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Ford ZK, Reker AN, Chen S, Kadakia F, Bunk A, Davidson S. Cannabinoid Receptor 1 Expression in Human Dorsal Root Ganglia and CB13-Induced Bidirectional Modulation of Sensory Neuron Activity. FRONTIERS IN PAIN RESEARCH 2022; 2:721332. [PMID: 35295508 PMCID: PMC8915700 DOI: 10.3389/fpain.2021.721332] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 10/08/2021] [Indexed: 12/23/2022] Open
Abstract
Cannabinoid receptors have been identified as potential targets for analgesia from studies on animal physiology and behavior, and from human clinical trials. Here, we sought to improve translational understanding of the mechanisms of cannabinoid-mediated peripheral analgesia. Human lumbar dorsal root ganglia were rapidly recovered from organ donors to perform physiological and anatomical investigations into the potential for cannabinoids to mediate analgesia at the level of the peripheral nervous system. Anatomical characterization of in situ gene expression and immunoreactivity showed that 61 and 53% of human sensory neurons express the CB1 gene and receptor, respectively. Calcium influx evoked by the algogen capsaicin was measured by Fura-2AM in dissociated human sensory neurons pre-exposed to the inflammatory mediator prostaglandin E2 (PGE2) alone or together with CB13 (1 μM), a cannabinoid agonist with limited blood–brain barrier permeability. Both a higher proportion of neurons and a greater magnitude of response to capsaicin were observed after exposure to CB13, indicating cannabinoid-mediated sensitization. In contrast, membrane properties measured by patch-clamp electrophysiology demonstrated that CB13 suppressed excitability and reduced action potential discharge in PGE2-pre-incubated sensory neurons, suggesting the suppression of sensitization. This bidirectional modulation of sensory neuron activity suggests that cannabinoids may suppress overall membrane excitability while simultaneously enhancing responsivity to TRPV1-mediated stimuli. We conclude that peripherally restricted cannabinoids may have both pro- and anti-nociceptive effects in human sensory neurons.
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Affiliation(s)
- Zachary K Ford
- Neuroscience Graduate Program, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Ashlie N Reker
- Department of Anesthesiology and Pain Research Center, University of Cincinnati, College of Medicine, Cincinnati, OH, United States
| | - Sisi Chen
- Department of Anesthesiology and Pain Research Center, University of Cincinnati, College of Medicine, Cincinnati, OH, United States
| | - Feni Kadakia
- Neuroscience Graduate Program, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Alexander Bunk
- Neuroscience Graduate Program, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Steve Davidson
- Neuroscience Graduate Program, College of Medicine, University of Cincinnati, Cincinnati, OH, United States.,Department of Anesthesiology and Pain Research Center, University of Cincinnati, College of Medicine, Cincinnati, OH, United States
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2
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Ford NC, Barpujari A, He SQ, Huang Q, Zhang C, Dong X, Guan Y, Raja SN. Role of primary sensory neurone cannabinoid type-1 receptors in pain and the analgesic effects of the peripherally acting agonist CB-13 in mice. Br J Anaesth 2022; 128:159-173. [PMID: 34844727 PMCID: PMC8787781 DOI: 10.1016/j.bja.2021.10.020] [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: 06/30/2021] [Revised: 09/27/2021] [Accepted: 10/14/2021] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Cannabinoid type-1 receptors (CB1Rs) are expressed in primary sensory neurones, but their role in pain modulation remains unclear. METHODS We produced Pirt-CB1R conditional knockout (cKO) mice to delete CB1Rs in primary sensory neurones selectively, and used behavioural, pharmacological, and electrophysiological approaches to examine the influence of peripheral CB1R signalling on nociceptive and inflammatory pain. RESULTS Conditional knockout of Pirt-CB1R did not alter mechanical or heat nociceptive thresholds, complete Freund adjuvant-induced inflammation, or heat hyperalgesia in vivo. The intrinsic membrane properties of small-diameter dorsal root ganglion neurones were also comparable between cKO and wild-type mice. Systemic administration of CB-13, a peripherally restricted CB1/CB2R dual agonist (5 mg kg-1), inhibited nociceptive pain and complete Freund adjuvant-induced inflammatory pain. These effects of CB-13 were diminished in Pirt-CB1R cKO mice. In small-diameter neurones from wild-type mice, CB-13 concentration-dependently inhibited high-voltage activated calcium current (HVA-ICa) and induced a rightward shift of the channel open probability curve. The effects of CB-13 were significantly attenuated by AM6545 (a CB1R antagonist) and Pirt-CB1R cKO. CONCLUSION CB1R signalling in primary sensory neurones did not inhibit nociceptive or inflammatory pain, or the intrinsic excitability of nociceptive neurones. However, peripheral CB1Rs are important for the analgesic effects of systemically administered CB-13. In addition, HVA-ICa inhibition appears to be a key ionic mechanism for CB-13-induced pain inhibition. Thus, peripherally restricted CB1R agonists could have utility for pain treatment.
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Affiliation(s)
- Neil C Ford
- Division of Pain Medicine, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Awinita Barpujari
- Division of Pain Medicine, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Shao-Qiu He
- Division of Pain Medicine, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Qian Huang
- Division of Pain Medicine, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Chi Zhang
- Division of Pain Medicine, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Xinzhong Dong
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neurological Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yun Guan
- Division of Pain Medicine, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neurological Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Srinivasa N Raja
- Division of Pain Medicine, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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3
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Anand U, Pacchetti B, Anand P, Sodergren MH. Cannabis-based medicines and pain: a review of potential synergistic and entourage effects. Pain Manag 2021; 11:395-403. [PMID: 33703917 DOI: 10.2217/pmt-2020-0110] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The recent legalization of medicinal cannabis in several jurisdictions has spurred the development of therapeutic formulations for chronic pain. Unlike pure delta-9-tetrahydrocannabinol (THC), full-spectrum products contain naturally occurring cannabinoids and have been reported to show improved efficacy or tolerability, attributed to synergy between cannabinoids and other components in the cannabis plant. Although 'synergy' indicates that two or more active compounds may produce an additive or combined effect greater than their individual analgesic effect, potentiation of the biological effect of a compound by related but inactive compounds, in combination, was termed the 'entourage effect'. Here, we review current evidence for potential synergistic and entourage effects of cannabinoids in pain relief. However, definitive clinical trials and in vitro functional studies are still required.
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Affiliation(s)
- Uma Anand
- Faculty of Medicine, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK
| | | | - Praveen Anand
- Faculty of Medicine, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK
| | - Mikael Hans Sodergren
- Faculty of Medicine, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK
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4
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Oultram JMJ, Pegler JL, Bowser TA, Ney LJ, Eamens AL, Grof CPL. Cannabis sativa: Interdisciplinary Strategies and Avenues for Medical and Commercial Progression Outside of CBD and THC. Biomedicines 2021; 9:biomedicines9030234. [PMID: 33652704 PMCID: PMC7996784 DOI: 10.3390/biomedicines9030234] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/16/2021] [Accepted: 02/23/2021] [Indexed: 12/11/2022] Open
Abstract
Cannabis sativa (Cannabis) is one of the world’s most well-known, yet maligned plant species. However, significant recent research is starting to unveil the potential of Cannabis to produce secondary compounds that may offer a suite of medical benefits, elevating this unique plant species from its illicit narcotic status into a genuine biopharmaceutical. This review summarises the lengthy history of Cannabis and details the molecular pathways that underpin the production of key secondary metabolites that may confer medical efficacy. We also provide an up-to-date summary of the molecular targets and potential of the relatively unknown minor compounds offered by the Cannabis plant. Furthermore, we detail the recent advances in plant science, as well as synthetic biology, and the pharmacology surrounding Cannabis. Given the relative infancy of Cannabis research, we go on to highlight the parallels to previous research conducted in another medically relevant and versatile plant, Papaver somniferum (opium poppy), as an indicator of the possible future direction of Cannabis plant biology. Overall, this review highlights the future directions of cannabis research outside of the medical biology aspects of its well-characterised constituents and explores additional avenues for the potential improvement of the medical potential of the Cannabis plant.
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Affiliation(s)
- Jackson M. J. Oultram
- Centre for Plant Science, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; (J.M.J.O.); (J.L.P.); (A.L.E.)
| | - Joseph L. Pegler
- Centre for Plant Science, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; (J.M.J.O.); (J.L.P.); (A.L.E.)
| | - Timothy A. Bowser
- CannaPacific Pty Ltd., 109 Ocean Street, Dudley, NSW 2290, Australia;
| | - Luke J. Ney
- School of Psychological Sciences, University of Tasmania, Hobart, TAS 7005, Australia;
| | - Andrew L. Eamens
- Centre for Plant Science, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; (J.M.J.O.); (J.L.P.); (A.L.E.)
| | - Christopher P. L. Grof
- Centre for Plant Science, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; (J.M.J.O.); (J.L.P.); (A.L.E.)
- CannaPacific Pty Ltd., 109 Ocean Street, Dudley, NSW 2290, Australia;
- Correspondence: ; Tel.: +612-4921-5858
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5
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Riquelme-Sandoval A, de Sá-Ferreira CO, Miyakoshi LM, Hedin-Pereira C. New Insights Into Peptide Cannabinoids: Structure, Biosynthesis and Signaling. Front Pharmacol 2020; 11:596572. [PMID: 33362550 PMCID: PMC7759141 DOI: 10.3389/fphar.2020.596572] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 10/19/2020] [Indexed: 01/01/2023] Open
Abstract
Classically, the endocannabinoid system (ECS) consists of endogenous lipids, of which the best known are anandamide (AEA) and 2 arachidonoylglycerol (2-AG), their enzyme machinery for synthesis and degradation and their specific receptors, cannabinoid receptor one (CB1) and cannabinoid receptor two (CB2). However, endocannabinoids also bind to other groups of receptors. Furthermore, another group of lipids are considered to be endocannabinoids, such as the fatty acid ethanolamides, the fatty acid primary amides and the monoacylglycerol related molecules. Recently, it has been shown that the hemopressin peptide family, derived from α and β chains of hemoglobins, is a new family of cannabinoids. Some studies indicate that hemopressin peptides are expressed in the central nervous system and peripheral tissues and act as ligands of these receptors, thus suggesting that they play a physiological role. In this review, we examine new evidence on lipid endocannabinoids, cannabinoid receptors and the modulation of their signaling pathways. We focus our discussion on the current knowledge of the pharmacological effects, the biosynthesis of the peptide cannabinoids and the new insights on the activation and modulation of cannabinoid receptors by these peptides. The novel peptide compounds derived from hemoglobin chains and their non-classical activation of cannabinoid receptors are only starting to be uncovered. It will be exciting to follow the ensuing discoveries, not only in reference to what is already known of the classical lipid endocannabinoids revealing more complex aspects of endocannabinoid system, but also as to its possibilities as a future therapeutic tool.
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Affiliation(s)
- Agustín Riquelme-Sandoval
- Laboratory of Cellular Neuroanatomy, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Caio O de Sá-Ferreira
- Laboratory of Cellular Neuroanatomy, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Leo M Miyakoshi
- Laboratory of Cellular Neuroanatomy, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Cecilia Hedin-Pereira
- Laboratory of Cellular Neuroanatomy, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,VPPCB-Fiocruz, Rio de Janeiro, Brazil.,National Institute of Science and Technology in Neuroimmunomodulation (INCT-NIM), Rio de Janeiro, Brazil
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6
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Alsalem M, Altarifi A, Haddad M, Azab B, Kalbouneh H, Imraish A, Saleh T, El-Salem K. Analgesic Effects and Impairment in Locomotor Activity Induced by Cannabinoid/Opioid Combinations in Rat Models of Chronic Pain. Brain Sci 2020; 10:brainsci10080523. [PMID: 32781705 PMCID: PMC7547378 DOI: 10.3390/brainsci10080523] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/02/2020] [Accepted: 08/03/2020] [Indexed: 11/20/2022] Open
Abstract
Both opioids and cannabinoids have well-known antinociceptive effects in different animal models of chronic pain. However, unwanted side effects limit their use. The aim of this study is to evaluate the antinociceptive effect of combining synthetic cannabinoids with subtherapeutic doses of opioids, and to evaluate the effects of these drugs/combinations on rat’s locomotor activity. Intra-plantar injection of Complete Freund’s Adjuvant (CFA) into the left hindpaw and intraperitoneal injection of streptozotocin (STZ) were used to induce inflammatory and diabetic neuropathic pain in adult male Sprague-Dawley rats, respectively. Von Frey filaments were used to assess the antinociceptive effects of opioids (morphine and tramadol) and the synthetic cannabinoids (HU210 and WIN55212) or their combinations on CFA and STZ-induced mechanical allodynia. Open field test was used to evaluate the effect of these drugs or their combinations on locomotion. HU210 and WIN55212 did not produce significant antinociceptive effect on inflammatory pain while only the maximal dose of HU210 (1 mg/kg) was effective in neuropathic pain. Only the maximal doses of morphine (3.2 mg/kg) and tramadol (10 mg/kg) had significant anti-allodynic effects in both models. Tramadol (1 mg/kg) enhanced the antinociceptive effects of WIN55212 but not HU210 in neuropathic pain with no effect on inflammatory pain. However, in open field test, the aforementioned combination did not change tramadol-induced depression of locomotion. Tramadol and WIN55212 combination produces antinociceptive effects in neuropathic but not inflammatory pain at low doses with no additional risk of locomotor impairment, which may be useful in clinical practice.
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Affiliation(s)
- Mohammad Alsalem
- Faculty of Medicine, The University of Jordan, Amman 11942, Jordan; (B.A.); (H.K.)
- Correspondence:
| | - Ahmad Altarifi
- Faculty of Medicine, Jordan University of Science and Technology, Irbid 22110, Jordan; (A.A.); (K.E.-S.)
| | - Mansour Haddad
- Faculty of Pharmacy, Philadelphia University, Amman 19392, Jordan;
| | - Belal Azab
- Faculty of Medicine, The University of Jordan, Amman 11942, Jordan; (B.A.); (H.K.)
| | - Heba Kalbouneh
- Faculty of Medicine, The University of Jordan, Amman 11942, Jordan; (B.A.); (H.K.)
| | - Amer Imraish
- Faculty of Science, The University of Jordan, Amman 11942, Jordan;
| | - Tareq Saleh
- Faculty of Medicine, The Hashemite University, Zarqa 13133, Jordan;
| | - Khalid El-Salem
- Faculty of Medicine, Jordan University of Science and Technology, Irbid 22110, Jordan; (A.A.); (K.E.-S.)
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7
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Haberberger RV, Barry C, Matusica D. Immortalized Dorsal Root Ganglion Neuron Cell Lines. Front Cell Neurosci 2020; 14:184. [PMID: 32636736 PMCID: PMC7319018 DOI: 10.3389/fncel.2020.00184] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 05/28/2020] [Indexed: 12/14/2022] Open
Abstract
Pain is one of the most significant causes of suffering and disability world-wide, and arguably the most burdensome global health challenge. The growing number of patients suffering from chronic pain conditions such as fibromyalgia, complex regional pain syndrome, migraine and irritable bowel syndrome, not only reflect the complexity and heterogeneity of pain types, but also our lack of understanding of the underlying mechanisms. Sensory neurons within the dorsal root ganglia (DRG) have emerged as viable targets for effective chronic pain therapy. However, DRG's contain different classes of primary sensory neurons including pain-associated nociceptive neurons, non-nociceptive temperature sensing, mechanosensory and chemoreceptive neurons, as well as multiple types of immune and endothelial cells. This cell-population heterogeneity makes investigations of individual subgroups of DRG neurons, such as nociceptors, difficult. In attempts to overcome some of these difficulties, a limited number of immortalized DRG-derived cell lines have been generated over the past few decades. In vitro experiments using DRG-derived cell lines have been useful in understanding sensory neuron function. In addition to retaining phenotypic similarities to primary cultured DRG neurons, these cells offer greater suitability for high throughput assays due to ease of culture, maintenance, growth efficiency and cost-effectiveness. For accurate interpretation and translation of results it is critical, however, that phenotypic similarities and differences of DRG-derived cells lines are methodically compared to native neurons. Published reports to date show notable variability in how these DRG-derived cells are maintained and differentiated. Understanding the cellular and molecular differences stemming from different culture methods, is essential to validate past and future experiments, and enable these cells to be used to their full potential. This review describes currently available DRG-derived cell lines, their known sensory and nociceptor specific molecular profiles, and summarize their morphological features related to differentiation and neurite outgrowth.
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Affiliation(s)
- Rainer Viktor Haberberger
- Anatomy & Histology, College of Medicine and Public Health, Flinders Health & Medical Research Institute, Flinders University, Adelaide, SA, Australia
| | - Christine Barry
- Anatomy & Histology, College of Medicine and Public Health, Flinders Health & Medical Research Institute, Flinders University, Adelaide, SA, Australia
| | - Dusan Matusica
- Anatomy & Histology, College of Medicine and Public Health, Flinders Health & Medical Research Institute, Flinders University, Adelaide, SA, Australia
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8
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Targeting Peripherally Restricted Cannabinoid Receptor 1, Cannabinoid Receptor 2, and Endocannabinoid-Degrading Enzymes for the Treatment of Neuropathic Pain Including Neuropathic Orofacial Pain. Int J Mol Sci 2020; 21:ijms21041423. [PMID: 32093166 PMCID: PMC7073137 DOI: 10.3390/ijms21041423] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/17/2020] [Accepted: 02/18/2020] [Indexed: 02/06/2023] Open
Abstract
Neuropathic pain conditions including neuropathic orofacial pain (NOP) are difficult to treat. Contemporary therapeutic agents for neuropathic pain are often ineffective in relieving pain and are associated with various adverse effects. Finding new options for treating neuropathic pain is a major priority in pain-related research. Cannabinoid-based therapeutic strategies have emerged as promising new options. Cannabinoids mainly act on cannabinoid 1 (CB1) and 2 (CB2) receptors, and the former is widely distributed in the brain. The therapeutic significance of cannabinoids is masked by their adverse effects including sedation, motor impairment, addiction and cognitive impairment, which are thought to be mediated by CB1 receptors in the brain. Alternative approaches have been developed to overcome this problem by selectively targeting CB2 receptors, peripherally restricted CB1 receptors and endocannabinoids that may be locally synthesized on demand at sites where their actions are pertinent. Many preclinical studies have reported that these strategies are effective for treating neuropathic pain and produce no or minimal side effects. Recently, we observed that inhibition of degradation of a major endocannabinoid, 2-arachydonoylglycerol, can attenuate NOP following trigeminal nerve injury in mice. This review will discuss the above-mentioned alternative approaches that show potential for treating neuropathic pain including NOP.
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9
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Nociceptor Signalling through ion Channel Regulation via GPCRs. Int J Mol Sci 2019; 20:ijms20102488. [PMID: 31137507 PMCID: PMC6566991 DOI: 10.3390/ijms20102488] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 05/08/2019] [Accepted: 05/13/2019] [Indexed: 12/23/2022] Open
Abstract
The prime task of nociceptors is the transformation of noxious stimuli into action potentials that are propagated along the neurites of nociceptive neurons from the periphery to the spinal cord. This function of nociceptors relies on the coordinated operation of a variety of ion channels. In this review, we summarize how members of nine different families of ion channels expressed in sensory neurons contribute to nociception. Furthermore, data on 35 different types of G protein coupled receptors are presented, activation of which controls the gating of the aforementioned ion channels. These receptors are not only targeted by more than 20 separate endogenous modulators, but can also be affected by pharmacotherapeutic agents. Thereby, this review provides information on how ion channel modulation via G protein coupled receptors in nociceptors can be exploited to provide improved analgesic therapy.
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10
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Guerrero-Alba R, Barragán-Iglesias P, González-Hernández A, Valdez-Moráles EE, Granados-Soto V, Condés-Lara M, Rodríguez MG, Marichal-Cancino BA. Some Prospective Alternatives for Treating Pain: The Endocannabinoid System and Its Putative Receptors GPR18 and GPR55. Front Pharmacol 2019; 9:1496. [PMID: 30670965 PMCID: PMC6331465 DOI: 10.3389/fphar.2018.01496] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 12/07/2018] [Indexed: 12/12/2022] Open
Abstract
Background: Marijuana extracts (cannabinoids) have been used for several millennia for pain treatment. Regarding the site of action, cannabinoids are highly promiscuous molecules, but only two cannabinoid receptors (CB1 and CB2) have been deeply studied and classified. Thus, therapeutic actions, side effects and pharmacological targets for cannabinoids have been explained based on the pharmacology of cannabinoid CB1/CB2 receptors. However, the accumulation of confusing and sometimes contradictory results suggests the existence of other cannabinoid receptors. Different orphan proteins (e.g., GPR18, GPR55, GPR119, etc.) have been proposed as putative cannabinoid receptors. According to their expression, GPR18 and GPR55 could be involved in sensory transmission and pain integration. Methods: This article reviews select relevant information about the potential role of GPR18 and GPR55 in the pathophysiology of pain. Results: This work summarized novel data supporting that, besides cannabinoid CB1 and CB2 receptors, GPR18 and GPR55 may be useful for pain treatment. Conclusion: There is evidence to support an antinociceptive role for GPR18 and GPR55.
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Affiliation(s)
- Raquel Guerrero-Alba
- Departamento de Fisiología y Farmacología, Centro de Ciencias Básicas, Universidad Autónoma de Aguascalientes, Aguascalientes, Mexico
| | - Paulino Barragán-Iglesias
- School of Behavioral and Brain Sciences and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, United States
| | - Abimael González-Hernández
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Santiago de Querétaro, Mexico
| | - Eduardo E Valdez-Moráles
- Cátedras CONACYT, Departamento de Cirugía, Centro de Ciencias Biomédicas, Universidad Autónoma de Aguascalientes, Aguascalientes, Mexico
| | - Vinicio Granados-Soto
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, Mexico City, Mexico
| | - Miguel Condés-Lara
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Santiago de Querétaro, Mexico
| | - Martín G Rodríguez
- Departamento de Fisiología y Farmacología, Centro de Ciencias Básicas, Universidad Autónoma de Aguascalientes, Aguascalientes, Mexico
| | - Bruno A Marichal-Cancino
- Departamento de Fisiología y Farmacología, Centro de Ciencias Básicas, Universidad Autónoma de Aguascalientes, Aguascalientes, Mexico
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11
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Sánchez-Zavaleta R, Cortés H, Avalos-Fuentes JA, García U, Segovia Vila J, Erlij D, Florán B. Presynaptic cannabinoid CB2 receptors modulate [ 3 H]-Glutamate release at subthalamo-nigral terminals of the rat. Synapse 2018; 72:e22061. [PMID: 30022523 DOI: 10.1002/syn.22061] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 07/12/2018] [Accepted: 07/13/2018] [Indexed: 11/08/2022]
Abstract
Recent studies suggested the expression of CB2 receptors in neurons of the CNS, however, most of these studies have only explored one aspect of the receptors, i.e., expression of protein, messenger RNA, or functional response, and more complete studies appear to be needed to establish adequately their role in the neuronal function. Electron microscopy studies showed the presence of CB2r in asymmetric terminals of the substantia nigra pars reticulata (SNr), and its mRNA appeared is expressed in the subthalamic nucleus. Here, we explore the expression, source, and functional effects of such receptors by different experimental approaches. Through PCR and immunochemistry, we showed mRNA and protein for CB2rs in slices and primary neuronal cultures from subthalamus. GW833972A, GW405833, and JHW 133, three CB2r agonists dose-dependent inhibited K+ -induced [3 H]-Glutamate release in slices of SNr, and the two antagonist/inverse agonists, JTE-907 and AM630, but not AM281, a CB1r antagonist, prevented GW833972A effect. Subthalamus lesions with kainic acid prevented GW833972A inhibition on release and decreased CB2r protein in nigral synaptosomes, thus nigral CB2rs originate in subthalamus. Inhibition of [3 H]-Glutamate release was PTX- and gallein-sensitive, suggesting a Giβγ -mediated effect. P/Q Ca2+ -type channel blocker, ω-Agatoxin-TK, also inhibited the [3 H]-Glutamate release, this effect was occluded with GW833972A inhibition, indicating that the βγ subunit effect is exerted on Ca2+ channel activity. Finally, microinjections of GW833972A in SNr induced contralateral turning. Our data showed that presynaptic CB2rs inhibit [3 H]-Glutamate release in subthalamo-nigral terminals by P/Q-channels modulation through the Giβγ subunit and suggested their participation in motor behavior.
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Affiliation(s)
- Rodolfo Sánchez-Zavaleta
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - Hernán Cortés
- Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra, Ciudad de México, México
| | - José Arturo Avalos-Fuentes
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - Ubaldo García
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - José Segovia Vila
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - David Erlij
- Department of Physiology, SUNY Downstate Medical Center, Brooklyn, New York
| | - Benjamín Florán
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
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12
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Jee Kim M, Tanioka M, Woo Um S, Hong SK, Hwan Lee B. Analgesic effects of FAAH inhibitor in the insular cortex of nerve-injured rats. Mol Pain 2018; 14:1744806918814345. [PMID: 30380982 PMCID: PMC6247483 DOI: 10.1177/1744806918814345] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/10/2018] [Accepted: 09/30/2018] [Indexed: 01/04/2023] Open
Abstract
The insular cortex is an important region of brain involved in the processing of pain and emotion. Recent studies indicate that lesions in the insular cortex induce pain asymbolia and reverse neuropathic pain. Endogenous cannabinoids (endocannabinoids), which have been shown to attenuate pain, are simultaneously degraded by fatty acid amide hydrolase (FAAH) that halts the mechanisms of action. Selective inhibitor URB597 suppresses FAAH activity by conserving endocannabinoids, which reduces pain. The present study examined the analgesic effects of URB597 treatment in the insular cortex of an animal model of neuropathic pain. Under pentobarbital anesthesia, male Sprague-Dawley rats were subjected to nerve injury and cannula implantation. On postoperative day 14, rodents received microinjection of URB597 into the insular cortex. In order to verify the analgesic mechanisms of URB597, cannabinoid 1 receptor (CB1R) antagonist AM251, peroxisome proliferator-activated receptor alpha (PPAR alpha) antagonist GW6471, and transient receptor potential vanilloid 1 (TRPV1) antagonist Iodoresiniferatoxin (I-RTX) were microinjected 15 min prior to URB597 injection. Changes in mechanical allodynia were measured using the von-Frey test. Expressions of CB1R, N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD), and TRPV1 significantly increased in the neuropathic pain group compared to the sham-operated control group. Mechanical threshold and expression of NAPE-PLD significantly increased in groups treated with 2 nM and 4 nM URB597 compared with the vehicle-injected group. Blockages of CB1R and PPAR alpha diminished the analgesic effects of URB597. Inhibition of TRPV1 did not effectively reduce the effects of URB597 but attenuated expression of NAPE-PLD compared with the URB597-injected group. In addition, optical imaging demonstrated that neuronal activity of the insular cortex was reduced following URB597 treatment. Our results suggest that microinjection of FAAH inhibitor into the insular cortex causes analgesic effects by decreasing neural excitability and increasing signals related to the endogenous cannabinoid pathway in the insular cortex.
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Affiliation(s)
- Min Jee Kim
- Department of Physiology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Motomasa Tanioka
- Department of Physiology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Sun Woo Um
- Department of Physiology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Seong-Karp Hong
- Division of Bio and Health Sciences, Mokwon University, Daejeon, Republic of Korea
| | - Bae Hwan Lee
- Department of Physiology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
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13
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Eldeeb K, Leone-Kabler S, Howlett AC. Mouse Neuroblastoma CB 1 Cannabinoid Receptor-Stimulated [ 35S]GTPɣS Binding: Total and Antibody-Targeted Gα Protein-Specific Scintillation Proximity Assays. Methods Enzymol 2017; 593:1-21. [PMID: 28750799 PMCID: PMC6535336 DOI: 10.1016/bs.mie.2017.06.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
G protein-coupled receptors (GPCRs) are important regulators of cellular signaling functions and therefore are a major target for drug discovery. The CB1 cannabinoid receptor is among the most highly expressed GPCRs in neurons, where it regulates many differentiated neuronal functions. One model system for studying the biochemistry of neuronal responses is the use of neuroblastoma cells originating from the C1300 tumor in the A/J mouse, including cloned cell lines NS20, N2A, N18TG2, N4TG1, and N1E-115, and various immortalized hybrids of neurons with N18TG2 cells. GPCR signal transduction is mediated through interaction with multiple types and subtypes of G proteins that transduce the receptor stimulus to effectors. The [35S]GTPɣS assay provides a valuable pharmacological method to evaluate efficacy and potency in the first step in GPCR signaling. Here, we present detailed protocols for the [35S]GTPɣS-binding assay to measure the total G protein binding and the antibody-targeted scintillation proximity assay to measure specific Gα proteins in neuroblastoma cell membrane preparations. This chapter presents step-by-step methods from cell culture, membrane preparation, assay procedures, and data analysis.
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Affiliation(s)
- Khalil Eldeeb
- Wake Forest School of Medicine, Winston-Salem, NC, United States; Campbell University School of Osteopathic Medicine, Lillington, NC, United States; AL-Azhar Faculty of Medicine, New Damietta, Egypt.
| | | | - Allyn C Howlett
- Wake Forest School of Medicine, Winston-Salem, NC, United States.
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Starowicz K, Finn DP. Cannabinoids and Pain: Sites and Mechanisms of Action. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2017; 80:437-475. [PMID: 28826543 DOI: 10.1016/bs.apha.2017.05.003] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The endocannabinoid system, consisting of the cannabinoid1 receptor (CB1R) and cannabinoid2 receptor (CB2R), endogenous cannabinoid ligands (endocannabinoids), and metabolizing enzymes, is present throughout the pain pathways. Endocannabinoids, phytocannabinoids, and synthetic cannabinoid receptor agonists have antinociceptive effects in animal models of acute, inflammatory, and neuropathic pain. CB1R and CB2R located at peripheral, spinal, or supraspinal sites are important targets mediating these antinociceptive effects. The mechanisms underlying the analgesic effects of cannabinoids likely include inhibition of presynaptic neurotransmitter and neuropeptide release, modulation of postsynaptic neuronal excitability, activation of the descending inhibitory pain pathway, and reductions in neuroinflammatory signaling. Strategies to dissociate the psychoactive effects of cannabinoids from their analgesic effects have focused on peripherally restricted CB1R agonists, CB2R agonists, inhibitors of endocannabinoid catabolism or uptake, and modulation of other non-CB1R/non-CB2R targets of cannabinoids including TRPV1, GPR55, and PPARs. The large body of preclinical evidence in support of cannabinoids as potential analgesic agents is supported by clinical studies demonstrating their efficacy across a variety of pain disorders.
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Affiliation(s)
- Katarzyna Starowicz
- Institute of Pharmacology, Polish Academy of Sciences, Laboratory of Pain Pathophysiology, Krakow, Poland
| | - David P Finn
- Pharmacology and Therapeutics, School of Medicine, Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, Ireland.
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Fischer MJM, Messlinger K. Cannabinoid and Vanilloid Effects of R(+)-Methanandamide in the Hemisected Meningeal Preparation. Cephalalgia 2016; 27:422-8. [PMID: 17448180 DOI: 10.1111/j.1468-2982.2007.01312.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The endogenous cannabinoid R(+)-methanandamide (mAEA) exerts differential anti- and pronociceptive effects by activating both cannabinoid (CB1) and vanilloid (TRPV1) receptors of nociceptive primary afferents. The significance of these effects in meningeal nociception was evaluated by modulation of calcitonin gene-related peptide (CGRP) release from meningeal afferents measured in an in vitro preparation of the hemisected rat skull. Temperature steps to 39°C and 45°C caused heat-dependent increases in CGRP release. One micromolar mAEA inhibited CGRP release at 32°C but facilitated it at 45°C. This effect was abolished in the presence of the TRPV1 receptor antagonist capsazepine. Lower doses of mAEA had no effect on basal or heat-evoked release. In the presence of the CB1 receptor antagonist SR141716 (0.2 μM) heat-stimulated increase in CGRP release was facilitated. CGRP release in the presence of SR141716 (0.2 μM) was further increased by adding mAEA at a concentration which had no effect on its own. These results confirm an opposing functional role for anandamide at CB1 and TRPV1 receptors on meningeal afferents.
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Affiliation(s)
- M J M Fischer
- Institute of Physiology and Experimental Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
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16
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Promising cannabinoid-based therapies for Parkinson's disease: motor symptoms to neuroprotection. Mol Neurodegener 2015; 10:17. [PMID: 25888232 PMCID: PMC4404240 DOI: 10.1186/s13024-015-0012-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 03/23/2015] [Indexed: 11/27/2022] Open
Abstract
Parkinson’s disease (PD) is a slow insidious neurological disorder characterized by a loss of dopaminergic neurons in the midbrain. Although several recent preclinical advances have proposed to treat PD, there is hardly any clinically proved new therapeutic for its cure. Increasing evidence suggests a prominent modulatory function of the cannabinoid signaling system in the basal ganglia. Hence, use of cannabinoids as a new therapeutic target has been recommended as a promising therapy for PD. The elements of the endocannabinoid system are highly expressed in the neural circuit of basal ganglia wherein they bidirectionally interact with dopaminergic, glutamatergic, and GABAergic signaling systems. As the cannabinoid signaling system undergoes a biphasic pattern of change during progression of PD, it explains the motor inhibition typically observed in patients with PD. Cannabinoid agonists such as WIN-55,212-2 have been demonstrated experimentally as neuroprotective agents in PD, with respect to their ability to suppress excitotoxicity, glial activation, and oxidative injury that causes degeneration of dopaminergic neurons. Additional benefits provided by cannabinoid related compounds including CE-178253, oleoylethanolamide, nabilone and HU-210 have been reported to possess efficacy against bradykinesia and levodopa-induced dyskinesia in PD. Despite promising preclinical studies for PD, use of cannabinoids has not been studied extensively at the clinical level. In this review, we reassess the existing evidence suggesting involvement of the endocannabinoid system in the cause, symptomatology, and treatment of PD. We will try to identify future threads of research that will help in the understanding of the potential therapeutic benefits of the cannabinoid system for treating PD.
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Schwitzer T, Schwan R, Angioi-Duprez K, Ingster-Moati I, Lalanne L, Giersch A, Laprevote V. The cannabinoid system and visual processing: a review on experimental findings and clinical presumptions. Eur Neuropsychopharmacol 2015; 25:100-12. [PMID: 25482685 DOI: 10.1016/j.euroneuro.2014.11.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 09/19/2014] [Accepted: 11/04/2014] [Indexed: 01/27/2023]
Abstract
Cannabis is one of the most prevalent drugs used worldwide. Regular cannabis use is associated with impairments in highly integrative cognitive functions such as memory, attention and executive functions. To date, the cerebral mechanisms of these deficits are still poorly understood. Studying the processing of visual information may offer an innovative and relevant approach to evaluate the cerebral impact of exogenous cannabinoids on the human brain. Furthermore, this knowledge is required to understand the impact of cannabis intake in everyday life, and especially in car drivers. Here we review the role of the endocannabinoids in the functioning of the visual system and the potential involvement of cannabis use in visual dysfunctions. This review describes the presence of the endocannabinoids in the critical stages of visual information processing, and their role in the modulation of visual neurotransmission and visual synaptic plasticity, thereby enabling them to alter the transmission of the visual signal. We also review several induced visual changes, together with experimental dysfunctions reported in cannabis users. In the discussion, we consider these results in relation to the existing literature. We argue for more involvement of public health research in the study of visual function in cannabis users, especially because cannabis use is implicated in driving impairments.
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Affiliation(s)
- Thomas Schwitzer
- EA7298, INGRES, Université de Lorraine, Vandœuvre-lès-Nancy F-54000, France; Maison des Addictions, CHU Nancy, Nancy F-54000, France; Centre Psychothérapique de Nancy, Nancy F-54000, France; INSERM U1114, Fédération de Médecine Translationnelle de Strasbourg, Département de Psychiatrie, Centre Hospitalier Régional Universitaire de Strasbourg, Strasbourg F-67000, France
| | - Raymund Schwan
- EA7298, INGRES, Université de Lorraine, Vandœuvre-lès-Nancy F-54000, France; Maison des Addictions, CHU Nancy, Nancy F-54000, France; Centre d׳Investigation Clinique CIC-INSERM 9501, CHU Nancy, Nancy F-54000, France; Centre Psychothérapique de Nancy, Nancy F-54000, France
| | | | | | - Laurence Lalanne
- Clinique Psychiatrique, CHRU Strasbourg, FTMS, Strasbourg, F-67000, France; INSERM U1114, Physiopathologie et Psychopathologie Cognitive de la Schizophrénie, Hôpitaux Universitaires de Strasbourg, Strasbourg F-67000, France
| | - Anne Giersch
- INSERM U1114, Fédération de Médecine Translationnelle de Strasbourg, Département de Psychiatrie, Centre Hospitalier Régional Universitaire de Strasbourg, Strasbourg F-67000, France
| | - Vincent Laprevote
- EA7298, INGRES, Université de Lorraine, Vandœuvre-lès-Nancy F-54000, France; Maison des Addictions, CHU Nancy, Nancy F-54000, France; Centre d׳Investigation Clinique CIC-INSERM 9501, CHU Nancy, Nancy F-54000, France; Centre Psychothérapique de Nancy, Nancy F-54000, France.
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18
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Activation of CB1 inhibits NGF-induced sensitization of TRPV1 in adult mouse afferent neurons. Neuroscience 2014; 277:679-89. [PMID: 25088915 DOI: 10.1016/j.neuroscience.2014.07.041] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 06/12/2014] [Accepted: 07/02/2014] [Indexed: 01/02/2023]
Abstract
Transient receptor potential vanilloid 1 (TRPV1)-containing afferent neurons convey nociceptive signals and play an essential role in pain sensation. Exposure to nerve growth factor (NGF) rapidly increases TRPV1 activity (sensitization). In the present study, we investigated whether treatment with the selective cannabinoid receptor 1 (CB1) agonist arachidonyl-2'-chloroethylamide (ACEA) affects NGF-induced sensitization of TRPV1 in adult mouse dorsal root ganglion (DRG) afferent neurons. We found that CB1, NGF receptor tyrosine kinase A (trkA), and TRPV1 are present in cultured adult mouse small- to medium-sized afferent neurons and treatment with NGF (100ng/ml) for 30 min significantly increased the number of neurons that responded to capsaicin (as indicated by increased intracellular Ca(2 +) concentration). Pretreatment with the CB1 agonist ACEA (10nM) inhibited the NGF-induced response, and this effect of ACEA was reversed by a selective CB1 antagonist. Further, pretreatment with ACEA inhibited NGF-induced phosphorylation of AKT. Blocking PI3 kinase activity also attenuated the NGF-induced increase in the number of neurons that responded to capsaicin. Our results indicate that the analgesic effect of CB1 activation may in part be due to inhibition of NGF-induced sensitization of TRPV1 and also that the effect of CB1 activation is at least partly mediated by attenuation of NGF-induced increased PI3 signaling.
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19
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Jankowski MP, Ross JL, Weber JD, Lee FB, Shank AT, Hudgins RC. Age-dependent sensitization of cutaneous nociceptors during developmental inflammation. Mol Pain 2014; 10:34. [PMID: 24906209 PMCID: PMC4059454 DOI: 10.1186/1744-8069-10-34] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 05/22/2014] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND It is well-documented that neonates can experience pain after injury. However, the contribution of individual populations of sensory neurons to neonatal pain is not clearly understood. Here we characterized the functional response properties and neurochemical phenotypes of single primary afferents after injection of carrageenan into the hairy hindpaw skin using a neonatal ex vivo recording preparation. RESULTS During normal development, we found that individual afferent response properties are generally unaltered. However, at the time period in which some sensory neurons switch their neurotrophic factor responsiveness, we observe a functional switch in slowly conducting, broad spiking fibers ("C"-fiber nociceptors) from mechanically sensitive and thermally insensitive (CM) to polymodal (CPM). Cutaneous inflammation induced prior to this switch (postnatal day 7) specifically altered mechanical and heat responsiveness, and heat thresholds in fast conducting, broad spiking ("A"-fiber) afferents. Furthermore, hairy skin inflammation at P7 transiently delayed the functional shift from CM to CPM. Conversely, induction of cutaneous inflammation after the functional switch (at P14) caused an increase in mechanical and thermal responsiveness exclusively in the CM and CPM neurons. Immunocytochemical analysis showed that inflammation at either time point induced TRPV1 expression in normally non-TRPV1 expressing CPMs. Realtime PCR and western blotting analyses revealed that specific receptors/channels involved in sensory transduction were differentially altered in the DRGs depending on whether inflammation was induced prior to or after the functional changes in afferent prevalence. CONCLUSION These data suggest that the mechanisms of neonatal pain development may be generated by different afferent subtypes and receptors/channels in an age-related manner.
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Affiliation(s)
- Michael P Jankowski
- Department of Anesthesia, Division of Pain Management, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave MLC 6016, Cincinnati, OH 45229, USA.
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20
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de Vries M, van Rijckevorsel DCM, Wilder-Smith OHG, van Goor H. Dronabinol and chronic pain: importance of mechanistic considerations. Expert Opin Pharmacother 2014; 15:1525-34. [PMID: 24819592 DOI: 10.1517/14656566.2014.918102] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Although medicinal cannabis has been used for many centuries, the therapeutic potential of delta-9-tetrahydrocannabinol (Δ9-THC; international non-proprietary name = dronabinol) in current pain management remains unclear. Several pharmaceutical products with defined natural or synthesized Δ9-THC content have been developed, resulting in increasing numbers of clinical trials investigating the analgesic efficacy of dronabinol in various pain conditions. Different underlying pain mechanisms, including sensitization of nociceptive sensory pathways and alterations in cognitive and autonomic processing, might explain the varying analgesic effects of dronabinol in chronic pain states. AREAS COVERED The pharmacokinetics, pharmacodynamics and mechanisms of action of products with a defined dronabinol content are summarized. Additionally, randomized clinical trials investigating the analgesic efficacy of pharmaceutical cannabis based products are reviewed for the treatment of chronic nonmalignant pain. EXPERT OPINION We suggest a mechanism-based approach beyond measurement of subjective pain relief to evaluate the therapeutic potential of dronabinol in chronic pain management. Development of objective mechanistic diagnostic biomarkers reflecting altered sensory and cognitive processing in the brain is essential to evaluate dronabinol induced analgesia, and to permit identification of responders and/or non-responders to dronabinol treatment.
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Affiliation(s)
- Marjan de Vries
- Radboud University Medical Center, Department of Surgery, Pain and Nociception Neuroscience Research Group , Route 690, PO Box 9101, 6500 HB Nijmegen , The Netherlands +31 024 361 0903 ; +31 024 354 0501 ;
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21
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Almeida V, Peres FF, Levin R, Suiama MA, Calzavara MB, Zuardi AW, Hallak JE, Crippa JA, Abílio VC. Effects of cannabinoid and vanilloid drugs on positive and negative-like symptoms on an animal model of schizophrenia: the SHR strain. Schizophr Res 2014; 153:150-9. [PMID: 24556469 DOI: 10.1016/j.schres.2014.01.039] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 01/14/2014] [Accepted: 01/16/2014] [Indexed: 02/06/2023]
Abstract
Studies have suggested that the endocannabinoid system is implicated in the pathophysiology of schizophrenia. We have recently reported that Spontaneously Hypertensive Rats (SHRs) present a deficit in social interaction that is ameliorated by atypical antipsychotics. In addition, SHRs display hyperlocomotion - reverted by atypical and typical antipsychotics. These results suggest that this strain could be useful to study negative symptoms (modeled by a decrease in social interaction) and positive symptoms (modeled by hyperlocomotion) of schizophrenia and the effects of potential drugs with an antipsychotic profile. The aim of this study was to investigate the effects of WIN55-212,2 (CB1/CB2 agonist), ACEA (CB1 agonist), rimonabant (CB1 inverse agonist), AM404 (anandamide uptake/metabolism inhibitor), capsaicin (agonist TRPV1) and capsazepine (antagonist TRPV1) on the social interaction and locomotion of control animals (Wistar rats) and SHRs. The treatment with rimonabant was not able to alter either the social interaction or the locomotion presented by Wistar rats (WR) and SHR at any dose tested. The treatment with WIN55-212,2 decreased locomotion (1mg/kg) and social interaction (0.1 and 0.3mg/kg) of WR, while the dose of 1mg/kg increased social interaction of SHR. The treatment with ACEA increased (0.3mg/kg) and decreased (1mg/kg) locomotion of both strain. The administration of AM404 increased social interaction and decreased locomotion of SHR (5mg/kg), and decreased social interaction and increased locomotion in WR (1mg/kg). The treatment with capsaicin (2.5mg/kg) increased social interaction of both strain and decreased locomotion of SHR (2.5mg/kg) and WR (0.5mg/kg and 2.5mg/kg). In addition, capsazepine (5mg/kg) decreased locomotion of both strains and increased (5mg/kg) and decreased (10mg/kg) social interaction of WR. Our results indicate that the schizophrenia-like behaviors displayed by SHR are differently altered by cannabinoid and vanilloid drugs when compared to control animals and suggest the endocannabinoid and the vanilloid systems as a potential target for the treatment of schizophrenia.
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Affiliation(s)
- Valéria Almeida
- Department of Pharmacology, Federal University of São Paulo, UNIFESP/EPM, Brazil; Laboratório Interdisciplinar de Neurociências Clínicas (LiNC), Department of Psychiatry, Federal University of São Paulo, UNIFESP/EPM, Brazil
| | - Fernanda F Peres
- Department of Pharmacology, Federal University of São Paulo, UNIFESP/EPM, Brazil; Laboratório Interdisciplinar de Neurociências Clínicas (LiNC), Department of Psychiatry, Federal University of São Paulo, UNIFESP/EPM, Brazil
| | - Raquel Levin
- Department of Pharmacology, Federal University of São Paulo, UNIFESP/EPM, Brazil; Laboratório Interdisciplinar de Neurociências Clínicas (LiNC), Department of Psychiatry, Federal University of São Paulo, UNIFESP/EPM, Brazil
| | - Mayra A Suiama
- Department of Pharmacology, Federal University of São Paulo, UNIFESP/EPM, Brazil; Laboratório Interdisciplinar de Neurociências Clínicas (LiNC), Department of Psychiatry, Federal University of São Paulo, UNIFESP/EPM, Brazil
| | - Mariana B Calzavara
- Laboratório Interdisciplinar de Neurociências Clínicas (LiNC), Department of Psychiatry, Federal University of São Paulo, UNIFESP/EPM, Brazil
| | - Antônio W Zuardi
- Department of Neuroscience and Behavior, University of São Paulo, Ribeirão Preto, Brazil; National Institute for Translational Medicine (INCT-TM, CNPq), Ribeirão Preto, Brazil
| | - Jaime E Hallak
- Department of Neuroscience and Behavior, University of São Paulo, Ribeirão Preto, Brazil; National Institute for Translational Medicine (INCT-TM, CNPq), Ribeirão Preto, Brazil
| | - José A Crippa
- Department of Neuroscience and Behavior, University of São Paulo, Ribeirão Preto, Brazil; National Institute for Translational Medicine (INCT-TM, CNPq), Ribeirão Preto, Brazil
| | - Vanessa C Abílio
- Department of Pharmacology, Federal University of São Paulo, UNIFESP/EPM, Brazil; Laboratório Interdisciplinar de Neurociências Clínicas (LiNC), Department of Psychiatry, Federal University of São Paulo, UNIFESP/EPM, Brazil.
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Ambrosino P, Soldovieri MV, Russo C, Taglialatela M. Activation and desensitization of TRPV1 channels in sensory neurons by the PPARα agonist palmitoylethanolamide. Br J Pharmacol 2013; 168:1430-44. [PMID: 23083124 DOI: 10.1111/bph.12029] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 10/03/2012] [Accepted: 10/10/2012] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND AND PURPOSE Palmitoylethanolamide (PEA) is an endogenous fatty acid amide displaying anti-inflammatory and analgesic actions. To investigate the molecular mechanism responsible for these effects, the ability of PEA and of pain-inducing stimuli such as capsaicin (CAP) or bradykinin (BK) to influence intracellular calcium concentrations ([Ca²⁺](i)) in peripheral sensory neurons, has been assessed in the present study. The potential involvement of the transcription factor PPARα and of TRPV1 channels in PEA-induced effects was also studied. EXPERIMENTAL APPROACH [Ca²⁺](i) was evaluated by single-cell microfluorimetry in differentiated F11 cells. Activation of TRPV1 channels was assessed by imaging and patch-clamp techniques in CHO cells transiently-transfected with rat TRPV1 cDNA. KEY RESULTS In F11 cells, PEA (1-30 μM) dose-dependently increased [Ca²⁺](i). The TRPV1 antagonists capsazepine (1 μM) and SB-366791 (1 μM), as well as the PPARα antagonist GW-6471 (10 μM), inhibited PEA-induced [Ca²⁺](i) increase; blockers of cannabinoid receptors were ineffective. PEA activated TRPV1 channels heterologously expressed in CHO cells; this effect appeared to be mediated at least in part by PPARα. When compared with CAP, PEA showed similar potency and lower efficacy, and caused stronger TRPV1 currents desensitization. Sub-effective PEA concentrations, closer to those found in vivo, counteracted CAP- and BK-induced [Ca²⁺](i) transients, as well as CAP-induced TRPV1 activation. CONCLUSIONS AND IMPLICATIONS Activation of PPARα and TRPV1 channels, rather than of cannabinoid receptors, largely mediate PEA-induced [Ca²⁺](i) transients in sensory neurons. Differential TRPV1 activation and desensitization by CAP and PEA might contribute to their distinct pharmacological profile, possibly translating into potentially relevant clinical differences.
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Affiliation(s)
- Paolo Ambrosino
- Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy
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23
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Duff G, Argaw A, Cecyre B, Cherif H, Tea N, Zabouri N, Casanova C, Ptito M, Bouchard JF. Cannabinoid receptor CB2 modulates axon guidance. PLoS One 2013; 8:e70849. [PMID: 23951024 PMCID: PMC3739758 DOI: 10.1371/journal.pone.0070849] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 06/28/2013] [Indexed: 01/29/2023] Open
Abstract
Navigation of retinal projections towards their targets is regulated by guidance molecules and growth cone transduction mechanisms. Here, we present in vitro and in vivo evidences that the cannabinoid receptor 2 (CB2R) is expressed along the retino-thalamic pathway and exerts a modulatory action on axon guidance. These effects are specific to CB2R since no changes were observed in mice where the gene coding for this receptor was altered (cnr2 (-/-)). The CB2R induced morphological changes observed at the growth cone are PKA dependent and require the presence of the netrin-1 receptor, Deleted in Colorectal Cancer. Interfering with endogenous CB2R signalling using pharmacological agents increased retinal axon length and induced aberrant projections. Additionally, cnr2 (-/-) mice showed abnormal eye-specific segregation of retinal projections in the dorsal lateral geniculate nucleus (dLGN) indicating CB2R's implication in retinothalamic development. Overall, this study demonstrates that the contribution of endocannabinoids to brain development is not solely mediated by CB1R, but also involves CB2R.
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MESH Headings
- Animals
- Axons/metabolism
- Axons/ultrastructure
- Cyclic AMP-Dependent Protein Kinases/genetics
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Embryo, Mammalian
- Endocannabinoids/metabolism
- Gene Expression Regulation, Developmental
- Geniculate Bodies/cytology
- Geniculate Bodies/growth & development
- Geniculate Bodies/metabolism
- Mice
- Mice, Knockout
- Netrin Receptors
- Neurogenesis/physiology
- Primary Cell Culture
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB2/deficiency
- Receptor, Cannabinoid, CB2/genetics
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Retinal Ganglion Cells/cytology
- Retinal Ganglion Cells/metabolism
- Visual Pathways/physiology
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Affiliation(s)
- Gabriel Duff
- School of Optometry, University of Montreal, Montreal, Quebec, Canada
- Faculty of Pharmacy, University of Montreal, Montreal, Quebec, Canada
| | - Anteneh Argaw
- School of Optometry, University of Montreal, Montreal, Quebec, Canada
- Department of Biomedical Science, Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada
| | - Bruno Cecyre
- School of Optometry, University of Montreal, Montreal, Quebec, Canada
| | - Hosni Cherif
- School of Optometry, University of Montreal, Montreal, Quebec, Canada
| | - Nicolas Tea
- School of Optometry, University of Montreal, Montreal, Quebec, Canada
| | - Nawal Zabouri
- School of Optometry, University of Montreal, Montreal, Quebec, Canada
| | | | - Maurice Ptito
- School of Optometry, University of Montreal, Montreal, Quebec, Canada
| | - Jean-François Bouchard
- School of Optometry, University of Montreal, Montreal, Quebec, Canada
- Faculty of Pharmacy, University of Montreal, Montreal, Quebec, Canada
- * E-mail:
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Svízenská IH, Brázda V, Klusáková I, Dubový P. Bilateral changes of cannabinoid receptor type 2 protein and mRNA in the dorsal root ganglia of a rat neuropathic pain model. J Histochem Cytochem 2013; 61:529-47. [PMID: 23657829 DOI: 10.1369/0022155413491269] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cannabinoid receptor type 2 (CB2R) plays a critical role in nociception. In contrast to cannabinoid receptor type 1 ligands, CB2R agonists do not produce undesirable central nervous system effects and thus promise to treat neuropathic pain that is often resistant to medical therapy. In the study presented here, we evaluated the bilateral distribution of the CB2R protein and messenger RNA (mRNA) in rat dorsal root ganglia (DRG) after unilateral peripheral nerve injury using immunohistochemistry, western blot, and in situ hybridization analysis. Unilateral chronic constriction injury (CCI) of the sciatic nerve induced neuropathic pain behavior and bilateral elevation of both CB2R protein and mRNA in lumbar L4-L5 as well as cervical C7-C8 DRG when compared with naive animals. CB2R protein and mRNA were increased not only in DRG neurons but also in satellite glial cells. The fact that changes appear bilaterally and (albeit at a lower level) even in the remote cervical DRG can be related to propagation of neuroinflammation alongside the neuraxis and to the neuroprotective effects of CB2R.
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Aghazadeh Tabrizi M, Baraldi PG, Saponaro G, Moorman AR, Romagnoli R, Preti D, Baraldi S, Corciulo C, Vincenzi F, Borea PA, Varani K. Design, Synthesis, and Pharmacological Properties of New Heteroarylpyridine/Heteroarylpyrimidine Derivatives as CB2 Cannabinoid Receptor Partial Agonists. J Med Chem 2013; 56:1098-112. [DOI: 10.1021/jm301527r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mojgan Aghazadeh Tabrizi
- Dipartimento di Scienze Farmaceutiche, Via Fossato di Mortara 17-19, Università di Ferrara, 44121, Ferrara, Italy
| | - Pier Giovanni Baraldi
- Dipartimento di Scienze Farmaceutiche, Via Fossato di Mortara 17-19, Università di Ferrara, 44121, Ferrara, Italy
| | - Giulia Saponaro
- Dipartimento di Scienze Farmaceutiche, Via Fossato di Mortara 17-19, Università di Ferrara, 44121, Ferrara, Italy
| | - Allan R. Moorman
- King Pharmaceuticals Research and Development, Inc., 4000 Centre Green Way,
Suite 300, Cary, North Carolina 27707, United States
| | - Romeo Romagnoli
- Dipartimento di Scienze Farmaceutiche, Via Fossato di Mortara 17-19, Università di Ferrara, 44121, Ferrara, Italy
| | - Delia Preti
- Dipartimento di Scienze Farmaceutiche, Via Fossato di Mortara 17-19, Università di Ferrara, 44121, Ferrara, Italy
| | - Stefania Baraldi
- Dipartimento di Scienze Farmaceutiche, Via Fossato di Mortara 17-19, Università di Ferrara, 44121, Ferrara, Italy
| | - Carmen Corciulo
- Dipartimento di Medicina Clinica e Sperimentale,
Sezione di Farmacologia, Università di Ferrara, 44121, Ferrara, Italy
| | - Fabrizio Vincenzi
- Dipartimento di Medicina Clinica e Sperimentale,
Sezione di Farmacologia, Università di Ferrara, 44121, Ferrara, Italy
| | - Pier Andrea Borea
- Dipartimento di Medicina Clinica e Sperimentale,
Sezione di Farmacologia, Università di Ferrara, 44121, Ferrara, Italy
| | - Katia Varani
- Dipartimento di Medicina Clinica e Sperimentale,
Sezione di Farmacologia, Università di Ferrara, 44121, Ferrara, Italy
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Brown I, Cascio MG, Rotondo D, Pertwee RG, Heys SD, Wahle KW. Cannabinoids and omega-3/6 endocannabinoids as cell death and anticancer modulators. Prog Lipid Res 2013; 52:80-109. [DOI: 10.1016/j.plipres.2012.10.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 10/05/2012] [Indexed: 01/18/2023]
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Peroxisome proliferator-activated receptor α mediates acute effects of palmitoylethanolamide on sensory neurons. J Neurosci 2012; 32:12735-43. [PMID: 22972997 DOI: 10.1523/jneurosci.0130-12.2012] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The amplitude of the depolarization-evoked Ca2+ transient is larger in dorsal root ganglion (DRG) neurons from tumor-bearing mice compared with that of neurons from naive mice, and the change is mimicked by coculturing DRG neurons with the fibrosarcoma cells used to generate the tumors (Khasabova et al., 2007). The effect of palmitoylethanolamide (PEA), a ligand for the peroxisome proliferator-activated receptor α (PPARα), was determined on the evoked-Ca2+ transient in the coculture condition. The level of PEA was reduced in DRG cells from tumor-bearing mice as well as those cocultured with fibrosarcoma cells. Pretreatment with PEA, a synthetic PPARα agonist (GW7647), or ARN077, an inhibitor of the enzyme that hydrolyzes PEA, acutely decreased the amplitude of the evoked Ca2+ transient in small DRG neurons cocultured with fibrosarcoma cells. The PPARα antagonist GW6471 blocked the effect of each. In contrast, the PPARα agonist was without effect in the control condition, but the antagonist increased the amplitude of the Ca2+ transient, suggesting that PPARα receptors are saturated by endogenous ligand under basal conditions. Effects of drugs on mechanical sensitivity in vivo paralleled their effects on DRG neurons in vitro. Local injection of ARN077 decreased mechanical hyperalgesia in tumor-bearing mice, and the effect was blocked by GW6471. These data support the conclusion that the activity of DRG neurons is rapidly modulated by PEA through a PPARα-dependent mechanism. Moreover, agents that increase the activity of PPARα may provide a therapeutic strategy to reduce tumor-evoked pain.
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Zádor F, Ötvös F, Benyhe S, Zimmer A, Páldy E. Inhibition of forebrain μ-opioid receptor signaling by low concentrations of rimonabant does not require cannabinoid receptors and directly involves μ-opioid receptors. Neurochem Int 2012; 61:378-88. [DOI: 10.1016/j.neuint.2012.05.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 04/12/2012] [Accepted: 05/10/2012] [Indexed: 01/22/2023]
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29
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Lisboa S, Guimarães F. Differential role of CB1 and TRPV1 receptors on anandamide modulation of defensive responses induced by nitric oxide in the dorsolateral periaqueductal gray. Neuropharmacology 2012; 62:2455-62. [DOI: 10.1016/j.neuropharm.2012.02.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 02/06/2012] [Accepted: 02/10/2012] [Indexed: 12/18/2022]
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30
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Atwood BK, Straiker A, Mackie K. CB₂ cannabinoid receptors inhibit synaptic transmission when expressed in cultured autaptic neurons. Neuropharmacology 2012; 63:514-23. [PMID: 22579668 DOI: 10.1016/j.neuropharm.2012.04.024] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/18/2012] [Accepted: 04/23/2012] [Indexed: 11/18/2022]
Abstract
The role of CB₂ in the central nervous system, particularly in neurons, has generated much controversy. Fueling the controversy are imperfect tools, which have made conclusive identification of CB₂ expressing neurons problematic. Imprecise localization of CB₂ has made it difficult to determine its function in neurons. Here we avoid the localization controversy and directly address the question if CB₂ can modulate neurotransmission. CB₂ was expressed in excitatory hippocampal autaptic neurons obtained from CB₁ null mice. Whole-cell patch clamp recordings were made from these neurons to determine the effects of CB₂ on short-term synaptic plasticity. CB₂ expression restored depolarization induced suppression of excitation to these neurons, which was lost following genetic ablation of CB₁. The endocannabinoid 2-arachidonylglycerol (2-AG) mimicked the effects of depolarization in CB₂ expressing neurons. Interestingly, ongoing basal production of 2-AG resulted in constitutive activation of CB₂, causing a tonic inhibition of neurotransmission that was relieved by the CB₂ antagonist AM630 or the diacylglycerol lipase inhibitor RHC80267. Through immunocytochemistry and analysis of spontaneous EPSCs, paired pulse ratios and coefficients of variation we determined that CB₂ exerts its function at a presynaptic site of action, likely through inhibition of voltage gated calcium channels. Therefore CB₂ expressed in neurons effectively mimics the actions of CB₁. Thus neuronal CB₂ is well suited to integrate into conventional neuronal endocannabinoid signaling processes, with its specific role determined by its unique and highly inducible expression profile.
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MESH Headings
- Animals
- Animals, Newborn
- Arachidonic Acids/antagonists & inhibitors
- Arachidonic Acids/metabolism
- Arachidonic Acids/pharmacology
- Astrocytes/cytology
- Cells, Cultured
- Endocannabinoids/antagonists & inhibitors
- Endocannabinoids/metabolism
- Endocannabinoids/pharmacology
- Enzyme Inhibitors/pharmacology
- Glycerides/antagonists & inhibitors
- Glycerides/metabolism
- Glycerides/pharmacology
- Heterozygote
- Hippocampus/cytology
- Hippocampus/drug effects
- Hippocampus/metabolism
- Lipoprotein Lipase/antagonists & inhibitors
- Mice
- Mice, Knockout
- Nerve Tissue Proteins/agonists
- Nerve Tissue Proteins/antagonists & inhibitors
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neurons/cytology
- Neurons/drug effects
- Neurons/metabolism
- Patch-Clamp Techniques
- Presynaptic Terminals/drug effects
- Presynaptic Terminals/metabolism
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB2/agonists
- Receptor, Cannabinoid, CB2/antagonists & inhibitors
- Receptor, Cannabinoid, CB2/genetics
- Receptor, Cannabinoid, CB2/metabolism
- Recombinant Fusion Proteins/metabolism
- Synaptic Transmission/drug effects
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Affiliation(s)
- Brady K Atwood
- Department of Psychological and Brain Sciences, Gill Center for Biomolecular Science, Indiana University, 1101 E. 10th Street, Bloomington, IN 47405, USA.
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Atwood BK, Wager-Miller J, Haskins C, Straiker A, Mackie K. Functional selectivity in CB(2) cannabinoid receptor signaling and regulation: implications for the therapeutic potential of CB(2) ligands. Mol Pharmacol 2011; 81:250-63. [PMID: 22064678 DOI: 10.1124/mol.111.074013] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Receptor internalization increases the flexibility and scope of G protein-coupled receptor (GPCR) signaling. CB(1) and CB(2) cannabinoid receptors undergo internalization after sustained exposure to agonists. However, it is not known whether different agonists internalize CB(2) to different extents. Because CB(2) is a promising therapeutic target, understanding its trafficking in response to different agonists is necessary for a complete understanding of its biology. Here we profile a number of cannabinoid receptor ligands and provide evidence for marked functional selectivity of cannabinoid receptor internalization. Classic, aminoalkylindole, bicyclic, cannabilactone, iminothiazole cannabinoid, and endocannabinoid ligands varied greatly in their effects on CB(1) and CB(2) trafficking. Our most striking finding was that (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl) pyrrolo-[1,2,3-d,e]-1,4-benzoxazin-6-yl]-1-naphthalenyl-methanone (WIN55,212-2) (and other aminoalkylindoles) failed to promote CB(2) receptor internalization, whereas 5-(1,1-dimethylheptyl)-2-(5-hydroxy-2-(3-hydroxypropyl)cyclohexyl)phenol (CP55,940) robustly internalized CB(2) receptors. Furthermore, WIN55,212-2 competitively antagonized CP55,940-induced CB(2) internalization. Despite these differences in internalization, both compounds activated CB(2) receptors as measured by extracellular signal-regulated kinase 1/2 phosphorylation and recruitment of β-arrestin(2) to the membrane. In contrast, whereas CP55,940 inhibited voltage-gated calcium channels via CB(2) receptor activation, WIN55,212-2 was ineffective on its own and antagonized the effects of CP55,940. On the basis of the differences we found between these two ligands, we also tested the effects of other cannabinoids on these signaling pathways and found additional evidence for functional selectivity of CB(2) ligands. These novel data highlight that WIN55,212-2 and other cannabinoids show strong functional selectivity at CB(2) receptors and suggest that different classes of CB(2) ligands may produce diverse physiological effects, emphasizing that each class needs to be separately evaluated for therapeutic efficacy.
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Affiliation(s)
- Brady K Atwood
- Department of Psychological and Brain Sciences, Gill Center for Biomolecular Science, Indiana University, Bloomington, Indiana 47405, USA
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Hama A, Sagen J. Activation of spinal and supraspinal cannabinoid-1 receptors leads to antinociception in a rat model of neuropathic spinal cord injury pain. Brain Res 2011; 1412:44-54. [PMID: 21813113 DOI: 10.1016/j.brainres.2011.07.031] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 07/12/2011] [Accepted: 07/13/2011] [Indexed: 12/21/2022]
Abstract
Activation of CNS cannabinoid subtype-1 (CB1) receptors has been shown to mediate the antinociceptive and other effects of systemically administered CB receptor agonists. The endogenous peptide CB receptor ligand hemopressin (HE) has previously demonstrated an antinociceptive effect in rats with a hind paw inflammation, without exhibiting characteristic CB1 receptor-mediated side-effects. The current study evaluated the effect of intrathecal (i.t.) and intracerebroventricular (i.c.v.) injection of HE in a rat model of neuropathic spinal cord injury (SCI) pain. The non-subtype selective CB receptor agonist WIN 55,212-2 was also centrally administered in SCI rats as a comparator. Four weeks following an acute compression of the mid-thoracic spinal cord, rats displayed markedly decreased hind paw withdrawal thresholds, indicative of below-level neuropathic pain. Central administration of WIN 55,212-2 significantly increased withdrawal thresholds, whereas HE did not. Hemopressin has been reported to block CB1 receptors in vitro, similar to the CB1 receptor antagonist rimonabant. Pretreatment with rimonabant completely blocked the antinociceptive effect of centrally administered WIN 55,212-2, but pretreatment with HE did not. While the data confirm that activation of either supraspinal or spinal CB1 receptors leads to significant antinociception in SCI rats, the current data do not support an antinociceptive effect from an acute blockade of central CB1 receptors, HE's putative antinociceptive mechanism, in neuropathic SCI rats. Although such a mechanism could be useful in other models of pain with a significant inflammatory component, the current data indicate that activation of CB1 receptors is needed to ameliorate neuropathic SCI pain.
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Affiliation(s)
- Aldric Hama
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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Brain cannabinoid CB₂ receptors modulate cocaine's actions in mice. Nat Neurosci 2011; 14:1160-6. [PMID: 21785434 PMCID: PMC3164946 DOI: 10.1038/nn.2874] [Citation(s) in RCA: 288] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Accepted: 06/13/2011] [Indexed: 11/09/2022]
Abstract
The presence and function of cannabinoid CB(2) receptors in the brain have been the subjects of much debate. We found that systemic, intranasal or intra-accumbens local administration of JWH133, a selective CB(2) receptor agonist, dose-dependently inhibited intravenous cocaine self-administration, cocaine-enhanced locomotion, and cocaine-enhanced accumbens extracellular dopamine in wild-type and CB(1) receptor knockout (CB(1)(-/-), also known as Cnr1(-/-)) mice, but not in CB(2)(-/-) (Cnr2(-/-)) mice. This inhibition was mimicked by GW405833, another CB(2) receptor agonist with a different chemical structure, and was blocked by AM630, a selective CB(2) receptor antagonist. Intra-accumbens administration of JWH133 alone dose-dependently decreased, whereas intra-accumbens administration of AM630 elevated, extracellular dopamine and locomotion in wild-type and CB(1)(-/-) mice, but not in CB(2)(-/-) mice. Intra-accumbens administration of AM630 also blocked the reduction in cocaine self-administration and extracellular dopamine produced by systemic administration of JWH133. These findings suggest that brain CB(2) receptors modulate cocaine's rewarding and locomotor-stimulating effects, likely by a dopamine-dependent mechanism.
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Donovan J, Grundy D. The differential effect of CB1 receptors on the discharge of afferent and efferent fibres supplying the rat jejunum. Neurogastroenterol Motil 2011; 23:567-e209. [PMID: 21414102 DOI: 10.1111/j.1365-2982.2011.01693.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND The cannabinoid receptor (CB(1) ) is expressed on GI sensory neurons and is suggested to play a role in food intake, inflammation and nociception. Expression of CB(1) in the nodose is influenced by nutritional status. Our aim was to determine the functional response of afferent and efferent fibres supplying the proximal jejunum to the CB(1) agonist docosatetraenylethanolamide (DEA) in fed and fasted animals. METHODS Experiments were performed on anesthetized rats, either fed ad libitum or fasted for 24 h. Blood pressure was recorded via the carotid artery and the proximal jejunum intubated to measure intraluminal pressure. A single paravascular nerve bundle was isolated and attached to an electrode for recording either afferent or efferent impulse traffic. KEY RESULTS Docosatetraenylethanolamide (1 mg kg(-1) , i.v.) had a depressor effect on blood pressure but surprisingly had little effect on afferent nerve activity in fed animals. In fasted animals the afferent response to DEA was augmented, however, the blood pressure effect was attenuated. In contrast, DEA caused a significant and prolonged increase in efferent firing, which was diminished in fasted animals. Bilateral cervical vagotomy had no effect on the DEA-mediated efferent response, however, hexamethonium (10 mg kg(-1) ) abolished excitation and unmasked an inhibitory effect of DEA. CONCLUSIONS & INFERENCES Docosatetraenylethanolamide has only a modest effect on intestinal afferent firing but a profound effect on efferent function, which is modulated by changes in nutritional status. The persistent response after vagotomy and block by hexamethonium suggests DEA is acting centrally, although there may be an inhibitory effect at the level of the postganglionic sympathetic neuron.
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Affiliation(s)
- J Donovan
- Department of Biomedical Sciences, University of Sheffield, Sheffield, UK.
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Riether D, Wu L, Cirillo PF, Berry A, Walker ER, Ermann M, Noya-Marino B, Jenkins JE, Albaugh D, Albrecht C, Fisher M, Gemkow MJ, Grbic H, Löbbe S, Möller C, O’Shea K, Sauer A, Shih DT, Thomson DS. 1,4-Diazepane compounds as potent and selective CB2 agonists: Optimization of metabolic stability. Bioorg Med Chem Lett 2011; 21:2011-6. [DOI: 10.1016/j.bmcl.2011.02.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 02/02/2011] [Accepted: 02/04/2011] [Indexed: 12/19/2022]
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36
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Fan Y, Hooker BA, Garrison TR, El-Kouhen OF, Idler KB, Holley-Shanks RR, Meyer MD, Yao BB. Pharmacological and molecular characterization of a dorsal root ganglion cell line expressing cannabinoid CB(1) and CB(2) receptors. Eur J Pharmacol 2011; 659:161-8. [PMID: 21458448 DOI: 10.1016/j.ejphar.2011.03.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 01/19/2011] [Accepted: 03/08/2011] [Indexed: 10/18/2022]
Abstract
The behavioral effects evoked by cannabinoids are primarily mediated by the CB(1) and CB(2) cannabinoid receptor subtypes. In vitro pharmacology of cannabinoid receptors has been elucidated using recombinant expression systems expressing either CB(1) or CB(2) receptors, with limited characterization in native cell lines endogenously expressing both CB(1) and CB(2) receptors. In the current study, we report the molecular and pharmacological characterization of the F-11 cell line, a hybridoma of rat dorsal root ganglion neurons and mouse neuroblastoma (N18TG2) cells, reported to endogenously express both cannabinoid receptors. The present study revealed that both receptors are of mouse origin in F-11 cells, and describes the relative gene expression levels between the two receptors. Pharmacological characterization of the F-11 cell line using cannabinoid agonists and antagonists indicated that the functional responses to these cannabinoid ligands are mainly mediated by CB(1) receptors. The non-selective cannabinoid ligands CP 55,940 and WIN 55212-2 are potent agonists and their efficacies in adenylate cyclase and MAPK assays are inhibited by the CB(1) selective antagonist SR141716A (SR1), but not by the CB(2) selective antagonist SR144528 (SR2). The endocannabinoid ligand 2AG, although not active in adenylate cyclase assays, was a potent activator of MAPK signaling in F-11 cells. The analysis of CB(1) and CB(2) receptor gene expression and the characterization of cannabinoid receptor pharmacology in the F-11 cell line demonstrate that it can be used as a tool for interrogating the endogenous signal transduction of cannabinoid receptor subtypes.
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Affiliation(s)
- Yihong Fan
- Neurological Diseases Research, Global Pharmaceutical Research & Development, Abbott Laboratories, R47W, AP9A, 100 Abbott Park Road, Abbott Park, IL 60064, USA.
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Pertwee RG, Howlett AC, Abood ME, Alexander SPH, Di Marzo V, Elphick MR, Greasley PJ, Hansen HS, Kunos G, Mackie K, Mechoulam R, Ross RA. International Union of Basic and Clinical Pharmacology. LXXIX. Cannabinoid receptors and their ligands: beyond CB₁ and CB₂. Pharmacol Rev 2011; 62:588-631. [PMID: 21079038 DOI: 10.1124/pr.110.003004] [Citation(s) in RCA: 1166] [Impact Index Per Article: 89.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
There are at least two types of cannabinoid receptors (CB(1) and CB(2)). Ligands activating these G protein-coupled receptors (GPCRs) include the phytocannabinoid Δ(9)-tetrahydrocannabinol, numerous synthetic compounds, and endogenous compounds known as endocannabinoids. Cannabinoid receptor antagonists have also been developed. Some of these ligands activate or block one type of cannabinoid receptor more potently than the other type. This review summarizes current data indicating the extent to which cannabinoid receptor ligands undergo orthosteric or allosteric interactions with non-CB(1), non-CB(2) established GPCRs, deorphanized receptors such as GPR55, ligand-gated ion channels, transient receptor potential (TRP) channels, and other ion channels or peroxisome proliferator-activated nuclear receptors. From these data, it is clear that some ligands that interact similarly with CB(1) and/or CB(2) receptors are likely to display significantly different pharmacological profiles. The review also lists some criteria that any novel "CB(3)" cannabinoid receptor or channel should fulfil and concludes that these criteria are not currently met by any non-CB(1), non-CB(2) pharmacological receptor or channel. However, it does identify certain pharmacological targets that should be investigated further as potential CB(3) receptors or channels. These include TRP vanilloid 1, which possibly functions as an ionotropic cannabinoid receptor under physiological and/or pathological conditions, and some deorphanized GPCRs. Also discussed are 1) the ability of CB(1) receptors to form heteromeric complexes with certain other GPCRs, 2) phylogenetic relationships that exist between CB(1)/CB(2) receptors and other GPCRs, 3) evidence for the existence of several as-yet-uncharacterized non-CB(1), non-CB(2) cannabinoid receptors; and 4) current cannabinoid receptor nomenclature.
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Affiliation(s)
- R G Pertwee
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, UK.
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Higuera-Matas A, Botreau F, Del Olmo N, Miguéns M, Olías O, Montoya GL, García-Lecumberri C, Ambrosio E. Periadolescent exposure to cannabinoids alters the striatal and hippocampal dopaminergic system in the adult rat brain. Eur Neuropsychopharmacol 2010; 20:895-906. [PMID: 20655181 DOI: 10.1016/j.euroneuro.2010.06.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 06/14/2010] [Accepted: 06/24/2010] [Indexed: 12/31/2022]
Abstract
In a previous work, we have shown that chronic administration of the cannabinoid agonist CP 55,940 (CP) during periadolescence increases cocaine self-administration in adult female rats, while it produces no such effect in males (Higuera-Matas et al., 2008). To extend these findings, we have analysed here the brains of the rats used as subjects in this previous work to evaluate the impact of the interaction between CP exposure and cocaine self-administration on dopaminergic parameters. We evaluated the levels of the dopamine transporter (DAT), and the D1- (D1R) and D2-type (D2R) dopaminergic receptors, as well as tyrosine hydroxylase (TH) mRNA in dopaminergic areas of the adult, cocaine self-administered, rat brain that had been chronically exposed to CP or vehicle (VH) during periadolescence. Control groups with CP/VH exposure and no self-administration experience were also included. In adult females, CP administration induced an up-regulation of DAT in the caudate-putamen that was maintained after cocaine self-administration. In males, CP induced an increase in the D1Rs content in the nucleus accumbens shell, which was not evident after cocaine self-administration. CP also reduced the expression of D2Rs in CA1 irrespective of sex. Finally, an increase in D1Rs was observed in the substantia nigra following cocaine self-administration. These findings suggest that a dopaminergic component modulated by cannabinoids may underlie the enhanced cocaine self-administration previously observed in adult female rats.
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Affiliation(s)
- Alejandro Higuera-Matas
- Department of Psychobiology, School of Psychology, UNED, C/Juan del Rosal no.10, 28040 Madrid, Spain
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Atwood BK, Mackie K. CB2: a cannabinoid receptor with an identity crisis. Br J Pharmacol 2010. [PMID: 20590558 DOI: 10.1111/j.1476-5381] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
CB(2) was first considered to be the 'peripheral cannabinoid receptor'. This title was bestowed based on its abundant expression in the immune system and presumed absence from the central nervous system. However, multiple recent reports question the absence of CB(2) from the central nervous system. For example, it is now well accepted that CB(2) is expressed in brain microglia during neuroinflammation. However, the extent of CB(2) expression in neurons has remained controversial. There have been studies claiming either extreme-its complete absence to its widespread expression-as well as everything in between. This review will discuss the reported tissue distribution of CB(2) with a focus on CB(2) in neurons, particularly those in the central nervous system as well as the implications of that presence. As CB(2) is an attractive therapeutic target for pain management and immune system modulation without overt psychoactivity, defining the extent of its presence in neurons will have a significant impact on drug discovery. Our recommendation is to encourage cautious interpretation of data that have been presented for and against CB(2)'s presence in neurons and to encourage continued rigorous study.
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Affiliation(s)
- Brady K Atwood
- The Gill Center and the Department of Psychological & Brain Sciences, Indiana University, Bloomington, IN 47405, USA
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40
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Abstract
CB(2) was first considered to be the 'peripheral cannabinoid receptor'. This title was bestowed based on its abundant expression in the immune system and presumed absence from the central nervous system. However, multiple recent reports question the absence of CB(2) from the central nervous system. For example, it is now well accepted that CB(2) is expressed in brain microglia during neuroinflammation. However, the extent of CB(2) expression in neurons has remained controversial. There have been studies claiming either extreme-its complete absence to its widespread expression-as well as everything in between. This review will discuss the reported tissue distribution of CB(2) with a focus on CB(2) in neurons, particularly those in the central nervous system as well as the implications of that presence. As CB(2) is an attractive therapeutic target for pain management and immune system modulation without overt psychoactivity, defining the extent of its presence in neurons will have a significant impact on drug discovery. Our recommendation is to encourage cautious interpretation of data that have been presented for and against CB(2)'s presence in neurons and to encourage continued rigorous study.
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Affiliation(s)
- Brady K Atwood
- The Gill Center and the Department of Psychological & Brain Sciences, Indiana University, Bloomington, IN 47405, USA
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Malone DT, Hill MN, Rubino T. Adolescent cannabis use and psychosis: epidemiology and neurodevelopmental models. Br J Pharmacol 2010; 160:511-22. [PMID: 20590561 DOI: 10.1111/j.1476-5381.2010.00721.x] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Cannabis is one of the most widely used illicit drugs among adolescents, and most users first experiment with it in adolescence. Adolescence is a critical phase for brain development, characterized by neuronal maturation and rearrangement processes, such as myelination, synaptic pruning and dendritic plasticity. The endocannabinoid system plays an important role in fundamental brain developmental processes such as neuronal cell proliferation, migration and differentiation. Therefore changes in endocannabinoid activity during this specific developmental phase, induced by the psychoactive component of marijuana, Delta(9)-tetrahydrocannabinol, might lead to subtle but lasting neurobiological changes that can affect brain functions and behaviour. In this review, we outline recent research into the endocannabinoid system focusing on the relationships between adolescent exposure to cannabinoids and increased risk for certain neuropsychiatric diseases such as schizophrenia, as highlighted by both human and animal studies. Particular emphasis will be given to the possible mechanisms by which adolescent cannabis consumption could render a person more susceptible to developing psychoses such as schizophrenia.
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Affiliation(s)
- Daniel T Malone
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia
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Abstract
The endocannabinoids anandamide and 2-arachydonoylglycerol (2-AG) are lipids naturally derived from membrane precursors which bind cannabinoid receptors (CB1, CB2). This endocannabinoid system is disturbed in schizophrenia. Indeed, there seems to be an association between schizophrenia and polymorphisms of the CB1 receptor gene. Moreover, CB1 receptors are found in higher density in the prefrontal cortex, hippocampus and basal ganglia of patients with schizophrenia. Similarly, anandamide levels are increased in the cerebrospinal fluid (CSF) and in the serum of schizophrenia patients, including during the prodromal state, suggesting that they may play a protective role in psychosis homeostasis. Future studies are needed to further explore the role of the endocannabinoid system in the pathophysiology of schizophrenia.
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Affiliation(s)
| | | | | | - Stéphane Potvin
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-514-251-4015; Fax: +1-514-251-2617
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Brain CB₂ Receptors: Implications for Neuropsychiatric Disorders. Pharmaceuticals (Basel) 2010; 3:2517-2553. [PMID: 27713365 PMCID: PMC4033937 DOI: 10.3390/ph3082517] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 08/04/2010] [Accepted: 08/09/2010] [Indexed: 12/26/2022] Open
Abstract
Although previously thought of as the peripheral cannabinoid receptor, it is now accepted that the CB2 receptor is expressed in the central nervous system on microglia, astrocytes and subpopulations of neurons. Expression of the CB2 receptor in the brain is significantly lower than that of the CB1 receptor. Conflicting findings have been reported on the neurological effects of pharmacological agents targeting the CB2 receptor under normal conditions. Under inflammatory conditions, CB2 receptor expression in the brain is enhanced and CB2 receptor agonists exhibit potent anti-inflammatory effects. These findings have prompted research into the CB2 receptor as a possible target for the treatment of neuroinflammatory and neurodegenerative disorders. Neuroinflammatory alterations are also associated with neuropsychiatric disorders and polymorphisms in the CB2 gene have been reported in depression, eating disorders and schizophrenia. This review will examine the evidence to date for a role of brain CB2 receptors in neuropsychiatric disorders.
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Sántha P, Jenes A, Somogyi C, Nagy I. The endogenous cannabinoid anandamide inhibits transient receptor potential vanilloid type 1 receptor-mediated currents in rat cultured primary sensory neurons. ACTA ACUST UNITED AC 2010; 97:149-58. [PMID: 20511124 DOI: 10.1556/aphysiol.97.2010.2.1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The activity of the transient receptor potential vanilloid type 1 ion channel (TRPV1) that is expressed by the great majority of polymodal nociceptors is pivotal for the development of inflammatory heat hyperalgesia. The responsiveness of TRPV1 is regulated by a series of intracellular signalling molecules including the cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA); increased or decreased PKA activity results in TRPV1 sensitisation or desensitisation, respectively. Activation of the cannabinoid 1 (CB1) receptor that is expressed by the majority of the TRPV1-expressing primary sensory neurons reduces PKA activity. Therefore, here we studied whether activation of the CB1 receptor resulted in reduced TRPV1-mediated responses in cultured rat primary sensory neurons. We found that TRPV1-mediated whole-cell currents were significantly reduced respectively, by 50% and 25% by 10 nM and 30 nM of the endogenous CB1 receptor agonist, anandamide. The PKA inhibitor, H89 (10 microM) also had a significant inhibitory effect on TRPV1-mediated currents ( approximately 70%). These findings suggest that activation of the CB1 receptor can reduce the activity of TRPV1 in primary sensory neurons, and that this inhibitory effect could be mediated through the reduction of PKA-mediated phosphorylation of TRPV1.
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Affiliation(s)
- P Sántha
- Section of Anaesthetics, Pain Medicine and Intensive Care, Department of Surgery and Cancer Faculty of Medicine, Chelsea and Westminster Hospital, London, UK
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Molecular mechanisms involved in the antitumor activity of cannabinoids on gliomas: role for oxidative stress. Cancers (Basel) 2010; 2:1013-26. [PMID: 24281104 PMCID: PMC3835116 DOI: 10.3390/cancers2021013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 05/14/2010] [Accepted: 05/17/2010] [Indexed: 11/17/2022] Open
Abstract
Cannabinoids, the active components of Cannabis sativa, have been shown to exert antiproliferative and proapoptotic effects on a wide spectrum of tumor cells and tissues. Of interest, cannabinoids have displayed great potency in reducing the growth of glioma tumors, one of the most aggressive CNS tumors, either in vitro or in animal experimental models curbing the growth of xenografts generated by subcutaneous or intrathecal injection of glioma cells in immune-deficient mice. Cannabinoids appear to be selective antitumoral agents as they kill glioma cells without affecting the viability of non-transformed cells. This review will summarize the anti-cancer properties that cannabinoids exert on gliomas and discuss their potential action mechanisms that appear complex, involving modulation of multiple key cell signaling pathways and induction of oxidative stress in glioma cells.
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Bartness TJ, Shrestha YB, Vaughan CH, Schwartz GJ, Song CK. Sensory and sympathetic nervous system control of white adipose tissue lipolysis. Mol Cell Endocrinol 2010; 318:34-43. [PMID: 19747957 PMCID: PMC2826518 DOI: 10.1016/j.mce.2009.08.031] [Citation(s) in RCA: 205] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Revised: 08/25/2009] [Accepted: 08/26/2009] [Indexed: 12/14/2022]
Abstract
Circulating factors are typically invoked to explain bidirectional communication between the CNS and white adipose tissue (WAT). Thus, initiation of lipolysis has been relegated primarily to adrenal medullary secreted catecholamines and the inhibition of lipolysis primarily to pancreatic insulin, whereas signals of body fat levels to the brain have been ascribed to adipokines such as leptin. By contrast, evidence is given for bidirectional communication between brain and WAT occurring via the sympathetic nervous system (SNS) and sensory innervation of this tissue. Using retrograde transneuronal viral tract tracers, the SNS outflow from brain to WAT has been defined. Functionally, sympathetic denervation of WAT blocks lipolysis to a variety of lipolytic stimuli. Using anterograde transneuronal viral tract tracers, the sensory input from WAT to brain has been defined. Functionally, these WAT sensory nerves respond electrophysiologically to increases in WAT SNS drive suggesting a possible neural negative feedback loop to regulate lipolysis.
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Affiliation(s)
- Timothy J Bartness
- Department of Biology and Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA 30302-4010, USA.
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Curto-Reyes V, Llames S, Hidalgo A, Menéndez L, Baamonde A. Spinal and peripheral analgesic effects of the CB2 cannabinoid receptor agonist AM1241 in two models of bone cancer-induced pain. Br J Pharmacol 2010; 160:561-73. [PMID: 20233215 DOI: 10.1111/j.1476-5381.2009.00629.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE The activation of CB(2) receptors induces analgesia in experimental models of chronic pain. The present experiments were designed to study whether the activation of peripheral or spinal CB(2) receptors relieves thermal hyperalgesia and mechanical allodynia in two models of bone cancer pain. EXPERIMENTAL APPROACH NCTC 2472 osteosarcoma or B16-F10 melanoma cells were intratibially inoculated to C3H/He and C57BL/6 mice. Thermal hyperalgesia was assessed by the unilateral hot plate test and mechanical allodynia by the von Frey test. AM1241 (CB(2) receptor agonist), AM251 (CB(1) receptor antagonist), SR144528 (CB(2) receptor antagonist) and naloxone were used. CB(2) receptor expression was measured by Western blot. KEY RESULTS AM1241 (0.3-10 mg.kg(-1)) abolished thermal hyperalgesia and mechanical allodynia in both tumour models. The antihyperalgesic effect was antagonized by subcutaneous, intrathecal or peri-tumour administration of SR144528. In contrast, the antiallodynic effect was inhibited by systemic or intrathecal, but not peri-tumour, injection of SR144528. The effects of AM1241 were unchanged by AM251 but were prevented by naloxone. No change in CB(2) receptor expression was found in spinal cord or dorsal root ganglia. CONCLUSIONS AND IMPLICATIONS Spinal CB(2) receptors are involved in the antiallodynic effect induced by AM1241 in two neoplastic models while peripheral and spinal receptors participate in the antihyperalgesic effects. Both effects were mediated by endogenous opiates. The use of drugs that activate CB(2) receptors could be a useful strategy to counteract bone cancer-induced pain symptoms.
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Affiliation(s)
- V Curto-Reyes
- Laboratorio de Farmacología, Facultad de Medicina, Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Universidad de Oviedo, Oviedo, Asturias, Spain
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Actions of ethanolamine on cultured sensory neurones from neonatal rats. Neurosci Lett 2010; 468:326-9. [DOI: 10.1016/j.neulet.2009.11.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Revised: 11/05/2009] [Accepted: 11/06/2009] [Indexed: 11/18/2022]
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Guindon J, Hohmann AG. The endocannabinoid system and pain. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2009; 8:403-21. [PMID: 19839937 DOI: 10.2174/187152709789824660] [Citation(s) in RCA: 307] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 06/24/2009] [Indexed: 12/29/2022]
Abstract
The therapeutic potential of cannabinoids has been the topic of extensive investigation following the discovery of cannabinoid receptors and their endogenous ligands. Cannabinoid receptors and their endogenous ligands are present at supraspinal, spinal and peripheral levels. Cannabinoids suppress behavioral responses to noxious stimulation and suppress nociceptive processing through activation of cannabinoid CB(1) and CB(2) receptor subtypes. Endocannabinoids, the brain's own cannabis-like substances, share the same molecular target as Delta(9)-tetrahydrocannabinol, the main psychoactive component in cannabis. Endocannabinoids serve as synaptic circuit breakers and regulate multiple physiological and pathological conditions, e.g. regulation of food intake, immunomodulation, inflammation, analgesia, cancer, addictive behavior, epilepsy and others. This review will focus on uncovering the roles of anandamide and 2-arachidonoylglycerol, the two best characterized endocannabinoids identified to date, in controlling nociceptive responding. The roles of anandamide and 2-arachidonoylglycerol, released under physiological conditions, in modulating nociceptive responding at different levels of the neuraxis will be emphasized in this review. Effects of modulation of endocannabinoid levels through inhibition of endocannabinoid hydrolysis and uptake is also compared with effects of exogenous administration of synthetic endocannabinoids in acute, inflammatory and neuropathic pain models. Finally, the therapeutic potential of the endocannabinoid signaling system is discussed in the context of identifying novel pharmacotherapies for the treatment of pain.
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Affiliation(s)
- Josée Guindon
- Neuroscience and Behavior Program, Department of Psychology, University of Georgia, Athens, GA 30602-3013, USA
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Rahn EJ, Hohmann AG. Cannabinoids as pharmacotherapies for neuropathic pain: from the bench to the bedside. Neurotherapeutics 2009; 6:713-37. [PMID: 19789075 PMCID: PMC2755639 DOI: 10.1016/j.nurt.2009.08.002] [Citation(s) in RCA: 208] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Neuropathic pain is a debilitating form of chronic pain resulting from nerve injury, disease states, or toxic insults. Neuropathic pain is often refractory to conventional pharmacotherapies, necessitating validation of novel analgesics. Cannabinoids, drugs that share the same target as Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the psychoactive ingredient in cannabis, have the potential to address this unmet need. Here, we review studies evaluating cannabinoids for neuropathic pain management in the clinical and preclinical literature. Neuropathic pain associated with nerve injury, diabetes, chemotherapeutic treatment, human immunodeficiency virus, multiple sclerosis, and herpes zoster infection is considered. In animals, cannabinoids attenuate neuropathic nociception produced by traumatic nerve injury, disease, and toxic insults. Effects of mixed cannabinoid CB(1)/CB(2) agonists, CB(2) selective agonists, and modulators of the endocannabinoid system (i.e., inhibitors of transport or degradation) are compared. Effects of genetic disruption of cannabinoid receptors or enzymes controlling endocannabinoid degradation on neuropathic nociception are described. Specific forms of allodynia and hyperalgesia modulated by cannabinoids are also considered. In humans, effects of smoked marijuana, synthetic Delta(9)-THC analogs (e.g., Marinol, Cesamet) and medicinal cannabis preparations containing both Delta(9)-THC and cannabidiol (e.g., Sativex, Cannador) in neuropathic pain states are reviewed. Clinical studies largely affirm that neuropathic pain patients derive benefits from cannabinoid treatment. Subjective (i.e., rating scales) and objective (i.e., stimulus-evoked) measures of pain and quality of life are considered. Finally, limitations of cannabinoid pharmacotherapies are discussed together with directions for future research.
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Affiliation(s)
- Elizabeth J. Rahn
- grid.213876.9000000041936738XNeuroscience and Behavior Program, Department of Psychology, University of Georgia, 30602-3013 Athens, GA
| | - Andrea G. Hohmann
- grid.213876.9000000041936738XNeuroscience and Behavior Program, Department of Psychology, University of Georgia, 30602-3013 Athens, GA
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