Cholinergic nitric oxide release from the urinary bladder mucosa in cyclophosphamide-induced cystitis of the anaesthetized rat

Monotherapy with tolterodine or mirabegron is insufficient for ameliorating cyclophosphamide-induced bladder overactivity in rats

Monotherapy continues to be the most common pharmacological treatment option for patients with overactive bladder (OAB), despite evidence indicating that it may have inferior efficacy compared to combination therapy. This seems to be especially true for patients with concomitant cystitis. The current study examined the effects of monotherapy with either the antimuscarinic tolterodine or the β3 agonist mirabegron on bladder overactivity induced by bladder inflammation. Further, the possible involvement of nitric oxide (NO) was studied. For this purpose, rats were pretreated with either drug for 10 days. Bladder inflammation was induced by intraperitoneal injection with cyclophosphamide, with saline serving as control. Micturition parameters were assessed in a metabolic cage. Meanwhile, urine samples were collected and further analysed for NO content. After 16 h, the animals were euthanized, and their bladders were excised and examined immunohistochemically for signs of inflammation. Cyclophosphamide treatment led to bladder overactivity and obvious signs of inflammation. Neither treatment with tolterodine nor mirabegron could significantly alleviate the induced overactivity or the observed inflammation. Further, while induction of inflammation led to a significant increase in NO production, neither drug seemed to act by further enhancing its production. On the contrary, treatment with either tolterodine or mirabegron significantly decreased NO production in cyclophosphamide treated rats. Considering previous findings showing significant improvement by combination therapy, the current study indirectly implies this as the superior treatment option. Further studies are needed to verify the involvement, or lack thereof, of NO in the mechanism of action of drugs used to treat OAB.

Beyond the urothelium: Interplay between autonomic nervous system and bladder inflammation in urinary tract infection, bladder pain syndrome with interstitial cystitis and neurogenic lower urinary tract dysfunction in spinal cord injury-ICI-RS 2023

INTRODUCTION

Inflammation and neuronal hypersensitivity are reactive protective mechanisms after urothelial injury. In lower urinary tract dysfunctions (LUTD), such as urinary tract infection (UTI), bladder pain syndrome with interstitial cystitis (BPS/IC) and neurogenic LUTD after spinal cord injury (SCI), chronic inflammation can develop. It is unclear how the protective reactionary inflammation escalates into chronic disease in some patients.

METHODS

During its 2023 meeting in Bristol, the International Consultation on Incontinence-Research Society (ICI-RS) reviewed the urothelial and inflammatory changes after UTI, BPS/IC and SCI. Potential factors contributing to the evolution into chronic disease were explored in a think-tank.

RESULTS

Five topics were discussed. (1) Visceral fat metabolism participates in the systemic pro-inflammatory effect of noradrenalin in BPS/IC and SCI. Sympathetic nervous system-adipocyte-bladder crosstalk needs further investigation. (2) Sympathetic hyperactivity also potentiates immune depression in SCI and needs to be investigated in BPS/IC. Gabapentin and tumor necrosis factor-α are promising research targets. (3) The exact peripheral neurons involved in the integrative protective unit formed by nervous and immune systems need to be further identified. (4) Neurotransmitter changes in SCI and BPS/IC: Neurotransmitter crosstalk needs to be considered in identifying new therapeutic targets. (5) The change from eubiosis to dysbiosis in SCI can contribute to UTI susceptibility and needs to be unraveled.

CONCLUSIONS

The think-tank discussed whether visceral fat metabolism, immune depression through sympathetic hyperactivity, peripheral nerves and neurotransmitter crosstalk, and the change in microbiome could provide explanations in the heterogenic development of chronic inflammation in LUTD. High-priority research questions were identified.

Nitric oxide signaling pathways in the normal and pathological bladder: Do they provide new pharmacological pathways?-ICI-RS 2023

AIMS

The nitric oxide (NO•)/soluble guanylate cyclase/cyclic-GMP (cGMP) signaling pathway is ubiquitous and regulates several functions in physiological systems as diverse as the vascular, nervous, and renal systems. However, its roles in determining normal and abnormal lower urinary tract functions are unclear. The aim was to identify potential therapeutic targets associated with this pathway to manage lower urinary tract functional disorders.

METHODS

This review summarizes a workshop held under the auspices of ICI-RS with a view to address these questions.

RESULTS

Four areas were addressed: NO• signaling to regulate neurotransmitter release to detrusor smooth muscle; its potential dual roles in alleviating and exacerbating inflammatory pathways; its ability to act as an antifibrotic mediator; and the control by nitrergic nerves of lower urinary tract vascular dynamics and the contractile performance of muscular regions of the bladder wall. Central to much of the discussion was the role of the NO• receptor, soluble guanylate cyclase (sGC) in regulating the generation of the enzyme product, the second messenger cGMP. The redox state of sGC is crucial in determining its enzymic activity and the role of a class of novel agents, sGC activators, to optimize activity and to potentially alleviate the consequences of lower urinary tract disorders was highlighted. In addition, the consequences of a functional relationship between nitrergic and sympathetic nerves to regulate vascular dynamics was discussed.

CONCLUSIONS

Several potential NO•-dependent drug targets in the lower urinary tract were identified that provide the basis for future research and translation to clinical trials.

Soluble guanylate cyclase mediates the relaxation of healthy and inflamed bladder smooth muscle by aqueous nitric oxide

Introduction: Due to its chemical properties, functional responses to nitric oxide (NO) are often difficult to examine. In the present study, we established a method to produce NO in an aqueous solution and validated its capacity to evoke functional responses in isolated rat bladders. Furthermore, we compared the NO responses to the commonly used NO donor sodium nitroprusside (SNP). We also investigated the impact of ongoing inflammation on the involvement of soluble guanylate cyclase (sGC) dependent signaling in NO relaxation. Methods: A setup to produce an aqueous NO solution was established, allowing the production of an aqueous solution containing a calculated NO concentration of 2 mM. Sixty male Sprague-Dawley rats received either no treatment (controls) or cyclophosphamide (CYP; 100 mg*kg-1 i.p., 60 h prior to the experiment) to induce experimental cystitis. Bladder strip preparations were mounted in organ baths and studied at basal tension or pre-contracted with methacholine (3 μM). Aqueous NO solution (40-400 μL; 2 mM corresponding to 4-40 μM) or SNP (1-1,000 μM) was added cumulatively in increasing concentrations. Relaxation to aqueous NO was also studied in the presence of the sGC inhibitor ODQ (0.25-25 μM). The expression of sGC was investigated by immunohistochemical analysis. Results: The NO solution caused functional relaxations in both controls and inflamed bladder preparations. NO-induced relaxations were significantly greater in inflamed bladder strips at basal tension, whereas no differences were seen in methacholine pre-contracted strips. In the presence of the sGC inhibitor ODQ in a high concentration, the NO-evoked relaxations were abolished in both control and inflamed preparations. At a lower concentration of ODQ, only NO relaxations in inflamed preparations were attenuated. Immunohistochemical analysis showed that sGC was expressed in the detrusor and mucosa, with a significantly lower expression in the inflamed detrusor. Conclusion: In the present study, we found that aqueous NO solution induces relaxation of the rat detrusor by activating soluble guanylate cyclase in both control and inflamed bladder strips. Induction of inflammation conceivably leads to decreased sGC expression in the detrusor, which may explain the different susceptibility towards inhibition of sGC in inflamed versus control tissue. The use of an aqueous NO solution should be further considered as a valuable complement to the pharmacological tools currently used.

Low-Dose Cyclophosphamide Induces Nerve Injury and Functional Overactivity in the Urinary Bladder of Rats

Aim: This research aimed to investigate the neurotoxicity of low-dose cyclophosphamide (CYP) on the urinary bladder of rats by in vivo and in vitro studies. Methods: To establish CYP-induced cystitis rat model, rats were treated with three intraperitoneal injections of CYP (25 mg/kg) in a week. During treatment, the up-down method was used to assess the mechanical withdrawal threshold. On day 8, urodynamic test and bladder smooth muscle contractility study, including the contraction of bladder strips to electrical field stimulation (EFS, 2-64 Hz), carbachol (CCh, 10^-8-10^-5 M) and KCl (120 mM), were performed to evaluate the function of bladder function. Body weight and bladder weight were also recorded. Morphometric analysis using an optical microscope and transmission electron microscope was performed to observe the changes of microstructure and submicrostructure of the bladder. The major pelvic neurons were isolated and treated with acrolein (the main CYP metabolite) to assess apoptosis in vitro. RT-PCR assays were used to quantify the mRNA expression levels of Nlrp6, Asc, Casp11 and Casp1 in bladder tissues and primary neurons. Results: After CYP injections, the body weights decreased, but the bladder weights increased in the model group. The mechanical withdrawal threshold of the cystitis model remained at a low level. The morphometric analysis suggested bladder inflammation and neuroinflammation in the bladder of the cystitis rat model. Urodynamic test revealed that, the amplitude, the pressure baseline, the peak pressure and pressure threshold of model rats significantly increased after CYP treatment. The muscle strips of model rats exhibited significantly higher contractility caused by EFS and CCh than the controls. Apoptotic cells appeared at the highest concentration group (100 μM acrolein) after 6 h of acrolein incubation in apoptosis assay of primary neurons. The mRNA expression levels of Nlrp6 and Casp11 were significantly increased in the cystitis rat model and in the acrolein-treated neurons. Conclusions: Low-dose CYP treatment was confirmed to induce nerve injury, which leading to bladder pain and overactive bladder in female rats, and the up-regulation of Nlrp6 and Casp11 may contribute to these pathological changes.

Cross-organ sensitization between the prostate and bladder in an experimental rat model of lipopolysaccharide (LPS)-induced chronic pelvic pain syndrome

BACKGROUND

The aim of the current study was to investigate the effects of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) on bladder function via prostate-to-bladder cross-sensitization in a rat model of lipopolysaccharide (LPS)-induced prostate inflammation.

METHODS

Male rats were intraprostatically injected with LPS or saline, serving as control. Micturition parameters were examined in a metabolic cage 10 or 14 days later. Subsequently, to evaluate bladder function, cystometry was performed. Micturition cycles were induced by saline infusion and cholinergic and purinergic contractile responses were measured by intravenous injection with methacholine and ATP, respectively. Thereafter, the prostate and bladder were excised and assessed histopathologically for possible inflammatory changes.

RESULTS

Metabolic cage experiments showed increased urinary frequency in rats with LPS-induced CP/CPPS. Cystometry showed a significant increase in the number of non-voiding contractions, longer voiding time and lower compliance in CP/CPPS animals compared to controls. Induction of CP/CPPS led to significantly reduced cholinergic and purinergic bladder contractile responses. Histopathological analysis demonstrated prostatic inflammation in CP/CPPS animals. There were no significant differences between the groups regarding the extent or the grade of bladder inflammation. Prostate weight was not significantly different between the groups.

CONCLUSIONS

The present study shows that prostate-to-bladder cross-sensitization can be triggered by an infectious focus in the prostate, giving rise to bladder overactivity and alterations in both afferent and efferent signalling. Future studies are required to fully understand the underlying mechanisms.

Allicin mitigates hepatic injury following cyclophosphamide administration via activation of Nrf2/ARE pathways and through inhibition of inflammatory and apoptotic machinery

Treatment with anti-neoplastic agents, including cyclophosphamide (CP), is associated with several adverse reactions. Here, we distinguished the potential protective effect of allicin against CP-mediated hepatotoxicity in rats. To assess the effect of allicin, four experimental groups were used, with 7 rats per group, including control, allicin (10 mg/kg), CP (200 mg/kg), and allicin + CP-treated groups. All groups were treated for 10 days. Blood and liver samples were collected for biochemical, molecular, and histological analyses. Treatment with CP led to deformations in the liver tissue that were associated with higher liver function markers (alanine transaminase, aspartate transaminase, and alkaline phosphatase). Additionally, a disturbance in the redox balance was observed after CP exposure, as indicated by increased levels of oxidants, including malondialdehyde and nitric oxide, and the decreased levels of endogenous antioxidants, including glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase, and catalase. At the molecular level, CP treatment resulted in reduced expression of the Nrf2/ARE pathway and other genes related to this pathway, including NAD(P)H quinone dehydrogenase 1 and glutamate-cysteine ligase catalytic subunit. CP also led to a hyper-inflammatory response in hepatic tissue, with increased production of pro-inflammatory cytokines, including tumor necrosis factor-alpha and interlukin-1beta, and upregulation of nitric oxide synthase 2. CP also enhanced the immunoreactivity of the profibrogenic cytokine, transforming growth factor-beta, in liver tissue. Upregulation of caspase 3 and Bcl-2-associated X protein and downregulation of B-cell lymphoma 2 were also observed in response to CP treatment. Treatment with allicin reversed the molecular, biochemical, and histological changes that occurred with CP exposure. These results suggest that allicin can be used in combination with CP to avoid hepatotoxicity.

Prostate-to-bladder cross-sensitization in a model of zymosan-induced chronic pelvic pain syndrome in rats

BACKGROUND

The aim of the present study was to investigate the effects of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) on bladder function and pathophysiology.

METHODS

To create a model for CPPS, rats were intraprostatically injected with zymosan or saline, serving as control. Metabolic cage experiments were performed 7, 14, or 21 days after zymosan injection and after 14 days in the control group. Thereafter, cystometry was performed in which simulated micturition cycles were induced by saline infusion and contractile responses to the cholinergic agonist methacholine and the purinergic agonist ATP were measured. Following cystometry, the prostate and urinary bladder were excised and assessed histopathologically for possible inflammatory changes.

RESULTS

Metabolic cage data revealed a significantly increased urinary frequency in zymosan treated rats. Likewise, the volume per micturition was significantly lower in all CPPS groups compared to controls. Cystometry showed a significant increase in the number of nonvoiding contractions, longer voiding time, and a trend towards lower compliance in CPPS rats compared to controls. Induction of CPPS led to significantly reduced cholinergic and purinergic contractile responses. Histopathological analysis demonstrated prostatic inflammation in all CPPS groups, in particular in later stage groups. Both the extent and grade of bladder inflammation were significantly higher in CPPS groups compared to controls.

CONCLUSIONS

The current findings demonstrate a potential prostate-to-bladder cross-sensitization leading to symptoms of bladder overactivity and signs of bladder inflammation. Future clinical studies are required to verify the outcomes of the current study and enable advancement of patient care.

Functional atropine sensitive purinergic responses in the healthy rat bladder

While acetylcholine is regarded to be the main directly contractile transmitter substance in the urinary bladder, interactions with other transmitters likely occur. Presently, the interplay between purinergic and cholinergic signalling was investigated to unravel the involvement of the urothelium and efferent neurons in the functionally important purinergically evoked release of acetylcholine in vitro. Functional characterization of receptor subtypes involved in this interplay was also performed. In vitro organ bath experiments with electrical field stimulation (EFS) or administration of agonist were performed in the absence and presence of the neurotoxin tetrodotoxin (TTX; 5 × 10^-7 M) and/or receptor antagonists, in intact and urothelium-denuded full thickness rat bladder strip preparations. Interestingly, functional contractions to ATP (10^-6-10^-3 M) remained unaffected by TTX, but were significantly lowered in the presence of the muscarinic antagonist atropine (10^-6 M). However, in urothelium-denuded strip preparations, this latter phenomenon was not present and the ATP response remained unaltered. To rule out purinergic interference caused by break-down of ATP, experiments were performed in which the stable ATP-analogue αβMeATP (10^-7-10^-5 M) gave rise to functional atropine-sensitive contractions. Furthermore, contractions to ATP were not affected by P2Y6 purinoceptor blockade (by MRS2578; 10^-7, 10^-5 M), nor were relaxatory responses to ATP sensitive to atropine, PPADS (3 × 10^-5 M) or αβMeATP. Lastly, relaxations to ADP (10^-6-10^-3 M) or NECA (10^-8-10^-5 M) were unaltered by the presence of atropine. To conclude, purinergic functional contractile, but not relaxatory, responses are supported by the cholinergic transmitter system in vitro, through non-neuronal mechanisms in the urothelium. Involved purinoceptors are of the P2X-subtype, most likely P2X1 and/or P2X3.

In vivo paracrine effects of ATP-induced urothelial acetylcholine in the rat urinary bladder

Mechanical stretch of the urothelium induces the release of ATP that activates bladder afferent nerves. In the rat urinary bladder, ATP is also a contractile co-transmitter in the parasympathetic innervation. In isolated preparations, ATP evokes a urothelial release of acetylcholine that substantially contributes to ATP-evoked contractile responses. Currently we aimed to further examine the interactions of ATP and acetylcholine in the rat urinary bladder in two in vivo models. In the whole bladder preparation, atropine reduced ATP-evoked responses by about 50% in intact but denervated bladders, while atropine had no effect after denudation of the urothelium. In a split bladder preparation, reflex-evoked responses of the contralateral half were studied by applying stimuli (agonists or stretch) to the ipsilateral half. Topical administration of ATP and methacholine as well as of stretch induced contralateral reflex-evoked contractions. While topical administration of atropine ipsilaterally reduced the ATP- and stretch-induced contralateral contractions by 27 and 39%, respectively, the P2X purinoceptor antagonist PPADS reduced them by 74 and 84%. In contrary, the muscarinic M2-(M4)-selective receptor antagonist methoctramine increased the responses by 38% (ATP) and 75% (stretch). Pirenzepine (M1-selective antagonist) had no effect on the reflex. In vitro, in the absence of the reflex, methoctramine did not affect the ATP-induced responses. It is concluded that urothelial ATP potently induces the micturition reflex and stimulates urothelial release of acetylcholine. Acetylcholine subsequently acts on afferents and on the detrusor muscle. While muscarinic M2 and/or M4 receptors in the sensory innervation exert inhibitory modulation, muscarinic M3 receptors cause excitation.

Combination drug therapy against OAB normalizes micturition parameters and increases the release of nitric oxide during chemically induced cystitis

Today, monotherapy is the most common pharmacological treatment option for patients suffering from overactive bladder (OAB). Recent reports have indicated potential benefits of combination therapy, using a muscarinic antagonist and a β3 -adrenoceptor agonist. This may be of particular interest for therapy-resistant patients with OAB and concomitant cystitis. The objective of the current study was to assess how combination therapy affects bladder parameters in health and cystitis and if the efficacy of the drugs can be linked to altered release of nitric oxide (NO). Rats were pretreated with either a combination of the muscarinic antagonist tolterodine and β3 -selective adrenoceptor agonist mirabegron or saline for 10 days. Forty-eight hours prior to assessing micturition parameters in a metabolic cage, the rats were intraperitoneally injected with cyclophosphamide, causing cystitis, or saline. Urine samples were collected and analyzed for NO content. Bladder contractile properties were assessed in an organ bath setup. Induction of cystitis led to bladder overactivity. Combination therapy normalized bladder parameters. Both induction of cystitis and drug treatment increased the release of NO. The innate contractile properties of the bladder were unaffected by combination therapy. This study demonstrates positive effects of combination drug therapy on symptoms of OAB, possibly indicating it to be a good option for treatment of OAB during concomitant cystitis. It remains to be determined if increased release of NO is crucial for successful pharmacological treatment of bladder overactivity during cystitis.

Chemical Profiling of Polyphenolics in Eucalyptus globulus and Evaluation of Its Hepato-Renal Protective Potential Against Cyclophosphamide Induced Toxicity in Mice

Cyclophosphamide (CP) is a potent anti-neoplastic and immunosuppressive agent; however, it causes multi-organ toxicity. We elucidated the protective activities of Eucalyptus globulus (EG) leaf extract against CP-induced hepato-renal toxicity. Mice were treated with EG for 15 days plus CP on day 12 and 13 of the experiment. Using HPLC-DAD-ESI-MS/MS, 26 secondary metabolites were identified in EG leaf extract. Out of them, 4 polyphenolic compounds were isolated: (1) 4-(O-β-d-xylopyranosyloxy)-3,5-di-hydroxy-benzoic acid, (2) 4-(O-α-l-rhamnopyranosyloxy)-3,5-di-hydroxy-benzoic acid, (3) gallic acid, and (4) methyl gallate. Effects of EG extract on biochemical parameters, gene expression, and immune-histopathological changes were assessed in comparison to mesna positive control. Results showed that EG improved CP-increased serum ALT, AST, creatinine, and blood urea nitrogen levels. The hepatic and renal tissue levels of MDA, nitric oxide, protein carbonyl, TNF-α, IL-6, and immunohistochemical expression of nuclear factor kappa-B (NF-kB) and caspase-3 were reduced. Also, hepatic and renal GSH contents, and nuclear factor E2-related factor 2 (NRf2)/ hemoxygenase-1 (HO-1) signaling levels were increased. Histopathological findings supported our findings where hepatic and renal architecture were almost restored. Results revealed the protective effects of EG against CP-induced hepato-renal toxicity. These effects may be related to EG antioxidant, anti-inflammatory, and anti-apoptotic properties coupled with activation of Nrf2/HO-1 signaling.

Impairment of cholinergic bladder contractility in rat model of type I diabetes complicated by cystitis: Contribution of neurotransmitter-degrading ectoenzymes

Parasympathetic regulation of urinary bladder contractions primarily involves acetylcholine release and activation of detrusor smooth muscle (DSM) muscarinic acetylcholine (mACh) receptors. Co-release of ATP and activation of DSM purinergic P2X1-receptors may participate as well in some species. Both types of neuromuscular transmission (NMT) are impaired in diabetes, however, which factors may contribute to such impairment remains poorly understood. Here by using rats with streptozotocin(STZ)-induced type I diabetes (8th week after induction) we show that contribution of atropine-sensitive m-cholinergic component to the contractions of urothelium-denuded DSM strips evoked by electric field stimulation (EFS) greatly increased when diabetic bladders presented overt signs of accompanying cystitis. Modeling of hemorrhagic cystitis alone in control rats by cyclophosphamide injection only modestly increased m-cholinergic component of EFS-contractions. However, exposure of DSM strips from control animals to acetylcholinesterase (AChE) inhibitor, neostigmine (1-10 μM) largely reproduced alterations in EFS contractions observed in diabetic DSM complicated by cystitis. Ellman's assay revealed statistically significant 31% decrease of AChE activities in diabetic vs. control DSM. Changes in purinergic contractility of diabetic DSM were consistent with altered P2X1-receptor desensitization and re-sensitization. They could be mimicked by pharmacological inhibition of ATP-degrading ecto-ATPases with ARL 67156 (50 μM), pointing to compromised extracellular ATP clearance as underlying reason. We conclude that decreased AChE activities associated with diabetes and likely cystitis provide complementary factor to the described in literature altered expression of mACh receptor subtypes linked to diabetes as well as to cystitis to produce dramatic modification of cholinergic NMT.

Molecular mechanism involved in cyclophosphamide-induced cardiotoxicity: Old drug with a new vision

Cyclophosphamide (CP) is an important anticancer drug which belongs to the class of alkylating agent. Cyclophosphamide is mostly used in bone marrow transplantation, rheumatoid arthritis, lupus erythematosus, multiple sclerosis, neuroblastoma and other types of cancer. Dose-related cardiotoxicity is a limiting factor for its use. CP-induced cardiotoxicity ranges from 7 to 28% and mortality ranges from 11 to 43% at the therapeutic dose of 170-180 mg/kg, i.v. CP undergoes hepatic metabolism that results in the production of aldophosphamide. Aldophosphamide decomposes into phosphoramide mustard & acrolein. Phosphoramide is an active neoplastic agent, and acrolein is a toxic metabolite which acts on the myocardium and endothelial cells. This is the first review article that talks about cyclophosphamide-induced cardiotoxicity and the different signaling pathways involved in its pathogenicity. Based on the available literature, CP is accountable for cardiomyocytes energy pool alteration by affecting the heart fatty acid binding proteins (H-FABP). CP has been found associated with cardiomyocytes apoptosis, inflammation, endothelial dysfunction, calcium dysregulation, endoplasmic reticulum damage, and mitochondrial damage. Molecular mechanism of cardiotoxicity has been discussed in detail through crosstalk of Nrf2/ARE, Akt/GSK-3β/NFAT/calcineurin, p53/p38MAPK, NF-kB/TLR-4, and Phospholamban/SERCA-2a signaling pathway. Based on the available literature we support the fact that metabolites of CP are responsible for cardiotoxicity due to depletion of antioxidants/ATP level, altered contractility, damaged endothelium and enhanced pro-inflammatory/pro-apoptotic activities resulting into cardiomyopathy, myocardial infarction, and heart failure. Dose adjustment, elimination/excretion of acrolein and maintenance of endogenous antioxidant pool could be the therapeutic approach to mitigate the toxicities.

Effects of caveolae depletion and urothelial denudation on purinergic and cholinergic signaling in healthy and cyclophosphamide-induced cystitis in the rat bladder

Cholesterol rich membrane invaginations, caveolae, have important roles in various cellular activities, one of them being signal transduction. This signaling pathway seems to be affected during various bladder disorders and the current study aimed to elucidate the plausible involvement of caveolae mediated signal transduction during cyclophosphamide induced cystitis. Furthermore, the urothelial cholinergic part of ATP-evoked contractions and its possible link to caveolae were investigated. Cholinergic, as well as purinergic, contractile responses in rat urinary bladders were examined using a classic organ bath set-up with full-thickness strip preparations or a whole bladder model that enabled luminal administration of substances. Furthermore, sub groups with and without urothelium were examined. The expression of caveolin-1 was also tested using western blot and immunofluorescence. Caveolae cholesterol depletion by methyl-β-cyclodextrin entailed a significant decrease of ATP-evoked bladder contractility. Interestingly, after muscarinic blockade the ATP induced contractions were significantly reduced in the same manner. Furthermore, this atropine-sensitive part of ATP-evoked responses was absent in denuded as well as inflamed bladders. A tendency towards a reduced expression of caveolin-1 was observed in rats with experimental cystitis. The cholinergic part of ATP-induced contractile responses seemed to be affected by urothelium denudation as well as caveolae depletion. Removing one of these structures nullifies the effect of the other, suggesting an important interaction between the urothelium and the caveolar structures. These effects are absent in inflamed animals and might be one pathophysiological aspect behind BPS/IC.

Deletion or pharmacological blockade of TLR4 confers protection against cyclophosphamide-induced mouse cystitis

Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS) is a chronic inflammatory disease without consistently effective treatment. We investigate the role of toll-like receptor 4 (TLR4) on voiding dysfunction and inflammation in the cyclophosphamide (CYP)-induced mouse cystitis. Male C57BL/6 [wild-type, (WT)] and/or TLR4 knockout (TLR4^-/-) mice were treated with an injection of CYP (300 mg/kg, 24 h) or saline (10 ml/kg). The pharmacological blockade of the TLR4 by resatorvid (10 mg/kg) was also performed 1 h prior CYP-injection in WT mice. Urodynamic profiles were assessed by voiding stain on filter paper and filling cystometry. Contractile responses to carbachol were measured in isolated bladders. In CYP-exposed WT mice, mRNA for TLR4, myeloid differentiation primary response 88, and TIR-domain-containing adapter-inducing interferon-β increased by 45%, 72%, and 38%, respectively ( P < 0.05). In free-moving mice, CYP-exposed mice exhibited a higher number of urinary spots and smaller urinary volumes. Increases of micturition frequency and nonvoiding contractions, concomitant with decreases of intercontraction intervals and capacity, were observed in the filling cystometry of WT mice ( P < 0.05). Carbachol-induced bladder contractions were significantly reduced in the CYP group, which was paralleled by reduced mRNA for M2 and M3 muscarinic receptors. These functional and molecular alterations induced by CYP were prevented in TLR4^-/- and resatorvid-treated mice. Additionally, the increased levels of inflammatory markers induced by CYP exposure, myeloperoxidase activity, interleukin-6, and tumor necrosis factor-alpha were significantly reduced by resatorvid treatment. Our findings reveal a central role for the TLR4 signaling pathway in initiating CYP-induced bladder dysfunction and inflammation and thus emphasize that TLR4 receptor blockade may have clinical value for IC/BPS treatment.

Autonomic Receptor-mediated Regulation of Production and Release of Nitric Oxide in Normal and Malignant Human Urothelial Cells

In the urinary bladder, the main source of NO seems to be the urothelium and the underlying suburothelium. In this study, we aimed to characterize how receptors in the human urothelium regulate the production and release of NO. For this, we cultured two human urothelial cell lines - the normal immortalized cell line UROtsa and the malignant cell line T24. These were treated with an array of agonists and antagonists with affinity for adrenergic, muscarinic and purinergic receptors. The production of NO and expression of nitric oxide synthase (NOS) was studied by immunocytochemistry and Western blotting. The amount of released NO was measured indirectly by detecting nitrite using amperometry and a Griess reaction kit. The results showed that NO, endothelial NOS and inducible NOS were predominantly produced and expressed in the close vicinity of the nucleus in untreated human urothelial cells. Upon treatment with a beta-adrenoceptor agonist, but not any of the other agonists or antagonists, the pattern of NO production changed, showing a more even production throughout the cytosol. The pattern of expression of endothelial NOS changed in a similar way upon dobutamine treatment. The release of nitrite, as a measurement of NO, increased after treatment with dobutamine from 0.31 ± 0.029 to 1.97 ± 0.18 nmol and 0.80 ± 0.12 to 3.27 ± 0.24 nmol in UROtsa and T24, respectively. In conclusion, our results show that the expression of NOS and production of NO as well as the release of NO from human urothelial cells is regulated by beta-adrenoceptor activation.

Acetylcholinesterase Inhibitors and Drugs Acting on Muscarinic Receptors- Potential Crosstalk of Cholinergic Mechanisms During Pharmacological Treatment

BACKGROUND

Pharmaceuticals with targets in the cholinergic transmission have been used for decades and are still fundamental treatments in many diseases and conditions today. Both the transmission and the effects of the somatomotoric and the parasympathetic nervous systems may be targeted by such treatments. Irrespective of the knowledge that the effects of neuronal signalling in the nervous systems may include a number of different receptor subtypes of both the nicotinic and the muscarinic receptors, this complexity is generally overlooked when assessing the mechanisms of action of pharmaceuticals.

METHODS

We have search of bibliographic databases for peer-reviewed research literature focused on the cholinergic system. Also, we have taken advantage of our expertise in this field to deduce the conclusions of this study.

RESULTS

Presently, the life cycle of acetylcholine, muscarinic receptors and their effects are reviewed in the major organ systems of the body. Neuronal and non-neuronal sources of acetylcholine are elucidated. Examples of pharmaceuticals, in particular cholinesterase inhibitors, affecting these systems are discussed. The review focuses on salivary glands, the respiratory tract and the lower urinary tract, since the complexity of the interplay of different muscarinic receptor subtypes is of significance for physiological, pharmacological and toxicological effects in these organs.

CONCLUSION

Most pharmaceuticals targeting muscarinic receptors are employed at such large doses that no selectivity can be expected. However, some differences in the adverse effect profile of muscarinic antagonists may still be explained by the variation of expression of muscarinic receptor subtypes in different organs. However, a complex pattern of interactions between muscarinic receptor subtypes occurs and needs to be considered when searching for selective pharmaceuticals. In the development of new entities for the treatment of for instance pesticide intoxication, the muscarinic receptor selectivity needs to be considered. Reactivators generally have a muscarinic M2 receptor acting profile. Such a blockade may engrave the situation since it may enlarge the effect of the muscarinic M3 receptor effect. This may explain why respiratory arrest is the major cause for deaths by esterase blocking.

Gamma-Glutamylcysteine Ethyl Ester Protects against Cyclophosphamide-Induced Liver Injury and Hematologic Alterations via Upregulation of PPARγ and Attenuation of Oxidative Stress, Inflammation, and Apoptosis

Gamma-glutamylcysteine ethyl ester (GCEE) is a precursor of glutathione (GSH) with promising hepatoprotective effects. This investigation aimed to evaluate the hepatoprotective effects of GCEE against cyclophosphamide- (CP-) induced toxicity, pointing to the possible role of peroxisome proliferator activated receptor gamma (PPARγ). Wistar rats were given GCEE two weeks prior to CP. Five days after CP administration, animals were sacrificed and samples were collected. Pretreatment with GCEE significantly alleviated CP-induced liver injury by reducing serum aminotransferases, increasing albumin, and preventing histopathological and hematological alterations. GCEE suppressed lipid peroxidation and nitric oxide production and restored GSH and enzymatic antioxidants in the liver, which were associated with downregulation of COX-2, iNOS, and NF-κB. In addition, CP administration significantly increased serum proinflammatory cytokines and the expression of liver caspase-3 and BAX, an effect that was reversed by GCEE. CP-induced rats showed significant downregulation of PPARγ which was markedly upregulated by GCEE treatment. These data demonstrated that pretreatment with GCEE protected against CP-induced hepatotoxicity, possibly by activating PPARγ, preventing GSH depletion, and attenuating oxidative stress, inflammation, and apoptosis. Our findings point to the role of PPARγ and suggest that GCEE might be a promising agent for the prevention of CP-induced liver injury.

5-HT2A receptor enhancement of contractile activity of the porcine urothelium and lamina propria

OBJECTIVES

To examine the effect of 5-hydroxytryptamine (5-HT; serotonin) on the contractile properties of the urothelium and lamina propria, as a better understanding of bladder physiology might aid the development of new treatments.

METHODS

Strips of porcine urothelium and lamina propria were suspended in gassed Krebs-bicarbonate solution, and cumulative concentration-response curves for 5-HT were generated in the absence and presence of 5-HT antagonists, Nω-nitro-l-arginine and indomethacin. Responses to α-methyl-5-HT were also examined.

RESULTS

Strips of urothelium/lamina propria developed spontaneous contractions, whereas the addition of 5-HT induced concentration-dependent increases in contractile tone with maximal contractions of 50.43 ± 2.78 mN/g tissue weight (n = 100). Tonic contractions to 5-HT were unchanged in the presence of Nω-nitro-l-arginine (100 μmol/L) or indomethacin (5 μmol/L). Selective concentrations of the antagonists methiothepin (5-HT_1&2 , 100 nmol/L), RS102221 (5-HT_2C , 30 nmol/L), ondansetron (5-HT₃ , 30 nmol/L), GR113808, (5-HT₄ , 100 nmol/L), SB699551 (5-HT₅ , 10 nmol/L), SB399885 (5-HT₆ , 100 nmol/L) and SB269970 (5-HT₇ , 10 nmol/L) did not influence responses to 5-HT. However, the 5-HT_2A antagonist, ketanserin (30-300 μmol/L), caused a shift of the 5-HT curve yielding an affinity estimate of 7.9.

CONCLUSIONS

The results show that contractile responses of the urothelium/lamina propria to 5-HT are predominantly mediated through the 5-HT_2A receptor.

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.

Combination therapy with β3 -adrenoceptor agonists and muscarinic acetylcholine receptor antagonists: Efficacy in rats with bladder overactivity

OBJECTIVE

To investigate the efficacy of combination therapy of a selective β3 -adrenoceptor agonist (mirabegron) and muscarinic acetylcholine receptor antagonists (a selective muscarinic acetylcholine receptor2 antagonist: methoctramine hemihydrate or a selective muscarinic acetylcholine receptor3 antagonist; 4-DAMP) compared with monotherapy of either agent in rats with oxotremorine methiodide (a non-selective muscarinic acetylcholine receptor agonist)-induced bladder overactivity.

METHODS

Cystometry was carried out in conscious female rats with intravesical instillation of oxotremorine methiodide (200 μmol/L). Either mirabegron (0.3-3 mg/kg), methoctramine (0.1-1 mg/kg) or 4-DAMP (0.03-0.3 mg/kg) was cumulatively applied intravenously. Also, the effects of combined application of mirabegron (3 mg/kg) plus methoctramine (1 mg/kg) or 4-DAMP (0.3 mg/kg) on cystometric parameters were compared with those of single-agent monotherapy.

RESULTS

Intravesical instillation of oxotremorine methiodide induced bladder overactivity, as evidenced by decreases in threshold pressure and bladder capacity. In oxotremorine methiodide-treated rats, single application of mirabegron (1, 3 mg/kg), methoctramine (0.3, 1 mg/kg) or 4-DAMP (0.1, 0.3 mg/kg) decreased baseline pressure and increased bladder capacity. In addition, reductions in threshold pressure and maximal voiding pressure were also seen after the administration of 4-DAMP (0.3 mg/kg). The combined treatment of mirabegron plus 4-DAMP induced a larger increase in bladder capacity compared with monotherapy of either drug, whereas there were no significant changes in cystometric parameters between the combination therapy of mirabegron plus methoctramine and monotherapy of either drug.

CONCLUSION

These results suggest that the combination therapy of β3 -adrenoceptor agonists plus muscarinic acetylcholine receptor3 antagonists is more effective compared with monotherapy for the treatment of bladder overactivity. In contrast, the efficacy of β3 -adrenoceptor agonists might not be increased by the addition of muscarinic acetylcholine receptor2 antagonists.

Three Gaseous Neurotransmitters, Nitric oxide, Carbon Monoxide, and Hydrogen Sulfide, Are Involved in the Neurogenic Relaxation Responses of the Porcine Internal Anal Sphincter

Background/Aims

The internal anal sphincter (IAS) plays an important role in maintaining continence and a number of neurotransmitters are known to regulate IAS tone. The aim of this study was to determine the relative importance of the neurotransmitters involved in the relaxant and contractile responses of the porcine IAS.

Methods

Responses of isolated strips of IAS to electrical field stimulation (EFS) were obtained in the absence and presence of inhibitors of neurotransmitter systems.

Results

Contractile responses of the sphincter to EFS were unaffected by the muscarinic receptor antagonist, atropine (1 μM), but were almost completely abolished by the adrenergic neuron blocker guanethidine (10 μM). Contractile responses were also reduced (by 45% at 5 Hz, P < 0.01) following desensitisation of purinergic receptors with α,β-methylene-ATP (10 μM). In the presence of guanethidine, atropine, and α,β-methylene-ATP, the remaining relaxatory responses to EFS were examined. These responses were not altered by the cyclooxygenase inhibitor, indomethacin (5 μM), the vasoactive intestinal polypeptide receptor antagonist, [_d-p-Cl-Phe6,Leu17]-vasoactive intestinal peptide (PheLeu-VIP; 100 nM), or the purinoceptor antagonists, 8-phenyltheophyline (P1 receptors) or suramin (P2 receptors). However, relaxation responses were reduced by Nω-nitro-L-arginine (L-NNA; 100 μM), an inhibitor of nitric oxide synthesis (40–50% reduction), zinc protoprophyrin IX (10 μM), an inhibitor of carbon monoxide synthesis (20–40% reduction), and also propargylglycine (30 μM) and aminooxyacetic acid (30 μM), inhibitors of hydrogen sulphide synthesis (15–20% reduction).

Conclusions

Stimulation of IAS efferent nerves releases excitatory and inhibitory neurotransmitters: noradrenaline is the predominant contractile transmitter with a smaller component from ATP, whilst 3 gases mediate relaxation responses to EFS, with the combined contributions being nitric oxide > carbon monoxide > hydrogen sulfide.

Local Change in Urinary Bladder Contractility Following CNS Dopamine Denervation in the 6-OHDA Rat Model of Parkinson's Disease

BACKGROUND

Urinary problems, including urinary frequency, urgency, and nocturia are some of the non-motor symptoms that correlate most with poor quality of life in Parkinson's disease. However, the mechanism behind these symptoms is poorly understood, in particular regarding peripheral bladder pathophysiology following dopamine degeneration.

OBJECTIVE

In this study, we compared the contractile responsiveness of urinary bladder from the 6-OHDA unilateral rat model of Parkinson's disease with that of normal untreated animals.

METHODS

The contractility of the urinary detrusor muscle was evaluated in bladder strip preparations using electrical field stimulation, and muscarinic and purinoceptor stimulations in an vitro organ bath setup.

RESULTS

Our data show that the overall contractile response following electrical field stimulation was significantly higher (43% at maximum contraction by 20-40 Hz stimulation) in the 6-OHDA-lesioned rats as compared to control animals. This increase was associated with a significant increase in the cholinergic contractile response, where the muscarinic agonist methacholine produced a 44% (at 10 -4 M concentration) higher response in the 6-OHDA-treated rats as compared to controls with a significant left-shift of the dose response. This indicates an altered sensitivity of the muscarinic receptor system following the specific central 6-OHDA-induced dopamine depletion. In addition a 36% larger contraction of strips from the 6-OHDA animals was also observed with purinoceptor activation using the agonist ATP (5×10 -3 M) during atropine treatment.

CONCLUSIONS

Our data shows that it is not only the central dopamine control of the micturition reflex that is altered in Parkinson's disease, but also the local contractile function of the urinary bladder. The current study draws attention to a mechanism of urinary dysfunction in Parkinson's disease that has previously not been described.

Therapeutic modulation of urinary bladder function: multiple targets at multiple levels

Storage dysfunction of the urinary bladder, specifically overactive bladder syndrome, is a condition that occurs frequently in the general population. Historically, pathophysiological and treatment concepts related to overactive bladder have focused on smooth muscle cells. Although these are the central effector, numerous anatomic structures are involved in their regulation, including the urothelium, afferent and efferent nerves, and the central nervous system. Each of these structures involves receptors for—and the urothelium itself also releases—many mediators. Moreover, hypoperfusion, hypertrophy, and fibrosis can affect bladder function. Established treatments such as muscarinic antagonists, β-adrenoceptor agonists, and onabotulinumtoxinA each work in part through their effects on the urothelium and afferent nerves, as do α1-adrenoceptor antagonists in the treatment of voiding dysfunction associated with benign prostatic hyperplasia; however, none of these treatments are specifically targeted to the urothelium and afferent nerves. It remains to be explored whether future treatments that specifically act at one of these structures will provide a therapeutic advantage.

Signalling molecules in the urothelium

The urothelium was long considered to be a silent barrier protecting the body from the toxic effects of urine. However, today a number of dynamic abilities of the urothelium are well recognized, including its ability to act as a sensor of the intravesical environment. During recent years several pathways of these urothelial abilities have been proposed and a major part of these pathways includes release of signalling molecules. It is now evident that the urothelium represents only one part of the sensory web. Urinary bladder signalling is finely tuned machinery of signalling molecules, acting in autocrine and paracrine manner, and their receptors are specifically distributed among different types of cells in the urinary bladder. In the present review the current knowledge of the formation, release, and signalling effects of urothelial acetylcholine, ATP, adenosine, and nitric oxide in health and disease is discussed.

Inhibition of nitric oxide synthase prevents muscarinic and purinergic functional changes and development of cyclophosphamide-induced cystitis in the rat

Nitric oxide (NO) has pivotal roles in cyclophosphamide- (CYP-) induced cystitis during which mucosal nitric oxide synthase (NOS) and muscarinic M5 receptor expressions are upregulated. In cystitis, urothelial muscarinic NO-linked effects hamper contractility. Therefore we wondered if a blockade of this axis also affects the induction of cystitis in the rat. Rats were pretreated with saline, the muscarinic receptor antagonist 4-DAMP (1 mg/kg ip), or the NOS inhibitor L-NAME (30 mg/kg ip) for five days. 60 h before the experiments the rats were treated with saline or CYP. Methacholine-, ATP-, and adenosine-evoked responses were smaller in preparations from CYP-treated rats than from saline-treated ones. Pretreatment with 4-DAMP did not change this relation, while pretreatment with L-NAME normalized the responses in the CYP-treated animals. The functional results were strengthened by the morphological observations; 4-DAMP pretreatment did not affect the parameters studied, namely, expression of muscarinic M5 receptors, P1A1 purinoceptors, mast cell distribution, or bladder wall enlargement. However, pretreatment with L-NAME attenuated the differences. Thus, the current study provides new insights into the complex mechanisms behind CYP-induced cystitis. The NO effects coupled to urothelial muscarinic receptors have a minor role in the development of cystitis. Inhibition of NOS may prevent the progression of cystitis.

Cyclophosphamide-induced alterations of the micturition reflex in a novel in situ urinary bladder model in the anesthetized rat

AIMS

Cyclophosphamide-induced cystitis alterations have been reported to occur both at efferent and afferent level in the micturition reflex arc. In particular, the stretching of the bladder wall causing urothelial release of ATP has been proposed as one of the pivotal mechanisms causing these alterations. To evaluate functional changes at efferent and afferent levels of the micturition reflex following cyclophosphamide treatment we have applied a novel in situ half bladder rat model.

METHODS

Male Sprague-Dawley rats were treated with either saline or cyclophosphamide (100 mg/kg), and stretch-, electric-, methacholine-, and ATP-induced responses were thereafter measured at 60-72 hr postinjection under pentobarbitone anesthesia. In the novel in situ half bladder model, the urinary bladder was prepared via a midline incision, where the two halves were separated all the way to the urethra as previously described.

RESULTS

Following bladder stretch of 30-80 mN, of the half that was not used for tension measurement, the cyclophosphamide-treated animals evoked significant two- to threefold larger contractile responses as compared to saline-treated control animals. A sensitization of the afferent arm was shown in cyclophosphamide-treated animals, since afferent stimulation evoked similar responses as in control animals despite that the efferent pelvic nerve stimulation displayed a lower contraction-frequency relationship in cyclophosphamide-treated animals. Atropine reduced the stretch(reflex)-evoked contraction by up to 50% in control and 75-80% in cyclophosphamide-treated rats. Subsequent addition of PPADS further reduced the contractions.

CONCLUSION

The micturition reflex response is increased following cyclophosphamide-induced cystitis, as compared to control. The likely cause is sensitization at mechanosensor level in the micturition arc, which overrides the decrement of the efferent cholinergic effects.

Polydatin, a natural precursor of resveratrol, induces cell cycle arrest and differentiation of human colorectal Caco-2 cell

Background

Human colon adenocarcinoma cells are resistant to chemotherapeutic agents, such as anthracyclines, that induce death by increasing the reactive oxygen species. A number of studies have been focused on chemo-preventive use of resveratrol as antioxidant against cardiovascular diseases, aging and cancer. While resveratrol cytotoxic action was due to its pro-oxidant properties. In this study, we investigate whether the Resveratrol (trans-3,5,49-trihydroxystilbene) and its natural precursor Polydatin (resveratrol-3-O-b-mono- D-glucoside, the glycoside form of resveratrol) combination, might have a cooperative antitumor effect on either growing or differentiated human adenocarcinoma colon cancer cells.

Methods

The polydatin and resveratrol pharmacological interaction was evaluated in vitro on growing and differentiated Caco-2 cell lines by median drug effect analysis calculating a combination index with CalcuSyn software. We have selected a synergistic combination and we have evaluated its effect on the biological and molecular mechanisms of cell death.

Results

Simultaneous exposure to polydatin and resveratrol produced synergistic antiproliferative effects compared with single compound treatment. We demonstrated that polydatin alone or in combination with resveratrol at 3:1 molar ratio synergistically modulated oxidative stress, cell cycle, differentiation and apoptosis. Worthy of note treatment with polydatin induced a nuclear localization and decreased expression of heat shock protein 27, and vimentin redistributed within the cell.

Conclusions

From morphological, and biochemical outcome we obtained evidences that polydatin induced a transition from a proliferative morphology to cell-specific differentiated structures and caused human CaCo-2 cell death by induction of apoptosis. Our data suggest the potential use of polydatin in combination chemotherapy for human colon cancer.

Adenosine receptor antagonism suppresses functional and histological inflammatory changes in the rat urinary bladder

Cyclophosphamide (CYP) induces an interstitial cystitis-like inflammation. The resulting bladder dysfunction has been associated with increased release of adenosine-5'-triphosphate (ATP), structural bladder wall changes and contractile impairment. Due to the inflammatory modulatory effects of purines it was presently wondered if pre-treatment with P1 and P2 purinoceptor antagonists affect the CYP-induced alterations. Rats were pre-treated with saline or antagonists for five days, and 60 h before the in vitro functional examination the rats were administered either saline or CYP. Histological examination revealed CYP-induced bladder wall thickening largely depending on submucosal enlargement, mast cell invasion of the detrusor muscle, increase in muscarinic M5 receptor expression and macrophage migration inhibitory factor (MIF) occurrence in large parts of the urothelium. Functionally, methacholine- and ATP-evoked contractions were smaller in urinary bladders from CYP-treated rats. Pre-treatment with the P2 purinoceptor antagonist suramin and the P1A2B antagonist PSB1115 did not to any great extent affect the CYP-induced changes. The P1A1 antagonist DPCPX, however, abolished the difference of methacholine-evoked contractions between saline- and CYP-treated rats. ATP-evoked contractions were reduced in control after the DPCPX pre-treatment, but not in cystitis. The functional observations for DPCPX were supported by its suppression of CYP-induced submucosal thickening, muscarinic M5 receptor expression and, possibly, detrusor mast cell infiltration and the spread of urothelial MIF occurrence. Thus, P1A1 is an important pro-inflammatory receptor in the acute CYP-induced cystitis and a P1A1 blockade during the initial phase may suppress CYP-induced cystitis. P1A1 purinoceptors seem to regulate contractility in healthy and in inflamed rat urinary bladders.

Muscarinic receptor subtypes involved in urothelium-derived relaxatory effects in the inflamed rat urinary bladder

Functional studies have shown altered cholinergic mechanisms in the inflamed bladder, which partly depend on muscarinic receptor-induced release of nitric oxide (NO). The current study aimed to characterize which muscarinic receptor subtypes that are involved in the regulation of the nitrergic effects in the bladder cholinergic response during cystitis. For this purpose, in vitro examinations of carbachol-evoked contractions of inflamed and normal bladder preparations were performed. The effects of antagonists with different selectivity for the receptor subtypes were assessed on intact and urothelium-denuded bladder preparations. In preparations from cyclophosphamide (CYP; in order to induce cystitis) pre-treated rats, the response to carbachol was about 75% of that of normal preparations. Removal of the urothelium or administration of a nitric oxide synthase inhibitor re-established the responses in the inflamed preparations. Administration of 4-diphenylacetoxy-N-methylpiperidine (4-DAMP) inhibited the carbachol-induced contractile responses of preparations from CYP pre-treated rats less potently than controls. Pirenzepine and p-fluoro-hexahydro-sila-diphenidol (pFHHSiD) affected the carbachol-induced contractile responses to similar extents in preparations of CYP pre-treated and control rats. However, the Schild slopes for the three antagonists were all significantly different from unity in the preparations from CYP pre-treated rats. Again, L-NNA or removal of the urothelium eliminated any difference compared to normal preparations. This study confirms that muscarinic receptor stimulation in the inflamed rat urinary bladder induces urothelial release of NO, which counteracts detrusor contraction.

Coupled nitric oxide and autonomic receptor functional responses in the normal and inflamed urinary bladder of the rat

Both divisions of the autonomic nervous system are involved in regulation of urinary bladder function. Several substances, other than noradrenaline and acetylcholine, seem to play important roles in physiology and pathophysiology of lower urinary tract. In the current study, we aimed to examine if there exist interplays between nitric oxide (NO) and autonomic transmitters and if such interactions vary in different parts of the urinary bladder in healthy and cyclophosphamide (CYP)-induced cystitic rats; when administered to the animals (100 mg/kg; i.p.), the cytotoxic CYP metabolite acrolein induces bladder inflammation. In the current study a series of in vitro functional studies were performed on detrusor muscle strip preparations. Stimulation with electrical field stimulation (EFS), methacholine, adenosine 5´-triphosphate (ATP), and adrenaline evoked contractile responses in isolated bladder preparations that were significantly reduced in cyclophosphamide (CYP)-treated rats. While the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine (L-NNA; 10(-4) M) did not affect contractile responses in normal, healthy strip preparations, it significantly increased the contractile responses to EFS, methacholine and adrenaline, but not to ATP, in the bladders from the CYP-treated rats. In the CYP-treated rats, the ATP-evoked relaxatory part of its dual response (an initial contraction followed by a relaxation) was 6-fold increased in comparison with that of normal preparations, whereas the isoprenaline relaxation was halved in the CYP-treated. While L-NNA (10(-4) M) had no effect on the isoprenaline-evoked relaxations, it reduced the ATP-evoked relaxations in strip preparations from the bladder body of CYP-treated rats. Stimulation of beta(2)- and beta(3)-adrenoceptors evoked relaxations and both responses were reduced in cystitis, the latter to a larger extent. In the trigone, the reduced ATP-evoked contractile response in the inflamed strips was increased by L-NNA, while L-NNA had no effect on the ATP-evoked relaxations, neither on the relaxations in healthy nor on the larger relaxations in the inflamed trigone. The study shows that both contractile and relaxatory functions are altered in the state of inflammation. The parasympathetic nerve-mediated contractions of the body of the bladder, evoked by the release of ATP and acetylcholine, were substantially reduced in cystitis. The relaxations to beta-adrenoceptor and purinoceptor stimulation were also reduced but only the ATP-evoked relaxation involved NO.

Unique properties of muscularis mucosae smooth muscle in guinea pig urinary bladder

The muscularis mucosae, a type of smooth muscle located between the urothelium and the urinary bladder detrusor, has been described, although its properties and role in bladder function have not been characterized. Here, using mucosal tissue strips isolated from guinea pig urinary bladders, we identified spontaneous phasic contractions (SPCs) that appear to originate in the muscularis mucosae. This smooth muscle layer exhibited Ca(2+) waves and flashes, but localized Ca(2+) events (Ca(2+) sparks, purinergic receptor-mediated transients) were not detected. Ca(2+) flashes, often in bursts, occurred with a frequency (∼5.7/min) similar to that of SPCs (∼4/min), suggesting that SPCs are triggered by bursts of Ca(2+) flashes. The force generated by a single mucosal SPC represented the maximal force of the strip, whereas a single detrusor SPC was ∼3% of maximal force of the detrusor strip. Electrical field stimulation (0.5-50 Hz) evoked force transients in isolated detrusor and mucosal strips. Inhibition of cholinergic receptors significantly decreased force in detrusor and mucosal strips (at higher frequencies). Concurrent inhibition of purinergic and cholinergic receptors nearly abolished evoked responses in detrusor and mucosae. Mucosal SPCs were unaffected by blocking small-conductance Ca(2+)-activated K(+) (SK) channels with apamin and were unchanged by blocking large-conductance Ca(2+)-activated K(+) (BK) channels with iberiotoxin (IbTX), indicating that SK and BK channels play a much smaller role in regulating muscularis mucosae SPCs than they do in regulating detrusor SPCs. Consistent with this, BK channel current density in myocytes from muscularis mucosae was ∼20% of that in detrusor myocytes. These findings indicate that the muscularis mucosae in guinea pig represents a second smooth muscle compartment that is physiologically and pharmacologically distinct from the detrusor and may contribute to the overall contractile properties of the urinary bladder.

Effect of hyaluronic acid on urine nerve growth factor in cyclophosphamide-induced cystitis

OBJECTIVES

To investigate how hyaluronic acid (HA) affects nerve growth factor (NGF) production and bladder overactivity in a cyclophosphamide (CYP)-induced cystitis rat model.

METHODS

Female Sprague-Dawley rats received three intermittent intraperitoneal injections of CYP (75 mg/kg) or saline. Before or after CYP injection, HA was given intravesically and urine NGF was checked with creatinine correction. Bladder function was evaluated by cystometrograms under Zoletil anesthesia. Furthermore, the effect of HA was counteracted with hyaluronidase (HYAL). Bladder structural change was compared among groups with trichrome stain.

RESULTS

The intercontraction interval (ICI) significantly decreased in CYP-injected rats in comparison to the saline-injected controls. In the CYP-injected groups, bladder HA instillation significantly increased the ICI, but did not change the maximum voiding pressure in comparison to the saline instillation. NGF production significantly increased in CYP-injected rats, but decreased significantly with HA treatment. Treatment with HA had a more significant effect on urine NGF and the use of HYAL would eliminate this effect. Specific staining showed mucosa swelling after CYP treatment. Little HA coating on bladder mucosa could be found in HA-treated rats.

CONCLUSIONS

Present findings raise the possibility that HA could be an effective treatment for CYP-related bladder overactivity through the involvement of NGF signaling.

A novel quinone-based derivative (DTNQ-Pro) induces apoptotic death via modulation of heat shock protein expression in Caco-2 cells

BACKGROUND AND PURPOSE

The resistance of human colon adenocarcinoma cells to antineoplastic agents may be related to the high endogenous expression of stress proteins, including the family of heat shock proteins (HSPs). Recently, a quinone-based pentacyclic derivative, DTNQ-Pro, showed high cytotoxic activity in human colon carcinoma cell lines. The aim of the present study was to determine the precise cellular mechanisms of this cytotoxic action of DTNQ-Pro.

EXPERIMENTAL APPROACH

Using human colorectal carcinoma-derived Caco-2 cells as a model, we studied the effects of DTNQ-Pro on cellular viability and oxidative stress; HSP70 and HSP27 accumulation; and cell cycle, differentiation and apoptosis.

KEY RESULTS

Incubation of Caco-2 cells with DTNQ-Pro reduced cell growth and increased the levels of reactive oxygen species in mitochondria. After 48 h of treatment, cells surviving showed an increased expression of Mn-superoxide dismutase (SOD), nitric oxide production and membrane lipid peroxidation. Treatment with DTNQ-Pro decreased HSP70 expression, and redistributed HSP27 and vimentin within the cell. DTNQ-Pro down-regulated the expression of A and B cyclins with arrest of the cell cycle in S phase and increased cellular differentiation. A second treatment of Caco-2 cells with DTNQ-Pro induced cellular death by activation of the apoptotic pathway.

CONCLUSIONS AND IMPLICATIONS

DTNQ-Pro causes Caco-2 cell death by induction of apoptosis via inhibition of HSP70 accumulation and the intracellular redistribution of HSP27. These findings suggest the potential use of DTNQ-Pro in combination chemotherapy for colon cancer.

Pharmacological modulation of the micturition pattern in normal and cyclophosphamide pre-treated conscious rats

In the current study, we wanted to assess the influence of muscarinic receptors, nitric oxide and purinoceptors on the micturition pattern of conscious normal and cyclophosphamide (CYP) pre-treated rats. The micturition parameters were assessed using a metabolic cage. Rats were pre-treated with either saline or CYP, to induce cystitis, followed by treatment with either the muscarinic M1/M3/M5 receptor antagonist 4-diphenylacetoxy-N-methylpiperidine (4-DAMP), the nitric oxide synthase blocker N(ω)-nitro-L-arginine methyl (L-NAME), the P2 purinoceptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS) or a combination of 4-DAMP with PPADS or L-NAME. Voiding volumes per micturition event were significantly lower in CYP pre-treated than in saline pre-treated rats. Neither 4-DAMP nor L-NAME had any effect in the normal rats, whereas PPADS reduced the micturition volume per event. In CYP pre-treated rats, 4-DAMP and L-NAME significantly increased voiding volumes per event and micturition frequency, respectively. 4-DAMP dose-dependently reduced the differences in micturition activity between saline and CYP pre-treated rats. We show that cystitis changes the urodynamics in conscious rats and that this change seems to depend on the production of NO and on altered muscarinic receptor effects. The altered muscarinic receptor responses are likely to per se involve NO-mediated mechanisms.

Removal of urothelium affects bladder contractility and release of ATP but not release of NO in rat urinary bladder

Background

The objective of our work was to investigate both the contractile function and the release of ATP and NO from strips of bladder tissue after removal of the urothelium.

Methods

The method of removal was a gentle swabbing motion rather than a sharp surgical cutting to separate the urothelium from the smooth muscle. The contractile response and ATP and NO release were measured in intact as well as on swabbed preparations. The removal of the urothelial layer was affirmed microscopically.

Results

After the swabbing, the smaller contractions were evoked by electrical as well as by chemical stimulation (50 μM carbachol or 50 μM α, β meATP). Electrical stimulation, carbachol and substance P (5 μM) evoked lower release of ATP in the swabbed strips than in intact strips. Although release of NO evoked by electrical stimulation or substance P was not changed, release of NO evoked by carbachol was significantly less in the swabbed preparations.

Conclusion

Since swabbing removes only the urothelium, the presence of the suburothelial layer may explain the difference between our findings and those of others who found an increase in contractility. Evoked release of ATP is reduced in swabbed strips, indicating that ATP derives solely from the urothelium. On the other hand, electrical stimulation and substance P evoke identical degrees of NO release in both intact and swabbed preparations, suggesting that NO can be released from the suburothelium. Conversely, carbachol-induced release of NO is lower in swabbed strips, implying that the cholinergic receptors (muscarinic or nicotinic) are located in the upper layer of the urothelium.

Bladder urothelial cells from patients with interstitial cystitis have an increased sensitivity to carbachol

AIMS

The presence of muscarinic receptors on bladder urothelial cells (BUC), suggests BUC may be a target for antimuscarinics. This study determined whether human BUC are responsive to a muscarinic agonist and if so, whether responses are altered in interstitial cystitis (IC) BUC.

METHODS

Primary urothelial cell cultures were established from cystoscopic biopsies. Normal (NB) and IC BUC were studied using calcium imaging techniques as a means to monitor the response to muscarinic receptor activation with the agonist, carbachol (CCh). Changes in intracellular Ca(2+) concentration ([Ca(2+)](i)) were measured with fura-2 ratiometric microfluorimetry. Dose-response curves (CCh dose vs. [Ca(2+)](i)) were measured in IC and NB BUC. Tolterodine was used to confirm the specificity (muscarinic versus nicotinic) of CCh evoked increases in [Ca(2+)](i).

RESULTS

CCh induced a dose-dependent increase in [Ca(2+)](i). Potency and efficacy of CCh was significantly greater in IC BUC. The maximal increase in [Ca(2+)](i) was 136.3 +/- 5.1% over baseline in 78 cells from 4 IC patients versus 92.4 +/- 4.8% over baseline in 67 cells from 4 NB subjects (P < 0.01). The EC50 of the evoked increase was 1.10 +/- 0.14 microM versus 3.36 +/- 0.72 microM (P < 0.01) in BUC from IC and NB controls, respectively. Removal of extracellular calcium or application of tolterodine, abolished CCh evoked increase in [Ca(2+)](i) in IC and NB BUC.

CONCLUSIONS

The greater sensitivity of IC BUC to CCh suggests that IC patholobiology may also include alterations muscarinic signaling. The physiologic sequelae of muscarinic activation in BUC need to be further investigated.

Uroprotective effects of curcumin in cyclophosphamide-induced haemorrhagic cystitis paradigm

The possible uroprotective effects of curcumin have been addressed in the current study. Haemorrhagic cystitis was induced by challenging male Swiss albino rats with a single dose of cyclophosphamide (150 mg/kg, i.p.). Curcumin (200 mg/kg, i.p.) was administered for 10 consecutive days followed by a single dose of cyclophosphamide. Haemorrhagic cystitis was well characterized morphologically and biochemically. The hallmark of this toxicity was marked congestion, oedema and extravasation in rat urinary bladder, as well as a marked desquamative damage to the urothelium and severe inflammation in the lamina propria. Leucocytic infiltration was also observed and determined by histopathological examination. Serum level of tumour necrosis factor-alpha was notably elevated associated with apparent hypokalaemia and hyponatraemia. Bladder contents of adenosine triphosphate, reduced glutathione and glutathione-S-transferase activity were markedly reduced. Malondialdehyde level, myeloperoxidase activity and urinary nitrite-nitrate levels, expressed as nitric oxide, were dramatically increased. Prior administration of curcumin ahead of cyclophosphamide challenge improved all the biochemical and histologic alterations induced by the cytotoxic drug. Based on these broad findings, it could be concluded that curcumin has proven uroprotective efficacy in this cyclophosphamide haemorrhagic cystitis model, possibly through modulating the release of inflammatory endocoids, namely tumour necrosis factor-alpha and nitric oxide, improving the energy status and restoring the oxidant/antioxidant balance.