51
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Synthesis of new opioid derivatives with a propellane skeleton and their pharmacologies: Part 5, novel pentacyclic propellane derivatives with a 6-amide side chain. Bioorg Med Chem 2015; 23:6271-9. [DOI: 10.1016/j.bmc.2015.08.036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 08/24/2015] [Accepted: 08/26/2015] [Indexed: 11/18/2022]
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52
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Loriga G, Lazzari P, Manca I, Ruiu S, Falzoi M, Murineddu G, Bottazzi MEH, Pinna G, Pinna GA. Novel diazabicycloalkane delta opioid agonists. Bioorg Med Chem 2015; 23:5527-38. [DOI: 10.1016/j.bmc.2015.07.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 07/17/2015] [Accepted: 07/19/2015] [Indexed: 12/19/2022]
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53
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Nozaki C, Nagase H, Nemoto T, Matifas A, Kieffer BL, Gaveriaux-Ruff C. In vivo properties of KNT-127, a novel δ opioid receptor agonist: receptor internalization, antihyperalgesia and antidepressant effects in mice. Br J Pharmacol 2015; 171:5376-86. [PMID: 25048778 DOI: 10.1111/bph.12852] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 06/30/2014] [Accepted: 07/13/2014] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND AND PURPOSE Activation of δ opioid (DOP) receptors regulates pain and emotional responses, and also displays ligand-biased agonism. KNT-127 (1,2,3,4,4a,5,12,12a-octahydro-2-methyl-4aβ,1β-([1,2]benzenomethano)-2,6-diazanaphthacene-12aβ,17-diol) is a novel DOP receptor agonist inducing analgesia and antidepressant effects in mice. Here, we have assessed KNT-127 for (i) analgesia against chronic inflammatory pain; (ii) effects on depression, locomotion and DOP receptor internalization; and (iii) for cross-tolerance to analgesic and antidepressant effects of acute treatment by other DOP receptor agonists. EXPERIMENTAL APPROACH Inflammatory pain was induced by complete Freund's adjuvant injection into tail or hindpaw, and thermal and mechanical sensitivities were determined in mice. Locomotor and antidepressant-like effects were measured using actimetry and forced swim test respectively. In vivo KNT-127 selectivity and internalization were assessed using DOP receptor knockout mice and knock-in mice expressing fluorescent-tagged DOP receptors. KNT-127 was injected acutely at 0.1-10.0 mg·kg(-1) or administered chronically at 5 mg·kg(-1) daily over 5 days. KEY RESULTS Acute treatment with KNT-127 reversed inflammatory hyperalgesia, produced an antidepressant-like effect but induced neither hyperlocomotion nor receptor sequestration. Chronic treatment with KNT-127 induced tolerance and cross-tolerance to SNC80-induced analgesia, but no tolerance to SNC80-evoked hyperlocomotor or antidepressant-like effects. CONCLUSIONS AND IMPLICATIONS The DOP receptor agonist KNT-127 induced agonist-specific acute and chronic responses, at both behavioural and cellular levels. It displays activities similar to the other recently reported DOP agonists, AR-M1000390, ADL5747 and ADL5859, and differs from SNC80. SNC80 differs from the other DOP receptor agonists including KNT-127, by exhibiting ligand-biased tolerance at this receptor.
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Affiliation(s)
- C Nozaki
- Institute of Molecular Psychiatry, University of Bonn, Bonn, Germany; Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Université de Strasbourg, Strasbourg, France
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Gibula-Bruzda E, Marszalek-Grabska M, Witkowska E, Izdebski J, Kotlinska JH. Enkephalin analog, cyclo[N(ε),N(β)-carbonyl-D-Lys(2),Dap(5)] enkephalinamide (cUENK6), inhibits the ethanol withdrawal-induced anxiety-like behavior in rats. Alcohol 2015; 49:229-36. [PMID: 25716198 DOI: 10.1016/j.alcohol.2015.01.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Revised: 01/20/2015] [Accepted: 01/22/2015] [Indexed: 01/08/2023]
Abstract
An analog of enkephalin, cyclo[N(ε),N(β)-carbonyl-D-Lys(2),Dap(5)] enkephalinamide (cUENK6), is predominantly a functional agonist of μ-opioid receptors (MOPr) and, to a lesser extent, of δ-opioid receptors (DOPr) in vitro. The aim of the present study was to determine whether cUENK6 could affect ethanol withdrawal-induced anxiety-like behavior in the elevated plus maze (EPM) test in rats. An anxiety-like effect of withdrawal was predicted to occur in the EPM test 24 h after the last ethanol administration (2 g/kg, intraperitoneally [i.p.]; 15% w/v once daily for 9 days). Ethanol withdrawal decreased the percent of time spent by rats in the open arms and the percent of open-arms entries. cUENK6 (0.25 nmol), given by intracerebroventricular (i.c.v.) injection, significantly reversed these anxiety-like effects of ethanol withdrawal and elevated the percent of time spent by rats in the open arms and the percent of open-arms entries. These effects of cUENK6 were significantly inhibited by the DOPr antagonist naltrindole (NTI) (5 nmol, i.c.v.), but not by the MOPr antagonist β-funaltrexamine (β-FNA) (5 nmol, i.c.v.). The preferential DOPr agonist [Leu(5)]-enkephalin (LeuEnk) (2.7 and 5.4 nmol, i.c.v.) and the MOPr agonist morphine (6.5 and 13 nmol, i.c.v.) reduced the anxiety-like effects of ethanol withdrawal. cUENK6 at the dose of 0.25 nmol did not disturb locomotor activity in the EPM, in contrast to cUENK6 at the dose of 0.5 nmol, and morphine at 6.5 and 13 nmol. However, similarly to LeuEnk, cUENK6 induced the anxiolytic-like effects in naïve rats. Thus, our study suggests that cUENK6 reduced ethanol withdrawal-induced anxiety-like behavior by activation of δ-opioid receptors rather than μ-opioid receptors.
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55
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A novel anxiogenic role for the delta opioid receptor expressed in GABAergic forebrain neurons. Biol Psychiatry 2015; 77:404-15. [PMID: 25444168 PMCID: PMC4297504 DOI: 10.1016/j.biopsych.2014.07.033] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 07/15/2014] [Accepted: 07/24/2014] [Indexed: 01/10/2023]
Abstract
BACKGROUND The delta opioid receptor (DOR) is broadly expressed throughout the nervous system; it regulates chronic pain, emotional responses, motivation, and memory. Neural circuits underlying DOR activities have been poorly explored by genetic approaches. We used conditional mouse mutagenesis to elucidate receptor function in GABAergic neurons of the forebrain. METHODS We characterized DOR distribution in the brain of Dlx5/6-CreXOprd1(fl/fl) (Dlx-DOR) mice and tested main central DOR functions through behavioral testing. RESULTS The DOR proteins were strongly deleted in olfactory bulb and striatum and remained intact in cortex and basolateral amygdala. Olfactory perception, circadian activity, and despair-like behaviors were unchanged. In contrast, locomotor stimulant effects of SNC80 (DOR agonist) and SKF81297 (D1 agonist) were abolished and increased, respectively. The Dlx-DOR mice showed lower levels of anxiety in the elevated plus maze, opposing the known high anxiety in constitutive DOR knockout animals. Also, Dlx-DOR mice reached the food more rapidly in a novelty suppressed feeding task, despite their lower motivation for food reward observed in an operant paradigm. Finally, c-fos protein staining after novelty suppressed feeding was strongly reduced in amygdala, concordant with the low anxiety phenotype of Dlx-DOR mice. CONCLUSIONS We demonstrate that DORs expressed in the forebrain mediate the described locomotor effect of SNC80 and inhibit D1-stimulated hyperactivity. Our data also reveal an unanticipated anxiogenic role for this particular DOR subpopulation, with a potential novel adaptive role. In emotional responses, DORs exert dual anxiolytic and anxiogenic roles, both of which may have implications in the area of anxiety disorders.
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56
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Chung PCS, Boehrer A, Stephan A, Matifas A, Scherrer G, Darcq E, Befort K, Kieffer BL. Delta opioid receptors expressed in forebrain GABAergic neurons are responsible for SNC80-induced seizures. Behav Brain Res 2015; 278:429-34. [PMID: 25447299 PMCID: PMC4382405 DOI: 10.1016/j.bbr.2014.10.029] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 10/12/2014] [Accepted: 10/21/2014] [Indexed: 01/01/2023]
Abstract
The delta opioid receptor (DOR) has raised much interest for the development of new therapeutic drugs, particularly to treat patients suffering from mood disorders and chronic pain. Unfortunately, the prototypal DOR agonist SNC80 induces mild epileptic seizures in rodents. Although recently developed agonists do not seem to show convulsant properties, mechanisms and neuronal circuits that support DOR-mediated epileptic seizures remain to be clarified. DORs are expressed throughout the nervous system. In this study we tested the hypothesis that SNC80-evoked seizures stem from DOR activity at the level of forebrain GABAergic transmission, whose inhibition is known to facilitate the development of epileptic seizures. We generated a conditional DOR knockout mouse line, targeting the receptor gene specifically in GABAergic neurons of the forebrain (Dlx-DOR). We measured effects of SNC80 (4.5, 9, 13.5 and 32 mg/kg), ARM390 (10, 30 and 60 mg/kg) or ADL5859 (30, 100 and 300 mg/kg) administration on electroencephalograms (EEGs) recorded in Dlx-DOR mice and their control littermates (Ctrl mice). SNC80 produced dose-dependent seizure events in Ctrl mice, but these effects were not detected in Dlx-DOR mice. As expected, ARM390 and ADL5859 did not trigger any detectable change in mice from both genotypes. These results demonstrate for the first time that SNC80-induced DOR activation induces epileptic seizures via direct inhibition of GABAergic forebrain neurons, and supports the notion of differential activities between first and second-generation DOR agonists.
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Affiliation(s)
- Paul Chu Sin Chung
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Annie Boehrer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Aline Stephan
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Audrey Matifas
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Grégory Scherrer
- Department of Anesthesiology, Perioperative and Pain Medicine, Department of Molecular and Cellular Physiology, Department of Neurosurgery, Stanford Neurosciences Institute, Stanford University, Palo Alto, CA 94304, USA
| | - Emmanuel Darcq
- Douglas Hospital Research Center, Department of Psychiatry, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - Katia Befort
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Brigitte L Kieffer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France; Douglas Hospital Research Center, Department of Psychiatry, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
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57
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Faster, better, stronger: towards new antidepressant therapeutic strategies. Eur J Pharmacol 2014; 753:32-50. [PMID: 25092200 DOI: 10.1016/j.ejphar.2014.07.046] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 05/28/2014] [Accepted: 07/24/2014] [Indexed: 12/26/2022]
Abstract
Major depression is a highly prevalent disorder and is predicted to be the second leading cause of disease burden by 2020. Although many antidepressant drugs are currently available, they are far from optimal. Approximately 50% of patients do not respond to initial first line antidepressant treatment, while approximately one third fail to achieve remission following several pharmacological interventions. Furthermore, several weeks or months of treatment are often required before clinical improvement, if any, is reported. Moreover, most of the commonly used antidepressants have been primarily designed to increase synaptic availability of serotonin and/or noradrenaline and although they are of therapeutic benefit to many patients, it is clear that other therapeutic targets are required if we are going to improve the response and remission rates. It is clear that more effective, rapid-acting antidepressants with novel mechanisms of action are required. The purpose of this review is to outline the current strategies that are being taken in both preclinical and clinical settings for identifying superior antidepressant drugs. The realisation that ketamine has rapid antidepressant-like effects in treatment resistant patients has reenergised the field. Further, developing an understanding of the mechanisms underlying the rapid antidepressant effects in treatment-resistant patients by drugs such as ketamine may uncover novel therapeutic targets that can be exploited to meet the Olympian challenge of developing faster, better and stronger antidepressant drugs.
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58
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Nagi K, Pineyro G. Kir3 channel signaling complexes: focus on opioid receptor signaling. Front Cell Neurosci 2014; 8:186. [PMID: 25071446 PMCID: PMC4085882 DOI: 10.3389/fncel.2014.00186] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Accepted: 06/18/2014] [Indexed: 12/03/2022] Open
Abstract
Opioids are among the most effective drugs to treat severe pain. They produce their analgesic actions by specifically activating opioid receptors located along the pain perception pathway where they inhibit the flow of nociceptive information. This inhibition is partly accomplished by activation of hyperpolarizing G protein-coupled inwardly-rectifying potassium (GIRK or Kir3) channels. Kir3 channels control cellular excitability in the central nervous system and in the heart and, because of their ubiquitous distribution, they mediate the effects of a large range of hormones and neurotransmitters which, upon activation of corresponding G protein-coupled receptors (GPCRs) lead to channel opening. Here we analyze GPCR signaling via these effectors in reference to precoupling and collision models. Existing knowledge on signaling bias is discussed in relation to these models as a means of developing strategies to produce novel opioid analgesics with an improved side effects profile.
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Affiliation(s)
- Karim Nagi
- Département de Pharmacologie, Faculté de Médecine, Université de Montréal Montreal, QC, Canada ; Centre de Recherche du CHU Sainte-Justine Montréal, QC, Canada
| | - Graciela Pineyro
- Département de Pharmacologie, Faculté de Médecine, Université de Montréal Montreal, QC, Canada ; Centre de Recherche du CHU Sainte-Justine Montréal, QC, Canada ; Département de Psychiatrie, Faculté de Médecine, Université de Montréal Montréal, QC, Canada
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59
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Klenowski P, Morgan M, Bartlett SE. The role of δ-opioid receptors in learning and memory underlying the development of addiction. Br J Pharmacol 2014; 172:297-310. [PMID: 24641428 DOI: 10.1111/bph.12618] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 01/10/2014] [Accepted: 01/19/2014] [Indexed: 01/14/2023] Open
Abstract
UNLABELLED Opioids are important endogenous ligands that exist in both invertebrates and vertebrates and signal by activation of opioid receptors to produce analgesia and reward or pleasure. The μ-opioid receptor is the best known of the opioid receptors and mediates the acute analgesic effects of opiates, while the δ-opioid receptor (DOR) has been less well studied and has been linked to effects that follow from chronic use of opiates such as stress, inflammation and anxiety. Recently, DORs have been shown to play an essential role in emotions and increasing evidence points to a role in learning actions and outcomes. The process of learning and memory in addiction has been proposed to involve strengthening of specific brain circuits when a drug is paired with a context or environment. The DOR is highly expressed in the hippocampus, amygdala, striatum and other basal ganglia structures known to participate in learning and memory. In this review, we will focus on the role of the DOR and its potential role in learning and memory underlying the development of addiction. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.
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Affiliation(s)
- Paul Klenowski
- Translational Research Institute, Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
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60
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Haj-Mirzaian A, Ostadhadi S, Kordjazy N, Dehpour AR, Ejtemaei Mehr S. Opioid/NMDA receptors blockade reverses the depressant-like behavior of foot shock stress in the mouse forced swimming test. Eur J Pharmacol 2014; 735:26-31. [DOI: 10.1016/j.ejphar.2014.03.053] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 03/15/2014] [Accepted: 03/26/2014] [Indexed: 10/25/2022]
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61
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Gendron L, Mittal N, Beaudry H, Walwyn W. Recent advances on the δ opioid receptor: from trafficking to function. Br J Pharmacol 2014; 172:403-19. [PMID: 24665909 DOI: 10.1111/bph.12706] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 03/17/2014] [Accepted: 03/18/2014] [Indexed: 01/12/2023] Open
Abstract
UNLABELLED Within the opioid family of receptors, δ (DOPrs) and μ opioid receptors (MOPrs) are typical GPCRs that activate canonical second-messenger signalling cascades to influence diverse cellular functions in neuronal and non-neuronal cell types. These receptors activate well-known pathways to influence ion channel function and pathways such as the map kinase cascade, AC and PI3K. In addition new information regarding opioid receptor-interacting proteins, downstream signalling pathways and resultant functional effects has recently come to light. In this review, we will examine these novel findings focusing on the DOPr and, in doing so, will contrast and compare DOPrs with MOPrs in terms of differences and similarities in function, signalling pathways, distribution and interactions. We will also discuss and clarify issues that have recently surfaced regarding the expression and function of DOPrs in different cell types and analgesia. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.
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Affiliation(s)
- Louis Gendron
- Département de physiologie et biophysique, Institut de pharmacologie de Sherbrooke, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada
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62
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Effects of the δ opioid agonist AZD2327 upon operant behaviors and assessment of its potential for abuse. Pharmacol Biochem Behav 2014; 124:48-57. [PMID: 24857840 DOI: 10.1016/j.pbb.2014.05.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 05/07/2014] [Accepted: 05/14/2014] [Indexed: 11/23/2022]
Abstract
AZD2327 is a brain-penetrant agonist at δ opioid receptors which has antidepressant and anxiolytic properties in a wide array of animal models. As part of the preclinical safety pharmacology assessment, a number of studies were conducted in order to characterize its behavioral effects and its potential for abuse, in order to enable testing in humans. AZD2327 produced only modest effects when tested in a multiple fixed-ratio differential reinforcement of low rate schedule in rats, and did not enhance the rate-suppressing effects of ethanol in the procedure. In a suppressed responding test, AZD2327 only reduced rates of unpunished responding. In drug discrimination studies, AZD2327 produced partial or no generalization from known drugs of abuse. In primates trained to self-administer cocaine, substitution with AZD2327 did not result in appreciable self-administration of AZD2327, indicating that it does not behave as a positive reinforcer under the present conditions. Following termination of repeated administration of AZD2327, no signs of physical dependence (withdrawal) were noted. Overall, the data suggest that AZD2327 does not possess a high potential for abuse, and appears to have only subtle behavioral effects as measured by operant behaviors.
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63
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Fujii H, Hayashida K, Saitoh A, Yokoyama A, Hirayama S, Iwai T, Nakata E, Nemoto T, Sudo Y, Uezono Y, Yamada M, Nagase H. Novel delta opioid receptor agonists with oxazatricyclodecane structure. ACS Med Chem Lett 2014; 5:368-72. [PMID: 24900842 DOI: 10.1021/ml400491k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 01/27/2014] [Indexed: 11/28/2022] Open
Abstract
We synthesized compounds 4a,c-f,h,i containing the oxazatricyclodecane structure from a novel rearrangement reaction product 2a. All the prepared compounds 4a,c-f,h,i exhibited full agonistic activities for the δ opioid receptor (DOR). Among them, the N-methyl derivative 4c was highly selective, and the most effective DOR agonist in functional assays. Subcutaneous administration of 4c produced dose-dependent and NTI (selective DOR antagonist)-reversible antinociception lacking any convulsive behaviors in the mice acetic acid writhing tests. The N-methyl derivative 4c is expected to be a promising lead compound for selective DOR agonists with a novel chemotype.
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Affiliation(s)
- Hideaki Fujii
- School
of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Kohei Hayashida
- School
of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Akiyoshi Saitoh
- Department
of Neuropsychopharmacology, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashimachi, Kodaira, Tokyo 187-8553, Japan
| | - Akinobu Yokoyama
- Division
of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Tokyo 104-0045, Japan
- Faculty
of Pharmaceutical Science, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 274-8510, Japan
| | - Shigeto Hirayama
- School
of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Takashi Iwai
- School
of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Eriko Nakata
- Discovery
Research Laboratories, Nippon Chemiphar Co., Ltd., 1-22 Hikokawado, Misato, Saitama 341-0005, Japan
| | - Toru Nemoto
- School
of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Yuka Sudo
- Division
of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Tokyo 104-0045, Japan
- Faculty
of Pharmaceutical Science, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 274-8510, Japan
| | - Yasuhito Uezono
- Division
of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Tokyo 104-0045, Japan
| | - Mitsuhiko Yamada
- Department
of Neuropsychopharmacology, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashimachi, Kodaira, Tokyo 187-8553, Japan
| | - Hiroshi Nagase
- School
of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
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DOR2-selective but not DOR1-selective antagonist abolishes anxiolytic-like effects of the δ opioid receptor agonist KNT-127. Neuropharmacology 2014; 79:314-20. [DOI: 10.1016/j.neuropharm.2013.11.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 11/06/2013] [Accepted: 11/23/2013] [Indexed: 01/02/2023]
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65
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Nemoto T, Ida Y, Iihara Y, Nakajima R, Hirayama S, Iwai T, Fujii H, Nagase H. The most effective influence of 17-(3-ethoxypropyl) substituent on the binding affinity and the agonistic activity in KNT-127 derivatives, δ opioid receptor agonists. Bioorg Med Chem 2013; 21:7628-47. [PMID: 24262888 DOI: 10.1016/j.bmc.2013.10.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 10/21/2013] [Accepted: 10/22/2013] [Indexed: 10/26/2022]
Abstract
We investigated the structure-activity relationship of KNT-127 (opioid δ agonist) derivatives with various 17-substituents which are different in length and size. The 17-substituent in KNT-127 derivatives exerted a great influence on the affinity and agonistic activity for the δ receptor. While the compounds with electron-donating 17-substituents showed higher affinities for the δ receptor than those with electron-withdrawing groups, KNT-127 derivatives with 17-fluoroalkyl groups (the high electron-withdrawing groups) showed high selectivities for the δ receptor among evaluated compounds. In addition, the basicity of nitrogen as well as the structure of the 17-N substituent such as the length and configuration at an asymmetric carbon atom contributed to agonist properties for the δ receptor. Thus, the analog with a 17-(3-ethoxypropyl) group showed the best selectively and potent agonistic activity for the δ receptor among KNT-127 derivatives. These findings should be useful for designing novel δ selective agonists.
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Affiliation(s)
- Toru Nemoto
- School of Pharmacy, Kitasato University, 5-9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan
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66
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Pharmacological traits of delta opioid receptors: pitfalls or opportunities? Psychopharmacology (Berl) 2013; 228:1-18. [PMID: 23649885 PMCID: PMC3679311 DOI: 10.1007/s00213-013-3129-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 04/15/2013] [Indexed: 12/11/2022]
Abstract
RATIONALE Delta opioid receptors (DORs) have been considered as a potential target to relieve pain as well as treat depression and anxiety disorders and are known to modulate other physiological responses, including ethanol and food consumption. A small number of DOR-selective drugs are in clinical trials, but no DOR-selective drugs have been approved by the Federal Drug Administration and some candidates have failed in phase II clinical trials, highlighting current difficulties producing effective delta opioid-based therapies. Recent studies have provided new insights into the pharmacology of the DOR, which is often complex and at times paradoxical. OBJECTIVE This review will discuss the existing literature focusing on four aspects: (1) Two DOR subtypes have been postulated based on differences in pharmacological effects of existing DOR-selective ligands. (2) DORs are expressed ubiquitously throughout the body and central nervous system and are, thus, positioned to play a role in a multitude of diseases. (3) DOR expression is often dynamic, with many reports of increased expression during exposure to chronic stimuli, such as stress, inflammation, neuropathy, morphine, or changes in endogenous opioid tone. (4) A large structural variety in DOR ligands implies potential different mechanisms of activating the receptor. CONCLUSION The reviewed features of DOR pharmacology illustrate the potential benefit of designing tailored or biased DOR ligands.
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Chu Sin Chung P, Kieffer BL. Delta opioid receptors in brain function and diseases. Pharmacol Ther 2013; 140:112-20. [PMID: 23764370 DOI: 10.1016/j.pharmthera.2013.06.003] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 05/15/2013] [Indexed: 01/02/2023]
Abstract
Evidence that the delta opioid receptor (DOR) is an attractive target for the treatment of brain disorders has strengthened in recent years. This receptor is broadly expressed in the brain, binds endogenous opioid peptides, and shows as functional profile highly distinct from those of mu and kappa opioid receptors. Our knowledge of DOR function has enormously progressed from in vivo studies using pharmacological tools and genetic approaches. The important role of this receptor in reducing chronic pain has been extensively overviewed; therefore this review focuses on facets of delta receptor activity relevant to psychiatric and other neurological disorders. Beneficial effects of DOR agonists are now well established in the context of emotional responses and mood disorders. DOR activation also regulates drug reward, inhibitory controls and learning processes, but whether delta compounds may represent useful drugs in the treatment of drug abuse remains open. Epileptogenic and locomotor-stimulating effects of delta agonists appear drug-dependent, and the possibility of biased agonism at DOR for these effects is worthwhile further investigations to increase benefit/risk ratio of delta therapies. Neuroprotective effects of DOR activity represent a forthcoming research area. Future developments in DOR research will benefit from in-depth investigations of DOR function at cellular and circuit levels.
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Affiliation(s)
- Paul Chu Sin Chung
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, UMR7104 CNRS/Université de Strasbourg, U964 INSERM, Illkirch, France
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Yamada M, Makino Y, Hashimoto T, Sugiyama A, Oka JI, Inagaki M, Yamada M, Saitoh A. Induction of galanin after chronic sertraline treatment in mouse ventral dentate gyrus. Brain Res 2013; 1516:76-82. [DOI: 10.1016/j.brainres.2013.04.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 02/12/2013] [Accepted: 04/02/2013] [Indexed: 01/18/2023]
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Fujii H, Takahashi T, Nagase H. Non-peptidic δ opioid receptor agonists and antagonists (2000 – 2012). Expert Opin Ther Pat 2013; 23:1181-208. [DOI: 10.1517/13543776.2013.804066] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Haj-Mirzaian A, Hamzeh N, Javadi-Paydar M, Abdollahzadeh Estakhri MR, Dehpour AR. Resistance to depression through interference of opioid and nitrergic systems in bile-duct ligated mice. Eur J Pharmacol 2013; 708:38-43. [PMID: 23528353 DOI: 10.1016/j.ejphar.2013.03.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2012] [Revised: 02/25/2013] [Accepted: 03/08/2013] [Indexed: 11/24/2022]
Abstract
This study was done to investigate the effects of opioid and nitrergic systems on depression in an experimental model of cholestasis in mice, since elevated levels of these substances are seen in cholestatic subjects. Bile duct ligated (BDL) and sham-operated mice were forced to swim individually and the immobility time in the last 4 min of the 6 min test was evaluated to determine the effects of cholestasis on depression. To assess the possible involvement of endogenous opioids and nitric oxide (NO), effective and sub-effective doses of naltrexone an antagonist of opioid receptors, and N-nitro-l-arginine methyl ester (L-NAME) a non-specific NO synthase inhibitor, were administrated acutely and chronically to BDL and Sham-operated mice and then their immobility time was measured in forced swimming test (FST). The immobility time significantly decreased after bile-duct ligation. Naltrexone and L-NAME significantly reversed antidepressant like effect of cholestasis. Co-administration of sub-effective doses of naltrexone and L-NAME also reversed antidepressant effect in FST in chronic administration. But acute drug administration did not reverse the anti-depressant effect of cholestasis. We have shown that elevated levels of endogenous opioids and NO in cholestatic mice induce an anti depressant like effect, causing a reduction in the mice immobility time in FST. And the study also showed the predominant effect of opioid system and NO modulation of that in anti-depressant like effect of cholestasis.
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Affiliation(s)
- Arya Haj-Mirzaian
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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71
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Saitoh A, Yamada M. Antidepressant-like Effects of δ Opioid Receptor Agonists in Animal Models. Curr Neuropharmacol 2013; 10:231-8. [PMID: 23449756 PMCID: PMC3468877 DOI: 10.2174/157015912803217314] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Revised: 03/09/2012] [Accepted: 04/05/2012] [Indexed: 12/28/2022] Open
Abstract
Recently, δ opioid receptor agonists have been proposed to be attractive targets for the development of novel antidepressants. Several studies revealed that single treatment of δ opioid receptor agonists produce antidepressant-like effects in the forced swimming test, which is one of the most popular animal models for screening antidepressants. In addition, subchronic treatment with δ opioid receptor agonists has been shown to completely attenuate the hyperemotional responses found in olfactory bulbectomized rats. This animal model exhibits hyperemotional behavior that may mimic the anxiety, aggression, and irritability found in depressed patients, suggesting that δ opioid receptor agonists could be effective in the treatment of these symptoms in depression. On the other hand, prototype δ opioid receptor agonists produce convulsive effects, which limit their therapeutic potential and clinical development. In this review, we presented the current knowledge regarding the antidepressant-like effects of δ opioid receptor agonists, which include some recently developed drugs lacking convulsive effects.
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Affiliation(s)
- Akiyoshi Saitoh
- Department of Neuropsychopharmacology, National Institute of Mental Health, National Center of Neurology and Psychiatry, Tokyo 187-8553, Japan
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The novel δ opioid receptor agonist KNT-127 produces distinct anxiolytic-like effects in rats without producing the adverse effects associated with benzodiazepines. Neuropharmacology 2012; 67:485-93. [PMID: 23246531 DOI: 10.1016/j.neuropharm.2012.11.025] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 11/19/2012] [Accepted: 11/24/2012] [Indexed: 11/20/2022]
Abstract
We previously reported that a δ opioid receptor agonist SNC80 produced potent anxiolytic-like effects in rodents. Recently, we succeeded in synthesizing a novel δ opioid receptor agonist KNT-127. In this study, we investigated the anxiolytic-like effects of KNT-127 using three different rat models of innate anxiety. In an elevated plus-maze test, KNT-127 (0.3, 1, and 3.0 mg/kg, s.c.) significantly and dose-dependently increased the time rats spent in the open arms 30 min after administration. The magnitude of the KNT-127 (3.0 mg/kg, s.c.)-induced anxiolytic-like effects was similar to that produced by diazepam (1.0 mg/kg, s.c.), a benzodiazepine anxiolytic. The anxiolytic-like effects of KNT-127 (3.0 mg/kg, s.c.) were abolished by pretreatment with naltrindole (0.1 mg/kg, s.c.), a selective δ opioid receptor antagonist, suggesting that KNT-127-induced anxiolytic-like effects are mediated by δ opioid receptors. These findings were supported by results obtained from light/dark and open-field tests. Interestingly, in contrast to diazepam (1.0 mg/kg, s.c.), KNT-127 (3.0 mg/kg, s.c.) caused no significant performance changes in the Y-maze test, the ethanol-induced sleeping test, and footprint test. This is the first study to demonstrate that the novel δ opioid receptor agonist KNT-127 produces distinct anxiolytic-like effects in rats, without producing the adverse effects associated with benzodiazepines.
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Bushlin I, Gupta A, Stockton SD, Miller LK, Devi LA. Dimerization with cannabinoid receptors allosterically modulates delta opioid receptor activity during neuropathic pain. PLoS One 2012; 7:e49789. [PMID: 23272051 PMCID: PMC3522681 DOI: 10.1371/journal.pone.0049789] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 10/11/2012] [Indexed: 11/20/2022] Open
Abstract
The diversity of receptor signaling is increased by receptor heteromerization leading to dynamic regulation of receptor function. While a number of studies have demonstrated that family A G-protein-coupled receptors are capable of forming heteromers in vitro, the role of these heteromers in normal physiology and disease has been poorly explored. In this study, direct interactions between CB(1) cannabinoid and delta opioid receptors in the brain were examined. Additionally, regulation of heteromer levels and signaling in a rodent model of neuropathic pain was explored. First we examined changes in the expression, function and interaction of these receptors in the cerebral cortex of rats with a peripheral nerve lesion that resulted in neuropathic pain. We found that, following the peripheral nerve lesion, the expression of both cannabinoid type 1 receptor (CB(1)R) and the delta opioid receptor (DOR) are increased in select brain regions. Concomitantly, an increase in CB(1)R activity and decrease in DOR activity was observed. We hypothesize that this decrease in DOR activity could be due to heteromeric interactions between these two receptors. Using a CB(1)R-DOR heteromer-specific antibody, we found increased levels of CB(1)R-DOR heteromer protein in the cortex of neuropathic animals. We subsequently examined the functionality of these heteromers by testing whether low, non-signaling doses of CB(1)R ligands influenced DOR signaling in the cortex. We found that, in cortical membranes from animals that experienced neuropathic pain, non-signaling doses of CB(1)R ligands significantly enhanced DOR activity. Moreover, this activity is selectively blocked by a heteromer-specific antibody. Together, these results demonstrate an important role for CB(1)R-DOR heteromers in altered cortical function of DOR during neuropathic pain. Moreover, they suggest the possibility that a novel heteromer-directed therapeutic strategy for enhancing DOR activity, could potentially be employed to reduce anxiety associated with chronic pain.
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Affiliation(s)
- Ittai Bushlin
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York, United States of America
- Department of Neuroscience and Friedman Brain Institute, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Achla Gupta
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Steven D. Stockton
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York, United States of America
- Department of Neuroscience and Friedman Brain Institute, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Lydia K. Miller
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Lakshmi A. Devi
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York, United States of America
- Department of Neuroscience and Friedman Brain Institute, Mount Sinai School of Medicine, New York, New York, United States of America
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Lutz PE, Kieffer BL. Opioid receptors: distinct roles in mood disorders. Trends Neurosci 2012; 36:195-206. [PMID: 23219016 DOI: 10.1016/j.tins.2012.11.002] [Citation(s) in RCA: 345] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 09/20/2012] [Accepted: 11/05/2012] [Indexed: 12/20/2022]
Abstract
The roles of opioid receptors in pain and addiction have been extensively studied, but their function in mood disorders has received less attention. Accumulating evidence from animal research reveals that mu, delta and kappa opioid receptors (MORs, DORs and KORs, respectively) exert highly distinct controls over mood-related processes. DOR agonists and KOR antagonists have promising antidepressant potential, whereas the risk-benefit ratio of currently available MOR agonists as antidepressants remains difficult to evaluate, in addition to their inherent abuse liability. To date, both human and animal studies have mainly examined MORs in the etiology of depressive disorders, and future studies will address DOR and KOR function in established and emerging neurobiological aspects of depression, including neurogenesis, neurodevelopment, and social behaviors.
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Affiliation(s)
- Pierre-Eric Lutz
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de Recherche Scientifique (CNRS), Strasbourg, France
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Abstract
This paper is the thirty-fourth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2011 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, United States.
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Negus SS, Rosenberg MB, Altarifi AA, O'Connell RH, Folk JE, Rice KC. Effects of the δ opioid receptor agonist SNC80 on pain-related depression of intracranial self-stimulation (ICSS) in rats. THE JOURNAL OF PAIN 2012; 13:317-27. [PMID: 22424913 DOI: 10.1016/j.jpain.2011.12.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 12/01/2011] [Accepted: 12/08/2011] [Indexed: 12/16/2022]
Abstract
UNLABELLED The delta opioid receptor agonist SNC80 produces both antinociceptive and antidepressant effects in rodents. This profile suggests that SNC80 may also reverse prodepressant effects of pain. Accordingly, this study compared SNC80 effects in complementary assays of pain-stimulated and pain-depressed behavior in rats. Intraperitoneal injection of dilute acid served as an acute noxious visceral stimulus in rats to stimulate abdominal stretching (a pain-stimulated behavior) or depress intracranial self-stimulation of the medial forebrain bundle (ICSS; a pain-depressed behavior). When administered once per week to minimize acute tolerance, SNC80 (1-10 mg/kg IP) decreased acid-stimulated stretching but had little effect on acid-induced depression of ICSS. More frequent SNC80 administration produced tolerance to SNC80 effects on acid-stimulated stretching, but unmasked antinociception in the assay of acid-depressed ICSS. SNC80 did not facilitate ICSS in the absence of pain, and effects of SNC80 were not duplicated by ARM390, a reputed delta agonist congener of SNC80 that does not internalize delta receptors. These findings support continued consideration of delta agonists as candidate analgesics to treat prodepressant effects of pain and illustrate the potential for diametrically opposite effects of drug treatments on preclinical measures of pain-stimulated and pain-depressed behavior. PERSPECTIVE The delta opioid agonist SNC80 blocked pain-related depression of intracranial self-stimulation in rats, suggesting that delta agonists may be useful to treat prodepressant effects of pain. Repeated SNC80 produced tolerance to SNC80 antinociception in a conventional assay of pain-stimulated behavior but unmasked SNC80 antinociception in an assay of pain-depressed behavior.
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Affiliation(s)
- S Stevens Negus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23220, USA.
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Tanahashi S, Ueda Y, Nakajima A, Yamamura S, Nagase H, Okada M. Novel δ1-receptor agonist KNT-127 increases the release of dopamine and L-glutamate in the striatum, nucleus accumbens and median pre-frontal cortex. Neuropharmacology 2012; 62:2057-67. [PMID: 22266218 DOI: 10.1016/j.neuropharm.2012.01.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 01/02/2012] [Accepted: 01/09/2012] [Indexed: 11/29/2022]
Abstract
The effects of systemic δ1-agonist on neurotransmission remains obscure, since no selective δ1-agonist exists that can penetrate the blood-brain barrier. Recently, we succeeded in synthesizing a putative δ1-receptor agonist, KNT-127, which has been demonstrated the effectiveness of systemic administration against anxiety and depressive-like behavior. To clarify the functional selectivity of KNT-127 and neurotransmission regulating system of δ1-receptor, the present study investigated the interaction between KNT-127 and δ-receptor antagonists on the release of dopamine, L-glutamate and GABA in nucleus accumbens (NAc), striatum and median pre-frontal cortex (mPFC) using multi-probe microdialysis. Intraperitoneal administration of KNT-127 increased the release of dopamine and L-glutamate in three regions, but decreased and increased GABA releases in respective NAc and mPFC without affecting that in striatum. The effects of KNT-127 in the three regions were abrogated by δ1-antagonist but not by δ2-antagonist. MK801 inhibited KNT-127-induced dopamine release in striatum and NAc, but enhanced that in mPFC, inhibited KNT-127-induced mPFC GABA release without affecting KNT-127-induced GABA reduction in NAc. Muscimol enhanced KNT-127-induced dopamine release in mPFC. Sulpiride inhibited KNT-127-induced reduction of GABA release in NAc. The results indicated that KNT-127 is a selective δ1-agonist, and suggested that δ1-receptor directly activates the release of dopamine and L-glutamate in the striatum, NAc and mPFC, but not that of GABA in the three regions. δ1-receptor indirectly inhibited GABA release in NAc via activated dopaminergic transmission, while δ1-receptor indirectly enhanced GABA release in mPFC via activated glutamatergic transmission.
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Affiliation(s)
- Shunsuke Tanahashi
- Department of Psychiatry, Division of Neuroscience, Graduate School of Medicine, Mie University, 2-174 Edobashi, Tsu, Mie 514-8507, Japan
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Delta opioid receptor analgesia: recent contributions from pharmacology and molecular approaches. Behav Pharmacol 2011; 22:405-14. [PMID: 21836459 DOI: 10.1097/fbp.0b013e32834a1f2c] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Delta opioid receptors represent a promising target for the development of novel analgesics. A number of tools have been developed recently that have significantly improved our knowledge of δ receptor function in pain control. These include several novel δ agonists with potent analgesic properties, and genetic mouse models with targeted mutations in the δ opioid receptor gene. Also, recent findings have further documented the regulation of δ receptor function at cellular level, which impacts on the pain-reducing activity of the receptor. These regulatory mechanisms occur at transcriptional and post-translational levels, along agonist-induced receptor activation, signaling and trafficking, or in interaction with other receptors and neuromodulatory systems. All these tools for in-vivo research, and proposed mechanisms at molecular level, have tremendously increased our understanding of δ receptor physiology, and contribute to designing innovative strategies for the treatment of chronic pain and other diseases such as mood disorders.
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