RESUMEN
Negative modulators of metabotropic glutamate 2 & 3 receptors demonstrate antidepressant-like activity in animal models and hold promise as novel therapeutic agents for the treatment of major depressive disorder. Herein we describe our efforts to prepare and optimize a series of conformationally constrained 3,4-disubstituted bicyclo[3.1.0]hexane glutamic acid analogs as orthosteric (glutamate site) mGlu2/3 receptor antagonists. This work led to the discovery of a highly potent and efficacious tool compound 18 (hmGlu2 IC50 46±14.2nM, hmGlu3 IC50=46.1±36.2nM). Compound 18 showed activity in the mouse forced swim test with a minimal effective dose (MED) of 1mg/kg ip. While in rat EEG studies it exhibited wake promoting effects at 3 and 10mg/kg ip without any significant effects on locomotor activity. Compound 18 thus represents a novel tool molecule for studying the impact of blocking mGlu2/3 receptors both in vitro and in vivo.
Asunto(s)
Antidepresivos/química , Antidepresivos/farmacología , Trastorno Depresivo Mayor/tratamiento farmacológico , Ácido Glutámico/análogos & derivados , Ácido Glutámico/farmacología , Receptores de Glutamato Metabotrópico/antagonistas & inhibidores , Animales , Antidepresivos/farmacocinética , Compuestos Bicíclicos con Puentes/química , Compuestos Bicíclicos con Puentes/farmacocinética , Compuestos Bicíclicos con Puentes/farmacología , Línea Celular , Trastorno Depresivo Mayor/metabolismo , Perros , Ácido Glutámico/farmacocinética , Haplorrinos , Hexanos/química , Hexanos/farmacocinética , Hexanos/farmacología , Humanos , Células de Riñón Canino Madin Darby , Ratones , Ratas , Receptores de Glutamato Metabotrópico/metabolismoRESUMEN
A novel series of selective negative allosteric modulators (NAMs) for metabotropic glutamate receptor 5 (mGlu5) was discovered from an isothiazole scaffold. One compound of this series, (1R,2R)-N-(4-(6-isopropylpyridin-2-yl)-3-(2-methyl-2H-indazol-5-yl)isothiazol-5-yl)-2-methylcyclopropanecarboxamide (24), demonstrated satisfactory pharmacokinetic properties and, following oral dosing in rats, produced dose-dependent and long-lasting mGlu5 receptor occupancy. Consistent with the hypothesis that blockade of mGlu5 receptors will produce analgesic effects in mammals, compound 24 produced a dose-dependent reduction in paw licking responses in the formalin model of persistent pain.
Asunto(s)
Amidas/química , Amidas/farmacología , Ciclopropanos/química , Ciclopropanos/farmacología , Receptor del Glutamato Metabotropico 5/metabolismo , Regulación Alostérica/efectos de los fármacos , Amidas/farmacocinética , Animales , Conducta Animal/efectos de los fármacos , Ciclopropanos/farmacocinética , Ácido Glutámico/química , Ácido Glutámico/metabolismo , Indazoles/química , Indazoles/farmacocinética , Indazoles/farmacología , Masculino , Ratas , Ratas Sprague-Dawley , Receptor del Glutamato Metabotropico 5/química , Tiazoles/química , Tiazoles/farmacocinética , Tiazoles/farmacologíaRESUMEN
The normalization of excessive glutamatergic neurotransmission through the activation of metabotropic glutamate 2 (mGlu2) receptors may have therapeutic potential in a variety of psychiatric disorders, including anxiety/depression and schizophrenia. Here, we characterize the pharmacological properties of N-(4-((2-(trifluoromethyl)-3-hydroxy-4-(isobutyryl)phenoxy)methyl)benzyl)-1-methyl-1H-imidazole-4-carboxamide (THIIC), a structurally novel, potent, and selective allosteric potentiator of human and rat mGlu2 receptors (EC(50) = 23 and 13 nM, respectively). THIIC produced anxiolytic-like efficacy in the rat stress-induced hyperthermia assay and the mouse stress-induced elevation of cerebellar cGMP and marble-burying assays. THIIC also produced robust activity in three assays that detect antidepressant-like activity, including the mouse forced-swim test, the rat differential reinforcement of low rate 72-s assay, and the rat dominant-submissive test, with a maximal response similar to that of imipramine. Effects of THIIC in the forced-swim test and marble burying were deleted in mGlu2 receptor null mice. Analysis of sleep electroencephalogram (EEG) showed that THIIC had a sleep-promoting profile with increased non-rapid eye movement (REM) and decreased REM sleep. THIIC also decreased the dark phase increase in extracellular histamine in the medial prefrontal cortex and decreased levels of the histamine metabolite tele-methylhistamine (t-MeHA) in rat cerebrospinal fluid. Collectively, these results indicate that the novel mGlu2-positive allosteric modulator THIIC has robust activity in models used to predict anxiolytic/antidepressant efficacy, substantiating, at least with this molecule, differentiation in the biological impact of mGlu2 potentiation versus mGlu2/3 orthosteric agonism. In addition, we provide evidence that sleep EEG and CSF t-MeHA might function as viable biomarker approaches to facilitate the translational development of THIIC and other mGlu2 potentiators.
Asunto(s)
Ansiolíticos/farmacología , Antidepresivos/farmacología , Compuestos de Bencilo/farmacología , Sistema Nervioso Central/efectos de los fármacos , Sistema Nervioso Central/metabolismo , Agonistas de Aminoácidos Excitadores/farmacología , Imidazoles/farmacología , Receptores de Glutamato Metabotrópico/agonistas , Animales , Conducta Animal/efectos de los fármacos , Conducta Animal/fisiología , Línea Celular , Sistema Nervioso Central/química , Cerebelo/química , Cerebelo/efectos de los fármacos , Cerebelo/metabolismo , Sinergismo Farmacológico , Humanos , Masculino , Ratones , Ratones Noqueados , Ratas , Ratas Endogámicas F344 , Ratas Sprague-Dawley , Ratas Wistar , Receptores de Glutamato Metabotrópico/fisiologíaRESUMEN
The role of organic cation transporter 1 (OCT1) in humans is gaining attention as data emerges regarding its role in physiology, drug exposure, and drug response. OCT1 variants with decreased in vitro function correlate well with altered exposure of multiple OCT1 substrates in variant carriers. In the current research, we investigate mechanisms behind activity of OCT1 variants in vitro by generating cell lines expressing known OCT1 variants and quantifying membrane OCT1 protein expression with corresponding OCT1 activity and kinetics. Oct knockout mice have provided additional insight into the role of Oct1 in the liver and have reproduced effects of altered OCT1 activity observed in the clinic. To assess the complex effect of Oct1 depletion on pharmacokinetics of prodrug proguanil and its active moiety cycloguanil, both of which are OCT1 substrates, Oct1/2-/- mice were used. Decreased membrane expression of OCT1 was demonstrated for all variant cell lines, although activity was substrate-dependent, as reported previously. Lack of change in activity for OCT1*2 resulted in increased intrinsic activity per pmol of OCT1 protein, particularly for sumatriptan but also for proguanil and cycloguanil. Similar to that reported in humans with decreased OCT1 function, systemic exposure of proguanil was minimally affected in Oct1/2-/- mice. However, proguanil liver partitioning and exposure decreased. Cycloguanil exposure decreased following proguanil administration in Oct1/2-/- mice, as did the systemic metabolite:parent ratio. When administered directly, systemic exposure of cycloguanil decreased slightly; however liver partitioning and exposure were decreased in Oct1/2-/- mice. Unexpectedly, following proguanil administration, the metabolite ratio in the liver changed only minimally, and liver partitioning of cycloguanil was affected in Oct1/2-/- mice to a lesser extent following proguanil administration than direct administration of cycloguanil. In conclusion, these in vitro and in vivo data offer additional complexity in understanding mechanisms of OCT1 variant activity as well as the effects of these variants in vivo. From cell lines, it is apparent that intrinsic activity is not directly related to OCT1 membrane expression. Additionally, in situations with a more complicated role of OCT1 in drug pharmacokinetics there is difficulty translating in vivo impact simply from intrinsic activity from cellular data.
RESUMEN
Multiple therapeutic opportunities have been suggested for compounds capable of selective activation of metabotropic glutamate 3 (mGlu3) receptors, but small molecule tools are lacking. As part of our ongoing efforts to identify potent, selective, and systemically bioavailable agonists for mGlu2 and mGlu3 receptor subtypes, a series of C4ß-N-linked variants of (1 S,2 S,5 R,6 S)-2-amino-bicyclo[3.1.0]hexane-2,6-dicarboxylic acid 1 (LY354740) were prepared and evaluated for both mGlu2 and mGlu3 receptor binding affinity and functional cellular responses. From this investigation we identified (1 S,2 S,4 S,5 R,6 S)-2-amino-4-[(3-methoxybenzoyl)amino]bicyclo[3.1.0]hexane-2,6-dicarboxylic acid 8p (LY2794193), a molecule that demonstrates remarkable mGlu3 receptor selectivity. Crystallization of 8p with the amino terminal domain of hmGlu3 revealed critical binding interactions for this ligand with residues adjacent to the glutamate binding site, while pharmacokinetic assessment of 8p combined with its effect in an mGlu2 receptor-dependent behavioral model provides estimates for doses of this compound that would be expected to selectively engage and activate central mGlu3 receptors in vivo.
Asunto(s)
Compuestos Bicíclicos con Puentes/síntesis química , Compuestos Bicíclicos con Puentes/farmacología , Agonistas de Aminoácidos Excitadores/síntesis química , Agonistas de Aminoácidos Excitadores/farmacología , Receptores de Glutamato Metabotrópico/agonistas , Animales , Compuestos Bicíclicos con Puentes/farmacocinética , Cristalografía por Rayos X , AMP Cíclico/farmacología , Agonistas de Aminoácidos Excitadores/farmacocinética , Antagonistas de Aminoácidos Excitadores/farmacología , Humanos , Masculino , Modelos Moleculares , Simulación del Acoplamiento Molecular , Estructura Molecular , Actividad Motora/efectos de los fármacos , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Fenciclidina/antagonistas & inhibidores , Fenciclidina/farmacología , Unión Proteica , Ratas , Ratas Sprague-DawleyRESUMEN
BACKGROUND: Conventional antidepressants lack efficacy for many patients (treatmentresistant depression or TRD) and generally take weeks to produce full therapeutic response in others. Emerging data has identified certain drugs such as ketamine as rapidly-acting antidepressants for major depressive disorder and TRD. Scopolamine, a drug used to treat motion sickness and nausea, has also been demonstrated to function as a rapidly-acting antidepressant. The mechanisms associated with efficacy in TRD patients and rapid onset of action have been suggested to involve a-Amino-3-hydroxy- 5-methyl-4-isoxazolepropionic acid (AMPA) receptor and mammalian target of rapamycin (mTOR) signaling. Since the work on these mechanisms with scopolamine has been limited, the present set of experiments was designed to further explore these mechanisms of action. METHOD: Male, NIH Swiss mice demonstrated a robust and immediate antidepressant signature with ketamine or scopolamine when studied under the forced-swim test. RESULTS: The AMPA receptor antagonist NBQX prevented this antidepressant-like effect of scopolamine and ketamine. An orally-bioavilable mTOR inhibitor (AZD8055) also attenuated the antidepressant- like effects of scopolamine and ketamine. Scopolamine was also shown to augment the antidepressant- like effect of the selective serotonin reuptake inhibitor citalopram. When given in combination, scopolamine and ketamine acted synergistically to produce antidepressant-like effects. Although drug interaction data suggested that additional mechanisms might be at play, metabolomic analysis of frontal cortex and plasma from muscarinic M1+/+ and M1 -/- mice given scopolamine or vehicle did not reveal any hints as to the nature of these additional mechanisms of action. CONCLUSION: Overall, the data substantiate and extend the idea that AMPA and mTOR signaling pathways are necessary for the antidepressant-like effects of scopolamine and ketamine, mechanisms that appear to be of general significance for TRD therapeutic agents.
Asunto(s)
Antidepresivos/farmacología , Trastorno Depresivo/tratamiento farmacológico , Escopolamina/farmacología , Animales , Citalopram/farmacología , Trastorno Depresivo/metabolismo , Interacciones Farmacológicas , Quimioterapia Combinada , Antagonistas de Aminoácidos Excitadores/farmacología , Lóbulo Frontal/efectos de los fármacos , Lóbulo Frontal/metabolismo , Ketamina/farmacología , Masculino , Metaboloma/efectos de los fármacos , Ratones Endogámicos C57BL , Ratones Noqueados , Morfolinas/farmacología , Quinoxalinas/farmacología , Receptor Muscarínico M1/genética , Receptor Muscarínico M1/metabolismo , Receptores AMPA/antagonistas & inhibidores , Receptores AMPA/metabolismo , Inhibidores Selectivos de la Recaptación de Serotonina/farmacología , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Serina-Treonina Quinasas TOR/metabolismoRESUMEN
BACKGROUND & OBJECTIVE: 6-[(1S)-1-[1-[5-(2-hydroxyethoxy)-2-pyridyl]pyrazol-3-yl]ethyl]- 3H-1,3-benzothiazol-2-one (LY3130481 or CERC-611) is a selective antagonist of AMPA receptors containing transmembrane AMPA receptor regulatory protein (TARP) γ-8 that is under development for epilepsy. The present study provided a broad inquiry into its anticonvulsant properties. LY3130481 was anticonvulsant in multiple acute seizure provocation models in mice and rats. In addition, LY3130481 was effective against absence seizures in the GAERS genetic model and in the Frings mouse model. Likewise, LY3130481 attenuated convulsions in mice and rats with long-term induction of seizures (e.g., corneal, pentylenetetrazole, hippocampal, and amygdala kindled seizures). In slices of epileptic human cortex, LY3130481 significantly decreased neuronal firing frequencies. LY3130481 displaced from rat brain a radioligand specific for AMPA receptors associated with TARP γ-8 whereas non-TARP-selective molecules did not. Binding was also observed in hippocampus freshly transected from a patient. RESULTS & CONCLUSION: Taken as a whole, the findings reported here establish the broad anticonvulsant efficacy of LY3130481 indicating that blockade of AMPA receptors associated with TARP γ-8 is sufficient for these protective effects.
Asunto(s)
Benzotiazoles/farmacología , Canales de Calcio/metabolismo , Pirazoles/farmacología , Receptores AMPA/antagonistas & inhibidores , Convulsiones/prevención & control , Animales , Anticonvulsivantes/farmacología , Corteza Cerebral/fisiología , Modelos Animales de Enfermedad , Femenino , Humanos , Masculino , Ratones , Neuronas/fisiología , Ensayo de Unión Radioligante , RatasRESUMEN
Pharmacological manipulation of specific neural circuits to optimize therapeutic index is an unrealized goal in neurology and psychiatry. AMPA receptors are important for excitatory synaptic transmission, and their antagonists are antiepileptic. Although efficacious, AMPA-receptor antagonists, including perampanel (Fycompa), the only approved antagonist for epilepsy, induce dizziness and motor impairment. We hypothesized that blockade of forebrain AMPA receptors without blocking cerebellar AMPA receptors would be antiepileptic and devoid of motor impairment. Taking advantage of an AMPA receptor auxiliary protein, TARP γ-8, which is selectively expressed in the forebrain and modulates the pharmacological properties of AMPA receptors, we discovered that LY3130481 selectively antagonized recombinant and native AMPA receptors containing γ-8, but not γ-2 (cerebellum) or other TARP members. Two amino acid residues unique to γ-8 determined this selectivity. We also observed antagonism of AMPA receptors expressed in hippocampal, but not cerebellar, tissue from an patient with epilepsy. Corresponding to this selective activity, LY3130481 prevented multiple seizure types in rats and mice and without motor side effects. These findings demonstrate the first rationally discovered molecule targeting specific neural circuitries for therapeutic advantage.
Asunto(s)
Anticonvulsivantes/farmacología , Benzotiazoles/farmacología , Cerebelo/efectos de los fármacos , Epilepsia/tratamiento farmacológico , Prosencéfalo/efectos de los fármacos , Pirazoles/farmacología , Piridonas/farmacología , Receptores AMPA/antagonistas & inhibidores , Animales , Anticonvulsivantes/efectos adversos , Canales de Calcio/metabolismo , Cerebelo/metabolismo , Convulsivantes/toxicidad , Modelos Animales de Enfermedad , Mareo/inducido químicamente , Epilepsia/inducido químicamente , Ratones , Nitrilos , Pentilenotetrazol/toxicidad , Prosencéfalo/metabolismo , Piridonas/efectos adversos , Ratas , Receptores AMPA/metabolismo , Convulsiones/inducido químicamente , Convulsiones/tratamiento farmacológicoRESUMEN
Nociceptin/Orphanin FQ (N/OFQ) is a 17 amino acid peptide whose receptor is designated ORL1 or nociceptin receptor (NOP). We utilized a potent, selective, and orally bioavailable antagonist with documented engagement with NOP receptors in vivo to assess antidepressant- and anxiolytic-related pharmacological effects of NOP receptor blockade along with measures of cognitive and motor impingement. LY2940094 ([2-[4-[(2-chloro-4,4-difluoro-spiro[5H-thieno[2,3-c]pyran-7,4'-piperidine]-1'-yl)methyl]-3-methyl-pyrazol-1-yl]-3-pyridyl]methanol) displayed antidepressant-like behavioral effects in the forced-swim test in mice, an effect absent in NOP -/- mice. LY2940094 also augmented the behavioral effect of fluoxetine without changing target occupancies (NOP and serotonin reuptake transporter [SERT]). LY2940094 did not have effects under a differential-reinforcement of low rate schedule. Although anxiolytic-like effects were not observed in some animal models (conditioned suppression, 4-plate test, novelty-suppressed feeding), LY2940094 had effects like that of anxiolytic drugs in three assays: fear-conditioned freezing in mice, stress-induced increases in cerebellar cGMP in mice, and stress-induced hyperthermia in rats. These are the first reports of anxiolytic-like activity with a systemically viable NOP receptor antagonist. LY2940094 did not disrupt performance in either a 5-choice serial reaction time or delayed matching-to-position assay. LY2940094 was also not an activator or suppressor of locomotion in rodents nor did it induce failures of rotarod performance. These data suggest that LY2940094 has unique antidepressant- and anxiolytic-related pharmacological effects in rodents. Clinical proof of concept data on this molecule in depressed patients have been reported elsewhere.
RESUMEN
As part of our ongoing efforts to identify novel ligands for the metabotropic glutamate 2 and 3 (mGlu2/3) receptors, we have incorporated substitution at the C3 and C4 positions of the (1S,2R,5R,6R)-2-amino-bicyclo[3.1.0]hexane-2,6-dicarboxylic acid scaffold to generate mGlu2/3 antagonists. Exploration of this structure-activity relationship (SAR) led to the identification of (1S,2R,3S,4S,5R,6R)-2-amino-3-[(3,4-difluorophenyl)sulfanylmethyl]-4-hydroxy-bicyclo[3.1.0]hexane-2,6-dicarboxylic acid hydrochloride (LY3020371·HCl, 19f), a potent, selective, and maximally efficacious mGlu2/3 antagonist. Further characterization of compound 19f binding to the human metabotropic 2 glutamate (hmGlu2) site was established by cocrystallization of this molecule with the amino terminal domain (ATD) of the hmGlu2 receptor protein. The resulting cocrystal structure revealed the specific ligand-protein interactions, which likely explain the high affinity of 19f for this site and support its functional mGlu2 antagonist pharmacology. Further characterization of 19f in vivo demonstrated an antidepressant-like signature in the mouse forced-swim test (mFST) assay when brain levels of this compound exceeded the cellular mGlu2 IC50 value.
Asunto(s)
Antidepresivos/farmacología , Conducta Animal/efectos de los fármacos , Descubrimiento de Drogas , Receptores de Glutamato Metabotrópico/antagonistas & inhibidores , Animales , Antidepresivos/síntesis química , Antidepresivos/química , Encéfalo/efectos de los fármacos , Ciclohexanos/síntesis química , Ciclohexanos/química , Ciclohexanos/farmacología , Relación Dosis-Respuesta a Droga , Humanos , Masculino , Ratones , Ratones Endogámicos , Modelos Moleculares , Estructura Molecular , Actividad Motora/efectos de los fármacos , Receptores de Glutamato Metabotrópico/química , Receptores de Glutamato Metabotrópico/aislamiento & purificación , Relación Estructura-Actividad , NataciónRESUMEN
As part of our ongoing research to identify novel agents acting at metabotropic glutamate 2 (mGlu2) and 3 (mGlu3) receptors, we have previously reported the identification of the C4α-methyl analog of mGlu2/3 receptor agonist 1 (LY354740). This molecule, 1S,2S,4R,5R,6S-2-amino-4-methylbicyclo[3.1.0]hexane-2,6-dicarboxylate 2 (LY541850), exhibited an unexpected mGlu2 agonist/mGlu3 antagonist pharmacological profile, whereas the C4ß-methyl diastereomer (3) possessed dual mGlu2/3 receptor agonist activity. We have now further explored this structure-activity relationship through the preparation of cyclic and acyclic C4-disubstituted analogs of 1, leading to the identification of C4-spirocyclopropane 5 (LY2934747), a novel, potent, and systemically bioavailable mGlu2/3 receptor agonist which exhibits both antipsychotic and analgesic properties in vivo. In addition, through the combined use of protein-ligand X-ray crystallography employing recombinant human mGlu2/3 receptor amino terminal domains, molecular modeling, and site-directed mutagenesis, a molecular basis for the observed pharmacological profile of compound 2 is proposed.
Asunto(s)
Compuestos Bicíclicos con Puentes/farmacología , Receptores de Glutamato Metabotrópico/agonistas , Compuestos de Espiro/farmacología , Animales , Compuestos Bicíclicos con Puentes/química , Compuestos Bicíclicos con Puentes/metabolismo , Cristalografía por Rayos X , Humanos , Masculino , Modelos Moleculares , Estructura Terciaria de Proteína , Ratas , Ratas Sprague-Dawley , Receptores de Glutamato Metabotrópico/química , Receptores de Glutamato Metabotrópico/genética , Compuestos de Espiro/química , Compuestos de Espiro/metabolismoRESUMEN
Identification of orthosteric mGlu(2/3) receptor agonists capable of discriminating between individual mGlu2 and mGlu3 subtypes has been highly challenging owing to the glutamate-site sequence homology between these proteins. Herein we detail the preparation and characterization of a series of molecules related to (1S,2S,5R,6S)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylate 1 (LY354740) bearing C4-thiotriazole substituents. On the basis of second messenger responses in cells expressing other recombinant human mGlu2/3 subtypes, a number of high potency and efficacy mGlu2 receptor agonists exhibiting low potency mGlu3 partial agonist/antagonist activity were identified. From this, (1R,2S,4R,5R,6R)-2-amino-4-(1H-1,2,4-triazol-3-ylsulfanyl)bicyclo[3.1.0]hexane-2,6-dicarboxylic acid 14a (LY2812223) was further characterized. Cocrystallization of 14a with the amino terminal domains of hmGlu2 and hmGlu3 combined with site-directed mutation studies has clarified the underlying molecular basis of this unique pharmacology. Evaluation of 14a in a rat model responsive to mGlu2 receptor activation coupled with a measure of central drug disposition provides evidence that this molecule engages and activates central mGlu2 receptors in vivo.
Asunto(s)
Compuestos Bicíclicos con Puentes/química , Receptores de Glutamato Metabotrópico/agonistas , Triazoles/química , Regulación Alostérica , Animales , Unión Competitiva , Compuestos Bicíclicos con Puentes/farmacocinética , Compuestos Bicíclicos con Puentes/farmacología , Calcio/metabolismo , AMP Cíclico/metabolismo , Perros , Agonismo Parcial de Drogas , Humanos , Masculino , Ratones , Modelos Moleculares , Actividad Motora/efectos de los fármacos , Mutagénesis Sitio-Dirigida , Estructura Terciaria de Proteína , Ratas Sprague-Dawley , Receptores de Glutamato Metabotrópico/antagonistas & inhibidores , Receptores de Glutamato Metabotrópico/genética , Receptores de Glutamato Metabotrópico/metabolismo , Estereoisomerismo , Triazoles/farmacocinética , Triazoles/farmacologíaRESUMEN
Curcumin, the major constituent of the spice tumeric produces a plethora of biological actions that have translated in vivo into behavioral and neurochemical effects in rodents that are also produced by clinically-used antidepressants. The present study was designed to provide a systematic replication of prior behavioral, pharmacological, and neurochemical experiments. In particular, the ability of curcumin to engender anti-immobility effects in the mouse forced-swim assay was established. Although prior work had shown curcumin to function as an inhibitor of the monoamine metabolizing enzyme, monoamine oxidase (MAO), neither MAOA nor MAOB was inhibitied by curcumin in the present study. Curcumin had also been reported previously to function as a cannabinoid CB1 receptor inverse agonist/antagonist. However, in our hands, curcumin did not potently alter GTP-γ.-35S binding indicative of functional CB1 antagonism (Kb = 2080 nM). Moreover, curcumin was not able to prevent the hypothermic effects of the cannabinoid receptor agonist (-)-cis-3-[2-Hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol (CP 55,940). Nonetheless, the anti-immobility effects of curcumin did not occur in CB1 -/- mice. Finally, a broad array of protein receptors and enzymes were evaluated in vitro for their potential interaction with and/or functional engagement with curcumin. Of the more than 100 targets screened, curcumin had very low potency in most. Of those targets with appreciable activity, curcumin had affinities for the human cloned muscarinic receptor subtypes (Ki = 1.3-3.1 uM). Moreover, the plasma and brain levels of curcumin at behaviorally-active doses were below quantitative limits. Given these findings, it is concluded that the prominent antidepressant-like behavioral effects of curcumin, replicated here and in multiple acute and chronic rodent models detailed in the literature, are the result of as yet undisclosed mechanisms of action. The scientific and patient communities await the full scale clinical evaluation of a sufficiently bioavailable curcumin analog in major depressive disorder.
Asunto(s)
Antidepresivos/uso terapéutico , Curcumina/uso terapéutico , Depresión/tratamiento farmacológico , Animales , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Curcumina/farmacología , Ciclohexanoles/farmacología , Depresión/sangre , Depresión/patología , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Inmunosupresores/farmacología , Masculino , Ratones , Ratones Noqueados , Inhibidores de la Monoaminooxidasa/farmacología , Inhibidores de la Monoaminooxidasa/uso terapéutico , Unión Proteica/efectos de los fármacos , Receptor Cannabinoide CB1/deficiencia , Receptor Cannabinoide CB1/metabolismo , Receptores de Amina Biogénica/metabolismo , Natación/psicologíaRESUMEN
As part of our ongoing interest in identifying novel agonists acting at metabotropic glutamate (mGlu) 2/3 receptors, we have explored the effect of structural modifications of 1S,2S,5R,6S-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylate (LY354740), a potent and pharmacologically balanced mGlu2/3 receptor agonist. Incorporation of relatively small substituents (e.g., F, O) at the C4 position of this molecule resulted in additional highly potent mGlu2/3 agonists that demonstrate excellent selectivity over the other mGlu receptor subtypes, while addition of larger C4-substituents (e.g., SPh) led to a loss of agonist potency and/or the appearance of weak mGlu2/3 receptor antagonist activity. Further characterization of the α-fluoro-substituted analogue (LY459477) in vivo revealed that this molecule possesses good oral bioavailability in rats and effectively suppresses phencyclidine-evoked locomotor activity at doses that do not impair neuromuscular coordination. This molecule therefore represents a valuable new addition to the arsenal of pharmacological tools competent to investigate mGlu2/3 receptor function both in vitro and in vivo.
Asunto(s)
Aminoácidos Dicarboxílicos/síntesis química , Antipsicóticos/síntesis química , Compuestos Bicíclicos con Puentes/síntesis química , Ciclohexanos/síntesis química , Receptores de Glutamato Metabotrópico/agonistas , Administración Oral , Aminoácidos Dicarboxílicos/farmacocinética , Aminoácidos Dicarboxílicos/farmacología , Animales , Antipsicóticos/farmacocinética , Antipsicóticos/farmacología , Compuestos Bicíclicos con Puentes/farmacocinética , Compuestos Bicíclicos con Puentes/farmacología , Ciclohexanos/farmacocinética , Ciclohexanos/farmacología , Humanos , Masculino , Modelos Moleculares , Actividad Motora/efectos de los fármacos , Trastornos Psicóticos/tratamiento farmacológico , Trastornos Psicóticos/psicología , Ratas , Ratas Sprague-Dawley , Receptores de Glutamato Metabotrópico/metabolismo , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
Group II metabotropic glutamate (mGlu) receptor agonists, including (1S,2S,5R,6S)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylate monohydrate (LY354740) and (-)-2-oxa-4-aminobicyclo[3.1.0]hexane-4,6-dicarboxylate (LY379268), have demonstrated efficacy in animal models of anxiety and schizophrenia, and LY354740 decreased anxiety in human subjects. Herein, we report the in vitro pharmacological profile and pharmacokinetic properties of another potent, selective, and structurally novel mGlu2/3 receptor agonist, (-)-(1R,4S,5S,6S)-4-amino-2-sulfonylbicyclo[3.1.0]hexane-4,6-dicarboxylic acid (LY404039) and provide comparisons with LY354740. Similar to LY354740, LY404039 is a nanomolar potent agonist at recombinant human mGlu2 and mGlu3 receptors (K(i) = 149 and 92, respectively) and in rat neurons expressing native mGlu2/3 receptors (Ki = 88). LY404039 is highly selective for mGlu2/3 receptors, showing more than 100-fold selectivity for these receptors, versus ionotropic glutamate receptors, glutamate transporters, and other receptors targeted by known anxiolytic and antipsychotic medications. Functionally, LY404039 potently inhibited forskolin-stimulated cAMP formation in cells expressing human mGlu2 and mGlu3 receptors. Electrophysiological studies indicated that LY404039 suppressed electrically evoked excitatory activity in the striatum, and serotonin-induced l-glutamate release in the prefrontal cortex; effects reversed by LY341495. These characteristics suggest LY404039 modulates glutamatergic activity in limbic and forebrain areas relevant to psychiatric disorders; and that, similar to LY354740, it works through a mechanism that may be devoid of negative side effects associated with current antipsychotics and anxiolytics. Interestingly, despite the slightly lower potency (approximately 2-5-fold) of LY404039 versus LY354740 in binding, functional, and electrophysiological assays, LY404039 demonstrated higher plasma exposure and better oral bioavailability in pharmacokinetic experiments. Collectively, the current data indicate that LY404039 may be valuable in the treatment of neuropsychiatric disorders, including anxiety and psychosis.