sb-223412 and senktide

To determine whether bronchoconstriction can be mediated via the tachykinin NK₃ receptors, isolated guinea pig lungs were challenged with the exogenous tachykinin NK₃-receptor agonists [MePhe⁷]-neurokinin B ([MePhe⁷]-NKB) and senktide. [MePhe⁷]-NKB induced bronchoconstriction (EC50 = 11.8 ± 1.7 µM) that was significantly inhibited by the tachykinin NK₃-receptor antagonist SB 223412 at 10 µM (EC50 = 24.4 ± 4.5 µM). Senktide also induced bronchoconstriction (EC50 = 96.2 ± 20.3 µM) and the bronchoconstriction was significantly reduced by SB 223412 at 1 and 10 µM (EC50 = 270.8 ± 78.9 µM and 388.3 ± 105.5 µM, respectively). Although the authors demonstrated that SB 223412, [MePhe⁷]-NKB, and senktide are potent and selective for the tachykinin NK3 receptors in binding and functional (Ca(2+) mobilization) assays, the tachykinin NK₁-receptor antagonist CP 99,994 at 1 µM (EC50 = 32.7 ± 8.5 µM) produced inhibition of [MePhe⁷]-NKB-induced bronchoconstriction, whereas the tachykinin NK₂-receptor antagonist SR 48968 at 0.1 µM (EC50 = 213.2 ± 42.9 µM) blocked senktide-induced bronchoconstriction. These data suggest that [MePhe⁷]-NKB and senktide caused bronchoconstriction in guinea pig through activation of the tachykinin NK₃-receptors but the tachykinin NK₁- and/or NK₂-receptors are also involved in the response.

Topics: Animals; Bronchoconstriction; Bronchoconstrictor Agents; CHO Cells; Cricetinae; Cricetulus; Disease Models, Animal; Guinea Pigs; In Vitro Techniques; Lung; Male; Peptide Fragments; Piperidines; Quinolines; Receptors, Neurokinin-3; Substance P

Intracerebroventricular (i.c.v.) administration of tachykinin NK(1) receptor agonists induces tapping of the hind legs in gerbils, so-called gerbil foot tapping, which is thought to reflect a fear-related response. The aim of the present study was to examine how ligands selective for NK(1), NK(2) and NK(3) receptors affect the gerbil foot tap response. Agonists selective for NK receptor subtypes were administered i.c.v. and the gerbil foot tap response was monitored. The effect of systemically administered antagonists was also studied. The interaction of ligands with gerbil NK(1) receptors was evaluated using autoradiography on gerbil brain slices with [(3)H]-Sar,Met(O(2))-substance P or [(3)H]GR205171 as radioligand. The effects of ligands on NK(1) and NK(3) receptor-mediated increases in intracellular calcium in vitro were studied in Chinese hamster ovary cells expressing the cloned gerbil receptors. The selective NK(1) receptor agonist ASMSP and the selective NK(3) receptor agonist senktide induced dose-dependent increases in gerbil foot tapping with similar potency. The maximal effect of senktide was approximately 40% of the maximal response evoked by ASMSP. The effects of ASMSP and senktide were blocked by administration of the selective NK(1) receptor antagonist CP99,994 (10 micromol/kg s.c.). The effects of senktide, but not ASMSP, were blocked by administration of the selective NK(3) receptor antagonist SB223412 (50 micromol/kg i.p.). Senktide did not displace NK(1) receptor radioligand binding and was >1000-fold less potent than ASMSP at activating gerbil NK(1) receptors. The selective NK(3) receptor agonist senktide evokes fear-related gerbil foot tapping, an effect which probably involves indirect enhancement of NK(1) receptor signalling.

Topics: Animals; Autoradiography; Behavior, Animal; Brain; Calcium; CHO Cells; Cloning, Molecular; Cricetinae; Cricetulus; Dose-Response Relationship, Drug; Foot; Gerbillinae; Injections, Intraventricular; Male; Neurokinin A; Neurokinin-1 Receptor Antagonists; Peptide Fragments; Piperidines; Quinolines; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Substance P

The neuropeptide tachykinins and their receptors have been implicated in the pathogenesis of lung disease, although the role of the tachykinin neurokinin-3 receptor has not been elucidated. Using confocal microscopy, we identified tachykinin neurokinin-3 receptors on human bronchial parasympathetic ganglion neurons. Electrophysiologic recordings demonstrated that activation of sensory nerve fibers, either by antidromic stimulation or capsaicin, depolarized these neurons. This response was mimicked by exogenously applied tachykinin neurokinin-3 receptor-selective agonist, senktide analogue, but not significantly by tachykinin neurokinin-1 or neurokinin-2 receptor-selective agonists. Responses to endogenous tachykinins or exogenous selective tachykinin neurokinin-3 receptor activation with senktide analogue were inhibited by the selective tachykinin neurokinin-3 receptor antagonists, SB 223412 or SB 235375. We provide the first evidence that tachykinin neurokinin-3 receptors regulate human bronchial parasympathetic ganglion neurotransmission by activation of a peripheral reflex. This pathway may play a significant role in controlling bronchomotor tone and air flow to the lung.

Topics: Acetates; Adult; Bronchi; Capsaicin; Electric Stimulation; Evoked Potentials; Female; Ganglia, Parasympathetic; Humans; Male; Microscopy, Confocal; Middle Aged; Nerve Fibers; Neurons, Afferent; Peptide Fragments; Quinolines; Receptors, Neurokinin-3; Substance P; Synaptic Transmission

Neurokinin-containing nerve fibers were localized to guinea pig airway parasympathetic ganglia in control tissues but not in tissues pretreated with capsaicin. The purpose of the present study was to determine whether neurokinins, released during axonal reflexes or after antidromic afferent nerve stimulation, modulate ganglionic synaptic neurotransmission. The neurokinin type 3 (NK(3)) receptor antagonists SB-223412 and SR-142801 inhibited vagally mediated cholinergic contractions of bronchi in vitro at stimulation voltages threshold for preganglionic nerve activation but had no effect on vagally mediated contractions evoked at optimal voltage or field stimulation-induced contractions. Intracellular recordings from the ganglia neurons revealed that capsaicin-sensitive nerve stimulation potentiated subsequent preganglionic nerve-evoked fast excitatory postsynaptic potentials. This effect was mimicked by the NK(3) receptor agonist senktide analog and blocked by SB-223412. In situ, senktide analog markedly increased baseline tracheal cholinergic tone, an effect that was reversed by atropine and prevented by vagotomy or SB-223412. Comparable effects of intravenous senktide analog on pulmonary insufflation pressure were observed. These data highlight the important integrative role played by parasympathetic ganglia and indicate that activation of NK(3) receptors in airway ganglia by endogenous neurokinins facilitates synaptic neurotransmission.

Topics: Animals; Bronchi; Bronchoconstriction; Electric Stimulation; Excitatory Postsynaptic Potentials; Ganglia, Parasympathetic; Guinea Pigs; Immunohistochemistry; In Vitro Techniques; Male; Neurons; Peptide Fragments; Piperidines; Quinolines; Receptors, Neurokinin-3; Substance P; Synaptic Transmission; Trachea; Vagotomy; Vagus Nerve

Previous studies in vitro have shown that NK3 receptors exist on primary afferent terminals in rat spinal cord and mediate potentiation of the depolarisation-evoked substance P (SP) release. In the present study we have investigated the role of the NK3 receptor-mediated SP release system in a model of inflammatory pain. Monoarthritis was induced in rats by unilateral injection of complete Freund's adjuvant (CFA); withdrawal latencies to a thermal stimulus were subsequently measured at various times following CFA. The CFA-treated paw displayed hyperalgesia as early as 4 h after CFA injection and hyperalgesia was maintained until day 4 but had disappeared by day 21. The thermal hyperalgesia was associated with an increase in basal SP release from spinal cord synaptosomes. The possible involvement of endogenous neurokinin B acting at NK3 receptors was tested by using SB 223412-A [(S)-(-)-N-(alpha-ethylbenzyl)-3-hydroxy-2-phenylquinoline-4-carbo xamide hydrochloride], a novel, potent (Ki=30 nM) and selective (Ki>10,000 nM for NK1 and NK2 receptors), non-peptidic NK3 receptor antagonist. In vitro SB 223412-A antagonised the potentiation of SP release produced by senktide in spinal cord synaptosomes. Administered systemically to monoarthritic rats (50 mg/kg, p.o., b.i.d., for 4 days), the NK3 receptor antagonist SB 223412-A significantly reduced thermal hyperalgesia and normalised the basal release of SP from spinal cord synaptosomes. The data suggest that neurokinin B acting at NK3 receptors that mediate SP release within the spinal cord play a role in inflammation. These NK3 receptors may represent, therefore, appropriate targets in the therapy of inflammatory pain.

Topics: Afferent Pathways; Animals; Arthritis, Experimental; Freund's Adjuvant; Hyperalgesia; Inflammation; Male; Pain; Peptide Fragments; Quinolines; Rats; Rats, Sprague-Dawley; Reaction Time; Receptors, Neurokinin-3; Spinal Cord; Substance P

Optimization of the previously reported 2-phenyl-4-quinolinecarboxamide NK-3 receptor antagonist 14, with regard to potential metabolic instability of the ester moiety and affinity and selectivity for the human neurokinin-3 (hNK-3) receptor, is described. The ester functionality could be successfully replaced by the ketone (31) or by lower alkyl groups (Et, 21, or n-Pr, 24). Investigation of the substitution pattern of the quinoline ring resulted in the identification of position 3 as a key position to enhance hNK-3 binding affinity and selectivity for the hNK-3 versus the hNK-2 receptor. All of the chemical groups introduced at this position, with the exception of halogens, increased the hNK-3 binding affinity, and compounds 53 (3-OH, SB 223412, hNK-3-CHO binding Ki = 1.4 nM) and 55 (3-NH2, hNK-3-CHO binding Ki = 1.2 nM) were the most potent compounds of this series. Selectivity studies versus the other neurokinin receptors (hNK-2-CHO and hNK-1-CHO) revealed that 53 is about 100-fold selective for the hNK-3 versus hNK-2 receptor, with no affinity for the hNK-1 at concentrations up to 100 microM. In vitro studies demonstrated that 53 is a potent functional antagonist of the hNK-3 receptor (reversal of senktide-induced contractions in rabbit isolated iris sphincter muscles and reversal of NKB-induced Ca2+ mobilization in CHO cells stably expressing the hNK-3 receptor), while in vivo this compound showed oral and intravenous activity in NK-3 receptor-driven models (senktide-induced behavioral responses in mice and senktide-induced miosis in rabbits). Overall, the biological data indicate that (S)-N-(1-phenylpropyl)-3-hydroxy-2-phenylquinoline-4-carboxamide (53, SB 223412) may serve as a pharmacological tool in animal models of disease to assess the functional and pathophysiological role of the NK-3 receptor and to establish therapeutic indications for non-peptide NK-3 receptor antagonists.

Topics: Animals; Calcium; Cell Line; CHO Cells; Cloning, Molecular; Cricetinae; Humans; In Vitro Techniques; Iris; Mice; Miosis; Motor Activity; Muscle Contraction; Muscle, Smooth; Peptide Fragments; Quinolines; Rabbits; Radioligand Assay; Receptors, Neurokinin-3; Structure-Activity Relationship; Substance P

1. Inhibition of NK3 receptor agonist-induced contraction in the rabbit isolated iris sphincter muscle was used to assess the in vitro functional activity of three 2-phenyl-4-quinolinecarboxamides, members of a novel class of potent and selective non-peptide NK3 receptor antagonists. In addition, an in vivo correlate of this in vitro response, namely NK3 receptor agonist-induced miosis in conscious rabbits, was characterized with some of these antagonists. 2. In vitro senktide (succinyl-[Asp9,MePhe8]-substance P (6-11) and [MePhe7]-neurokinin B ([MePhe7]-NKB) were potent contractile agents in the rabbit iris sphincter muscle but exhibited quite different profiles. Senktide produced monophasic log concentration-effect curves with a mean pD2=9.03+/-0.06 and mean nH=1.2+/-0.02 (n=14). In contrast, [MePhe7]-NKB produced shallow log concentration-effect curves which often appeared biphasic (nH=0.54+/-0.04, n=8), preventing the accurate determination of pD2 values. 3. The contractile responses to the NK3 receptor agonist senktide were antagonized in a surmountable and concentration-dependent manner by SB 223412 ((-)-(S)-N-(alpha-ethylbenzyl)-3-hydroxy-2-phenylquinoline-4-ca rboxamide; 3-30 nM, pA2=8.4, slope=1.8+/-0.3, n=4). SB 222200 ((-)-(S)-N-(alpha-ethylbenzyl)-3-methyl-2-phenylquinoline-4-car box amide; 30-300 nM, pA2=7.9, slope=1.4+/-0.06, n=4) and SB 218795 ((-)-(R)-N-(alpha-methoxycarbonylbenzyl)-2-phenylquinoline-4-carboxamide; 0.3 and 3 microM apparent pKB=7.4+/-0.06, n=6). 4. Contractile responses to the NK3 receptor agonist [MePhe7]-NKB in the rabbit iris sphincter muscle were unaffected by SB 218795 (0.3 and 3 microM, n=8). In contrast, SB 223412 (30 and 300 microM n=4) and SB 222200 (0.3 and 3 microM, n=4) inhibited responses to low concentrations (< or = 1 nM), to a greater extent than higher concentrations (> 1 nM) of [MePhe7]-NKB. Furthermore, log concentration-effect curves to [MePhe7]-NKB became steeper and monophasic in the presence of each antagonist. 5. SB 218795 (3 microM, n=4) had no effect on contractions induced by transmural nerve stimulation (2 Hz) or substance P, exemplifying the selectivity of this class of antagonist for functional NK3 receptors over NK1 receptors in the rabbit. 6. In vivo, senktide (1, 10 and 25 microg i.v., i.e. 1.2, 11.9 and 29.7 nmol, respectively) induced concentration-dependent bilateral miosis in conscious rabbits (maximum pupillary constriction=4.25+/-0.25 mm; basal pupillary diameter 7.75+/-0.48 mm; n=4).

Topics: Animals; In Vitro Techniques; Iris; Male; Miosis; Muscle Contraction; Muscle, Smooth; Neurokinin B; Neurokinin-1 Receptor Antagonists; Peptide Fragments; Piperidines; Quinolines; Rabbits; Receptors, Neurokinin-3; Substance P

Topics: Animals; Binding, Competitive; CHO Cells; Ciliary Body; Cricetinae; Cricetulus; Drug Design; Guinea Pigs; Humans; Muscle Contraction; Peptide Fragments; Piperidines; Quinolines; Rabbits; Receptors, Neurokinin-3; Recombinant Fusion Proteins; Structure-Activity Relationship; Substance P