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Agulló L, Escorial M, Orutño S, Muriel J, Sandoval J, Margarit C, Peiró AM. Epigenetic and sex differences in opioid use disorder in chronic pain: A real-world study linked with OPRM1 DNA methylation. Addict Biol 2024; 29:e13422. [PMID: 38949208 PMCID: PMC11215788 DOI: 10.1111/adb.13422] [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: 02/05/2024] [Revised: 05/24/2024] [Accepted: 06/04/2024] [Indexed: 07/02/2024]
Abstract
Opioid use disorder (OUD) is a multifaceted condition influenced by sex, genetic and environmental factors that could be linked with epigenetic changes. Understanding how these factors interact is crucial to understand and address the development and progression of this disorder. Our aim was to elucidate different potential epigenetic and genetic mechanisms between women and men that correlate with OUD under real-world pain unit conditions. Associations between analgesic response and the DNA methylation level of the opioid mu receptor (OPRM1) gene (CpG sites 1-5 selected in the promoter region) were evaluated in 345 long opioid-treated chronic non cancer pain: cases with OUD (n = 67) and controls (without OUD, n = 278). Cases showed younger ages, low employment status and quality of life, but higher morphine equivalent daily dose and psychotropic use, compared to the controls. The patients with OUD showed a significant decrease in OPRM1 DNA methylation, which correlated with clinical outcomes like pain relief, depression and different adverse events. Significant differences were found at the five CpG sites studied for men, and exclusively in women for CpG site 3, in relation to OUD diagnosis. These findings support the importance of epigenetics and sex as biological variables to be considered toward efficient OUD understanding and therapy development.
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Affiliation(s)
- Laura Agulló
- Pharmacogenetic Unit, Clinical Pharmacology DepartmentAlicante Institute for Health and Biomedical Research (ISABIAL)AlicanteSpain
- Bioengineering Institute, Department of Pharmacology, Paediatrics and Organic ChemistryMiguel Hernández University (UMH)ElcheSpain
| | - Mónica Escorial
- Pharmacogenetic Unit, Clinical Pharmacology DepartmentAlicante Institute for Health and Biomedical Research (ISABIAL)AlicanteSpain
- Bioengineering Institute, Department of Pharmacology, Paediatrics and Organic ChemistryMiguel Hernández University (UMH)ElcheSpain
| | - Samantha Orutño
- Alicante Institute for Health and Biomedical Research (ISABIAL)AlicanteSpain
| | - Javier Muriel
- Pharmacogenetic Unit, Clinical Pharmacology DepartmentAlicante Institute for Health and Biomedical Research (ISABIAL)AlicanteSpain
| | - Juan Sandoval
- Epigenomics UnitLa Fe Health Research InstituteValenciaSpain
| | - César Margarit
- Pain Unit, Department of Health of AlicanteDr. Balmis General HospitalAlicanteSpain
| | - Ana M. Peiró
- Pharmacogenetic Unit, Clinical Pharmacology DepartmentAlicante Institute for Health and Biomedical Research (ISABIAL)AlicanteSpain
- Bioengineering Institute, Department of Pharmacology, Paediatrics and Organic ChemistryMiguel Hernández University (UMH)ElcheSpain
- Pain Unit, Department of Health of AlicanteDr. Balmis General HospitalAlicanteSpain
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2
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Quezada M, Ponce C, Berríos‐Cárcamo P, Santapau D, Gallardo J, De Gregorio C, Quintanilla ME, Morales P, Ezquer M, Herrera‐Marschitz M, Israel Y, Andrés‐Herrera P, Hipólito L, Ezquer F. Amelioration of morphine withdrawal syndrome by systemic and intranasal administration of mesenchymal stem cell-derived secretome in preclinical models of morphine dependence. CNS Neurosci Ther 2024; 30:e14517. [PMID: 37927136 PMCID: PMC11017443 DOI: 10.1111/cns.14517] [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: 07/31/2023] [Revised: 09/21/2023] [Accepted: 10/12/2023] [Indexed: 11/07/2023] Open
Abstract
BACKGROUND Morphine is an opiate commonly used in the treatment of moderate to severe pain. However, prolonged administration can lead to physical dependence and strong withdrawal symptoms upon cessation of morphine use. These symptoms can include anxiety, irritability, increased heart rate, and muscle cramps, which strongly promote morphine use relapse. The morphine-induced increases in neuroinflammation, brain oxidative stress, and alteration of glutamate levels in the hippocampus and nucleus accumbens have been associated with morphine dependence and a higher severity of withdrawal symptoms. Due to its rich content in potent anti-inflammatory and antioxidant factors, secretome derived from human mesenchymal stem cells (hMSCs) is proposed as a preclinical therapeutic tool for the treatment of this complex neurological condition associated with neuroinflammation and brain oxidative stress. METHODS Two animal models of morphine dependence were used to evaluate the therapeutic efficacy of hMSC-derived secretome in reducing morphine withdrawal signs. In the first model, rats were implanted subcutaneously with mini-pumps which released morphine at a concentration of 10 mg/kg/day for seven days. Three days after pump implantation, animals were treated with a simultaneous intravenous and intranasal administration of hMSC-derived secretome or vehicle, and withdrawal signs were precipitated on day seven by i.p. naloxone administration. In this model, brain alterations associated with withdrawal were also analyzed before withdrawal precipitation. In the second animal model, rats voluntarily consuming morphine for three weeks were intravenously and intranasally treated with hMSC-derived secretome or vehicle, and withdrawal signs were induced by morphine deprivation. RESULTS In both animal models secretome administration induced a significant reduction of withdrawal signs, as shown by a reduction in a combined withdrawal score. Secretome administration also promoted a reduction in morphine-induced neuroinflammation in the hippocampus and nucleus accumbens, while no changes were observed in extracellular glutamate levels in the nucleus accumbens. CONCLUSION Data presented from two animal models of morphine dependence suggest that administration of secretome derived from hMSCs reduces the development of opioid withdrawal signs, which correlates with a reduction in neuroinflammation in the hippocampus and nucleus accumbens.
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Affiliation(s)
- Mauricio Quezada
- Center for Regenerative Medicine, Faculty of MedicineClínica Alemana‐Universidad del DesarrolloSantiagoChile
| | - Carolina Ponce
- Department of Neuroscience, Faculty of MedicineUniversidad de ChileSantiagoChile
| | - Pablo Berríos‐Cárcamo
- Center for Regenerative Medicine, Faculty of MedicineClínica Alemana‐Universidad del DesarrolloSantiagoChile
| | - Daniela Santapau
- Center for Regenerative Medicine, Faculty of MedicineClínica Alemana‐Universidad del DesarrolloSantiagoChile
| | - Javiera Gallardo
- Center for Regenerative Medicine, Faculty of MedicineClínica Alemana‐Universidad del DesarrolloSantiagoChile
| | - Cristian De Gregorio
- Center for Regenerative Medicine, Faculty of MedicineClínica Alemana‐Universidad del DesarrolloSantiagoChile
| | - María Elena Quintanilla
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Science, Faculty of MedicineUniversidad de ChileSantiagoChile
| | - Paola Morales
- Department of Neuroscience, Faculty of MedicineUniversidad de ChileSantiagoChile
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Science, Faculty of MedicineUniversidad de ChileSantiagoChile
| | - Marcelo Ezquer
- Center for Regenerative Medicine, Faculty of MedicineClínica Alemana‐Universidad del DesarrolloSantiagoChile
| | - Mario Herrera‐Marschitz
- Department of Neuroscience, Faculty of MedicineUniversidad de ChileSantiagoChile
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Science, Faculty of MedicineUniversidad de ChileSantiagoChile
| | - Yedy Israel
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Science, Faculty of MedicineUniversidad de ChileSantiagoChile
| | - Paula Andrés‐Herrera
- Department of Pharmacy and Pharmaceutical Technology and ParasitologyUniversity of ValenciaValenciaSpain
- University Institute of Biotechnology and Biomedicine (BIOTECMED)University of ValenciaValenciaSpain
| | - Lucia Hipólito
- Department of Pharmacy and Pharmaceutical Technology and ParasitologyUniversity of ValenciaValenciaSpain
- University Institute of Biotechnology and Biomedicine (BIOTECMED)University of ValenciaValenciaSpain
| | - Fernando Ezquer
- Center for Regenerative Medicine, Faculty of MedicineClínica Alemana‐Universidad del DesarrolloSantiagoChile
- Research Center for the Development of Novel Therapeutic Alternatives for Alcohol Use DisordersSantiagoChile
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3
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Zhang J, Song C, Dai J, Li L, Yang X, Chen Z. Mechanism of opioid addiction and its intervention therapy: Focusing on the reward circuitry and mu‐opioid receptor. MedComm (Beijing) 2022; 3:e148. [PMID: 35774845 PMCID: PMC9218544 DOI: 10.1002/mco2.148] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Revised: 05/03/2022] [Accepted: 05/07/2022] [Indexed: 11/09/2022] Open
Affiliation(s)
- Jia‐Jia Zhang
- National Translational Science Center for Molecular Medicine & Department of Cell Biology The Fourth Military Medical University Xi'an China
| | - Chang‐Geng Song
- Department of Neurology Xijing Hospital The Fourth Military Medical University Xi'an China
| | - Ji‐Min Dai
- Department of Hepatobiliary Surgery Xijing Hospital The Fourth Military Medical University Xi'an China
| | - Ling Li
- National Translational Science Center for Molecular Medicine & Department of Cell Biology The Fourth Military Medical University Xi'an China
| | - Xiang‐Min Yang
- National Translational Science Center for Molecular Medicine & Department of Cell Biology The Fourth Military Medical University Xi'an China
| | - Zhi‐Nan Chen
- National Translational Science Center for Molecular Medicine & Department of Cell Biology The Fourth Military Medical University Xi'an China
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Brown TG, Xu J, Hurd YL, Pan YX. Dysregulated expression of the alternatively spliced variant mRNAs of the mu opioid receptor gene, OPRM1, in the medial prefrontal cortex of male human heroin abusers and heroin self-administering male rats. J Neurosci Res 2022; 100:35-47. [PMID: 32506472 PMCID: PMC8143898 DOI: 10.1002/jnr.24640] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 04/20/2020] [Accepted: 04/27/2020] [Indexed: 11/08/2022]
Abstract
Heroin, a mu agonist, acts through the mu opioid receptor. The mu opioid receptor gene, OPRM1, undergoes extensive alternative splicing, creating an array of splice variants that are conserved from rodent to humans. Increasing evidence suggests that these OPRM1 splice variants are pharmacologically important in mediating various actions of mu opioids, including analgesia, tolerance, physical dependence, rewarding behavior, as well as addiction. In the present study, we examine expression of the OPRM1 splice variant mRNAs in the medial prefrontal cortex (mPFC), one of the major brain regions involved in decision-making and drug-seeking behaviors, of male human heroin abusers and male rats that developed stable heroin-seeking behavior using an intravenous heroin self-administration (SA) model. The results show similar expression profiles among multiple OPRM1 splice variants in both human control subjects and saline control rats, illustrating conservation of OPRM1 alternative splicing from rodent to humans. Moreover, the expressions of several OPRM1 splice variant mRNAs were dysregulated in the postmortem mPFCs from heroin abusers compared to the control subjects. Similar patterns were observed in the rat heroin SA model. These findings suggest potential roles of the OPRM1 splice variants in heroin addiction that could be mechanistically explored using the rat heroin SA model.
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Affiliation(s)
- Taylor G Brown
- Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Jin Xu
- Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Yasmin L Hurd
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ying-Xian Pan
- Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
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5
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G-Protein-Coupled Estrogen Receptor (GPER) in the Rostral Ventromedial Medulla Is Essential for Mobilizing Descending Inhibition of Itch. J Neurosci 2021; 41:7727-7741. [PMID: 34349001 DOI: 10.1523/jneurosci.2592-20.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 07/19/2021] [Accepted: 07/28/2021] [Indexed: 11/21/2022] Open
Abstract
Chronic itch is a troublesome condition and often difficult to cure. Emerging evidence suggests that the periaqueductal gray (PAG)-rostral ventromedial medulla (RVM) pathway may play an important role in the regulation of itch, but the cellular organization and molecular mechanisms remain incompletely understood. Here, we report that a group of RVM neurons distinctively express the G-protein-coupled estrogen receptor (GPER), which mediates descending inhibition of itch. We found that GPER+ neurons in the RVM were activated in chronic itch conditions in rats and mice. Selective ablation or chemogenetic suppression of RVM GPER+ neurons resulted in mechanical alloknesis and increased scratching in response to pruritogens, whereas chemogenetic activation of GPER+ neurons abrogated itch responses, indicating that GPER+ neurons are antipruritic. Moreover, GPER-deficient mice and rats of either sex exhibited hypersensitivity to mechanical and chemical itch, a phenotype reversible by the µ type opioid receptor (MOR) antagonism. Additionally, significant MOR phosphorylation in the RVM was detected in chronic itch models in wild-type but not in GPER-/- rats. Therefore, GPER not only identifies a population of medullary antipruritic neurons but may also determine the descending antipruritic tone through regulating µ opioid signaling.SIGNIFICANCE STATEMENT Therapeutic options for itch are limited because of an as yet incomplete understanding of the mechanisms of itch processing. Our data have provided novel insights into the cellular organization and molecular mechanisms of descending regulation of itch in normal and pathologic conditions. GPER+ neurons (largely GABAergic) in the RVM are antipruritic neurons under tonic opioidergic inhibition, activation of GPER promotes phosphorylation of MOR and disinhibition of the antipruritic GPER+ neurons from inhibitory opioidergic inputs, and failure to mobilize GPER+ neurons may result in the exacerbation of itch. Our data also illuminate on some of the outstanding questions in the field, such as the mechanisms underlying sex bias in itch, pain, and opioid analgesia and the paradoxical effects of morphine on pain and itch.
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Chakrabarti S, Liu NJ, Gintzler AR. Relevance of Mu-Opioid Receptor Splice Variants and Plasticity of Their Signaling Sequelae to Opioid Analgesic Tolerance. Cell Mol Neurobiol 2021; 41:855-862. [PMID: 32804312 DOI: 10.1007/s10571-020-00934-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 08/01/2020] [Indexed: 10/23/2022]
Abstract
Opioid dose escalation to effectively control pain is often linked to the current prescription opioid abuse epidemic. This creates social as well as medical imperatives to better understand the mechanistic underpinnings of opioid tolerance to develop interventions that minimize it, thereby maximizing the analgesic effectiveness of opioids. Profound opioid analgesic tolerance can be observed in the absence of mu-opioid receptor (MOR) downregulation, aggregate MOR G protein uncoupling, and MOR desensitization, in the absence of impaired G protein coupled receptor kinase phosphorylation, arrestin binding, or endocytosis. Thus, we have explored alternative biochemical sequelae that might better account for opioid analgesic tolerance. Our findings indicate that substantial plasticity among upstream and downstream components of opioid receptor signaling and the emergence of alternative signaling pathways are major contributors to opioid analgesic tolerance. An exemplar of this plasticity is our findings that chronic morphine upregulates the MOR variants MOR-1B2 and MOR-1C1 and phosphorylation of their C-terminal sites not present in MOR-1, events causally associated with the chronic morphine-induced shift in MOR G protein coupling from predominantly Gi/Go inhibitory to Gs-stimulatory adenylyl cyclase signaling. The unique feature(s) of these variants that underlies their susceptibility to adapting to chronic morphine by altering the nature of their G protein coupling reveals the richness and pliability of MOR signaling that is enabled by generating a wide diversity of MOR variants. Furthermore, given differential anatomical expression patterns of MOR variants, MOR splice variant-dependent adaptations to chronic morphine could enable mechanistic underpinnings of tolerance and dependence that are CNS region- and cell-specific.
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Affiliation(s)
- Sumita Chakrabarti
- Department Obstetrics and Gynecology, SUNY Downstate Health Sciences University, 450 Clarkson Ave, Brooklyn, NY, 11203, USA
| | - Nai-Jiang Liu
- Department Obstetrics and Gynecology, SUNY Downstate Health Sciences University, 450 Clarkson Ave, Brooklyn, NY, 11203, USA
| | - Alan R Gintzler
- Department Obstetrics and Gynecology, SUNY Downstate Health Sciences University, 450 Clarkson Ave, Brooklyn, NY, 11203, USA.
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Sex dependent alteration of epigenetic marks after chronic morphine treatment in mice organs. Food Chem Toxicol 2021; 152:112200. [PMID: 33891991 DOI: 10.1016/j.fct.2021.112200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/20/2021] [Accepted: 04/07/2021] [Indexed: 11/23/2022]
Abstract
Epigenetic marks may be also affected by several factors, such as age, lifestyle, early life experiences and exposure to chemicals or drugs, such as opioids. Previous studies have focused on how morphine epigenetically regulates different regions of the brain that are implicated in tolerance, dependence and other psychiatric disorders more related to the physio-pathological effects of opioids. Nevertheless, a significant knowledge gap remains regarding the effect of chronic treatment on other organs and biological systems. Therefore, the aim of this work is to increase our knowledge about the impact of chronic morphine exposure on DNA methylation and histone modification levels in each of the organs of male and female model mice in vivo. Our results reveal, for the first time, that chronic morphine treatment induced changes in DNA methylation/hydroxymethylation and histone modification in-vivo at the systemic level, revealing a potential physiological effect on the regulation of gene expression. Notably, morphine-induced epigenetic modification occurs in a sex-dependent manner, revealing the existence of different underlying mechanisms of epigenetic modification in male and female mice.
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8
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Lutz PE, Almeida D, Filliol D, Jollant F, Kieffer BL, Turecki G. Increased functional coupling of the mu opioid receptor in the anterior insula of depressed individuals. Neuropsychopharmacology 2021; 46:920-927. [PMID: 33531622 PMCID: PMC8115105 DOI: 10.1038/s41386-021-00974-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 01/14/2021] [Indexed: 12/20/2022]
Abstract
The mu opioid receptor (MOR) is a G protein-coupled receptor that plays an essential role in reward and hedonic processes, and that has been implicated in disorders such as depression and addiction. Over the last decade, several brain imaging studies in depressed patients have consistently found that dysregulation of MOR function occurs in particular in the anterior insular cortex, an important brain site for the perception of internal states and emotional regulation. To investigate molecular mechanisms that may underlie these effects, here we assessed genetic polymorphisms, expression, and functional G-protein coupling of MOR in a large post-mortem cohort (N = 95) composed of depressed individuals who died by suicide, and healthy controls. Results indicated that depression, but not comorbid substance use disorder or acute opiate consumption, was associated with increased MOR activity. This effect was partly explained by a specific increase in expression of the inhibitory alpha G-protein subunit GNAI2. Consistent with previous neuroimaging studies, our findings support the notion that enhanced endogenous opioidergic tone in the anterior insula may buffer negative affective states in depressed individuals, a mechanism that could potentially contribute to the antidepressant efficacy of emerging opioid-based medications.
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Affiliation(s)
- Pierre-Eric Lutz
- McGill Group for Suicide Studies, Douglas Mental Health Research Centre, McGill University, 6875 LaSalle Boulevard, Verdun, Montréal, QC, Canada. .,Centre National de la Recherche Scientifique, Université de Strasbourg, Fédération de Médecine Translationnelle de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives UPR3212, Strasbourg, France.
| | - Daniel Almeida
- grid.14709.3b0000 0004 1936 8649McGill Group for Suicide Studies, Douglas Mental Health Research Centre, McGill University, 6875 LaSalle Boulevard, Verdun, Montréal, QC Canada
| | - Dominique Filliol
- grid.420255.40000 0004 0638 2716Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire, INSERM U-964, CNRS UMR-7104, Université de Strasbourg, Illkirch, France
| | - Fabrice Jollant
- grid.14709.3b0000 0004 1936 8649McGill Group for Suicide Studies, Douglas Mental Health Research Centre, McGill University, 6875 LaSalle Boulevard, Verdun, Montréal, QC Canada ,grid.508487.60000 0004 7885 7602Université de Paris, Paris, France ,grid.411165.60000 0004 0593 8241CHU Nîmes, Nîmes, France ,Present Address: Clinique des Maladies Mentales et de l’Encéphale (CMME), CH Sainte-Anne, GHU Paris, Psychiatrie et Neurosciences, Paris, France
| | - Brigitte L. Kieffer
- grid.420255.40000 0004 0638 2716Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire, INSERM U-964, CNRS UMR-7104, Université de Strasbourg, Illkirch, France ,grid.14709.3b0000 0004 1936 8649Douglas Mental Health Research Centre, Department of Psychiatry, McGill University, Montréal, QC H4H 1R3 Canada ,grid.412220.70000 0001 2177 138XPresent Address: INSERM U1114, Department of Psychiatry, University Hospital of Strasbourg, Strasbourg, France
| | - Gustavo Turecki
- McGill Group for Suicide Studies, Douglas Mental Health Research Centre, McGill University, 6875 LaSalle Boulevard, Verdun, Montréal, QC, Canada.
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Islam A, Rahman MA, Brenner MB, Moore A, Kellmyer A, Buechler HM, DiGiorgio F, Verchio VR, McCracken L, Sumi M, Hartley R, Lizza JR, Moura-Letts G, Fischer BD, Keck TM. Abuse Liability, Anti-Nociceptive, and Discriminative Stimulus Properties of IBNtxA. ACS Pharmacol Transl Sci 2020; 3:907-920. [DOI: 10.1021/acsptsci.0c00066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Bradford D. Fischer
- Cooper Medical School of Rowan University, 401 Broadway, Camden, New Jersey 08103, United States
| | - Thomas M. Keck
- Cooper Medical School of Rowan University, 401 Broadway, Camden, New Jersey 08103, United States
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Narayan A, Hunkele A, Xu J, Bassoni DL, Pasternak GW, Pan YX. Mu Opioids Induce Biased Signaling at the Full-Length Seven Transmembrane C-Terminal Splice Variants of the mu Opioid Receptor Gene, Oprm1. Cell Mol Neurobiol 2020; 41:1059-1074. [PMID: 33033993 DOI: 10.1007/s10571-020-00973-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Accepted: 09/23/2020] [Indexed: 01/06/2023]
Abstract
The biased signaling has been extensively studied in the original mu opioid receptor (MOR-1), particularly through G protein and β-arrestin2 signaling pathways. The concept that the G protein pathway is often linked to the therapeutic effect of the drug, while the β-arrestin pathway is associated to the side effects has been proposed to develop biased analgesic compounds with limited side-effects associated with traditional opiates. The mu opioid receptor gene, OPRM1, undergoes extensive alternative pre-mRNA splicing, generating multiple splice variants or isoforms that are conserved from rodent to human. One type of the Oprm1 splice variants are the full-length 7 transmembrane (7TM) C-terminal splice variants, which have identical receptor structures including entire binding pocket, but contain a different intracellular C-terminal tail resulted from 3' alternative splicing. Increasing evidence suggest that these full-length 7TM C-terminal variants play important roles in mu opioid pharmacology, raising questions regarding biased signaling at these multiple C-terminal variants. In the present study, we investigated the effect of different C-terminal variants on mu agonist-induced G protein coupling, β-arrestin2 recruitment, and ultimately, signaling bias. We found that mu agonists produced marked differences in G protein activation and β-arrestin2 recruitment among various C-terminal variants, leading to biased signaling at various level. Particularly, MOR-1O, an exon 7-associated variant, showed greater β-arrestin2 bias for most mu agonists than MOR-1, an exon 4-associated variant. Biased signaling of G protein-coupled receptors has been defined by evidences that different agonists can produce divergent signaling transduction pathways through a single receptor. Our findings that a single mu agonist can induce differential signaling through multiple 7TM splice variants provide a new perspective on biased signaling at least for Oprm1, which perhaps is important for our understanding of the complex mu opioid actions in vivo where all the 7TM splice variants co-exist.
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Affiliation(s)
- Ankita Narayan
- Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY, 10065, USA
| | - Amanda Hunkele
- Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY, 10065, USA
| | - Jin Xu
- Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY, 10065, USA
| | | | - Gavril W Pasternak
- Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY, 10065, USA
| | - Ying-Xian Pan
- Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY, 10065, USA.
- Department of Anesthesiology, Rutgers New Jersey Medical School, 185 South Orange Avenue, Newark, NJ, 07103, USA.
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Fattore L, Marti M, Mostallino R, Castelli MP. Sex and Gender Differences in the Effects of Novel Psychoactive Substances. Brain Sci 2020; 10:brainsci10090606. [PMID: 32899299 PMCID: PMC7564810 DOI: 10.3390/brainsci10090606] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/28/2020] [Accepted: 08/31/2020] [Indexed: 12/12/2022] Open
Abstract
Sex and gender deeply affect the subjective effects and pharmaco-toxicological responses to drugs. Men are more likely than women to use almost all types of illicit drugs and to present to emergency departments for serious or fatal intoxications. However, women are just as likely as men to develop substance use disorders, and may be more susceptible to craving and relapse. Clinical and preclinical studies have shown important differences between males and females after administration of “classic” drugs of abuse (e.g., Δ9-tetrahydrocannabinol (THC), morphine, cocaine). This scenario has become enormously complicated in the last decade with the overbearing appearance of the new psychoactive substances (NPS) that have emerged as alternatives to regulated drugs. To date, more than 900 NPS have been identified, and can be catalogued in different pharmacological categories including synthetic cannabinoids, synthetic stimulants (cathinones and amphetamine-like), hallucinogenic phenethylamines, synthetic opioids (fentanyls and non-fentanyls), new benzodiazepines and dissociative anesthetics (i.e., methoxetamine and phencyclidine-derivatives). This work collects the little knowledge reached so far on the effects of NPS in male and female animal and human subjects, highlighting how much sex and gender differences in the effects of NPS has yet to be studied and understood.
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Affiliation(s)
- Liana Fattore
- Institute of Neuroscience-Cagliari, National Research Council (CNR), Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
- Correspondence:
| | - Matteo Marti
- Department of Morphology, Surgery and Experimental Medicine, Section of Legal Medicine and LTTA Center, University of Ferrara, 44121 Ferrara, Italy;
- Department of Anti-Drug Policies, Collaborative Center for the Italian National Early Warning System, Presidency of the Council of Ministers, 00187 Rome, Italy
| | - Rafaela Mostallino
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy; (R.M.); (M.P.C.)
| | - Maria Paola Castelli
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy; (R.M.); (M.P.C.)
- National Institute of Neuroscience (INN), University of Cagliari, 09124 Cagliari, Italy
- Center of Excellence “Neurobiology of Addiction”, University of Cagliari, 09124 Cagliari, Italy
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Yang BZ, Zhou H, Cheng Z, Kranzler HR, Gelernter J. Genomewide Gene-by-Sex Interaction Scans Identify ADGRV1 for Sex Differences in Opioid Dependent African Americans. Sci Rep 2019; 9:18070. [PMID: 31792237 PMCID: PMC6889277 DOI: 10.1038/s41598-019-53560-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 10/31/2019] [Indexed: 12/17/2022] Open
Abstract
Sex differences in opioid dependence (OD) are genetically influenced. We conducted genomewide gene-by-sex interaction scans for the DSM-IV diagnosis of OD in 8,387 African-American (AA) or European-American subjects (43.6% women; 4,715 OD subjects). Among AAs, 9 SNPs were genome-wide significant at ADGRV1 (adhesion G-protein-coupled receptor V1, lead-SNP rs2366929*(C/T), p = 1.5 × 10-9) for sex-different risk of OD, with the rs2366929*C-allele increasing OD risk only for men. The top co-expressions in brain were between ADGRV1 and GRIK2 in substantia nigra and medullary inferior olivary nucleus, and between ADGRV1 and EFHC2 in frontal cortex and putamen. Significant sex-differential ADGRV1 expression from GTEx was detected in breast (Bonferroni-corrected-p < 0.002) and in heart (p < 0.0125), with nominal significance identified in brain, thyroid, lung, and stomach (p < 0.05). ADGRV1 co-expression and disease-enrichment analysis identifying the top 10 diseases showed strikingly sexually dimorphic risks. The enrichment and transcriptome analyses provided convergent support that ADGRV1 exerts a sex-different effect on OD risk. This is the first study to identify genetic variants contributing to sex differences in OD. It shows that ADGRV1 contributes to OD risk only in AA men, a finding that warrants further study.
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Affiliation(s)
- Bao-Zhu Yang
- Yale University School of Medicine, Department of Psychiatry, New Haven, CT, USA
- VA Connecticut Healthcare System, Department of Psychiatry, West Haven, CT, USA
| | - Hang Zhou
- Yale University School of Medicine, Department of Psychiatry, New Haven, CT, USA
- VA Connecticut Healthcare System, Department of Psychiatry, West Haven, CT, USA
| | - Zhongshan Cheng
- Yale University School of Medicine, Department of Psychiatry, New Haven, CT, USA
- VA Connecticut Healthcare System, Department of Psychiatry, West Haven, CT, USA
| | - Henry R Kranzler
- University of Pennsylvania Perelman School of Medicine, Department of Psychiatry, Philadelphia, PA, USA
- VISN 4 MIRECC, Crescenz Philadelphia VAMC, Philadelphia, PA, USA
| | - Joel Gelernter
- Yale University School of Medicine, Department of Psychiatry, New Haven, CT, USA.
- VA Connecticut Healthcare System, Department of Psychiatry, West Haven, CT, USA.
- Yale University School of Medicine, Departments of Genetics and Neuroscience, New Haven, CT, USA.
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Chakrabarti S, Liu NJ, Gintzler AR. Phosphorylation of unique C-terminal sites of the mu-opioid receptor variants 1B2 and 1C1 influences their Gs association following chronic morphine. J Neurochem 2019; 152:449-467. [PMID: 31479519 DOI: 10.1111/jnc.14863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 03/14/2019] [Accepted: 08/11/2019] [Indexed: 11/27/2022]
Abstract
We recently demonstrated in rat spinal cord that a regimen of escalating doses of systemic morphine, analogous to regimens used clinically for chronic pain management, selectively up-regulates the mu-opioid receptor (MOR) splice variants MOR-1B2 and MOR-1C1 mRNA and functional protein. This study investigated the potential relevance of up-regulating MOR-1B2 and MOR-1C1 to the ability of chronic morphine to shift MOR signaling from predominantly Gi /Go inhibitory to Gs stimulatory. Specifically, we tested the hypotheses that chronic morphine induces phosphorylation of carboxyl terminal sites unique to MOR-1B2 and MOR-1C1, and that this phosphorylation is causally related to augmented association of these variants with Gs α. Hypotheses were validated by (i) abolition of the chronic morphine-induced increment in MOR-1C1 and MOR-1B2 association with Gs α by inhibitors of protein kinase A and Casein kinase 2, respectively; (ii) failure of chronic morphine to augment MOR variant Gs α interactions in Chinese hamster ovary cells transiently transfected with either rat MOR-1C1 or MOR-1B2 in which targeted protein kinase A and Casein kinase 2 serine phosphorylation sites, respectively, were mutated to alanine; (iii) abrogation of chronic morphine-induced augmented MOR Gs α association in spinal cord of male rats following intrathecal administration of dicer substrate small interfering RNAs targeting MOR-1B2/MOR-1C1 mRNA. The ability of chronic morphine to not only up-regulate-specific MOR variants but also their carboxyl terminal phosphorylation and consequent augmented association with Gs α may represent a novel component of opioid tolerance mechanisms, suggesting novel potential targets for tolerance abatement.
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Affiliation(s)
- Sumita Chakrabarti
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, New York, USA
| | - Nai-Jiang Liu
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, New York, USA
| | - Alan R Gintzler
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, New York, USA
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Enman NM, Reyes BAS, Shi Y, Valentino RJ, Van Bockstaele EJ. Sex differences in morphine-induced trafficking of mu-opioid and corticotropin-releasing factor receptors in locus coeruleus neurons. Brain Res 2018; 1706:75-85. [PMID: 30391476 DOI: 10.1016/j.brainres.2018.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 10/24/2018] [Accepted: 11/01/2018] [Indexed: 01/18/2023]
Abstract
The locus coeruleus (LC)-norepinephrine (NE) system is a key nucleus in which endogenous opioid and stress systems intersect to regulate the stress response. LC neurons of male rats become sensitized to stress following chronic morphine administration. Whether sex dictates this pattern of opioid-induced plasticity has not been demonstrated. Delineating the neurobiological adaptations produced by chronic opioids will enhance our understanding of stress vulnerability in opioid-dependent individuals, and may reveal how stress negatively impacts addiction recovery. In the present study, the effect of chronic morphine on the subcellular distribution of mu-opioid (MOR) and CRF receptors (CRFR) was investigated in the LC of male and female rats using immunoelectron microscopy. Results showed that placebo-treated females exhibited higher MOR and CRFR cytoplasmic distribution ratio when compared to placebo-treated males. Chronic morphine exposure induced a shift in the distribution of MOR immunogold-silver particles from the plasma membrane to the cytoplasm selectively in male LC neurons. Interestingly, chronic morphine exposure induced CRFR recruitment to the plasma membrane of both male and female LC neurons. These findings provide a potential mechanism by which chronic opioid administration increases stress vulnerability in males and females via an increase in surface availability of CRFR in LC neurons. However, our results also support the notion that cellular adaptations to chronic opioids differ across the sexes as redistribution of MOR following morphine exposure was only observed in male LC neurons.
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Affiliation(s)
- Nicole M Enman
- Department of Pharmacology and Physiology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA.
| | - Beverly A S Reyes
- Department of Pharmacology and Physiology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA.
| | - Yufan Shi
- Department of Pharmacology and Physiology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA
| | - Rita J Valentino
- Department of Anesthesiology and Critical Care, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
| | - Elisabeth J Van Bockstaele
- Department of Pharmacology and Physiology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA.
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16
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Regan PM, Langford TD, Khalili K. Regulation and Functional Implications of Opioid Receptor Splicing in Opioid Pharmacology and HIV Pathogenesis. J Cell Physiol 2016; 231:976-85. [PMID: 26529364 PMCID: PMC4728022 DOI: 10.1002/jcp.25237] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 11/02/2015] [Indexed: 12/18/2022]
Abstract
Despite the identification and characterization of four opioid receptor subtypes and the genes from which they are encoded, pharmacological data does not conform to the predications of a four opioid receptor model. Instead, current studies of opioid pharmacology suggest the existence of additional receptor subtypes; however, no additional opioid receptor subtype has been identified to date. It is now understood that this discrepancy is due to the generation of multiple isoforms of opioid receptor subtypes. While several mechanisms are utilized to generate these isoforms, the primary mechanism involves alternative splicing of the pre-mRNA transcript. Extensive alternative splicing patterns for opioid receptors have since been identified and discrepancies in opioid pharmacology are now partially attributed to variable expression of these isoforms. Recent studies have been successful in characterizing the localization of these isoforms as well as their specificity in ligand binding; however, the regulation of opioid receptor splicing specificity is poorly characterized. Furthermore, the functional significance of individual receptor isoforms and the extent to which opioid- and/or HIV-mediated changes in the opioid receptor isoform profile contributes to altered opioid pharmacology or the well-known physiological role of opioids in the exacerbation of HIV neurocognitive dysfunction is unknown. As such, the current review details constitutive splicing mechanisms as well as the specific architecture of opioid receptor genes, transcripts, and receptors in order to highlight the current understanding of opioid receptor isoforms, potential mechanisms of their regulation and signaling, and their functional significance in both opioid pharmacology and HIV-associated neuropathology.
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Affiliation(s)
- Patrick M. Regan
- Department of Neuroscience and Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - T. Dianne Langford
- Department of Neuroscience and Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Kamel Khalili
- Department of Neuroscience and Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
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Chakrabarti S, Madia PA, Gintzler AR. Selective up-regulation of functional mu-opioid receptor splice variants by chronic opioids. J Neurochem 2016; 136:1119-1130. [PMID: 26718622 DOI: 10.1111/jnc.13519] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 12/15/2015] [Accepted: 12/18/2015] [Indexed: 11/28/2022]
Abstract
We recently reported (Verzillo, et al. J. Neurochem: 130, 790-796, 2014) that chronic systemic morphine selectively up-regulates mRNA encoding two C-terminal μ-opioid receptor (MOR) splice variants, MOR-1C1 and MOR-1B2 (MOR-1B2/-1C1). Given the known disconnects between changes in levels of mRNA and corresponding protein, it is essential to directly demonstrate that chronic opioid treatment elevates functional MOR-1B2/-1C1 protein prior to inferring relevance of these MOR variants to spinal opioid tolerance mechanisms. Accordingly, we investigated the ability of chronic opioid exposure to up-regulate MOR protein in Chinese hamster ovary cells stably transfected with rat MOR variants MOR-1B2, MOR-1C1, or MOR-1 (considered to be the predominant MOR). Findings revealed that chronic treatment with the clinically relevant opioids morphine, oxycodone and hydrocodone substantially up-regulated membrane MOR-1B2/-1C1 protein. This up-regulation was abolished by the protein synthesis inhibitor cycloheximide, eliminating contributions from receptor redistribution. The increment in MOR-1B2/-1C1 protein was paralleled by a significant increment in opioid agonist-stimulated GTPγS-binding (reflective of increased aggregate MOR G protein coupling) indicating that up-regulated MOR-1B2/-1C1 represented functional receptors. Strikingly, these tolerance-associated adaptations of MOR-1B2/-1C1 differed considerably from those of MOR-1. Antithetical regulation of MOR-1B2/-1C1 and MOR-1 by chronic opioids has significant implications for the design of new therapeutic agents to counteract opioid analgesic tolerance and accompanying addiction. Since chronic opioids induce MOR-1B2/-1C1 up-regulation in spinal cord of males, but not females, elucidating cellular compartments and intracellular pathways mediating MOR-1B2/-1C1 up-regulation and defining their unique signaling attributes would enable a precision medicinal approach to pain management and addiction therapy. In the spinal cord of males, but not females, chronic morphine up-regulates mRNA encoding two mu-opioid receptor (MOR) variants, MOR-1B2 and MOR-1C1 (MOR-1B2/-1C1). We now demonstrate that chronic treatment with the clinically relevant opioids morphine, hydrocodone or oxycodone up-regulates MOR-1B2/-1C1 functional protein, which is dependent on de novo protein synthesis. Findings underscore the importance of unique signaling attributes of MOR variants to sexually dimorphic tolerance mechanisms.
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Affiliation(s)
- Sumita Chakrabarti
- Department of Obstetrics and Gynecology, State University of New York, Brooklyn, New York, USA
| | - Priyanka A Madia
- Department of Obstetrics and Gynecology, State University of New York, Brooklyn, New York, USA
| | - Alan R Gintzler
- Department of Obstetrics and Gynecology, State University of New York, Brooklyn, New York, USA
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Abstract
This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 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 (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 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 (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, United States.
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Regan PM, Sariyer IK, Langford TD, Datta PK, Khalili K. Morphine-induced MOR-1X and ASF/SF2 Expressions Are Independent of Transcriptional Regulation: Implications for MOR-1X Signaling. J Cell Physiol 2015; 231:1542-53. [PMID: 26553431 DOI: 10.1002/jcp.25246] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 10/05/2015] [Indexed: 01/13/2023]
Abstract
Recently, multiple μ-opioid receptor (MOR) isoforms have been identified that originate from a single gene, OPRM1; however, both their regulation and their functional significance are poorly characterized. The objectives of this study were to decipher, first, the regulation of alternatively spliced μ-opioid receptor isoforms and the spliceosome components that determine splicing specificity and, second, the signaling pathways utilized by particular isoforms both constitutively and following agonist binding. Our studies demonstrated that the expression of a particular splice variant, MOR-1X, was up-regulated by morphine, and this coincided with an increase in the essential splicing factor ASF/SF2. Structural comparison of this isoform to the prototypical variant MOR-1 revealed that the unique distal portion of the C-terminal domain contains additional phosphorylation sites, whereas functional comparison found distinct signaling differences, particularly in the ERK and p90 RSK pathways. Additionally, MOR-1X expression significantly reduced Bax expression and mitochondrial dehydrogenase activity, suggesting a unique functional consequence for MOR-1X specific signaling. Collectively, these findings suggest that alternative splicing of the MOR is altered by exogenous opioids, such as morphine, and that individual isoforms, such as MOR-1X, mediate unique signal transduction with distinct functional consequence. Furthermore, we have identified for the first time a potential mechanism that involves the essential splicing factor ASF/SF2 through which morphine regulates splicing specificity of the MOR encoding gene, OPRM1.
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Affiliation(s)
- Patrick M Regan
- Department of Neuroscience and Center for Neurovirology, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
| | - Ilker K Sariyer
- Department of Neuroscience and Center for Neurovirology, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
| | - T Dianne Langford
- Department of Neuroscience and Center for Neurovirology, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
| | - Prasun K Datta
- Department of Neuroscience and Center for Neurovirology, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
| | - Kamel Khalili
- Department of Neuroscience and Center for Neurovirology, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
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Vassoler FM, Wright SJ, Byrnes EM. Exposure to opiates in female adolescents alters mu opiate receptor expression and increases the rewarding effects of morphine in future offspring. Neuropharmacology 2015; 103:112-21. [PMID: 26700246 DOI: 10.1016/j.neuropharm.2015.11.026] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/18/2015] [Accepted: 11/25/2015] [Indexed: 12/22/2022]
Abstract
Prescription opiate use and abuse has increased dramatically over the past two decades, including increased use in adolescent populations. Recently, it has been proposed that use during this critical period may affect future offspring even when use is discontinued prior to conception. Here, we utilize a rodent model to examine the effects of adolescent morphine exposure on the reward functioning of the offspring. Female Sprague Dawley rats were administered morphine for 10 days during early adolescence (post-natal day 30-39) using an escalating dosing regimen. Animals then remained drug free until adulthood at which point they were mated with naïve males. Adult offspring (F1 animals) were tested for their response to morphine-induced (0, 1, 2.5, 5, and 10 mg/kg, s.c.) conditioned place preference (CPP) and context-independent morphine-induced sensitization. Naïve littermates were used to examine mu opiate receptor expression in the nucleus accumbens and ventral tegmental area. Results indicate that F1 females whose mothers were exposed to morphine during adolescence (Mor-F1) demonstrate significantly enhanced CPP to the lowest doses of morphine compared with Sal-F1 females. There were no differences in context-independent sensitization between maternal treatment groups. Protein expression analysis showed significantly increased levels of accumbal mu opiate receptor in Mor-F1 offspring and decreased levels in the VTA. Taken together, these findings demonstrate a shift in the dose response curve with regard to the rewarding effects of morphine in Mor-F1 females which may in part be due to altered mu opiate receptor expression in the nucleus accumbens and VTA.
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Affiliation(s)
- Fair M Vassoler
- Department of Biomedical Sciences, Cummings School of Veterinary Medicine, Tufts University, Peabody Pavilion, 200 Westborough Road, Grafton, MA 01536, USA.
| | - Siobhan J Wright
- Department of Biomedical Sciences, Cummings School of Veterinary Medicine, Tufts University, Peabody Pavilion, 200 Westborough Road, Grafton, MA 01536, USA
| | - Elizabeth M Byrnes
- Department of Biomedical Sciences, Cummings School of Veterinary Medicine, Tufts University, Peabody Pavilion, 200 Westborough Road, Grafton, MA 01536, USA
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Kumar A, Liu NJ, Madia PA, Gintzler AR. Contribution of Endogenous Spinal Endomorphin 2 to Intrathecal Opioid Antinociception in Rats Is Agonist Dependent and Sexually Dimorphic. THE JOURNAL OF PAIN 2015; 16:1200-10. [PMID: 26342648 DOI: 10.1016/j.jpain.2015.08.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 08/05/2015] [Accepted: 08/10/2015] [Indexed: 12/16/2022]
Abstract
UNLABELLED Interactions between exogenous and endogenous opioids are not commonly investigated as a basis for sexually dimorphic opioid analgesia. We investigated the influence of spinal endomorphin 2 (EM2), an endogenous mu-opioid receptor (MOR) ligand, on the spinal antinociception produced by intrathecally administered opioids. Activation of spinal MORs facilitated spinal EM2 release. This effect was sexually dimorphic, occurring in males but not in females. Although activational effects of testosterone were required for opioid facilitation of spinal EM2 release in males, the absence of this facilitation in females did not result from either insufficient levels of testosterone or mitigating effects of estrogens. Strikingly, in males, the contribution of spinal EM2 to the analgesia produced by intrathecally applied MOR agonists depended on their analgesic efficacy relative to that of EM2. Spinal EM2 released by the higher efficacy MOR agonist sufentanil diminished sufentanil's analgesic effect, whereas EM2 released by the lower efficacy morphine had the opposite effect on spinal morphine antinociception. Understanding antithetical contributions of endogenous EM2 to intrathecal opioid antinociception not only enlightens the selection of opioid medications for pain management but also helps to explain variable sex dependence of the antinociception produced by different opioids, facilitating the acceptance of sexually dimorphic antinociception as a basic tenet. PERSPECTIVE The male-specific MOR-coupled enhancement of spinal EM2 release implies a parallel ability to harness endogenous EM2 antinociception. The inferred diminished ability of females to utilize the spinal EM2 antinociceptive system could contribute to their greater frequency and severity of chronic pain syndromes.
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Affiliation(s)
- Arjun Kumar
- Department of Obstetrics and Gynecology, State University of New York, Brooklyn, New York
| | - Nai-Jiang Liu
- Department of Obstetrics and Gynecology, State University of New York, Brooklyn, New York
| | - Priyanka A Madia
- Department of Obstetrics and Gynecology, State University of New York, Brooklyn, New York
| | - Alan R Gintzler
- Department of Obstetrics and Gynecology, State University of New York, Brooklyn, New York.
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