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1.
Nat Commun ; 15(1): 2533, 2024 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-38514618

RESUMO

Small-molecule modulators of diverse voltage-gated K+ (Kv) channels may help treat a wide range of neurological disorders. However, developing effective modulators requires understanding of their mechanism of action. We apply an orthogonal approach to elucidate the mechanism of action of an imidazolidinedione derivative (AUT5), a highly selective positive allosteric modulator of Kv3.1 and Kv3.2 channels. AUT5 modulation involves positive cooperativity and preferential stabilization of the open state. The cryo-EM structure of the Kv3.1/AUT5 complex at a resolution of 2.5 Å reveals four equivalent AUT5 binding sites at the extracellular inter-subunit interface between the voltage-sensing and pore domains of the channel's tetrameric assembly. Furthermore, we show that the unique extracellular turret regions of Kv3.1 and Kv3.2 essentially govern the selective positive modulation by AUT5. High-resolution apo and bound structures of Kv3.1 demonstrate how AUT5 binding promotes turret rearrangements and interactions with the voltage-sensing domain to favor the open conformation.


Assuntos
Canais de Potássio Shaw , Sítios de Ligação , Canais de Potássio Shaw/metabolismo
2.
Cell Rep Med ; 5(2): 101389, 2024 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-38266642

RESUMO

The recurrent variant KCNC1-p.Arg320His causes progressive myoclonus epilepsy (EPM) type 7, defined by progressive myoclonus, epilepsy, and ataxia, and is without effective treatment. KCNC1 encodes the voltage-gated potassium channel subunit Kv3.1, specifically expressed in high-frequency-firing neurons. Variant subunits act via loss of function; hence, EPM7 pathogenesis may involve impaired excitability of Kv3.1-expressing neurons, while enhancing Kv3 activity could represent a viable therapeutic strategy. We generate a mouse model, Kcnc1-p.Arg320His/+, which recapitulates the core features of EPM7, including progressive ataxia and seizure susceptibility. Kv3.1-expressing cerebellar granule cells and neocortical parvalbumin-positive GABAergic interneurons exhibit abnormalities consistent with Kv3 channel dysfunction. A Kv3-specific positive modulator (AUT00206) selectively enhances the firing frequency of Kv3.1-expressing neurons and improves motor function and seizure susceptibility in Kcnc1-Arg320His/+ mice. This work identifies a cellular and circuit basis of dysfunction in EPM7 and demonstrates that Kv3 positive modulators such as AUT00206 have therapeutic potential for the treatment of EPM7.


Assuntos
Epilepsias Mioclônicas Progressivas , Camundongos , Animais , Epilepsias Mioclônicas Progressivas/genética , Ataxia/genética , Convulsões/genética , Neurônios , Encéfalo
4.
Brain Neurosci Adv ; 6: 23982128221086464, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35359460

RESUMO

Synapse loss is associated with cognitive decline in Alzheimer's disease, and owing to their plastic nature, synapses are an ideal target for therapeutic intervention. Oligomeric amyloid beta around amyloid plaques is known to contribute to synapse loss in mouse models and is associated with synapse loss in human Alzheimer's disease brain tissue, but the mechanisms leading from Aß to synapse loss remain unclear. Recent data suggest that the fast-activating and -inactivating voltage-gated potassium channel subtype 3.4 (Kv3.4) may play a role in Aß-mediated neurotoxicity. Here, we tested whether this channel could also be involved in Aß synaptotoxicity. Using adeno-associated virus and clustered regularly interspaced short palindromic repeats technology, we reduced Kv3.4 expression in neurons of the somatosensory cortex of APP/PS1 mice. These mice express human familial Alzheimer's disease-associated mutations in amyloid precursor protein and presenilin-1 and develop amyloid plaques and plaque-associated synapse loss similar to that observed in Alzheimer's disease brain. We observe that reducing Kv3.4 levels ameliorates dendritic spine loss and changes spine morphology compared to control virus. In support of translational relevance, Kv3.4 protein was observed in human Alzheimer's disease and control brain and is associated with synapses in human induced pluripotent stem cell-derived cortical neurons. We also noted morphological changes in induced pluripotent stem cell neurones challenged with human Alzheimer's disease-derived brain homogenate containing Aß but, in this in vitro model, total mRNA levels of Kv3.4 were found to be reduced, perhaps as an early compensatory mechanism for Aß-induced damage. Overall, our results suggest that approaches to reduce Kv3.4 expression and/or function in the Alzheimer's disease brain could be protective against Aß-induced synaptic alterations.

5.
Bioorg Med Chem Lett ; 22(7): 2620-3, 2012 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-22366657

RESUMO

A series of novel benzimidazoles are discussed as NR2B-selective N-methyl-d-aspartate (NMDA) receptor antagonists. High throughput screening (HTS) efforts identified a number of potent and selective NR2B antagonists such as 1. Exploration of the substituents around the core of this template identified a number of compounds with high potency for NR2B (pIC(50) >7) and good selectivity against the NR2A subunit (pIC(50) <4.3) as defined by FLIPR-Ca(2+) and radioligand binding studies. These agents offer potential for the development of therapeutics for a range of nervous system disorders including chronic pain, neurodegeneration, migraine and major depression.


Assuntos
Analgésicos/síntese química , Antidepressivos/síntese química , Benzimidazóis/síntese química , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Analgésicos/farmacologia , Antidepressivos/farmacologia , Benzimidazóis/farmacologia , Descoberta de Drogas , Ensaios de Triagem em Larga Escala , Humanos , Técnicas de Patch-Clamp , Ensaio Radioligante , Receptores de N-Metil-D-Aspartato/metabolismo , Relação Estrutura-Atividade
6.
Epilepsia ; 53(3): 425-36, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22221318

RESUMO

Retigabine [RTG (international nonproprietary name); ezogabine (EZG; U.S. adopted name)] is a first-in-class antiepileptic drug (AED) that reduces neuronal excitability by enhancing the activity of KCNQ (K(v)7) potassium (K(+)) channels. RTG/EZG has recently been approved by the European Medicines Agency and the U.S. Food and Drug Administration as adjunctive therapy in adults with partial-onset seizures. In this review we discuss the activity that RTG/EZG has demonstrated across a broad spectrum of in vitro/in vivo animal models of seizures, including generalized tonic-clonic, primary generalized (absence), and partial seizures, in addition to the compound's ability to resist and block the occurrence of seizures induced by a range of stimuli across different regions of the brain. The potency of RTG/EZG in models refractory to several conventional AEDs and the work done to assess antiepileptogenesis and neuroprotection are discussed. Studies that have evaluated the central nervous system side effects of RTG/EZG in animals are reviewed in order to compare these effects with adverse events observed in patients with epilepsy. Based on its demonstrated effect in a number of animal epilepsy models, the synergistic and additive activity of RTG/EZG with other AEDs supports its potential use in therapeutic combinations for different seizure types. The distinct mechanism of action of RTG/EZG from those of currently available AEDs, along with its broad preclinical activity, underscores the key role of KCNQ (K(v)7) K(+) channels in neuronal excitability, and further supports the potential efficacy of this unique molecule in the treatment of epilepsy.


Assuntos
Anticonvulsivantes/farmacologia , Carbamatos/farmacologia , Modelos Animais de Doenças , Epilepsia/tratamento farmacológico , Fenilenodiaminas/farmacologia , Animais , Anticonvulsivantes/efeitos adversos , Anticonvulsivantes/uso terapêutico , Carbamatos/efeitos adversos , Carbamatos/uso terapêutico , Sinergismo Farmacológico , Epilepsia/classificação , Humanos , Canais de Potássio KCNQ/agonistas , Canais de Potássio KCNQ/fisiologia , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Fenilenodiaminas/efeitos adversos , Fenilenodiaminas/uso terapêutico , Resultado do Tratamento
7.
Epilepsia ; 53(3): 412-24, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22220513

RESUMO

The pharmacologic profile of retigabine [RTG (international nonproprietary name); ezogabine, EZG (U.S. adopted name)], is different from all currently approved antiepileptic drugs (AEDs). Its primary mechanism of action (MoA) as a positive allosteric modulator of KCNQ2-5 (K(v) 7.2-7.5) ion channels defines RTG/EZG as the first neuronal potassium (K(+)) channel opener for the treatment of epilepsy. KCNQ2-5 channels are predominantly expressed in neurons and are important determinants of cellular excitability, as indicated by the occurrence of human genetic mutations in KCNQ channels that underlie inheritable disorders including, in the case of KCNQ2/3, the syndrome of benign familial neonatal convulsions. In vitro pharmacologic studies demonstrate that the most potent action of RTG/EZG is at KCNQ2-5 channels, particularly heteromeric KCNQ2/3. Furthermore, mutagenesis and modeling studies have pinpointed the RTG/EZG binding site to a hydrophobic pocket near the channel gate, indicating how RTG/EZG can stabilize the open form of KCNQ2-5 channels; the absence of this site in KCNQ1 also provides a clear explanation for the inbuilt selectivity RTG/EZG has for potassium channels other than the KCNQ cardiac channel. KCNQ channels are active at the normal cell resting membrane potential (RMP) and contribute a continual hyperpolarizing influence that stabilizes cellular excitability. The MoA of RTG/EZG increases the number of KCNQ channels that are open at rest and also primes the cell to retort with a larger, more rapid, and more prolonged response to membrane depolarization or increased neuronal excitability. In this way, RTG/EZG amplifies this natural inhibitory force in the brain, acting like a brake to prevent the high levels of neuronal action potential burst firing (epileptiform activity) that may accompany sustained depolarizations associated with the initiation and propagation of seizures. This action to restore physiologic levels of neuronal activity is thought to underlie the efficacy of RTG/EZG as an anticonvulsant in a broad spectrum of preclinical seizure models and in placebo-controlled trials in patients with partial epilepsy. In this article, we consider the pharmacologic characteristics of RTG/EZG at the receptor, cellular, and network levels as a means of understanding the novel and efficacious MoA of this new AED as defined in both preclinical and clinical research.


Assuntos
Anticonvulsivantes/farmacologia , Carbamatos/farmacologia , Epilepsia/tratamento farmacológico , Canais de Potássio KCNQ/agonistas , Fenilenodiaminas/farmacologia , Animais , Anticonvulsivantes/uso terapêutico , Carbamatos/uso terapêutico , Epilepsia/fisiopatologia , Humanos , Canais de Potássio KCNQ/genética , Canais de Potássio KCNQ/metabolismo , Fenilenodiaminas/uso terapêutico , Ratos , Resultado do Tratamento
8.
Mol Cell Neurosci ; 48(1): 51-61, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21708262

RESUMO

Exposure to intense sound can cause damage to the delicate sensory and neuronal components of the cochlea leading to hearing loss. Such damage often causes the dendrites of the spiral ganglion neurons (SGN), the neurons that provide the afferent innervation of the hair cells, to swell and degenerate thus damaging the synapse. In models of neuropathic pain, axotomy, another form of afferent nerve damage, is accompanied by altered voltage-gated sodium channel (VGSC) expression, leading to neuronal hyperactivity. In this study, adult Wistar rats were exposed to noise which produced a mild, 20 dB hearing threshold elevation and their VGSC expression was investigated. Quantitative PCR showed decreased Na(V)1.1 and Na(V)1.6 mRNA expression in the SGN following noise exposure (29% and 56% decrease respectively) while Na(V)1.7 mRNA expression increased by approximately 20% when compared to control rats. Immunohistochemistry extended these findings, revealing increased staining for Na(V)1.1 along the SGN dendrites and Na(V)1.7 in the cell bodies after noise. These results provide the first evidence for selective changes in VGSC expression following moderate noise-induced hearing loss and could contribute to elevated hearing thresholds and to the generation of perceptual anomalies commonly associated with cochlear damage, such as tinnitus and hyperacusis.


Assuntos
Células Ciliadas Auditivas/fisiologia , Perda Auditiva Provocada por Ruído/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Plasticidade Neuronal/fisiologia , Neurônios Aferentes/fisiologia , Canais de Sódio/metabolismo , Animais , Limiar Auditivo/fisiologia , Cóclea/citologia , Cóclea/patologia , Cóclea/fisiologia , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Células Ciliadas Auditivas/citologia , Perda Auditiva Provocada por Ruído/patologia , Humanos , Masculino , Canal de Sódio Disparado por Voltagem NAV1.1 , Canal de Sódio Disparado por Voltagem NAV1.6 , Canal de Sódio Disparado por Voltagem NAV1.7 , Proteínas do Tecido Nervoso/genética , Neurônios Aferentes/citologia , Ratos , Ratos Wistar , Canais de Sódio/genética , Gânglio Espiral da Cóclea/citologia
9.
J Pharmacol Exp Ther ; 338(1): 100-13, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21487071

RESUMO

Sodium channel inhibition is a well precedented mechanism used to treat epilepsy and other hyperexcitability disorders. The established sodium channel blocker and broad-spectrum anticonvulsant lamotrigine is also effective in the treatment of bipolar disorder and has been evaluated in patients with schizophrenia. Double-blind placebo-controlled clinical trials found that the drug has potential to reduce cognitive symptoms of the disorder. However, because of compound-related side-effects and the need for dose titration, a conclusive evaluation of the drug's efficacy in patients with schizophrenia has not been possible. (5R)-5-(4-{[(2-Fluorophenyl)methyl]oxy}phenyl)-l-prolinamide (GSK2) and (2R,5R)-2-(4-{[(2-fluorophenyl)methyl]oxy}phenyl)-7-methyl-1,7-diazaspiro[4.4]nonan-6-one (GSK3) are two new structurally diverse sodium channel blockers with potent anticonvulsant activity. In this series of studies in the rat, we compared the efficacy of the two new molecules to prevent a cognitive deficit induced by the N-methyl-d-aspartic acid receptor antagonist phencyclidine (PCP) in the reversal-learning paradigm in the rat. We also explored the effects of the drugs to prevent brain activation and neurochemical effects of PCP. We found that, like lamotrigine, both GSK2 and GSK3 were able to prevent the deficit in reversal learning produced by PCP, thus confirming their potential in the treatment of cognitive symptoms of schizophrenia. However, higher doses than those required for anticonvulsant efficacy of the drugs were needed for activity in the reversal-learning model, suggesting a lower therapeutic window relative to mechanism-dependent central side effects for this indication.


Assuntos
Transtornos Cognitivos/induzido quimicamente , Transtornos Cognitivos/prevenção & controle , Fenciclidina/toxicidade , Esquizofrenia/induzido quimicamente , Esquizofrenia/prevenção & controle , Bloqueadores dos Canais de Sódio/uso terapêutico , Animais , Feminino , Masculino , Ratos , Ratos Sprague-Dawley , Reversão de Aprendizagem/efeitos dos fármacos , Reversão de Aprendizagem/fisiologia , Bloqueadores dos Canais de Sódio/farmacologia , Resultado do Tratamento
10.
J Immunol ; 183(5): 3454-62, 2009 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-19648266

RESUMO

Prolonged Ca(2+) entry through Ca(2+) release-activated Ca(2+) (CRAC) channels is crucial in activating the Ca(2+)-sensitive transcription factor NFAT, which is responsible for directing T cell proliferation and cytokine gene expression. To establish whether targeting CRAC might counteract intestinal inflammation, we evaluated the in vitro effect of a selective CRAC inhibitor on T cell cytokine production and T-bet expression by lamina propria mononuclear cells (LPMC) and biopsy specimens from inflammatory bowel disease (IBD) patients. The inhibitory activity of the CRAC blocker was investigated through patch-clamp experiments on rat basophilic leukemia cells and fluorometric imaging plate reader intracellular Ca(2+) assays using thapsigargin-stimulated Jurkat T cells and its detailed selectivity profile defined using a range of in vitro radioligand binding and functional assays. Anti-CD3/CD28-stimulated LPMC and biopsy specimens from 51 patients with IBD were cultured with a range of CRAC inhibitor concentrations (0.01-10 microM). IFN-gamma, IL-2, IL-8, and IL-17 were analyzed by ELISA. T-bet was determined by immunoblotting. We found that the CRAC blocker concentration-dependently inhibited CRAC current in rat basophilic leukemia cells and thapsigargin-induced Ca(2+) influx in Jurkat T cells. A concentration-dependent reduction in T-bet expression and production of IFN-gamma, IL-2, IL-17, but not IL-8, was observed in IBD LPMC and biopsy specimens treated with the CRAC inhibitor. In conclusion, we provide evidence that the suppression of CRAC channel function may dampen the increased T cell response in the inflamed gut, thus suggesting a promising role for CRAC inhibitor drugs in the therapeutic management of patients with IBD.


Assuntos
Canais de Cálcio/metabolismo , Citocinas/antagonistas & inibidores , Citocinas/biossíntese , Doenças Inflamatórias Intestinais/imunologia , Doenças Inflamatórias Intestinais/patologia , Proteínas com Domínio T/antagonistas & inibidores , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Adulto , Idoso , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Linhagem Celular Tumoral , Humanos , Doenças Inflamatórias Intestinais/metabolismo , Mucosa Intestinal/imunologia , Mucosa Intestinal/metabolismo , Mucosa Intestinal/patologia , Células Jurkat , Pessoa de Meia-Idade , Técnicas de Cultura de Órgãos , Técnicas de Patch-Clamp , Ratos , Proteínas com Domínio T/fisiologia , Subpopulações de Linfócitos T/patologia , Adulto Jovem
11.
Br J Pharmacol ; 157(8): 1301-17, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19594762

RESUMO

N-methyl-D-aspartate receptors (NMDARs) are ion channels gated by glutamate, the major excitatory neurotransmitter in the mammalian central nervous system (CNS). They are widespread in the CNS and are involved in numerous physiological and pathological processes including synaptic plasticity, chronic pain and psychosis. Aberrant NMDAR activity also plays an important role in the neuronal loss associated with ischaemic insults and major degenerative disorders including Parkinson's and Alzheimer's disease. Agents that target and alter NMDAR function may, thus, have therapeutic benefit. Interestingly, NMDARs are endowed with multiple extracellular regulatory sites that recognize ions or small molecule ligands, some of which are likely to regulate receptor function in vivo. These allosteric sites, which differ from agonist-binding and channel-permeation sites, provide means to modulate, either positively or negatively, NMDAR activity. The present review focuses on allosteric modulation of NMDARs containing the NR2B subunit. Indeed, the NR2B subunit confers a particularly rich pharmacology with distinct recognition sites for exogenous and endogenous allosteric ligands. Moreover, NR2B-containing receptors, compared with other NMDAR subtypes, appear to contribute preferentially to pathological processes linked to overexcitation of glutamatergic pathways. The actions of extracellular H+, Mg2+, Zn2+, of polyamines and neurosteroids, and of the synthetic compounds ifenprodil and derivatives ('prodils') are presented. Particular emphasis is put upon the structural determinants and molecular mechanisms that underlie the effects exerted by these agents. A better understanding of how NR2B-containing NMDARs (and NMDARs in general) operate and how they can be modulated should help define new strategies to counteract the deleterious effects of dysregulated NMDAR activity.


Assuntos
Receptores de N-Metil-D-Aspartato/fisiologia , Regulação Alostérica , Sítio Alostérico , Animais , Encefalopatias/tratamento farmacológico , Encefalopatias/metabolismo , Transtorno Depressivo Maior/tratamento farmacológico , Transtorno Depressivo Maior/metabolismo , Humanos , Magnésio/fisiologia , Neurotransmissores/farmacologia , Neurotransmissores/fisiologia , Dor/tratamento farmacológico , Dor/metabolismo , Piperidinas/farmacologia , Poliaminas/farmacologia , Subunidades Proteicas/antagonistas & inibidores , Subunidades Proteicas/fisiologia , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Transmissão Sináptica , Zinco/fisiologia
12.
J Neurochem ; 108(2): 384-96, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19012743

RESUMO

The 5-HT(3) receptor is a member of the 'Cys-loop' family of ligand-gated ion channels that mediate fast excitatory and inhibitory transmission in the nervous system. Current evidence points towards native 5-HT(3) receptors originating from homomeric assemblies of 5-HT(3A) or heteromeric assembly of 5-HT(3A) and 5-HT(3B). Novel genes encoding 5-HT(3C), 5-HT(3D), and 5-HT(3E) have recently been described but the functional importance of these proteins is unknown. In the present study, in silico analysis (confirmed by partial cloning) indicated that 5-HT(3C), 5-HT(3D), and 5-HT(3E) are not human-specific as previously reported: they are conserved in multiple mammalian species but are absent in rodents. Expression profiles of the novel human genes indicated high levels in the gastrointestinal tract but also in the brain, Dorsal Root Ganglion (DRG) and other tissues. Following the demonstration that these subunits are expressed at the cell membrane, the functional properties of the recombinant human subunits were investigated using patch clamp electrophysiology. 5-HT(3C), 5-HT(3D), and 5-HT(3E) were all non-functional when expressed alone. Co-transfection studies to determine potential novel heteromeric receptor interactions with 5-HT(3A) demonstrated that the expression or function of the receptor was modified by 5-HT(3C) and 5-HT(3E), but not 5-HT(3D). The lack of distinct effects on current rectification, kinetics or pharmacology of 5-HT(3A) receptors does not however provide unequivocal evidence to support a direct contribution of 5-HT(3C) or 5-HT(3E) to the lining of the ion channel pore of novel heteromeric receptors. The functional and pharmacological contributions of these novel subunits to human biology and diseases such as irritable bowel syndrome for which 5-HT(3) receptor antagonists have major clinical usage, therefore remains to be fully determined.


Assuntos
Evolução Biológica , Subunidades Proteicas/fisiologia , Receptores 5-HT3 de Serotonina/química , Receptores 5-HT3 de Serotonina/fisiologia , Animais , Linhagem Celular Transformada , Cricetinae , Cricetulus , Relação Dose-Resposta a Droga , Estimulação Elétrica/métodos , Furões , Antagonistas GABAérgicos/farmacologia , Proteínas de Fluorescência Verde/genética , Humanos , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Técnicas de Patch-Clamp/métodos , Picrotoxina/farmacologia , Coelhos , Serotonina/farmacologia , Transfecção
13.
Drug Discov Today ; 14(1-2): 56-67, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19063991

RESUMO

TRPV1 is a noxious heat, capsaicin (vanilloid) and acid receptor for which the development of antagonists represents a novel therapeutic approach for the treatment of pain. TRPV1 antagonists have entered early clinical development and initial reports indicate that they have demonstrated pharmacodynamic effects consistent with TRPV1 antagonist activity and anti-hyperalgesic action in humans. Should these effects extend to the relief of symptoms experienced by patients with chronic pain then this class of compounds may offer one of the first novel mechanisms of action for the treatment for pain for many years. In this article we will discuss recent progress and challenges in the field in this highly competitive area of drug discovery.


Assuntos
Analgésicos/farmacologia , Dor/tratamento farmacológico , Canais de Cátion TRPV/antagonistas & inibidores , Analgésicos/uso terapêutico , Animais , Doença Crônica , Sistemas de Liberação de Medicamentos , Desenho de Fármacos , Humanos , Dor/fisiopatologia
14.
Bioorg Med Chem Lett ; 18(20): 5609-13, 2008 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-18809327

RESUMO

6-Phenylnicotinamide (2) was previously identified as a potent TRPV1 antagonist with activity in an in vivo model of inflammatory pain. Optimization of this lead through modification of both the biaryl and heteroaryl components has resulted in the discovery of 6-(4-fluorophenyl)-2-methyl-N-(2-methylbenzothiazol-5-yl)nicotinamide (32; SB-782443) which possesses an excellent overall profile and has been progressed into pre-clinical development.


Assuntos
Benzotiazóis/síntese química , Química Farmacêutica/métodos , Niacinamida/análogos & derivados , Niacinamida/síntese química , Canais de Cátion TRPV/antagonistas & inibidores , Canais de Cátion TRPV/química , Administração Oral , Animais , Benzotiazóis/farmacologia , Capsaicina/química , Linhagem Celular , Desenho de Fármacos , Cobaias , Humanos , Inflamação , Concentração Inibidora 50 , Modelos Químicos , Niacinamida/química , Niacinamida/farmacologia , Ratos
15.
Curr Pharm Des ; 14(1): 32-41, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18220816

RESUMO

Based on the painful effects of exposure to capsaicin, TRPV1 (transient receptor potential vanilloid subfamily member 1) localization is most readily associated with peripheral sensory neurons, however, TRPV1 is now known to be expressed, albeit at lower levels, in the spinal cord, brain and a wide-range of non-neuronal cells. The latter includes epithelial cells (e.g. keratinocytes, urothelium, gastric epithelial cells, enterocytes, and pneumocytes) through vascular endothelium and cells of the immune system (e.g. T-cells and mast cells) to smooth muscle, fibroblasts and hepatocytes. Despite extensive research, the physiological function of TRPV1 in the brain and in non-neuronal tissues remains elusive. The preliminary results are exciting, but many are unconfirmed and/or contradictory. As yet, studies with TRPV1 knock-out mice have proven unhelpful in clarifying such biological roles. Now that a range of potent and selective TRPV1 antagonists are available in this rapidly expanding research field, further understanding of the biological roles of TRPV1 throughout the body is within reach. In this article, we will summarize the known roles of peripheral TRPV1 receptors in physiology and disease and review the current perspectives for the therapeutic potential of TRPV1 agonists and antagonists in the treatment of a wide range of conditions such as pain, cancer, migraine, chronic cough, asthma, rectal hypersensitivity, inflammatory bowel disease, obesity, overactive bladder and diabetes. New applications of targeting central TRPV1 receptors are reviewed in the accompanying article by Starowicz et al. (in this issue).


Assuntos
Sistemas de Liberação de Medicamentos , Expressão Gênica , Canais de Cátion TRPV/metabolismo , Animais , Capsaicina/farmacologia , Ensaios Clínicos como Assunto , Modelos Animais de Doenças , Desenho de Fármacos , Humanos , Sistema Nervoso Periférico/patologia , Sistema Nervoso Periférico/fisiologia , Canais de Cátion TRPV/agonistas , Canais de Cátion TRPV/antagonistas & inibidores
16.
J Pharmacol Exp Ther ; 321(3): 1183-92, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17392405

RESUMO

Vanilloid receptor-1 (TRPV1) is a nonselective cation channel, predominantly expressed by sensory neurons, which plays a key role in the detection of noxious painful stimuli such as capsaicin, acid, and heat. TRPV1 antagonists may represent novel therapeutic agents for the treatment of a range of conditions including chronic pain, migraine, and gastrointestinal disorders. Here we describe the in vitro pharmacology of N-(2-bromophenyl)-N'-[((R)-1-(5-trifluoromethyl-2-pyridyl)pyrrolidin-3-yl)]urea (SB-705498), a novel TRPV1 antagonist identified by lead optimization of N-(2-bromophenyl)-N'-[2-[ethyl(3-methylphenyl)amino]ethyl]urea (SB-452533), which has now entered clinical trials. Using a Ca(2+)-based fluorometric imaging plate reader (FLIPR) assay, SB-705498 was shown to be a potent competitive antagonist of the capsaicin-mediated activation of the human TRPV1 receptor (pK(i) = 7.6) with activity at rat (pK(i) = 7.5) and guinea pig (pK(i) = 7.3) orthologs. Whole-cell patch-clamp electrophysiology was used to confirm and extend these findings, demonstrating that SB-705498 can potently inhibit the multiple modes of receptor activation that may be relevant to the pathophysiological role of TRPV1 in vivo: SB-705498 caused rapid and reversible inhibition of the capsaicin (IC(50) = 3 nM)-, acid (pH 5.3)-, or heat (50 degrees C; IC(50) = 6 nM)-mediated activation of human TRPV1 (at -70 mV). Interestingly, SB-705498 also showed a degree of voltage dependence, suggesting an effective enhancement of antagonist action at negative potentials such as those that might be encountered in neurons in vivo. The selectivity of SB-705498 was defined by broad receptor profiling and other cellular assays in which it showed little or no activity versus a wide range of ion channels, receptors, and enzymes. SB-705498 therefore represents a potent and selective multimodal TRPV1 antagonist, a pharmacological profile that has contributed to its definition as a suitable drug candidate for clinical development.


Assuntos
Ácidos/farmacologia , Capsaicina/farmacologia , Temperatura Alta , Pirrolidinas/farmacologia , Canais de Cátion TRPV/antagonistas & inibidores , Ureia/análogos & derivados , Animais , Ligação Competitiva/efeitos dos fármacos , Sinalização do Cálcio/efeitos dos fármacos , Linhagem Celular , Células Cultivadas , Relação Dose-Resposta a Droga , Eletrofisiologia , Cobaias , Humanos , Concentração de Íons de Hidrogênio , Potenciais da Membrana/efeitos dos fármacos , Estrutura Molecular , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/fisiologia , Técnicas de Patch-Clamp , Pirrolidinas/química , Ratos , Canais de Cátion TRPV/genética , Canais de Cátion TRPV/fisiologia , Transfecção , Ureia/química , Ureia/farmacologia
17.
J Pharmacol Exp Ther ; 321(2): 564-72, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17267580

RESUMO

Spreading depression (SD) has long been associated with the underlying pathophysiology of migraine. Evidence that the N-methyl-D-aspartate (NMDA) glutamate receptor (NMDA-R) is implicated in the generation and propagation of SD has itself been available for more than 15 years. However, to date, there are no reports of NMDA-R antagonists being developed for migraine therapy. In this study, an uncompetitive, pan-NMDA-R blocker, memantine, approved for clinical use, and two antagonists with selectivity for NMDA-R containing the NR2B subunit, (1S,2S)-1-(4-hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol (CP-101,606) and (+/-)-(R*,S*)-alpha-(4-hydroxyphenyl)-beta-methyl-4-(phenylmethyl)-1-piperidine propanol (Ro 25-6981), were investigated to assess their protective effects against SD in the rat. Under isoflurane anesthesia, d.c. potential and the related cortical blood flow and partial pressure of O2 (pO2) were recorded simultaneously at separate cortical sites. Drugs (1, 3, and 10 mg/kg i.p.) were given 1 h or 30 min before KCl application to the brain surface. Core temperature and arterial pCO2,pO2, and pH measurements confirmed physiological stability. KCl induced 7.7+/-1.8 (mean+/-S.D.) SD events with d.c. amplitude of 14.9+/-2.8 mV. Memantine and CP-101,606 dose-dependently decreased SD event number (to 2.0+/-1.8 and 2.3+/-2.9, respectively) and SD amplitude at doses relevant for therapeutic use. Ro 25-6981 also decreased SD events significantly, but less effectively (to 4.5+/-1.6), without affecting amplitude. These results indicate that NR2B-containing NMDA receptors are key mediators of SD, and as such, memantine- and NR2B-selective antagonists may be useful new therapeutic agents for the treatment of migraine and other SD-related disorders (e.g., stroke and brain injury). Whether chronic, rather than acute, treatment may improve their efficacy remains to be determined.


Assuntos
Depressão Alastrante da Atividade Elétrica Cortical/efeitos dos fármacos , Antagonistas de Aminoácidos Excitatórios/farmacologia , Transtornos de Enxaqueca/tratamento farmacológico , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Animais , Circulação Cerebrovascular/efeitos dos fármacos , Maleato de Dizocilpina/farmacologia , Relação Dose-Resposta a Droga , Antagonistas de Aminoácidos Excitatórios/uso terapêutico , Masculino , Memantina/farmacocinética , Memantina/farmacologia , Oxigênio/sangue , Fenóis/farmacocinética , Fenóis/farmacologia , Piperidinas/farmacocinética , Piperidinas/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores de N-Metil-D-Aspartato/classificação
18.
J Neurosci ; 26(50): 12852-60, 2006 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-17167076

RESUMO

We used a mouse with deletion of exons 4, 5, and 6 of the SCN11A (sodium channel, voltage-gated, type XI, alpha) gene that encodes the voltage-gated sodium channel Na(v)1.9 to assess its contribution to pain. Na(v)1.9 is present in nociceptor sensory neurons that express TRPV1, bradykinin B2, and purinergic P2X3 receptors. In Na(v)1.9-/- mice, the non-inactivating persistent tetrodotoxin-resistant sodium TTXr-Per current is absent, whereas TTXr-Slow is unchanged. TTXs currents are unaffected by the mutation of Na(v)1.9. Pain hypersensitivity elicited by intraplantar administration of prostaglandin E2, bradykinin, interleukin-1beta, capsaicin, and P2X3 and P2Y receptor agonists, but not NGF, is either reduced or absent in Na(v)1.9-/- mice, whereas basal thermal and mechanical pain sensitivity is unchanged. Thermal, but not mechanical, hypersensitivity produced by peripheral inflammation (intraplanatar complete Freund's adjuvant) is substantially diminished in the null allele mutant mice, whereas hypersensitivity in two neuropathic pain models is unchanged in the Na(v)1.9-/- mice. Na(v)1.9 is, we conclude, an effector of the hypersensitivity produced by multiple inflammatory mediators on nociceptor peripheral terminals and therefore plays a key role in mediating peripheral sensitization.


Assuntos
Hiperalgesia/metabolismo , Neuropeptídeos/biossíntese , Nervos Periféricos/metabolismo , Canais de Sódio/biossíntese , Animais , Feminino , Hiperalgesia/genética , Inflamação/genética , Inflamação/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Canal de Sódio Disparado por Voltagem NAV1.9 , Neurônios Aferentes/metabolismo , Neuropeptídeos/genética , Dor/genética , Dor/metabolismo , Medição da Dor/métodos , Canais de Sódio/genética
19.
Eur J Pharmacol ; 540(1-3): 73-81, 2006 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-16737693

RESUMO

The anti-hyperalgesic effects of TRPV1 receptor antagonists are well documented in animal models of pain, however, the precise site of their action is not known. Here we have examined the effects of the selective TRPV1 antagonist SB-366791 on glutamatergic synaptic transmission in substantia gelatinosa using spinal cord slices from either control rats or animals that had undergone a peripheral inflammation induced by intraplantar injection of Freund's complete adjuvant (FCA). In control animals, SB-366791 (30 microM) had no effect on spontaneous excitatory post-synaptic currents (sEPSC) or evoked EPSCs. In slices from FCA-inflamed animals, SB-366791 decreased sEPSC frequency to 66+/-8% of control in 5/10 neurones, and decreased miniature glutamatergic EPSCs (mEPSC) frequency to 63+/-4% of control, in 6/7 neurones; with no significant effect on sEPSC or mEPSC amplitude. Dorsal root evoked EPSCs at C-fibre intensity were reduced to 72+/-6% of control by SB-366791 (30 microM) in 3/4 neurones from FCA-treated animals. In conclusion, SB-366791 inhibited glutamatergic transmission in a subset of neurones via a pre-synaptic mechanism following peripheral inflammation. We hypothesise that during peripheral inflammation spinal TRPV1 becomes tonically active, promoting the synaptic release of glutamate. These results provide evidence for a mechanism by which TRPV1 contributes to inflammatory pain and provides a basis for the understanding of the efficacy of TRPV1 antagonists.


Assuntos
Anilidas/farmacologia , Cinamatos/farmacologia , Inflamação/fisiopatologia , Células do Corno Posterior/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Canais de Cátion TRPV/antagonistas & inibidores , Animais , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Adjuvante de Freund/administração & dosagem , Adjuvante de Freund/toxicidade , Glutamatos/metabolismo , Inflamação/induzido quimicamente , Modelos Biológicos , Células do Corno Posterior/fisiologia , Ratos , Transmissão Sináptica/fisiologia , Canais de Cátion TRPV/metabolismo , Fatores de Tempo
20.
Bioorg Med Chem Lett ; 16(12): 3287-91, 2006 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-16580202

RESUMO

Small molecule antagonists of the vanilloid receptor TRPV1 (also known as VR1) are disclosed. Pyrrolidinyl ureas such as 8 and 15 (SB-705498) emerged as lead compounds following optimisation of the previously described urea SB-452533. Pharmacological studies using electrophysiological and FLIPR-Ca2+-based assays showed that compounds such as 8 and 15 were potent antagonists versus the multiple chemical and physical modes of TRPV1 activation (namely capsaicin, acid and noxious heat). Furthermore, 15 possessed suitable developability properties to enable progression of this compound into in vivo studies and subsequently clinical development.


Assuntos
Pirrolidinas/síntese química , Pirrolidinas/farmacologia , Canais de Cátion TRPV/antagonistas & inibidores , Ureia/análogos & derivados , Administração Oral , Animais , Capsaicina/farmacologia , Linhagem Celular , Desenho de Fármacos , Cobaias , Humanos , Estrutura Molecular , Pirrolidinas/administração & dosagem , Pirrolidinas/química , Ratos , Relação Estrutura-Atividade , Canais de Cátion TRPV/metabolismo , Ureia/administração & dosagem , Ureia/síntese química , Ureia/química , Ureia/farmacologia
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