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Wang H, Flores RJ, Yarur HE, Limoges A, Bravo-Rivera H, Casello SM, Loomba N, Enriquez-Traba J, Arenivar M, Wang Q, Ganley R, Ramakrishnan C, Fenno LE, Kim Y, Deisseroth K, Or G, Dong C, Hoon MA, Tian L, Tejeda HA. Prefrontal cortical dynorphin peptidergic transmission constrains threat-driven behavioral and network states. Neuron 2024; 112:2062-2078.e7. [PMID: 38614102 PMCID: PMC11250624 DOI: 10.1016/j.neuron.2024.03.015] [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: 01/18/2023] [Revised: 01/19/2024] [Accepted: 03/13/2024] [Indexed: 04/15/2024]
Abstract
Prefrontal cortical (PFC) circuits provide top-down control of threat reactivity. This includes ventromedial PFC (vmPFC) circuitry, which plays a role in suppressing fear-related behavioral states. Dynorphin (Dyn) has been implicated in mediating negative affect and maladaptive behaviors induced by severe threats and is expressed in limbic circuits, including the vmPFC. However, there is a critical knowledge gap in our understanding of how vmPFC Dyn-expressing neurons and Dyn transmission detect threats and regulate expression of defensive behaviors. Here, we demonstrate that Dyn cells are broadly activated by threats and release Dyn locally in the vmPFC to limit passive defensive behaviors. We further demonstrate that vmPFC Dyn-mediated signaling promotes a switch of vmPFC networks to a fear-related state. In conclusion, we reveal a previously unknown role of vmPFC Dyn neurons and Dyn neuropeptidergic transmission in suppressing defensive behaviors in response to threats via state-driven changes in vmPFC networks.
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Affiliation(s)
- Huikun Wang
- Neuromodulation and Synaptic Integration Unit, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD, USA
| | - Rodolfo J Flores
- Neuromodulation and Synaptic Integration Unit, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD, USA
| | - Hector E Yarur
- Neuromodulation and Synaptic Integration Unit, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD, USA
| | - Aaron Limoges
- Neuromodulation and Synaptic Integration Unit, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD, USA; Columbia University - NIH Graduate Partnership Program, National Institutes of Health, Bethesda, MD, USA
| | - Hector Bravo-Rivera
- Neuromodulation and Synaptic Integration Unit, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD, USA
| | - Sanne M Casello
- Neuromodulation and Synaptic Integration Unit, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD, USA
| | - Niharika Loomba
- Neuromodulation and Synaptic Integration Unit, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD, USA
| | - Juan Enriquez-Traba
- Neuromodulation and Synaptic Integration Unit, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD, USA
| | - Miguel Arenivar
- Neuromodulation and Synaptic Integration Unit, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD, USA; Brown University - NIH Graduate Partnership Program, National Institutes of Health, Bethesda, MD, USA
| | - Queenie Wang
- Neuromodulation and Synaptic Integration Unit, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD, USA
| | - Robert Ganley
- Molecular Genetics Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Charu Ramakrishnan
- Departments of Bioengineering and Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - Lief E Fenno
- Departments of Bioengineering and Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - Yoon Kim
- Departments of Bioengineering and Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - Karl Deisseroth
- Departments of Bioengineering and Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - Grace Or
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CA, USA
| | - Chunyang Dong
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CA, USA
| | - Mark A Hoon
- Molecular Genetics Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Lin Tian
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CA, USA; Max Planck Florida Institute for Neuroscience, Jupiter, FL, USA
| | - Hugo A Tejeda
- Neuromodulation and Synaptic Integration Unit, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD, USA.
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Huang P, Ho CK, Cao D, Inan S, Rawls SM, Li M, Huang B, Pagare PP, Townsend EA, Poklis JL, Halquist MS, Banks M, Zhang Y, Liu-Chen LY. NCP, a dual kappa and mu opioid receptor agonist, is a potent analgesic against inflammatory pain without reinforcing or aversive properties. J Pharmacol Exp Ther 2024; 389:JPET-AR-2023-001870. [PMID: 38409113 PMCID: PMC10949162 DOI: 10.1124/jpet.123.001870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 01/24/2024] [Accepted: 01/30/2024] [Indexed: 02/28/2024] Open
Abstract
While agonists of mu (MOR) and kappa (KOR) opioid receptors have analgesic effects, they produce euphoria and dysphoria, respectively. Other side effects include respiratory depression and addiction for MOR agonists and sedation for KOR agonists. We reported that 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-{[4'-(2'-cyanopyridyl)]carboxamido}cmorphinan (NCP) displayed potent KOR full agonist and MOR partial agonist activities (58%) with 6.5x KOR-over-MOR selectivity in vitro Herein, we characterized pharmacological effects of NCP in rodents. In mice, NCP exerted analgesic effects against inflammatory pain in both the formalin test and the acetic acid writhing test, with A50 values of 47.6 and 14.4 microg/kg (s.c.), respectively. The analgesic effects in the acetic acid writhing test were mediated by the KOR. NCP at doses much higher than those effective in reducing inflammatory pain did not produce antinociception in the hot plate and tail flick tests, inhibit compound 48/80-induced scratching, cause conditioned place aversion (CPA) or preference, impair rotarod performance, inhibit locomotor activity, cause respiratory depression, or precipitate morphine withdrawal. However, NCP (10~100 microg/kg) inhibited gastrointestinal transit with a maximum of ~40% inhibition. In MOR knockout mice, NCP caused CPA, demonstrating that its lack of CPA is due to combined actions on the MOR and KOR. Following s.c. injection, NCP penetrated into the mouse brain. In rats trained to self-administer heroin, NCP (1~320 microg/kg/infusion) did not function as a reinforcer. Thus, NCP produces potent analgesic effects via KOR without side effects except constipation. Therefore, dual full KOR/partial MOR agonists with moderate KOR-over-MOR selectivity may be promising as non-addictive analgesics for inflammatory pain. Significance Statement Developing non-addictive analgesics is crucial for reducing opioid overdose deaths, minimizing drug misuse, and promoting safer pain management practices. Herein, pharmacology of a potential non-addictive analgesic, NCP, is reported. NCP has full KOR agonist / partial MOR agonist activities with a 6.5 x selectivity for KOR over MOR. Unlike MOR agonists, analgesic doses of NCP do not lead to self-administration or respiratory depression. Furthermore, NCP does not produce aversion, hypolocomotion, or motor incoordination, side effects typically associated with KOR activation.
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Affiliation(s)
- Peng Huang
- Temple University Lewis Katz School of Medicine, United States
| | - Conrad K Ho
- Temple University Lewis Katz School of Medicine, United States
| | - Danni Cao
- Temple University Lewis Katz School of Medicine, United States
| | - Saadet Inan
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Lewis Katz School of Medicine, Temple University, United States
| | - Scott M Rawls
- Temple University Lewis Katz School of Medicine, United States
| | - Mengchu Li
- Virginia Commonwealth University School of Pharmacy, United States
| | - Boshi Huang
- Virginia Commonwealth University School of Pharmacy, United States
| | - Piyusha P Pagare
- Virginia Commonwealth University School of Pharmacy, United States
| | | | | | | | - Matthew Banks
- Virginia Commonwealth University School of Medicine, United States
| | - Yan Zhang
- Virginia Commonwealth University School of Pharmacy, United States
| | - Lee-Yuan Liu-Chen
- Center for Substance Abuse Research, Temple University Lewis Katz School of Medicine, United States
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3
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Tache S, Kerr PL, Sirbu C. The Foundational Science of Endogenous Opioids and Their Receptors. ADVANCES IN NEUROBIOLOGY 2024; 35:9-26. [PMID: 38874716 DOI: 10.1007/978-3-031-45493-6_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
The function of endogenous opioids spans from initiating behaviors that are critical for survival, to responding to rapidly changing environmental conditions. A network of interconnected systems throughout the body characterizes the endogenous opioid system (EOS). EOS receptors for beta-endorphin, enkephalin, dynorphin, and endomorphin underpin the diverse functions of the EOS across biological systems. This chapter presents a succinct yet comprehensive summary of the structure of the EOS, EOS receptors, and their relationship to other biological systems.
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Affiliation(s)
- Simona Tache
- Iuliu Haţieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Patrick L Kerr
- West Virginia University School of Medicine-Charleston, Charleston, WV, USA.
| | - Cristian Sirbu
- Center for Cancer Research, Charleston Area Medical Center, Charleston, WV, USA
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4
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Margolis EB, Moulton MG, Lambeth PS, O'Meara MJ. The life and times of endogenous opioid peptides: Updated understanding of synthesis, spatiotemporal dynamics, and the clinical impact in alcohol use disorder. Neuropharmacology 2023; 225:109376. [PMID: 36516892 PMCID: PMC10548835 DOI: 10.1016/j.neuropharm.2022.109376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 12/03/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022]
Abstract
The opioid G-protein coupled receptors (GPCRs) strongly modulate many of the central nervous system structures that contribute to neurological and psychiatric disorders including pain, major depressive disorder, and substance use disorders. To better treat these and related diseases, it is essential to understand the signaling of their endogenous ligands. In this review, we focus on what is known and unknown about the regulation of the over two dozen endogenous peptides with high affinity for one or more of the opioid receptors. We briefly describe which peptides are produced, with a particular focus on the recently proposed possible synthesis pathways for the endomorphins. Next, we describe examples of endogenous opioid peptide expression organization in several neural circuits and how they appear to be released from specific neural compartments that vary across brain regions. We discuss current knowledge regarding the strength of neural activity required to drive endogenous opioid peptide release, clues about how far peptides diffuse from release sites, and their extracellular lifetime after release. Finally, as a translational example, we discuss the mechanisms of action of naltrexone (NTX), which is used clinically to treat alcohol use disorder. NTX is a synthetic morphine analog that non-specifically antagonizes the action of most endogenous opioid peptides developed in the 1960s and FDA approved in the 1980s. We review recent studies clarifying the precise endogenous activity that NTX prevents. Together, the works described here highlight the challenges and opportunities the complex opioid system presents as a therapeutic target.
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Affiliation(s)
- Elyssa B Margolis
- UCSF Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, CA, USA; Neuroscience Graduate Program, University of California, San Francisco, CA, USA.
| | - Madelyn G Moulton
- UCSF Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, CA, USA
| | - Philip S Lambeth
- UCSF Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, CA, USA
| | - Matthew J O'Meara
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, 48109, USA
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5
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Murphy MD, Heller EA. Convergent actions of stress and stimulants via epigenetic regulation of neural circuitry. Trends Neurosci 2022; 45:955-967. [PMID: 36280459 PMCID: PMC9671852 DOI: 10.1016/j.tins.2022.10.001] [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: 07/18/2022] [Revised: 09/21/2022] [Accepted: 10/01/2022] [Indexed: 11/17/2022]
Abstract
The dorsal striatum integrates prior and current information to guide appropriate decision-making. Chronic stress and stimulant exposure interferes with decision-making, and can confer similar cognitive and behavioral inflexibilities. This review examines the literature on acute and chronic regulation of the epigenome by stress and stimulants. Recent evidence suggests that exposures to stress and stimulants share similarities in the manners in which they regulate the dorsal striatum epigenome through DNA methylation, transposable element activity, and histone post-translational modifications. These findings suggest that chronic stress and stimulant exposure leads to the accumulation of epigenetic modifications that impair immediate and future neuron function and activity. Such epigenetic mechanisms represent potential therapeutic targets for ameliorating convergent symptoms of stress and addiction.
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Affiliation(s)
- Michael D Murphy
- Department of Neuroscience, University of Pennsylvania, Philadelphia, PA, 19104, USA; Institute for Translational Medicine and Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104, USA; Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Elizabeth A Heller
- Institute for Translational Medicine and Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104, USA; Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA; Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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6
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In Vitro, In Vivo and In Silico Characterization of a Novel Kappa-Opioid Receptor Antagonist. Pharmaceuticals (Basel) 2022; 15:ph15060680. [PMID: 35745598 PMCID: PMC9229160 DOI: 10.3390/ph15060680] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/20/2022] [Accepted: 05/24/2022] [Indexed: 12/04/2022] Open
Abstract
Kappa-opioid receptor (KOR) antagonists are promising innovative therapeutics for the treatment of the central nervous system (CNS) disorders. The new scaffold opioid ligand, Compound A, was originally found as a mu-opioid receptor (MOR) antagonist but its binding/selectivity and activation profile at the KOR and delta-opioid receptor (DOR) remain elusive. In this study, we present an in vitro, in vivo and in silico characterization of Compound A by revealing this ligand as a KOR antagonist in vitro and in vivo. In the radioligand competitive binding assay, Compound A bound at the human KOR, albeit with moderate affinity, but with increased affinity than to the human MOR and without specific binding at the human DOR, thus displaying a preferential KOR selectivity profile. Following subcutaneous administration in mice, Compound A effectively reverse the antinociceptive effects of the prototypical KOR agonist, U50,488. In silico investigations were carried out to assess the structural determinants responsible for opioid receptor subtype selectivity of Compound A. Molecular docking, molecular dynamics simulations and dynamic pharmacophore (dynophore) generation revealed differences in the stabilization of the chlorophenyl moiety of Compound A within the opioid receptor binding pockets, rationalizing the experimentally determined binding affinity values. This new chemotype bears the potential for favorable ADMET properties and holds promise for chemical optimization toward the development of potential therapeutics.
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7
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Chen C, Huang P, Bland K, Li M, Zhang Y, Liu-Chen LY. Agonist-Promoted Phosphorylation and Internalization of the Kappa Opioid Receptor in Mouse Brains: Lack of Connection With Conditioned Place Aversion. Front Pharmacol 2022; 13:835809. [PMID: 35652052 PMCID: PMC9149264 DOI: 10.3389/fphar.2022.835809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/31/2022] [Indexed: 12/30/2022] Open
Abstract
Selective kappa opioid receptor (KOR) agonists are promising antipruritic agents and analgesics. However, clinical development of KOR agonists has been limited by side effects, including psychotomimetic effects, dysphoria, and sedation, except for nalfurafine, and recently. CR845 (difelikefalin). Activation of KOR elicits G protein- and β-arrestin-mediated signaling. KOR-induced analgesic and antipruritic effects are mediated by G protein signaling. However, different results have been reported as to whether conditioned place aversion (CPA) induced by KOR agonists is mediated by β-arrestin signaling. In this study, we examined in male mice if there was a connection between agonist-promoted CPA and KOR phosphorylation and internalization, proxies for β-arrestin recruitment in vivo using four KOR agonists. Herein, we demonstrated that at doses producing maximal effective analgesic and antiscratch effects, U50,488H, MOM-SalB, and 42B, but not nalfurafine, promoted KOR phosphorylation at T363 and S369 in mouse brains, as detected by immunoblotting with phospho-KOR-specific antibodies. In addition, at doses producing maximal effective analgesic and antiscratch effects, U50,488H, MOM-SalB, and 42B, but not nalfurafine, caused KOR internalization in the ventral tegmental area of a mutant mouse line expressing a fusion protein of KOR conjugated at the C-terminus with tdTomato (KtdT). We have reported previously that the KOR agonists U50,488H and methoxymethyl salvinorin B (MOM-SalB) cause CPA, whereas nalfurafine and 42B do not, at doses effective for analgesic and antiscratch effects. Taken together, these data reveal a lack of connection between agonist-promoted KOR-mediated CPA with agonist-induced KOR phosphorylation and internalization in male mice.
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Affiliation(s)
- Chongguang Chen
- Center for Substance Abuse Research and Department of Neural Sciences, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Peng Huang
- Center for Substance Abuse Research and Department of Neural Sciences, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Kathryn Bland
- Center for Substance Abuse Research and Department of Neural Sciences, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Mengchu Li
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, United States
| | - Yan Zhang
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, United States
| | - Lee-Yuan Liu-Chen
- Center for Substance Abuse Research and Department of Neural Sciences, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
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8
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García-López C, Gómez-Huertas C, Sánchez-González JM, Borroni D, Rodríguez-Calvo-de-Mora M, Romano V, Rachwani-Anil R, Ramos-López JF, Ortiz-Pérez S, Rocha-de-Lossada C. Opioids and Ocular Surface Pathology; A Literature Review of New Treatments Horizons. J Clin Med 2022; 11:jcm11051424. [PMID: 35268515 PMCID: PMC8911328 DOI: 10.3390/jcm11051424] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 03/02/2022] [Accepted: 03/03/2022] [Indexed: 12/01/2022] Open
Abstract
This review discusses the role of opioids in the corneal surface and the different pathways and therapeutic methods of management. A literature review was performed using PubMed database. For the database search, the main searching words “opioid” and “topical opioid treatment” were used with the descriptors “cornea”, “ocular surface”, “neuropathic corneal pain”, “corneal sensitivity” and “naltrexone”; original scientific articles and reviews were included to achieve the purpose of the review. The endogenous opioid system has relevant functions in the organism, and in daily use, opioids are used as painkillers. However, these drugs may be employed for other indications as opioid pathways have a wide spectrum. The corneal surface for topical treatment is easily accessible, hence sparing the side effects of systemic opioids. Instillation of opioid antagonist substances, such as naltrexone, increases corneal healing rates and stimulates the division of corneal epithelium cells without deleterious effects. The natural modulation of endogenous opioids controls different forms of pain, including inflammatory and neuropathic pain, both in the ocular surface and in the central nervous system. There are diverse methods in controlling pain using opioids, especially in refractory forms. This review attempts to collect the literature about corneal surface and opioid pathways to provide an overview image and a possible direction of the news treatments.
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Affiliation(s)
- Celia García-López
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
| | - Carmen Gómez-Huertas
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
| | - José-María Sánchez-González
- Department of Physics of Condensed Matter, Optics Area, University of Seville, 41004 Seville, Spain
- Correspondence: ; Tel.: +34-955-42-08-61
| | - Davide Borroni
- Department of Doctoral Studies, Riga Stradins University, LV-1007 Riga, Latvia;
- Cornea Research Unit, ADVALIA Vision, 20145 Milan, Italy
| | - Marina Rodríguez-Calvo-de-Mora
- Department of Ophthalmology, Hospital Regional Universitario de Málaga, 29010 Málaga, Spain;
- Department of Ophthalmology (Qvision), Vithas Almería, 04120 Almería, Spain
| | - Vito Romano
- Department of Eye and Vision Science Ophthalmology, St Paul’s Eye Hospital, Liverpool L7 8XP, UK;
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L69 3BX, UK
- Department of Medical and Surgical Specialties, Radiological Sciences, and Public Health, Ophthalmology Clinic, University of Brescia, 25121 Brescia, Italy
| | | | - Juan-Francisco Ramos-López
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
| | - Santiago Ortiz-Pérez
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
- Department of Surgery, Faculty of Medicine, University of Granada, 18010 Granada, Spain
| | - Carlos Rocha-de-Lossada
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
- Department of Ophthalmology (Qvision), Vithas Almería, 04120 Almería, Spain
- Department of Ophthalmology, Ceuta Medical Center, 51001 Ceuta, Spain
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9
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French AR, van Rijn RM. An updated assessment of the translational promise of G-protein-biased kappa opioid receptor agonists to treat pain and other indications without debilitating adverse effects. Pharmacol Res 2022; 177:106091. [PMID: 35101565 PMCID: PMC8923989 DOI: 10.1016/j.phrs.2022.106091] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/14/2022] [Accepted: 01/18/2022] [Indexed: 01/22/2023]
Abstract
Kappa opioid receptor (κOR) agonists lack the abuse liability and respiratory depression effects of clinically used mu opioid receptor (μOR) analgesics and are hypothesized to be safer alternatives. However, κOR agonists have limiting adverse effects of their own, including aversion, sedation, and mood effects, that have hampered their clinical translation. Studies performed over the last 15 years have suggested that these adverse effects could result from activation of distinct intracellular signaling pathways that are dependent on β-arrestin, whereas signaling downstream of G protein activation produces antinociception. This led to the hypothesis that agonists biased away from β-arrestin signaling would have improved therapeutic windows over traditional unbiased agonists and allow for clinical development of analgesic G-protein-biased κOR agonists. Given a recent controversy regarding the benefits of G-protein-biased μOR agonists, it is timely to reassess the therapeutic promise of G-protein-biased κOR agonists. Here we review recent discoveries from preclinical κOR studies and critically evaluate the therapeutic windows of G-protein-biased κOR agonists in each of the adverse effects above. Overall, we find that G-protein-biased κOR agonists generally have improved therapeutic window relative to unbiased agonists, although frequently study design limits strong conclusions in this regard. However, a steady flow of newly developed biased κOR agonists paired with recently engineered behavioral and molecular tools puts the κOR field in a prime position to make major advances in our understanding of κOR function and fulfill the promise of translating a new generation of biased κOR agonists to the clinic.
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Affiliation(s)
- Alexander R French
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Richard M van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Drug Discovery, Purdue University, West Lafayette, IN 47907, USA.
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10
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Agonist-promoted kappa opioid receptor (KOR) phosphorylation has behavioral endpoint-dependent and sex-specific effects. Neuropharmacology 2022; 202:108860. [PMID: 34736959 PMCID: PMC9122667 DOI: 10.1016/j.neuropharm.2021.108860] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 10/27/2021] [Accepted: 10/29/2021] [Indexed: 02/07/2023]
Abstract
We reported previously that the selective agonist U50,488H promoted phosphorylation of the mouse kappa opioid receptor (mKOR) in vitro at four residues in the C-terminal domain. In this study, we generated a mutant mouse line in which all the four residues were mutated to Ala (K4A) to examine the in vivo functional significance of agonist-induced KOR phosphorylation. U50,488H promoted KOR phosphorylation in brains of the wildtype (WT), but not K4A, male and female mice. Autoradiography of [3H] 69,593 binding to KOR in brain sections showed that WT and K4A mice had similar KOR distribution and expression levels in brain regions without sex differences. In K4A mice, U50,488H inhibited compound 48/80-induced scratching and attenuated novelty-induced hyperlocomotion to similar extents as in WT mice without sex differences. Interestingly, repeated pretreatment with U50,488H (80 mg/kg, s.c.) resulted in profound tolerance to the anti-scratch effects of U50,488H (5 mg/kg, s.c.) in WT mice of both sexes and female K4A mice, while in male K4A mice tolerance was attenuated. Moreover, U50,488H (2 mg/kg) induced conditioned place aversion (CPA) in WT mice of both sexes and male K4A mice, but not in female K4A mice. In contrast, U50,488H (5 mg/kg) caused CPA in male, but not female, mice, regardless of genotype. Thus, agonist-promoted KOR phosphorylation plays important roles in U50,488H-induced tolerance and CPA in a sex-dependent manner, without affecting acute U50,488H-induced anti-pruritic and hypo-locomotor effects. These results are the first to demonstrate sex differences in the effects of GPCR phosphorylation on the GPCR-mediated behaviors.
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