Pelvic Organ Cross-sensitization Research Articles

Organ cross-sensitization mechanisms in chronic diseases related to the genitourinary tract.

There are various refractory chronic inflammatory diseases related to the genitourinary tract, such as interstitial cystitis/bladder pain syndrome and chronic prostatitis/chronic pelvic pain syndrome. It has been reported that in the general population, these diseases are related to other chronic illnesses, such as irritable bowel syndrome or vulvodynia. Herein, we review papers regarding pelvic organ cross-sensitization, a factor which is considered to contribute to these relationships. Several other researchers and ourselves have reported that noxious stimuli from a diseased pelvic organ are transmitted to an adjacent normal structure via shared sensory neural pathways at the prespinal, spinal, and supraspinal levels, resulting in functional changes in the adjacent normal structure. In conclusion, since there are few treatments to cure interstitial cystitis/bladder pain syndrome and chronic prostatitis/chronic pelvic pain syndrome completely, further studies regarding organ cross-sensitization may provide new insights into the pathophysiology and treatment strategies for these diseases.

Bladder-bowel interactions: Do we understand pelvic organ cross-sensitization? International Consultation on Incontinence Research Society (ICI-RS) 2018.

Mounting evidence from experimental animal and human studies suggests that cross-sensitization exists between different organs. Lower urinary tract (LUT) and bowel dysfunction commonly overlap, and the role of cross-sensitization between pelvic visceral organs is uncertain. At the International Consultation on Incontinence Research Society (ICI-RS) meeting in 2018, a panel of clinicians participated in a discussion on bladder and bowel interactions in the context of pelvic organ cross-sensitization. Bladder and bowel problems commonly co-occur in adults and children across different disorders, and the mechanism responsible for overlapping dysfunction is uncertain in most instances. At a neuronal level, cross-sensitization occurs as a result of afferent signaling from the LUT and lower bowel through different central and peripheral mechanisms. Studies in animals and humans have demonstrated evidence for cross-organ sensitization following experimental inflammation or distension of the lower bowel, affecting the LUT. Nerve stimulation is an effective treatment for different functional LUT and bowel disorders, and whether this treatment may influence cross-organ sensitization remains uncertain. The role of physiologically dormant C-fibers, the bladder-gut-brain axis, and gut microbiome in cross-sensitization are speculative. Recommendations for research were made to explore the role of cross-organ sensitization in the pathogenesis of co-occurring LUT and bowel dysfunction in humans.

Editorial Comment from Dr Yoshimura to Gynecological associated disorders and management

This article by the group of Dr. Whitmore described concisely and thoroughly the current status of the diagnosis and management of chronic pelvic pain (CPP) or CPP syndrome (CPPS), particularly focusing on gynecological aspects of this often difficult-to-treat disease condition. Because CPPS is a larger umbrella of painful disorders encompassing different pelvic organs or structures including uterus, external genital organs (female or male), bladder, colon and pelvic floor muscles, there are significantly overlapping symptoms in CPPS patients, in whom multiple domains are involved in the emergence of overall symptoms. In this IJU special issue of the 2018 International Consultation on Interstitial Cystitis Japan (ICICJ) meeting, Dr. Ueda's group showed that the involvement of multiple domains is also the case in men with CPPS, in which a number of patients who were symptomatically diagnosed to have chronic prostatitis showed a co-morbidity of cystoscopically-confirmed interstitial cystitis. Recent studies using animal models also revealed that pelvic organ cross-sensitization among bladder, colon, uterus or prostate greatly contributes to pelvic pain and bladder hypersensitivity, suggesting that multiple pelvic organs interact each other to exhibit the final symptomatic profile of CPPS. Thus, multidisciplinary approaches should be taken to explore the contribution of each domain of different pelvic organs or structures to the overall CPP symptoms including those of sexual dysfunction, as well described in this review, which could hopefully lead to the individualized treatment for better therapeutic outcomes in patients with CPPS. None declared.

Liposome Based Intravesical Therapy Targeting Nerve Growth Factor Ameliorates Bladder Hypersensitivity in Rats with Experimental Colitis

Pelvic organ cross sensitization is considered to contribute to overlapping symptoms in chronic pelvic pain syndrome. Nerve growth factor over expression in the bladder is reportedly involved in the symptom development of bladder pain syndrome/interstitial cystitis. We examined whether a reduction of over expressed nerve growth factor in the bladder by intravesical treatment with liposome and oligonucleotide conjugates would ameliorate bladder hypersensitivity in a rat colitis model. Adult female rats were divided into 1) a control group, 2) a colitis-oligonucleotide group with intracolonic TNBS (2,4,6-trinitrobenzene sulfonic acid) enema and intravesical liposome-oligonucleotide treatments, 2) a colitis-saline group with intracolonic TNBS and intravesical saline treatments, 4) a sham oligonucleotide group with intravesical liposome-oligonucleotide treatment without colitis and 5) a sham-saline group with intravesical saline treatment without colitis. Liposomes conjugated with nerve growth factor antisense oligonucleotide or saline solution were instilled in the bladder and 24 hours later colitis was induced by TNBS enema. Effects of nerve growth factor antisense treatment were evaluated by pain behavior, cystometry, molecular analyses and immunohistochemistry 10 days after TNBS treatment. In colitis-oligonucleotide rats nerve growth factor antisense treatment ameliorated pain behavior and decreased a reduction in the intercontraction interval in response to acetic acid stimulation as well as nerve growth factor expression in the bladder mucosa. All were enhanced in colitis-saline rats compared to sham rats. Nerve growth factor over expression in the bladder mucosa and bladder hypersensitivity induced after colitis were decreased by intravesical application of liposome-oligonucleotide targeting nerve growth factor. This suggests that local antinerve growth factor therapy could be effective treatment of bladder symptoms in chronic pelvic pain syndrome.

Upregulation of α₂δ-1 Calcium Channel Subunit in the Spinal Cord Contributes to Pelvic Organ Cross-Sensitization in a Rat Model of Experimentally-Induced Endometriosis.

Pelvic organ cross-sensitization, also termed as viscero-visceral referred hyperalgesia, is a major contributor to painful endometriosis. Its underlying mechanism is poorly understood. Clinical and basic studies have shown that gabapentin, a drug that binds to the α2δ-1 subunit of voltage-dependent calcium channels (Cavα2δ-1), is effective in treating chronic visceral pain. Accordingly, we hypothesized that pelvic organ cross-sensitization in painful endometriosis is mediated by an upregulation of Cavα2δ-1 in the spinal cord. We examined if the dysregulation of spinal Cavα2δ-1 subunit may play an important role in the development of ectopic growths-to-colon cross-sensitization in a rat model of experimentally-induced endometriosis. Our findings suggest that there was an increased Cavα2δ-1 expression in the dorsal horn and an ectopic growths-to-colon cross-sensitization in female rats with established endometriosis. Intrathecal administration of gabapentin (300 μg) remarkably reduced the ectopic growths-to-colon cross-sensitization in rats with established endometriosis. Furthermore, intrathecal injection of Cavα2δ-1 antisense oligodeoxynucleotides reversed the ectopic growths-to-colon cross-sensitization and also normalized the upregulation of spinal Cavα2δ-1 expression in endometriosis rats. The current study suggests that the upregulation of Cavα2δ-1 in the spinal cord may contribute to pelvic organ cross-sensitization in painful endometriosis. Our study may provide a biological basis for selectively targeting this pathway to relieve viscero-visceral referred hyperalgesia in patients with painful endometriosis.

Activation of p38 MAPK in the rostral ventromedial medulla by visceral noxious inputs transmitted via the dorsal columns may contribute to pelvic organ cross-sensitization in rats with endometriosis

Whether visceral organ cross-sensitization is involved in endometriosis-associated pain remains elusive. Previous studies have shown that visceral noxious stimuli may trigger a cascade of signal transductions in the rostral ventromedial medulla (RVM) via the spinal dorsal column (DC) pathway and the RVM plays a critical role in the descending control of visceral nociception. In the current study, we hypothesized that the p38 mitogen-activated protein kinase (MAPK) activation in the RVM by noxious visceral inputs from ectopic growths via the DC was involved in the development of pelvic organ cross-sensitization in established endometriosis. A rat model of experimental endometriosis was established. To examine ectopic growths-to-colon cross-sensitization, graded colorectal distention (CRD) was performed and abdominal withdrawal reflex (AWR) scores were recorded in female rats at 8weeks after the uterine or fat (control) auto-transplantation. Western blot study was carried out to examine the phosphorylated form and the total level of p38 MAPK protein in the RVM. Our results showed that lesions of bilateral DCs immediately following uterine or fat auto-transplantation in female rats significantly attenuated the later development of ectopic growths-to-colon cross-sensitization and the increased p38 MAPK activation in the RVM, as compared to sham DC lesions. Furthermore, intra-RVM microinjection of a p38 MAPK inhibitor (SB 203580), but not vehicle, in female rats with established endometriosis significantly attenuated ectopic growths-to-colon cross-sensitization and the increased activation of p38 MAPK in the RVM. These findings suggest that the noxious inputs from ectopic growths may activate p38 MAPK in the RVM via the DC, which may contribute to the development of ectopic growths-to-colon cross-sensitization in established endometriosis.

Pelvic organ cross-sensitization to enhance bladder and urethral pain behaviors in rats with experimental colitis

Neural cross-sensitization has been postulated as a mechanism underlying overlaps of chronic pelvic pain disorders such as bladder pain syndrome/interstitial cystitis (BPS/IC) and irritable bowel syndrome (IBS). Animals with experimental colitis have been used to study the underlying mechanisms for overlapped pelvic pain symptoms, and shown to exhibit bladder overactivity evidenced by frequent voiding; however, it has not directly been evaluated whether pain sensation derived from the lower urinary tract is enhanced in colitis models. Also, the cross-sensitization between the colon and urethra has not been studied previously. In the present study, we therefore investigated pain behaviors induced by nociceptive stimuli in the lower urinary tract and the involvement of C-fiber afferent pathways using rats with colitis induced by intracolonic application of 2,4,6-trinitrobenzenesulfonic acid (TNBS). In TNBS-induced colitis rats at 10days, intravesical application of resiniferatoxin (RTx) induced a significantly greater number of episodes of both licking and freezing behaviors, which were reduced by capsaicin-sensitive C-fiber afferent desensitization. Histochemical studies using fluorescent dye tracers injected into the colon, bladder or urethra showed that dichotomized afferent neurons comprised 6.9–14.5% of L1, L6 and S1 dorsal root ganglion (DRG) neurons innervating the colon or the lower urinary tract. Transient receptor potential vanilloid 1 (TRPV1) mRNA expression was significantly increased in, the bladder, urethra and S1 DRG in colitis rats. An increase in myeloperoxidase (MPO) activity was found in the colon, but not in the bladder or urethra after intracolonic TNBS treatment. These results indicate that TNBS-induced colitis increased pain sensitivity in the bladder and urethra via activation of C-fiber afferent pathways due to colon-to-bladder and colon-to-urethral cross-sensitization, suggesting the contribution of pelvic organ cross-sensitization mechanisms to overlapped pain symptoms in BPS/IC and IBS.

MP1-02 UNDERSTANDING THE MECHANISMS OF VISCERAL ORGAN CROSSTALK: IS IT ALL DUE TO ALTERED PERMEABILITY?

You have accessJournal of UrologyUrodynamics/Incontinence/Female Urology: Basic Research I1 Apr 2014MP1-02 UNDERSTANDING THE MECHANISMS OF VISCERAL ORGAN CROSSTALK: IS IT ALL DUE TO ALTERED PERMEABILITY? Ehsan Mohammadi, Karl Tyler, William Dakil, Samuel VanGordon, Beverley Greenwood-Van Meerveld, and Robert Hurst Ehsan MohammadiEhsan Mohammadi More articles by this author , Karl TylerKarl Tyler More articles by this author , William DakilWilliam Dakil More articles by this author , Samuel VanGordonSamuel VanGordon More articles by this author , Beverley Greenwood-Van MeerveldBeverley Greenwood-Van Meerveld More articles by this author , and Robert HurstRobert Hurst More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.100AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Although the pathophysiology of painful bladder syndrome (PBS) is poorly understood there is evidence of female predominance and comorbidity with irritable bowel syndrome (IBS). It is our hypothesis that altered bladder permeability leads to hyperexcitability of visceral afferent neurons and underlies pelvic organ cross sensitization. In this study we aimed to investigate the effect of acute bladder damage on the permeability of the bladder and colon. METHODS Experiments were performed in anesthetized, ovariectomized (OVX) female Sprague Dawley rats (n = 28); the bladder was catheterized for the intravesical administration of protamine sulfate (1mg/ml in 400 μl) saline-instilled and untreated naïve rats served as controls. After 24 hr. the bladder and colonic tissue were harvested. A sample was taken for histology and the remaining tissue was mounted into modified Ussing chambers and bathed in Kreb’s solution at 37°C. After a stabilization period, permeability was assessed electrophysiologically via transepithelial resistance (TEER) and via the flux of a macromolecular marker (fluorescein isothiocynate-dextrin [FITC-4 KD). RESULTS Other than mild edema, exposing the bladder to protamine sulfate induced very minimal physical urothelial damage but no colonic damage as defined histologically. We therefore conclude the main effect was to neutralize the protective glycosaminoglycan layer. However, there was a significant (P<0.01) decrease in TEER in protamine-sulfate treated bladders (1175 ± 164 ω/cm2) compared to saline-treated (1617 ± 202 1ω/cm2) or naïve controls (2524 ± 422 ω/cm2). We also found that in response to mild bladder damage, colonic TEER significantly (P<0.05) decreased (126.7 ± 22.44 ω/cm2) when compared to saline-treated (177.7 ± 14.23 ω/cm2) and untreated naïve controls (233.7 ± 14.14 ω/cm2). CONCLUSIONS These data demonstrate that following acute bladder damage there is not only an increase in bladder permeability but also a marked rise in the permeability of the colon in the absence of any histological damage to the colon. Thus changes in epithelial permeability may represent a novel mechanism for visceral organ crosstalk and may be important in the overlapping symptomology of PBS and IBS. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e1 Peer Review Report Advertisement Copyright & Permissions© 2014MetricsAuthor Information Ehsan Mohammadi More articles by this author Karl Tyler More articles by this author William Dakil More articles by this author Samuel VanGordon More articles by this author Beverley Greenwood-Van Meerveld More articles by this author Robert Hurst More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

1599 HIGHER EXPRESSION OF PDE5 IN THE ANTERIOR FIBROMUSCULAR STROMA OF THE HUMAN PROSTATE COMPARED WITH OTHER GLANDULAR ZONE

injection into the prostate of SD rats. After 1 week, L6-S1 dorsal root ganglia (DRG) were removed and whole cell patch-clamp recordings were performed on individual D-AN and B-AN, which were labeled by retrograde axonal transport of fluorescent dyes, Fast Blue (FB) or DiI, injected into the bladder wall or the prostate, respectively. Since the majority of C-fibers are sensitive to capsaicin, FB and/or DiI-labeled cells that exhibited inward currents in response to capsaicin application were selected for evaluation. The mRNA level of an A-type K channel (KA) subunit, Kv1.4 in D-AN and B-AN was evaluated by real-time RT-PCR using laser-capture microdissection methods. RESULTS: Capsaicin-sensitive D-AN or B-AN from prostatitis rats exhibited lower thresholds for spike activation (-28.3 1.4 mV or -28.7 1.4 mV) compared to control rats (-19.5 1.1 mV or -21.3 2.2 mV). The number of action potentials of D-AN or B-AN during a 800 msec depolarizing pulse was significantly increased after prostatitis (5.1 0.7 or 3.5 0.4 spikes) compared to control rats (1.2 0.1 or 1.4 0.3 spikes). In prostatitis rats, Kv1.4 mRNA was significantly decreased in D-AN and B-AN compared to non-labeled neurons. In B-AN, the peak density of KA currents during membrane depolarization to 0 mV in prostatitis rats (39.3 5.9 pA/pF) was significantly smaller than that from control rats (76.5 11.0 pA/pF). CONCLUSIONS: These results indicate that the excitability of capsaicin-sensitive C-fiber D-AN and B-AN is increased due to reduced KA activity associated with decreased expression of Kv1.4 -subunit following prostatic inflammation. Thus, pelvic organ cross-sensitization between prostate and bladder could be an important mechanism inducing storage LUTS in BPH patients with prostatic inflammation.

Differential effects of intravesical resiniferatoxin on excitability of bladder spinal neurons upon colon–bladder cross-sensitization

Cross-sensitization in the pelvis may contribute to etiology of functional pelvic pain disorders such as interstitial cystitis/bladder pain syndrome (IC/BPS). Increasing evidence suggests the involvement of transient receptor potential vanilloid 1 (TRPV1) receptors in the development of neurogenic inflammation in the pelvis and pelvic organ cross-sensitization. The objective of this study was to test the hypothesis that desensitization of TRPV1 receptors in the urinary bladder can minimize the effects of cross-sensitization induced by experimental colitis on excitability of bladder spinal neurons. Extracellular activity of bladder neurons was recorded in response to graded urinary bladder distension (UBD) in rats pretreated with intravesical resiniferatoxin (RTX, 10−7M). Colonic inflammation was induced by intracolonic instillation of 2,4,6-trinitrobenzene sulfonic acid (TNBS). The duration of excitatory responses to noxious UBD during acute colonic inflammation (3 days post-TNBS) was significantly shortened in the group with RTX pretreatment (25.3±1.5s, n=49) when compared to the control group (35.1±4.2s, n=43, p<0.05). The duration of long-lasting excitatory responses, but not short-lasting responses of bladder spinal neurons during acute colitis was significantly reduced by RTX from 52.9±6.6s (n=21, vehicle group) to 34.4±2.1s (RTX group, n=21, p<0.05). However, activation of TRPV1 receptors in the urinary bladder prior to acute colitis increased the number of bladder neurons receiving input from large somatic fields from 22.7% to 58.2% (p<0.01). The results of our study provide evidence that intravesical RTX reduces the effects of viscerovisceral cross-talk induced by colonic inflammation on bladder spinal neurons. However, RTX enhances the responses of bladder neurons to somatic stimulation, thereby limiting its therapeutic potential.

493 DEVELOPMENT OF A NEUROGENIC BLADDER IN TRANSIENT RECEPTOR POTENTIAL VANILLOID 1 KNOCKOUT MICE

INTRODUCTION AND OBJECTIVES: Bladder pain of unknown etiology has been associated with co-morbid conditions and functional abnormalities in adjacent pelvic organs. This phenomenon is called “crosssensitization” and occurs predominantly via convergent neural pathways connecting distinct pelvic organs. Our previous studies showed that colonic inflammation can cause detrusor instability via activation of transient receptor potential vanilloid 1 (TRPV1) signaling pathways. In this study, we aimed to determine whether cross-sensitization in the pelvis can develop in the absence of TRPV1 receptors and lead to a neurogenic bladder. METHODS: Four groups of adult male mice (N 25) were included in the study: 2 groups of C57BL/6 wild-type (WT) mice with and without acute colitis (induced by intracolonic trinitrobenzene sulfonic acid, TNBS) and 2 groups of TRPV1 knockout mice (TRPV1 / ) mice with and without acute colitis. Mice were sacrificed at day 3 after the induction of pelvic organ cross-sensitization by acute colitis and the function of the detrusor was evaluated in vitro using isolated detrusor smooth muscle (DSM) strips. The level of inflammation in the distal colon and urinary bladder was evaluated by the myeloperoxidase (MPO) assay. The contractility of DSM strips was studied in response to potassium chloride test, electric field stimulation and relaxation of DSM by Rho kinase inhibitor. RESULTS: In WT mice, acute colitis caused 2-fold up-regulation of MPO levels in the colon whereas in TRPV1 / mice an increase reached 1.5 fold (p 0.05 to respective control). MPO levels were unchanged in the bladders from both groups. The contractile response of DSM strips to electric stimulation was significantly increased after colitis in WT mice (85.97 12.27 g/g) when compared to control group (44.39 10.81 g/g, p 0.05). The same changes were observed in the TRPV1 / group with pelvic organ cross-sensitization. The use of Rho kinase inhibitor Y27632 induced DSM relaxation in WT group by 72.87 10.40% whereas it was only 39.38 6.46% in the TRPV / group (N 6, p 0.05 to WT). CONCLUSIONS: Our data provide evidence that the absence of TRPV1 receptors does not eliminate the occurence of cross-sensitization in the pelvis and TRPV / mice develop a neurogenic bladder. However, DSM from TRPV / mice showed decreased relaxation in response to a Rho kinase inhibitor suggesting alterations in DSM signaling pathways.

Colonic inflammation up‐regulates voltage‐gated sodium channels in bladder sensory neurons via activation of peripheral transient potential vanilloid 1 receptors

Primary sensory neurons express several types of ion channels including transient receptor potential vanilloid 1 (TRPV1) and voltage-gated Na(+) channels. Our previous studies showed an increased excitability of bladder primary sensory and spinal neurons triggered by inflammation in the distal colon as a result of pelvic organ cross-sensitization. The goal of this work was to determine the effects of TRPV1 receptor activation by potent agonists and/or colonic inflammation on voltage-gated Na(+) channels expressed in bladder sensory neurons. Sprague-Dawley rats were treated with intracolonic saline (control), resiniferatoxin (RTX, 10(-7 ) mol L(-1)), TNBS (colonic irritant) or double treatment (RTX followed by TNBS). TNBS-induced colitis increased the amplitude of total Na(+) current by two-fold and of tetrodotoxin resistant (TTX-R) Na(+) current by 78% (P ≤ 0.05 to control) in lumbosacral bladder neurons during acute phase (3 days post-TNBS). Instillation of RTX in the distal colon caused an enhancement in the amplitude of total Na(+) current at -20 mV from -112.1 ± 18.7 pA/pF (control) to -183.6 ± 27.8 pA/pF (3 days post-RTX, P ≤ 0.05) without changes in TTX resistant component. The amplitude of net Na(+) current was also increased by 119% at day 3 in the group with double treatment (RTX followed by TNBS, P ≤ 0.05 to control) which was significantly higher than in either group with a single treatment. These results provide evidence that colonic inflammation activates TRPV1 receptors at the peripheral sensory terminals leading to an up-regulation of voltage gated Na(+) channels on the cell soma of bladder sensory neurons. This mechanism may underlie the occurrence of peripheral cross-sensitization in the pelvis and functional chronic pelvic pain.

Acute colonic inflammation triggers detrusor instability via activation of TRPV1 receptors in a rat model of pelvic organ cross-sensitization.

Chronic pelvic pain of unknown etiology is a common clinical condition and may develop as a result of cross-sensitization in the pelvis when pathological changes in one of the pelvic organs result in functional alterations in an adjacent structure. The aim of the current study was to compare transient receptor potential vanilloid 1 (TRPV1) activated pathways on detrusor contractility in vivo and in vitro using a rat model of pelvic organ cross-sensitization. Four groups of male Sprague-Dawley rats (N = 56) were included in the study. Animals received intracolonic saline (control), resiniferatoxin (RTX, TRPV1 agonist, 10(-7) M), 2,4,6-trinitrobenzene sulfonic acid (TNBS, colonic irritant), or double treatment (RTX followed by TNBS). Detrusor muscle contractility was assessed under in vitro and in vivo conditions. Intracolonic RTX increased the contractility of the isolated detrusor in response to electric field stimulation (EFS) by twofold (P ≤ 0.001) and enhanced the contractile response of the bladder smooth muscle to carbachol (CCh). Acute colonic inflammation reduced detrusor contractility upon application of CCh in vitro, decreased bladder capacity by 28.1% (P ≤ 0.001), and reduced micturition volume by 60% (P ≤ 0.001). These changes were accompanied by an increased number of nonmicturition contractions from 3.7 ± 0.7 to 15 ± 2.7 (N = 6 in both groups, P ≤ 0.001 vs. control). Desensitization of intracolonic TRPV1 receptors before the induction of acute colitis restored the response of isolated detrusor strips to CCh but not to EFS stimulation. Cystometric parameters were significantly improved in animals with double treatment and approximated the control values. Our data suggest that acute colonic inflammation triggers the occurrence of detrusor instability via activation of TRPV1-related pathways. Comparison of the results obtained under in vitro vs. in vivo conditions provides evidence that intact neural pathways are critical for the development of an overactive bladder resulting from pelvic organ cross talk.

951 ANALYSIS OF TRANSIENT RECEPTOR POTENTIAL CHANNELS RELATED TO BLADDER OVERACTIVITY INDUECED BY PELVIC ORGAN CROSS-SENSITIZATION IN RATS

INTRODUCTION AND OBJECTIVES: Pelvic organ cross-sensitization has been proposed as one of the pathogenesis of bladder pain syndrome/interstitial cystitis. Thus, we examined changes in bladder function after the stimulation of transient receptor potential (TRP) channels in the colon, uterus or stomach because TRP channels are one of the main nociceptive receptors. METHODS: Under isoflurane anesthesia, a polyethylene catheter was implanted into the colon, uterus or stomach as well as the bladder in female Sprague-Dawley rats, and cystometry was then performed in an awake condition. 1) Capsaicin (TRPV1 activator; 1, 3, 10 & 30mM), R1747 (TRPV4 activator; 1, 3, 10 & 30mM), allyl isothiocyanate (AITC: TRPA1 activator; 1, 3, 10 & 30%) or menthol (TRPM8 activator; 3, 10, 30 & 100%) was cumulatively applied in a 50ul solution of each dose with 30min intervals into the colon, uterus or stomach. 2) Time-dependent changes in bladder function were examined after 30% AITC injection into the colon or uterus. We also examined changes in bladder function when ruthenium red (RR: TRPA1 inhibitor) was intrathecally (i.t.; 0.03ug, 5ul) or intravenously (i.v.; 3mg/kg, 0.5ml/ kg) applied 30min before or 120min after colon AITC injection. RESULTS: 1) There were no significant changes in bladder function after the TRPV1, V4 or M8 stimulation in the colon or uterus, whereas threshold pressure (TP) and intercontraction interval (ICI) were significantly decreased by 10% or greater AITC injection into the colon or 30% AITC injection into the uterus. None of TRP channel stimulations in the stomach influenced bladder function. 2) TP and ICI were significantly decreased from 30 min and 60 min after 30% AITC injection, respectively, in the colon. TP and ICI were significantly decreased 60 min after AITC injection in the uterus, and became stable after 120min. Bladder overactivity induced by colon AITC application was prevented by the pretreatment of RR (i.v. and i.t.). On the other hand, only the i.t., but not i.v., application of RR increased TP and ICI significantly when RR was applied after the induction of colon-toblabber cross-sensitization. CONCLUSIONS: Bladder overacitvity occurs from 30–60 min after the stimulation of TRPA1 channels, but not TRPV1, V4 or M8, in the colon or uterus, indicating the importance of TRPA1 for the pelvic organ cross-sensitization. In addition, central sensitization seems to be involved in the pelvic organ cross-sensitization because i.t. application of a TRPA1 inhibitor can attenuate the colon-to-bladder cross-sensitization.

Experimental colitis triggers the release of substance P and calcitonin gene-related peptide in the urinary bladder via TRPV1 signaling pathways

Clinical data provide evidence of high level of co-morbidity among genitourinary and gastrointestinal disorders characterized by chronic pelvic pain. The objective of this study was to test the hypothesis that colonic inflammation can impact the function of the urinary bladder via activation of TRPV1 signaling pathways followed by alterations in gene and protein expression of substance P (SP) and calcitonin gene-related peptide (CGRP) in sensory neurons and in the bladder. Inflammation was induced by intracolonic instillation of trinitrobenzene sulfonic acid (TNBS, 12.5 mg/kg), and desensitization of TRPV1 receptors was evoked by intracolonic resiniferatoxin (RTX, 10 − 7 M). mRNA and protein concentrations of CGRP and SP were measured at 3, 5 and 30 days. RTX instillation in the colon caused 3-fold up-regulation of SP mRNA in the urinary bladder at day 5 ( n = 7, p ≤ 0.05) followed by 35-fold increase at day 30 ( n = 5, p ≤ 0.05). Likewise, TNBS colitis triggered 15.8-fold up-regulation of SP mRNA 1 month after TNBS ( n = 5, p ≤ 0.05). Desensitization of colonic TRPV1 receptors prior to TNBS abolished SP increase in the urinary bladder. RTX led to 4.3-fold increase of CGRP mRNA at day 5 ( n = 7, p ≤ 0.05 to control) in the bladder followed by 28-fold increase at day 30 post-RTX ( n = 4, p ≤ 0.05). Colitis did not alter CGRP concentration during acute phase; however, at day 30 mRNA level was increased by 17.8 ± 6.9-fold ( n = 5, p ≤ 0.05) in parallel with 4-fold increase in CGRP protein ( n = 5, p ≤ 0.01) in the detrusor. Protein concentration of CGRP in the spinal cord was diminished by 45–65% ( p ≤ 0.05) during colitis. RTX pretreatment did not affect CGRP concentration in the urinary bladder; however, it caused a reduction in CGRP release from lumbosacral DRG neurons during acute phase (3 and 5 days post-TNBS). Our results clearly demonstrate that colonic inflammation triggers the release of pro-inflammatory neuropeptides SP and CGRP in the urinary bladder via activation of TRPV1 signaling mechanisms enunciating the neurogenic nature of pelvic organ cross-sensitization.

Sites of Pain From Interstitial Cystitis/Painful Bladder Syndrome

In interstitial cystitis/painful bladder syndrome multiple pain sites are common. We hypothesized that a careful and systematic description of the pain of interstitial cystitis/painful bladder syndrome might provide clues to its pathogenesis. Women with 12 months or greater of interstitial cystitis/painful bladder syndrome symptoms underwent a medical record review and interview. Each completed a questionnaire that included views of the female body and described up to 5 interstitial cystitis/painful bladder syndrome pains, noting 40 descriptors for each. Two-thirds of the 226 patients reported multiple pains. Pain could be consolidated at 4 sites, including suprapubic, urethral, genital and nongenitourinary. Most descriptors were similar and little evidence indicated that 1 pain influenced pain at another site. Another 3 patterns were evident, including 1) a suprapubic > urethral > genital > nongenitourinary ranking in site distribution and at each site proportions that were solitary, the worst and the most frequent pains, and pains that responded to bladder events, 2) site specific allodynia, and 3) for urethral and genital pains a wider spectrum of sensations, including burning, stinging and sharp. Patients with urethral (38%) or genital (27%) pain did not differ from those without such pain in 95% of 44 important characteristics. Suprapubic prominence and changes in the voiding cycle are features consistent with but do not prove that the bladder is the pain generator in interstitial cystitis/painful bladder syndrome and the pain sites described by patients are referred from it. The patients with interstitial cystitis/painful bladder syndrome who might have been diagnosed with vulvodynia or urethral syndrome did not differ from others in important patient variables.

Convergence of bladder and colon sensory innervation occurs at the primary afferent level

Dichotomizing afferents are individual dorsal root ganglion (DRG) neurons that innervate two distinct structures thereby providing a form of afferent convergence that may be involved in pelvic organ cross-sensitization. To determine the distribution of dichotomizing afferents supplying the distal colon and bladder of the Sprague–Dawley rat and the C57Bl/6 mouse, we performed concurrent retrograde labeling of urinary bladder and distal colon afferents using cholera toxin subunit B (CTB) fluorescent conjugates. Animals were perfused 4–5 days after sub-serosal organ injections, and the T10-S2 DRG were removed, sectioned, and analyzed using confocal microscopy. In the rat, CTB-positive afferents retrogradely labeled from the bladder were nearly three times more numerous than those labeled from the distal colon, while in the mouse, each organ was equally represented. In both species, the majority of colon and bladder afferents projected from lumbosacral (LS) ganglia and secondarily from thoracolumbar (TL) ganglia. In the rat, 17% of the total CTB-positive neurons were retrogradely labeled from both organs with 11% localized in TL, 6% in LS, and 0.8% in thoracic (TH) ganglia. In the mouse, 21% of the total CTB-positive neurons were dually-labeled with 12% localized in LS, 4% in TH, and 4% in TL ganglia. These findings support the existence of dichotomizing pelvic afferents, which provide a pre-existing neuronal substrate for possible immediate and maintained pelvic organ cross-sensitization and ultimately may play a role in the overlap of pelvic pain disorders.

Hyperexcitability of convergent colon and bladder dorsal root ganglion neurons after colonic inflammation: mechanism for pelvic organ cross‐talk

Clinical studies reveal concomitant occurrence of several gastrointestinal and urologic disorders, including irritable bowel syndrome and interstitial cystitis. The purpose of this study was to determine the mechanisms underlying cross-organ sensitization at the level of dorsal root ganglion (DRG) after acute and subsided gastrointestinal inflammation. DiI (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate) and Fast Blue were injected into the distal colon and urinary bladder of male rats, respectively. Convergent DRG neurons were found in L1-L3 and L6-S2 ganglia with an average distribution of 14% +/- 2%. The resting membrane potential (RMP) of cells isolated from upper lumbar (UL) ganglia was -59.8 +/- 2.7 mV, whereas lumbosacral (LS) neurons were more depolarized (RMP = -49.4 +/- 2.1 mV, P < or = 0.05) under control conditions. Acute trinitrobenzene sulfonic acid (TNBS) colitis (3 days) decreased voltage and current thresholds for action potential firing in LS but not UL convergent capsaicin-sensitive neurons. This effect persisted for 30 days in the absence of overt colonic inflammation. The current threshold for action potential (AP) firing in UL cells was also decreased from 165.0 +/- 24.5 pA (control) to 85.0 +/- 19.1 pA at 30 days (P < or = 0.05), indicating increased excitability. The presence of a subpopulation of colon-bladder convergent DRG neurons and their persistent hyperexcitability after colonic inflammation provides a basis for pelvic organ cross-sensitization.

Colonic irritation in the rat sensitizes urinary bladder afferents to mechanical and chemical stimuli: an afferent origin of pelvic organ cross-sensitization

Chronic pelvic pain (CPP) disorders frequently overlap. We have demonstrated that acute and chronic colonic irritation can lead to neurogenic cystitis. We hypothesize that acute colonic irritation can sensitize urinary bladder afferents to mechanical and chemical stimuli. Single-unit afferent activity was recorded from fine filaments of the pelvic nerve in urethane-anesthetized Sprague-Dawley female rats before and 1 h after intracolonic administration of trinitrobenzenesulfonic acid (TNBS). Only spontaneously active afferents with receptive fields in the bladder and conduction velocities <2.5 m/s (unmyelinated C-fibers) were studied. Mechanical sensitivity was tested by bladder distension (BD) during saline infusion, whereas chemical sensitivity was tested with intravesical capsaicin, bradykinin, or substance P. Colonic irritation increased the resting firing rate of bladder afferents twofold (1.0 +/- 0.2 vs. 0.49 +/- 0.2 impulses/s, P < 0.05). Moreover, at low-pressure BDs (10-20 mmHg), a greater percentage of afferents exhibited increased activity following TNBS (73 vs. 27%, P < 0.05). Although the magnitude of the afferent response to BD was unchanged at low pressures, the response was greatly enhanced at pressures 30 mmHg and above (2.36 +/- 0.56 vs. 8.55 +/- 0.73 impulses/s, P < 0.05). Responses to capsaicin, bradykinin, and substance P were also significantly enhanced following TNBS, and all responses were blocked by bladder denervation. In rats, colonic irritation sensitizes urinary bladder afferents to noxious mechanical and chemical stimuli. Interruption of the neural input to the bladder minimized this effect, suggesting a local afferent pathway from the colon. Thus, the overlap of CPP disorders may be a consequence of pelvic afferent cross-sensitization.

A Model of Neural Cross-Talk and Irritation in the Pelvis: Implications for the Overlap of Chronic Pelvic Pain Disorders

Irritable bowel syndrome, interstitial cystitis, and other chronic pelvic pain (CPP) disorders often occur concomitantly. Neural cross-talk may play a role in the overlap of CPP disorders via the convergence of pelvic afferents. We investigated the hypothesis that afferent irritation of one pelvic organ may adversely influence and sensitize another via neural interactions. We measured pelvic organ smooth muscle and striated muscle reflexes during micturition and colorectal distention (CRD) in urethane-anesthetized rats. The effects of acute cystitis on distal colonic sensory thresholds to CRD and the effects of acute colonic irritation on micturition parameters were assessed. External urethral sphincter (EUS) electromyography (EMG) was typical for the rat, with phasic firing during micturition. External anal sphincter EMG also showed phasic firing during micturition in synchrony with EUS activity but, in addition, showed both tonic bursts and phasic firing independent of EUS activity. Before bladder irritation, graded CRDs to 40 cm H2O produced no notable changes in abdominal wall EMG activity. Following acute bladder irritation, dramatic increases in abdominal wall EMG activity in response to CRD were observed at much lower distention pressures, indicating colonic afferent sensitization. Analogously, following acute colonic irritation, bladder contraction frequency increased 66%, suggesting sensitization of lower urinary tract afferents. We report compelling evidence of bidirectional cross-sensitization of the colon and lower urinary tract in a novel experimental model. This cross-sensitization may account for the substantial overlap of CPP disorders; however, further studies are needed to fully characterize these pathways.