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Quintero JM, Diaz LE, Galve-Roperh I, Bustos RH, Leon MX, Beltran S, Dodd S. The endocannabinoid system as a therapeutic target in neuropathic pain: a review. Expert Opin Ther Targets 2024:1-17. [PMID: 39317147 DOI: 10.1080/14728222.2024.2407824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 09/19/2024] [Indexed: 09/26/2024]
Abstract
INTRODUCTION This review highlights the critical role of the endocannabinoid system (ECS) in regulating neuropathic pain and explores the therapeutic potential of cannabinoids. Understanding the mechanisms of the ECS, including its receptors, endogenous ligands, and enzymatic routes, can lead to innovative treatments for chronic pain, offering more effective therapies for neuropathic conditions. This review bridges the gap between preclinical studies and clinical applications by emphasizing ECS modulation for better pain management outcomes. AREAS COVERED A review mapped the existing literature on neuropathic pain and the effects of modulating the ECS using natural and synthetic cannabinoids. This analysis examined ECS components and their alterations in neuropathic pain, highlighting the peripheral, spinal, and supraspinal mechanisms. This review aimed to provide a thorough understanding of the therapeutic potential of cannabinoids in the management of neuropathic pain. EXPERT OPINION Advances in cannabinoid research have shown significant potential for the management of chronic neuropathic pain. The study emphasizes the need for high-quality clinical trials and collaborative efforts among researchers, clinicians, and regulatory bodies to ensure safe and effective integration of cannabinoids into pain management protocols. Understanding the mechanisms and optimizing cannabinoid formulations and delivery methods are crucial for enhancing therapeutic outcomes.
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Affiliation(s)
- Jose-Manuel Quintero
- Department of Clinical Pharmacology, Evidence-Based Therapeutics Group, Faculty of Medicine, Universidad de La Sabana and Clínica Universidad de La Sabana, Chía, Cundinamarca, Colombia
- Doctoral Programme of Biosciences, Universidad de La Sabana, Chía, Colombia
| | | | - Ismael Galve-Roperh
- Department of Biochemistry and Molecular Biology, School of Chemistry and Instituto de Investigación en Neuroquímica, Complutense University, Madrid, Spain
- Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS) and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Rosa-Helena Bustos
- Department of Clinical Pharmacology, Evidence-Based Therapeutics Group, Faculty of Medicine, Universidad de La Sabana and Clínica Universidad de La Sabana, Chía, Cundinamarca, Colombia
| | - Marta-Ximena Leon
- Grupo Dolor y Cuidados Paliativos, Universidad de La Sabana, Chía, Colombia
| | | | - Seetal Dodd
- Faculty of Medicine, Universidad de La Sabana, Chía, Colombia
- IMPACT - The Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Deakin University, Barwon Health, Geelong, Australia
- Centre for Youth Mental Health, University of Melbourne, Parkville, Australia
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Limerick G, Uniyal A, Ford N, He S, Grenald SA, Zhang C, Cui X, Sivanesan E, Dong X, Guan Y, Raja SN. Peripherally restricted cannabinoid and mu-opioid receptor agonists synergistically attenuate neuropathic mechanical hypersensitivity in mice. Pain 2024:00006396-990000000-00615. [PMID: 38815196 DOI: 10.1097/j.pain.0000000000003278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 04/02/2024] [Indexed: 06/01/2024]
Abstract
ABSTRACT Many medications commonly used to treat neuropathic pain are associated with significant, dose-limiting adverse effects, including sedation, dizziness, and fatigue. These adverse effects are due to the activity of these medications within the central nervous system. The objective of this work was to investigate the interactions between peripherally restricted cannabinoid receptor and mu-opioid receptor (MOR) agonists on ongoing and evoked neuropathic pain behaviors in mouse models. RNAscope analysis of cannabinoid receptor type 1 (CB1R) and MOR mRNA demonstrated that the mRNA of both receptors is colocalized in both mouse and human dorsal root ganglion. Single-cell RNAseq of dorsal root ganglion from chronic constriction injury mice showed that the mRNA of both receptors (Cnr1 and Oprm1) is coexpressed across different neuron clusters. Myc-CB1R and FLAG-MOR were cotransfected into immortalized HEK-293T cells and were found to interact at a subcellular level. We also find that CB-13 (a peripherally restricted dual CB1R and cannabinoid receptor type 2 agonist) and DALDA (a peripherally restricted MOR agonist) both attenuate mechanical hypersensitivity in a murine model of neuropathic pain. Using isobolographic analysis, we demonstrate that when coadministered, these agents synergistically attenuate mechanical hypersensitivity. Importantly, combination dosing of these agents does not cause any detectable preferential behaviors or motor impairment. However, repeated dosing of these agents is associated with the development of tolerance to these drugs. Collectively, these findings suggest that leveraging synergistic pain inhibition between cannabinoid receptor and MOR agonists in peripheral sensory neurons may be worth examining in patients with neuropathic pain.
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Affiliation(s)
| | - Ankit Uniyal
- Departments of Anesthesiology and Critical Care Medicine
| | - Neil Ford
- Departments of Anesthesiology and Critical Care Medicine
| | - ShaoQiu He
- Departments of Anesthesiology and Critical Care Medicine
| | | | - Chi Zhang
- Departments of Anesthesiology and Critical Care Medicine
| | - Xiang Cui
- Departments of Anesthesiology and Critical Care Medicine
| | | | - Xinzhong Dong
- Neuroscience
- Neurology and Neurosurgery and
- Dermatology, School of Medicine, The Johns Hopkins University, Baltimore, MD, United States
| | - Yun Guan
- Departments of Anesthesiology and Critical Care Medicine
- Neurology and Neurosurgery and
| | - Srinivasa N Raja
- Departments of Anesthesiology and Critical Care Medicine
- Neurology and Neurosurgery and
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Guenther KG, Xu Z, Romero J, Hillard CJ, Mackie K, Hohmann AG. Conditional deletion of CB2 cannabinoid receptors from peripheral sensory neurons eliminates CB2-mediated antinociceptive efficacy in a mouse model of carrageenan-induced inflammatory pain. Neuropharmacology 2023; 237:109601. [PMID: 37286073 PMCID: PMC10409300 DOI: 10.1016/j.neuropharm.2023.109601] [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: 11/30/2022] [Revised: 05/18/2023] [Accepted: 05/23/2023] [Indexed: 06/09/2023]
Abstract
CB2 cannabinoid receptor agonists suppress pathological pain in animal models and lack unwanted side effects commonly associated with direct activation of CB1 receptors. However, the types of pain most responsive to CB2 agonists are incompletely understood and cell types which underlie CB2-mediated therapeutic efficacy remain largely unknown. We previously reported that the CB2 receptor agonist LY2828360 reduced neuropathic nociception induced by toxic challenge with chemotherapeutic and anti-retroviral agents in mice. Whether these findings generalize to models of inflammatory pain is not known. Here we show that LY2828360 (10 mg/kg i.p.) reversed the maintenance of carrageenan-induced mechanical allodynia in female mice. Anti-allodynic efficacy was fully preserved in global CB1 knock out (KO) mice but absent in CB2 KO mice. The anti-allodynic efficacy of LY2828360 was absent in conditional KO (cKO) mice lacking CB2 receptors in peripheral sensory neurons (AdvillinCRE/+; CB2f/f) and preserved in cKO mice lacking CB2 receptors in microglia/macrophages expressing C-X3-C Motif Chemokine Receptor 1 (CX3CR1CRE/+; CB2f/f). Intraplantar administration of LY2828360 (30 μg i.pl.) reversed carrageenan-induced mechanical allodynia in CB2f/f but not AdvillinCRE/+; CB2f/f mice of both sexes. Thus, CB2 receptors in peripheral sensory neurons likely underlie the therapeutic effects of LY2828360 injection in the paw. Lastly, qRT-PCR analyses revealed that LY2828360 reduced carrageenan-induced increases in IL-1β and IL-10 mRNA in paw skin. Our results suggest that LY2828360 suppresses inflammatory nociception in mice through a neuronal CB2-dependent mechanism that requires peripheral sensory neuron CB2 receptors and suggest that the clinical applications of LY2828360 as an anti-hyperalgesic agent should be re-evaluated.
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Affiliation(s)
- Kelsey G Guenther
- Program in Neuroscience, Indiana University, Bloomington, IN, USA; Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA
| | - Zhili Xu
- Program in Neuroscience, Indiana University, Bloomington, IN, USA; Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA
| | - Julian Romero
- Faculty of Experimental Sciences, Universidad Francisco de Vitoria, Madrid, Spain
| | - Cecilia J Hillard
- Department of Pharmacology and Toxicology, Med. Col. of Wisconsin, Milwaukee, WI, USA
| | - Ken Mackie
- Program in Neuroscience, Indiana University, Bloomington, IN, USA; Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA; Gill Center for Biomolecular Science, Indiana University, Bloomington, IN, USA
| | - Andrea G Hohmann
- Program in Neuroscience, Indiana University, Bloomington, IN, USA; Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA; Gill Center for Biomolecular Science, Indiana University, Bloomington, IN, USA.
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Rathod SS, Agrawal YO, Nakhate KT, Meeran MFN, Ojha S, Goyal SN. Neuroinflammation in the Central Nervous System: Exploring the Evolving Influence of Endocannabinoid System. Biomedicines 2023; 11:2642. [PMID: 37893016 PMCID: PMC10604915 DOI: 10.3390/biomedicines11102642] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 09/20/2023] [Accepted: 09/21/2023] [Indexed: 10/29/2023] Open
Abstract
Neuroinflammation is a complex biological process that typically originates as a protective response in the brain. This inflammatory process is triggered by the release of pro-inflammatory substances like cytokines, prostaglandins, and reactive oxygen and nitrogen species from stimulated endothelial and glial cells, including those with pro-inflammatory functions, in the outer regions. While neuronal inflammation is common in various central nervous system disorders, the specific inflammatory pathways linked with different immune-mediated cell types and the various factors influencing the blood-brain barrier significantly contribute to disease-specific characteristics. The endocannabinoid system consists of cannabinoid receptors, endogenous cannabinoids, and enzymes responsible for synthesizing and metabolizing endocannabinoids. The primary cannabinoid receptor is CB1, predominantly found in specific brain regions such as the brainstem, cerebellum, hippocampus, and cortex. The presence of CB2 receptors in certain brain components, like cultured cerebellar granular cells, Purkinje fibers, and microglia, as well as in the areas like the cerebral cortex, hippocampus, and cerebellum is also evidenced by immunoblotting assays, radioligand binding, and autoradiography studies. Both CB1 and CB2 cannabinoid receptors exhibit noteworthy physiological responses and possess diverse neuromodulatory capabilities. This review primarily aims to outline the distribution of CB1 and CB2 receptors across different brain regions and explore their potential roles in regulating neuroinflammatory processes.
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Affiliation(s)
- Sumit S. Rathod
- Shri Vile Parle Kelavani Mandal’s Institute of Pharmacy, Dhule 424001, Maharashtra, India; (S.S.R.); (Y.O.A.); (K.T.N.)
- Department of Pharmacy, R. C. Patel Institute of Pharmaceutical Education and Research, Shirpur 425405, Maharashtra, India
| | - Yogeeta O. Agrawal
- Shri Vile Parle Kelavani Mandal’s Institute of Pharmacy, Dhule 424001, Maharashtra, India; (S.S.R.); (Y.O.A.); (K.T.N.)
| | - Kartik T. Nakhate
- Shri Vile Parle Kelavani Mandal’s Institute of Pharmacy, Dhule 424001, Maharashtra, India; (S.S.R.); (Y.O.A.); (K.T.N.)
| | - M. F. Nagoor Meeran
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, Abu Dhabi P.O. Box 15551, United Arab Emirates;
| | - Shreesh Ojha
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, Abu Dhabi P.O. Box 15551, United Arab Emirates;
| | - Sameer N. Goyal
- Shri Vile Parle Kelavani Mandal’s Institute of Pharmacy, Dhule 424001, Maharashtra, India; (S.S.R.); (Y.O.A.); (K.T.N.)
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Mabou Tagne A, Fotio Y, Uppal PS, Piomelli D. Synergistic antinociceptive effects of concomitant NAAA and peripheral FAAH inhibition. Exp Neurol 2022; 357:114194. [PMID: 35932800 DOI: 10.1016/j.expneurol.2022.114194] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/25/2022] [Accepted: 07/30/2022] [Indexed: 11/19/2022]
Abstract
The intracellular lipid amidases, fatty acid amide hydrolase (FAAH) and N-acylethanolamine acid amidase (NAAA), terminate the actions of anandamide and palmitoylethanolamide (PEA), two antinociceptive and anti-inflammatory lipid-derived mediators. Here we show, confirming prior research, that small-molecule inhibitors of peripheral FAAH (compound URB937) and systemic NAAA (compound ARN19702) individually attenuate, in male CD-1 mice, pain-related behaviors and paw inflammation in the formalin and carrageenan tests. More importantly, isobolographic analyses revealed that the combination of URB937 and ARN19702 produced substantial synergistic (greater than additive) antinociceptive effects in both models as well as additive anti-inflammatory effects in the carrageenan test. Together, the findings uncover a functional interplay between FAAH and NAAA substrates in the control of nociception, which might be exploited clinically to develop safe and effective pain management strategies.
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Affiliation(s)
- Alex Mabou Tagne
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697-4625, USA.
| | - Yannick Fotio
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697-4625, USA
| | - Parwinder Singh Uppal
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697-4625, USA
| | - Daniele Piomelli
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697-4625, USA; Department of Biological Chemistry, University of California, Irvine, CA 92697-4625, USA; Department of Pharmaceutical Sciences, University of California Irvine, CA 92697-4625, USA.
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Kupczyk P, Rykala M, Serek P, Pawlak A, Slowikowski B, Holysz M, Chodaczek G, Madej JP, Ziolkowski P, Niedzwiedz A. The cannabinoid receptors system in horses: Tissue distribution and cellular identification in skin. J Vet Intern Med 2022; 36:1508-1524. [PMID: 35801813 PMCID: PMC9308437 DOI: 10.1111/jvim.16467] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 05/27/2022] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND The endocannabinoid system (ECS) is composed of cannabinoid receptors type 1 (CBR1) and type 2 (CBR2), cannabinoid-based ligands (endogenous chemically synthesized phytocannabinoids), and endogenous enzymes controlling their concentrations. Cannabinoid receptors (CBRs) have been identified in invertebrates and in almost all vertebrate species in the central and peripheral nervous system as well as in immune cells, where they control neuroimmune homeostasis. In humans, rodents, dogs, and cats, CBRs expression has been confirmed in the skin, and their expression and tissue distribution become disordered in pathological conditions. Cannabinoid receptors may be a possible therapeutic target in skin diseases. OBJECTIVES To characterize the distribution and cellular expression of CBRs in the skin of horses under normal conditions. ANIMALS Fifteen healthy horses. METHODS Using full-thickness skin punch biopsy samples, skin-derived primary epidermal keratinocytes and dermal-derived cells, we performed analysis of Cnr1 and Cnr2 genes using real-time PCR and CBR1 and CBR2 protein expression by confocal microscopy and Western blotting. RESULTS Normal equine skin, including equine epidermal keratinocytes and dermal fibroblast-like cells, all exhibited constant gene and protein expression of CBRs. CONCLUSIONS AND CLINICAL IMPORTANCE Our results represent a starting point for developing and translating new veterinary medicine-based pharmacotherapies using ECS as a possible target.
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Affiliation(s)
- Piotr Kupczyk
- Division of General and Experimental Pathology, Department of Clinical and Experimental Pathology, Faculty of Medicine, Wroclaw Medical University, Wroclaw, Poland
| | - Marta Rykala
- Department of Internal Medicine and Clinic for Horses, Dogs and Cats, Faculty of Veterinary Medicine, University of Environmental and Life Sciences, Wroclaw, Poland
| | - Pawel Serek
- Department of Biochemistry and Immunochemistry, Faculty of Medicine, Wroclaw Medical University, Wroclaw, Poland
| | - Aleksandra Pawlak
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Environmental and Life Sciences, Wroclaw, Poland
| | - Bartosz Slowikowski
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Karol Marcinkowski Poznan University of Medical Sciences, Poznan, Poland
| | - Marcin Holysz
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Karol Marcinkowski Poznan University of Medical Sciences, Poznan, Poland
| | - Grzegorz Chodaczek
- Bioimaging Laboratory, Lukasiewicz Research Network - PORT Polish Center for Technology Development, Wroclaw, Poland
| | - Jan P Madej
- Department of Immunology, Pathophysiology and Veterinary Preventive Medicine, Faculty of Veterinary Medicine, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - Piotr Ziolkowski
- Division of General and Experimental Pathology, Department of Clinical and Experimental Pathology, Faculty of Medicine, Wroclaw Medical University, Wroclaw, Poland
| | - Artur Niedzwiedz
- Department of Internal Medicine and Clinic for Horses, Dogs and Cats, Faculty of Veterinary Medicine, University of Environmental and Life Sciences, Wroclaw, Poland
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Ortiz YT, McMahon LR, Wilkerson JL. Medicinal Cannabis and Central Nervous System Disorders. Front Pharmacol 2022; 13:881810. [PMID: 35529444 PMCID: PMC9070567 DOI: 10.3389/fphar.2022.881810] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 04/05/2022] [Indexed: 01/02/2023] Open
Abstract
Cannabinoids, including those found in cannabis, have shown promise as potential therapeutics for numerous health issues, including pathological pain and diseases that produce an impact on neurological processing and function. Thus, cannabis use for medicinal purposes has become accepted by a growing majority. However, clinical trials yielding satisfactory endpoints and unequivocal proof that medicinal cannabis should be considered a frontline therapeutic for most examined central nervous system indications remains largely elusive. Although cannabis contains over 100 + compounds, most preclinical and clinical research with well-controlled dosing and delivery methods utilize the various formulations of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), the two most abundant compounds in cannabis. These controlled dosing and delivery methods are in stark contrast to most clinical studies using whole plant cannabis products, as few clinical studies using whole plant cannabis profile the exact composition, including percentages of all compounds present within the studied product. This review will examine both preclinical and clinical evidence that supports or refutes the therapeutic utility of medicinal cannabis for the treatment of pathological pain, neurodegeneration, substance use disorders, as well as anxiety-related disorders. We will predominately focus on purified THC and CBD, as well as other compounds isolated from cannabis for the aforementioned reasons but will also include discussion over those studies where whole plant cannabis has been used. In this review we also consider the current challenges associated with the advancement of medicinal cannabis and its derived potential therapeutics into clinical applications.
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Affiliation(s)
- Yuma T. Ortiz
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, United States
| | - Lance R. McMahon
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, United States
| | - Jenny L. Wilkerson
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, United States
- *Correspondence: Jenny L. Wilkerson,
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Abstract
Cannabinoids, including those found in cannabis, have shown promise as potential therapeutics for numerous health issues, including pathological pain and diseases that produce an impact on neurological processing and function. Thus, cannabis use for medicinal purposes has become accepted by a growing majority. However, clinical trials yielding satisfactory endpoints and unequivocal proof that medicinal cannabis should be considered a frontline therapeutic for most examined central nervous system indications remains largely elusive. Although cannabis contains over 100 + compounds, most preclinical and clinical research with well-controlled dosing and delivery methods utilize the various formulations of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), the two most abundant compounds in cannabis. These controlled dosing and delivery methods are in stark contrast to most clinical studies using whole plant cannabis products, as few clinical studies using whole plant cannabis profile the exact composition, including percentages of all compounds present within the studied product. This review will examine both preclinical and clinical evidence that supports or refutes the therapeutic utility of medicinal cannabis for the treatment of pathological pain, neurodegeneration, substance use disorders, as well as anxiety-related disorders. We will predominately focus on purified THC and CBD, as well as other compounds isolated from cannabis for the aforementioned reasons but will also include discussion over those studies where whole plant cannabis has been used. In this review we also consider the current challenges associated with the advancement of medicinal cannabis and its derived potential therapeutics into clinical applications.
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Raux PL, Drutel G, Revest JM, Vallée M. New perspectives on the role of the neurosteroid pregnenolone as an endogenous regulator of type-1 cannabinoid receptor (CB1R) activity and function. J Neuroendocrinol 2022; 34:e13034. [PMID: 34486765 DOI: 10.1111/jne.13034] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 08/06/2021] [Accepted: 08/06/2021] [Indexed: 12/14/2022]
Abstract
Pregnenolone is a steroid with specific characteristics, being the first steroid to be synthesised from cholesterol at all sites of steroidogenesis, including the brain. For many years, pregnenolone was defined as an inactive precursor of all steroids because no specific target had been discovered. However, over the last decade, it has become a steroid of interest because it has been recognised as being a biomarker for brain-related disorders through the development of metabolomic approaches and advanced analytical methods. In addition, physiological roles for pregnenolone emerged when specific targets were discovered. In this review, we highlight the discovery of the selective interaction of pregnenolone with the type-1 cannabinoid receptor (CB1R). After describing the specific characteristic of CB1Rs, we discuss the newly discovered mechanisms of their regulation by pregnenolone. In particular, we describe the action of pregnenolone as a negative allosteric modulator and a specific signalling inhibitor of the CB1R. These particular characteristics of pregnenolone provide a great strategic opportunity for therapeutic development in CB1-related disorders. Finally, we outline new perspectives using innovative genetic tools for the discovery of original regulatory mechanisms of pregnenolone on CB1-related functions.
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Affiliation(s)
- Pierre-Louis Raux
- INSERM U1215, Neurocentre Magendie, Group "Physiopathology and Therapeutic Approaches of Stress-Related Disease", Bordeaux, France
- University of Bordeaux, Bordeaux, France
| | - Guillaume Drutel
- INSERM U1215, Neurocentre Magendie, Group "Physiopathology and Therapeutic Approaches of Stress-Related Disease", Bordeaux, France
- University of Bordeaux, Bordeaux, France
| | - Jean-Michel Revest
- INSERM U1215, Neurocentre Magendie, Group "Physiopathology and Therapeutic Approaches of Stress-Related Disease", Bordeaux, France
- University of Bordeaux, Bordeaux, France
| | - Monique Vallée
- INSERM U1215, Neurocentre Magendie, Group "Physiopathology and Therapeutic Approaches of Stress-Related Disease", Bordeaux, France
- University of Bordeaux, Bordeaux, France
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Curcumin induces peripheral antinociception by opioidergic and cannabinoidergic mechanism: Pharmacological evidence. Life Sci 2022; 293:120279. [PMID: 35032552 DOI: 10.1016/j.lfs.2021.120279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 12/17/2021] [Accepted: 12/26/2021] [Indexed: 11/23/2022]
Abstract
BACKGROUND Curcumin is one of the compounds present in plants of the genus Curcuma sp., being very used not only as condiment but also with medicinal purposes. As an analgesic, papers highlight the efficacy of curcumin in the treatment of various types of pain. AIMS In this study we evaluated the peripheral antinociceptive effect of curcumin and by which mechanisms this effect is induced. MAIN METHODS The mice paw pressure test was used on animals which had increased pain sensitivity by intraplantar injection of carrageenan. All the drugs were administered in the right hind paw. KEY FINDINGS Curcumin was administered to the right hind paw animals induced antinociceptive effect. Non -selective antagonist of opioid receptors naloxone reverted the antinociceptive effect induced by curcumin. Selective antagonists for μ, δ and κ opioid receptors clocinnamox, naltrindole and nor- binaltorphimine, respectively, reverted the antinociceptive effect induced by curcumin. Bestatin, enkephalinases inhibitor that degrade peptides opioids, did not change the nociceptive response. Selective antagonists for CB1 and CB2 cannabinoid receptors, AM251 and AM630, respectively, reversed the antinociceptive effect induced by curcumin. The MAFP inhibitor of the enzyme FAAH which breaks down anandamide, JZL184, enzyme inhibitor MAGL which breaks down the 2-AG, as well as the VDM11 anandamide reuptake inhibitor potentiated the antinociceptive effect of curcumin. SIGNIFICANCE These results suggest that curcumin possibly peripheral antinociception induced by opioid and cannabinoid systems activation and possibly for endocannabinoids and opioids release.
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Finn DP, Haroutounian S, Hohmann AG, Krane E, Soliman N, Rice ASC. Cannabinoids, the endocannabinoid system, and pain: a review of preclinical studies. Pain 2021; 162:S5-S25. [PMID: 33729211 PMCID: PMC8819673 DOI: 10.1097/j.pain.0000000000002268] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 03/10/2021] [Indexed: 12/13/2022]
Abstract
ABSTRACT This narrative review represents an output from the International Association for the Study of Pain's global task force on the use of cannabis, cannabinoids, and cannabis-based medicines for pain management, informed by our companion systematic review and meta-analysis of preclinical studies in this area. Our aims in this review are (1) to describe the value of studying cannabinoids and endogenous cannabinoid (endocannabinoid) system modulators in preclinical/animal models of pain; (2) to discuss both pain-related efficacy and additional pain-relevant effects (adverse and beneficial) of cannabinoids and endocannabinoid system modulators as they pertain to animal models of pathological or injury-related persistent pain; and (3) to identify important directions for future research. In service of these goals, this review (1) provides an overview of the endocannabinoid system and the pharmacology of cannabinoids and endocannabinoid system modulators, with specific relevance to animal models of pathological or injury-related persistent pain; (2) describes pharmacokinetics of cannabinoids in rodents and humans; and (3) highlights differences and discrepancies between preclinical and clinical studies in this area. Preclinical (rodent) models have advanced our understanding of the underlying sites and mechanisms of action of cannabinoids and the endocannabinoid system in suppressing nociceptive signaling and behaviors. We conclude that substantial evidence from animal models supports the contention that cannabinoids and endocannabinoid system modulators hold considerable promise for analgesic drug development, although the challenge of translating this knowledge into clinically useful medicines is not to be underestimated.
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Affiliation(s)
- David P Finn
- Pharmacology and Therapeutics, School of Medicine, Galway Neuroscience Centre and Centre for Pain Research, Human Biology Building, National University of Ireland Galway, University Road, Galway, Ireland
| | - Simon Haroutounian
- Department of Anesthesiology and Washington University Pain Center, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Andrea G Hohmann
- Psychological and Brain Sciences, Program in Neuroscience, and Gill Center for Biomolecular Science, Indiana University, Bloomington, IN, USA
| | - Elliot Krane
- Departments of Anesthesiology, Perioperative, and Pain Medicine, & Pediatrics, Stanford University School of Medicine, Stanford, California, USA
| | - Nadia Soliman
- Pain Research, Department of Surgery & Cancer, Faculty of Medicine, Imperial College London, UK
| | - Andrew SC Rice
- Pain Research, Department of Surgery & Cancer, Faculty of Medicine, Imperial College London, UK
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Wilkerson JL, Bilbrey JA, Felix JS, Makriyannis A, McMahon LR. Untapped endocannabinoid pharmacological targets: Pipe dream or pipeline? Pharmacol Biochem Behav 2021; 206:173192. [PMID: 33932409 DOI: 10.1016/j.pbb.2021.173192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 04/18/2021] [Accepted: 04/21/2021] [Indexed: 10/21/2022]
Abstract
It has been established that the endogenous cannabinoid (endocannabinoid) system plays key modulatory roles in a wide variety of pathological conditions. The endocannabinoid system comprises both cannabinoid receptors, their endogenous ligands including 2-arachidonoylglycerol (2-AG), N-arachidonylethanolamine (anandamide, AEA), and enzymes that regulate the synthesis and degradation of endogenous ligands which include diacylglycerol lipase alpha (DAGL-α), diacylglycerol lipase beta (DAGL-β), fatty acid amide hydrolase (FAAH), monoacylglycerol lipase (MAGL), α/β hydrolase domain 6 (ABHD6). As the endocannabinoid system exerts considerable involvement in the regulation of homeostasis and disease, much effort has been made towards understanding endocannabinoid-related mechanisms of action at cellular, physiological, and pathological levels as well as harnessing the various components of the endocannabinoid system to produce novel therapeutics. However, drug discovery efforts within the cannabinoid field have been slower than anticipated to reach satisfactory clinical endpoints and raises an important question into the validity of developing novel ligands that therapeutically target the endocannabinoid system. To answer this, we will first examine evidence that supports the existence of an endocannabinoid system role within inflammatory diseases, neurodegeneration, pain, substance use disorders, mood disorders, as well as metabolic diseases. Next, this review will discuss recent clinical studies, within the last 5 years, of cannabinoid compounds in context to these diseases. We will also address some of the challenges and considerations within the cannabinoid field that may be important in the advancement of therapeutics into the clinic.
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Affiliation(s)
- Jenny L Wilkerson
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, USA.
| | - Joshua A Bilbrey
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, USA
| | - Jasmine S Felix
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, USA
| | - Alexandros Makriyannis
- Center for Drug Discovery and Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA; Departments of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA
| | - Lance R McMahon
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, USA.
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Komorowska-Müller JA, Schmöle AC. CB2 Receptor in Microglia: The Guardian of Self-Control. Int J Mol Sci 2020; 22:E19. [PMID: 33375006 PMCID: PMC7792761 DOI: 10.3390/ijms22010019] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/16/2020] [Accepted: 12/18/2020] [Indexed: 12/12/2022] Open
Abstract
Microglia are key to maintaining the homeostasis of the brain. These immune cells of the brain can be our biggest ally in fighting infections, but can worsen pathology or hinder recovery when uncontrolled. Thus, understanding how microglia contribute to neuroinflammatory processes and how their activity can be controlled is of great importance. It is known that activation of endocannabinoid system, and especially the cannabinoid type 2 receptor (CB2R), decreases inflammation. Alongside its non-psychoactive effect, it makes the CB2R receptor a perfect target for treating diseases accompanied by neuroinflammation including neurodegenerative diseases. However, the exact mechanisms by which CB2R regulates microglial activity are not yet understood. Here, we review the current knowledge on the roles of microglial CB2R from in vitro and in vivo studies. We look into CB2R function under physiological and pathological conditions and focus on four different disease models representing chronic and acute inflammation. We highlight open questions and controversies and provide an update on the latest discoveries that were enabled by the development of novel technologies. Also, we discuss the recent findings on the role of microglia CB2R in cognition and its role in neuron-microglia communication.
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Affiliation(s)
- Joanna Agnieszka Komorowska-Müller
- Institute for Molecular Psychiatry, Medical Faculty, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany;
- International Max Planck Research School for Brain and Behavior, University of Bonn, 53175 Bonn, Germany
| | - Anne-Caroline Schmöle
- Institute for Molecular Psychiatry, Medical Faculty, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany;
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Haspula D, Clark MA. Cannabinoid Receptors: An Update on Cell Signaling, Pathophysiological Roles and Therapeutic Opportunities in Neurological, Cardiovascular, and Inflammatory Diseases. Int J Mol Sci 2020; 21:E7693. [PMID: 33080916 PMCID: PMC7590033 DOI: 10.3390/ijms21207693] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/16/2022] Open
Abstract
The identification of the human cannabinoid receptors and their roles in health and disease, has been one of the most significant biochemical and pharmacological advancements to have occurred in the past few decades. In spite of the major strides made in furthering endocannabinoid research, therapeutic exploitation of the endocannabinoid system has often been a challenging task. An impaired endocannabinoid tone often manifests as changes in expression and/or functions of type 1 and/or type 2 cannabinoid receptors. It becomes important to understand how alterations in cannabinoid receptor cellular signaling can lead to disruptions in major physiological and biological functions, as they are often associated with the pathogenesis of several neurological, cardiovascular, metabolic, and inflammatory diseases. This review focusses mostly on the pathophysiological roles of type 1 and type 2 cannabinoid receptors, and it attempts to integrate both cellular and physiological functions of the cannabinoid receptors. Apart from an updated review of pre-clinical and clinical studies, the adequacy/inadequacy of cannabinoid-based therapeutics in various pathological conditions is also highlighted. Finally, alternative strategies to modulate endocannabinoid tone, and future directions are also emphasized.
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Affiliation(s)
- Dhanush Haspula
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA;
| | - Michelle A. Clark
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33314, USA
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Quiñonez‐Bastidas GN, Palomino‐Hernández O, López‐Ortíz M, Rocha‐González HI, González‐Anduaga GM, Regla I, Navarrete A. Antiallodynic effect of PhAR-DBH-Me involves cannabinoid and TRPV1 receptors. Pharmacol Res Perspect 2020; 8:e00663. [PMID: 32965798 PMCID: PMC7510332 DOI: 10.1002/prp2.663] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 08/20/2020] [Accepted: 08/21/2020] [Indexed: 12/29/2022] Open
Abstract
The antiallodynic effect of PhAR-DBH-Me was evaluated on two models of neuropathic pain, and the potential roles of CB1, CB2, and TRPV1 receptors as molecular targets of PhAR-DBH-Me were studied. Female Wistar rats were submitted to L5/L6 spinal nerve ligation (SNL) or repeated doses of cisplatin (0.1 mg/kg, i.p.) to induce experimental neuropathy. Then, tactile allodynia was determined, and animals were treated with logarithmic doses of PhAR-DBH-Me (3.2-100 mg/kg, i.p.). To evaluate the mechanism of action of PhAR-DBH-Me, in silico studies using crystallized structures of CB1, CB2, and TRPV1 receptors were performed. To corroborate the computational insights, animals were intraperitoneally administrated with antagonists for CB1 (AM-251, 3 mg/kg), CB2 (AM-630, 1 mg/kg), and TRPV1 receptors (capsazepine, 3 mg/kg), 15 min before to PhAR-DBH-Me (100 mg/kg) administration. Vagal stimulation evoked on striated muscle contraction in esophagus, was used to elicited pharmacological response of PhAR-DBH-ME on nervous tissue. Systemic administration of PhAR-DBH-Me reduced the SNL- and cisplatin-induced allodynia. Docking studies suggested that PhAR-DBH-Me acts as an agonist for CB1, CB2, and TRPV1 receptors, with similar affinity to the endogenous ligand anandamide. Moreover antiallodynic effect of PhAR-DBH-Me was partially prevented by administration of AM-251 and AM-630, and completely prevented by capsazepine. Finally, PhAR-DBH-Me decreased the vagally evoked electrical response in esophagus rat. Taken together, results indicate that PhAR-DBH-Me induces an antiallodynic effect through partial activation of CB1 and CB2 receptors, as well as desensitization of TRPV1 receptors. Data also shed light on the novel vanilloid nature of the synthetic compound PhAR-DBH-Me.
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Affiliation(s)
| | - Oscar Palomino‐Hernández
- Computational Biomedicine ‐ Institute for Advanced Simulation (IAS‐5) and Institute of Neuroscience and Medicine (INM‐9)Forschungszentrum JülichJülichGermany
- Department of ChemistryRheinisch‐Westfälische Technische Hochschule AachenAachenGermany
| | - Manuel López‐Ortíz
- Facultad de Estudios Superiores ZaragozaUniversidad Nacional Autónoma de México (UNAM)MéxicoDFMéxico
| | - Héctor Isaac Rocha‐González
- Sección de Estudios de Posgrado e InvestigaciónEscuela Superior de MedicinaInstituto Politécnico NacionalMéxicoCiudad de MéxicoMéxico
| | - Gloria Melisa González‐Anduaga
- Facultad de QuímicaDepartamento de FarmaciaUniversidad Nacional Autónoma de MéxicoCiudad UniversitariaCoyoacánCiudad de MéxicoMéxico
| | - Ignacio Regla
- Facultad de Estudios Superiores ZaragozaUniversidad Nacional Autónoma de México (UNAM)MéxicoDFMéxico
| | - Andrés Navarrete
- Facultad de QuímicaDepartamento de FarmaciaUniversidad Nacional Autónoma de MéxicoCiudad UniversitariaCoyoacánCiudad de MéxicoMéxico
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PnAn13, an antinociceptive synthetic peptide inspired in the Phoneutria nigriventer toxin PnTx4(6-1) (δ-Ctenitoxin-Pn1a). Toxicon X 2020; 7:100045. [PMID: 32875290 PMCID: PMC7452081 DOI: 10.1016/j.toxcx.2020.100045] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 05/24/2020] [Accepted: 05/29/2020] [Indexed: 11/22/2022] Open
Abstract
Animal venoms are an almost inexhaustible source for promising molecules with biological activity and the venom of Phoneutria nigriventer spider is a good example of this. Among several other toxins obtained from this venom, PnTx4(6–1), also called δ-Ctenitoxin-Pn1a, was isolated and initially described as an insect toxin that binds to the site 3 of sodium channels in cockroach nerve cord synaptosomes (Periplaneta americana) and slows down sodium current inactivation in isolated axons of this animal. This toxin did not cause any apparent toxicity to mice when intracerebroventricularly injected (30 μg). Subsequently, it was demonstrated that PnTx4(6–1) has an antinociceptive effect in three different pain models: inflammatory, induced by carrageenan; nociceptive, induced by prostaglandin E2 and neuropathic, induced by sciatic nerve constriction. Using diverse antagonists from receptors, it was shown that the cannabinoid system, via the CB1 receptor, and the opioid system, through the μ and δ receptors, are both involved in the antinociceptive effect of PnTx4(6–1). In the present work, it was synthesized a peptide, named PnAn13, based on the amino acid sequence of PnTx4(6–1) in order to try to reproduce or increase the analgesic effect of the toxin. As it was seen for the toxin, PnAn13 had antinociceptive activity, when intrathecally injected, and this effect involved the cannabinoid and opioid systems. In addition, when it was evaluated the peripheral effect of PnAn13, via intraplantar administration, this peptide was able to reverse the hyperalgesic threshold, evoked by prostaglandin E2. Therefore, using different pharmacological tools, it was shown the participation of cannabinoid and opioid systems in this effect. A synthetic peptide PnAn13, reproduced the antinociceptive effects of the PnTx4(6-1) (δ-Ctenitoxin-Pn1a) toxin. PnAn13 showed a clear analgesic effect in the nociceptive in vivo rat pain model, both centrally and peripherally. The antinociceptive effect of PnAn13 involves cannabinoid and opioid systems.
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Slivicki RA, Iyer V, Mali SS, Garai S, Thakur GA, Crystal JD, Hohmann AG. Positive Allosteric Modulation of CB 1 Cannabinoid Receptor Signaling Enhances Morphine Antinociception and Attenuates Morphine Tolerance Without Enhancing Morphine- Induced Dependence or Reward. Front Mol Neurosci 2020; 13:54. [PMID: 32410959 PMCID: PMC7199816 DOI: 10.3389/fnmol.2020.00054] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Accepted: 03/17/2020] [Indexed: 01/09/2023] Open
Abstract
Opioid analgesics represent a critical treatment for chronic pain in the analgesic ladder of the World Health Organization. However, their use can result in a number of unwanted side-effects including incomplete efficacy, constipation, physical dependence, and overdose liability. Cannabinoids enhance the pain-relieving effects of opioids in preclinical studies and dampen unwanted side-effects resulting from excessive opioid intake. We recently reported that a CB1 positive allosteric modulator (PAM) exhibits antinociceptive efficacy in models of pathological pain and lacks the adverse side effects of direct CB1 receptor activation. In the present study, we evaluated whether a CB1 PAM would enhance morphine’s therapeutic efficacy in an animal model of chemotherapy-induced neuropathic pain and characterized its impact on unwanted side-effects associated with chronic opioid administration. In paclitaxel-treated mice, both the CB1 PAM GAT211 and the opioid analgesic morphine reduced paclitaxel-induced behavioral hypersensitivities to mechanical and cold stimulation in a dose-dependent manner. Isobolographic analysis revealed that combinations of GAT211 and morphine resulted in anti-allodynic synergism. In paclitaxel-treated mice, a sub-threshold dose of GAT211 prevented the development of tolerance to the anti-allodynic effects of morphine over 20 days of once daily dosing. However, GAT211 did not reliably alter somatic withdrawal signs (i.e., jumps, paw tremors) in morphine-dependent neuropathic mice challenged with naloxone. In otherwise naïve mice, GAT211 also prolonged antinociceptive efficacy of morphine in the tail-flick test and reduced the overall right-ward shift in the ED50 for morphine to produce antinociception in the tail-flick test, consistent with attenuation of morphine tolerance. Pretreatment with GAT211 did not alter somatic signs of μ opioid receptor dependence in mice rendered dependent upon morphine via subcutaneous implantation of a morphine pellet. Moreover, GAT211 did not reliably alter μ-opioid receptor-mediated reward as measured by conditioned place preference to morphine. Our results suggest that a CB1 PAM may be beneficial in enhancing and prolonging the therapeutic properties of opioids while potentially sparing unwanted side-effects (e.g., tolerance) that occur with repeated opioid treatment.
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Affiliation(s)
- Richard A Slivicki
- Program in Neuroscience, Indiana University, Bloomington, IN, United States.,Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Vishakh Iyer
- Program in Neuroscience, Indiana University, Bloomington, IN, United States.,Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Sonali S Mali
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Sumanta Garai
- Center for Drug Discovery, Bouve College of Health Sciences, Northeastern University, Boston, MA, United States
| | - Ganesh A Thakur
- Center for Drug Discovery, Bouve College of Health Sciences, Northeastern University, Boston, MA, United States
| | - Jonathon D Crystal
- Program in Neuroscience, Indiana University, Bloomington, IN, United States.,Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Andrea G Hohmann
- Program in Neuroscience, Indiana University, Bloomington, IN, United States.,Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States.,Gill Center for Biomolecular Science, Indiana University, Bloomington, IN, United States
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Milligan AL, Szabo-Pardi TA, Burton MD. Cannabinoid Receptor Type 1 and Its Role as an Analgesic: An Opioid Alternative? J Dual Diagn 2020; 16:106-119. [PMID: 31596190 PMCID: PMC7007359 DOI: 10.1080/15504263.2019.1668100] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Understanding how the body regulates pain is fundamental to develop rational strategies to combat the growing prevalence of chronic pain states, opioid dependency, and the increased financial burden to the medical care system. Pain is the most prominent reason why Americans seek medical attention and extensive literature has identified the importance of the endocannabinoid pathway in controlling pain. Modulation of the endocannabinoid system offers new therapeutic opportunities for the selective control of excessive neuronal activity in several pain conditions (acute, inflammatory, chronic, and neuropathic). Cannabinoids have a long history of medicinal use and their analgesic properties are well documented; however, there are major impediments to understanding cannabinoid pain modulation. One major issue is the presence of psychotropic side effects associated with D9-tetrahydrocannabinol (THC) or synthetic derivatives, which puts an emphatic brake on their use. This dose-limiting effect prevents the appropriate degree of analgesia . Animal studies have shown that the psychotropic effects are mediated via brain cannabinoid type 1 (CB1) receptors, while analgesic activity in chronic pain states may be mediated via CB1R action in the spinal cord, brainstem, peripheral sensory neurons, or immune cells. The development of appropriate therapies is incumbent on our understanding of the role of peripheral versus central endocannabinoid-driven analgesia. Recent physiological, pharmacological, and anatomical studies provide evidence that one of the main roles of the endocannabinoid system is the regulation of gamma-aminobutyric acid (GABA) and/or glutamate release. This article will review this evidence in the context of its implications for pain. We first provide a brief overview of CB1R's role in the regulation of nociception, followed by a review of the evidence that the peripheral endocannabinoid system modulates nociception. We then look in detail at regulation of central-mediated analgesia, followed up with evidence that cannabinoidmediated modulation of pain involves modulation of GABAergic and glutamatergic neurotransmission in key brain regions. Finally, we discuss cannabinoid action on non-neuronal cells in the context of inflammation and direct modulation of neurons. This work stands to reveal long-standing controversies in the cannabinoid analgesia area that have had an impact on failed clinical trials and implementation of therapeutics targeting this system.
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Kopruszinski CM, Navratilova E, Vagnerova B, Swiokla J, Patwardhan A, Dodick D, Porreca F. Cannabinoids induce latent sensitization in a preclinical model of medication overuse headache. Cephalalgia 2019; 40:68-78. [PMID: 31311288 DOI: 10.1177/0333102419865252] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
AIM Evaluation of cannabinoid receptor agonists in a preclinical model of medication overuse headache. METHODS Female Sprague Dawley rats received graded intraperitoneal doses of WIN55,212-2 or Δ-9-tetrahydrocannabinol (Δ-9-THC). Antinociception (tail-flick test), catalepsy and hypomotility (open field test) and impairment of motor function (rotarod test) were assessed to establish effective dosing. Rats were then treated twice daily with equianalgesic doses of WIN55,212-2 or Δ-9-THC, or vehicle, for 7 days and cutaneous tactile sensory thresholds were evaluated during and three weeks following drug discontinuation. Rats then received a one-hour period of bright light stress (BLS) on two consecutive days and tactile sensory thresholds were re-assessed. RESULTS WIN55,212-2 and Δ-9-THC produced antinociception as well as hypomotility, catalepsy and motor impairment. Repeated administration of WIN55,212-2 and Δ-9-THC induced generalized periorbital and hindpaw allodynia that resolved within 3 weeks after discontinuation of drug. Two episodes of BLS produced delayed and long-lasting periorbital and hindpaw allodynia selectively in rats previously treated with WIN55,212-2, and Δ-9-THC. INTERPRETATION Cannabinoid receptor agonists including Δ-9-THC produce a state of latent sensitization characterized by increased sensitivity to stress, a presumed migraine trigger. Overuse of cannabinoids including cannabis may increase the risk of medication overuse headache in vulnerable individuals.
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Affiliation(s)
| | - Edita Navratilova
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA
| | - Barbora Vagnerova
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA
| | - Juliana Swiokla
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA
| | - Amol Patwardhan
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA
| | - David Dodick
- Department of Neurology, Mayo Clinic, Phoenix, AZ, USA
| | - Frank Porreca
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA.,Department of Neurology, Mayo Clinic, Phoenix, AZ, USA
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Li Y, Zhang L, Wu Y, Zheng Q, Chen M, Qian Z, Wei C, Han J, Liu Z, Ren W, Liu Y. Cannabinoids-induced peripheral analgesia depends on activation of BK channels. Brain Res 2019; 1711:23-28. [PMID: 30615887 DOI: 10.1016/j.brainres.2019.01.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 12/11/2018] [Accepted: 01/03/2019] [Indexed: 12/14/2022]
Abstract
The endogenous cannabinoid system is involved in the physiological inhibitory control of pain and is of particular interest for the development of therapeutic approaches for pain management. Selective activation of the peripheral CB1 cannabinoid receptor has been shown to suppress the heightened firing of primary afferents, which is the peripheral mechanism underlying neuropathic pain after nerve injury. However, the mechanism underlying this effect of CB1 receptor remains unclear. The large-conductance calcium-activated potassium (BK) channels have been reported to participate in anticonvulsant and vasorelaxant effects of cannabinoids. We asked whether BK channels participate in cannabinoids-induced analgesia and firing-suppressing effects in primary afferents after nerve injury. Here, using mice with chronic constriction injury (CCI)-induced neuropathic pain, antinociception action and firing-suppressing effect of HU210 were measured before and after BK channel blocker application. We found that local peripheral application of HU210 alleviated CCI-induced pain behavior and suppressed the heightened firing of injured fibers. Co-administration of IBTX with HU210 significantly reversed the analgesia and the firing-suppressing effect of HU210. This result indicated that the peripheral analgesic effects of cannabinoids depends on activation of BK channels.
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Affiliation(s)
- Yongfeng Li
- MOE Key Laboratory of Modern Teaching Technology, Center for Teacher Professional Ability Development, Shaanxi Normal University, 199 South Chang'an Road, Xi'an 710062, China
| | - Leili Zhang
- MOE Key Laboratory of Modern Teaching Technology, Center for Teacher Professional Ability Development, Shaanxi Normal University, 199 South Chang'an Road, Xi'an 710062, China
| | - Yuwei Wu
- MOE Key Laboratory of Modern Teaching Technology, Center for Teacher Professional Ability Development, Shaanxi Normal University, 199 South Chang'an Road, Xi'an 710062, China
| | - Qiaohua Zheng
- MOE Key Laboratory of Modern Teaching Technology, Center for Teacher Professional Ability Development, Shaanxi Normal University, 199 South Chang'an Road, Xi'an 710062, China
| | - Mengjiao Chen
- School of Physics & Information Technology, Shaanxi Normal University, 620 West Chang'an Avenue, Xi'an 710119, China
| | - Zhaoqiang Qian
- MOE Key Laboratory of Modern Teaching Technology, Center for Teacher Professional Ability Development, Shaanxi Normal University, 199 South Chang'an Road, Xi'an 710062, China
| | - Chunling Wei
- MOE Key Laboratory of Modern Teaching Technology, Center for Teacher Professional Ability Development, Shaanxi Normal University, 199 South Chang'an Road, Xi'an 710062, China
| | - Jing Han
- MOE Key Laboratory of Modern Teaching Technology, Center for Teacher Professional Ability Development, Shaanxi Normal University, 199 South Chang'an Road, Xi'an 710062, China
| | - Zhiqiang Liu
- MOE Key Laboratory of Modern Teaching Technology, Center for Teacher Professional Ability Development, Shaanxi Normal University, 199 South Chang'an Road, Xi'an 710062, China
| | - Wei Ren
- MOE Key Laboratory of Modern Teaching Technology, Center for Teacher Professional Ability Development, Shaanxi Normal University, 199 South Chang'an Road, Xi'an 710062, China
| | - Yihui Liu
- MOE Key Laboratory of Modern Teaching Technology, Center for Teacher Professional Ability Development, Shaanxi Normal University, 199 South Chang'an Road, Xi'an 710062, China.
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Slivicki RA, Saberi SA, Iyer V, Vemuri VK, Makriyannis A, Hohmann AG. Brain-Permeant and -Impermeant Inhibitors of Fatty Acid Amide Hydrolase Synergize with the Opioid Analgesic Morphine to Suppress Chemotherapy-Induced Neuropathic Nociception Without Enhancing Effects of Morphine on Gastrointestinal Transit. J Pharmacol Exp Ther 2018; 367:551-563. [PMID: 30275151 DOI: 10.1124/jpet.118.252288] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 09/28/2018] [Indexed: 01/15/2023] Open
Abstract
Opioid-based therapies remain a mainstay for chronic pain management, but unwanted side effects limit therapeutic use. We compared efficacies of brain-permeant and -impermeant inhibitors of fatty acid amide hydrolase (FAAH) in suppressing neuropathic pain induced by the chemotherapeutic agent paclitaxel. Paclitaxel produced mechanical and cold allodynia without altering nestlet shredding or marble burying behaviors. We compared FAAH inhibitors that differ in their ability to penetrate the central nervous system for antiallodynic efficacy, pharmacological specificity, and synergism with the opioid analgesic morphine. (3'-(aminocarbonyl)[1,1'-biphenyl]- 3-yl)-cyclohexylcarbamate (URB597), a brain-permeant FAAH inhibitor, attenuated paclitaxel-induced allodynia via cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2) mechanisms. URB937, a brain-impermeant FAAH inhibitor, suppressed paclitaxel-induced allodynia through a CB1 mechanism only. 5-[4-(4-cyano-1-butyn-1-yl)phenyl]-1-(2,4-dichlorophenyl)-N-(1,1-dioxido-4-thiomorpholinyl)-4-methyl-1H-pyrazole-3-carboxamide (AM6545), a peripherally restricted CB1 antagonist, fully reversed the antiallodynic efficacy of N-cyclohexyl-carbamic acid, 3'-(aminocarbonyl)-6-hydroxy[1,1'- biphenyl]-3-yl ester (URB937) but only partially reversed that of URB597. Thus, URB937 suppressed paclitaxel-induced allodynia through a mechanism that was dependent upon peripheral CB1 receptor activation only. Antiallodynic effects of both FAAH inhibitors were reversed by N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251). Antiallodynic effects of URB597, but not URB937, were reversed by 6-iodo-2-methyl-1-[2-(4-morpholinyl)ethyl]-1H-indol-3-yl](4-methoxyphenyl)methanone (AM630). Isobolographic analysis revealed synergistic interactions between morphine and either URB597 or URB937 in reducing paclitaxel-induced allodynia. A leftward shift in the dose-response curve of morphine antinociception was observed when morphine was coadministered with either URB597 or URB937, consistent with morphine sparing. However, neither URB937 nor URB597 enhanced morphine-induced deficits in colonic transit. Thus, our findings suggest that FAAH inhibition may represent a therapeutic avenue to reduce the overall amount of opioid needed for treating neuropathic pain with potential to reduce unwanted side effects that accompany opioid administration.
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Affiliation(s)
- Richard A Slivicki
- Program in Neuroscience (R.A.S., V.I., A.G.H.), Department of Psychological and Brain Sciences (R.A.S., S.A.S., V.I., A.G.H.), and Gill Center for Biomolecular Science (A.G.H.), Indiana University, Bloomington, Indiana; and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (V.K.V., A.M.)
| | - Shahin A Saberi
- Program in Neuroscience (R.A.S., V.I., A.G.H.), Department of Psychological and Brain Sciences (R.A.S., S.A.S., V.I., A.G.H.), and Gill Center for Biomolecular Science (A.G.H.), Indiana University, Bloomington, Indiana; and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (V.K.V., A.M.)
| | - Vishakh Iyer
- Program in Neuroscience (R.A.S., V.I., A.G.H.), Department of Psychological and Brain Sciences (R.A.S., S.A.S., V.I., A.G.H.), and Gill Center for Biomolecular Science (A.G.H.), Indiana University, Bloomington, Indiana; and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (V.K.V., A.M.)
| | - V Kiran Vemuri
- Program in Neuroscience (R.A.S., V.I., A.G.H.), Department of Psychological and Brain Sciences (R.A.S., S.A.S., V.I., A.G.H.), and Gill Center for Biomolecular Science (A.G.H.), Indiana University, Bloomington, Indiana; and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (V.K.V., A.M.)
| | - Alexandros Makriyannis
- Program in Neuroscience (R.A.S., V.I., A.G.H.), Department of Psychological and Brain Sciences (R.A.S., S.A.S., V.I., A.G.H.), and Gill Center for Biomolecular Science (A.G.H.), Indiana University, Bloomington, Indiana; and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (V.K.V., A.M.)
| | - Andrea G Hohmann
- Program in Neuroscience (R.A.S., V.I., A.G.H.), Department of Psychological and Brain Sciences (R.A.S., S.A.S., V.I., A.G.H.), and Gill Center for Biomolecular Science (A.G.H.), Indiana University, Bloomington, Indiana; and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (V.K.V., A.M.)
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Ferreira RCM, Castor MGM, Piscitelli F, Di Marzo V, Duarte IDG, Romero TRL. The Involvement of the Endocannabinoid System in the Peripheral Antinociceptive Action of Ketamine. THE JOURNAL OF PAIN 2017; 19:487-495. [PMID: 29247851 DOI: 10.1016/j.jpain.2017.12.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 08/11/2017] [Accepted: 12/03/2017] [Indexed: 10/18/2022]
Abstract
Ketamine has been widely used as an analgesic and produces dissociative anesthetic effects. The antinociceptive effects of ketamine have been studied, but the involvement of endocannabinoids in these effects has not yet been investigated. In this study, we evaluated the involvement of the endocannabinoid system in the peripheral antinociceptive effects induced by ketamine. All drugs were administered via the intraplantar route. To induce hyperalgesia, rat paws were injected with prostaglandin E2 (2 µg per paw). The nociceptive threshold for mechanical stimulation was measured in the right hind paw of Wistar rats using the Randall-Selitto test. The tissue levels of anandamide (AEA), 2-arachidonoylglycerol, palmitoylethanolamide, and oleoylethanolamide were measured using liquid chromatography coupled to single quadrupole mass spectrometry. The administration of the cannabinoid receptor type 1 (CB1) antagonist, N(piperidine-1yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl 1 pyrazolcarboxamide (20, 40, and 80 µg per paw), but not the cannabinoid receptor type 2 antagonist, 6-iodo-2-methyl-1-(2-morpholinoethyl)-1H-indol-3-yl) (4-methoxyphenyl) methanone (100 µg per paw), antagonized the ketamine-induced peripheral antinociception in a dose-dependent manner. Additionally, the administration of the endocannabinoid metabolizing enzyme inhibitor (.5 µg per paw) or an AEA reuptake inhibitor, (5Z,8Z,11Z,14Z)N(4Hydroxy2methylphenyl)5,8,11,14 eicosatetraenamide (2.5 µg per paw) significantly enhanced low-dose ketamine-induced peripheral antinociception. AEA paw levels were increased only after ketamine administration to prostaglandin E2-injected paws. These data suggest that ketamine, in the presence of a nociceptive stimulus, induces a selective release of AEA levels and subsequent CB1 cannabinoid activation at the peripheral level. PERSPECTIVE This study suggests that ketamine antinociception depends at least in part on AEA release and CB1 cannabinoid receptor activation in inflammatory conditions. This study could potentially help clinicians in the use of ketamine as a peripheral analgesic for inflammatory pain.
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Affiliation(s)
- Renata C M Ferreira
- Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Marina G M Castor
- Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Fabiana Piscitelli
- Endocannabinoid Research Group, Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Naples, Italy
| | - Vincenzo Di Marzo
- Endocannabinoid Research Group, Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Naples, Italy
| | - Igor D G Duarte
- Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Thiago R L Romero
- Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
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The Evaluation of the Clinical Effects of Botulinum Toxin on Nocturnal Bruxism. Pain Res Manag 2017; 2017:6264146. [PMID: 28757802 PMCID: PMC5516743 DOI: 10.1155/2017/6264146] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 05/21/2017] [Indexed: 11/17/2022]
Abstract
OBJECTIVES Nocturnal bruxism can be managed by botulinum toxin (Botox®) in patients who have not responded to conservative treatment. The aim of this study was to evaluate the efficacy of botulinum toxin A (BTXA) in the treatment of nocturnal bruxism. MATERIAL AND METHODS The retrospective study comprised 25 female patients, aged 23-55 years (mean 35.84 ± 8.41 years). All patients received a single injection of BTXA in the right and left masseters. Evaluation was made by Visual Analogue Scale (VAS) values, complaint duration, onset of effect, and duration of effectiveness. RESULTS BTXA produced significant improvements in pain scores. Only 2 adverse events (8%) were recorded. CONCLUSION BTX-A is effective in the treatment of nocturnal bruxism.
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Grabiec U, Dehghani F. N-Arachidonoyl Dopamine: A Novel Endocannabinoid and Endovanilloid with Widespread Physiological and Pharmacological Activities. Cannabis Cannabinoid Res 2017; 2:183-196. [PMID: 29082315 PMCID: PMC5627668 DOI: 10.1089/can.2017.0015] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
N-arachidonoyl dopamine (NADA) is a member of the family of endocannabinoids to which several other N-acyldopamines belong as well. Their activity is mediated through various targets that include cannabinoid receptors or transient receptor potential vanilloid (TRPV)1. Synthesis and degradation of NADA are not yet fully understood. Nonetheless, there is evidence that NADA plays an important role in nociception and inflammation in the central and peripheral nervous system. The TRPV1 receptor, for which NADA is a potent agonist, was shown to be an endogenous transducer of noxious heat. Moreover, it has been demonstrated that NADA exerts protective and antioxidative properties in microglial cell cultures, cortical neurons, and organotypical hippocampal slice cultures. NADA is present in very low concentrations in the brain and is seemingly not involved in activation of the classical pathways. We believe that treatment with exogenous NADA during and after injury might be beneficial. This review summarizes the recent findings on biochemical properties of NADA and other N-acyldopamines and their role in physiological and pathological processes. These findings provide strong evidence that NADA is an effective agent to manage neuroinflammatory diseases or pain and can be useful in designing novel therapeutic strategies.
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Affiliation(s)
- Urszula Grabiec
- Department of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Faramarz Dehghani
- Department of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
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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: 99] [Impact Index Per Article: 14.1] [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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26
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Ligresti A, De Petrocellis L, Di Marzo V. From Phytocannabinoids to Cannabinoid Receptors and Endocannabinoids: Pleiotropic Physiological and Pathological Roles Through Complex Pharmacology. Physiol Rev 2016; 96:1593-659. [DOI: 10.1152/physrev.00002.2016] [Citation(s) in RCA: 253] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Apart from having been used and misused for at least four millennia for, among others, recreational and medicinal purposes, the cannabis plant and its most peculiar chemical components, the plant cannabinoids (phytocannabinoids), have the merit to have led humanity to discover one of the most intriguing and pleiotropic endogenous signaling systems, the endocannabinoid system (ECS). This review article aims to describe and critically discuss, in the most comprehensive possible manner, the multifaceted aspects of 1) the pharmacology and potential impact on mammalian physiology of all major phytocannabinoids, and not only of the most famous one Δ9-tetrahydrocannabinol, and 2) the adaptive pro-homeostatic physiological, or maladaptive pathological, roles of the ECS in mammalian cells, tissues, and organs. In doing so, we have respected the chronological order of the milestones of the millennial route from medicinal/recreational cannabis to the ECS and beyond, as it is now clear that some of the early steps in this long path, which were originally neglected, are becoming important again. The emerging picture is rather complex, but still supports the belief that more important discoveries on human physiology, and new therapies, might come in the future from new knowledge in this field.
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Affiliation(s)
- Alessia Ligresti
- Endocannabinoid Research Group, Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Pozzuoli, Italy
| | - Luciano De Petrocellis
- Endocannabinoid Research Group, Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Pozzuoli, Italy
| | - Vincenzo Di Marzo
- Endocannabinoid Research Group, Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Pozzuoli, Italy
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27
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Donvito G, Wilkerson JL, Damaj MI, Lichtman AH. Palmitoylethanolamide Reverses Paclitaxel-Induced Allodynia in Mice. J Pharmacol Exp Ther 2016; 359:310-318. [PMID: 27608657 DOI: 10.1124/jpet.116.236182] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 09/07/2016] [Indexed: 12/29/2022] Open
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) represents a serious complication associated with antineoplastic drugs. Although there are no medications available that effectively prevent CIPN, many classes of drugs have been used to treat this condition, including anticonvulsants, serotonin and noradrenaline reuptake inhibitors, and opioids. However, these therapeutic options yielded inconclusive results in CIPN clinical trials and produced assorted side effects with their prolonged use. Thus, there is an urgent need to develop efficacious and safe treatments for CIPN. In this report, we tested whether the endogenous lipid palmitoylethanolamide (PEA) alone or in combination with the anticonvulsant gabapentin would reduce allodynia in a mouse paclitaxel model of CIPN. Gabapentin and PEA reversed paclitaxel-induced allodynia with respective ED50 doses (95% confidence interval) of 67.4 (61.52-73.94) and 9.2 (8.39-10.16) mg/kg. Isobolographic analysis of these drugs in combination revealed synergistic antiallodynic effects. The PPAR-α antagonist receptor antagonist GW6471 [N-((2S)-2-(((1Z)-1-methyl-3-oxo-3-(4-(trifluoromethyl)phenyl)prop-1-enyl)amino)-3-(4-(2-(5-methyl-2-phenyl-1,3-oxazol-4-yl)ethoxy)phenyl)propyl)propanamide] completely blocked the antinociceptive effects of PEA. In addition, PEA administered via intraplantar injection into a paw, intrathecal injection, and intracerebroventricular injection reversed paclitaxel-induced allodynia, suggesting that it may act at multiple sites in the neuroaxis and periphery. Finally, repeated administration of PEA (30 mg/kg, 7 days) preserved the antiallodynic effects with no evidence of tolerance. These findings taken together suggest that PEA possesses potential to treat peripheral neuropathy in cancer patients undergoing chemotherapy.
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Affiliation(s)
- Giulia Donvito
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (G.D.; J.L.W.; M.I.D.; A.H.L.); and Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy (G.D.)
| | - Jenny L Wilkerson
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (G.D.; J.L.W.; M.I.D.; A.H.L.); and Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy (G.D.)
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (G.D.; J.L.W.; M.I.D.; A.H.L.); and Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy (G.D.)
| | - Aron H Lichtman
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (G.D.; J.L.W.; M.I.D.; A.H.L.); and Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy (G.D.)
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28
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Effect of cannabinoids on CGRP release in the isolated rat lumbar spinal cord. Neurosci Lett 2016; 614:39-42. [DOI: 10.1016/j.neulet.2015.12.060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 12/23/2015] [Accepted: 12/29/2015] [Indexed: 12/24/2022]
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Abstract
Cells in injured and inflamed tissues produce a number of proalgesic lipid-derived mediators, which excite nociceptive neurons by activating selective G-protein-coupled receptors or ligand-gated ion channels. Recent work has shown that these proalgesic factors are counteracted by a distinct group of lipid molecules that lower nociceptor excitability and attenuate nociception in peripheral tissues. Analgesic lipid mediators include endogenous agonists of cannabinoid receptors (endocannabinoids), lipid-amide agonists of peroxisome proliferator-activated receptor-α, and products of oxidative metabolism of polyunsaturated fatty acids via cytochrome P450 and other enzyme pathways. Evidence indicates that these lipid messengers are produced and act at different stages of inflammation and the response to tissue injury, and may be part of a peripheral gating mechanism that regulates the access of nociceptive information to the spinal cord and the brain. Growing knowledge about this peripheral control system may be used to discover safer medicines for pain.
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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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31
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Alshadwi A, Nadershah M, Osborn T. Therapeutic applications of botulinum neurotoxins in head and neck disorders. Saudi Dent J 2014; 27:3-11. [PMID: 25544809 PMCID: PMC4273262 DOI: 10.1016/j.sdentj.2014.10.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 08/18/2014] [Accepted: 10/20/2014] [Indexed: 11/06/2022] Open
Abstract
Objective The aim of this article is to review the mechanism of action, physiological effects, and therapeutic applications of botulinum neurotoxins in the head and neck area. Study design An extensive literature search was performed using keywords. The resulting articles were analyzed for relevance in four areas: overview on botulinum neurotoxins, the role of botulinum neurotoxins in the management of salivary secretory disorders, the role of botulinum neurotoxins in the management of facial pain, and the role of botulinum neurotoxins in head and neck movement disorders. Institutional review board approval was not needed due the nature of the study. Results Botulinum neurotoxin therapy was demonstrated to be a valuable alternative to conventional medical therapy for many conditions affecting the head and neck area in terms of morbidly, mortality, and patient satisfaction with treatment outcomes. Conclusion Botulinum neurotoxin therapy provides viable alternatives to traditional treatment modalities for some conditions affecting the head and neck region that have neurological components. This therapy can overcome some of the morbidities associated with conventional therapy. More research is needed to determine the ideal doses of botulinum neurotoxin to treat different diseases affecting the head and neck regions.
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Affiliation(s)
- Ahmad Alshadwi
- Department of Oral and Maxillofacial Surgery, Boston University-Henry M. Goldman School of Dental Medicine, 100 East Newton Street, Suite G-407, Boston, MA 02118, United States ; King Feisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Mohammed Nadershah
- Academic Faculty King Abdulaziz University-Dental School, Jeddah, Saudi Arabia
| | - Timothy Osborn
- Department of Oral and Maxillofacial Surgery, Boston University-Henry M. Goldman School of Dental Medicine, 100 East Newton Street, Suite G-407, Boston, MA 02118, United States
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dos Santos GG, Dias EV, Teixeira JM, Athie MCP, Bonet IJM, Tambeli CH, Parada CA. The analgesic effect of dipyrone in peripheral tissue involves two different mechanisms: Neuronal KATP channel opening and CB1 receptor activation. Eur J Pharmacol 2014; 741:124-31. [DOI: 10.1016/j.ejphar.2014.07.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 07/10/2014] [Accepted: 07/11/2014] [Indexed: 10/25/2022]
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Grim TW, Ghosh S, Hsu KL, Cravatt BF, Kinsey SG, Lichtman AH. Combined inhibition of FAAH and COX produces enhanced anti-allodynic effects in mouse neuropathic and inflammatory pain models. Pharmacol Biochem Behav 2014; 124:405-11. [PMID: 25058512 PMCID: PMC4206939 DOI: 10.1016/j.pbb.2014.07.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 07/09/2014] [Accepted: 07/11/2014] [Indexed: 12/31/2022]
Abstract
UNLABELLED Common pharmacological treatments of neuropathic and chronic inflammatory pain conditions generally lack efficacy and/or are associated with significant untoward side effects. However, recent preclinical data indicate that combined inhibition of cyclooxygenase (COX) and fatty acid amide hydrolase (FAAH), the primary catabolic enzyme of the endocannabinoid N-arachidonoylethanolamine (anandamide; AEA), produces enhanced antinociceptive effects in a variety of murine models of pain. Accordingly, the primary objective of the present study was to investigate the consequences of co-administration of the COX inhibitor diclofenac and the highly selective FAAH inhibitor PF-3845 in models of neuropathic pain (i.e., chronic constrictive injury of the sciatic nerve (CCI)) and inflammatory pain induced by an intraplantar injection of carrageenan. Here, we report that combined administration of subthreshold doses of these drugs produced enhanced antinociceptive effects in CCI and carrageenan pain models, the latter of which was demonstrated to require both CB1 and CB2 receptors. The combined administration of subthreshold doses of these drugs also increased AEA levels and decreased prostaglandin levels in whole brain. Together, these data add to the growing research that dual blockade of FAAH and COX represents a potential therapeutic strategy for the treatment of neuropathic and inflammatory pain states. PERSPECTIVE Tandem inhibition of FAAH and COX attenuates inflammatory and neuropathic pain states, which may avoid potentially harmful side effects of other therapeutic options, such as NSAIDs or opioids.
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Affiliation(s)
- Travis W Grim
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298-0613, USA.
| | - Sudeshna Ghosh
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298-0613, USA
| | - Ku-Lung Hsu
- Department of Chemical Physiology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037, USA
| | - Benjamin F Cravatt
- Department of Chemical Physiology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037, USA
| | - Steven G Kinsey
- Department of Psychology, West Virginia University, Morgantown, WV 26506, USA
| | - Aron H Lichtman
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298-0613, USA
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Marchalant Y, Brownjohn PW, Bonnet A, Kleffmann T, Ashton JC. Validating Antibodies to the Cannabinoid CB2 Receptor: Antibody Sensitivity Is Not Evidence of Antibody Specificity. J Histochem Cytochem 2014; 62:395-404. [PMID: 24670796 PMCID: PMC4174627 DOI: 10.1369/0022155414530995] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Antibody-based methods for the detection and quantification of membrane integral proteins, in particular, the G protein-coupled receptors (GPCRs), have been plagued with issues of primary antibody specificity. In this report, we investigate one of the most commonly utilized commercial antibodies for the cannabinoid CB2 receptor, a GPCR, using immunoblotting in combination with mass spectrometry. In this way, we were able to develop powerful negative and novel positive controls. By doing this, we are able to demonstrate that it is possible for an antibody to be sensitive for a protein of interest—in this case CB2—but still cross-react with other proteins and therefore lack specificity. Specifically, we were able to use western blotting combined with mass spectrometry to unequivocally identify CB2 protein in over-expressing cell lines. This shows that a common practice of validating antibodies with positive controls only is insufficient to ensure antibody reliability. In addition, our work is the first to develop a label-free method of protein detection using mass spectrometry that, with further refinement, could provide unequivocal identification of CB2 receptor protein in native tissues.
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Affiliation(s)
- Yannick Marchalant
- Aix-Marseille University, Neurobiologie des Interactions Cellulaires et Neurophysiopathologie, Marseille, France (YM,AB)Department of Pharmacology and Toxicology (PWB,JCA)Centre for Protein Research, Biochemistry Department, University of Otago, Dunedin, New Zealand (TK)
| | - Philip W Brownjohn
- Aix-Marseille University, Neurobiologie des Interactions Cellulaires et Neurophysiopathologie, Marseille, France (YM,AB)Department of Pharmacology and Toxicology (PWB,JCA)Centre for Protein Research, Biochemistry Department, University of Otago, Dunedin, New Zealand (TK)
| | - Amandine Bonnet
- Aix-Marseille University, Neurobiologie des Interactions Cellulaires et Neurophysiopathologie, Marseille, France (YM,AB)Department of Pharmacology and Toxicology (PWB,JCA)Centre for Protein Research, Biochemistry Department, University of Otago, Dunedin, New Zealand (TK)
| | - Torsten Kleffmann
- Aix-Marseille University, Neurobiologie des Interactions Cellulaires et Neurophysiopathologie, Marseille, France (YM,AB)Department of Pharmacology and Toxicology (PWB,JCA)Centre for Protein Research, Biochemistry Department, University of Otago, Dunedin, New Zealand (TK)
| | - John C Ashton
- Aix-Marseille University, Neurobiologie des Interactions Cellulaires et Neurophysiopathologie, Marseille, France (YM,AB)Department of Pharmacology and Toxicology (PWB,JCA)Centre for Protein Research, Biochemistry Department, University of Otago, Dunedin, New Zealand (TK)
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Greco R, Mangione AS, Sandrini G, Nappi G, Tassorelli C. Activation of CB2 receptors as a potential therapeutic target for migraine: evaluation in an animal model. J Headache Pain 2014; 15:14. [PMID: 24636539 PMCID: PMC3995520 DOI: 10.1186/1129-2377-15-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 02/28/2014] [Indexed: 12/14/2022] Open
Abstract
Background Experimental animal models of migraine have suggested the existence of interactions between the endocannabinoid system and pain mediation in migraine. Extensive evidence has demonstrated a role for the cannabinoid-1 (CB1) receptor in antinociception. However, recent research suggests that also CB2 receptors, especially located outside the central nervous system, play a role in the perception of pain. Systemic administration of nitroglycerin (NTG) consistently induces spontaneous-like headache attacks in migraneurs; in the rat, systemic NTG induces a condition of hyperalgesia, probably through the activation of cerebral/spinal structures involved in nociceptive transmission. In this study we evaluated the role of CB2 receptors in two animal models of pain that may be relevant for migraine: the tail flick test and the formalin test performed during NTG-induced hyperalgesia. Methods The study was performed in male Sprague-Dawley rats pre-treated with NTG (10 mg/kg, i.p.) or vehicle (4 hours before) and treated with the CB2 agonist AM1241 o dimethylsulfoxide (DMSO) 60 minutes before both the tail flick test and the formalin test. Results AM1241 showed a significant analgesic effect in baseline conditions in both tests. Furthermore, when administered 3 hours after NTG administration, AM1241 at both doses significantly reduced the total number of flinches/shakes during phase II of the test. Conclusion These findings suggest that the pharmacological manipulation of the CB2 receptor may represent a potential therapeutic tool for the treatment of migraine.
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Affiliation(s)
| | | | | | | | - Cristina Tassorelli
- Laboratory of Neurophysiology of Integrative Autonomic Systems, Headache Science Centre, "C, Mondino" National Neurological Institute, 27100 Pavia, Italy.
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Keimpema E, Hökfelt T, Harkany T, Doherty P. The molecular interplay between endocannabinoid and neurotrophin signals in the nervous system and beyond. Eur J Neurosci 2014; 39:334-43. [DOI: 10.1111/ejn.12431] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 10/16/2013] [Accepted: 10/18/2013] [Indexed: 12/20/2022]
Affiliation(s)
- Erik Keimpema
- Division of Molecular Neurobiology; Department of Medical Biochemistry and Biophysics; Karolinska Institutet; Scheeles väg 1:A1 SE-17177 Stockholm Sweden
- Department of Molecular Neuroscience; Center for Brain Research; Medical University of Vienna; Spitalgasse 4 A-1090 Vienna Austria
| | - Tomas Hökfelt
- Department of Neuroscience; Karolinska Institutet; Stockholm Sweden
| | - Tibor Harkany
- Division of Molecular Neurobiology; Department of Medical Biochemistry and Biophysics; Karolinska Institutet; Scheeles väg 1:A1 SE-17177 Stockholm Sweden
- Department of Molecular Neuroscience; Center for Brain Research; Medical University of Vienna; Spitalgasse 4 A-1090 Vienna Austria
| | - Patrick Doherty
- Wolfson Centre for Age-Related Diseases; King's College London; London SE1 9RT UK
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McPartland JM, Simons DG. Myofascial Trigger Points: Translating Molecular Theory into Manual Therapy. J Man Manip Ther 2013. [DOI: 10.1179/106698106790819982] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
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38
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Gondim DV, Araújo JCB, Cavalcante ALC, Havt A, Quetz JDS, Brito GADC, Ribeiro RDA, Lima Vale M. CB1 and CB2 contribute to antinociceptive and anti-inflammatory effects of electroacupuncture on experimental arthritis of the rat temporomandibular joint. Can J Physiol Pharmacol 2012. [PMID: 23181276 DOI: 10.1139/y2012-130] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Electroacupuncture (EA) and cannabinoids have been reported to have anti-inflammatory and antinociceptive effects in animal models of arthritis. Male Wistar rats were injected with saline or zymosan (2 mg) into the temporomandibular joint (TMJ). EA (10 Hz, 30 min) was performed 2 h after or 1 h before zymosan administration. AM251 or AM630 (3 mg/kg, i.p.)were administered before EA treatment. Mechanical hypernociception was accessed after zymosan administration. Rats were sacrificed 6 h after zymosan administration and the joint was removed for histopathological analysis. The gene expression of CB₁ and CB₂ receptors was assessed after sacrifice of the TMJ arthritic animals. EA inhibited zymosan-induced hypernociception (p < 0.05). AM251 reversed significantly the antinociceptive effect of EA, suggesting that the CB₁ receptor is involved in this effect. AM630 reversed the anti-inflammatory effect of EA. CB₁ and CB₂ receptor gene expression was upregulated 6 h after zymosan-induced arthritis in the EA-treated group. We observed downregulation of CB₂ receptor gene expression in the EA group at the 24th hour compared with the 6th hour. Higher CB₁ receptor gene expression was also found compared with the 6th hour. EA produced antinociceptive and anti-inflammatory effects, and these effects appeared to be mediated through CB₁ and CB₂ receptor activation.
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Affiliation(s)
- Delane Viana Gondim
- Medical Sciences Post-Graduation, Faculty of Medicine, Federal University of Ceará, Fortaleza, Brazil.
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Liu YQ, Qiu F, Qiu CY, Cai Q, Zou P, Wu H, Hu WP. Cannabinoids inhibit acid-sensing ion channel currents in rat dorsal root ganglion neurons. PLoS One 2012; 7:e45531. [PMID: 23029075 PMCID: PMC3446897 DOI: 10.1371/journal.pone.0045531] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 08/21/2012] [Indexed: 12/26/2022] Open
Abstract
Local acidosis has been found in various pain-generating conditions such as inflammation and tissue injury. Cannabinoids exert a powerful inhibitory control over pain initiation via peripheral cognate receptors. However, the peripheral molecular targets responsible for the antinociceptive effects of cannabinoids are still poorly understood. Here, we have found that WIN55,212-2, a cannabinoid receptor agonist, inhibits the activity of native acid-sensing ion channels (ASICs) in rat dorsal root ganglion (DRG) neurons. WIN55,212-2 dose-dependently inhibited proton-gated currents mediated by ASICs. WIN55,212-2 shifted the proton concentration–response curve downwards, with an decrease of 48.6±3.7% in the maximum current response but with no significant change in the EC50 value. The inhibition of proton-gated current induced by WIN55,212-2 was almost completely blocked by the selective CB1 receptor antagonist AM 281, but not by the CB2 receptor antagonist AM630. Pretreatment of forskolin, an AC activator, and the addition of cAMP also reversed the inhibition of WIN55,212-2. Moreover, WIN55,212-2 altered acid-evoked excitability of rat DRG neurons and decreased the number of action potentials induced by acid stimuli. Finally, WIN55,212-2 attenuated nociceptive responses to injection of acetic acid in rats. These results suggest that WIN55,212-2 inhibits the activity of ASICs via CB1 receptor and cAMP dependent pathway in rat primary sensory neurons. Thus, cannabinoids can exert their analgesic action by interaction with ASICs in the primary afferent neurons, which was novel analgesic mechanism of cannabinoids.
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Affiliation(s)
- Yu-Qiang Liu
- Department of Pharmacology, Hubei University of Science and Technology, Xianning, Hubei, P R China
| | - Fang Qiu
- Department of Pharmacology, Hubei University of Science and Technology, Xianning, Hubei, P R China
| | - Chun-Yu Qiu
- Department of Pharmacology, Hubei University of Science and Technology, Xianning, Hubei, P R China
| | - Qi Cai
- Department of Pharmacology, Hubei University of Science and Technology, Xianning, Hubei, P R China
| | - Pengcheng Zou
- Hubei Furen Pharmaceutical Corporation Ltd, Shinanqiao, Tongcheng, Hubei, P R China
| | - Heming Wu
- Hubei Furen Pharmaceutical Corporation Ltd, Shinanqiao, Tongcheng, Hubei, P R China
| | - Wang-Ping Hu
- Department of Pharmacology, Hubei University of Science and Technology, Xianning, Hubei, P R China
- * E-mail:
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Ramos JA, Bianco FJ. The role of cannabinoids in prostate cancer: Basic science perspective and potential clinical applications. Indian J Urol 2012; 28:9-14. [PMID: 22557710 PMCID: PMC3339795 DOI: 10.4103/0970-1591.94942] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Prostate cancer is a global public health problem, and it is the most common cancer in American men and the second cause for cancer-related death. Experimental evidence shows that prostate tissue possesses cannabinoid receptors and their stimulation results in anti-androgenic effects. To review currently relevant findings related to effects of cannabinoid receptors in prostate cancer. PubMed search utilizing the terms “cannabis,” “cannabinoids,” “prostate cancer,” and “cancer pain management,” giving preference to most recent publications was done. Articles identified were screened for their relevance to the field of prostate cancer and interest to both urologist and pain specialists. Prostate cancer cells possess increased expression of both cannabinoid 1 and 2 receptors, and stimulation of these results in decrease in cell viability, increased apoptosis, and decreased androgen receptor expression and prostate-specific antigen excretion. It would be of interest to conduct clinical studies utilizing cannabinoids for patients with metastatic prostate cancer, taking advantage not only of its beneficial effects on prostate cancer but also of their analgesic properties for bone metastatic cancer pain.
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Affiliation(s)
- Juan A Ramos
- Universidad de Carabobo, School of Health Sciences, Bárbula, Venezuela
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Booker L, Kinsey SG, Abdullah RA, Blankman JL, Long JZ, Ezzili C, Boger DL, Cravatt BF, Lichtman AH. The fatty acid amide hydrolase (FAAH) inhibitor PF-3845 acts in the nervous system to reverse LPS-induced tactile allodynia in mice. Br J Pharmacol 2012; 165:2485-96. [PMID: 21506952 DOI: 10.1111/j.1476-5381.2011.01445.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Inflammatory pain presents a problem of clinical relevance and often elicits allodynia, a condition in which non-noxious stimuli are perceived as painful. One potential target to treat inflammatory pain is the endogenous cannabinoid (endocannabinoid) system, which is comprised of CB1 and CB2 cannabinoid receptors and several endogenous ligands, including anandamide (AEA). Blockade of the catabolic enzyme fatty acid amide hydrolase (FAAH) elevates AEA levels and elicits antinociceptive effects, without the psychomimetic side effects associated with Δ(9) -tetrahydrocannabinol (THC). EXPERIMENTAL APPROACH Allodynia was induced by intraplantar injection of LPS. Complementary genetic and pharmacological approaches were used to determine the strategy of blocking FAAH to reverse LPS-induced allodynia. Endocannabinoid levels were quantified using mass spectroscopy analyses. KEY RESULTS FAAH (-/-) mice or wild-type mice treated with FAAH inhibitors (URB597, OL-135 and PF-3845) displayed an anti-allodynic phenotype. Furthermore, i.p. PF-3845 increased AEA levels in the brain and spinal cord. Additionally, intraplantar PF-3845 produced a partial reduction in allodynia. However, the anti-allodynic phenotype was absent in mice expressing FAAH exclusively in the nervous system under a neural specific enolase promoter, implicating the involvement of neuronal fatty acid amides (FAAs). The anti-allodynic effects of FAAH-compromised mice required activation of both CB1 and CB2 receptors, but other potential targets of FAA substrates (i.e. µ-opioid, TRPV1 and PPARα receptors) had no apparent role. CONCLUSIONS AND IMPLICATIONS AEA is the primary FAAH substrate reducing LPS-induced tactile allodynia. Blockade of neuronal FAAH reverses allodynia through the activation of both cannabinoid receptors and represents a promising target to treat inflammatory pain. LINKED ARTICLES This article is part of a themed section on Cannabinoids in Biology and Medicine. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-8. To view Part I of Cannabinoids in Biology and Medicine visit http://dx.doi.org/10.1111/bph.2011.163.issue-7.
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Affiliation(s)
- Lamont Booker
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
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García-Gutiérrez MS, García-Bueno B, Zoppi S, Leza JC, Manzanares J. Chronic blockade of cannabinoid CB2 receptors induces anxiolytic-like actions associated with alterations in GABA(A) receptors. Br J Pharmacol 2012; 165:951-64. [PMID: 21838753 DOI: 10.1111/j.1476-5381.2011.01625.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND AND PURPOSE The aim of this study was to explore the effects of CB(2) receptor agonist and antagonist in the regulation of anxiety-like behaviours. EXPERIMENTAL APPROACHES Effects of acute and chronic treatment with the CB(2) receptor agonist JWH133 and CB(2) receptor antagonist AM630 were evaluated in the light-dark box (LDB) and elevated plus maze (EPM) tests in Swiss ICR mice. CB(2) receptor, GABA(A) α(2) and GABA(A) γ(2) gene and protein expression in the cortex and amygdala of mice chronically treated with JWH133 or AM630 were examined by RT-PCR and Western blot. Effects of chronic AM630 treatment were evaluated in spontaneously anxious DBA/2 mice in LDB. KEY RESULTS Acute JWH133 treatment failed to produce any effect. Acute AM630 treatment increased anxiety and was blocked by pre-treatment with JWH133. Chronic JWH133 treatment increased anxiety-like behaviour whereas chronic AM630 treatment was anxiolytic in LDB and EPM tests. Chronic AM630 treatment increased gene and reduced protein expression of CB(2) receptors, GABA(A) α(2) and GABA(A) γ(2) in cortex and amygdala. Chronic JWH133 treatment resulted in opposite gene and protein alterations. In addition, chronic AM630 administration decreased the anxiety of DBA/2 mice in the LDB test. CONCLUSIONS AND IMPLICATIONS The opposing behavioural and molecular changes observed after chronic treatment with AM630 or JWH133 support the key role of CB(2) receptors in the regulation of anxiety. Indeed, the efficacy of AM630 in reducing the anxiety of the spontaneously anxious DBA/2 strain of mice strengthens the potential of the CB(2) receptor as a new target in the treatment of anxiety-related disorders.
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Affiliation(s)
- María S García-Gutiérrez
- Instituto de Neurociencias, Universidad Miguel Hernández-CSIC, Avda. Ramón y Cajal s/n, San Juan de Alicante, Alicante, Spain
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Mitrirattanakul S, Poomsawat S, Fuangtharnthip P. Cannabinoid receptor 1 (CB1R) expression in rat dental pulp. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/s1348-8643(12)00003-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Inhibiting the breakdown of endogenous opioids and cannabinoids to alleviate pain. Nat Rev Drug Discov 2012; 11:292-310. [DOI: 10.1038/nrd3673] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Guindon J, Guijarro A, Piomelli D, Hohmann AG. Peripheral antinociceptive effects of inhibitors of monoacylglycerol lipase in a rat model of inflammatory pain. Br J Pharmacol 2012; 163:1464-78. [PMID: 21198549 DOI: 10.1111/j.1476-5381.2010.01192.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND AND PURPOSE The endocannabinoid 2-arachidonoylglycerol (2-AG) is degraded primarily by monoacylglycerol lipase (MGL). We compared peripheral antinociceptive effects of JZL184, a novel irreversible MGL inhibitor, with the reversible MGL-preferring inhibitor URB602 and exogenous 2-AG in rats. EXPERIMENTAL APPROACH Nociception in the formalin test was assessed in groups receiving dorsal paw injections of vehicle, JZL184 (0.001-300 µg), URB602 (0.001-600 µg), 2-AG (ED(50)), 2-AG + JZL184 (at their ED(50)), 2-AG + URB602 (at their ED(50)), AM251 (80 µg), AM251 + JZL184 (10 µg), AM630 (25 µg) or AM630 + JZL184 (10 µg). Effects of MGL inhibitors on endocannabinoid accumulation and on activities of endocannabinoid-metabolizing enzymes were assessed. KEY RESULTS Intra-paw administration of JZL184, URB602 and 2-AG suppressed early and late phases of formalin pain. JZL184 and URB602 acted through a common mechanism. JZL184 (ED(50) Phase 1: 0.06 ± 0.028; Phase 2: 0.03 ± 0.011 µg) produced greater antinociception than URB602 (ED(50) Phase 1: 120 ± 51.3; Phase 2: 66 ± 23.9 µg) or 2-AG. Both MGL inhibitors produced additive antinociceptive effects when combined with 2-AG. Antinociceptive effects of JZL184, like those of URB602, were blocked by cannabinoid receptor 1 (CB(1)) and cannabinoid receptor 2 (CB(2)) antagonists. JZL184 suppressed MGL but not fatty-acid amide hydrolase or N-arachidonoyl-phosphatidylethanolamine phospholipase D activities ex vivo. URB602 increased hind paw 2-AG without altering anandamide levels. CONCLUSIONS AND IMPLICATIONS MGL inhibitors suppressed formalin-induced pain through peripheral CB(1) and CB(2) receptor mechanisms. MGL inhibition increased paw skin 2-AG accumulation to mediate these effects. MGL represents a target for the treatment of inflammatory pain.
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Affiliation(s)
- Josée Guindon
- Neuroscience and Behavior Program, Department of Psychology, University of Georgia, Athens, GA, USA
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Rezende R, Paiva-Lima P, Dos Reis W, Camêlo V, Faraco A, Bakhle Y, Francischi J. Endogenous Opioid and Cannabinoid Mechanisms Are Involved in the Analgesic Effects of Celecoxib in the Central Nervous System. Pharmacology 2012; 89:127-36. [DOI: 10.1159/000336346] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 01/01/2012] [Indexed: 02/02/2023]
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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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Reis GML, Ramos MA, Pacheco DDF, Klein A, Perez AC, Duarte IDG. Endogenous cannabinoid receptor agonist anandamide induces peripheral antinociception by activation of ATP-sensitive K+ channels. Life Sci 2011; 88:653-7. [DOI: 10.1016/j.lfs.2011.01.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 12/15/2010] [Accepted: 01/07/2011] [Indexed: 02/06/2023]
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Schalk-Hihi C, Schubert C, Alexander R, Bayoumy S, Clemente JC, Deckman I, DesJarlais RL, Dzordzorme KC, Flores CM, Grasberger B, Kranz JK, Lewandowski F, Liu L, Ma H, Maguire D, Macielag MJ, McDonnell ME, Mezzasalma Haarlander T, Miller R, Milligan C, Reynolds C, Kuo LC. Crystal structure of a soluble form of human monoglyceride lipase in complex with an inhibitor at 1.35 Å resolution. Protein Sci 2011; 20:670-83. [PMID: 21308848 PMCID: PMC3081545 DOI: 10.1002/pro.596] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 01/14/2011] [Indexed: 01/07/2023]
Abstract
A high-resolution structure of a ligand-bound, soluble form of human monoglyceride lipase (MGL) is presented. The structure highlights a novel conformation of the regulatory lid-domain present in the lipase family as well as the binding mode of a pharmaceutically relevant reversible inhibitor. Analysis of the structure lacking the inhibitor indicates that the closed conformation can accommodate the native substrate 2-arachidonoyl glycerol. A model is proposed in which MGL undergoes conformational and electrostatic changes during the catalytic cycle ultimately resulting in its dissociation from the membrane upon completion of the cycle. In addition, the study outlines a successful approach to transform membrane associated proteins, which tend to aggregate upon purification, into a monomeric and soluble form.
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Affiliation(s)
- Céline Schalk-Hihi
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477,*Correspondence to: Céline Schalk-Hihi (E-mail: ) or Carsten Schubert (E-mail: )
| | - Carsten Schubert
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477,*Correspondence to: Céline Schalk-Hihi (E-mail: ) or Carsten Schubert (E-mail: )
| | - Richard Alexander
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Shariff Bayoumy
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Jose C Clemente
- Department of Lead Generation Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Ingrid Deckman
- Department of Lead Generation Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Renee L DesJarlais
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Keli C Dzordzorme
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Christopher M Flores
- Department of Neuroscience, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Bruce Grasberger
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - James K Kranz
- Department of Lead Generation Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Frank Lewandowski
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Li Liu
- Department of Medicinal Chemistry, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Hongchang Ma
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Diane Maguire
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Mark J Macielag
- Department of Medicinal Chemistry, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Mark E McDonnell
- Department of Medicinal Chemistry, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Tara Mezzasalma Haarlander
- Department of Lead Generation Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Robyn Miller
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Cindy Milligan
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Charles Reynolds
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
| | - Lawrence C Kuo
- Department of Structural Biology, Johnson & Johnson Pharmaceutical Research and DevelopmentL.L.C., Welsh and McKean Roads, Spring House, Pennsylvania 19477
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50
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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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