SCI, an osmotic pump was placed subcutaneously into the back of the mice and vehicle or anti-NGF antibody was administered at a rate of 10 μg/kg per hour for two weeks. Four weeks after SCI, the L6 dorsal root ganglia (DRG) were removed. Expression of the TRPV1, TRPC1, TRPC3, and TRPC6 genes was analyzed using real-time polymerase chain reaction (PCR) following LCM of the bladder afferent neurons, which were labeled by Fast Blue injected into the bladder wall 1 week prior to tissue removal. The mRNA expression of TRPV1 was found to be higher in vehicle-treated SCI mice than in SI mice. The expression level of TRPC3 and TRPC6 in vehicle-treated SCI mice was lower than in SI mice. However, in SCI mice treated with anti-NGF antibody, the mRNA expression of TRPV1 was lower, and the mRNA levels of TRPC3 and TRPC6 were higher than in vehicle-SCI mice. These results suggest that the NGF-dependent changes in specific TRP channel genes, such as TRPV1, TRPC3, and TRPC6, could be involved in SCI-induced afferent hyperexcitability and DO.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.neulet.2018.06.049DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6448406PMC
September 2018

Frequency Dependent Tibial Neuromodulation of Bladder Underactivity and Overactivity in Cats.

Neuromodulation 2018 Oct 27;21(7):700-706. Epub 2018 Jun 27.

Department of Urology, University of Pittsburgh, Pittsburgh, PA, USA.

Objective: This study is aimed at determining if tibial nerve stimulation (TNS) can modulate both bladder underactivity and overactivity.

Methods: In α-chloralose anesthetized cats, tripolar cuff electrodes were implanted on both tibial nerves and TNS threshold (T) for inducing toe twitching was determined for each nerve. Normal bladder activity was elicited by slow intravesical infusion of saline; while bladder overactivity was induced by infusion of 0.25% acetic acid to irritate the bladder. Bladder underactivity was induced during saline infusion by repeated application (2-6 times) of 30-min TNS (5 Hz, 4-8T, 0.2 msec) to the left tibial nerve, while TNS (1 Hz, 4T, 0.2 msec) was applied to the right tibial nerve to reverse the bladder underactivity.

Results: Prolonged 5-Hz TNS induced bladder underactivity by significantly increasing bladder capacity to 173.8% ± 10.4% of control and reducing the contraction amplitude to 40.1% ± 15.3% of control, while 1 Hz TNS normalized the contraction amplitude and significantly reduced the bladder capacity to 130%-140% of control. TNS at 1 Hz in normal bladders did not change contraction amplitude and only slightly changed the capacity, but in both normal and underactive bladders significantly increased contraction duration. The effects of 1 Hz TNS did not persist following stimulation. Under isovolumetric conditions when the bladder was underactive, TNS (0.5-3 Hz; 1-4T) induced large amplitude and sustained bladder contractions. In overactive bladders, TNS during cystometry inhibited bladder overactivity at 5 Hz but not at 1 Hz.

Conclusions: This study indicates that TNS at different frequencies might be used to treat bladder underactivity and overactivity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/ner.12792DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6175618PMC
October 2018

Bladder underactivity after prolonged stimulation of somatic afferent axons in the tibial nerve in cats.

Neurourol Urodyn 2018 09 10;37(7):2121-2127. Epub 2018 Apr 10.

Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania.

Aims: To establish an animal model of bladder underactivity induced by prolonged and intense stimulation of somatic afferent axons in the tibial nerve.

Methods: In seven cats under α-chloralose anesthesia, tibial nerve stimulation (TNS) of 30-min duration was repeatedly (3-8 times) applied at 4-6 times threshold (T) intensity for inducing a toe twitch to produce bladder underactivity determined by cystometry. Naloxone (1 mg/kg, i.v.) was administered to examine the role of opioid receptors in TNS-induced bladder underactivity.

Results: After prolonged (1.5-4 h) and intense (4-6T) TNS, a complete suppression of the micturition reflex occurred in six cats and an increase in bladder capacity to about 150% of control and a decrease in the micturition contraction amplitude to 50% of control occurred in one cat. The bladder underactivity was maintained for at least 1-1.5 h. Naloxone reversed the bladder underactivity, but an additional 30-min TNS removed the naloxone effect.

Conclusions: The results indicate that prolonged and intense activation of somatic afferent axons in the tibial nerve can suppress the central reflex mechanisms controlling micturition. This animal model may be useful for examining the pathophysiology of neurogenic bladder underactivity and for development of new treatments for underactive bladder symptoms.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/nau.23577DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6146051PMC
September 2018

Nerve growth factor-dependent hyperexcitability of capsaicin-sensitive bladder afferent neurones in mice with spinal cord injury.

Exp Physiol 2018 06 24;103(6):896-904. Epub 2018 Apr 24.

Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA.

New Findings: What is the central question of this study? Nerve growth factor (NGF) is reportedly a mediator inducing urinary bladder dysfunction. Is NGF directly involved in hyperexcitability of capsaicin-sensitive C-fibre bladder afferent pathways after spinal cord injury (SCI)? What is the main finding and its importance? Neutralization of NGF by anti-NGF antibody treatment reversed the SCI-induced increase in the number of action potentials and the reduction in spike thresholds and A-type K current density in mouse capsaicin-sensitive bladder afferent neurones. Thus, NGF plays an important and direct role in hyperexcitability of capsaicin-sensitive C-fibre bladder afferent neurones attributable to the reduction in A-type K channel activity in SCI.

Abstract: Nerve growth factor (NGF) has been implicated as an important mediator in the induction of C-fibre bladder afferent hyperexcitability, which contributes to the emergence of neurogenic lower urinary tract dysfunction after spinal cord injury (SCI). In this study, we determined whether NGF immunoneutralization using an anti-NGF antibody (NGF-Ab) normalizes the SCI-induced changes in electrophysiological properties of capsaicin-sensitive C-fibre bladder afferent neurones in female C57BL/6 mice. The spinal cord was transected at the Th8/Th9 level. Two weeks later, continuous administration of NGF-Ab (10 μg kg  h , s.c. for 2 weeks) was started. Bladder afferent neurones were labelled with Fast-Blue (FB), a fluorescent retrograde tracer, injected into the bladder wall 3 weeks after SCI. Four weeks after SCI, freshly dissociated L6-S1 dorsal root ganglion neurones were prepared. Whole-cell patch-clamp recordings were then performed in FB-labelled neurones. After recording action potentials or voltage-gated K currents, the sensitivity of each neurone to capsaicin was evaluated. In capsaicin-sensitive FB-labelled neurones, SCI significantly reduced the spike threshold and increased the number of action potentials during membrane depolarization for 800 ms. These SCI-induced changes were reversed by NGF-Ab. Densities of slow-decaying A-type K (K ) and sustained delayed rectifier-type K currents were significantly reduced by SCI. The NGF-Ab treatment reversed the SCI-induced reduction in the K current density. These results indicate that NGF plays an important role in hyperexcitability of mouse capsaicin-sensitive C-fibre bladder afferent neurones attributable to a reduction in K channel activity. Thus, NGF-targeting therapies could be effective for treatment of afferent hyperexcitability and neurogenic lower urinary tract dysfunction after SCI.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1113/EP086951DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5984147PMC
June 2018

Role of proNGF/p75 signaling in bladder dysfunction after spinal cord injury.

J Clin Invest 2018 05 26;128(5):1772-1786. Epub 2018 Mar 26.

Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, Ohio, USA.

Loss of bladder control is a challenging outcome facing patients with spinal cord injury (SCI). We report that systemic blocking of pro-nerve growth factor (proNGF) signaling through p75 with a CNS-penetrating small-molecule p75 inhibitor resulted in significant improvement in bladder function after SCI in rodents. The usual hyperreflexia was attenuated with normal bladder pressure, and automatic micturition was acquired weeks earlier than in the controls. The improvement was associated with increased excitatory input to the spinal cord, in particular onto the tyrosine hydroxylase-positive fibers in the dorsal commissure. The drug also had an effect on the bladder itself, as the urothelial hyperplasia and detrusor hypertrophy that accompany SCI were largely prevented. Urothelial cell loss that precedes hyperplasia was dependent on p75 in response to urinary proNGF that is detected after SCI in rodents and humans. Surprisingly, death of urothelial cells and the ensuing hyperplastic response were beneficial to functional recovery. Deleting p75 from the urothelium prevented urothelial death, but resulted in reduction in overall voiding efficiency after SCI. These results unveil a dual role of proNGF/p75 signaling in bladder function under pathological conditions with a CNS effect overriding the peripheral one.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/JCI97837DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5919823PMC
May 2018

The effect of the electrophilic fatty acid nitro-oleic acid on TRP channel function in sensory neurons.

Nitric Oxide 2018 Mar 22. Epub 2018 Mar 22.

Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.

Nitro-oleic acid (NO-OA) and related nitroalkenes are electrophilic fatty acid derivatives that are present in normal tissues at nanomolar concentrations and can increase significantly during inflammation. These substances can suppress multiple intracellular signaling pathways contributing to inflammation by reversible Michael addition reactions with nucleophilic residues such as cysteine and histidine leading to post-translational modification of proteins. NO-OA also can influence inflammation and pain by acting on transient receptor potential (TRP) channels in primary sensory neurons. TRPV1, TRPA1 and TRPC can respond to electrophilic fatty acids because they have ankyrin-like repeats in their N terminus that are rich in cysteine residues that react with electrophiles and other thiol modifying species. NO-OA acts on TRP channels to initially depolarize and induce firing in sensory neurons followed by desensitization and suppression of firing. In vivo experiments revealed that pretreatment with NO-OA reduces nociceptive behavior evoked by local administration of a TRPA1 agonist (AITC) to the rat hind paw. These results raise the possibility that NO-OA might be useful clinically to reduce neurogenic inflammation and certain types of painful sensations by desensitizing TRPA1 expressing nociceptive afferents.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.niox.2018.03.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6151181PMC
March 2018

The effect of neutralization of nerve growth factor (NGF) on bladder and urethral dysfunction in mice with spinal cord injury.

Neurourol Urodyn 2018 08 8;37(6):1889-1896. Epub 2018 Mar 8.

Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.

Aims: To investigate the role of nerve growth factor (NGF) in lower urinary tract dysfunction in mice with spinal cord injury (SCI).

Methods: Using 4-week SCI mice, single-filling cystometry and external urethral sphincter (EUS)-electromyography were performed under an awake condition. In some SCI mice, anti-NGF antibodies (10 µg/kg/h) were administered for 1 or 2 weeks before the urodynamic study. NGF levels in the bladder and L6/S1 spinal cord were assayed by ELISA. The transcript levels of P2X receptors and TRP channels in L6/S1 dorsal root ganglia (DRG) were measured by RT-PCR.

Results: In SCI mice, the area under the curve of non-voiding contractions (NVCs) during the storage phase was significantly decreased in both 1- and 2-week anti-NGF antibody-treated SCI groups. However, EUS-electromyogram parameters during voiding were not altered by the treatment. Bladder mucosal and spinal NGF levels were decreased after 2 weeks of anti-NGF antibody treatment. TRPA1 and TRPV1 transcripts in L6/S1 DRG were significantly decreased after 1- or 2-week anti-NGF treatment.

Conclusions: In SCI mice, NGF is involved in the emergence of NVCs in association with increased expression of TRP receptors that are predominantly found in C-fiber afferent pathways. Thus, NGF targeting treatments could be effective for treating storage problems such as detrusor overactivity after SCI.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/nau.23539DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6129225PMC
August 2018