Characterization of the capsaicin-sensitive component of cyclophosphamide-induced inflammation in the rat urinary bladder

Suppression of Inflammatory and Fibrotic Signals by Cinnamon (Cinnamomum cassia) and Cinnamaldehyde in Cyclophosphamide-Induced Overactive Bladder in Mice

Cinnamon (Cinnamomum cassia) is a well-known traditional Chinese medicine used to treat nocturia by tonifying and warming the kidney. Our recent clinical study found that overactive bladder (OAB) patients treated with cinnamon powder (CNP) patches exhibited significantly ameliorated OAB symptoms without significant side effects, but the mechanism of action is unclear. To explore the beneficial effects and action mechanisms of CNP and its major active component cinnamaldehyde (CNA) in an OAB-related murine model, cyclophosphamide- (CYP-) induced OAB injury was performed on male ICR mice in the presence or absence of CNP and CNA, as well as solifenacin, a clinical drug for OAB as a reference. Twenty-four-hour micturition patterns (frequency of urination and volume of urine per time), as well as histopathological examination, immunohistochemistry (IHC), and Western blotting of the bladder, were analyzed for mechanism elucidation. Administration of CYP (300 mg/kg, i.p.) induced typical OAB pathophysiological changes, including increased frequency of urination and reduced volume of urine. CYP-induced mice displayed strong edema of the bladder and hemorrhagic cystitis, accompanied by loss of normal corrugated folds and decreased muscarinic receptors (M2/M3) in the urothelium, and disordered/broken structures of the lamina propria and detrusor. These changes were correlated with increased leukocyte (CD11b) infiltration colocalized with inflammatory (pp65 NFκB, macrophage migration inhibitory factor (MIF)/Toll-like receptor 4 (TLR4)) and fibrotic (stem cell factor (SCF)/c-Kit, α-smooth muscle actin (α-SMA)/β-catenin) signals. Treatment with CNP (600 mg/kg, p.o.) and CNA (10–50 mg/kg, p.o.), but not solifenacin (50 mg/kg), 30 min after CYP induction significantly ameliorated CYP-induced dysfunction in micturition patterns and pathophysiological changes. CNP and CNA further suppressed MIF/TLR4-associated inflammatory and SCF/c-Kit-related fibrotic signaling pathways. Our findings indicate that suppression of inflammatory and fibrotic signals contributes to the crucial mechanism in the improvement of CYP-induced OAB by CNP and CNA.

The Influence of an Adrenergic Antagonist Guanethidine (GUA) on the Distribution Pattern and Chemical Coding of Dorsal Root Ganglia (DRG) Neurons Supplying the Porcine Urinary Bladder

Although guanethidine (GUA) was used in the past as a drug to suppress hyperactivity of the sympathetic nerve fibers, there are no available data concerning the possible action of this substance on the sensory component of the peripheral nervous system supplying the urinary bladder. Thus, the present study was aimed at disclosing the influence of intravesically instilled GUA on the distribution, relative frequency, and chemical coding of dorsal root ganglion neurons associated with the porcine urinary bladder. The investigated sensory neurons were visualized with a retrograde tracing method using Fast Blue (FB), while their chemical profile was disclosed with single-labeling immunohistochemistry using antibodies against substance P (SP), calcitonin gene-related peptide (CGRP), pituitary adenylate cyclase activating polypeptide (PACAP), galanin (GAL), neuronal nitric oxide synthase (nNOS), somatostatin (SOM), and calbindin (CB). After GUA treatment, a slight decrease in the number of FB⁺ neurons containing SP was observed when compared with untreated animals (34.6 ± 6.5% vs. 45.6 ± 1.3%), while the number of retrogradely traced cells immunolabeled for GAL, nNOS, and CB distinctly increased (12.3 ± 1.0% vs. 7.4 ± 0.6%, 11.9 ± 0.6% vs. 5.4 ± 0.5% and 8.6 ± 0.5% vs. 2.7 ± 0.4%, respectively). However, administration of GUA did not change the number of FB⁺ neurons containing CGRP, PACAP, or SOM. The present study provides evidence that GUA significantly modifies the sensory innervation of the porcine urinary bladder wall and thus may be considered a potential tool for studying the plasticity of this subdivision of the bladder innervation.

A Method to Isolate Pericytes From the Mouse Urinary Bladder for the Study of Diabetic Bladder Dysfunction

Purpose

Pericytes surround the endothelial cells in microvessels and play a distinct role in controlling vascular permeability and maturation. The loss of pericyte function is known to be associated with diabetic retinopathy and erectile dysfunction. This study aimed to establish a technique for the isolation of pericytes from the mouse urinary bladder and an in vitro model that mimics in vivo diabetic bladder dysfunction.

Methods

To avoid contamination with epithelial cells, the urothelial layer was meticulously removed from the underlying submucosa and detrusor muscle layer. The tissues were cut into multiple pieces, and the fragmented tissues were settled by gravity into collagen I-coated culture plates. The cells were cultured under normal-glucose (5 mmol/L) or high-glucose (30 mmol/L) conditions, and tube formation, cell proliferation, and TUNEL assays were performed. We also performed hydroethidine staining to measure superoxide anion production.

Results

We successfully isolated high-purity pericytes from the mouse urinary bladder. The cells were positively stained for platelet-derived growth factor receptor-β and NG2 and negatively stained for smooth muscle cell markers (desmin and myosin) and an endothelial cell marker (CD31). The number of tubes formed and the number of proliferating cells were significantly lower when the pericytes were exposed to high-glucose conditions compared with normal-glucose conditions. In addition, there were significant increases in superoxide anion production and the number of apoptotic cells when the pericytes were cultured under high-glucose conditions.

Conclusions

To the best of our knowledge, this is the first study to isolate and culture pericytes from the mouse urinary bladder. Our model would be a useful tool for screening the efficacy of therapeutic candidates targeting pericyte function in diabetic bladder dysfunction and exploring the functional role of specific targets at the cellular level.

Activation of soluble guanylyl cyclase by BAY 58-2667 improves bladder function in cyclophosphamide-induced cystitis in mice

Activators of soluble guanylyl cyclase (sGC) interact directly with its prosthetic heme group, enhancing the enzyme responsiveness in pathological conditions. This study aimed to evaluate the effects of the sGC activator BAY 58-2667 on voiding dysfunction, protein expressions of α1 and β1 sGC subunits and cGMP levels in the bladder tissues after cyclophosphamide (CYP) exposure. Female C57BL/6 mice (20-25 g) were injected with CYP (300 mg/kg ip) to induce cystitis. Mice were pretreated or not with BAY 58-2667 (1 mg/kg, gavage), given 1 h before CYP injection. The micturition patterns and in vitro bladder contractions were evaluated at 24 h. In freely moving mice, the CYP injection produced reduced the micturition volume and increased the number of urine spots. Cystometric recordings in CYP-injected mice revealed significant increases in basal pressure, voiding frequency, and nonvoiding contractions (NVCs), along with decreases in bladder capacity, intercontraction interval, and compliance. BAY 58-2667 significantly prevented the micturition alterations observed in both freely moving mice and cystometry and normalized the reduced in vitro carbachol-induced contractions in the CYP group. Reduced protein expressions of α1 and β1 sGC subunits and of cGMP levels were observed in the CYP group, all of which were prevented by BAY 58-2667. CYP exposure significantly increased reactive-oxygen species (ROS) generation in both detrusor and urothelium, and this was normalized by BAY 58-2667. The increased myeloperoxidase and cyclooxygenase-2 activities in the bladders of the CYP group remained unchanged by BAY 58-2667. Activators of sGC may constitute a novel and promising therapeutic approach for management of interstitial cystitis.

The TRPA1 channel in inflammatory and neuropathic pain and migraine

The transient receptor potential ankyrin 1 (TRPA1), a member of the TRP superfamily of channels, is primarily localized to a subpopulation of primary sensory neurons of the trigeminal, vagal, and dorsal root ganglia. This subset of nociceptors produces and releases the neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP), which mediate neurogenic inflammatory responses. TRPA1 is activated by a number of exogenous compounds, including molecules of botanical origin, environmental irritants, and medicines. However, the most prominent feature of TRPA1 resides in its unique sensitivity for large series of reactive byproducts of oxidative and nitrative stress. Here, the role of TRPA1 in models of different types of pain, including inflammatory and neuropathic pain and migraine, is summarized. Specific attention is paid to TRPA1 as the main contributing mechanism to the transition of mechanical and cold hypersensitivity from an acute to a chronic condition and as the primary transducing pathway by which oxidative/nitrative stress produces acute nociception, allodynia, and hyperalgesia. A series of migraine triggers or medicines have been reported to modulate TRPA1 activity and the ensuing CGRP release. Thus, TRPA1 antagonists may be beneficial in the treatment of inflammatory and neuropathic pain and migraine.

Inflammation and pyroptosis mediate muscle expansion in an interleukin-1β (IL-1β)-dependent manner

Muscle inflammation is often associated with its expansion. Bladder smooth muscle inflammation-induced cell death is accompanied by hyperplasia and hypertrophy as the primary cause for poor bladder function. In mice, DNA damage initiated by chemotherapeutic drug cyclophosphamide activated caspase 1 through the formation of the NLRP3 complex resulting in detrusor hyperplasia. A cyclophosphamide metabolite, acrolein, caused global DNA methylation and accumulation of DNA damage in a mouse model of bladder inflammation and in cultured bladder muscle cells. In correlation, global DNA methylation and NLRP3 expression was up-regulated in human chronic bladder inflammatory tissues. The epigenetic silencing of DNA damage repair gene, Ogg1, could be reversed by the use of demethylating agents. In mice, demethylating agents reversed cyclophosphamide-induced bladder inflammation and detrusor expansion. The transgenic knock-out of Ogg1 in as few as 10% of the detrusor cells tripled the proliferation of the remaining wild type counterparts in an in vitro co-culture titration experiment. Antagonizing IL-1β with Anakinra, a rheumatoid arthritis therapeutic, prevented detrusor proliferation in conditioned media experiments as well as in a mouse model of bladder inflammation. Radiation treatment validated the role of DNA damage in the NLRP3-associated caspase 1-mediated IL-1β secretory phenotype. A protein array analysis identified IGF1 to be downstream of IL-1β signaling. IL-1β-induced detrusor proliferation and hypertrophy could be reversed with the use of Anakinra as well as an IGF1 neutralizing antibody. IL-1β antagonists in current clinical practice can exploit the revealed mechanism for DNA damage-mediated muscular expansion.

Effect of inflammatory mediators on ATP release of human urothelial RT4 cells

Inflammation is an important contributor to the aetiology of a number of bladder dysfunctions including interstitial cystitis, painful bladder syndrome, and overactive bladder. The aim of this study was to examine the effects of inflammatory mediators on urothelial ATP release. Human urothelial RT4 cells were exposed to normal buffer or varying concentrations of inflammatory mediators (bradykinin, histamine, and serotonin) in the presence or absence of hypotonic stretch stimuli (1 : 2 dilution of Krebs-Henseleit buffer). Others have demonstrated that bradykinin increased stretch-induced ATP release; however, we observed no change in control or stretch-induced ATP release with bradykinin. Pretreatment of RT4 cells with histamine or serotonin decreased stretch-induced ATP release (P = 0.037, P = 0.040, resp.). Previous studies have demonstrated increased ATP release in response to inflammation utilising whole bladder preparations in contrast to our simple model of cultured urothelial cells. The current study suggests that it is unlikely that there is a direct interaction between the release of inflammatory mediators and increased ATP release, but rather more complex interactions occurring in response to inflammation that lead to increased bladder sensation.

TRP channels and pain

Nociception is the process whereby primary afferent nerve fibers of the somatosensory system detect noxious stimuli. Pungent irritants from pepper, mint, and mustard plants have served as powerful pharmacological tools for identifying molecules and mechanisms underlying this initial step of pain sensation. These natural products have revealed three members of the transient receptor potential (TRP) ion channel family--TRPV1, TRPM8, and TRPA1--as molecular detectors of thermal and chemical stimuli that activate sensory neurons to produce acute or persistent pain. Analysis of TRP channel function and expression has validated the existence of nociceptors as a specialized group of somatosensory neurons devoted to the detection of noxious stimuli. These studies are also providing insight into the coding logic of nociception and how specification of nociceptor subtypes underlies behavioral discrimination of noxious thermal, chemical, and mechanical stimuli. Biophysical and pharmacological characterization of these channels has provided the intellectual and technical foundation for developing new classes of analgesic drugs.

Immunohistochemical characteristics of suburothelial microvasculature in the mouse bladder

The morphological characteristics of smooth muscle cells (SMCs) and their innervation of the suburothelial microvasculature of the mouse bladder were investigated by immunohistochemistry. Whole mount bladder mucosal preparations were immune-stained for α-smooth muscle actin (α-SMA) and/or neuronal markers and examined using confocal laser scanning microscopy. Suburothelial arterioles consisted of α-SMA-immunopositive circular smooth muscle cells, while the venular wall composed of α-SMA-positive SMCs that displayed several processes which extended from their cell bodies to form an extensive meshwork. In larger venules, a complex meshwork of stellate-shaped SMCs were observed. NG2 chondroitin sulphate proteoglycan-immunoreactive cell bodies of capillary pericytes were not immunoreactive for α-SMA. In the rat bladder suburothelial venules, circular SMCs were the dominant cell type expressing α-SMA-immunoreactivity. Since α-SMA-positive SMCs in suburothelial arterioles and venules in the mouse bladder had quite distinct morphologies, the innervation of both vessels could be examined by double labelling for α-SMA and various neuronal markers. Varicose nerve bundles immunoreactive for tyrosine hydroxylase (sympathetic nerves), choline acetyltransferase (cholinergic nerves) or substance P (primary afferent nerves) were all detected along side suburothelial arterioles. Single varicose nerve fibres positive for these three neuronal markers were also detected around the venules. Thus, whole mount preparations are useful when examining the morphology of α-SMA-positive SMCs of the microvasculature in the suburothelium of mouse bladder as well as their relationship with their innervations. In conclusion, arterioles and venules of the bladder suburothelium are the target of sympathetic, cholinergic and primary afferent nerve fibres.

Effects of kinin B(1) and B(2) receptor antagonists on overactive urinary bladder syndrome induced by spinal cord injury in rats

BACKGROUND AND PURPOSE

Kinin B(1) and B(2) receptors have been implicated in physiological and pathological conditions of the urinary bladder. However, their role in overactive urinary bladder (OAB) syndrome following spinal cord injury (SCI) remains elusive.

EXPERIMENTAL APPROACH

We investigated the role of kinin B(1) and B(2) receptors in OAB after SCI in rats.

KEY RESULTS

SCI was associated with a marked inflammatory response and functional changes in the urinary bladder. SCI resulted in an up-regulation of B(1) receptor mRNA in the urinary bladder, dorsal root ganglion and spinal cord, as well as in B(1) protein in the urinary bladder and B(1) and B(2) receptor protein in spinal cord. Interestingly, both B(1) and B(2) protein expression were similarly distributed in detrusor muscle and urothelium of animals with SCI. In vitro stimulation of urinary bladder with the selective B(1) or B(2) agonist elicited a higher concentration-response curve in the SCI urinary bladder than in naive or sham urinary bladders. Cystometry revealed that treatment of SCI animals with the B(2) selective antagonist icatibant reduced the amplitude and number of non-voiding contractions (NVCs). The B(1) antagonist des-Arg(9) -[Leu(8) ]-bradykinin reduced the number of NVCs while the non-peptide B(1) antagonist SSR240612 reduced the number of NVCs, the urinary bladder capacity and increased the voiding efficiency and voided volume.

CONCLUSIONS AND IMPLICATIONS

Taken together, these data show the important roles of B(1) and B(2) receptors in OAB following SCI in rats and suggest that blockade of these receptors could be a potential therapeutic target for controlling OAB.

Synergestic effect of lycopene and Melatonin against the genesis of oxidative stress induced by cyclophosphamide in rats

Cyclophosphamide (CP) is an alkylating agent that has been considered effective for cancer treatment. Lycopene, the pigment in tomato fruits, has beneficial effect in the treatment of some diseases. The goal of this study is to evaluate the protective effect of lycopene alone or combined with melatonin (Mel) in inhibiting the oxidative stress and toxic effect of CP in rats. Five groups of rats were included in this study; Group I served as the control. Rats in groups II-V were administrated with single dose of CP (150 mg/kg B.W) interperitoneally for 3 days. On the same day of CP administration, the rats in group III were fed a diet supplemented with lycopene (50 mg/kg of diet), rats in group IV were administered with a dose of 2.5 mg Mel/kg body weight (bw) injected subcutaneously and rats in group V were supplemented with lycopene and a dose of 2.5 mg Mel/kg bw injected subcutaneously. After 15 days the blood samples were collected. Results obtained showed that CP exerted its toxic effect by increasing the free radicals and reactive oxygen species that causes lipid peroxidation and cell damage, and this in turn is detected by elevation in nitric oxide (NO) and malondialdehyde (MDA), while the activities of antioxidants enzymes including (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)) were significantly decreased as compared with the control rats. The combined treatment (Lyco + Mel) group showed potential reduction in these parameters more than those treated with lyco alone. The activities of SOD, CAT and GPx were found significantly high than lyco alone treated rats. A positive significant correlation between NO and MDA ( r = .81). In conclusion, these results suggested that supplementation of diet with lycopene and Mel provided antioxidant defense with strong chemopreventive activity against Cp-induced cytotoxicity.

Effect of silymarin on bladder overactivity in cyclophosphamide-induced cystitis rat model

The purpose of this study was to investigate the effects of silymarin, a phytotherapeutic agent, on bladder overactivity in a cyclophosphamide (CYP)-induced cystitis rat model. Female Wistar Albino rats received a single intraperitoneal injection of CYP (150 mg/kg) or saline and after 72 h, bladder function was evaluated by in vitro preparations of whole bladders and cystometry with continuous saline infusion under urethane anesthesia. Silymarin or a vehicle was orally given for 7 days in rats. CYP was injected on the 5th day of silymarin or vehicle treatment and then the animals were killed on the 8th day. CYP-treatment dramatically potentiated the basal spontaneous contractions of isolated whole bladders compared to control rats. In anesthetized rats, during continuous infusion cystometry, intercontraction interval (ICI) was significantly shorter, but bladder voiding pressure was not significantly changed in CYP-injected rats compared to control rats. In the CYP-injected group, silymarin treatment significantly decreased the amplitude, frequency (contractions/min) and area under the curve of spontaneous contractions, but failed to change carbachol-induced contraction in isolated whole bladder. Also, silymarin treatment significantly increased the ICI in comparison to the vehicle treatment. In the saline-injected group, no significant changes in the bladder function were observed between the silymarin and vehicle-treated groups. Histopathological examination showed that CYP-induced bladder inflammation tended to be lower in the silymarin+CYP-treated group. In conclusion, the oral administration of silymarin suppressed CYP-induced bladder overactivity. Silymarin may be considered as an attractive treatment for CYP-induced bladder overactivity.

Inhibitory effects of phosphodiesterase 5 inhibitor, tadalafil, on mechanosensitive bladder afferent nerve activities of the rat, and on acrolein-induced hyperactivity of these nerves

What's known on the subject? and What does the study add? Tadalafil, a phosphodiesterase type 5 inhibitor, might be effective for not only erectile dysfunction but also lower urinary tract symptoms (LUTS). One of the mechanisms of tadalafil on LUTS is added in the study.

OBJECTIVE

To determine if tadalafil, a phosphodiesterase type 5 inhibitor, decreases afferent nerve activity from the bladder with and without chemical stimulation by intravesical acrolein instillation.

MATERIALS AND METHODS

Female Sprague-Dawley rats were used. Under urethane anaesthesia, single afferent fibres of the nerve primarily originating from the bladder were identified by electrical stimulation of the pelvic nerve and by bladder distension, and classified by conduction velocity as Aδ- or C-fibres. After measuring the baseline single afferent activities (SAA) during constant filling, two experiments were performed. First, tadalafil was administrated intravenously (i.v.) at three doses, 0.01, 0.03 and 0.1 mg/kg cumulatively and SAA were repeatedly studied after each administration. Second, in the presence of vehicle or tadalafil (0.1 mg/kg) i.v., the effect of intravesical instillation of acrolein (0.003%) was studied.

RESULTS

In all, 39 single units were isolated (Aδ-fibres 21; C-fibres, 18) in 25 rats. Tadalafil dose-dependently decreased SAA of both Aδ- and C-fibres during saline instillation. Intravesical acrolein facilitated SAA of both fibres after vehicle administration. Pretreatment with tadalafil significantly inhibited the acrolein-induced hyperactivity of both fibres.

CONCLUSION

Our study shows, using selective unifibre potential measurement, that systemic administration of tadalafil reduces mechanosensitive afferent activities of both Aδ- and C-fibres elicited by bladder distension in the rat, and also that tadalafil has an inhibitory effect on the increased activities of both fibres induced by intravesical acrolein instillation.

Oral glutamine attenuates cyclophosphamide-induced oxidative stress in the bladder but does not prevent hemorrhagic cystitis in rats

Cyclophosphamide (CP) is widely used in the treatment of cancer and non-malignant disease states such as rheumatoid arthritis. Hemorrhagic cystitis is a major dose-limiting side effect of CP. The incidence of this side effect is related to the dosage and can be as high as 75%. Elimination of the side effects of CP can lead to better tolerance of the drug, and a more efficient therapy can be achieved for patients in need of CP treatment. Several studies have demonstrated that oxidative stress and neutrophil infiltration play important roles in CP-induced bladder damage. Glutamine is utilized under clinical conditions for preventing chemotherapeutic drug-induced side effects, based on its ability to attenuate oxidative stress. The aim of the study is to verify whether glutamine prevents CP-induced oxidative stress and bladder damage using a rat model. Adult male rats were administered 150 mg/kg body weight of CP intraperitoneally. Glutamine pretreated rats were administered 1 g/kg body weight of glutamine orally 2 h before the administration of CP. Vehicle/glutamine-treated rats served as controls. All the rats were killed 16 h after the dose of CP/vehicle. The urinary bladders were removed and used for light microscopic and biochemical studies. The markers of oxidative stress including malondialdehyde content, protein carbonyl content, protein thiol, and myeloperoxidase activity, a marker of neutrophil infiltration, were measured in bladder homogenates. CP treatment induced hemorrhagic cystitis in the rats. Pretreatment with glutamine significantly reduced CP-induced lipid peroxidation (p < 0.01), protein oxidation (p < 0.01), and increase in myeloperoxidase activity (p < 0.05). However, it did not prevent CP-induced bladder damage. The results of the present study show that glutamine pretreatment does not attenuate CP-induced hemorrhagic cystitis, although it prevents CP-induced oxidative stress and neutrophil infiltration significantly. It is therefore necessary to clarify the utility of glutamine as a chemoprotective agent before it is recommended in the market as a nutrient supplement.

Protective effect of aminoguanidine against cyclophosphamide-induced oxidative stress and renal damage in rats

BACKGROUND

Cyclophosphamide (CP) is widely used in the treatment of tumors and B-cell malignant disease, such as lymphoma, myeloma, chronic lymphocytic leukemia, and Waldenstrom's macroglobulinemia. Renal damage is one of the dose-limiting side effects of CP. Oxidative stress is reported to play important roles in CP-induced renal damage.

AIM

To find out whether aminoguanidine (AG) protects against CP-induced oxidative stress and renal damage.

METHOD

Renal damage was induced in the rats by administration of a single injection of CP at a dose of 150 mg/kg body weight intraperitoneally. For the AG pretreatment studies, the rats were injected intraperitoneally with AG at a dose of 200 mg/kg body weight 1 hour before administration of CP. The control rats received AG or saline alone. All the rats were killed 16 hours after the administration of CP or saline. The kidneys were used for histological examination by light microscopy and biochemical assays--malondialdehyde, protein carbonyl content, reduced glutathione (GSH), and the activities of antioxidant enzymes including glutathione peroxidase (GPx), glutathione S transferase (GSTase), catalase, glutathione reductase, and myeloperoxidase (MPO), a marker of neutrophil infiltration.

RESULTS

Pretreatment with AG attenuated CP-induced renal damage histologically. Pretreatment with AG prevented CP-induced lipid peroxidation, protein oxidation, depletion of reduced GSH, and loss of activities of the antioxidant enzymes including GPx, catalase, and GSTase and also MPO activity.

CONCLUSION

The results of the present study reveal that AG can prevent CP-induced renal damage by inhibiting oxidative stress. Thus, AG may be useful for prevention of the nephrotoxicity of CP.

Aminoguanidine, a selective nitric oxide synthase inhibitor, attenuates cyclophosphamide-induced renal damage by inhibiting protein nitration and poly(ADP-Ribose) polymerase activation

BACKGROUND

Cyclophosphamide (CP) is an antineoplastic agent that is used for the treatment of many neoplastic diseases. Renal damage is one of the dose-limiting side effects of CP. Recent studies show that nitrosative stress plays an important role in CP-induced renal damage.

AIM

The purpose of our study was to investigate whether aminoguanidine (AG), a selective inducible nitric oxide synthase inhibitor, protects against CP-induced nitrosative stress and renal damage.

METHOD

Renal damage was induced in rats by administration of a single injection of CP at a dose of 150 mg/kg body weight intraperitoneally. For the AG pretreatment studies, the rats were injected intraperitoneally with AG at a dose of 200 mg/kg body weight 1 h before administration of CP. The control rats received AG or saline alone. All the rats were killed 16 h after the administration of CP or saline. Pretreatment with AG prevented CP-induced nitration of protein tyrosine and poly(ADP-ribose) polymerase (PARP) activation.

RESULT

Pretreatment with AG attenuated CP-induced renal damage. The present study demonstrates that AG is effective in preventing CP-induced renal damage and also that the protective effect is from its ability to inhibit nitric oxide-induced protein nitration and PARP activation.

CONCLUSION

The present study shows that AG can prevent CP-induced renal damage by inhibiting protein tyrosine nitration and PARP activation. Thus, a more efficient and comfortable therapy can be achieved for patients in need of CP treatment. AG appears to be a promising drug for the prevention of nephrotoxicity of CP.

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.

Expression of nitric oxide synthase and aquaporin-3 in cyclophosphamide treated rat bladder

PURPOSE

The expression of Nitric oxide Synthase (NOS) and aquaporin (AQP) water channels in rat bladder is recently reported. The aim of this study is to evaluate the expression of inducible NOS (iNOS), aquaporin-3 (AQP-3) in cyclophosphamide (CYP) induced rat bladder.

MATERIALS AND METHODS

The 32 Sprague-Dawley rats were divided into cystitis group (n=20) and control group (n=12). In cystitis group, 100mg/kg CYP was injected every second day for 1 week whereas in control group, normal saline was injected. After extracting of the bladder and dividing dome, body and trigone of the bladder, independently H&E staining and immunohistochemical staining for iNOS and AQP-3 were performed. Expressions of iNOS and AQP-3 were analyzed with a confocal laser scanning microscope and an image analyzer.

RESULTS

The expression of iNOS significantly increased in the mucosa, submucosa layer of dome in cystitis group (p<0.05). The expression of AQP-3 significantly increased in the mucosa, submucosa, vessel layer of dome in cystitis group (p<0.05).

CONCLUSIONS

These results suggest that inflammatory change activates NOS and AQP-3 expression in the bladder tissue of rats. These may imply that NOS and AQP-3 have a pathophyiological role in the cyclophophamide induced interstitial cystitis. Further study on the NOS and AQP-3 in bladder is needed for clinical application.

O-GlcNAc mediated glycosylation down-regulation in mice with cyclophosphamide induced cystitis

PURPOSE

Cyclophosphamide induced cystitis is an established model for the study of bladder injury and wound healing. Glycosylation is an important modification mechanism that regulates the structure and function of secreted proteins and growth factors from inflammation sites. We determined the effect of cyclophosphamide induced cystitis on O-GlcNAc mediated glycosylation in the bladder.

MATERIALS AND METHODS

Cystitis in WT C57BL6 mice was induced with intraperitoneal cyclophosphamide. Retrieved bladders were analyzed using histology, immunohistochemistry, reverse transcriptase-polymerase chain reaction and Western blot for glycosylation associated factors.

RESULTS

Acute bladder injury was seen up to 168 hours (7 days) after injection. Reverse transcriptase-polymerase chain reaction revealed down-regulation of O-GlcNAc transferase, a key enzyme in O-GlcNAc mediated glycosylation, at the 8, 48 and 168-hour time points. Also, the glycosidase menangioma expressed antigen 5 was up-regulated at similar time points. Western blot analysis revealed decreased glycosylated protein during cyclophosphamide induced inflammation.

CONCLUSIONS

To our knowledge we report the first study of alterations in O-GlcNAc mediated glycosylation activity in bladders with cyclophosphamide induced cystitis. Glycosylation may have a significant role in the bladder wound healing process. Future studies of the glycosylation signaling pathways in the bladder would assist in future potential therapy for bladder inflammatory disease and cancer by elucidating pathways that guide bladder development and wound healing.

Cystitis increases colorectal afferent sensitivity in the mouse

Studies in humans and rodents suggest that colon inflammation promotes urinary bladder hypersensitivity and, conversely, that cystitis contributes to colon hypersensitivity, events referred to as cross-organ sensitization. To investigate a potential peripheral mechanism, we examined whether cystitis alters the sensitivity of pelvic nerve colorectal afferents. Male C57BL/6 mice were treated with cyclophosphamide (CYP) or saline, and the mechanosensitive properties of single afferent fibers innervating the colorectum were studied with an in vitro preparation. In addition, mechanosensitive receptive endings were exposed to an inflammatory soup (IS) to study sensitization. Urinary bladder mechanosensitive afferents were also tested. We found that baseline responses of stretch-sensitive colorectal afferents did not differ between treatment groups. Whereas IS excited a proportion of colorectal afferents CYP treatment did not alter the magnitude of this response. However, the number of stretch-sensitive fibers excited by IS was increased relative to saline-treated mice. Responses to IS were not altered by CYP treatment, but the proportion of IS-responsive fibers was increased relative to saline-treated mice. In bladder, IS application increased responses of muscular afferents to stretch, although no differences were detected between saline- and CYP-treated mice. In contrast, their chemosensitivity to IS was decreased in the CYP-treated group. Histological examination revealed no changes in colorectum and modest edema and infiltration in the urinary bladder of CYP-treated mice. In conclusion, CYP treatment increased mechanical sensitivity of colorectal muscular afferents and increased the proportion of chemosensitive colorectal afferents. These data support a peripheral contribution to cross-organ sensitization of pelvic organs.

Nitrosative stress, protein tyrosine nitration, PARP activation and NAD depletion in the kidneys of rats after single dose of cyclophosphamide

OBJECTIVES

Cyclophosphamide (CP) and its structural analogue ifosfamide are highly effective cytostatic drugs. While both cyclophosphamide and ifosfamide have severe urotoxic side effects, only ifosfamide is thought to be nephrotoxic. The nephrotoxicity of CP in generally overlooked because of normal plasma creatinine levels. Therefore, little information is available regarding the pathogenic mechanism of renal damage by CP. In the present study, we investigated the role of nitrosative stress in CP-induced renal damage.

METHODS

The experimental rats received a single i.p. of 150 mg/kg body weight CP in saline and were killed 6 h or 16 h later. The control rats received saline. The kidneys were used for histological and biochemical analysis. Nitrotyrosine and poly (ADP-ribose) polymerase (PARP) were localized immunohistochemically as indicators of protein nitration and DNA damage, respectively. Nitrite, NAD and superoxide dismutase (SOD) activity were assayed in the kidney homogenates.

RESULTS

The nitrite level in the kidneys of CP-treated rats was elevated twofold. The kidneys of CP-treated rats stained strongly for nitrotyrosine as well as for PARP. Significant decrease in oxidized NAD levels was also observed in the kidneys of CP-treated rats. The activity of the peroxynitrite sensitive enzyme SOD was significantly reduced in the kidneys of CP-treated rats.

CONCLUSION

The results of the present study reveal that nitrosative stress may play an important role in CP-induced renal damage. It is suggested that protein nitration, PARP activation and NAD +/- depletion may play a critical role in the pathogenesis of cyclophosphamide induced renal damage.

Aminoguanidine, selective nitric oxide synthase inhibitor, ameliorates cyclophosphamide-induced hemorrhagic cystitis by inhibiting protein nitration and PARS activation

OBJECTIVES

To elucidate the mechanism by which aminoguanidine (AG) protects against cyclophosphamide (CP)-induced hemorrhagic cystitis.

METHODS

Hemorrhagic cystitis was induced in the rats by administration of a single injection of CP at a dose of 150 mg/kg body weight intraperitoneally. For the AG pretreatment studies, the rats were injected intraperitoneally with AG at a dose of 200 mg/kg body weight 1 hour before administration of CP. The control rats received AG or saline alone. All the rats were killed 16 hours after the administration of CP or saline.

RESULTS

Pretreatment with AG ameliorated CP-induced bladder damage. Pretreatment with AG prevented CP-induced elevation in nitrate levels, nitration of protein tyrosine, poly (adenosine diphosphate ribose) polymerase (PARP) activation, and restored the activity of superoxide dismutase, the peroxynitrite-sensitive enzyme. The results of the present study have confirmed that AG is effective in preventing CP-induced cystitis and have also demonstrated that the protective effect is from its ability to inhibit nitric oxide-induced protein nitration and poly (adenosine diphosphate ribose) polymerase activation.

CONCLUSIONS

AG can prevent CP-induced urotoxicity and lead to better tolerance of the drug. Thus, a more efficient and comfortable therapy can be achieved for patients in need of CP treatment. AG appears to be a promising drug for the prevention of the urotoxicity of CP.

Protein nitration, PARP activation and NAD+ depletion may play a critical role in the pathogenesis of cyclophosphamide-induced hemorrhagic cystitis in the rat

OBJECTIVES

Hemorrhagic cystitis (HC) is a major dose-limiting side effect of cyclophosphamide (CP). The mechanism by which CP induces cystitis is not clear. Recent studies demonstrate that nitric oxide; (peroxynitrite) is involved in bladder damage caused by CP. However, the molecular targets of peroxynitrite are not known. The present study is aimed at investigating whether proteins and DNA are molecular targets of peroxynitrite using a rat model.

METHODS

The experimental rats received a single i.p. injection of 150 mg kg(-1) body weight CP in saline and killed 6 or 16 h later. The control rats received saline. The bladders were used for histological and biochemical analysis. Nitrotyrosine and poly-(ADP-ribose) polymerase (PARP) were localized immunohistochemically as indicators of protein nitration and DNA damage, respectively. Nitrite, malondialdehyde, protein thiol and superoxide dismutase (SOD) activity were assayed in the bladder.

RESULTS

Hematuria and urinary bladder edema was observed in the CP-treated rats and histologically, moderate to severe damage to the urinary bladder was observed. The bladders of CP-treated rats stained strongly for nitrotyrosine as well as for PARP. Significant decrease in oxidized NAD levels was observed in the bladders of CP-treated rats 16 h following treatment with CP. Protein thiol was depleted and the activity of the peroxynitrite sensitive enzyme SOD was significantly reduced in the bladders of CP-treated rats.

CONCLUSION

The results of the present study reveal that protein nitration, PARP activation and NAD+ depletion may play a critical role in the pathogenesis of CP-induced hemorrhagic cystitis. Based on the results we propose a mechanism for CP-induced cystitis.

Sensitization of pelvic afferent nerves in the in vitro rat urinary bladder-pelvic nerve preparation by purinergic agonists and cyclophosphamide pretreatment

Effects of purinergic agonists (alpha,beta-meATP and ATP) and cyclophosphamide-induced cystitis on bladder afferent nerve (BAN) activity were studied in an in vitro bladder-pelvic nerve preparation. Distension of the bladder induced spontaneous bladder contractions that were accompanied by multiunit afferent firing. Intravesical administration of 40 and 130 microM alpha,beta-meATP increased afferent firing from 27 +/- 3 to 53 +/- 6 and 61 +/- 2 spikes/s, respectively, but did not change the maximum amplitude of spontaneous bladder contractions. Electrical stimulation on the surface of the bladder elicited action potentials (AP) in BAN. alpha,beta-meATP decreased the voltage threshold from 9.0 +/- 1.2 to 3.5 +/- 0.5 V (0.15-ms pulse duration) and increased the area of the APs (82% at 80-V stimulus intensity). These effects were blocked by TNP-ATP (30 microM). ATP (2 mM) applied in the bath produced similar changes in BAN activity. These effects were blocked by bath application of PPADS (30 microM). Neither TNP-ATP nor PPADS affected BAN activity induced by distension of the bladder. Cystitis induced by pretreatment of the rats with cyclophosphamide (100 mg/kg ip) increased afferent firing in response to isotonic bladder distension (10-40 cmH(2)O), decreased the threshold, and increased the area of evoked APs. The increase in afferent firing at 10 cmH(2)O intravesical pressure was reduced 52% by PPADS. These results indicate that purinergic agonists acting on P2X receptors and cystitis induced by cyclophosphamide can increase excitability of the BANs.

Effect of phosphodiesterase type 4 inhibitor rolipram on cyclophosphamide-induced cystitis in rats

Cyclophosphamide induces a severe haemorrhagic cystitis characterized by bladder overactivity. The study was conducted to examine effects of a phosphodiesterase 4 (PDE4) inhibitor rolipram on bladder overactivity in rats with cyclophosphamide treatment. 42 female Wistar rats were used. 30 rats received a single i.p. injection of cyclophosphamide, and after 72 h, bladder function was evaluated by (1) in vitro preparations of whole bladders and (2) cystometry with continuous saline infusion under urethane anesthesia. Cyclophosphamide-treatment dramatically potentiated the basal spontaneous contractions of isolated whole bladders compared to control rats. Atropine, guanethidine or suramin was ineffective on the spontaneous contractions whereas nifedipine completely abolished. Rolipram (5-80 microM) induced a significant concentration-dependent decrease on the amplitude, frequency (contractions/min) and area under the curve of spontaneous contractions. Carbachol elicited phasic contractions superimposed on a tonic contraction. Rolipram caused a relaxation on the tonic contraction whereas it could not affect the phasic contractions induced by carbachol. In anesthetized rats, during continuous infusion cystometry, intercontraction interval was significantly shorter in cyclophosphamide-injected rats than in control rats. Rolipram at 5-40 microM has no significant effect on the intercontraction interval and contraction pressure while it significantly decreased pressure threshold. At 80 microM, it significantly decreased the intercontraction interval and contraction pressure. In conclusion, PDE4 inhibitor rolipram caused a significant decrease on the amplitude, frequency and area under the curve of basal spontaneous contractions in cyclophosphamide-treated rats, at doses that have no effect on the carbachol-induced phasic contractions and cystometric parameters. PDE4 inhibitors may be considered as an attractive strategy for the treatment of cyclophosphamide-induced bladder overactivity.

Increased glutathione levels and activity of PON1 (phenyl acetate esterase) in the liver of rats after a single dose of cyclophosphamide: a defense mechanism?

The clinical utility of cyclophosphamide (CYP) as an anticancer drug is limited by its urotoxicity and nephrotoxicity and to a lesser extent by its hepatotoxicity. The present study was undertaken in order to find out the reason why liver is least susceptible of the three organs to CYP-induced damage although it is the major site for drug activation and metabolism. Adult female Wistar rats weighing 200-250 g were administered single intraperitoneal injection of CYP at the dose of 150 mg/kg body weight and sacrificed at various time intervals 6, 16 or 24h after the dose of CYP. The control rats were administered saline alone. Hepatotoxicity was assessed by measuring plasma alanine aminotransferase (ALT) activity and histopathology of the liver. Liver was used for the assay of reduced glutathione; activity of paraoxonase (PON1) malondialdehyde - marker of lipid peroxidation. Serum was used for the assay of ALT activity and PON1 activity. The level of reduced glutathione in the liver CYP treated rat was increased by 22% and 57% at 16 and 24h, respectively. Interestingly, a marked increase in the activity of PON1 (122%) was observed in the livers of CYP treated rats 24h after treatment. This was accompanied by significant increase in PON1 activity (23%) in the serum. No significant alteration in hepatic malondialdehyde level was observed at any time period after treatment. Serum ALT activity was increased slightly 24h after treatment with CYP. Mild liver damage was observed histologically only 24h after treatment with the drug. The present investigation shows for the first time that an increase in antioxidant levels in the liver may be a defense mechanism to prevent/minimize CYP-induced liver damage.

Changes in muscarinic receptors in the toad urothelial cell line TBM-54 following acrolein treatment

1. In cyclophosphamide-induced cystitis in the rat, cholinergic function of the bladder and muscarinic receptor expression are altered. In the present study, we investigated whether the toad urothelial cell line TBM-54 expresses functional muscarinic receptors and whether changes in muscarinic receptors can be induced in vitro by treating cells with acrolein, a metabolite of cyclophosphamide causing cystitis. 2. The occurrence of muscarinic receptors on cells was assessed by microphysiometry, a method analysing receptor function by measuring changes in the extracellular acidity rate (ECAR) in response to receptor stimulation. 3. Challenging untreated cells with the muscarinic receptor agonist carbachol gave rise to a concentration-dependent increase in changes in ECAR, with a maximal response at 1 mmol/L carbachol of 51 +/- 6%. Pre-incubating cells with different muscarinic receptor antagonists (i.e. pirenzepine (M(1) receptor selective), methoctramine (M(2)/M(4) receptor selective) and 4-diphenylacetoxy-N-methylpiperidine methobromide (4-DAMP; M(3)/M(1)/M(5) receptor selective)), gave rise to a concentration-dependent decrease in the effects of carbachol (0.5 mmol/L) on changes in ECAR. 4. Western blot analysis was used to determine the expression of all muscarinic receptor subtypes (M(1)-M(5)) by the cell line. Following acrolein treatment, cells were markedly less sensitive to carbachol and the expression of muscarinic M(2) receptors was decreased, whereas the expression of muscarinic M(3) receptors was increased. 5. In conclusion, the urothelial cell line TBM-54 expresses functional muscarinic receptors and exposure to acrolein leads to a modulation in the expression of muscarinic receptors. Consequently, acrolein may have direct effects on muscarinic receptor function and expression that contribute to the pathogenesis of cyclophosphamide-induced cystitis.

Potentiation of pulmonary reflex response to capsaicin 24h following whole-body acrolein exposure is mediated by TRPV1

Pulmonary C-fibers are stimulated by irritant air pollutants producing apnea, bronchospasm, and decrease in HR. Chemoreflex responses resulting from C-fiber activation are sometimes mediated by TRPV1 and release of substance P. While acrolein has been shown to stimulate C-fibers, the persistence of acrolein effects and the role of C-fibers in these responses are unknown. These experiments were designed to determine the effects of whole-body acrolein exposure and pulmonary chemoreflex response post-acrolein. Rats were exposed to either air or 3 ppm acrolein for 3 h while ventilatory function and HR were measured; 1-day later response to capsaicin challenge was measured in anesthetized rats. Rats experienced apnea and decrease in HR upon exposure to acrolein, which was not affected by either TRPV1 antagonist or NK(1)R antagonist pretreatment. Twenty-four hours later, capsaicin caused apnea and bronchoconstriction in control rats, which was potentiated in rats exposed to acrolein. Pretreatment with TRPV1 antagonist or NK(1)R antagonist prevented potentiation of apneic response and bronchoconstriction 24h post-exposure. These data suggest that although potentiation of pulmonary chemoreflex response 24h post-acrolein is mediated by TRPV1 and release of substance P, cardiopulmonary inhibition during whole-body acrolein exposure is mediated through other mechanisms.

The Influence of Alpha1-Adrenoreceptors on Neuropeptide Release from Primary Sensory Neurons of the Lower Urinary Tract

OBJECTIVES

Adrenergic alpha(1)-receptors agonists and antagonists have been reported to increase and reduce, respectively, neurogenic inflammatory responses mediated by capsaicin-sensitive sensory neurons. However, the precise role and localization of the alpha(1)-adrenoceptors involved in these effects are not known.

METHODS

We have studied in the rat whether functional alpha(1)-adrenoreceptors are expressed in primary sensory neurons, and whether they regulate neurogenic inflammation and nociceptive responses in the urinary bladder.

RESULTS

The alpha(1)-adrenoreceptor agonist phenylephrine (1 micromol/l) (1) mobilized intracellular Ca(2+) in cultured lumbar and sacral dorsal root ganglia neurons, (2) caused the release of substance P (SP) from terminals of capsaicin-sensitive sensory neurons from the lumbar enlargement of the dorsal spinal cord and urinary bladder, and (3) increased plasma protein extravasation in the urinary bladder. All these effects were abolished by the alpha(1)-adrenoceptor antagonist alfuzosin (10 micromol/l). Furthermore, alfuzosin (30 microg/kg, i.v.) partially, but significantly, inhibited cyclophosphamide-induced plasma protein extravasation in the rat urinary bladder. Phenylephrine-induced Ca(2+) mobilization in cultured dorsal root ganglia neurons was exaggerated by pretreating the rats in vivo with cyclophosphamide. Finally, cyclophosphamide increased c-fos expression in the rat lumbar spinal cord. Also these in vitro and in vivo effects were inhibited by pretreatment with alfuzosin.

CONCLUSIONS

Alpha(1)-adrenoceptors are functionally expressed by capsaicin-sensitive, nociceptive, primary sensory neurons of the rat urinary tract, and their activation may contribute to signal irritative and nociceptive responses arising from the urinary tract. It is possible that, at least, part of the beneficial effects of alpha(1)-adrenoceptor antagonists in the amelioration of storage symptoms in the lower urinary tract derives from their inhibitory effect on neurogenic inflammatory responses.

Exogenous overexpression of nerve growth factor in the urinary bladder produces bladder overactivity and altered micturition circuitry in the lumbosacral spinal cord

BACKGROUND

Exogenous NGF or saline was delivered to the detrusor smooth muscle of female rats for a two-week period using osmotic mini-pumps. We then determined: (1) bladder function using conscious cystometry; (2) organization of micturition reflexes using Fos protein expression in lumbosacral (L5-S1) spinal cord neurons; (3) calcitonin gene-related peptide (CGRP)-immunoreactivity (IR) in lumbosacral spinal cord segments.

METHODS

An osmotic pump infused 0.9% NaCl (n = 6) or NGF (n = 6)(2.5 microg/microl solution; 0.5 microl/hr) for two weeks into the bladder wall. NGF bladder content was determined by enzyme-linked immunoassays. Bladder function was assessed with conscious cystometry. Immunohistochemical and imaging techniques were used to determine the distribution of Fos-IR cells and CGRP expression in the L5-S1 spinal cord in saline and NGF-treated rats two hours after intravesical saline distention. Fos expression and CGRP-IR in NGF-treated rats with bladder distention was compared to that observed in cyclophosphamide (CYP; 75 mg/kg; i.p.) treated rats with bladder distention.

RESULTS

Two-week infusion of NGF into the bladder wall increased bladder weight, reduced bladder capacity (60%), reduced the intercontraction interval (60%) and increased the amplitude of non-voiding contractions. NGF treatment and intravesical saline distention (2 hr) increased expression of Fos protein in L6-S1 spinal cord and altered the distribution pattern of Fos-IR cells. CGRP-IR in the lumbosacral spinal cord was also increased after NGF treatment.

CONCLUSION

These data suggest that NGF infusion into the bladder wall induces bladder overactivity, can reveal a "nociceptive" Fos expression pattern in the spinal cord in response to a non-noxious bladder stimulus and increases CGRP-IR in the lumbosacral spinal cord.

Effect of cyclophosphamide treatment on selected lysosomal enzymes in the kidney of rats

The anti-cancer drug cyclophosphamide (CYP) is nephrotoxic besides being urotoxic thereby limiting its clinical utility. Since the nephrotoxicity of CYP is less common compared to its urotoxicity, not much importance has been given for the study of mechanism of CYP-induced nephrotoxicity. The aim of the present study is to investigate the possible role of lysosomal enzymes in CYP-induced renal damage. Adult female Wistar rats weighing 200-250 g were used for the study. The rats were administered single-intraperitoneal injection of CYP at the dose of 150 mg/kg body wt and sacrificed at various time intervals 6, 16 or 24 h after the dose of CYP. The control rats were administered saline alone. Nephrotoxicity was assessed by measuring plasma creatinine and urea and histopathology of the kidney. The kidney was weighed and used for the assay of lysosomal enzymes namely acid phosphatase, beta-glucuronidase and N-acetylglucosaminidase and total protein content. Histologically, the CYP-treated rat kidneys showed progressive renal damage with increase in time after treatment. Glomerular nephritis, cortical tubular vacuolization and interstitial edema were observed in the CYP-treated rats. Surprisingly, a significant drastic decrease (instead of an increase) in the activities of lysosomal enzymes was observed in the kidneys of CYP-treated rats at 16 and 24 h as compared with the control. A highly significant increase (270%) in protein content was observed in the kidneys of the CYP-treated rats as compared with the control. Decrease in the activities of lysosomal protein digestive enzymes may contribute to CYP-induced renal damage. The accumulation of abnormal amounts of the protein in the kidney may be due at least in part to defect in lysosomal enzyme activity and contribute to renal damage.

Cyclophosphamide Induced Cystitis: Role of Nitric Oxide Synthase, Cyclooxygenase-1 and 2, and NK1Receptors

PURPOSE

The role of substance P, inducible nitric oxide synthase, and cyclooxygenase-1 and 2 on the pathogenesis of cyclophosphamide induced cystitis was investigated in rats.

MATERIALS AND METHODS

Sprague-Dawley male rats received 1 of certain treatments, including 1) 0.9 weight per volume saline (0.10 ml/100 gm intraperitoneally), 2) cyclophosphamide (75 mg/kg intraperitoneally), 3) cyclophosphamide plus the NK(1) receptor antagonist Win-51.708 (20 mg/kg intraperitoneally), 4) cyclophosphamide plus the inducible nitric oxide synthase inhibitor S-methylthiourea (20 mg/kg intraperitoneally), 5) cyclophosphamide plus the highly selective cyclooxygenase-2 inhibitor rofecoxib (15 mg/kg intraperitoneally), 6) cyclophosphamide plus the selective cyclooxygenase-2 inhibitor meloxicam (15 mg/kg intraperitoneally), 7) cyclophosphamide plus the nonselective cyclooxygenase inhibitor ketoprofen (20 mg/kg intraperitoneally) or 8) cyclophosphamide plus methylthiourea plus meloxicam. Parameters were evaluated 6 hours after cyclophosphamide administration, including plasma protein extravasation, histological changes, myeloperoxidase and inducible nitric oxide synthase activities in the bladder, plasmatic nitric oxide metabolites and urinary nitric oxide metabolites, and prostaglandin E(2) levels.

RESULTS

Cyclophosphamide produced inflammatory and cytotoxic changes in the bladder, accompanied by increased nitric oxide metabolites, urinary prostaglandins, myeloperoxidase and inducible nitric oxide synthase activity. Pretreatment with Win-51.708 and with methylthiourea prevented all of these effects except myeloperoxidase activity, which was only prevented by Win-51.708. All inducible cyclooxygenases were able to prevent prostaglandin synthesis and increases in myeloperoxidase activity. Combined inhibition of inducible nitric oxide synthase and cyclooxygenase-2/cyclooxygenase-1 (methylthiourea plus meloxicam) did not provide any additional protection against bladder damage, increased inducible nitric oxide synthase activity or prostaglandin E(2) synthesis. Additionally, this combination was unable to prevent increased myeloperoxidase activity.

CONCLUSIONS

The results of this study suggest that there is crosstalk between nitric oxide and the cyclooxygenase enzyme with cyclooxygenase-1/cyclooxygenase-2 isoforms having an important role in this relationship. Augmented myeloperoxidase activity seems to be associated with NK(1) receptor activation and low levels of nitric oxide with cyclooxygenase-1 having an important role.

Effects of intravesical instillation of cyclooxygenase-2 inhibitor on the expression of inducible nitric oxide synthase and nerve growth factor in cyclophosphamide-induced overactive bladder

OBJECTIVE

To examine the effects of intravesical cyclooxygenase-2 (COX-2) inhibitors on the expression of inducible nitric oxide synthase (iNOS) and nerve growth factor (NGF) in cyclophosphamide (CYP)-induced overactive bladder (OAB).

MATERIALS AND METHODS

In all, 40 Sprague-Dawley rats were divided into control, OAB, and COX-2 inhibitor-treated groups. OAB was induced by an intraperitoneal injection with CYP. Cystometry was performed in all rats and, in half of the OAB rats, a COX-2 inhibitor was administered intravesically. The bladders of all rats were stained immunohistochemically for iNOS and NGF.

RESULTS

In the OAB rats, the contraction interval and intercontraction interval were significantly shorter than in control rats, and the contraction time and pressure were significantly greater. In the COX-2 inhibitor-treated rats, the contraction interval and intercontraction interval were significantly longer than in the OAB rats, and the contraction time was significantly shorter. On immunohistochemical staining, there was no iNOS activity and NGF activity was minimally localized in the mucosa and submucosa in the control group. In the OAB rats, NGF activity in the mucosa and submucosa were increased, and there was greater expression of iNOS in all layers and of NGF in detrusor; in the COX-2 inhibitor-treated rats, their expression was less in all layers.

CONCLUSIONS

Intravesical instillation with COX-2 inhibitors can reduce CYP-induced bladder hyperactivity and expression of iNOS and NGF. Intravesical instillation with COX-2 inhibitors can be considered as a possible treatment for OAB.

TRPA1 mediates the inflammatory actions of environmental irritants and proalgesic agents

TRPA1 is an excitatory ion channel targeted by pungent irritants from mustard and garlic. TRPA1 has been proposed to function in diverse sensory processes, including thermal (cold) nociception, hearing, and inflammatory pain. Using TRPA1-deficient mice, we now show that this channel is the sole target through which mustard oil and garlic activate primary afferent nociceptors to produce inflammatory pain. TRPA1 is also targeted by environmental irritants, such as acrolein, that account for toxic and inflammatory actions of tear gas, vehicle exhaust, and metabolic byproducts of chemotherapeutic agents. TRPA1-deficient mice display normal cold sensitivity and unimpaired auditory function, suggesting that this channel is not required for the initial detection of noxious cold or sound. However, TRPA1-deficient mice exhibit pronounced deficits in bradykinin-evoked nociceptor excitation and pain hypersensitivity. Thus, TRPA1 is an important component of the transduction machinery through which environmental irritants and endogenous proalgesic agents depolarize nociceptors to elicit inflammatory pain.

Anandamide-evoked activation of vanilloid receptor 1 contributes to the development of bladder hyperreflexia and nociceptive transmission to spinal dorsal horn neurons in cystitis

The role of anandamide in the development of inflammatory hyperalgesia and visceral hyperreflexia was studied in the rat urinary bladder. Animals were given intraperitoneal cyclophosphamide injection, which evokes painful hemorrhagic cystitis accompanied by increased bladder reflex activity. The vanilloid receptor 1 [transient receptor potential vanilloid 1 (TRPV1)] antagonist capsazepine, applied onto the serosal surface of bladders, significantly reduced the hyperreflexia. Mass spectrometric analysis revealed that cyclophosphamide injection significantly and persistently increased the anandamide content of bladder tissues. The increase in the anandamide content paralleled the development of reflex hyperactivity. Anandamide (1-100 microm), applied onto the serosal surface of naive bladders, increased the reflex activity in a concentration-dependent manner. Repeated anandamide applications did not produce desensitization of the response. The anandamide-evoked effect was blocked by capsazepine or by instillation of resiniferatoxin, the ultrapotent TRPV1 agonist, into the bladders 24 hr before the anandamide challenge. The cannabinoid 1 receptor antagonist SR141716A [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide] significantly increased the potency of anandamide in enhancing bladder reflex activity in naive but not in cyclophosphamide-injected animals. Application of the fatty acid amide hydrolyze inhibitor palmitoylisopropylamine onto the serosal surface of bladders also increased the reflex activity both in naive and cyclophosphamide-injected rats. This latter effect in naive animals was blocked by capsazepine and by resiniferatoxin pretreatment. Finally, intravesical instillation of anandamide (50 microm) increased c-fos expression in the spinal cord, which was reduced by capsazepine or by resiniferatoxin pretreatment. These results suggest that anandamide, through activating TRPV1, contributes to the development of hyperreflexia and hyperalgesia during cystitis.

Protective effect of taurine against cyclophosphamide-induced urinary bladder toxicity in rats

1. In the present study, the effect of taurine, on cyclophosphamide (CP)-induced urinary bladder toxicity was investigated. 2. Administration of a single dose of CP (150 mg/kg, i.p.) induced cystitis, as manifested by marked congestion, oedema and extravasation in rat urinary bladder, as well as a marked desquamative damage to the urothium, severe inflammation in the lamina propria, focal erosions and polymorphonuclear leucocytes associated with occasional lymphocyte infiltration as determined by macroscopic and histopathological examination. 3. A significant decrease in the endogenous anti-oxidant compound glutathione and elevation of lipid peroxidation also resulted in rat urinary bladder tissue. 4. Cyclophosphamide-induced cystitis markedly affected the contractile function of the urinary bladder, as revealed by a significant inhibition of tissue responsiveness to acetylcholine (ACh) at different molar concentrations in vitro. 5. Conversely, pretreatment with taurine (1% in drinking water to reach a dose of 1 g/kg per day) for 7 days before and 1 day after CP injection produced a significant decrease in urinary bladder weight (oedema) and a marked decrease in vascular congestion and haemorrhage, as well as a profound improvement in histological structure. Moreover, taurine pretreatment resulted in a significant decrease in lipid peroxide in urinary bladder tissue and glutathione content was greatly restored. 6. Urinary bladder rings isolated from rats treated concurrently with taurine and CP showed a significant increase in their responsiveness to ACh compared with the CP group. 7. These results suggest that taurine offers a protective effect against CP-induced urinary bladder toxicity and may, therefore, decrease the limitation on its clinical application. These results merit extension and further investigation of the impact of taurine on CP antitumour activity.

Expression and function of bradykinin B1 and B2 receptors in normal and inflamed rat urinary bladder urothelium

The bladder urothelium exhibits dynamic sensory properties that adapt to changes in the local environment. These studies investigated the localization and function of bradykinin receptor subtypes B1 and B2 in the normal and inflamed (cyclophosphamide (CYP)-induced cystitis) bladder urothelium and their contribution to lower urinary tract function in the rat. Our findings indicate that the bradykinin 2 receptor (B2R) but not the bradykinin 1 receptor (B1R) is expressed in control bladder urothelium. B2R immunoreactivity was localized throughout the bladder, including the urothelium and detrusor smooth muscle. Bradykinin-evoked activation of this receptor elevated intracellular calcium (EC(50) = 8.4 nM) in a concentration-related manner and evoked ATP release from control cultured rat urothelial cells. In contrast, B1R mRNA was not detected in control rat urinary bladder; however, following acute (24 h) and chronic (8 day) CYP-induced cystitis in the rat, B1R mRNA was detected throughout the bladder. Functional B1Rs were demonstrated by evoking ATP release and increases in [Ca(2+)](i) in CYP (24 h)-treated cultured rat urothelial cells with a selective B1 receptor agonist (des-Arg(9)-bradykinin). Cystometry performed on control anaesthetized rats revealed that intravesical instillation of bradykinin activated the micturition pathway. Attenuation of this response by the P2 receptor antagonist PPADS suggests that bradykinin-induced micturition facilitation may be due in part to increased purinergic responsiveness. CYP (24 h)-treated rats demonstrated bladder hyperactivity that was significantly reduced by intravesical administration of either B1 (des-Arg(10)-Hoe-140) or B2 (Hoe-140) receptor antagonists. These studies demonstrate that urothelial expression of bradykinin receptors is plastic and is altered by pathology.

Peripheral tachykinin receptors as potential therapeutic targets in visceral diseases

More than 10 years of intensive preclinical investigation of selective tachykinin (TK) receptor antagonists has provided a rationale to the speculation that peripheral neurokinin (NK)-1, -2 and -3 receptors may be involved in the pathophysiology of various human diseases at the visceral level. In the airways, despite promising effects in animal models of asthma, pilot clinical trials with selective NK-1 or -2 receptor antagonists in asthmatics have been ambiguous, whereas the potential antitussive effects of NK-1, -2 or -3 antagonists have not yet been verified in humans. In the gastrointestinal (GI) tract, irritable bowel syndrome (IBS) and pancreatitis are appealing targets for peripherally-acting NK-1 and -2 antagonists, respectively. In the genito-urinary tract, NK-1 receptor antagonists could offer some protection against nephrotoxicity and cytotoxicity induced by chemotherapeutic agents, whereas NK-2 receptor antagonists appear to be promising new agents for the treatment of neurogenic bladder hyperreflexia. Finally, there is preclinical evidence for hypothesising an effect of NK-3 receptor antagonists on the cardiovascular disturbance that characterises pre-eclampsia. Other more speculative applications are also mentioned.

The effect of inflammation on rat urinary bladder-dependent relaxation in coaxial bioassay system

The effect of urinary bladder inflammation on the activity of a bladder-derived relaxant factor in the coaxial bioassay system was examined. Bladder inflammation was induced by intraperitoneal (i.p.) cyclophosphamide or intravesical lipopolysaccharide (LPS) injection to male rats. In precontracted rat anococcygeus muscle that was placed within rat bladder (coaxial bioassay system), acetylcholine induced a relaxation response, which was not altered by the denudation of urothelium or incubation with indomethacin and N(G)-methyl-L-arginine. Acetylcholine-induced relaxation was significantly attenuated, when bladders were removed from cyclophosphamide- and LPS-pretreated group of rats and were used with intact urothelium in the coaxial bioassay system. However, the impairment acetylcholine response in both pretreatment groups was not observed after denudation of the bladder urothelium. These results showed that bladder inflammation did not alter the synthesis and/or release of this bladder-derived relaxant factor, which is neither a cyclooxygenase product nor nitric oxide, but restricted its demonstration by coaxial bioassay assembly probably due to inflammation-induced mucosal oedema.

Neurogenic inflammation of the bladder

Current evidence suggests multiple and redundant pathways through which the nervous system can initiate, amplify, and perpetuate inflammation. Many of the processes initiated by neurogenic inflammation have the capacity to recruit the participation of additional sensory nerves. These observations indicate that effective strategies for prevention or treatment of neurogenic inflammation of the bladder will entail or require intervention at multiple points. It has been observed that pain management in the future will be based on selective intervention tailored to the specific processes modulating pain perception in individual patients. It is exciting to contemplate the same approach to prevention and treatment of neurogenic bladder inflammation.

LPS-sensory peptide communication in experimental cystitis

Stimulation of sensory nerves can lead to release of peptides such as substance P (SP) and consequently to neurogenic inflammation. We studied the role of bacterial lipopolysaccharide (LPS) in regulating SP-induced inflammation. Experimental cystitis was induced in female mice by intravesical instillation of SP, LPS, or fluorescein-labeled LPS. Uptake of fluorescein-labeled LPS was determined by confocal analysis, and bladder inflammation was determined by morphological analysis. SP was infused into the bladders of some mice 24 h after exposure to LPS. In vitro studies determined the capacity of LPS and SP to induce histamine and cytokine release by the bladder. LPS was taken up by urothelial cells and distributed systemically. Twenty-four hours after instillation of LPS or SP, bladder inflammation was characterized by edema and leukocytic infiltration of the bladder wall. LPS pretreatment enhanced neutrophil infiltration induced by SP, increased in vitro release of histamine, tumor necrosis factor-alpha, and interferon-gamma, and significantly reduced transforming growth factor-beta1 release. These findings suggest that LPS amplifies neurogenic inflammation, thereby playing a role in the pathogenesis of neurogenic cystitis.

Peripheral tachykinin receptors as targets for new drugs

Tachykinins are widely distributed in the peripheral nervous system of the respiratory, urinary and gastrointestinal tract, stored in enteric neurons and in peripheral nerve endings of capsaicin-sensitive primary afferent neurons from which are released by stimuli having both pathological and physiological relevance. The most studied effects produced by tachykinins in these systems are smooth muscle contraction, plasma protein extravasation, mucus secretion and recruitment/activation of immune cells. The use of tachykinin receptor-selective antagonists and knockout animals has enabled to identify the involvement of tachykinin NK(1), NK(2) and NK(3) receptors as mediators of peripheral effects of tachykinins in different systems/species. The bulk of data obtained in experimental animal models suggests that tachykinins could contribute to the genesis of symptoms accompanying various human diseases including asthma/bronchial hyperreactivity, cystitis of various aetiology, inflammatory bowel diseases and irritable bowel syndrome. Tachykinin receptor antagonists are expected to afford therapeutically relevant effects.

Tachykinins as modulators of the micturition reflex in the central and peripheral nervous system

In the normal urinary bladder, tachykinins (TKs) are expressed in a population of bladder nociceptors that is sensitive to the excitatory and desensitizing effects of capsaicin (i.e., capsaicin-sensitive primary afferent neurons (CSPANs)). Several endobiotics or xenobiotics excite CSPANs and release TKs and other mediators at both the peripheral and spinal cord level. The peripheral release of TKs determines a set of responses (known as neurogenic inflammation) that includes vasodilatation, plasma protein extravasation, smooth muscle contraction and stimulation of afferent nerves. Following chronic inflammation, both immune cells and capsaicin-resistant sensory neurons can de novo express TKs: whether these pools of TKs are releasable and contribute to inflammatory processes is presently unsettled. At the spinal cord level, the release of TKs contributes in determining an altered pattern of vesicourethral reflexes in response to nociceptive stimulation of the bladder by conveying: (a) the afferent transmission to supraspinal sites, and (b) descending or sensory inputs to the sacral parasympathetic nucleus (SPN). Recent evidence also attribute a synergetic role of TKs in the supraspinal modulation of the sensory arm of the micturition reflex. The overall available information suggests that TK receptor antagonists may affect bladder motility/reflexes which occur during different pathological states, while having little influence on the normal motor bladder function.

Expression of inducible nitric oxide synthase in primary culture of rat bladder smooth muscle cells by plasma from cyclophosphamide-treated rats

Intraperitoneal administration of cyclophosphamide (50-150 mg/kg) for 6 or 12 h induced edema and hemorrhagic changes in rat bladder, which were both dose and time-dependent. Pretreatment with nitric oxide synthase (NOS) inhibitors N(G)-nitro-L-arginine methyl ester (L-NAME, 40 mg/kg) or with s-methylisothiourea (40 mg/kg) ameliorated the cyclophosphamide-induced cystitis. Cyclophosphamide administration also produced increases in NO-metabolite levels (nitrate+nitrite) in the urine and plasma of rats. Greater increases in NO metabolites were observed with 150 than with 50 mg/kg of cyclophosphamide, and at 12 than at 6 h after cyclophosphamide injection. Pretreatment with L-NAME and s-methylisothiourea significantly reduced cyclophosphamide-induced increases in urine and plasma NO-metabolite levels. To explore the mechanism by which cyclophosphamide increases the expression of inducible NOS (iNOS), primary cultures of rat bladder smooth muscle were developed. Exposure to tumor necrosis factor alpha (TNF-alpha) plus interferon gamma, produced a marked increase in the expression of iNOS and in NO production in the culture medium. However, exposure to cyclophosphamide or to its metabolite acrolein (10(-6)-10(-4) M for 24 h) did not increase iNOS or NO-metabolite levels. On the other hand, incubation of primary cell cultures with plasma from rats treated with cyclophosphamide (150 mg/kg, 12 h) produced a marked increase in iNOS expression and NO production. Taken together, our results indicate that NO plays an important role in the pathogenesis of cyclophosphamide-induced cystitis in rats, and some factors may be released in cyclophosphamide-treated rat plasma which stimulate iNOS expression in primary culture of rat bladder smooth muscle cells.

Alterations in neuropeptide expression in lumbosacral bladder pathways following chronic cystitis

These studies examined changes in the expression of calcitonin gene-related peptide (CGRP) and substance P (SP) in lumbosacral (L6-S1) micturition reflex pathways, following chronic cystitis induced by cyclophosphamide (CYP). In control Wistar rats, CGRP- or SP-immunoreactivity (IR) was expressed in fibers in the superficial dorsal horn in all segmental levels examined (L4-S1). Bladder afferent cells in the dorsal root ganglia (DRG; L6, S1) from control animals also exhibited CGRP- (41-55%) or SP-IR (2-3%). Following chronic, CYP-induced cystitis, CGRP- and SP-IR were dramatically increased in spinal segments and DRG (L6, S1) involved in micturition reflexes. The density of CGRP- and SP-IR was increased in the superficial laminae (I-II) of the L6 and S1 spinal segments. No changes in CGRP- or SP-IR were observed in the L4-L5 segments. Staining was also dramatically increased in a fiber bundle extending ventrally from Lissauer's tract in lamina I along the lateral edge of the DH to the sacral parasympathetic nucleus in the L6-S1 spinal segments. Following chronic cystitis, CGRP- and SP-IR in cells in the L6 and S1 DRG significantly (P< or =0.05) increased and the percentage of bladder afferent cells expressing CGRP- (76%) or SP-IR (11-18%) also significantly (P< or =0.001) increased. No changes were observed in the L4-L5 DRG. These studies suggest that the neuropeptides, CGRP and SP, may play a role in urinary bladder afferent pathways, following chronic urinary bladder inflammation. Changes in CGRP or SP expression following cystitis may contribute to the altered visceral sensation (allodynia) and/or urinary bladder hyperreflexia in the clinical syndrome, interstitial cystitis.

Urinary levels of substance P and its metabolites are not increased in interstitial cystitis

OBJECTIVES

To determine whether interstitial cystitis is associated with the increased release of substance P from the bladder wall into urine, by measuring urinary excretion rates of substance P and its metabolites in women with interstitial cystitis and in a control group of women with stress incontinence and normal bladder function.

PATIENTS AND METHODS

Catheter urine was collected from 13 patients and 10 controls during a water diuresis ( approximately 10 mL/min) before and after instilling the bladder with 100 mL of water. The contribution of the bladder wall to urinary substance P peptides was assessed by measuring the change in substance P peptide levels after 2 min of bladder stasis before and after instillation.

RESULTS

Absolute substance P excretion rates were similar in patients with interstitial cystitis and controls; 2 min of bladder stasis reduced the substance P excretion rate (P = 0.03) and increased the excretion rate of substance P metabolites (P = 0.01).

CONCLUSIONS

The release of substance P from the bladder wall was not increased in patients with interstitial cystitis.