Pharmacological characterization of thromboxane and prostanoid receptors in human isolated urinary bladder

Pharmacological study on the enhancing effects of U46619 on guinea pig urinary bladder smooth muscle contraction induced by acetylcholine and α,β-methylene ATP and the possible involvement of protein kinase C

We examined whether U46619 (a prostanoid TP receptor agonist) could enhance the contractions of guinea pig urinary bladder smooth muscle (UBSM) in response to acetylcholine (ACh) and an ATP analog (α,β-methylene ATP (αβ-MeATP)) through stimulation of the UBSM TP receptor and whether protein kinase C (PKC) is involved. U46619 (10-7 M) markedly enhanced UBSM contractions induced by electrical field stimulation and ACh/αβ-MeATP (3 × 10-6 M each), the potentiation of which was completely suppressed by SQ 29,548 (a TP receptor antagonist, 6 × 10-7 M). PKC inhibitors did not attenuate the ACh-induced contractions enhanced by U46619 although they partly suppressed the U46619-enhanced, αβ-MeATP-induced contractions. While phorbol 12-myristate 13-acetate (PMA, a PKC activator, 10-6 M) did not enhance ACh-induced contractions, it enhanced αβ-MeATP-induced contractions, an effect that was completely suppressed by PKC inhibitors. αβ-MeATP-induced contractions, both with and without U46619 enhancement, were strongly inhibited by diltiazem. U46619/PMA enhanced 50 mM KCl-induced contractions, the potentiation of which was partly/completely attenuated by PKC inhibitors. These findings suggest that U46619 potentiates parasympathetic nerve-associated UBSM contractions by stimulating UBSM TP receptors. PKC-increased Ca2+ influx through voltage-dependent Ca2+ channels may partially play a role in purinergic receptor-mediated UBSM contractions enhanced by TP receptor stimulation.

Prostanoid TP receptor stimulation enhances contractile activities in guinea pig urinary bladder smooth muscle through activation of Ca2+ entry channels: Potential targets in the treatment of urinary bladder contractile dysfunction

AIMS

We examined the potential stimulatory effects of U46619 (a prostanoid TP receptor agonist) and five prostanoids on the contractile activities of urinary bladder smooth muscle (UBSM), focusing on the role of the TP receptor and its associated Ca²⁺ influx routes to understand the roles of prostanoids in the regulation of UB contractile activity.

MAIN METHODS

Changes in the basal tone and spontaneous contractile activity (amplitude and frequency) of isolated guinea pig UBSM were measured isotonically. The presence of TP receptors in UBSM was examined by RT-qPCR and immunofluorescence.

KEY FINDINGS

U46619, prostaglandin (PG) E₂, PGF_2α, and PGA₂ enhanced UBSM basal tone and spontaneous contractile activities, which were measured as amplitudes and frequencies. The enhancing effects of U46619 were completely suppressed by SQ 29,548 (a TP receptor antagonist), which also partially suppressed the stimulating effects of other prostanoids. The expression of TP receptors in UBSMs was verified at the mRNA and protein level. The enhancing effects of U46619 completely disappeared in Ca²⁺-free solution. U46619-enhanced basal tone was completely suppressed by verapamil, an inhibitor of voltage-dependent Ca²⁺ channels (VDCCs), and verapamil strongly decreased the spontaneous contraction frequency. The spontaneous contractions remaining in the presence of verapamil were strongly suppressed by SKF-96365 (an inhibitor of receptor-operated Ca²⁺ channels (ROCCs)/store-operated Ca²⁺ channels (SOCCs)), but not by LOE-908 (an inhibitor of ROCCs).

SIGNIFICANCE

Prostanoids can enhance UBSM contractile activities and thus may be endogenous candidates for induction of detrusor overactivity. The TP receptor and TP-receptor-activated VDCCs/SOCCs are key molecules responsible for these effects.

Isoprostanes evoke contraction of the murine and human detrusor muscle via activation of the thromboxane prostanoid TP receptor and Rho kinase

Local or systemic inflammation can severely impair urinary bladder functions and contribute to the development of voiding disorders in millions of people worldwide. Isoprostanes are inflammatory lipid mediators that are upregulated in the blood and urine by oxidative stress and may potentially induce detrusor overactivity. The aim of the present study was to investigate the effects and signal transduction of isoprostanes in human and murine urinary bladders in order to provide potential pharmacological targets in detrusor overactivity. Contraction force was measured with a myograph in murine and human urinary bladder smooth muscle (UBSM) ex vivo. Isoprostane 8-iso-PGE₂ and 8-iso-PGF_2α evoked dose-dependent contraction in the murine UBSM, which was abolished in mice deficient in the thromboxane prostanoid (TP) receptor. The responses remained unaltered after removal of the mucosa or incubation with tetrodotoxin. Smooth muscle-specific deletion of Gα_12/13 protein or inhibition of Rho kinase by Y-27632 decreased the contractions. In Gα_q/11-knockout mice, responses were reduced and in the presence of Y-27632 abolished completely. In human UBSM, the TP agonist U-46619 evoked dose-dependent contractions. Neither atropine nor the purinergic receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid decreased the effect, indicating that TP receptors directly mediate detrusor muscle contraction. 8-iso-PGE₂ and 8-iso-PGF_2α evoked dose-dependent contraction in the human UBSM, and these responses were abolished by the TP antagonist SQ-29548 and were decreased by Y-27632. Our results indicate that isoprostanes evoke contraction in murine and human urinary bladders, an effect mediated by the TP receptor. The G_12/13-Rho-Rho kinase pathway plays a significant role in mediating the contraction and therefore may be a potential therapeutic target in detrusor overactivity.NEW & NOTEWORTHY Voiding disorders affect millions of people worldwide. Inflammation can impair urinary bladder functions and contribute to the development of detrusor overactivity. The effects and signal transduction of inflammatory lipid mediator isoprostanes were studied in human and murine urinary bladders ex vivo. We found that isoprostanes evoke contraction, an effect mediated by thromboxane prostanoid receptors. The G_12/13-Rho-Rho kinase signaling pathway plays a significant role in mediating the contraction and therefore may be a potential therapeutic target.

Prostaglandin E2 and F2alpha Modulate Urinary Bladder Urothelium, Lamina Propria and Detrusor Contractility via the FP Receptor

Current pharmacological treatment options for many bladder contractile dysfunctions are not suitable for all patients, thereby bringing interest to the investigation of therapies that target a combination of receptors. This study aimed to compare responses of PGE₂ on the urinary bladder urothelium with lamina propria (U&LP, also called the bladder mucosa) or detrusor smooth muscle and attempt to identify the receptor subtypes mediating PGE₂ contractile responses in these tissues. In the presence of selective EP1 – 4 receptor antagonists, varying concentrations of PGE₂ were applied to isolated strips of porcine U&LP and detrusor that were mounted in organ baths filled with Krebs-bicarbonate solution and gassed with carbogen. The addition of PGE₂ (1 and 10 μM) and PGF_2α (10 μM) to U&LP preparations caused significant increases in the baseline tension and in the spontaneous phasic contractile frequency. In detrusor preparations, significant increases in the baseline tension were observed in response to PGE₂ (1 and 10 μM) and PGF_α (10 μM), and spontaneous phasic contractions were initiated in 83% of preparations. None of the selective PGE₂ receptor antagonists inhibited the increases in baseline tension in both U&LP and detrusor. However, the antagonism of PGF_2α receptor showed significantly inhibited contractile responses in both layers of the bladder. This study presents prostaglandin receptor systems as a potential regulator of urinary bladder contractility. The main contractile effects of PGE₂ in both U&LP and detrusor are mediated via the FP receptor with no observed contribution from any of the four EP receptors.

The five primary prostaglandins stimulate contractions and phasic activity of the urinary bladder urothelium, lamina propria and detrusor

Background

Inflammation is often associated with several bladder dysfunctions, including overactive bladder (OAB) and interstitial cystitis/bladder pain syndrome (IC/PBS). As such, inflammation of the bladder and the actions of inflammatory mediators may contribute to the development of urinary symptoms. This study assessed the actions of PGE₂, PGF₂, PGD₂, TXA₂, and PGI₂ on urinary bladder urothelium with lamina propria (U&LP), and detrusor smooth muscle.

Methods

Studies were carried out using isolated tissue baths, where strips of porcine bladder U&LP or detrusor were exposed to varying concentrations of prostaglandin agonists (1 μM and 10 μM).

Results

All assessed prostaglandin agonists contracted both the U&LP and detrusor smooth muscle, with the rank order of contractile response effectiveness as: PGE₂ > PGF_2α > TXA₂ > PGD₂ > PGI₂. In U&LP, treatment with PGE₂ (10 μM) increased tonic contractions by 1.36 ± 0.09 g (n = 42, p < 0.001) and phasic contractions by 40.4 ± 9.6% (n = 42, p < 0.001). In response to PGF_2α (10 μM), U&LP tonic contractions increased by 0.79 ± 0.06 g (n = 14, p < 0.001) and phasic activity by 13.3% ± 5.3% (n = 15, p < 0.05). In detrusor preparations, PGE₂ (10 μM) increased tonic contractions by 1.32 ± 0.13 g (n = 38, p < 0.001) and PGF_2α (10 μM) by 0.97 ± 0.14 g (n = 12, p < 0.001). Only 34% (n = 48) of all detrusor preparations exhibited spontaneous activity prior to the addition of any agonist at a frequency of 2.03 ± 0.12 cpm. In preparations that did not exhibit initial phasic activity, all of the prostaglandin agonists were capable of commencing phasic activity.

Conclusions

The urinary bladder U&LP and detrusor respond to a variety of prostaglandin agonists, with their activation resulting in direct contractions, as well as increases to spontaneous contractile activity. This study presents the prostaglandin receptor system as a potential therapeutic target for lower urinary tract dysfunction.

Inhibition of Female and Male Human Detrusor Smooth Muscle Contraction by the Rac Inhibitors EHT1864 and NSC23766

Introduction

Lower urinary tract symptoms (LUTS) due to overactive bladder (OAB) are caused by spontaneous detrusor contractions. Medical treatment with muscarinic receptor antagonists or β₃-adrenoceptor agonists aims to inhibit detrusor contractions, but overall results are unsatisfactory. Consequently, improved understanding of bladder smooth muscle contraction and identification of novel compounds for its inhibition are needed to develop alternative options. A role of the GTPase Rac1 for smooth muscle contraction has been reported from the prostate, but is unknown in the human detrusor. Here, we examined effects of the Rac inhibitors NSC23766, which may also antagonize muscarinic receptors, and EHT1864 on contraction of human detrusor tissues.

Methods

Female and male human detrusor tissues were obtained from radical cystectomy. Effects of NSC23766 (100 µM) and EHT1864 (100 µM) on detrusor contractions were studied in an organ bath.

Results

Electric field stimulation induced frequency-dependent contractions of detrusor tissues, which were inhibited by NSC23766 and EHT1864. Carbachol induced concentration-dependent contractions. Concentration response curves for carbachol were shifted to the right by NSC23766, reflected by increased EC₅₀ values, but unchanged E_max values. EHT1864 reduced carbachol-induced contractions, resulting in reduced E_max values for carbachol. The thromboxane analog U46619 induced concentration-dependent contractions, which remained unchanged by NSC23766, but were reduced by EHT1864.

Conclusions

NSC23766 and EHT1864 inhibit female and male human detrusor contractions. NSC23766, but not EHT1864 competitively antagonizes muscarinic receptors. In addition to neurogenic and cholinergic contractions, EHT1864 inhibits thromboxane A₂-induced detrusor contractions. The latter may be promising, as the origin of spontaneous detrusor contractions in OAB is noncholinergic. In vivo, both compounds may improve OAB-related LUTS.

α1 -Blocker inhibits non-voiding contractions and decreases the level of intravesical prostaglandin E2 in rats with partial bladder outlet obstruction

OBJECTIVES

To elucidate the mechanism of action of the α₁ -blocker, naftopidil, in partial bladder outlet obstruction animals, by studying non-voiding contractions, and the levels of mediators were measured with resiniferatoxin treatment.

METHODS

A total of 35 female Wistar rats were randomly divided into a sham or bladder outlet obstruction group, and rats in each group were given vehicle or resiniferatoxin. Incomplete urethral ligation was applied to the bladder outlet obstruction group. After cystometry, the intravesical level of prostaglandin E₂ and adenosine 5'-triphosphate was measured in the instilled perfusate collected. Naftopidil was given at the time of cystometry.

RESULTS

In bladder outlet obstruction rats, non-voiding contractions, bladder capacity, and the intravesical levels of prostaglandin E₂ and adenosine 5'-triphosphate were markedly increased compared with sham rats. Naftopidil decreased non-voiding contractions, enlarged the bladder capacity, and decreased the intravesical levels of prostaglandin E₂ and adenosine 5'-triphosphate. Resiniferatoxin enhanced non-voiding contractions. The effects of naftopidil on non-voiding contractions and the intravesical level of prostaglandin E₂ , but not adenosine 5'-triphosphate, were tolerant to resiniferatoxin.

CONCLUSIONS

In bladder outlet obstruction rats, one cause of generation of non-voiding contractions might be bladder wall distension, but not transient receptor potential cation channel V1. The increase in intravesical prostaglandin E₂ might also be associated with the generation of non-voiding contractions. Naftopidil inhibits the increase in non-voiding contractions and decreases the intravesical level of prostaglandin E₂ , which are independent of transient receptor potential cation channel V1.

Sildenafil corrects the increased contractility of rat detrusor muscle induced by alprostadil in vitro

BACKGROUND

Sildenafil (PDE5-inhibitor) and alprostadil (PGE₁) are used in combination clinically for the management of some cases of erectile dysfunction. Despite the roles of prostaglandins (PG) and nitric oxide (NO) pathways in contractility of bladder smooth muscle are frequently studied, the effect of sildenafil/alprostadil combination and the crosstalk between NO/cGMP and PG pathways on bladder activity is not documented.

METHODS

Organ-bath experiments were performed using isolated rat detrusor muscle. Direct and neurogenic contractions were induced using ACh and electric stimulation (EFS, 4Hz, 80V, 1ms), respectively. The contractile responses in absence and presence of the tested drugs at different concentrations were compared. Results are expressed as mean ± SEM (n = 5-7).

RESULTS

Alprostadil (0.01-10 μM) concentration-dependently potentiated ACh (100μM)- and EFS (4 Hz)- induced contraction. Maximum potentiation of ACh-contraction in presence of alprostadil was 40 ± 5%. Sildenafil potentiated ACh-induced contraction at low concentrations (0.01-1 μM), but inhibited it at higher ones (10-100 μM). IBMX (non-selective PDE-inhibitor, 0.01-100μM) and SNP (NO-donor, 1nM-1 mM) produced the same biphasic pattern. The potentiatory phase of sildenafil was inhibited by atropine (0.1μM), L-NAME (non-selective NOS-inhibitor, 100μM), N-PLA (nNOS-inhibitor, 30μM) or MB (nonselective GC-inhibitor, 10μM). In presence of sildenafil (0.1μM), the concentration-response curve of alprostadil (0.01-10μM) on both ACh and EFS-induced contraction was clearly shifted downward.

CONCLUSIONS

A crosstalk between PGE₁ and NO/cGMP pathways may exist. At low concentrations only, the effect of sildenafil on bladder contractility is dependent on NO/cGMP. cGMP intracellularly-elevated by sildenafil, may inhibit the activity of PLC and hence the cascade of EP₁-receptors, thus masking the hyperactivity of bladder caused by alprostadil, which adds to the advantages of this combination.

Hypoactivity of rat detrusor muscle in a model of cystitis: exacerbation by non-selective COX inhibitors and amelioration by a selective DP1 receptor antagonist

Various studies have confirmed that prostaglandins (PG) alter the bladder motor activity and micturition reflex in both human and animals. However, no sufficient data is reported about the effect of cyclooxygenase (COX) inhibitors neither in normal bladder physiology nor in pathological conditions. This study aims to compare the potential effects of some COX inhibitors with varying COX-1/COX-2 selectivities (indomethacin, ketoprofen, and diclofenac) with that of the selective COX-2 inhibitor (DFU) on bladder function. The role played by some PGs and their receptors in controlling detrusor muscle function in normal condition and in cystitis is also studied. Organ bath experiments were performed using isolated rat detrusor muscle. Direct and neurogenic contractions were induced using ACh and electric stimulation (EFS), respectively. A model of hemorrhagic cystitis was induced by single injection of cyclophosphamide (300 mg/kg) in rats, and confirmed by histophathological examination. Results are expressed as mean ± SEM of 5-9 rats. Alprostadil and iloprost (1 nM- 10 µM) concentration-dependently potentiated ACh (100 μM)- and EFS (4 Hz)-induced contraction, with maximum potentiation of 40.01 ± 5.29 and 27.59 ± 6.64%, respectively, in case of ACh contractions. In contrast, ONO-AE1-259 (selective EP₂ agonist, 1 nM-10 μM) inhibited muscle contraction. SC51322 (EP₁-antagonist, 10 μM) and RO1138452 (IP antagonist, 10 μM) inhibited both direct and neurogenic responses. Hemorrhagic cystitis reduced both ACh and EFS responses as well as the potentiatory effect of iloprost and the inhibitory effect of RO1138452 on ACh contractions. ONO-AE3-237 (DP₁ antagonist, 1 μM) significantly potentiated contractions in cystitis but showed no effect in normal bladder. A significant inhibition of contractile response was observed in presence of indomethacin, ketoprofen, and diclofenac at all tested concentrations (20, 50, and 100 μM). Highest effect was induced by diclofenac. The effect of these COX inhibitors on EFS contractions was intensified in case of cystitis, indomethacin being the most potent. Atropine (1 nM) significantly reduced indomethacin effect on ACh contraction only in normal rats. On the other hand, DFU (10^-6 M) significantly potentiated the contractile effect of ACh in case of cystitis although it showed no effect in normal rats. EP₁ receptors seem to play an important role in rat bladder contractility. DP₁ receptors as COX-2, on the other hand, gain an important role only in case of cystitis. The use of non-selective COX inhibitors in cystitis may be associated with bladder hypoactivity; selective COX-2 inhibitors may be a safer option.

Single Administration of HBK-15-a Triple 5-HT1A, 5-HT7, and 5-HT3 Receptor Antagonist-Reverses Depressive-Like Behaviors in Mouse Model of Depression Induced by Corticosterone

Studies suggest that the blockade of 5-HT1A, 5-HT7, and 5-HT3 receptor may increase the speed of antidepressant response. 1-[(2,6-Dimethylphenoxy)ethoxyethyl]-4-(2-methoxyphenyl)piperazine hydrochloride (HBK-14) and 1-[(2-chloro-6-methylphenoxy)ethoxyethyl]-4-(2-methoxyphenyl)piperazine hydrochloride (HBK-15), dual 5-HT1A and 5-HT7 antagonists, showed significant antidepressant- and anxiolytic-like properties in our previous tests in rodents. In this study, we aimed to investigate their antidepressant potential using mouse model of corticosterone-induced depression. We chose sucrose preference test, forced swim test, and elevated plus maze to determine anhedonic-, antidepressant-, and anxiolytic-like activities. We also evaluated the influence of the active compound on brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) levels in the hippocampus. Moreover, for both compounds, we performed biofunctional (5-HT3 receptor) and pharmacokinetic studies. We found that HBK-14 and HBK-15 were potent 5-HT3 receptor antagonists. HBK-14 (2.5 mg/kg) and HBK-15 (1.25 mg/kg) after intravenous (i.v.) and intraperitoneal (i.p.) administration permeated the blood-brain barrier with brain/plasma ratio lower than 1. The bioavailability of studied compounds after i.p. administration was 15% for HBK-14 and 54% for HBK-15. Chronic administration of HBK-15 (1.25 mg/kg) and fluoxetine (10 mg/kg) protected corticosterone-treated mice from anhedonic-, depressive-, and anxiety-like behaviors, as well as decreases in BDNF and NGF levels in the hippocampus. HBK-14 (2.5 mg/kg) counteracted anxiety-like behaviors in corticosterone-treated mice. Single administration of HBK-15 (1.25 mg/kg) and ketamine (1 mg/kg) reversed depression-like behavior and regulated decreased BDNF level in the hippocampus in corticosterone-treated mice. Our results suggest that simultaneous blockade of serotonergic 5-HT1A, 5-HT7, and 5-HT3 receptors might accelerate antidepressant response.

Prostaglandin D2 effects and DP1 /DP2 receptor distribution in guinea pig urinary bladder out-flow region

The proximal urethra and urinary bladder trigone play important roles in continence. We have previously shown that PGD₂ is released from guinea pig bladder urothelium/suburothelium and can inhibit detrusor contractile responses. We presently wished to investigate PGD₂ actions in guinea pig out‐flow region and the distribution of DP₁/DP₂ receptors. The effects of PGD₂ on urothelium‐intact trigone and proximal urethra contractility were studied in organ bath experiments. Expression of DP₁/DP₂ receptor proteins was analysed by western blot. Immunohistochemistry was used to identify distribution of DP₁/DP₂ receptors. PGD₂ in a dose‐dependent manner inhibited trigone contractions induced by electrical field stimulation (EFS) and inhibited spontaneous contractions of the proximal urethra. PGD₂ was equally (trigone) or slightly less potent (urethra) compared with PGE₂. Expression of DP₁ and DP₂ receptors was found in male guinea pig bladder trigone, neck and proximal urethra. In the trigone and proximal urethra, DP₁ receptors were found on the membrane of smooth muscle cells and weak immunoreactivty was observed in the urothelium. DP₂ receptors were distributed more widespread, weakly and evenly in the urothelium and smooth muscles. Inhibitory effects by PGD₂ on motor activity of guinea pig trigone and proximal urethra are consistent with finding DP₁ and DP₂ receptors located in the urothelium and smooth muscle cells of the trigone and proximal urethra, and PGD₂ may therefore be a modulator of the bladder out‐flow region, possibly having a function in regulation of micturition and a role in overactive bladder syndrome.

Receptors involved in the modulation of guinea pig urinary bladder motility by prostaglandin D2

BACKGROUND AND PURPOSE

We have described a urothelium-dependent release of PGD2 -like activity which had inhibitory effects on the motility of guinea pig urinary bladder. Here, we have pharmacologically characterized the receptors involved and localized the sites of PGD2 formation and of its receptors.

EXPERIMENTAL APPROACH

In the presence of selective DP and TP receptor antagonists alone or combined, PGD2 was applied to urothelium-denuded diclofenac-treated urinary bladder strips mounted in organ baths. Antibodies against PGD2 synthase and DP1 receptors were used with Western blots and for histochemistry.

KEY RESULTS

PGD2 inhibited nerve stimulation -induced contractions in strips of guinea pig urinary bladder with estimated pIC50 of 7.55 ± 0.15 (n = 13), an effect blocked by the DP1 receptor antagonist BW-A868C. After blockade of DP1 receptors, PGD2 enhanced the contractions, an effect abolished by the TP receptor antagonist SQ-29548. Histochemistry revealed strong immunoreactivity for PGD synthase in the urothelium/suburothelium with strongest reaction in the suburothelium. Immunoreactive DP1 receptors were found in the smooth muscle of the bladder wall with a dominant localization to smooth muscle membranes.

CONCLUSIONS AND IMPLICATIONS

In guinea pig urinary bladder, the main effect of PGD2 is an inhibitory action via DP1 receptors localized to the smooth muscle, but an excitatory effect via TP receptors can also be evoked. The urothelium with its suburothelium might signal to the smooth muscle which is rich in PGD2 receptors of the DP1 type. The results are important for our understanding of regulation of bladder motility.

Recent applications of 1,3-thiazole core structure in the identification of new lead compounds and drug discovery

1,3-Thiazole is one of the most important scaffolds in heterocyclic chemistry and drug design and discovery. It is widely found in diverse pharmacologically active substances and in some naturally-occurring compounds. Thiazole is a versatile building-block for lead generation, and is easily access of diverse derivatives for subsequent lead optimization. In the recent years, many thiazole derivatives have been synthesized and subjected to varied biological activities. In this article we intended to review the most important biological effects of thiazole-based compounds and highlight their roles in new leads identification and drug discovery. This article is also intended to help researches for finding potential future directions on the development of more potent and specific analogs of thiazole-based compounds for various biological targets.

Rationale for the use of prostaglandins and phosphodiesterase inhibitors in the treatment of functional bladder disorders

In this paper a general discussion of the available data on the role of prostaglandin (PG) and phosphodiesterase is discussed. Functional studies would be a next step to understand the functional meaning of the data described in this paper. The data presented are a basis for further research on selective modulation of the EP1 and EP2 receptor which could be a therapeutic target in functional bladder disorders such as OAB. PDE inhibitors are closer to clinical use, as these drugs have been studied and registered for other indications such as erectile dysfunction in men. Therefore, in vivo studies in human subjects can be conducted on short term. However, from a scientific point of view, it is very important to unravel the exact site of action and role of PDE inhibition with in vitro and in vivo studies as is the case with PG. In this way, a combination of drugs targeting different mechanisms involved in bladder physiology such as PG, cGMP, cAMP, and muscarinic receptors, could reduce side effects and improve efficacy.

Synergistic effects of loxoprofen and glycine on the micturition reflex in conscious rats

We examined the inhibitory effects of loxoprofen, a cyclooxygenase inhibitor, and glycine, a major inhibitory neurotransmitter, on the micturition reflex in conscious rats and hypothesized that these drugs would interact synergistically to inhibit micturition. Voiding behaviors were assessed using a metabolic cage. Oral loxoprofen decreased the urinary frequency, and only a high dose(10 mg/kg) significantly reduced the voided volume. With cystometry, intravenous loxoprofen(0.1-3 mg/kg) and glycine (30 and 100 mg/kg) prolonged the intercontraction intervals (ICI) in adose-dependent manner, but did not change the maximum voiding pressure (MVP) in conscious rats. The combination of loxoprofen (3 mg/kg) and glycine (100 mg/kg) strongly prolonged the ICI more than with either drug alone. The lowest dose of loxoprofen (0.1 mg/kg) and glycine(30 mg/kg) did not affect either the ICI or the MVP, but their combination resulted in a significant increase in the ICI. These results suggest that the combined administration of loxoprofen and glycine produced a synergistic inhibitory effect on the micturition reflex.

Hit-to-lead optimization of 2-(1H-pyrazol-1-yl)-thiazole derivatives as a novel class of EP1 receptor antagonists

We describe a medicinal chemistry approach to generate a series of 2-(1H-pyrazol-1-yl)thiazole compounds that act as selective EP1 receptor antagonists. The obtained results suggest that compound 12 provides the best EP1 receptor antagonist activity and demonstrates good oral pharmacokinetics.

Prostaglandin E2 induces spontaneous rhythmic activity in mouse urinary bladder independently of efferent nerves

BACKGROUND AND PURPOSE

The acute effects of PGE(2) on bladder smooth muscle and nerves were examined to determine the origin of PGE(2)-induced spontaneous rhythmic contractions.

EXPERIMENTAL APPROACH

Contraction studies, confocal Ca(2+) imaging and electrophysiological recordings in strips of mouse urinary bladder were used to differentiate the effects of PGE(2) on bladder smooth muscle and efferent nerves.

KEY RESULTS

PGE(2) (50 µM) increased the tone and caused phasic contractions of detrusor smooth muscle strips. Confocal Ca(2+) imaging showed that PGE(2) increased the frequency of whole-cell Ca(2+) transients (WCTs) (72 ± 5%) and intracellular recordings showed it increased the frequency of spontaneous depolarizations, from 0.31·s(-1) to 0.90·s(-1). Non-selective inhibition of EP receptors using SC-51322 and AH-6809 (10 µM), or the L-type Ca(2+) channel blocker nifedipine (1 µM), prevented these phasic contractions and WCTs, and reduced the tone (by 45 ± 7% and 59 ± 6%, respectively). Blocking P2X1 receptors with NF449 (10 µM) caused a small but significant reduction in the frequency of PGE(2)-induced phasic contractions (24 ± 9%) and WCTs (28 ± 17%) but had no significant effect on spontaneous depolarizations or tone. Inhibiting muscarinic receptors with cyclopentolate (1 µM) had no significant effect on these measures. Spontaneous WCTs became synchronous in PGE(2), implying enhanced functional coupling between neighbouring cells. However, the electrical input resistance was unchanged.

CONCLUSIONS AND IMPLICATIONS

It was concluded that depolarization alone is sufficient to explain a functional increase in intercellular coupling and the ability of PGE(2) to increase detrusor spontaneous rhythmic activity does not require parasympathetic nerves.

Increased high-sensitivity C-reactive protein predicts a high risk of lower urinary tract symptoms in Chinese male: Results from the Fangchenggang Area Male Health and Examination Survey

BACKGROUND

Reports have shown that increased serum C-reactive protein (CRP) suggests a risk of lower urinary tract symptoms (LUTS) in the West population. However, few studies have investigated the role of CRP as regards LUTS in a Chinese male population.

METHODS

Data were collected from 1,452 men who participated in the population-based Fangchenggang Area Male Health and Examination Survey (FAMHES), which was carried out in Guangxi, China, from September 2009 to December 2009. In the current study, serum CRP was measured with a high-sensitivity method (hsCRP) and LUTS was assessed by International Prostate Symptom Score (IPSS). Meanwhile, information about potential confounding variables (smoking, hypertension, diabetes, etc.) were included.

RESULTS

We observed that statistically significant distinction presented in the distribution of hsCRP levels and age between LUTS group and non-LUTS group (P < 0.001). Comparing with the lowest hsCRP tertile, men with the highest hsCRP tertile were 1.72 times more likely to have overall LUTS and 1.93 times more likely to have irritative symptoms. As for individual symptoms of LUTS, statistically significant correlations were noted between serum hsCRP levels and urgency (OR = 1.74, 95% CI = 1.09-2.78) and nocturia (OR = 1.64, 95% CI = 1.18-2.27), when comparing them from the 1st to 3rd hsCRP tertiles. After multivariate adjusted, the results changed slightly and were still significant.

CONCLUSIONS

In a Chinese male population, we firstly confirmed a positive correlation of serum hsCRP with LUTS. It can be inferred that inflammation may be involved in the processes of LUTS.

Long-term effect of loxoprofen sodium on nocturia in patients with benign prostatic hyperplasia

Purpose

We evaluated the long-term effects of loxoprofen on nocturia in patients with benign prostatic hyperplasia (BPH).

Materials and Methods

Between January 2006 and December 2008, 40 BPH patients with 2 or more episodes of nocturia received an alpha-blocker, 5-alpha reductase inhibitor, and a single dose of 60 mg of loxoprofen at night before sleep for 12 months (Group I). During the same period, 38 BPH patients selected as the control group received an alpha-blocker and 5-alpha reductase inhibitor (Group II). Patients were reevaluated after 3, 6, and 12 months of treatment by the number of nocturia episodes and side effects.

Results

After 3 months of treatment, the number of nocturia episodes decreased significantly compared with baseline in both group I and group II (1.9±0.7, 2.1±0.7, respectively, p<0.05). The degree of decrease in nocturia was significantly different between the groups (-1.5±0.9, -1.1±0.9, respectively, p=0.034). After 6 and 12 months, the number of nocturia episodes decreased significantly compared with baseline in both group I and group II (p<0.05), but the degree of decrease was not significantly different between the groups (p>0.05). After 6 and 12 months of treatment in group I, treatment-emergent adverse events, including 5 cases of gastric discomfort (12.5%), 3 cases of leg edema (7.5%), and 1 case of decreased urine volume (2.5%), occurred in 9 of the 40 (22.5%) patients.

Conclusions

Loxoprofen can be an effective treatment for patients with nocturia secondary to BPH in the short term. Long-term use of loxoprofen is not recommended because of the side effects.

Linear measurement of cell contraction in a capillary collagen gel system

Three-dimensional collagen gel contraction is the standard assay utilized for functionally quantifying a variety of cell types, in particular smooth muscle cells (SMCs) and myofibroblasts. Here, we have developed a method to effectively reduce the three-dimensional parameters of the standard collagen gel into a single, linear measurement. Cell/collagen suspensions that are cast into glass capillary tubes provide several advantages over the well plate format, such as eliminating the need for digital imaging equipment and software to quantify the amount of cellular contraction. In addition, capillary tube gels require significantly fewer cells and far less reagents than standard methods.

Urodynamic Effects of Propiverine on Detrusor Overactivity and Abdominal Straining during Voiding in Awake Rats with Intravesical Prostaglandin E2Instillation

Purpose

We investigated the effect of propiverine on cystometric parameters based on intraabdominal pressure (IAP) in awake rats in an overactive bladder (OAB) model induced by intravesical instillation of prostaglandin E₂ (PGE₂).

Materials and Methods

Twenty-two female Sprague-Dawley rats were used. Polyethylene catheters were implanted into the bladder to record the intravesical pressure (IVP) and into the femoral artery to administer medication. A balloon-fitted catheter was positioned in the abdominal cavity to record the IAP. Awake cystometries were performed before and after intraarterial administration of propiverine 1 mg/kg (n=6), intravesical administration of 50µM PGE₂ only (n=6), or intravesical PGE₂ plus 1 mg/kg (n=4) or 3 mg/kg (n=6) of intraarterial propiverine. Cystometric pressure and volume parameters and variables related to detrusor overactivity (DO) were investigated.

Results

Rats administered intravesical PGE₂ showed increased pressure parameters and decreased volume parameters comparable to the DO model, which was effectively prevented by propiverine (1 or 3 mg/kg). Typical DO shown during the filling phase was decreased by intraarterial propiverine (3 mg/kg) injection. After propiverine (3 mg/kg) injection, IAP was increased at the time of micturition pressure with or without threshold pressure (p<0.05, p<0.01) depending on the dose administered.

Conclusions

Propiverine improved pressure- and volume-related parameters in an OAB model. Furthermore, it also decreased the frequency of DO. However, higher concentrations of propiverine induced straining voiding.

Prostanoid receptor antagonists: development strategies and therapeutic applications

Identification of the primary products of cyclo-oxygenase (COX)/prostaglandin synthase(s), which occurred between 1958 and 1976, was followed by a classification system for prostanoid receptors (DP, EP(1), EP(2) ...) based mainly on the pharmacological actions of natural and synthetic agonists and a few antagonists. The design of potent selective antagonists was rapid for certain prostanoid receptors (EP(1), TP), slow for others (FP, IP) and has yet to be achieved in certain cases (EP(2)). While some antagonists are structurally related to the natural agonist, most recent compounds are 'non-prostanoid' (often acyl-sulphonamides) and have emerged from high-throughput screening of compound libraries, made possible by the development of (functional) assays involving single recombinant prostanoid receptors. Selective antagonists have been crucial to defining the roles of PGD(2) (acting on DP(1) and DP(2) receptors) and PGE(2) (on EP(1) and EP(4) receptors) in various inflammatory conditions; there are clear opportunities for therapeutic intervention. The vast endeavour on TP (thromboxane) antagonists is considered in relation to their limited pharmaceutical success in the cardiovascular area. Correspondingly, the clinical utility of IP (prostacyclin) antagonists is assessed in relation to the cloud hanging over the long-term safety of selective COX-2 inhibitors. Aspirin apart, COX inhibitors broadly suppress all prostanoid pathways, while high selectivity has been a major goal in receptor antagonist development; more targeted therapy may require an intermediate position with defined antagonist selectivity profiles. This review is intended to provide overviews of each antagonist class (including prostamide antagonists), covering major development strategies and current and potential clinical usage.

The effect of endothelin-1 on the production of interleukin-6 in cultured human detrusor smooth muscle cells, and the effect of interleukin-6 on the contractile response of bladder smooth muscle strips from rats

OBJECTIVE

To determine the effect of endothelin-1 (ET-1) on the production of interleukin-6 (IL-6) in cultured human detrusor smooth muscle cells (HDSMCs) and the effect of IL-6 on the contractile response of bladder smooth muscle strips from rats.

MATERIALS AND METHODS

The expression of IL-6 mRNA and production of IL-6 protein in cultured HDSMCs treated with the different concentrations of ET-1 were assayed by reverse transcriptase-polymerase chain reaction and specific enzyme-linked immunosorbent assay, respectively. The strips from Sprague-Dawley rats were either untreated or treated with 1 ng/mL of IL-6 for 60 min. Using increasing cumulative concentrations of acetylcholine (ACh), bethanechol (BCh), or sodium nitroprusside, we assessed the concentration-contraction or the relaxation responses. In cystitis-induced strips, change of contractions induced by noradrenaline (NA) with or without treatment of IL-6 were assessed. The IL-6-treated strips were incubated for 30 min in the presence or absence indomethacin or SQ29548, and then the effects on ACh- or BCh-induced contractions were measured.

RESULTS

The expression of IL-6 mRNA and the production of IL-6 protein on the cultured HDSMCs pretreated by ET-1 were significantly higher than in the control (P<0.05). The ACh- and BCh-induced contractions were increased in the IL-6 pretreated strips from both dome and trigone, regardless of the presence of urothelium (P<0.05). The presence of cystitis augmented the NA-induced contractions (P<0.05). The contractions induced by ACh and BCh were inhibited by indomethacin and SQ29548.

CONCLUSIONS

ET-1 induces expression of IL-6 mRNA and production of IL-6 protein on HDSMCs. IL-6 enhances detrusor smooth muscle contractility via the muscarinic or adrenergic receptor pathway.

Inflammatory Mechanisms Associated with Prostatic Inflammation and Lower Urinary Tract Symptoms

Inflammation is a common finding in histologic prostate specimens obtained from aging men, and accumulating data suggest that inflammation may play an important role in the development of benign prostatic hyperplasia (BPH), and the development and progression of lower urinary tract symptoms (LUTS). Inflammatory processes may contribute to prostatic enlargement directly through stimulation of prostate growth, or, alternatively, through decreasing prostatic apoptosis. Additionally, inflammatory processes may impact other components of the urogenital tract, such as the bladder, and contribute to the LUTS that may be experienced both in the presence and in the absence of prostate enlargement. Current research therefore offers clues about converging inflammatory pathways which may be targeted to improve treatment of BPH and/or LUTS as well as identifying potential targets for prevention of these syndromes.

Enhanced bladder capacity and reduced prostaglandin E2-mediated bladder hyperactivity in EP3 receptor knockout mice

Nonsteroidal anti-inflammatory cyclooxygenase inhibitors that function to reduce prostaglandin E2 (PGE2) production have been widely reported as effective agents in models of urinary bladder overactivity. We therefore investigated a potential role for the PGE2 receptor, EP3, in urinary bladder function by performing conscious, freely moving cystometry on EP3 receptor knockout (KO) mice. EP3 KO mice demonstrated an enhanced bladder capacity compared with wild-type (WT) mice ( approximately 185% of WT) under control conditions, based on larger voided and infused bladder volumes. Infusion of the EP3 receptor agonist GR63799X into the bladder of WT mice reduced the bladder capacity. This was ineffective in EP3 KO mice that demonstrated a time-dependent increase in bladder capacity with GR63799X, an effect similar to that observed with vehicle in both genotypes. In addition, infusion of PGE2 into WT mice induced bladder overactivity, an effect that was significantly blunted in the EP3 KO mice. The data reported here provide the first evidence supporting a functional role for EP3 receptors in normal urinary bladder function and implicate EP3 as a contributor to bladder overactivity during pathological conditions of enhanced PGE2 production, as reported previously in overactive bladder patients.

Thromboxane A2: physiology/pathophysiology, cellular signal transduction and pharmacology

Thromboxane A(2) (TXA(2)), an unstable arachidonic acid metabolite, elicits diverse physiological/pathophysiological actions, including platelet aggregation and smooth muscle contraction. TXA(2) has been shown to be involved in allergies, modulation of acquired immunity, atherogenesis, neovascularization, and metastasis of cancer cells. The TXA(2) receptor (TP) communicates mainly with G(q) and G(13), resulting in phospholipase C activation and RhoGEF activation, respectively. In addition, TP couples with G(11), G(12), G(13), G(14), G(15), G(16), G(i), G(s) and G(h). TP is widely distributed in the body, and is expressed at high levels in thymus and spleen. The second extracellular loop of TP is an important ligand-binding site, and Asp(193) is a key amino acid. There are two alternatively spliced isoforms of TP, TPalpha and TPbeta, which differ only in their C-terminals. TPalpha and TPbeta communicate with different G proteins, and undergo hetero-dimerization, resulting in changes in intracellular traffic and receptor protein conformations. TP cross-talks with receptor tyrosine kinases, such as EGF receptor, to induce cell proliferation and differentiation. TP is glycosylated in the N-terminal region for recruitment to plasma membranes. Furthermore, TP conformation is changed by coupling to G proteins, showing several states of agonist binding. Finally, several drugs modify TP-mediated events; these include cyclooxygenase inhibitors, TXA(2) synthase inhibitors and TP antagonists. Some flavonoids of natural origin also have TP receptor antagonistic activity. Recent advances in TP research have clarified TXA(2)-mediated events in detail, and further study will supply more beneficial information about TXA(2) pathophysiology.

The effects of exogenous prostaglandins and the identification of constitutive cyclooxygenase I and II immunoreactivity in the normal guinea pig bladder

OBJECTIVES

To establish the functional consequences of exposing the isolated whole bladder preparation to exogenous prostaglandins (PGE(1), PGE(2), PGF(2alpha)) and to determine which cells express cyclooxygenase (COX) types I and II, to generate PG to effect these changes in vivo.

MATERIALS AND METHODS

Fifteen female guinea pigs (270-350 g) were used, i.e. seven for structural studies and eight for physiological measurement. For the structural study pieces of the lateral wall were incubated separately in Krebs' solution at 36 degrees C, gassed with 95% O(2) and 5% CO(2) with 1 mm isobutyl-methyl-xanthene. Individual pieces were then exposed to 100 microm of the nitric oxide (NO) donor NONOate for 10 min; control tissues remained in Krebs' solution. Tissues were then fixed in 4% paraformaldehyde. For the physiological experiments bladders were isolated and a cannula inserted into the urethra to monitor intravesical pressure. The bladders were suspended in a chamber containing carboxygenated physiological solution at 33-36 degrees C. All drugs were added to the abluminal bladder surface.

RESULTS

In the resting bladder there were small spontaneous transient rises in pressure, i.e. autonomous activity. Exposure to PGE(2) (3-300 nM) resulted in an increase in basal pressure on which were superimposed autonomous activity, which was increased both in amplitude and frequency. The changes in the amplitude and frequency depended on the concentration of PGE(2). After a brief exposure (240 s) to PGE(2) the augmentation of the autonomous activity continued for >60 min despite regular washing. The responses were similar with PGE(1) but the responses to PGF(2alpha) and arachidonic acid were reduced. The augmented activity was reduced by the EP1/EP2 receptor blocking agent AH6809 (10 microm). Using an antibody to the 70 kDa constitutive form (COX I), COX I immunoreactivity (COX I-IR) was located in cells in the basal urothelium, in lamina propria and cells on the surface of the inner muscle bundles. There were few COX I-IR cells associated with the outer muscle bundles. The COX I-IR cells lying within the lamina propria were distinct from the suburothelial cells which respond to NO with an increase in cGMP. The lamina propria COX I-IR cells appeared to form a network surrounding muscle trabeculae within the inner muscle layer. COX II-IR was associated with the nuclei of cells in the urothelium, lamina propria and muscle.

CONCLUSIONS

These data show that PGs regulate autonomous activity. Potential sources of endogenous PG were identified. It is unclear how the PGs produced by these cells alter autonomous activity. There might be a direct activation of the muscle by PGs released by the network of superficial muscle interstitial cells, or PG released from the urothelium might influence phasic contractile activity via networks of COX I-IR interstitial cells. The possible roles and importance of this mechanism for bladder physiology and pathology are discussed.

Latanoprost-related transient incontinence

Latanoprost has increasingly become the first choice in topical anti-glaucoma therapy. Local adverse events like hypertrichosis and increased iris pigmentation are common whereas systemic adverse events have been rare and mild in intensity. The authors would like to report a case of transient urge incontinence after initiation of latanoprost therapy confirmed by challenge-rechallenge tests and speculate on the causal relationship.

Activation of the central cholinergic system mediates the reversal of hypotension by centrally administrated U-46619, a thromboxane A2 analog, in hemorrhaged rats

In the present study, we investigated the role of the central cholinergic system in mediating the pressor effect of intracerebroventricularly administrated U-46619, a thromboxane A2 (TxA2) analog, in hemorrhaged hypotensive rats. Hemorrhage was performed by withdrawing a total volume of 2.1 ml of blood per 100 g body weight over a period of 10 min. Intracerebroventricular (i.c.v.) injection of U-46619 (0.5, 1, 2 micro g) produced a dose- and time-dependent increase in arterial pressure and reversed the hypotension of this condition. Hemorrhage caused small increases in extracellular hypothalamic acetylcholine and choline levels. Intracerebroventricular administration of U-46619 (1 micro g) further increased the levels of extracellular acetylcholine and choline by 57% and 41%, respectively. Pretreatment with SQ-29548 (8 mug; i.c.v.), a selective TxA2 receptor antagonist, completely abrogated the effects of subsequent injection of U-46619 (1 mug; i.c.v.) on arterial pressure and extracellular acetylcholine and choline levels. Pretreatment with mecamylamine (50 micro g; i.c.v.), a cholinergic nonselective nicotinic receptor antagonist, attenuated the pressor effect of U-46619 (1 micro g, i.c.v.) in hemorrhaged rats whereas pretreatment with atropine (10 micro g; i.c.v.), a cholinergic nonselective muscarinic receptor antagonist, had no effect. Interestingly, pretreatment of rats with methyllycaconitine (10 micro g; i.c.v.) or alpha-bungarotoxin (10 micro g; i.c.v.), selective antagonists of alpha-7 subtype nicotinic acetylcholine receptors (alpha7nAChRs), partially abolished the pressor effect of U-46619 (1 micro g; i.c.v.) in the hypotensive condition. Pretreatment with a combination of mecamylamine plus methyllycaconitine or mecamylamine plus alpha-bungarotoxin attenuated the reversal effect of U-46619, but only to the same extent as pretreatment with either antagonist alone. In conclusion, i.c.v. administration of U-46619 restores arterial pressure and increases posterior hypothalamic acetylcholine and choline levels by activating central TxA2 receptors in hemorrhaged hypotensive rats. The activation of central nicotinic cholinergic receptors, predominantly alpha7nAChRs, partially acts as a mediator in the pressor responses to i.c.v. injection of U-46619 under these conditions.

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.

Contractile mechanisms coupled to TRPA1 receptor activation in rat urinary bladder

TRPA1 is a member of the transient receptor potential (TRP) channel family present in sensory neurons. Here we show that vanilloid receptor (TRPV1) stimulation with capsaicin and activation of TRPA1 with allyl isothiocyanate or cinnamaldehyde cause a graded contraction of the rat urinary bladder in vitro. Repeated applications of maximal concentrations of the agonists produce desensitization to their contractile effects. Moreover, contraction caused by TRPA1 agonists generates cross-desensitization with capsaicin. The TRP receptor antagonist ruthenium red (10-100 microM) inhibits capsaicin (0.03 microM), allyl isothiocyanate (100 microM) and cinnamaldehyde (300 microM)-induced contractions in the rat urinary bladder. The selective TRPV1 receptor antagonist SB 366791 (10 microM) blocks capsaicin-induced contraction, but partially reduces allyl isothiocyanate- or cinnamaldehyde-mediated contraction. However, allyl isothiocyanate and cinnamaldehyde (10-1000 microM) completely fail to interfere with the specific binding sites for the TRPV1 agonist [(3)H]-resiniferatoxin. Allyl isothiocyanate or cinnamaldehyde-mediated contractions of rat urinary bladder, which rely on external Ca(2+) influx, are significantly inhibited by tachykinin receptor antagonists as well as by tetrodotoxin (1 microM) or indomethacin (1 microM). Allyl isothiocyanate-induced contraction is not changed by atropine (1 microM) or suramin (300 microM). The exposure of urinary bladders to allyl isothiocyanate (100 microM) causes an increase in the prostaglandin E(2) and substance P levels. Taken together, these results indicate that TRPA1 agonists contract rat urinary bladder through sensory fibre stimulation, depending on extracellular Ca(2+) influx and release of tachykinins and cyclooxygenase metabolites, probably prostaglandin E(2). Thus, TRPA1 appears to exert an important role in urinary bladder function.

Effect of cyclooxygenase inhibitors on the micturition reflex in rats: correlation with inhibition of cyclooxygenase isozymes

OBJECTIVE

To investigate the role of cyclooxygenase (COX) isozymes (COX-1 and -2) in the regulation of bladder volume capacity (BVC) in several rat urodynamic models, using a selection of nonsteroidal anti-inflammatory drugs (NSAIDs), some selective for COX-2, correlating the potency of the tested compounds in the urodynamic models and their in vitro potency as inhibitors of COX isozymes, to verify the relative importance of the different isozymes.

MATERIALS AND METHODS

The effects of an i.v. administration of several nonselective and selective COX-2 inhibitors (indomethacin, meloxicam, naproxen, aspirin, paracetamol, flurbiprofen, nimesulide, NS-398, celecoxib, rofecoxib and L 745337) on bladder filling and voiding were evaluated in conscious and anaesthetized rats by cystometry. The cystometry was done in conscious rats 1 day after catheter implantation, by filling the bladder with dilute acetic acid (0.2%) or saline, and again with saline 5 days after catheterization. Effects on isovolumic bladder contractions in anaesthetized rats were also evaluated.

RESULTS

All the NSAIDs tested dose-dependently increased BVC; their potency at increasing BVC during infusion of the bladder with acetic acid was similar to that evaluated with saline on cystometry 1 day after catheterization. When a nonselective (naproxen) and a selective (nimesulide) COX-2 inhibitor were tested in rats with bladders infused with saline 5 days after catheterization, their effects on BVC were significantly lower than those evaluated at 1 day. All tested compounds dose-dependently inhibited isovolumic bladder contractions in anaesthetized rats. There was a good correlation between the potency in inhibiting the isovolumic bladder contractions in anaesthetized rats and in increasing BVC during cystometry in conscious rats with the bladder infused with acetic acid. The potency of the compounds in the cystometry model with bladders infused with acetic and in the isovolumic bladder voiding contractions correlated well with COX-2 inhibition, but not COX-1.

CONCLUSIONS

Both nonselective and COX-2 selective inhibitors are more active in inhibiting the micturition reflex in rats with bladder overactivity caused by bladder irritation than in normal rats. The potency of the anti-inflammatory compounds in inhibiting bladder overactivity induced by chemical or surgical irritation, and their activity in a cystometrographic model practically independent of bladder irritation (isovolumic bladder contractions in anaesthetized rats), was related to the potency as inhibitors of COX-2 isozyme. This suggests that the involvement of prostaglandins in the micturition reflex in rats is mainly mediated by this isozyme.

Urinary nitrite excretion and urinary variables in patients with primary nocturnal frequency of micturition: effects of indomethacin suppositories

Urinary nitrite excretion was measured in patients with primary nocturnal frequency of micturition (PNFM) and in normal individuals. Effects of indomethacin suppository on urine volume and other urinary variables were evaluated. The study comprised seven patients with PNFM and seven healthy control (age range 30-45 years). Nitrite was assayed in spot morning urine samples; urine volume, urine osmolality and electrolytes, serum osmolality and electrolytes and functional bladder capacity (FBC) were assayed. Both groups were then given 100 mg of indomethacin suppository daily for a maximum of 10 days and urinary variables were re-evaluated during day 10. Results showed that urinary nitrite excretion of patients with PNFM was greater than that of the normal subjects (230+/-62 umol/l vs. 42+/-30 umol/l, P<0.05). The mean (SD) 24 h urine volume and osmolality, the night urine volume and osmolality, serum osmolality, FBC, creatinine clearance, fractional excretion of sodium (FENa), fractional excretion of potassium (FEK), and urinary excretion of glucose and potassium were lower in patients with PNFM as compared with normal individuals, although not statistically significantly so, except for FBC that was significantly lower in the patients. Urinary excretion of sodium, calcium, chloride, phosphorus, magnesium, day-night urinary volume ratio, spot morning osmolality, nocturnal index, and nocturnal polyuria index were higher in patients with PNFM. Indomethacin decreased the 24 h urinary volume by 21%, creatinine clearance by 12%, osmolar clearance by 14% and urinary protein excretion by 38% in the patients. These variables decreased by 26, 45, 17 and 12% respectively in the healthy subjects, whereas 24 h urinary protein excretion increased mildly by 9%. Indomethacin increased day-night urinary volume ratio by 73% in the healthy subjects. It might be concluded that urinary nitrite excretion, urinary excretion of sodium, chloride, phosphorus, calcium, and magnesium increased and FBC decreased in patients with PNFM; Indomethacin decreased urinary volume, FENa, FEK, osmolar clearance, and free water clearance in the healthy subjects and the patients. These might explain the mechanism of action of indomethacin to reduce frequency of voiding. The possible interaction of prostaglandin and NO in the pathogenesis of PNFM is discussed.

Loxoprofen inhibits facilitated micturition reflex induced by acetic acid urinary bladder infusion of the rats

Prostaglandins (PGs) are well known as one of the chemical mediators of inflammation. Nonsteroidal anti-inflammatory drugs (NSAIDs), PG synthesis inhibitors, are used for anti-nociception and/or anti-inflammation. We examine the effect of loxoprofen, an NSAID, on micturiton in acetic acid-induced bladder inflammation of the rats. In cystometrogram study with saline infusion into the urinary bladder, loxoprofen did not alter the interval of bladder contraction (IC, 107% of the control). IC was shortened by acetic acid infusion (65% of the control) and loxoprofen prolonged the IC (162% of acetic acid infused period). This prolonged IC was approximately same as the control. Loxoprofen did not alter the threshold pressure and the maximal voiding pressure. These data suggest that PGE2 might not play a part of normal micturition and may play a part of the micturition reflex during acetic acid infusion. That is, loxoprofen might be useful for pathological hyperreflex of the micturition.