ABSTRACT
Orphanin FQ/nociceptin (OFQ/N) is the endogenously occurring peptide ligand for the nociceptin opioid receptor (NOP) that produces anxiolytic-like effects in mice and rats. The present study assessed the anxiolytic-like activity of 8-[bis(2-methylphenyl)-methyl]-3-phenyl-8-azabicyclo[3.2.1]octan-3-ol (SCH 221510), a novel potent piperidine NOP agonist (EC(50) = 12 nM) that binds with high affinity (K(i) = 0.3 nM) and functional selectivity (>50-fold over the mu-, kappa-, and delta-opioid receptors). The anxiolytic-like activity and side-effect profile of SCH 221510 were assessed in a variety of models and the benzodiazepine, chlordiazepoxide (CDP), was included for comparison. The effects of chronic dosing of SCH 221510 were also assessed. Furthermore, the specificity of the anxiolytic-like effect of SCH 221510 was investigated with the NOP receptor antagonist 1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one (J-113397) and the opioid receptor antagonist naltrexone. Like CDP (1-30 mg/kg i.p.), SCH 221510 (1-30 mg/kg p.o.) produced anxiolytic-like effects in the elevated plus-maze (rat and gerbil), Vogel conflict (rat), conditioned lick suppression (rat), fear-potentiated startle (rat), and pup separation-induced vocalization (guinea pig) assays. In the Vogel conflict, the anxiolytic-like effect of SCH 221510 (10 mg/kg) was attenuated by J-113397 (3-10 mg/kg p.o.), but not naltrexone (3-30 mg/kg i.p.). Additionally, the anxiolytic-like effects of SCH 221510 did not change appreciably following 14-day b.i.d. dosing in rats (10 mg/kg). Furthermore, unlike CDP, SCH 221510 (3-30 mg/kg) produced anxiolytic-like activity at doses that did not disrupt overt behavior. Collectively, these data suggest that NOP agonists such as SCH 221510 may have an anxiolytic-like profile similar to benzodiazepines, with a reduced side-effect liability.
Subject(s)
Anti-Anxiety Agents/pharmacology , Azabicyclo Compounds/pharmacology , Behavior, Animal/drug effects , Receptors, Opioid/agonists , Animals , Animals, Newborn , Anti-Anxiety Agents/chemistry , Azabicyclo Compounds/chemistry , Benzimidazoles/pharmacology , CHO Cells , Cricetinae , Cricetulus , Female , Gerbillinae , Guinea Pigs , Humans , Male , Molecular Structure , Narcotic Antagonists , Piperidines/pharmacology , Protein Binding , Rats , Rats, Wistar , Receptors, Opioid/metabolism , Nociceptin ReceptorABSTRACT
A series of novel five-membered urea derivatives as potent NK1 receptor antagonists is described. The effects of substitution of a 4-fluoro group at the phenyl ring and the introduction of an alpha-methyl group at the benzylic position to improve potency and duration of in vivo activity are discussed. Several compounds with high affinity and sustained in vivo activity were identified.
Subject(s)
Anti-Anxiety Agents/chemistry , Anti-Anxiety Agents/pharmacology , Neurokinin-1 Receptor Antagonists , Urea/analogs & derivatives , Urea/pharmacology , Animals , Anti-Anxiety Agents/chemical synthesis , Benzyl Alcohols/chemistry , Crystallography, X-Ray , Drug Evaluation, Preclinical , Fluorine/chemistry , Gerbillinae , Models, Molecular , Molecular Structure , Motor Activity/drug effects , Structure-Activity Relationship , Urea/chemical synthesisABSTRACT
A series of novel five- and six-membered ring urea derivatives have been described as potent and selective NK1 receptor antagonists. Several compounds in this series exhibited good oral activity and brain penetration. Syntheses of these compounds are also described herein.
Subject(s)
Neurokinin-1 Receptor Antagonists , Urea/analogs & derivatives , Animals , Biological Availability , Dose-Response Relationship, Drug , Gerbillinae , Heterocyclic Compounds/chemical synthesis , Heterocyclic Compounds/pharmacokinetics , Heterocyclic Compounds/pharmacology , Motor Activity/drug effects , Protein Binding , Rats , Structure-Activity Relationship , Urea/pharmacokinetics , Urea/pharmacologyABSTRACT
In search of a backup M(2) muscarinic receptor antagonist to the previously reported compound 1, we discovered compound (+)-14, which showed superior oral efficacy in animal models. The improvement of oral efficacy was achieved by modulating both the molecular weight and lipophilicity of the lead compounds.
Subject(s)
Autoreceptors/antagonists & inhibitors , Central Nervous System Agents/chemical synthesis , Muscarinic Antagonists/chemical synthesis , Piperidines/chemical synthesis , Receptors, Muscarinic/drug effects , Acetylcholine/metabolism , Administration, Oral , Animals , Avoidance Learning/drug effects , Central Nervous System Agents/chemistry , Central Nervous System Agents/pharmacology , Corpus Striatum/metabolism , Humans , In Vitro Techniques , Microdialysis , Molecular Conformation , Muscarinic Antagonists/chemistry , Muscarinic Antagonists/pharmacology , Piperidines/chemistry , Piperidines/pharmacology , Rats , Receptor, Muscarinic M2 , Structure-Activity RelationshipABSTRACT
We previously reported the initial discovery of a novel class of stabilized benzylidene ketal M(2) receptor antagonists. This paper discusses new analogues consisting of benzamide modifications which not only improved M(2) receptor affinity and selectivity, but also enhanced the pharmacokinetic properties of the series. These changes led to the discovery of a highly potent and selective M(2) antagonist, which demonstrated in vivo efficacy and had good bioavailability in multiple species.
Subject(s)
Benzamides/chemistry , Benzylidene Compounds/chemistry , Benzylidene Compounds/pharmacokinetics , Muscarinic Antagonists/chemistry , Muscarinic Antagonists/pharmacology , Receptors, Muscarinic/drug effects , Acetylcholine/analysis , Acetylcholine/biosynthesis , Animals , Area Under Curve , Benzamides/pharmacology , Drug Design , Drug Evaluation, Preclinical , Humans , Microdialysis , Microsomes, Liver/drug effects , Microsomes, Liver/metabolism , Rats , Receptors, Muscarinic/metabolism , Structure-Activity RelationshipABSTRACT
Several neurokinin NK1 receptor antagonists currently being developed for anxiety and depression have reduced affinity for the rat and mouse NK1 receptor compared with human. Consequently, it has proven difficult to test these agents in traditional rat and mouse models of anxiety and depression. This issue has been overcome, in part, by using non-traditional lab species such as the guinea pig and gerbil, which have NK1 receptors closer in homology to human NK1 receptors. However, there are very few reports describing the behavior of gerbils in traditional models of anxiety. The aim of the present study was to determine if the elevated plus-maze, a commonly used anxiety model, could be adapted for the gerbil. Using a specially-designed elevated plus-maze, gerbils exhibited an 'anxious' behavioral profile similar to that observed in rats and mice, i.e., reduced entries into, and time spent exploring, an open, aversive arm. The anxiolytic drugs diazepam (0.03-3 mg/kg i.p.), chlordiazepoxide (0.3-10 mg/kg i.p.), and buspirone (0.3-30 mg/kg s.c.) increased open arm exploration and produced anxiolytic-like effects on risk-assessment behaviors (reduced stretch-attend postures and increased head dips). Of particular interest, the antidepressant drugs imipramine (1-30 mg/kg p.o.), fluoxetine (1-30 mg/kg, p.o.) and paroxetine (0.3-10 mg/kg p.o.) each produced some acute anxiolytic-like activity, without affecting locomotor activity. The antipsychotic, haloperidol, and the psychostimulant, amphetamine, did not produce any anxiolytic-like effects (1-10 mg/kg s.c). The anxiogenic beta-carboline, FG-7142, reduced time spent in the open arm and head dips, and increased stretch-attend postures (1-30 mg/kg, i.p.). These studies have demonstrated that gerbils exhibit an anxiety-like profile on an elevated plus-maze, and that the gerbil elevated plus-maze may have predictive validity for anxiolytics, and antidepressants with potential anxiolytic-like effects.
Subject(s)
Behavior, Animal/drug effects , Maze Learning/drug effects , Motor Activity/drug effects , Adrenergic Uptake Inhibitors/pharmacology , Amphetamine/pharmacology , Analysis of Variance , Animals , Anti-Anxiety Agents/pharmacology , Antidepressive Agents/pharmacology , Antipsychotic Agents/pharmacology , Carbolines/pharmacology , Dose-Response Relationship, Drug , Evaluation Studies as Topic , Exploratory Behavior/drug effects , Female , GABA Antagonists/pharmacology , Gerbillinae , Haloperidol/pharmacology , Psychological Tests/standardsABSTRACT
Neurokinin NK1 receptor antagonists may have therapeutic potential in the treatment of anxiety and depression. Species variants in the NK1 receptor result in reduced affinity of NK1 receptor antagonists at rat and mouse NK1 receptors, making it difficult to test NK1 antagonists in traditional preclinical models of anxiety and depression. Gerbil NK1 receptors are similar in homology to the human NK1 receptor. In a companion article, we described the anxiety-like behavioral profile of gerbils on an adapted elevated plus-maze, and the ability of anxiolytic drugs to produce anti-anxiety effects in the gerbil elevated plus-maze. The aim of the present study was to determine whether oral (p.o.) administration of the NK1 receptor antagonists MK-869, L-742,694, L-733,060, CP-99,994, and CP-122,721 produced anxiolytic-like effects in the gerbil elevated plus-maze. Upon testing, all five NK1 antagonists produced anxiolytic-like effects. MK-869 (0.01-3 mg/kg) was the most potent NK1 antagonist, producing anxiolytic-like effects on percentage of open arm time, percentage of open arm entries, stretch-attend postures, and head dips at 0.03-0.3 mg/kg doses. L-742,694 (1-30 mg/kg) and L-733,060 (1-10 mg/kg) produced anxiolytic-like effects on percentage of open arm time and stretch-attend postures at 3-10 mg/kg doses. CP-99,994 (3-30 mg/kg) only produced an anxiolytic-like effect on stretch-attend postures. CP-122,721 (3-30 mg/kg) produced an anxiolytic-like effect on percentage of open arm time at 30 mg/kg. The order of potency of the NK1 antagonists to increase percentage of open arm time was very similar to their potency to block NK1 agonist-induced foot-tapping. These studies demonstrate that neurokinin NK1 receptor antagonists produce anxiolytic-like effects in a novel gerbil elevated plus-maze, and suggest that this is an appropriate model to test NK1 antagonists for preclinical anxiolytic activity.