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Lambert DG. Opioids and opioid receptors; understanding pharmacological mechanisms as a key to therapeutic advances and mitigation of the misuse crisis. BJA OPEN 2023; 6:100141. [PMID: 37588171 PMCID: PMC10430815 DOI: 10.1016/j.bjao.2023.100141] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 04/05/2023] [Accepted: 04/12/2023] [Indexed: 08/18/2023]
Abstract
Opioids are a mainstay in acute pain management and produce their effects and side effects (e.g., tolerance, opioid-use disorder and immune suppression) by interaction with opioid receptors. I will discuss opioid pharmacology in some controversial areas of enquiry of anaesthetic relevance. The main opioid target is the µ (mu,MOP) receptor but other members of the opioid receptor family, δ (delta; DOP) and κ (kappa; KOP) opioid receptors also produce analgesic actions. These are naloxone-sensitive. There is important clinical development relating to the Nociceptin/Orphanin FQ (NOP) receptor, an opioid receptor that is not naloxone-sensitive. Better understanding of the drivers for opioid effects and side effects may facilitate separation of side effects and production of safer drugs. Opioids bind to the receptor orthosteric site to produce their effects and can engage monomer or homo-, heterodimer receptors. Some ligands can drive one intracellular pathway over another. This is the basis of biased agonism (or functional selectivity). Opioid actions at the orthosteric site can be modulated allosterically and positive allosteric modulators that enhance opioid action are in development. As well as targeting ligand-receptor interaction and transduction, modulating receptor expression and hence function is also tractable. There is evidence for epigenetic associations with different types of pain and also substance misuse. As long as the opioid narrative is defined by the 'opioid crisis' the drive to remove them could gather pace. This will deny use where they are effective, and access to morphine for pain relief in low income countries.
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5-HT 2A receptor- and M 1 muscarinic acetylcholine receptor-mediated activation of Gα q/11 in postmortem dorsolateral prefrontal cortex of opiate addicts. Pharmacol Rep 2021; 73:1155-1163. [PMID: 33835465 DOI: 10.1007/s43440-021-00248-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 03/05/2021] [Accepted: 03/11/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND Chronic exposure to opiates causes the development of tolerance and physical dependence as well as persistent brain neuroplasticity. Despite a wealth of postmortem human studies for opiate addicts, little direct information regarding the functional status of serotonergic and cholinergic receptor-mediated signaling pathways in the human brain of opiate addicts is yet available. METHODS Functional activation of Gαq/11 proteins coupled to 5-HT2A and M1 type muscarinic acetylcholine receptor (mAChR) was assessed by using the method named [35S]GTPγS binding/immunoprecipitation in frontal cortical membrane preparations from postmortem human brains obtained from opiate addicts and matched controls. RESULTS Concentration-response curves for 5-HT and carbachol in individual subjects were analyzed according to a nonlinear regression model, which generated the values of maximum percent increase (%Emax), negative logarithm of the half-maximal effect (pEC50) and slope factor. As for 5-HT2A receptor-mediated Gαq/11 activation, the %Emax values were reduced significantly and the pEC50 values were decreased significantly in opiate addicts as compared to the control group. Regarding carbachol-induced Gαq/11 activation, no significant difference in %Emax or pEC50 values was detected between the both groups, whereas the slope factor was increased significantly in opiate addicts as compared to the control group. CONCLUSION Our data demonstrate that the signaling pathways mediated by Gαq/11 proteins coupled with 5-HT2A receptors and M1 mAChRs in prefrontal cortex are functionally altered in opiate addicts in comparison with control subjects. These alterations may underpin some aspects of addictive behavior to opiate as well as neuropsychological consequences or comorbid mental disorders associated with opioid use.
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Karavidha KK, Burmeister M, Greenwald MK. β-Arrestin 2 (ARRB2) Polymorphism is Associated With Adverse Consequences of Chronic Heroin Use. Am J Addict 2021; 30:351-357. [PMID: 33783060 DOI: 10.1111/ajad.13150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 12/10/2020] [Accepted: 12/28/2020] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND AND OBJECTIVES β-arrestin 2 is an intracellular protein recruited during the activation of G-protein-coupled receptors. In preclinical studies, β-arrestin 2 has been implicated in µ-opioid receptor desensitization and internalization and the development of opioid tolerance and dependence. The present study investigated relationships between variants in the gene encoding β-arrestin 2 (ARRB2) and clinically relevant phenotypes among individuals with opioid use disorder (OUD). We hypothesized that ARRB2 variants would be associated with the negative effects of long-term heroin use. METHODS Chronic heroin users (N = 201; n = 103 African American; n = 98 Caucasian) were genotyped for ARRB2 r1045280 (synonymous, also affecting binding motif of transcription factor GTF2IRD1), rs2036657 (3'UTR) and rs3786047 (intron) and assessed for the past-month frequency of use, injection use, and lifetime duration of heroin use, number of heroin quit-attempts, and heroin use-related consequences. RESULTS Lifetime heroin-use consequences (especially occupational and health-related) were significantly lower for African American ARRB2 r1045280 C-allele carriers compared with the TT genotype. There was no significant genotype difference in the Caucasian group. ARRB2 rs2036657 was in strong linkage disequilibrium with rs1045280. DISCUSSION AND CONCLUSIONS These results, consistent with extant data, illustrate a role for ancestry-dependent allelic variation in ARRB2 r1045280 on heroin-use consequences. The ARRB2 r1045280 C-allele played a protective role in African-descent participants. SCIENTIFIC SIGNIFICANCE These first-in-human findings, which should be replicated, provide support for mechanistic investigations of ARRB2 and related intracellular signaling molecules in OUD etiology, treatment, and relapse prevention. (Am J Addict 2021;00:00-00).
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Affiliation(s)
- Klevis K Karavidha
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, Michigan
| | - Margit Burmeister
- Department of Computational Medicine & Bioinformatics, Michigan Neuroscience Institute, University of Michigan, Ann Arbor, Michigan
| | - Mark K Greenwald
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, Michigan.,Department of Pharmacy Practice, Wayne State University, Detroit, Michigan
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Blackwood CA, Cadet JL. The molecular neurobiology and neuropathology of opioid use disorder. CURRENT RESEARCH IN NEUROBIOLOGY 2021; 2. [PMID: 35548327 PMCID: PMC9090195 DOI: 10.1016/j.crneur.2021.100023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The number of people diagnosed with opioid use disorder has skyrocketed as a consequence of the opioid epidemic and the increased prescribing of opioid drugs for chronic pain relief. Opioid use disorder is characterized by loss of control of drug taking, continued drug use in the presence of adverse consequences, and repeated relapses to drug taking even after long periods of abstinence. Patients who suffer from opioid use disorder often present with cognitive deficits that are potentially secondary to structural brain abnormalities that vary according to the chemical composition of the abused opioid. This review details the neurobiological effects of oxycodone, morphine, heroin, methadone, and fentanyl on brain neurocircuitries by presenting the acute and chronic effects of these drugs on the human brain. In addition, we review results of neuroimaging in opioid use disorder patients and/or histological studies from brains of patients who had expired after acute intoxication following long-term use of these drugs. Moreover, we include relevant discussions of the neurobiological mechanisms involved in promoting abnormalities in the brains of opioid-exposed patients. Finally, we discuss how novel strategies could be used to provide pharmacological treatment against opioid use disorder. Brain abnormalities caused by opioid intoxication. Intoxication of opioids leads to defects in brain neurocircuitries. Insight into the molecular mechanisms associated with craving in heroin addicts.
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Affiliation(s)
| | - Jean Lud Cadet
- Corresponding author.Molecular Neuropsychiatry Research Branch NIH/NIDA Intramural Research Program 251 Bayview Boulevard Baltimore, MD, USA
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5
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Blackwood CA, McCoy MT, Ladenheim B, Cadet JL. Escalated Oxycodone Self-Administration and Punishment: Differential Expression of Opioid Receptors and Immediate Early Genes in the Rat Dorsal Striatum and Prefrontal Cortex. Front Neurosci 2020; 13:1392. [PMID: 31998063 PMCID: PMC6962106 DOI: 10.3389/fnins.2019.01392] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 12/10/2019] [Indexed: 12/22/2022] Open
Abstract
Opioid use disorder (OUD) is characterized by compulsive drug taking despite adverse life consequences. Here, we sought to identify neurobiological consequences associated with the behavioral effects of contingent footshocks administered after escalation of oxycodone self-administration. To reach these goals, Sprague-Dawley rats were trained to self-administer oxycodone for 4 weeks and were then exposed to contingent electric footshocks. This paradigm helped to dichotomize rats into two distinct behavioral phenotypes: (1) those that reduce lever pressing (shock-sensitive) and (2) others that continue lever pressing (shock-resistant) for oxycodone during contingent punishment. The rats were euthanized at 2-h after the last oxycodone plus footshock session. The dorsal striata and prefrontal cortices were dissected for use in western blot and RT-qPCR analyses. All oxycodone self-administration rats showed significant decreased expression of Mu and Kappa opioid receptor proteins only in the dorsal striatum. However, expression of Delta opioid receptor protein was decreased in both brain regions. RT-qPCR analyses documented significant decreases in the expression of c-fos, fosB, fra2, junB, egr1, and egr2 mRNAs in the dorsal striatum (but not in PFC) of the shock-sensitive rats. In the PFC, junD expression was reduced in both phenotypes. However, egr3 mRNA expression was increased in the PFC of only shock-resistant rats. These results reveal that, similar to psychostimulants and alcohol, footshocks can dichotomize rats that escalated their intake of oxycodone into two distinct behavioral phenotypes. These animals also show significant differences in the mRNA expression of immediate early genes, mainly, in the dorsal striatum. The increases in PFC egr3 expression in the shock-resistant rats suggest that Egr3 might be involved in the persistence of oxycodone-associated memory under aversive conditions. This punishment-driven model may help to identify neurobiological substrates of persistent oxycodone taking and abstinence in the presence of adverse consequences.
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Affiliation(s)
- Christopher A Blackwood
- Molecular Neuropsychiatry Research Branch, NIH/NIDA Intramural Research Program, Baltimore, MD, United States
| | - Michael T McCoy
- Molecular Neuropsychiatry Research Branch, NIH/NIDA Intramural Research Program, Baltimore, MD, United States
| | - Bruce Ladenheim
- Molecular Neuropsychiatry Research Branch, NIH/NIDA Intramural Research Program, Baltimore, MD, United States
| | - Jean Lud Cadet
- Molecular Neuropsychiatry Research Branch, NIH/NIDA Intramural Research Program, Baltimore, MD, United States
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Taqi MM, Faisal M, Zaman H. OPRM1 A118G Polymorphisms and Its Role in Opioid Addiction: Implication on Severity and Treatment Approaches. PHARMACOGENOMICS & PERSONALIZED MEDICINE 2019; 12:361-368. [PMID: 31819591 PMCID: PMC6885558 DOI: 10.2147/pgpm.s198654] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 11/13/2019] [Indexed: 12/14/2022]
Abstract
The epidemic of opioid addiction is shaping up as the most serious clinical issues of current times. Opioids have the greatest propensity to develop addiction after first exposure. Molecular, genetic variations, epigenetic alterations, and environmental factors are also implicated in the development of opioid addiction. Genetic and epigenetic variations in candidate genes have been identified for their associations with opioid addiction. OPRM1 nonsynonymous single nucleotide polymorphism rs1799971 (A118G) is the most prominent candidate due to its significant association with onset and treatment of opioid addiction. Marked inter-individual variability in response to available maintenance pharmacotherapies is the common feature observed in individuals with opioid addiction. Several therapies are only effective among subgroups of opioid individuals which indicate that ethnic, environmental factors and genetic polymorphism including rs1799971 may be responsible for the response to treatment. Pharmacogenetics has the potential to enhance our understanding around the underlying genetic, epigenetic and molecular mechanisms responsible for the heterogeneous response of maintenance pharmacotherapies in opioid addiction. A more detailed understanding of molecular, epigenetic and genetic variants especially the implication of OPRM1 A118G polymorphism in an individual may serve as the way forward to address the opioid epidemic. Personalized medicine, which involves developing targeted pharmacotherapies in accordance with individual genetic and epigenetic makeup, are required to develop safe and effective treatments for opioid addiction.
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Affiliation(s)
- Malik Mumtaz Taqi
- Division of Mental Health and Addiction, University of Oslo, Oslo, Norway
| | - Muhammad Faisal
- Faculty of Health Studies, University of Bradford, Bradford, UK.,Bradford Institute for Health Research, Bradford Teaching Hospitals NHS Foundation Trust, Bradford, UK
| | - Hadar Zaman
- School of Pharmacy and Medical Sciences, Faculty of Life Sciences, University of Bradford, Bradford, UK
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Luessen DJ, Sun H, McGinnis MM, Hagstrom M, Marrs G, McCool BA, Chen R. Acute ethanol exposure reduces serotonin receptor 1A internalization by increasing ubiquitination and degradation of β-arrestin2. J Biol Chem 2019; 294:14068-14080. [PMID: 31366729 DOI: 10.1074/jbc.ra118.006583] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 07/23/2019] [Indexed: 11/06/2022] Open
Abstract
Acute alcohol exposure alters the trafficking and function of many G-protein-coupled receptors (GPCRs) that are associated with aberrant behavioral responses to alcohol. However, the molecular mechanisms underlying alcohol-induced changes in GPCR function remain unclear. β-Arrestin is a key player involved in the regulation of GPCR internalization and thus controls the magnitude and duration of GPCR signaling. Although β-arrestin levels are influenced by various drugs of abuse, the effect of alcohol exposure on β-arrestin expression and β-arrestin-mediated GPCR trafficking is poorly understood. Here, we found that acute ethanol exposure increases β-arrestin2 degradation via its increased ubiquitination in neuroblastoma-2a (N2A) cells and rat prefrontal cortex (PFC). β-Arrestin2 ubiquitination was likely mediated by the E3 ligase MDM2 homolog (MDM2), indicated by an increased coupling between β-arrestin2 and MDM2 in response to acute ethanol exposure in both N2A cells and rat PFC homogenates. Importantly, ethanol-induced β-arrestin2 reduction was reversed by siRNA-mediated MDM2 knockdown or proteasome inhibition in N2A cells, suggesting β-arrestin2 degradation is mediated by MDM2 through the proteasomal pathway. Using serotonin 5-HT1A receptors (5-HT1ARs) as a model receptor system, we found that ethanol dose-dependently inhibits 5-HT1AR internalization and that MDM2 knockdown reverses this effect. Moreover, ethanol both reduced β-arrestin2 levels and delayed agonist-induced β-arrestin2 recruitment to the membrane. We conclude that β-arrestin2 dysregulation by ethanol impairs 5-HT1AR trafficking. Our findings reveal a critical molecular mechanism underlying ethanol-induced alterations in GPCR internalization and implicate β-arrestin as a potential player mediating behavioral responses to acute alcohol exposure.
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Affiliation(s)
- Deborah J Luessen
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157
| | - Haiguo Sun
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157
| | - Molly M McGinnis
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157
| | - Michael Hagstrom
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157
| | - Glen Marrs
- Center for Molecular Signaling, Department of Biology, Wake Forest University, Winston Salem, North Carolina 27106
| | - Brian A McCool
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157
| | - Rong Chen
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157 .,Center for Molecular Signaling, Department of Biology, Wake Forest University, Winston Salem, North Carolina 27106.,Center for the Neurobiology of Addiction Treatment, Wake Forest School of Medicine, Winston Salem, North Carolina 27157
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8
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D,L-Methadone does not improve radio- and chemotherapy in glioblastoma in vitro. Cancer Chemother Pharmacol 2019; 83:1017-1024. [PMID: 30888463 DOI: 10.1007/s00280-019-03816-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 03/13/2019] [Indexed: 12/30/2022]
Abstract
PURPOSE Glioblastoma (GBM) is the most common malignant tumor of the central nervous system. Median survival of glioblastoma patients under standard therapy including radiotherapy and chemotherapy using temozolomide (TMZ) is 14.6 months. As cell culture experiments combining D,L-methadone with doxorubicin demonstrated an increased reduction of cell viability of glioblastoma cells, the opioid has been discussed as a drug for the treatment of GBM. Despite lack of clinical and experimental evidence that D,L-methadone in combination with standard therapy will be beneficial, an increasing number of tumor patients medicating themselves with D,L-methadone present to the hospitals in Germany. METHODS As a first step towards understanding whether D,L-methadone may increase the efficacy of standard therapy, we used a cell culture model of primary GBM and fibroblast cell cultures derived from GBM patients. The cultures were treated with different concentrations of D,L-methadone in combination with X-irradiation, TMZ or both. Cell viability was determined by measuring ATP in cell lysates and dehydrogenase activity in living cells. RESULTS When only treated with D,L-methadone, 1 µM of the opioid was sufficient to reduce viability of fibroblasts, whereas 10 µM was needed to significantly reduce glioblastoma cell viability. In addition, D,L-methadone did not improve the anti-neoplastic effects of X-irradiation, temozolomide or both. CONCLUSIONS As D,L-methadone reduces glioblastoma cell viability only when concentrations are used that had been reported to be toxic to patients and as there were no interactions observable combining it with standard therapy, a recommendation for the use of D,L-methadone in glioblastoma therapy cannot be given.
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Abstract
The opioid epidemic is at the epicenter of the drug crisis, resulting in an inconceivable number of overdose deaths and exorbitant associated medical costs that have crippled many communities across the socioeconomic spectrum in the United States. Classic medications for the treatment of opioid use disorder predominantly target the opioid system and thus have been underutilized, in part due to their own potential for abuse and heavy regulatory burden for patients and clinicians. Opioid antagonists are now evolving in their use, not only to prevent acute overdoses but as extended-use treatment options. Strategies that target specific genetic and epigenetic factors, along with novel nonopioid medications, hold promise as future therapeutic interventions for opioid abuse. Success in increasing the treatment options in the clinical toolbox will, hopefully, help to end the historical pattern of recurring opioid epidemics. [AJP at 175: Remembering Our Past As We Envision Our Future Drug Addiction in Relation to Problems of Adolescence Zimmering and colleagues wrote in the midst of an opiate epidemic among young people that "only the human being, or rather certain types of human beings, will return to the enslaving, self-destructive habit." (Am J Psychiatry 1952; 109:272-278 )].
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Affiliation(s)
- Yasmin L. Hurd
- Departments of Psychiatry and Neuroscience, Icahn School of Medicine, Addiction Institute, Mount Sinai Behavioral Health System, New York
| | - Charles P. O’Brien
- Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania
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10
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Marie-Claire C, Jourdaine C, Lépine JP, Bellivier F, Bloch V, Vorspan F. Pharmacoepigenomics of opiates and methadone maintenance treatment: current data and perspectives. Pharmacogenomics 2017; 18:1359-1372. [DOI: 10.2217/pgs-2017-0040] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Current treatments of opioid addiction include primarily maintenance medications such as methadone. Chronic exposure to opiate and/or long-lasting maintenance treatment induce modulations of gene expression in brain and peripheral tissues. There is increasing evidence that epigenetic modifications underlie these modulations. This review summarizes published results on opioid-induced epigenetic changes in animal models and in patients. The epigenetic modifications observed with other drugs of abuse often used by opiate abusers are also outlined. Specific methadone maintenance treatment induced epigenetic modifications at different treatment stages may be combined with the ones resulting from patients’ substance use history. Therefore, research comparing groups of addicts with similar history and substances use disorders but contrasting for well-characterized treatment phenotypes should be encouraged.
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Affiliation(s)
- Cynthia Marie-Claire
- Variabilité de réponse aux psychotropes, INSERMU1144/Faculté de Pharmacie de Paris/Université Paris Descartes/Université ParisDiderot/Université Sorbonne Paris Cité, Paris, France
| | - Clément Jourdaine
- AP-HP, GH Saint-Louis – Lariboisière – F. Widal, Pôle de Psychiatrie et de Médecine Addictologique, 75475 Paris cedex 10, France
| | - Jean-Pierre Lépine
- AP-HP, GH Saint-Louis – Lariboisière – F. Widal, Pôle de Psychiatrie et de Médecine Addictologique, 75475 Paris cedex 10, France
| | - Frank Bellivier
- Variabilité de réponse aux psychotropes, INSERMU1144/Faculté de Pharmacie de Paris/Université Paris Descartes/Université ParisDiderot/Université Sorbonne Paris Cité, Paris, France
- AP-HP, GH Saint-Louis – Lariboisière – F. Widal, Pôle de Psychiatrie et de Médecine Addictologique, 75475 Paris cedex 10, France
| | - Vanessa Bloch
- Variabilité de réponse aux psychotropes, INSERMU1144/Faculté de Pharmacie de Paris/Université Paris Descartes/Université ParisDiderot/Université Sorbonne Paris Cité, Paris, France
| | - Florence Vorspan
- Variabilité de réponse aux psychotropes, INSERMU1144/Faculté de Pharmacie de Paris/Université Paris Descartes/Université ParisDiderot/Université Sorbonne Paris Cité, Paris, France
- AP-HP, GH Saint-Louis – Lariboisière – F. Widal, Pôle de Psychiatrie et de Médecine Addictologique, 75475 Paris cedex 10, France
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Upregulation of IRAS/nischarin (I 1-imidazoline receptor), a regulatory protein of μ-opioid receptor trafficking, in postmortem prefrontal cortex of long-term opiate and mixed opiate/cocaine abusers. Neurochem Int 2017; 108:282-286. [PMID: 28461172 DOI: 10.1016/j.neuint.2017.04.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 04/25/2017] [Accepted: 04/27/2017] [Indexed: 02/06/2023]
Abstract
Imidazoline receptor antisera-selected (IRAS)/nischarin, a putative I1-imidazoline receptor, has recently been shown to regulate μ-opioid receptor (OR) trafficking and resensitisation. To study a possible involvement of this μ-OR regulator in opiate dependence, the present study assessed by Western blot analysis the contents of IRAS/nischarin and μ-OR in total homogenates and subcellular preparations of postmortem human prefrontal cortex (PFC/BA9) of long-term opiate and mixed opiate/cocaine abusers as well as of matched healthy control subjects. In the PFC/BA9 of long-term opiate/cocaine abusers (all subjects together) IRAS/nischarin content was increased (+67%, p < 0.01, n = 11) when compared with matched controls (n = 10). Similar increases were found for the subgroups of opiate (+72%, n = 6) and mixed opiate/cocaine (+61%, n = 5) abusers. IRAS/nischarin immunocontents were also found increased in subcellular membrane preparations (+61%, p < 0.05, n = 10) of PFC/BA9 from opiate addicts. In the same brain samples, the levels of μ-OR were not different to those in control subjects. Based on the increased contents in brains of opiate abusers and the reported function as μ-OR regulator, IRAS/nischarin could represent a new promising target for treatment of opiate use disorder.
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Porter-Stransky KA, Weinshenker D. Arresting the Development of Addiction: The Role of β-Arrestin 2 in Drug Abuse. J Pharmacol Exp Ther 2017; 361:341-348. [PMID: 28302862 DOI: 10.1124/jpet.117.240622] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/15/2017] [Indexed: 01/01/2023] Open
Abstract
The protein β-arrestin (βarr) 2 directly interacts with receptors and signaling pathways that mediate the behavioral effects of drugs of abuse, making it a prime candidate for therapeutic interventions. βarr2 drives desensitization and internalization of G protein-coupled receptors, including dopamine, opioid, and cannabinoid receptors, and it can also trigger G protein-independent intracellular signaling. βarr2 mediates several drug-induced behaviors, but the relationship is complex and dependent on the type of behavior (e.g., psychomotor versus reward), the class of drug (e.g., psychostimulant versus opioid), and the circuit being interrogated (e.g., brain region, cell type, and specific receptor ligand). Here we discuss the current state of research concerning the contribution of βarr2 to the psychomotor and rewarding effects of addictive drugs. Next we identify key knowledge gaps and suggest new tools and approaches needed to further elucidate the neuroanatomical substrates and neurobiological mechanisms to explain how βarr2 modulates behavioral responses to drugs of abuse, as well as its potential as a therapeutic target.
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Affiliation(s)
| | - David Weinshenker
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia
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13
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Johnson EO, Hancock DB, Levy JL, Gaddis NC, Page GP, Glasheen C, Saccone NL, Bierut LJ, Kral AH. KAT2B polymorphism identified for drug abuse in African Americans with regulatory links to drug abuse pathways in human prefrontal cortex. Addict Biol 2016; 21:1217-1232. [PMID: 26202629 PMCID: PMC4724343 DOI: 10.1111/adb.12286] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 05/12/2015] [Accepted: 06/20/2015] [Indexed: 12/21/2022]
Abstract
Drug abuse is a common and heritable set of disorders, but the underlying genetic factors are largely unknown. We conducted genome-wide association studies of drug abuse using 7 million imputed single nucleotide polymorphisms (SNPs) and insertions/deletions in African Americans (AAs; n = 3742) and European Americans (EAs; n = 6845). Cases were drawn from the Urban Health Study of street-recruited people, who injected drugs and reported abusing opioids, cocaine, marijuana, stimulants and/or other drugs 10 or more times in the past 30 days, and were compared with population controls. Independent replication testing was conducted in 755 AAs and 1131 EAs from the Genetic Association Information Network. An intronic SNP (rs9829896) in the K(lysine) acetyltransferase 2B (KAT2B) gene was significantly associated with drug abuse in AAs (P = 4.63 × 10-8 ) and independently replicated in AAs (P = 0.0019). The rs9829896-C allele (frequency = 12%) had odds ratios of 0.68 and 0.53 across the AA cohorts: meta-analysis P = 3.93 × 10-10 . Rs9829896-C was not associated with drug abuse across the EA cohorts: frequency = 36% and meta-analysis P = 0.12. Using dorsolateral prefrontal cortex data from the BrainCloud cohort, we found that rs9829896-C was associated with reduced KAT2B expression in AAs (n = 113, P = 0.050) but not EAs (n = 110, P = 0.39). KAT2B encodes a transcriptional regulator in the cyclic adenosine monophosphate and dopamine signaling pathways, and rs9829896-C was associated with expression of genes in these pathways: reduced CREBBP expression (P = 0.011) and increased OPRM1 expression (P = 0.016), both in AAs only. Our study identified the KAT2B SNP rs9829896 as having novel and biologically plausible associations with drug abuse and gene expression in AAs but not EAs, suggesting ancestry-specific effects.
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Affiliation(s)
- Eric O Johnson
- Fellow Program and Behavioral Health and Criminal Justice Division, RTI International, Research Triangle Park, NC, USA.
| | - Dana B Hancock
- Behavioral and Urban Health Program, Behavioral Health and Criminal Justice Division, RTI International, Research Triangle Park, NC, USA
| | - Joshua L Levy
- Research Computing Division, RTI International, Research Triangle Park, NC, USA
| | - Nathan C Gaddis
- Research Computing Division, RTI International, Research Triangle Park, NC, USA
| | - Grier P Page
- Fellow Program, Center for Genomics in Public Health and Medicine, and Genomics, Statistical Genetics, and Environmental Research Program, RTI International, Atlanta, GA, USA
| | - Cristie Glasheen
- Behavioral and Urban Health Program, Behavioral Health and Criminal Justice Division, RTI International, Research Triangle Park, NC, USA
| | - Nancy L Saccone
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Laura J Bierut
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Alex H Kral
- Behavioral and Urban Health Program, Behavioral Health and Criminal Justice Division, RTI International, San Francisco, CA, USA
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14
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Wang Y, Wang H, Li W, Zhu J, Gold MS, Zhang D, Wang L, Li Y, Yan X, Cheng J, Li Q, Wang W. Reduced responses to heroin-cue-induced craving in the dorsal striatum: effects of long-term methadone maintenance treatment. Neurosci Lett 2014; 581:120-4. [PMID: 25157798 DOI: 10.1016/j.neulet.2014.08.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 07/29/2014] [Accepted: 08/14/2014] [Indexed: 10/24/2022]
Abstract
Methadone maintenance treatment (MMT) is safe and effective for heroin addiction, but the neural basis of the length effects of long-term MMT on brain activity during craving in former heroin addicts is unclear. This study explored it by comparing the brain activations of heroin addicts with different length of MMT during pictorial presentation of heroin-related cue. Fifteen male former heroin addicts successfully treated by MMT less than 1 year (Group A), 15 matched patients with 2-3 year MMT (Group B) and 17 healthy controls underwent functional magnetic resonance imaging while heroin-related and neutral stimuli were present to them. Subjective cue-elicited craving was measured with visual analog scale before and after imaging. Then, partial correlation analysis to reveal the relationship between drug-related blood oxygen level dependent (BOLD) signal intensity and heroin or methadone use history. Finally, self-reported craving was not different between Group A and B before and after scanning. Compared with Group A, Group B had a significant reduced brain activity to heroin-related minus neural cues in the bilateral caudate. After controlling for the variable heroin use history, the drug-related BOLD signal intensity in the bilateral caudate was negatively correlated with MMT duration and total methadone consumption. When MMT history was controlled, the drug-related activity intensity in right caudate had a positive correlation with heroin daily dosage. Long-term MMT may improve heroin-craving response by modulating the impaired function in the bilateral dorsal striatum caused by former heroin use.
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Affiliation(s)
- Yarong Wang
- Department of Radiology, Tangdu Hospital, the Fourth Military Medical University, 569 Xinsi Road, Baqiao District, Xi'an 710038, China; Department of Psychiatry and Addiction Medicine, University of Florida College of Medicine and McKnight Brain Institute, Gainesville, Florida 32610, USA
| | - Hanyue Wang
- Department of Radiology, Tangdu Hospital, the Fourth Military Medical University, 569 Xinsi Road, Baqiao District, Xi'an 710038, China
| | - Wei Li
- Department of Radiology, Tangdu Hospital, the Fourth Military Medical University, 569 Xinsi Road, Baqiao District, Xi'an 710038, China
| | - Jia Zhu
- Department of Radiology, Tangdu Hospital, the Fourth Military Medical University, 569 Xinsi Road, Baqiao District, Xi'an 710038, China
| | - Mark S Gold
- Department of Psychiatry and Addiction Medicine, University of Florida College of Medicine and McKnight Brain Institute, Gainesville, Florida 32610, USA
| | - Dongsheng Zhang
- Department of Radiology, Tangdu Hospital, the Fourth Military Medical University, 569 Xinsi Road, Baqiao District, Xi'an 710038, China
| | - Lina Wang
- Department of Radiology, Tangdu Hospital, the Fourth Military Medical University, 569 Xinsi Road, Baqiao District, Xi'an 710038, China
| | - Yongbin Li
- Department of Radiology, Tangdu Hospital, the Fourth Military Medical University, 569 Xinsi Road, Baqiao District, Xi'an 710038, China
| | - Xuejiao Yan
- Department of Radiology, Tangdu Hospital, the Fourth Military Medical University, 569 Xinsi Road, Baqiao District, Xi'an 710038, China
| | - Jiajie Cheng
- Department of Radiology, Tangdu Hospital, the Fourth Military Medical University, 569 Xinsi Road, Baqiao District, Xi'an 710038, China
| | - Qiang Li
- Department of Radiology, Tangdu Hospital, the Fourth Military Medical University, 569 Xinsi Road, Baqiao District, Xi'an 710038, China.
| | - Wei Wang
- Department of Radiology, Tangdu Hospital, the Fourth Military Medical University, 569 Xinsi Road, Baqiao District, Xi'an 710038, China.
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15
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Jiang YL, Tian W, Lu G, Rudd JA, Lai KF, Yeung LY, Wai MSM, Li YY, Huang ML, Yew DT. Patterns of cortical activation following motor tasks and psychological-inducing movie cues in heroin users: an fMRI study. Int J Psychiatry Med 2014; 47:25-40. [PMID: 24956915 DOI: 10.2190/pm.47.1.c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Drug abuse and addiction are worldwide health problems. However, few studies have used fMRI to investigate the effect of chronic heroin use on brain activation. This is a study along this line. METHOD fMRI positive sites in the brain were recorded during different motor and sensory activities. RESULTS Following motor activities, heroin users had more sites globally activated in the brain than in normal volunteers, with ex-heroin users being least reactive. Conversely, a "heroin puffing" movie produced more activation in ongoing-heroin and ex-heroin users than in the normal individuals, whereas a movie with explicit sexual content was less stimulatory in both groups of heroin users compared to normal individuals. CONCLUSIONS These significant findings relative to the function of specific brain nuclei are discussed.
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Affiliation(s)
| | | | - Gang Lu
- The Chinese University of Hong Kong, and, Kunming Medical University, China
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16
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Zamora-Martinez ER, Edwards S. Neuronal extracellular signal-regulated kinase (ERK) activity as marker and mediator of alcohol and opioid dependence. Front Integr Neurosci 2014; 8:24. [PMID: 24653683 PMCID: PMC3949304 DOI: 10.3389/fnint.2014.00024] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 02/19/2014] [Indexed: 11/13/2022] Open
Abstract
Early pioneering work in the field of biochemistry identified phosphorylation as a crucial post-translational modification of proteins with the ability to both indicate and arbitrate complex physiological processes. More recent investigations have functionally linked phosphorylation of extracellular signal-regulated kinase (ERK) to a variety of neurophysiological mechanisms ranging from acute neurotransmitter action to long-term gene expression. ERK phosphorylation serves as an intracellular bridging mechanism that facilitates neuronal communication and plasticity. Drugs of abuse, including alcohol and opioids, act as artificial yet powerful rewards that impinge upon natural reinforcement processes critical for survival. The graded progression from initial exposure to addiction (or substance dependence) is believed to result from drug- and drug context-induced adaptations in neuronal signaling processes across brain reward and stress circuits following excessive drug use. In this regard, commonly abused drugs as well as drug-associated experiences are capable of modifying the phosphorylation of ERK within central reinforcement systems. In addition, chronic drug and alcohol exposure may drive ERK-regulated epigenetic and structural alterations that underlie a long-term propensity for escalating drug use. Under the influence of such a neurobiological vulnerability, encountering drug-associated cues and contexts can produce subsequent alterations in ERK signaling that drive relapse to drug and alcohol seeking. Current studies are determining precisely which molecular and regional ERK phosphorylation-associated events contribute to the addiction process, as well as which neuroadaptations need to be targeted in order to return dependent individuals to a healthy state.
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Affiliation(s)
- Eva R Zamora-Martinez
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute La Jolla, CA, USA
| | - Scott Edwards
- Department of Physiology and Alcohol and Drug Abuse Center of Excellence, Louisiana State University Health Sciences Center New Orleans, LA, USA
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17
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Sillivan SE, Whittard JD, Jacobs MM, Ren Y, Mazloom AR, Caputi FF, Horvath M, Keller E, Ma’ayan A, Pan YX, Chiang LW, Hurd YL. ELK1 transcription factor linked to dysregulated striatal mu opioid receptor signaling network and OPRM1 polymorphism in human heroin abusers. Biol Psychiatry 2013; 74:511-9. [PMID: 23702428 PMCID: PMC4070524 DOI: 10.1016/j.biopsych.2013.04.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Revised: 04/12/2013] [Accepted: 04/12/2013] [Indexed: 12/21/2022]
Abstract
BACKGROUND Abuse of heroin and prescription opiate medications has grown to disturbing levels. Opioids mediate their effects through mu opioid receptors (MOR), but minimal information exists regarding MOR-related striatal signaling relevant to the human condition. The striatum is a structure central to reward and habitual behavior and neurobiological changes in this region are thought to underlie the pathophysiology of addiction disorders. METHODS We examined molecular mechanisms related to MOR in postmortem human brain striatal specimens from a homogenous European Caucasian population of heroin abusers and control subjects and in an animal model of heroin self-administration. Expression of ets-like kinase 1 (ELK1) was examined in relation to polymorphism of the MOR gene OPRM1 and drug history. RESULTS A characteristic feature of heroin abusers was decreased expression of MOR and extracellular regulated kinase signaling networks, concomitant with dysregulation of the downstream transcription factor ELK1. Striatal ELK1 in heroin abusers associated with the polymorphism rs2075572 in OPRM1 in a genotype dose-dependent manner and correlated with documented history of heroin use, an effect reproduced in an animal model that emphasizes a direct relationship between repeated heroin exposure and ELK1 dysregulation. A central role of ELK1 was evidenced by an unbiased whole transcriptome microarray that revealed ~20% of downregulated genes in human heroin abusers are ELK1 targets. Using chromatin immune precipitation, we confirmed decreased ELK1 promoter occupancy of the target gene Use1. CONCLUSIONS ELK1 is a potential key transcriptional regulatory factor in striatal disturbances associated with heroin abuse and relevant to genetic mutation of OPRM1.
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Affiliation(s)
- Stephanie E. Sillivan
- Department of Psychiatry and Neuroscience, Mount Sinai School of Medicine, New York, New York 10029
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York 10029
| | - John D. Whittard
- Department of Psychiatry and Neuroscience, Mount Sinai School of Medicine, New York, New York 10029
| | - Michelle M. Jacobs
- Department of Psychiatry and Neuroscience, Mount Sinai School of Medicine, New York, New York 10029
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York 10029
| | - Yanhua Ren
- Department of Psychiatry and Neuroscience, Mount Sinai School of Medicine, New York, New York 10029
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York 10029
| | - Amin R. Mazloom
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York 10029
| | - Francesca F. Caputi
- Department of Psychiatry and Neuroscience, Mount Sinai School of Medicine, New York, New York 10029
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York 10029
| | - Monika Horvath
- Department of Forensic Medicine, Uppsala University, Uppsala, Sweden
- Department of Forensic Medicine, Semmelweis University, Budapest, Hungary
| | - Eva Keller
- Department of Forensic Medicine, Semmelweis University, Budapest, Hungary
| | - Avi Ma’ayan
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York 10029
| | - Ying-Xian Pan
- Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | | | - Yasmin L. Hurd
- Department of Psychiatry and Neuroscience, Mount Sinai School of Medicine, New York, New York 10029
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York 10029
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18
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Santulli G, Trimarco B, Iaccarino G. G-protein-coupled receptor kinase 2 and hypertension: molecular insights and pathophysiological mechanisms. High Blood Press Cardiovasc Prev 2013; 20:5-12. [PMID: 23532739 DOI: 10.1007/s40292-013-0001-8] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 11/06/2012] [Indexed: 12/17/2022] Open
Abstract
Numerous factors partake in the fine-tuning of arterial blood pressure. The heptahelical G-protein-coupled receptors (GPCRs) represent one of the largest classes of cell-surface receptors. Further, ligands directed at GPCRs account for nearly 30 % of current clinical pharmaceutical agents available. Given the wide variety of GPCRs involved in blood pressure control, it is reasonable to speculate for a potential role of established intermediaries involved in the GPCR desensitization process, like the G-protein-coupled receptor kinases (GRKs), in the regulation of vascular tone. Of the seven mammalian GRKs, GRK2 seems to be the most relevant isoform at the cardiovascular level. This review attempts to assemble the currently available information concerning GRK2 and hypertension, opening new potential fields of translational investigation to treat this vexing disease.
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Affiliation(s)
- Gaetano Santulli
- Department of Advanced Biomedical Sciences, Federico II University of Naples, 80131, Naples, Italy.
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19
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Zhao J, Xin X, Xie GX, Palmer PP, Huang YG. Molecular and cellular mechanisms of the age-dependency of opioid analgesia and tolerance. Mol Pain 2012; 8:38. [PMID: 22612909 PMCID: PMC3517334 DOI: 10.1186/1744-8069-8-38] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 05/09/2012] [Indexed: 01/17/2023] Open
Abstract
The age-dependency of opioid analgesia and tolerance has been noticed in both clinical observation and laboratory studies. Evidence shows that many molecular and cellular events that play essential roles in opioid analgesia and tolerance are actually age-dependent. For example, the expression and functions of endogenous opioid peptides, multiple types of opioid receptors, G protein subunits that couple to opioid receptors, and regulators of G protein signaling (RGS proteins) change with development and age. Other signaling systems that are critical to opioid tolerance development, such as N-methyl-D-aspartic acid (NMDA) receptors, also undergo age-related changes. It is plausible that the age-dependent expression and functions of molecules within and related to the opioid signaling pathways, as well as age-dependent cellular activity such as agonist-induced opioid receptor internalization and desensitization, eventually lead to significant age-dependent changes in opioid analgesia and tolerance development.
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Affiliation(s)
- Jing Zhao
- Department of Anesthesia, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China
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20
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Álvaro-Bartolomé M, La Harpe R, Callado L, Meana J, García-Sevilla J. Molecular adaptations of apoptotic pathways and signaling partners in the cerebral cortex of human cocaine addicts and cocaine-treated rats. Neuroscience 2011; 196:1-15. [DOI: 10.1016/j.neuroscience.2011.08.074] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 08/30/2011] [Accepted: 08/30/2011] [Indexed: 01/08/2023]
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21
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Bai B, Liu HQ, Chen J, Li YL, Du H, Lu H, Yu PL. Construction of the Subtracted cDNA Library of Striatal Neurons Treated with Long-term Morphine. ACTA ACUST UNITED AC 2011; 26:54-9. [DOI: 10.1016/s1001-9294(11)60020-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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22
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Lötsch J, Geisslinger G, Tegeder I. Genetic modulation of the pharmacological treatment of pain. Pharmacol Ther 2009; 124:168-84. [DOI: 10.1016/j.pharmthera.2009.06.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Accepted: 06/22/2009] [Indexed: 12/15/2022]
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23
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Eisinger DA, Ammer H. Down-regulation of c-Cbl by morphine accounts for persistent ERK1/2 signaling in delta-opioid receptor-expressing HEK293 cells. J Biol Chem 2009; 284:34819-28. [PMID: 19828455 DOI: 10.1074/jbc.m109.042937] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Opioids display ligand-specific differences in the time course of ERK1/2 signaling. Whereas full agonists, like etorphine, induce only transient activation of ERK1/2, the partial agonist morphine mediates persistent stimulation of mitogenic signaling. Here we report that in stably delta-opioid receptor (DOR)-expressing HEK293 (HEK/DOR) cells, the transient nature of etorphine-induced ERK1/2 signaling is due to desensitization of epidermal growth factor (EGF) receptor-mediated activation of the Ras/Raf-1/ERK1/2 cascade. Desensitization of ERK1/2 activity by etorphine is associated with down-regulation of EGF receptors, an effect mediated by the ubiquitin ligase c-Cbl. In contrast, chronic morphine treatment failed to desensitize EGF receptors, resulting in unimpeded ERK1/2 signaling. The failure of morphine to desensitize ERK1/2 signaling is mediated by persistent activation of c-Src, which induces degradation of c-Cbl. The role of c-Src in opioid-specific ERK1/2 signaling is further demonstrated by pretreatment of the cells with PP2 and SKI-I as well as overexpression of a dominant negative c-Src mutant (c-Src(dn)) or a c-Src-resistant c-Cbl mutant (CblY3F), both of which facilitate desensitization of ERK1/2 signaling by morphine. Conversely, overexpression of c-Src as well as down-regulation of c-Cbl by small interfering RNA results in persistent etorphine-induced stimulation of ERK1/2 activity. Subcellular fractionation experiments finally attributed the ability of morphine to persistently activate c-Src to its redistribution from Triton X-100-insensitive membrane rafts to DOR and EGF receptor containing high density membrane compartments implicated in ERK1/2 signaling. These results demonstrate that agonist-specific differences in the temporal and spatial pattern of c-Src activation determine the kinetics of DOR-mediated regulation of ERK1/2 signaling.
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Affiliation(s)
- Daniela A Eisinger
- Institute of Pharmacology, Toxicology and Pharmacy, Ludwig-Maximilians-University Munich, 80539 Muenchen, Germany.
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24
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Hernández-Pinto AM, Puebla-Jiménez L, Arilla-Ferreiro E. alpha-Tocopherol decreases the somatostatin receptor-effector system and increases the cyclic AMP/cyclic AMP response element binding protein pathway in the rat dentate gyrus. Neuroscience 2009; 162:106-17. [PMID: 19393293 DOI: 10.1016/j.neuroscience.2009.04.047] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Revised: 04/06/2009] [Accepted: 04/19/2009] [Indexed: 02/07/2023]
Abstract
Neuronal survival has been shown to be enhanced by alpha-tocopherol and modulated by cyclic AMP (cAMP). Somatostatin (SST) receptors couple negatively to adenylyl cyclase (AC), thus leading to decreased cAMP levels. Whether alpha-tocopherol can stimulate neuronal survival via regulation of the somatostatinergic system, however, is unknown. The aim of this study was to investigate the effects of alpha-tocopherol on the SST signaling pathway in the rat dentate gyrus. To that end, 15-week-old male Sprague-Dawley rats were treated daily for 1 week with (+)-alpha-tocopherol or vehicle and sacrificed on the day following the last administration. No changes in either SST-like immunoreactivity (SST-LI) content or SST mRNA levels were detected in the dentate gyrus as a result of alpha-tocopherol treatment. A significant decrease in the density of the SST binding sites and an increase in the dissociation constant, however, were detected. The lower SST receptor density in the alpha-tocopherol-treated rats correlated with a significant decrease in the protein levels of the SST receptor subtypes SSTR1-SSTR4, whereas the corresponding mRNA levels were unaltered. G-protein-coupled-receptor kinase 2 expression was decreased by alpha-tocopherol treatment. This vitamin induced a significant increase in both basal and forskolin-stimulated AC activity, as well as a decrease in the inhibitory effect of SST on AC. Whereas the protein levels of AC type V/VI were not modified by alpha-tocopherol administration, ACVIII expression was significantly enhanced, suggesting it might account for the increase in AC activity. In addition, this treatment led to a reduction in Gialpha1-3 protein levels and in Gi functionality. alpha-Tocopherol did not affect the expression of the regulator of G-protein signaling 6/7 (RGS6/7). Finally, alpha-tocopherol induced an increase in the levels of phosphorylated cAMP response element binding protein (p-CREB) and total CREB in the dentate gyrus. Since CREB synthesis and phosphorylation promote the survival of many cells, including neurons, whereas SST inhibits the cAMP-PKA pathway, which is known to be involved in CREB phosphorylation, the alpha-tocopherol-induced reduction of SSTR observed here might possibly contribute, via increased cAMP levels and CREB activity, to the mechanism by which this vitamin promotes the survival of newborn neurons in the dentate gyrus.
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Affiliation(s)
- A M Hernández-Pinto
- Grupo de Neurobioquímica, Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Crta. Madrid-Barcelona Km. 33.6, Universidad de Alcalá de Henares, E-28871 Alcalá de Henares, Madrid, Spain
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25
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Alfaras-Melainis K, Gomes I, Rozenfeld R, Zachariou V, Devi L. Modulation of opioid receptor function by protein-protein interactions. Front Biosci (Landmark Ed) 2009; 14:3594-607. [PMID: 19273296 DOI: 10.2741/3474] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Opioid receptors, MORP, DORP and KORP, belong to the family A of G protein coupled receptors (GPCR), and have been found to modulate a large number of physiological functions, including mood, stress, appetite, nociception and immune responses. Exogenously applied opioid alkaloids produce analgesia, hedonia and addiction. Addiction is linked to alterations in function and responsiveness of all three opioid receptors in the brain. Over the last few years, a large number of studies identified protein-protein interactions that play an essential role in opioid receptor function and responsiveness. Here, we summarize interactions shown to affect receptor biogenesis and trafficking, as well as those affecting signal transduction events following receptor activation. This article also examines protein interactions modulating the rate of receptor endocytosis and degradation, events that play a major role in opiate analgesia. Like several other GPCRs, opioid receptors may form homo or heterodimers. The last part of this review summarizes recent knowledge on proteins known to affect opioid receptor dimerization.
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26
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Effects of chronic morphine and morphine withdrawal on gene expression in rat peripheral blood mononuclear cells. Neuropharmacology 2008; 55:1347-54. [DOI: 10.1016/j.neuropharm.2008.08.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 08/04/2008] [Accepted: 08/19/2008] [Indexed: 12/30/2022]
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27
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Saland LC, Chavez JB, Lee DC, Garcia RR, Caldwell KK. Chronic ethanol exposure increases the association of hippocampal mu-opioid receptors with G-protein receptor kinase 2. Alcohol 2008; 42:493-7. [PMID: 18760718 DOI: 10.1016/j.alcohol.2008.06.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 06/06/2008] [Accepted: 06/09/2008] [Indexed: 11/26/2022]
Abstract
Opioid receptors (ORs) have been shown to have a significant role in the central nervous system (CNS) effects of chronic ethanol consumption. The OR antagonist, naltrexone, is used clinically to reduce continued intake. We previously observed that chronic ethanol consumption, by adult male Sprague-Dawley rats, induced a reduction in functional coupling of mu- and delta-ORs to G-proteins in rat CNS regions, including the hippocampus. G-protein receptor kinase (GRK) 2 phosphorylates G-protein coupled receptors, including ORs, after agonist binding, as part of normal regulation and desensitization. We tested the hypothesis that chronic ethanol exposure affects the association of the GRK2 with the mu-OR. Co-immunoprecipitation methods were used to determine if mu-OR association with GRK2 is elevated in the hippocampus after chronic ethanol, when compared to controls. Hippocampal homogenates from chronic ethanol and pair-fed control rats were treated with affinity-purified rabbit polyclonal antibodies (ab) to mu-OR, and immune complexes were probed for GRK2 by immunoblotting techniques. Results demonstrate an association of GRK2 with mu-ORs in chronic ethanol-treated rats, but not in the controls. Possible changes in GRK2 association with ORs after chronic ethanol may be related to levels of phosphorylation and subsequent trafficking of the receptors.
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28
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Rodríguez-Muñoz M, de la Torre-Madrid E, Gaitán G, Sánchez-Blázquez P, Garzón J. RGS14 prevents morphine from internalizing Mu-opioid receptors in periaqueductal gray neurons. Cell Signal 2007; 19:2558-71. [PMID: 17825524 DOI: 10.1016/j.cellsig.2007.08.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 08/06/2007] [Indexed: 01/24/2023]
Abstract
Opioid agonists display different capacities to stimulate mu-opioid receptor (MOR) endocytosis, which is related to their ability to provoke the phosphorylation of specific cytosolic residues in the MORs. Generally, opioids that efficiently promote MOR endocytosis and recycling produce little tolerance, as is the case for [D-Ala(2), N-MePhe(4),Gly-ol(5)] encephalin (DAMGO). However, morphine produces rapid and profound antinociceptive desensitization in the adult mouse brain associated with little MOR internalization. The regulator of G-protein signaling, the RGS14 protein, associates with MORs in periaqueductal gray matter (PAG) neurons, and when RGS14 is silenced morphine increased the serine 375 phosphorylation in the C terminus of the MOR, a GRK substrate. Subsequently, these receptors were internalized and recycled back to the membrane where they accumulated on cessation of antinociception. These mice now exhibited a resensitized response to morphine and little tolerance developed. Thus, in morphine-activated MORs the RGS14 prevents GRKs from phosphorylating those residues required for beta-arresting-mediated endocytosis. Moreover morphine but not DAMGO triggered a process involving calcium/calmodulin-dependent kinase II (CaMKII) in naïve mice, which contributes to MOR desensitization in the plasma membrane. In RGS14 knockdown mice morphine failed to activate this kinase. It therefore appears that phosphorylation and internalization of MORs disrupts the CaMKII-mediated negative regulation of these opioid receptors.
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MESH Headings
- Amino Acid Sequence
- Analgesics, Opioid/administration & dosage
- Analgesics, Opioid/pharmacology
- Animals
- Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Drug Tolerance
- Endocytosis/drug effects
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Enzyme Activation
- G-Protein-Coupled Receptor Kinases/metabolism
- Gene Silencing
- Hot Temperature/adverse effects
- Injections, Intraventricular
- Male
- Mice
- Molecular Sequence Data
- Morphine/administration & dosage
- Morphine/pharmacology
- Neurons/drug effects
- Neurons/enzymology
- Neurons/metabolism
- Oligonucleotides, Antisense/metabolism
- Pain/etiology
- Pain/physiopathology
- Pain/prevention & control
- Pain Measurement
- Pain Threshold/drug effects
- Periaqueductal Gray/cytology
- Periaqueductal Gray/drug effects
- Periaqueductal Gray/enzymology
- Periaqueductal Gray/metabolism
- Phosphorylation
- RGS Proteins/genetics
- RGS Proteins/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/metabolism
- Serine/metabolism
- Synaptosomes/drug effects
- Synaptosomes/metabolism
- Time Factors
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Affiliation(s)
- María Rodríguez-Muñoz
- Neurofarmacología, Instituto de Neurobiología Santiago Ramón y Cajal, Madrid E-28002, Spain
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Williams TM, Daglish MRC, Lingford-Hughes A, Taylor LG, Hammers A, Brooks DJ, Grasby P, Myles JS, Nutt DJ. Brain opioid receptor binding in early abstinence from opioid dependence: positron emission tomography study. Br J Psychiatry 2007; 191:63-9. [PMID: 17602127 DOI: 10.1192/bjp.bp.106.031120] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Although opioid receptor function in humans is clearly reduced during opioid dependence, what happens to the receptor in early abstinence is not understood. AIMS This study sought to examine changes in opioid receptor availability in early abstinence from opioid dependence. METHOD Ten people with opioid dependence who had completed in-patient detoxification and 20 healthy controls underwent [11C]-diprenorphine positron emission tomography. Clinical variables were assessed with structured questionnaires. Opioid receptor binding was characterised as the volume of distribution of [11C]-diprenorphine using a template of predefined brain volumes and an exploratory voxel-by-voxel analysis. RESULTS Compared with controls, participants with opioid dependence had increased [11C]-diprenorphine binding in the whole brain and in 15 of the 21 a priori regions studied. CONCLUSIONS This study suggests that opioid receptor binding is increased throughout the brain in early abstinence from dependent opioid use. These data complement the findings in cocaine and alcohol dependence.
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Affiliation(s)
- Tim M Williams
- Psychopharmacology Unit, University of Bristol, and Bristol Specialist Drug Service, Blackberry Hill Hospital, UK
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Abstract
Heterotrimeric G protein-coupled receptors (GPCRs) are found on the surface of all cells of multicellular organisms and are major mediators of intercellular communication. More than 800 distinct GPCRs are present in the human genome, and individual receptor subtypes respond to hormones, neurotransmitters, chemokines, odorants, or tastants. GPCRs represent the most widely targeted pharmacological protein class. Because drugs that target GPCRs often engage receptor regulatory mechanisms that limit drug effectiveness, particularly in chronic treatment, there is great interest in understanding how GPCRs are regulated, as a basis for designing therapeutic drugs that evade this regulation. The major GPCR regulatory pathway involves phosphorylation of activated receptors by G protein-coupled receptor kinases (GRKs), followed by binding of arrestin proteins, which prevent receptors from activating downstream heterotrimeric G protein pathways while allowing activation of arrestin-dependent signaling pathways. Although the general mechanisms of GRK-arrestin regulation have been well explored in model cell systems and with purified proteins, much less is known about the role of GRK-arrestin regulation of receptors in physiological and pathophysiological settings. This review focuses on the physiological functions and potential pathophysiological roles of GRKs and arrestins in human disorders as well as on recent studies using knockout and transgenic mice to explore the role of GRK-arrestin regulation of GPCRs in vivo.
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Affiliation(s)
- Richard T Premont
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
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31
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Golovko AI, Golovko SI, Leontieva LV. The neurochemistry of the psychological dependence syndrome in addictive diseases of chemical etiology. NEUROCHEM J+ 2007. [DOI: 10.1134/s1819712407010011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Cunha-Oliveira T, Rego AC, Garrido J, Borges F, Macedo T, Oliveira CR. Street heroin induces mitochondrial dysfunction and apoptosis in rat cortical neurons. J Neurochem 2007; 101:543-54. [PMID: 17250679 DOI: 10.1111/j.1471-4159.2006.04406.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cortical function has been suggested to be highly compromised by repeated heroin self-administration. We have previously shown that street heroin induces apoptosis in neuronal-like PC12 cells. Thus, we analysed the apoptotic pathways involved in street heroin neurotoxicity using primary cultures of rat cortical neurons. Our street heroin sample was shown to be mainly composed by heroin, 6-monoacetylmorphine and morphine. Exposure of cortical neurons to street heroin induced a slight decrease in metabolic viability, without loss of neuronal integrity. Early activation of caspases involved in the mitochondrial apoptotic pathway was observed, culminating in caspase 3 activation, Poly-ADP Ribose Polymerase (PARP) cleavage and DNA fragmentation. Apoptotic morphology was completely prevented by the non-selective caspase inhibitor z-VAD-fmk, indicating an important role for caspases in neurodegeneration induced by street heroin. Ionotropic glutamate receptors, opioid receptors and oxidative stress were not involved in caspase 3 activation. Interestingly, street heroin cytotoxicity was shown to be independent of a functional mitochondrial respiratory chain, as determined using NT-2 rho(0) cells. Nonetheless, in street heroin-treated cortical neurons, cytochrome c was released, accompanied by a decrease in mitochondrial potential and Bcl-2/Bax. Pure heroin hydrochloride similarly decreased metabolic viability but only slightly activated caspase 3. Altogether, our data suggest an important role for mitochondria in mediating street heroin neurotoxic effects.
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Canciani L, Giaroni C, Zanetti E, Giuliani D, Pisani R, Moro E, Trinchera M, Crema F, Lecchini S, Frigo G. Functional interaction between α2-adrenoceptors, μ- and κ-opioid receptors in the guinea pig myenteric plexus: Effect of chronic desipramine treatment. Eur J Pharmacol 2006; 553:269-79. [PMID: 17055479 DOI: 10.1016/j.ejphar.2006.09.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Revised: 09/08/2006] [Accepted: 09/11/2006] [Indexed: 10/24/2022]
Abstract
The existence of a functional interplay between alpha(2)-adrenoceptor and opioid receptor inhibitory pathways modulating neurotransmitter release has been demonstrated in the enteric nervous system by development of sensitivity changes to alpha(2)-adrenoceptor, mu- and kappa-opioid receptor agents on enteric cholinergic neurons after chronic sympathetic denervation. In the present study, to further examine this hypothesis we evaluated whether manipulation of alpha(2)-adrenoceptor pathways by chronic treatment with the antidepressant drug, desipramine (10 mg/kg i.p. daily, for 21 days), could entail changes in enteric mu- and kappa-opioid receptor pathways in the myenteric plexus of the guinea pig distal colon. In this region, subsensitivity to the inhibitory effect of both UK14,304 and U69,593, respectively alpha(2A)-adrenoceptor and kappa-opioid receptor agonist, on the peristaltic reflex developed after chronic desipramine treatment. On opposite, in these experimental conditions, supersensitivity developed to the inhibitory effect of [D-Ala, N-Me-Phe4-Gly-ol5]-enkephalin (DAMGO), mu-opioid receptor agonist, on propulsion velocity. Immunoreactive expression levels of alpha(2A)-adrenoceptors, mu- and kappa-opioid receptors significantly decreased in the myenteric plexus of the guinea pig colon after chronic desipramine treatment. In these experimental conditions, mRNA levels of alpha(2A)-adrenoceptors, mu- and kappa-opioid receptors significantly increased, excluding a direct involvement of transcription mechanisms in the regulation of receptor expression. Levels of G protein-coupled receptor kinase 2/3 and of inhibitory G(i/o) proteins were significantly reduced in the myenteric plexus after chronic treatment with desipramine. Such changes might represent possible molecular mechanisms involved in the development of subsensitivity to UK14,304 and U69,593 on the efficiency of peristalsis. Alternative molecular mechanisms, including a higher efficiency in the coupling between receptor activation and downstream intracellular effector systems, possibly independent from inhibitory G(i/o) proteins, may be accounted for the development of supersensitivity to DAMGO. Increased sensitivity to the mu-opioid agonist might compensate for the development of alpha(2A)-adrenoceptor and kappa-opioid receptor subsensitivity. On the whole, the present data further strengthen the concept that, manipulation of alpha(2)-adrenergic inhibitory receptor pathways in the enteric nervous system entails changes in opioid inhibitory receptor pathways, which might be involved in maintaining homeostasis as suggested for mu-opioid, but not for kappa-opioid receptors.
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MESH Headings
- Adrenergic alpha-2 Receptor Agonists
- Adrenergic alpha-Agonists/pharmacology
- Analgesics/pharmacology
- Analgesics, Opioid/pharmacology
- Animals
- Antidepressive Agents, Tricyclic/pharmacology
- Benzeneacetamides/pharmacology
- Blotting, Western
- Brimonidine Tartrate
- Desipramine/pharmacology
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- G Protein-Coupled Inwardly-Rectifying Potassium Channels/biosynthesis
- GTP-Binding Proteins/biosynthesis
- Guinea Pigs
- In Vitro Techniques
- Male
- Myenteric Plexus/drug effects
- Peristalsis/drug effects
- Pyrrolidines/pharmacology
- Quinoxalines/pharmacology
- RNA, Messenger/biosynthesis
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/drug effects
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/drug effects
- Reverse Transcriptase Polymerase Chain Reaction
- Synaptosomes/drug effects
- Synaptosomes/metabolism
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Affiliation(s)
- Luca Canciani
- Clinical and Applied Pharmacology Centre, University of Insubria and University of Pavia, via O Rossi 9, I-21100 Varese, Italy
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Abstract
Phosphorylation of the agonist-activated form of G-protein-coupled receptors (GPCRs) by a protein kinase from the G-protein-coupled receptor kinase (GRK) family initiates, with arrestin proteins, a negative feedback process known as desensitization. Because these receptors are involved in so many vital functions, it seems likely that disorders affecting GRK- or arrestin-mediated regulation of GPCRs would contribute to, if not engender, disease. Traditionally, it is believed that the desensitization process protects the cell against an overstimulation; however, in certain situations, this process is maladjusted and participes in disease progression. For example, in Oguchi disease, excessive rhodopsin stimulation due to a functional loss of GRK1 or arrestin 1 leads to light sensitization and stationary night blindness. Also, transgenic mice with vascular smooth muscle-targeted overexpression of GRK2 showed an elevated resting blood pressure, suggesting that increase in GRK2 level in humans is involved in hypertension associated with a decreased effect of beta-adrenergic receptor-mediated vasorelaxation. The restoration of normal GPCR function in modulating the desensitization process has been successfully demonstrated in animal models of heart failure, which indicates that targeting GRKs or arrestins may open a novel therapeutic strategy in human diseases with GPCR dysregulation. However, the few effective pharmacological compounds in this domain currently preclude human clinical tests.
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Affiliation(s)
- Thierry Métayé
- Laboratoire de Biophysique, Groupe de Recherche en Endocrinologie Expérimentale et Clinique, CHU de Poitiers, BP577, 86021 Poitiers Cedex, France.
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Abstract
This paper is the 27th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over 30 years of research. It summarizes papers published during 2004 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, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, USA.
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36
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Abstract
Opiate drugs such as morphine are well known for their ability to produce potent analgesia as well as such unwanted side effects as tolerance, physical dependence, respiratory suppression and constipation. Opiates act at opioid receptors, which belong to the family of G protein-coupled receptors. The mechanisms governing mu opioid receptor (muOR) regulation are of particular interest since morphine and other clinically important analgesics produce their pharmacological effects through this receptor. Here we review recent advances in understanding how opioid receptor regulation can impart differential agonist efficacy produced in vivo.
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Affiliation(s)
- Kirsten M. Raehal
- Department of Pharmacology & Psychiatry, The Ohio State University, College of Medicine & Health Science, 5184A Graves Hall, 333 W 10th Ave, 43210-1239 Columbus, OH
| | - Laura M. Bohn
- Department of Pharmacology & Psychiatry, The Ohio State University, College of Medicine & Health Science, 5184A Graves Hall, 333 W 10th Ave, 43210-1239 Columbus, OH
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Métayé T, Gibelin H, Perdrisot R, Kraimps JL. Pathophysiological roles of G-protein-coupled receptor kinases. Cell Signal 2005; 17:917-28. [PMID: 15894165 DOI: 10.1016/j.cellsig.2005.01.002] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Accepted: 01/11/2005] [Indexed: 12/19/2022]
Abstract
G-protein-coupled receptor kinases (GRKs) interact with the agonist-activated form of G-protein-coupled receptors (GPCRs) to effect receptor phosphorylation and to initiate profound impairment of receptor signalling, or desensitization. GPCRs form the largest family of cell surface receptors known and defects in GRK function have the potential consequence to affect GPCR-stimulated biological responses in many pathological situations. This review focuses on the physiological role of GRKs revealed by genetically modified animals but also develops the involvement of GRKs in human diseases as, Oguchi disease, heart failure, hypertension or rhumatoid arthritis. Furthermore, the regulation of GRK levels in opiate addiction, cancers, psychiatric diseases, cystic fibrosis and cardiac diseases is discussed. Both transgenic mice and human pathologies have demonstrated the importance of GRKs in the signalling pathways of rhodopsin, beta-adrenergic and dopamine-1 receptors. The modulation of GRK activity in animal models of cardiac diseases can be effective to restore cardiac function in heart failure and opens a novel therapeutic strategy in diseases with GPCR dysregulation.
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Affiliation(s)
- Thierry Métayé
- Department of Nuclear Medicine and Biophysics, Groupe de Recherche en Endocrinologie Expérimentale et Clinique, CHU de Poitiers, France.
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Ferrer-Alcón M, García-Fuster MJ, La Harpe R, García-Sevilla JA. Long-term regulation of signalling components of adenylyl cyclase and mitogen-activated protein kinase in the pre-frontal cortex of human opiate addicts. J Neurochem 2004; 90:220-30. [PMID: 15198681 DOI: 10.1111/j.1471-4159.2004.02473.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Opiate addiction involves the development of chronic adaptive changes in micro -opioid receptors and associated pathways (e.g. cAMP signalling) which lead to neuronal plasticity in the brain. This study assessed the status of cAMP and mitogen-activated protein kinase (MAPK) pathways in brains (pre-frontal cortex) of chronic opiate addicts. In these subjects (n = 24), the immunodensities of adenylyl cyclase-I, PKA Calpha, total and phosphorylated CREB were not different from those in sex-, age- and PMD-matched controls. Moreover, the ratio pCREB/tCREB was similar in opiate addicts (0.74) and controls (0.76), further indicating that opiate addiction in humans is not associated with an upregulation of several key components of cAMP signalling in the pre-frontal cortex. In contrast, the components of MAPK cascade (Ras/c-Raf-1/MEK/ERK) were decreased in the same brains. Notably, pronounced downregulations of phosphorylated MEK (85%) and ERK1/2 (pERK1: 81%; pERK2: 80%) were quantitated in brains of opiate addicts. Chronic morphine treatment in rats (10-100 mg/kg for 5 days) was also associated with decreases of pERK1/2 (59-68%) in the cortex. In SH-SY5Y cells, morphine also stimulated the activity of pERK1/2 (2.5-fold) and the MEK inhibitor PD98059 blocked this effect (90%). The abnormalities of MAPK signalling might have important consequences in the long term development of various forms of neural plasticity associated with opiate addiction in humans.
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Affiliation(s)
- M Ferrer-Alcón
- Clinical Research Unit, Department of Psychiatry, University of Geneva, Chêne-Bourg, Switzerland
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