Recurrent infections drive persistent bladder dysfunction and pain via sensory nerve sprouting and mast cell activity.

Urinary tract infections (UTIs) account for almost 25% of infections in women. Many are recurrent (rUTI), with patients frequently experiencing chronic pelvic pain and urinary frequency despite clearance of bacteriuria after antibiotics. To elucidate the basis for these bacteria-independent bladder symptoms, we examined the bladders of patients with rUTI. We noticed a notable increase in neuropeptide content in the lamina propria and indications of enhanced nociceptive activity. In mice subjected to rUTI, we observed sensory nerve sprouting that was associated with nerve growth factor (NGF) produced by recruited monocytes and tissue-resident mast cells. Treatment of rUTI mice with an NGF-neutralizing antibody prevented sprouting and alleviated pelvic sensitivity, whereas instillation of native NGF into naïve mice bladders mimicked nerve sprouting and pain behavior. Nerve activation, pain, and urinary frequency were each linked to the presence of proximal mast cells, because mast cell deficiency or treatment with antagonists against receptors of several direct or indirect mast cell products was each effective therapeutically. Thus, our findings suggest that NGF-driven sensory sprouting in the bladder coupled with chronic mast cell activation represents an underlying mechanism driving bacteria-independent pain and voiding defects experienced by patients with rUTI.

Mechanism of Action of Tibial Nerve Stimulation in the Treatment of Lower Urinary Tract Dysfunction.

BACKGROUND AND OBJECTIVE: Tibial nerve stimulation (TNS) has long been used to effectively treat lower urinary tract dysfunction (LUTD). Although numerous studies have concentrated on TNS, its mechanism of action remains elusive. This review aimed to concentrate on the mechanism of action of TNS against LUTD. MATERIALS AND METHODS: A literature search was performed in PubMed on October 31, 2022. In this study, we introduced the application of TNS for LUTD, summarized different methods used in exploring the mechanism of TNS, and discussed the next direction to investigate the mechanism of TNS. RESULTS AND CONCLUSIONS: In this review, 97 studies, including clinical studies, animal experiments, and reviews, were used. TNS is an effective treatment for LUTD. The study of its mechanisms primarily concentrated on the central nervous system, tibial nerve pathway, receptors, and TNS frequency. More advanced equipment will be used in human experiments to investigate the central mechanism, and diverse animal experiments will be performed to explore the peripheral mechanism and parameters of TNS in the future.

Detrusor nerve radiofrequency ablation (DENERA): Experimental study of safety and efficacy in an ovine model.

PURPOSE: The subtrigonal perivesical nerve plexus contains a large proportion of the bladder's innervation. A transurethral radiofrequency ablation approach has successfully denervated this region to alleviate overactive bladder symptoms, with some urothelial heat injury. We report a novel transvaginal RFA device (DENERA) and assess its feasibility and efficacy in denervating the perivesical nerve plexus of in vivo sheep. METHODS: In 14 adult female in vivo sheep, pulsed radiofrequency energy was applied transvaginally for three cycles of 4 min, maintaining the tissue temperature at 45°C, with 30 s of rest between each cycle. The control group (n = 4) was sacrificed without ablation, and various groups were sacrificed 1 week (n = 3), 4 weeks (n = 4), and 12 weeks (n = 3) after ablation. The bladder subtrigones were harvested then analyzed with H&E, S100, and TH immunostaining to quantify their neural density and neural vacuolization. RESULTS: The ablation procedure increased the neural vacuolization the most at 1 week and decreased the neural density the most at 4 weeks, with both variables displaying a significant change followed by a slight rebound towards baseline at 12 weeks. The H&E analysis showed that the needles penetrated deep into the subtrigonal detrusor muscle. The sheep recovered from the procedure with no complications or damage in the bladder wall or urothelium. CONCLUSIONS: This study shows that one DENERA treatment can cause subtrigonal denervation with some rebound afterwards and no complications. DENERA may become a promising OAB treatment option that can ablate the perivesical plexus without harming the urothelium.

Pathways and parameters of sacral neuromodulation in rats.

The stimulation paradigm for sacral neuromodulation has remained largely unchanged since its inception. We sought to determine, in rats, whether stimulation-induced increases in bladder capacity correlated with the proportion of sensory pudendal (PudS) neurons at each stimulated location (L6, S1). If supported, this finding could guide the choice of stimulation side (left/right) and level (S2, S3, S4) in humans. Unexpectedly, we observed that acute stimulation at clinically relevant (low) amplitudes [1-1.5 × motor threshold (Tm)], did not increase bladder capacity, regardless of stimulus location (L6 or S1). More importantly for the ability to test our hypothesis, there was little anatomic variation, and S1 infrequently contributed nerve fibers to the PudS nerve. During mapping studies we noticed that large increases in PudS nerve activation occurred at amplitudes exceeding 2Tm. Thus, additional cystometric studies were conducted, this time with stimulation of the L6-S1 trunk, to examine further the relationship between stimulation amplitude and cystometric parameters. Stimulation at 1Tm to 6Tm evoked increases in bladder capacity and decreases in voiding efficiency that mirrored those produced by PudS nerve stimulation. Many animal studies involving electrical stimulation of nerves of the lower urinary tract use stimulation amplitudes that exceed those used clinically (∼1Tm). Our results confirm that high amplitudes generate immediate changes in cystometric parameters; however, the relationship to low-amplitude chronic stimulation in humans remains unclear. Additional studies are needed to understand changes that occur with chronic stimulation, how these changes relate to therapeutic outcomes, and the contribution of specific nerve fibers to these changes.NEW & NOTEWORTHY Acute low-amplitude electrical stimulation of sacral nerve (sacral neuromodulation) did not increase bladder capacity in anesthetized CD, obese-prone, or obese-resistant rats. Increasing stimulation amplitude correlated with increases in bladder capacity and pudendal sensory nerve recruitment. It is unclear how the high-amplitude acute stimulation that is commonly used in animal experiments to generate immediate effects compares mechanistically to the chronic low-amplitude stimulation used clinically.

H2O2 enhances the spontaneous phasic contractions of isolated human-bladder strips via activation of TRPA1 channels on sensory nerves and the release of substance P and PGE2.

Several studies have indicated that reactive oxygen species (ROS) can lead to detrusor overactivity (DO), but the underlying mechanisms are not known. Hydrogen dioxide (H2O2) is used commonly to investigate the effects of ROS. In present study, we investigated the effects of H2O2 on phasic spontaneous bladder contractions (SBCs) of isolated human-bladder strips (iHBSs) and the underlying mechanisms. Samples of bladder tissue were obtained from 26 patients undergoing cystectomy owing to bladder cancer. SBCs of iHBSs were recorded in organ-bath experiments. H2O2 (1µM-10mM) concentration-dependently increased the SBCs of iHBSs. These enhancing effects could be mimicked by an agonist of transient receptor potential (TRP)A1 channels (allyl isothiocyanate) and blocked with an antagonist of TRPA1 channels (HC030031; 10 µM). H2O2 induced enhancing effects also could be attenuated by desensitizing sensory afferents with capsaicin (10 µM), blocking nerve firing with TTX (1 µM), blocking neurokinin effects with NK2 receptor antagonist (SR48968, 10 µM), and blocking PGE2 synthesis with indomethacin (10 µM), respectively. Our study: (i) suggests activation of TRPA1 channels on bladder sensory afferents, and then release of substance P or PGE2 from sensory nerve terminals, contribute to the H2O2-induced enhancing effects on SBCs of iHBSs; (ii) provides insights for the mechanisms underlying ROS leading to DO; (iii) indicates that targeting TRPA1 channels might be the promising strategy against overactive bladder in conditions associated with excessive production of ROS.

Folic acid supplementation rescues bladder injury in fetal rats with myelomeningocele.

BACKGROUND: Bladder dysfunction has been linked to the progression of renal failure in children with neurogenic bladder (NB) dysfunction. The purpose of this study was to determine whether bladder injuries in fetal rats with myelomeningocele (MMC) may be treated with folic acid. METHODS: Pregnant Sprague-Dawley rats were randomly divided into three groups. On the 10th day of gestation, pregnant rats were intragastrically injected with all-trans retinoic acid (ATRA) (60 mg/kg) to induce MMC fetal rats. The same amount of olive oil was put into the control group to create normal fetal rats. The rats in the rescue group were given folic acid (40 mg/kg) by gavage 0.5 and 12 hr after ATRA therapy. Bladders were obtained via cesarean section on embryonic day E20.5 and examined for MMC. The histology of the fetuses was examined using hematoxylin and eosin staining, and immunohistochemistry (IHC) was utilized to determine the expression of α-smooth muscle actin (α-SMA) and neuron-specific nuclear-binding protein (NeuN). Furthermore, the levels of neuromuscular development-related and apoptotic proteins were determined by western blotting. RESULTS: The incidence of MMC in the model group was 60.6% (20/33) while it was much lower in the rescue group (21.4%). In comparison to the model group, the weight and crown-rump length of the fetal rats in the rescue group were significantly improved. IHC revealed that there was no significant difference in the expression of α-SMA and NeuN between the control and ATRA groups, while the expression levels decreased significantly in the MMC group. Western blot analysis showed that there was no significant difference between the model and ATRA groups, but the expression of the α-SMA protein and the ß3-tubulin was much lower in the MMC group than in the control group. After the administration of folic acid, the α-SMA and ß3-tubulin proteins considerably increased in the folic acid-rescued MMC group and folic acid-rescued ATRA group. Meanwhile, in the control group, the expression of cleaved caspase-3 in the bladder tissue was significantly higher, and the expression of poly (ADP-ribose) polymerase (PARP) protein was significantly lower compared to the control group. Folic acid therapy reduced cleaved caspase-3 expression while increasing PARP expression in comparison to the MMC group. CONCLUSIONS: NB in MMC fetal rats is associated with the reduction of bladder nerve and smooth muscle-related protein synthesis. However, folic acid therapy can help improve these functional deficiencies. Folic acid also exhibits strong anti-apoptotic properties against NB in MMC fetal rats.

Male Akita mice develop signs of bladder underactivity independent of NLRP3 as a result of a decrease in neurotransmitter release from efferent neurons.

Diabetic bladder dysfunction (DBD) is a prevalent diabetic complication that is recalcitrant to glucose control. Using the Akita mouse model (type 1) bred to be NLR family pyrin domain containing 3 (NLRP3)+/+ or NLRP3-/-, we have previously found that females (mild hyperglycemia) progress from an overactive to underactive bladder phenotype and that this progression was dependent on NLRP3-induced inflammation. Here, we examined DBD in the male Akita mouse (severe hyperglycemia) and found by urodynamics only a compensated underactive-like phenotype (increased void volume and decreased frequency but unchanged efficiency). Surprisingly, this phenotype was still present in the NLRP3-/- strain and so was not dependent on NLRP3 inflammasome-induced inflammation. To examine the cause of the compensated underactive-like phenotype, we assessed overall nerve bundle density and afferent nerve bundles (Aδ-fibers). Both were decreased in density during diabetes, but denervation was absent in the diabetic NLRP3-/- strain so it was deemed unlikely to cause the underactive-like symptoms. Changes in bladder smooth muscle contractility to cell depolarization and receptor activation were also not responsible as KCl (depolarizing agent), carbachol (muscarinic agonist), and α,ß-methylene-ATP (purinergic agonist) elicited equivalent contractions in denuded bladder strips in all groups. However, electrical field stimulation revealed a diabetes-induced decrease in contractility that was not blocked in the NLRP3-/- strain, suggesting that the bladder compensated underactive-like phenotype in the male Akita mouse is likely through a decrease in efferent neurotransmitter release.NEW & NOTEWORTHY In this study, we show that diabetic bladder dysfunction (the most common diabetic complication) manifests through different mechanisms that may be related to severity of hyperglycemia and/or sex. Male Akita mice, which have severe hyperglycemia, develop bladder underactivity as a result of a decrease in efferent neurotransmitter release that is independent of inflammation. This contrasts with females, who have milder hyperglycemia, where diabetic bladder dysfunction progresses from overactivity to underactivity in an inflammation-dependent manner.

Efficacy of the magnetic stimulation of sacral nerve roots combined with Tui-na on neurogenic bladder after spinal cord injury: preliminary short-term results.

OBJECTIVE: Neurogenic bladder (NGB) is a serious complication after spinal cord injury (SCI), a destructive neurological disease. This study focused on exploring the efficacy of the magnetic stimulation of sacral nerve roots combined with Tui-na in treating NGB after SCI. METHODS: One hundred patients with NGB after SCI were studied, and intermittent clean catheterization was performed with a water intake program, and patients were grouped into four groups by the random number table method: general treatment group, Tui-na group, magnetic stimulation group, and combined treatment group. A series of relevant factors (voiding diary, urodynamics, and quality of life scores) and clinical efficacy of patients in the four groups before and after treatment were observed. RESULTS: The magnetic stimulation of sacral nerve roots alone, Tui-na alone, and the combination of both were all effective in improving bladder function and quality of life in patients with NGB after SCI, including improvements in voiding frequency, single urine output, maximum urine output, residual urine output, bladder volume and quality of life scores in patients with NGB after SCI. The efficacy of the magnetic stimulation of sacral nerve roots combined with Tui-na was better than that of the magnetic stimulation of sacral nerve roots alone and the Tui-na alone. CONCLUSION: This research demonstrates that the magnetic stimulation of sacral nerve roots combined with Tui-na treatment could effectively improve the urinary system and the quality of life of patients with NGB after SCI, which is worthy of clinical promotion and application.

Increased Plasma Ignition Distance Practice may Prevent the Obturator Reflex Occurrences and Compare of its Effectiveness Versus Obturator Block: A Prospective, Randomized, Controlled Study.

OBJECTIVE: To compare the ability of the obturator nerve block (ONB) and increased plasma ignition distance practice (IPDP) techniques to inhibit obturator nerve reflex (ONR) occurring with bipolar transurethral resection of the bladder. METHODS: Sixty patients who had a tumor placed at the lateral sidewall or had a tumor in another part of the bladder along with the lateral wall were randomly enrolled. Cystoscopic and ultrasonographic examinations and a computerized tomography scanning of the urinary bladder were used to determine the ONB side. Group 1 consisted of patients who had the ONB procedure. Group 2 consisted of patients who had IPIDP. The severity of the ONR was classified as severe, mild, and very mild. The study's primary endpoint was ONR occurrences and successful completion of the surgery. The secondary endpoints were bleeding and bladder perforation. RESULTS: There was a significant difference in the occurrence of ONR between the two groups (P = 0.0011). However, there was no significant difference between the two groups in the ability to resect the tumor and complete the surgery (P = .764). There was no correlation between the ONR and the tumor size (P = 0.478). CONCLUSION: Our study concluded that both ONB and IPIDP have comparable results, especially in resecting tumors and completing the operation. IPIDP has some advantages over ONB, such as shorter operative time, lower total costs, and less trained personnel requirements.

Imaging neuro-urodynamics of mouse major pelvic ganglion with a micro-endoscopic approach.

Postganglionic neurons of the autonomic nervous system lie outside of the central nervous system and innervate specific target effectors such as organs or glands. The major pelvic ganglion (MPG) is one such ganglion that plays a significant role in controlling bladder function in rodents. However, because of technical and physical constraints in recording electrophysiological signals from these neurons in vivo, the functional neural activity in MPG is mostly unknown. Transgenic animal models expressing genetically encoded calcium indicators now provide opportunities to monitor the activity of populations of neurons in vivo to overcome these challenges related to traditional electrophysiological methods. However, like many peripheral neurons, the MPG is not conducive to conventional fluorescent microscopy techniques, as it is located in the pelvic cavity, thus limiting robust optical access by benchtop microscopes. Here, we present an endoscopic approach based on a custom miniscope system (UCLA V3) that allows for effective in vivo monitoring of neural activity in the MPG for the first time. We show that our imaging approach can monitor activity of hundreds of MPG neurons simultaneously during the filling and emptying of the bladder in a urethane-anesthetized transgenic mouse line expressing GCaMP6s in cholinergic MPG neurons. By using custom analysis scripts, we isolated the activity of hundreds of individual neurons and show that populations of neurons have distinct phasic activation patterns during sequential bladder filling and voiding events. Our imaging approach can be adapted to record activity from autonomic neurons across different organs and systems in both healthy and disease models.NEW & NOTEWORTHY The functional activity and information processing within autonomic ganglia is mostly unknown because of technical and physical constraints in recording electrophysiological signals from these neurons in vivo. Here, we use a micro-endoscopic approach to measure in vivo functional activity patterns from a population of autonomic neurons controlling bladder function for the first time. This approach can be adapted to record activity from autonomic neurons across different organs and systems in both healthy and disease models.

The T-type calcium channel Ca V 3.2 regulates bladder afferent responses to mechanical stimuli.

ABSTRACT: The bladder wall is innervated by a complex network of afferent nerves that detect bladder stretch during filling. Sensory signals, generated in response to distension, are relayed to the spinal cord and brain to evoke physiological and painful sensations and regulate urine storage and voiding. Hyperexcitability of these sensory pathways is a key component in the development of chronic bladder hypersensitivity disorders including interstitial cystitis/bladder pain syndrome and overactive bladder syndrome. Despite this, the full array of ion channels that regulate bladder afferent responses to mechanical stimuli have yet to be determined. Here, we investigated the role of low-voltage-activated T-type calcium (Ca V 3) channels in regulating bladder afferent responses to distension. Using single-cell reverse-transcription polymerase chain reaction and immunofluorescence, we revealed ubiquitous expression of Ca V 3.2, but not Ca V 3.1 or Ca V 3.3, in individual bladder-innervating dorsal root ganglia neurons. Pharmacological inhibition of Ca V 3.2 with TTA-A2 and ABT-639, selective blockers of T-type calcium channels, dose-dependently attenuated ex-vivo bladder afferent responses to distension in the absence of changes to muscle compliance. Further evaluation revealed that Ca V 3.2 blockers significantly inhibited both low- and high-threshold afferents, decreasing peak responses to distension, and delayed activation thresholds, thereby attenuating bladder afferent responses to both physiological and noxious distension. Nocifensive visceromotor responses to noxious bladder distension in vivo were also significantly reduced by inhibition of Ca V 3 with TTA-A2. Together, these data provide evidence of a major role for Ca V 3.2 in regulating bladder afferent responses to bladder distension and nociceptive signalling to the spinal cord.

Restoring bladder function using motor and sensory nerve transfers: a cadaveric feasibility study.

OBJECTIVE: Bladder dysfunction after nerve injury has a variable presentation, and extent of injury determines whether the bladder is spastic or atonic. The authors have proposed a series of 3 nerve transfers for functional innervation of the detrusor muscle and external urethral sphincter, along with sensory innervation to the genital dermatome. These transfers are applicable to only cases with low spinal segment injuries (sacral nerve root function is lost) and largely preserved lumbar function. Transfer of the posterior branch of the obturator nerve to the vesical branch of the pelvic nerve provides a feasible mechanism for patients to initiate detrusor contraction by thigh adduction. External urethra innervation (motor and sensory) may be accomplished by transfer of the vastus medialis nerve to the pudendal nerve. The sensory component of the pudendal nerve to the genitalia may be further enhanced by transfer of the saphenous nerve (sensory) to the pudendal nerve. The main limitations of coapting the nerve donors to their intrapelvic targets are the bifurcation or arborization points of the parent nerve. To ensure that the donor nerves had sufficient length and diameter, the authors sought to measure these parameters. METHODS: Twenty-six pelvic and anterior thigh regions were dissected in 13 female cadavers. After the graft and donor sites were clearly exposed and the branches identified, the donor nerves were cut at suitable distal sites and then moved into the pelvis for tensionless anastomosis. Diameters were measured with calipers. RESULTS: The obturator nerve was bifurcated a mean ± SD (range) of 5.5 ± 1.7 (2.0-9.0) cm proximal to the entrance of the obturator foramen. In every cadaver, the authors were able to bring the posterior division of the obturator nerve to the vesical branch of the pelvic nerve (located internal to the ischial spine) in a tensionless manner with an excess obturator nerve length of 2.0 ± 1.2 (0.0-5.0) cm. The distance between the femoral nerve arborization and the anterior superior iliac spine was 9.3 ± 1.8 (6.5-15.0) cm, and the distance from the femoral arborization to the ischial spine was 12.9 ± 1.4 (10.0-16.0) cm. Diameters were similar between donor and recipient nerves. CONCLUSIONS: The chosen donor nerves were long enough and of sufficient caliber for the proposed nerve transfers and tensionless anastomosis.

Efficacy of a novel wearable transcutaneous tibial nerve stimulation device on bladder reflex compared to implantable tibial nerve stimulation in cats.

OBJECTIVE: To determine the efficacy of novel wearable transcutaneous tibial nerve stimulation (TTNS) device on bladder reflex in cats compared to implantable tibial nerve stimulation (ITNS). MATERIALS AND METHODS: Two self-adhesive electrodes of the TTNS device were placed at the left leg, and ITNS was applied to stimulate the tibial nerve of the right leg, respectively. The intensity threshold (T) was defined as inducing observable toe movement. Multiple cystometrograms (CMGs) with normal saline (NS) infusion were performed to determine the inhibitory effects of TTNS and ITNS on the micturition reflex. RESULTS: TTNS at 4 times T (4 T), 6 times T (6 T), and the maximum output current intensity 24 mA significantly increased the bladder capacity (BC) compared to the control level (8.70 ± 2.46 ml) (all p < 0.05); however, there was no statistical significance among the three intensities. At the same time, ITNS at 2 times T (2 T), 4 T, 6 T, and the current intension 24 mA could significantly increase the BC compared to the control level (all p < 0.05). Likewise, no significant difference was observed among the four intensities (p > 0.05). The T values of TTNS were higher than those of ITNS (p = 0.02). The inhibitory effects of TTNS and ITNS revealed no significant difference at their respective 2 T, 4 T, 6 T, and 24 mA. Neither TTNS nor ITNS changed the contraction duration and amplitude (all p > 0.05). CONCLUSIONS: TTNS was effective in increasing BC. The non-invasive neuromodulation technique could achieve a similar effect as ITNS.

Spinal Cord Injury Causes Marked Tissue Rearrangement in the Urethra-Experimental Study in the Rat.

Traumatic spinal cord injury (SCI) results in the time-dependent development of urinary impairment due to neurogenic detrusor overactivity (NDO) and detrusor-sphincter-dyssynergia (DSD). This is known to be accompanied by massive changes in the bladder wall. It is presently less clear if the urethra wall also undergoes remodelling. To investigate this issue, female rats were submitted to complete spinal transection at the T8/T9 level and left to recover for 1 week and 4 weeks. To confirm the presence of SCI-induced NDO, bladder function was assessed by cystometry under urethane anesthesia before euthanasia. Spinal intact animals were used as controls. Urethras were collected and processed for further analysis. Following thoracic SCI, time-dependent changes in the urethra wall were observed. Histological assessment revealed marked urethral epithelium reorganization in response to SCI, as evidenced by an increase in epithelial thickness. At the muscular layer, SCI resulted in strong atrophy of the smooth muscle present in the urethral sphincter. Innervation was also affected, as evidenced by a pronounced decrease in the expression of markers of general innervation, particularly those present in sensory and sympathetic nerve fibres. The present data show an evident impact of SCI on the urethra, with significant histological rearrangement, accompanied by sensory and sympathetic denervation. It is likely that these changes will affect urethral function and contribute to SCI-induced urinary dysfunction, and they deserve further investigation.

High-density spinal cord stimulation selectively activates lower urinary tract nerves.

Objective.Epidural spinal cord stimulation (SCS) is a potential intervention to improve limb and autonomic functions, with lumbar stimulation improving locomotion and thoracic stimulation regulating blood pressure. Here, we asked whether sacral SCS could be used to target the lower urinary tract (LUT) and used a high-density epidural electrode array to test whether individual electrodes could selectively recruit LUT nerves.Approach. We placed a high-density epidural SCS array on the dorsal surface of the sacral spinal cord and cauda equina of anesthetized cats and recorded the stimulation-evoked activity from nerve cuffs on the pelvic, pudendal and sciatic nerves.Main results. Here we show that sacral SCS evokes responses in nerves innervating the bladder and urethra and that these nerves can be activated selectively. Sacral SCS always recruited the pelvic and pudendal nerves and selectively recruited both of these nerves in all but one animal. Individual branches of the pudendal nerve were always recruited as well. Electrodes that selectively recruited specific peripheral nerves were spatially clustered on the arrays, suggesting anatomically organized sensory pathways.Significance.This selective recruitment demonstrates a mechanism to directly modulate bladder and urethral function through known reflex pathways, which could be used to restore bladder and urethral function after injury or disease.

The distribution and chemical coding of urinary bladder trigone-projecting neurons in testicular and aorticorenal ganglia in male pigs.

Combined retrograde tracing and double-labelling immunofluorescence were used to investigate the distribution and chemical coding of neurons in testicular (TG) and aorticoerenal (ARG) ganglia supplying the urinary bladder trigone (UBT) in juvenile male pigs (n=4, 12 kg. of body weight). Retrograde fluorescent tracer Fast Blue (FB) was injected into the wall of the bladder trigone under pentobarbital anesthesia. After three weeks all the pigs were deeply anesthetized and transcardially perfused with 4% buffered paraformaldehyde. TG and ARG, were collected and processed for double-labelling immunofluorescence. The expression of tyrosine hydroxylase (TH) or dopamine beta-hydroxylase (DBH), neuropeptide Y (NPY), somatostatin (SOM), galanin (GAL), nitric oxide synthase (NOS) and vesicular acetylcholine transporter (VAChT) were investigated. The cryostat sections were examined with a Zeiss LSM 710 confocal microscope equipped with adequate filter blocks. The TG and ARG were found to contain many FB-positive neurons projecting to the UBT (UBT-PN). The UBT-PN were distributed in both TG and ARG. The majority of them were found in the right ganglia, mostly in TG. Immunohistochemistry disclosed that the vast majority of UBT-PN were noradrenergic (TH- and/or DBH-positive). Many noradrenergic neurons contained also immunoreactivity to NPY, SOM or GAL. Most of the UBT-PN were supplied with VAChT-, or NOS- IR (immunoreactive) varicose nerve fibres. This study has revealed a relatively large population of differently coded prevertebral neurons projecting to the porcine urinary bladder. As judged from their neurochemical organization these nerve cells constitute an important element of the complex neuro-endocrine system involved in the regulation of the porcine urogenital organ function.

Afferent nerve activity in a mouse model increases with faster bladder filling rates in vitro, but voiding behavior remains unaltered in vivo.

Storage and voiding functions in urinary bladder are well-known, yet fundamental physiological events coordinating these behaviors remain elusive. We sought to understand how voiding function is influenced by the rate at which the bladder fills. We hypothesized that faster filling rates would increase afferent sensory activity and increase micturition rate. In vivo, this would mean animals experiencing faster bladder filling would void more frequently with smaller void volumes. To test this hypothesis, we measured afferent nerve activity during different filling rates using an ex vivo mouse bladder preparation and assessed voiding frequency in normally behaving mice noninvasively (UroVoid). Bladder afferent nerve activity depended on the filling rate, with faster filling increasing afferent nerve activity at a given volume. Voiding behavior in vivo was measured in UroVoid cages. Male and female mice were given access to tap water or, to induce faster bladder filling rates, water containing 5% sucrose. Fluid intake increased dramatically in mice consuming 5% sucrose. As expected, micturition frequency was elevated in the sucrose group. However, even with the greatly increased rate of urine production, void volumes were unchanged in both genders. Although faster filling rates generated higher afferent nerve rates ex vivo, this did not translate into more frequent, smaller-volume voids in vivo. This suggests afferent nerve activity is only one factor contributing to the switch from bladder filling to micturition. Together with afferent nerve activity, higher centers in the central nervous system and the state of arousal are likely critical to coordinating the micturition reflex.

Acute Intravesical Capsaicin for the Study of TRPV1 in the Lower Urinary Tract: Clinical Relevance and Potential for Innovation.

Capsaicin acts on sensory nerves via vanilloid receptors. TRPV1 has been extensively studied with respect to functional lower urinary tract (LUT) conditions in rodents and humans. We aimed to (1) provide background information on capsaicin and TRPV1 and its mechanisms of action and basis for clinical use, (2) review the use of acute intravesical capsaicin instillation (AICI) in rodents to mimic various LUT disorders in which capsaicin sensitive C-fibers are involved and (3) discuss future innovative treatments. A comprehensive search of the major literature databases until June 2022 was conducted. Both capsaicin-sensitive and resistant unmyelinated bladder afferent C-fibers are involved in non-neurogenic overactive bladder/detrusor overactivity (OAB/DO). AICI is a suitable model to study afferent hyperactivity mimicking human OAB. Capsaicin-sensitive C-fibers are also involved in neurogenic DO (NDO) and potential targets for NDO treatment. AICI has been successfully tested for NDO treatment in humans. Capsaicin-sensitive bladder afferents are targets for NDO treatment. TRPV1-immunoreactive nerve fibers are involved in the pathogenesis of interstitial cystitis/painful bladder syndrome (IC/PBS). The AICI experimental model appears relevant for the preclinical study of treatments targeting bladder afferents for refractory IC/BPS. The activity of capsaicin-sensitive bladder afferents is increased in experimental bladder outlet obstruction (BOO). The AICI model may also be relevant for bladder disorders resulting from C-fiber hyperexcitabilities related to BOO. In conclusion, there is a rationale for the selective blockade of TRPV1 channels for various bladder disorders. The AICI model is clinically relevant for the investigation of pathophysiological conditions in which bladder C-fiber afferents are overexcited and for assessing innovative treatments for bladder disorders based on their pathophysiology.

Objective and Subjective Assessment of Bladder Function after Robot-assisted Laparoscopic Radical Hysterectomy for Early-stage Cervical Cancer.

STUDY OBJECTIVE: To examine whether objective bladder function after robot-assisted radical hysterectomy (RRH) for early-stage cervical cancer is correlated with subjective patient-reported outcomes and quality of life during the first year after RRH. DESIGN: Prospective observational study. SETTING: Karolinska University Hospital, Sweden. PATIENTS: Women with early-stage cervical cancer (International Federation of Gynecology and Obstetrics stage IA2-IB1) between July 2017 and May 2019 were assessed for eligibility. INTERVENTIONS: RRH. MEASUREMENTS AND MAIN RESULTS: Subjective bladder function was evaluated with the Female Lower Urinary Tract Symptoms and Urinary Incontinence Quality of Life modules of the International Consultation on Incontinence Questionnaire. Objective urinary function was characterized with urodynamic tests, and the nerves ablated at RRH were quantified by using immunohistochemical staining of biopsies from the resected paracervix, vesicouterine, and sacrouterine ligaments. Twenty-seven women were included for analysis at baseline, 2 weeks, 3 months, and 12 months after surgery. RRH caused hypotonia of the urinary bladder (p <.05). Patient-reported outcomes of voiding and filling dysfunction were most significant 2 weeks after surgery (p <.05) but for most of the women, bladder function recovered within 3 months. No correlations were found with either subjective or objective urinary function and the number of ablated nerves. CONCLUSION: For most women, objective and subjective urinary bladder dysfunction recovered within 3 months after RRH. The absence of correlation between functional outcomes and ablated autonomous nerves suggests that other underlying causes play a significant role. Early detection of bladder overextension after RRH is paramount, and the role of postoperative bladder catheterization needs further investigation.