1
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Islam A, Rahman MA, Brenner MB, Moore A, Kellmyer A, Buechler HM, DiGiorgio F, Verchio VR, McCracken L, Sumi M, Hartley R, Lizza JR, Moura-Letts G, Fischer BD, Keck TM. Abuse Liability, Anti-Nociceptive, and Discriminative Stimulus Properties of IBNtxA. ACS Pharmacol Transl Sci 2020; 3:907-920. [DOI: 10.1021/acsptsci.0c00066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Bradford D. Fischer
- Cooper Medical School of Rowan University, 401 Broadway, Camden, New Jersey 08103, United States
| | - Thomas M. Keck
- Cooper Medical School of Rowan University, 401 Broadway, Camden, New Jersey 08103, United States
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2
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Norman H, D'Souza MS. Endogenous opioid system: a promising target for future smoking cessation medications. Psychopharmacology (Berl) 2017; 234:1371-1394. [PMID: 28285326 DOI: 10.1007/s00213-017-4582-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 02/24/2017] [Indexed: 01/09/2023]
Abstract
BACKGROUND Nicotine addiction continues to be a health challenge across the world. Despite several approved medications, smokers continue to relapse. Several human and animal studies have evaluated the role of the endogenous opioid system as a potential target for smoking cessation medications. METHODS In this review, studies that have elucidated the role of the mu (MORs), delta (DORs), and kappa (KORs) opioid receptors in nicotine reward, nicotine withdrawal, and reinstatement of nicotine seeking will be discussed. Additionally, the review will discuss discrepancies in the literature and therapeutic potential of the endogenous opioid system, and suggest studies to address gaps in knowledge with respect to the role of the opioid receptors in nicotine dependence. RESULTS Data available till date suggest that blockade of the MORs and DORs decreased the rewarding effects of nicotine, while activation of the MORs and DORs decreased nicotine withdrawal-induced aversive effects. In contrast, activation of the KORs decreased the rewarding effects of nicotine, while blockade of the KORs decreased nicotine withdrawal-induced aversive effects. Interestingly, blockade of the MORs and KORs attenuated reinstatement of nicotine seeking. In humans, MOR antagonists have shown benefits in select subpopulations of smokers and further investigation is required to realize their full therapeutic potential. CONCLUSION Future work must assess the influence of polymorphisms in opioid receptor-linked genes in nicotine dependence, which will help in both identifying individuals vulnerable to nicotine addiction and the development of opioid-based smoking cessation medications. Overall, the endogenous opioid system continues to be a promising target for future smoking cessation medications.
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Affiliation(s)
- Haval Norman
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH, 45810, USA
| | - Manoranjan S D'Souza
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH, 45810, USA.
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3
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Pellissier LP, Pujol CN, Becker JAJ, Le Merrer J. Delta Opioid Receptors: Learning and Motivation. Handb Exp Pharmacol 2016; 247:227-260. [PMID: 28035528 DOI: 10.1007/164_2016_89] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Delta opioid receptor (DOR) displays a unique, highly conserved, structure and an original pattern of distribution in the central nervous system, pointing to a distinct and specific functional role among opioid peptide receptors. Over the last 15 years, in vivo pharmacology and genetic models have allowed significant advances in the understanding of this role. In this review, we will focus on the involvement of DOR in modulating different types of hippocampal- and striatal-dependent learning processes as well as motor function, motivation, and reward. Remarkably, DOR seems to play a key role in balancing hippocampal and striatal functions, with major implications for the control of cognitive performance and motor function under healthy and pathological conditions.
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Affiliation(s)
- L P Pellissier
- Physiologie de la Reproduction et des Comportements, INRA UMR-0085, CNRS UMR-7247, INSERM, Université François Rabelais, IFCE, 37380, Nouzilly, France
| | - C N Pujol
- Département de Neurosciences, Institut de Génomique fonctionnelle, INSERM U-661, CNRS UMR-5203, 34094, Montpellier, France
| | - J A J Becker
- Physiologie de la Reproduction et des Comportements, INRA UMR-0085, CNRS UMR-7247, INSERM, Université François Rabelais, IFCE, 37380, Nouzilly, France
| | - J Le Merrer
- Physiologie de la Reproduction et des Comportements, INRA UMR-0085, CNRS UMR-7247, INSERM, Université François Rabelais, IFCE, 37380, Nouzilly, France.
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4
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Gibula-Bruzda E, Marszalek-Grabska M, Gawel K, Witkowska E, Izdebski J, Kotlinska JH. The influence of the new enkephalin derivative, cyclo[N(ε),N(β)-carbonyl-d-Lys(2),Dap(5)] enkephalinamide (cUENK6), on reinstatement of ethanol-induced conditioned place preference in rats. Physiol Behav 2015; 145:50-6. [PMID: 25817357 DOI: 10.1016/j.physbeh.2015.03.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/18/2015] [Accepted: 03/24/2015] [Indexed: 11/28/2022]
Abstract
The aim of the present study was to determine whether a new cyclic analog of enkephalin, cyclo[N(ε),N(β)-carbonyl-d-Lys(2),Dap(5)] enkephalinamide (cUENK6), a preferential μ-(MORs), and, to a lower extent, a δ-opioid receptor (DORs) agonist in vitro, could reinstate ethanol-induced conditioned place preference (CPP). In our work, male Wistar rats were first conditioned either with ethanol (10% w/v, 0.5g/kg, intraperitoneally (i.p.)) or 0.9% NaCl in a biased CPP procedure. The intracerebroventricular (i.c.v.) administration of DORs antagonist (naltrindole, 2.5 and 5nmol) or MORs antagonist (β-funaltrexamine, 5 and 10nmol), but not the κ opioid receptor (KORs) antagonist (norbinaltorphimine, 5 and 10nmol) was then administered and inhibited the expression of ethanol-induced CPP. After the extinction session, i.c.v. administration of cUENK6 at the dose of 0.125, 0.25 and 0.5nmol occurred, and was found to reinstate the ethanol-induced CPP similar to that of the priming injection of ethanol. However, the reinstated effect of cUENK6 (0.25nmol) was strongly abolished by administration of naltrindole and, to lesser extent, by β-funaltrexamine. Furthermore, the preferential MORs agonist-morphine (13nmol, i.c.v.) and the DORs agonist-[Leu(5)]-enkephalin (2.7 and 5.4nmol, i.c.v.) also reinstated the ethanol-induced CPP. cUENK6 given alone at the dose of 0.25nmol before the testing phase had no effect in animals that received 0.9% NaCl during the conditioning phase and also did not influence their locomotor activity. These data suggest that the effects of cUENK6 did not have an impact on the results obtained in the reinstatement procedure of CPP. Overall, the data support the idea that both MORs and DORs are normally involved in the expression and reinstatement of ethanol conditioned seeking behavior - as indexed by CPP in rats.
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Affiliation(s)
- Ewa Gibula-Bruzda
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland.
| | | | - Kinga Gawel
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| | - Ewa Witkowska
- Laboratory of Peptides, Department of Chemistry, University of Warsaw, Warsaw, Poland
| | - Jan Izdebski
- Laboratory of Peptides, Department of Chemistry, University of Warsaw, Warsaw, Poland
| | - Jolanta H Kotlinska
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
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5
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Beaudry H, Gendron L, Morón JA. Implication of delta opioid receptor subtype 2 but not delta opioid receptor subtype 1 in the development of morphine analgesic tolerance in a rat model of chronic inflammatory pain. Eur J Neurosci 2015; 41:901--7. [PMID: 25639561 DOI: 10.1111/ejn.12829] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 11/11/2014] [Accepted: 12/10/2014] [Indexed: 12/20/2022]
Abstract
Opioids are well known for their robust analgesic effects. Chronic activation of mu opioid receptors (MOPs) is, however, accompanied by various unwanted effects such as analgesic tolerance. Among other mechanisms, interactions between MOPs and delta opioid receptors (DOPs) are thought to play an important role in morphine-induced behavioral adaptations. Interestingly, certain conditions such as inflammation enhance the function of the DOP through a MOP-dependent mechanism. Here, we investigated the role of DOPs during the development of morphine tolerance in an animal model of chronic inflammatory pain. Using behavioral approaches, we first established that repeated systemic morphine treatment induced morphine analgesic tolerance in rats coping with chronic inflammatory pain. We then observed that blockade of DOPs with subcutaneous naltrindole (NTI), a selective DOP antagonist, significantly attenuated the development of morphine tolerance in a dose-dependent manner. We confirmed that this effect was DOP mediated by showing that an acute injection of NTI had no effect on morphine-induced analgesia in naive animals. Previous pharmacological characterizations revealed the existence of DOP subtype 1 and DOP subtype 2. As opposed to NTI, 7-benzylidenenaltrexone and naltriben were reported to be selective DOP subtype 1 and DOP subtype 2 antagonists, respectively. Interestingly, naltriben but not 7-benzylidenenaltrexone was able to attenuate the development of morphine analgesic tolerance in inflamed rats. Altogether, our results suggest that targeting of DOP subtype 2 with antagonists provides a valuable strategy to attenuate the analgesic tolerance that develops after repeated morphine administration in the setting of chronic inflammatory pain.
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Affiliation(s)
- H Beaudry
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University Medical Center, Columbia University, P&S Box 46, 630 West 168th Street, New York, NY, 10032, USA; Department of Physiology and Biophysics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, QC, J1H 5N4, Canada
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6
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Lasota A, Frączak O, Leśniak A, Muchowska A, Lipkowski AW, Nowakowski M, Ejchart A, Olma A. Analogues of deltorphin I containing conformationally restricted amino acids in position 2: structure and opioid activity. J Pept Sci 2014; 21:120-5. [DOI: 10.1002/psc.2738] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 12/09/2014] [Accepted: 12/12/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Anika Lasota
- Institute of Organic Chemistry; Lodz University of Technology; Zeromskiego 116 90-924 Lodz Poland
| | - Oliwia Frączak
- Institute of Organic Chemistry; Lodz University of Technology; Zeromskiego 116 90-924 Lodz Poland
| | - Anna Leśniak
- Mossakowski Medical Research Centre; Polish Academy of Sciences; Pawinskiego 5 01-793 Warsaw Poland
| | - Adriana Muchowska
- Mossakowski Medical Research Centre; Polish Academy of Sciences; Pawinskiego 5 01-793 Warsaw Poland
| | - Andrzej W. Lipkowski
- Mossakowski Medical Research Centre; Polish Academy of Sciences; Pawinskiego 5 01-793 Warsaw Poland
| | - Michał Nowakowski
- Centre of New Technologies; University of Warsaw; Zwirki i Wigury 93 02-089 Warsaw Poland
| | - Andrzej Ejchart
- Institute of Biochemistry and Biophysics; Polish Academy of Sciences; Pawinskiego 5A 02-106 Warsaw Poland
| | - Aleksandra Olma
- Institute of Organic Chemistry; Lodz University of Technology; Zeromskiego 116 90-924 Lodz Poland
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7
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Le Merrer J, Faget L, Matifas A, Kieffer BL. Cues predicting drug or food reward restore morphine-induced place conditioning in mice lacking delta opioid receptors. Psychopharmacology (Berl) 2012; 223:99-106. [PMID: 22526530 PMCID: PMC5632531 DOI: 10.1007/s00213-012-2693-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Accepted: 03/12/2012] [Indexed: 11/30/2022]
Abstract
RATIONALE The exact role of delta opioid receptors in drug-induced conditioned place preference (CPP) remains debated. Under classical experimental conditions, morphine-induced CPP is decreased in mice lacking delta opioid receptors (Oprd1 (-/-)). Morphine self-administration, however, is maintained, suggesting that drug-context association rather than drug reward is deficient in these animals. OBJECTIVES This study further examined the role of delta opioid receptors in mediating drug-cue associations, which are necessary for the expression of morphine-induced CPP. METHODS We first identified experimental conditions under which Oprd1 (-/-) mice are able to express CPP to morphine (5, 10 or 20 mg/kg) in a drug-free state and observed that, in this paradigm, CPP was dependent on circadian time conditions. We then took advantage of this particularity to assess the ability of various cues (internal or discrete), predicting either drug or food reward, to restore CPP induced by morphine (10 mg/kg) in Oprd1 (-/-) mice in conditions under which they normally fail to express CPP. RESULTS We found that presentation of circadian, drug or auditory cues, predicting morphine or food reward, restored morphine CPP in Oprd1 (-/-) mice, which then performed as well as control mice. CONCLUSIONS This study reveals that, in contrast to spatial cues, internal or discrete morphine-predicting stimuli permit full expression of morphine CPP in Oprd1 (-/-) mice. Delta receptors, therefore, appear to play a crucial role in modulating spatial contextual cue-related responses. This activity may be critical when context gains control over behavior, as is the case for context-induced relapse in drug abuse.
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Affiliation(s)
- Julie Le Merrer
- Département de Médecine Translationnelle et Neurogénétique, Institut de Biologie Moléculaire et Cellulaire, 1 rue Laurent Fries, 67 404 Illkirch Cedex, France
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8
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Hadjiconstantinou M, Neff NH. Nicotine and endogenous opioids: Neurochemical and pharmacological evidence. Neuropharmacology 2011; 60:1209-20. [DOI: 10.1016/j.neuropharm.2010.11.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 11/03/2010] [Accepted: 11/11/2010] [Indexed: 10/18/2022]
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Le Merrer J, Plaza-Zabala A, Del Boca C, Matifas A, Maldonado R, Kieffer BL. Deletion of the δ opioid receptor gene impairs place conditioning but preserves morphine reinforcement. Biol Psychiatry 2011; 69:700-3. [PMID: 21168121 DOI: 10.1016/j.biopsych.2010.10.021] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 10/04/2010] [Accepted: 10/22/2010] [Indexed: 11/25/2022]
Abstract
BACKGROUND Converging experimental data indicate that δ opioid receptors contribute to mediate drug reinforcement processes. Whether their contribution reflects a role in the modulation of drug reward or an implication in conditioned learning, however, has not been explored. In the present study, we investigated the impact of δ receptor gene knockout on reinforced conditioned learning under several experimental paradigms. METHODS We assessed the ability of δ receptor knockout mice to form drug-context associations with either morphine (appetitive)- or lithium (aversive)-induced Pavlovian place conditioning. We also examined the efficiency of morphine to serve as a positive reinforcer in these mice and their motivation to gain drug injections, with operant intravenous self-administration under fixed and progressive ratio schedules and at two different doses. RESULTS Mutant mice showed impaired place conditioning in both appetitive and aversive conditions, indicating disrupted context-drug association. In contrast, mutant animals displayed intact acquisition of morphine self-administration and reached breaking-points comparable to control subjects. Thus, reinforcing effects of morphine and motivation to obtain the drug were maintained. CONCLUSION Collectively, the data suggest that δ receptor activity is not involved in morphine reinforcement but facilitates place conditioning. This study reveals a novel aspect of δ opioid receptor function in addiction-related behaviors.
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Affiliation(s)
- Julie Le Merrer
- Département de Neurobiologie et Génétique, Institut de Biologie Moléculaire et Cellulaire, Illkirch, France
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10
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Berrendero F, Robledo P, Trigo JM, Martín-García E, Maldonado R. Neurobiological mechanisms involved in nicotine dependence and reward: participation of the endogenous opioid system. Neurosci Biobehav Rev 2010; 35:220-31. [PMID: 20170672 PMCID: PMC2908214 DOI: 10.1016/j.neubiorev.2010.02.006] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 02/08/2010] [Accepted: 02/09/2010] [Indexed: 01/07/2023]
Abstract
Nicotine is the primary component of tobacco that maintains the smoking habit and develops addiction. The adaptive changes of nicotinic acetylcholine receptors produced by repeated exposure to nicotine play a crucial role in the establishment of dependence. However, other neurochemical systems also participate in the addictive effects of nicotine including glutamate, cannabinoids, GABA and opioids. This review will cover the involvement of these neurotransmitters in nicotine addictive properties, with a special emphasis on the endogenous opioid system. Thus, endogenous enkephalins and beta-endorphins acting on mu-opioid receptors are involved in nicotine-rewarding effects, whereas opioid peptides derived from prodynorphin participate in nicotine aversive responses. An up-regulation of mu-opioid receptors has been reported after chronic nicotine treatment that could counteract the development of nicotine tolerance, whereas the down-regulation induced on kappa-opioid receptors seems to facilitate nicotine tolerance. Endogenous enkephalins acting on mu-opioid receptors also play a role in the development of physical dependence to nicotine. In agreement with these actions of the endogenous opioid system, the opioid antagonist naltrexone has shown to be effective for smoking cessation in certain sub-populations of smokers.
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Affiliation(s)
- Fernando Berrendero
- Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, University Pompeu Fabra, PRBB, C/Doctor Aiguader 88, 08003 Barcelona, Spain
| | - Patricia Robledo
- Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, University Pompeu Fabra, PRBB, C/Doctor Aiguader 88, 08003 Barcelona, Spain
- Municipal Institute of Medical Research (IMIM), Barcelona, Spain
| | - José Manuel Trigo
- Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, University Pompeu Fabra, PRBB, C/Doctor Aiguader 88, 08003 Barcelona, Spain
| | - Elena Martín-García
- Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, University Pompeu Fabra, PRBB, C/Doctor Aiguader 88, 08003 Barcelona, Spain
| | - Rafael Maldonado
- Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, University Pompeu Fabra, PRBB, C/Doctor Aiguader 88, 08003 Barcelona, Spain
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11
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Influence of new deltorphin analogues on reinstatement of cocaine-induced conditioned place preference in rats. Behav Pharmacol 2010; 21:638-48. [DOI: 10.1097/fbp.0b013e32833e7e97] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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Trigo JM, Martin-García E, Berrendero F, Robledo P, Maldonado R. The endogenous opioid system: a common substrate in drug addiction. Drug Alcohol Depend 2010; 108:183-94. [PMID: 19945803 DOI: 10.1016/j.drugalcdep.2009.10.011] [Citation(s) in RCA: 146] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 09/30/2009] [Accepted: 10/28/2009] [Indexed: 12/17/2022]
Abstract
Drug addiction is a chronic brain disorder leading to complex adaptive changes within the brain reward circuits that involve several neurotransmitters. One of the neurochemical systems that plays a pivotal role in different aspects of addiction is the endogenous opioid system (EOS). Opioid receptors and endogenous opioid peptides are largely distributed in the mesolimbic system and modulate dopaminergic activity within these reward circuits. Chronic exposure to the different prototypical drugs of abuse, including opioids, alcohol, nicotine, psychostimulants and cannabinoids has been reported to produce significant alterations within the EOS, which seem to play an important role in the development of the addictive process. In this review, we will describe the adaptive changes produced by different drugs of abuse on the EOS, and the current knowledge about the contribution of each component of this neurobiological system to their addictive properties.
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Affiliation(s)
- José Manuel Trigo
- Laboratori de Neurofarmacologia, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, PRBB, Barcelona, Spain
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13
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Delta-opioid receptor antagonists prevent sensitization to the conditioned rewarding effects of morphine. Biol Psychiatry 2009; 65:169-74. [PMID: 18950747 PMCID: PMC3832215 DOI: 10.1016/j.biopsych.2008.09.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Revised: 09/03/2008] [Accepted: 09/05/2008] [Indexed: 11/20/2022]
Abstract
BACKGROUND Functional interactions between mu- and delta-opioid receptors (MOPr and DOPr, respectively) are implicated in morphine tolerance and dependence. The contribution of DOPr to the conditioned rewarding effects of morphine and the enhanced conditioned response that occurs after repeated morphine administration is unknown. This issue was addressed with the conditioned place preference procedure (CPP). METHODS Rats received home cage injections of saline or morphine (5.0 mg/kg/day x 5 days) before conditioning. For sensitization studies, DOPr antagonists (DOPr1/2: naltrindole, DOPr2: naltriben, DOPr1: 7-benzylidenenaltrexone) were administered before morphine injections. Conditioning sessions (2 morphine; 2 saline) commenced 3 days later. To assess the influence of acute DOPr blockade on the conditioning of morphine reward in naïve animals, 3 morphine and 3 saline conditioning sessions were employed. Antagonists were administered before morphine conditioning sessions. RESULTS Morphine was ineffective as a conditioning stimulus after two conditioning sessions in naïve rats. However, doses > or = 3.0 mg/kg produced significant CPP in morphine pre-exposed rats, confirming that sensitization develops to the conditioned rewarding effects of morphine. In animals that received morphine pre-exposure with naltrindole or naltriben but not 7-benzylidenenaltrexone, sensitization was prevented. No attenuation of morphine CPP was observed in animals that received DOPr antagonists acutely, before conditioning sessions. CONCLUSIONS These data indicate a critical role of DOPr systems in mediating sensitization to the conditioned rewarding effects of morphine. The efficacy of naltrindole and naltriben in preventing the enhanced response to morphine suggest the specific involvement of DOPr2 in the sensitization process.
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Terashvili M, Wu HE, Schwasinger ET, Hung KC, Hong JS, Tseng LF. (+)-Morphine attenuates the (-)-morphine-produced conditioned place preference and the mu-opioid receptor-mediated dopamine increase in the posterior nucleus accumbens of the rat. Eur J Pharmacol 2008; 587:147-54. [PMID: 18448094 PMCID: PMC2566855 DOI: 10.1016/j.ejphar.2008.03.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 01/08/2008] [Accepted: 03/10/2008] [Indexed: 11/18/2022]
Abstract
An unbiased conditioned place preference paradigm and the microdialysis technique was used to evaluate the effect of (+)-morphine pretreatment on the conditioned place preference produced by (-)-morphine and the increased release of the dopamine produced by mu-opioid ligand endomorphin-1, respectively, in the posterior nucleus accumbens shell of the male CD rat. (-)-Morphine (2.5-10 microg) microinjected into the posterior nucleus accumbens shell dose-dependently produced the conditioned place preference. Pretreatment with (+)-morphine (0.1-10 pg) given into the posterior accumbens shell for 45 min dose-dependently attenuated the conditioned place preference produced by (-)-morphine (5 microg) given into the same posterior accumbens shell. However, higher doses of (+)-morphine (0.1 and 1 ng) were less effective in attenuating the (-)-morphine-produced conditioned place preference. Thus, like given systemically, (+)-morphine given into the posterior nucleus accumbens shell also induces a U-shaped dose-response curve for attenuating the (-)-morphine-produced conditioned place preference. Microinjection of mu-opioid agonist endomorphin-1 (1-10 microg) given into the ventral tegmental area dose-dependently increased the release of the extracellular dopamine in the posterior nucleus accumbens shell in the urethane-anesthetized rats. The increased dopamine caused by endomorphin-1 (10 microg) was completed blocked by the (+)-morphine (10 pg) pretreatment given into ventral tegmental area. It is concluded that (+)-morphine attenuates the (-)-morphine-produced conditioned place preference and the mu-opioid receptor-mediated increase of extracellular dopamine in the posterior nucleus accumbens shell of the rat.
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Affiliation(s)
- Maia Terashvili
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Hsiang-En Wu
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Emma T. Schwasinger
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Kuei-Chun Hung
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Jau-Shyong Hong
- Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, National Institute of Health, Research Triangle Park, NC 27709
| | - Leon F. Tseng
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226
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15
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David V, Matifas A, Gavello-Baudy S, Decorte L, Kieffer BL, Cazala P. Brain regional Fos expression elicited by the activation of mu- but not delta-opioid receptors of the ventral tegmental area: evidence for an implication of the ventral thalamus in opiate reward. Neuropsychopharmacology 2008; 33:1746-59. [PMID: 17895918 DOI: 10.1038/sj.npp.1301529] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Both mu-opioid receptors (MORs) and delta-opioid receptors (DORs) are expressed in the ventral tegmental area (VTA) and are thought to be involved in the addictive properties of opiates. However, their respective contributions to opiate reward remain unclear. We used intracranial self-administration (ICSA) to study the rewarding effects of morphine microinjections into the VTA of male and female MOR-/- and DOR-/- mice. In brains of mice tested for intra-VTA morphine self-administration, we analyzed regional Fos protein expression to investigate the neural circuitry underlying this behavior. Male and female WT and DOR-/- mice exhibited similar self-administration performances, whereas knockout of the MOR gene abolished intra-VTA morphine self-administration at all doses tested. Naloxone (4 mg/kg) disrupted this behavior in WT and DOR mutants, without triggering physical signs of withdrawal. Morphine ICSA was associated with an increase in Fos within the nucleus accumbens, striatum, limbic cortices, amygdala, hippocampus, the lateral mammillary nucleus (LM), and the ventral posteromedial thalamus (VPM). This latter structure was found to express high levels of Fos exclusively in self-administering WT and DOR-/- mice. Abolition of morphine reward in MOR-/- mice was associated with a decrease in Fos-positive neurons in the mesocorticolimbic dopamine system, amygdala, hippocampus (CA1), LM, and a complete absence within the VPM. We conclude that (i) VTA MORs, but not DORs, are critical for morphine reward and (ii) the role of VTA-thalamic projections in opiate reward deserves to be further explored.
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MESH Headings
- Analysis of Variance
- Animals
- Behavior, Animal/drug effects
- Brain/anatomy & histology
- Brain/drug effects
- Brain/metabolism
- Cell Count/methods
- Conditioning, Operant/drug effects
- Female
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/physiology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Morphine/administration & dosage
- Naloxone/pharmacology
- Narcotic Antagonists/pharmacology
- Narcotics/administration & dosage
- Neurons/drug effects
- Neurons/metabolism
- Oncogene Proteins v-fos/genetics
- Oncogene Proteins v-fos/metabolism
- Reaction Time/drug effects
- Reaction Time/physiology
- Receptors, Opioid, delta/deficiency
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, mu/deficiency
- Receptors, Opioid, mu/metabolism
- Self Administration
- Ventral Tegmental Area/cytology
- Ventral Tegmental Area/drug effects
- Ventral Tegmental Area/metabolism
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Affiliation(s)
- Vincent David
- Centre de Neurosciences Intégratives et Cognitives, CNRS UMR 5228/Universités de Bordeaux 1 et 2, Talence, France.
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16
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Ito S, Mori T, Sawaguchi T. Differential effects of μ-opioid, δ-opioid and κ-opioid receptor agonists on dopamine receptor agonist-induced climbing behavior in mice. Behav Pharmacol 2006; 17:691-701. [PMID: 17110795 DOI: 10.1097/fbp.0b013e32801155a1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Interactions between the dopaminergic system and opioids have not been adequately clarified. The present study was designed to investigate the effects of micro-opioid (morphine), delta-opioid (SNC80) and kappa-opioid (U50 488H) receptor agonists on dopamine receptor agonist-induced climbing behavior in mice. Apomorphine (dopamine-receptor agonist) increased stereotyped climbing behavior, unlike methamphetamine, morphine, U-50 488H and (+/-)7-hydroxy-N,N-di-n-propyl-2-aminotetralin hydrobromide (D2-like receptor agonist). Furthermore, SKF81297 (D1 receptor agonist) and SNC80 caused climbing behavior. In addition, while morphine (20 mg/kg), but not U50 488H or SNC80, significantly attenuated high-dose apomorphine (2.0 mg/kg)-induced climbing behavior, it significantly potentiated low-dose apomorphine (0.5 mg/kg)-induced climbing behavior. These results suggest that morphine may have dual effects on the behavioral effects induced by apomorphine. Furthermore, we interestingly showed that the combination of apomorphine or SKF81297 and SNC80 enhanced frequent nonstereotypic climbing behavior, suggesting that delta/D1 interactions may play a prominent role in the expression of certain types of behavior in mice. Thus, micro-opioid, delta-opioid and kappa-opioid receptor agonists induce possible differential effects on the dopaminergic system in mice.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer/pharmacology
- Analgesics, Non-Narcotic/pharmacology
- Analgesics, Opioid/pharmacology
- Animals
- Apomorphine
- Benzamides/pharmacology
- Benzazepines
- Dopamine Agonists
- Male
- Mice
- Mice, Inbred Strains
- Morphine/pharmacology
- Motor Activity/drug effects
- Piperazines/pharmacology
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, mu/agonists
- Tetrahydronaphthalenes
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Affiliation(s)
- Shinobu Ito
- Department of Legal Medicine, Tokyo Women's Medical University, Tokyo, Japan
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17
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Mori T, Ito S, Kita T, Narita M, Suzuki T, Sawaguchi T. Effects of mu-, delta- and kappa-opioid receptor agonists on methamphetamine-induced self-injurious behavior in mice. Eur J Pharmacol 2006; 532:81-7. [PMID: 16464448 DOI: 10.1016/j.ejphar.2005.12.035] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 12/02/2005] [Accepted: 12/19/2005] [Indexed: 11/19/2022]
Abstract
Opioid receptor agonists can differentially modify the behavioral effects of direct/indirect dopamine receptor agonists, such as methamphetamine, cocaine and apomorphine. However, the effects of opioid receptor agonists on high-dose methamphetamine-induced behavior have not yet been clarified. Therefore, the present study was undertaken to investigate the effects of mu (morphine)-, delta (SNC80)- and kappa (U50,488H)-opioid receptor agonists on methamphetamine-induced self-injurious behavior and locomotor activity in mice. Methamphetamine (20 mg/kg) induced severe self-injurious behavior. In a combination test, some opioid receptor agonists significantly attenuated methamphetamine-induced self-injurious behavior, with potencies in the order morphine>buprenorphine (mu-opioid and kappa-opioid receptor agonist/antagonist) >U50,488H, as maximum effects. These results suggest that the stimulation of mu- and kappa-opioid receptors plays an inhibitory role in high-dose methamphetamine-induced stereotypic self-injurious behavior in mice, without affecting locomotor activity.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer/pharmacology
- Analgesics, Opioid/pharmacology
- Animals
- Behavior, Animal/drug effects
- Benzamides/pharmacology
- Buprenorphine/pharmacology
- Dopamine Agents/pharmacology
- Dose-Response Relationship, Drug
- Male
- Methamphetamine/pharmacology
- Mice
- Morphine/pharmacology
- Motor Activity/drug effects
- Piperazines/pharmacology
- Receptors, Opioid/agonists
- Receptors, Opioid/physiology
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/physiology
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/physiology
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/physiology
- Time Factors
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Affiliation(s)
- Tomohisa Mori
- Department of Legal Medicine, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
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18
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Martin TJ, McIntosh S, Smith JE. Alkylation of opioid receptors by 5′-naltrindole-isothiocyanate injected into the nucleus accumbens of rats: Receptor selectivity and anatomical diffusion. Synapse 2006; 60:384-91. [PMID: 16847946 DOI: 10.1002/syn.20310] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Subtypes of the delta opioid receptor (Oprd1) have been suggested based on pharmacology studies. However, these subtypes have not been confirmed biochemically using either receptor binding assays or molecular cloning. Naltrindole-5'-isothiocyanate (5'-NTII) is an irreversible opioid antagonist that appears to selectively inhibit the actions of a subset of delta opioid agonists in vivo, referred to as putative delta-2 agonists. The biochemical and anatomical selectivity of wash-resistant inhibition of binding of [(3)H]DAMGO (Oprm1), [(3)H]DPDPE (Oprd1, putative subtype 1 agonist), or [(3)H]deltorphin II (Oprd1, putative subytpe 2 agonist) in coronal sections was assessed using quantitative in vitro autoradiography following injection of 5'-NTII into the nucleus accumbens in rats. 5'-NTII decreased [(3)H]deltorphin II to a greater extent than the binding of the other two radioligands following administration of 0.05-2.5 nmol. The effects of 5'-NTII were largely confined to the nucleus accumbens; however, some loss in the ventral caudate was also noted. In contrast, administration of the nonselective opioid receptor alkylating antagonist beta-chlornaltexamine (beta-CNA) over a similar range of doses was found to be nonselective for either delta radioligand, and produced greater inhibition of Oprm1 relative to Oprd1 binding, consistent with the nonselective pharmacological activity of this antagonist. Although 5'-NTII inhibited [(3)H]deltorphin II binding to a greater extent, the binding of the other two radioligands was decreased over a similar range of doses. Absolute conclusions regarding the involvement of delta-2 opioid receptors in pharmacological or physiological effects based on studies with 5'-NTII should therefore be tempered, and for site-directed studies it would be best to employ doses of 0.5 nmol or lower.
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Affiliation(s)
- Thomas J Martin
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine,Winston-Salem, North Carolina 27157, USA.
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19
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Hebb ALO, Drolet G, Mendella PD, Roach SP, Gauthier MS, Zacharko RM. Intracerebroventricular d-Pen2, d-Pen5-enkephalin administration soon after stressor imposition influences behavioral responsivity to a subsequent stressor encounter in CD-1 mice. Pharmacol Biochem Behav 2005; 82:453-69. [PMID: 16290012 DOI: 10.1016/j.pbb.2005.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2005] [Revised: 09/21/2005] [Accepted: 10/04/2005] [Indexed: 11/25/2022]
Abstract
Endogenous opioid peptide systems diminish stress-induced autonomic nervous system, neuroendocrine (hypothalamic-pituitary-adrenal axis) and behavioral responses, attenuating a collection of physiological symptoms basic to emotional and affective states. Neurogenic stressors may incite specific central changes in opioid peptide availability as well as changes in mu and delta-opioid receptor function. The present investigation evaluated the proactive influence of an intracerebroventricular injection of the opioid receptor agonist D-Pen2, D-Pen5-enkephalin (DPDPE) (0 microg, 0.005 microg, 1.0 microg or 2.5 microg) on locomotor behavior of mice following uncontrollable footshock (Shock) or novel shock chamber exposure (No Shock). It was expected that DPDPE administration following Shock on Day 1 would restore locomotor activity up to 1 week and prevent shock-associated behavior of mice encountering a brief session of footshock 18 days later. Exposure to Shock reduced horizontal locomotor and vertical locomotor (rearing) activity of mice while 2.5 microg DPDPE restored behavior. Eighteen days following Shock and DPDPE challenge, mice were exposed to either an abbreviated session of footshock (Mild Stress) or the shock chamber (Cues). Mice in the No Shock and Shock groups administered 2.5 microg DPDPE on Day 1 did not exhibit any locomotor deficits in response to Mild Stress on Day 18. Mice in the Shock group administered 0.005 microg DPDPE on Day 1, did not exhibit exaggerated rearing deficits following ensuing Mild Stressor encounter relative to mice reexposed to Cues on Day 18. Taken together, these data show that (a) footshock differentially affects rearing and locomotor activity, (b) DPDPE administration increases locomotor activity for up to 1 week following footshock and DPDPE administration, (c) reexposure to Mild Stress affects rearing and locomotor performance differently depending on previous stressor history and DPDPE dose, (d) DPDPE affords long-lasting protection to previously non-stressed mice against the deleterious effects of subsequent mild stress on locomotor activity, while a low dose of DPDE is sufficient to prevent shock-induced sensitization of rearing deficits, 18 days following original stressor and drug presentation. Finally, our investigation demonstrates that DPDPE administration alters the behavioral impact of future stressful encounters and emphasizes the importance of investigating opioid mechanisms in chronic stress disorders.
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Affiliation(s)
- Andrea L O Hebb
- Laboratory of Molecular Neurobiology, Dalhousie University, Halifax, NS, Canada.
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20
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Terashvili M, Wu HE, Leitermann RJ, Hung KC, Clithero AD, Schwasinger ET, Tseng LF. Differential conditioned place preference responses to endomorphin-1 and endomorphin-2 microinjected into the posterior nucleus accumbens shell and ventral tegmental area in the rat. J Pharmacol Exp Ther 2004; 309:816-24. [PMID: 14755004 DOI: 10.1124/jpet.103.059287] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
An unbiased conditioned place preference (CPP) paradigm was used to evaluate the reward effects of endogenous mu-opioid receptor ligands endomorphin-1 (EM-1) and endomorphin-2 (EM-2) from the mesolimbic posterior nucleus accumbens (Acb) shell and the ventral tegmental area (VTA) in CD rats. EM-1 (1.6-8.1 nmol) microinjected into posterior Acb shell produced CPP, whereas EM-2 (8.7-17.5 nmol) given into the same Acb shell produced conditioned place aversion (CPA). EM-1 (1.6-16.3 nmol) microinjected into the VTA produced CPP, whereas EM-2 (8.7 and 17.5 nmol) given into the same VTA site did not produce any effect, but at a high dose (35 nmol) produced CPP. EM-1 (3.3 nmol) or EM-2 (17.5 nmol) microinjected into the nigrostriatal substantia nigra was not significantly different from vehicle-injected groups. D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH(2) (CTOP) at 94.13 pmol or 3-methoxynaltrexone at 0.64 pmol microinjected into the posterior Acb shell blocked EM-1-induced CPP and EM-2-induced CPA. At a higher dose, CTOP (941.3 pmol) and 3-methoxynaltrexone (6.4 pmol) produced CPA and CPP, respectively. Coadministration with antiserum against dynorphin A(1-17) (Dyn) (10 microg) microinjected into the posterior Acb shell blocked EM-2-induced CPA. However, it did not affect EM-1-induced CPP. It is concluded that EM-1 and EM-2 produce site-dependent CPP and CPA, respectively, by stimulation of different subtypes of mu-opioid-receptors; stimulation of one subtype of mu-opioid-receptor at the posterior Acb shell and VTA by EM-1 induces CPP, whereas stimulation of another subtype of mu-opioid receptor at the posterior Acb shell, but not the VTA, by EM-2 induces the release of Dyn to produce CPA.
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Affiliation(s)
- Maia Terashvili
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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21
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Filira F, Biondi B, Biondi L, Giannini E, Gobbo M, Negri L, Rocchi R. Opioid peptides: synthesis and biological properties of [(Nγ-glucosyl,Nγ-methoxy)-α,γ-diamino-(S)-butanoyl]4-deltorphin-1-neoglycopeptide and related analogues. Org Biomol Chem 2003; 1:3059-63. [PMID: 14518129 DOI: 10.1039/b306142f] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The [D-Ala2]deltorphin 1 sequence in which the aspartic acid residue is replaced by the N gamma-OCH3-alpha, gamma-diamino (S) butanoyl residue was synthesized using the Fmoc-chemistry-based solid phase procedure. The resulting deltorphin analogue was chemoselectively glucosylated by reaction with unprotected D-glucose (Glc). The Asn4-, (2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-galactopyranosyl)-Asn4- and the (2-acetamido-2-deoxy-D-galactopyranosyl)-Asn4-deltorphin I were also prepared for comparison. The affinity of the new compounds for the delta-opioid receptor was expressed by the inhibition constant (Ki) of the binding of the delta-receptor selective ligand [3H]naltrindole (NTI) to rat brain membrane preparations. The in vitro biological activity of the synthetic peptides was compared with that of the mu-opioid receptor agonist dermorphin in guinea pig ileum (GPI) preparations and with that of the delta-opioid receptor agonist deltorphin I in mouse vas deferens (MVD) preparations. The substitution of Asp4 with Asn failed to affect drastically the Ki and IC50 values for delta-sites, suggesting that an electrostatic interaction does not play an essential role in the binding to delta-opioid sites. The steric hindrance of the side chain of the residue in position 4 affects binding to delta-sites. The increase of the Ki value is smaller when the sugar-peptide linkage involves the gamma-nitrogen of the Dab residue in comparison with the Asn amide side chain.
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Affiliation(s)
- Fernando Filira
- Department of Organic Chemistry, University of Padova, Institute of Biomolecular Chemistry, C. N. R., Section of Padova, via Marzolo, 1-35131, Padova, Italy
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22
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Biondi L, Giannini E, Filira F, Gobbo M, Marastoni M, Negri L, Scolaro B, Tomatisc R, Rocchi R. Synthesis, conformation and biological activity of dermorphin and deltorphin I analogues containingN-alkylglycine in place of residues in position 1, 3, 5 and 6. J Pept Sci 2003; 9:638-48. [PMID: 14620129 DOI: 10.1002/psc.487] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Syntheses are described of new dermorphin and [D-Ala2]deltorphin I analogues in which the phenylalanine, the tyrosine or the valine residues have been substituted by the corresponding N-alkylglycine residues. Structural investigations by CD measurements in different solvents and preliminary pharmacological experiments were carried out on the resulting peptide-peptoid hybrids. The contribution from aromatic side chain residues is prominent in the CD spectra of dermorphin analogues and the assignment of a prevailing secondary structure could be questionable. In the CD spectra of deltorphin analogues the aromatic contribution is lower and the dichroic curves indicate the predominance of random conformer populations. The disappearance of the aromatic contribution in the [Ntyr1,D-Ala2]-deltorphin spectrum could be explained in terms of high conformational freedom of the N-terminal residue. The kinetics of degradation of the synthetic peptoids digestion by rat and human plasma enzymes were compared with that of [Leu5]-enkephalin. The binding to opioid receptors was tested on crude membrane preparations from CHO cells stably transfected with the mu- and delta-opioid receptors. The biological potency of peptoids was compared with that of dermorphin in GPI preparations and with that of deltorphin I in MVD preparations. All the substitutions produced a dramatic decrease in the affinity of the peptide-peptoid hybrids for both the mu- and delta-opioid receptors. Nval5 and/or Nval6 containing hybrids behaved as mu-opioid receptor agonists and elicit a dose-dependent analgesia (tail-flick test) when injected i.c.v. in rats.
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MESH Headings
- Analgesics, Opioid/chemical synthesis
- Analgesics, Opioid/chemistry
- Analgesics, Opioid/pharmacology
- Animals
- CHO Cells
- Cricetinae
- Cricetulus
- Guinea Pigs
- Male
- Mice
- Muscle Contraction/drug effects
- Muscle, Smooth/drug effects
- Muscle, Smooth/metabolism
- Muscle, Smooth/physiology
- N-substituted Glycines/chemistry
- Oligopeptides/chemical synthesis
- Oligopeptides/chemistry
- Oligopeptides/pharmacology
- Opioid Peptides
- Pain/drug therapy
- Protein Conformation
- Rats
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, mu/metabolism
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Affiliation(s)
- Laura Biondi
- Department of Organic Chemistry, University of Padova, Institute of Biomolecular Chemistry, C.N.R., Section of Padova, via Marzolo, 1-35131 Padova, Italy
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23
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Narita M, Ozaki S, Ioka M, Mizoguchi H, Nagase H, Tseng LF, Suzuki T. Different motivational effects induced by the endogenous mu-opioid receptor ligands endomorphin-1 and -2 in the mouse. Neuroscience 2001; 105:213-8. [PMID: 11483313 DOI: 10.1016/s0306-4522(01)00151-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The present study was designed to investigate the motivational effects of the newly discovered endogenous mu-opioid receptor ligands, endomorphin-1 and endomorphin-2, using the conditioned place preference paradigm in mice. The binding properties of these peptides were first examined using an opioid binding assay. In membranes obtained from the mouse whole brain, the binding of [3H][D-Ala2, NMePhe4, Gly(ol)5]enkephalin (DAMGO; mu), but not of [3H][D-Phe2, D-Phe5]enkephalin (DPDPE; delta) or [3H]U69593 (kappa) selectively and concentration-dependently competed with that of endomorphin-1 and endomorphin-2, indicating that both endomorphin-1 and endomorphin-2 are specific ligands for mu-opioid receptors in the brain. Endomorphin-1 (1-30 nmol/mouse) given i.c.v. produced a dose-related place preference. This effect was abolished by pre-treatment with the mu-opioid receptor antagonist beta-funaltrexamine but not the delta-opioid receptor antagonist naltrindole or the kappa-opioid receptor antagonist nor-binaltorphimine. In contrast, endomorphin-2 (5.6 nmol/mouse) produced place aversion. This aversive effect was inhibited by nor-binaltorphimine as well as beta-funaltrexamine, but not by naltrindole. The place aversion produced by endomorphin-2 was also attenuated by pre-treatment with antiserum against the endogenous kappa-opioid receptor ligand dynorphin A (1-17). These findings indicate that endomorphin-1 may produce its rewarding effect via mu-opioid receptors. On the other hand, the aversive effect induced by endomorphin-2 may be associated with the stimulation of endomorphin-1-insensitive mu-opioid receptors and the activation of dynorphinergic systems in the mouse brain.
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MESH Headings
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Binding, Competitive/drug effects
- Binding, Competitive/physiology
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Central Nervous System/drug effects
- Central Nervous System/metabolism
- Conditioning, Psychological/drug effects
- Conditioning, Psychological/physiology
- Male
- Mice
- Mice, Inbred C57BL
- Motivation
- Narcotic Antagonists/pharmacology
- Narcotics/pharmacology
- Oligopeptides/metabolism
- Oligopeptides/pharmacology
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/metabolism
- Reward
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Affiliation(s)
- M Narita
- Department of Toxicology, School of Pharmacy, Hoshi University, Tokyo, Japan
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24
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Imaizumi M, Takeda M, Sawano S, Fushiki T. Opioidergic contribution to conditioned place preference induced by corn oil in mice. Behav Brain Res 2001; 121:129-36. [PMID: 11275290 DOI: 10.1016/s0166-4328(00)00388-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We previously reported that voluntary intake of corn oil in the light box showed place preference in the conditioned place preference (CPP) test in mice. In the present study, we investigated the contribution of opioidergic systems to the corn oil-induced CPP in mice. Acquisition of the place preference by corn oil intake was blocked by i.p. injections of an opioid mu antagonist, naloxone (0.1 and 0.3 mg/kg), and delta antagonists, 7-benzylidenenaltrexone (0.5 mg/kg) and naltriben (0.5 mg/kg) 15 min before conditioning. The opioid kappa agonist U-50488H (1 and 3 mg/kg i.p.) also blocked corn oil-induced CPP. Naloxone (1 mg/kg, i.p.) and naltriben (0.5 mg/kg, i.p.) did not affect corn oil intake in the home cage. However, 7-benzylidenenaltrexone (0.5 mg/kg, i.p.) and U-50488H (1 mg/kg i.p.) decreased and increased the corn oil intake, respectively. These results suggested that the rewarding effects of corn oil in the CPP test are at least partially mediated via opioidergic systems through mu and delta receptors. Further, we showed that an opioid kappa agonist reduced the rewarding effects of corn oil in the CPP test in mice, although it increased corn oil intake.
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Affiliation(s)
- M Imaizumi
- Laboratory of Nutrition Chemistry, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Oiwake-cho Sakyo-ku, Kyoto 606-8502, Japan.
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25
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Abstract
Three major types of opioid receptors, designated mu, delta, and kappa, are widely expressed in the CNS. Development of selective receptor ligands and recent cloning of each receptor have contributed greatly to our increasing knowledge of the neuropharmacological profile of each opioid receptor type. It is of interest to note that they include noncompetitive and allosteric interactions among their types. This review focuses on the functional interaction among these opioid receptor types that contribute to opioid dependence. Various studies provide arguments to support substantial roles for mu-opioid receptors and the possible involvement of delta-opioid receptors in the development of physical and psychological dependence on morphine. Noradrenergic transmission originating in the locus coeruleus is most likely to play the primary causal role in the expression of physical dependence on morphine. In contrast, many studies have pointed to the mesolimbic dopaminergic pathway projecting from the ventral tegmental area to the nucleus accumbens as a critical site for the initiation of psychological dependence on opioids. It is noteworthy as the broad existence of opposing interactions between mu/delta- and kappa-receptors in the brain. The activation of kappa-receptors leads to the suppression of unpleasant mu/delta-mediated side effects such as the rewarding effect. Considering the functional interaction among opioid receptor types, the co-administration of morphine-like compounds with kappa-receptor agonists may constitute a preferable and superior approach to the treatment of pain with fewer side effects.
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Affiliation(s)
- M Narita
- Department of Toxicology, School of Pharmacy, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
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26
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Hutcheson DM, Matthes HWD, Valjent E, Sanchez-Blazquez P, Rodriguez-Diaz M, Garzon J, Kieffer BL, Maldonado R. Lack of dependence and rewarding effects of deltorphin II in mu-opioid receptor-deficient mice. Eur J Neurosci 2001. [DOI: 10.1046/j.1460-9568.2001.01363.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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27
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Hutcheson DM, Matthes HWD, Valjent E, Sánchez-Blázquez P, Rodríguez-Díaz M, Garzón J, Kieffer BL, Maldonado R. Lack of dependence and rewarding effects of deltorphin II in mu-opioid receptor-deficient mice. Eur J Neurosci 2001. [DOI: 10.1111/j.1460-9568.2001.01363.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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28
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Svingos AL, Clarke CL, Pickel VM. Localization of the delta-opioid receptor and dopamine transporter in the nucleus accumbens shell: implications for opiate and psychostimulant cross-sensitization. Synapse 1999; 34:1-10. [PMID: 10459166 DOI: 10.1002/(sici)1098-2396(199910)34:1<1::aid-syn1>3.0.co;2-h] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Opiate- and psychostimulant-induced modulation of dopamine transmission in the nucleus accumbens shell (AcbSh) is thought to play a key role in their potent reinforcing and locomotor effects. To investigate the cellular basis for potential functional interactions involving opiates active at the delta-opioid receptor (DOR) and psychostimulants that bind selectively to the dopamine transporter (DAT), we examined the electron microscopic localization of their respective antisera in rat AcbSh. DOR immunoperoxidase labeling was seen primarily, and DAT immunogold particles exclusively, in axon terminals. In these terminals, DOR immunoreactivity was prominently associated with discrete segments of the plasma membrane and the membranes of nearby small synaptic and large dense core vesicles. DAT immunogold particles were almost exclusively distributed along nonsynaptic axonal plasma membranes. Thirty-nine percent DOR-labeled profiles (221/566) either apposed DAT-immunoreactive terminals or also contained DAT. Of these 221 DOR-labeled profiles, 13% were axon terminals containing DAT and 15% were dendritic spines apposed to DAT-immunoreactive terminals. In contrast, 70% were morphologically heterogeneous axon terminals and small axons apposed to DAT-immunoreactive terminals. Our results indicate that DOR agonists in the AcbSh can directly modulate the release of dopamine, as well as postsynaptic responses in spiny neurons that receive dopaminergic input, but act principally to control the presynaptic secretion of other neurotransmitters whose release may influence or be influenced by extracellular dopamine. Thus, while opiates and psychostimulants mainly have differential sites of action, cross-sensitization of their addictive properties may occur through common neuronal targets.
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Affiliation(s)
- A L Svingos
- Weill Medical College of Cornell University, Department of Neurology and Neuroscience, Division of Neurobiology, New York, New York 10021, USA.
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29
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Cowen MS, Lawrence AJ. The role of opioid-dopamine interactions in the induction and maintenance of ethanol consumption. Prog Neuropsychopharmacol Biol Psychiatry 1999; 23:1171-212. [PMID: 10581642 DOI: 10.1016/s0278-5846(99)00060-3] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
1. Alcohol is one of the most widely used recreational drugs, but also one of the most widely abused, causing vast economic, social and personal damage. 2. Several animal models are available to study the reinforcing mechanisms that are the basis of the abuse liability of ethanol. Innate differences in opioid or dopamine neurotransmission may enhance the abuse liability of ethanol, as indicated by animal and human studies. 3. Opioid antagonists have been shown to be effective, both experimentally and clinically, in decreasing ethanol consumption, presumably since ethanol induces the release of endogenous opioid peptides in vivo. However, ethanol may also stimulate the formation of opiate-like compounds, which could interact with opioid (or dopamine) receptors. Ethanol may cause changes in neurotransmission mediated via opioid receptors that determines whether alcohol abuse is more or less likely. 4. Ethanol appears to facilitate dopamine release by increasing opioidergic activity, disinhibiting dopaminergic neurons (by inhibition of GABAergic neurotransmission) via mu-opioid receptors in the ventral tegmental area (VTA) and delta-opioid receptors in the nucleus accumbens (NAcc). The effects of ethanol would be antagonised by presynaptic kappa-opioid receptors present on dopaminergic terminals in the NAcc. 5. Mesolimbic dopamine release induced by ethanol consumption seems to indicate ethanol-related stimuli are important, focussing attention on and enabling learning of the stimuli. However, studies indicate that there are redundant pathways, and neural pathways 'downstream' of the mesolimbic dopamine system, which also enable the reinforcing properties of ethanol to be mediated.
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Affiliation(s)
- M S Cowen
- Dept. of Pharmacology, Monash University, Clayton, Vic., Australia
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30
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Matsuzawa S, Suzuki T, Misawa M, Nagase H. Different roles of mu-, delta- and kappa-opioid receptors in ethanol-associated place preference in rats exposed to conditioned fear stress. Eur J Pharmacol 1999; 368:9-16. [PMID: 10096764 DOI: 10.1016/s0014-2999(99)00008-4] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The present study was designed to investigate the role of the endogenous opioid system in the development of ethanol-induced place preference in rats exposed to conditioned fear stress (exposure to an environment paired previously with electric foot shock), using the conditioned place preference paradigm. The administration of ethanol (300 mg/kg, i.p.) with conditioned fear stress induced significant place preference. Naloxone (1 and 3 mg/kg, s.c.), a non-selective opioid receptor antagonist, significantly attenuated this ethanol-induced place preference. Moreover, the selective mu-opioid receptor antagonist beta-funaltrexamine (3 and 10 mg/kg, i.p.) and the selective delta-opioid receptor antagonist naltrindole (1 and 3 mg/kg, s.c.) significantly attenuated ethanol-induced place preference. In contrast, the selective kappa-opioid receptor antagonist nor-binaltorphimine (3 mg/kg, i.p.) significantly enhanced ethanol-induced place preference. Furthermore, 75 mg/kg ethanol (which tended to produce place preference) combined with the mu-opioid receptor agonist morphine (0.1 mg/kg, s.c.) or the selective delta-opioid receptor agonist 2-methyl-4aalpha-(3-hydroxyphenyl)-1,2,3,4,4a,5,12,12aalpha- octahydroquinolino [2,3,3,-g] isoquinoline (TAN-67; 20 mg/kg, s.c.), at doses which alone did not produce place preference, produced significant place preference. However, co-administration of the selective kappa-opioid receptor agonist trans-3,4-dichloro-N-(2-(1-pyrrolidinyl)cyclohexyl)benzenacetamide methanesulfonate (U50,488H; 0.3 and 1 mg/kg, s.c.) with ethanol (300 mg/kg, i.p.) dose dependently attenuated ethanol-induced place preference. Moreover, conditioned fear stress shifted the response curve for the aversive effect of U50,488H to the left. These results suggest that mu- and delta-opioid receptors may play critical roles in the rewarding mechanism of ethanol, and that kappa-opioid receptors may modulate the development of the rewarding effect of ethanol under psychological stress.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer/pharmacology
- Analgesics/pharmacology
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Central Nervous System Depressants/pharmacology
- Conditioning, Psychological/drug effects
- Ethanol/pharmacology
- Fear/psychology
- Male
- Morphine/pharmacology
- Naloxone/pharmacology
- Naltrexone/analogs & derivatives
- Naltrexone/pharmacology
- Narcotic Antagonists/pharmacology
- Quinolines/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid/physiology
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/physiology
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, kappa/physiology
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/physiology
- Stress, Psychological/physiopathology
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Affiliation(s)
- S Matsuzawa
- Department of Pharmacology, School of Pharmacy, Hoshi University, Ebara, Tokyo, Japan
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31
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Negri L, Lattanzi R, Tabacco F, Orrù L, Severini C, Scolaro B, Rocchi R. Dermorphin and deltorphin glycosylated analogues: synthesis and antinociceptive activity after systemic administration. J Med Chem 1999; 42:400-4. [PMID: 9986710 DOI: 10.1021/jm9810699] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the present paper we describe the synthesis of some dermorphin and deltorphin analogues beta-O- and alpha-C-glycosylated on the C-terminal amino acid residue and report their opioid receptor affinity and selectivity as well as their analgesic potency after subcutaneous injection in mice.
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Affiliation(s)
- L Negri
- Institute of Medical Pharmacology, University "La Sapienza" of Rome, P.le Aldo Moro, 5, I-00185 Rome, Italy
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32
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Tzschentke TM. Measuring reward with the conditioned place preference paradigm: a comprehensive review of drug effects, recent progress and new issues. Prog Neurobiol 1998; 56:613-72. [PMID: 9871940 DOI: 10.1016/s0301-0082(98)00060-4] [Citation(s) in RCA: 917] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This review gives an overview of recent findings and developments in research on brain mechanisms of reward and reinforcement from studies using the place preference conditioning paradigm, with emphasis on those studies that have been published within the last decade. Methodological issues of the paradigm (such as design of the conditioning apparatus, biased vs unbiased conditioning, state dependency effects) are discussed. Results from studies using systemic and local (intracranial) drug administration, natural reinforcers, and non-drug treatments and from studies examining the effects of lesions are presented. Papers reporting on conditioned place aversion (CPA) experiments are also included. A special emphasis is put on the issue of tolerance and sensitization to the rewarding properties of drugs. Transmitter systems that have been investigated with respect to their involvement in brain reward mechanisms include dopamine, opioids, acetylcholine, GABA, serotonin, glutamate, substance P, and cholecystokinin, the motivational significance of which has been examined either directly, by using respective agonist or antagonist drugs, or indirectly, by studying the effects of these drugs on the reward induced by other drugs. For a number of these transmitters, detailed studies have been conducted to delineate the receptor subtype(s) responsible for the mediation of the observed drug effects, particularly in the case of dopamine, the opioids, serotonin and glutamate. Brain sites that have been implicated in the mediation of drug-induced place conditioning include the 'traditional' brain reward sites, ventral tegmental area and nucleus accumbens, but the medial prefrontal cortex, ventral pallidum, amygdala and the pedunculopontine tegmental nucleus have also been shown to play important roles in the mediation of place conditioning induced by drugs or natural reinforcers. Thus, although the paradigm has also been criticized because of some inherent methodological problems, it is clear that during the past decade place preference conditioning has become a valuable and firmly established and very widely used tool in behavioural pharmacology and addiction research.
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Affiliation(s)
- T M Tzschentke
- Department of Neuropharmacology, University of Tübingen, Germany.
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Matsuzawa S, Suzuki T, Misawa M, Nagase H. Involvement of mu- and delta-opioid receptors in the ethanol-associated place preference in rats exposed to foot shock stress. Brain Res 1998; 803:169-77. [PMID: 9729364 DOI: 10.1016/s0006-8993(98)00679-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to establish the ethanol-induced place preference in rats exposed to foot shock stress using the conditioned place preference paradigm. We also investigated the role of the endogenous opioid system in the development of the ethanol-induced place preference. The administration of ethanol (300 mg/kg, i.p.) with foot shock stress, but not without such stress, induced a marked and significant place preference. Naloxone (1 and 3 mg/kg, s.c.), a non-selective opioid receptor antagonist, significantly attenuated the ethanol-induced place preference. Moreover, the selective mu-opioid receptor antagonist beta-funaltrexamine (3 and 10 mg/kg, i.p.) and selective delta-opioid receptor antagonist naltrindole (1 and 3 mg/kg, s.c.), but not the selective kappa-opioid receptor antagonist nor-binaltorphimine (1 and 3 mg/kg, i.p.), significantly attenuated the ethanol-induced place preference. Furthermore, 150 mg/kg ethanol (which tended to produce a place preference, although not significantly) combined with each dose (that did not produce a place preference) of the mu-opioid receptor agonist morphine (0.1 mg/kg, s.c.) or selective delta-opioid receptor agonist 2-methyl-4aalpha-(3-hydroxyphenyl)-1,2,3,4,4a,5,12, 12aalpha-octahydroquinolino [2,3,3-g] isoquinoline (TAN-67; 20 mg/kg, s.c.), but not the selective kappa-opioid receptor agonist trans-3, 4-dichloro-N-(2-(1-pyrrolidinyl)cyclohexyl)benzenacetamide methanesulfonate (U50,488H; 1 mg/kg, s.c.), produced a significant place preference. These data indicate that stress may be important for development of the rewarding effect of ethanol, and that mu- and delta-opioid receptors may be involved in the rewarding mechanism of ethanol under stressful conditions.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer/administration & dosage
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer/pharmacology
- Animals
- Behavior, Animal/drug effects
- Dose-Response Relationship, Drug
- Electric Stimulation
- Ethanol/administration & dosage
- Ethanol/pharmacology
- Exploratory Behavior/drug effects
- Foot/physiology
- Injections, Intraperitoneal
- Injections, Subcutaneous
- Male
- Morphine/administration & dosage
- Morphine/pharmacology
- Naloxone/administration & dosage
- Naloxone/pharmacology
- Naltrexone/administration & dosage
- Naltrexone/analogs & derivatives
- Naltrexone/pharmacology
- Narcotics/pharmacology
- Quinolines/administration & dosage
- Quinolines/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid, delta/physiology
- Receptors, Opioid, mu/physiology
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Affiliation(s)
- S Matsuzawa
- Department of Pharmacology, School of Pharmacy, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
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34
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Cellular sites for activation of delta-opioid receptors in the rat nucleus accumbens shell: relationship with Met5-enkephalin. J Neurosci 1998. [PMID: 9465017 DOI: 10.1523/jneurosci.18-05-01923.1998] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The shell compartment of the nucleus accumbens (AcbSh) is prominently involved in the rewarding aspects of delta-opioid receptor (DOR) agonists, including one of its putative endogenous ligands, Met5-enkephalin (Enk). We examined the ultrastructural immunocytochemical localization of an antipeptide DOR antiserum and an antibody against Enk to determine the major cellular sites for DOR activation and the spatial relationship between DOR and Enk in this region. Sixty percent of DOR-immunoreactive profiles were axon terminals and small unmyelinated axons, whereas the remainder were mainly dendrites and dendritic spines. In axons and terminals, DOR labeling was distributed along plasma and vesicular membranes. DOR-containing terminals were mainly large and primarily formed symmetric synapses or occasionally asymmetric synapses. DOR immunoreactivity also was associated with terminals that were small and formed punctate symmetric or nonrecognizable synapses. Dual immunoperoxidase and immunogold labeling showed that 35% of DOR-labeled axons apposed other terminals that contained Enk. In addition, 25% of the DOR-labeled terminals contained Enk. Thirty-five percent of DOR labeling was observed within dendrites and dendritic spines. DOR-labeled spines showed intense immunoreactivity within asymmetric postsynaptic junctions, which were formed by terminals that lacked Enk immunoreactivity. DOR-labeled spines, however, were apposed to Enk-containing terminals in 13% of all associations between dually labeled profiles. These results provide ultrastructural evidence that activation of DOR in the AcbSh is primarily involved in modulating the presynaptic release of mainly inhibitory, but also excitatory, neurotransmitters. These data also suggest that DOR plays a role in determining the postsynaptic response to excitatory afferents.
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Abstract
This paper is the twentieth installment of our annual review of research concerning the opiate system. It summarizes papers published during 1997 that studied the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress; tolerance and dependence; eating and drinking; alcohol; gastrointestinal, renal, and hepatic function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurologic disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunologic responses; and other behaviors.
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Affiliation(s)
- G A Olson
- Department of Psychology, University of New Orleans, LA 70148, USA
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36
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Suzuki T, Mori T, Tsuji M, Misawa M, Nagase H. The role of delta-opioid receptors in the discriminative stimulus properties of a low dose of methamphetamine. Eur J Pharmacol 1997; 331:1-8. [PMID: 9274922 DOI: 10.1016/s0014-2999(97)01020-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The effects of selective mu-, delta- and kappa-opioid receptor agonists and antagonists on the discriminative stimulus properties of methamphetamine were examined in rats that had been trained to discriminate between methamphetamine (0.4 mg/kg) and saline. Methamphetamine produced a dose-related increase in methamphetamine-appropriate responses in all of the rats. In generalization tests, neither morphine (a mu-opioid receptor agonist: 0.3-10 mg/kg) nor 3,4-dichloro-N-[2-(1-pyrrolidinyl)cyclohexo]benzeneacetamide (U50,488H: a kappa-opioid receptor agonist: 1.0-8.0 mg/kg) generalized to the discriminative stimulus properties of methamphetamine. A newly synthesized non-peptide selective delta-opioid receptor agonist 2-methyl-4aalpha-(3-hydroxyphenyl)-1,2,3,4,4a,5,12,12aalpha- octahydroquinolino(2,3,3,-g)isoquinoline (TAN-67: 32 mg/kg) partially generalized (70% methamphetamine-appropriate responses) to the discriminative stimulus properties of methamphetamine. In combination tests, pretreatment with the mu- and kappa-opioid receptor antagonists, beta-funaltrexamine (9.0 mg/kg) and nor-binaltorphimine (10 mg/kg), respectively, had little or no influence on the discriminative stimulus properties of methamphetamine. In contrast, pretreatment with naltrindole (a non-selective delta-opioid receptor antagonist: 3.0 mg/kg) or naltriben (a selective delta2-opioid receptor antagonist: 1.0 mg/kg), but not with 7-benzylidenenaltrexone (a selective delta1-opioid receptor antagonist: 0.5 and 1.0 mg/kg), significantly attenuated the discriminative stimulus properties of methamphetamine. However, naltrindole (3.0 mg/kg) did not significantly attenuate the discriminative stimulus properties of methamphetamine at a higher training dose (1.0 mg/kg). Our findings may have some bearing on the relative importance of the role of delta-opioid (especially delta2-opioid) receptors in the discriminative stimulus properties of a low dose of methamphetamine.
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Affiliation(s)
- T Suzuki
- Department of Pharmacology, School of Pharmacy, Hoshi University, Tokyo, Japan.
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37
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Suzuki T, Mori T, Tsuji M, Maeda J, Kishimoto Y, Misawa M, Nagase H. Differential effects of mu-, delta- and kappa-opioid receptor agonists on the discriminative stimulus properties of cocaine in rats. Eur J Pharmacol 1997; 324:21-9. [PMID: 9137909 DOI: 10.1016/s0014-2999(97)00062-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The effects of selective mu-, delta- and kappa-opioid receptor agonists on the discriminative stimulus properties of cocaine were examined in rats trained to discriminate between cocaine (10 mg/kg) and saline. Cocaine produced a dose-related increase in cocaine-appropriate responses in all of the rats. In generalization tests, neither morphine (mu-opioid receptor agonist) nor N-methyl-N-7-(1-pyrrolidinyl)-1-oxaspiro[4,5]dec-8-11-4-benzofu ranacetamide (U50,488H: kappa-opioid receptor agonist) generalized to the discriminative stimulus properties of cocaine. On the other hand, the newly synthesized non-peptide selective delta-opioid receptor agonist 2-methyl-4a alpha-(3-hydroxyphenyl)-1,2,3,4,4a,5,12,12a alpha-octahydro-quinolino(2,3,3,-g)isoquinoline (TAN-67) partially generalized (56.7% cocaine-appropriate responses) to the discriminative stimulus properties of cocaine. Intracerebroventricular (i.c.v.) administration of [D-Ala2]deltorphin II (peptide delta 2-opioid receptor agonist) completely generalized, while neither [D-Ala2,MePhe4,Gly-ol5]enkephalin (DAMGO: mu-opioid receptor agonist) nor [D-Pen2,D-Pen5]enkephalin (DPDPE; delta 1-opioid receptor agonist) generalized to the discriminative stimulus properties of cocaine. These results suggest that the discriminative stimulus properties of cocaine may be partially mediated by delta-opioid (especially delta 2-opioid) receptors. In combination tests, pretreatment with morphine (3.0 mg/kg) and TAN-67 (3.0 and 10 mg/kg) significantly potentiated the discriminative stimulus properties cocaine. In contrast, pretreatment with U50,488H (2.0 and 4.0 mg/kg) scarcely shifted the discriminative stimulus properties of cocaine. Furthermore, the potentiating effect of 3.0 mg/kg morphine on the discriminative stimulus properties of cocaine was attenuated by 2.0 mg/kg U50,488H. In contrast, the potentiating effect of 10 mg/kg TAN-67 on the discriminative stimulus properties of cocaine was not reversed by either 2.0 or 4.0 mg/kg U50,488H. These results suggest that mu-, delta- and kappa-opioid receptor agonists modulate the discriminative stimulus properties of cocaine through different mechanisms, perhaps through different effects on the dopaminergic system.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer
- Analgesics/administration & dosage
- Analgesics/pharmacology
- Analysis of Variance
- Animals
- Cocaine/administration & dosage
- Cocaine/toxicity
- Discrimination Learning/drug effects
- Discrimination, Psychological/drug effects
- Dose-Response Relationship, Drug
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
- Enkephalin, D-Penicillamine (2,5)-
- Enkephalins/administration & dosage
- Enkephalins/pharmacology
- Injections, Intraventricular
- Male
- Morphine/administration & dosage
- Morphine/toxicity
- Narcotics/administration & dosage
- Narcotics/toxicity
- Pyrrolidines/administration & dosage
- Pyrrolidines/pharmacology
- Quinolines/administration & dosage
- Quinolines/pharmacology
- Rats
- Rats, Inbred F344
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, mu/agonists
- Substance-Related Disorders
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Affiliation(s)
- T Suzuki
- Department of Pharmacology, School of Pharmacy, Hoshi University, Tokyo, Japan
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