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Zeng P, Wang T, Zhang L, Guo F. Exploring the causes of augmentation in restless legs syndrome. Front Neurol 2023; 14:1160112. [PMID: 37840917 PMCID: PMC10571710 DOI: 10.3389/fneur.2023.1160112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 09/13/2023] [Indexed: 10/17/2023] Open
Abstract
Long-term drug treatment for Restless Legs Syndrome (RLS) patients can frequently result in augmentation, which is the deterioration of symptoms with an increased drug dose. The cause of augmentation, especially derived from dopamine therapy, remains elusive. Here, we review recent research and clinical progress on the possible mechanism underlying RLS augmentation. Dysfunction of the dopamine system highly possibly plays a role in the development of RLS augmentation, as dopamine agonists improve desensitization of dopamine receptors, disturb receptor interactions within or outside the dopamine receptor family, and interfere with the natural regulation of dopamine synthesis and release in the neural system. Iron deficiency is also indicated to contribute to RLS augmentation, as low iron levels can affect the function of the dopamine system. Furthermore, genetic risk factors, such as variations in the BTBD9 and MEIS1 genes, have been linked to an increased risk of RLS initiation and augmentation. Additionally, circadian rhythm, which controls the sleep-wake cycle, may also contribute to the worsening of RLS symptoms and the development of augmentation. Recently, Vitamin D deficiency has been suggested to be involved in RLS augmentation. Based on these findings, we propose that the progressive reduction of selective receptors, influenced by various pathological factors, reverses the overcompensation of the dopamine intensity promoted by short-term, low-dose dopaminergic therapy in the development of augmentation. More research is needed to uncover a deeper understanding of the mechanisms underlying the RLS symptom and to develop effective RLS augmentation treatments.
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Affiliation(s)
- Pengyu Zeng
- Department of Neurobiology, Department of Neurology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
| | - Tiantian Wang
- Department of Pharmacy, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Center for Sleep Medicine, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Lisan Zhang
- Department of Neurobiology, Department of Neurology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Center for Sleep Medicine, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Fang Guo
- Department of Neurobiology, Department of Neurology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
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2
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Woods S, Basco J, Clemens S. Effects of iron-deficient diet on sleep onset and spinal reflexes in a rodent model of Restless Legs Syndrome. Front Neurol 2023; 14:1160028. [PMID: 37273717 PMCID: PMC10234126 DOI: 10.3389/fneur.2023.1160028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 05/02/2023] [Indexed: 06/06/2023] Open
Abstract
Restless Legs Syndrome (RLS) is a common sensorimotor and a sleep disorder that affects 2.5-10% of the European and North American populations. RLS is also often associated with periodic leg movements during sleep (PLMS). Despite ample evidence of genetic contributions, the underlying mechanisms that elicit the sensory and motor symptoms remain unidentified. Clinically, RLS has been correlated with an altered central iron metabolism, particularly in the brain. While several animal models have been developed to determine the outcome of an altered iron homeostasis on brain function, the potential role of an altered iron homeostasis on sleep and sensorimotor circuits has not yet been investigated. Here, we utilize a mouse model to assess the effects of an iron-deficient (ID) but non-anemic state on sleep time and episodes, and sensorimotor reflexes in male and female mice. We found that animals on the ID diet displayed an increased expression of the transferrin receptor in the spinal cord, confirming the results of previous studies that focused only on the impact of ID in the brain. We also demonstrate that the ID diet reduced hematocrit levels compared to controls but not into the anemic range, and that animals on the ID diet exhibited RLS-like symptoms with regard to sleep onset and spinal cord reflex excitability. Interestingly, the effects on the spinal cord were stronger in females than in males, and the ID diet-induced behaviors were rescued by the return of the animals to the control diet. Taken together, these results demonstrate that diet-induced ID changes to CNS function are both inducible and reversible, and that they mimic the sleep and sensorimotor RLS symptoms experienced in the clinic. We therefore propose replacing the commonly used phrase "brain iron deficiency" (BID) hypothesis in the RLS research field with the term "iron deficiency in the central nervous system" (ID-CNS), to include possible effects of altered iron levels on spinal cord function.
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Newman AH, Xi ZX, Heidbreder C. Current Perspectives on Selective Dopamine D 3 Receptor Antagonists/Partial Agonists as Pharmacotherapeutics for Opioid and Psychostimulant Use Disorders. Curr Top Behav Neurosci 2023; 60:157-201. [PMID: 35543868 PMCID: PMC9652482 DOI: 10.1007/7854_2022_347] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Over three decades of evidence indicate that dopamine (DA) D3 receptors (D3R) are involved in the control of drug-seeking behavior and may play an important role in the pathophysiology of substance use disorders (SUD). The expectation that a selective D3R antagonist/partial agonist would be efficacious for the treatment of SUD is based on the following key observations. First, D3R are distributed in strategic areas belonging to the mesolimbic DA system such as the ventral striatum, midbrain, and ventral pallidum, which have been associated with behaviors controlled by the presentation of drug-associated cues. Second, repeated exposure to drugs of abuse produces neuroadaptations in the D3R system. Third, the synthesis and characterization of highly potent and selective D3R antagonists/partial agonists have further strengthened the role of the D3R in SUD. Based on extensive preclinical and preliminary clinical evidence, the D3R shows promise as a target for the development of pharmacotherapies for SUD as reflected by their potential to (1) regulate the motivation to self-administer drugs and (2) disrupt the responsiveness to drug-associated stimuli that play a key role in reinstatement of drug-seeking behavior triggered by re-exposure to the drug itself, drug-associated environmental cues, or stress. The availability of PET ligands to assess clinically relevant receptor occupancy by selective D3R antagonists/partial agonists, the definition of reliable dosing, and the prospect of using human laboratory models may further guide the design of clinical proof of concept studies. Pivotal clinical trials for more rapid progression of this target toward regulatory approval are urgently required. Finally, the discovery that highly selective D3R antagonists, such as R-VK4-116 and R-VK4-40, do not adversely affect peripheral biometrics or cardiovascular effects alone or in the presence of oxycodone or cocaine suggests that this class of drugs has great potential in safely treating psychostimulant and/or opioid use disorders.
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Affiliation(s)
- Amy Hauck Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse-Intramural Research Program, Baltimore, MD, USA.
| | - Zheng-Xiong Xi
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse-Intramural Research Program, Baltimore, MD, USA
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Silvani A, Ghorayeb I, Manconi M, Li Y, Clemens S. Putative Animal Models of Restless Legs Syndrome: A Systematic Review and Evaluation of Their Face and Construct Validity. Neurotherapeutics 2023; 20:154-178. [PMID: 36536233 PMCID: PMC10119375 DOI: 10.1007/s13311-022-01334-4] [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] [Accepted: 12/02/2022] [Indexed: 12/24/2022] Open
Abstract
Restless legs syndrome (RLS) is a sensorimotor disorder that severely affects sleep. It is characterized by an urge to move the legs, which is often accompanied by periodic limb movements during sleep. RLS has a high prevalence in the population and is usually a life-long condition. While its origins remain unclear, RLS is initially highly responsive to treatment with dopaminergic agonists that target D2-like receptors, in particular D2 and D3, but the long-term response is often unsatisfactory. Over the years, several putative animal models for RLS have been developed, mainly based on the epidemiological and neurochemical link with iron deficiency, treatment efficacy of D2-like dopaminergic agonists, or genome-wide association studies that identified risk factors in the patient population. Here, we present the first systematic review of putative animal models of RLS, provide information about their face and construct validity, and report their role in deciphering the underlying pathophysiological mechanisms that may cause or contribute to RLS. We propose that identifying the causal links between genetic risk factors, altered organ functions, and changes to molecular pathways in neural circuitry will eventually lead to more effective new treatment options that bypass the side effects of the currently used therapeutics in RLS, especially for long-term therapy.
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Affiliation(s)
- Alessandro Silvani
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum - University of Bologna, Ravenna Campus, Ravenna, Italy
| | - Imad Ghorayeb
- Département de Neurophysiologie Clinique, Pôle Neurosciences Cliniques, CHU de Bordeaux, Bordeaux, France
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, Université de Bordeaux, Bordeaux, France
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, CNRS, Bordeaux, France
| | - Mauro Manconi
- Sleep Medicine Unit, Neurocenter of Southern Switzerland, EOC, Ospedale Civico, Lugano, Switzerland
- Department of Neurology, University Hospital, Inselspital, Bern, Switzerland
- Faculty of Biomedical Sciences, Università della Svizzera Italiana, Lugano, Switzerland
| | - Yuqing Li
- Department of Neurology, College of Medicine, Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, USA
| | - Stefan Clemens
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, USA.
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Piña-Leyva C, Lara-Lozano M, Rodríguez-Sánchez M, Vidal-Cantú GC, Barrientos Zavalza E, Jiménez-Estrada I, Delgado-Lezama R, Rodríguez-Sosa L, Granados-Soto V, González-Barrios JA, Florán-Garduño B. Hypothalamic A11 Nuclei Regulate the Circadian Rhythm of Spinal Mechanonociception through Dopamine Receptors and Clock Gene Expression. Life (Basel) 2022; 12:life12091411. [PMID: 36143447 PMCID: PMC9506518 DOI: 10.3390/life12091411] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 09/05/2022] [Accepted: 09/07/2022] [Indexed: 11/26/2022] Open
Abstract
Several types of sensory perception have circadian rhythms. The spinal cord can be considered a center for controlling circadian rhythms by changing clock gene expression. However, to date, it is not known if mechanonociception itself has a circadian rhythm. The hypothalamic A11 area represents the primary source of dopamine (DA) in the spinal cord and has been found to be involved in clock gene expression and circadian rhythmicity. Here, we investigate if the paw withdrawal threshold (PWT) has a circadian rhythm, as well as the role of the dopaminergic A11 nucleus, DA, and DA receptors (DR) in the PWT circadian rhythm and if they modify clock gene expression in the lumbar spinal cord. Naïve rats showed a circadian rhythm of the PWT of almost 24 h, beginning during the night–day interphase and peaking at 14.63 h. Similarly, DA and DOPAC’s spinal contents increased at dusk and reached their maximum contents at noon. The injection of 6-hydroxydopamine (6-OHDA) into the A11 nucleus completely abolished the circadian rhythm of the PWT, reduced DA tissue content in the lumbar spinal cord, and induced tactile allodynia. Likewise, the repeated intrathecal administration of D1-like and D2-like DA receptor antagonists blunted the circadian rhythm of PWT. 6-OHDA reduced the expression of Clock and Per1 and increased Per2 gene expression during the day. In contrast, 6-OHDA diminished Clock, Bmal, Per1, Per2, Per3, Cry1, and Cry2 at night. The repeated intrathecal administration of the D1-like antagonist (SCH-23390) reduced clock genes throughout the day (Clock and Per2) and throughout the night (Clock, Per2 and Cry1), whereas it increased Bmal and Per1 throughout the day. In contrast, the intrathecal injection of the D2 receptor antagonists (L-741,626) increased the clock genes Bmal, Per2, and Per3 and decreased Per1 throughout the day. This study provides evidence that the circadian rhythm of the PWT results from the descending dopaminergic modulation of spinal clock genes induced by the differential activation of spinal DR.
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Affiliation(s)
- Celia Piña-Leyva
- · Department of Physiology, Biophysics, and Neurosciences, CINVESTAV, Av. No. 2508 National Polytechnic Institute, Mexico City 06760, Mexico
| | - Manuel Lara-Lozano
- · Department of Physiology, Biophysics, and Neurosciences, CINVESTAV, Av. No. 2508 National Polytechnic Institute, Mexico City 06760, Mexico
- Genomic Medicine Laboratory, Regional Hospital “October 1st”, ISSSTE, Av. No. 1669 National Polytechnic Institute, Mexico City 07760, Mexico
| | - Marina Rodríguez-Sánchez
- · Department of Physiology, Biophysics, and Neurosciences, CINVESTAV, Av. No. 2508 National Polytechnic Institute, Mexico City 06760, Mexico
| | - Guadalupe C. Vidal-Cantú
- Neurobiology of Pain Laboratory, Departamento de Farmacología, Cinvestav, Sede Sur, México City 14330, Mexico
| | - Ericka Barrientos Zavalza
- Doctorado en Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana, Unidad Iztapalapa, Mexico City 09340, Mexico
| | - Ismael Jiménez-Estrada
- · Department of Physiology, Biophysics, and Neurosciences, CINVESTAV, Av. No. 2508 National Polytechnic Institute, Mexico City 06760, Mexico
| | - Rodolfo Delgado-Lezama
- · Department of Physiology, Biophysics, and Neurosciences, CINVESTAV, Av. No. 2508 National Polytechnic Institute, Mexico City 06760, Mexico
| | - Leonardo Rodríguez-Sosa
- Department of Physiology, Medicine Faculty, National Autonomous University of Mexico, University City, Mexico City 04510, Mexico
| | - Vinicio Granados-Soto
- Neurobiology of Pain Laboratory, Departamento de Farmacología, Cinvestav, Sede Sur, México City 14330, Mexico
| | - Juan Antonio González-Barrios
- Genomic Medicine Laboratory, Regional Hospital “October 1st”, ISSSTE, Av. No. 1669 National Polytechnic Institute, Mexico City 07760, Mexico
- Correspondence: (J.A.G.-B.); (B.F.-G.); Tel.: +52-55-81077971 (J.A.G.-B.); +52-55-13848283 (B.F.-G.)
| | - Benjamín Florán-Garduño
- · Department of Physiology, Biophysics, and Neurosciences, CINVESTAV, Av. No. 2508 National Polytechnic Institute, Mexico City 06760, Mexico
- Correspondence: (J.A.G.-B.); (B.F.-G.); Tel.: +52-55-81077971 (J.A.G.-B.); +52-55-13848283 (B.F.-G.)
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Salminen AV, Clemens S, García-Borreguero D, Ghorayeb I, Li Y, Manconi M, Ondo W, Rye D, Siegel JM, Silvani A, Winkelman JW, Allen RP, Ferré S. Consensus guidelines on the construct validity of rodent models of restless legs syndrome. Dis Model Mech 2022; 15:dmm049615. [PMID: 35946581 PMCID: PMC9393041 DOI: 10.1242/dmm.049615] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 07/10/2022] [Indexed: 12/16/2022] Open
Abstract
Our understanding of the causes and natural course of restless legs syndrome (RLS) is incomplete. The lack of objective diagnostic biomarkers remains a challenge for clinical research and for the development of valid animal models. As a task force of preclinical and clinical scientists, we have previously defined face validity parameters for rodent models of RLS. In this article, we establish new guidelines for the construct validity of RLS rodent models. To do so, we first determined and agreed on the risk, and triggering factors and pathophysiological mechanisms that influence RLS expressivity. We then selected 20 items considered to have sufficient support in the literature, which we grouped by sex and genetic factors, iron-related mechanisms, electrophysiological mechanisms, dopaminergic mechanisms, exposure to medications active in the central nervous system, and others. These factors and biological mechanisms were then translated into rodent bioequivalents deemed to be most appropriate for a rodent model of RLS. We also identified parameters by which to assess and quantify these bioequivalents. Investigating these factors, both individually and in combination, will help to identify their specific roles in the expression of rodent RLS-like phenotypes, which should provide significant translational implications for the diagnosis and treatment of RLS.
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Affiliation(s)
- Aaro V. Salminen
- Institute of Neurogenomics, Helmholtz Zentrum München GmbH - German Research Center for Environmental Health, 85764 Neuherberg, Germany
- Institute of Human Genetics, Klinikum rechts der Isar, Technische Universität München, 81675 Munich, Germany
| | - Stefan Clemens
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | | | - Imad Ghorayeb
- Département de Neurophysiologie Clinique, Pôle Neurosciences Cliniques, CHU de Bordeaux, 33076 Bordeaux, France
- Université de Bordeaux, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, 33076 Bordeaux, France
- CNRS, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, 33076 Bordeaux, France
| | - Yuqing Li
- Department of Neurology, Norman Fixel Institute for Neurological Diseases, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Mauro Manconi
- Sleep Medicine Unit, Regional Hospital of Lugano, Neurocenter of Southern Switzerland, 6900 Lugano, Switzerland
- Faculty of Biomedical Sciences, Università della Svizzera Italiana, 6900 Lugano, Switzerland
- Department of Neurology, University Hospital Inselspital, 3010 Bern, Switzerland
| | - William Ondo
- Houston Methodist Hospital Neurological Institute, Weill Cornell Medical School, Houston, TX 77070, USA
| | - David Rye
- Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jerome M. Siegel
- Neuropsychiatric Institute and Brain Research Institute, University of California, Los Angeles, CA 90095, USA
- Neurobiology Research, Veterans Administration Greater Los Angeles Healthcare System, North Hills, CA 91343, USA
| | - Alessandro Silvani
- Department of Biomedical and Neuromotor Sciences Alma Mater Studiorum, Università di Bologna, 48121 Ravenna Campus, Ravenna, Italy
| | - John W. Winkelman
- Departments of Psychiatry and Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Richard P. Allen
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21224, USA
| | - Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
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Morphine Resistance in Spinal Cord Injury-Related Neuropathic Pain in Rats is Associated With Alterations in Dopamine and Dopamine-Related Metabolomics. THE JOURNAL OF PAIN 2022; 23:772-783. [PMID: 34856409 DOI: 10.1016/j.jpain.2021.11.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 11/08/2021] [Accepted: 11/18/2021] [Indexed: 01/15/2023]
Abstract
Opioids are not universally effective for treating neuropathic pain following spinal cord injury (SCI), a finding that we previously demonstrated in a rat model of SCI. The aim of this study was to determine analgesic response of morphine-responsive and nonresponsive SCI rats to adjunct treatment with dopamine modulators and to establish if the animal groups expressed distinct metabolomic profiles. Thermal thresholds were tested in female Long Evans rats (N = 45) prior to contusion SCI, after SCI and following injection of morphine, morphine combined with dopamine modulators, or dopamine modulators alone. Spinal cord and striatum samples were processed for metabolomics and targeted mass spectrometry. Morphine provided analgesia in 1 of 3 of SCI animals. All animals showed improved analgesia with morphine + pramipexole (D3 receptor agonist). Only morphine nonresponsive animals showed improved analgesia with the addition of SCH 39166 (D1 receptor antagonist). Metabolomic analysis identified 3 distinct clusters related to the tyrosine pathway that corresponded to uninjured, SCI morphine-responsive and SCI morphine-nonresponsive groups. Mass spectrometry showed matching differences in dopamine levels in striatum and spinal cord between these groups. The data suggest an overall benefit of the D3 receptor system in improving analgesia, and an association between morphine responsiveness and metabolomic changes in the tyrosine/dopamine pathways in striatum and spinal cord. PERSPECTIVE: Spinal cord injury (SCI) leads to opioid-resistant neuropathic pain that is associated with changes in dopamine metabolomics in the spinal cord and striatum of rats. We present evidence that adjuvant targeting of the dopamine system may be a novel pain treatment approach to overcome opioid desensitization and tolerance after SCI.
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Abstract
Restless Legs Syndrome (RLS) is a sensorimotor disorder that severely affects sleep. It is characterized by an urge to move the legs that is often accompanied by periodic limb movements during sleep (PLMS). RLS has a high prevalence in the population and is usually a life-long condition. While its origins remain unclear, RLS is initially highly responsive to treatment with dopaminergics that target the D3 receptor. However, over time patients often develop a gradual tolerance that can lead to the emergence of adverse effects and the augmentation of the symptoms. While the basal ganglia and the striatum control leg movements, the lumbar spinal cord is the gateway for the sensory processing of the symptoms and critical for the associated leg movements. D3 receptors are highly expressed in nucleus accumbens (NAc) of the striatum and the sensory-processing areas of the spinal dorsal horn. In contrast, D1 receptors are strongly expressed throughout the entire striatum and in the ventral horn of the spinal cord. Long-term treatment with D3 receptor full agonists is associated with an upregulation of the D1 receptor subtype, and D3 and D1 receptors can form functional heteromers, in which the D3R controls the D1R function. It is conceivable that the switch from beneficial treatment to augmentation observed in RLS patients after prolonged D3R agonist exposure may be the result of unmasked D1-like receptor actions.
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Affiliation(s)
- Stefan Clemens
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, USA.
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Yuan HL, Zhao YL, Hu K, He YJ, Yang XW, Luo XD. C 19 Benzylisoquinoline Alkaloid with Unprecedented Architecture from Hypecoum erectum. J Org Chem 2021; 86:16764-16769. [PMID: 34723525 DOI: 10.1021/acs.joc.1c01990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hyperectumine (1), the first C19 benzylisoquinoline alkaloid with a complicated ring system, was isolated from Hypecoum erectum and structurally characterized. Its biosynthetic origin should involve a hybrid pattern of C8 + C8 + C1 + C2, from which a C17 benzylisoquinoline alkaloid might be further attacked by a malonamic acid and undergo decarboxylation and cyclization to produce 1. Compound (-)-1 exhibited moderate anti-inflammatory activity via suppression of LPS-activated inflammatory mediators in RAW 264.7 macrophage cells.
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Affiliation(s)
- Hai-Lian Yuan
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, People's Republic of China
| | - Yun-Li Zhao
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Provincial Center for Research and Development of Natural Products, School of Chemical Science and Technology, Yunnan University, Kunming 650091, People's Republic of China
| | - Kun Hu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, People's Republic of China
| | - Ying-Jie He
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Provincial Center for Research and Development of Natural Products, School of Chemical Science and Technology, Yunnan University, Kunming 650091, People's Republic of China
| | - Xing-Wei Yang
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Shenzhen 518107, People's Republic of China
| | - Xiao-Dong Luo
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, People's Republic of China.,Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Provincial Center for Research and Development of Natural Products, School of Chemical Science and Technology, Yunnan University, Kunming 650091, People's Republic of China
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10
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Lv Q, Wang X, Asakawa T, Wang XP. Pharmacologic Treatment of Restless Legs Syndrome. Curr Neuropharmacol 2021; 19:372-382. [PMID: 33380302 PMCID: PMC8033969 DOI: 10.2174/1570159x19666201230150127] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 10/24/2020] [Accepted: 12/19/2020] [Indexed: 01/14/2023] Open
Abstract
Restless legs syndrome (RLS)/Willis-Ekbom disease is a neurologic disorder characterized by a strong desire to move when at rest (usually in the evening) and paraesthesia in their lower legs. The most widely used therapies for first-line treatment of RLS are dopaminergic drugs; however, their long-term use can lead to augmentation. α2δ Ligands, opioids, iron, glutamatergic drugs, adenosine, and sleep aids have been investigated as alternatives. The pathogenesis of RLS is not well understood. Despite the efficacy of dopaminergic drugs in the treatment of this disorder, unlike in Parkinson’s disease dopaminergic cell loss in the substantia nigra has not been observed in RLS. The etiology of RLS is likely complex, involving multiple neural pathways. RLS-related genes identified in genome-wide association studies can provide insight into the mechanistic basis and pathophysiology of RLS. Here we review the current treatments and knowledge of the mechanisms underlying RLS.
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Affiliation(s)
- Qing Lv
- Department of Neurology, TongRen Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Xinlin Wang
- Department of Neurology, TongRen Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Tetsuya Asakawa
- Department of Neurosurgery, Hamamatsu University School of Medicine, Handayama, 1-20-1, Higashi-ku, Hamamatsucity, Shizuoka 431-3192, Japan
| | - Xiao Ping Wang
- Department of Neurology, TongRen Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
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Lyu S, Doroodchi A, Xing H, Sheng Y, DeAndrade MP, Yang Y, Johnson TL, Clemens S, Yokoi F, Miller MA, Xiao R, Li Y. BTBD9 and dopaminergic dysfunction in the pathogenesis of restless legs syndrome. Brain Struct Funct 2020; 225:1743-1760. [PMID: 32468214 DOI: 10.1007/s00429-020-02090-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 05/13/2020] [Indexed: 01/17/2023]
Abstract
Restless legs syndrome (RLS) is characterized by an urge to move legs, usually accompanied by uncomfortable sensations. RLS symptoms generally happen at night and can be relieved by movements. Genetic studies have linked polymorphisms in BTBD9 to a higher risk of RLS. Knockout of BTBD9 homolog in mice (Btbd9) and fly results in RLS-like phenotypes. A dysfunctional dopaminergic system is associated with RLS. However, the function of BTBD9 in the dopaminergic system and RLS is not clear. Here, we made use of the simple Caenorhabditis elegans nervous system. Loss of hpo-9, the worm homolog of BTBD9, resulted in hyperactive egg-laying behavior. Analysis of genetic interactions between hpo-9 and genes for dopamine receptors (dop-1, dop-3) indicated that hpo-9 and dop-1 worked similarly. Reporter assays of dop-1 and dop-3 revealed that hpo-9 knockout led to a significant increase of DOP-3 expression. This appears to be evolutionarily conserved in mice with an increased D2 receptor (D2R) mRNA in the striatum of the Btbd9 knockout mice. Furthermore, the striatal D2R protein was significantly decreased and Dynamin I was increased. Overall, activities of DA neurons in the substantia nigra were not altered, but the peripheral D1R pathway was potentiated in the Btbd9 knockout mice. Finally, we generated and characterized the dopamine neuron-specific Btbd9 knockout mice and detected an active-phase sleepiness, suggesting that dopamine neuron-specific loss of Btbd9 is sufficient to disturb the sleep. Our results suggest that increased activities in the D1R pathway, decreased activities in the D2R pathway, or both may contribute to RLS.
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Affiliation(s)
- Shangru Lyu
- Department of Neurology, Norman Fixel Institute for Neurological Diseases, College of Medicine, University of Florida, PO Box 100236, Gainesville, FL, 32610-0236, USA
| | - Atbin Doroodchi
- Department of Cell, Developmental and Integrative Biology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Hong Xing
- Department of Neurology, Norman Fixel Institute for Neurological Diseases, College of Medicine, University of Florida, PO Box 100236, Gainesville, FL, 32610-0236, USA
| | - Yi Sheng
- Department of Aging and Geriatric Research, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Mark P DeAndrade
- Department of Neurology, Norman Fixel Institute for Neurological Diseases, College of Medicine, University of Florida, PO Box 100236, Gainesville, FL, 32610-0236, USA
| | - Youfeng Yang
- Department of Cell, Developmental and Integrative Biology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Tracy L Johnson
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, 27834, USA
| | - Stefan Clemens
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, 27834, USA
| | - Fumiaki Yokoi
- Department of Neurology, Norman Fixel Institute for Neurological Diseases, College of Medicine, University of Florida, PO Box 100236, Gainesville, FL, 32610-0236, USA
| | - Michael A Miller
- Department of Cell, Developmental and Integrative Biology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Rui Xiao
- Department of Aging and Geriatric Research, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Yuqing Li
- Department of Neurology, Norman Fixel Institute for Neurological Diseases, College of Medicine, University of Florida, PO Box 100236, Gainesville, FL, 32610-0236, USA.
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12
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Galaj E, Newman AH, Xi ZX. Dopamine D3 receptor-based medication development for the treatment of opioid use disorder: Rationale, progress, and challenges. Neurosci Biobehav Rev 2020; 114:38-52. [PMID: 32376243 PMCID: PMC7252042 DOI: 10.1016/j.neubiorev.2020.04.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 04/28/2020] [Indexed: 01/11/2023]
Abstract
Opioid abuse and overdose have become a national crisis in the USA. Although several opioid-based pharmacotherapies are available, they are ineffective in long-term relapse prevention. National Institute on Drug Abuse has listed dopamine D3 receptor antagonists as high priority for anti-opioid medication development. The novel D3 receptor antagonists (VK4-116, VK4-40) are effective in reducing opioid reward and relapse as well as potentiate opioid analgesia. D3 receptor antagonists deserve further studies as new pharmacotherapies for pain and of opioid use disorder.
Opioid abuse and related overdose deaths continue to rise in the United States, contributing to the current national opioid crisis. Although several opioid-based pharmacotherapies are available (e.g., methadone, buprenorphine, naloxone), they show limited effectiveness in long-term relapse prevention. In response to the opioid crisis, the National Institute on Drug Abuse proposed a list of pharmacological targets of highest priority for medication development for the treatment of opioid use disorders (OUD). Among these are antagonists of dopamine D3 receptors (D3R). In this review, we first review recent progress in research of the dopamine hypothesis of opioid reward and abuse and then describe the rationale and recent development of D3R ligands for the treatment of OUD. Herein, an emphasis is placed on the effectiveness of newly developed D3R antagonists in the animal models of OUD. These new drug candidates may also potentiate the analgesic effects of clinically used opioids, making them attractive as adjunctive medications for pain management and treatment of OUD.
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Affiliation(s)
- Ewa Galaj
- Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, MD, United States
| | - Amy Hauck Newman
- Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, MD, United States
| | - Zheng-Xiong Xi
- Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, MD, United States.
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13
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Dopamine D 1 or D 3 receptor modulators prevent morphine tolerance and reduce opioid withdrawal symptoms. Pharmacol Biochem Behav 2020; 194:172935. [PMID: 32335101 DOI: 10.1016/j.pbb.2020.172935] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 04/20/2020] [Accepted: 04/21/2020] [Indexed: 01/31/2023]
Abstract
The long-term treatment of chronic pain by opioids is limited by tolerance and risk of addiction/dependence. Previously, we have shown that combination treatment of morphine with a dopamine D1 or D3 receptor modulator restored morphine analgesia in morphine-resistant neuropathic pain and decreased morphine's reward potential in an acute setting. Here, we investigated whether such adjunct therapy with a dopamine D1 receptor preferring antagonist (SCH 39166) or a dopamine D3 receptor preferring agonist (pramipexole) could prevent morphine tolerance and reduce withdrawal symptoms. Initially, tolerance to the combination of morphine + pramipexole was assessed in mice. Mice receiving intraperitoneal injections of morphine showed reduced thermal thresholds on Day 7 whereas those receiving morphine + pramipexole maintained analgesia at Day 7. Next, tolerance and withdrawal to both combinations were tested over 14 days in rats. Rats were assigned one of four drug conditions, (1) saline, 2) morphine, 3) morphine + SCH 39166, 4) morphine + pramipexole), for chronic administration via osmotic pumps. Chronic administration of morphine over 14 days resulted in a significant reduction of morphine analgesia. However, analgesia was maintained when morphine was administered with either the dopamine D1 receptor preferring antagonist or the D3 receptor preferring agonist. Withdrawal symptoms peaked at 48 h and were decreased in rats receiving either combination compared to morphine alone. The data suggests that adjunct therapy with dopamine D1 or D3 receptor preferring modulators prevents morphine tolerance and reduces the duration of morphine withdrawal symptoms, and thus this combination has potential for long-term pain management therapy.
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14
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D3 and D1 receptors: The Yin and Yang in the treatment of restless legs syndrome with dopaminergics. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2019; 84:79-100. [PMID: 31229178 DOI: 10.1016/bs.apha.2019.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Dopaminergic treatments targeting the D3 receptor subtype to reduce the symptoms of RLS show substantial initial clinical benefits but fail to maintain their efficacy over time. Sensorimotor circuits in the spinal cord are the gateway for the sensory processing of the symptoms and critical for the associated leg movements that relieve the symptoms and the periodic limb movements that often develop during sleep. There is a high preponderance of the inhibitory D3 receptor in the sensory-processing areas of the spinal cord (dorsal horn), whereas the motor areas in the ventral horn more strongly express the excitatory D1 receptor subtype. D3 and D1 receptors can form functional heteromeric ensembles that influence each other. In the spinal cord, long-term treatment with D3 receptor agonists is associated with the upregulation of the D1 receptor subtype and block of D1 receptor function at this stage can restore the D3 receptor effect. Alternate scenarios for a role of dopamine involve a role for the D5 receptor in regulating motor excitability and for the D4 receptor subtype in controlling D3-like effects. A model emerges that proposes that the behavioral changes in RLS, while responsive to D3 receptor agonists, may be ultimately be the result of unmasked increased D1-like receptor activities.
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15
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Dopamine D1 and D3 receptor modulators restore morphine analgesia and prevent opioid preference in a model of neuropathic pain. Neuroscience 2019; 406:376-388. [DOI: 10.1016/j.neuroscience.2019.03.034] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/04/2019] [Accepted: 03/14/2019] [Indexed: 12/25/2022]
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16
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Sokolov AY, Popova NS, Povarenkov AS, Amelin AV. The Role of Dopamine in Primary Headaches. NEUROCHEM J+ 2018. [DOI: 10.1134/s1819712418030145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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17
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Comorbidities, treatment, and pathophysiology in restless legs syndrome. Lancet Neurol 2018; 17:994-1005. [PMID: 30244828 DOI: 10.1016/s1474-4422(18)30311-9] [Citation(s) in RCA: 142] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 07/05/2018] [Accepted: 08/08/2018] [Indexed: 12/11/2022]
Abstract
Restless legs syndrome, also known as Willis-Ekbom disease, is a common neurological condition whose manifestation is affected by complex environmental and genetic interactions. Restless legs syndrome can occur on its own, mostly at a young age, or with comorbidities such as cardiovascular disease, diabetes, and arterial hypertension, making it a difficult condition to properly diagnose. However, the concept of restless legs syndrome as being two entities, primary or secondary to another condition, has been challenged with genetic data providing further insight into the pathophysiology of the condition. Although dopaminergic treatment was formerly the first-line therapy, prolonged use can result in a serious worsening of symptoms known as augmentation. Clinical studies on pregabalin, gabapentin enacarbil, oxycodone-naloxone, and iron preparations have provided new treatment options, but most patients still report inadequate long-term management of symptoms. Studies of the hypoxic pathway activation and iron deficiency have provided valuable information about the pathophysiology of restless legs syndrome that should now be translated into new, more effective treatments for restless legs syndrome.
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18
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Meneely S, Dinkins ML, Kassai M, Lyu S, Liu Y, Lin CT, Brewer K, Li Y, Clemens S. Differential Dopamine D1 and D3 Receptor Modulation and Expression in the Spinal Cord of Two Mouse Models of Restless Legs Syndrome. Front Behav Neurosci 2018; 12:199. [PMID: 30233336 PMCID: PMC6131574 DOI: 10.3389/fnbeh.2018.00199] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 08/13/2018] [Indexed: 12/22/2022] Open
Abstract
Restless Legs Syndrome (RLS) is often and successfully treated with dopamine receptor agonists that target the inhibitory D3 receptor subtype, however there is no clinical evidence of a D3 receptor dysfunction in RLS patients. In contrast, genome-wide association studies in RLS patients have established that a mutation of the MEIS1 gene is associated with an increased risk in developing RLS, but the effect of MEIS1 dysfunction on sensorimotor function remain unknown. Mouse models for a dysfunctional D3 receptor (D3KO) and Meis1 (Meis1KO) were developed independently, and each animal expresses some features associated with RLS in the clinic, but they have not been compared in their responsiveness to treatment options used in the clinic. We here confirm that D3KO and Meis1KO animals show increased locomotor activities, but that only D3KO show an increased sensory excitability to thermal stimuli. Next we compared the effects of dopaminergics and opioids in both animal models, and we assessed D1 and D3 dopamine receptor expression in the spinal cord, the gateway for sensorimotor processing. We found that Meis1KO share most of the tested behavioral properties with their wild type (WT) controls, including the modulation of the thermal pain withdrawal reflex by morphine, L-DOPA and D3 receptor (D3R) agonists and antagonists. However, Meis1KO and D3KO were behaviorally more similar to each other than to WT when tested with D1 receptor (D1R) agonists and antagonists. Subsequent Western blot analyses of D1R and D3R protein expression in the spinal cord revealed a significant increase in D1R but not D3R expression in Meis1KO and D3KO over WT controls. As the D3R is mostly present in the dorsal spinal cord where it has been shown to modulate sensory pathways, while activation of the D1Rs can activate motoneurons in the ventral spinal cord, we speculate that D3KO and Meis1KO represent two complementary animal models for RLS, in which the mechanisms of sensory (D3R-mediated) and motor (D1R-mediated) dysfunctions can be differentially explored.
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Affiliation(s)
- Samantha Meneely
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Mai-Lynne Dinkins
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Miki Kassai
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Shangru Lyu
- Department of Neurology, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Yuning Liu
- Department of Neurology, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Chien-Te Lin
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Kori Brewer
- Department of Emergency Medicine, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Yuqing Li
- Department of Neurology, College of Medicine, University of Florida, Gainesville, FL, United States
- Wuxi Medical School, Jiangnan University, Wuxi, China
| | - Stefan Clemens
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
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19
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Long-term treatment with dopamine D3 receptor agonists induces a behavioral switch that can be rescued by blocking the dopamine D1 receptor. Sleep Med 2017; 40:47-52. [DOI: 10.1016/j.sleep.2017.10.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 09/29/2017] [Accepted: 10/04/2017] [Indexed: 11/23/2022]
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20
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Dopamine D1-like Receptors Regulate Constitutive, μ-Opioid Receptor-Mediated Repression of Use-Dependent Synaptic Plasticity in Dorsal Horn Neurons: More Harm than Good? J Neurosci 2017; 36:5661-73. [PMID: 27194343 DOI: 10.1523/jneurosci.2469-15.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 04/11/2016] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED The current study reports on a synaptic mechanism through which D1-like receptors (D1LRs) modulate spinal nociception and plasticity by regulating activation of the μ-opioid receptor (MOR).D1LR stimulation with agonist SKF 38393 concentration-dependently depressed C-fiber-evoked potentials in rats receiving spinal nerve ligation (SNL), but not in uninjured rats. Depression was prevented by MOR- but not GABA-receptor blockade. Neurons expressing the D1 subtype were immunopositive for met-enkephalin and vesicular glutamate transporter VGLUT2, but not for GABAergic marker vGAT.Nerve ligation was followed by increased immunoreactivity for D1 in synaptic compartment (P3) in dorsal horn homogenates and presynaptic met-enkephalin-containing boutons. SNL led to increased immunoreactivity for met-enkephalin in dorsal horn homogenates, which was dose-dependently attenuated by selective D1LR antagonist SCH 23390. During blockade of either D1R or MOR, low-frequency (0.2 or 3 Hz) stimulation (LFS) to the sciatic nerve induced long-term potentiation (LTP) of C-fiber-evoked potentials, revealing a constituent role of both receptors in repressing afferent-induced synaptic plasticity. LFS consistently induced NMDA receptor-dependent LTP in nerve-injured rats. The ability of MOR both to prevent LTP and to modulate mechanical and thermal pain thresholds in behavioral tests was preserved in nerve-ligated rats that were postoperatively treated with SCH 23390. D1LR priming for 30 min sufficed to disrupt MOR function in otherwise naive rats via a mechanism involving receptor overuse.The current data support that, whereas D1LR-modulated MOR activation is instrumental in antinociception and endogenous repression of synaptic plasticity, this mechanism deteriorates rapidly by sustained use, generating increased vulnerability to afferent input. SIGNIFICANCE STATEMENT The current study shows that dopamine D1-like receptors (D1LRs) and μ-opioid receptors (MOR) in the spinal dorsal horn constitutively repress the expression of synaptic long-term potentiation (LTP) of C-fiber-evoked potentials. Anatomical data are provided supporting that the D1 subtype regulates MOR function by modulating met-enkephalin release. Sustained neuropathic pain induced by spinal nerve ligation is accompanied by D1R and met-enkephalin upregulation, acquired D1LR-mediated antinociception, and a loss of endogenous repression of further synaptic plasticity. We show that the ability of MOR to oppose LTP is rapidly impaired by sustained D1LR activation via a mechanism involving sustained MOR activation.
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21
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Samir S, Yllanes AP, Lallemand P, Brewer KL, Clemens S. Morphine responsiveness to thermal pain stimuli is aging-associated and mediated by dopamine D1 and D3 receptor interactions. Neuroscience 2017; 349:87-97. [PMID: 28257894 DOI: 10.1016/j.neuroscience.2017.02.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 01/16/2017] [Accepted: 02/20/2017] [Indexed: 01/09/2023]
Abstract
Morphine actions involve the dopamine (DA) D1 and D3 receptor systems (D1R and D3R), and the responses to morphine change with age. We here explored in differently aged wild-type (WT) and D3R knockout mice (D3KO) the interactions of the D1R/D3R systems with morphine in vivo at three different times of the animals' lifespan (2months, 1year, and 2years). We found that: (1) thermal pain withdrawal reflexes follow an aging-associated phenotype, with relatively longer latencies at 2months and shorter latencies at 1year, (2) over the same age range, a dysfunction of the D3R subtype decreases reflex latencies more than aging alone, (3) morphine altered reflex responses in a dose-dependent manner in WT animals and changed at its higher dose the phenotype of the D3KO animals from a morphine-resistant state to a morphine-responsive state, (4) block of D1R function had an aging-dependent effect on thermal withdrawal latencies in control animals that, in old animals, was stronger than that of low-dose morphine. Lastly, (5) block of D1R function in young D3KO animals mimicked the behavioral phenotype observed in the aged WT. Our proof-of-concept data from the rodent animal model suggest that, with age, block of D1R function may be considered as an alternative to the use of morphine, to modulate the response to painful stimuli.
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Affiliation(s)
- Sophia Samir
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Alexander P Yllanes
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Perrine Lallemand
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Kori L Brewer
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Stefan Clemens
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States.
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22
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Blockade of neuronal dopamine D2 receptor attenuates morphine tolerance in mice spinal cord. Sci Rep 2016; 6:38746. [PMID: 28004735 PMCID: PMC5177930 DOI: 10.1038/srep38746] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 11/14/2016] [Indexed: 12/23/2022] Open
Abstract
Tolerance induced by morphine remains a major unresolved problem and significantly limits its clinical use. Recent evidences have indicated that dopamine D2 receptor (D2DR) is likely to be involved in morphine-induced antinociceptive tolerance. However, its exact effect and molecular mechanism remain unknown. In this study we examined the effect of D2DR on morphine antinociceptive tolerance in mice spinal cord. Chronic morphine treatment significantly increased levels of D2DR in mice spinal dorsal horn. And the immunoreactivity of D2DR was newly expressed in neurons rather than astrocytes or microglia both in vivo and in vitro. Blockade of D2DR with its antagonist (sulpiride and L-741,626, i.t.) attenuated morphine antinociceptive tolerance without affecting basal pain perception. Sulpiride (i.t.) also down-regulated the expression of phosphorylation of NR1, PKC, MAPKs and suppressed the activation of astrocytes and microglia induced by chronic morphine administration. Particularly, D2DR was found to interact with μ opioid receptor (MOR) in neurons, and chronic morphine treatment enhanced the MOR/D2DR interactions. Sulpiride (i.t.) could disrupt the MOR/D2DR interactions and attenuate morphine tolerance, indicating that neuronal D2DR in the spinal cord may be involved in morphine tolerance possibly by interacting with MOR. These results may present new opportunities for the treatment and management of morphine-induced antinociceptive tolerance which often observed in clinic.
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23
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Liu P, Xing B, Chu Z, Liu F, Lei G, Zhu L, Gao Y, Chen T, Dang YH. Dopamine D3 receptor knockout mice exhibit abnormal nociception in a sex-different manner. J Neurosci Res 2016; 95:1438-1445. [PMID: 27716994 DOI: 10.1002/jnr.23952] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 08/19/2016] [Accepted: 09/06/2016] [Indexed: 01/11/2023]
Abstract
Pain is a complex and subjective experience. Previous studies have shown that mice lacking the dopamine D3 receptor (D3RKO) exhibit hypoalgesia, indicating a role of the D3 receptor in modulation of nociception. Given that there are sex differences in pain perception, there may be differences in responses to nociceptive stimuli between male and female D3RKO mice. In the current study, we examined the role of the D3 receptor in modulating nociception in male and female D3RKO mice. Acute thermal pain was modeled by hot-plate test. This test was performed at different temperatures including 52°C, 55°C, and 58°C. The von Frey hair test was applied to evaluate mechanical pain. And persistent pain produced by peripheral tissue injury and inflammation was modeled by formalin test. In the hot-plate test, compared with wild-type (WT) mice, D3RKO mice generally exhibited longer latencies at each of the three temperatures. Specially, male D3RKO mice showed hypoalgesia compared with male WT mice when the temperature was 55°C, while for the female mice, there was a statistical difference between genotypes when the test condition was 52°C. In the von Frey hair test, both male and female D3RKO mice exhibited hypoalgesia. In the formalin test, the male D3RKO mice displayed a similar nociceptive behavior as their sex-matched WT littermates, whereas significantly depressed late-phase formalin-induced nociceptive behaviors were observed in the female mutants. These findings indicated that the D3 receptor affects nociceptive behaviors in a sex-specific manner and that its absence induces more analgesic behavior in the female knockout mice. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Peng Liu
- College of Medicine & Forensics, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, People's Republic of China
| | - Bo Xing
- Xi'an Mental Health Center, Xi'an, Shaanxi, PR China
| | - Zheng Chu
- College of Medicine & Forensics, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, People's Republic of China
| | - Fei Liu
- College of Medicine & Forensics, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, People's Republic of China.,Affiliated Stomatology Hospital of Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, People's Republic of China
| | - Gang Lei
- College of Medicine & Forensics, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, People's Republic of China
| | - Li Zhu
- College of Medicine & Forensics, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, People's Republic of China
| | - Ya Gao
- College of Medicine & Forensics, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, People's Republic of China.,Key Laboratory of the Health Ministry for Forensic Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases of the Education Ministry, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Teng Chen
- College of Medicine & Forensics, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, People's Republic of China.,Key Laboratory of the Health Ministry for Forensic Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases of the Education Ministry, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Yong-Hui Dang
- College of Medicine & Forensics, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, People's Republic of China.,Key Laboratory of the Health Ministry for Forensic Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases of the Education Ministry, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
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24
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Connectome and molecular pharmacological differences in the dopaminergic system in restless legs syndrome (RLS): plastic changes and neuroadaptations that may contribute to augmentation. Sleep Med 2016; 31:71-77. [PMID: 27539027 DOI: 10.1016/j.sleep.2016.06.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/21/2016] [Accepted: 06/04/2016] [Indexed: 01/08/2023]
Abstract
Restless legs syndrome (RLS) is primarily treated with levodopa and dopaminergics that target the inhibitory dopamine receptor subtypes D3 and D2. The initial success of this therapy led to the idea of a hypodopaminergic state as the mechanism underlying RLS. However, multiple lines of evidence suggest that this simplified concept of a reduced dopamine function as the basis of RLS is incomplete. Moreover, long-term medication with the D2/D3 agonists leads to a reversal of the initial benefits of dopamine agonists and augmentation, which is a worsening of symptoms under therapy. The recent findings on the state of the dopamine system in RLS that support the notion that a dysfunction in the dopamine system may in fact induce a hyperdopaminergic state are summarized. On the basis of these data, the concept of a dynamic nature of the dopamine effects in a circadian context is presented. The possible interactions of cell adhesion molecules expressed by the dopaminergic systems and their possible effects on RLS and augmentation are discussed. Genome-wide association studies (GWAS) indicate a significantly increased risk for RLS in populations with genomic variants of the cell adhesion molecule receptor type protein tyrosine phosphatase D (PTPRD), and PTPRD is abundantly expressed by dopamine neurons. PTPRD may play a role in the reconfiguration of neural circuits, including shaping the interplay of G protein-coupled receptor (GPCR) homomers and heteromers that mediate dopaminergic modulation. Recent animal model data support the concept that interactions between functionally distinct dopamine receptor subtypes can reshape behavioral outcomes and change with normal aging. Additionally, long-term activation of one dopamine receptor subtype can increase the receptor expression of a different receptor subtype with opposite modulatory actions. Such dopamine receptor interactions at both spinal and supraspinal levels appear to play important roles in RLS. In addition, these interactions can extend to the adenosine A1 and A2A receptors, which are also prominently expressed in the striatum. Interactions between adenosine and dopamine receptors and dopaminergic cell adhesion molecules, including PTPRD, may provide new pharmacological targets for treating RLS. In summary, new treatment options for RLS that include recovery from augmentation will have to consider dynamic changes in the dopamine system that occur during the circadian cycle, plastic changes that can develop as a function of treatment or with aging, changes in the connectome based on alterations in cell adhesion molecules, and receptor interactions that may extend beyond the dopamine system itself.
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Abstract
This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, United States.
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Keeler BE, Lallemand P, Patel MM, de Castro Brás LE, Clemens S. Opposing aging-related shift of excitatory dopamine D1 and inhibitory D3 receptor protein expression in striatum and spinal cord. J Neurophysiol 2015; 115:363-9. [PMID: 26561599 DOI: 10.1152/jn.00390.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 11/06/2015] [Indexed: 12/18/2022] Open
Abstract
Normal aging is associated with a decrease in motor function, a concomitant increase in muscle stiffness and tone, and a decrease in dopamine (DA) levels in the spinal cord. The striatum plays a critical role in the control of motor function, and it receives strong DA innervation from the substantia nigra. However, locomotor activity also requires the activation of motoneurons in the lumbar spinal cord, which in the mouse express all five DA receptor subtypes (D1-D5). Of these, the D3 receptor (D3R) expresses the highest affinity to DA and mediates inhibitory actions, while activation of the lower-affinity D1 receptor (D1R) system promotes excitatory effects. To test whether the aging-related decrease in DA levels is associated with corresponding changes in DA receptor protein expression levels, we probed with Western blot and immunohistochemical techniques for D1R and D3R protein expression levels over the normal life span of the mouse. We found that with age D1R expression levels increased in both striatum and spinal cord, while D3R expression levels remained stable in the striatum or slightly decreased in the spinal cord. The resulting D1-to-D3 ratio indicates a strong upregulation of D1R-mediated pathways in old animals, which is particularly pronounced in the lumbar spinal cord. These data suggest that aging may be associated with a shift in DA-mediated pathways in striatum and spinal cord, which in turn could be an underlying factor in the emergence of aging- and DA-related motor dysfunctions such as Parkinson's disease or Restless Legs Syndrome (RLS).
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Affiliation(s)
- Benjamin E Keeler
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Perrine Lallemand
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Mukund M Patel
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Lisandra E de Castro Brás
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Stefan Clemens
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
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Morioka N, Sugimoto T, Sato K, Okazaki S, Saeki M, Hisaoka-Nakashima K, Nakata Y. The induction of Per1 expression by the combined treatment with glutamate, 5-hydroxytriptamine and dopamine initiates a ripple effect on Bmal1 and Cry1 mRNA expression via the ERK signaling pathway in cultured rat spinal astrocytes. Neurochem Int 2015; 90:9-19. [DOI: 10.1016/j.neuint.2015.06.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 06/18/2015] [Accepted: 06/27/2015] [Indexed: 11/30/2022]
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Sharples SA, Humphreys JM, Jensen AM, Dhoopar S, Delaloye N, Clemens S, Whelan PJ. Dopaminergic modulation of locomotor network activity in the neonatal mouse spinal cord. J Neurophysiol 2015; 113:2500-10. [PMID: 25652925 DOI: 10.1152/jn.00849.2014] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 01/29/2015] [Indexed: 01/08/2023] Open
Abstract
Dopamine is now well established as a modulator of locomotor rhythms in a variety of developing and adult vertebrates. However, in mice, while all five dopamine receptor subtypes are present in the spinal cord, it is unclear which receptor subtypes modulate the rhythm. Dopamine receptors can be grouped into two families-the D1/5 receptor group and the D2/3/4 group, which have excitatory and inhibitory effects, respectively. Our data suggest that dopamine exerts contrasting dose-dependent modulatory effects via the two receptor families. Our data show that administration of dopamine at concentrations >35 μM slowed and increased the regularity of a locomotor rhythm evoked by bath application of 5-hydroxytryptamine (5-HT) and N-methyl-d(l)-aspartic acid (NMA). This effect was independent of the baseline frequency of the rhythm that was manipulated by altering the NMA concentration. We next examined the contribution of the D1- and D2-like receptor families on the rhythm. Our data suggest that the D1-like receptor contributes to enhancement of the stability of the rhythm. Overall, the D2-like family had a pronounced slowing effect on the rhythm; however, quinpirole, the D2-like agonist, also enhanced rhythm stability. These data indicate a receptor-dependent delegation of the modulatory effects of dopamine on the spinal locomotor pattern generator.
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Affiliation(s)
- Simon A Sharples
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | | | - A Marley Jensen
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina; and
| | - Sunny Dhoopar
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Nicole Delaloye
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Stefan Clemens
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina; and
| | - Patrick J Whelan
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta, Canada
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Nijs J, Meeus M, Versijpt J, Moens M, Bos I, Knaepen K, Meeusen R. Brain-derived neurotrophic factor as a driving force behind neuroplasticity in neuropathic and central sensitization pain: a new therapeutic target? Expert Opin Ther Targets 2014; 19:565-76. [PMID: 25519921 DOI: 10.1517/14728222.2014.994506] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Central sensitization is a form of maladaptive neuroplasticity underlying many chronic pain disorders, including neuropathic pain, fibromyalgia, whiplash, headache, chronic pelvic pain syndrome and some forms of osteoarthritis, low back pain, epicondylitis, shoulder pain and cancer pain. Brain-derived neurotrophic factor (BDNF) is a driving force behind neuroplasticity, and it is therefore crucial for neural maintenance and repair. However, BDNF also contributes to sensitization of pain pathways, making it an interesting novel therapeutic target. AREAS COVERED An overview of BDNF's sensitizing capacity at every level of the pain pathways is presented, including the peripheral nociceptors, dorsal root ganglia, spinal dorsal horn neurons, and brain descending inhibitory and facilitatory pathways. This is followed by the presentation of several potential therapeutic options, ranging from indirect influencing of BDNF levels (using exercise therapy, anti-inflammatory drugs, melatonin, repetitive transcranial magnetic stimulation) to more specific targeting of BDNF's receptors and signaling pathways (blocking the proteinase-activated receptors 2-NK-κβ signaling pathway, administration of phencyclidine for antagonizing NMDA receptors, or blockade of the adenosine A2A receptor). EXPERT OPINION This section focuses on combining pharmacotherapy with multimodal rehabilitation for balancing the deleterious and therapeutic effects of BNDF treatment in chronic pain patients, as well as accounting for the complex and biopsychosocial nature of chronic pain.
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Affiliation(s)
- Jo Nijs
- Pain in Motion international research group
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