RESUMO
Inhibitors of phosphodiesterase-4 (PDE4) have been approved for the treatment of inflammatory disorders, but are associated with dose-limiting nausea and vomiting. These side effects are hypothesized to be mediated by inhibition of the PDE4D isozyme. Here we demonstrate the anti-inflammatory effects of the novel brain penetrant PDE4D-sparing PDE4 inhibitor, ABI-4. ABI-4 was a potent (EC50â¼14nM) inhibitor of lipopolysaccharide (LPS) induced TNF-α release from mouse microglia and human PBMCs. ABI-4 (0.32mg/kg) blocked LPS-induced release of pro-inflammatory cytokines (TNF-α, IL-1ß, IL-6) in blood and brain of mice. In a rat model of endotoxin induced uveitis, ABI-4 (0.03-0.3mg/kg) demonstrated steroid-like efficacy in preventing leucocyte infiltration of the aqueous humor when administered 4h after LPS. LPS (0.32mg/kg×5days) caused a 30% upregulation of translocator protein (TSPO) binding which was prevented by co-administration of ABI-4 (0.32mg/kg). In a paradigm to assess motivation, LPS (0.32mg/kg) reduced the number of rewards received, whereas the effect was significantly blunted in mice dosed with ABI-4 (P<0.05) or in PDE4B-/- mice. PDE4B was also shown to modulate brain and plasma levels of TNF-α and IL-1ß in aged mice. Aged mice dosed chronically with ABI-4 (0.32mg/kg) as well as aged PDE4B-/- mice, had significantly lower levels of TNF-α and IL-1ß in brain and plasma relative to vehicle treated or PDE4+/+ mice. Together these data demonstrate that the PDE4D sparing, PDE4 inhibitor, ABI-4 retains potency and efficacy in exerting anti-inflammatory effects. This mechanism warrants further investigation in human disorders involving neuroinflammation.
Assuntos
Anti-Inflamatórios/administração & dosagem , Encéfalo/efeitos dos fármacos , Encefalite/tratamento farmacológico , Inflamação/tratamento farmacológico , Inibidores da Fosfodiesterase 4/administração & dosagem , Animais , Encéfalo/metabolismo , Encefalite/induzido quimicamente , Encefalite/metabolismo , Humanos , Inflamação/induzido quimicamente , Inflamação/metabolismo , Mediadores da Inflamação/metabolismo , Isoenzimas/administração & dosagem , Lipopolissacarídeos , Masculino , Camundongos Endogâmicos C57BL , Microglia/efeitos dos fármacos , Microglia/metabolismo , Motivação/efeitos dos fármacos , Ratos Endogâmicos LewRESUMO
Kappa opioid receptors (KORs) have been implicated in anxiety and stress, conditions that involve activation of projections from the basolateral amygdala (BLA) to the medial prefrontal cortex (mPFC). Although KORs have been studied in several brain regions, their role on mPFC physiology and on BLA projections to the mPFC remains unclear. Here, we explored whether KORs modify synaptic inputs from the BLA to the mPFC using in vivo electrophysiological recordings with electrical and optogenetic stimulation. Systemic administration of the KOR agonist U69,593 inhibited BLA-evoked synaptic responses in the mPFC without altering hippocampus-evoked responses. Intra-mPFC U69,593 inhibited electrical and optogenetic BLA-evoked synaptic responses, an effect blocked by the KOR antagonist nor-BNI. Bilateral intra-mPFC injection of the KOR antagonist nor-BNI increased center time in the open field test, suggesting an anxiolytic effect. The data demonstrate that mPFC KORs negatively regulate glutamatergic synaptic transmission in the BLA-mPFC pathway and anxiety-like behavior. These findings provide a framework whereby KOR signaling during stress and anxiety can regulate the flow of emotional state information from the BLA to the mPFC.
Assuntos
Complexo Nuclear Basolateral da Amígdala/fisiologia , Córtex Pré-Frontal/fisiologia , Receptores Opioides kappa/metabolismo , Analgésicos Opioides/farmacologia , Animais , Ansiolíticos/farmacologia , Ansiedade/tratamento farmacológico , Ansiedade/fisiopatologia , Complexo Nuclear Basolateral da Amígdala/efeitos dos fármacos , Benzenoacetamidas/farmacologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Ácido Glutâmico/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/fisiologia , Masculino , Camundongos Endogâmicos C57BL , Microeletrodos , Naltrexona/análogos & derivados , Naltrexona/farmacologia , Antagonistas de Entorpecentes/farmacologia , Vias Neurais/efeitos dos fármacos , Vias Neurais/fisiologia , Optogenética , Córtex Pré-Frontal/efeitos dos fármacos , Pirrolidinas/farmacologia , Distribuição Aleatória , Ratos Long-Evans , Receptores Opioides kappa/agonistas , Receptores Opioides kappa/antagonistas & inibidoresRESUMO
Positive allosteric modulators ("potentiators") of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors (AMPAR) enhance excitatory neurotransmission and may improve the cognitive deficits associated with various neurological disorders. The dihydroisoxazole (DHI) series of AMPAR potentiators described herein originated from the identification of 7 by a high-throughput functional activity screen using mouse embryonic stem (mES) cell-derived neuronal precursors. Subsequent structure-based drug design using X-ray crystal structures of the ligand-binding domain of human GluA2 led to the discovery of both PF-04725379 (11), which in tritiated form became a novel ligand for characterizing the binding affinities of subsequent AMPAR potentiators in rat brain homogenate, and PF-04701475 (8a), a prototype used to explore AMPAR-mediated pharmacology in vivo. Lead series optimization provided 16a, a functionally potent compound lacking the potentially bioactivatable aniline within 8a, but retaining desirable in vitro ADME properties.
Assuntos
Descoberta de Drogas , Isoxazóis/química , Isoxazóis/farmacologia , Receptores de AMPA/metabolismo , Absorção , Regulação Alostérica/efeitos dos fármacos , Animais , Ensaios de Triagem em Larga Escala , Humanos , Isoxazóis/metabolismo , Isoxazóis/farmacocinética , Masculino , Camundongos , Modelos Moleculares , Estrutura Terciária de Proteína , Ratos , Receptores de AMPA/química , Relação Estrutura-AtividadeRESUMO
α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) positive allosteric modulation (i.e., "potentiation") has been proposed to overcome cognitive impairments in schizophrenia, but AMPAR overstimulation can be excitotoxic. Thus, it is critical to define carefully a potentiator's mechanism-based therapeutic index (TI) and to determine confidently its translatability from rodents to higher-order species. Accordingly, the novel AMPAR potentiator N-{(3R,4S)-3-[4-(5-cyano-2-thienyl)phenyl]tetrahydro-2H-pyran-4-yl}propane-2-sulfonamide (PF-4778574) was characterized in a series of in vitro assays and single-dose animal studies evaluating AMPAR-mediated activities related to cognition and safety to afford an unbound brain compound concentration (Cb,u)-normalized interspecies exposure-response relationship. Because it is unknown which AMPAR subtype(s) may be selectively potentiated for an optimal TI, PF-4778574 binding affinity and functional potency were determined in rodent tissues expected to express a native mixture of AMPAR subunits and their associated proteins to afford composite pharmacological values. Functional activity was also quantified in recombinant cell lines stably expressing human GluA2 flip or flop homotetramers. Procognitive effects of PF-4778574 were evaluated in both rat electrophysiological and nonhuman primate (nhp) behavioral models of pharmacologically induced N-methyl-d-aspartate receptor hypofunction. Safety studies assessed cerebellum-based AMPAR activation (mouse) and motor coordination disruptions (mouse, dog, and nhp), as well as convulsion (mouse, rat, and dog). The resulting empirically derived exposure-response continuum for PF-4778574 defines a single-dose-based TI of 8- to 16-fold for self-limiting tremor, a readily monitorable clinical adverse event. Importantly, the Cb,u mediating each physiological effect were highly consistent across species, with efficacy and convulsion occurring at just fractions of the in vitro-derived pharmacological values.
Assuntos
Agonistas de Aminoácidos Excitatórios/farmacologia , Receptores de AMPA/agonistas , Receptores de AMPA/fisiologia , Tiofenos/farmacologia , Regulação Alostérica/efeitos dos fármacos , Regulação Alostérica/fisiologia , Animais , Células Cultivadas , Cães , Agonistas de Aminoácidos Excitatórios/uso terapêutico , Feminino , Células HEK293 , Humanos , Macaca fascicularis , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Desempenho Psicomotor/efeitos dos fármacos , Desempenho Psicomotor/fisiologia , Distribuição Aleatória , Ratos , Ratos Sprague-Dawley , Convulsões/fisiopatologia , Convulsões/prevenção & controle , Tiofenos/uso terapêutico , Resultado do TratamentoRESUMO
Social withdrawal is one of several negative symptoms of schizophrenia, all of which are poorly treated by current therapies. One challenge in developing agents with efficacy against negative symptoms is the lack of suitable preclinical models. The social approach test was used as the basis for developing an assay to test emerging therapies for negative symptoms. NMDA antagonists and dopamine agonists have been used extensively to produce or disrupt behaviors thought to be rodent correlates of positive and cognitive symptoms of schizophrenia. The aim of these studies was to determine whether sociability of mice in the 3-chamber social approach test could be disrupted and whether this paradigm could have utility in predicting efficacy against negative symptoms. The criteria for such a model were: a lack of response to antipsychotics and attenuation by agents such as the glycine agonist, d-cycloserine, which has been shown to possess clinical efficacy against negative symptoms. Administration of the NMDA antagonists MK-801, PCP, or ketamine did not disrupt sociability. In contrast, Grin1 hypomorph mice displayed a social deficit which was not reversed by atypical antipsychotics or d-serine. d-Amphetamine disrupted sociability without stimulating locomotor activity and its effect was not reversed by antipsychotics. The GABAA inverse agonist, FG-7142, reduced sociability and this was reversed by the GABAA antagonist, flumazenil and dcycloserine, but not by clozapine, or the GABAA benzodiazepine anxiolytic, alprazolam. Based on our criteria, the GABAA model warrants further evaluation to confirm that this paradigm has utility as a preclinical model for predicting efficacy against negative symptoms of schizophrenia.
Assuntos
Transtornos do Comportamento Social/induzido quimicamente , Transtornos do Comportamento Social/genética , Análise de Variância , Animais , Antipiréticos/uso terapêutico , Carbolinas , Proteínas de Transporte/genética , Dextroanfetamina/farmacologia , Inibidores da Captação de Dopamina/farmacologia , Relação Dose-Resposta a Droga , Antagonistas de Aminoácidos Excitatórios/toxicidade , Antagonistas GABAérgicos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas do Tecido Nervoso/genética , Receptores de N-Metil-D-Aspartato , Transtornos do Comportamento Social/tratamento farmacológico , Fatores de TempoRESUMO
A novel series of mGluR2 positive allosteric modulators (PAMs), 1-[(1-methyl-1H-imidazol-2-yl)methyl]-4-phenylpiperidines, is herein disclosed. Structure-activity relationship studies led to potent, selective mGluR2 PAMs with excellent pharmacokinetic profiles. A representative lead compound (+)-17e demonstrated dose-dependent inhibition of methamphetamine-induced hyperactivity and mescaline-induced scratching in mice, providing support for potential efficacy in treating psychosis.
Assuntos
Antipsicóticos/síntese química , Compostos Bicíclicos Heterocíclicos com Pontes/síntese química , Imidazóis/síntese química , Piperidinas/síntese química , Receptores de Glutamato Metabotrópico/metabolismo , Regulação Alostérica , Animais , Antipsicóticos/farmacocinética , Antipsicóticos/farmacologia , Disponibilidade Biológica , Encéfalo/metabolismo , Compostos Bicíclicos Heterocíclicos com Pontes/farmacocinética , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Linhagem Celular , Cães , Humanos , Hipercinese/induzido quimicamente , Hipercinese/tratamento farmacológico , Imidazóis/farmacocinética , Imidazóis/farmacologia , Técnicas In Vitro , Metanfetamina , Camundongos , Microssomos Hepáticos/metabolismo , Modelos Moleculares , Piperidinas/farmacocinética , Piperidinas/farmacologia , Conformação Proteica , Ensaio Radioligante , Ratos , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
The discovery, synthesis and SAR of a novel series of 3-benzyl-1,3-oxazolidin-2-ones as positive allosteric modulators (PAMs) of mGluR2 is described. Expedient hit-to-lead work on a single HTS hit led to the identification of a ligand-efficient and structurally attractive series of mGluR2 PAMs. Human microsomal clearance and suboptimal physicochemical properties of the initial lead were improved to give potent, metabolically stable and orally available mGluR2 PAMs.