Urinary bladder function and somatic sensitivity in vasoactive intestinal polypeptide (VIP)-/- mice

Bisphenol A affects vipergic nervous structures in the porcine urinary bladder trigone

Bisphenol A (BPA) is used in the production of plastics approved for contact with feed and food. Upon entering living organisms, BPA, as a potent endocrine disruptor, negatively affects various internal organs and regulatory systems, especially in young individuals. Although previous studies have described the neurotoxic effects of BPA on various tissues, it should be underlined that the putative influence of this substance on the chemical architecture of the urinary bladder intrinsic innervation has not yet been studied. One of the most important neuronal substances involved in the regulation of urinary bladder functions is vasoactive intestinal polypeptide (VIP), which primarily participates in the regulation of muscular activity and blood flow. Therefore, this study aimed to determine the influence of various doses of BPA on the distribution pattern of VIP-positive neural structures located in the wall of the porcine urinary bladder trigone using the double-immunofluorescence method. The obtained results show that BPA influence leads to an increase in the number of both neurons and nerve fibres containing VIP in the porcine urinary bladder trigone. This may indicate that VIP participates in adaptive processes of the urinary bladder evoked by BPA.

c-Jun/p38MAPK/ASIC3 pathways specifically activated by nerve growth factor through TrkA are crucial for mechanical allodynia development

Mechanical allodynia is a cardinal sign of several inflammatory pain disorders where nerve growth factor, a prototypic neurotrophin, plays a crucial role by binding to TrkA receptors. Here, we took the advantage of our generated knock-in mouse model expressing a chimeric TrkA/TrkC receptor that seems to not specifically develop mechanical allodynia after inflammation, to identify the TrkA downstream pathways involved in this phenomenon. We confirmed and extended that disrupting TrkA-specific pathways leads to a specific deficit in mechanical hypersensitivity development after somatic (systemic nerve growth factor administration and paw incision) and, to a lesser extent, visceral injuries. Despite a deficit in thin, mainly peptidergic, fibre innervation in TrkAC mice, thermal hyperalgesia development was not different from WT mice. Inflammatory reaction (oedema, IL-6 content), pain behaviours after intraplantar capsaicin, as well as TRPV1 calcium imaging response of dorsal root ganglion neurons were similar between TrkAC and WT mice. This deficiency in mechanical allodynia development in TrkAC mice is likely due to the alteration of the expression of different TrkA transduction pathways (ie, Akt, p38 MAPK, and c-Jun) especially p38 MAPK, in the dorsal root ganglion cell bodies, ultimately leading to an alteration of at least, ASIC3 channel overexpression, known to participate in nociceptor mechanosensory function.

Animal Model for Lower Urinary Tract Dysfunction in Parkinson's Disease

Although Parkinson's disease (PD) is characterized by the loss of dopaminergic neurons in the substantia nigra and subsequent motor symptoms, various non-motor symptoms often precede these other symptoms. While motor symptoms are certainly burdensome, a wide range of non-motor symptoms have emerged as the key determinant of the quality of life in PD patients. The prevalence of lower urinary tract symptoms differs according to the study, with ranges between 27% and 63.9%. These can be influenced by the stage of disease, the presence of lower urinary tract-related comorbidities, and parallels with other manifestations of autonomic dysfunction. Animal models can provide a platform for investigating the mechanisms of PD-related dysfunction and for the assessment of novel treatment strategies. Animal research efforts have been primarily focused on PD motor signs and symptoms. However, the etiology of lower urinary tract dysfunction in PD has yet to be definitively clarified. Several animal PD models are available, each of which has a different effect on the autonomic nervous system. In this article, we review the various lower urinary tract dysfunction animal PD models. We additionally discuss techniques for determining the appropriate model for evaluating the development of lower urinary tract dysfunction treatments.

Intrabladder PAC1 Receptor Antagonist, PACAP(6-38), Reduces Urinary Bladder Frequency and Pelvic Sensitivity in Mice Exposed to Repeated Variate Stress (RVS)

Stress causes symptom exacerbation in functional disorders of the urinary bladder. However, the potential mediators and underlying mechanisms of stress effects on micturition reflex function are unknown. We have characterized PACAP (Adcyap1) and PAC1 receptor (Adcyap1r1) signaling in stress-induced urinary bladder dysfunction in mice. We determined PACAP and PAC1 transcripts and protein expressions in the urinary bladder and lumbosacral dorsal root ganglia (DRG) and spinal cord in repeated variate stress (RVS) or control mouse (handling only) groups. RVS in mice significantly (p ≤ 0.01) increased serum corticosterone and urinary bladder NGF content and decreased weight gain. PACAP and PAC1 mRNA and protein were differentially regulated in lower urinary tract tissues with changes observed in lumbosacral DRG and spinal cord but not in urinary bladder. RVS exposure in mice significantly (p ≤ 0.01) increased (2.5-fold) voiding frequency as determined using conscious cystometry. Intrabladder administration of the PAC1 receptor antagonist, PACAP(6-38) (300 nM), significantly (p ≤ 0.01) increased infused volume (1.5-2.7-fold) to elicit a micturition event and increased the intercontraction interval (i.e., decreased voiding frequency) in mice exposed to RVS and in control mice, but changes were smaller in magnitude in control mice. We also evaluated the effect of PAC1 blockade at the level of the urinary bladder on pelvic sensitivity in RVS or control mouse groups using von Frey filament testing. Intrabladder administration of PACAP(6-38) (300 nM) significantly (p ≤ 0.01) reduced pelvic sensitivity following RVS. PACAP/receptor signaling in the CNS and PNS contributes to increased voiding frequency and pelvic sensitivity following RVS and may represent a potential target for therapeutic intervention.

TRPV4 blockade reduces voiding frequency, ATP release, and pelvic sensitivity in mice with chronic urothelial overexpression of NGF

Transient receptor potential vanilloid family member 4 (TRPV4) transcript and protein expression increased in the urinary bladder and lumbosacral dorsal root ganglia of transgenic mice with chronic urothelial overexpression of nerve growth factor (NGF-OE). We evaluated the functional role of TRPV4 in bladder function with open-outlet cystometry, void spot assays, and natural voiding (Urovoid) assays with the TRPV4 antagonist HC-067047 (1 μM) or vehicle in NGF-OE and littermate wild-type (WT) mice. Blockade of TRPV4 at the level of the urinary bladder significantly (P ≤ 0.01) increased the intercontraction interval (2.2-fold) and void volume (2.6-fold) and decreased nonvoiding contractions (3.0-fold) in NGF-OE mice, with lesser effects (1.3-fold increase in the intercontraction interval and 1.3-fold increase in the void volume) in WT mice. Similar effects of TRPV4 blockade on bladder function in NGF-OE mice were demonstrated with natural voiding assays. Intravesical administration of HC-067047 (1 µM) significantly (P ≤ 0.01) reduced pelvic sensitivity in NGF-OE mice but was without effect in littermate WT mice. Blockade of urinary bladder TRPV4 or intravesical infusion of brefeldin A significantly (P ≤ 0.01) reduced (2-fold) luminal ATP release from the urinary bladder in NGF-OE and littermate WT mice. The results of the present study suggest that TRPV4 contributes to luminal ATP release from the urinary bladder and increased voiding frequency and pelvic sensitivity in NGF-OE mice.

FTY720 Improves Behavior, Increases Brain Derived Neurotrophic Factor Levels and Reduces α-Synuclein Pathology in Parkinsonian GM2+/- Mice

Parkinson's disease (PD) is a progressive aging disorder that affects millions worldwide, thus, disease-modifying-therapies are urgently needed. PD pathology includes α-synuclein (aSyn) accumulation as synucleinopathy. Loss of GM1 gangliosides occurs in PD brain, which is modeled in GM2 synthase transgenic mice. GM2+/- mice have low, not absent GM1 and develop age-onset motor deficits, making them an excellent PD drug testing model. FTY720 (fingolimod) reduces synucleinopathy in A53T aSyn mice and motor dysfunction in 6-OHDA and rotenone PD models, but no one has tested FTY720 in mice that develop age-onset PD-like motor problems. We confirmed that GM2+/-mice had equivalent rotarod, hindlimb reflexes, and adhesive removal functions at 9 mo. From 11 mo, GM2+/- mice received oral FTY720 or vehicle 3x/week to 16 mo. As bladder problems occur in PD, we also assessed GM2+/- bladder function. This allowed us to demonstrate improved motor and bladder function in GM2+/- mice treated with FTY720. By immunoblot, FTY720 reduced levels of proNGF, a biomarker of bladder dysfunction. In humans with PD, arm swing becomes abnormal, and brachial plexus modulates arm swing. Ultrastructure of brachial plexus in wild type and GM2 transgenic mice confirmed abnormal myelination and axons in GM2 transgenics. FTY720 treated GM2+/- brachial plexus sustained myelin associated protein levels and reduced aggregated aSyn and PSer129 aSyn levels. FTY720 increases brain derived neurotrophic factor (BDNF) and we noted increased BDNF in GM2+/- brachial plexus and cerebellum, which contribute to rotarod performance. These findings provide further support for testing low dose FTY720 in patients with PD.

Parkinsonian GM2 synthase knockout mice lacking mature gangliosides develop urinary dysfunction and neurogenic bladder

Parkinson's disease is a neurodegenerative disorder that reduces a patients' quality of life by the relentless progression of motor and non-motor symptoms. Among the non-motor symptoms is a condition called neurogenic bladder that is associated with detrusor muscle underactivity or overactivity occurring from neurologic damage. In Parkinson's disease, Lewy-body-like protein aggregation inside neurons typically contributes to pathology. This is associated with dopaminergic neuron loss in substantia nigra pars compacta (SNc) and in ventral tegmental area (VTA), both of which play a role in micturition. GM1 gangliosides are mature glycosphingolipids that enhance normal myelination and are reduced in Parkinson's brain. To explore the role of mature gangliosides in vivo, we obtained GM2 Synthase knockout (KO) mice, which develop parkinsonian pathology including a loss of SNc dopaminergic neurons, which we reconfirmed. However, bladder function and innervation have never been assessed in this model. We compared GM2 Synthase KO and wild type (WT) littermates' urination patterns from 9 to 19 months of age by counting small and large void spots produced during 1 h tests. Because male and female mice had different patterns, we evaluated data by sex and genotype. Small void spots were significantly increased in 12-16 month GM2 Synthase KO females, consistent with overactive bladder. Similarly, at 9-12 month GM2 KO males tended to have more small void spots than WT males. As GM2 Synthase KO mice aged, both females and males had fewer small and large void spots, consistent with detrusor muscle underactivity. Ultrasounds confirmed bladder enlargement in GM2 Synthase KO mice compared to WT mice. Tyrosine hydroxylase (TH) immunohistochemistry revealed significant dopaminergic loss in GM2 Synthase KO VTA and SNc, and a trend toward TH loss in the GM2 KO periaqueductal gray (PAG) micturition centers. Levels of the nerve growth factor precursor, proNGF, were significantly increased in GM2 Synthase KO bladders and transmission electron micrographs showed atypical myelination of pelvic ganglion innervation in GM2 Synthase KO bladders. Cumulatively, our findings provide the first evidence that mature ganglioside loss affects micturition center TH neurons as well as proNGF dysregulation and abnormal innervation of the bladder. Thus, identifying therapies that will counteract these effects should be beneficial for those suffering from Parkinson's disease and related disorders.

PACAP/PAC1 Expression and Function in Micturition Pathways

Neural injury, inflammation, or diseases commonly and adversely affect micturition reflex function that is organized by neural circuits in the CNS and PNS. One neuropeptide receptor system, pituitary adenylate cyclase-activating polypeptide (PACAP; Adcyap1), and its cognate receptor, PAC1 (Adcyap1r1), have tissue-specific distributions in the lower urinary tract. PACAP and associated receptors are expressed in the LUT and exhibit changes in expression, distribution, and function in preclinical animal models of bladder pain syndrome (BPS)/interstitial cystitis (IC), a chronic, visceral pain syndrome characterized by pain, and LUT dysfunction. Blockade of the PACAP/PAC1 receptor system reduces voiding frequency and somatic (e.g., hindpaw, pelvic) sensitivity in preclinical animal models and a transgenic mouse model that mirrors some clinical symptoms of BPS/IC. The PACAP/receptor system in micturition pathways may represent a potential target for therapeutic intervention to reduce LUT dysfunction following urinary bladder inflammation.

Immunomodulatory Roles of PACAP and VIP: Lessons from Knockout Mice

A bidirectional cross-talk is established between the nervous and immune systems through common mediators including neuropeptides, neurotransmitters, and cytokines. Among these, PACAP and VIP are two highly related neuropeptides widely distributed in the organism with purported immunomodulatory actions. Due to their well-known anti-inflammatory properties, administration of these peptides has proven to be beneficial in models of acute and chronic inflammatory diseases. Nevertheless, the relevance of the endogenous source of these peptides in the modulation of immune responses remains to be elucidated. The development of transgenic mice with specific deletions in the genes coding for these neuropeptides (Vip and Adcyap1) or for their G-protein-coupled receptors VPAC1, VPAC2, and PAC1 (Vipr1, Vipr2, Adcyap1r1) has allowed to address this question, underscoring the complexity of the immunoregulatory properties of PACAP and VIP. The goal of this review is to integrate the existing information on the immune phenotypes of mice deficient for PACAP, VIP, or their receptors, to provide a global view on the roles of these endogenous neuropeptides during immunological health and disease.

PACAP38-Mediated Bladder Afferent Nerve Activity Hyperexcitability and Ca2+ Activity in Urothelial Cells from Mice

Pituitary adenylate cyclase-activating polypeptide (PACAP; Adcyap1) and its cognate PAC1 receptor (Adcyap1r1) have tissue-specific distributions in the lower urinary tract (LUT). The afferent limb of the micturition reflex is often compromised following bladder injury, disease, and inflammatory conditions. We have previously demonstrated that PACAP signaling contributes to increased voiding frequency and decreased bladder capacity with cystitis. Thus, the present studies investigated the sensory components (e.g., urothelial cells, bladder afferent nerves) of the urinary bladder that may underlie the pathophysiology of aberrant PACAP activation. We utilized bladder-pelvic nerve preparations and urothelial sheet preparations to characterize PACAP-induced bladder afferent nerve discharge with distention and PACAP-induced Ca²⁺ activity, respectively. We determined that PACAP38 (100 nM) significantly (p ≤ 0.01) increased bladder afferent nerve activity with distention that was blocked with a PAC1/VPAC2 receptor antagonist PACAP6-38 (300 nM). PACAP38 (100 nM) also increased Ca²⁺ activity in urothelial cells over that observed in control preparations. Taken together, these results establish a role for PACAP signaling in bladder sensory components (e.g., urothelial cells, bladder afferent nerves) that may ultimately facilitate increased voiding frequency.

Expression and Function of Chemokines CXCL9-11 in Micturition Pathways in Cyclophosphamide (CYP)-Induced Cystitis and Somatic Sensitivity in Mice

Changes in urinary bladder function and somatic sensation may be mediated, in part, by inflammatory changes in the urinary bladder including the expression of chemokines. Male and female C57BL/6 mice were treated with cyclophosphamide (CYP; 75 mg/kg, 200 mg/kg, i.p.) to induce bladder inflammation (4 h, 48 h, chronic). We characterized the expression of CXC chemokines (CXCL9, CXCL10 and CXCL11) in the urinary bladder and determined the effects of blockade of their common receptor, CXCR3, at the level urinary bladder on bladder function and somatic (hindpaw and pelvic) sensation. qRT-PCR and Enzyme-Linked Immunoassays (ELISAs) were used to determine mRNA and protein expression of CXCL9, CXCL10 and CXCL11 in urothelium and detrusor. In urothelium of female mice treated with CYP, CXCL9 and CXCL10 mRNA significantly (p ≤ 0.01) increased with CYP treatment whereas CXC mRNA expression in the detrusor exhibited both increases and decreases in expression with CYP treatment. CXC mRNA expression urothelium and detrusor of male mice was more variable with both significant (p ≤ 0.01) increases and decreases in expression depending on the specific CXC chemokine and CYP treatment. CXCL9 and CXCL10 protein expression was significantly (p ≤ 0.01) increased in the urinary bladder with 4 h CYP treatment in female mice whereas CXC protein expression in the urinary bladder of male mice did not exhibit an overall change in expression. CXCR3 blockade with intravesical instillation of AMG487 (5 mg/kg) significantly (p ≤ 0.01) increased bladder capacity, reduced voiding frequency and reduced non-voiding contractions in female mice treated with CYP (4 h, 48 h). CXCR3 blockade also reduced (p ≤ 0.01) hindpaw and pelvic sensitivity in female mice treated with CYP (4 h, 48 h). CXC chemokines may be novel targets for treating urinary bladder dysfunction and somatic sensitization resulting from urinary bladder inflammation.

PACAP/Receptor System in Urinary Bladder Dysfunction and Pelvic Pain Following Urinary Bladder Inflammation or Stress

Complex organization of CNS and PNS pathways is necessary for the coordinated and reciprocal functions of the urinary bladder, urethra and urethral sphincters. Injury, inflammation, psychogenic stress or diseases that affect these nerve pathways and target organs can produce lower urinary tract (LUT) dysfunction. Numerous neuropeptide/receptor systems are expressed in the neural pathways of the LUT and non-neural components of the LUT (e.g., urothelium) also express peptides. One such neuropeptide receptor system, pituitary adenylate cyclase-activating polypeptide (PACAP; Adcyap1) and its cognate receptor, PAC1 (Adcyap1r1), have tissue-specific distributions in the LUT. Mice with a genetic deletion of PACAP exhibit bladder dysfunction and altered somatic sensation. PACAP and associated receptors are expressed in the LUT and exhibit neuroplastic changes with neural injury, inflammation, and diseases of the LUT as well as psychogenic stress. Blockade of the PACAP/PAC1 receptor system reduces voiding frequency in preclinical animal models and transgenic mouse models that mirror some clinical symptoms of bladder dysfunction. A change in the balance of the expression and resulting function of the PACAP/receptor system in CNS and PNS bladder reflex pathways may underlie LUT dysfunction including symptoms of urinary urgency, increased voiding frequency, and visceral pain. The PACAP/receptor system in micturition pathways may represent a potential target for therapeutic intervention to reduce LUT dysfunction.

Urothelial Tight Junction Barrier Dysfunction Sensitizes Bladder Afferents

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic voiding disorder that presents with pain in the urinary bladder and surrounding pelvic region. A growing body of evidence suggests that an increase in the permeability of the urothelium, the epithelial barrier that lines the interior of the bladder, contributes to the symptoms of IC/BPS. To examine the consequence of increased urothelial permeability on pelvic pain and afferent excitability, we overexpressed in the urothelium claudin 2 (Cldn2), a tight junction (TJ)-associated protein whose message is significantly upregulated in biopsies of IC/BPS patients. Consistent with the presence of bladder-derived pain, rats overexpressing Cldn2 showed hypersensitivity to von Frey filaments applied to the pelvic region. Overexpression of Cldn2 increased the expression of c-Fos and promoted the activation of ERK1/2 in spinal cord segments receiving bladder input, which we conceive is the result of noxious stimulation of afferent pathways. To determine whether the mechanical allodynia observed in rats with reduced urothelial barrier function results from altered afferent activity, we examined the firing of acutely isolated bladder sensory neurons. In patch-clamp recordings, about 30% of the bladder sensory neurons from rats transduced with Cldn2, but not controls transduced with GFP, displayed spontaneous activity. Furthermore, bladder sensory neurons with tetrodotoxin-sensitive (TTX-S) action potentials from rats transduced with Cldn2 showed hyperexcitability in response to suprathreshold electrical stimulation. These findings suggest that as a result of a leaky urothelium, the diffusion of urinary solutes through the urothelial barrier sensitizes bladders afferents, promoting voiding at low filling volumes and pain.

Spinal astrocytic activation contributes to mechanical allodynia in a rat model of cyclophosphamide-induced cystitis

BACKGROUND

Previous studies have demonstrated that glial cells play an important role in the generation and maintenance of neuropathic pain. Activated glial cells produce numerous mediators such as proinflammatory cytokines that facilitate neuronal activity and synaptic plasticity. Similarly, bladder pain syndrome/interstitial cystitis shares many characteristics of neuropathic pain. However, related report on the involvement of spinal glia in bladder pain syndrome/interstitial cystitis-associated pathological pain and the underlying mechanisms are still lacking. The present study investigated spinal glial activation and underlying molecular mechanisms in a rat model of bladder pain syndrome/interstitial cystitis.

RESULTS

A rat model of bladder pain syndrome/interstitial cystitis was established via systemic injection with cyclophosphamide. Mechanical allodynia was tested with von Frey monofilaments and up-down method. Moreover, Western blots and double immunofluorescence were used to detect the expression and location of glial fibrillary acidic protein, OX42/Iba1, P-P38, NeuN, interleukin (IL)-1β, phosphorylation of N-methyl-D-aspartate receptor 1 (P-NR1), and IL-1 receptor I (IL-1RI) in the L6-S1 spinal cord. We found that glial fibrillary acidic protein rather than OX42/Iba1 or P-P38 was significantly increased in the spinal cord of cyclophosphamide-induced cystitis. L-alpha-aminoadipate but not minocycline markedly attenuated the allodynia. Furthermore, we found that spinal IL-1β was dramatically increased in cyclophosphamide-induced cystitis, and activated astrocytes were the only source of IL-1β release, which contributed to allodynia in cystitis rats. Besides, spinal P-NR1 was statistically increased in cyclophosphamide-induced cystitis and only localized in IL-1RI positive neurons in spinal dorsal horn. Additionally, NR antagonist significantly attenuated the cystitis-induced pain. Interestingly, the time course of the P-NR1 expression paralleled to that of IL-1β or glial fibrillary acidic protein.

CONCLUSIONS

Our results demonstrated that astrocytic activation but not microglial activation contributed to the allodynia in cyclophosphamide-induced cystitis and IL-1β released from astrocytes might bind to its endogenous receptor on the neurons inducing the phosphorylation of NR1 subunit, leading to sensory neuronal hyperexcitability and pathological pain.

Accelerated onset of the vesicovesical reflex in postnatal NGF-OE mice and the role of neuropeptides

The mechanisms underlying the postnatal maturation of micturition from a somatovesical to a vesicovesical reflex are not known but may involve neuropeptides in the lower urinary tract. A transgenic mouse model with chronic urothelial overexpression (OE) of NGF exhibited increased voiding frequency, increased number of non-voiding contractions, altered morphology and hyperinnervation of the urinary bladder by peptidergic (e.g., Sub P and CGRP) nerve fibers in the adult. In early postnatal and adult NGF-OE mice we have now examined: (1) micturition onset using filter paper void assays and open-outlet, continuous fill, conscious cystometry; (2) innervation and neurochemical coding of the suburothelial plexus of the urinary bladder using immunohistochemistry and semi-quantitative image analyses; (3) neuropeptide protein and transcript expression in urinary bladder of postnatal and adult NGF-OE mice using Q-PCR and ELISAs and (4) the effects of intravesical instillation of a neurokinin (NK)-1 receptor antagonist on bladder function in postnatal and adult NGF-OE mice using conscious cystometry. Postnatal NGF-OE mice exhibit age-dependent (R²=0.996-0.998; p≤0.01) increases in Sub and CGRP expression in the urothelium and significantly (p≤0.01) increased peptidergic hyperinnervation of the suburothelial nerve plexus. By as early as P7, NGF-OE mice exhibit a vesicovesical reflex in response to intravesical instillation of saline whereas littermate WT mice require perigenital stimulation to elicit a micturition reflex until P13 when vesicovesical reflexes are first observed. Intravesical instillation of a NK-1 receptor antagonist, netupitant (0.1μg/ml), significantly (p≤0.01) increased void volume and the interval between micturition events with no effects on bladder pressure (baseline, threshold, peak) in postnatal NGF-OE mice; effects on WT mice were few. NGF-induced pleiotropic effects on neuropeptide (e.g., Sub P) expression in the urinary bladder contribute to the maturation of the micturition reflex and are excitatory to the micturition reflex in postnatal NGF-OE mice. These studies provide insight into the mechanisms that contribute to the postnatal development of the micturition reflex.

Effects of CYP-Induced Cystitis on Growth Factors and Associated Receptor Expression in Micturition Pathways in Mice with Chronic Overexpression of NGF in Urothelium

We have determined if cyclophosphamide (CYP)-induced cystitis produces additional changes in growth factor/receptors expression in the urinary bladder (urothelium, detrusor) and lumbosacral (L6-S1) dorsal root ganglia (DRG) in a transgenic mouse model with chronic urothelial overexpression of NGF (NGF-OE). Functionally, NGF-OE mice treated with CYP exhibit significant increases in voiding frequency above that observed in control NGF-OE mice (no CYP). Quantitative PCR was used to determine NGF, BDNF, VEGF, and receptors (TrkA, TrkB, p75(NTR)) transcripts expression in tissues from NGF-OE and wild-type (WT) mice with CYP-induced cystitis of varying duration (4 h, 48 h, 8 days). In urothelium of control NGF-OE mice, NGF mRNA was significantly (p ≤ 0.001) increased. Urothelial expression of NGF mRNA in NGF-OE mice treated with CYP (4 h, 48 h, 8 days) was not further increased but maintained with all durations of CYP treatment evaluated. In contrast, CYP-induced cystitis (4 h, 48 h, 8 days) in NGF-OE mice demonstrated significant (p ≤ 0.05) regulation in BDNF, VEGF, TrkA, TrkB, and P75(NTR) mRNA in urothelium and detrusor smooth muscle. Similarly, CYP-induced cystitis (4 h, 48 h, 8 days) in NGF-OE mice resulted in significant (p ≤ 0.05), differential changes in transcript expression for NGF, BDNF, and receptors (TrkA, TrkB, p75(NTR)) in S1 DRG that was dependent on the duration-of CYP-induced cystitis. In general, NGF, BDNF, TrkA, and TrkB protein content in the urinary bladder increased in WT and NGF-OE mice with CYP-induced cystitis (4 h). Changes in NGF, TrkA and TrkB expression in the urinary bladder were significantly (p ≤ 0.05) greater in NGF-OE mice with CYP-induced cystitis (4 h) compared to WT mice with cystitis (4 h). However, the magnitude of change between WT and NGF-OE mice was only significantly (p ≤ 0.05) different for TrkB expression in urinary bladder of NGF-OE mice treated with CYP. These studies are consistent with target-derived NGF and other inflammatory mediators affecting neurochemical plasticity with potential contributions to reflex function of micturition pathways.

Intravesical PAC1 Receptor Antagonist, PACAP(6-38), Reduces Urinary Bladder Frequency and Pelvic Sensitivity in NGF-OE Mice

Chronic NGF overexpression (OE) in the urothelium, achieved through the use of a highly urothelium-specific uroplakin II promoter, stimulates neuronal sprouting in the urinary bladder, produces increased voiding frequency and non-voiding contractions, and referred somatic sensitivity. Additional NGF-mediated pleiotropic changes might contribute to increased voiding frequency and pelvic hypersensitivity in NGF-OE mice such as neuropeptide/receptor systems including PACAP(Adcyap1) and PAC1 receptor (Adcyap1r1). Given the presence of PAC1-immunoreactive fibers and the expression of PAC1 receptor expression in bladder tissues, and PACAP-facilitated detrusor contraction, whether PACAP/receptor signaling contributes to increased voiding frequency and somatic sensitivity was evaluated in NGF-OE mice. Intravesical administration of the PAC1 receptor antagonist, PACAP(6-38) (300 nM), significantly (p ≤ 0.01) increased intercontraction interval (2.0-fold) and void volume (2.5-fold) in NGF-OE mice. Intravesical instillation of PACAP(6-38) also decreased baseline bladder pressure in NGF-OE mice. PACAP(6-38) had no effects on bladder function in WT mice. Intravesical administration of PACAP(6-38) (300 nM) significantly (p ≤ 0.01) reduced pelvic sensitivity in NGF-OE mice but was without effect in WT mice. PACAP/receptor signaling contributes to the increased voiding frequency and pelvic sensitivity observed in NGF-OE mice.

A novel method for assessing bladder-related pain reveals the involvement of nerve growth factor in pain associated with cyclophosphamide-induced chronic cystitis in mice

BACKGROUND

Pain is a prominent feature of interstitial cystitis/painful bladder syndrome (IC/PBS), but the underlying mechanisms are not fully understood. There is a lack of well-characterized research tools, such as pain evaluation methods and experimental animal models, for investigating non-ulcerative cystitis. We developed a novel method for evaluating bladder pain in mice with cyclophosphamide (CYP)-induced cystitis.

METHODS

Cystitis was produced by a single intraperitoneal injection of CYP (300 mg/kg) or repeated injections of CYP (150 mg/kg once daily for 4 days). Blunt stimulation with a cotton probe was applied to the abdominal region, and the thresholds for withdrawal responses were measured quantitatively using an anaesthesiometer.

RESULTS

The single injection of CYP provoked acute cystitis with severe bladder inflammation in mice. In these mice, we could detect an increased sensitivity to blunt stimulation, which was abolished by intravesical lidocaine. The stimulation induced phosphorylation of extracellular signal-regulated kinases in bladder-projecting sensory neurons. Chronic treatment with CYP produced persistent pain responses to the blunt stimulus. Although there were few signs of bladder inflammation in these mice, the concentration of nerve growth factor (NGF) was elevated in bladder tissue, and NGF antiserum inhibited the hypersensitivity.

CONCLUSIONS

The blunt probe method is useful for evaluating bladder pain signalling in mice, and revealed the involvement of an NGF-sensitive pain pathway in chronic cystitis pain. This assessment method may be useful for studying the pathophysiology of bladder pain and for developing therapeutic strategies for non-ulcerative IC/PBS in patients.

Role of CXCR2 and TRPV1 in functional, inflammatory and behavioural changes in the rat model of cyclophosphamide-induced haemorrhagic cystitis

BACKGROUND AND PURPOSE

Cyclophosphamide induces urotoxicity characterized by the development of cystitis, which involves bladder overactivity and inflammation. Here, we investigated the roles of chemokine receptor 2 (CXCR2) and transient receptor potential vanilloid 1 (TRPV1) channels in a rat model of cyclophosphamide-induced cystitis.

EXPERIMENTAL APPROACH

Cystitis induced by cyclophosphamide in rats was assessed by gross morphology, histology and immunohistochemistry of bladder tissue. mRNA for CXCR2 and TRPV1 channels were measured by RT-PCR. Nociceptive responses in paw and abdomen, along with cystometric measures were recorded.

KEY RESULTS

Cyclophosphamide, i.p., induced pain behaviour, bladder inflammation and voiding dysfunction. The CXCR2 antagonist, SB225002, the TRPV1 channel antagonist, SB366791 or their combination reduced the mechanical hypersensitivity of paw and abdominal area and nociceptive behaviour after cyclophosphamide. Cyclophosphamide-induced cystitis was characterized by haemorrhage, oedema, neutrophil infiltration and other inflammatory changes, which were markedly decreased by the antagonists. Up-regulation of CXCR2 and TRPV1 mRNA in the bladder after cyclophosphamide was inhibited by SB225002, SB366791 or their combination. Expression of CXCR2 and TRPV1 channels was increased in the urothelium after cyclophosphamide. Bladder dysfunction was shown by increased number of non-voiding contractions (NVCs) and bladder pressures and a reduction in bladder capacity (BC), voided volume (VV) and voiding efficiency (VE). SB225002 or its combination with SB366791 reduced bladder pressures, whereas SB225002, SB366791 or their combination increased BC, VV and VE, and also reduced the number of NVCs.

CONCLUSIONS AND IMPLICATIONS

CXCR2 and TRPV1 channels play important roles in cyclophosphamide-induced cystitis in rats and could provide potential therapeutic targets for cystitis.

Repeated variate stress in male rats induces increased voiding frequency, somatic sensitivity, and urinary bladder nerve growth factor expression

Stress exacerbates symptoms of functional lower urinary tract disorders including interstitial cystitis (IC)/bladder pain syndrome (BPS) and overactive bladder (OAB) in humans, but mechanisms contributing to symptom worsening are unknown. These studies address stress-induced changes in the structure and function of the micturition reflex using an animal model of stress in male rats. Rats were exposed to 7 days of repeated variate stress (RVS). Target organ (urinary bladder, thymus, adrenal gland) tissues were collected and weighed following RVS. Evans blue (EB) concentration and histamine, myeloperoxidase (MPO), nerve growth factor (NGF), brain-derived neurotropic factor (BDNF), and CXCL12 protein content (ELISA) were measured in the urinary bladder, and somatic sensitivity of the hindpaw and pelvic regions was determined following RVS. Bladder function was evaluated using continuous, open outlet intravesical infusion of saline in conscious rats. Increases in body weight gain were significantly (P ≤ 0.01) attenuated by day 5 of RVS, and adrenal weight was significantly (P ≤ 0.05) increased. Histamine, MPO, NGF, and CXCL12 protein expression was significantly (P ≤ 0.01) increased in the urinary bladder after RVS. Somatic sensitivity of the hindpaw and pelvic regions was significantly (P ≤ 0.01) increased at all monofilament forces tested (0.1-4 g) after RVS. Intercontraction interval, infused volume, and void volume were significantly (P ≤ 0.01) decreased after RVS. These studies demonstrate increased voiding frequency, histamine, MPO, NGF, and CXCL12 bladder content and somatic sensitivity after RVS suggesting an inflammatory component to stress-induced changes in bladder function and somatic sensitivity.

Expression and function of CCL2/CCR2 in rat micturition reflexes and somatic sensitivity with urinary bladder inflammation

Chemokines are proinflammatory mediators of the immune response, and there is growing evidence for chemokine/receptor signaling involvement in pronociception. Bladder pain syndrome (BPS)/interstitial cystitis (IC) is a chronic pain syndrome characterized by pain, pressure, or discomfort perceived to be bladder-related with at least one urinary symptom. We have explored the expression and functional roles of CCL2 (monocyte chemoattractant protein-1) and its high-affinity receptor, CCR2, in micturition reflex function and somatic sensitivity in rats with urinary bladder inflammation induced by cyclophosphamide (CYP) treatment of varying duration (4 h, 48 h, chronic). Real-time quantitative RT-PCR, ELISAs, and immunohistochemistry demonstrated significant (P ≤ 0.01) increases in CCL2 and CCR2 expression in the urothelium and in Fast Blue-labeled bladder afferent neurons in lumbosacral dorsal root ganglia with CYP-induced cystitis. Intravesical infusion of RS504393 (5 μM), a specific CCR2 antagonist, reduced voiding frequency and increased bladder capacity and void volume in rats with CYP-induced cystitis (4 h), as determined with open outlet, conscious cystometry. In addition, CCR2 blockade, at the level of the urinary bladder, reduced referred somatic sensitivity of the hindpaw and pelvic region in rats with CYP treatment, as determined with von Frey filament testing. We provide evidence of functional roles for CCL2/CCR2 signaling at the level of the urinary bladder in reducing voiding frequency and somatic sensitivity following CYP-induced cystitis (4 h). These studies suggest that chemokines/receptors may be novel targets with therapeutic potential in the context of urinary bladder inflammation.

Antagonism of the transient receptor potential ankyrin 1 (TRPA1) attenuates hyperalgesia and urinary bladder overactivity in cyclophosphamide-induced haemorrhagic cystitis

The aim of this study was to investigate the involvement of the transient receptor potential ankyrin 1 (TRPA1) in haemorrhagic cystitis, the main side effect of cyclophosphamide-based chemotherapy. Hannover female rats received intraperitoneal (i.p.) injection of cyclophosphamide (three doses of 100 mg/kg, every other day, in a total of five days). This treatment was followed by the treatment with TRPA1 antagonist HC 030031 (50 mg/kg, p.o.). The threshold for hindpaw withdrawal or abdominal retraction to von Frey Hair and the locomotor activity were measured. The treatment with the TRPA1 antagonist HC 030031 significantly decreased mechanical hyperalgesia induced by cyclophosphamide without interfere with locomotor activity. Urodynamic parameters were performed by cystometry 24 h after a single treatment with cyclophosphamide (200 mg/kg, i.p.) in control and HC 030031 treated rats. Analyses of the urodynamic parameters showed that a single dose of cyclophosphamide was enough to significantly increase the number and amplitude of non-voiding contractions and to decrease the voided volume and voiding efficiency, without significantly altering basal, threshold or maximum pressure. The treatment with HC 030031 either before (100 mg/kg, p.o.) or after (30 mg/kg, i.v.) cyclophosphamide inhibited the non-voiding contractions but failed to counteract the loss in voiding efficiency. Our data demonstrates that nociceptive symptoms and urinary bladder overactivity caused by cyclophosphamide, in part, are dependent upon the activation of TRPA1. In this context, the antagonism of the receptor may be an alternative to minimise the urotoxic symptoms caused by this chemotherapeutic agent.

Activation of cannabinoid receptor 2 inhibits experimental cystitis

Cannabinoids have been shown to exert analgesic and anti-inflammatory effects, and the effects of cannabinoids are mediated primarily by cannabinoid receptors 1 and 2 (CB1and CB2). Both CB1 and CB2 are present in bladders of various species, including human, monkey, and rodents, and it appears that CB2 is highly expressed in urothelial cells. We investigated whether treatment with the CB2 agonist GP1a alters severity of experimental cystitis induced by acrolein and referred mechanical hyperalgesia associated with cystitis. We also investigated whether the mitogen-activated protein kinases (MAPK), ERK1/2, p38, and JNK are involved in the functions of CB2. We found that treatment with the selective CB2 agonist GP1a (1-10 mg/kg, ip) inhibited the severity of bladder inflammation 3 h after intravesical instillation of acrolein in a dose-dependent manner, and inhibition reached significance at a dose of 10 mg/kg (P < 0.05). Treatment with GP1a (10 mg/kg) inhibited referred mechanical hyperalgesia associated with cystitis (P < 0.05). The inhibitory effects of the CB2 agonist were prevented by the selective CB2 antagonist AM630 (10 mg/kg, sc). We further demonstrated the inhibitory effects of CB2 appear to be at least partly mediated by reducing bladder inflammation-induced activation of ERK1/2 MAPK pathway. The results of the current study indicate that CB2 is a potential therapeutic target for treatment of bladder inflammation and pain in patients.

Transcriptional and translational plasticity in rodent urinary bladder TRP channels with urinary bladder inflammation, bladder dysfunction, or postnatal maturation

These studies examined the transcriptional and translational plasticity of three transient receptor potential (TRP) channels (TRPA1, TRPV1, TRPV4) with established neuronal and non-neuronal expression and functional roles in the lower urinary tract. Mechanosensor and nociceptor roles in either physiological or pathological lower urinary tract states have been suggested for TRPA1, TRPV1, and TRPV4. We have previously demonstrated the neurochemical, organizational, and functional plasticity in micturition reflex pathways following induction of urinary bladder inflammation using the antineoplastic agent, cyclophosphamide. More recently, we have characterized similar plasticity in micturition reflex pathways in a transgenic mouse model with chronic urothelial overexpression (OE) of nerve growth factor (NGF) and in a transgenic mouse model with deletion of vasoactive intestinal polypeptide (VIP). In addition, the micturition reflex undergoes postnatal maturation that may also reflect plasticity in urinary bladder TRP channel expression. Thus, we examined plasticity in urinary bladder TRP channel expression in diverse contexts using a combination of quantitative, real-time PCR and western blotting approaches. We demonstrate transcriptional and translational plasticity of urinary bladder TRPA1, TRPV1, and TRVP4 expression. Although the functional significance of urinary bladder TRP channel plasticity awaits further investigation, these studies demonstrate context- (inflammation, postnatal development, NGF-OE, VIP deletion) and tissue-dependent (urothelium + suburothelium, detrusor) plasticity.

Remote control of renal physiology by the intestinal neuropeptide pigment-dispersing factor in Drosophila

The role of the central neuropeptide pigment-dispersing factor (PDF) in circadian timekeeping in Drosophila is remarkably similar to that of vasoactive intestinal peptide (VIP) in mammals. Like VIP, PDF is expressed outside the circadian network by neurons innervating the gut, but the function and mode of action of this PDF have not been characterized. Here we investigate the visceral roles of PDF by adapting cellular and physiological methods to the study of visceral responses to PDF signaling in wild-type and mutant genetic backgrounds. We find that intestinal PDF acts at a distance on the renal system, where it regulates ureter contractions. We show that PdfR, PDF's established receptor, is expressed by the muscles of the excretory system, and present evidence that PdfR-induced cAMP increases underlie the myotropic effects of PDF. These findings extend the similarities between PDF and VIP beyond their shared central role as circadian regulators, and uncover an unexpected endocrine mode of myotropic action for an intestinal neuropeptide on the renal system.

Autonomic dysfunction and plasticity in micturition reflexes in human α-synuclein mice

Although often overshadowed by the motor dysfunction associated with Parkinson's disease (PD), autonomic dysfunction including urinary bladder and bowel dysfunctions are often associated with PD and may precede motoric changes; such autonomic dysfunction may permit early detection and intervention. Lower urinary tract symptoms are common in PD patients and result in significant morbidity. This studies focus on nonmotor symptoms in PD using a transgenic mouse model with overexpression of human α-synuclein (hSNCA), the peptide found in high concentrations in Lewy body neuronal inclusions, the histopathologic hallmark of PD. We examined changes in the physiological, molecular, chemical, and electrical properties of neuronal pathways controlling urinary bladder function in transgenic mice. The results of these studies reveal that autonomic dysfunction (i.e., urinary bladder) can precede motor dysfunction. In addition, mice with hSNCA overexpression in relevant neuronal populations is associated with alterations in expression of neurotransmitter/neuromodulatory molecules (PACAP, VIP, substance P, and neuronal NOS) within neuronal pathways regulating bladder function as well as with increased NGF expression in the urinary bladder. Changes in the electrical and synaptic properties of neurons in the major pelvic ganglia that provide postganglionic innervation to urogenital tissues were not changed as determined with intracellular recording. The urinary bladder dysfunction observed in transgenic mice likely reflects changes in peripheral (i.e., afferent) and/or central micturition pathways or changes in the urinary bladder. SYN-OE mice provide an opportunity to examine early events underlying the molecular and cellular plasticity of autonomic nervous system pathways underlying synucleinopathies.

Increased expression of interleukin-6 family members and receptors in urinary bladder with cyclophosphamide-induced bladder inflammation in female rats

Recent studies suggest that janus-activated kinases-signal transducer and activator of transcription signaling pathways contribute to increased voiding frequency and referred pain of cyclophosphamide (CYP)-induced cystitis in rats. Potential upstream chemical mediator(s) that may be activated by CYP-induced cystitis to stimulate JAK/STAT signaling are not known in detail. In these studies, members of the interleukin (IL)-6 family of cytokines including, leukemia inhibitory factor (LIF), IL-6, and ciliary neurotrophic factor (CNTF) and associated receptors, IL-6 receptor (R) α, LIFR, and gp130 were examined in the urinary bladder in control and CYP-treated rats. Cytokine and receptor transcript and protein expression and distribution were determined in urinary bladder after CYP-induced cystitis using quantitative, real-time polymerase chain reaction (Q-PCR), western blotting, and immunohistochemistry. Acute (4 h; 150 mg/kg; i.p.), intermediate (48 h; 150 mg/kg; i.p.), or chronic (75 mg/kg; i.p., once every 3 days for 10 days) cystitis was induced in adult, female Wistar rats with CYP treatment. Q-PCR analyses revealed significant (p ≤ 0.01) CYP duration- and tissue- (e.g., urothelium, detrusor) dependent increases in LIF, IL-6, IL-6Rα, LIFR, and gp130 mRNA expression. Western blotting demonstrated significant (p ≤ 0.01) increases in IL-6, LIF, and gp130 protein expression in whole urinary bladder with CYP treatment. CYP-induced cystitis significantly (p ≤ 0.01) increased LIF-immunoreactivity (IR) in urothelium, detrusor, and suburothelial plexus whereas increased gp130-IR was only observed in urothelium and detrusor. These studies suggest that IL-6 and LIF may be potential upstream chemical mediators that activate JAK/STAT signaling in urinary bladder pathways.

Neurotrophin/receptor expression in urinary bladder of mice with overexpression of NGF in urothelium

Urothelium-specific overexpression of nerve growth factor (NGF) in the urinary bladder of transgenic mice stimulates neuronal sprouting in the urinary bladder, produces increased voiding frequency, and results in increased referred somatic hypersensitivity. Additional NGF-mediated pleiotropic changes might contribute to the increased voiding frequency and pelvic hypersensitivity observed in these transgenic mice, such as modulation of other growth factor/receptor systems. Chronic overexpression of NGF in the urothelium was achieved through the use of a highly urothelium-specific uroplakin II promoter. In the present study, we examined NGF, brain-derived neurotrophic factor (BDNF), and associated receptor [p75(NTR), tyrosine kinase (Trk)A, TrkB] transcript and protein expression in urothelium and detrusor smooth muscle of NGF-overexpressing (OE) and littermate wild-type mice, using real-time quantitative reverse transcription-polymerase chain reaction, ELISAs, and semiquantitation of immunohistochemistry. We focused on these growth factor/receptors given the established roles of NGF/TrkA, NGF/p75(NTR), and BDNF/TrkB systems in bladder function. Increased voiding frequency in NGF-OE mice was confirmed by examining urination patterns. BDNF, TrkA, and TrkB protein expression was significantly (P ≤ 0.01) reduced and p75(NTR) protein expression was significantly (P ≤ 0.01) increased in urinary bladder of NGF-OE mice. The NGF-OE-induced changes in neurotrophic factor/receptor expression in urinary bladder may represent compensatory changes to reduce voiding frequency in the NGF-OE mouse.

Neuropeptides in lower urinary tract function

Numerous neuropeptide/receptor systems including vasoactive intestinal polypeptide, pituitary adenylate cyclase-activating polypeptide, calcitonin gene-related peptide, substance P, neurokinin A, bradykinin, and endothelin-1 are expressed in the lower urinary tract (LUT) in both neural and nonneural (e.g., urothelium) components. LUT neuropeptide immunoreactivity is present in afferent and autonomic efferent neurons innervating the bladder and urethra and in the urothelium of the urinary bladder. Neuropeptides have tissue-specific distributions and functions in the LUT and exhibit neuroplastic changes in expression and function with LUT dysfunction following neural injury, inflammation, and disease. LUT dysfunction with abnormal voiding, including urinary urgency, increased voiding frequency, nocturia, urinary incontinence, and pain, may reflect a change in the balance of neuropeptides in bladder reflex pathways. LUT neuropeptide/receptor systems may represent potential targets for therapeutic intervention.

VIP and PACAP effects on mouse major pelvic ganglia neurons

Major pelvic ganglia (MPG) neurons innervate urogenital organs and components of the lower bowel. Immunoreactivity for vasoactive intestinal polypeptide (VIP) has previously been observed in the MPG, and VIP knockout animals have impaired micturition reflexes suggesting a role for this neuropeptide in urogenital function. Here, we investigate the presence and action of VIP and a related neuropeptide, pituitary adenylate cyclase activating polypeptide (PACAP), in the pelvic ganglia of male mice. An abundance of VIP-immunoreactive (IR) neurons and nerve fibers were observed in the ganglion, whereas PACAP immunoreactivity was not seen. Extracts from acutely isolated MPG contained transcripts for the VPAC1, VPAC2, and PAC1 receptors. Local application of VIP, PACAP, or maxadilan to isolated pelvic ganglion neurons shortened the duration of the afterhyperpolarization (AHP) of action potentials elicited by brief intracellular depolarization. All three peptides also increased neuronal excitability within a subpopulation of the sampled neurons. Bath application of apamin, a peptide antagonist of SK channels, shortened the duration of the AHP indicating that AHP duration in pelvic neurons is determined principally by SK-channel activity. The results suggest that VIP has a role in the neural control of pelvic organ function and activation of VPAC and/or PAC1 receptors can modulate the activity of the autonomic neurons innervating pelvic organs.

PACAP expression in explant cultured mouse major pelvic ganglia

The major pelvic ganglia (MPG) contain both parasympathetic and sympathetic postganglionic neurons and provide much of the autonomic innervation to urogenital organs and components of the lower bowel. Whereas many parasympathetic neurons were found to express vasoactive intestinal polypeptide (VIP), no MPG neurons exhibited immunoreactivity for pituitary adenylate cyclase-activating polypeptide (PACAP). However, in 3-day cultured MPGs, numerous PACAP-IR cells and nerve fibers were present, and transcript levels for PACAP increased significantly. In 3-day cultured MPGs, PACAP immunoreactivity was seen in cells that were also immunoreactive for VIP or neuronal nitric oxide synthase, but not tyrosine hydroxylase, indicating that PACAP expression occurred preferentially in MPG parasympathetic postganglionic neurons. Transcript levels for the VPAC2, but not VPAC1 or PAC1 receptor, also increased significantly following 3 days in culture. Transcript levels of activating transcription factor 3 (ATF-3), a marker of cellular injury, were increased 64-fold in 3-day explants, and ATF-3-IR nuclei were evident in both TH-IR and nNOS-IR neurons as well as in non-neuronal cells. In sum, these results demonstrate that, although only the parasympathetic neurons in explant cultured MPGs increase expression of PACAP, both sympathetic and parasympathetic postganglionic neurons in the cultured MPG whole-mount increase expression of ATF-3.

Bladder dysfunction and altered somatic sensitivity in PACAP-/- mice

PURPOSE

PACAP and receptors are expressed in micturition pathways. Studies show that PACAP has a role in detrusor smooth muscle contraction to facilitate adenosine triphosphate release from urothelium and PACAP antagonism decreases cyclophosphamide induced bladder hyperreflexia.

MATERIALS AND METHODS

PACAP contributions to micturition and somatic sensation were studied in PACAP knockout (PACAP(-/-)), litter mate heterozygote (PACAP(+/-)) and WT mice by conscious cystometry with continuous intravesical saline or acetic acid (0.5%) instillation, urination patterns, somatic sensitivity testing of hind paw and pelvic regions with calibrated von Frey filaments, and morphological bladder assessments.

RESULTS

PACAP(-/-) mice had an increased bladder mass with fewer but larger urine spots. In PACAP(-/-) mice the lamina propria and detrusor smooth muscle were significantly thicker but the urothelium was unchanged. PACAP(-/-) mice had increased bladder capacity, voided volume and intercontraction interval with significantly increased detrusor contraction duration and large residual volume. WT mice responded to acetic acid (0.5%) with a decrease in voided volume and intercontraction interval but PACAP(+/-) and PACAP(-/-) mice did not respond. PACAP(-/-) mice were less responsive to somatic stimulation. PACAP(+/-) mice also had bladder dysfunction, and somatic and visceral sensory abnormalities but to a lesser degree.

CONCLUSIONS

PACAP gene disruption contributes to changes in bladder morphology and function, and somatic and visceral hypoalgesia.

Expression and function of CXCL12/CXCR4 in rat urinary bladder with cyclophosphamide-induced cystitis

Chemokines, otherwise known as chemotactic cytokines, are proinflammatory mediators of the immune response and have been implicated in altered sensory processing, hyperalgesia, and central sensitization following tissue injury or inflammation. To address the role of CXCL12/CXCR4 signaling in normal micturition and inflammation-induced bladder hyperreflexia, bladder inflammation in adult female Wistar rats (175-250 g) was induced by injecting cyclophosphamide (CYP) intraperitoneally at acute (150 mg/kg; 4 h), intermediate (150 mg/kg; 48 h), and chronic (75 mg/kg; every 3rd day for 10 days) time points. CXCL12, and its receptor, CXCR4, were examined in the whole urinary bladder of control and CYP-treated rats using enzyme-linked immunosorbent assays (ELISAs), quantitative PCR (qRT-PCR), and immunostaining techniques. ELISAs, qRT-PCR, and immunostaining experiments revealed a significant (P < or = 0.01) increase in CXCL12 and CXCR4 expression in the whole urinary bladder, and particularly in the urothelium, with CYP treatment. The functional role of CXCL12/CXCR4 signaling in micturition was evaluated using conscious cystometry with continuous instillation of saline and CXCR4 receptor antagonist (AMD-3100; 5 microM) administration in control and CYP (48 h)-treated rats. Receptor blockade of CXCR4 using AMD-3100 increased bladder capacity in control (no CYP) rats and reduced CYP-induced bladder hyperexcitability as demonstrated by significant (P < or = 0.01) increases in intercontraction interval, bladder capacity, and void volume. These results suggest a role for CXCL12/CXCR4 signaling in both normal micturition and with bladder hyperreflexia following bladder inflammation.

Involvement of JAK-STAT signaling/function after cyclophosphamide-induced bladder inflammation in female rats

Cytokines are upregulated in a variety of inflammatory conditions and cytokine/receptor interactions can activate JAK-STAT signaling. Previous studies demonstrated upregulation of numerous cytokines in the urinary bladder following cyclophosphamide (CYP)-induced cystitis. The role of JAK-STAT signaling in urinary bladder inflammation and referred somatic sensitivity has not been addressed. The contribution of JAK-STAT signaling pathways in CYP-induced bladder hyperreflexia and referred somatic hypersensitivity was determined in CYP-treated rats using a JAK2 inhibitor, AG490. Acute (4 h; 150 mg/kg ip), intermediate (48 h; 150 mg/kg ip), or chronic (75 mg/kg ip, once every 3 days for 10 days) cystitis was induced in adult, female Wistar rats with CYP treatment. Phosphorylation status of STAT-3 was increased in urinary bladder after CYP-induced cystitis (4 h, 48 h, chronic). Blockade of JAK2 with AG490 (5-15 mg/kg ip or intravesical) significantly (P < or = 0.05) reduced bladder hyperreflexia and hind paw sensitivity in CYP-treated rats. These studies demonstrate a potential role for JAK-STAT signaling pathways in bladder hyperreflexia and referred pain induced by CYP-induced bladder inflammation.