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Candenas L, Lecci A, Pinto FM, Patak E, Maggi CA, Pennefather JN. Tachykinins and tachykinin receptors: effects in the genitourinary tract. Life Sci 2005; 76:835-62. [PMID: 15589963 DOI: 10.1016/j.lfs.2004.10.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Accepted: 07/30/2004] [Indexed: 11/30/2022]
Abstract
Tachykinins (TKs) are a family of peptides involved in the central and peripheral regulation of urogenital functions through the stimulation of TK NK1, NK2 and NK3 receptors. At the urinary system level, TKs locally stimulate smooth muscle tone, ureteric peristalsis and bladder contractions, initiate neurogenic inflammation and trigger local and spinal reflexes aimed to maintain organ functions in emergency conditions. At the genital level, TKs are involved in smooth muscle contraction, in inflammation and in the modulation of steroid secretion by the testes and ovaries. TKs produce vasodilatation of maternal and fetal placental vascular beds and appear to be involved in reproductive function, stress-induced abortion, and pre-eclampsia. The current data suggest that the genitourinary tract is a primary site of action of the tachykininergic system.
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Affiliation(s)
- Luz Candenas
- Instituto de Investigaciones Químicas, Centro de Investigaciones Científicas Isla de La Cartuja, Avda. Americo Vespucio s/n, 41092 Sevilla, Spain.
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Weisshoff H, Nagel T, Hänsicke A, Zschunke A, Mügge C. Structure determination and by-product profile of the NK(2) receptor antagonist nepadutant, a bicyclic glycopeptide. FEBS Lett 2001; 491:299-304. [PMID: 11240145 DOI: 10.1016/s0014-5793(01)02203-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have synthesized and fully characterized the NK(2) receptor antagonist nepadutant and its by-products using nuclear magnetic resonance (NMR) and restrained molecular dynamics. The agent consists of an active bicyclic hexapeptide combined with a sugar residue. Analysis of the high-performance liquid chromatogram and the mass spectroscopy spectra yields traces of three by-products with the same molecular weight as the main product. The conformation of the molecules in the bicyclic hexapeptide segment, the active region, is well defined, whereas the sugar moiety is disordered. For the peptide region of nepadutant and all of its by-products, the NMR observables can be described by a single backbone conformation, more specifically a betaI, betaII-turn arrangement. The active dipeptide unit Trp-Phe occupies the i+1 and i+2 position of a betaI-turn. The by-product profile is characterized by different forms of sugars which are caused mainly by isomerization in the process of ring opening.
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Affiliation(s)
- H Weisshoff
- Institute of Chemistry, Humboldt University of Berlin, Germany
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Onori L, Aggio A, Taddei G, Tonini M. Contribution of NK(2) tachykinin receptors to propulsion in the rabbit distal colon. Am J Physiol Gastrointest Liver Physiol 2000; 278:G137-47. [PMID: 10644572 DOI: 10.1152/ajpgi.2000.278.1.g137] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The role of the tachykinin neurokinin (NK)(2) receptors on rabbit distal colon propulsion was investigated by using two selective NK(2)-receptor antagonists, MEN-10627 and SR-48968. Experiments on colonic circular muscle strips showed that contractile responses to [beta-Ala(8)]NKA-(4-10) (1 nM-1 microM), a selective NK(2)-receptor agonist, were competitively antagonized by MEN-10627 (1-100 nM), whereas SR-48968 (0.1-10 nM) caused an insurmountable antagonism, thus confirming the difference in the mode of action of the two compounds. Colonic propulsion was elicited by distending a mobile rubber balloon with 0.3 ml (submaximal stimulus) or 1.0 ml (maximal stimulus) of water. The velocity of anal displacement of the balloon (mm/s) was considered the main propulsion parameter. At low concentrations (1.0-100 nM and 0.1-10 nM, respectively), MEN-10627 and SR-48968 facilitated the velocity of propulsion, whereas at high concentrations (100 nM and 1 microM, respectively) they decelerated propulsion. The excitatory and inhibitory effects of both antagonists were observed only with submaximal stimulus. We focused on the hypothesis that the facilitatory effect on propulsion may result from blockade of neuronal NK(2) receptors and the inhibitory effect from suppression of the excitatory transmission mediated by NK(2) receptors on smooth muscle cells. In the presence of N(G)-nitro-L-arginine (300 microM), a nitric oxide synthase inhibitor, MEN-10627, at a concentration (10 nM) that was found to accelerate propulsion in control experiments inhibited the velocity of propulsion. In the presence of threshold (1-10 nM) or full (1 microM) concentration of atropine, which inhibited to a great extent the velocity of propulsion, the inhibitory effect of MEN-10627 (1 microM) was markedly increased. In conclusion, in the rabbit distal colon NK(2) receptors may decelerate propulsion by activating a nitric oxide-dependent neuronal mechanism and may accelerate it by a postjunctional synergistic interaction with cholinergic muscarinic receptors.
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Affiliation(s)
- L Onori
- Department of Internal Medicine and Public Health, University of L'Aquila, 67100 L'Aquila, Italy
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Abstract
The tachykinins (TKs) are a family of small peptides which share the common C-terminal sequence Phe-X-Gly-Leu-MetNH2. Three peptides of this family, substance P, neurokinin A and neurokinin B, have an established role as neurotransmitters in mammals. 2. Three receptors for TKs have been cloned: they are G-protein coupled receptors with seven putative transmembrane spanning segments and have been termed NK1 (substance P-preferring), NK2 (neurokinin A-preferring) and NK3 (neurokinin B-preferring). 3. Synthetic agonists are available to selectively stimulate only one receptor, while natural TKs can act as full agonist at each one of the three receptors, albeit at different concentrations. 4. A number of potent and selective antagonists, both peptide and nonpeptide in nature, have recently been developed. 5. The introduction of these ligands has revealed an unforeseen pharmacological heterogeneity of NK1, NK2 and NK3 receptors which appears largely, if not exclusively, linked to the existence of species homologues of the three receptors.
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Affiliation(s)
- C A Maggi
- Pharmacology Department, A. Menarini Pharmaceuticals, Florence, Italy
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Abstract
For a long time research on the action of TKs on gastrointestinal tissue has been demonstrating the importance of the TKs as non-cholinergic stimulators of motility in most parts of the mammalian gastrointestinal tract. The past years witnessed the development of TK agonists and antagonists selective for the various receptor types, which prompted a wealth of new insight into the pharmacology and molecular biology of the TK receptors. This knowledge now allows a more specific elucidation of the role of TKs and their receptors in the various aspects of gastrointestinal motility, not only in normal tissue but also under pathological conditions.
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Affiliation(s)
- U Holzer-Petsche
- Department of Experimental and Clinical Pharmacology, Karl-Franzens-University, Graz, Austria
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Affiliation(s)
- L Quartara
- Chemistry Department, A. Menarini Industrie Farmaceutiche Riunite, Firenze, Italy
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Wiesenfeld-Hallin Z, Luo L, Xu XJ, Maggi CA. Differential effects of selective tachykinin NK2 receptor antagonists in rat spinal cord. Eur J Pharmacol 1994; 251:99-102. [PMID: 8137876 DOI: 10.1016/0014-2999(94)90449-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The effects of intrathecally (i.t.) injected selective tachykinin NK2 receptor antagonists, MEN 10,207, MEN 10,376 and R396, on the spinal effect of neurokinin A were studied in decerebrate, spinalized, unanesthetized rats. I.t. neurokinin A (7 pmol) briefly facilitated the flexor reflex, an effect that was dose dependently inhibited by pretreatment with MEN 10,207 and MEN 10,376 with similar and high potency. I.t. R396 itself caused strong facilitation of the flexor reflect. At lower doses, the effect of i.t. neurokinin A was potentiated by R396. R396 only exhibited moderate antagonism of neurokinin A-induced reflex facilitation even at very high doses. It has been proposed that the tachykinin NK2 receptor may be further classified into two subtypes, NK2A and NK2B, with MEN 10,207 and MEN 10,376 having high affinity for the former and R396 for the latter. Our results suggested that the tachykinin NK2 receptor in rat spinal cord which mediates the excitatory effect of neurokinin A may belong to the NK2A subpopulation of receptors.
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Affiliation(s)
- Z Wiesenfeld-Hallin
- Department of Laboratory Medical Science and Technology, Huddinge University Hospital, Karolinska Institute, Sweden
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Astolfi M, Manzini S, Maggi CA, Giachetti A. Comparison of NK-2 selective peptide and non-peptide antagonists in rat distal colon muscularis mucosae. ACTA ACUST UNITED AC 1993. [DOI: 10.1111/j.1474-8673.1993.tb00285.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Maggi CA, Quartara L, Patacchini R, Giuliani S, Barbanti G, Turini D, Giachetti A. MEN 10,573 and MEN 10,612, novel cyclic pseudopeptides which are potent tachykinin NK-2 receptor antagonists. REGULATORY PEPTIDES 1993; 47:151-8. [PMID: 8234901 DOI: 10.1016/0167-0115(93)90419-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The activity and selectivity of MEN 10,573 and MEN 10,612, novel cyclic pseudopeptides which are selective tachykinin NK-2 receptor antagonists is described, as compared to that of previously characterized linear and cyclic compounds. For the NK-2 receptor, the activity of test compounds was investigated in the hamster isolated trachea (HT) and the endothelium-deprived rabbit isolated pulmonary artery (RPA), two preparations which are endowed with pharmacologically distinct forms of the NK-2 receptor. The novel cyclic pseudopeptides, MEN 10,573 and MEN 10,612 displayed very high affinity for the NK-2 receptor in the HT (pA2 8.66 and 9.06, respectively) which is higher than that observed in the RPA (pA2 7.31 and 7.41 for MEN 10,573 and MEN 10,612, respectively). The antagonism exerted by MEN 10,573 and MEN 10,612 was of competitive nature in both preparations. MEN 10,573 and MEN 10,612 also displayed competitive antagonism for NK-2 receptor-mediated responses in the rabbit bronchus (RB), rat vas deferens (RVD), circular muscle of the human colon (HUC) and ileum (HUI). In the RB, HUC and HUI, the potency of the novel cyclic pseudopeptides was comparable to that of MDL 29,913 and about 10-fold greater than that of L659,877. In the RVD however, the potency of MEN 10,573 MEN 10,612 or MDL 29,913 was similar to that of L659,877. In anaesthetized rats, i.v. injection of MEN 10,612 produced a selective and long-lasting blockade of the urinary bladder contraction produced by the i.v. injection of the NK-2 receptor selective agonist [beta Ala8]neurokinin A(4-10), without affecting the response to the NK-1 receptor selective agonist [Sar9]substance P sulfone.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- C A Maggi
- A. Menarini Pharmaceuticals, Department of Pharmacology, Florence, Italy
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Guard S, Pain D, Franks R, Watling KJ. [125I]neurokinin A labels pharmacologically distinct populations of NK2 binding sites in hamster and rabbit urinary bladder. Eur J Pharmacol 1993; 232:287-90. [PMID: 8385619 DOI: 10.1016/0014-2999(93)90786-h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The pharmacological profile of NK2 binding sites has been characterised in homogenates of rabbit urinary bladder and compared with that present in homogenates of hamster bladder. In both species, [125I]neurokinin A-specific binding to urinary bladder membranes was displaced by neurokinin A and the NK2 agonist [beta-Ala8]neurokinin A-(4-10) whilst the NK1 ligands [Sar9,Met(O2)11]substance P and (+/-)-CP-96,345, and the NK3 agonist, senktide, were only weak displacers or ineffective. At rabbit NK2 sites, the rank order of affinity of NK2 receptor-selective antagonists was; MEN 10,376 > MEN 10,207 > L-659,877 >> R 396. In contrast, the rank order of displacement of [125I]neurokinin A-specific binding to hamster bladder membranes was: L-659,877 > R 396 > MEN 10,376 > MEN 10,207. These data demonstrate that [125I]neurokinin A binds to pharmacologically distinct NK2 binding sites in hamster and rabbit urinary bladder.
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Affiliation(s)
- S Guard
- Parke-Davis Neuroscience Research Centre, Addenbrookes Hospital Site, Cambridge, UK
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Maggi CA, Patacchini R, Rovero P, Giachetti A. Tachykinin receptors and tachykinin receptor antagonists. JOURNAL OF AUTONOMIC PHARMACOLOGY 1993; 13:23-93. [PMID: 8382703 DOI: 10.1111/j.1474-8673.1993.tb00396.x] [Citation(s) in RCA: 516] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- C A Maggi
- Pharmacology and Chemistry Department, A. Menarini Pharmaceuticals, Florence, Italy
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Maggi CA, Giuliani S, Patacchini R, Quartara L, Rovero P, Renzetti AR, Mizrahi J, Giachetti A. Heterogeneity of tachykinin NK-2 receptors in rabbit, guinea-pig and human smooth muscles. Neuropeptides 1992; 23:181-6. [PMID: 1335134 DOI: 10.1016/0143-4179(92)90120-l] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Recent evidence indicates that the tachykinin NK-2 receptor is heterogenous (subtypes/species variants) and the existence of NK-2A (or 'non-classical') and NK-2B (or 'classical') forms of the NK-2 receptor in mammalian tissues has been proposed. In this study we have compared the affinities of 7 linear octa- and heptapeptide derivatives of neurokinin A (4-10) and that of two cyclic hexapeptides endowed with selective NK-2 receptor antagonist properties in 5 mammalian smooth muscle preparations previously characterized as expressing the NK-2A receptor subtype (rabbit pulmonary artery and bronchus, guinea-pig bronchus, human ileum and colon) and 2 preparations previously characterized as expressing the NK-2B receptor subtype (rat vas deferens and hamster trachea). The results of this comparative study reinforce the concept of two broad categories of preparations expressing pharmacologically distinguishable forms of the tachykinin NK-2 receptor and suggest the possibility of a further heterogeneity within the previously defined NK-2A receptor subtype.
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Affiliation(s)
- C A Maggi
- Department of Pharmacology, A. Menarini Pharmaceuticals, Florence, Italy
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Rovero P, Astolfi M, Manzini S, Jukic D, Rouissi N, Maggi CA, Regoli D. Structure-activity relationship study of R396, an NK2 tachykinin antagonist selective for the NK2B receptor subtype. Neuropeptides 1992; 23:143-5. [PMID: 1335133 DOI: 10.1016/0143-4179(92)90114-c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We report on a structure-activity study of R396 (Ac-Leu-Asp-Gln-Trp-Phe-Gly-NH2), a linear hexapeptide tachykinin antagonist selective for the putative NK2B receptor subtype. Asp2, Trp4 and the C-terminal glycinamide have been challenged by classical amino acid substitutions with the aim of elucidating the structural requirements responsible for NK2 subtype selectivity. The biological activities indicate that Asp2 has a crucial role for the high affinity of R396 at the NK2B subtype: none of the analogues substituted in position 2 display higher affinity as compared to R396, regardless of the nature of the residue introduced. Trp4 has been replaced by other aromatic residues, again yielding weak antagonist or inactive compounds. Finally, the C-terminal amide appears to be crucial for affinity, the free acid analogue being devoid of biological activity. On the other hand, antagonistic activity is maintained both by the desGly pentapeptide and by the analogue bearing beta Ala in place of Gly in position 6. In conclusion, since the NK2B selectivity pattern was maintained throughout the whole series of R396 replacement analogues, we speculate that the overall conformational features of this family of linear hexapeptides favour the interaction with the NK2B receptor subtype.
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Affiliation(s)
- P Rovero
- CNR, Istituto di Mutagenesi e Differenziamento, Pisa, Italy
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