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Neugebauer V, Presto P, Yakhnitsa V, Antenucci N, Mendoza B, Ji G. Pain-related cortico-limbic plasticity and opioid signaling. Neuropharmacology 2023; 231:109510. [PMID: 36944393 PMCID: PMC10585936 DOI: 10.1016/j.neuropharm.2023.109510] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 03/15/2023] [Accepted: 03/16/2023] [Indexed: 03/23/2023]
Abstract
Neuroplasticity in cortico-limbic circuits has been implicated in pain persistence and pain modulation in clinical and preclinical studies. The amygdala has emerged as a key player in the emotional-affective dimension of pain and pain modulation. Reciprocal interactions with medial prefrontal cortical regions undergo changes in pain conditions. Other limbic and paralimbic regions have been implicated in pain modulation as well. The cortico-limbic system is rich in opioids and opioid receptors. Preclinical evidence for their pain modulatory effects in different regions of this highly interactive system, potentially opposing functions of different opioid receptors, and knowledge gaps will be described here. There is little information about cell type- and circuit-specific functions of opioid receptor subtypes related to pain processing and pain-related plasticity in the cortico-limbic system. The important role of anterior cingulate cortex (ACC) and amygdala in MOR-dependent analgesia is most well-established, and MOR actions in the mesolimbic system appear to be similar but remain to be determined in mPFC regions other than ACC. Evidence also suggests that KOR signaling generally serves opposing functions whereas DOR signaling in the ACC has similar, if not synergistic effects, to MOR. A unifying picture of pain-related neuronal mechanisms of opioid signaling in different elements of the cortico-limbic circuitry has yet to emerge. This article is part of the Special Issue on "Opioid-induced changes in addiction and pain circuits".
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Affiliation(s)
- Volker Neugebauer
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA; Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX, USA; Garrison Institute on Aging, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
| | - Peyton Presto
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Vadim Yakhnitsa
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Nico Antenucci
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Brianna Mendoza
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Guangchen Ji
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA; Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX, USA
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2
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Casello SM, Flores RJ, Yarur HE, Wang H, Awanyai M, Arenivar MA, Jaime-Lara RB, Bravo-Rivera H, Tejeda HA. Neuropeptide System Regulation of Prefrontal Cortex Circuitry: Implications for Neuropsychiatric Disorders. Front Neural Circuits 2022; 16:796443. [PMID: 35800635 PMCID: PMC9255232 DOI: 10.3389/fncir.2022.796443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 04/27/2022] [Indexed: 01/08/2023] Open
Abstract
Neuropeptides, a diverse class of signaling molecules in the nervous system, modulate various biological effects including membrane excitability, synaptic transmission and synaptogenesis, gene expression, and glial cell architecture and function. To date, most of what is known about neuropeptide action is limited to subcortical brain structures and tissue outside of the central nervous system. Thus, there is a knowledge gap in our understanding of neuropeptide function within cortical circuits. In this review, we provide a comprehensive overview of various families of neuropeptides and their cognate receptors that are expressed in the prefrontal cortex (PFC). Specifically, we highlight dynorphin, enkephalin, corticotropin-releasing factor, cholecystokinin, somatostatin, neuropeptide Y, and vasoactive intestinal peptide. Further, we review the implication of neuropeptide signaling in prefrontal cortical circuit function and use as potential therapeutic targets. Together, this review summarizes established knowledge and highlights unknowns of neuropeptide modulation of neural function underlying various biological effects while offering insights for future research. An increased emphasis in this area of study is necessary to elucidate basic principles of the diverse signaling molecules used in cortical circuits beyond fast excitatory and inhibitory transmitters as well as consider components of neuropeptide action in the PFC as a potential therapeutic target for neurological disorders. Therefore, this review not only sheds light on the importance of cortical neuropeptide studies, but also provides a comprehensive overview of neuropeptide action in the PFC to serve as a roadmap for future studies in this field.
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Affiliation(s)
- Sanne M. Casello
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, United States
| | - Rodolfo J. Flores
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, United States
| | - Hector E. Yarur
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, United States
| | - Huikun Wang
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, United States
| | - Monique Awanyai
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, United States
| | - Miguel A. Arenivar
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, United States
| | - Rosario B. Jaime-Lara
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, United States
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, United States
| | - Hector Bravo-Rivera
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, United States
| | - Hugo A. Tejeda
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, United States
- *Correspondence: Hugo A. Tejeda,
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3
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Sturaro C, Malfacini D, Argentieri M, Djeujo FM, Marzola E, Albanese V, Ruzza C, Guerrini R, Calo’ G, Molinari P. Pharmacology of Kappa Opioid Receptors: Novel Assays and Ligands. Front Pharmacol 2022; 13:873082. [PMID: 35529436 PMCID: PMC9068900 DOI: 10.3389/fphar.2022.873082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
The present study investigated the in vitro pharmacology of the human kappa opioid receptor using multiple assays, including calcium mobilization in cells expressing chimeric G proteins, the dynamic mass redistribution (DMR) label-free assay, and a bioluminescence resonance energy transfer (BRET) assay that allows measurement of receptor interaction with G protein and β-arrestin 2. In all assays, dynorphin A, U-69,593, and [D-Pro10]dyn(1-11)-NH2 behaved as full agonists with the following rank order of potency [D-Pro10]dyn(1-11)-NH2 > dynorphin A ≥ U-69,593. [Dmt1,Tic2]dyn(1-11)-NH2 behaved as a moderate potency pure antagonist in the kappa-β-arrestin 2 interaction assay and as low efficacy partial agonist in the other assays. Norbinaltorphimine acted as a highly potent and pure antagonist in all assays except kappa-G protein interaction, where it displayed efficacy as an inverse agonist. The pharmacological actions of novel kappa ligands, namely the dynorphin A tetrameric derivative PWT2-Dyn A and the palmitoylated derivative Dyn A-palmitic, were also investigated. PWT2-Dyn A and Dyn A-palmitic mimicked dynorphin A effects in all assays showing similar maximal effects but 3–10 fold lower potency. In conclusion, in the present study, multiple in vitro assays for the kappa receptor have been set up and pharmacologically validated. In addition, PWT2-Dyn A and Dyn A-palmitic were characterized as potent full agonists; these compounds are worthy of further investigation in vivo for those conditions in which the activation of the kappa opioid receptor elicits beneficial effects e.g. pain and pruritus.
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Affiliation(s)
- Chiara Sturaro
- Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Ferrara, Italy
| | - Davide Malfacini
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
- *Correspondence: Davide Malfacini,
| | - Michela Argentieri
- Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Ferrara, Italy
| | - Francine M. Djeujo
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Erika Marzola
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Ferrara, Italy
| | - Valentina Albanese
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Ferrara, Italy
| | - Chiara Ruzza
- Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Ferrara, Italy
- Technopole of Ferrara, LTTA Laboratory for Advanced Therapies, Ferrara, Italy
| | - Remo Guerrini
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Ferrara, Italy
- Technopole of Ferrara, LTTA Laboratory for Advanced Therapies, Ferrara, Italy
| | - Girolamo Calo’
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Paola Molinari
- National Center for Drug Research and Evaluation, National Institute of Health, Rome, Italy
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4
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Addiction and the cerebellum with a focus on actions of opioid receptors. Neurosci Biobehav Rev 2021; 131:229-247. [PMID: 34555385 DOI: 10.1016/j.neubiorev.2021.09.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 08/12/2021] [Accepted: 09/12/2021] [Indexed: 01/19/2023]
Abstract
Increasing evidence suggests that the cerebellum could play a role in the higher cognitive processes involved in addiction as the cerebellum contains anatomical and functional pathways to circuitry controlling motivation and saliency. In addition, the cerebellum exhibits a widespread presence of receptors, including opioid receptors which are known to play a prominent role in synaptic and circuit mechanisms of plasticity associated with drug use and development of addiction to opioids and other drugs of abuse. Further, the presence of perineural nets (PNNs) in the cerebellum which contain proteins known to alter synaptic plasticity could contribute to addiction. The role the cerebellum plays in processes of addiction is likely complex, and could depend on the particular drug of abuse, the pattern of use, and the stage of the user within the addiction cycle. In this review, we discuss functional and structural modifications shown to be produced in the cerebellum by opioids that exhibit dependency-inducing properties which provide support for the conclusion that the cerebellum plays a role in addiction.
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5
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Tejeda HA, Wang H, Flores RJ, Yarur HE. Dynorphin/Kappa-Opioid Receptor System Modulation of Cortical Circuitry. Handb Exp Pharmacol 2021; 271:223-253. [PMID: 33580392 DOI: 10.1007/164_2021_440] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cortical circuits control a plethora of behaviors, from sensation to cognition. The cortex is enriched with neuropeptides and receptors that play a role in information processing, including opioid peptides and their cognate receptors. The dynorphin (DYN)/kappa-opioid receptor (KOR) system has been implicated in the processing of sensory and motivationally-charged emotional information and is highly expressed in cortical circuits. This is important as dysregulation of DYN/KOR signaling in limbic and cortical circuits has been implicated in promoting negative affect and cognitive deficits in various neuropsychiatric disorders. However, research investigating the role of this system in controlling cortical circuits and computations therein is limited. Here, we review the (1) basic anatomy of cortical circuits, (2) anatomical architecture of the cortical DYN/KOR system, (3) functional regulation of cortical synaptic transmission and microcircuit function by the DYN/KOR system, (4) regulation of behavior by the cortical DYN/KOR system, (5) implications for the DYN/KOR system for human health and disease, and (6) future directions and unanswered questions for the field. Further work elucidating the role of the DYN/KOR system in controlling cortical information processing and associated behaviors will be of importance to increasing our understanding of principles underlying neuropeptide modulation of cortical circuits, mechanisms underlying sensation and perception, motivated and emotional behavior, and cognition. Increased emphasis in this area of study will also aid in the identification of novel ways to target the DYN/KOR system to treat neuropsychiatric disorders.
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Affiliation(s)
- Hugo A Tejeda
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA.
| | - Huikun Wang
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Rodolfo J Flores
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Hector E Yarur
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
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6
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Bertalan É, Lešnik S, Bren U, Bondar AN. Protein-water hydrogen-bond networks of G protein-coupled receptors: Graph-based analyses of static structures and molecular dynamics. J Struct Biol 2020; 212:107634. [DOI: 10.1016/j.jsb.2020.107634] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 09/06/2020] [Accepted: 09/24/2020] [Indexed: 12/15/2022]
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7
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McKendrick G, Graziane NM. Drug-Induced Conditioned Place Preference and Its Practical Use in Substance Use Disorder Research. Front Behav Neurosci 2020; 14:582147. [PMID: 33132862 PMCID: PMC7550834 DOI: 10.3389/fnbeh.2020.582147] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 09/02/2020] [Indexed: 12/25/2022] Open
Abstract
The conditioned place preference (CPP) paradigm is a well-established model utilized to study the role of context associations in reward-related behaviors, including both natural rewards and drugs of abuse. In this review article, we discuss the basic history, various uses, and considerations that are tied to this technique. There are many potential takeaway implications of this model, including negative affective states, conditioned drug effects, memory, and motivation, which are all considered here. We also discuss the neurobiology of CPP including relevant brain regions, molecular signaling cascades, and neuromodulatory systems. We further examine some of our prior findings and how they integrate CPP with self-administration paradigms. Overall, by describing the fundamentals of CPP, findings from the past few decades, and implications of using CPP as a research paradigm, we have endeavored to support the case that the CPP method is specifically advantageous for studying the role of a form of Pavlovian learning that associates drug use with the surrounding environment.
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Affiliation(s)
- Greer McKendrick
- Neuroscience Graduate Program, Penn State College of Medicine, Hershey, PA, United States.,Department of Anesthesiology and Perioperative Medicine, Penn State College of Medicine, Hershey, PA, United States
| | - Nicholas M Graziane
- Departments of Anesthesiology and Perioperative Medicine and Pharmacology, Penn State College of Medicine, Hershey, PA, United States
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8
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Opioid system modulation of cognitive affective bias: implications for the treatment of mood disorders. Behav Pharmacol 2020; 31:122-135. [DOI: 10.1097/fbp.0000000000000559] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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9
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Fluegge K. A model of lipid dysregulation and altered nutrient status in Alzheimer's disease. ALZHEIMER'S & DEMENTIA (NEW YORK, N. Y.) 2019; 5:139-145. [PMID: 31065583 PMCID: PMC6495090 DOI: 10.1016/j.trci.2019.03.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
INTRODUCTION Dysregulated lipid metabolism and nutrient status are thought to play a role in the pathophysiology of Alzheimer's disease (AD). However, the precise involvement is not well understood, and it remains unclear exactly how such dysregulated lipid metabolism and altered nutrient status, especially changes in phosphatidylcholine, B12, and folate, are connected to the hallmark pathology in AD (i.e., amyloidogenesis). METHODS We have postulated that genetic susceptibility (i.e., APOE ε4/ε4) to environmental exposure to emissions of nitrous oxide (N2O) could underlie the onset of AD and its early neuropsychiatric correlates. RESULTS AND DISCUSSION The current theoretical editorial describes, using clinical, preclinical, and in vitro evidences, how this model contributes not only to amyloidogenesis but also other nonopioid effects, specifically altered lipid metabolism, depletion of vitamin B12, and disruption of the folate-mediated one carbon metabolic pathway.
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Affiliation(s)
- Keith Fluegge
- Institute of Health and Environmental Research, Columbus OH 43220
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10
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de Oliveira PG, Ramos MLS, Amaro AJ, Dias RA, Vieira SI. G i/o-Protein Coupled Receptors in the Aging Brain. Front Aging Neurosci 2019; 11:89. [PMID: 31105551 PMCID: PMC6492497 DOI: 10.3389/fnagi.2019.00089] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 04/03/2019] [Indexed: 12/18/2022] Open
Abstract
Cells translate extracellular signals to regulate processes such as differentiation, metabolism and proliferation, via transmembranar receptors. G protein-coupled receptors (GPCRs) belong to the largest family of transmembrane receptors, with over 800 members in the human species. Given the variety of key physiological functions regulated by GPCRs, these are main targets of existing drugs. During normal aging, alterations in the expression and activity of GPCRs have been observed. The central nervous system (CNS) is particularly affected by these alterations, which results in decreased brain functions, impaired neuroregeneration, and increased vulnerability to neuropathologies, such as Alzheimer's and Parkinson diseases. GPCRs signal via heterotrimeric G proteins, such as Go, the most abundant heterotrimeric G protein in CNS. We here review age-induced effects of GPCR signaling via the Gi/o subfamily at the CNS. During the aging process, a reduction in protein density is observed for almost half of the Gi/o-coupled GPCRs, particularly in age-vulnerable regions such as the frontal cortex, hippocampus, substantia nigra and striatum. Gi/o levels also tend to decrease with aging, particularly in regions such as the frontal cortex. Alterations in the expression and activity of GPCRs and coupled G proteins result from altered proteostasis, peroxidation of membranar lipids and age-associated neuronal degeneration and death, and have impact on aging hallmarks and age-related neuropathologies. Further, due to oligomerization of GPCRs at the membrane and their cooperative signaling, down-regulation of a specific Gi/o-coupled GPCR may affect signaling and drug targeting of other types/subtypes of GPCRs with which it dimerizes. Gi/o-coupled GPCRs receptorsomes are thus the focus of more effective therapeutic drugs aiming to prevent or revert the decline in brain functions and increased risk of neuropathologies at advanced ages.
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Affiliation(s)
- Patrícia G de Oliveira
- Department of Medical Sciences, Institute of Biomedicine (iBiMED) and The Discovery CTR, Universidade de Aveiro, Aveiro, Portugal
| | - Marta L S Ramos
- Department of Medical Sciences, Institute of Biomedicine (iBiMED) and The Discovery CTR, Universidade de Aveiro, Aveiro, Portugal
| | - António J Amaro
- School of Health Sciences (ESSUA), Universidade de Aveiro, Aveiro, Portugal
| | - Roberto A Dias
- Department of Medical Sciences, Institute of Biomedicine (iBiMED) and The Discovery CTR, Universidade de Aveiro, Aveiro, Portugal
| | - Sandra I Vieira
- Department of Medical Sciences, Institute of Biomedicine (iBiMED) and The Discovery CTR, Universidade de Aveiro, Aveiro, Portugal
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Ugur M, Derouiche L, Massotte D. Heteromerization Modulates mu Opioid Receptor Functional Properties in vivo. Front Pharmacol 2018; 9:1240. [PMID: 30483121 PMCID: PMC6244869 DOI: 10.3389/fphar.2018.01240] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 10/11/2018] [Indexed: 01/28/2023] Open
Abstract
Mu opioid receptors modulate a large number of physiological functions. They are in particular involved in the control of pain perception and reward properties. They are also the primary molecular target of opioid drugs and mediate their beneficial analgesic effects, euphoric properties as well as negative side effects such as tolerance and physical dependence. Importantly, mu opioid receptors can physically associate with another receptor to form a novel entity called heteromer that exhibits specific ligand binding, signaling, and trafficking properties. As reviewed here, in vivo physical proximity has now been evidenced for several receptor pairs, subsequent impact of heteromerization on native mu opioid receptor signaling and trafficking identified and a link to behavioral changes established. Selective targeting of heteromers as a tool to modulate mu opioid receptor activity is therefore attracting growing interest and raises hopes for innovative therapeutic strategies.
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Affiliation(s)
- Muzeyyen Ugur
- Centre de la Recherche Nationale Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Lyes Derouiche
- Centre de la Recherche Nationale Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Dominique Massotte
- Centre de la Recherche Nationale Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
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12
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Abstract
The failure of traditional antidepressant medications to adequately target cognitive impairment is associated with poor treatment response, increased risk of relapse, and greater lifetime disability. Opioid receptor antagonists are currently under development as novel therapeutics for major depressive disorder (MDD) and other stress-related illnesses. Although it is known that dysregulation of the endogenous opioid system is observed in patients diagnosed with MDD, the impact of opioidergic neurotransmission on cognitive impairment has not been systematically evaluated. Here we review the literature indicating that opioid manipulations can alter cognitive functions in humans. Furthermore, we detail the preclinical studies that demonstrate the ability of mu-opioid receptor and kappa-opioid receptor ligands to modulate several cognitive processes. Specifically, this review focuses on domains within higher order cognitive processing, including attention and executive functioning, which can differentiate cognitive processes influenced by motivational state.
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13
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Fluegge K. Tau Protein Levels in ADHD. Indian J Clin Biochem 2018; 34:237-239. [PMID: 31093001 DOI: 10.1007/s12291-018-0747-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 03/08/2018] [Indexed: 10/17/2022]
Affiliation(s)
- Keith Fluegge
- Institute of Health and Environmental Research, Cleveland, OH 44118 USA
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14
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Polter AM, Barcomb K, Chen RW, Dingess PM, Graziane NM, Brown TE, Kauer JA. Constitutive activation of kappa opioid receptors at ventral tegmental area inhibitory synapses following acute stress. eLife 2017; 6. [PMID: 28402252 PMCID: PMC5389861 DOI: 10.7554/elife.23785] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/13/2017] [Indexed: 12/14/2022] Open
Abstract
Stressful experiences potently activate kappa opioid receptors (κORs). κORs in the ventral tegmental area regulate multiple aspects of dopaminergic and non-dopaminergic cell function. Here we show that at GABAergic synapses on rat VTA dopamine neurons, a single exposure to a brief cold-water swim stress induces prolonged activation of κORs. This is mediated by activation of the receptor during the stressor followed by a persistent, ligand-independent constitutive activation of the κOR itself. This lasting change in function is not seen at κORs at neighboring excitatory synapses, suggesting distinct time courses and mechanisms of regulation of different subsets of κORs. We also provide evidence that constitutive activity of κORs governs the prolonged reinstatement to cocaine-seeking observed after cold water swim stress. Together, our studies indicate that stress-induced constitutive activation is a novel mechanism of κOR regulation that plays a critical role in reinstatement of drug seeking. DOI:http://dx.doi.org/10.7554/eLife.23785.001 People who are recovering from drug addiction are more vulnerable to cravings and relapse when under stress. This ability of stress to boost drug relapse can also be shown in animals previously exposed to addictive drugs. Rats can learn to press a lever to administer themselves a dose of cocaine and, during withdrawal, rats previously exposed to the drug will press the lever more often if they are stressed. Indeed, just a few minutes of stress is enough to increase lever pressing for several days. Stress and addictive drugs both act on a region of the brain called the ventral tegmental area, or VTA, which is part of the brain’s reward system. Stress indirectly increases the activity of the VTA. It does so by activating a protein on the surface of VTA neurons called the kappa opioid receptor (κOR for short). Previous studies revealed that five minutes of stress increases the activity of κORs in the VTA of rats for five days. Conversely, blocking κORs stopped stressed rats from pressing the lever more often for cocaine. Together, these findings suggested that activating κORs in the VTA contributes to stress-induced drug relapse. Polter et al. have now discovered how stress activates κORs. It turns out that stressful or unpleasant experiences cause the brain to produce a protein called dynorphin, which binds to and activates the κORs. After a stressful event, the receptors are said to have become constitutively active, and blocking this constitutive activity prevents stress from inducing drug-seeking behavior. Polter et al. show that binding of dynorphin is needed to change the shape of the receptors so that they remain active even after dynorphin has detached, but it is likely that other molecules are also involved. This is the first study to show a link between stress, constitutive activation of κORs, and drug relapse. The next step is to work out why this process occurs on only some and not all occasions when the brain releases dynorphin, and why only certain κORs in the VTA respond in this way. Whether constitutive kOR activity drives stress-related craving in people with a history of drug abuse and how to halt these cravings also remain to be determined. DOI:http://dx.doi.org/10.7554/eLife.23785.002
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Affiliation(s)
- Abigail M Polter
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
| | - Kelsey Barcomb
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
| | - Rudy W Chen
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
| | - Paige M Dingess
- Neuroscience Program, University of Wyoming, Laramie, United States.,University of Wyoming, School of Pharmacy, Laramie, United States
| | - Nicholas M Graziane
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
| | - Travis E Brown
- Neuroscience Program, University of Wyoming, Laramie, United States.,University of Wyoming, School of Pharmacy, Laramie, United States
| | - Julie A Kauer
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
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15
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Abstract
This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 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, drug abuse and alcohol, 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, United States.
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Fluegge K. Does environmental exposure to the greenhouse gas, N 2O, contribute to etiological factors in neurodevelopmental disorders? A mini-review of the evidence. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2016; 47:6-18. [PMID: 27566494 DOI: 10.1016/j.etap.2016.08.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Revised: 08/11/2016] [Accepted: 08/13/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND Neurodevelopmental disorders are increasing in prevalence worldwide. Previous work suggests that exposure to the environmental air pollutant and greenhouse gas - nitrous oxide (N2O) - may be an etiological factor in neurodevelopmental disorders through the targeting of several neural correlates. METHODOLOGY While a number of recent systematic reviews have addressed the role of general anesthesia in the surgical setting and neurodevelopmental outcomes, a narrative mini-review was conducted to first define and characterize the relevant variables (i.e., N2O, attention-deficit hyperactivity disorder [ADHD] and autism spectrum disorders [ASD]) and their potential interactions into a coherent, hypothesis-generating work. The narrative mini-review merges basic principles in environmental science, anesthesiology, and psychiatry to more fully develop the novel hypotheses that neurodevelopmental impairment found in conditions like ADHD and ASD may be due to exposure to the increasing air pollutant, N2O. RESULTS The results of the present mini-review indicate that exposure to N2O, even at non-toxic doses, may modulate central neurotransmission and target many neural substrates directly implicated in neurodevelopmental disorders, including the glutamatergic, opioidergic, cholinergic, and dopaminergic systems. Epidemiological studies also indicate that early and repeated exposure to general anesthesia, including N2O, may contribute to later adverse neurodevelopmental outcomes in children. CONCLUSIONS The current evidence and subsequent hypotheses suggest that a renewed interest be taken in the toxicological assessment of environmental N2O exposure using validated biomarkers and psychiatric endpoints. Given the relevance of N2O as a greenhouse gas, societies may also wish to engage in a more robust monitoring and reporting of N2O levels in the environment for climactic benefit as well.
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Affiliation(s)
- Keith Fluegge
- Institute of Health and Environmental Research, Cleveland, OH 44118, USA.
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Gait abnormalities, ADHD, and environmental exposure to nitrous oxide. Psychiatry Res 2016; 242:169-170. [PMID: 27285951 DOI: 10.1016/j.psychres.2016.05.058] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 05/02/2016] [Accepted: 05/31/2016] [Indexed: 11/21/2022]
Abstract
Papadopoulos et al. (2014) investigated gait profiles of children with attention-deficit hyperactivity disorder-combined type (ADHD-CT) compared to typical developing (TD) controls. The authors reported differences in the gait profile of ADHD-CT in the self-selected fast speed category. Additionally, others have proposed a maturational delay hypothesis in gait, demonstrating that gait variability decreases with age in ADHD children. It has been previously suggested that the cognitive impairment seen in conditions like ADHD may result from chronic, environmental exposure to the air pollutant, nitrous oxide (N2O). Exposure to N2O is thought to exert its antinociceptive properties by stimulating release of dynorphin peptides in the central nervous system which act upon kappa opioid receptors (KOR). Opioid-mediated gait abnormalities in ADHD are supported with evidence that prodynorphin mutations in mice lead to cytotoxic levels of dynorphin A (DYN A) and contribute to abnormal gait profiles and gradual loss of motor coordination. Interestingly, constitutive activity of the KOR receptor in rat brain has been recently shown to undergo maturational alterations, suggesting that while altered gait profiles in ADHD may be a function of the enhanced opioidergic activity attributable to chronic exposure to the environmental air pollutant, N2O, age-attenuated constitutive activity of KOR in brain may explain the normalization of these altered gait profiles in older ADHD subjects.
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Fluegge K. Does MeCP2 deficiency in autism confer protection against later development of Alzheimer’s disease? A reply to Oberman and Pascual-Leone (2014). Med Hypotheses 2016; 92:18-20. [DOI: 10.1016/j.mehy.2016.04.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 04/11/2016] [Accepted: 04/13/2016] [Indexed: 02/08/2023]
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