ABSTRACT
The α7 nicotinic acetylcholine receptor is a calcium permeable, ligand-gated ion channel that modulates synaptic transmission in the hippocampus, thalamus, and cerebral cortex. Previously disclosed work described PNU-120596 that acts as a powerful positive allosteric modulator of the α7 nicotinic acetylcholine receptor. The initial structure-activity relationships around PNU-120596 were gleaned from screening a large thiazole library. Independent systematic examination of the aryl and heteroaryl groups resulted in compounds with enhanced potency and improved physico-chemical properties culminating in the identification of 16 (PHA-758454). In the presence of acetylcholine, 16 enhanced evoked currents in rat hippocampal neurons. In a rat model of impaired sensory gating, treatment with 16 led to a reversal of the gating deficit in a dose-dependent manner. These results demonstrate that aryl heteroaryl ureas, like compound 16, may be useful tools for continued exploration of the unique biology of the α7 nicotinic acetylcholine receptor.
Subject(s)
Receptors, Nicotinic , alpha7 Nicotinic Acetylcholine Receptor , Rats , Animals , Hippocampus , Phenylurea Compounds/chemistry , Isoxazoles/pharmacology , Isoxazoles/chemistry , Allosteric RegulationABSTRACT
The objective of the described research effort was to identify a novel serotonin and norepinephrine reuptake inhibitor (SNRI) with improved norepinephrine transporter activity and acceptable metabolic stability and exhibiting minimal drug-drug interaction. We describe herein the discovery of a series of 3-substituted pyrrolidines, exemplified by compound 1. Compound 1 is a selective SNRI in vitro and in vivo, has favorable ADME properties, and retains inhibitory activity in the formalin model of pain behavior. Compound 1 thus represents a potential new probe to explore utility of SNRIs in central nervous system disorders, including chronic pain conditions.
ABSTRACT
A novel alpha7 nAChR agonist, N-[(3R,5R)-1-azabicyclo[3.2.1]oct-3-yl]furo[2,3-c]pyridine-5-carboxamide (3a, PHA-709829), has been identified for the potential treatment of cognitive deficits in schizophrenia. The compound shows potent and selective alpha7 in vitro activity, excellent brain penetration, good rat oral bioavailability and robust in vivo efficacy in a rat auditory sensory gating model.
Subject(s)
Azabicyclo Compounds/pharmacology , Nicotinic Agonists/pharmacology , Pyridines/pharmacology , Receptors, Nicotinic/drug effects , Animals , Azabicyclo Compounds/chemical synthesis , Azabicyclo Compounds/chemistry , Benzamides/pharmacology , Blood Proteins/drug effects , Bridged Bicyclo Compounds/pharmacology , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Dogs , Dose-Response Relationship, Drug , Humans , Mice , Microsomes, Liver/drug effects , Molecular Conformation , Nicotinic Agonists/chemical synthesis , Nicotinic Agonists/chemistry , Pyridines/chemical synthesis , Pyridines/chemistry , Quinuclidines/pharmacology , Rats , Receptors, Muscarinic/drug effects , Stereoisomerism , Structure-Activity Relationship , alpha7 Nicotinic Acetylcholine ReceptorABSTRACT
A novel set of azabicyclic aryl amides have been identified as potent and selective agonists of the alpha7 nAChR. A two-pronged approach was taken to improve the potential hERG liability of previously disclosed alpha7 nAChR agonist, PNU-282,987, while maintaining the compound's other desirable pharmacological properties. The first approach involved further exploration of the aryl carboxylic acid fragment of PNU-282,987, while the second approach focused on modification of the azabicyclic amine portion of PNU-282,987. The best compounds from each series are characterized by rapid brain penetration, good oral bioavailability in rat, and demonstrate in vivo efficacy in a rat P50 auditory sensory gating assay. At least one analog from each series (1h, 1o, 2a, 9a, and 18a) shows an improved hERG safety profile over PNU-282,987.
Subject(s)
Brain/metabolism , Drug Design , Nicotinic Agonists/pharmacology , Receptors, Nicotinic/chemistry , Animals , Bungarotoxins , Cells, Cultured , Electrophysiology , Evoked Potentials, Auditory/drug effects , Hippocampus/drug effects , Ion Channel Gating/drug effects , Molecular Structure , Motor Activity/drug effects , Neurons/drug effects , Nicotinic Agonists/chemical synthesis , Nicotinic Agonists/chemistry , Patch-Clamp Techniques , Rats , Rats, Sprague-Dawley , Structure-Activity Relationship , Synapses/drug effects , Synapses/physiology , alpha7 Nicotinic Acetylcholine ReceptorABSTRACT
N-[(3R)-1-Azabicyclo[2.2.2]oct-3-yl]furo[2,3-c]pyridine-5-carboxamide (14, PHA-543,613), a novel agonist of the alpha7 neuronal nicotinic acetylcholine receptor (alpha7 nAChR), has been identified as a potential treatment of cognitive deficits in schizophrenia. Compound 14 is a potent and selective alpha7 nAChR agonist with an excellent in vitro profile. The compound is characterized by rapid brain penetration and high oral bioavailability in rat and demonstrates in vivo efficacy in auditory sensory gating and, in an in vivo model to assess cognitive performance, novel object recognition.
Subject(s)
Bridged Bicyclo Compounds, Heterocyclic/chemical synthesis , Cognition Disorders/drug therapy , Nicotinic Agonists/chemical synthesis , Nootropic Agents/chemical synthesis , Quinuclidines/chemical synthesis , Receptors, Nicotinic/metabolism , Schizophrenia/drug therapy , Animals , Biological Availability , Brain/metabolism , Bridged Bicyclo Compounds, Heterocyclic/chemistry , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Drug Stability , Ether-A-Go-Go Potassium Channels/drug effects , Evoked Potentials, Auditory/drug effects , Humans , In Vitro Techniques , Learning/drug effects , Male , Memory/drug effects , Microsomes, Liver/drug effects , Microsomes, Liver/metabolism , Neurons/drug effects , Neurons/physiology , Nicotinic Agonists/pharmacokinetics , Nicotinic Agonists/pharmacology , Nootropic Agents/pharmacokinetics , Nootropic Agents/pharmacology , Patch-Clamp Techniques , Quinuclidines/chemistry , Quinuclidines/pharmacology , Radioligand Assay , Rats , Rats, Sprague-Dawley , Receptors, Nicotinic/physiology , Recognition, Psychology/drug effects , Stereoisomerism , Structure-Activity Relationship , alpha7 Nicotinic Acetylcholine ReceptorABSTRACT
A library of benzamides was tested for alpha7 nicotinic acetylcholine receptor (nAChR) agonist activity using a chimeric receptor in a functional, cell-based, high-throughput assay. From this library, quinuclidine benzamides were found to have alpha7 nAChR agonist activity. The SAR diverged from the activity of this compound class verses the 5-HT(3) receptor, a structural homologue of the alpha7 nAChR. PNU-282987, the most potent compound from this series, was also shown to open native alpha7 nAChRs in cultured rat neurons and to reverse an amphetamine-induced gating deficit in rats.
