RESUMEN
Combination studies of neurokinin 1 (NK1) receptor antagonists and serotonin-selective reuptake inhibitors (SSRIs) have shown promise in preclinical models of depression. Such a combination may offer important advantages over the current standard of care. Herein we describe the discovery and optimization of an indazole-based chemotype to provide a series of potent dual NK1 receptor antagonists/serotonin transporter (SERT) inhibitors to overcome issues of ion channel blockade. This effort culminated in the identification of compound 9, an analogue that demonstrated favorable oral bioavailability, excellent brain uptake, and robust in vivo efficacy in a validated depression model. Over the course of this work, a novel heterocycle-directed asymmetric hydrogenation was developed to facilitate installation of the key stereogenic center.
Asunto(s)
Antidepresivos/farmacología , Indazoles/farmacología , Antagonistas del Receptor de Neuroquinina-1/farmacología , Inhibidores Selectivos de la Recaptación de Serotonina/farmacología , Administración Oral , Animales , Antidepresivos/síntesis química , Antidepresivos/química , Antidepresivos/toxicidad , Trastorno Depresivo/tratamiento farmacológico , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Descubrimiento de Drogas , Evaluación Preclínica de Medicamentos , Gerbillinae , Humanos , Indazoles/síntesis química , Indazoles/química , Indazoles/toxicidad , Ratones , Estructura Molecular , Antagonistas del Receptor de Neuroquinina-1/síntesis química , Antagonistas del Receptor de Neuroquinina-1/química , Antagonistas del Receptor de Neuroquinina-1/toxicidad , Ratas , Receptores de Neuroquinina-1/metabolismo , Proteínas de Transporte de Serotonina en la Membrana Plasmática/metabolismo , Inhibidores Selectivos de la Recaptación de Serotonina/síntesis química , Inhibidores Selectivos de la Recaptación de Serotonina/química , Inhibidores Selectivos de la Recaptación de Serotonina/toxicidad , Relación Estructura-Actividad , Regulador Transcripcional ERG/metabolismoRESUMEN
The development of alpha7 nicotinic acetylcholine receptor agonists is considered a promising approach for the treatment of cognitive symptoms in schizophrenia patients. In the present studies we characterized the novel agent, (2R)-N-(6-(1H-imidazol-1-yl)-4-pyrimidinyl)-4'H-spiro[4-azabicyclo[2.2.2]octane-2,5'-[1,3]oxazol]-2'-amine (BMS-933043), in vitro and in rodent models of schizophrenia-like deficits in cognition and sensory processing. BMS-933043 showed potent binding affinity to native rat (Ki = 3.3 nM) and recombinant human alpha7 nicotinic acetylcholine receptors (Ki = 8.1 nM) and agonist activity in a calcium fluorescence assay (EC50 = 23.4 nM) and whole cell voltage clamp electrophysiology (EC50 = 0.14 micromolar (rat) and 0.29 micromolar (human)). BMS-933043 exhibited a partial agonist profile relative to acetylcholine; the relative efficacy for net charge crossing the cell membrane was 67% and 78% at rat and human alpha7 nicotinic acetylcholine receptors respectively. BMS-933043 showed no agonist or antagonist activity at other nicotinic acetylcholine receptor subtypes and was at least 300 fold weaker at binding to and antagonizing human 5-HT3A receptors (Ki = 2,451 nM; IC50 = 8,066 nM). BMS-933043 treatment i) improved 24 hour novel object recognition memory in mice (0.1-10 mg/kg, sc), ii) reversed MK-801-induced deficits in Y maze performance in mice (1-10 mg/kg, sc) and set shift performance in rats (1-10 mg/kg, po) and iii) reduced the number of trials required to complete the extradimensional shift discrimination in neonatal PCP treated rats performing the intra-dimensional/extradimensional set shifting task (0.1-3 mg/kg, po). BMS-933043 also improved auditory gating (0.56-3 mg/kg, sc) and mismatch negativity (0.03-3 mg/kg, sc) in rats treated with S(+)ketamine or neonatal phencyclidine respectively. Given this favorable preclinical profile BMS-933043 was selected for further development to support clinical evaluation in humans.
Asunto(s)
Trastornos del Conocimiento/tratamiento farmacológico , Quinuclidinas/uso terapéutico , Esquizofrenia/tratamiento farmacológico , Compuestos de Espiro/uso terapéutico , Receptor Nicotínico de Acetilcolina alfa 7/agonistas , Animales , Trastornos del Conocimiento/fisiopatología , Evaluación Preclínica de Medicamentos , Células HEK293 , Humanos , Masculino , Ratones , Técnicas de Placa-Clamp , Quinuclidinas/farmacología , Ensayo de Unión Radioligante , Ratas , Esquizofrenia/fisiopatología , Compuestos de Espiro/farmacologíaRESUMEN
Patients with schizophrenia show marked deficits in processing sensory inputs including a reduction in the generation and synchronization of 40 Hz gamma oscillations in response to steady-state auditory stimulation. Such deficits are not readily demonstrable at other input frequencies. Acute administration of NMDA antagonists to healthy human subjects or laboratory animals is known to reproduce many sensory and cognitive deficits seen in schizophrenia patients. In the following study, we tested the hypothesis that the NMDA antagonist MK-801 would selectively disrupt steady-state gamma entrainment in the auditory cortex of urethane-anesthetized rat. Moreover, we further hypothesized that nicotinic receptor activation would alleviate this disruption. Auditory steady state responses were recorded in response to auditory stimuli delivered over a range of frequencies (10-80 Hz) and averaged over 50 trials. Evoked power was computed under baseline condition and after vehicle or MK-801 (0.03 mg/kg, iv). MK-801 produced a significant attenuation in response to 40 Hz auditory stimuli while entrainment to other frequencies was not affected. Time-frequency analysis revealed deficits in both power and phase-locking to 40 Hz. Nicotine (0.1 mg/kg, iv) administered after MK-801 reversed the attenuation of the 40 Hz response. Administered alone, nicotine augmented 40 Hz steady state power and phase-locking. Nicotine's effects were blocked by simultaneous administration of the α4ß2 antagonist DHßE. Thus we report for the first time, a rodent model that mimics a core neurophysiological deficit seen in patients with schizophrenia and a pharmacological approach to alleviate it.
Asunto(s)
Corteza Auditiva/efectos de los fármacos , Ondas Encefálicas/efectos de los fármacos , Maleato de Dizocilpina/farmacología , Nicotina/farmacología , Estimulación Acústica , Anestésicos Intravenosos/farmacología , Animales , Corteza Auditiva/fisiología , Ondas Encefálicas/fisiología , Dihidro-beta-Eritroidina/farmacología , Maleato de Dizocilpina/antagonistas & inhibidores , Potenciales Evocados Auditivos/efectos de los fármacos , Potenciales Evocados Auditivos/fisiología , Antagonistas de Aminoácidos Excitadores/farmacología , Masculino , Nicotina/antagonistas & inhibidores , Agonistas Nicotínicos/farmacología , Antagonistas Nicotínicos/farmacología , Ratas , Uretano/farmacologíaRESUMEN
High throughput screening led to the identification of a novel series of quinolone α7 nicotinic acetylcholine receptor (nAChR) agonists. Optimization of an HTS hit (1) led to 4-phenyl-1-(quinuclidin-3-ylmethyl)quinolin-2(1H)-one, which was found to be potent and selective. Poor brain penetrance in this series was attributed to transporter-mediated efflux, which was in turn due to high pKa. A novel 4-fluoroquinuclidine significantly lowered the pKa of the quinuclidine moiety, reducing efflux as measured by a Caco-2 assay.
Asunto(s)
Agonistas Nicotínicos/química , Quinolonas/química , Receptores Nicotínicos/química , Animales , Células CACO-2 , Evaluación Preclínica de Medicamentos , Humanos , Cinética , Agonistas Nicotínicos/síntesis química , Agonistas Nicotínicos/metabolismo , Quinolonas/síntesis química , Quinolonas/metabolismo , Ratas , Receptores Nicotínicos/metabolismo , Relación Estructura-Actividad , Receptor Nicotínico de Acetilcolina alfa 7RESUMEN
We report here on a chemical genetic screen designed to address the mechanism of action of a small molecule. Small molecules that were active in models of urinary incontinence were tested on the nematode Caenorhabditis elegans, and the resulting phenotypes were used as readouts in a genetic screen to identify possible molecular targets. The mutations giving resistance to compound were found to affect members of the RGS protein/G-protein complex. Studies in mammalian systems confirmed that the small molecules inhibit muscarinic G-protein coupled receptor (GPCR) signaling involving G-alphaq (G-protein alpha subunit). Our studies suggest that the small molecules act at the level of the RGS/G-alphaq signaling complex, and define new mutations in both RGS and G-alphaq, including a unique hypo-adapation allele of G-alphaq. These findings suggest that therapeutics targeted to downstream components of GPCR signaling may be effective for treatment of diseases involving inappropriate receptor activation.