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Kong C, Castro DC, Lee J, Piston DW. The role of mu-opioid receptors in pancreatic islet alpha cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.13.593899. [PMID: 38798528 PMCID: PMC11118541 DOI: 10.1101/2024.05.13.593899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
30% of people in the United States have diabetes or pre-diabetes. Many of these individuals will develop diabetic neuropathy as a comorbidity, which is often treated with exogenous opioids like morphine, oxycodone, or tramadol. Although these opioids are effective analgesics, growing evidence indicates that they may directly impact the endocrine pancreas function in human and preclinical models. One common feature of these exogenous opioid ligands is their preference for the mu opioid receptor (MOPR), so we aimed to determine if endogenous MOPRs directly regulate pancreatic islet metabolism and hormone secretion. We show that pharmacological antagonism of MOPRs enhances glucagon secretion, but not insulin secretion, from human islets under high glucose conditions. This increased secretion is accompanied by increased cAMP signaling. mRNA expression of MOPRs is enriched in human islet α-cells, but downregulated in T2D islet donors, suggesting a link between metabolism and MOPR expression. Conditional genetic knockout of MOPRs in murine α-cells increases glucagon secretion in high glucose conditions without increasing glucagon content. Consistent with downregulation of MOPRs during metabolic disease, conditional MOPR knockout mice treated with a high fat diet show impaired glucose tolerance, increased glucagon secretion, increased insulin content, and increased islet size. Finally, we show that MOPR-mediated changes in glucagon secretion are driven, in part, by KATP channel activity. Together, these results demonstrate a direct mechanism of action for endogenous opioid regulation of endocrine pancreas.
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Affiliation(s)
- Chen Kong
- Department of Cell Biology & Physiology, Washington University School of Medicine, St Louis, Missouri, 63110, USA
| | - Daniel C. Castro
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri, 63110, USA
| | - Jeongmin Lee
- Department of Cell Biology & Physiology, Washington University School of Medicine, St Louis, Missouri, 63110, USA
| | - David W. Piston
- Department of Cell Biology & Physiology, Washington University School of Medicine, St Louis, Missouri, 63110, USA
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Torres-Rodriguez JM, Wilson TD, Singh S, Torruella-Suárez ML, Chaudhry S, Adke AP, Becker JJ, Neugebauer B, Lin JL, Martinez Gonzalez S, Soler-Cedeño O, Carrasquillo Y. The parabrachial to central amygdala pathway is critical to injury-induced pain sensitization in mice. Neuropsychopharmacology 2024; 49:508-520. [PMID: 37542159 PMCID: PMC10789863 DOI: 10.1038/s41386-023-01673-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/27/2023] [Accepted: 07/12/2023] [Indexed: 08/06/2023]
Abstract
The spino-ponto-amygdaloid pathway is a major ascending circuit relaying nociceptive information from the spinal cord to the brain. Potentiation of excitatory synaptic transmission in the parabrachial nucleus (PBN) to central amygdala (CeA) pathway has been reported in rodent models of persistent pain. However, the functional significance of this pathway in the modulation of the somatosensory component of pain was recently challenged by studies showing that spinal nociceptive neurons do not target CeA-projecting PBN cells and that manipulations of this pathway have no effect on reflexive-defensive somatosensory responses to peripheral noxious stimulation. Here, we showed that activation of CeA-projecting PBN neurons is critical to increase both stimulus-evoked and spontaneous nociceptive responses following an injury in male and female mice. Using optogenetic-assisted circuit mapping, we confirmed a functional excitatory projection from PBN→CeA that is independent of the genetic or firing identity of CeA cells. We then showed that peripheral noxious stimulation increased the expression of the neuronal activity marker Fos in CeA-projecting PBN neurons and that chemogenetic inactivation of these cells decreased behavioral hypersensitivity in models of neuropathic and inflammatory pain without affecting baseline nociception. Lastly, we showed that chemogenetic activation of CeA-projecting PBN neurons is sufficient to induced bilateral hypersensitivity without injury. Together, our results indicate that the PBN→CeA pathway is a key modulator of pain-related behaviors that can increase reflexive-defensive and affective-motivational responses to somatosensory stimulation in injured states without affecting nociception under normal physiological conditions.
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Affiliation(s)
- Jeitzel M Torres-Rodriguez
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Torri D Wilson
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Sudhuman Singh
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Maria L Torruella-Suárez
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Sarah Chaudhry
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Anisha P Adke
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Jordan J Becker
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Benjamin Neugebauer
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Jenny L Lin
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Santiago Martinez Gonzalez
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Omar Soler-Cedeño
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA
| | - Yarimar Carrasquillo
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, USA.
- National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, USA.
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Bavencoffe AG, Lopez ER, Johnson KN, Tian J, Gorgun FM, Shen BQ, Zhu MX, Dessauer CW, Walters ET. Widespread latent hyperactivity of nociceptors outlasts enhanced avoidance behavior following incision injury. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.30.578108. [PMID: 38352319 PMCID: PMC10862851 DOI: 10.1101/2024.01.30.578108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
Nociceptors with somata in dorsal root ganglia (DRGs) exhibit an unusual readiness to switch from an electrically silent state to a hyperactive state of tonic, nonaccommodating, low-frequency, irregular discharge of action potentials (APs). Ongoing activity (OA) during this state is present in vivo in rats months after spinal cord injury (SCI), and has been causally linked to SCI pain. OA induced by various neuropathic conditions in rats, mice, and humans is retained in nociceptor somata after dissociation and culturing, providing a powerful tool for investigating its mechanisms and functions. An important question is whether similar nociceptor OA is induced by painful conditions other than neuropathy. The present study shows that probable nociceptors dissociated from DRGs of rats subjected to postsurgical pain (induced by plantar incision) exhibit OA. The OA was most apparent when the soma was artificially depolarized to a level within the normal range of membrane potentials where large, transient depolarizing spontaneous fluctuations (DSFs) can approach AP threshold. This latent hyperactivity persisted for at least 3 weeks, whereas behavioral indicators of affective pain - hindpaw guarding and increased avoidance of a noxious substrate in an operant conflict test - persisted for 1 week or less. An unexpected discovery was latent OA in neurons from thoracic DRGs that innervate dermatomes distant from the injured tissue. The most consistent electrophysiological alteration associated with OA was enhancement of DSFs. Potential in vivo functions of widespread, low-frequency nociceptor OA consistent with these and other findings are to amplify hyperalgesic priming and to drive anxiety-related hypervigilance.
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Affiliation(s)
- Alexis G. Bavencoffe
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston
| | - Elia R. Lopez
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston
| | - Kayla N. Johnson
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston
| | - Jinbin Tian
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston
| | - Falih M. Gorgun
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston
| | - Breanna Q. Shen
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston
| | - Michael X. Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston
| | - Carmen W. Dessauer
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston
| | - Edgar T. Walters
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston
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Qi Y, Nelson TS, Prasoon P, Norris C, Taylor BK. Contribution of µ Opioid Receptor-expressing Dorsal Horn Interneurons to Neuropathic Pain-like Behavior in Mice. Anesthesiology 2023; 139:840-857. [PMID: 37566700 PMCID: PMC10840648 DOI: 10.1097/aln.0000000000004735] [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] [Indexed: 08/13/2023]
Abstract
BACKGROUND Intersectional genetics have yielded tremendous advances in our understanding of molecularly identified subpopulations and circuits within the dorsal horn in neuropathic pain. The authors tested the hypothesis that spinal µ opioid receptor-expressing neurons (Oprm1-expressing neurons) contribute to behavioral hypersensitivity and neuronal sensitization in the spared nerve injury model in mice. METHODS The authors coupled the use of Oprm1Cre transgenic reporter mice with whole cell patch clamp electrophysiology in lumbar spinal cord slices to evaluate the neuronal activity of Oprm1-expressing neurons in the spared nerve injury model of neuropathic pain. The authors used a chemogenetic approach to activate or inhibit Oprm1-expressing neurons, followed by the assessment of behavioral signs of neuropathic pain. RESULTS The authors reveal that spared nerve injury yielded a robust neuroplasticity of Oprm1-expressing neurons. Spared nerve injury reduced Oprm1 gene expression in the dorsal horn as well as the responsiveness of Oprm1-expressing neurons to the selective µ agonist (D-Ala2, N-MePhe4, Gly-ol)-enkephalin (DAMGO). Spared nerve injury sensitized Oprm1-expressing neurons, as reflected by an increase in their intrinsic excitability (rheobase, sham 38.62 ± 25.87 pA [n = 29]; spared nerve injury, 18.33 ± 10.29 pA [n = 29], P = 0.0026) and spontaneous synaptic activity (spontaneous excitatory postsynaptic current frequency in delayed firing neurons: sham, 0.81 ± 0.67 Hz [n = 14]; spared nerve injury, 1.74 ± 1.68 Hz [n = 10], P = 0.0466), and light brush-induced coexpression of the immediate early gene product, Fos in laminae I to II (%Fos/tdTomato+: sham, 0.42 ± 0.57% [n = 3]; spared nerve injury, 28.26 ± 1.92% [n = 3], P = 0.0001). Chemogenetic activation of Oprm1-expressing neurons produced mechanical hypersensitivity in uninjured mice (saline, 2.91 ± 1.08 g [n = 6]; clozapine N-oxide, 0.65 ± 0.34 g [n = 6], P = 0.0006), while chemogenetic inhibition reduced behavioral signs of mechanical hypersensitivity (saline, 0.38 ± 0.37 g [n = 6]; clozapine N-oxide, 1.05 ± 0.42 g [n = 6], P = 0.0052) and cold hypersensitivity (saline, 6.89 ± 0.88 s [n = 5] vs. clozapine N-oxide, 2.31 ± 0.52 s [n = 5], P = 0.0017). CONCLUSIONS The authors conclude that nerve injury sensitizes pronociceptive µ opioid receptor-expressing neurons in mouse dorsal horn. Nonopioid strategies to inhibit these interneurons might yield new treatments for neuropathic pain. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Yanmei Qi
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Tyler S. Nelson
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Pranav Prasoon
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Christopher Norris
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Bradley K. Taylor
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Ren K, Vickers R, Murillo J, Ruparel NB. Revolutionizing orofacial pain management: the promising potential of stem cell therapy. FRONTIERS IN PAIN RESEARCH 2023; 4:1239633. [PMID: 38028430 PMCID: PMC10679438 DOI: 10.3389/fpain.2023.1239633] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 09/22/2023] [Indexed: 12/01/2023] Open
Abstract
Orofacial pain remains a significant health issue in the United States. Pain originating from the orofacial region can be composed of a complex array of unique target tissue that contributes to the varying success of pain management. Long-term use of analgesic drugs includes adverse effects such as physical dependence, gastrointestinal bleeding, and incomplete efficacy. The use of mesenchymal stem cells for their pain relieving properties has garnered increased attention. In addition to the preclinical and clinical results showing stem cell analgesia in non-orofacial pain, studies have also shown promising results for orofacial pain treatment. Here we discuss the outcomes of mesenchymal stem cell treatment for pain and compare the properties of stem cells from different tissues of origin. We also discuss the mechanism underlying these analgesic/anti-nociceptive properties, including the role of immune cells and the endogenous opioid system. Lastly, advancements in the methods and procedures to treat patients experiencing orofacial pain with mesenchymal stem cells are also discussed.
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Affiliation(s)
- Ke Ren
- Department of Pain and Neural Sciences, University of Maryland, Baltimore, MD, United States
| | - Russel Vickers
- Clinical Stem Cells Pty Ltd., Sydney, NSW, Australia
- Oral Health Center, School of Dentistry, Faculty of Health and Behavioural Sciences, The University of Queensland, Brisbane, QLD, Australia
- Institute for Glycomics, Griffith University Queensland, Southport, QLD, Australia
| | - Josue Murillo
- Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Nikita B. Ruparel
- Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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Singleton S, Sneddon C, Bakina A, Lambert JJ, Hales TG. Early-life adversity increases morphine tolerance and persistent inflammatory hypersensitivity through upregulation of δ opioid receptors in mice. Pain 2023; 164:2253-2264. [PMID: 37171192 PMCID: PMC10502877 DOI: 10.1097/j.pain.0000000000002925] [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: 01/05/2023] [Revised: 03/03/2023] [Accepted: 03/17/2023] [Indexed: 05/13/2023]
Abstract
ABSTRACT Exposure to severely stressful events during childhood is associated with poor health outcomes in later life, including chronic pain and substance use disorder. However, the mediators and mechanisms are unclear. We investigated the impact of a well-characterized mouse model of early-life adversity, fragmented maternal care (FC) between postnatal day 2 and 9, on nociception, inflammatory hypersensitivity, and responses to morphine. Male and female mice exposed to FC exhibited prolonged basal thermal withdrawal latencies and decreased mechanical sensitivity. In addition, morphine had reduced potency in mice exposed to FC and their development of tolerance to morphine was accelerated. Quantitative PCR analysis in several brain regions and the spinal cords of juvenile and adult mice revealed an impact of FC on the expression of genes encoding opioid peptide precursors and their receptors. These changes included enhanced abundance of δ opioid receptor transcript in the spinal cord. Acute inflammatory hypersensitivity (induced by hind paw administration of complete Freund's adjuvant) was unaffected by exposure to FC. However, after an initial recovery of mechanical hypersensitivity, there was a reappearance in mice exposed to FC by day 15, which was not seen in control mice. Changes in nociception, morphine responses, and hypersensitivity associated with FC were apparent in males and females but were absent from mice lacking δ receptors or β-arrestin2. These findings suggest that exposure to early-life adversity in mice enhances δ receptor expression leading to decreased basal sensitivity to noxious stimuli coupled with accelerated morphine tolerance and enhanced vulnerability to persistent inflammatory hypersensitivity.
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Affiliation(s)
- Sam Singleton
- The Institute of Academic Anaesthesia, Division of Cellular and Systems Medicine, School of Medicine, Ninewells Hospital, University of Dundee, Dundee, United Kingdom
| | - Claire Sneddon
- The Institute of Academic Anaesthesia, Division of Cellular and Systems Medicine, School of Medicine, Ninewells Hospital, University of Dundee, Dundee, United Kingdom
| | - Alice Bakina
- The Institute of Academic Anaesthesia, Division of Cellular and Systems Medicine, School of Medicine, Ninewells Hospital, University of Dundee, Dundee, United Kingdom
| | - Jeremy J. Lambert
- The Institute of Academic Anaesthesia, Division of Cellular and Systems Medicine, School of Medicine, Ninewells Hospital, University of Dundee, Dundee, United Kingdom
| | - Tim G. Hales
- The Institute of Academic Anaesthesia, Division of Cellular and Systems Medicine, School of Medicine, Ninewells Hospital, University of Dundee, Dundee, United Kingdom
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Nguyen E, Chiang MC, Nguyen C, Ross SE. Brainstem Modulation of Nociception by Periaqueductal Gray Neurons Expressing the μ-Opioid Receptor in Mice. Anesthesiology 2023; 139:462-475. [PMID: 37364291 PMCID: PMC10870981 DOI: 10.1097/aln.0000000000004668] [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] [Indexed: 06/28/2023]
Abstract
BACKGROUND Pharmacologic manipulations directed at the periaqueductal gray have demonstrated the importance of the μ-opioid receptor in modulating reflexive responses to nociception. The authors hypothesized that a supraspinal pathway centered on neurons in the periaqueductal gray containing the μ-opioid receptor could modulate nociceptive and itch behaviors. METHODS The study used anatomical, optogenetic, and chemogenetic approaches in male and female mice to manipulate μ-opioid receptor neurons in the periaqueductal gray. Behavioral assays including von Frey, Hargreaves, cold plantar, chloroquine-induced itch, hotplate, formalin-induced injury, capsaicin-induced injury, and open field tests were used. In separate experiments, naloxone was administered in a postsurgical model of latent sensitization. RESULTS Activation of μ-opioid receptor neurons in the periaqueductal gray increased jumping (least-squares mean difference of -3.30 s; 95% CI, -6.17 to -0.44; P = 0.023; n = 7 or 8 mice per group), reduced itch responses (least-squares mean difference of 70 scratching bouts; 95% CI, 35 to 105; P < 0.001; n = 8 mice), and elicited modestly antinociceptive effects (least-squares mean difference of -0.7 g on mechanical and -10.24 s on thermal testing; 95% CI, -1.3 to -0.2 and 95% CI, -13.77 to -6.70, and P = 0.005 and P < 0.001, respectively; n = 8 mice). Last, the study uncovered the role of the periaqueductal gray in suppressing hyperalgesia after a postsurgical state of latent sensitization (least-squares mean difference comparing saline and naloxone of -12 jumps; 95% CI, -17 to -7; P < 0.001 for controls; and -2 jumps; 95% CI, -7 to 4; P = 0.706 after optogenetic stimulation; n = 7 to 9 mice per group). CONCLUSIONS μ-Opioid receptor neurons in the periaqueductal gray modulate distinct nocifensive behaviors: their activation reduced responses to mechanical and thermal testing, and attenuated scratching behaviors, but facilitated escape responses. The findings emphasize the role of the periaqueductal gray in the behavioral expression of nociception using reflexive and noxious paradigms. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Eileen Nguyen
- University of Pittsburgh School of Medicine, Department of Anesthesiology, Pittsburgh, PA, USA
- University of Pittsburgh, Department of Neurobiology, Pittsburgh, PA, USA
- University of California, Los Angeles, Department of Anesthesiology, Los Angeles, CA, USA
| | - Michael C. Chiang
- University of Pittsburgh School of Medicine, Department of Anesthesiology, Pittsburgh, PA, USA
- University of Pittsburgh, Department of Neurobiology, Pittsburgh, PA, USA
| | - Catherine Nguyen
- University of Pittsburgh School of Medicine, Department of Anesthesiology, Pittsburgh, PA, USA
- University of Pittsburgh, Department of Neurobiology, Pittsburgh, PA, USA
| | - Sarah E. Ross
- University of Pittsburgh School of Medicine, Department of Anesthesiology, Pittsburgh, PA, USA
- University of Pittsburgh, Department of Neurobiology, Pittsburgh, PA, USA
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Sadee W. Ligand-Free Signaling of G-Protein-Coupled Receptors: Physiology, Pharmacology, and Genetics. Molecules 2023; 28:6375. [PMID: 37687205 PMCID: PMC10489045 DOI: 10.3390/molecules28176375] [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: 07/29/2023] [Revised: 08/28/2023] [Accepted: 08/30/2023] [Indexed: 09/10/2023] Open
Abstract
G-protein-coupled receptors (GPCRs) are ubiquitous sensors and regulators of cellular functions. Each GPCR exists in complex aggregates with multiple resting and active conformations. Designed to detect weak stimuli, GPCRs can also activate spontaneously, resulting in basal ligand-free signaling. Agonists trigger a cascade of events leading to an activated agonist-receptor G-protein complex with high agonist affinity. However, the ensuing signaling process can further remodel the receptor complex to reduce agonist affinity, causing rapid ligand dissociation. The acutely activated ligand-free receptor can continue signaling, as proposed for rhodopsin and μ opioid receptors, resulting in robust receptor activation at low agonist occupancy with enhanced agonist potency. Continued receptor stimulation can further modify the receptor complex, regulating sustained ligand-free signaling-proposed to play a role in opioid dependence. Basal, acutely agonist-triggered, and sustained elevated ligand-free signaling could each have distinct functions, reflecting multi-state conformations of GPCRs. This review addresses basal and stimulus-activated ligand-free signaling, its regulation, genetic factors, and pharmacological implications, focusing on opioid and serotonin receptors, and the growth hormone secretagogue receptor (GHSR). The hypothesis is proposed that ligand-free signaling of 5-HT2A receptors mediate therapeutic effects of psychedelic drugs. Research avenues are suggested to close the gaps in our knowledge of ligand-free GPCR signaling.
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Affiliation(s)
- Wolfgang Sadee
- Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA;
- Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158, USA
- Aether Therapeutics Inc., Austin, TX 78756, USA
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9
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Nelson TS, Santos DFS, Prasoon P, Gralinski M, Allen HN, Taylor BK. Endogenous μ-opioid-Neuropeptide Y Y1 receptor synergy silences chronic postoperative pain in mice. PNAS NEXUS 2023; 2:pgad261. [PMID: 37649580 PMCID: PMC10465188 DOI: 10.1093/pnasnexus/pgad261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 03/09/2023] [Accepted: 07/31/2023] [Indexed: 09/01/2023]
Abstract
Tissue injury creates a delicate balance between latent pain sensitization (LS) and compensatory endogenous analgesia. Inhibitory G-protein-coupled receptor (GPCR) interactions that oppose LS, including μ-opioid receptor (MOR) or neuropeptide Y Y1 receptor (Y1R) activity, persist in the spinal cord dorsal horn (DH) for months, even after the resolution of normal pain thresholds. Here, we demonstrate that following recovery from surgical incision, a potent endogenous analgesic synergy between MOR and Y1R activity persists within DH interneurons to reduce the intensity and duration of latent postoperative hypersensitivity and ongoing pain. Failure of such endogenous GPCR signaling to maintain LS in remission may underlie the transition from acute to chronic pain states.
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Affiliation(s)
- Tyler S Nelson
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, 200 Lothrop Street, Pittsburgh, PA 15213, USA
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Diogo F S Santos
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, 200 Lothrop Street, Pittsburgh, PA 15213, USA
| | - Pranav Prasoon
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, 200 Lothrop Street, Pittsburgh, PA 15213, USA
| | - Margaret Gralinski
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, 200 Lothrop Street, Pittsburgh, PA 15213, USA
| | - Heather N Allen
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, 200 Lothrop Street, Pittsburgh, PA 15213, USA
| | - Bradley K Taylor
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, 200 Lothrop Street, Pittsburgh, PA 15213, USA
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10
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Reddy D, Wickman JR, Ajit SK. Epigenetic regulation in opioid induced hyperalgesia. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2023; 14:100146. [PMID: 38099284 PMCID: PMC10719581 DOI: 10.1016/j.ynpai.2023.100146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/14/2023] [Accepted: 11/21/2023] [Indexed: 12/17/2023]
Abstract
About 25 million American adults experience pain daily and one of the most commonly prescribed drugs to treat pain are opioids. Prolonged opioid usage and dose escalations can cause a paradoxical response where patients experience enhanced pain sensitivity. This opioid induced hyperalgesia (OIH) is a major hurdle when treating pain in the clinic because its underlying mechanisms are still not fully understood. OIH is also commonly overlooked and lacks guidelines to prevent its onset. Research on pain disorders and opioid usage have recognized potential epigenetic drivers of disease including DNA methylation, histone modifications, miRNA regulation, but their involvement in OIH has not been well studied. This article discusses epigenetic changes that may contribute to pathogenesis, with an emphasis on miRNA alterations in OIH. There is a crucial gap in knowledge including how multiple epigenetic modulators contribute to OIH. Elucidating the epigenetic changes underlying OIH and the crosstalk among these mechanisms could lead to the development of novel targets for the prevention and treatment of this painful phenomena.
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Affiliation(s)
- Deepa Reddy
- Department of Pharmacology & Physiology, Drexel University College of Medicine, 245 North 15th Street, Philadelphia, PA 19102, USA
| | - Jason R. Wickman
- Department of Pharmacology & Physiology, Drexel University College of Medicine, 245 North 15th Street, Philadelphia, PA 19102, USA
| | - Seena K. Ajit
- Department of Pharmacology & Physiology, Drexel University College of Medicine, 245 North 15th Street, Philadelphia, PA 19102, USA
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Inyang KE, Sim J, Clark KB, Matan G, Monahan K, Evans C, Beng P, Ma JV, Heijnen CJ, Dantzer R, Scherrer G, Kavelaars A, Bernard M, Aldhamen Y, Folger JK, Laumet G. Tonic Meningeal Interleukin-10 Upregulates Delta Opioid Receptor to Prevent Relapse to Pain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.08.544200. [PMID: 37333074 PMCID: PMC10274865 DOI: 10.1101/2023.06.08.544200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Chronic pain often alternates between transient remission and relapse of severe pain. While most research on chronic pain has focused on mechanisms maintaining pain, there is a critical unmet need to understand what prevents pain from re-emerging in those who recover from acute pain. We found that interleukin (IL)-10, a pain resolving cytokine, is persistently produced by resident macrophages in the spinal meninges during remission from pain. IL-10 upregulated expression and analgesic activity of δ-opioid receptor (δOR) in the dorsal root ganglion. Genetic or pharmacological inhibition of IL-10 signaling or δOR triggered relapse to pain in both sexes. These data challenge the widespread assumption that remission of pain is simply a return to the naïve state before pain was induced. Instead, our findings strongly suggest a novel concept that: remission is a state of lasting pain vulnerability that results from a long-lasting neuroimmune interactions in the nociceptive system.
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12
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Tsuda M, Masuda T, Kohno K. Microglial diversity in neuropathic pain. Trends Neurosci 2023:S0166-2236(23)00124-8. [PMID: 37244781 DOI: 10.1016/j.tins.2023.05.001] [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: 03/17/2023] [Revised: 04/17/2023] [Accepted: 05/02/2023] [Indexed: 05/29/2023]
Abstract
Microglia play pivotal roles in controlling CNS functions in diverse physiological and pathological contexts, including neuropathic pain, a chronic pain condition caused by lesions or diseases of the somatosensory nervous system. In this review article, we summarize evidence primarily from basic research on the role of microglia in the development and remission of neuropathic pain. The identification of a subset of microglia that emerged after pain development and that was necessary for remission of neuropathic pain highlights the highly divergent and dynamic nature of microglia in the course of neuropathic pain. Understanding microglial diversity in terms of gene expression, physiological states, and functional roles could lead to new strategies that aid in the diagnosis and management of neuropathic pain, and that may not have been anticipated from the viewpoint of targeting all microglia uniformly.
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Affiliation(s)
- Makoto Tsuda
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan; Kyushu University Institute for Advanced Study, Fukuoka, Japan.
| | - Takahiro Masuda
- Division of Molecular Neuroimmunology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Keita Kohno
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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13
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Torres-Rodriguez JM, Wilson TD, Singh S, Chaudhry S, Adke AP, Becker JJ, Lin JL, Martinez Gonzalez S, Soler-Cedeño O, Carrasquillo Y. The parabrachial to central amygdala circuit is a key mediator of injury-induced pain sensitization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.08.527340. [PMID: 36945586 PMCID: PMC10028796 DOI: 10.1101/2023.02.08.527340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The spino-ponto-amygdaloid pathway is a major ascending circuit relaying nociceptive information from the spinal cord to the brain. Potentiation of excitatory synaptic transmission in the parabrachial nucleus (PbN) to central amygdala (CeA) pathway has been reported in rodent models of persistent pain. At the behavioral level, the PbN→CeA pathway has been proposed to serve as a general alarm system to potential threats that modulates pain-related escape behaviors, threat memory, aversion, and affective-motivational (but not somatosensory) responses to painful stimuli. Increased sensitivity to previously innocuous somatosensory stimulation is a hallmark of chronic pain. Whether the PbN→CeA circuit contributes to heightened peripheral sensitivity following an injury, however, remains unknown. Here, we demonstrate that activation of CeA-projecting PbN neurons contributes to injury-induced behavioral hypersensitivity but not baseline nociception in male and female mice. Using optogenetic assisted circuit mapping, we confirmed a functional excitatory projection from PbN→CeA that is independent of the genetic or firing identity of CeA cells. We then showed that peripheral noxious stimulation increases the expression of the neuronal activity marker c-Fos in CeA-projecting PbN neurons and chemogenetic inactivation of these cells reduces behavioral hypersensitivity in models of neuropathic and inflammatory pain without affecting baseline nociception. Lastly, we show that chemogenetic activation of CeA-projecting PbN neurons is sufficient to induce bilateral hypersensitivity without injury. Together, our results demonstrate that the PbN→CeA pathway is a key modulator of pain-related behaviors that can amplify responses to somatosensory stimulation in pathological states without affecting nociception under normal physiological conditions. Significance Statement Early studies identified the spino-ponto-amygdaloid pathway as a major ascending circuit conveying nociceptive inputs from the spinal cord to the brain. The functional significance of this circuit to injury-induced hypersensitivity, however, remains unknown. Here, we addressed this gap in knowledge using viral-mediated anatomical tracers, ex-vivo electrophysiology and chemogenetic intersectional approaches in rodent models of persistent pain. We found that activation of this pathway contributes to injury-induced hypersensitivity, directly demonstrating a critical function of the PbN→CeA circuit in pain modulation.
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Affiliation(s)
| | - Torri D. Wilson
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Sudhuman Singh
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Sarah Chaudhry
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Anisha P. Adke
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Jordan J. Becker
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Jenny L. Lin
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | | | - Omar Soler-Cedeño
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Yarimar Carrasquillo
- National Center for Complementary and Integrative Health, Bethesda, MD, United States
- National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, United States
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14
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Morales-Medina JC, Pugliese N, Di Cerbo A, Zizzadoro C, Iannitti T. Evidence for Endogenous Opioid Dependence Related to Latent Sensitization in a Rat Model of Chronic Inflammatory Pain. Int J Mol Sci 2023; 24:ijms24032812. [PMID: 36769126 PMCID: PMC9917357 DOI: 10.3390/ijms24032812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 01/25/2023] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
Studies performed in a mouse model of chronic inflammatory pain induced by intraplantar injection of complete Freund's adjuvant (CFA) have shown that constitutive activation of the endogenous opioid signaling, besides serving as a mechanism of endogenous analgesia that tonically represses pain sensitization, also generates a state of endogenous opioid dependence. Since species-related differences concerning pain biology and addictive behaviors occur between mice and rats, the present study explored whether the coexistence of endogenous opioid analgesia and endogenous opioid dependence also characterizes a homologous rat model. To this aim, CFA-injured Wistar rats were treated with either 3 mg/kg or 10 mg/kg of the opioid receptor inverse agonist naltrexone (NTX) during the pain remission phase and monitored for 60 min for possible withdrawal behaviors. At 3 mg/kg, NTX, besides inducing the reinstatement of mechanical allodynia, also caused a distinct appearance of ptosis, with slight but nonsignificant changes to the occurrence of teeth chatters and rearing. On the other hand, 10 mg/kg of NTX failed to unmask pain sensitization and induced significantly lower levels of ptosis than 3 mg/kg. Such an NTX-related response pattern observed in the rat CFA model seems to differ substantially from the pattern previously described in the mouse CFA model. This supports the knowledge that mice and rats are not identical in terms of pharmacological response and stresses the importance of choosing the appropriate species for preclinical pain research purposes depending on the scientific question being asked.
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Affiliation(s)
- Julio César Morales-Medina
- Centro de Investigación en Reproducción Animal, CINVESTAV-Universidad Autónoma de Tlaxcala, AP 62, Tlaxcala 90000, Mexico
| | - Nicola Pugliese
- Department of Veterinary Medicine, University of Bari, 70010 Valenzano, Italy
| | - Alessandro Di Cerbo
- School of Biosciences and Veterinary Medicine, University of Camerino, 62024 Matelica, Italy
- Correspondence: (A.D.C.); (C.Z.)
| | - Claudia Zizzadoro
- Department of Veterinary Medicine, University of Bari, 70010 Valenzano, Italy
- Correspondence: (A.D.C.); (C.Z.)
| | - Tommaso Iannitti
- Section of Experimental Medicine, Department of Medical Sciences, University of Ferrara, Via Fossato di Mortara 70, 44121 Ferrara, Italy
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15
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Franchini L, Orlandi C. Probing the orphan receptors: Tools and directions. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2023; 195:47-76. [PMID: 36707155 DOI: 10.1016/bs.pmbts.2022.06.011] [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: 02/08/2023]
Abstract
The endogenous ligands activating a large fraction of the G Protein Coupled Receptor (GPCR) family members have yet to be identified. These receptors are commonly labeled as orphans (oGPCRs), and because of the absence of available pharmacological tools they are currently understudied. Nonetheless, genome wide association studies, together with research using animal models identified many physiological functions regulated by oGPCRs. Similarly, mutations in some oGPCRs have been associated with rare genetic disorders or with an increased risk of developing pathologies. The once underestimated pharmacological potential of targeting oGPCRs is increasingly being exploited by the development of novel tools to understand their biology and by drug discovery endeavors aimed at identifying new modulators of their activity. Here, we summarize recent advancements in the field of oGPCRs and future directions.
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Affiliation(s)
- Luca Franchini
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, United States
| | - Cesare Orlandi
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, United States.
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16
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Hogri R, Baltov B, Drdla-Schutting R, Mussetto V, Raphael H, Trofimova L, Sandkühler J. Probing pain aversion in rats with the "Heat Escape Threshold" paradigm. Mol Pain 2023; 19:17448069231156657. [PMID: 36717755 PMCID: PMC9996743 DOI: 10.1177/17448069231156657] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The aversive aspect of pain constitutes a major burden faced by pain patients. This has been recognized by the pain research community, leading to the development of novel methods focusing on affective-motivational behaviour in pain model animals. The most common tests used to assess pain aversion in animals require cognitive processes, such as associative learning, complicating the interpretation of results. To overcome this issue, studies in recent years have utilized unconditioned escape as a measure of aversion. However, the vast majority of these studies quantify jumping - a common escape behaviour in mice, but not in adult rats, thus limiting its use. Here, we present the "Heat Escape Threshold" (HET) paradigm for assessing heat aversion in rats. We demonstrate that this method can robustly and reproducibly detect the localized effects of an inflammatory pain model (intraplantar carrageenan) in male and female Sprague-Dawley rats. In males, a temperature that evoked unconditioned escape following carrageenan treatment also induced real-time place avoidance (RTPA). Systemic morphine more potently alleviated carrageenan-induced heat aversion (as measured by the HET and RTPA methods), as compared to reflexive responses to heat (as measured by the Hargreaves test), supporting previous findings. Next, we examined how blocking of excitatory transmission to the lateral parabrachial nucleus (LPBN), a key node in the ascending pain system, affects pain behaviour. Using the HET and Hargreaves tests, we show that intra-LPBN application of glutamate antagonists reverses the effects of carrageenan on both affective and reflexive pain behaviour, respectively. Finally, we employed the HET paradigm in a generalized opioid-withdrawal pain model. Withdrawal from a brief systemic administration of remifentanil resulted in a long-lasting and robust increase in heat aversion, but no change in reflexive responses to heat. Taken together, these data demonstrate the utility of the HET paradigm as a novel tool in preclinical pain research.
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Affiliation(s)
- Roni Hogri
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
| | - Bozhidar Baltov
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
| | - Ruth Drdla-Schutting
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
| | - Valeria Mussetto
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
| | - Holzinger Raphael
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
| | - Lidia Trofimova
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
| | - Jürgen Sandkühler
- Department of Neurophysiology,
Center for
Brain Research, Medical University of
Vienna, Vienna, Austria
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17
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Gutiérrez-Rojas RA, Aguayo-Cerón KA, Vargas-De-León C, Cabrera-Becerra SE, Almanza-Pérez JC, Huang F, Villafaña S, Romero-Nava R. Glycine Effect on the Expression Profile of Orphan Receptors GPR21, GPR26, GPR39, GPR82 and GPR6 in a Model of Inflammation in 3T3-L1 Cells. Life (Basel) 2022; 12:1687. [PMID: 36362842 PMCID: PMC9696036 DOI: 10.3390/life12111687] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/19/2022] [Accepted: 10/21/2022] [Indexed: 07/30/2023] Open
Abstract
BACKGROUND Chronic or low-grade inflammation is a process where various immune cells are recruited from the periphery into adipose tissue. This event gives rise to localised inflammation, in addition to having a close interaction with cardiometabolic pathologies where the mediation of orphan receptors is observed. The aim of this study was to analyse the participation of the orphan receptors GPR21, GPR39, GPR82 and GPR6 in a chronic inflammatory process in 3T3-L1 cells. The 3T3-L1 cells were stimulated with TNF-α (5 ng/mL) for 60 min as an inflammatory model. Gene expression was measured by RT-qPCR. RESULTS We showed that the inflammatory stimulus of TNF-α in adipocytes decreased the expression of the orphan receptors GPR21, GPR26, GPR39, GPR82 and GPR6, which are related to low-grade inflammation. CONCLUSIONS Our results suggest that GPR21 and GPR82 are modulated by glycine, it shows a possible protective role in the presence of an inflammatory environment in adipocytes, and they could be a therapeutic target to decrease the inflammation in some diseases related to low-grade inflammation such as diabetes, obesity and metabolic syndrome.
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Affiliation(s)
| | - Karla Aidee Aguayo-Cerón
- Laboratorio de Señalización Intracelular, Sección de Estudios de Posgrado, Escuela Superior de Medicina del Instituto Politécnico Nacional, Ciudad de México 11340, Mexico
| | - Cruz Vargas-De-León
- Laboratorio de Señalización Intracelular, Sección de Estudios de Posgrado, Escuela Superior de Medicina del Instituto Politécnico Nacional, Ciudad de México 11340, Mexico
- División de Investigación, Hospital Juárez de México, Ciudad de México 07760, Mexico
| | - Sandra Edith Cabrera-Becerra
- Laboratorio de Señalización Intracelular, Sección de Estudios de Posgrado, Escuela Superior de Medicina del Instituto Politécnico Nacional, Ciudad de México 11340, Mexico
| | - Julio Cesar Almanza-Pérez
- Laboratorio de Farmacología, Departamento de Ciencias de la Salud, DCBS, Universidad Autónoma Metropolitana-Iztapalapa (UAM-I), Ciudad de México 09340, Mexico
| | - Fengyang Huang
- Laboratorio de Investigación en Farmacología, Hospital Infantil de México Federico Gómez (HIMFG), Ciudad de México 06720, Mexico
| | - Santiago Villafaña
- Laboratorio de Señalización Intracelular, Sección de Estudios de Posgrado, Escuela Superior de Medicina del Instituto Politécnico Nacional, Ciudad de México 11340, Mexico
| | - Rodrigo Romero-Nava
- Laboratorio de Señalización Intracelular, Sección de Estudios de Posgrado, Escuela Superior de Medicina del Instituto Politécnico Nacional, Ciudad de México 11340, Mexico
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18
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TRPM8 contributes to sex dimorphism by promoting recovery of normal sensitivity in a mouse model of chronic migraine. Nat Commun 2022; 13:6304. [PMID: 36272975 PMCID: PMC9588003 DOI: 10.1038/s41467-022-33835-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 09/30/2022] [Indexed: 12/25/2022] Open
Abstract
TRPA1 and TRPM8 are transient receptor potential channels expressed in trigeminal neurons that are related to pathophysiology in migraine models. Here we use a mouse model of nitroglycerine-induced chronic migraine that displays a sexually dimorphic phenotype, characterized by mechanical hypersensitivity that develops in males and females, and is persistent up to day 20 in female mice, but disappears by day 18 in male mice. TRPA1 is required for development of hypersensitivity in males and females, whereas TRPM8 contributes to the faster recovery from hypersensitivity in males. TRPM8-mediated antinociception effects required the presence of endogenous testosterone in males. Administration of exogenous testosterone to females and orchidectomized males led to recovery from hypersensitivity. Calcium imaging and electrophysiological recordings in in vitro systems confirmed testosterone activity on murine and human TRPM8, independent of androgen receptor expression. Our findings suggest a protective function of TRPM8 in shortening the time frame of hypersensitivity in a mouse model of migraine.
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19
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Zhang J, Junigan JM, Trinh R, Kavelaars A, Heijnen CJ, Grace PM. HDAC6 Inhibition Reverses Cisplatin-Induced Mechanical Hypersensitivity via Tonic Delta Opioid Receptor Signaling. J Neurosci 2022; 42:7862-7874. [PMID: 36096670 PMCID: PMC9617617 DOI: 10.1523/jneurosci.1182-22.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/20/2022] [Accepted: 09/01/2022] [Indexed: 11/30/2022] Open
Abstract
Peripheral neuropathic pain induced by the chemotherapeutic cisplatin can persist for months to years after treatment. Histone deacetylase 6 (HDAC6) inhibitors have therapeutic potential for cisplatin-induced neuropathic pain since they persistently reverse mechanical hypersensitivity and spontaneous pain in rodent models. Here, we investigated the mechanisms underlying reversal of mechanical hypersensitivity in male and female mice by a 2 week treatment with an HDAC6 inhibitor, administered 3 d after the last dose of cisplatin. Mechanical hypersensitivity in animals of both sexes treated with the HDAC6 inhibitor was temporarily reinstated by a single injection of the neutral opioid receptor antagonist 6β-naltrexol or the peripherally restricted opioid receptor antagonist naloxone methiodide. These results suggest that tonic peripheral opioid ligand-receptor signaling mediates reversal of cisplatin-induced mechanical hypersensitivity after treatment with an HDAC6 inhibitor. Pointing to a specific role for δ opioid receptors (DORs), Oprd1 expression was decreased in DRG neurons following cisplatin administration, but normalized after treatment with an HDAC6 inhibitor. Mechanical hypersensitivity was temporarily reinstated in both sexes by a single injection of the DOR antagonist naltrindole. Consistently, HDAC6 inhibition failed to reverse cisplatin-induced hypersensitivity when DORs were genetically deleted from advillin+ neurons. Mechanical hypersensitivity was also temporarily reinstated in both sexes by a single injection of a neutralizing antibody against the DOR ligand met-enkephalin. In conclusion, we reveal that treatment with an HDAC6 inhibitor induces tonic enkephalin-DOR signaling in peripheral sensory neurons to suppress mechanical hypersensitivity.SIGNIFICANCE STATEMENT Over one-fourth of cancer survivors suffer from intractable painful chemotherapy-induced peripheral neuropathy (CIPN), which can last for months to years after treatment ends. HDAC6 inhibition is a novel strategy to reverse CIPN without negatively interfering with tumor growth, but the mechanisms responsible for persistent reversal are not well understood. We built on evidence that the endogenous opioid system contributes to the spontaneous, apparent resolution of pain caused by nerve damage or inflammation, referred to as latent sensitization. We show that blocking the δ opioid receptor or its ligand enkephalin unmasks CIPN in mice treated with an HDAC6 inhibitor (latent sensitization). Our work provides insight into the mechanisms by which treatment with an HDAC6 inhibitor apparently reverses CIPN.
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Affiliation(s)
- Jixiang Zhang
- Laboratories of Neuroimmunology, Department of Symptom Research, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Jazzmine M Junigan
- Laboratories of Neuroimmunology, Department of Symptom Research, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Ronnie Trinh
- Laboratories of Neuroimmunology, Department of Symptom Research, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Annemieke Kavelaars
- Laboratories of Neuroimmunology, Department of Symptom Research, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Cobi J Heijnen
- Laboratories of Neuroimmunology, Department of Symptom Research, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Peter M Grace
- Laboratories of Neuroimmunology, Department of Symptom Research, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
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20
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Liu YJ, Li YL, Fang ZH, Liao HL, Zhang YY, Lin J, Liu F, Shen JF. NMDARs mediate peripheral and central sensitization contributing to chronic orofacial pain. Front Cell Neurosci 2022; 16:999509. [PMID: 36238833 PMCID: PMC9553029 DOI: 10.3389/fncel.2022.999509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 08/22/2022] [Indexed: 11/28/2022] Open
Abstract
Peripheral and central sensitizations of the trigeminal nervous system are the main mechanisms to promote the development and maintenance of chronic orofacial pain characterized by allodynia, hyperalgesia, and ectopic pain after trigeminal nerve injury or inflammation. Although the pathomechanisms of chronic orofacial pain are complex and not well known, sufficient clinical and preclinical evidence supports the contribution of the N-methyl-D-aspartate receptors (NMDARs, a subclass of ionotropic glutamate receptors) to the trigeminal nociceptive signal processing pathway under various pathological conditions. NMDARs not only have been implicated as a potential mediator of pain-related neuroplasticity in the peripheral nervous system (PNS) but also mediate excitatory synaptic transmission and synaptic plasticity in the central nervous system (CNS). In this review, we focus on the pivotal roles and mechanisms of NMDARs in the trigeminal nervous system under orofacial neuropathic and inflammatory pain. In particular, we summarize the types, components, and distribution of NMDARs in the trigeminal nervous system. Besides, we discuss the regulatory roles of neuron-nonneuronal cell/neuron-neuron communication mediated by NMDARs in the peripheral mechanisms of chronic orofacial pain following neuropathic injury and inflammation. Furthermore, we review the functional roles and mechanisms of NMDARs in the ascending and descending circuits under orofacial neuropathic and inflammatory pain conditions, which contribute to the central sensitization. These findings are not only relevant to understanding the underlying mechanisms, but also shed new light on the targeted therapy of chronic orofacial pain.
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Affiliation(s)
- Ya-Jing Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yue-Ling Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Zhong-Han Fang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Hong-Lin Liao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yan-Yan Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jiu Lin
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Fei Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- *Correspondence: Jie-Fei Shen Fei Liu
| | - Jie-Fei Shen
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- *Correspondence: Jie-Fei Shen Fei Liu
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21
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Ligand-Free Signaling of G-Protein-Coupled Receptors: Relevance to μ Opioid Receptors in Analgesia and Addiction. Molecules 2022; 27:molecules27185826. [PMID: 36144565 PMCID: PMC9503102 DOI: 10.3390/molecules27185826] [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: 07/26/2022] [Revised: 09/04/2022] [Accepted: 09/06/2022] [Indexed: 11/17/2022] Open
Abstract
Numerous G-protein-coupled receptors (GPCRs) display ligand-free basal signaling with potential physiological functions, a target in drug development. As an example, the μ opioid receptor (MOR) signals in ligand-free form (MOR-μ*), influencing opioid responses. In addition, agonists bind to MOR but can dissociate upon MOR activation, with ligand-free MOR-μ* carrying out signaling. Opioid pain therapy is effective but incurs adverse effects (ADRs) and risk of opioid use disorder (OUD). Sustained opioid agonist exposure increases persistent basal MOR-μ* activity, which could be a driving force for OUD and ADRs. Antagonists competitively prevent resting MOR (MOR-μ) activation to MOR-μ*, while common antagonists, such as naloxone and naltrexone, also bind to and block ligand-free MOR-μ*, acting as potent inverse agonists. A neutral antagonist, 6β-naltrexol (6BN), binds to but does not block MOR-μ*, preventing MOR-μ activation only competitively with reduced potency. We hypothesize that 6BN gradually accelerates MOR-μ* reversal to resting-state MOR-μ. Thus, 6BN potently prevents opioid dependence in rodents, at doses well below those blocking antinociception or causing withdrawal. Acting as a ‘retrograde addiction modulator’, 6BN could represent a novel class of therapeutics for OUD. Further studies need to address regulation of MOR-μ* and, more broadly, the physiological and pharmacological significance of ligand-free signaling in GPCRs.
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Dwyer TS, O’Brien JB, Ptak CP, LaVigne JE, Flaherty DP, Watts VJ, Roman DL. Protein-protein interaction-based high throughput screening for adenylyl cyclase 1 inhibitors: Design, implementation, and discovery of a novel chemotype. Front Pharmacol 2022; 13:977742. [PMID: 36147328 PMCID: PMC9486168 DOI: 10.3389/fphar.2022.977742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 08/08/2022] [Indexed: 11/25/2022] Open
Abstract
Genetic and preclinical studies have implicated adenylyl cyclase 1 (AC1) as a potential target for the treatment of chronic inflammatory pain. AC1 activity is increased following inflammatory pain stimuli and AC1 knockout mice show a marked reduction in responses to inflammatory pain. Previous drug discovery efforts have centered around the inhibition of AC1 activity in cell-based assays. In the present study, we used an in vitro approach focused on inhibition of the protein-protein interaction (PPI) between Ca2+/calmodulin (CaM) and AC1, an interaction that is required for activation of AC1. We developed a novel fluorescence polarization (FP) assay focused on the PPI between an AC1 peptide and CaM and used this assay to screen over 23,000 compounds for inhibitors of the AC1-CaM PPI. Next, we used a cellular NanoBiT assay to validate 21 FP hits for inhibition of the AC1-CaM PPI in a cellular context with full-length proteins. Based on efficacy, potency, and selectivity for AC1, hits 12, 13, 15, 18, 20, and 21 were prioritized. We then tested these compounds for inhibition of AC1 activity in cyclic AMP (cAMP) accumulation assays, using HEK293 cells stably expressing AC1. Hit 15 contained a dithiophene scaffold and was of particular interest because it shared structural similarities with our recently reported benzamide series of AC1 inhibitors. We next tested a small set of 13 compounds containing the dithiophene scaffold for structure-activity relationship studies. Although many compounds were non-selective, we observed trends for tuning AC1/AC8 selectivity based on heterocycle type and substituents. Having an ethyl on the central thiophene caused the scaffold to be more selective for AC8. Cyclization of the alkyl substituent fused to the thiophene significantly reduced activity and also shifted selectivity toward AC8. Notably, combining the fused cyclohexane-thiophene ring system with a morpholine heterocycle significantly increased potency at both AC1 and AC8. Through designing a novel FP screen and NanoBiT assay, and evaluating hits in cAMP accumulation assays, we have discovered a novel, potent, dithiophene scaffold for inhibition of the AC1- and AC8-CaM PPI. We also report the most potent fully efficacious inhibitor of AC8 activity known to-date.
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Affiliation(s)
- Tiffany S. Dwyer
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN, United States
| | - Joseph B. O’Brien
- Department of Pharmaceutical Sciences & Experimental Therapeutics, The University of Iowa College of Pharmacy, Iowa City, IA, United States
| | - Christopher P. Ptak
- Nuclear Magnetic Resonance Facility, The University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Justin E. LaVigne
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN, United States
| | - Daniel P. Flaherty
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN, United States
- Purdue Institute for Drug Discovery, West Lafayette, IN, United States
- Purdue Institute for Integrative Neuroscience, West Lafayette, IN, United States
| | - Val J. Watts
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN, United States
- Purdue Institute for Drug Discovery, West Lafayette, IN, United States
- Purdue Institute for Integrative Neuroscience, West Lafayette, IN, United States
- *Correspondence: David L. Roman, ; Val J. Watts,
| | - David L. Roman
- Department of Pharmaceutical Sciences & Experimental Therapeutics, The University of Iowa College of Pharmacy, Iowa City, IA, United States
- Iowa Neuroscience Institute, Iowa City, IA, United States
- Holden Comprehensive Cancer Center, The University of Iowa Hospitals & Clinics, Iowa City, IA, United States
- *Correspondence: David L. Roman, ; Val J. Watts,
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23
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Johnson K, Doucette A, Edwards A, Verdi A, McFarland R, Hulke S, Fowler A, Watts VJ, Klein AH. Reduced activity of adenylyl cyclase 1 attenuates morphine induced hyperalgesia and inflammatory pain in mice. Front Pharmacol 2022; 13:937741. [PMID: 36120355 PMCID: PMC9479488 DOI: 10.3389/fphar.2022.937741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 08/02/2022] [Indexed: 11/29/2022] Open
Abstract
Opioid tolerance, opioid-induced hyperalgesia during repeated opioid administration, and chronic pain are associated with upregulation of adenylyl cyclase activity. The objective of this study was to test the hypothesis that a reduction in adenylyl cyclase 1 (AC1) activity or expression would attenuate morphine tolerance and hypersensitivity, and inflammatory pain using murine models. To investigate opioid tolerance and opioid-induced hyperalgesia, mice were subjected to twice daily treatments of saline or morphine using either a static (15 mg/kg, 5 days) or an escalating tolerance paradigm (10–40 mg/kg, 4 days). Systemic treatment with an AC1 inhibitor, ST03437 (2.5–10 mg/kg, IP), reduced morphine-induced hyperalgesia in mice. Lumbar intrathecal administration of a viral vector incorporating a short-hairpin RNA targeting Adcy1 reduced morphine-induced hypersensitivity compared to control mice. In contrast, acute morphine antinociception, along with thermal paw withdrawal latencies, motor performance, exploration in an open field test, and burrowing behaviors were not affected by intrathecal Adcy1 knockdown. Knockdown of Adcy1 by intrathecal injection also decreased inflammatory mechanical hyperalgesia and increased burrowing and nesting activity after intraplantar administration of Complete Freund’s Adjuvant (CFA) one-week post-injection.
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Affiliation(s)
- Kayla Johnson
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, MN, United States
| | - Alexis Doucette
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, MN, United States
| | - Alexis Edwards
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, MN, United States
| | - Aleeya Verdi
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, MN, United States
| | - Ryan McFarland
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, MN, United States
| | - Shelby Hulke
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, MN, United States
| | - Amanda Fowler
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, MN, United States
| | - Val J. Watts
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
| | - Amanda H. Klein
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, MN, United States
- *Correspondence: Amanda H. Klein,
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24
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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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25
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Gao SH, Tao Y, Zhu Y, Huang H, Shen LL, Gao CY. Activation of Dopamine D2 Receptors Alleviates Neuronal Hyperexcitability in the Lateral Entorhinal Cortex via Inhibition of HCN Current in a Rat Model of Chronic Inflammatory Pain. Neurosci Bull 2022; 38:1041-1056. [PMID: 35705785 PMCID: PMC9468209 DOI: 10.1007/s12264-022-00892-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 04/10/2022] [Indexed: 10/18/2022] Open
Abstract
Functional changes in synaptic transmission from the lateral entorhinal cortex to the dentate gyrus (LEC-DG) are considered responsible for the chronification of pain. However, the underlying alterations in fan cells, which are the predominant neurons in the LEC that project to the DG, remain elusive. Here, we investigated possible mechanisms using a rat model of complete Freund's adjuvant (CFA)-induced inflammatory pain. We found a substantial increase in hyperpolarization-activated/cyclic nucleotide-gated currents (Ih), which led to the hyperexcitability of LEC fan cells of CFA slices. This phenomenon was attenuated in CFA slices by activating dopamine D2, but not D1, receptors. Chemogenetic activation of the ventral tegmental area -LEC projection had a D2 receptor-dependent analgesic effect. Intra-LEC microinjection of a D2 receptor agonist also suppressed CFA-induced behavioral hypersensitivity, and this effect was attenuated by pre-activation of the Ih. Our findings suggest that down-regulating the excitability of LEC fan cells through activation of the dopamine D2 receptor may be a strategy for treating chronic inflammatory pain.
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Affiliation(s)
- Shi-Hao Gao
- Department of Rehabilitation, Daping Hospital, Army Medical University, Chongqing, 400042, China
- Army 953 Hospital, Army Medical University, Shigatse, 857000, China
| | - Yong Tao
- Department of Rehabilitation, Daping Hospital, Army Medical University, Chongqing, 400042, China
| | - Yang Zhu
- Department of Rehabilitation, Daping Hospital, Army Medical University, Chongqing, 400042, China
| | - Hao Huang
- Department of Rehabilitation, Daping Hospital, Army Medical University, Chongqing, 400042, China
| | - Lin-Lin Shen
- Department of Respiratory and Critical Care Medicine, Xinqiao Hospital, Army Medical University, Chongqing, 400037, China.
| | - Chang-Yue Gao
- Department of Rehabilitation, Daping Hospital, Army Medical University, Chongqing, 400042, China.
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Cooper AH, Hedden NS, Prasoon P, Qi Y, Taylor BK. Postsurgical Latent Pain Sensitization Is Driven by Descending Serotonergic Facilitation and Masked by µ-Opioid Receptor Constitutive Activity in the Rostral Ventromedial Medulla. J Neurosci 2022; 42:5870-5881. [PMID: 35701159 PMCID: PMC9337598 DOI: 10.1523/jneurosci.2038-21.2022] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 05/22/2022] [Accepted: 05/27/2022] [Indexed: 01/29/2023] Open
Abstract
Following tissue injury, latent sensitization (LS) of nociceptive signaling can persist indefinitely, kept in remission by compensatory µ-opioid receptor constitutive activity (MORCA) in the dorsal horn of the spinal cord. To demonstrate LS, we conducted plantar incision in mice and then waited 3-4 weeks for hypersensitivity to resolve. At this time (remission), systemic administration of the opioid receptor antagonist/inverse agonist naltrexone reinstated mechanical and heat hypersensitivity. We first tested the hypothesis that LS extends to serotonergic neurons in the rostral ventral medulla (RVM) that convey pronociceptive input to the spinal cord. We report that in male and female mice, hypersensitivity was accompanied by increased Fos expression in serotonergic neurons of the RVM, abolished on chemogenetic inhibition of RVM 5-HT neurons, and blocked by intrathecal injection of the 5-HT3R antagonist ondansetron; the 5-HT2AR antagonist MDL-11 939 had no effect. Second, to test for MORCA, we microinjected the MOR inverse agonist d-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2 (CTAP) and/or neutral opioid receptor antagonist 6β-naltrexol. Intra-RVM CTAP produced mechanical hypersensitivity at both hindpaws; 6β-naltrexol had no effect by itself, but blocked CTAP-induced hypersensitivity. This indicates that MORCA, rather than an opioid ligand-dependent mechanism, maintains LS in remission. We conclude that incision establishes LS in descending RVM 5-HT neurons that drives pronociceptive 5-HT3R signaling in the dorsal horn, and this LS is tonically opposed by MORCA in the RVM. The 5-HT3 receptor is a promising therapeutic target for the development of drugs to prevent the transition from acute to chronic postsurgical pain.SIGNIFICANCE STATEMENT Surgery leads to latent pain sensitization and a compensatory state of endogenous pain control that is maintained long after tissue healing. Here, we show that either chemogenetic inhibition of serotonergic neuron activity in the RVM or pharmacological inhibition of 5-HT3 receptor signaling at the spinal cord blocks behavioral signs of postsurgical latent sensitization. We conclude that MORCA in the RVM opposes descending serotonergic facilitation of LS and that the 5-HT3 receptor is a promising therapeutic target for the development of drugs to prevent the transition from acute to chronic postsurgical pain.
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Affiliation(s)
- Andrew H Cooper
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Naomi S Hedden
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Pranav Prasoon
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Yanmei Qi
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Bradley K Taylor
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
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Farzinpour Z, Liu A, Cao P, Mao Y, Zhang Z, Jin Y. Microglial Engulfment of Spines in the Ventral Zona Incerta Regulates Anxiety-Like Behaviors in a Mouse Model of Acute Pain. Front Cell Neurosci 2022; 16:898346. [PMID: 35910255 PMCID: PMC9337222 DOI: 10.3389/fncel.2022.898346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 06/17/2022] [Indexed: 12/20/2022] Open
Abstract
Although activation of microglial cells is critical in developing brain disorders, their role in anxiety-like behaviors in pain is still vague. This study indicates that alteration of microglia’s neuronal spine engulfment capacity in ventral zona incerta (ZIV) leads to significant pain and anxiety-like behaviors in mice 1-day post-injection of Complete Freud’s Adjuvant (CFA1D). Performing whole-cell patch-clamp recordings in GABAergic neurons in the ZIV (ZIVGABA) in brain slices, we observed decreased activity in ZIvGABA and reduced frequency of the miniature excitatory postsynaptic currents (mEPSCs) in ZIVGABA of CFA1D mice compared with the saline1D mice. Besides, chemogenetic activation of ZIVGABA significantly relieved pain and anxiety-like behaviors in CFA1D mice. Conversely, in naïve mice, chemogenetic inhibition of ZIVGABA induced pain and anxiety-like behaviors. Interestingly, we found changes in the density and morphology of ZIVMicroglia and increased microglial engulfment of spines in ZIV of CFA1D mice. Furthermore, pain sensitization and anxiety-like behaviors were reversed when the ZIVMicroglia of CFA1D-treated mice were chemically inhibited by intra-ZIV minocycline injection, accompanied by the recovery of decreased ZIVGABA excitability. Conclusively, our results provide novel insights that dysregulation of microglial engulfment capacity encodes maladaptation of ZIVGABA, thus promoting the development of anxiety-like behaviors in acute pain.
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Affiliation(s)
- Zahra Farzinpour
- Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - An Liu
- Department of Physiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Peng Cao
- Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yu Mao
- Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Zhi Zhang
- Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- *Correspondence: Zhi Zhang,
| | - Yan Jin
- Stroke Center and Department of Neurology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Yan Jin,
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28
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Alvarez-Bagnarol Y, Marchette RCN, Francis C, Morales MM, Vendruscolo LF. NEURONAL CORRELATES OF HYPERALGESIA AND SOMATIC SIGNS OF HEROIN WITHDRAWAL IN MALE AND FEMALE MICE. eNeuro 2022; 9:ENEURO.0106-22.2022. [PMID: 35728954 PMCID: PMC9267003 DOI: 10.1523/eneuro.0106-22.2022] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 05/17/2022] [Accepted: 06/03/2022] [Indexed: 11/21/2022] Open
Abstract
Opioid withdrawal involves the manifestation of motivational and somatic symptoms. However, the brain structures that are involved in the expression of different opioid withdrawal signs remain unclear. We induced opioid dependence by repeatedly injecting escalating heroin doses in male and female C57BL/6J mice. We assessed hyperalgesia during spontaneous heroin withdrawal and somatic signs of withdrawal that was precipitated by the preferential µ-opioid receptor antagonist naloxone. Heroin-treated mice exhibited significantly higher hyperalgesia and somatic signs than saline-treated mice. Following behavioral assessment, we measured regional changes in brain activity by automated the counting of c-Fos expression (a marker of cellular activity). Using Principal Component Analysis, we determined the association between behavior (hyperalgesia and somatic signs of withdrawal) and c-Fos expression in different brain regions. Hyperalgesia was associated with c-Fos expression in the lateral hypothalamus, central nucleus of the amygdala, ventral tegmental area, parabrachial nucleus, dorsal raphe, and locus coeruleus. Somatic withdrawal was associated with c-Fos expression in the paraventricular nucleus of the thalamus, lateral habenula, dorsal raphe, and locus coeruleus. Thus, hyperalgesia and somatic withdrawal signs were each associated with c-Fos expression in unique sets of brain areas. The expression of c-Fos in the dorsal raphe and locus coeruleus was associated with both hyperalgesia and somatic withdrawal. Understanding common neurobiological mechanisms of acute and protracted opioid withdrawal may help identify new targets for treating this salient aspect of opioid use disorder.SIGNIFICANCE STATEMENTThe public impact of the opioid crisis has prompted an effort to understand the neurobiological mechanisms of opioid use disorder (OUD). The need to avoid withdrawal symptoms is hypothesized to drive compulsive drug-taking and -seeking in OUD. Thus, understanding the mechanisms of acute and protracted opioid withdrawal may help identify new targets for treating this salient aspect of OUD. We reported brain structures that are associated with the expression of hyperalgesia and somatic signs of opioid withdrawal in male and female heroin-dependent mice. Hyperalgesia during spontaneous opioid withdrawal and somatic withdrawal resulted in c-Fos expression in autonomic and limbic brain regions. The expression of c-Fos in the dorsal raphe and locus coeruleus were associated with both hyperalgesia and somatic withdrawal.
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Affiliation(s)
- Yocasta Alvarez-Bagnarol
- Neuronal Networks Section, Integrative Neuroscience Research Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, MD, USA
- Neurobiology of Addiction Section, Integrative Neuroscience Research Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, MD, USA
- Department of Anatomy and Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico
| | - Renata C N Marchette
- Neurobiology of Addiction Section, Integrative Neuroscience Research Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, MD, USA
| | - Chase Francis
- Neuronal Networks Section, Integrative Neuroscience Research Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, MD, USA
| | - Marisela M Morales
- Neuronal Networks Section, Integrative Neuroscience Research Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, MD, USA
| | - Leandro F Vendruscolo
- Neurobiology of Addiction Section, Integrative Neuroscience Research Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, MD, USA
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29
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Güereca YM, Kell PA, Kuhn BL, Hellman N, Sturycz CA, Toledo TA, Huber FA, Demuth M, Lannon EW, Palit S, Shadlow JO, Rhudy JL. The Relationship Between Experienced Discrimination and Pronociceptive Processes in Native Americans: Results From the Oklahoma Study of Native American Pain Risk. THE JOURNAL OF PAIN 2022; 23:1006-1024. [PMID: 35021117 DOI: 10.1016/j.jpain.2021.12.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/30/2021] [Accepted: 12/20/2021] [Indexed: 12/24/2022]
Abstract
Native Americans (NAs) have higher pain rates than the general U.S. population. It has been found that increased central sensitization and reduced pain inhibition are pronociceptive processes that increase pain risk; yet, little attention has focused on the influence of psychosocial factors. Discrimination is a psychosocial factor associated with increased pain in other minoritized groups; however, it is unclear whether it also promotes pain in NAs. This study analyzed data from 269 healthy, pain-free participants (N = 134 non-Hispanic whites [NHWs], N = 135 NAs) from the Oklahoma Study of Native American Pain Risk. Experienced discrimination was measured using the Everyday Discrimination Scale (EDS). Nociceptive processes were measured via static measures of spinal sensitivity (nociceptive flexion reflex [NFR] threshold, 3-stimulation NFR threshold), temporal summation of pain (TS-Pain) and nociceptive flexion reflex (TS-NFR), and conditioned pain modulation of pain (CPM-Pain) and NFR (CPM-NFR). Results demonstrated that greater discrimination was associated with enhanced TS-NFR and impaired CPM-NFR but not static measures of spinal sensitivity or measures of pain modulation (TS-Pain, CPM-Pain). Although the effects of discrimination on outcomes were similar in both groups (not moderated by ethnicity), NAs experienced higher levels of discrimination and therefore discrimination mediated a relationship between ethnicity and impaired CPM-NFR. This indicates experienced discrimination may promote a pain risk phenotype in NAs that involves spinal sensitization resulting from impaired inhibition of spinal nociception without sensitization of pain experience. PERSPECTIVE: This study found that discrimination was associated with spinal sensitization and impaired descending inhibition of spinal nociception. These findings bolster our understanding of how social stressors experienced disproportionately by minoritized groups can contribute to pain outcomes.
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Affiliation(s)
- Yvette M Güereca
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Parker A Kell
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Bethany L Kuhn
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Natalie Hellman
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | | | - Tyler A Toledo
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | | | - Mara Demuth
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Edward W Lannon
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Shreela Palit
- University of Florida, Pain Research and Intervention Center of Excellence, Gainesville, Florida
| | - Joanna O Shadlow
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Jamie L Rhudy
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma.
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30
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Rhudy JL, Huber FA, Toledo TA, Kell PA, Street EN, Shadlow JO. Psychosocial and cardiometabolic predictors of chronic pain onset in Native Americans: serial mediation analyses of 2-year prospective data from the Oklahoma Study of Native American Pain Risk. Pain 2022; 163:e654-e674. [PMID: 34433767 PMCID: PMC8866534 DOI: 10.1097/j.pain.0000000000002458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 07/19/2021] [Indexed: 11/25/2022]
Abstract
ABSTRACT Chronic pain results in considerable suffering, as well as significant economic and societal costs. Previous evidence suggests that Native Americans (NAs) have higher rates of chronic pain than other U.S. racial or ethnic groups, but the mechanisms contributing to this pain disparity are poorly understood. The Oklahoma Study of Native American Pain Risk was developed to address this issue and recruited healthy, pain-free NAs and non-Hispanic Whites. Cross-sectional analyses identified several measures of adversity (eg, trauma and discrimination), cognitive-affective factors (perceived stress and pain-related anxiety/catastrophizing), and cardiometabolic factors (eg, body mass index, blood pressure, and heart rate variability) that were associated with pronociceptive processes (eg, central sensitization, descending inhibition, and hyperalgesia). Every 6-months after enrollment, eligible participants (N = 277) were recontacted and assessed for the onset of chronic pain. This study examines predictors of chronic pain onset in the 222 participants (80%) who responded over the first 2 years. The results show that NAs developed chronic pain at a higher rate than non-Hispanic Whites (OR = 2.902, P < 0.05), even after controlling for age, sex, income, and education. Moreover, serial mediation models identified several potential pathways to chronic pain onset within the NA group. These paths included perceived discrimination, psychological stress, pain-related anxiety, a composite measure of cardiometabolic risk, and impaired descending inhibition of spinal nociception (assessed from conditioned pain modulation of the nociceptive flexion reflex). These results provide the first prospective evidence for a pain disparity in NAs that seems to be promoted by psychosocial, cardiometabolic, and pronociceptive mechanisms.
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Affiliation(s)
- Jamie L. Rhudy
- The University of Tulsa, Department of Psychology, Tulsa, OK
| | | | - Tyler A. Toledo
- The University of Tulsa, Department of Psychology, Tulsa, OK
| | - Parker A. Kell
- The University of Tulsa, Department of Psychology, Tulsa, OK
| | - Erin N. Street
- The University of Tulsa, Department of Psychology, Tulsa, OK
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31
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Endogenous Opioids and Their Role in Stem Cell Biology and Tissue Rescue. Int J Mol Sci 2022; 23:ijms23073819. [PMID: 35409178 PMCID: PMC8998234 DOI: 10.3390/ijms23073819] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 01/25/2023] Open
Abstract
Opioids are considered the oldest drugs known by humans and have been used for sedation and pain relief for several centuries. Nowadays, endogenous opioid peptides are divided into four families: enkephalins, dynorphins, endorphins, and nociceptin/orphanin FQ. They exert their action through the opioid receptors (ORs), transmembrane proteins belonging to the super-family of G-protein-coupled receptors, and are expressed throughout the body; the receptors are the δ opioid receptor (DOR), μ opioid receptor (MOR), κ opioid receptor (KOR), and nociceptin/orphanin FQ receptor (NOP). Endogenous opioids are mainly studied in the central nervous system (CNS), but their role has been investigated in other organs, both in physiological and in pathological conditions. Here, we revise their role in stem cell (SC) biology, since these cells are a subject of great scientific interest due to their peculiar features and their involvement in cell-based therapies in regenerative medicine. In particular, we focus on endogenous opioids’ ability to modulate SC proliferation, stress response (to oxidative stress, starvation, or damage following ischemia–reperfusion), and differentiation towards different lineages, such as neurogenesis, vasculogenesis, and cardiogenesis.
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Scott JA, Soto-Velasquez M, Hayes MP, LaVigne JE, Miller HR, Kaur J, Ejendal KFK, Watts VJ, Flaherty DP. Optimization of a Pyrimidinone Series for Selective Inhibition of Ca 2+/Calmodulin-Stimulated Adenylyl Cyclase 1 Activity for the Treatment of Chronic Pain. J Med Chem 2022; 65:4667-4686. [PMID: 35271288 PMCID: PMC9390083 DOI: 10.1021/acs.jmedchem.1c01759] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Adenylyl cyclase type 1 (AC1) is involved in signaling for chronic pain sensitization in the central nervous system and is an emerging target for the treatment of chronic pain. AC1 and a closely related isoform AC8 are also implicated to have roles in learning and memory signaling processes. Our team has carried out cellular screening for inhibitors of AC1 yielding a pyrazolyl-pyrimidinone scaffold with low micromolar potency against AC1 and selectivity versus AC8. Structure-activity relationship (SAR) studies led to analogues with cellular IC50 values as low as 0.25 μM, selectivity versus AC8 and other AC isoforms as well as other common neurological targets. A representative analogue displayed modest antiallodynic effects in a mouse model of inflammatory pain. This series represents the most potent and selective inhibitors of Ca2+/calmodulin-stimulated AC1 activity to date with improved drug-like physicochemical properties making them potential lead compounds for the treatment of inflammatory pain.
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Affiliation(s)
- Jason A Scott
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana 47907, United States
| | - Monica Soto-Velasquez
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana 47907, United States
| | - Michael P Hayes
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana 47907, United States
| | - Justin E LaVigne
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana 47907, United States
| | - Heath R Miller
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jatinder Kaur
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana 47907, United States
| | - Karin F K Ejendal
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana 47907, United States
| | - Val J Watts
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana 47907, United States
- Purdue Institute for Drug Discovery, West Lafayette, Indiana 47907, United States
- Purdue Institute for Integrative Neuroscience, 207 South Martin Jischke Dr. West Lafayette, Indiana 47907, United States
| | - Daniel P Flaherty
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana 47907, United States
- Purdue Institute for Drug Discovery, West Lafayette, Indiana 47907, United States
- Purdue Institute for Integrative Neuroscience, 207 South Martin Jischke Dr. West Lafayette, Indiana 47907, United States
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Scarlata MJ, Keeley RJ, Carmack SA, Tsai PJ, Vendruscolo JCM, Lu H, Koob GF, Vendruscolo LF, Stein EA. Cingulate circuits are associated with escalation of heroin use and naloxone-induced increases in heroin self-administration. ADDICTION NEUROSCIENCE 2022; 1:100002. [PMID: 37323812 PMCID: PMC10270679 DOI: 10.1016/j.addicn.2021.100002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Opioid use disorder (OUD) is defined as a compulsion to seek and take opioids, loss of control over intake and the development of a negative emotional state when access to opioids is denied. Using functional magnetic resonance imaging (fMRI) data in a rat model of OUD, we demonstrate that the escalation of heroin self-administration (SA) and the increased heroin SA following an injection of an opioid receptor antagonist (naloxone) are associated with changes in distinct brain circuits, centered on the cingulate cortex (Cg). Here, SA escalation score was negatively associated with changes in resting state functional connectivity (rsFC) between the Cg and the dorsal striatum. Conversely, increased heroin SA following naloxone injection, was associated with increased connectivity between the Cg and the extended amygdala and hypothalamus. Naloxone-induced increased SA was also positively associated with changes in the amplitude of low frequency fluctuations within the Cg, a measure of spontaneous neuronal activity. Characterizing the distinct brain circuit and behavior changes associated with different facets of addiction increases our understanding of OUD and may provide insight into addiction prevention and treatment.
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Affiliation(s)
- MJ Scarlata
- Neuroimaging Research Branch, National Institute on Drug Abuse, United States of America
| | - RJ Keeley
- Neuroimaging Research Branch, National Institute on Drug Abuse, United States of America
| | - SA Carmack
- Integrative Neuroscience Research Branch, National Institute on Drug Abuse (NIDA), Intramural Research Program, NIH, Baltimore, MD, United States of America
| | - P-J Tsai
- Neuroimaging Research Branch, National Institute on Drug Abuse, United States of America
| | - JCM Vendruscolo
- Integrative Neuroscience Research Branch, National Institute on Drug Abuse (NIDA), Intramural Research Program, NIH, Baltimore, MD, United States of America
| | - H Lu
- Neuroimaging Research Branch, National Institute on Drug Abuse, United States of America
| | - GF Koob
- Integrative Neuroscience Research Branch, National Institute on Drug Abuse (NIDA), Intramural Research Program, NIH, Baltimore, MD, United States of America
| | - LF Vendruscolo
- Integrative Neuroscience Research Branch, National Institute on Drug Abuse (NIDA), Intramural Research Program, NIH, Baltimore, MD, United States of America
| | - EA Stein
- Neuroimaging Research Branch, National Institute on Drug Abuse, United States of America
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Cooper AH, Hedden NS, Corder G, Lamerand SR, Donahue RR, Morales-Medina JC, Selan L, Prasoon P, Taylor BK. Endogenous µ-opioid receptor activity in the lateral and capsular subdivisions of the right central nucleus of the amygdala prevents chronic postoperative pain. J Neurosci Res 2022; 100:48-65. [PMID: 33957003 PMCID: PMC8571119 DOI: 10.1002/jnr.24846] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 03/29/2021] [Indexed: 01/03/2023]
Abstract
Tissue injury induces a long-lasting latent sensitization (LS) of spinal nociceptive signaling that is kept in remission by an opposing µ-opioid receptor (MOR) constitutive activity. To test the hypothesis that supraspinal sites become engaged, we induced hindpaw inflammation, waited 3 weeks for mechanical hypersensitivity to resolve, and then injected the opioid receptor inhibitors naltrexone, CTOP or β-funaltrexamine subcutaneously, and/or into the cerebral ventricles. Intracerebroventricular injection of each inhibitor reinstated hypersensitivity and produced somatic signs of withdrawal, indicative of LS and endogenous opioid dependence, respectively. In naïve or sham controls, systemic naloxone (3 mg/kg) produced conditioned place aversion, and systemic naltrexone (3 mg/kg) increased Fos expression in the central nucleus of the amygdala (CeA). In LS animals tested 3 weeks after plantar incision, systemic naltrexone reinstated mechanical hypersensitivity and produced an even greater increase in Fos than in sham controls, particularly in the capsular subdivision of the right CeA. One third of Fos+ profiles co-expressed protein kinase C delta (PKCδ), and 35% of PKCδ neurons co-expressed tdTomato+ in Oprm1Cre ::tdTomato transgenic mice. CeA microinjection of naltrexone (1 µg) reinstated mechanical hypersensitivity only in male mice and did not produce signs of somatic withdrawal. Intra-CeA injection of the MOR-selective inhibitor CTAP (300 ng) reinstated hypersensitivity in both male and female mice. We conclude that MORs in the capsular subdivision of the right CeA prevent the transition from acute to chronic postoperative pain.
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Affiliation(s)
- Andrew H. Cooper
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, and the Pittsburgh Project to end Opioid Misuse, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Naomi S. Hedden
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, and the Pittsburgh Project to end Opioid Misuse, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Gregory Corder
- Department of Psychiatry and Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sydney R. Lamerand
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, and the Pittsburgh Project to end Opioid Misuse, University of Pittsburgh, Pittsburgh, PA 15213, USA,Center for Neurosciences at the University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Renee R. Donahue
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA
| | | | - Lindsay Selan
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, and the Pittsburgh Project to end Opioid Misuse, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Pranav Prasoon
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, and the Pittsburgh Project to end Opioid Misuse, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Bradley K. Taylor
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, and the Pittsburgh Project to end Opioid Misuse, University of Pittsburgh, Pittsburgh, PA 15213, USA,Corresponding author: Bradley K. Taylor, 200 Lothrop Street, BSTW1455, Department of Anesthesiology & Perioperative Pain Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA,
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Laboureyras E, Boujema MB, Mauborgne A, Simmers J, Pohl M, Simonnet G. Fentanyl-induced hyperalgesia and analgesic tolerance in male rats: common underlying mechanisms and prevention by a polyamine deficient diet. Neuropsychopharmacology 2022; 47:599-608. [PMID: 34621016 PMCID: PMC8674360 DOI: 10.1038/s41386-021-01200-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 09/20/2021] [Accepted: 09/24/2021] [Indexed: 01/03/2023]
Abstract
Opioids are a mainstay of pain management but can induce unwanted effects, including analgesic tolerance and paradoxical hyperalgesia, either of which leads to increased pain. Clinically, however, the relationship between these two phenomena remains elusive. By evaluating changes in mechanical nociceptive threshold in male rats, we found that in contrast to a purely analgesic control response to a single subcutaneous administration of fentanyl (25 μg/kg), in rats subjected to inflammatory pain 2 weeks previously (Day0), the same test dose (D13) induced a bi-phasic response: initial decreased analgesia (tolerance) followed by hyperalgesia lasting several hours. Both the tolerance and hyperalgesia were further enhanced in rats that had additionally received fentanyl on D0. The dose-response profiles (5 fg to 50 μg/kg) of pain- and opioid-experienced rats were very different from pain/drug-naive rats. At ultra-low fentanyl doses (<5 ng/kg and <500 ng/kg for naïve control and pain/drug-experienced rats, respectively), solely hyperalgesia was observed in all cases. At higher doses, which now produced analgesia alone in naive rats, reduced analgesia (tolerance) coupled with hyperalgesia occurred in pain/fentanyl-experienced rats, with both phases increasing with dose. Transcriptomic and pharmacological data revealed that an overactivation of the spinal N-methyl-D-aspartate receptor-inducible NO synthase cascade plays a critical role in both acute tolerance and hyperalgesia, and together with the finding that the magnitudes of analgesia and associated hyperalgesia are negatively correlated, is indicative of closely related phenomena. Finally, a polyamine deficient diet prevented inducible NO synthase transcript upregulation, restored fentanyl's analgesic efficacy and suppressed the emergence of hyperalgesia.
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Affiliation(s)
- Emilie Laboureyras
- grid.462004.40000 0004 0383 7404Univ. de Bordeaux, INCIA, 33076 Bordeaux, France ,grid.462004.40000 0004 0383 7404CNRS, INCIA, UMR 5287, 33076 Bordeaux, France
| | - Meric Ben Boujema
- grid.462004.40000 0004 0383 7404Univ. de Bordeaux, INCIA, 33076 Bordeaux, France ,grid.462004.40000 0004 0383 7404CNRS, INCIA, UMR 5287, 33076 Bordeaux, France
| | - Annie Mauborgne
- grid.462844.80000 0001 2308 1657Univ. Pierre et Marie Curie, INSERM UMRS 975, 75013 Paris, France
| | - John Simmers
- grid.462004.40000 0004 0383 7404Univ. de Bordeaux, INCIA, 33076 Bordeaux, France ,grid.462004.40000 0004 0383 7404CNRS, INCIA, UMR 5287, 33076 Bordeaux, France
| | - Michel Pohl
- grid.508487.60000 0004 7885 7602Univ. Paris Descartes, INSERM UMR 894, 75014 Paris, France
| | - Guy Simonnet
- Univ. de Bordeaux, INCIA, 33076, Bordeaux, France. .,CNRS, INCIA, UMR 5287, 33076, Bordeaux, France.
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Shiers S, Elahi H, Hennen S, Price TJ. Evaluation of calcium-sensitive adenylyl cyclase AC1 and AC8 mRNA expression in the anterior cingulate cortex of mice with spared nerve injury neuropathy. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2022; 11:100081. [PMID: 35005298 PMCID: PMC8715370 DOI: 10.1016/j.ynpai.2021.100081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 12/01/2021] [Accepted: 12/15/2021] [Indexed: 12/19/2022]
Abstract
AC1 and AC8 are widely expressed in many regions of the mouse brain including the hippocampus, ACC, medial prefrontal cortex and midbrain regions, but AC1 is more highly expressed. Findings suggest a potential role for AC8 in anxiety-like behaviors caused by spared nerve injury in mice. SNI causes an increase in AC8 mRNA expression in NMDAR-2B (Nr2b) positive neurons in the contralateral ACC but does not affect AC1 mRNA expression.
The anterior cingulate cortex (ACC) is a critical region of the brain for the emotional and affective components of pain in rodents and humans. Hyperactivity in this region has been observed in neuropathic pain states in both patients and animal models and ablation of this region from cingulotomy, or inhibition with genetics or pharmacology can diminish pain and anxiety. Two adenylyl cyclases (AC), AC1 and AC8 play an important role in regulating nociception and anxiety-like behaviors through an action in the ACC, as genetic and pharmacological targeting of these enzymes reduces mechanical hypersensitivity and anxiety-like behavior, respectively. However, the distribution of these ACs in the ACC has not been studied in the context of neuropathic pain. To address this gap in knowledge, we conducted RNAscope in situ hybridization to assess AC1 and AC8 mRNA distribution in mice with spared nerve injury (SNI). Given the key role of AC1 in nociception in neuropathic, inflammatory and visceral pain animal models, we hypothesized that AC1 would be upregulated in the ACC of mice following nerve injury. This hypothesis was also founded on data showing increased AC1 expression in the ACC of mice with zymosan-induced visceral inflammation. We found that AC1 and AC8 are widely expressed in many regions of the mouse brain including the hippocampus, ACC, medial prefrontal cortex and midbrain regions, but AC1 is more highly expressed. Contrary to our hypothesis, SNI causes an increase in AC8 mRNA expression in NMDAR-2B (Nr2b) positive neurons in the contralateral ACC but does not affect AC1 mRNA expression. Our findings show that changes in Adcy1 mRNA expression in the ACC are insufficient to explain the important role of this AC in mechanical hypersensitivity in mice following nerve injury and suggest a potential unappreciated role of AC8 in regulation of ACC synaptic changes after nerve injury.
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Affiliation(s)
- Stephanie Shiers
- The University of Texas at Dallas, Center for Advanced Pain Studies and Department of Neuroscience, Richardson, TX, USA
| | - Hajira Elahi
- The University of Texas at Dallas, Center for Advanced Pain Studies and Department of Neuroscience, Richardson, TX, USA
| | | | - Theodore J Price
- The University of Texas at Dallas, Center for Advanced Pain Studies and Department of Neuroscience, Richardson, TX, USA
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37
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Zhang WW, Cao H, Li Y, Fu XJ, Zhang YQ. Peripheral ablation of type Ⅲ adenylyl cyclase induces hyperalgesia and eliminates KOR-mediated analgesia in mice. JCI Insight 2021; 7:153191. [PMID: 34914639 PMCID: PMC8855833 DOI: 10.1172/jci.insight.153191] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 12/15/2021] [Indexed: 11/17/2022] Open
Abstract
Ca2+/calmodulin-stimulated group Ⅰ adenylyl cyclase (AC) isoforms AC1 and AC8 have been involved in nociceptive processing and morphine responses. However, whether AC3, another member of group I ACs, is involved in nociceptive transmission and regulates opioid receptor signaling remain elusive. Here we report that conditional knockout of AC3 (AC3CKO) in L3 and L4 DRGs robustly facilitates the mouse nociceptive responses, decreases voltage-gated potassium (Kv) channel currents and increases neuronal excitability. Also, AC3CKO eliminates the analgesic effect of κ opioid receptor (KOR) agonist and its inhibition on Kv channel by classical Gαi/o signaling or nonclassical direct interaction of KOR and AC3 proteins. Interestingly, significantly upregulated AC1 level and cAMP concentration are detected in AC3 deficient DRGs. Inhibition of AC1 completely reversed cAMP upregulation, neuronal excitability enhancement and nociceptive behavioral hypersensitivity in AC3CKO mice. Our findings suggest a crucial role of peripheral AC3 in nociceptive modulation and KOR opioid analgesia.
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Affiliation(s)
- Wen-Wen Zhang
- Department of Translational Neurosciences, Fudan University, Shanghai, China
| | - Hong Cao
- Department of Translational Neurosciences, Fudan University, Shanghai, China
| | - Yang Li
- College of Intelligence and Information Engineering, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Xian-Jun Fu
- Qingdao Academy of Chinese Medical Science, Shandong University of Traditional Chinese Medicine, Qingdao, China
| | - Yu-Qiu Zhang
- Department of Translational Neurosciences, Fudan University, Shanghai, China
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38
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Serrano NE, Saputra SG, Íbias J, Company M, Nazarian A. Pain-induced impulsivity is sexually dimorphic and mu-opioid receptor sensitive in rats. Psychopharmacology (Berl) 2021; 238:3447-3462. [PMID: 34427720 DOI: 10.1007/s00213-021-05963-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 08/10/2021] [Indexed: 12/13/2022]
Abstract
RATIONALE AND OBJECTIVES Pain sensation can negatively impact cognitive function, including impulsivity. Pain-induced changes in impulsivity can contribute to development of psychiatric comorbidities found in those with chronic pain conditions. The goal of this study was to determine whether complete Freund's adjuvant (CFA)-induced pain manipulation enhances impulsivity in rats. Whether the pain-induced impulsivity is sexually dimorphic, and if mu-opioid receptors play a role in these processes. METHODS Male and female rats were screened for trait impulsivity and designated as high or low impulsive using a delay discounting task. Rats then received a hind paw injection of CFA, and their impulsivity was assessed for 16 days. The effects of morphine on impulsivity were also examined. In a separate experiment, rats were pretreated with beta-funaltrexamine (β-FNA) to determine the role of mu-opioid receptors on impulsivity. RESULTS CFA treatment increased impulsivity in males and females. The onset of CFA-induced impulsivity was faster in high impulsive females than males. Morphine blocked CFA-induced impulsivity in both sexes in a dose- and time-dependent manner. β-FNA prevented the actions of morphine on CFA-induced impulsivity in high impulsive males, but not high impulsive females. Moreover, β-FNA increased CFA-induced impulsivity in morphine naïve males, but not females. CONCLUSION These findings demonstrate unique sex differences in CFA-induced impulsivity, response to morphine, and the impact of mu-opioid receptors. A better understanding of cognitive deficits and their mechanisms can provide insight into the development of substance abuse and psychiatric comorbidities that occur in people with chronic pain.
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Affiliation(s)
- Nidia Espinoza Serrano
- Department of Pharmaceutical Sciences, Western University of Health Sciences, 309 E. Second Street, Pomona, CA, 91766, USA
| | - Samuel G Saputra
- Department of Pharmaceutical Sciences, Western University of Health Sciences, 309 E. Second Street, Pomona, CA, 91766, USA
| | - Javier Íbias
- Departamento de Metodologίa de Las Ciencias del Comportamiento, Facultad de Psicologίa, Universidad Nacional de Educacίon a Distancia (UNED), 28040, Madrid, Spain
| | - Matthew Company
- Department of Pharmaceutical Sciences, Western University of Health Sciences, 309 E. Second Street, Pomona, CA, 91766, USA
| | - Arbi Nazarian
- Department of Pharmaceutical Sciences, Western University of Health Sciences, 309 E. Second Street, Pomona, CA, 91766, USA.
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39
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Gerum M, Simonin F. Behavioral characterization, potential clinical relevance and mechanisms of latent pain sensitization. Pharmacol Ther 2021; 233:108032. [PMID: 34763010 DOI: 10.1016/j.pharmthera.2021.108032] [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: 04/16/2021] [Revised: 10/22/2021] [Accepted: 11/03/2021] [Indexed: 10/19/2022]
Abstract
Chronic pain is a debilitating disorder that can occur as painful episodes that alternates with bouts of remission and occurs despite healing of the primary insult. Those episodes are often triggered by stressful events. In the last decades, a similar situation has been evidenced in a wide variety of rodent models (including inflammatory pain, neuropathy and opioid-induced hyperalgesia) where animals develop a chronic latent hyperalgesia that silently persists after behavioral signs of pain resolution. This state, referred as latent pain sensitization, is due to the compensatory activation of antinociceptive systems, such as the opioid system or NPY and its receptors. A transitory phase of hyperalgesia can then be reinstated by pharmacological or genetic blockade of these antinociceptive systems or by submitting animals to acute stress. Those observations reveal that there is a constant endogenous analgesia responsible for chronic pain inhibition that might paradoxically contribute to maintain this maladaptive state and could then participate to the transition from acute to chronic pain. Thus, demonstration of the existence of this phenomenon in humans and a better understanding of the mechanisms by which latent pain sensitization develops and maintains over long periods of time will be of particular interest to help identifying new therapeutic strategies and targets for chronic pain treatment. The present review aims to recapitulate behavioral expression, potential clinical relevance, cellular mechanisms and intracellular signaling pathways involved so far in latent pain sensitization.
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Affiliation(s)
- Manon Gerum
- Biotechnologie et Signalisation Cellulaire, UMR7242 CNRS, Université de Strasbourg, Institut du Médicament de Strasbourg, Illkirch-Graffenstaden, France
| | - Frédéric Simonin
- Biotechnologie et Signalisation Cellulaire, UMR7242 CNRS, Université de Strasbourg, Institut du Médicament de Strasbourg, Illkirch-Graffenstaden, France.
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Rhudy JL, Kuhn BL, Demuth MJ, Huber FA, Hellman N, Toledo TA, Lannon EW, Palit S, Payne MF, Sturycz CA, Kell PA, Guereca YM, Street EN, Shadlow JO. Are Cardiometabolic Markers of Allostatic Load Associated With Pronociceptive Processes in Native Americans?: A Structural Equation Modeling Analysis From the Oklahoma Study of Native American Pain Risk. THE JOURNAL OF PAIN 2021; 22:1429-1451. [PMID: 34033965 PMCID: PMC8578174 DOI: 10.1016/j.jpain.2021.04.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 04/07/2021] [Accepted: 04/26/2021] [Indexed: 10/21/2022]
Abstract
Native Americans (NAs) experience higher rates of chronic pain than the general U.S. population, but the risk factors for this pain disparity are unknown. NAs also experience high rates of stressors and cardiovascular and metabolic health disparities (eg, diabetes, cardiovascular disease) consistent with allostatic load (stress-related wear-and-tear on homeostatic systems). Given that allostatic load is associated with chronic pain, then allostatic load may contribute to their pain disparity. Data from 302 healthy, pain-free men and women (153 NAs, 149 non-Hispanic Whites [NHW]) were analyzed using structural equation modeling to determine whether cardiometabolic allostatic load (body mass index, blood pressure, heart rate variability) mediated the relationship between NA ethnicity and experimental measures of pronociceptive processes: temporal summation of pain (TS-pain) and the nociceptive flexion reflex (TS-NFR), conditioned pain modulation of pain (CPM-pain) and NFR (CPM-NFR), and pain tolerance. Results indicated that NAs experienced greater cardiometabolic allostatic load that was related to enhanced TS-NFR and impaired CPM-NFR. Cardiometabolic allostatic load was unrelated to measures of pain perception (CPM-pain, TS-pain, pain sensitivity). This suggests cardiometabolic allostatic load may promote spinal sensitization in healthy NAs, that is not concomitant with pain sensitization, perhaps representing a unique pain risk phenotype in NAs. PERSPECTIVE: Healthy, pain-free Native Americans experienced greater cardiometabolic allostatic load that was associated with a pronociceptive pain phenotype indicative of latent spinal sensitization (ie, spinal sensitization not associated with hyperalgesia). This latent spinal sensitization could represent a pain risk phenotype for this population.
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Affiliation(s)
- Jamie L Rhudy
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma.
| | - Bethany L Kuhn
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Mara J Demuth
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | | | - Natalie Hellman
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Tyler A Toledo
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Edward W Lannon
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Shreela Palit
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma; Pain Research and Intervention Center of Excellence, University of Florida, Gainesville, Florida
| | - Michael F Payne
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma; Cincinnati Children's Hospital Medical Center, Department of Pediatrics, Division of Behavioral Medicine & Clinical Psychology, Cincinnati, Ohio
| | | | - Parker A Kell
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Yvette M Guereca
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Erin N Street
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
| | - Joanna O Shadlow
- Department of Psychology, The University of Tulsa, Tulsa, Oklahoma
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Ostrom KF, LaVigne JE, Brust TF, Seifert R, Dessauer CW, Watts VJ, Ostrom RS. Physiological Roles of Mammalian Transmembrane Adenylyl Cyclase Isoforms. Physiol Rev 2021; 102:815-857. [PMID: 34698552 DOI: 10.1152/physrev.00013.2021] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Adenylyl cyclases (ACs) catalyze the conversion of ATP to the ubiquitous second messenger cAMP. Mammals possess nine isoforms of transmembrane ACs, dubbed AC1-9, that serve as major effector enzymes of G protein-coupled receptors. The transmembrane ACs display varying expression patterns across tissues, giving potential for them having a wide array of physiologic roles. Cells express multiple AC isoforms, implying that ACs have redundant functions. Furthermore, all transmembrane ACs are activated by Gαs so it was long assumed that all ACs are activated by Gαs-coupled GPCRs. AC isoforms partition to different microdomains of the plasma membrane and form prearranged signaling complexes with specific GPCRs that contribute to cAMP signaling compartments. This compartmentation allows for a diversity of cellular and physiological responses by enabling unique signaling events to be triggered by different pools of cAMP. Isoform specific pharmacological activators or inhibitors are lacking for most ACs, making knockdown and overexpression the primary tools for examining the physiological roles of a given isoform. Much progress has been made in understanding the physiological effects mediated through individual transmembrane ACs. GPCR-AC-cAMP signaling pathways play significant roles in regulating functions of every cell and tissue, so understanding each AC isoform's role holds potential for uncovering new approaches for treating a vast array of pathophysiological conditions.
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Affiliation(s)
- Katrina F Ostrom
- W. M. Keck Science Department, Claremont McKenna College, Claremont, CA, United States
| | - Justin E LaVigne
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
| | - Tarsis F Brust
- Department of Pharmaceutical Sciences, Palm Beach Atlantic University, West Palm Beach, FL, United States
| | - Roland Seifert
- Institute of Pharmacology, Hannover Medical School, Hannover, Germany
| | - Carmen W Dessauer
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas, United States
| | - Val J Watts
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States.,Purdue Institute for Drug Discovery, Purdue University, West Lafayette, IN, United States.,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States
| | - Rennolds S Ostrom
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, United States
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Takemura H, Kushimoto K, Horii Y, Fujita D, Matsuda M, Sawa T, Amaya F. IGF1-driven induction of GPCR kinase 2 in the primary afferent neuron promotes resolution of acute hyperalgesia. Brain Res Bull 2021; 177:305-315. [PMID: 34687776 DOI: 10.1016/j.brainresbull.2021.10.011] [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: 03/27/2021] [Revised: 09/07/2021] [Accepted: 10/18/2021] [Indexed: 10/20/2022]
Abstract
Dynamic regulation of G-protein-coupled receptor (GPCR) kinase 2 (GRK2) expression restores cellular function by protecting from overstimulation via GPCR and non-GPCR signaling. In the primary afferent neurons, GRK2 negatively regulates nociceptive tone. The present study tested the hypothesis that induction of GRK2 in the primary afferent neurons contributes to the resolution of acute pain after tissue injury. GRK2 expression in the dorsal root ganglion (DRG) was analyzed at 1 and 7 days after the incision. Intraperitoneal administration of a GRK2 inhibitor was performed 7 days post-incision in male Sprague-Dawley rats who underwent plantar incisions to analyze the pain-related behavioral effect of the GRK2 inhibitor. Separately, GRK2 expression was analyzed after injecting insulin-like growth factor 1 (IGF1) into the rat hind paw. In addition, an IGF1 receptor (IGF1R) inhibitor was administered in the plantar incision rats to determine its effect on the incision-induced hyperalgesia and GRK2 expression. Plantar incision induced an increase in GRK2 in the DRG at 7 days, but not at 1 day post-incision. Acute hyperalgesia after the plantar incision disappeared by 7 days post-incision. Intraperitoneal injection of the GRK2 inhibitor at this time reinstated mechanical hyperalgesia, although the GRK2 inhibitor did not produce hyperalgesia in naive rats. After the incision, IGF1 expression increased in the paw, but not in the DRG. Intraplantar injection of IGF1 increased GRK2 expression in the ipsilateral DRG. IGF1R inhibitor administration prevented both the induction of GRK2 and resolution of hyperalgesia after the plantar incision. These findings demonstrate that induction of GRK2 expression driven by tissue IGF1 has potent analgesic effects and produces resolution of hyperalgesia after tissue injury. Dysregulation of IGF1-GRK2 signaling could potentially lead to failure of the spontaneous resolution of acute pain and, hence, development of chronic pain after surgery.
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Affiliation(s)
- Hitomi Takemura
- Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan; Research Unit for the Neurobiology of Pain, Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Kohsuke Kushimoto
- Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan; Research Unit for the Neurobiology of Pain, Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Yasuhiko Horii
- Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan; Research Unit for the Neurobiology of Pain, Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Daisuke Fujita
- Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan; Research Unit for the Neurobiology of Pain, Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Megumi Matsuda
- Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan; Research Unit for the Neurobiology of Pain, Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Teiji Sawa
- Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Fumimasa Amaya
- Research Unit for the Neurobiology of Pain, Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan; Department of Pain Management and Palliative Care Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan.
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43
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He Y, Shi Z, Kashyap Y, Messing RO, Wang ZJ. Protein kinase Cδ as a neuronal mechanism for headache in a chronic intermittent nitroglycerin model of migraine in mice. Pain 2021; 162:2499-2511. [PMID: 34108435 PMCID: PMC8448952 DOI: 10.1097/j.pain.0000000000002353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 05/25/2021] [Indexed: 12/15/2022]
Abstract
ABSTRACT Migraine is one of the most common neurological disorders characterized by recurrent attacks of typically throbbing and unilateral headaches, affecting up to 20% of the population worldwide. Despite the high prevalence and severity of this primary headache disorder, it remains to be a challenge to fully understand and treat migraine headaches. By characterizing and validating a mouse migraine model, this study aimed to investigate the functional contribution of protein kinase C (PKC) isoforms in migraine. In this study, we identified the presence of migraine-like ongoing pain in mice after chronic intermittent treatment with nitroglycerin (NTG). The peptide antagonist of calcitonin gene-related peptide α-CGRP (8-37), but not topiramate nor sumatriptan, effectively blocked ongoing pain and elicited pain relief-induced conditioned place preference in NTG-treated mice. Prominent activation of PKCδ was observed in chronic NTG-treated mice. Functional inhibition of PKCδ significantly attenuated ongoing spontaneous pain in chronic NTG-treated mice. Furthermore, we recapitulated the NTG-triggered migraine behavior in wild-type mice, but not in PKCδ-null mice. In response to repeated administration of NTG, ongoing spontaneous pain was not developed in mice lacking the specific PKC isoform. This study identified the presence of ongoing pain in mice treated with NTG, a known human migraine trigger that closely resembles the common manifestation of spontaneous migraine attacks in humans. These findings demonstrated a critical regulatory role of PKCδ in migraine pathophysiology, which may offer new pharmacological targets for antimigraine treatment.
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Affiliation(s)
- Ying He
- Department of Pharmaceutical Sciences and Center for Biomolecular Science, University of Illinois, Chicago, IL 60612
| | - Zuoxiao Shi
- Department of Pharmaceutical Sciences and Center for Biomolecular Science, University of Illinois, Chicago, IL 60612
| | - Yavnika Kashyap
- Department of Pharmaceutical Sciences and Center for Biomolecular Science, University of Illinois, Chicago, IL 60612
| | - Robert O. Messing
- Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas, Austin, Texas, USA
| | - Zaijie Jim Wang
- Department of Pharmaceutical Sciences and Center for Biomolecular Science, University of Illinois, Chicago, IL 60612
- Department of Neurology & Rehabilitation, University of Illinois, Chicago, IL 60612
- Department of Bioengineering, University of Illinois, Chicago, IL 60607
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44
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Broad opioid antagonism amplifies disruption of locomotor function following therapy-like hindlimb stretching in spinal cord injured rats. Spinal Cord 2021; 60:312-319. [PMID: 34561547 DOI: 10.1038/s41393-021-00705-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 09/01/2021] [Accepted: 09/02/2021] [Indexed: 11/08/2022]
Abstract
STUDY DESIGN Preclinical pilot study. OBJECTIVES To test the hypothesis that spinal opioidergic circuitry contributes to muscle stretch-induced locomotor deficits. SETTING Kentucky Spinal Cord Injury Research Center, Louisville, KY, USA. METHODS A pilot study with eight female Sprague-Dawley rats that received 25 g-cm T10 contusion injuries and recovered for 5 weeks. Rats were divided into two groups with one group receiving subcutaneous injections of naltrexone dissolved in saline (15 mg/kg) or an equal volume of saline. Each group received a daily 24-minute stretching protocol during weeks 6, 8, and 11 post-injury. Locomotor function was assessed throughout using the BBB Open Field Locomotor Scale. RESULTS Consistent with previous findings, stretching reduced locomotor function in both naltrexone and saline groups. However, the loss of locomotor function appeared earlier in the naltrexone group. Animals in both groups had a similar rate of recovery following the termination of stretching. Interestingly, the administration of naltrexone did not influence acute thermal cutaneous nociceptive responses as measured by a tail-flick assay but caused a significant increase in spasticity following stretch. CONCLUSIONS The results of this study suggest that the endogenous opioid system plays a role in modulating the negative impact of muscle stretch on spinal cord motor circuitry that is vulnerable due to loss of descending input. The observed actions of the broad-spectrum opioid antagonist naltrexone imply that pharmaceuticals targeting the endogenous opioid system post-SCI may have unintended consequences.
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Kell PA, Hellman N, Huber FA, Lannon EW, Kuhn BL, Sturycz CA, Toledo TA, Demuth MJ, Hahn BJ, Shadlow JO, Rhudy JL. The Relationship Between Adverse Life Events and Endogenous Inhibition of Pain and Spinal Nociception: Findings From the Oklahoma Study of Native American Pain Risk (OK-SNAP). THE JOURNAL OF PAIN 2021; 22:1097-1110. [PMID: 33819573 PMCID: PMC8419014 DOI: 10.1016/j.jpain.2021.03.146] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 03/09/2021] [Accepted: 03/12/2021] [Indexed: 12/26/2022]
Abstract
Adverse life events (ALEs) are a risk factor for chronic pain; however, mechanisms underlying this association are not understood. This study examined whether cumulative ALE exposure impairs endogenous inhibition of pain (assessed from pain report) and spinal nociception (assessed from nociceptive flexion reflex; NFR) in healthy, pain-free Native Americans (n = 124) and non-Hispanic Whites (n = 129) during a conditioned pain modulation (CPM) task. Cumulative ALE exposure was assessed prior to testing by summing the number of potentially traumatic events experienced by each participant across their lifespan. Multilevel modeling found that ALEs were associated with NFR modulation during the CPM task even after controlling for general health, body mass index, sex, age, blood pressure, sleep quality, stimulation intensity, stimulus number, perceived stress, and psychological distress. Low exposure to ALEs was associated with NFR inhibition, whereas high exposure to ALEs was associated with NFR facilitation. By contrast, pain perception was inhibited during the CPM task regardless of the level of ALE exposure. Race/ethnicity did not moderate these results. Thus, ALEs may be pronociceptive for both Native Americans and non-Hispanic Whites by impairing descending inhibition of spinal nociception. This could contribute to a chronic pain risk phenotype involving latent spinal sensitization. PERSPECTIVE: This study found that adverse life events were associated with impaired descending inhibition of spinal nociception in a sample of Native Americans and non-Hispanic Whites. These findings expand on previous research linking adversity to chronic pain risk by identifying a proximate physiological mechanism for this association.
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Affiliation(s)
- Parker A Kell
- Department of Psychology; The University of Tulsa; Tulsa, Oklahoma
| | - Natalie Hellman
- Department of Psychology; The University of Tulsa; Tulsa, Oklahoma
| | | | - Edward W Lannon
- Department of Psychology; The University of Tulsa; Tulsa, Oklahoma
| | - Bethany L Kuhn
- Department of Psychology; The University of Tulsa; Tulsa, Oklahoma
| | | | - Tyler A Toledo
- Department of Psychology; The University of Tulsa; Tulsa, Oklahoma
| | - Mara J Demuth
- Department of Psychology; The University of Tulsa; Tulsa, Oklahoma
| | - Burkhart J Hahn
- Department of Psychology; The University of Tulsa; Tulsa, Oklahoma
| | - Joanna O Shadlow
- Department of Psychology; The University of Tulsa; Tulsa, Oklahoma
| | - Jamie L Rhudy
- Department of Psychology; The University of Tulsa; Tulsa, Oklahoma.
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Arbiters of endogenous opioid analgesia: role of CNS estrogenic and glutamatergic systems. Transl Res 2021; 234:31-42. [PMID: 33567346 PMCID: PMC8217383 DOI: 10.1016/j.trsl.2021.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 11/24/2022]
Abstract
Nociception and opioid antinociception in females are pliable processes, varying qualitatively and quantitatively over the reproductive cycle. Spinal estrogenic signaling via membrane estrogen receptors (mERs), in combination with multiple other signaling molecules [spinal dynorphin, kappa-opioid receptors (KOR), glutamate and metabotropic glutamate receptor 1 (mGluR1)], appears to function as a master coordinator, parsing functionality between pronociception and antinociception. This provides a window into pharmacologically accessing intrinsic opioid analgesic/anti-allodynic systems. In diestrus, membrane estrogen receptor alpha (mERα) signals via mGluR1 to suppress spinal endomorphin 2 (EM2) analgesia. Strikingly, in the absence of exogenous opioids, interfering with this suppression in a chronic pain model elicits opioid anti-allodynia, revealing contributions of endogenous opioid(s). In proestrus, robust spinal EM2 analgesia is manifest but this requires spinal dynorphin/KOR and glutamate-activated mGluR1. Furthermore, spinal mGluR1 blockade in a proestrus chronic pain animal (eliminating spinal EM2 analgesia) exacerbates mechanical allodynia, revealing tempering by endogenous opioid(s). A complex containing mu-opioid receptor, KOR, aromatase, mGluRs, and mERα are foundational to eliciting endogenous opioid anti-allodynia. Aromatase-mERα oligomers are also plentiful, in a central nervous system region-specific fashion. These can be independently regulated and allow estrogens to act intracellularly within the same signaling complex in which they are synthesized, explaining asynchronous relationships between circulating estrogens and central nervous system estrogen functionalities. Observations with EM2 highlight the translational relevance of extensively characterizing exogenous responsiveness to endogenous opioids and the neuronal circuits that mediate them along with the multiplicity of estrogenic systems that concomitantly function in phase and out-of-phase with the reproductive cycle.
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47
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O'Brien JB, Roman DL. Novel treatments for chronic pain: moving beyond opioids. Transl Res 2021; 234:1-19. [PMID: 33727192 DOI: 10.1016/j.trsl.2021.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 03/06/2021] [Accepted: 03/08/2021] [Indexed: 02/06/2023]
Abstract
It is essential that safe and effective treatment options be available to patients suffering from chronic pain. The emergence of an opioid epidemic has shaped public opinions and created stigmas surrounding the use of opioids for the management of pain. This reality, coupled with high risk of adverse effects from chronic opioid use, has led chronic pain patients and their healthcare providers to utilize nonopioid treatment approaches. In this review, we will explore a number of cellular reorganizations that are associated with the development and progression of chronic pain. We will also discuss the safety and efficacy of opioid and nonopioid treatment options for chronic pain. Finally, we will review the evidence for adenylyl cyclase type 1 (AC1) as a novel target for the treatment of chronic pain.
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Affiliation(s)
- Joseph B O'Brien
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, Iowa
| | - David L Roman
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, Iowa; Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa.
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48
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Muchhala KH, Jacob JC, Dewey WL, Akbarali HI. Role of β-arrestin-2 in short- and long-term opioid tolerance in the dorsal root ganglia. Eur J Pharmacol 2021; 899:174007. [PMID: 33705801 PMCID: PMC8058323 DOI: 10.1016/j.ejphar.2021.174007] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 02/25/2021] [Accepted: 02/28/2021] [Indexed: 11/26/2022]
Abstract
G-protein-biased agonists with reduced β-arrestin-2 activation are being investigated as safer alternatives to clinically-used opioids. β-arrestin-2 has been implicated in the mechanism of opioid-induced antinociceptive tolerance. Opioid-induced analgesic tolerance is classically considered as centrally-mediated, but recent reports implicate nociceptive dorsal root ganglia neurons as critical mediators in this process. Here, we investigated the role of β-arrestin-2 in the mechanism of opioid tolerance in dorsal root ganglia nociceptive neurons using β-arrestin-2 knockout mice and the G-protein-biased μ-opioid receptor agonist, TRV130. Whole-cell current-clamp electrophysiology experiments revealed that 15-18-h overnight exposure to 10 μM morphine in vitro induced acute tolerance in β-arrestin-2 wild-type but not knockout neurons. Furthermore, in wild-type neurons circumventing β-arrestin-2 activation by overnight treatment with 200 nM TRV130 attenuated tolerance. Similarly, acute morphine tolerance in vivo in β-arrestin-2 knockout mice was prevented in the warm-water tail-withdrawal assay. Treatment with 30 mg/kg TRV130 s.c. also inhibited acute antinociceptive tolerance in vivo in wild-type mice. Alternately, in β-arrestin-2 knockout neurons tolerance induced by 7-day in vivo exposure to 50 mg morphine pellet was conserved. Likewise, β-arrestin-2 deletion did not mitigate in vivo antinociceptive tolerance induced by 7-day exposure to 25 mg or 50 mg morphine pellet in both female or male mice, respectively. Consequently, these results indicated that β-arrestin-2 mediates acute but not chronic opioid tolerance in dorsal root ganglia neurons and to antinociception in vivo. This suggests that opioid-induced antinociceptive tolerance may develop even in the absence of β-arrestin-2 activation, and thus significantly affect the clinical utility of biased agonists.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Behavior, Animal/drug effects
- Cells, Cultured
- Disease Models, Animal
- Drug Tolerance
- Female
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/metabolism
- Ganglia, Spinal/physiopathology
- Male
- Mice, Knockout
- Morphine/pharmacology
- Neurons/drug effects
- Neurons/metabolism
- Nociceptive Pain/genetics
- Nociceptive Pain/metabolism
- Nociceptive Pain/physiopathology
- Nociceptive Pain/prevention & control
- Pain Threshold/drug effects
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/metabolism
- Spiro Compounds/pharmacology
- Thiophenes/pharmacology
- Time Factors
- beta-Arrestin 2/deficiency
- beta-Arrestin 2/genetics
- beta-Arrestin 2/metabolism
- Mice
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Affiliation(s)
- Karan H Muchhala
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1112 East Clay St, Richmond, VA, 23298, USA
| | - Joanna C Jacob
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1112 East Clay St, Richmond, VA, 23298, USA
| | - William L Dewey
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1112 East Clay St, Richmond, VA, 23298, USA
| | - Hamid I Akbarali
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1112 East Clay St, Richmond, VA, 23298, USA.
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49
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Watkins LR, Orlandi C. In vitro profiling of orphan G protein coupled receptor (GPCR) constitutive activity. Br J Pharmacol 2021; 178:2963-2975. [PMID: 33784795 DOI: 10.1111/bph.15468] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 03/18/2021] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND AND PURPOSE Members of the GPCR family are targeted by a significant fraction of the available FDA-approved drugs. However, the physiological role and pharmacological properties of many GPCRs remain unknown, representing untapped potential in drug design. Of particular interest are ~100 less-studied GPCRs known as orphans because their endogenous ligands are unknown. Intriguingly, disease-causing mutations identified in patients, together with animal studies, have demonstrated that many orphan receptors play crucial physiological roles and, thus, represent attractive drug targets. EXPERIMENTAL APPROACH The majority of deorphanized GPCRs demonstrate coupling to Gi/o . However, a limited number of techniques allow the detection of intrinsically small constitutive activity associated with Gi/o protein activation, which represents a significant barrier in our ability to study orphan GPCR signalling. Using luciferase reporter assays, we effectively detected constitutive Gs , Gq and G12/13 protein signalling by unliganded receptors and introducing various G protein chimeras, we provide a novel, highly sensitive tool capable of identifying Gi/o coupling in unliganded orphan GPCRs. KEY RESULTS Using this approach, we measured the constitutive activity of the entire class C GPCR family that includes eight orphan receptors and a subset of 20 prototypical class A GPCR members, including 11 orphans. Excitingly, this approach illuminated the G protein coupling profile of eight orphan GPCRs (GPR22, GPR137b, GPR88, GPR156, GPR158, GPR179, GPRC5D and GPRC6A) previously linked to pathophysiological processes. CONCLUSION AND IMPLICATIONS We provide a new platform that could be utilized in ongoing studies in orphan receptor signalling and de-orphanization efforts.
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Affiliation(s)
- Lyndsay R Watkins
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, USA
| | - Cesare Orlandi
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, USA
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50
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Aghajani N, Pourhamzeh M, Azizi H, Semnanian S. Central blockade of orexin type 1 receptors reduces naloxone induced activation of locus coeruleus neurons in morphine dependent rats. Neurosci Lett 2021; 755:135909. [PMID: 33892002 DOI: 10.1016/j.neulet.2021.135909] [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: 02/19/2021] [Revised: 04/04/2021] [Accepted: 04/16/2021] [Indexed: 11/30/2022]
Abstract
Orexin neuropeptides are implicated in the expression of morphine dependence. Locus coeruleus (LC) nucleus is an important brain area involving in the development of withdrawal signs of morphine and contains high expression of orexin type 1 receptors (OX1Rs). Despite extensive considerations, effects of immediate inhibition of OX1Rs by a single dose administration of SB-334867 prior to the naloxone-induced activation of LC neurons remains unknown. Therefore, we examined the direct effects of OX1Rs acute blockade on the neuronal activity of the morphine-dependent rats which underwent naloxone administration. Adult male rats underwent subcutaneous administration of 10 mg/kg morphine (two times/day) for a ten-day period. On the last day of experiment, intra-cerebroventricular administration of 10 μg/μl antagonist of OX1Rs, SB-334867, was performed just before intra-peritoneal injection of 2 mg/kg naloxone. Thereafter, in vivo extracellular single unit recording was employed to evaluate the electrical activity of LC neuronal cells. The outcomes demonstrated that morphine tolerance developed following ten-day of injection. Then, naloxone administration causes hyperactivity of LC neuronal cells, whereas a single dose administration of SB-334867 prior to naloxone prevented the enhanced activity of neurons upon morphine withdrawal. Our findings indicate that increased response of LC neuronal cells to applied naloxone could be prevented by the acute inhibition of the OX1Rs just before the naloxone treatment.
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Affiliation(s)
- Niloofar Aghajani
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Mahsa Pourhamzeh
- Division of Neuroscience, Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Hossein Azizi
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
| | - Saeed Semnanian
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
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