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Zhu C, Lan X, Wei Z, Yu J, Zhang J. Allosteric modulation of G protein-coupled receptors as a novel therapeutic strategy in neuropathic pain. Acta Pharm Sin B 2024; 14:67-86. [PMID: 38239234 PMCID: PMC10792987 DOI: 10.1016/j.apsb.2023.07.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 06/09/2023] [Accepted: 07/12/2023] [Indexed: 01/22/2024] Open
Abstract
Neuropathic pain is a debilitating pathological condition that presents significant therapeutic challenges in clinical practice. Unfortunately, current pharmacological treatments for neuropathic pain lack clinical efficacy and often lead to harmful adverse reactions. As G protein-coupled receptors (GPCRs) are widely distributed throughout the body, including the pain transmission pathway and descending inhibition pathway, the development of novel neuropathic pain treatments based on GPCRs allosteric modulation theory is gaining momentum. Extensive research has shown that allosteric modulators targeting GPCRs on the pain pathway can effectively alleviate symptoms of neuropathic pain while reducing or eliminating adverse effects. This review aims to provide a comprehensive summary of the progress made in GPCRs allosteric modulators in the treatment of neuropathic pain, and discuss the potential benefits and adverse factors of this treatment. We will also concentrate on the development of biased agonists of GPCRs, and based on important examples of biased agonist development in recent years, we will describe universal strategies for designing structure-based biased agonists. It is foreseeable that, with the continuous improvement of GPCRs allosteric modulation and biased agonist theory, effective GPCRs allosteric drugs will eventually be available for the treatment of neuropathic pain with acceptable safety.
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Affiliation(s)
- Chunhao Zhu
- School of Pharmacy, Ningxia Medical University, Yinchuan 750004, China
- School of Basic Medical Science, Ningxia Medical University, Yinchuan 750004, China
| | - Xiaobing Lan
- School of Pharmacy, Ningxia Medical University, Yinchuan 750004, China
| | - Zhiqiang Wei
- Medicinal Chemistry and Bioinformatics Center, Ocean University of China, Qingdao 266100, China
| | - Jianqiang Yu
- School of Pharmacy, Ningxia Medical University, Yinchuan 750004, China
| | - Jian Zhang
- School of Pharmacy, Ningxia Medical University, Yinchuan 750004, China
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210023, China
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2
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Doyle MR, Martinez AR, Qiao R, Dirik S, Di Ottavio F, Pascasio G, Martin-Fardon R, Benner C, George O, Telese F, de Guglielmo G. Strain and sex-related behavioral variability of oxycodone dependence in rats. Neuropharmacology 2023; 237:109635. [PMID: 37327971 PMCID: PMC10353778 DOI: 10.1016/j.neuropharm.2023.109635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 06/18/2023]
Abstract
Over the past two decades, the escalating prescription of opioid medications for pain management has culminated in a widespread opioid epidemic, significantly impacting public health, social dynamics, and economic stability. The urgent need for improved treatments for opioid addiction necessitates a deeper understanding of its biological underpinnings, with genetic variations playing a crucial role in individual susceptibility to opioid use disorder (OUD) and influencing clinical practices. In this study, we leverage the genetic diversity of four rat strains (ACI/N, BN/NHsd, WKY/N, and F344/N) to examine the contribution of genetic factors to oxycodone metabolism and addiction-like behaviors. We used the extended access to intravenous oxycodone self-administration procedure (12 h/day, 0.15 mg/kg/injection) to comprehensively characterize oxycodone-related behaviors and pharmacokinetics. We measured escalation of oxycodone self-administration, motivation for drug consumption, tolerance to the analgesic effects of oxycodone, withdrawal-induced hyperalgesia, and oxycodone-induced respiratory depression. Additionally, we examined oxycodone-seeking behavior after four weeks of withdrawal by reintroducing the animals to environmental and cue stimuli previously associated with oxycodone self-administration. The findings revealed notable strain differences in several behavioral measures, including oxycodone metabolism. Intriguingly, BN/NHsd and WKY/N strains exhibited similar drug intake and escalation patterns but displayed significant disparities in oxycodone and oxymorphone metabolism. Minimal sex differences were observed within strains, primarily relating to oxycodone metabolism. In conclusion, this study identifies strain differences in the behavioral responses and pharmacokinetics associated with oxycodone self-administration in rats, providing a robust foundation for identifying genetic and molecular variants associated with various facets of the opioid addiction process.
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Affiliation(s)
- Michelle R Doyle
- Department of Psychiatry, University of California San Diego, School of Medicine, La Jolla, CA, USA; Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Angelica R Martinez
- Department of Psychiatry, University of California San Diego, School of Medicine, La Jolla, CA, USA
| | - Ran Qiao
- Department of Psychiatry, University of California San Diego, School of Medicine, La Jolla, CA, USA
| | - Selen Dirik
- Department of Psychiatry, University of California San Diego, School of Medicine, La Jolla, CA, USA
| | - Francesca Di Ottavio
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Glenn Pascasio
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Rémi Martin-Fardon
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Christopher Benner
- Department of Medicine, University of California San Diego, School of Medicine, La Jolla, CA, USA
| | - Olivier George
- Department of Psychiatry, University of California San Diego, School of Medicine, La Jolla, CA, USA
| | - Francesca Telese
- Department of Psychiatry, University of California San Diego, School of Medicine, La Jolla, CA, USA
| | - Giordano de Guglielmo
- Department of Psychiatry, University of California San Diego, School of Medicine, La Jolla, CA, USA.
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3
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Adhikary S, Williams JT. Cellular Tolerance Induced by Chronic Opioids in the Central Nervous System. Front Syst Neurosci 2022; 16:937126. [PMID: 35837149 PMCID: PMC9273719 DOI: 10.3389/fnsys.2022.937126] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 06/08/2022] [Indexed: 01/21/2023] Open
Abstract
Opioids are powerful analgesics that elicit acute antinociceptive effects through their action the mu opioid receptor (MOR). However opioids are ineffective for chronic pain management, in part because continuous activation of MORs induces adaptive changes at the receptor level and downstream signaling molecules. These adaptations include a decrease in receptor-effector coupling and changes to second messenger systems that can counteract the persistent activation of MORs by opioid agonists. Homeostatic regulation of MORs and downstream signaling cascades are viewed as precursors to developing tolerance. However, despite numerous studies identifying crucial mechanisms that contribute to opioid tolerance, no single regulatory mechanism that governs tolerance in at the cellular and systems level has been identified. Opioid tolerance is a multifaceted process that involves both individual neurons that contain MORs and neuronal circuits that undergo adaptations following continuous MOR activation. The most proximal event is the agonist/receptor interaction leading to acute cellular actions. This review discusses our understanding of mechanisms that mediate cellular tolerance after chronic opioid treatment that, in part, is mediated by agonist/receptor interaction acutely.
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4
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Minhas M, Limebeer CL, Strom E, Parker LA, Leri F. High fructose corn syrup alters behavioural and neurobiological responses to oxycodone in rats. Pharmacol Biochem Behav 2021; 205:173189. [PMID: 33845083 DOI: 10.1016/j.pbb.2021.173189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 04/05/2021] [Accepted: 04/06/2021] [Indexed: 11/30/2022]
Abstract
There are indications that sugars in the diet can play a role in vulnerability to opioid abuse. The current study examined a range of neuro-behavioural interactions between oxycodone (OXY) and high fructose corn syrup (HFCS). Male Sprague-Dawley rats had access to HFCS (0 or 50%) over 26 days in their home cages and were subsequently tested on place conditioning induced by 0, 0.16 and 2.5 mg/kg OXY (3 pairings of drug and saline, each 30 min), as well as on locomotor responses to 0, 0.16 and 2.5 mg/kg OXY, and in-vivo microdialysis was employed to measure dopamine (DA) levels in the nucleus accumbens (NAc) in response to 0 and 2.5 mg/kg OXY. A complex set of interactions between HFCS exposure and responses to OXY were observed: HFCS increased place preference induced by OXY, it enhanced the suppressant effect of OXY on locomotion, and it attenuated OXY-induced elevation in DA overflow in the NAc. Taken together, these findings suggest that nutrition has the potential to influence some responses to opioids which may be relevant to their abuse.
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Affiliation(s)
- Meenu Minhas
- Department of Psychology, University of Guelph, Ontario N1G 2W1, Canada
| | - Cheryl L Limebeer
- Department of Psychology, University of Guelph, Ontario N1G 2W1, Canada
| | - Evan Strom
- Department of Psychology, University of Guelph, Ontario N1G 2W1, Canada
| | - Linda A Parker
- Department of Psychology, University of Guelph, Ontario N1G 2W1, Canada
| | - Francesco Leri
- Department of Psychology, University of Guelph, Ontario N1G 2W1, Canada.
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5
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Abstract
Understanding the molecular biology of opioid analgesia is essential for its proper implementation and mechanistic approach to its modulation in order to maximize analgesia and minimize undesired effects. By appreciating the molecular mechanisms intrinsic to opioid analgesia, one can manipulate a molecular target to augment or diminish a specific effect using adjuvant drugs, select an appropriate opioid for opioid rotation or define a molecular target for new opioid drug development. In this review, we present the cellular and molecular mechanisms of opioid analgesia and that of the associated phenomena of tolerance, dependence, and hyperalgesia. The specific mechanisms highlighted are those that presently can be clinically addressed.
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6
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Soluble epoxide hydrolase inhibitor mediated analgesia lacks tolerance in rat models. Brain Res 2019; 1728:146573. [PMID: 31790682 DOI: 10.1016/j.brainres.2019.146573] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 11/05/2019] [Accepted: 11/27/2019] [Indexed: 12/28/2022]
Abstract
Effectively treating chronic pain remains a therapeutic challenge in the clinic. Recent evidence has shown the inhibition of the soluble epoxide hydrolase (sEH) to be an effective strategy to limit chronic pain in preclinical models, horses and companion animals. Determining the safety of sEH inhibition in addition to this demonstrated efficacy is a critical step to the further development of sEH inhibitors (sEHI) as analgesics. Here we describe a comparison of the sEHI TPPU with other first in class analgesics for human chronic pain. We assess the development of tolerance to the analgesia mediated by TPPU with extended use. We also assess for CNS effects by measuring changes in motor control and functioning. The sEHI are multimodal analgesics that have demonstrated potent efficacy against chronic pain. They have previously been tested and show no reward potential using operant methods. The results of the current experiments show that they lack motor function effects and also lack the development of tolerance with extended dosing.
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7
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Emery MA, Eitan S. Members of the same pharmacological family are not alike: Different opioids, different consequences, hope for the opioid crisis? Prog Neuropsychopharmacol Biol Psychiatry 2019; 92:428-449. [PMID: 30790677 DOI: 10.1016/j.pnpbp.2019.02.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 02/15/2019] [Accepted: 02/15/2019] [Indexed: 01/14/2023]
Abstract
Pain management is the specialized medical practice of modulating pain perception and thus easing the suffering and improving the life quality of individuals suffering from painful conditions. Since this requires the modulation of the activity of endogenous systems involved in pain perception, and given the large role that the opioidergic system plays in pain perception, opioids are currently the most effective pain treatment available and are likely to remain relevant for the foreseeable future. This contributes to the rise in opioid use, misuse, and overdose death, which is currently characterized by public health officials in the United States as an epidemic. Historically, the majority of preclinical rodent studies were focused on morphine. This has resulted in our understanding of opioids in general being highly biased by our knowledge of morphine specifically. However, recent in vitro studies suggest that direct extrapolation of research findings from morphine to other opioids is likely to be flawed. Notably, these studies suggest that different opioid analgesics (opioid agonists) engage different downstream signaling effects within the cell, despite binding to and activating the same receptors. This recognition implies that, in contrast to the historical status quo, different opioids cannot be made equivalent by merely dose adjustment. Notably, even at equianalgesic doses, different opioids could result in different beneficial and risk outcomes. In order to foster further translational research regarding drug-specific differences among opioids, here we review basic research elucidating differences among opioids in pharmacokinetics, pharmacodynamics, their capacity for second messenger pathway activation, and their interactions with the immune system and the dopamine D2 receptors.
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Affiliation(s)
- Michael A Emery
- Behavioral and Cellular Neuroscience, Department of Psychological and Brain Sciences, Texas A&M University, 4235 TAMU, College Station, TX 77843, USA; Interdisciplinary Program in Neuroscience, Texas A&M Institute for Neuroscience (TAMIN), College Station, TX, USA
| | - Shoshana Eitan
- Behavioral and Cellular Neuroscience, Department of Psychological and Brain Sciences, Texas A&M University, 4235 TAMU, College Station, TX 77843, USA; Interdisciplinary Program in Neuroscience, Texas A&M Institute for Neuroscience (TAMIN), College Station, TX, USA.
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8
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Munro G, Petersen S, Jansen-Olesen I, Olesen J. A unique inbred rat strain with sustained cephalic hypersensitivity as a model of chronic migraine-like pain. Sci Rep 2018; 8:1836. [PMID: 29382888 PMCID: PMC5789845 DOI: 10.1038/s41598-018-19901-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 01/04/2018] [Indexed: 02/07/2023] Open
Abstract
Animal models of migraine-like pain enabling ongoing study of behaviour typically involve the systemic administration of chemical vasodilators or dural administration of inflammatory algogens. However, neither method mediates prolonged effects on behavior indicative of enduring pathophysiological changes occurring within dural or trigeminal pain circuits. We generated successive generations of a unique inbred rat strain, spontaneous trigeminal allodynia (STA) rats, previously reported to exhibit an episodic migraine-like behavioural phenotype. We show that both male and female STA rats display robust and sustained reductions in periorbital thresholds to cutaneous mechanical stimulation. Otherwise, the general behavior (e.g. locomotor, grooming) of these rats appeared normal. In female STA rats, the mechanical hypersensitivity was confined to the cephalic region, manifested after puberty through adolescence, and was sustained into adulthood recapitulating the clinical manifestation of migraine. We exploited this hitherto unidentified chronic phenotype to show that the migraine-specific drugs sumatriptan (5-HT1B/1D receptor agonist) and olcegepant (CGRP receptor antagonist) could completely reverse cephalic hypersensitivity using a within subject cross-over paradigm. Our findings indicate that STA rats actually possess a phenotype indicative of migraine chronicity which is exquisitely sensitive to migraine therapeutics. This unique strain could prove to be an invaluable resource in preclinical migraine drug discovery.
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Affiliation(s)
- Gordon Munro
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Nordre Ringvej 69, 2600, Glostrup, Denmark.
| | - Steffen Petersen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Nordre Ringvej 69, 2600, Glostrup, Denmark
| | - Inger Jansen-Olesen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Nordre Ringvej 69, 2600, Glostrup, Denmark
| | - Jes Olesen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Nordre Ringvej 69, 2600, Glostrup, Denmark
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9
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Johnson TA, Milan-Lobo L, Che T, Ferwerda M, Lambu E, McIntosh NL, Li F, He L, Lorig-Roach N, Crews P, Whistler JL. Identification of the First Marine-Derived Opioid Receptor "Balanced" Agonist with a Signaling Profile That Resembles the Endorphins. ACS Chem Neurosci 2017; 8:473-485. [PMID: 27744679 DOI: 10.1021/acschemneuro.6b00167] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Opioid therapeutics are excellent analgesics, whose utility is compromised by dependence. Morphine (1) and its clinically relevant derivatives such as OxyContin (2), Vicodin (3), and Dilaudid (4) are "biased" agonists at the μ opioid receptor (OR), wherein they engage G protein signaling but poorly engage β-arrestin and the endocytic machinery. In contrast, endorphins, the endogenous peptide agonists for ORs, are potent analgesics, show reduced liability for tolerance and dependence, and engage both G protein and β-arrestin pathways as "balanced" agonists. We set out to determine if marine-derived alkaloids could serve as novel OR agonist chemotypes with a signaling profile distinct from morphine and more similar to the endorphins. Screening of 96 sponge-derived extracts followed by LC-MS-based purification to pinpoint the active compounds and subsequent evaluation of a mini library of related alkaloids identified two structural classes that modulate the ORs. These included the following: aaptamine (10), 9-demethyl aaptamine (11), demethyl (oxy)-aaptamine (12) with activity at the δ-OR (EC50: 5.1, 4.1, 2.3 μM, respectively) and fascaplysin (17), and 10-bromo fascaplysin (18) with activity at the μ-OR (EC50: 6.3, 4.2 μM respectively). An in vivo evaluation of 10 using δ-KO mice indicated its previously reported antidepressant-like effects are dependent on the δ-OR. Importantly, 17 functioned as a balanced agonist promoting both G protein signaling and β-arrestin recruitment along with receptor endocytosis similar to the endorphins. Collectively these results demonstrate the burgeoning potential for marine natural products to serve as novel lead compounds for therapeutic targets in neuroscience research.
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Affiliation(s)
- Tyler A. Johnson
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
- Department
of Natural Sciences and Mathematics, Dominican University of California, San Rafael, California 94901, United States
| | - Laura Milan-Lobo
- Department
of Neurology, University of California, San Francisco, California 94158, United States
| | - Tao Che
- National
Institute of Mental Health Psychoactive Drug Screening Program, University of North Carolina, Chapel Hill, North Carolina 27514, United States
| | - Madeline Ferwerda
- Department
of Neurology, University of California, San Francisco, California 94158, United States
| | - Eptisam Lambu
- Department
of Natural Sciences and Mathematics, Dominican University of California, San Rafael, California 94901, United States
| | - Nicole L. McIntosh
- Department
of Natural Sciences and Mathematics, Dominican University of California, San Rafael, California 94901, United States
| | - Fei Li
- Department
of Neurology, University of California, San Francisco, California 94158, United States
| | - Li He
- Department
of Neurology, University of California, San Francisco, California 94158, United States
| | - Nicholas Lorig-Roach
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Phillip Crews
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Jennifer L. Whistler
- Department
of Neurology, University of California, San Francisco, California 94158, United States
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10
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Kibaly C, Lin HY, Loh HH, Law PY. Spinal or supraspinal phosphorylation deficiency at the MOR C-terminus does not affect morphine tolerance in vivo. Pharmacol Res 2017; 119:153-168. [PMID: 28179123 DOI: 10.1016/j.phrs.2017.01.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 12/20/2016] [Accepted: 01/19/2017] [Indexed: 11/18/2022]
Abstract
The development of tolerance to morphine, one of the most potent analgesics, in the management of chronic pain is a significant clinical problem and its mechanisms are poorly understood. Morphine exerts its pharmacological effects via the μ-opioid receptor (MOR). Tolerance is highly connected to G-protein-coupled receptors (GPCR) phosphorylation and desensitization increase. Because morphine desensitization previously has been shown to be MOR phosphorylation- and ß-arrestin2-independent (in contrast to agonists such as fentanyl), we examined the contribution of phosphorylation of the entire C-terminus to the development of antinociceptive tolerance to the partial (morphine) and full (fentanyl) MOR agonists in vivo. In MOR knockout (MORKO) mice, we delivered via lentivirus the genes encoding the wild-type MOR (WTMOR) or a phosphorylation-deficient MOR (Cterm(-S/T)MOR) in which all of the serine and threonine residues were mutated to alanine into the ventrolateral periaqueductal grey matter (vlPAG) or lumbar spinal cord (SC), structures that are involved in nociception. We compared the analgesic ED50 in WTMOR- and Cterm(-S/T)MOR-expressing MORKO mice before and after morphine or fentanyl tolerance was induced. Morphine acute antinociception was partially restored in WTMOR- or Cterm(-S/T)MOR-transferred MORKO mice. Fentanyl acute antinociception was observed only in MORKO mice with the transgenes expressed in the SC. Morphine antinociceptive tolerance was not affected by expressing Cterm(-S/T)MOR in the vlPAG or SC of MORKO mice. Fentanyl-induced tolerance in MORKO mice expressing WTMOR or Cterm(-S/T)MOR, is greater than morphine-induced tolerance. Thus, MOR C-terminus phosphorylation does not appear to be critical for morphine tolerance in vivo.
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Affiliation(s)
- Cherkaouia Kibaly
- Department of Pharmacology and Basic Research Center on Molecular and Cell Biology of Drug Addiction, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Hong-Yiou Lin
- Beaumont Hospital, 3601 West 13 Mile Road, Royal Oak, MI 48073, USA
| | - Horace H Loh
- Department of Pharmacology and Basic Research Center on Molecular and Cell Biology of Drug Addiction, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ping-Yee Law
- Department of Pharmacology and Basic Research Center on Molecular and Cell Biology of Drug Addiction, University of Minnesota, Minneapolis, MN 55455, USA
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11
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Abstract
Medication-assisted treatment of opioid use disorder with physiological dependence at least doubles rates of opioid-abstinence outcomes in randomized, controlled trials comparing psychosocial treatment of opioid use disorder with medication versus with placebo or no medication. This article reviews the current evidence for medication-assisted treatment of opioid use disorder and also presents clinical practice imperatives for preventing opioid overdose and the transmission of infectious disease. The evidence strongly supports the use of agonist therapies to reduce opioid use and to retain patients in treatment, with methadone maintenance remaining the gold standard of care. Combined buprenorphine/naloxone, however, also demonstrates significant efficacy and favorable safety and tolerability in multiple populations, including youth and prescription opioid-dependent individuals, as does buprenorphine monotherapy in pregnant women. The evidence for antagonist therapies is weak. Oral naltrexone demonstrates poor adherence and increased mortality rates, although the early evidence looks more favorable for extended-release naltrexone, which has the advantages that it is not subject to misuse or diversion and that it does not present a risk of overdose on its own. Two perspectives-individualized treatment and population management-are presented for selecting among the three available Food and Drug Administration-approved maintenance therapies for opioid use disorder. The currently unmet challenges in treating opioid use disorder are discussed, as are the directions for future research.
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12
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Real-time imaging of mu opioid receptors by total internal reflection fluorescence microscopy. Methods Mol Biol 2015; 1230:79-86. [PMID: 25293317 PMCID: PMC4836948 DOI: 10.1007/978-1-4939-1708-2_6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Receptor trafficking and signaling are intimately linked, especially in the Mu opioid receptor (MOR) where ligand-dependent endocytosis and recycling have been associated with opioid tolerance and dependence. Ligands of MOR can induce receptor endocytosis and recycling within minutes of exposure in heterologous systems and cultured neurons. Endocytosis removes desensitized receptors after their activation from the plasma membrane, while recycling promotes resensitization by delivering functional receptors to the cell surface. These rapid mechanisms can escape traditional analytical methods where only snapshots are obtained from highly dynamic events.Total internal reflection fluorescence (TIRF) microscopy is a powerful tool that can be used to investigate, in real time, surface trafficking events at the single molecule level. The restricted excitation of fluorophores located at or near the plasma membrane in combination with high sensitivity quantitative cameras makes it possible to record and analyze individual endocytic and recycling event in real time. In this chapter, we describe a TIRF microscopy protocol to investigate in real time, the ligand-dependent MOR trafficking in Human Embryonic Kidney 293 cells and dissociated striatal neuronal cultures. This approach can provide unique spatio-temporal resolution to understand the fundamental events controlling MOR trafficking at the plasma membrane.
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13
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Allouche S, Noble F, Marie N. Opioid receptor desensitization: mechanisms and its link to tolerance. Front Pharmacol 2014; 5:280. [PMID: 25566076 PMCID: PMC4270172 DOI: 10.3389/fphar.2014.00280] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/02/2014] [Indexed: 02/04/2023] Open
Abstract
Opioid receptors (OR) are part of the class A of G-protein coupled receptors and the target of the opiates, the most powerful analgesic molecules used in clinic. During a protracted use, a tolerance to analgesic effect develops resulting in a reduction of the effectiveness. So understanding mechanisms of tolerance is a great challenge and may help to find new strategies to tackle this side effect. This review will summarize receptor-related mechanisms that could underlie tolerance especially receptor desensitization. We will focus on the latest data obtained on molecular mechanisms involved in opioid receptor desensitization: phosphorylation, receptor uncoupling, internalization, and post-endocytic fate of the receptor.
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Affiliation(s)
- Stéphane Allouche
- Laboratoire de Signalisation, Électrophysiologie et Imagerie des Lésions D'ischémie-Reperfusion Myocardique, Université de Caen, UPRES EA 4650, IFR 146 ICORE Caen, France
| | - Florence Noble
- Centre National de la Recherche Scientifique, ERL 3649 Paris, France ; Institut National de la Santé et de la Recherche Médicale, UMR-S 1124 Paris, France ; Université Paris Descartes, Neuroplasticité et Thérapies des Addictions Paris, France
| | - Nicolas Marie
- Centre National de la Recherche Scientifique, ERL 3649 Paris, France ; Institut National de la Santé et de la Recherche Médicale, UMR-S 1124 Paris, France ; Université Paris Descartes, Neuroplasticité et Thérapies des Addictions Paris, France
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14
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Illing S, Mann A, Schulz S. Heterologous regulation of agonist-independent μ-opioid receptor phosphorylation by protein kinase C. Br J Pharmacol 2014; 171:1330-40. [PMID: 24308893 DOI: 10.1111/bph.12546] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 11/12/2013] [Accepted: 12/02/2013] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND AND PURPOSE Homologous agonist-induced phosphorylation of the μ-opioid receptor (MOR) is initiated at the carboxyl-terminal S375, followed by phosphorylation of T370, T376 and T379. In HEK293 cells, this sequential and hierarchical multi-site phosphorylation is specifically mediated by G-protein coupled receptor kinases 2 and 3. In the present study, we provide evidence for a selective and dose-dependent phosphorylation of T370 after activation of PKC by phorbol esters. EXPERIMENTAL APPROACH We used a combination of phospho site-specific antibodies, kinase inhibitors and siRNA knockdown screening to identify kinases that mediate agonist-independent phosphorylation of the MOR in HEK293 cells. In addition, we show with phospho site-specific antibodies were also used to study constitutive phosphorylation at S363 of MORs in mouse brain in vivo. KEY RESULTS Activation of PKC by phorbol esters or heterologous activation of substance P receptors co-expressed with MORs in the same cell induced a selective and dose-dependent phosphorylation of T370 that specifically requires the PKCα isoform. Inhibition of PKC activity did not compromise homologous agonist-driven T370 phosphorylation. In addition, S363 was constitutively phosphorylated in both HEK293 cells and mouse brain in vivo. Constitutive S363 phosphorylation required ongoing PKC activity. When basal PKC activity was decreased, S363 was also a substrate for homologous agonist-stimulated phosphorylation. CONCLUSIONS AND IMPLICATIONS Our results have disclosed novel mechanisms of heterologous regulation of MOR phosphorylation by PKC. These findings represent a useful starting point for definitive experiments elucidating the exact contribution of PKC-driven MOR phosphorylation to diminished MOR responsiveness in morphine tolerance and pathological pain.
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Affiliation(s)
- Susann Illing
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
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15
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Brandenburg LO, Pufe T, Koch T. Role of phospholipase d in g-protein coupled receptor function. MEMBRANES 2014; 4:302-18. [PMID: 24995811 PMCID: PMC4194036 DOI: 10.3390/membranes4030302] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 06/24/2014] [Accepted: 06/25/2014] [Indexed: 01/09/2023]
Abstract
Prolonged agonist exposure of many G-protein coupled receptors induces a rapid receptor phosphorylation and uncoupling from G-proteins. Resensitization of these desensitized receptors requires endocytosis and subsequent dephosphorylation. Numerous studies show the involvement of phospholipid-specific phosphodiesterase phospholipase D (PLD) in the receptor endocytosis and recycling of many G-protein coupled receptors e.g., opioid, formyl or dopamine receptors. The PLD hydrolyzes the headgroup of a phospholipid, generally phosphatidylcholine (PC), to phosphatidic acid (PA) and choline and is assumed to play an important function in cell regulation and receptor trafficking. Protein kinases and GTP binding proteins of the ADP-ribosylation and Rho families regulate the two mammalian PLD isoforms 1 and 2. Mammalian and yeast PLD are also potently stimulated by phosphatidylinositol 4,5-bisphosphate. The PA product is an intracellular lipid messenger. PLD and PA activities are implicated in a wide range of physiological processes and diseases including inflammation, diabetes, oncogenesis or neurodegeneration. This review discusses the characterization, structure, and regulation of PLD in the context of membrane located G-protein coupled receptor function.
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Affiliation(s)
- Lars-Ove Brandenburg
- Department of Anatomy and Cell Biology, RWTH Aachen University, Wendlingweg 2, D-52074 Aachen, Germany.
| | - Thomas Pufe
- Department of Anatomy and Cell Biology, RWTH Aachen University, Wendlingweg 2, D-52074 Aachen, Germany.
| | - Thomas Koch
- Department of Pharmacology and Toxicology, Otto-von-Guericke-University Magdeburg, D-39120 Magdeburg, Germany.
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16
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Respiratory effects of buprenorphine/naloxone alone and in combination with diazepam in naive and tolerant rats. Toxicol Lett 2014; 228:75-84. [DOI: 10.1016/j.toxlet.2014.04.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 04/09/2014] [Accepted: 04/10/2014] [Indexed: 11/18/2022]
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Macey TA, Bobeck EN, Suchland KL, Morgan MM, Ingram SL. Change in functional selectivity of morphine with the development of antinociceptive tolerance. Br J Pharmacol 2014; 172:549-61. [PMID: 24666417 DOI: 10.1111/bph.12703] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 03/14/2014] [Accepted: 03/18/2014] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE Opioids, such as morphine, are the most effective treatment for pain but their efficacy is diminished with the development of tolerance following repeated administration. Recently, we found that morphine activated ERK in opioid-tolerant but not in naïve rats, suggesting that morphine activation of μ-opioid receptors is altered following repeated morphine administration. Here, we have tested the hypothesis that μ-opioid receptor activation of ERK in the ventrolateral periaqueductal gray (vlPAG) is dependent on dynamin, a protein implicated in receptor endocytosis. EXPERIMENTAL APPROACH Rats were made tolerant to repeated microinjections of morphine into the vlPAG. The effects of dynamin on ERK activation and antinociception were assessed by microinjecting myristoylated dominant-negative dynamin peptide (Dyn-DN) or a scrambled control peptide into the vlPAG. Microinjection of a fluorescent dermorphin analogue (DERM-A594) into the vlPAG was used to monitor μ-opioid receptor internalization. KEY RESULTS Morphine did not activate ERK and Dyn-DN administration had no effect on morphine-induced antinociception in saline-pretreated rats. In contrast, morphine-induced ERK activation in morphine-pretreated rats that was blocked by Dyn-DN administration. Dyn-DN also inhibited morphine antinociception. Finally, morphine reduced DERM-A594 internalization only in morphine-tolerant rats indicating that μ-opioid receptors were internalized and unavailable to bind DERM-A594. CONCLUSIONS AND IMPLICATIONS Repeated morphine administration increased μ-opioid receptor activation of ERK signalling via a dynamin-dependent mechanism. These results demonstrate that the balance of agonist signalling to G-protein and dynamin-dependent pathways is altered, effectively changing the functional selectivity of the agonist-receptor complex. 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)
- T A Macey
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, USA
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18
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Joanna L, Talarek S, Orzelska J, Fidecka S, Wujec M, Plech T. The antinociceptive effect of 4-substituted derivatives of 5-(4-chlorophenyl)-2-(morpholin-4-ylmethyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione in mice. Naunyn Schmiedebergs Arch Pharmacol 2013; 387:367-75. [PMID: 24326964 PMCID: PMC3964309 DOI: 10.1007/s00210-013-0938-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 11/06/2013] [Indexed: 01/01/2023]
Abstract
The aim of the present experiments was to examine the antinociceptive activity of 4-substituted derivatives of 5-(4-chlorophenyl)-2-(morpholin-4-ylmethyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione in mice. The compounds were synthesized using the so-called Mannich reaction and their structures were confirmed using IR and 1H-NMR spectra. The antinociceptive activity was investigated in two behavioral tests: the hot plate test and the writhing test. For preliminary estimation of other behavioral effects, the locomotor activity of mice, the motor coordination in the rota-rod test, and the myorelaxation in the chimney test were also studied. The changes in body temperature of animals were also recorded. We demonstrated that all examined compounds produced antinociceptive effect, both in the hot plate test and in the writhing test, without impact on the motor coordination and myorelaxation of animals. The pharmacological effect of all drugs has been developed within 60 min after administration of drugs; and in two cases (T-103 and T-104), it has been a short-lasting effect (up to 90 min). Two compounds (T-100 and T-102) also inhibited the locomotor activity of animals. T-104 induced the changes in body temperature of mice. Generally, we demonstrated that combination of two different heterocyclic systems (morpholine and 1,2,4-triazole) might be beneficial for reduction of nociception.
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19
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Doll C, Pöll F, Peuker K, Loktev A, Glück L, Schulz S. Deciphering µ-opioid receptor phosphorylation and dephosphorylation in HEK293 cells. Br J Pharmacol 2013; 167:1259-70. [PMID: 22725608 DOI: 10.1111/j.1476-5381.2012.02080.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE The molecular basis of agonist-selective signalling at the µ-opioid receptor is poorly understood. We have recently shown that full agonists such as [D-Ala(2)-MePhe(4)-Gly-ol]enkephalin (DAMGO) stimulate the phosphorylation of a number of carboxyl-terminal phosphate acceptor sites including threonine 370 (Thr(370)) and serine 375 (Ser(375)), and that is followed by a robust receptor internalization. In contrast, morphine promotes a selective phosphorylation of Ser(375) without causing rapid receptor internalization. EXPERIMENTAL APPROACH Here, we identify kinases and phosphatases that mediate agonist-dependent phosphorylation and dephosphorylation of the µ-opioid receptor using a combination of phosphosite-specific antibodies and siRNA knock-down screening in HEK293 cells. KEY RESULTS We found that DAMGO-driven phosphorylation of Thr(370) and Ser(375) was preferentially catalysed by G-protein-coupled receptor kinases (GRKs) 2 and 3, whereas morphine-driven Ser(375) phosphorylation was preferentially catalysed by GRK5. On the functional level, inhibition of GRK expression resulted in enhanced µ-opioid receptor signalling and reduced receptor internalization. Analysis of GRK5-deficient mice revealed that GRK5 selectively contributes to morphine-induced Ser(375) phosphorylation in brain tissue. We also identified protein phosphatase 1γ as a µ-opioid receptor phosphatase that catalysed Thr(370) and Ser(375) dephosphorylation at or near the plasma membrane within minutes after agonist removal, which in turn facilitates receptor recycling. CONCLUSIONS AND IMPLICATIONS Together, the morphine-activated µ-opioid receptor is a good substrate for phosphorylation by GRK5 but a poor substrate for GRK2/3. GRK5 phosphorylates µ-opioid receptors selectively on Ser(375), which is not sufficient to drive significant receptor internalization.
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Affiliation(s)
- Christian Doll
- Institute of Pharmacology and Toxicology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany
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20
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Williams JT, Ingram SL, Henderson G, Chavkin C, von Zastrow M, Schulz S, Koch T, Evans CJ, Christie MJ. Regulation of μ-opioid receptors: desensitization, phosphorylation, internalization, and tolerance. Pharmacol Rev 2013; 65:223-54. [PMID: 23321159 DOI: 10.1124/pr.112.005942] [Citation(s) in RCA: 585] [Impact Index Per Article: 53.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Morphine and related µ-opioid receptor (MOR) agonists remain among the most effective drugs known for acute relief of severe pain. A major problem in treating painful conditions is that tolerance limits the long-term utility of opioid agonists. Considerable effort has been expended on developing an understanding of the molecular and cellular processes that underlie acute MOR signaling, short-term receptor regulation, and the progression of events that lead to tolerance for different MOR agonists. Although great progress has been made in the past decade, many points of contention and controversy cloud the realization of this progress. This review attempts to clarify some confusion by clearly defining terms, such as desensitization and tolerance, and addressing optimal pharmacological analyses for discerning relative importance of these cellular mechanisms. Cellular and molecular mechanisms regulating MOR function by phosphorylation relative to receptor desensitization and endocytosis are comprehensively reviewed, with an emphasis on agonist-biased regulation and areas where knowledge is lacking or controversial. The implications of these mechanisms for understanding the substantial contribution of MOR signaling to opioid tolerance are then considered in detail. While some functional MOR regulatory mechanisms contributing to tolerance are clearly understood, there are large gaps in understanding the molecular processes responsible for loss of MOR function after chronic exposure to opioids. Further elucidation of the cellular mechanisms that are regulated by opioids will be necessary for the successful development of MOR-based approaches to new pain therapeutics that limit the development of tolerance.
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Affiliation(s)
- John T Williams
- Vollum Institute, Oregon Health Sciences University, Portland, Oregon, USA
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21
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Allouche S, Le Marec T, Noble F, Marie N. Different patterns of administration modulate propensity of methadone and buprenorphine to promote locomotor sensitization in mice. Prog Neuropsychopharmacol Biol Psychiatry 2013; 40:286-91. [PMID: 23103550 DOI: 10.1016/j.pnpbp.2012.10.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 10/04/2012] [Accepted: 10/18/2012] [Indexed: 10/27/2022]
Abstract
Following chronic administration of morphine a locomotor sensitization is usually observed. This behavioral sensitization is influenced by numerous factors including the administration pattern. While methadone and buprenorphine are the two main treatments for opioid dependence, literature about their ability to promote long-term sensitization after chronic exposure/withdrawal are scarce considering the long-term treatments used in patients. In this study we investigated the propensity of these two opioids to promote behavioral sensitization using different patterns of administration. Mice were treated with escalating doses of methadone or buprenorphine during 5 days given either once (binge) or three times a day (TTD). After 1-, 7-, 14- and 35-days washout period, animals were challenged with either morphine or the opioid used for the chronic treatment to evaluate heterologous or homologous sensitization, respectively. While methadone produced homologous and heterologous sensitization either with the binge or the TTD regimen over the whole period studied, buprenorphine induced a transient heterologous locomotor sensitization on day 14 only with the binge administration. Our data evidenced a different ability of methadone and buprenorphine to produce behavioral sensitization and that the pattern of drug exposure determined the expression of this phenomenon.
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Affiliation(s)
- Stéphane Allouche
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8206, France
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22
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Just S, Illing S, Trester-Zedlitz M, Lau EK, Kotowski SJ, Miess E, Mann A, Doll C, Trinidad JC, Burlingame AL, von Zastrow M, Schulz S. Differentiation of opioid drug effects by hierarchical multi-site phosphorylation. Mol Pharmacol 2012; 83:633-9. [PMID: 23239825 DOI: 10.1124/mol.112.082875] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Differences in the ability of opioid drugs to promote regulated endocytosis of μ-opioid receptors are related to their tendency to produce drug tolerance and dependence. Here we show that drug-specific differences in receptor internalization are determined by a conserved, 10-residue sequence in the receptor's carboxyl-terminal cytoplasmic tail. Diverse opioids induce receptor phosphorylation at serine (S)375, present in the middle of this sequence, but opioids differ markedly in their ability to drive higher-order phosphorylation on flanking residues [threonine (T)370, T376, and T379]. Multi-phosphorylation is required for the endocytosis-promoting activity of this sequence and occurs both sequentially and hierarchically, with S375 representing the initiating site. Higher-order phosphorylation involving T370, T376, and T379 specifically requires GRK2/3 isoforms, and the same sequence controls opioid receptor internalization in neurons. These results reveal a biochemical mechanism differentiating the endocytic activity of opioid drugs.
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Affiliation(s)
- Sascha Just
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Drackendorfer Straße 1, D-07747 Jena, Germany.
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23
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Characterization of the antinociceptive effects of the individual isomers of methadone after acute and chronic administrations. Behav Pharmacol 2011; 22:548-57. [PMID: 21836464 DOI: 10.1097/fbp.0b013e328349ab0d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Methadone is a long-acting opioid used in the treatment of various pain states and substitution therapy in heroin addiction. Extensive behavioral characterization has been carried out using the racemate, but limited investigation has been performed with the individual isomers. The L-isomer is a potent opioid agonist, whereas the D-isomer has weak µ-opioid activity and has also been shown to possess N-methyl-D-aspartate antagonist properties in vitro. The acute antinociceptive effects of the isomers were evaluated in rats using a warm-water, tail-withdrawal procedure at two stimulus intensities (50° and 55°C). Increasing dose ratios of D-methadone to L-methadone were administered chronically to determine the ability of the D-isomer to modulate antinociceptive tolerance to the L-isomer. Acutely, both L-methadone (0.1-5.6 mg/kg, subcutaneously) and D-methadone (3.0-56.0 mg/kg, subcutaneously) produced antinociception, although the efficacy of the D-isomer was limited at 55°C. These effects were dose dependently blocked by naltrexone (0.01-1.0 mg/kg, subcutaneously). Administered chronically, D-methadone (1.7-10 mg/kg, subcutaneously) dose dependently blocked tolerance development to the L-isomer (1.7 mg/kg, subcutaneously). These findings support the antinociceptive effects of the isomers being opioid receptor mediated with the L-isomer functioning as a full-efficacy agonist, whereas the D-isomer seems to have lower efficacy. The ability of nonracemic doses of the D-isomer to prevent tolerance development to the L-isomer may be attributed to partial µ-agonist activity; however, N-methyl-D-aspartate antagonist activity cannot be discounted.
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24
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Analgesic tolerance to high-efficacy agonists but not to morphine is diminished in phosphorylation-deficient S375A μ-opioid receptor knock-in mice. J Neurosci 2011; 31:13890-6. [PMID: 21957251 DOI: 10.1523/jneurosci.2304-11.2011] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Morphine is one of the most potent analgesic drugs. However, the utility of morphine in the management of chronic pain is limited by its rapid development of tolerance. Morphine exerts all of its pharmacological effects via the μ-opioid receptor. In many systems, tolerance is associated with phosphorylation and desensitization of G-protein-coupled receptors (GPCRs). In case of the μ-opioid receptor, phosphorylation occurs in an agonist-selective manner. High-efficacy agonists such as [d-Ala(2)-MePhe(4)-Gly-ol]enkephalin (DAMGO), fentanyl, or etonitazene stimulate the phosphorylation of both C-terminal threonine 370 (T370) and serine 375 (S375). In contrast, morphine promotes the phosphorylation of S375 but fails to stimulate T370 phosphorylation. Here, we have assessed the contribution of S375 phosphorylation to the development of antinociceptive tolerance to high- and low-efficacy μ agonists in vivo. We show that S375 phosphorylation of the μ-opioid receptor occurs in intact mouse brain in a dose-dependent manner after administration of morphine, fentanyl, or etonitazene. In knock-in mice expressing the phosphorylation-deficient S375A mutant of the μ-opioid receptor, morphine and fentanyl exhibited greater dose-dependent antinociceptive responses than in wild-type mice. However, acute and chronic tolerance to morphine was retained in S375A mutant mice. In contrast, antinociceptive tolerance after repeated subcutaneous application of etonitazene or repeated intracerebroventricular application of DAMGO was diminished. Thus, tolerance to μ agonists with different efficacies develops through distinct pathways. Whereas tolerance induced by DAMGO or etonitazene requires agonist-driven phosphorylation of S375, the development and maintenance of antinociceptive tolerance to morphine occurs independent of S375 phosphorylation.
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25
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Raehal KM, Schmid CL, Groer CE, Bohn LM. Functional selectivity at the μ-opioid receptor: implications for understanding opioid analgesia and tolerance. Pharmacol Rev 2011; 63:1001-19. [PMID: 21873412 DOI: 10.1124/pr.111.004598] [Citation(s) in RCA: 197] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Opioids are the most effective analgesic drugs for the management of moderate or severe pain, yet their clinical use is often limited because of the onset of adverse side effects. Drugs in this class produce most of their physiological effects through activation of the μ opioid receptor; however, an increasing number of studies demonstrate that different opioids, while presumably acting at this single receptor, can activate distinct downstream responses, a phenomenon termed functional selectivity. Functional selectivity of receptor-mediated events can manifest as a function of the drug used, the cellular or neuronal environment examined, or the signaling or behavioral measure recorded. This review summarizes both in vitro and in vivo work demonstrating functional selectivity at the μ opioid receptor in terms of G protein coupling, receptor phosphorylation, interactions with β-arrestins, receptor desensitization, internalization and signaling, and details on how these differences may relate to the progression of analgesic tolerance after their extended use.
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Affiliation(s)
- Kirsten M Raehal
- Molecular Therapeutics and Neuroscience, The Scripps Research Institute, Jupiter, Florida, USA
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26
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Nagi K, Piñeyro G. Regulation of opioid receptor signalling: implications for the development of analgesic tolerance. Mol Brain 2011; 4:25. [PMID: 21663702 PMCID: PMC3138391 DOI: 10.1186/1756-6606-4-25] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 06/13/2011] [Indexed: 11/10/2022] Open
Abstract
Opiate drugs are the most effective analgesics available but their clinical use is restricted by severe side effects. Some of these undesired actions appear after repeated administration and are related to adaptive changes directed at counteracting the consequences of sustained opioid receptor activation. Here we will discuss adaptations that contribute to the development of tolerance. The focus of the first part of the review is set on molecular mechanisms involved in the regulation of opioid receptor signalling in heterologous expression systems and neurons. In the second part we assess how adaptations that take place in vivo may contribute to analgesic tolerance developed during repeated opioid administration.
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Affiliation(s)
- Karim Nagi
- Département de Pharmacologie, Faculté de Médecine, Université de Montréal, Canada
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27
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Berger AC, Whistler JL. Morphine-induced mu opioid receptor trafficking enhances reward yet prevents compulsive drug use. EMBO Mol Med 2011; 3:385-97. [PMID: 21656686 PMCID: PMC3394511 DOI: 10.1002/emmm.201100144] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 03/29/2011] [Accepted: 03/31/2011] [Indexed: 01/08/2023] Open
Abstract
Morphine, heroin and other commonly abused opioids induce little mu opioid receptor (MOR) trafficking compared to endogenous opioids. We utilized knock-in mice expressing a mutant recycling MOR (RMOR) that desensitizes and is internalized in response to morphine to show that facilitating MOR trafficking not only enhances morphine reward but, despite this, reduces the development of addiction-like behaviours. To demonstrate this, we developed a novel model of the transition from controlled to compulsive drug use that recapitulates many features of human addiction, including persistent drug seeking despite adverse consequences and a decreased preference for alternative rewards. These behaviours emerged spontaneously in wild-type but not RMOR mice, and their intensity predicted the reinstatement of morphine seeking after extended abstinence, while prior morphine intake did not. These results confirm previous findings in the rat that addiction can be dissociated from both reward and consumption. Most importantly, these results demonstrate that one can simultaneously reduce the ‘addictiveness’ of morphine and enhance its desirable effects by promoting agonist-induced MOR trafficking.
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Affiliation(s)
- Amy Chang Berger
- Neuroscience Program, University of California, San Francisco, Ernest Gallo Clinic and Research Center, 5858 Horton Street, Suite 200, Emeryville, CA 94608, USA
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28
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Recovery from mu-opioid receptor desensitization after chronic treatment with morphine and methadone. J Neurosci 2011; 31:4434-43. [PMID: 21430144 DOI: 10.1523/jneurosci.4874-10.2011] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Chronic treatment with morphine results in a decrease in μ-opioid receptor sensitivity, an increase in acute desensitization, and a reduction in the recovery from acute desensitization in locus ceruleus neurons. With acute administration, morphine is unlike many other opioid agonists in that it does not mediate robust acute desensitization or induce receptor trafficking. This study compares μ-opioid receptor desensitization and trafficking in brain slices taken from rats treated for 6-7 d with a range of doses of morphine (60, 30, and 15 mg · kg(-1) · d(-1)) and methadone (60, 30, and 5 mg · kg(-1) · d(-1)) applied by subcutaneous implantation of osmotic minipumps. Mice were treated with 45 mg · kg(-1) · d(-1). In morphine-treated animals, recovery from acute [Met](5)enkephalin-induced desensitization and receptor recycling was diminished. In contrast, recovery and recycling were unchanged in slices from methadone-treated animals. Remarkably the reduced recovery from desensitization and receptor recycling found in slices from morphine-treated animals were not observed in animals lacking β-arrestin-2. Furthermore, pharmacological inhibition of G-protein receptor kinase 2 (GRK2), although not affecting the ability of [Met](5)enkephalin to induce desensitization, acutely reversed the delay in recovery from desensitization produced by chronic morphine treatment. These results characterize a previously unidentified function of the GRK/arrestin system in mediating opioid regulation in response to chronic morphine administration. They also suggest that the GRK/arrestin system, rather than serving as a primary mediator of acute desensitization, controls recovery from desensitization by regulating receptor reinsertion to the plasma membrane after chronic treatment with morphine. The sustained GRK/arrestin-dependent desensitization is another way in which morphine and methadone are distinguished.
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29
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He L, Whistler JL. Chronic ethanol consumption in rats produces opioid antinociceptive tolerance through inhibition of mu opioid receptor endocytosis. PLoS One 2011; 6:e19372. [PMID: 21602922 PMCID: PMC3094338 DOI: 10.1371/journal.pone.0019372] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 04/01/2011] [Indexed: 02/07/2023] Open
Abstract
It is well known that the mu-opioid receptor (MOR) plays an important role in the rewarding properties of ethanol. However, it is less clear how chronic ethanol consumption affects MOR signaling. Here, we demonstrate that rats with prolonged voluntary ethanol consumption develop antinociceptive tolerance to opioids. Signaling through the MOR is controlled at many levels, including via the process of endocytosis. Importantly, agonists at the MOR that promote receptor endocytosis, such as the endogenous peptides enkephalin and β-endorphin, show a reduced propensity to promote antinociceptive tolerance than do agonists, like morphine, which do not promote receptor endocytosis. These observations led us to examine whether chronic ethanol consumption produced opioid tolerance by interfering with MOR endocytosis. Indeed, here we show that chronic ethanol consumption inhibits the endocytosis of MOR in response to opioid peptide. This loss of endocytosis was accompanied by a dramatic decrease in G protein coupled receptor kinase 2 (GRK2) protein levels after chronic drinking, suggesting that loss of this component of the trafficking machinery could be a mechanism by which endocytosis is lost. We also found that MOR coupling to G-protein was decreased in ethanol-drinking rats, providing a functional explanation for loss of opioid antinociception. Together, these results suggest that chronic ethanol drinking alters the ability of MOR to endocytose in response to opioid peptides, and consequently, promotes tolerance to the effects of opioids.
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Affiliation(s)
- Li He
- Ernest Gallo Clinic and Research Center, University of California, Emeryville, California, United States of America
| | - Jennifer L. Whistler
- Ernest Gallo Clinic and Research Center, University of California, Emeryville, California, United States of America
- Department of Neurology, University of California, San Francisco, California, United States of America
- * E-mail:
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Listos J, Talarek S, Poleszak E, Wróbel A, Fidecka S. Attenuating effect of adenosine receptor agonists on the development of behavioral sensitization induced by sporadic treatment with morphine. Pharmacol Biochem Behav 2011; 98:356-61. [DOI: 10.1016/j.pbb.2011.01.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 01/17/2011] [Accepted: 01/24/2011] [Indexed: 10/18/2022]
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31
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Buprenorphine-induced hyperalgesia in the rat. Eur J Pharmacol 2011; 651:89-95. [DOI: 10.1016/j.ejphar.2010.10.083] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 10/13/2010] [Accepted: 10/31/2010] [Indexed: 11/19/2022]
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32
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McPherson J, Rivero G, Baptist M, Llorente J, Al-Sabah S, Krasel C, Dewey WL, Bailey CP, Rosethorne EM, Charlton SJ, Henderson G, Kelly E. μ-opioid receptors: correlation of agonist efficacy for signalling with ability to activate internalization. Mol Pharmacol 2010; 78:756-66. [PMID: 20647394 DOI: 10.1124/mol.110.066613] [Citation(s) in RCA: 214] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We have compared the ability of a number of μ-opioid receptor (MOPr) ligands to activate G proteins with their abilities to induce MOPr phosphorylation, to promote association of arrestin-3 and to cause MOPr internalization. For a model of G protein-coupled receptor (GPCR) activation where all agonists stabilize a single active conformation of the receptor, a close correlation between signaling outputs might be expected. Our results show that overall there is a very good correlation between efficacy for G protein activation and arrestin-3 recruitment, whereas a few agonists, in particular endomorphins 1 and 2, display apparent bias toward arrestin recruitment. The agonist-induced phosphorylation of MOPr at Ser(375), considered a key step in MOPr regulation, and agonist-induced internalization of MOPr were each found to correlate well with arrestin-3 recruitment. These data indicate that for the majority of MOPr agonists the ability to induce receptor phosphorylation, arrestin-3 recruitment, and internalization can be predicted from their ability as agonists to activate G proteins. For the prototypic MOPr agonist morphine, its relatively weak ability to induce MOPr internalization can be explained by its low agonist efficacy.
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Affiliation(s)
- Jamie McPherson
- Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, Bristol, BS8 1TD, UK
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Chiang YC, Hung TW, Lee CWS, Yan JY, Ho IK. Enhancement of tolerance development to morphine in rats prenatally exposed to morphine, methadone, and buprenorphine. J Biomed Sci 2010; 17:46. [PMID: 20529288 PMCID: PMC2890660 DOI: 10.1186/1423-0127-17-46] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 06/07/2010] [Indexed: 12/02/2022] Open
Abstract
Background Abuse of addictive substances is a serious problem that has a significant impact on areas such as health, the economy, and public safety. Heroin use among young women of reproductive age has drawn much attention around the world. However, there is a lack of information on effects of prenatal exposure to opioids on their offspring. In this study, an animal model was established to study effects of prenatal exposure to opioids on offspring. Methods Female pregnant Sprague-Dawley rats were sub-grouped to receive (1) vehicle, (2) 2-4 mg/kg morphine (1 mg/kg increment per week), (3) 7 mg/kg methadone, and (4) 3 mg/kg buprenorphine, subcutaneously, once or twice a day from E3 to E20. The experiments were conducted on animals 8-12 weeks old and with body weight between 250 and 350 g. Results Results showed that prenatal exposure to buprenorphine caused higher mortality than other tested substance groups. Although we observed a significantly lower increase in body weight in all of the opioid-administered dams, the birth weight of the offspring was not altered in all treated groups. Moreover, no obvious behavioral abnormality or body-weight difference was noted during the growing period (8-12 weeks) in all offspring. When the male offspring received morphine injection twice a day for 4 days, the prenatally opioid-exposed rats more quickly developed a tolerance to morphine (as shown by the tail-flick tests), most notably the prenatally buprenorphine-exposed offspring. However, the tolerance development to methadone or buprenorphine was not different in offspring exposed prenatally to methadone or buprenorphine, respectively, when compared with that of the vehicle controlled group. Similar results were also obtained in the female animals. Conclusions Animals prenatally exposed to morphine, methadone, or buprenorphine developed tolerance to morphine faster than their controlled mates. In our animal model, prenatal exposure to buprenorphine also resulted in higher mortality and much less sensitivity to morphine-induced antinociception than prenatal exposure to morphine or methadone. This indicates that buprenorphine in higher doses may not be an ideal maintenance drug for treating pregnant women. This study provides a reference in selecting doses for clinical usage in treating pregnant heroin addicts.
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Affiliation(s)
- Yao-Chang Chiang
- Division of Mental Health & Addiction Medicine, Institute of Population Health Sciences, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli County 35053, Taiwan, ROC
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Berger AC, Whistler JL. How to design an opioid drug that causes reduced tolerance and dependence. Ann Neurol 2010; 67:559-69. [PMID: 20437553 DOI: 10.1002/ana.22002] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Mu opioid receptor (MOR) agonists such as morphine are extremely effective treatments for acute pain. In the setting of chronic pain, however, their long-term utility is limited by the development of tolerance and physical dependence. Drug companies have tried to overcome these problems by simply "dialing up" signal transduction at the receptor, designing more potent and efficacious agonists and more long-lasting formulations. Neither of these strategies has proven to be successful, however, because the net amount of signal transduction, particularly over extended periods of drug use, is a product of much more than the pharmacokinetic properties of potency, efficacy, half-life, and bioavailability, the mainstays of traditional pharmaceutical screening. Both the quantity and quality of signal transduction are influenced by many regulated processes, including receptor desensitization, trafficking, and oligomerization. Importantly, the efficiency with which an agonist first stimulates signal transduction is not necessarily related to the efficiency with which it stimulates these other processes. Here we describe recent findings that suggest MOR agonists with diminished propensity to cause tolerance and dependence can be identified by screening drugs for the ability to induce MOR desensitization, endocytosis, and recycling. We also discuss preliminary evidence that heteromers of the delta opioid receptor and the MOR are pronociceptive, and that drugs that spare such heteromers may also induce reduced tolerance.
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Affiliation(s)
- Amy Chang Berger
- Department of Neurology, University of California, San Francisco, Ernest Gallo Clinic and Research Center, Emeryville, CA, USA
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micro-Opioid receptor endocytosis prevents adaptations in ventral tegmental area GABA transmission induced during naloxone-precipitated morphine withdrawal. J Neurosci 2010; 30:3276-86. [PMID: 20203187 DOI: 10.1523/jneurosci.4634-09.2010] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Chronic morphine drives adaptations in synaptic transmission thought to underlie opiate dependence. Here we examine the role of micro-opioid receptor (MOR) trafficking in one of these adaptations, specifically, changes in GABA transmission in the ventral tegmental area (VTA). To address this question, we used a knock-in mouse, RMOR (for recycling MOR), in which genetic change in the MOR promotes morphine-induced receptor desensitization and endocytosis in GABA interneurons of the VTA. In wild-type mice (postnatal days 23-28) chronic morphine (10 mg/kg, s.c., twice daily for 5 d), induced a cAMP-dependent increase in the probability of GABA release onto VTA dopamine neurons. The increased GABA release frequency correlated with physical dependence on morphine measured by counting somatic signs of morphine withdrawal, such as, tremors, jumps, rears, wet-dog shakes, and grooming behavior precipitated by subcutaneous administration of naloxone (NLX) (2 mg/kg). This adaptation in GABA release was prevented in RMOR mice given the same morphine treatment, implicating MOR trafficking in this morphine-induced change in plasticity. Importantly, treatment with the cAMP activity inhibitor rp-cAMPS [(R)-adenosine, cyclic 3',5'-(hydrogenphosphorothioate) triethylammonium] (50 ng/0.5 microl), directly to the VTA, attenuated somatic withdrawal signs to systemic morphine produced by intra-VTA NLX (500 ng/0.5 microl), directly tying enhanced cAMP-driven GABA release to naloxone-precipitated morphine withdrawal in the VTA.
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Wang YH, Sun JF, Tao YM, Xu XJ, Chi ZQ, Liu JG. Paradoxical relationship between RAVE (relative activity versus endocytosis) values of several opioid receptor agonists and their liability to cause dependence. Acta Pharmacol Sin 2010; 31:393-8. [PMID: 20228826 DOI: 10.1038/aps.2010.19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIM To examine the relationship between the RAVE (relative activity versus endocytosis) values of opiate agonists and their dependence liability by studying several potent analgesics with special profiles in the development of physical and psychological dependence. METHODS The effects of (-)-cis-(3R,4S,2'R) ohmefentanyl (F9202), (+)-cis-(3R,4S,2'S) ohmefentanyl (F9204), dihydroetorphine (DHE) and morphine on [(35)S]GTP gamma S binding, forskolin-stimulated cAMP accumulation, and receptor internalization were studied in CHO cells stably expressing HA-tagged mu-opioid receptors (CHO-HA-MOR). cAMP overshoot in response to the withdrawal of these compound treatments was also tested. RESULTS All four agonists exhibited the same rank order of activity in stimulation of [(35)S]GTP gamma S binding, inhibition of adenylyl cyclase (AC) and induction of receptor internalization: DHE>F9204>F9202>morphine. Based on these findings and the previous in vivo analgesic data obtained from our and other laboratories, the RAVE values of the four agonists were calculated. The rank order of RAVE values was morphine>F9202>F9204>DHE. For the induction of cAMP overshoot, the rank order was F9202>or=morphine>F9204>or=DHE. CONCLUSION Taken in combination with previous findings of these compounds' liability to develop dependence, the present study suggests that the agonist with the highest RAVE value seems to have a relatively greater liability to develop psychological dependence relative to the agonist with the lowest RAVE value. However, the RAVE values of these agonists are not correlated with their probability of developing physical dependence or inducing cAMP overshoot, a cellular hallmark of dependence.
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Rankovic M, Jacob L, Rankovic V, Brandenburg LO, Schröder H, Höllt V, Koch T. ADP-ribosylation factor 6 regulates mu-opioid receptor trafficking and signaling via activation of phospholipase D2. Cell Signal 2009; 21:1784-93. [DOI: 10.1016/j.cellsig.2009.07.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 07/08/2009] [Accepted: 07/29/2009] [Indexed: 10/20/2022]
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He L, Kim JA, Whistler JL. Biomarkers of morphine tolerance and dependence are prevented by morphine-induced endocytosis of a mutant mu-opioid receptor. FASEB J 2009; 23:4327-34. [PMID: 19679639 DOI: 10.1096/fj.09-133223] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Growing evidence shows that trafficking of the mu-opioid receptor (MOR) is a critical process in functional recovery from desensitization following activation and plays important roles in morphine tolerance and dependence largely because of the failure of morphine to promote such trafficking. However, morphine tolerance and dependence are believed to be mediated by multiple mechanisms, including well-documented biochemical changes in cAMP activity, N-methyl-D-aspartate receptors (NMDARs), glucocorticoid receptors (GRs), and c-fos. Here, we assess the consequences of promoting morphine-induced endocytosis on these biochemical changes utilizing a knock-in mouse model, RMOR, in which MORs undergo morphine-induced endocytosis. Chronic morphine treatment of wild-type (WT) mice promoted superactivation of adenylyl cyclase, alterations in NMDARs, and up-regulation of GR and c-fos in distinct brain regions. Notably, none of these biochemical changes occurred in the RMOR-knock-in mice. Together, these data demonstrate that morphine tolerance and dependence are mediated by multiple biochemical mechanisms and that MOR endocytosis plays a critical role in each of these mechanisms.
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Affiliation(s)
- Li He
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California-San Francisco, Emeryville, CA 94608, USA
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Abstract
Buprenorphine is a weak partial agonist at mu-opioid receptors that is used for treatment of pain and addiction. Intracellular and whole-cell recordings were made from locus ceruleus neurons in rat brain slices to characterize the actions of buprenorphine. Acute application of buprenorphine caused a hyperpolarization that was prevented by previous treatment of slices with the irreversible opioid antagonist beta-chlornaltrexamine (beta-CNA) but was not reversed by a saturating concentration of naloxone. As expected for a partial agonist, subsaturating concentrations of buprenorphine decreased the [Met](5)enkephalin (ME)-induced hyperpolarization or outward current. When the ME-induced current was decreased below a critical value, desensitization and internalization of mu-opioid receptors was eliminated. The inhibition of desensitization by buprenorphine was not the result of previous desensitization, slow dissociation from the receptor, or elimination of receptor reserve. Treatment of slices with subsaturating concentrations of etorphine, methadone, oxymorphone, or beta-CNA also reduced the current induced by ME but did not block ME-induced desensitization. Treatment of animals with buprenorphine for 1 week resulted in the inhibition of the current induced by ME and a block of desensitization that was not different from the acute application of buprenorphine to brain slices. These observations show the unique characteristics of buprenorphine and further demonstrate the range of agonist-selective actions that are possible through G-protein-coupled receptors.
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Achat-Mendes C, Valdez GR, Platt DM, Rowlett JK, Spealman RD. Intravenous self-administration of etonitazene alone and combined with cocaine in rhesus monkeys: comparison with heroin and antagonism by naltrexone and naloxonazine. Psychopharmacology (Berl) 2009; 204:489-98. [PMID: 19225763 PMCID: PMC2682624 DOI: 10.1007/s00213-009-1480-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Accepted: 01/24/2009] [Indexed: 11/27/2022]
Abstract
RATIONALE In humans, micro opioid-cocaine combinations (speedballs) have been reported to heighten pleasurable effects and result in greater abuse potential compared to either drug individually. Emerging evidence in animals suggests that the ability of mu opioids to enhance the reinforcing effects of cocaine might be independent of their mu intrinsic efficacy even though mu agonist efficacy appears to be a determinant in the reinforcing effects of micro opioids themselves. OBJECTIVES This study examined the relationship between agonist efficacy, self-administration, and the enhancement of cocaine self-administration using the high-efficacy mu agonist etonitazene. MATERIALS AND METHODS Rhesus monkeys self-administered cocaine, heroin, etonitazene, and opioid-cocaine combinations under a progressive-ratio schedule of intravenous drug injection. RESULTS Unlike cocaine and heroin, etonitazene did not maintain consistent self-administration at any dose tested (0.001-1.0 microg/kg/injection). However, combining etonitazene (0.1-1.0 microg/kg/injection) with cocaine (0.01 and 0.03 mg/kg/injection) enhanced cocaine self-administration, and this enhancement was attenuated by naltrexone. These effects are similar to those obtained by combining non-reinforcing doses of heroin and cocaine. Antagonism of etonitazene-cocaine and heroin-cocaine self-administration by naloxonazine was short lasting and was not maintained after 24 h (when naloxonazine's purported micro(1) subtype antagonist effects are thought to predominate). CONCLUSIONS The results suggest that high micro agonist efficacy does not guarantee consistent drug self-administration and that the ability of mu agonists to enhance cocaine self-administration does not depend exclusively on reinforcing efficacy. Moreover, the results do not support a major role for micro(1) receptor mechanisms in either etonitazene- or heroin-induced enhancement of cocaine self-administration.
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Affiliation(s)
- Cindy Achat-Mendes
- Division of Neuroscience, New England Primate Research Center, Harvard Medical School, Southborough, MA 01772, USA.
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41
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Gupta K, Vats ID, Gupta YK, Saleem K, Pasha S. Lack of tolerance and morphine-induced cross-tolerance to the analgesia of chimeric peptide of Met-enkephalin and FMRFa. Peptides 2008; 29:2266-75. [PMID: 18930087 DOI: 10.1016/j.peptides.2008.09.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Revised: 09/18/2008] [Accepted: 09/18/2008] [Indexed: 12/20/2022]
Abstract
Chimeric peptide of Met-enkephalin and FMRFa (YGGFMKKKFMRFa-YFa), a kappa-opioid receptor specific peptide, did not induce tolerance and cross-tolerance effects to its analgesic action on day 5 after pretreatment with either YFa or morphine for 4 days. However, pretreatment with YFa for 4 days led to the development of cross-tolerance to the analgesic effects of morphine and also 4 days of pretreatment of morphine resulted in the expression of tolerance to its own analgesic effects. Similar expression of tolerance and cross-tolerance were also observed when YFa was compared with the kappa receptor agonist peptide dynorphin A(1-13) [DynA(1-13)]. Cross-tolerance effects between YFa and DynA(1-13) analgesia were also not observed on day 5. Interestingly, when YFa and DynA(1-13) were tested for their analgesic effects for 5 days, reduction in analgesia on day 3 was observed in case of DynA(1-13) whereas YFa maintained its analgesia for 5 days. Thus, chimeric peptide YFa may serve as a useful probe to understand pain modulation and expression of tolerance and cross-tolerance behavior with other opioids.
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Affiliation(s)
- Kshitij Gupta
- Peptide Synthesis Laboratory, Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
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Kim JA, Bartlett S, He L, Nielsen CK, Chang AM, Kharazia V, Waldhoer M, Ou CJ, Taylor S, Ferwerda M, Cado D, Whistler JL. Morphine-induced receptor endocytosis in a novel knockin mouse reduces tolerance and dependence. Curr Biol 2008; 18:129-35. [PMID: 18207746 DOI: 10.1016/j.cub.2007.12.057] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 12/19/2007] [Accepted: 12/20/2007] [Indexed: 11/26/2022]
Abstract
Opioid drugs, such as morphine, are among the most effective analgesics available. However, their utility for the treatment of chronic pain is limited by side effects including tolerance and dependence. Morphine acts primarily through the mu-opioid receptor (MOP-R) , which is also a target of endogenous opioids. However, unlike endogenous ligands, morphine fails to promote substantial receptor endocytosis both in vitro, and in vivo. Receptor endocytosis serves at least two important functions in signal transduction. First, desensitization and endocytosis act as an "off" switch by uncoupling receptors from G protein. Second, endocytosis functions as an "on" switch, resensitizing receptors by recycling them to the plasma membrane. Thus, both the off and on function of the MOP-R are altered in response to morphine compared to endogenous ligands. To examine whether the low degree of endocytosis induced by morphine contributes to tolerance and dependence, we generated a knockin mouse that expresses a mutant MOP-R that undergoes morphine-induced endocytosis. Morphine remains an excellent antinociceptive agent in these mice. Importantly, these mice display substantially reduced antinociceptive tolerance and physical dependence. These data suggest that opioid drugs with a pharmacological profile similar to morphine but the ability to promote endocytosis could provide analgesia while having a reduced liability for promoting tolerance and dependence.
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Affiliation(s)
- Joseph A Kim
- Ernest Gallo Clinic & Research Center, 5858 Horton St., Suite 200, Emeryville, California 94608, USA
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Listos J, Talarek S, Fidecka S. Adenosine receptor agonists attenuate the development of diazepam withdrawal-induced sensitization in mice. Eur J Pharmacol 2008; 588:72-7. [PMID: 18466897 DOI: 10.1016/j.ejphar.2008.04.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 03/19/2008] [Accepted: 04/02/2008] [Indexed: 10/22/2022]
Abstract
In the present study, the effects of adenosine agonists on the development of sensitization to withdrawal signs precipitated after sporadic treatment with diazepam, in mice, were investigated. To obtain the sensitization, the animals were divided into groups: continuously and sporadically treated with diazepam (15.0 mg/kg, s.c.). The adenosine receptor agonists (CPA, CGS 21,680 and NECA) were administered in sporadically diazepam treated mice during two diazepam-free periods. Concomitant administration of pentetrazole (55.0 mg/kg, s.c.) with flumazenil (5.0 mg/kg, i.p.) after the last injection of diazepam or vehicle, induced the withdrawal signs, such as clonic seizures, tonic convulsion and death episodes. The major finding of our experiments is attenuation of withdrawal signs in sensitized mice, inducing by all adenosine agonists. Only higher dose of CPA produced significantly decreased the number of withdrawal incidents, while both used doses of CGS 21,680 and NECA produced more clear effects. These results support the hypothesis that adenosinergic system is involved in the mechanisms of sensitization to the benzodiazepine withdrawal signs, and adenosine A(2A) receptors play more important role in that process.
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Affiliation(s)
- Joanna Listos
- Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, Staszica 4, 20-081 Lublin, Poland.
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Cummins E, Leri F. Unreinforced responding during limited access to heroin self-administration. Pharmacol Biochem Behav 2008; 90:420-7. [PMID: 18479741 DOI: 10.1016/j.pbb.2008.03.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Revised: 03/21/2008] [Accepted: 03/29/2008] [Indexed: 11/29/2022]
Abstract
These studies were designed to explore a peculiar behavior displayed by rats during the acquisition of heroin self-administration (0.05 mg/kg/infusion) on a fixed-ratio 1 schedule of reinforcement in limited access conditions (i.e. 3 h/day). Rats trained under these conditions develop a tendency to emit extra lever presses during the time of heroin infusions (unreinforced responses). We found that a similar behavior develops in animals responding for sucrose pellets, but not for intravenous infusions of cocaine (0.5 mg/kg/infusion, 3 h/day). In sucrose trained rats, unreinforced responses emitted during the delivery of sucrose pellets was enhanced by food deprivation. In heroin trained rats, development of unreinforced responding was accompanied by an increase in responding for heroin on a progressive ratio schedule, and by a reduction of the depressant action of heroin (3 mg/kg, SC) on locomotor activity. On the basis of these findings, we concluded that unreinforced responding during heroin self-administration reflects a change in the motivation to obtain the drug, as well as a reduced sensitivity the motor impairing action of heroin. This suggests that acquisition of heroin self-administration is regulated by a balance between drug effects that promote and limit heroin intake.
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Affiliation(s)
- Erin Cummins
- Department of Psychology, University of Guelph, Guelph (ON), Canada N1G 2W1
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45
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Virk MS, Williams JT. Agonist-specific regulation of mu-opioid receptor desensitization and recovery from desensitization. Mol Pharmacol 2008; 73:1301-8. [PMID: 18198283 DOI: 10.1124/mol.107.042952] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Agonist-selective actions of opioids on the desensitization of mu-opioid receptors (MORs) have been well characterized, but few if any studies have examined agonist-dependent recovery from desensitization. The outward potassium current induced by several opioids was studied using whole-cell voltage-clamp recordings in locus ceruleus neurons. A brief application of the irreversible opioid antagonist beta-chlornaltrexamine (beta-CNA) was applied immediately after treatment of slices with saturating concentrations of opioid agonists. This approach permitted the measurement of desensitization and recovery from desensitization using multiple opioid agonists, including [Met](5)enkephalin (ME), [d-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO), etorphine, fentanyl, methadone, morphine, morphine-6-glucuronide, oxycodone, and oxymorphone. The results indicate that desensitization protects receptors from irreversible antagonism with beta-CNA. The amount of desensitization was measured as the decrease in current during a 10-min application of a saturating agonist concentration and was a good predictor of the extent of receptor protection from irreversible inactivation with beta-CNA. After desensitization with ME or DAMGO and treatment with beta-CNA, there was an initial profound inhibition of MOR-induced current that recovered significantly after 45 min. There was, however, no recovery of MOR-mediated current with time after treatment with agonists that did not cause desensitization, such as oxycodone. These results demonstrate that desensitization prevents irreversible inactivation of receptors by beta-CNA.
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Affiliation(s)
- Michael S Virk
- Vollum Institute, L474, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, OR 97239.
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Affiliation(s)
- Marie Fallon
- St Columba's Hospice Chair of Palliative Medicine University of Edinburgh and Edinburgh Cancer Research Centre Western General Hospital Edinburgh
| | - Lesley Colvin
- Department of Anaesthesia and Pain Medicine University of Edinburgh and Western General Hospital Edinburgh
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Abstract
This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 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 neurological 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 and thermoregulation (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, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367, United States.
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Role of receptor internalization in opioid tolerance and dependence. Pharmacol Ther 2007; 117:199-206. [PMID: 18076994 DOI: 10.1016/j.pharmthera.2007.10.003] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Accepted: 10/25/2007] [Indexed: 12/01/2022]
Abstract
Agonist-induced mu-opioid receptor (MOPr) internalization has long been suggested to contribute directly to functional receptor desensitization and opioid tolerance. In contrast, recent evidence suggests that opioid receptor internalization could in fact reduce opioid tolerance in vivo, but the mechanisms that are responsible for the internalization-mediated protection against opioid tolerance are controversely discussed. One prevailing hypothesis is, that receptor internalization leads to decreased receptor signaling and therefore to reduced associated compensatory changes in downstream signaling systems that are involved in the development of opioid tolerance. However, numerous studies have demonstrated that desensitized and internalized mu-opioid receptors are rapidly recycled to the cell surface in a reactivated state, thus counteracting receptor desensitization and opioid tolerance. Further studies revealed agonist-selective differences in the ability to induce opioid receptor internalization. Recently it has been demonstrated that the endocytotic efficacies of opioids are negatively correlated to the induced opioid tolerance. Thus, clearer understanding of the role of opioid receptor trafficking in the regulation of opioid tolerance and dependence will help in the treatment of patients suffering from chronic pain or drug dependence.
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Morphine-induced analgesic tolerance, locomotor sensitization and physical dependence do not require modification of mu opioid receptor, cdk5 and adenylate cyclase activity. Neuropharmacology 2007; 54:475-86. [PMID: 18082850 DOI: 10.1016/j.neuropharm.2007.10.015] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 10/22/2007] [Accepted: 10/23/2007] [Indexed: 11/21/2022]
Abstract
Acute morphine administration produces analgesia and reward, but prolonged use may lead to analgesic tolerance in patients chronically treated for pain and to compulsive intake in opioid addicts. Moreover, long-term exposure may induce physical dependence, manifested as somatic withdrawal symptoms in the absence of the drug. We set up three behavioral paradigms to model these adaptations in mice, using distinct regimens of repeated morphine injections to induce either analgesic tolerance, locomotor sensitization or physical dependence. Interestingly, mice tolerant to analgesia were not sensitized to hyperlocomotion, whereas sensitized mice displayed some analgesic tolerance. We then examined candidate molecular modifications that could underlie the development of each behavioral adaptation. First, analgesic tolerance was not accompanied by mu opioid receptor desensitization in the periaqueductal gray. Second, cdk5 and p35 protein levels were unchanged in caudate-putamen, nucleus accumbens and prefrontal cortex of mice displaying locomotor sensitization. Finally, naloxone-precipitated morphine withdrawal did not enhance basal or forskolin-stimulated adenylate cyclase activity in nucleus accumbens, prefrontal cortex, amygdala, bed nucleus of stria terminalis or periaqueductal gray. Therefore, the expression of behavioral adaptations to chronic morphine treatment was not associated with the regulation of micro opioid receptor, cdk5 or adenylate cyclase activity in relevant brain areas. Although we cannot exclude that these modifications were not detected under our experimental conditions, another hypothesis is that alternative molecular mechanisms, yet to be discovered, underlie analgesic tolerance, locomotor sensitization and physical dependence induced by chronic morphine administration.
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Martini L, Whistler JL. The role of mu opioid receptor desensitization and endocytosis in morphine tolerance and dependence. Curr Opin Neurobiol 2007; 17:556-64. [DOI: 10.1016/j.conb.2007.10.004] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Revised: 10/10/2007] [Accepted: 10/16/2007] [Indexed: 12/12/2022]
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