Micturition Reflex Research Articles

Centrally administered corticotropin-releasing factor facilitates the rat micturition reflex via brain glutamatergic receptors

Centrally administered corticotropin-releasing factor facilitates the rat micturition reflex via brain glutamatergic receptors

Physiological Importance of Apan Vayu in Mutranishkramanprakriya in Relation to Micturition Reflex

Ayurvedais an ancient Indian system of medicine whose major goal is to keep healthy people well and cure diseased people. That is why, from ancient times, people from all over the world have been looking to India. Health, according to Ayurveda, is a state in which the dosha, agni, dhaatu, mala, and all physiological processes are in a homeostatic state, and the soul, sense organs, and mind are all in a state of absolute wellbeing. The Vatadoshais the most significant of the three doshas, and it is in charge of controlling all types of movements. Aaharais turned into saaraand kittapart when the food is digested by agniwith the help of samanavayu. With the harmonization of other Pranaand Vyanavayus, apanavayueliminates the kittapart of food.In pakvadhana, the apanavayupasses through the sroni(pelvis), basti(urinary bladder), medhra(external genital equipment of each sex), and uru(thighs). It aids samirana(flatus), sakrit(feces), mutra(urine), sukra(semen), garbha(foetus), and artava(menstrual fluid) removal.An attempt has been made in this article to comprehend the physiological significance of apanvayuin micturition. The core resources for this study were gathered from Ayurvedicclassics with available commentaries, as well as modern medical science text books for a better grasp of the subject

Serial transurethral cystometry: A novel method for longitudinal evaluation of reflex lower urinary tract function in adult female rats.

AimsThe aim of the study is to develop a minimally invasive method for longitudinal evaluation of lower urinary tract function that allows for simultaneous measurements of bladder pressure and external urethral sphincter (EUS) electromyographic (EMG) activity.MethodsTo evaluate the reliability of serial transurethral cystometry (STUC), rats (n = 12) underwent three sessions of STUC, one session a week for 3 weeks. During each session, rats were anesthetized with ketamine–xylazine (90 mg/kg and 10 mg/kg), and micturition reflex data were acquired using transurethral cystometry and percutaneous recording of EUS (EMG) activity during continuous infusion of saline into the bladder. The reliability and consistency of the STUC method were assessed using intra‐class correlation (ICC) analysis and repeated measures ANOVA.ResultsICC values calculated from five successive events during the first micturition session indicate good to excellent reliability for measurements of peak bladder pressure, threshold bladder pressure, minimum bladder pressure, volume threshold, duration of EUS bursting, and number of EUS burst events. Across the three recording sessions no significant difference was observed in peak bladder pressure, threshold bladder pressure, minimum bladder pressure, volume threshold, number of EUS burst events, and duration of EUS bursting using repeated measures ANOVA.ConclusionSerial transurethral cystometry under ketamine–xylazine anesthesia with simultaneous percutaneous EUS EMG recording is a novel, reliable, accurate, and minimally invasive method for quantitative assessment of lower urinary tract (LUT) function in adult female rats over extended periods of time.

Current Knowledge and Novel Frontiers in Lower Urinary Tract Dysfunction after Spinal Cord Injury: Basic Research Perspectives.

This review article aims to summarize the recent advancement in basic research on lower urinary tract dysfunction (LUTD) following spinal cord injury (SCI) above the sacral level. We particularly focused on the neurophysiologic mechanisms controlling the lower urinary tract (LUT) function and the SCI-induced changes in micturition control in animal models of SCI. The LUT has two main functions, the storage and voiding of urine, that are regulated by a complex neural control system. This neural system coordinates the activity of two functional units in the LUT: the urinary bladder and an outlet including bladder neck, urethra, and striated muscles of the pelvic floor. During the storage phase, the outlet is closed and the bladder is quiescent to maintain a low intravesical pressure and continence, and during the voiding phase, the outlet relaxes and the bladder contracts to promote efficient release of urine. SCI impairs voluntary control of voiding as well as the normal reflex pathways that coordinate bladder and sphincter function. Following SCI, the bladder is initially areflexic but then becomes hyperreflexic due to the emergence of a spinal micturition reflex pathway. However, the bladder does not empty efficiently because coordination between the bladder and urethral sphincter is lost. In animal models of SCI, hyperexcitability of silent C-fiber bladder afferents is a major pathophysiological basis of neurogenic LUTD, especially detrusor overactivity. Reflex plasticity is associated with changes in the properties of neuropeptides, neurotrophic factors, or chemical receptors of afferent neurons. Not only C-fiber but also Aδ-fiber could be involved in the emergence of neurogenic LUTD such as detrusor sphincter dyssynergia following SCI. Animal research using disease models helps us to detect the different contributing factors for LUTD due to SCI and to find potential targets for new treatments.

The role of lumbosacral innervating noradrenergic neurons in micturition control

A long-standing observation is that the micturition reflex receives supraspinal descending control. Although one supraspinal nucleus (Barrington’s nucleus) is identified as the pontine micturition center, it remains largely unknown whether and how other supraspinal tracts are involved in micturition control. Here, we focused on the role of lumbosacral projecting neurons located in the Locus Coeruleus (LC) in modulating micturition, since previous studies indicated that the LC is involved in controlling bladder contraction. First, by performing an AAV mediated retrograde labeling using a TH-iCre mouse line, we demonstrated specific targeting of LC noradrenergic neurons innervating the lumbosacral spinal cord with high efficiency. Next, by lumbosacral injection of a retro-AAV carrying Cre-dependent human diphtheria toxin receptors (DTR), we achieved specific ablation of LC NA+ neurons with lumbosacral projections upon the administration of diphtheria toxin. Our results showed that specific ablation of theseneurons led to overflow incontinence leaks and lower void efficiency. Mechanistically, by performing the urodynamics analysis, we showed that ablation of lumbosacral innervating NAneurons resulted in detrusor-sphincter dyssynergia. Taken together, our study provided novel insights into the underlying mechanisms of supraspinal control of micturition reflex and thus shed light on developing novel treatment to improve micturition control in patients with SCI or lower urinary tract symptoms.

Dual-Pseudorabies Viral Tracing for Spinal Tyrosine Hydroxylase Interneurons Involved in Segmental Micturition Reflex Circuitry in Spinal Cord Injured Rats.

Traumatic spinal cord injury (SCI) often leads to urinary dysfunction. Although an involuntary micturition reflex can be established to elicit voiding with time, complications arise in the form of bladder hyper-reflexia and detrusor-sphincter dyssynergia that cause incontinence and inefficient expulsion of urine. To date, the neuronal mechanisms that underlie regulation of micturition after SCI are not well understood. We recently observed an increase of a population of tyrosine hydroxylase (TH)+ cells in the rat lumbosacral cord post-SCI, which contribute to the sustention of a low level of dopamine that modulates the recovered bladder reflex. To identify whether spinal TH+ cells are involved in the micturition reflex pathway post-SCI, two isoforms of the trans-synaptic retrograde tracer, pseudorabies virus encoding green fluorescent protein (GFP; PRV-152) or red fluorescent protein (RFP; PRV-614), were injected into the bladder detrusor or the external urethral sphincter (EUS), respectively, 3 weeks after a spinal cord transection at the 10th thoracic level (T10) in rats. Immunohistochemistry was performed to examine infected TH+ cells in the caudal cord at both 48 and 72 h post-injection. As a result, double-labeled TH+/GFP+ and TH+/RFP+ cells could be found in the superficial dorsal horn, parasympathetic nuclei, and dorsal gray commissure (lamina X) at both time points. More importantly, a shared population of TH+ interneurons (TH+/GFP+/RFP+) exists between bladder and EUS circuitry. These results suggest that spinal TH+ interneurons may coordinate activity of the bladder and EUS that occurs during micturition reflexes post-SCI.

Liberation of Serotonin Is Not Unaffected by Acetylcholine in Rat Hippocampus.

PurposeRaised cerebral titers of acetylcholine have notable links with storage symptomatology related to lower urinary tract symptoms. The hippocampus contributes to the normal control of continence in the majority of instances (circuit 3). Owing to synaptic connections with other nerve cells, acetylcholine affects the micturition pathway via the liberation of additional cerebral neurotransmitters. Despite the fact that cerebral serotonin is a key inhibitor of reflex bladder muscle contractions, the influence of acetylcholine on its liberation is poorly delineated. The current research was conducted in order to explore the role of acetylcholine in serotonin liberation from sections of rat hippocampus in order to improve the comprehension of the relationship between cholinergic and serotonergic neurons.MethodsHippocampal sections from 6 mature male Sprague-Dawley rats were equilibrated over a 30-minute period in standard incubation medium so as to facilitate [3H]5-hydroxytryptamine (5-HT) uptake. The cerebral neurotransmitter, acetylcholine, was applied to the sections. Aliquots of drained medium solution were utilized in order to quantify the radioactivity associated with [3H]5-HT liberation; any alterations in this parameter were noted.ResultsWhen judged against the controls, [3H]5-HT liberation from the hippocampal sections remained unaltered following the administration of acetylcholine, implying that this agent has no inhibitory action on this process.ConclusionsSerotonin liberation from murine hippocampal sections is unaffected by acetylcholine. It is postulated that the bladder micturition reflex responds to acetylcholine through its immediate cholinergic activity rather than by its influence on serotonin release. These pathways are a promising target for the design of de novo therapeutic agents.

Estrogen inhibits bladder overactivity in rats with cyclophosphamide-induced cystitis via downregulating the expression of P2X3 receptors in bladder epithelium cells.

The therapeutic effect of estrogen on interstitial cystitis/bladder pain syndrome is unclear. We aim to explore the effect of estrogen on bladder overactivity in rats with cyclophosphamide-induced cystitis and its underlying mechanism. In vivo cystometry was used to determine the effect of estrogen on bladder excitability. The effect of estrogen on the expression of P2X3 receptors in bladder epithelium was detected by real-time polymerase chain reaction and western blot. Effect of P2X3 receptors in bladder urothelium on stretch-released adenosine triphosphate was performed by a Flexcell FX5000 Compression system and an Enzyme-Linked Immunosorbent Assay Kit. Estrogen deprivation significantly increased the urinary frequency, while supplementation with diarylpropionitrile (DPN), an estrogen receptor β (ERβ) agonist, alleviated the urinary frequency. 17β-Estradiol and DPN decreased the expression of P2X3 receptors in urothelium cells which was partially inhibited by ERβ antagonist 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a]pyrimidin-3-yl]phenol. Meanwhile, inhibiting the expression of P2X3 receptors by ERβ agonist or antagonizing the function of P2X3 receptors by selective P2X3 receptor antagonist AF-353 or A-317491 significantly reduced the stretch-released ATP from urothelium cells. Estrogen has a direct effect on the regulation of bladder overactivity in rats with cyclophosphamide-induced cystitis by downregulating the expression of bladder epithelial P2X3 receptors through ERβ and reducing the adenosine triphosphate released from urothelium during bladder filling, thereby inhibiting the generation of the micturition reflex.

Urothelial Calcium-Sensing Receptor Modulates Micturition Function via Mediating Detrusor Activity and Ameliorates Bladder Hyperactivity in Rats.

The urothelium displays mechano- and chemosensory functions via numerous receptors and channels. The calcium-sensing receptor (CaSR) detects extracellular calcium and modulates several physiological functions. Nonetheless, information about the expression and the role of CaSR in lower urinary tract has been absent. We aimed to determine the existence of urothelial CaSR in urinary bladder and its effect on micturition function. We utilized Western blot to confirm the expression of CaSR in bladder and used immunofluorescence to verify the location of the CaSR in the bladder urothelium via colocalization with uroplakin III A. The activation of urothelial CaSR via the CaSR agonist, AC-265347 (AC), decreased urinary bladder smooth muscle (detrusor) activity, whereas its inhibition via the CaSR antagonist, NPS-2143 hydrochloride (NPS), increased detrusor activity in in vitro myography experiments. Cystometry, bladder nerve activities recording, and bladder surface microcirculation detection were conducted to evaluate the effects of the urothelial CaSR via intravesical administrations. Intravesical AC inhibited micturition reflex, bladder afferent and efferent nerve activities, and reversed cystitis-induced bladder hyperactivity. The urothelial CaSR demonstrated a chemosensory function, and modulated micturition reflex via regulating detrusor activity. This study provided further evidence of how the urothelial CaSR mediated micturition and implicated the urothelial CaSR as a potential pharmacotherapeutic target in the intervention of bladder disorders.

Analyses of the Mode of Action of an Alpha-Adrenoceptor Blocker in Substantia Gelatinosa Neurons in Rats.

To elucidate why naftopidil increases the frequency of spontaneous synaptic currents in only some substantia gelatinosa (SG) neurons, post-hoc analyses were performed. Blind patch-clamp recording was performed using slice preparations of SG neurons from the spinal cords of adult rats. Spontaneous inhibitory and excitatory postsynaptic currents (sIPSCs and sEPSCs, respectively) were recorded. The ratios of the frequency and amplitude of the sIPSCs and sEPSCs following the introduction of naftopidil compared with baseline, and after the application of naftopidil, serotonin (5-HT), and prazosin, compared with noradrenaline (NA) were evaluated. First, the sIPSC analysis indicated that SG neurons reached their full response ratio for NA at 50 μM. Second, they responded to 5-HT (50 μM) with a response ratio similar to that for NA, but prazosin (10 μM) did not change the sEPSCs and sIPSCs. Third, the highest concentration of naftopidil (100 μM) led to two types of response in the SG neurons, which corresponded with the reactions to 5-HT and prazosin. These results indicate that not all neurons were necessarily activated by naftopidil, and that the micturition reflex may be regulated in a sophisticated manner by inhibitory mechanisms in these interneurons.

MP08-15 HIGH-RESOLUTION EPIDURAL SPINAL CORD STIMULATION (HR-SCS) EVOKES SELECTIVE MICTURITION AND CONTINENCE REFLEXES THROUGH A FREQUENCY-DEPENDENT EFFECT GOVERNED BY DISTINCT NEURAL CIRCUITS

You have accessJournal of UrologyBladder & Urethra: Anatomy, Physiology & Pharmacology (MP08)1 Sep 2021MP08-15 HIGH-RESOLUTION EPIDURAL SPINAL CORD STIMULATION (HR-SCS) EVOKES SELECTIVE MICTURITION AND CONTINENCE REFLEXES THROUGH A FREQUENCY-DEPENDENT EFFECT GOVERNED BY DISTINCT NEURAL CIRCUITS Chaitanya Gopinath, Maria K. Jantz, Ritesh Kumar, Bryan L. McLaughlin, and Robert A. Gaunt Chaitanya GopinathChaitanya Gopinath More articles by this author , Maria K. JantzMaria K. Jantz More articles by this author , Ritesh KumarRitesh Kumar More articles by this author , Bryan L. McLaughlinBryan L. McLaughlin More articles by this author , and Robert A. GauntRobert A. Gaunt More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000001981.15AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Spinal cord stimulation (SCS) has been explored for controlling lower urinary tract function in experimental and clinical settings. However, there are no mechanistic and reproducible approaches to evoke both micturition and continence reflexes. Here, we demonstrate that epidural SCS can selectively evoke micturition and continence behaviors in both isovolumetric and cystometric studies in feline anesthetized animal model. Our results indicate the existence of two distinct frequency-dependent neural circuits mediating continence and micturition evoked by varying stimulus frequencies. METHODS: Three male and three female cats (n=6) were anesthetized with α-chloralose after initial surgical preparations under isoflurane anesthesia. Nerve cuffs were placed unilaterally on the pelvic nerve, pudendal nerve and its branches (sensory, deep perineal and caudal rectal nerves). HR-SCS electrodes (Ripple Neuro, Micro-Leads Medical) were placed on the epidural surface of sacral cord and cauda equina. Stimulation pulse trains with amplitudes between 200-800 µA were delivered through SCS electrodes while recording bladder pressure and compound action potentials in the peripheral nerve cuffs. Electromyograms from the pelvic floor and urethral sphincter, as well as bladder pressure data were collected, first under isovolumetric bladder conditions and later during filling cystometries. RESULTS: Epidural SCS through many electrodes was able to elicit functional changes in the bladder and urethra. We also identified bipolar electrode pairs that evoked a frequency-dependent effect. Stimulation at 3 Hz stimulation evoked a continence reflex, while the same electrodes evoked a voiding reflex when the stimulation frequency was changed to 33 Hz. Inhibition through 3 Hz stimulation was particularly robust and resulted in abolishing all non-voiding contractions (NVCs) and decreasing the bladder pressure to its baseline value. Voiding under 33 Hz was incomplete and varied between 20-50% of the infused volume. In 3 animals, an acute spinalization at T10 abolished all 33 Hz-evoked responses suggesting that this neural circuit requires an intact spino-bulbo-spinal reflex. The 3 Hz continence reflex remained unaffected by spinalization suggesting a local reflex in the lumbosacral spinal cord. CONCLUSIONS: HR-SCS can selectively evoke continence and micturition reflexes through a unique frequency-dependent effect. Source of Funding: NIH OT2OD024908 and Craig H. Neilsen Foundation—476681 © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e155-e156 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Chaitanya Gopinath More articles by this author Maria K. Jantz More articles by this author Ritesh Kumar More articles by this author Bryan L. McLaughlin More articles by this author Robert A. Gaunt More articles by this author Expand All Advertisement Loading ...

Learned control of urinary reflexes in cattle to help reduce greenhouse gas emissions

Indiscriminate voiding of excreta by cattle contributes to greenhouse gas (GHG) emissions and soil and water contamination1,2. Emissions are higher in animal-friendly husbandry offering cattle more space2 - a trade-off we call the 'climate killer conundrum'. Voiding in a specific location (latrine) would help resolve this dilemma by allowing ready capture and treatment of excreta under more spacious farming conditions. For urination, toileting requires self-control and coordination of a complex chain of behaviors including awareness of bladder fullness, overriding of excretory reflexes, selection of a latrine and intentional relaxation of the external urethral sphincter3. Attempts to train toileting in cattle have so far been only partly successful4-6, even though their excretion and associated neurophysiological control are similar to those in species capable of toileting3. Similarly, very young infants have been considered incapable of self-initiated voiding, but they can be taught with extensive training7. Using a backward chaining, reward-based training procedure, we here show that cattle can control their micturition reflex and use a latrine for urination. Such self-control provides evidence that animals can learn to respond to and reveal internal experiences via appropriately trained operant behaviors, thereby providing another way to explore their subjective states.

MP08-03 BRAIN HYDROGEN SULFIDE SUPPRESSES THE RAT MICTURITION REFLEX VIA BRAIN GABA RECEPTORS

You have accessJournal of UrologyBladder & Urethra: Anatomy, Physiology & Pharmacology (MP08)1 Sep 2021MP08-03 BRAIN HYDROGEN SULFIDE SUPPRESSES THE RAT MICTURITION REFLEX VIA BRAIN GABA RECEPTORS Masaki Yamamoto, Takahiro Shimizu, Suo Zou, Shogo Shimizu, Youichirou Higashi, Mikiya Fujieda, and Motoaki Saito Masaki YamamotoMasaki Yamamoto More articles by this author , Takahiro ShimizuTakahiro Shimizu More articles by this author , Suo ZouSuo Zou More articles by this author , Shogo ShimizuShogo Shimizu More articles by this author , Youichirou HigashiYouichirou Higashi More articles by this author , Mikiya FujiedaMikiya Fujieda More articles by this author , and Motoaki SaitoMotoaki Saito More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000001981.03AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: We previously reported that hydrogen sulfide (H2S), an endogenous gasotransmitter, is a possible relaxation factor in the rat bladder. However, roles of central H2S in regulation of the micturition reflex are unknown. In this study, we examined effects of centrally administered GYY4137 (GYY, H2S donor) and AOAA (H2S synthesis inhibitor) on the rat micturition reflex. METHODS: Urethane anesthetized (0.8 g/kg, ip) male Wistar rats (350-400 g) were used. A catheter was inserted into the bladder to perform continuous cystometry (12 ml/h saline infusion). Three hours after the surgery, GYY (3 or 10 nmol/rat), AOAA (30 or 100 μg/rat) or vehicle was intracerebroventricularly (ICV) administered. In some rats, effects of ICV pretreated SR95531 (SR, GABAA antagonist, 0.1 nmol/rat) or SCH50911 (SCH, GABAB antagonist, 0.1 nmol/rat) on the GYY (10 nmol/rat, ICV)-induced responses were investigated. Continuous cystometry and evaluation of intercontraction intervals (ICI) and maximal voiding pressure (MVP) were started 60 min before the first ICV administration. In some rats, before and after AOAA administration (30 μg/rat, ICV), single cystometry (12 ml/h saline infusion) was performed. RESULTS: GYY dose-dependently prolonged ICI without changing MVP (fig. 1A-B). On the other hand, AOAA significantly shortened ICI without changing MVP (fig. 1C-D). In single cystometry, AOAA significantly reduced single-voided volume and bladder capacity without increasing post-voiding residual volume or voiding efficiency (table 1). The AOAA (30 μg/rat, ICV)-induced ICI shortening was reversed in the central presence of GYY (10 nmol/rat, ICV) (data not shown). The GYY-induced ICI prolongation was suppressed by SR and SCH (fig. 2A-B). CONCLUSIONS: Brain H2S endogenously suppresses the rat micturition reflex via brain GABAA and GABAB receptors in rats. Thus, the brain H2S might be new therapeutic targets for neurogenic bladder overactivity. Source of Funding: JSPS KAKENHI (#17K09303, #20K07827), Takeda Science Foundation © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e150-e150 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Masaki Yamamoto More articles by this author Takahiro Shimizu More articles by this author Suo Zou More articles by this author Shogo Shimizu More articles by this author Youichirou Higashi More articles by this author Mikiya Fujieda More articles by this author Motoaki Saito More articles by this author Expand All Advertisement Loading ...

Validation of a new rat model of urethral sphincter injury and leak point pressure measurements

Aims In vivo experiments were performed to establish and validate a rat model of urethral sphincter injury and to develop a method for leak point pressure (LPP) measurements performed repeatedly in the same animal. Methods Twenty-four Sprague-Dawley female rats underwent bladder and epidural catheter implantation. Five days later, cystometry was performed using continuous infusion. Anesthesia with isoflurane, ketamine-xylazine (KX) or fentanyl-fluanisone-midazolam (FFM) was used. After three micturition cycles, intrathecal bupivacaine was administered leading to the suppression of reflex bladder contractions. LPP measurements were performed using vertical tilt. After the initial LPP measurement, animals underwent partial resection of the striated urethral sphincter. The effect was evaluated 6 weeks after surgery, by repeating the LPP measurement in the same animal. Results Ten out of 19 animals showed full micturition cycles under isoflurane, and all 9 animals under KX anesthesia. No significant difference in micturition pressures (Mean ± SEM; 30.1 ± 2.3 vs. 26.8 ± 1.6 mmHg) and LPP (31.0 ± 2.4 vs. 28.0 ± 0.9 mmHg) was observed between isoflurane and KX groups, respectively. Reflex micturition was suppressed with FFM. Bupivacaine led to overflow incontinence in all cases. Sphincter injury caused fibrotic changes and a significant increase in LPP (26.4 ± 2.3 before vs. 46.9 ± 4.6 mmHg after injury, p < 0.05). Conclusions KX anesthesia preserves bladder contractions. Intrathecal bupivacaine eliminates reflex micturition, allowing for repeated LPP measurements in the same animal. Resection of striated sphincter resulted in increased LPP 6 weeks post injury. The site of urethral sphincter resection healed with fibrosis.

The nitric oxide-cyclic guanosine monophosphate pathway inhibits the bladder ATP release in response to a physiological or pathological stimulus.

The release of ATP from the epithelium of the urinary bladder (urothelium) in response to mechanical/chemical stimuli contributes to the visceral sensation in the micturition reflex. The nitric oxide (NO)‐mediated induction of cyclic guanosine monophosphate (cGMP) has been detected in urothelial cells and may inhibit the micturition reflex. However, the function of the NO‐cGMP pathway in the regulation of urothelial ATP release remains poorly understood in contrast to its effects on smooth muscles or primary afferent nerves. Therefore, we investigated the relevance of the NO‐cGMP pathway to ATP release on the mucosal side in the present study. The administration of l‐arginine (NO precursor) or NOC 12 (NO donor) significantly reduced ATP release to the mucosal side at a physiologically normal urine storage pressure (5 cmH2O). L‐NAME (NO synthase inhibitor) significantly increased the distention‐induced release of ATP. The phosphodiesterase‐5 inhibitor, sildenafil, which increases cGMP levels, inhibited distention‐induced ATP release. Furthermore, sildenafil significantly reduced ATP release in response to the administration of lipopolysaccharide. These results suggest that the NO‐cGMP pathway inhibited urothelial ATP release during the storage phase under both physiological and pathological conditions.

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

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

Corticotropin-Releasing Hormone from the Pontine Micturition Center Plays an Inhibitory Role in Micturition.

Lower urinary tract or voiding disorders are prevalent across all ages and affect >40% of adults over 40 years old, leading to decreased quality of life and high health care costs. The pontine micturition center (PMC; i.e., Barrington's nucleus) contains a large population of neurons that localize the stress-related neuropeptide, corticotropin-releasing hormone (CRH) and project to neurons in the spinal cord to regulate micturition. How the PMC and CRH-expressing neurons in the PMC control volitional micturition is of critical importance for human voiding disorders. To investigate the specific role of CRH in the PMC, neurons in the PMC-expressing CRH were optogenetically activated during in vivo cystometry in unanesthetized mice of either sex. Optogenetic activation of CRH-PMC neurons led to increased intermicturition interval and voided volume, similar to the altered voiding phenotype produced by social stress. Female mice showed a significantly more pronounced phenotype change compared with male mice. These effects were eliminated by CRH-receptor 1 antagonist pretreatment. Optogenetic inhibition of CRH-PMC neurons led to an altered voiding phenotype characterized by more frequent voids and smaller voided volumes. Last, in a cyclophosphamide cystitis model of bladder overactivity, optogenetic activation of CRH-PMC neurons returned the voiding pattern to normal. Collectively, our findings demonstrate that CRH from PMC spinal-projecting neurons has an inhibitory function on micturition and is a potential therapeutic target for human disease states, such as voiding postponement, urinary retention, and underactive or overactive bladder.SIGNIFICANCE STATEMENT The pontine micturition center (PMC), which is a major regulator of volitional micturition, is neurochemically heterogeneous, and excitatory neurotransmission derived from PMC neurons is thought to mediate the micturition reflex. In the present study, using optogenetic manipulation of CRH-containing neurons in double-transgenic mice, we demonstrate that CRH, which is prominent in PMC-spinal projections, has an inhibitory function on volitional micturition. Moreover, engaging this inhibitory function of CRH can ameliorate bladder hyperexcitability induced by cyclophosphamide in a model of cystitis. The data underscore CRH as a novel target for the treatment of voiding dysfunctions, which are highly prevalent disease processes in children and adults.

Anesthetic protocols for urodynamic studies of the lower urinary tract in small rodents-A systematic review.

Urodynamic studies in rats and mice are broadly used to examine pathomechnisms of disease and identify and test therapeutic targets. This review aims to highlight the effects of the anesthetics on the lower urinary tract function and seeks to identify protocols that allow recovery from anesthesia and repeated measurements while preserving the function which is being studied. All studies published in English language, which compared the data obtained under various types of anesthesia and the urodynamics performed in awake animals were included. It appears that urethane, an anesthetic recommended extensively for the investigation of lower urinary tract function, is appropriate for acute urodynamic studies only. Major advantages of urethane are its stability and ability to preserve the micturition reflex. Due to its toxicity and carcinogenicity, urethane anesthesia should not be used for recovery procedures. This review evaluated available alternatives including propofol, isoflurane and combinations of urethane, ketamine/xylazine, ketamine/medetomidine, and/or fentanyl/fluanisone/midazolam. Different effects have been demonstrated among these drugs on the urinary bladder, the urethral sphincter, as well as on their neuroregulation. The lowest incidence of adverse effects was observed with the use of a combination of ketamine and xylazine. Although the variations in the reviewed study protocols represent a limitation, we believe that this summary will help in standardizing and optimizing future experiments.

Pathogenesis evidence from human and animal models of detrusor underactivity

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

Telocytes of the male urogenital system: Interrelationships, possible functions, and pathological implications.

The male urogenital system is composed of the reproductive system and the urinary tract; they have an interconnected embryonic development and share one of their anatomical components, the urethra. This system has a highly complex physiology deeply interconnected with the circulatory and nervous systems, as well as being capable of adapting to environmental variations; it also undergoes changes with aging and, in the case of the reproductive system, with seasonality. The stroma is an essential component in this physiological plasticity and its complexity has increased with the description in the last decade of a new cell type, the telocyte. Several studies have demonstrated the presence of telocytes in the organs of the male urogenital system and other systems; however, their exact function is not yet known. The present review addresses current knowledge about telocytes in the urogenital system in terms of their locations, interrelationships, possible functions and pathological implications. It has been found that telocytes in the urogenital system possibly have a leading role in stromal tissue organization/maintenance, in addition to participation in stem cell niches and an association with the immune system, as well as specific functions in the urogenital system, lipid synthesis in the testes, erythropoiesis in the kidneys and the micturition reflex in the bladder. There is also evidence that telocytes are involved in pathologies in the kidneys, urethra, bladder, prostate, and testes.