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We have tested the activity of 4-(S)-amino-5-(4-{4-[2,4-dichloro-3-(2,4-dimethyl-8-quinolyloxymethyl)phenylsulfonamido]-tetrahydro-2 H-4-pyranylcarbonyl} piperazino)-5-oxopentyl](trimethyl)ammonium chloride hydrochloride (MEN16132), a novel nonpeptide kinin B2receptor antagonist, on bradykinin (BK)-induced inflammatory responses, bronchoconstriction, and hypotension in guinea pigs. After i.v. (1-10 nmol/kg i.v.), intratracheal (i.t.) (10-100 nmol/kg i.t.), or aerosol (0.01-0.1 mM/5 min) administration, MEN16132 inhibited in a dose-dependent manner the bronchoconstriction induced by BK (10 nmol/kg i.v.). MEN16132 was more potent and possessed a longer duration of action as compared with the peptide B2receptor antagonist icatibant (HOE140; H-d-Arg-Arg-Pro-Hyp-Gly-Thi-Ser-d-Tic-Oic-Arg-OH trifluoroacetate). After i.v. administration, its inhibitory effect on bronchoconstriction lasted more than 8 h at 30 nmol/kg. When administered by i.v. or i.t. routes, the dose completely inhibiting bronchoconstriction also partially reduced the hypotensive response to BK, whereas after aerosol administration, the inhibitory effect was limited to respiratory level. Intranasal (i.n.) administration of MEN16132 (0.01-0.3 nmol/nostril) reduced, in a dose-dependent and long-lasting manner, the nasal mucosa plasma protein extravasation induced by BK (100 nmol/nostril), and it exerted a complete inhibition at about 30-fold lower dose than icatibant. At 1 nmol/nostril, MEN16132 activity was significant for at least 6 h with no systemic effect measured as inhibition of BK-induced hypotension, and at 10 nmol/nostril, the inhibitory effect lasted for more than 15 h with only a weak effect on hypotension. These findings indicate that in vivo MEN16132 is a potent kinin B2receptor antagonist with long duration of action, both after i.v. and local administration. A complete and prolonged inhibition of BK-induced bronchoconstriction or nasal inflammation can be achieved with MEN16132 topical administration (aerosol or i.n.) at doses devoid of systemic effects.

Tachykinins have been implicated in inflammatory responses such as those occurring in inflammatory bowel disease. Accordingly, we investigated the effect of a selective neurokinin (NK) 2 receptor antagonist, nepadutant, on proto-oncogene expression in the L6-S1spinal cord as well as in dorsal root ganglion (DRG) neurons after either non-noxious colorectal distension (CRD) or trinitrobenzenesulfonic acid (TNBS)-induced colitis in the adult rat. In both preparations, c-foswas expressed in similar spinal cord regions, including medial and lateral dorsal horn, dorsal commissure (DCM; laminae X above the central canal), and the sacral parasympathetic nucleus (SPN, laminae V–VII). However, TNBS-induced colitis produced significantly larger numbers (8–10-fold increase over control) of Fos-positive spinal cord neurons. In addition, there was also a significant increase (3–4-fold) in the number of Jun-positive colon DRG neurons after colitis compared with CRD. Nepadutant had no significant effect on proto-oncogene expression induced by CRD in either spinal cord neurons or DRG neurons. In contrast, nepadutant significantly decreased (70%) the number of Fos-positive neurons in dorsal horn, DCM, and SPN spinal cord regions and significantly decreased (75%) the number of Jun-positive DRG neurons after TNBS-induced irritation of the colon. These findings indicate that nepadutant suppresses the responses of colonic afferent neurons to nociceptive stimuli and that NK2 receptor antagonists may be beneficial in the treatment of sensory symptoms of colitis.

Tachykinins have been implicated in inflammatory responses such as those occurring in inflammatory bowel disease. Accordingly, we investigated the effect of a selective neurokinin (NK) 2 receptor antagonist, nepadutant, on proto-oncogene expression in the L(6)-S(1) spinal cord as well as in dorsal root ganglion (DRG) neurons after either non-noxious colorectal distension (CRD) or trinitrobenzenesulfonic acid (TNBS)-induced colitis in the adult rat. In both preparations, c-fos was expressed in similar spinal cord regions, including medial and lateral dorsal horn, dorsal commissure (DCM; laminae X above the central canal), and the sacral parasympathetic nucleus (SPN, laminae V-VII). However, TNBS-induced colitis produced significantly larger numbers (8-10-fold increase over control) of Fos-positive spinal cord neurons. In addition, there was also a significant increase (3-4-fold) in the number of Jun-positive colon DRG neurons after colitis compared with CRD. Nepadutant had no significant effect on proto-oncogene expression induced by CRD in either spinal cord neurons or DRG neurons. In contrast, nepadutant significantly decreased (70%) the number of Fos-positive neurons in dorsal horn, DCM, and SPN spinal cord regions and significantly decreased (75%) the number of Jun-positive DRG neurons after TNBS-induced irritation of the colon. These findings indicate that nepadutant suppresses the responses of colonic afferent neurons to nociceptive stimuli and that NK2 receptor antagonists may be beneficial in the treatment of sensory symptoms of colitis.

Tachykinin NK2receptor antagonists could reduce motility and symptoms during gastrointestinal diseases characterized by local inflammation such as diarrhea or colitis; however, how these conditions change pharmacodynamic and pharmacokinetic characteristics of NK2receptor antagonists is unknown. We investigated the effect of the peptide NK2receptor antagonist nepadutant on spontaneous intestinal motility or [βAla8]NKA(4-10)-induced colonic and bladder contractions in rodent models of intestinal inflammation (enteritis induced by castor oil and rectocolitis induced by local instillation of acetic acid in rats, enteritis induced by bacterial toxins in mice). In the castor oil model, the oral/intraduodenal bioavailability of nepadutant was also determined. The intrarectal (i.r.) administration of nepadutant (100 nmol/kg) did not reduce [βAla8]NKA(4-10) (10 nmol/kg i.v.)-induced colonic and bladder contractions in normal animals, but the same dose of nepadutant produced an inhibitory effect in the two organs following rectocolitis; in contrast, nepadutant is equieffective by the intravenous route in normal and colitic animals. In this model, nepadutant (100 nmol/kg i.r. or i.v.) decreased spontaneous colonic hypermotility, without affecting motility in controls. The intraduodenal administration of nepadutant (30 nmol/kg), which was ineffective on [βAla8]NKA(4-10) (10 nmol/kg i.v.)-induced colonic and bladder contractions in control animals, abolished bladder contractions in castor oil-pretreated animals. In this latter group, the oral and intraduodenal bioavailability of nepadutant showed a 7- to 9-fold increase with respect to controls. Oral administration of nepadutant, in nanomolar or subnanomolar dosage, reduced diarrhea induced by bacterial toxins in mice. It is concluded that intestinal inflammation increases nepadutant absorption in the intestine, enhancing its activity. These results suggest that a drug with a limited oral bioavailability could be used for treating gastrointestinal diseases associated with a local inflammation.

We have compared the in vivo activity of the bradykinin B2receptor peptide antagonists MEN 11270 and Icatibant versus the nonpeptide antagonist FR 173657, after intravenous (i.v.) and intratracheal (i.t.) administration, on the bradykinin (BK)-induced bronchoconstriction and hypotension in anesthetized guinea pigs. We have also assessed the affinity of these antagonists for B2receptors in guinea pig lung membranes by radioligand binding and the metabolic stability of peptide antagonists in guinea pig plasma and tissue homogenates. The i.v. administration of MEN 11270, Icatibant, or FR 173657 induced a dose-dependent (10–100 nmol/kg) inhibition of both hypotension and bronchoconstriction induced by bradykinin (10 nmol/kg i.v.). The inhibitory effect of MEN 11270 and Icatibant was comparable both in terms of potency and time course, whereas FR 173657 was less potent and shorter acting. After i.t. administration MEN 11270 and Icatibant (10–100 nmol/kg) dose dependently inhibited both bronchoconstriction and hypotension, whereas FR 173657 (10–100 nmol/kg) reduced bronchoconstriction without affecting hypotension. The antibronchoconstrictor effect of MEN 11270 was more prolonged than that of Icatibant and FR 173657, whereas no differences were found between the peptide antagonists in inhibiting hypotension. These findings indicated that, in vivo, the peptide antagonists are more potent and longer lasting than FR 173657 acting on bradykinin B2receptors in guinea pig airways and in the vascular system. The greater efficacy of the antagonists in blocking airway compared with vascular B2receptors after topical administration suggests that they can block airway B2receptors with little systemic effects.

We have compared the in vivo activity of the bradykinin B(2) receptor peptide antagonists MEN 11270 and Icatibant versus the nonpeptide antagonist FR 173657, after intravenous (i.v.) and intratracheal (i.t.) administration, on the bradykinin (BK)-induced bronchoconstriction and hypotension in anesthetized guinea pigs. We have also assessed the affinity of these antagonists for B(2) receptors in guinea pig lung membranes by radioligand binding and the metabolic stability of peptide antagonists in guinea pig plasma and tissue homogenates. The i.v. administration of MEN 11270, Icatibant, or FR 173657 induced a dose-dependent (10-100 nmol/kg) inhibition of both hypotension and bronchoconstriction induced by bradykinin (10 nmol/kg i.v.). The inhibitory effect of MEN 11270 and Icatibant was comparable both in terms of potency and time course, whereas FR 173657 was less potent and shorter acting. After i.t. administration MEN 11270 and Icatibant (10-100 nmol/kg) dose dependently inhibited both bronchoconstriction and hypotension, whereas FR 173657 (10-100 nmol/kg) reduced bronchoconstriction without affecting hypotension. The antibronchoconstrictor effect of MEN 11270 was more prolonged than that of Icatibant and FR 173657, whereas no differences were found between the peptide antagonists in inhibiting hypotension. These findings indicated that, in vivo, the peptide antagonists are more potent and longer lasting than FR 173657 acting on bradykinin B(2) receptors in guinea pig airways and in the vascular system. The greater efficacy of the antagonists in blocking airway compared with vascular B(2) receptors after topical administration suggests that they can block airway B(2) receptors with little systemic effects.

The contractile responses elicited by the selective kinin B1and B2receptor agonists [desArg9]-bradykinin ([desArg9]-BK) and [Hyp3, Tyr(Me)8]-bradykinin ([Hyp3, Tyr(Me)8]-BK) (1 nM–10 μM), respectively, were evaluated in control vs.inflamed (cyclophosphamide 150 mg kg−1i.p., 48 h before the sacrifice) rat isolated urinary bladder strips. The contractile responses to the B2receptor agonist did not differ in control vs.inflamed bladders, whereas the contractile responses to [desArg9]-BK were potentiated in inflamed bladders. The selective B1and B2receptor antagonists B 9858 (H-Lys-Lys-Arg-Pro-Hyp-Gly-Igl-Ser-DIgl-Oic-OH) and Hoe 140 (H-DArg-Arg-Pro-Hyp-Gly-Thi-Ser-DTic-Oic-Arg-OH), both at 1 μM, inhibited the response to the B1and B2receptor agonists, respectively, in both control and inflamed bladders. In addition, the concentration-response curve to [Hyp3, Tyr(Me)8]-BK was shifted to the right and depressed by B 9858 in inflamed bladders. The nonselective cyclooxygenase (COX) inhibitors S-(−)-ketoprofen (10 μM) and piroxicam (30 μM) markedly depressed the concentration-response curves to [desArg9]-BK and [Hyp3, Tyr(Me)8]-BK in control bladders, but neither drug affected the B1or B2receptor agonist-mediated responses in inflamed bladders. The selective inhibitor of the inducible COX-2 isoenzyme, NS-398 (1 μM), did not inhibit the contractile responses to [desArg9]-BK and [Hyp3, Tyr(Me)8]-BK in either control or inflamed bladders, whereas it significantly potentiated the response to the B1receptor agonist in inflamed bladders. The exogenous administration of prostaglandin E2(PGE2) induced S-(−)-ketoprofen-resistant contractile responses that were depressed in inflamed bladders. Pretreatment with S-(−)-ketoprofen restored the PGE2-mediated contractile responses of inflamed bladders to control values. PGE2assay revealed that the basal production of PGE2is significantly higher after inflammation than in control conditions. [desArg9]-BK and [Hyp3, Tyr(Me)8]-BK (1 μM each) both stimulated PGE2production, and their effect was larger in inflamed than in control bladders. Piroxicam (30 μM) prevented the PGE2production evoked by [desArg9]-BK in both control and inflamed bladders and likewise abolished that produced by [Hyp3, Tyr(Me)8]-BK. NS-398 (1 μM) reduced the PGE2production elicited by [desArg9]-BK in control and inflamed bladders. When NS-398 was tested on the [Hyp3, Tyr(Me)8]-BK-induced PGE2production, it inhibited PGE2production in the inflamed bladders only, without significantly modifying the response obtained in controls. These findings demonstrate that 1) in normal bladders, the activation of B1and B2receptors evokes contraction that is largely mediated by COX-1 metabolites, whereas the COX-2 appears to be involved in PGE2production after the activation of B1receptor only, without interfering with contraction, and 2) in inflamed bladders, the activation of B1and B2receptors still produce PGE2, but the contractile response is not reduced by COX inhibitors, a result that indicates that additional mechanisms play a compensatory role.

Acute imipramine administration (15 mg/kg i.p. 60 min before) increased the threshold for activating the spinal but not the supraspinal vesico-vesical micturition reflex in urethane-anesthetized rats. On the other hand, "chronic" imipramine administration (15 mg/kg i.p./day for 5 consecutive days) increased selectively the threshold of the supraspinal micturition reflex. Intravenous administration of cumulative doses of imipramine (up to 14 mg/kg) exerted a progressive inhibitory effect on the supraspinal reflex and voiding efficiency, possibly related to direct inhibition of muscular contractility at the bladder level. However, with the dose regimen used to compare the action of imipramine on spinal and supraspinal reflexes (15 mg/kg i.p., 60 min before), imipramine did not affect the volume-pressure curve or myogenic activity in decentralized bladders (bilateral removal of pelvic ganglia). The effect of acute imipramine on threshold of the spinal vesico-vesical reflex was absent in rats receiving oral p-chlorophenylalanine to deplete 5-hydroxytryptamine stores in the central nervous system. On the other hand, p-chlorophenylalanine pretreatment did not prevent the action of chronic imipramine administration on the supraspinal reflex. Acute administration of desipramine, the major metabolite of imipramine, increased threshold of the spinal but not supraspinal micturition reflex. These findings indicate that the ability of imipramine to modulate vesico-urethral motility at the central nervous system level may involve different mechanisms. Inhibition of 5-hydroxytryptamine reuptake in nerve terminals may be important for the acute modulatory effect of imipramine on the spinal reflex.

The contractile responses elicited by the selective kinin B1 and B2 receptor agonists [desArg9]-bradykinin ([desArg9]-BK) and [Hyp3, Tyr(Me)8]-bradykinin ([Hyp3, Tyr(Me)8]-BK) (1 nM-10 microM), respectively, were evaluated in control vs. inflamed (cyclophosphamide 150 mg kg-1 i.p., 48 h before the sacrifice) rat isolated urinary bladder strips. The contractile responses to the B2 receptor agonist did not differ in control vs. inflamed bladders, whereas the contractile responses to [desArg9]-BK were potentiated in inflamed bladders. The selective B1 and B2 receptor antagonists B 9858 (H-Lys-Lys-Arg-Pro-Hyp-Gly-Igl-Ser-DIgl-Oic-OH) and Hoe 140 (H-DArg-Arg-Pro-Hyp-Gly-Thi-Ser-DTic-Oic-Arg-OH), both at 1 microM, inhibited the response to the B1 and B2 receptor agonists, respectively, in both control and inflamed bladders. In addition, the concentration-response curve to [Hyp3, Tyr(Me)8]-BK was shifted to the right and depressed by B 9858 in inflamed bladders. The nonselective cyclooxygenase (COX) inhibitors S-(-)-ketoprofen (10 microM) and piroxicam (30 microM) markedly depressed the concentration-response curves to [desArg9]-BK and [Hyp3, Tyr(Me)8]-BK in control bladders, but neither drug affected the B1 or B2 receptor agonist-mediated responses in inflamed bladders. The selective inhibitor of the inducible COX-2 isoenzyme, NS-398 (1 microM), did not inhibit the contractile responses to [desArg9]-BK and [Hyp3, Tyr(Me)8]-BK in either control or inflamed bladders, whereas it significantly potentiated the response to the B1 receptor agonist in inflamed bladders. The exogenous administration of prostaglandin E2 (PGE2) induced S-(-)-ketoprofen-resistant contractile responses that were depressed in inflamed bladders. Pretreatment with S-(-)-ketoprofen restored the PGE2-mediated contractile responses of inflamed bladders to control values. PGE2 assay revealed that the basal production of PGE2 is significantly higher after inflammation than in control conditions. [desArg9]-BK and [Hyp3, Tyr(Me)8]-BK (1 microM each) both stimulated PGE2 production, and their effect was larger in inflamed than in control bladders. Piroxicam (30 microM) prevented the PGE2 production evoked by [desArg9]-BK in both control and inflamed bladders and likewise abolished that produced by [Hyp3, Tyr(Me)8]-BK. NS-398 (1 microM) reduced the PGE2 production elicited by [desArg9]-BK in control and inflamed bladders. When NS-398 was tested on the [Hyp3, Tyr(Me)8]-BK-induced PGE2 production, it inhibited PGE2 production in the inflamed bladders only, without significantly modifying the response obtained in controls. These findings demonstrate that 1) in normal bladders, the activation of B1 and B2 receptors evokes contraction that is largely mediated by COX-1 metabolites, whereas the COX-2 appears to be involved in PGE2 production after the activation of B1 receptor only, without interfering with contraction, and 2) in inflamed bladders, the activation of B1 and B2 receptors still produce PGE2, but the contractile response is not reduced by COX inhibitors, a result that indicates that additional mechanisms play a compensatory role.

Intravenous administration of the selective 5-hydroxytryptamine (5-HT)1A receptor agonist 8-hydroxy-2-(di-N-propylaminotetralin (8-OH-DPAT) and of a low doses of buspirone elicited the supraspinal micturition reflex (SMR) in urethane-anesthetized rats when the urinary bladder was filled with just a subthreshold volume of saline (threshold conditions). The effect of i.v. 8-OH-DPAT was abolished by hexamethonium or spiroxatrine. When SMR was elicited by bladder distension (suprathreshold conditions), i.v. 8-OH-DPAT increased the frequency of bladder contractions. In threshold conditions, stimulation of SMR was also induced by i.c.v. or by i.t. administration of 8-OH-DPAT and 5-HT but not by topical application of 8-OH-DPAT onto the bladder. Guanethidine pretreatment, which produced detrusor hyperreflexia, antagonized the effect of both i.c.v. and i.t. 8-OH-DPAT. In rats treated with capsaicin as adults, the response to 8-OH-DPAT was unchanged. In rats treated with capsaicin as newborns, instead, the response to i.t. 8-OH-DPAT was abolished and that to i.c.v. 8-OH-DPAT was shifted to higher doses. Pretreatment with 5,7-dihyroxytryptamine did not affect the response to i.t. 8-OH-DPAT but shifted to higher doses the response to i.c.v. 8-OH-DPAT. Intravenous administration of spiroxatrine, methysergide, NAN-190 [1-(2-methoxyphenyl)-4-[4-(2-phtalimido)butyl] piperazine] or high doses of buspirone but not of 1-sulpiride inhibited SMR in suprathreshold conditions. The inhibitory effect of spiroxatrine, NAN-190 and buspirone was not reduced by guanethidine pretreatment. In chronically spinalized animals, i.v. 8-OH-DPAT increased the amplitude of the reflex bladder contractions induced by bladder distension.(ABSTRACT TRUNCATED AT 250 WORDS)

We have studied the effects of two newly developed tachykinin antagonists, MEN 10,207 and MEN 10,376, which are highly selective for NK-2 tachykinin receptors on tachykinin-induced contraction in the rat urinary bladder and guinea pig airways in vivo. MEN 10,207 exhibited antagonism only at doses which produced agonist effects. By contrast, MEN 10,376 was devoid of significant agonist activity at i.v. doses (1-3 mumol/kg) which selectively antagonized the effects of an NK-2 agonist [beta-Ala8]-neurokinin A(4-10) (bladder contraction in rats, bronchoconstriction in guinea pigs) without affecting the response to an NK-1 agonist [Sar9]-substance P sulfone (hypotension, salivation and bladder contraction in rats, bronchoconstriction in guinea pigs). At these NK-2-selective blocking doses, MEN 10,376: 1) did not affect urodynamic parameters at cystometry in normal rats but reduced amplitude of micturition contractions following induction of chemical (intravesical xylene) cystitis and 2) reduced by a maximum of 50% the noncholinergic bronchoconstrictor response to vagal nerve stimulation. These findings provide the first evidence for involvement of NK-2 receptors in physiological responses in the urinary and respiratory tracts.

Distension of a balloon placed in the proximal colon of anesthetized, guanethidine- and naloxone-pretreated guinea pigs elicited a series of long-lasting regular phasic pressure waves which were suppressed by hexamethonium. Activity evoked by a low degree of balloon distension was largely, but not completely, suppressed by atropine. Further balloon distension in atropine-treated animals enabled us to study the effect of tachykinin receptor antagonists on the atropine-resistant and hexamethonium-sensitive response to distension. The selective tachykinin receptor antagonists, (+/-)-CP 96,345 for the NK-1 receptor and L 659,877, MEN 10,376 and SR 48,968 for the NK-2 receptor, inhibited with varying potency the atropine-resistant response to distension. These antagonists also blocked the contraction of the guinea pig colon produced by the i.v. administration of selective NK-1 and NK-2 receptor agonists. In vitro experiments, using mucosa-free circular muscle strips from the guinea pig colon, proved the existence of functional NK-1 and NK-2 receptors in this tissue. We conclude that both NK-1 and NK-2 receptors participate in the atropine-resistant reflex contractions produced by localized balloon distension of the guinea pig colon in vivo.

This study investigates the role of peripheral tachykinin receptors in the initiation of reflex urinary bladder contractions in urethane-anesthetized rats. Intravenous administration of the selective tachykinin neurokinin (NK)-1 receptor agonist [Sar9]substance P (SP) sulfone (0.3-30 nmol/kg) or of the selective tachykinin NK-2 receptor agonist [beta Ala8]NK-A(4-10) (0.3-100 nmol/kg) produced dose-related bladder contractions. Among NK-3 receptor agonists, senktide (1-100 nmol/kg) was not effective; [MePhe7] NK-B (3-100 nmol/kg) induced bladder contraction, but the magnitude of the response was only 20 to 25% of that produced by NK-1 or NK-2 agonists. The NK-1 receptor antagonist GR 82,334 (0.1 mumol/kg i.v.) blocked the urinary bladder contraction induced by [Sar9]SP sulfone (1 nmol/kg i.v.), but not that induced by [beta Ala8]NK-A(4-10). On the contrary, the NK-2 receptor antagonist L 659,877 (0.1-1 mumol/kg i.v.) abolished the effect of [beta Ala8] NK-A(4-10) (1 nmol/kg i.v.), but failed to affect the response to [Sar9]SP sulfone. The combined administration of GR 82,334 (0.1 mumol/kg i.v.) and L 659,877 (1 mumol/kg i.v.) blocked the tonic bladder contraction induced by topical application of capsaicin in pelvic ganglionectomized rats (efferent response of sensory nerves), but did not affect the hexamethonium-sensitive phasic reflex bladder contractions evoked by capsaicin in sham-operated rats (chemonociceptive micturition reflex). GR 82,334 (0.1 mumol/kg i.v.) or L 659,877 (1 mumol/kg i.v.), alone or in combination, did not modify cystometric parameters of the volume-evoked micturition reflex.(ABSTRACT TRUNCATED AT 250 WORDS)