RESUMO
The localization of substance P in brain regions that coordinate stress responses and receive convergent monoaminergic innervation suggested that substance P antagonists might have psychotherapeutic properties. Like clinically used antidepressant and anxiolytic drugs, substance P antagonists suppressed isolation-induced vocalizations in guinea pigs. In a placebo-controlled trial in patients with moderate to severe major depression, robust antidepressant effects of the substance P antagonist MK-869 were consistently observed. In preclinical studies, substance P antagonists did not interact with monoamine systems in the manner seen with established antidepressant drugs. These findings suggest that substance P may play an important role in psychiatric disorders.
Assuntos
Antidepressivos de Segunda Geração/uso terapêutico , Transtorno Depressivo/tratamento farmacológico , Morfolinas/uso terapêutico , Antagonistas dos Receptores de Neurocinina-1 , Substância P/antagonistas & inibidores , Adolescente , Adulto , Idoso , Tonsila do Cerebelo/efeitos dos fármacos , Tonsila do Cerebelo/metabolismo , Animais , Antidepressivos de Segunda Geração/efeitos adversos , Antidepressivos de Segunda Geração/metabolismo , Antidepressivos de Segunda Geração/farmacologia , Aprepitanto , Comportamento Animal/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Transtorno Depressivo/etiologia , Transtorno Depressivo/metabolismo , Feminino , Gerbillinae , Cobaias , Humanos , Masculino , Pessoa de Meia-Idade , Morfolinas/efeitos adversos , Morfolinas/metabolismo , Morfolinas/farmacologia , Norepinefrina/fisiologia , Paroxetina/uso terapêutico , Receptores da Neurocinina-1/metabolismo , Serotonina/fisiologia , Estresse Psicológico/tratamento farmacológico , Substância P/metabolismo , Vocalização Animal/efeitos dos fármacosRESUMO
The synthesis and biochemical evaluation of a series of spirofused indole oxazoline 5-HT3 antagonists is described in which the oxazoline ring acts as a bioisosteric replacement for esters and amides. The effect of substitution about the indole ring has shown the steric limitations of the aromatic binding site. Incorporation of a variety of azabicyclic systems within the rigid spirofused framework has allowed the definition of a binding model which incorporates a number of known antagonists and agonists. In this model steric constraints limit substitution around the indole ring although there is some bulk tolerance at the 1- and 2-positions. The importance of constraining the basic nitrogen within an azabicyclic system is underlined by comparison with the monocyclic piperidine. The highest affinity was observed for those compounds in which the basic nitrogen occupies a bridgehead position, the most potent analogue in this group being the azabicyclic [3.3.1] system (pIC50 = 8.95), suggesting lipophilic interactions may play a role in increasing affinity. A suggested model for agonist binding is included in which the basic nitrogens are superimposed and the 5-hydroxyl group of 5-HT is superimposed on the H-bond-accepting atom of the heterocyclic linking group.
Assuntos
Compostos Bicíclicos com Pontes/síntese química , Indóis/síntese química , Oxazóis/síntese química , Antagonistas da Serotonina/síntese química , Animais , Sítios de Ligação/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Compostos Bicíclicos com Pontes/metabolismo , Compostos Bicíclicos com Pontes/farmacologia , Indóis/metabolismo , Indóis/farmacologia , Ligantes , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Oxazóis/metabolismo , Oxazóis/farmacologia , Ratos , Antagonistas da Serotonina/metabolismo , Antagonistas da Serotonina/farmacologia , Estereoisomerismo , Relação Estrutura-Atividade , Difração de Raios XRESUMO
The synthesis and biochemical evaluation of a series of oxadiazole derivatives of imidazobenzodiazepines related to the benzodiazepine antagonist Ro 15-1788 (2a) are reported. Although the oxadiazole ring is seen as an isosteric replacement for the ester linkage, significant differences in structure-activity trends were observed. Specifically, oxadiazoles 9-12 invariably had increased receptor efficacy (as witnessed by measurements of the GABA shift) relative to the corresponding ester. Additionally, and in direct contrast to the classical agonists such as diazepam, affinity for the benzodiazepine receptor was enhanced by a 7- rather than 8-halo substituent. The results are discussed in terms of a six-point receptor-binding model originally based on the X-ray structure of 2a. For comparison, the crystal structures of two representative oxadiazole derivatives, 10h and 12o, having a 6-oxo and 6-phenyl group, respectively, were determined and the data incorporated into a modified binding model to account for the greater efficacy of these compounds. It is concluded that the antagonist behavior of 2a relies upon the hydrogen-bond-acceptor properties of the ester carbonyl oxygen whereas for the oxadiazole series this site is localized at the imidazole nitrogen.
Assuntos
Benzodiazepinas/síntese química , Oxidiazóis/síntese química , Receptores de GABA-A/efeitos dos fármacos , Animais , Benzodiazepinas/farmacologia , Membrana Celular/metabolismo , Córtex Cerebral/metabolismo , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Oxidiazóis/farmacologia , Ratos , Ratos Endogâmicos , Receptores de GABA-A/metabolismo , Relação Estrutura-Atividade , Difração de Raios XRESUMO
The synthesis and biochemical evaluation of a series of indole oxadiazole 5-HT3 antagonists are described. The key pharmacophoric elements have been defined as a basic nitrogen, a linking group capable of H-bonding interactions, and an aromatic moiety. The steric limitations of the aromatic binding site have been determined by substitution about the indole ring. Variation of the heterocyclic linking group has shown that while two hydrogen-bonding interactions are possible, only one is essential for high affinity. The environment of the basic nitrogen has been investigated and shown to be optimal when constrained within an azabicyclic system. These results have been incorporated into a proposed binding model for the 5-HT3 antagonist binding site, in which the optimum distance between the aromatic binding site and the basic amine is 8.4-8.9 A and the steric limitations are defined by van der Waals difference mapping.
Assuntos
Encéfalo/metabolismo , Indóis/síntese química , Oxidiazóis/síntese química , Receptores de Serotonina/efeitos dos fármacos , Antagonistas da Serotonina/síntese química , Animais , Ligação Competitiva , Membrana Celular/metabolismo , Córtex Cerebral/metabolismo , Eletroquímica , Indicadores e Reagentes , Indóis/química , Indóis/metabolismo , Indóis/farmacologia , Espectroscopia de Ressonância Magnética , Masculino , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Oxidiazóis/química , Oxidiazóis/farmacologia , Ratos , Ratos Endogâmicos , Receptores de Serotonina/metabolismo , Antagonistas da Serotonina/química , Antagonistas da Serotonina/farmacologia , Relação Estrutura-Atividade , TropizetronaRESUMO
As part of a program of screening the Merck sample collection, N-ethyl-L-tryptophan benzyl ester was identified as a weak antagonist at the substance P (NK1) receptor. Structure-activity studies showed that the indole ring system could be replaced by 3,4-dichlorophenyl, alpha- or beta-naphthyl, or benzthiophene with retention or only small loss of affinity. It was found that acylation of the tryptophan nitrogen gave compounds with higher affinity than N-ethyl or other basic amines. Optimization of substitution on the benzyl ester led to the identification of the 3,5-bis-(trifluoromethyl)benzyl ester of N-acetyl-L-tryptophan 26 as a potent and selective substance P receptor antagonist. Compound 26 blocked substance P induced dermal extravasation in vivo and was the most potent compound from this structurally novel class of antagonists which further adds to the diversity of small molecules that bind to the (NK1) receptor.
Assuntos
Antagonistas dos Receptores de Neurocinina-1 , Triptofano/análogos & derivados , Acilação , Sequência de Aminoácidos , Animais , Células CHO , Simulação por Computador , Cricetinae , Dermatite de Contato/prevenção & controle , Cobaias , Humanos , Masculino , Modelos Moleculares , Conformação Molecular , Dados de Sequência Molecular , Estrutura Molecular , Receptores da Neurocinina-1/metabolismo , Proteínas Recombinantes/metabolismo , Relação Estrutura-Atividade , Substância P/farmacologia , Triptofano/síntese química , Triptofano/farmacologiaRESUMO
The synthesis and in vitro and in vivo evaluation of a series of 3-(benzyloxy)-1-azabicyclo-[2.2.2]octane NK1 antagonists are described. While a number of 3,5-disubstituted benzyl ethers afford high affinity, the 3,5-bis(trifluoromethyl)benzyl was found to combine high in vitro affinity with good oral activity. Detailed structure-activity relationship studies in conjunction with data from molecular modeling and mutagenesis work have allowed the construction of a model of the pharmacophore. Specific interactions that have been identified include an interaction between His-197 and one of the rings of the benzhydryl, a lipophilic pocket containing His-265 that the benzyl ether occupies, and a possible hydrogen bond between Gln-165 and the oxygen of the benzyl ether.
Assuntos
Compostos Aza/síntese química , Compostos Aza/farmacologia , Compostos Bicíclicos Heterocíclicos com Pontes/síntese química , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Antagonistas dos Receptores de Neurocinina-1 , Animais , Compostos Aza/química , Sítios de Ligação , Compostos Bicíclicos Heterocíclicos com Pontes/química , Cristalografia por Raios X , Cobaias , Humanos , Masculino , Modelos Moleculares , Conformação Molecular , Mutagênese , Relação Estrutura-AtividadeRESUMO
1-(5-[[(2R,3S)-2-([(1R)-1-[3,5-Bis(trifluoromethyl)phenyl]ethyl]oxy)-3-(4-fluorophenyl)morpholin-4-yl]methyl]-2H-1,2,3-triazol-4-yl)-N,N-dimethylmethanamine hydrochloride 3 is a high affinity, orally active, h-NK(1) receptor antagonist with a long central duration of action and a solubility in water of >100 mg/mL. The construction of the 5-dimethylaminomethyl 1,2,3-triazol-4-yl unit, which incorporates the solubilizing group of 3, was accomplished by thermal rearrangement of a propargylic azide in the presence of dimethylamine. Compound 3 is highly effective in pre-clinical tests that are relevant to clinical efficacy in emesis and depression.
Assuntos
Antidepressivos/síntese química , Antieméticos/síntese química , Morfolinas/síntese química , Antagonistas dos Receptores de Neurocinina-1 , Triazóis/síntese química , Administração Oral , Aminas/síntese química , Aminas/química , Aminas/farmacologia , Animais , Animais Recém-Nascidos , Antidepressivos/química , Antidepressivos/farmacologia , Antieméticos/química , Antieméticos/farmacologia , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Cães , Furões , Gerbillinae , Cobaias , Técnicas In Vitro , Injeções Intravenosas , Macaca mulatta , Morfolinas/química , Morfolinas/farmacologia , Ensaio Radioligante , Ratos , Solubilidade , Relação Estrutura-Atividade , Triazóis/química , Triazóis/farmacologia , Vocalização Animal/efeitos dos fármacosRESUMO
Previously reported studies from these laboratories described the design of a novel series of high-affinity NK1 antagonists based on the 4,4-disubstituted piperidine ring system. Further structure-activity studies have now established that for high NK1 affinity the benzyl ether side chain must be 3,5-disubstituted and highly lipophilic, the optimal side chain being the 3, 5-bis(trifluoromethyl)benzyl ether, 12 (hNK1 IC50 = 0.95 nM). Additional studies have shown that this class of NK1 antagonist tolerates a wider range of substituents on the piperidine nitrogen, including acyl (38) (hNK1 IC50 = 5.3 nM) and sulfonyl (39) (hNK1 IC50 = 5.7 nM) derivatives. Following preliminary pharmacokinetic analysis, two compounds (32 and 43) were selected for in vivo study in the resiniferotoxin-induced vascular leakage model, both showing excellent profiles (ID50 = 0.22 and 0.28 mg/kg, respectively).
Assuntos
Antagonistas dos Receptores de Neurocinina-1 , Piperidinas/síntese química , Pirrolidinas/síntese química , Tiazóis/síntese química , Animais , Células CHO , Permeabilidade Capilar/efeitos dos fármacos , Cricetinae , Diterpenos/toxicidade , Esôfago/irrigação sanguínea , Esôfago/efeitos dos fármacos , Cobaias , Fosfatos de Inositol/metabolismo , Masculino , Piperidinas/farmacocinética , Piperidinas/farmacologia , Pirrolidinas/farmacocinética , Pirrolidinas/farmacologia , Ensaio Radioligante , Receptores da Neurocinina-1/biossíntese , Relação Estrutura-Atividade , Tiazóis/farmacocinéticaRESUMO
The preparation of a series of N-heteroarylpiperidine ether-based human NK1 antagonists is described. Two of the compounds 3-[-(2S,3S)-3-(((3,5-bis(trifluoromethyl)phenyl)methyl)oxy)- 2-phenylpiperidino}methyl]-1,2,4-triazole (11) and 5-[¿(2S,3S)-3-(((3,5-bis(trifluoromethyl)-phenyl)methyl)oxy)-2- phenylpiperidino}methyl]-3-oxo-1,2,4-triazolone (12)), in particular, are orally bioavailable and exhibited significant improvements in potency, both in vitro and in vivo, over the lead (carboxamidomethyl)piperidine ether 1. Rat liver microsome studies on a selected number of compounds from this series show the triazolone heterocycle to be considerably more stable than the others. Furthermore, both 11 and 12 have been profiled in a number of assays that may be predictive of the clinical utility of substance P antagonists.
Assuntos
Antagonistas dos Receptores de Neurocinina-1 , Piperidinas/síntese química , Triazóis/síntese química , Animais , Disponibilidade Biológica , Estabilidade de Medicamentos , Furões , Cobaias , Humanos , Inflamação/tratamento farmacológico , Macaca mulatta , Masculino , Microssomos Hepáticos/metabolismo , Transtornos de Enxaqueca/tratamento farmacológico , Piperidinas/metabolismo , Piperidinas/uso terapêutico , Ratos , Receptores da Neurocinina-1/metabolismo , Triazóis/metabolismo , Triazóis/uso terapêutico , Vômito/tratamento farmacológicoRESUMO
The mechanism of action of conventional antidepressants (e.g. imipramine) has been linked to modulation of central monoamine systems. Substance P (NK1) receptor antagonists may have antidepressant and anxiolytic effects in patients with major depressive disorder and high anxiety but, unlike conventional antidepressants, are independent of activity at monoamine reuptake sites, transporters, receptors, or monoamine oxidase. To investigate the possibility that substance P receptor antagonists influence central monoamine systems indirectly, we have compared the effects of chronic administration of imipramine with that of the substance P receptor antagonist L-760735 on the spontaneous firing activity of locus coeruleus neurones. Electrophysiological recordings were made from brain slices prepared from guinea-pigs that had been dosed orally every day for 4 weeks with either L-760735 (3 mg/kg), imipramine (10 mg/kg), or vehicle (water), or naive animals. Chronic, but not acute, treatment with the substance P receptor antagonist L-760735, induced burst firing of neurones in the locus coeruleus. This effect resembles that of the conventional antidepressant imipramine. However, their effects are dissociable since, in contrast to chronic imipramine treatment, chronic L-760735 treatment does not cause functional desensitisation of somatic alpha2 adrenoceptors. The mechanism by which chronic substance P receptor antagonist or conventional antidepressant treatment influences the pattern of firing activity of norepinephrine neurones remains to be elucidated. However, an indirect action in the periphery or distant brain nuclei has been excluded by the use of the in vitro slice preparation, suggesting a local site of action in the locus coeruleus.
Assuntos
Potenciais de Ação/efeitos dos fármacos , Ansiolíticos/farmacologia , Antidepressivos Tricíclicos/farmacologia , Locus Cerúleo/efeitos dos fármacos , Morfolinas/farmacologia , Antagonistas dos Receptores de Neurocinina-1 , Neurônios/efeitos dos fármacos , Norepinefrina/metabolismo , Potenciais de Ação/fisiologia , Agonistas de Receptores Adrenérgicos alfa 2 , Antagonistas de Receptores Adrenérgicos alfa 2 , Animais , Animais Recém-Nascidos , Esquema de Medicação , Cobaias , Locus Cerúleo/metabolismo , Masculino , Neurônios/metabolismo , Receptores Adrenérgicos alfa 2/metabolismo , Receptores da Neurocinina-1/agonistas , Receptores da Neurocinina-1/metabolismoRESUMO
1 The ability of a series of 17 isatogen derivatives to relax smooth muscle, inhibit adenosine 5'-diphosphate (ADP)-stimulated respiration in isolated mitochondria and to antagonize the inhibitory effects of adenosine 5'-triphosphate (ATP) on smooth muscle was measured. 2 Substitution in the 4- and 7-positions of the A-ring gave compounds that were strong inhibitors of mitochondrial ATP synthesis and potent, non-specific smooth muscle relaxants. The compounds also possessed ATP-receptor blocking activity. 3 Substitution in the 5- and 6-positions of the A-ring decreased both the relaxant effect on smooth muscle and inhibition of ATP synthesis, whilst enhancing ATP-receptor antagonism. 4 In a series of 6-substituted 2-phenylisatogens, 6-methoxy-2-phenylisatogen was the most effective ATP-receptor antagonist. This compound also showed the greatest separation of the desired pharmacological activity (ATP-receptor blockade) from the other two activities (smooth muscle relaxation and inhibition of mitochondrial ATP synthesis).
Assuntos
Trifosfato de Adenosina/antagonistas & inibidores , Indóis/farmacologia , Isatina/farmacologia , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Trifosfato de Adenosina/biossíntese , Animais , Ceco/efeitos dos fármacos , Fenômenos Químicos , Química , Feminino , Cobaias , Técnicas In Vitro , Isatina/análogos & derivados , Mitocôndrias Musculares/metabolismo , Relaxamento Muscular/efeitos dos fármacos , Relação Estrutura-AtividadeRESUMO
[structure: see text]. Complementary stereoselective syntheses of individual C3 epimers of the NK-1 receptor antagonist precursor 1 have been developed. Both diastereomers were derived from the common intermediate 3; introduction of the 3S stereocenter in 1a was achieved through hydrogenation of an arylated dihydrofuran, whereas the corresponding stereogenic center in 1b was installed using a stereo- and regioselective alkene hydroarylation.
Assuntos
Compostos Aza/síntese química , Compostos Aza/farmacologia , Antagonistas dos Receptores de Neurocinina-1 , Compostos de Espiro/síntese química , Compostos de Espiro/farmacologia , Cromatografia Líquida de Alta Pressão , Ligantes , Espectroscopia de Ressonância Magnética , EstereoisomerismoRESUMO
The ability of tachykinin NK1 receptor antagonists to inhibit GR73632 (D-Ala-[L-Pro9,Me-Leu8]substance P-(7-11))-induced foot tapping in gerbils was employed as an indirect measure of brain penetration and this was compared with their ability to prevent acute emesis induced by cisplatin in ferrets. (+)-GR203040 ((2S,3S and 2R,3R)-2-methoxy-5-tetrazol-1-yl-benzyl-(2-phenyl-piperidin- 3-yl)-amine), CP-99,994 ((2S,3S)-cis-3-(2-methoxybenzylamino)-2-phenyl piperidine) dihydrochloride), and L-742,694 (2-(S)-(3,5-bis(trifluoromethyl)benzyloxy)-3-(S)-phenyl-4-(5-(3-oxo-1,2, 4-triazolo)methylmorpholine) potently inhibited GR73632-induced foot tapping (ID50 < or = 0.85 mg/kg), and acute retching induced by cisplatin (ID50 < or = 0.18 mg/kg). RPR100893 ((3aS,4S,7aS)-7,7-diphenyl-4-(2-methoxyphenyl)-2-[(S)-2-(2-m ethoxyphenyl)proprionyl] perhydroisoindol-4-ol) was not a potent antagonist of retching (ID50 4.1 mg/kg) or foot tapping (ID50 > 10 mg/kg). High doses (3-10 mg/kg) of CGP49823 ((2R,4S)-2-benzyl-1-(3,5-dimethylbenzoyl)-N-[(4-quinolinyl)methyl] -4-piperineamine) dihydrochloride), FK888 (N2-[(4R)-4-hydroxy-1-(1-methyl-1H-indol-3-yl)carbonyl-L-propyl]-N-methy l-N-phenylmethyl-L-3-(2-naphthyl)-alaninamide), and LY303870 ((R)-1-[N-(2-methoxybenzyl)acetylamino]-3-(1H-indol-3-yl)-2-[N-(2-(4-(pi peridinyl)piperidin-1-yl)acetyl)amino]propane) were required to inhibit foot tapping; these agents were not anti-emetic in this dose range. SR140333 ((S)-1-[2-[3-(3,4-dichlorphenyl)-1 (3-isopropoxyphenylacetyl)piperidin-3-yl] ethyl]-4-phenyl-1 azaniabicyclo [2.2.2]octane; 3-10 mg/kg) failed to inhibit foot tapping or emesis. Affinities for the human and ferret tachykinin NK1 receptor were highly correlated (r = 0.93, P = 0.0008). Inhibition of foot tapping in gerbils, but not NK1 receptor binding affinity, predicted anti-emetic activity in ferrets (r = 0.75, P < 0.01). These findings confirm that the anti-emetic activity of tachykinin NK1 receptor antagonists is dependent on brain penetration.
Assuntos
Antieméticos/farmacologia , Antagonistas dos Receptores de Neurocinina-1 , Fragmentos de Peptídeos/antagonistas & inibidores , Substância P/análogos & derivados , Administração Oral , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Células CHO , Cisplatino/antagonistas & inibidores , Clonagem Molecular , Cricetinae , Furões , Gerbillinae , Humanos , Infusões Intravenosas , Membranas/efeitos dos fármacos , Membranas/metabolismo , Ensaio Radioligante , Substância P/antagonistas & inibidores , Substância P/metabolismoAssuntos
Química Encefálica/efeitos dos fármacos , Indóis/farmacologia , Receptores de Serotonina/metabolismo , Antagonistas da Serotonina/farmacologia , Animais , Ligação Competitiva/efeitos dos fármacos , Técnicas In Vitro , Masculino , Ratos , Ratos Endogâmicos , Receptores de Serotonina/efeitos dos fármacos , Tropanos/farmacologia , TropizetronaRESUMO
Based on single residue substitutions, previous studies suggested that Gln165, His197, and His265 of the neurokinin-1 receptor interact directly with many nonpeptide antagonists, including CP-96,345. To further test this model, all three residues have been substituted simultaneously with alanine. The Q165A-H197A-H265A triple mutant bound CP-96,345 and eight analogs with similar affinity (2-20 microM), even though the same series of compounds bound to the wild-type receptor with affinities over a range of 1000-fold. These observations correspond exactly to the prediction of the binding site model. The micromolar binding affinity of all tested CP-96,345 analogs for the triple mutant seems to reflect solely van der Waals interactions, which suggests a significant contribution of conformational compatibility (or shape complementarity) to binding affinity. The primary role of conformational compatibility in ligand binding was consistent with the observation that simply transferring the residues involved in polar interactions with beta2-agonists into the neurokinin-1 receptor did not lead to increased binding affinity for the beta2-agonists. Taken together, these results support a general principle of ligand-receptor binding in which specific polar interactions can take place only if the overall ligand conformation is compatible with the stereochemistry of the binding pocket. In addition, double-residue and triple-residue substitutions, in combination with single-residue substitutions, can provide an alternative route to reveal multiple interactions that may not be detectable by single-residue substitutions and represent a novel approach to examine ligand-receptor interactions in the absence of high-resolution structural data.
Assuntos
Antagonistas dos Receptores de Neurocinina-1 , Sequência de Aminoácidos , Animais , Células COS , Cricetinae , Humanos , Conformação Molecular , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Ligação Proteica , Receptores da Neurocinina-1/genética , Receptores da Neurocinina-1/metabolismo , Homologia de Sequência de AminoácidosRESUMO
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.
Assuntos
Compostos de Bifenilo/farmacologia , Glutamina/metabolismo , Piperidinas/farmacologia , Quinuclidinas/antagonistas & inibidores , Quinuclidinas/farmacologia , Receptores da Neurocinina-1/metabolismo , Sequência de Aminoácidos , Compostos de Bifenilo/metabolismo , Membrana Celular/metabolismo , Células Cultivadas , Humanos , Ligação de Hidrogênio , Indóis/metabolismo , Indóis/farmacologia , Isoindóis , Dados de Sequência Molecular , Antagonistas dos Receptores de Neurocinina-1 , Piperidinas/metabolismo , Conformação Proteica , Quinuclidinas/metabolismo , Receptores da Neurocinina-1/químicaRESUMO
Previous studies suggested that the antagonist binding site in the neurokinin-1 receptor is composed of phylogenetically conserved residues, while phylogenetically divergent residues affect the conformation of the binding site. To test this hypothesis, we investigated the role of conserved residues in antagonist binding. Histidine 197 in the human receptor was found to interact with CP-96,345 but not RP67580. In addition, a nearby residue, histidine 265 of the human receptor, is required for the binding of RP67580 but not CP-96,345 or substance P. The interaction between residue 265 and RP67580 is consistent with a hydrogen bonding interaction. Analysis of several analogs of CP-96,345 revealed that histidine 265 of the human receptor is in proximity to the substituted benzyl moiety of CP-96,345, and can interact with other analogs of CP-96,345. In contrast to the human neurokinin-1 receptor, both histidine 197 and histidine 265 in the rat neurokinin-1 receptor appear to interact with both CP-96,345 and RP67580. These results support a conformational difference between the antagonist binding sites of the rat and human neurokinin-1 receptors and provide a model for examining specific interactions between antagonists and the receptor.
Assuntos
Compostos de Bifenilo/metabolismo , Histidina , Indóis/metabolismo , Conformação Proteica , Receptores da Neurocinina-1/química , Receptores da Neurocinina-1/metabolismo , Sequência de Aminoácidos , Analgésicos/metabolismo , Animais , Sítios de Ligação , Linhagem Celular , Sequência Conservada , Humanos , Ligação de Hidrogênio , Hipnóticos e Sedativos/metabolismo , Isoindóis , Modelos Moleculares , Mutagênese Sítio-Dirigida , Antagonistas dos Receptores de Neurocinina-1 , Mutação Puntual , Ratos , Relação Estrutura-Atividade , TransfecçãoRESUMO
Heterocyclic replacements for the carboxamido group of the previously disclosed phenylglycinol-based human NK1 (hNK1) receptor antagonists have been investigated, ultimately leading to acyclic compounds with sub-nanomolar affinity for the hNK1 receptor.