piperidines and 7-7-diphenyl-2-(1-imino-2-(2-methoxyphenyl)ethyl)perhydroisoindol-4-one

To understand the functions of the neocortex, it is essential to characterize the properties of neurons constituting cortical circuits. Here, we focused on a distinct group of GABAergic neurons that are defined by a specific colocalization of intense labeling for both neuronal nitric oxide synthase (nNOS) and substance P (SP) receptor [neurokinin 1 (NK1) receptors]. We investigated the mechanisms of the SP actions on these neurons in visual cortical slices obtained from young glutamate decarboxylase 67-green fluorescent protein knock-in mice. Bath application of SP induced a nonselective cation current leading to depolarization that was inhibited by the NK1 antagonists in nNOS-immunopositive neurons. Ruthenium red and La(3+), transient receptor potential (TRP) channel blockers, suppressed the SP-induced current. The SP-induced current was mediated by G proteins and suppressed by D609, an inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC), but not by inhibitors of phosphatidylinositol-specific PLC, adenylate cyclase or Src tyrosine kinases. Ca(2+) imaging experiments under voltage clamp showed that SP induced a rise in intracellular Ca(2+) that was abolished by removal of extracellular Ca(2+) but not by depletion of intracellular Ca(2+) stores. These results suggest that SP regulates nNOS neurons by activating TRP-like Ca(2+)-permeable nonselective cation channels through a PC-PLC-dependent signaling pathway.

Topics: Animals; Anthracenes; Boron Compounds; Calcium; Calcium Channel Blockers; Dose-Response Relationship, Drug; Electric Stimulation; Excitatory Amino Acid Agents; GABAergic Neurons; Glutamate Decarboxylase; Imidazoles; In Vitro Techniques; Isoindoles; Mice; Mice, Transgenic; Neurokinin-1 Receptor Antagonists; Nitric Oxide Synthase Type III; Patch-Clamp Techniques; Piperidines; Quinolines; Quinuclidines; Signal Transduction; Substance P; Type C Phospholipases; Visual Cortex

Mice lacking the NK(1) receptor (NK(1)R-/- mice) and selective, high-affinity, non-peptide, NK(1), NK(2) and NK(3) receptor antagonists were used to identify the tachykinin receptor subtype(s) mediating the central responses induced by neurokinin A (NKA). The peptides, substance P (SP), NKA and senktide and the antagonists were injected intracerebroventricularly (ICV) through an implanted cannula. NKA (50 pmol) was as potent as SP (50 pmol) in inducing grooming behaviour (face washing and hind limb grooming) in wild-type mice, but both peptides failed to induce behavioural responses in NK(1)R-/- mice. In wild-type mice, the NK(1) receptor antagonist, RP 67580 (2 nmol), effectively inhibited grooming behaviour elicited by SP, but was inactive against grooming induced by NKA, which in turn was abolished after pre-treatment with the selective NK(2) receptor agonist, SR 48968 (2 nmol). Unlike NKA, the selective NK(2) receptor agonists, (β Ala(8)) NKA 4-10 and (NLeu(10)) NKA 4-10, injected ICV at doses of 50 or 100 pmol did not elicit any behavioural response in wild-type mice. The NK(3) receptor antagonist, SR 142801, inhibited behaviours induced by the NK(3) receptor agonist, senktide, but did not alter behavioural responses to either SP or NKA in wild-type mice. The present findings demonstrate that central biological actions of SP and senktide are mediated by activation of NK(1) and NK(3) receptors, respectively. Our results also indicate that NK(1) receptors are essential for generating central actions induced by NKA, which are most probably mediated by a cross-talk between the NK(1) and NK(2) receptors.

Topics: Animals; Behavior, Animal; Benzamides; Brain; Dose-Response Relationship, Drug; Grooming; Injections, Intraventricular; Isoindoles; Male; Mice; Mice, Knockout; Neurokinin A; Neurokinin-1 Receptor Antagonists; Peptide Fragments; Piperidines; Receptor Cross-Talk; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Stereoisomerism; Substance P

Substance P (SP), a neurokinin-1 receptor (NK-1R) agonist, is mainly produced and stored in primary sensory nerves and, upon its release, participates in cardiovascular and renal functional regulation. This study tests the hypothesis that activation of the NK-1Rs by SP occurs during hypertension induced by deoxycorticosterone (DOCA)-salt treatment, which contributes to renal injury in this model. C57BL/6 mice were subjected to uninephrectomy and DOCA-salt treatment in the presence or absence of administration of selective NK-1 antagonists, L-733,060 (20 mg/kg·d, ip) or RP-67580 (8 mg/kg·d, ip). Five weeks after the treatment, mean arterial pressure determined by the telemetry system increased in DOCA-salt mice but without difference between NK-1R antagonist-treated or NK-1R antagonist-untreated DOCA-salt groups. Plasma SP levels were increased in DOCA-salt compared with control mice (P < 0.05). Renal hypertrophy and increased urinary 8-isoprostane and albumin excretion were observed in DOCA-salt compared with control mice (P < 0.05). Periodic acid-Schiff and Masson's trichrome staining showed more severe glomerulosclerosis and tubulointerstitial injury in the renal cortex in DOCA-salt compared with control mice, respectively (P < 0.05). Hydroxyproline assay and F4/80-staining showed that renal collagen levels and interstitial monocyte/macrophage infiltration were greater in DOCA-salt compared with control mice, respectively (P < 0.05). Blockade of the NK-1R with L-733,060 or RP-67580 in DOCA-salt mice suppressed increments in urinary 8-isoprostane and albumin excretion, interstitial monocyte/macrophage infiltration, and glomerulosclerosis and tubulointerstitial injury and fibrosis (P < 0.05). Thus, our data show that blockade of the NK-1Rs alleviates renal functional and tissue injury in the absence of alteration in blood pressure in DOCA-salt-hypertensive mice. The results suggest that elevated SP levels during DOCA-salt hypertension play a significant role contributing to renal damage possibly via enhancing oxidative stress and macrophage infiltration of the kidney.

Topics: Animals; Blood Pressure; Desoxycorticosterone; Hydroxyproline; Hypertension; Isoindoles; Kidney; Male; Mice; Mice, Inbred C57BL; Piperidines; Receptors, Neurokinin-1; Substance P; Telemetry; Time Factors

All neuronal networks are modulated by multiple neuropeptides and biogenic amines. Yet, few studies investigate how different modulators interact to regulate network activity. Here we explored the state-dependent functional interactions between three excitatory neuromodulators acting on neurokinin1 (NK1), alpha1 noradrenergic (alpha1 NE), and 5-HT2 serotonin receptors within the pre-Bötzinger complex (pre-BötC), an area critical for the generation of breathing. In anesthetized, in vivo mice, the reliance on endogenous NK1 activation depended on spontaneous breathing frequency and the modulatory state of the animal. Endogenous NK1 activation had no significant respiratory effect when stimulating raphe magnus and/or locus ceruleus, but became critical when alpha1 NE and 5-HT2 receptors were pharmacologically blocked. The dependence of the centrally generated respiratory rhythm on NK1 activation was blunted in the presence of alpha1 NE and 5-HT2 agonists as demonstrated in slices containing the pre-BötC. We conclude that a modulator's action is determined by the concurrent modulation and interaction with other neuromodulators. Deficiencies in one neuromodulator are immediately compensated by the action of other neuromodulators. This interplay could play a role in the state dependency of certain breathing disorders.

Topics: Action Potentials; Adrenergic alpha-1 Receptor Antagonists; Animals; Animals, Newborn; Electric Stimulation; Electromyography; Hypoglossal Nerve; In Vitro Techniques; Isoindoles; Ketanserin; Locus Coeruleus; Mice; Microinjections; Neural Inhibition; Neural Pathways; Neurokinin-1 Receptor Antagonists; Neurons; Neurotransmitter Agents; Piperidines; Raphe Nuclei; Receptors, Adrenergic, alpha-1; Receptors, Neurokinin-1; Receptors, Serotonin, 5-HT2; Respiration; Respiratory Center; Serotonin 5-HT2 Receptor Antagonists; Serotonin Antagonists

Though neurokinin(1) (NK(1)) receptor antagonists are active in experimental models of depression, clinical efficacy has proven disappointing. This encourages interest in association of NK(1) receptor blockade with inhibition of serotonin (5-HT) reuptake. The selective NK(1) antagonist, GR205171, dose-dependently enhanced citalopram-induced elevations of extracellular levels of 5-HT in frontal cortex, an action expressed stereospecifically vs its less active distomer, GR226206. Further, increases in 5-HT levels in dorsal hippocampus, basolateral amygdala, nucleus accumbens, and striatum were likewise potentiated, and GR205171 similarly facilitated the influence of fluoxetine upon levels of 5-HT, as well as dopamine and noradrenaline. In parallel electrophysiological studies, the inhibitory influence of citalopram and fluoxetine upon raphe-localized serotonergic neurones was stereospecifically blunted by GR205171. Antidepressant actions of citalopram in a forced-swim test in mice were stereospecifically potentiated by GR205171, and it also enhanced attenuation by citalopram of stress-related ultrasonic vocalizations in rats. Further, GR205171 and citalopram additively abrogated the advance in circadian rhythms provoked by exposure to light in hamsters. By contrast, GR205171 stereospecifically blocked anxiogenic actions of citalopram in social interaction procedures in rats and gerbils, and stereospecifically abolished facilitation of fear-induced foot tapping by fluoxetine in gerbils. By analogy to GR205171, a further NK(1) antagonist, RP67580, enhanced the influence of citalopram upon frontocortical levels of 5-HT and potentiated its actions in the forced swim test. In conclusion, NK(1)receptor blockade differentially modulates functional actions of SSRIs: antidepressant properties are reinforced, whereas anxiogenic effects are attenuated. Combined NK(1) receptor antagonism/5-HT reuptake inhibition may offer advantages in the management of depressed and anxious states.

Topics: Animals; Anti-Anxiety Agents; Antidepressive Agents; Behavior, Animal; Brain; Citalopram; Cricetinae; Dopamine; Drug Synergism; Fluoxetine; Gerbillinae; Isoindoles; Male; Mesocricetus; Mice; Neurokinin-1 Receptor Antagonists; Neurons; Norepinephrine; Piperidines; Rats; Rats, Wistar; Selective Serotonin Reuptake Inhibitors; Serotonin; Tetrazoles

Intrathecal (i.t.) injection of morphine-3-glucuronide (M3G), a major metabolite of morphine without analgesic actions, produces a severe hindlimb scratching followed by biting and licking in mice. The pain-related behavior evoked by M3G was inhibited dose-dependently by i.t. co-administration of tachykinin NK(1) receptor antagonists, sendide, [D-Phe(7), D-His(9)] substance P(6-11), CP-99994 or RP-67580 and i.t. pretreatment with antiserum against substance P. The competitive NMDA receptor antagonists, D-APV and CPP, the NMDA ion-channel blocker, MK-801 or the competitive antagonist of the polyamine recognition site of NMDA receptor ion-channel complex, ifenprodil, produced inhibitory effects on i.t. M3G-evoked nociceptive response. The NO-cGMP-PKG pathway, which involves the extracellular signal-regulated kinase (ERK), has been implicated as mediators of plasticity in several pain models. Here, we investigated whether M3G could influence the ERK activation in the NO-cGMP-PKG pathway. The i.t. injection of M3G evoked a definite activation of ERK in the lumbar dorsal spinal cord, which was prevented dose-dependently by U0126, a MAP kinase-ERK inhibitor. The selective nNOS inhibitor N(omega)-propyl-l-arginine, the selective iNOS inhibitor W1400, the soluble guanylate cyclase inhibitor ODQ and the PKG inhibitor KT-5823 inhibited dose-dependently the nociceptive response to i.t. M3G. In western blotting analysis, inhibiting M3G-induced nociceptive response using these inhibitors resulted in a significant blockade of ERK activation induced by M3G in the spinal cord. Taken together, these results suggest that activation of the spinal ERK signaling in the NO-cGMP-PKG pathway contributes to i.t. M3G-evoked nociceptive response.

Topics: Analgesics; Animals; Behavior, Animal; Butadienes; Central Nervous System Stimulants; Cyclic GMP; Dose-Response Relationship, Drug; Enzyme Activation; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Injections, Spinal; Isoindoles; Male; Mice; Mice, Inbred Strains; Morphine Derivatives; Nitric Oxide; Nitriles; Nociceptors; Pain; Peptide Fragments; Piperidines; Pyrrolidonecarboxylic Acid; Receptors, Tachykinin; Specific Pathogen-Free Organisms; Spinal Cord; Stereoisomerism; Substance P

Allodynia or hyperalgesia induced by peripheral nerve injury may be involved in changes in the sensitivity of neurotransmitters at the spinal cord level. In order to clarify the functional role of neurotransmitters in peripheral nerve injury, we used rats with nerve injury induced by chronic constriction of the sciatic nerve (CCI rat model) and estimated the effects of the intrathecal injection of drugs known to affect glutamate and tachykinin receptors. In sham-operated rats, the NMDA receptor agonist NMDA and AMPA-kinate receptor agonist RS-(5)-bromowillardin reduced withdrawal latency. The non-competitive NMDA receptor antagonist MK-801, competitive NMDA receptor antagonist AP-5 and AMPA-kinate receptor antagonist NBQX increased withdrawal latency. Substance P (SP) increased the withdrawal latency but only transitorily. The NK1 receptor antagonist RP67580 increased withdrawal latency, but the NK2 receptor antagonist SR48968 did not show an effect. In CCI rats, RS-(5)-bromowillardin reduced withdrawal latency, but NMDA did not show an effect. NBQX increased withdrawal latency, while MK-801 and AP-5 showed little or no effect. SP reduced withdrawal latency, and both RP67580 and SR48968 increased it. These results indicate that the alteration in sensitivity of ionotropic glutamate receptors and tachykinin receptors in the spinal cord contribute to development and maintenance of nerve injury-evoked neuropathic pain.

Topics: Alanine; Analgesics; Animals; Behavior, Animal; Benzamides; Dizocilpine Maleate; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Indoles; Isoindoles; Male; N-Methylaspartate; Pain; Pain Measurement; Piperidines; Quinoxalines; Rats; Rats, Sprague-Dawley; Receptors, AMPA; Receptors, Kainic Acid; Receptors, Tachykinin; Sciatic Nerve; Spinal Cord; Substance P; Valine

Tachykinins are important mediators in neuromuscular signalling but have not been thoroughly characterised in the mouse gut. We investigated the participation of tachykinin receptors in contractility of circular muscle strips of the mouse ileum.. Electrical field stimulation (EFS) of excitatory nonadrenergic noncholinergic (NANC) nerves induced frequency-dependent contractions which were mimicked by substance P (SP). Desensitisation of SP and NK(1), NK(2) or NK(3) receptors significantly reduced contractions to EFS. The NK(1) receptor blocker RP67580 significantly inhibited NANC contractions to EFS. The NK(2) and NK(3) receptor blockers nepadutant and SR142801 did not affect NANC contractions per se but increased the RP67580-induced inhibition of NANC contractions to EFS. Contractions to SP were significantly reduced by RP67580 but not affected by nepadutant or SR142801. The NK(1) and NK(2) receptor agonists, septide and [beta-ala(8)]-NKA 4-10 (beta-A-NKA), respectively, but not the NK(3) receptor agonist senktide-induced dose-dependent contractions. Atropine inhibited and l-NNA augmented contractions to septide. Contractions to beta-A-NKA were insensitive to atropine but augmented by l-NNA.. Tachykinins mediate NANC contractions to EFS in the mouse small intestine. Endogenously released tachykinins activate mainly NK(1) receptors, located on cholinergic nerves and smooth muscle cells and, to a lesser degree, NK(2) and NK(3) receptors, most likely located presynaptically.

Topics: Action Potentials; Analgesics; Animals; Antipsychotic Agents; Atropine; Electric Stimulation; Ileum; Indoles; Isoindoles; Mice; Muscarinic Antagonists; Muscle Contraction; Muscle, Smooth; Neurons; Nitroarginine; Peptide Fragments; Piperidines; Pyrrolidonecarboxylic Acid; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Substance P

The mechanism(s) underlying stress-induced colonic hypersensitivity (SICH) are incompletely understood. Our aims were to assess the acute and delayed (24 h) effect of water avoidance (WA) stress on visceral nociception in awake male Wistar rats and to evaluate the role of two stress-related modulation systems: the substance P/neurokinin-1 receptor (SP/NK(1)R) and the corticotropin-releasing factor (CRF)/CRF(1) receptor (CRF/CRF(1)R) systems, as well as the possible involvement of the sympathetic nervous system. Visceral pain responses were measured as the visceromotor response to colorectal distension (CRD) at baseline, immediately after WA and again 24 h later. The NK(1)R antagonists RP-67580 and SR-140333 and the CRF(1)R antagonist CP-154526 were injected 15 min before WA or 1 h before the CRD on day 2. Chemical sympathectomy was performed by repeated injection of 6-hydroxydopamine. WA stress resulted in a significant increase in the visceromotor response on day 2, but no change immediately after WA. Injection of CP-154526 abolished delayed SICH when applied either before WA stress or before the CRD on day 2. Both NK(1)R antagonists only decreased SICH when injected before the CRD on day 2. Chemical sympathectomy did not affect delayed SICH. Our results indicate that in male Wistar rats, both NK(1)R and CRF(1)R activation, but not sympathetic nervous system activation, play a role in the development of SICH.

Topics: Animals; Colon; Electromyography; Fear; Hypersensitivity, Delayed; Immunohistochemistry; Indoles; Isoindoles; Male; Muscle, Smooth; Neurokinin-1 Receptor Antagonists; Nociceptors; Physical Stimulation; Piperidines; Pyrimidines; Pyrroles; Quinuclidines; Rats; Rats, Wistar; Receptors, Corticotropin-Releasing Hormone; Receptors, Neurokinin-1; Stress, Psychological; Sympathectomy, Chemical; Sympathetic Nervous System

Intrathecal injection of histamine elicited a behavioral response consisting of scratching, biting and licking in conscious mice. Here, we have examined the involvement of substance P (SP) by using intrathecal injection of tachykinin neurokinin (NK)(1) receptor antagonists and SP antiserum. Histamine-induced behavioral response was evoked significantly 5-10 min after intrathecal injection and reached a maximum at 10-15 min. Dose-dependency of the induced response showed a bell-shaped pattern from 200 to 3200 pmol, and maximum effect was observed at 800-1000 pmol. The H(1) receptor antagonist, d-chlorpheniramine and pyrilamine but not the H(2) receptor antagonists, ranitidine and zolantidine, inhibited histamine-induced behavioral response. The NK(1) receptor antagonists, CP-99,994, RP-67580 and sendide, inhibited histamine-induced behavioral response in a dose-dependent manner. A significant antagonistic effect of [D-Phe(7), D-His(9)]SP (6-11), a selective antagonist for SP receptors, was observed against histamine-induced response. The NK(2) receptor antagonist, MEN-10376, had no effect on the response elicited by histamine. Pretreatment with SP antiserum resulted in a significant reduction of the response to histamine. No significant reduction of histamine-induced response was detected in mice pretreated with NK A antiserum. The present results suggest that elicitation of scratching, biting and licking behavior induced by intrathecal injection of histamine may be largely mediated by NK(1) receptors via H(1) receptors in the spinal cord.

Topics: Animals; Behavior, Animal; Dose-Response Relationship, Drug; Histamine; Histamine H1 Antagonists; Histamine H2 Antagonists; Indoles; Injections, Spinal; Isoindoles; Male; Mice; Neurokinin A; Neurokinin-1 Receptor Antagonists; Peptide Fragments; Piperidines; Pyrrolidonecarboxylic Acid; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Spinal Cord; Substance P

Extensive screening of compound libraries was undertaken to identify compounds with high affinity for the rat NK(1) receptor based on inhibition of [(125)I]-substance P binding. RP67580, SR140333, NKP-608 and GR205171 were selected as compounds of interest, with cloned rat NK(1) receptor binding K(i) values of 0.15-1.9 nM. Despite their high binding affinity, NKP-608 and GR205171 exhibited only a moderate functional antagonism of substance P-induced inositol-1-phosphate accumulation and acidification rate at 1 microM using cloned or native rat NK(1) receptors in vitro. The ability of the compounds to penetrate the CNS was determined by inhibition of NK(1) agonist-induced behaviours in gerbils and rats. GR205171 and NKP-608 potently inhibited GR73632-induced foot drumming in gerbils (ID(50) 0.04 and 0.2 mg/kg i.v., respectively). In contrast, RP67580 and SR140333 were poorly brain penetrant in gerbils (no inhibition at 10 mg/kg i.v.) and were not examined further in vivo. In rats, only high doses of GR205171 (10 or 30 mg/kg s.c.) inhibited NK(1) agonist-induced sniffing and hypertension, whilst NKP-608 (1 or 10 mg/kg i.p.) was without effect. GR205171 (3-30 mg/kg s.c.) caused only partial inhibition of separation-induced vocalisations in rat pups, a response that is known to be NK(1) receptor mediated in other species. These observations demonstrate the shortcomings of currently available NK(1) receptor antagonists for rat psychopharmacology assays.

Topics: Animals; CHO Cells; Cricetinae; Dose-Response Relationship, Drug; Female; Gerbillinae; Humans; Indoles; Isoindoles; Male; Neurokinin-1 Receptor Antagonists; Piperidines; Quinolines; Quinuclidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-1; Tetrazoles; Tumor Cells, Cultured

Mast cell activation, bronchoconstriction, inflammation and airway hyperreactivity are prominent features of non-atopic hypersensitivity reactions in mouse airways. We studied the role of tachykinin receptors in mice that were skin-sensitized with dinitrofluorobenzene (or vehicle) and challenged intranasally with dinitrobenzene sulfonic acid. Tachykinin NK1 receptor blockade, by treatment with the antagonist RP67580, or absence of the tachykinin NK1 receptor resulted in a strong reduction in the accumulation of neutrophils in the bronchoalveolar lavage fluid, and in the development of tracheal hyperreactivity in mice 48 h after challenge. In contrast, treatment with the tachykinin NK2 receptor antagonist SR48968 did not affect the dinitrofluorobenzene-induced hypersensitivity reaction. We have previously shown that mast cells play a crucial role in the development of non-atopic asthma. However, we did not observe an inhibitory effect of the tachykinin receptor antagonists or the genetic absence of tachykinin NK1 receptors on mast cell protease release. In conclusion, distal from mast cell activation, the tachykinin NK1 receptor is crucial for the infiltration of pulmonary neutrophils and the development of tracheal hyperreactivity in non-atopic asthma.

Topics: Administration, Intranasal; Airway Obstruction; Animals; Benzamides; Dinitrofluorobenzene; Hypersensitivity; In Vitro Techniques; Indoles; Inflammation; Isoindoles; Leukocytes; Male; Mast Cells; Mice; Mice, Inbred BALB C; Mice, Knockout; Neurokinin-1 Receptor Antagonists; Piperidines; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Trachea

Tachykinins are known to be involved in the processing of information leading to central sensitization and nociception. Using an animal model of repetitive colorectal distensions (CRD), we investigated the effect of spinal administration of tachykinin receptor antagonists in the mediation of visceral hypersensitivity. Intrathecal administration of the NK(1) receptor antagonist RP-67,580 (6.5 nmol) and the NK(3) receptor antagonist R-820 (6.5 nmol) completely blocked the CRD-induced hyperalgesia for both noxious and innocuous stimuli. The intrathecal administration of SR-48,968, a tachykinin NK(2) receptor antagonist, did not affect the visceral pain threshold of hypersensitive animals. Thus, the results from the present experiment support the concept that tachykinins with actions at spinal NK(1) and NK(3) but not NK(2) receptor sites are involved in visceral hypersensitivity mediated by nociceptive and non-nociceptive afferent inputs.

Topics: Animals; Benzamides; Digestive System; Hyperalgesia; Indoles; Injections, Spinal; Isoindoles; Male; Neurokinin-1 Receptor Antagonists; Nociceptors; Oligopeptides; Pain; Pain Threshold; Physical Stimulation; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Receptors, Tachykinin; Visceral Afferents

We investigated the effect of topical application of capsaicin cream on withdrawal latency in the hind foot of rat in response to radiant heat in an experimental model of neuropathic pain. A neuropathic state was induced by loose ligation of the sciatic nerve with chromic gut suture. A marked thermal hyperalgesia was observed in response to heat stimulus applied to the operated side from 3 days through 2 weeks, followed by a gradual return to the control level by 35 days after surgery. Capsaicin cream applied to both the bilateral hind instep and sole once a day for a continuous period of 2 weeks or 4 weeks alleviated thermal hyperalgesia in a dose-dependent manner. A remarkable effect was observed 2 weeks after the start of the application and this effect proved to be reversible. On the other hand, in sham-operated animals when capsaicin cream was applied once daily from day 7 after the sham operation, from 1 day through 3 weeks following capsaicin application, withdrawal latency of the sham-operated paws of the capsaicin-treated group was significantly increased as compared to that of the vehicle cream-treated group. The effects of antagonists of glutamate receptor and tachykinin receptors were investigated 7 days post surgery. Pretreatment with MK-801 (0.5 mg kg(-1), i.p.), but not with CNQX (0.5 mg kg(-1), i.p.), reversed the thermal hyperalgesia following nerve injury. Neither of RP67580 (1--10 mg kg(-1), i.p.) nor SR48968 (1--10 mg kg(-1), i.p.) had any effect on the withdrawal latency in the injured and non-injured hind paw. These results suggest that although the manifestation of effectiveness may be delayed by changes in networks of neurotransmitters related to the nociceptive pathways following nerve injury, longer-term repetitive application of capsaicin cream has a significant therapeutic effect on subjects with painful peripheral neuropathy.

Topics: 6-Cyano-7-nitroquinoxaline-2,3-dione; Analgesics; Animals; Benzamides; Capsaicin; Carrageenan; Disease Models, Animal; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Hyperalgesia; Indoles; Isoindoles; Male; Neuroprotective Agents; Pain; Peripheral Nervous System Diseases; Piperidines; Postoperative Period; Rats; Rats, Sprague-Dawley; Sciatic Nerve; Substance Withdrawal Syndrome; Time Factors

1. The effects of tachykinin NK(1), NK(2) and NK(3) receptor agonists and antagonists were measured on blood pressure (MAP) and heart rate (HR) after bilateral microinjection into the substantia nigra (SN) of awake, unrestrained rats. 2. Increasing doses (25 pmol - 1 nmol) of selective agonists at NK(1) ([Sar(9),Met(O(2))(11)]SP), NK(2) ([beta-Ala(8)]NKA(4 - 10)) and NK(3) (senktide) receptors into the SN produced tachycardia which was selectively and reversibly blocked by the prior injection of tachykinin antagonists at NK(1) (RP67580, 250 pmol), NK(2) (SR48968, 250 pmol) and NK(3) (R-820, 500 pmol) receptor. A rapid fall in MAP followed by a pressor response was seen with 1 nmol of [Sar(9),Met(O(2))(11)]SP. Behavioural activity was elicited by 1 nmol of [Sar(9),Met(O(2)(11)]SP (sniffing > face washing = grooming) and senktide (sniffing > wet dog shake > rearing = locomotion). Tachykinin antagonists had no direct cardiovascular or behavioural effects. 3. The tachycardia produced by 100 pmol of [beta-Ala(8)]NKA(4 - 10) or senktide was abolished by an i.v. treatment with atenolol (beta(1)-adrenoceptor antagonist, 5 mg kg(-1)) while that evoked by [Sar(9),Met(O(2))(11)]SP was reduced. A combination of atenolol (5 mg kg(-1)) and atropine (muscarinic antagonist, 1 mg kg(-1)) blocked the response evoked by [Sar(9),Met(O(2))(11)]SP. 4. These data suggest that the SN is a potential site of modulation of cardiac activity by tachykinins. In addition to the withdrawal of the cardiovagal activity by NK(1) receptor, the three tachykinin receptors appear to increase the sympatho/adrenal drive to the heart. This occurs independently of changes in MAP and behaviour. Hence, this study highlights a new central regulatory mechanism of cardiac autonomic activity.

Topics: Adrenergic beta-Antagonists; Animals; Atenolol; Atropine; Benzamides; Blood Pressure; Hemodynamics; Indoles; Isoindoles; Male; Microinjections; Muscarinic Antagonists; Neurokinin-1 Receptor Antagonists; Oligopeptides; Peptide Fragments; Piperidines; Rats; Rats, Wistar; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Receptors, Tachykinin; Substance P; Substantia Nigra; Tachycardia; Tachykinins

To clarify the roles of tachykinins in volume-induced micturition and in bladder hyperactivity, presumed to originate from supraspinal structures, normal, female Sprague-Dawley rats were investigated cystometrically before and after intracerebroventricular (i.c.v) administration of RP 67,580, a selective antagonist of NK-1 receptors, and/or SR 48,968, a selective antagonist of NK-2 receptors. The effects of RP 67,580 and SR 48,968 on intra-peritoneal (i.p.) L-dopa-induced bladder hyperactivity were also investigated. I.c.v. administration of RP 67,580 (20 nmol) SR 48,968 (20 nmol) suppressed micturition. Combination of i.c.v. RP 67, 580 (2 nmol) and SR 48,968 (2 nmol) significantly decreased micturition pressure (18%), and increased bladder capacity (26%), micturition volume (18%), and residual volume (223%). In rats pretreated with i.p. carbidopa 50 mg/kg, i.p. L-dopa 50 mg/kg caused bladder hyperactivity that was attenuated by the combination of i.c. v. RP 67,580 (2 nmol) and SR 48,968 (2 nmol). The results suggest that tachykinins, via stimulation of NK receptors in supraspinal structures, are involved in both volume and L-dopa-induced stimulation of bladder activity. This may imply that tachykinins can influence both the supraspinal and spinal control of the urinary bladder. It also implies that supraspinal NK receptors are a possible target for drugs aimed for elimination of bladder hyperactivity mediated via these pathways. Neurourol. Urodynam. 19:101-109, 2000.

Topics: Animals; Benzamides; Brain; Female; Indoles; Injections, Intraventricular; Isoindoles; Levodopa; Methylene Blue; Neurokinin-1 Receptor Antagonists; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-2; Reference Values; Tachykinins; Tissue Distribution; Urinary Bladder; Urine

Recent pharmacological evidence has implicated substance P and neurokinin A, natural ligands for neurokinin-1 and neurokinin-2 receptors, respectively, as neurotransmitters in brain neuronal circuits activated upon noxious stimulation. The expression of the inducible transcription factor, c-Fos, was used to identify areas in the brain activated by a noxious stimulus (the subcutaneous injection of formalin), and to investigate the effects of intracerebroventricular administration of selective, nonpeptide antagonists for neurokinin-1 and neurokinin-2 tachykinin receptors on the neural activity in these areas and on the behavioural response to formalin-induced pain. Formalin (5%, 50 microl), injected subcutaneously through a chronically implanted catheter in the region of the lower hindlimb, increased c-Fos expression in a number of brain areas related to nociceptive transmission or the integration of stress responses. Grooming behaviour, licking and biting directed to the injected site, was the most frequent behavioural response. Intracerebroventricular pretreatment of rats with either RP 67580 (500 pmol), the active enantiomer of a neurokinin-1 receptor antagonist, or with SR 48968 (500 pmol), the active enantiomer of a neurokinin-2 receptor antagonist, reduced the formalin-induced c-Fos staining in the prefrontal cortex, dorsomedial and ventromedial nuclei of the hypothalamus, the locus coeruleus and the periaqueductal gray. The neurokinin-1, but not the neurokinin-2, receptor antagonist attenuated the formalin-induced activation of c-Fos in the paraventricular nucleus of the hypothalamus. Simultaneous intracerebroventricular pretreatment with both neurokinin-1 and neurokinin-2 receptor antagonists did not produce any additional inhibitory effect on the post-formalin c-Fos expression. None of the tachykinin receptor antagonists had an effect on the formalin-induced c-Fos expression in the septohypothalamic nucleus, medial thalamus, parabrachial nucleus and central amygdaloid nucleus, indicating that neurotransmitters other than neurokinins are most probably responsible for the activation of these areas in response to noxious stimulation. While both tachykinin receptor antagonists reduced the grooming behaviour to formalin, the neurokinin-1 receptor antagonist was clearly more effective than the neurokinin-2 receptor antagonist. Intracerebroventricular pretreatment of rats with the inactive enantiomers of the tachykinin receptor antagonists, RP 68651 and S

Topics: Analgesics; Animals; Behavior, Animal; Benzamides; Brain; Formaldehyde; Grooming; Indoles; Injections, Intraventricular; Isoindoles; Male; Pain; Piperidines; Proto-Oncogene Proteins c-fos; Rats; Rats, Wistar; Receptors, Tachykinin

To elucidate the interaction between nitric oxide (NO) and substance P (SP) in neurogenic inflammatory responses, we measured the change in the degree of Evans blue leakage and NO levels in perfusate from the subcutaneous space in the rat instep following noxious heat stimulation (47 degrees C for 30 min). Furthermore, the effects of drugs affecting nitric oxide synthase were examined. Noxious heat stimulation caused on an increase in NOx, or NO2- and NO3- into the perfusate in parallel with plasma extravasation. Nw-nitro-L-arginine methylester (L-NAME: 100 mg/kg once daily.) intraperitoneally (i.p.) given five times (chronic treatment) significantly suppressed the increase in Evans blue extravasation induced by heat stimulation, whereas acute treatments with L- and D-NAME (100 mg/kg once, i.p.) did not show any significant effect. NO release induced by heating also was significantly suppressed by chronic pretreatment with L-NAME, but not by acute treatment. SP (10(-5) M) applied into the perfusate caused a remarkable increase in the NOx release into the perfusate. Intra-arterial injection of RP67580 (1 mg/kg) on the perfused side, but not SR48968 (1 mg/kg), significantly attenuated the increases in Evans blue leakage and NOx release during heat stimulation. These results suggest that heat-induced SP release from the peripheral endings of small-diameter afferent fibers causes NO generation through NK-1R, and that this gas act to elicit or enhance inflammatory responses.

Topics: Analgesics; Animals; Benzamides; Evans Blue; Forelimb; Hyperthermia, Induced; Indoles; Inflammation; Isoindoles; Male; Neurons, Afferent; NG-Nitroarginine Methyl Ester; Nitric Oxide; Piperidines; Rats; Rats, Sprague-Dawley; Skin; Substance P

The aim of this study was to determine whether tachykinin receptors might be involved in the mediation of the atropine- and capsaicin-sensitive third phase of a triphasic contractile response to vagal nerve stimulation of the guinea-pig isolated oesophagus. The third phase was inhibited 23.3 +/- 1.7% (P< 0.001, n = 5) and 30. 8 +/- 9.0% (P< 0.05, n = 5) by the NK(3)receptor antagonist, SR 142 801 (0.1 and 1 microM respectively). SR 142 801 (0.1 and 1 microM) had no significant effect on the response to a submaximal concentration of acetylcholine (0.1 mM, n = 4). The third phase was not significantly affected by NK(1)or NK(2)receptor antagonists. Thus, in the guinea-pig oesophagus, it appears that while NK(1)and NK(2)receptors are not involved, NK(3)receptors play a minor role in mediating a contractile response when afferent neurones are excited by vagal nerve stimulation.

Topics: Animals; Benzamides; Electric Stimulation; Esophagus; Guinea Pigs; In Vitro Techniques; Indoles; Isoindoles; Male; Muscle Contraction; Neurokinin-1 Receptor Antagonists; Piperidines; Quinuclidines; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Receptors, Tachykinin; Vagus Nerve

1. The respiratory response to microinjection of tachykinins and analogues into the commissural nucleus of the solitary tract (cNTS) of urethane-anaesthetized rats was investigated in the presence and absence of selective tachykinin NK(1), NK(2) and NK(3) antagonists (RP 67580, SR 48968 and SR 142801, respectively). 2. All tachykinins, except for the selective NK(2) agonist, [Nle(10)]-NKA(4-10), increased tidal volume (VT). The rank potency order of naturally-occurring tachykinins was neurokinin A (NKA)> or =substance P (SP)>>NKB, whereas the rank order for selective analogues was senktide> or = septide>> [Sar(9),Met(O(2))(11)]-SP>>[Nle(10)]-NKA(4-10). Septide (NK(1)-selective) and senktide (NK(3)-selective) were 22 fold more potent (pD(2) approximately 12) at stimulating VT than SP (pD(2) approximately 10.5). 3. Tachykinin agonists produced varying degrees of respiratory slowing, independent of changes in VT. At doses producing maximum stimulation of VT, agonists induced either a mild (<10 breaths min(-1) decrease; SP and septide), moderate (10 - 25 breaths min(-1) decrease; NKA, NKB and [Sar(9),Met(O(2)]-SP) or severe ( approximately 40 breaths min(-1) decrease; senktide) bradypnoea. [Nle(10)]-NKA(4-10) produced a dose-dependent bradypnoea without affecting VT. 4. RP 67580 significantly attenuated the VT response to SP (33 pmol) and NKA (10 pmol) but not NKB (100 pmol). In the presence of RP 67580, the mild bradypnoeic response to NKB was significantly enhanced whereas SP and NKA induced a bradyapnea which was not observed in the absence of RP 67580. SR 48968 had no effect on the VT response to SP or NKB, markedly enhanced the VT response to NKA and completely blocked the bradypnoeic response to [Nle(10)]-NKA(4-10). Only SR142801 attenuated the VT response to NKB. 5. The present data suggest that all three tachykinin receptors (NK(1), NK(2) and NK(3)) are present in the cNTS and are involved in the central control of respiration.

Topics: Animals; Benzamides; Indoles; Isoindoles; Male; Microinjections; Neurokinin A; Neurokinin B; Neurokinin-1 Receptor Antagonists; Piperidines; Rats; Rats, Wistar; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Receptors, Tachykinin; Respiratory Mechanics; Solitary Nucleus; Substance P; Tachykinins; Tidal Volume

Binding experiments performed with [(125)I]-NKA allowed us to demonstrate the presence of "septide-sensitive" specific binding sites on membranes from rat CHO cells transfected with the NK(1) receptor cDNA (CHO-rat-NK1 cells), human astrocytoma U373 MG, or mouse cortical astrocytes, cells which express NK(1) but neither NK(2) nor NK(3) receptors. In all cases, [(125)I]-NKA was specifically bound with high affinity (2 to 5 nM) to a single population of sites. In the three preparations, pharmacological characteristics of [(125)I]-NKA binding sites were notably different from those of classical NK(1) binding sites selectively labelled with [(125)I]-BHSP. Indeed, the endogenous tachykinins NKA, NPK, and NKB and the septide-like compounds such as septide, SP(6-11), ALIE-124, [Apa(9-10)]SP, or [Lys(5)]NKA(4-10) had a much higher affinity for [(125)I]-NKA than [(125)I]-BHSP binding sites. Interestingly, differences were also found in the ratio of B(max) values for [(125)I]-NKA and [(125)I]-BHSP specific bindings from one tissue to another. These latter observations suggest that these two types of NK(1) binding sites are present on distinct NK(1) receptor isoforms (or conformers). Finally, while several tachykinins and tachykinin-related compounds stimulated cAMP formation or increased inositol phosphate accumulation in CHO-rat-NK1 cells, these compounds only increased the accumulation of inositol phosphates in the two other preparations.

Topics: Animals; Binding Sites; CHO Cells; Cricetinae; Humans; Indoles; Iodine Radioisotopes; Isoindoles; Mice; Neurokinin A; Neurokinin-1 Receptor Antagonists; Peptide Fragments; Piperidines; Protein Isoforms; Pyrrolidonecarboxylic Acid; Radioligand Assay; Rats; Receptors, Neurokinin-1; Substance P; Tetrazoles; Tumor Cells, Cultured

In order to clarify the role of supraspinal tachykinins in volume-induced micturition and in bladder hyperactivity secondary to bladder outlet obstruction, conscious, normal, female Sprague-Dawley rats were investigated cystometrically before and after intracerebroventricular administration of RP 67,580, a selective antagonist of neurokinin (NK)-1 receptors and/or SR 48,968, a selective antagonist of NK-2 receptors. In normal rats, RP 67,580 or SR 48,968, at a dose of 2 nmol, caused no marked changes in cystometric parameters. Higher doses (up to 20 nmol) caused dose-dependent decreases in micturition pressure and increased bladder capacity, micturition volume and residual urine. A combination of the two drugs, each at a dose of 2 nmol, significantly decreased micturition pressure and increased bladder capacity. In rats with bladder outlet obstruction, the antagonists suppressed micturition dose-dependently, producing urinary retention in two out of eight rats already at a dose of 2 nmol. At a dose of 20 nmol, dribbling incontinence, due to urinary retention, was seen in five out of ten rats. A combination of the two drugs (2 nmol of each drug) caused urinary retention in three out of nine animals and significantly increased bladder capacity, micturition volume and residual volume. The results suggest that outflow obstruction in rats increases the effects of tachykinins in supraspinal structures involved in micturition, and that antagonism of supraspinal NK-receptors may depress the micturition reflex. Whether or not this implies that supraspinal NK-receptors can be targets for drugs aimed for inhibiting bladder hyperactivity in humans should be explored.

Topics: Analgesics; Animals; Benzamides; Catheterization; Female; Indoles; Isoindoles; Methylene Blue; Neurokinin-1 Receptor Antagonists; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-2; Tachykinins; Tissue Distribution; Urinary Bladder; Urinary Bladder Neck Obstruction; Urinary Incontinence; Urination

A better knowledge of the pathophysiology of chronic pain could help to improve the treatment of patients with such syndrome. The aim of the present work was to elucidate the possible involvement of spinal substance P and neurokinin A in the mechanical and thermal allodynia observed in streptozocin-induced diabetic rats. A tachykinin NK(1) receptor antagonist, RP-67,580 ((3aR,7aR) -7, 7-diphenyl-2-(1-imino-2(2-methoxy phenyl)-ethyl) perhydroisoindol-4-one hydrochloride), a tachykinin NK(2) receptor antagonist, SR-48,968 ((S)-N-methyl (4-(acetylamino-4phenylpiperidino)-2-(3, 4-dichlorophenyl) butyl) benzamide) and their respective enantiomers were intrathecally administered 4 weeks after the induction of diabetes. Mechanical and thermal allodynia were evaluated before and up to 60 min after injection. The tachykinin receptor antagonists at the highest doses (10 and 25 microgram) significantly reduced allodynia, their enantiomers being inactive. Both of these data suggest the involvement of substance P and neurokinin A in the neuropathy-induced allodynia and offer a novel hypothesis to treat chronic pain due to diabetes.

Topics: Analgesics; Animals; Benzamides; Diabetes Mellitus, Experimental; Dose-Response Relationship, Drug; Indoles; Isoindoles; Male; Neurokinin-1 Receptor Antagonists; Pain; Pain Threshold; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-2; Tachykinins; Temperature; Time Factors

Substance P is an important neuromediator in spinal synaptic transmission, particularly in processing nociceptive afferent information. The effects of substance P are mediated by activation of the neurokinin 1 receptor. Evidence has suggested that excitatory amino acids such as glutamate, and prostaglandins including prostaglandin E2 are involved in the enhanced spinal excitability and hyperalgesia produced by spinal substance P. In the present study, we have demonstrated that intrathecal injection of substance P (20 nmol) in rats chronically implanted with intrathecal dialysis catheters induced a decrease in thermal paw withdrawal latency (before: 10.4+/-0.3 s; after 7.6+/-0.6 s), which was accompanied by an increase in prostaglandin E2 (362+/-37% of baseline), glutamate (267+/-84%) and taurine (279+/-57%), but not glycine, glutamine, serine or asparagine. Intrathecal injection of artificial cerebrospinal fluid had no effect upon the behavior or release. Substance P-induced thermal hyperalgesia and prostaglandin E2 release were significantly attenuated by a selective neurokinin 1 receptor antagonist RP67580, but not by an enantiomer RP68651. However, substance P-induced release of glutamate and taurine was not reduced by treatment with RP67580. SR140333, another neurokinin 1 receptor antagonist, displayed the same effects as RP67580 (i.e. block of thermal hyperalgesia and prostaglandin E2 release, but not release of amino acids). These results provide direct evidence suggesting that the spinal substance P-induced thermal hyperalgesia is mediated by an increase in spinal prostaglandin E2 via activation of the neurokinin 1 receptor. These findings define an important linkage between small afferents, sensory neurotransmitter release and spinal prostanoids in the cascade of spinally-mediated hyperalgesia. The evoked release of glutamate is apparently not a result of activation of neurokinin 1 receptors. Accordingly, consistent with other pharmacological data, acute spinal glutamate release does not contribute to the hyperalgesia induced by activation of spinal neurokinin 1 receptors.

Topics: Amino Acids; Analgesics; Animals; Dinoprostone; Hot Temperature; Hyperalgesia; Indoles; Injections, Spinal; Isoindoles; Male; Neurokinin-1 Receptor Antagonists; Piperidines; Quinuclidines; Rats; Rats, Inbred Strains; Spinal Cord; Substance P

The anti-emetic potential of CP-122,721 ((+)-2S,3S)-3-(2-methoxy-5-trifluoromethoxybenzyl)amino-2-phenylpi peridine), CP-99,994 ((+)-(2S,3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine), CP-100,263 ((-)-(2R,3R)-3-(2-methoxybenzylamino)-2-phenylpiperidine), RP 67580 ((3R, 7aR)-7,7-diphenyl-2-[1-imino-2-(2-methoxyphenyl)ethyl] po-hydroisoindol-4-one), FK 888 (N2-[(4R)-4-hydroxy-1-(1-methyl-1H-in-dole-3-yl)carbonyl-L-propyl] -N-methyl-N-phenylmethyl-1-3-(2-naphthyl)-alaninamide) and GR 82334 ([D-Pro9[spiro-g-lactam]Leu10]-physalaemin-(1-11)) was investigated to inhibit nicotine (5 mg/kg, s.c.)-, copper sulphate pentahydrate (120 mg/kg, intragastric)- and motion (4 cm horizontal displacement at 1 Hz for 5 min)-induced emesis in Suncus murinus. A 30 min intraperitoneal pre-treatment with CP-122,721, CP-99,994, RP 67580 and FK 888 significantly (P < 0.05) antagonized nicotine-induced emesis with ID50 values of 2.1, 2.3, 13.5 and 19.2 mg/kg, respectively CP-100,263, the less active enantiomer of CP-99,994, was inactive at doses up to 10 mg/kg. Infusion of GR 82334, CP-122,721, CP-99,994 and FK 888 into the dorsal vagal complex of the hindbrain also antagonized nicotine-induced emesis yielding ID50 values of 1.1, 3.0, 3.3 and 58.0 microg/dorsal vagal complex, respectively RP 67580 and CP-100,263 were inactive. RP 67580 and FK 888 failed to antagonize copper sulphate-induced emesis but CP-122,721 and CP-99,994 were active yielding ID50 values of 2.2 and 3.0 mg/kg, i.p., respectively. CP-99,994 also completely prevented motion-induced emesis at 10 mg/kg, i.p. (P < 0.05) and RP 67580 produced a significant reduction of motion-induced emesis at 10 mg/kg, i.p. (P < 0.05). These studies provide evidence of a central site of action of tachykinin NK1 receptor antagonists to inhibit nicotine-induced emesis in S. murinus and confirm the broad profile of inhibitory action. The rank order of potency of the antagonists following the intra-dorsal vagal complex administration suggests that the S. murinus tachykinin NK1 receptor has a unique pharmacological profile.

Topics: Animals; Antiemetics; Copper Sulfate; Dipeptides; Dose-Response Relationship, Drug; Emetics; Female; Ganglionic Stimulants; Indoles; Infusions, Parenteral; Isoindoles; Male; Motion Sickness; Neurokinin-1 Receptor Antagonists; Nicotine; Physalaemin; Piperidines; Shrews; Stereoisomerism; Vomiting

1. The respiratory response to microinjection of capsaicin into the commissural nucleus of the solitary tract (cNTS) of urethane-anaesthetized rats was investigated in the absence and presence of the competitive vanilloid (capsaicin) antagonist, capsazepine, and selective tachykinin NK1, NK2 and NK3 antagonists (RP 67580, SR 48968 and SR 142801, respectively). 2. Microinjection of capsaicin reduced respiratory frequency but not tidal volume (VT), leading to an overall reduction in minute ventilation (VE). The effect was dose-dependent between 0.5 and 2 nmol capsaicin. Doses greater than 2 nmol produced apnoea. Tachyphylaxis was observed following repeated injection of capsaicin (1 nmol, 30 min apart). 3. Capsazepine (1 nmol) had no effect on frequency or VT when injected alone but completely blocked the respiratory response to capsaicin (1 nmol). 4. RP 67580 (1 but not 5 nmol) alone depressed frequency and VT slightly. Moreover, RP 67580 appeared to potentiate the bradypnoeic effect of capsaicin. In contrast, SR 48968 and SR 142801 (1 and 5 nmol) alone had no significant effect on respiration. However, both agents significantly attenuated the reduction in frequency produced by capsaicin. 5. In conclusion, microinjection of capsaicin into the cNTS decreases overall ventilation, primarily by reducing frequency. The action of capsaicin appears from the data to be mediated by vanilloid receptors since it is blocked by the competitive vanilloid antagonist capsazepine and is subject to tachyphylaxis. However, since NK2 (SR 48968) and NK3 (SR 142801) receptor antagonists block the actions of capsaicin, we propose that capsaicin acts also by releasing tachykinins from central afferent terminals in the cNTS.

Topics: Anesthesia; Animals; Benzamides; Capsaicin; Dose-Response Relationship, Drug; Indoles; Isoindoles; Male; Microinjections; Neurokinin-1 Receptor Antagonists; Piperidines; Rats; Rats, Wistar; Receptors, Drug; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Receptors, Tachykinin; Respiratory Mechanics; Solitary Nucleus; Tidal Volume

To define the effects of antisense oligonucleotides on spinal neurokinin 1 (NK1) receptor function in nociceptive processing, several antisense oligonucleotides directed against the NK1 receptor mRNA were intrathecally injected into rats via an implanted catheter, and their effect on the behavioural response to formalin injected into the paw was assessed. We observed that there was no significant reduction of pain behaviour or immunostaining of spinal NK1 receptors after repeated daily intrathecal treatment with an antisense oligonucleotide. However, spinal application of substance P (SP) in the antisense oligonucleotide-treated animals resulted in a profound and long-lasting reduction in the behavioural response to formalin injection, and a parallel reduction in the NK1 receptor immunoreactivity normally observed in spinal dorsal horn. Intrathecal SP in the control groups, i.e., rats treated with an oligonucleotide containing four mismatched bases, the corresponding sense oligonucleotide, a mixture of the sense and the antisense oligonucleotides, in each case had no effect. The effects of SP were blocked by NK1 receptor antagonists and were not mimicked by NMDA. The mechanism underlying these effects is not clear. It may be due to partial degradation of the internalised receptors, which cannot be replaced by newly synthesised receptors because of the action of the NK1 antisense oligonucleotide.

Topics: Animals; Down-Regulation; Formaldehyde; Indoles; Injections, Spinal; Isoindoles; Male; N-Methylaspartate; Oligonucleotides, Antisense; Pain; Pain Threshold; Piperidines; Quinuclidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-1; Spinal Cord; Substance P

These experiments tested the hypothesis that substance P neurotransmission at tachykinin NK1 receptors in the locus coeruleus is involved in stress-induced activation of the locus coeruleus, using c-fos as an index of activation. Selective tachykinin NK1 receptor antagonists administered systemically did not result in substantial locus coeruleus c-fos expression. Restraint stress resulted in a large number of locus coeruleus c-fos expressing cells. Administration of two selective tachykinin NK1 receptor antagonists prior to restraint resulted in an increase in the number of locus coeruleus c-fos expressing cells, compared to restraint alone. These results suggest that the enhanced c-fos expression observed in response to tachykinin NK1 receptor antagonists combined with stress, could be due to the blockade of tachykinin NK1 receptor-mediated activity at sites other than the locus coeruleus, resulting in an overall activation of the locus coeruleus.

Topics: Acetamides; Analgesics; Animals; Gene Expression Regulation; Genes, fos; Indoles; Isoindoles; Locus Coeruleus; Neurokinin-1 Receptor Antagonists; Piperidines; Quinuclidines; Rats; Restraint, Physical; Stereoisomerism; Stress, Physiological; Substance P; Synaptic Transmission

In the present study, tachykinin receptors (designated NK 1, NK2 and NK3) involved in regulation of ion transport in porcine jejunum were characterised. Stripped tissue preparations were mounted in Ussing chambers and short-circuited. Substance P produced a concentration dependent increase in short-circuit current, the relationship showing a double sigmoidal form. The non-peptide NK1 receptor antagonist, CP 99,994 ((2S,3S)-3-(2-methoxybenzyl)amino-2-phenylpiperidine), caused a dextral shift of the first sigmoidal response, indicating the involvement of an NK1 receptor. This was further supported by a concentration-dependent response of the NK1 receptor agonist [Sar9Met(O2)11]substance P with an EC50 value of 235.0+/-53.9 nM. Increasing concentrations of CP 99,994 (0.1, 0.3 and 1 microM) produced a parallel dextral shift of the [Sar9Met(O2)11]substance P curve with a slope of the Schild regression significantly different from unity (1.59). The neurokinin A concentration-response curve, with an EC50 value of 68.87+/-16.23 nM, was not significantly changed by the non-peptide NK2 receptor antagonist SR 48,968 ((S)-N-methyl-N-(4-(4-acetylamino-4-phenylpiperidino)-2-(3,4-dichlorophe nyl)butyl)bezamide). In additional studies, the peptide NK2 receptor antagonists, GR 94,800 (PhCO-Ala-Ala-DTrp-Phe-DPro-Pro-NleNH2) and PD 147,714 ((2,3-diOMeZ)-(S)Trp(S)alphaMePheGlyNH2), did not change the response to neurokinin A. However, CP 99,994 totally inhibited neurokinin A responses at 0.5 microM and above. The NK2 receptor agonist, [beta-Ala8]neurokinin A-(4-10), caused only an increase in short-circuit current in microM concentrations, whereas the NK3 receptor agonist, senktide, did not elicit a response. These results indicate, that substance P and neurokinin A mediate ion transport in porcine jejunum through NK1 receptors. However, tachykinins seem to activate another receptor. Two active conformers of the NK1 receptor might be present.

Topics: Animals; Binding, Competitive; Electric Stimulation; Evoked Potentials; Female; In Vitro Techniques; Indoles; Ion Transport; Isoindoles; Jejunum; Male; Membrane Potentials; Neurokinin A; Neurokinin-1 Receptor Antagonists; Piperidines; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Receptors, Tachykinin; Substance P; Swine

The intrathecal effect of 0.1 to 10 microg of RP-67,580 (3aR,7aR)-7,7-diphenyl-2[1-imino-2(2-methoxyphenyl)-ethyl]++ +perhydroisoindol-4-one hydrochloride, CP-96,345 (2S,3S)-cis-(2(diphenylmethyl)-N-[(2-methoxyphenyl) methyl]-1-azabicyclo[2.2.2]octan-3-amine), SR-140,333 (S)-(1-¿2-[3-(3,4-dichlorophenyl)- 1-(3-isopropoxyphenylacetyl)piperidin-3-yl]ethyl¿-4-phenyl-1 -azonia-bicyclo[2.2.2.]-octane,chloride), all neurokinin (NK)1-receptor antagonists, SR-48,968 (S)-N-methyl-N[4-(4-acetylamino-4-[phenylpiperidino)-2-(3,4-dichlorophen yl)-butyl]benzamide, a tachykinin NK2 receptor antagonist and SR-142,801 (S)-(N)-(1-(3-(1-benzoyl-3-(3,4-dichlorophenyl) piperidin-3-yl)propyl)-4-phenylpiperidin-4-yl)-N-methyl acetamide, a tachykinin NK3 receptor antagonist, and of their respective inactive enantiomers on thresholds of vocalization due to a mechanical stimulus in mononeuropathic (sciatic nerve ligature) and diabetic rats, was examined. The tachykinin NK1 and the NK2 receptor antagonists were antinociceptive in both models, with a higher effect of the former in diabetic rats. The tachykinin NK3 receptor antagonist was weakly effective in diabetic rats only. This indicates a differential involvement of the tachykinins according to the model of neuropathic pain, suggesting a potential role for tachykinin receptor antagonists in the treatment of neuropathic pain.

Topics: Analgesics; Animals; Benzamides; Biphenyl Compounds; Denervation; Diabetes Mellitus, Experimental; Indoles; Isoindoles; Male; Neurokinin-1 Receptor Antagonists; Pain; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Receptors, Tachykinin; Sciatic Nerve

The neurokinins, substance P (SP) and neurokinin A (NKA) represent natural, nonspecific ligands of NK1 and NK2 receptors. In our study in conscious rats, we tested the hypothesis that neurokinins, especially SP, are used by neuronal circuits to generate cardiovascular and behavioral responses to stress by using the selective, high-affinity, nonpeptide antagonists of NK1 and NK2 receptors, CP-96, 345, RP 67580 and SR 48968, respectively, Formalin injected s.c. through a chronically implanted catheter in the region of the lower leg was used as a stress stimulus. The antagonists and their inactive enantiomers, RP 68651 and SR 48965, as a control for nonspecific activity, were injected intracerebroventricularly (i.c.v.) 10 min before the s.c. injection of formalin. Formalin (2.5%, 50 microliters, s.c.) induced a marked increase in mean arterial pressure (MAP) and heart rate (HR) as well as hind limb grooming/biting (HG) as the dominant behavioral manifestation. Pretreatment with the NK1 receptor antagonist, CP-96,345 (5 nmol, i.c.v.), significantly attenuated only the HR (-54%; P < .01) but not the MAP response to formalin. The NK1 receptor antagonist, RP 67580, injected i.c.v. at doses of 100, 500 and 2500 pmol significantly reduced both, the MAP and HR responses to formalin by maximally 63% (P < .01) and 52% (P < .01), respectively. In a separate set of experiments, we compared the effect of the individual and simultaneous blockade of central NK1 and NK2 receptors on the cardiovascular and behavioral responses to formalin stress. Pretreatment with RP 67580 (100 pmol, i.c.v.) attenuated the MAP (-30%; P < .05), HR (-40%; P < .01) and HG (P < .05) responses to formalin. The NK2 receptor antagonist, SR 48968 (650 pmol, i.c.v.), affected neither the cardiovascular nor the behavioral responses. i.c.v. pretreatment with both tachykinin receptor antagonists (RP 67580: 100 pmol; SR 48968: 650 pmol) reduced the MAP, HR and HG responses to formalin to the same extent as RP 67580 alone. Pretreatment with the inactive enantiomers, RP 68651 (100 pmol, i.c.v.) and SR 48965 (650 pmol, i.c.v.) did not alter the cardiovascular and behavioral responses to formalin. Our results demonstrate that centrally administered NK1 receptor antagonists inhibit the cardiovascular and behavioral reactions in response to a noxious stimulus. They provide first pharmacological evidence that endogenous SP acts as mediator of stress responses in the brain.

Topics: Animals; Behavior, Animal; Benzamides; Biphenyl Compounds; Blood Pressure; Brain; Heart Rate; Indoles; Isoindoles; Male; Neurokinin-1 Receptor Antagonists; Periaqueductal Gray; Piperidines; Rats; Rats, Wistar; Receptors, Neurokinin-2; Stress, Physiological

This study describes a novel intravital microscope technique for direct measurement of dural blood vessel diameter through a closed cranial window in anaesthetized rats. This technique avoids removal of the skull, which can lead to problems of altered vessel reactivity and brain swelling that are encountered with open cranial window techniques. Substance P and calcitonin gene-related (CGRP) evoked increases in dural vessel diameter, which were abolished by the NK1 receptor antagonist, RP67580 and the CGRP receptor antagonist, human-alpha CGRP(8-37) respectively. Neurokinin A produced increases in dural vessel diameter which were unaffected by the NK2 receptor antagonist SR 48968 but were blocked by RP67580, suggesting that neurokinin A can act through NK1 receptors to produce dural vasodilation in rats. The NK3 receptor agonist, senktide, had no effects on dural vessel diameter. All drugs were administered intravenously. In humans, vasodilation within the meningeal vasculature has been implicated in the pathogenesis of migraine, the present experiments indicate that substance P or neurokinin A (both acting through NK1 receptors) or CGRP may be responsible.

Topics: Anesthetics; Animals; Benzamides; Blood Pressure; Calcitonin Gene-Related Peptide; Dura Mater; Indoles; Isoindoles; Male; Microscopy, Video; Neurokinin A; Neurokinin-1 Receptor Antagonists; Peptide Fragments; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-2; Receptors, Tachykinin; Substance P; Vasodilator Agents

In anesthetized rats, renal pelvic administration of bradykinin results in a prostaglandin (PG)-dependent increase in afferent renal nerve activity (ARNA). We now measured renal pelvic release of PGE and substance P during renal pelvic administration of bradykinin. Bradykinin increased ARNA and renal pelvic release of PGE by 497 +/- 252 pg/min and substance P. by 10.7 +/- 7.2 pg/min. Renal pelvic perfusion with indomethacin abolished the bradykinin-mediated increase in ARNA and reduced renal pelvic release of PGE and substance P by 76 +/- 11 and 72 +/- 8%, respectively. To examine whether the increased substance P release contributed to bradykinin-mediated activation of renal sensory receptors, renal pelvis was perfused with the substance P-receptor antagonists CP-96,345, CP-99,994, or RP-67580. The ARNA response to bradykinin was reduced 73 +/- 11, 55 +/- 12, and 64 +/- 10% by CP-96,345, CP-99,994, and RP-67580, respectively. The inactive enantiomers CP-96,344 and RP-68651 had no effect. These data suggest that bradykinin increases renal pelvic release of PGE, which facilitates the release of substance P, which in turn stimulates substance P receptors. Thus the ARNA response to bradykinin is largely mediated by activation of substance P receptors.

Topics: Animals; Biphenyl Compounds; Bradykinin; Indoles; Indomethacin; Isoindoles; Kidney; Male; Neurokinin-1 Receptor Antagonists; Neurons, Afferent; Piperidines; Prostaglandins; Prostaglandins E; Rats; Rats, Sprague-Dawley; Substance P

We investigated the electrocortical (E.Co.G) correlates of visceral (topical capsaicin application or overdistension of the urinary bladder) and somatic (perineal pinching) painful stimulation in urethane-anesthetized rats and their modulation by intrathecal application of selective tachykinins receptors (NK 1 and NK 2) antagonists. Vesical overdistension or topical capsaicin on the bladder serosal surface produced an immediate and lasting E.Co.G. desynchronization resembling a cortical arousal. A second application of capsaicin was ineffective. Bladder contraction induced by topical acetylcholine did not alter E.Co.G. A desynchronized E.Co.G. was also induced by pinching of the perineal area of the rat. Intrathecal administration of lidocaine at lumbosacral level abolished the E.Co.G. desynchronization induced by both visceral and somatic noxious stimulation. On the other hand capsaicin-induced or over-distension (but not pinching-induced) E.Co.G. desynchronization disappeared in animals systemically pretreated with capsaicin or after intrathecal administration of NK 1 tachykinin receptor antagonists such as the peptide GR 82334 or the nonpeptide RP 67580, whereas the inactive enantiomer RP 68651 or the nonpeptide NK 2 antagonists SR 48968 were ineffective. In conclusion, the experimental model described herein, allowing a quantitative analysis of the E.Co.G. correlates of visceral and somatic noxious stimulation in urethane-anesthetized rats, provides evidence for a specific neural pathway carrying bladder-arising visceral (both mechanical and chemical) nociception that uses pelvic capsaicin-sensitive afferents projecting to NK 1 (but not NK 2) bearing spinal neurons and that ultimately leads to activation of cortical areas.

Topics: Acetylcholine; Administration, Topical; Anesthesia; Animals; Benzamides; Capsaicin; Cortical Synchronization; Electric Stimulation; Indoles; Injections, Spinal; Isoindoles; Lidocaine; Male; Perineum; Physalaemin; Piperidines; Rats; Rats, Wistar; Receptors, Tachykinin; Sensitivity and Specificity; Urethane; Urinary Bladder

Vascular NK-1 and NK-2 tachykinin receptors in the rat and the guinea pig were characterized pharmacologically by using available agonists and antagonists exhibiting varying degrees of selectivity for these receptors. Because the anesthetized guinea pig has unusually low blood pressure, these animals were pithed and vagotomized and infused, throughout the experimental procedure, with norepinephrine (6 micrograms/kg/min). This treatment raised their blood pressure to a level appropriate for the determination of dose-hypotensive response curves. The NK-1 receptor agonists substance P (SP) and septide (0.004 to 1 microgram/kg iv) decreased carotid artery blood pressure in a dose-dependent manner in both species, but they were more potent (13- and 33-fold, respectively) in guinea pigs than in rats. The NK-2 receptor agonist [beta Ala8]-NKA(4-10) (0.06 to 1 microgram/kg) also dose-dependently lowered blood pressure in the pithed guinea pig with noradrenaline-supported blood pressure, although it failed to do so in the same rat preparation. RP 67580, a selective NK-1 antagonist, antagonized the SP- or septide-induced hypotensive response in rats, but not in guinea pigs. Conversely, RPR 100893, a novel NK-1 receptor antagonist chemically related to RP 67580, dose-dependently inhibited hypotension induced by SP, and even more, that induced by septide only in guinea pigs. In the latter species, neither RP 67580 nor RPR 100893 affected decreases in blood pressure induced by [beta Ala8]-NKA(4-10). These decreases were, however, inhibited by the NK-2 receptor antagonist SR 48968. The selectivity of this compound for the latter receptor was confirmed by its failure to affect SP- or septide-induced hypotension in either guinea pigs or rats. These results confirm that the hypotensive responses to SP and septide are mediated by NK-1 receptors in the two species studied. However, functional NK-2 receptors appear to be present in the vascular bed of the guinea pig but not that of the rat, since in the former species the hypotensive responses induced [beta Ala8]-NKA(4-10) were inhibited by SR 48968 but not by the NK-1 receptor antagonists studied. This conclusion is, to our knowledge, drawn here for the first time from clear-cut pharmacological results.

Topics: Animals; Benzamides; Blood Pressure; Guinea Pigs; Hypotension; Indoles; Isoindoles; Male; Neurokinin A; Neurokinin-1 Receptor Antagonists; Peptide Fragments; Piperidines; Pyrrolidonecarboxylic Acid; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Substance P

The selective NK2 agonist [Lys5-MeLeu9,Nle10]NKA(4-10) markedly stimulated [3H]inositol monophosphate (PI1) formation in prisms from the rat urinary bladder. This response was blocked by the NK2 antagonist SR 48968. Senktide (NK3 agonist) was inactive. Septide, a short SP analogue, and the NK1 agonists [Pro9]SP and [Sar9,Met(O2)11]SP also stimulated [3H]IP1 formation and several NK1 tachykinin antagonists (RP 67580, CP 96345, GR 82334, and [D-Pro9,t beta-BPr10,Trp11]SP) were more potent in blocking the septide than the [Pro9]SP response. GR 82334 was the most discriminative. SR 48968 (10(-6) M shifted the [Pro9]SP dose-response curve but did not modify the septide dose-response curve. Septide had a low affinity for [3H][Pro9]SP binding sites, suggesting further that septide and NK1 agonists act on different receptors. Finally, both [Pro9]SP and [Sar9,Met(O2)11]SP blocked the septide-evoked response, acting as partial agonists at the septide-sensitive tachykinin receptors.

Topics: Amino Acid Sequence; Animals; Benzamides; Hydrolysis; Indoles; Isoindoles; Male; Molecular Sequence Data; Muscle Contraction; Muscle, Smooth; Neurokinin A; Peptide Fragments; Phosphatidylinositols; Piperidines; Pyrrolidonecarboxylic Acid; Rats; Rats, Sprague-Dawley; Receptors, Tachykinin; Substance P; Urinary Bladder

Most nonpeptide neurokinin (NK)1 antagonists display a marked difference in affinity for rat versus human NK1 receptors. The molecular basis for the species selectivity of RP67580 and CP96,345 has been previously addressed [J. Biol. Chem. 267:25668-25671 (1992); J. Biol. Chem. 268:2319-2323 (1993)]. We are extending these previous results to additional NK1 antagonists, which are members of different chemical families. Included is a new perhydroisoindolol, RPR100893, which unlike its parent compound (RP67580) is human receptor selective. Chimeric rat/human NK1 receptors, as well as rat and human mutant NK1 receptors, were constructed and expressed in COS-1 cells, and affinities for substance P and the various antagonists were determined in binding studies. With human receptor-selective antagonists, the rat R290(S-->I) mutation was the most effective in increasing antagonist affinity (from 7- to 23-fold). Combination with the R116(L-->V) mutation led to an additional increase in affinity for trans-4-hydroxy-1-(1H-indol-3-ylcarbonyl)-L-prolyl-N- methyl-N-(phenylmethyl)-L-tyrosineamide (a derivative of FK888) and to nearly full human receptor affinity for RPR100893 and (+/-)-CP99,994. Based on the gains in affinities, these results confirm and extend the role of residues 116 and 290 of the NK1 receptor in the species selectivity of these three new human receptor-selective NK1 antagonists. In comparison, the affinity of RP67580, the least selective molecule, was most affected by changes at position 116, and combination with mutations at either position 97 (V-->E) or position 290 led to the human receptor phenotype. For the heterosteroid KAN610857, modifications of the rat receptor at positions 97 and 290, and to a lesser degree position 116, were the most effective in reducing affinity. Two double-mutants [R(97,290) and R(116,290)], although different from those identified for RP67580, also displayed human receptor-like affinity. Therefore, the molecular determinants of the species selectivity appear to be different, in part, between rat and human receptor-selective compounds, even between closely related chemical families.

Topics: Androstanes; Animals; Benzimidazoles; Dipeptides; Humans; Indoles; Isoindoles; Neurokinin-1 Receptor Antagonists; Piperidines; Rats; Receptors, Neurokinin-1; Species Specificity; Substance P

1. Oedema formation induced by intradermal capsaicin has been studied in rabbit skin. The effect of the anti-inflammatory steroid dexamethasone and also of a range of known inhibitors of oedema formation have been investigated in order to elucidate mechanisms involved in capsaicin-induced oedema formation. 2. Oedema formation, in response to intradermally-injected test agents, was measured by the local extravascular accumulation of intravenously injected 125I-labelled albumin. In separate experiments skin blood flow was assessed by the clearance of intradermally-injected 133xenon. 3. Oedema formation induced by intradermal histamine (3 nmol) and bradykinin (1 nmol), when in the presence of vasodilator doses of calcitonin gene-related peptide (CGRP) (3 pmol) or prostaglandin E1, (PGE1) (10 pmol), was significantly inhibited (P < 0.01) in rabbits pretreated with intravenous dexamethasone (3 mg kg-1, -4 h). In contrast dexamethasone had no effect on capsaicin (3 mumol)-induced oedema formation or, on capsaicin (30-100 nmol)-induced blood flow. 4. Oedema formation observed in response to intradermal capsaicin (3 mumol) was significantly inhibited (P < 0.01) when the selective capsaicin antagonist, ruthenium red (3 nmol) was co-injected. This suggests that the mechanism of capsaicin-induced oedema involves activation of sensory nerves. However, oedema was not inhibited when capsaicin was co-injected with the neurokinin NK1 receptor antagonist, RP67580 (10 nmol), the NK2 antagonist SR48960 (10 nmol) or the CGRP antagonist CGRP8-37 (300 pmol). 5. Oedema formation induced by capsaicin was not inhibited when co-injected with the histamine HI receptor antagonist, mepyramine (3 nmol), the PAF antagonist, WEB 2086 (100 nmol), the bradykinin B2 receptor antagonist, Hoel4O (1 nmol), or the cyclo-oxygenase inhibitor, indomethacin (10 nmol),suggesting that these mediators do not play a major role in the capsaicin-induced response.6. Histological analysis of capsaicin-treated skin sites revealed undamaged, intact microvessels and lack of haemorrhage. Further, co-injection of capsaicin with the hydrogen peroxide remover, catalase(2,200 u), had no effect on oedema formation. This suggests that capsaicin does not induce oedema formation secondary to free radical-induced damage.7. These results indicate that capsaicin-induced oedema in rabbit skin involves activation of sensory nerves. However, the oedema is not inhibited by pretreatment with the anti-inflammatory steroid,dex

Topics: Alprostadil; Animals; Anti-Inflammatory Agents, Non-Steroidal; Benzamides; Bradykinin; Calcitonin Gene-Related Peptide; Capillary Permeability; Capsaicin; Catalase; Dexamethasone; Drug Interactions; Edema; Histamine; Indoles; Indomethacin; Injections, Intradermal; Injections, Intravenous; Isoindoles; Male; Piperidines; Rabbits; Regional Blood Flow; Ruthenium Red; Skin; Substance P; Vasodilator Agents

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.

Topics: Adrenergic beta-Antagonists; Animals; Bradykinin; Capsaicin; Dose-Response Relationship, Drug; Indoles; Indomethacin; Injections, Spinal; Isoindoles; Male; Muscle Contraction; Muscle, Smooth; Piperidines; Quinuclidines; Rats; Rats, Wistar; Reflex; Substance P; Urinary Bladder

When instilled intravesically in normal, unanesthetized rats, neurokinin A (NKA), but not substance P (SP) and neurokinin B (NKB), stimulated micturition. The effect of NKA was inhibited by the NK2 receptor selective antagonists SR 48,968 and MEN 10,627, but not by the NK1 receptor selective antagonist RP 67,580, suggesting that the effect was mediated by stimulation of NK2 receptors. Given intra-arterially near the bladder, NKA produced an increase in basal intravesical pressure before initiating micturition, indicating that the tachykinin had a direct contractant effect on the detrusor smooth muscle. Such a contractile effect was not observed when NKA was given intravesically. The effect of intra-arterial NKA could not be blocked by the NK1 receptor selective antagonist SR 140,333 or the NK2 receptor selective antagonist SR 48,968, but by their combination. Also intra-arterial NKB stimulated micturition, but was less potent than NKA. Intra-arterial SP had only weak stimulating effects. The results suggest that intravesically administered NKA can initiate micturition in the normal rat by stimulation of superficially located NK2 receptors in the urothelium. Intra-arterially administered NKA caused bladder hyperactivity via stimulation of both NK1 and NK2 receptors.

Topics: Administration, Intravesical; Animals; Benzamides; Female; Indoles; Injections, Intra-Arterial; Isoindoles; Muscle Contraction; Muscle, Smooth; Neurokinin A; Neurokinin B; Neurokinin-1 Receptor Antagonists; Peptides, Cyclic; Piperidines; Quinuclidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-2; Substance P; Urinary Bladder; Urination

In normal conscious rats investigated by continuous cystometry, intravesically instilled prostaglandin (PG) E2 facilitated micturition and increased basal intravesical pressure. The effect was attenuated by both the NK1 receptor selective antagonist RP 67,580 and the NK2 receptor selective antagonist SR 48,968, given intra-arterially, suggesting that it was mediated by stimulation of both NK1 and NK2 receptors. Intra-arterially given PGE2 produced a distinct increase in bladder pressure before initiating a micturition reflex, indicating that the PG had a direct contractant effect on the detrusor smooth muscle. The effect of intra-arterial PGE2 could not be blocked by intra-arterial RP 67,580 or SR 48,968, which opens the possibility that the micturition reflex elicited by intra-arterial PGE2 was mediated by pathways other than the reflex initiated when the PG was given intravesically. The present results thus suggest that intra-arterial PGE2, given near the bladder, may initiate micturition in the normal rat chiefly by directly contracting the smooth muscle of the detrusor. However, when given intravesically, PGE2 may stimulate micturition by releasing tachykinins from nerves in and/or immediately below the urothelium. These tachykinins, in turn, initiate a micturition reflex by stimulating NK1 and NK2 receptors. Prostanoids may, via release of tachykinins, contribute to both urge and bladder hyperactivity seen in inflammatory conditions of the lower urinary tract.

Topics: Administration, Intravesical; Animals; Benzamides; Consciousness; Dinoprostone; Female; Indoles; Injections, Intra-Arterial; Isoindoles; Muscle, Smooth; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, Tachykinin; Tachykinins; Urinary Bladder

Tachykinins released from sensory airway nerves have been shown to increase vascular permeability and plasma-protein extravasation (PPE) in rodent airways. We previously demonstrated that in Fisher (F344) rats, tachykinins cause bronchoconstriction mainly by indirect mechanisms involving the activation of NK1 receptor and mast cells, whereas in the less responsive BDE rats tachykinins have a direct NK2 receptor-mediated effect on bronchial smooth muscle. Using Evans blue dye as an intravascular marker, we demonstrated that F344 rats are hyperresponsive for the PPE induced by substance P (SP) and capsaicin. The NK1 receptor antagonist RP 67,580 reduced the neurogenic PPE in both strains, whereas the NK2 receptor antagonist SR 48,968 had no effect, indicating that only NK1 receptors are involved in the PPE. Pretreatment with the 5-HT antagonist methysergide decreased the neurogenic PPE in F344 rats but not in BDE rats. In F344 rats depleted of mast-cell mediators with compound 48/80, the SP-induced PPE was significantly reduced. Pretreatment with the H1 antagonist mepyramine and the H2 antagonist cimetidine caused a similar reduction in SP-induced PPE in main bronchi of both strains. Pretreatment with atropine, indomethacin, or the leukotriene antagonist ICI 198,615 did not affect the SP-induced PPE. In conclusion, neurogenic PPE in rat airways involves the activation of NK1 receptors. In F344 but not in BDE rats, an additional indirect mechanism involving 5-HT release and mast-cell activation participates in the neurogenic PPE.

Topics: Animals; Benzamides; Blood Pressure; Bronchi; Capillary Permeability; Capsaicin; Cimetidine; Coloring Agents; Dose-Response Relationship, Drug; Evans Blue; Histamine Antagonists; Indoles; Inflammation; Isoindoles; Methysergide; Neurokinin-1 Receptor Antagonists; Piperidines; Pyrilamine; Rats; Rats, Inbred F344; Rats, Inbred Strains; Receptors, Neurokinin-1; Serotonin; Serotonin Antagonists; Substance P; Trachea

We investigated the possibility that substance P would mediate defecation in rats subjected to restraint-stress. The increases in fecal pellet output caused by restraint-stress were inhibited by a neurokinin (NK)1 receptor antagonist, RP67580 with an ED50 (95% confidence limits) value of 0.59 (0.54-0.65) mg/kg i.p. RP68651, the enantiomer of RP67580 devoid of affinity for NK1 receptors, had little effect on it. In contrast, (+/-)SR48968, an NK2 receptor antagonist, was without effect. Furthermore, capsaicin treatment (125 mg/kg i.p.) was inactive in this model. These results suggest that the activation of NK1 receptors and substance P released from intrinsic neurons of the colon would be involved in stress-induced defecation in rats.

Topics: Analgesics; Animals; Benzamides; Capsaicin; Defecation; Dose-Response Relationship, Drug; Indoles; Isoindoles; Male; Neurokinin-1 Receptor Antagonists; Piperidines; Rats; Rats, Wistar; Receptors, Neurokinin-2; Restraint, Physical; Stereoisomerism; Stress, Psychological; Substance P

Effects of the NK1 receptor antagonist CP-99,994 on nicotine-induced emesis were examined in Suncus murinus. CP-99,994 (3 and 10 mg/kg i.p.) attenuated emesis to (-)nicotine (4 mg/kg s.c.). CP-100,263 (3 and 10 mg/kg i.p.), the enantiomer of CP-99,994 with 1000 fold lower affinity for the NK1 receptor was without effect and RP67580 reduced emesis only at a dose of 30 mg/kg i.p. Responses to NK1 antagonists were ranked according to their affinities for the Suncus murinus NK1 receptor.

Topics: Animals; Antiemetics; Dose-Response Relationship, Drug; Indoles; Isoindoles; Male; Morphine; Neurokinin A; Nicotine; Piperidines; Receptors, Neurokinin-1; Shrews; Stereoisomerism; Substance P; Vomiting

The in vivo pharmacological profiles of the selective tachykinin NK1 receptor agonists, [Sar9,Met(O2)11]substance P and GR 73632, were examined in gerbils. Both agonists induced a pronounced chromodacryorrhea following intravenous injection which was stereoselectively antagonised by the tachykinin NK1 receptor antagonist, CP-99,994, but not by its inactive enantiomer, CP-100,263, or the rat-selective tachykinin NK1 receptor antagonist, RP 67,580. In contrast, chromodacryorrhea was not observed following intravenous injection of the selective tachykinin NK2 receptor agonist, [beta-Ala8]neurokinin A-(4-10), or the selective tachykinin NK3 receptor agonist, senktide. These results suggest that [Sar9,Met(O2)11]substance P-induced chromodacryorrhea results from activation of peripheral tachykinin NK1 receptors. Repetitive hind paw tapping was also observed in gerbils but only following intracerebroventricular injection of [Sar9,Met(O2)11]substance P or GR 73632. Furthermore, GR 73632-induced hind paw tapping was significantly attenuated by co-administration of the peptide tachykinin NK1 receptor antagonist, GR 82334, or intravenous injection of CP-99,994. Thus, in contrast to chromodacryorrhea, repetitive hind paw tapping may result from activation of central tachykinin NK1 receptors.

Topics: Animals; Behavior, Animal; Dose-Response Relationship, Drug; Drug Synergism; Gerbillinae; Harderian Gland; Indoles; Injections, Intravenous; Injections, Intraventricular; Isoindoles; Male; Neurokinin A; Peptide Fragments; Piperidines; Receptors, Neurokinin-1; Substance P

Capsaicin, instilled intravesically in normal, unanesthetized rats induced a concentration-dependent bladder hyperactivity, which could be abolished by hexamethonium, given intra-arterially near the bladder, or by morphine administered intrathecally. The effect was reversible and could be repeated. The NK-2 receptor selective antagonist SR 48,968 and the nonselective NK receptor antagonist spantide, given intra-arterially near the bladder, which by themselves, in the concentrations used, did not affect cystometric parameters, both counteracted the capsaicin-induced hyperactivity, whereas the NK-1 receptor selective antagonist RP 67,580 failed to do so. Blockade of tachykinin receptors in the urinary bladder does not seem to produce changes of the micturition reflex associated with bladder filling in the conscious rat. However, tachykinins released from capsaicin-sensitive nerves by various stimuli may, through stimulation of NK-2 receptors, lower the threshold for initiation of the micturition reflex. In the rat, intravesical capsaicin may be a suitable model for studies of afferent activity caused by stimuli releasing peptides from sensory nerves in the bladder, thereby provoking bladder hyperactivity.

Topics: Administration, Intravesical; Animals; Benzamides; Capsaicin; Consciousness; Dose-Response Relationship, Drug; Female; Hexamethonium; Hexamethonium Compounds; Indoles; Isoindoles; Morphine; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, Tachykinin; Substance P; Urinary Bladder

Tachykinins participate in somatic pain and intestinal motility control. The role of tachykinin receptors in both colonic motor disturbances and visceral pain (abdominal contractions as an index of visceral pain) induced by rectal distension were investigated.. Rats were surgically prepared with electrodes implanted on the proximal colon and the abdominal striated muscles. Catheters were implanted in lateral ventricles of the brain. Rectal distension was performed by inflation of a balloon (0.1-1.6 mL) rectally inserted. CP-96,345 and RP-67,580 (neurokinin [NK] 1 antagonists) and SR-48,968 (NK2 antagonist) were injected intraperitoneally (IP) or intracerebroventricularly (ICV) 20 minutes before distension. GR-73,632 and GR-64,639 (NK1, NK2 agonists) were infused intravenously at 0.15 micrograms.kg-1.min-1.. Rectal distension evoked a significant inhibition of colonic motility and an increase in abdominal contractions. CP-96,345 injected ICV (0.2-0.8 mg/kg) or IP (5-10 mg/kg) and RP-67,580 (0.2 mg/kg IP) eliminated distension-induced colonic inhibition but did not affect abdominal response. SR-48,968 did not affect colonic response but significantly reduced visceral pain (0.4, 0.8 mg/kg ICV: 5-10 mg/kg IP). GR-73,632 enhanced the rectal distension-induced colonic inhibition, whereas GR-64,349 induced a greater abdominal response.. NK1 receptors mediate the rectocolonic inhibitory reflex, whereas NK2 receptors participate in visceral pain; both responses involve central structures.

Topics: Abdomen; Animals; Benzamides; Biphenyl Compounds; Colon; Colonic Diseases, Functional; Gastrointestinal Motility; Hypnotics and Sedatives; Indoles; Isoindoles; Male; Neurokinin A; Peptide Fragments; Piperidines; Rats; Rats, Wistar; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Receptors, Tachykinin; Rectum; Substance P; Tachykinins

1. The effects of the NK1-receptor antagonists, (+/-)-CP 96,345 and CP 99,994, on NK1-agonist evoked contractions were compared in isolated rings of guinea-pig tracheal smooth muscle. 2. (+/-)-CP 96,345 and CP 99,994 were similarly effective in antagonizing responses evoked by septide, whereas CP 99,994 was more effective than (+/-)-CP 96,345 in inhibiting responses evoked by [Sar9Met11(O2)] substance P. 3. These results suggest that responses to septide and [Sar9Met11(O2)] substance P may be operated via different populations of NK1-receptors.

Topics: Animals; Biphenyl Compounds; Guinea Pigs; In Vitro Techniques; Indoles; Isoindoles; Male; Muscle Contraction; Muscle, Smooth; Neurokinin A; Neurokinin-1 Receptor Antagonists; Peptide Fragments; Piperidines; Pyrrolidonecarboxylic Acid; Substance P; Trachea

1. The effects of intracerebroventricular (i.c.v.) injection of selective and potent NK1 (RP 67580), NK2 (SR 48968) and NK3 (R 486, [Trp7, beta-Ala8]NKA(4-10)) receptor antagonists were assessed on the cardiovascular and behavioural responses elicited by the i.c.v. injection of substance P (SP), neurokinin A (NKA) or [MePhe7]neurokinin B ([MePhe7]NKB) in the conscious freely moving rat. 2. SP, NKA and [MePhe7]NKB (5-650 pmol) evoked dose-dependent increases in mean arterial blood pressure (MAP) and heart rate (HR) with the rank order of potency SP > NKA > [MePhe7]NKB. The cardiovascular responses were accompanied by excessive face washing, grooming and wet dog shakes. 3. The cardiovascular effects and face washing behaviour induced by SP (25 pmol) were significantly reduced by the pre-injection (i.c.v., 5 min earlier) of RP 67580 (6.5 nmol). However, this antagonist failed to affect the central effects of 25 pmol NKA or [MePhe7]NKB. 4. The cardiovascular and behavioural responses (except for wet dog shakes) elicited by NKA (25 pmol) were significantly reduced by 6.5 nmol SR 48968. However, the latter antagonist had no effect on the SP or [MePhe7]NKB-mediated responses. 5. Both cardiovascular and behavioural effects produced by either SP or NKA (25 pmol) were completely abolished when rats were pretreated with a combination of RP 67580 (6.5 nmol) and SR 48968 (6.5 nmol), yet this combination of antagonists failed to modify the central effects of [MePhe7]NKB. 6. R 486 (6.5 nmol) inhibited the cardiovascular effects as well as wet dog shakes produced by [MePhe7]NKB, but it was inactive against the responses induced by either SP or NKA. 7. None of the tachykinin receptor antagonists or agonists caused motor impairment or respiratory distress. All antagonists blocked in a reversible manner and were devoid of intrinsic activity except R486 (6.5 nmol) which produced a transient increase of MAP and HR.8. These results suggest that the central effects of SP, NKA and [MePhe7]NKB are primarily mediated by central NK1, NK2 and NK3 receptors, respectively. However, a minor activation of NK2 receptors bySP and NK1 receptors by NKA was seen during blockade of both receptors. This study therefore supports the existence of functional NK1, NK2 and NK3 receptors in the adult rat brain.

Topics: Animals; Behavior, Animal; Benzamides; Blood Pressure; Dose-Response Relationship, Drug; Heart Rate; Hemodynamics; Indoles; Injections, Intraventricular; Isoindoles; Male; Neurokinin A; Neurokinin B; Neurokinin-1 Receptor Antagonists; Oligopeptides; Piperidines; Rats; Rats, Wistar; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Receptors, Tachykinin; Substance P; Tachykinins

1. The effects of the non-peptide tachykinin NK1 receptor antagonists, RP 67580, SR 140333, CP-96,345 and CP-99,994 have been investigated on electrically-evoked release of substance P-like immunoreactivity (SP-LI) from rat spinal cord slices. 2. RP 67580 (10 nM) and SR 140333 (1 nM), perfused 5 min prior to and during 8 min stimulation of the dorsal roots (20 V, 0.5 ms, 1 Hz), significantly enhanced SP-LI release by 213 +/- 43 (n = 8) and 203 +/- 31 (n = 5) % of control evoked release (187 +/- 16% of basal outflow, n = 22) respectively. Neither compound modified basal outflow of SP-LI (15.3 +/- 2.5 fmol/8 ml, n = 10). 3. RP 67580 (10 nM) did not modify electrically-evoked release of calcitonin gene-related peptide-LI from rat spinal cord slices. 4. CP-96,345 (10 nM) and CP-99,994 (1 and 10 nM) did not alter electrically-evoked SP-LI release; however, they both inhibited release at 1 microM. Inhibition was also induced by 1 microM RP 67580 but not 1 microM SR 140333. 5. The effect of the NK1 receptor agonists, [Sar9 Met (O2)11]SP and [Sar9]SP, could not be tested on SP-LI release due to interference with the substance P radioimmunoassay (RIA). The other NK1 receptor agonists used, GR 73632, [Pro9]SP and septide, which did not interfere with the RIA, increased SP-LI basal outflow by 1807 +/- 713% (n = 3), 1259 +/- 160% (n = 3) and 620 +/- 69% (n = 3) at 10 nM, 1 nM and 1 microM, respectively. At the same concentrations, the three agonists also enhanced electrically evoked SP-LI release by 204 +/- 38% (n = 6), 753 +/- 40% (n = 3) and 504 +/- 97% (n = 3), respectively. The GR 73632 (10 nM)-induced increase in electrically-evoked SP-LI release, was not prevented by SR140333 (100 nM). None of the agonists inhibited SP-LI release at lower concentrations (0.1 nM GR73632; 0.01 and 0.1 nM [Pro9]SP and 1-100 nM septide).6 NKA and NKB, at concentrations up to 10 nM which did not interfere with the RIA, did not modify electrically-evoked release of SP-LI.7 The ability of NKI receptor antagonists to enhance electrically-evoked SP-LI release supports the concept of an NK1 autoreceptor control mechanism at substance P nerve terminals within the dorsal horn of the rat spinal cord.

Topics: Amino Acid Sequence; Analgesics; Animals; Biphenyl Compounds; Calcitonin Gene-Related Peptide; Electric Stimulation; Hypnotics and Sedatives; In Vitro Techniques; Indoles; Isoindoles; Male; Molecular Sequence Data; Neurokinin-1 Receptor Antagonists; Piperidines; Quinuclidines; Rats; Rats, Wistar; Receptors, Neurokinin-1; Spinal Cord; Substance P

1. The effects on micturition of RP 67,580, a selective NK1 receptor antagonist, and SR 48,968, a highly, potent antagonist at NK2 receptor sites, given intrathecally (i.t.) or intra-arterially (i.a.) near the bladder, were investigated in unanaesthetized rats with and without bladder outlet obstruction. 2. In normal rats, RP 67,580, given i.t. in doses of 2 and 20 nmol per rat, decreased micturition pressure, but did not change other cystometric parameters. After 20 nmol of RP 67,580, dribbling incontinence due to retention was observed in 1 out of 7 animals. This effect was reversible. I.t. RP 67,580 in a dose of 2 nmol, had no effect on hyperactivity induced by intravesically instilled capsaicin. 3. In animals with bladder hypertrophy secondary to outflow obstruction, RP 67,580, given i.t. in a dose of 2 nmol per rat, decreased the micturition pressure, but had no effect on other cystometric parameters. After 20 nmol, dribbling incontinence due to retention was observed in 5 out of 7 animals. 4. RP 67,580, given i.a. in a dose of 4 nmol, had little effect on the cystometric parameters investigated, both in normal animals and rats with bladder hypertrophy. 5. SR 48,968, given i.t. in doses of 2 and 20 nmol per rat, had no clear-cut effects on the micturition pattern in normal rats, or rats with bladder hypertrophy. However, the drug reduced capsaicin-induced bladder hyperactivity. When given i.a. in a dose of 4 nmol, SR 48,968 had no effect on cystometric parameters in normal rats or rats with bladder hypertrophy. 6. The effects of both RP 67,580 and SR 48,968 were stereoselective, their enantiomers (RP 68,651 and SR 48,965) being inactive.7. These results thus suggest that at the spinal level there is a tachykinin involvement (via NK,receptors) in the micturition reflex induced by bladder filling, both in normal rats, and, more clearly, in animals with bladder hypertrophy secondary to outflow obstruction. The bladder response to filling was not influenced by blockade of vesical NKI and NK2 receptors. On the other hand, the bladder hyperactivity evoked by intravesical capsaicin seems to involve NK2 receptors both at the bladder and spinal levels.

Topics: Analgesics; Animals; Benzamides; Cystoscopy; Female; Hypertrophy; Indoles; Injections, Intra-Arterial; Injections, Spinal; Isoindoles; Neurokinin-1 Receptor Antagonists; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-2; Tachykinins; Urinary Bladder; Urinary Bladder Neck Obstruction; Urinary Catheterization; Urination

The intraperitoneal administration of cyclophosphamide (150 mg/kg, 48 h before cystometry) induced detrusor hyperreflexia in urethane-anaesthetized rats. Intrathecal administration of the selective tachykinin NK1 receptor antagonist, GR 82,334 ([D-Pro9(spiro-gamma-lactam)Leu10,Trp11]physalaemin-(1-11)) (1 nmol/rat i.t.) had no significant effect on micturition in normal rats but increased the volume threshold In cyclophosphamide-treated rats. Another tachykinin NK1 receptor antagonist, RP 67,580 ((3aR,7aR)-7,7-diphenyl-2-[1-imino-2(2-methoxyphenyl)ethyl]+ ++perhydroisoindol -4-one) (10 nmol/rat i.t.) increased the volume threshold to a similar extent in both vehicle- and cyclophosphamide-treated animals. The tachykinin NK2 receptor antagonist, SR 48,968 (S7-N-methyl-N[4-(acetylamino-4-phenylpiperidino)-2-(3,4- dichlorophenyl)butyl]benzamide hydrochloride (10 nmol/rat i.t.) did not modify micturition parameters in normal rats but antagonized bladder hyperreflexia in cyclophosphamide-treated animals; SR 48,968 restored the volume threshold for the micturition reflex to values close to control values. SR 48,965 (R7-N-methyl-N[4-(acetylamino-4-phenylpiperidino)-2-(3,4- dichlorophenyl)butyl]benzamide hydrochloride) (10 nmol/rat i.t.), the enantiomer of SR 48,968 devoid of affinity for tachykinin NK2 receptors, was inactive. 2-Amino-5-phosphonovaleric acid (25 and 250 nmol/rat i.t.), a selective antagonist of NMDA receptors, augmented the volume threshold both in controls and in rats with detrusor hyperreflexia; after administration of this antagonist, however, the volume threshold in cyclophosphamide-treated animals was still lower than in controls. Intravenous administration of SR 48,968, RP 67,580, or the combined administration of SR 48,968 and RP 67,580 had no effect on cystometry variables either in rats with detrusor hyperreflexia or in controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 2-Amino-5-phosphonovalerate; Animals; Benzamides; Cyclophosphamide; Cystitis; Indoles; Injections, Intravenous; Injections, Spinal; Isoindoles; Male; Neurokinin-1 Receptor Antagonists; Physalaemin; Piperidines; Rats; Rats, Wistar; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Spinal Cord; Urinary Incontinence; Urination

1. Three non-peptide tachykinin receptor antagonists, CP-96,345, RP 67580 and SR 48968, were found to inhibit the electrically-evoked, tachykinin-mediated contractile responses of the rabbit iris sphincter in a concentration-dependent fashion; the pIC50 values were 5.6 +/- 0.01, 5.4 +/- 0.07 and 4.8 +/- 0.03, respectively. 2. These antagonists also inhibited the electrically-evoked, parasympathetic response of the rabbit iris sphincter and the sympathetic response of the guinea-pig vas deferens in a concentration-dependent manner; the pIC50 values were 0.3-1.2 log units lower than those recorded for the tachykinin-mediated responses. 3. Two local anaesthetics, bupivacaine and oxybuprocaine, were also found to inhibit the tachykinin-mediated, cholinergic and sympathetic contractile responses in these tissues in a concentration-dependent manner; the concentration ranges for producing the inhibition were similar to those of the non-peptide tachykinin receptor antagonists. 4. On the sciatic nerves of frogs, the tachykinin receptor antagonists inhibited action potentials in a concentration-dependent manner; the potency of the three drugs was similar to that of bupivacaine. 5. Our results suggest that, in addition to blocking tachykinin receptors, the non-peptide tachykinin receptor antagonists, CP-96,345, RP 67580 and SR 48968, may exert non-specific inhibitory effects on neurotransmission.

Topics: Action Potentials; Anesthetics, Local; Animals; Benzamides; Biphenyl Compounds; Bupivacaine; Electric Stimulation; Female; Guinea Pigs; In Vitro Techniques; Indoles; Iris; Isoindoles; Male; Muscle Contraction; Muscle, Smooth; Piperidines; Procaine; Rabbits; Rana catesbeiana; Receptors, Tachykinin; Sciatic Nerve; Synaptic Transmission; Vas Deferens

The tachykinin receptor antagonists (3aR,7aR)-7,7-diphenyl-2(1-imino-2-(2-methoxyphenyl/ethyl)++ +perhydroisoindole) (RP 67580) and (+)-(2S-3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine (CP-99,994), which act selectively at neurokinin (NK)1 receptors, inhibited the early phase of formalin-induced pain in mice. Although (+)-(1-hydroxy-3-aminopyrrolidine-2-one) ((+)-HA966), a partial agonist at glycine B receptors, was inactive alone, it potentiated the actions of RP 67580 (but not its inactive stereoisomer, RP68651) and CP-99,994. In its presence, the dose-response curve for RP 67580 was dose-dependently shifted to the left. In contrast, (+)-HA966 did not modify the induction of ataxia by RP 67580 and CP-99,994. These data suggest that co-administration of partial agonists at glycine B receptors may improve the antinociceptive potency and 'therapeutic window' of tachykinin NK1 receptor antagonists.

Topics: Analgesics; Animals; Behavior, Animal; Dose-Response Relationship, Drug; Drug Synergism; Glycine; Indoles; Isoindoles; Male; Mice; Piperidines; Pyrrolidinones; Receptors, Glycine; Receptors, Tachykinin

The molecular mechanism of action of three chemically distinct nonpeptide antagonists, SR 140,333, FK 888, and RP 67,580, was compared with that of the previously characterized compound CP 96,345, using a series of chimeric constructs between their common target, the rat neurokinin (NK)-1 (substance P) receptor, and the homologous nonresponsive NK-3 (NKB) receptor. The ability of all four nonpeptide compounds to displace radiolabeled substance P from the NK-1 receptor and their ability to inhibit the peptide-induced increase in inositol phosphate turnover were critically dependent on structural elements located in an area from the middle of the second extracellular loop through transmembrane segments V and VI to the middle of the third extracellular loop of the NK-1 receptor. Dissection of the domain around the outer part of transmembrane segments V and VI into smaller segments demonstrated that the individual nonpeptide antagonists, in agreement with their distinct chemical structures, were dependent on different subepitopes within the common putative binding domain. Full NK-1-like susceptibility to SR 140,333, FK 888, and CP 96,345 could be transferred to the NK-3 receptor by exchange of transmembrane segments V and VI and adjacent parts with corresponding segments from the NK-1 receptor. For SR 140,333 and CP 96,345, almost the same effect could be achieved by transfer of two discontinuous segments around the top of transmembrane segments V and VI. RP 67,580 shared interaction sites with the other compounds around the top of transmembrane segment VI but appeared also to be dependent on transmembrane segment VII. It is concluded that four nonpeptide antagonists, despite overt chemical differences, appear to block NK-1 receptor function by interacting in distinct ways with a common site located spatially around the outer part of transmembrane segment VI.

Topics: Animals; Binding Sites; CHO Cells; Cricetinae; Dipeptides; Gene Transfer Techniques; Indoles; Inositol Phosphates; Isoindoles; Neurokinin-1 Receptor Antagonists; Piperidines; Quinuclidines; Rats; Receptors, Neurokinin-1; Receptors, Neurokinin-3

Substance P binds to and activates the neurokinin-1 receptor with high affinity, thereby modulating several neuronal pathways including pain transmission and neurogenic inflammation. Several high affinity non-peptide antagonists have recently been described. To elucidate the molecular interactions specific for binding to the neurokinin-1 receptor, site-directed mutagenesis has been utilized to identify amino acid residues that interact directly with antagonists. Glutamine 165 in the fourth transmembrane segment was shown to be critical for the binding of CP-96,345 but not SR140333. Analysis of quinuclidine analogs suggests that glutamine 165 interacts with the C-3 heteroatom in this class of antagonists, probably through a hydrogen bond. Glutamine 165 also plays a minor role in the binding of peptides and RP67580. In contrast, serine 169 was determined to be critical for the binding of RP67580. These data indicate that residues 165 and 169 in the fourth transmembrane segment, along with residues in the fifth, sixth, and seventh transmembrane segments as demonstrated previously, form the non-peptide antagonist binding site in the neurokinin-1 receptor. Furthermore, the antagonist binding site overlaps with the binding site for peptide agonists in the fourth and seventh transmembrane segments.

Topics: Amino Acid Sequence; Biphenyl Compounds; Cell Membrane; Cells, Cultured; Glutamine; Humans; Hydrogen Bonding; Indoles; Isoindoles; Molecular Sequence Data; Neurokinin-1 Receptor Antagonists; Piperidines; Protein Conformation; Quinuclidines; Receptors, Neurokinin-1

Residue number 17 in transmembrane segment VI has been shown to be crucial for the binding of agonists in G-protein-coupled receptors for the monoamines. In many peptide receptors a histidyl residue has been conserved at this position. We find that replacement of HisVI-17 in the NK-1 receptor with either glutamine, phenylalanine, or alanine has no apparent effect on the binding of the natural peptide ligand substance P or on the agonist induced increase in inositolphosphate turnover. However, the binding of certain non-peptide antagonists was impaired; for example, replacement of HisVI-17 with alanine decreased the affinity for FK888 and RP67,580 5- to 12-fold, respectively. A glutamine side chain was a good substitute for the imidazole in the binding of all non-peptide antagonists. It is concluded that the conserved HisVI-17 in the NK-1 receptor is involved in the binding of certain non-peptide antagonists, but is not important for the action of the natural peptide agonist, substance P.

Topics: Amino Acid Sequence; Animals; Binding Sites; Binding, Competitive; Biphenyl Compounds; Cell Line; Cell Membrane; Conserved Sequence; Dipeptides; Humans; Indoles; Isoindoles; Kinetics; Molecular Sequence Data; Mutagenesis, Site-Directed; Neurokinin-1 Receptor Antagonists; Piperidines; Protein Structure, Secondary; Quinuclidines; Receptors, Neurokinin-1; Recombinant Proteins; Sequence Homology, Amino Acid; Substance P; Transfection

The tachykinin receptor type that mediates tachykinin-induced plasma extravasation in the rat knee joint was identified by using selective antagonists as well as natural or synthetic agonists. Substance P (SP) and neurokinin (NK) A induced plasma extravasation with almost the same potency and the maximum response was obtained at 5 nmol/knee. NKB was about ten times less potent than SP or NKA. The NK1 selective agonist, [Sar9, Met(O2)11]-SP, was about ten times more potent than SP, and the NK2 selective agonist, [Nle10]-NKA4-10, was about fifty times less potent than NK1 agonist. The NK3 agonist, Senktide, was totally ineffective at 0.5-50 nmol/knee. All responses induced by SP (5 nmol/knee), NKA (5 nmol/knee), NKB (50 nmol/knee), NK1 agonist (0.5 nmol/knee) or NK2 agonist (25 nmol/knee) were significantly and profoundly inhibited by the NK1 selective antagonist, RP67580, but not by the NK2 selective antagonist, SR48968. Taken together, we conclude that tachykinin-induced plasma extravasation in the rat knee joint is mediated via NK1 receptors.

Topics: Animals; Benzamides; Capillary Permeability; Evans Blue; Hindlimb; Indoles; Isoindoles; Joints; Male; Neurokinin A; Neurokinin-1 Receptor Antagonists; Piperidines; Rats; Rats, Wistar; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Substance P; Synovial Fluid; Tachykinins

Locally applied lactic acid and capsaicin caused extravasation of Evans blue dye in trachea, main bronchi and nasal mucosa of anaesthetized rats. In animals pretreated with capsaicin to deplete sensory neuropeptides, the lactic acid response was abolished in main bronchi and highly reduced in trachea. Pretreatment with the NK1 receptor antagonist, RP 67580 (3 mg x kg-1 intravenously), markedly inhibited the lactic acid-induced extravasation at all levels; similar pretreatment with NK2 receptor antagonist, SR 48968 (0.5 mg x kg-1 intravenously), was ineffective. Locally applied ruthenium red (a transmembrane Ca2+ fluxes inhibitor), capsazepine (a capsacin receptor antagonist) and diclofenac intraperitoneally (a cyclooxygenase blocker) did not change the lactic acid effect, while the capsaicin response was only diminished in bronchi by local pretreatment with ruthenium red. In conclusion locally applied lactic acid in rat trachea and nasal cavity activated capsaicin sensitive sensory nerve endings producing plasma protein extravasation. This reaction was shown to be mediated by tachykinins acting on the NK1 receptor through a mechanism which appeared to be resistant to capsazepine and ruthenium red and independent of cyclooxygenase products. In comparison the effect of capsacin was partially ruthenium red-sensitive but not influenced by capsazepine.

Topics: Animals; Benzamides; Blood Proteins; Bronchi; Capsaicin; Evans Blue; Extravasation of Diagnostic and Therapeutic Materials; Indoles; Isoindoles; Lactates; Lactic Acid; Male; Nasal Mucosa; Neurokinin-1 Receptor Antagonists; Neurons, Afferent; Piperidines; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-1; Respiratory Physiological Phenomena; Respiratory System; Trachea