Evidence for the involvement of bradykinin in chemically-evoked cystitis in anaesthetized rats

Physiological Roles of Bradykinin and Involvement of Bradykinin B2 Receptor in Urethral Function in Humans and Animals

OBJECTIVE

We investigated the role of bradykinin in urethral function by examining contractile responses in urethral smooth muscle strips isolated from humans and the intraurethral pressure in rats and dogs.

METHODS

The contractile responses of human urethral tissue for bradykinin (0.01-10 µmol/L) were examined, and changes in intraurethral pressure induced by bradykinin (0.003-10 µg/kg) in anesthetized rats or dogs were measured. In addition, the effects of pretreatment with the bradykinin B2 receptor antagonist FK3657 were also examined.

RESULTS

In smooth muscle strips obtained from human urethra, bradykinin induced contraction, which was inhibited by FK3657 in a concentration-dependent manner. In anesthetized rats and dogs, intravenously administered bradykinin dose-dependently increased intraurethral pressure. FK3657 shifted the intraurethral pressure dose-response curve for bradykinin to the right in rats. The bradykinin-induced elevation of intraurethral pressure was also dose-dependently inhibited by FK3657 in dogs.

CONCLUSIONS

The present study provides evidence that bradykinin elicits urethral smooth muscle contraction via the bradykinin B2 receptor, suggesting the potential utility of this receptor as a novel target for the treatment of voiding dysfunction.

Intratesticular Bradykinin Involvement in Rat Testicular Pain Models

OBJECTIVES

To clarify the role of bradykinin in urogenital pain, we investigated bradykinin involvement in rat models of testicular pain.

METHODS

Bradykinin (0.1, 0.3, 1, 3 and 10 mmol/L) or distilled water was injected into the testes of male Wistar rats, and induced pain behaviors in conscious rats were evaluated. The effect of pretreatment with bradykinin B2 receptor antagonist FK3657 on bradykinin-induced pain behavior was then examined. We also evaluated the analgesic effect of FK3657 in a rat acetic acid-induced testicular pain as well as changes in the intratesticular bradykinin concentration after testicular injection of acetic acid.

RESULTS

An injection of bradykinin into the testes of conscious rats induced pain behaviors that were dose-proportionally reduced by prior administration of FK3657. In addition, FK3657 dose-dependently inhibited the pain responses induced by testicular injection of 1% acetic acid. An increase in intratesticular bradykinin concentration was detected after the testicular injection of 1% acetic acid.

CONCLUSIONS

Here, we found that intratesticular bradykinin evokes pain behavior via stimulation of bradykinin B2 receptors and that intratesticular acetic acid injection induces intratesticular bradykinin synthesis, consequently leading to pain behavior. These findings suggest that the potential utility of bradykinin B2 receptor antagonists as a novel target for treating urogenital pain.

Pre- and post-junctional bradykinin B2 receptors regulate smooth muscle tension to the pig intravesical ureter

AIMS

Neuronal and non-neuronal bradykinin (BK) receptors regulate the contractility of the bladder urine outflow region. The current study investigates the role of BK receptors in the regulation of the smooth muscle contractility of the pig intravesical ureter.

METHODS

Western blot and immunohistochemistry were used to show the expression of BK B1 and B2 receptors and myographs for isometric force recordings.

RESULTS

B2 receptor expression was consistently detected in the intravesical ureter urothelium and smooth muscle layer, B1 expression was not detected where a strong B2 immunoreactivity was observed within nerve fibers among smooth muscle bundles. On ureteral strips basal tone, BK induced concentration-dependent contractions, were potently reduced by extracellular Ca(2+) removal and by B2 receptor and voltage-gated Ca(2+) (VOC) channel blockade. BK contraction did not change as a consequence of urothelium mechanical removal or cyclooxygenase and Rho-associated protein kinase inhibition. On 9,11-dideoxy-9a,11a-methanoepoxy prostaglandin F2α (U46619)-precontracted samples, under non-adrenergic non-cholinergic (NANC) and nitric oxide (NO)-independent NANC conditions, electrical field stimulation-elicited frequency-dependent relaxations which were reduced by B2 receptor blockade. Kallidin, a B1 receptor agonist, failed to increase preparation basal tension or to induce relaxation on U46619-induced tone.

CONCLUSIONS

The present results suggest that BK produces contraction of pig intravesical ureter via smooth muscle B2 receptors coupled to extracellular Ca(2+) entry mainly via VOC (L-type) channels. Facilitatory neuronal B2 receptors modulating NO-dependent or independent NANC inhibitory neurotransmission are also demonstrated.

Bradykinin modulates spontaneous nerve growth factor production and stretch-induced ATP release in human urothelium

The urothelium plays a crucial role in integrating urinary bladder sensory outputs, responding to mechanical stress and chemical stimulation by producing several diffusible mediators, including ATP and, possibly, neurotrophin nerve growth factor (NGF). Such urothelial mediators activate underlying afferents and thus may contribute to normal bladder sensation and possibly to the development of bladder overactivity. The muscle-contracting and pain-inducing peptide bradykinin is produced in various inflammatory and non-inflammatory pathologies associated with bladder overactivity, but the effect of bradykinin on human urothelial function has not yet been characterized. The human urothelial cell line UROtsa expresses mRNA for both B1 and B2 subtypes of bradykinin receptors, as determined by real-time PCR. Bradykinin concentration-dependently (pEC50=8.3, Emax 4434±277nM) increased urothelial intracellular calcium levels and induced phosphorylation of the mitogen-activated protein kinase (MAPK) ERK1/2. Activation of both bradykinin-induced signaling pathways was completely abolished by the B2 antagonist icatibant (1μM), but not the B1 antagonist R715 (1μM). Bradykinin-induced (100nM) B2 receptor activation markedly increased (192±13% of control levels) stretch-induced ATP release from UROtsa in hypotonic medium, the effect being dependent on intracellular calcium elevations. UROtsa cells also expressed mRNA and protein for NGF and spontaneously released NGF to the medium in the course of hours (11.5±1.4pgNGF/mgprotein/h). Bradykinin increased NGF mRNA expression and accelerated urothelial NGF release to 127±5% in a protein kinase C- and ERK1/2-dependent manner. Finally, bradykinin up-regulated mRNA for transient-receptor potential vanilloid (TRPV1) sensory ion channel in UROtsa. In conclusion, we show that bradykinin represents a versatile modulator of human urothelial phenotype, accelerating stretch-induced ATP release, spontaneous release of NGF, as well as expression of sensory ion channel TRPV1. Bradykinin-induced changes in urothelial sensory function might contribute to the development of bladder dysfunction.

Involvement of bradykinin in trypsin-induced urinary bladder contraction in cyclophosphamide-treated rats

Protease-activated receptor-2 (PAR-2) is activated by serine proteases, such as trypsin and mast cell tryptase. Previous studies have demonstrated that both trypsin and PAR-2 activating peptide contract isolated rat urinary bladder preparations, however, the mechanisms are not fully understood. In the present study, we examined the role of bradykinin in contractions induced by trypsin and the PAR-2 agonist 2-furoyl-LIGRL-NH(2) in urinary bladders isolated from control or cyclophosphamide (CYP)-induced cystitis rats. The contractile effects of trypsin were significantly greater in the preparations obtained from CYP-treated rats than in those from controls. The bradykinin B2 receptor antagonist Hoe 140 did not affect trypsin-induced contractions in control rat bladders, whereas it significantly reduced the contractile effects of trypsin on bladders from CYP-treated rats. On the other hand, Hoe 140 failed to affect contractions induced by the PAR-2 agonist 2-furoyl-LIGRL-NH(2). These results suggest that the actions of trypsin on urinary bladders in cystitis rats are partly exerted through stimulation of bradykinin B2 receptor in a PAR-2-independent manner. This mechanism seems to be involved in the enhancement of trypsin-induced bladder contractions observed after induction of cystitis with CYP in rats.

Resveratrol prevents bradykinin-induced contraction of rat urinary bladders by decreasing prostaglandin production and calcium influx

Resveratrol, a polyphenol found in grapes and peanuts, exerts beneficial effects on a number of diseases of cardiovascular and central nervous system. However, effects of resveratrol on the urinary system have not been fully investigated. In the present study, we examined effects of resveratrol on bradykinin-induced contraction and release of prostaglandin E2 in isolated rat urinary bladders. The effects of resveratrol on contractions induced by several agonists (prostaglandin E2, prostaglandin F2α and carbachol) and high K+ were also examined. We found that resveratrol concentration-dependently reduced the bradykinin-induced contraction in the rat urinary bladder preparations. The higher concentration of resveratrol (100 μM) abolished the bradykinin-induced prostaglandin E2 release. Similar results were obtained when the cyclooxygenase inhibitor indomethacin (10 μM) was used instead of resveratrol. Resveratrol also attenuated the prostaglandin E2-, prostaglandin F2α-, and to a lesser extent carbachol-induced contractions. Contractile responses to bradykinin, prostaglandin E2 and carbachol were largely prevented by blockade of Ca2+ channels with diltiazem. Both resveratrol and diltiazem prevented contractions induced by an addition of Ca2+ (2.5- 10 mM) into Ca2+-free/50 mMK+ solution or by 50 mMK+ solution containing normal Ca2+ (2.5 mM). These results suggest that resveratrol prevents bradykinin-induced contractions by attenuating not only the production of prostaglandins but also actions of them. The effect of resveratrol on contractile actions seems to be in part due to inhibition of Ca2+ influx. Because bradykinin plays an important role in pathological conditions of urinary bladder function, resveratrol may exert beneficial effects on the urinary bladder diseases.

Involvement of capsaicin-sensitive afferents and the Transient Receptor Potential Vanilloid 1 Receptor in xylene-induced nocifensive behaviour and inflammation in the mouse

The inflammatory actions of xylene, an aromatic irritant and sensitizing agent, were described to be predominantly neurogenic in the rat, but the mechanism and the role of the Transient Receptor Potential Vanilloid 1 (TRPV1) capsaicin receptor localized on a subpopulation of sensory nerves has not been elucidated. This paper characterizes the involvement of capsaicin-sensitive afferents and the TRPV1 receptor in nociceptive and acute inflammatory effects of xylene in the mouse. Topical application of xylene on the paw induced a short, intensive nocifensive behaviour characterized by paw liftings and shakings, which was more intensive in Balb/c than in C57Bl/6 mice. Genetic deletion of the TRPV1 receptor as well as destroying capsaicin-sensitive nerve terminals with resiniferatoxin (RTX) pretreatment markedly reduced, but did not abolish nocifensive behaviours. In respect to the xylene-induced plasma protein extravasation detected by Evans blue leakage, significant difference was neither observed between the Balb/c and C57Bl/6 strains, nor the ear and the dorsal paw skin. These inflammatory responses were diminished in the RTX pretreated group, but not in the TRPV1 gene-deleted one. Injection of the antioxidant N-acetylcysteine 15min prior to xylene smearing significantly reduced plasma protein extravasation at both sites. These results demonstrate that xylene-induced acute nocifensive behaviour is mediated by capsaicin-sensitive afferents via TRPV1 receptor activation in mice. Neurogenic inflammatory components play an important role in xylene-induced plasma protein extravasation, but independently of the TRPV1 ion channel. Reactive oxygen or carbonyl species participate in this process presumably via stimulation of the TRPA1 channel.

Characterization of kinin receptors in human cultured detrusor smooth muscle cells

BACKGROUND AND PURPOSE

Kinins have an important role in inflammatory cystitis and in animal pathophysiological models, by acting on epithelium, fibroblasts, sensory innervation and smooth muscle. The aim of this study was to characterize the receptors responsible for direct motor responses induced by kinins on human detrusor.

EXPERIMENTAL APPROACH

Human detrusor cells from biopsies were isolated and maintained in culture. B(1) and B(2) kinin receptors were characterized by means of radioligand and functional experiments (PI accumulation and PGE(2) release).

KEY RESULTS

[(3)H]-[desArg(9)]-Lys-BK and [(3)H]-BK saturation studies indicated receptor density (B(max)) and K (d) values of 19 or 113 fmol mg(-1), and 0.16 or 0.11 nM for the B(1) or B(2) receptors, respectively. Inhibition binding studies indicated the selectivity of the B(1) receptor antagonist [desArg(9)Leu(8)]-Lys-BK and of the B(2) receptor antagonists Icatibant and MEN16132. [DesArg(9)]-Lys-BK and BK induced PI accumulation with an EC(50) of 1.6 and 1.4 nM and different maximal responses (E(max) of [desArg(9)]-Lys-BK was 10% of BK). BK also induced prostaglandin E(2) release (EC(50) 2.3 nM), whereas no response was detected with the B(1) receptor agonist. The incubation of detrusor smooth muscle cells with interleukin 1beta (IL-1beta) or tumour necrosis factor-alpha (TNF-alpha) (10 ng ml(-1)) induced a time-dependent increase in radioligand-specific binding, which was greater for the B(1) than for the B(2) receptor.

CONCLUSIONS AND IMPLICATIONS

Human detrusor smooth muscle cells in culture retain kinin receptors, and represent a suitable model to investigate the mechanisms and changes that occur under chronic inflammatory conditions.

Prostatitis: epidemiology of inflammation

Approximately 8 million prostatitis-related outpatient visits per year have been reported worldwide. Only a small percentage presents with bacterial prostatitis. Chronic pelvic pain syndrome/prostatodynia is a frustrating disease for patients and caregivers. This paper is an attempt to analyze causes and types of inflammation and to determine if inflammation may have an impact on treatment and outcome. Is inflammation even a relevant factor in the diagnosis of chronic pelvic pain syndrome? Do we need to begin to look for different factors involved in the development of this often crippling disease?

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

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

Cardiovascular effects of peptide kinin B2 receptor antagonists in rats

Bradykinin (BK) is a vasoactive peptide reputed to play an important role in cardiovascular homeostasis. In this study, we describe the cardiovascular changes (mean blood pressure (BP) and heart rate (HR)) induced by the i.v. administration (left jugular vein) of two selective kinin B2 receptor antagonist, namely icatibant (0.1-1 micromol/kg as a bolus) and MEN1 1270 (0.1-1 micromol/kg as a bolus or 1 micromol/kg infused in 15 or 60 min), in urethane-anaesthetized or conscious rats with an indwelling catheter implanted in the right carotid artery for BP measurements. In conscious rats, icatibant at 0.1 or 0.3 micromol/kg did not change BP but at 0.1 micromol/kg increased HR at 30 min from administration. MEN1 1270 at 0.1 or 0.3 micromol/kg induced a dose-related increase in BP and a concomitant bradycardia (significant at 0.3 micromol/kg) lasting for 5 or 30 min, respectively. Icatibant at 1 micromol/kg induced a slight (P < 0.05) increase in BP that resolved in 5 min and a biphasic tachycardia (peaks at 30 and 90 min from administration). MEN1 1270 at 1 micromol/kg induced a triphasic change in HR (tachycardia in the first 5 min, bradycardia at 30 min, and tachycardia at 90 and 120 min) and a biphasic change in BP (hypotension at 15 min and hypertension at 30 min). The i.v. infusion of MEN1 1270 (1 micromol/kg in 15 or 60 min) produced hypertension, whereas HR was increased only following the 15-min infusion. In urethane-anaesthetized rats, both icatibant and MEN1 1270 (0.1 micromol/kg as a bolus) increased BP and the onset for this effect was correlated with the time course of the antagonism of BK-induced hypotension, where the effect of MEN1 1270 was more rapid than that of icatibant. These results indicate that kinin B2 receptor antagonists can induce acute cardiovascular effects, and the reason for the different haemodynamic profile between icatibant and MEN1 1270 could be putatively attributed to kinetic characteristics.

[Bradykinin antagonist: current status and perspective]

The kallikrein-kinin system plays an important role in many physiological and pathophysiological conditions such as homeostasis of circulation, inflammation/allergy, pain, shock, etc. Two types of kinin receptor are known, bradykinin (BK) B1 receptor and BK B2 receptor. B2 receptors are constitutively expressed and mediate most physiological actions of kinins, whereas B1 receptors are highly inducible upon inflammatory stimulation or tissue injury, suggesting that they are involved in inflammation and/or nociception. Only three peptide type B2 antagonists, NPC 567, CP-0127 and HOE-140, have been evaluated in clinical studies so far, and some beneficial effects of B2 antagonists have been shown for rhinitis, asthma, systemic inflammatory response syndrome/sepsis and brain injury. However, the results were less convincing than expected. Now several potent and orally active nonpeptide B2-receptor antagonists have been found, which are expected to overcome the weak point of the peptide type antagonists and clarify the therapeutic potential of the B2-receptor antagonist for novel indications as well as those mentioned above. As for B1 receptors, no antagonist has been tested in a clinical trial. The important role of B1 receptors is just being elucidated by use of peptide type antagonists or B1 receptor gene knockout mice. The further development of newer B1 antagonists and clinical evaluation is desired.

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

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

The role of sensorial neuropeptides in the edematogenic responses mediated by B(1) agonist des-Arg(9)-BK in rats pre-treated with LPS

In the present study we have investigated some of the mechanisms underlying B(1) kinin receptor-induced paw edema formation in rats that had been treated with LPS, paying special attention to the involvement of neurogenic inflammation. Intradermal (i.d.) injection of the B(1) receptor agonist des-Arg(9)-BK (100 nmol/paw) resulted in a marked increase in paw volume in animals pre-treated with LPS (0.40+/-0.06 ml). The co-injection of the selective NK(1) FK888 (1 nmol/paw) or NK(2) SR 48968 (3 nmol/paw) receptor antagonists resulted in a significant inhibition of the edema induced by des-Arg(9)-BK (30+/-4 and 25+/-7%, respectively). The NK(3) SR 142801 (3 nmol/paw) antagonist did not demonstrate any significant effect on B(1) receptor-mediated paw edema. The edema induced by des-Arg(9)-BK was also significantly inhibited (33+/-5%) by the co-injection of the CGRP-receptor antagonist CGRP 8-37 (1 nmol/paw) or by treatment of animals with capsaicin (50 mgkg(-1), s.c., 48 h, prior) (45+/-4%). The pre-treatment of animals with methysergide or with mianserin, 5-HT(1) and 5HT(2) antagonists, respectively (both 10 mgkg(-1), i.p. 30 min), resulted in a significant reduction of the edema mediated by B(1) receptors (23+/-5 and 20+/-3%, respectively). In addition, compound 48/80 (12 microg/paw, 24 h) significantly reduced des-Arg(9)-induced paw edema in rats pre-treated with LPS (23+/-3%), while the treatment of animals with the H(1) receptor antagonist pyrilamine (10 mgkg(-1), i.p., 30 min) failed to affect the edematogenic responses involving B(1) receptors. Finally, the co-injection of NOS inhibitors L-NAME (100 nmol/paw) or 7-NINA (10 nmol/paw) did not affect the rat paw edema caused by des-Arg(9)-BK, whereas they significantly inhibited BK-induced paw edema. Jointly, the results of the present study show that the edematogenic response mediated by the activation of B(1) receptors, in animals pre-treated with LPS, involves the release of tachykinins and CGRP, as well as serotonin, while NO and histamine seem not to be involved. Therefore, these data further support the notion that B(1) receptors have an important role in modulating the inflammatory processes.

Characterization of bradykinin B(2) receptor antagonists in human and rat urinary bladder

The effect of three selective bradykinin B(2) receptor antagonists, MEN11270 (H-DArg-Arg-Pro-Hyp-Gly-Thi-c(Dab-DTic-Oic-Arg)c(7gamma-1 0alpha)), Icatibant (H-DArg-Arg-Pro-Hyp-Gly-Thi-Ser-DTic-Oic-Arg-OH), and FR173567 ((E)-3-(6-acetamido-3-pyridyl)-N-[N-[2, 4-dichloro-3-[(2-methyl-8-quinolinyl) oxymethyl] phenyl]-N-methylaminocarbonylmethyl]acrylamide) was evaluated in the human and rat urinary bladder in vitro and in vivo in anaesthetized rats. Bradykinin evoked a concentration-dependent contraction of human (pD(2)=7.2) and rat (pD(2)=7.7) detrusor muscle strips. In human preparations, all the antagonists tested produced a rightward-shift in the concentration-response curve for bradykinin. Schild plot analysis yielded pK(B) values of 8.4, 8.4 and 8.6 for MEN11270, Icatibant, and FR173567, respectively. In the rat preparations the three antagonists (at 100 nM concentration), produced a shift to the right which gave apparent pA(2) values of 8. 2, 8.0 and 8.1 for MEN11270, Icatibant, and FR173567, respectively. In anaesthetized rats, both MEN11270 and Icatibant (1-10 nmol/kg i.v. ) dose dependently reduced the bradykinin (100 nmol/kg i.v.)-induced urinary bladder contraction, their effect being prompt and long-lasting. In contrast, FR173567 (100 nmol/kg i.v.) produced a partial and short-lasting inhibition of bradykinin-induced bladder contractions. The present findings indicate that all the antagonists tested recognize with similar potencies the bradykinin B(2) receptors expressed in the detrusor muscle of both humans and rats. MEN11270 and Icatibant possess a higher potency and longer duration of action in vivo than FR173657, suggesting that the activity of this non-peptide antagonist in vivo is hampered by factors unrelated to its affinity for bradykinin B(2) receptors.

Pharmacological and molecular evidence for kinin B1 receptor expression in urinary bladder of cyclophosphamide-treated rats

1. In the present study, we developed an experimental model of cystitis induced by cyclophosphamide (CYP). In order to characterize des-Arg9-BK-induced contraction on the urinary bladder (UB) during the development of inflammation and to quantify kinin B1 receptor gene expression using a quantitative RT - PCR technique. 2. In the presence of peptidase inhibitors captopril (10 microM), DL-thiorphan (1 microM) and DL-2-mercaptomethyl-3-guanidino-ethylthiopropanoic acid (MERGEPTA 5 microM), bradykinin (BK) (0.3 - 3,000 nM) evoked a concentration-dependent contraction of rat UB which was not different between the CYP- and vehicle-treated groups. Unlike BK, des-Arg9-BK (0.3 - 100,000 nM) did not contract UB from vehicle-treated rats but contracted vigorously bladder strips from CYP-treated rats 14, 24 and 168 h after treatment. In UB of 24 h treated rat, the pD2 value of des-Arg9-BK was 7.3+/-0.1. 3. The cyclo-oxygenase inhibitor indomethacin (3 microM) reduced by 30% the maximal response of des-Arg9-BK. Both the kinin B1 receptor antagonists des-Arg9-[Leu8]BK (10 microM) and des-Arg10-Hoe 140 (10 microM) produced a rightward shift of the concentration-response curve to des-Arg9-BK yielding pKB values of 6.8+/-0.2 and 7.2+/-0.1, respectively, whilst the kinin B2 receptor antagonist Hoe 140 (1 microM) had no effect. 4. After CYP treatment, mRNA coding for the kinin B1 receptor appeared predominantly in UB. In this organ, the induction was progressive, reaching a maximum 48 h after CYP treatment. 5. In conclusion, the present study provides strong evidence for an induction of kinin B1 receptors in UB of CYP-treated rats. This was associated at a molecular level with an increase in mRNA expression of the gene coding for the kinin B1 receptor. This kinin receptor displayed the whole features of a classical rat kinin B1 receptor.

Effect of dexamethasone on cyclophosphamide-induced cystitis in rats: lack of relation with bradykinin B1 receptor-mediated motor responses

We investigated the role of bradykinin B receptors in inducing urinary bladder contraction and maintaining bladder compliance in anaesthetized rats following cyclophosphamide-induced bladder inflammation and the influence of dexamethasone treatment on these responses. In the group treated with cyclophosphamide the amplitude of the contraction induced by the selective bradykinin B1 receptor agonist des-Arg9-bradykinin was larger than that in controls and dexamethasone prevented the up-regulation of this response induced by inflammation. The specific binding of [3H]des-Arg10-kallidin to bladder membranes was only detected in cyclophosphamide-treated rats: this binding was prevented by dexamethasone pretreatment. The bladder contraction induced by des-Arg9-bradykinin in cyclophosphamide-treated rats was antagonized by the bradykinin B1 receptor antagonist des-Arg9-D-Arg-[Hyp3,Thi5,D-Tic7,Oic8]bradykinin (des-Arg10-Hoe 140). Cyclophosphamide treatment increased the bladder weight and dexamethasone reversed this effect. Bladder compliance was decreased in the bladder inflammation group and this effect was partially reversed by dexamethasone pretreatment. Neither des-Arg10-Hoe 140 nor the combined administration of des-Arg10Hoe 140 and the selective bradykinin B2 receptor antagonist D-Arg-[Hyp3,Thi5,D-Tic7,Oic8]bradykinin (Hoe 140) affected bladder compliance, thus excluding a role of kinins in the maintenance of bladder tone during inflammation. These results indicate that: (1) dexamethasone pretreatment ameliorates cyclophosphamide-induced bladder inflammation: (2) dexamethasone pretreatment prevents cyclophosphamide-induced up-regulation of bradykinin B receptors; (3) kinins do not contribute to the increased vesical tone during inflammation.

Lipopolysaccharide upregulates bradykinin 1 receptors in the isolated mouse bladder

PURPOSE

Bradykinin 1 (B1) receptors have been shown to be upregulated at sites of inflammation. The purpose of this study was to determine the effect of lipopolysaccharide (LPS) on B1 receptor modulation in the isolated mouse bladder.

MATERIALS AND METHODS

The contractile responses of isolated mouse bladder to B1 and B2 agonists were determined in vitro following prolonged incubation with LPS or saline.

RESULTS

Bradykinin (BK), a B2 agonist, but not des-Arg9-bradykinin (DABK), a B1 agonist, was found to be a potent contractile agonist of the mouse urinary bladder under basal conditions. However, both sensitivity and maximal response to DABK increased during a second exposure to the agonist in a time-dependent manner. In vivo or in vitro treatment with LPS increased both sensitivity and maximal response of isolated bladders to DABK, whereas bladder contraction to BK and other peptides remained the same. Treatment of tissues with a B1 receptor antagonist 45 minutes prior to second exposure to DABK, or the prostaglandin synthesis inhibitor, indomethacin, 30 minutes prior to LPS or saline incubation, significantly inhibited the increase of both maximal response and sensitivity.

CONCLUSIONS

These results indicate that bladder B1 receptors can be upregulated by LPS, and that prostaglandins seem to mediate the effects of the B1 receptor activation in the isolated mouse bladder.

Ovalbumin-induced neurogenic inflammation in the bladder of sensitized rats

1. We have developed and characterized a model of immediate hypersensitivity/inflammation of the urinary bladder in vivo induced by local application of ovalbumin (OA) in OA- sensitive female rats. Two parameters of the inflammatory response were assessed following OA challenge: plasma protein extravasation (PPE) and changes in smooth muscle reactivity. The former was estimated by measurement of Evans blue extravasation at 0.5, 2, 4, 8 and 24 h time point following in vivo challenge. Changes in reactivity were determined by measurement of isotonic tension responses of urinary bladder strips following OA challenge in vitro. 2. Acute in vivo intravesical OA challenge (10 mg in 0.3 ml saline) in actively sensitized female Wistar rats caused a time-dependent PPE in the urinary bladder which was biphasic with peak responses at 2-4 and 24 h. 3. The PPE response to acute OA challenge, above base-line, at 2 h was abolished by systemic capsaicin pretreatment (50 mg kg(-1), s.c., 4 days before use) (P < 0.05) whilst the response at 24 h was unaffected. The 2 h time point was then used for further studies. 4. Degranulation of mast cells, achieved by pretreatment with compound 48/80 (5 mg kg(-1), s.c. for 3 consecutive days), completely abolished the PPE response to OA challenge at the 2 h time point. 5. The tachykinin NK1 receptor antagonist, SR 140333 (0.1 micromol kg(-1), i.v.), abolished the 2 h PPE response whilst the tachykinin NK2 receptor antagonist MEN 11420 (0.1 micromol kg(-1), i.v.) appeared to reduce the response by approximately 50% but this did not reach significance. The bradykinin B2 receptor antagonist, Hoe 140 (0.1 micromol kg(-1), i.v.), similarly to SR 140333, blocked the 2 h PPE response to OA, whereas the selective B1 receptor antagonist B 9858 (0.1 micromol kg(-1), i.v.) had no significant effect. Inhibition of cyclo-oxygenase (COX) achieved by pretreatment with the COX inhibitor dexketoprofen (5.3 micromol kg(-1), i.v.) also blocked the PPE response, whilst the leukotriene receptor antagonist ONO 1078 (1 micromol kg(-1), i.v.) significantly reduced PPE by about 80%. 6. In the rat isolated urinary bladder OA (1 mg ml(-1)) challenge produced a biphasic response with a rapidly achieved maximal contraction followed by a sustained contraction for approximately 25 min. In vitro capsaicin pretreatment (10 microM for 15 min) significantly attenuated the duration of the sustained contraction whilst having no effect on the maximum contractile response achieved. In vivo pretreatment of animals with compound 48/80 significantly attenuated (42%) the maximum contractile response. Combination of both treatments almost completely abolished the response. In vitro treatment with Hoe 140 (1 microM) had no significant effect on the response to OA and neither did ONO 1078 (1 microM). 7. These results show that both the early inflammatory response and alterations in smooth muscle reactivity to OA challenge in actively sensitized animals are dependent on mast cell degranulation and the activation of sensory C-fibres. Furthermore this model of allergic cystitis may be useful for investigating both the processes involved and potential novel therapies in the treatment of interstitial cystitis.

Effect of octreotide, a somatostatin analogue, on release of inflammatory mediators from isolated guinea pig bladder

OBJECTIVE

Somatostatin has been demonstrated to inhibit inflammation under certain circumstances. We hypothesized that in vivo treatment with octreotide, a long-acting analogue of somatostatin analogue, would diminish the capacity of inflammatory peptides to stimulate in vitro release of inflammatory mediators by the bladder.

METHODS

Female guinea pigs were injected with octreotide (20 mg./kg. i.m.) prior to euthanasia. Control guinea pigs received no treatment prior to euthanasia. Urinary bladders were removed and incubated with substance P (SP, 10 microM), neurokinin A (NKA, 10 microM), or bradykinin (BK, 10 microM) in the presence or absence of indomethacin (50 microM), and release of histamine, prostaglandins (PGE2 and PGF2 alpha), and leukotriene (LTB4) was determined.

RESULTS

Sensory peptides and BK induced time-dependent release of histamine and eicosanoids from isolated urinary bladder. Blockade of cyclooxygenase with indomethacin (50 microM) abolished peptide-induced prostaglandin release but enhanced LTB4 release. In vivo octreotide pretreatment decreased peptide-induced histamine release, had no effect on PGE2 or PGF2 alpha release, and LTB4 release. However, octreotide prevented the increase in LTB4 release in tissues incubated with indomethacin.

CONCLUSIONS

These results indicate that somatostatin has the capacity to suppress the release of histamine and prevents potentiation of LTB4 release by indomethacin by the guinea pig bladder in response to pro-inflammatory peptides, indicating that somatostatin may be useful in preventing or treating some forms of cystitis.

Pharmacological analysis of the local and reflex responses to bradykinin on rat urinary bladder motility in vivo

1. The topical application of bradykinin (BK) (0.05-5000 pmol/rat) onto the serosal surface of the urinary bladder in urethane-anaesthetized rats, evoked low amplitude tonic contractions (not exceeding 25 mmHg) or high amplitude (about 50 mmHg), phasic reflex contractions (chemoceptive micturition reflex) which were abolished by bilateral ablation of the pelvic ganglia. In ganglionectomized rats, BK induced only a local, tonic-type contraction. 2. Systemic capsaicin pretreatment (164 mumol kg-1, 4 days before) reduced the incidence of chemoceptive reflex induced by BK (500 pmol/rat) but had no effect on the magnitude of the tonic-type contraction elicited by BK in ganglionectomized rats. Indomethacin (11 mumol kg-1, 20 min before) reduced the incidence but not the amplitude of the reflex contractions induced by topical application of BK (500 pmol/rat). In ganglionectomized rats, indomethacin (11 mumol kg-1, 20 min before) decreased the amplitude of the tonic contraction evoked by BK. Indomethacin did not affect the chemoceptive reflex induced by topical application of capsaicin (15 nmol/rat) onto the bladder. 3. Intrathecal administration of the tachykinin NK1 receptor antagonists, RP 67,580 (10 nmol/rat) or SR 140,333 (10 nmol/rat), abolished the chemoceptive reflex induced by BK without modifying the magnitude of the tonic contraction. SR 140,333 (10 nmol/rat) also abolished the occurrence of the chemoceptive reflex induced by capsaicin. 4. Intravenous administration of the B2 receptor antagonist, Hoe 140 (35 nmol kg-1, 10 min before) abolished the reflex and local effects induced by BK on bladder motility but failed to modify the chemoceptive reflex induced by topical application of capsaicin (15 nmol/rat). 5. Intrathecal administration of Hoe 140 (10 nmol/rat) reduced the incidence of the chemoceptive reflex induced by BK but had no effect on the amplitude of the local motor response. Likewise, Hoe 140(10 nmol/rat, i.t.) reduced the incidence of reflex bladder contractions induced by topical application of capsaicin (15 nmol/rat) without affecting the magnitude of the tonic-type contraction.6. These findings indicate that BK stimulates motility through B2 receptors in the rat urinary bladder.BK activates the reflex response by stimulating capsaicin-sensitive afferent nerves with a contribution from prostanoids. At the spinal cord level, tachykinin NK1 and BK B2 receptors could also be involved in the chemoceptive reflex induced by BK or capsaicin.

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

1. Cyclophosphamide (CYP) (150 mg kg-1, i.p. 0.5-48 h before) caused a time-dependent plasma protein extravasation in the rat urinary bladder with the maximal extravasation occurring at between 2 and 4 h after administration of the drug. 2. Prior capsaicin desensitization of capsaicin-sensitive primary afferent neurones (CSPANs) (50 mg kg-1, s.c., 4 days before) resulted in approximately 50% inhibition of the magnitude of the extravasation response at the 2 h time-point. 3. Intraperitoneal (i.p.) pretreatment with the tachykinin NK1 receptor antagonist, RP 67,580 (0.44 mg kg-1) or the bradykinin B2 receptor antagonist, Hoe 140 (0.13 mg kg-1) had significant inhibitory effects, giving responses of 56 +/- 6% and 39 +/- 4% of the control extravasation response to CYP treatment after 2 h. Pretreatment with the tachykinin NK2 receptor antagonist, SR 48,968 (0.3 mg kg-1, i.p.), the histamine H1 receptor blocker, chlorpheniramine (10 mg kg-1, i.p.), the 5-HT receptor blocker, methysergide (6 mg kg-1, i.p.) or the cyclo-oxygenase inhibitor indomethacin (5 mg kg-1, i.p.) had no significant effect upon the development of the extravasation response at this same time-point. 4. In rat isolated urinary bladder strips, the active metabolite of CYP, acrolein (1-300 microM) produced a concentration-dependent contraction that was significantly reduced by in vitro capsaicin desensitization (10 microM for 15 min) indicating direct stimulation of CSPANs. CYP was without appreciable effect. 5. The effect of acrolein in vitro was significantly reduced by pretreatment of the bladder with a combination of tachykinin NK1 and NK2 receptor antagonists, RP 67,580 (3 microM) and SR 48,968 (1 microM). The dose-response curve to acrolein was also significantly inhibited by treatment with indomethacin (10 microM) and slightly affected by Hoe 140 (1 microM). 6. These findings demonstrate the contribution of CSPANs to the development of CYP-induced cystitis.Plasma protein extravasation involves activation of tachykinin NKI and bradykinin B2 receptors.Activation of CSPANs in the urinary bladder is likely to be due to the conversion of CYP into its active metabolite, acrolein, and not to a direct effect of CYP upon these nerve-endings.