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Gallego-Landin I, García-Baos A, Castro-Zavala A, Valverde O. Reviewing the Role of the Endocannabinoid System in the Pathophysiology of Depression. Front Pharmacol 2021; 12:762738. [PMID: 34938182 PMCID: PMC8685322 DOI: 10.3389/fphar.2021.762738] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 11/11/2021] [Indexed: 01/04/2023] Open
Abstract
Major depressive disorder is a high-impact, debilitating disease and it is currently considered the most prevalent mental illness. It is associated with disability, as well as increased morbidity and mortality. Despite its significant repercussions in our society, its exact pathophysiology remains unclear and therefore, available antidepressant treatment options are limited and, in some cases, ineffective. In the past years, research has focused on the development of a multifactorial theory of depression. Simultaneously, evidence supporting the role of the endocannabinoid system in the neurobiology of neuropsychiatric diseases has emerged. Studies have shown that the endocannabinoid system strongly impacts neurotransmission, and the neuroendocrine and neuroimmune systems, which are known to be dysfunctional in depressive patients. Accordingly, common antidepressants were shown to have a direct impact on the expression of cannabinoid receptors throughout the brain. Therefore, the relationship between the endocannabinoid system and major depressive disorder is worth consideration. Nevertheless, most studies focus on smaller pieces of what is undoubtedly a larger mosaic of interdependent processes. Therefore, the present review summarizes the existing literature regarding the role of the endocannabinoid system in depression aiming to integrate this information into a holistic picture for a better understanding of the relationship between the two.
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Affiliation(s)
- Ines Gallego-Landin
- Neurobiology of Behaviour Research Group (GReNeC—NeuroBio), Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Alba García-Baos
- Neurobiology of Behaviour Research Group (GReNeC—NeuroBio), Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Adriana Castro-Zavala
- Neurobiology of Behaviour Research Group (GReNeC—NeuroBio), Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Olga Valverde
- Neurobiology of Behaviour Research Group (GReNeC—NeuroBio), Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
- Neuroscience Research Programme, IMIM-Hospital del Mar Research Institute, Barcelona, Spain
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Signorello MG, Leoncini G. Activation of CaMKKβ/AMPKα pathway by 2-AG in human platelets. J Cell Biochem 2017; 119:876-884. [PMID: 28661046 DOI: 10.1002/jcb.26251] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 06/28/2017] [Indexed: 12/17/2022]
Abstract
The objective of this study was to determine whether AMPK is activated by 2-arachidonoylglycerol (2-AG) and participates to the cytoskeleton control in human platelets. We found that 2-AG stimulates the AMPKα activation through a Ca2+ /Calmodulin-dependent pathway as the specific inhibition of the CaMKKβ by STO-609 inhibits the AMPKα phosphorylation/activation. Moreover, the CaMKKβ/AMPKα pathway activated by 2-AG is involved in the phosphorylation of cofilin, vasodilator stimulated phosphoprotein (VASP), and myosin light chain (MLCs). These proteins participate to actin cytoskeletal remodelling during aggregation. We found that the phosphorylation/activation inhibition of these proteins is associated with a significant reduction in actin polymerization, aggregation, ATP, and α-granule secretion. Finally, AMPKα activation, Cofilin, VASP, and MLCs phosphorylation are significantly reduced by SR141716, the specific inhibitor of type 1 cannabinoid (CB1) receptor, suggesting that the CB1 receptor is involved in the 2-AG effect. In conclusion, we have shown that the CaMKKβ/AMPKα pathway is activated by 2-AG in human platelets and controls the phosphorylation of key proteins involved in actin polymerization and aggregation.
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Affiliation(s)
| | - Giuliana Leoncini
- Department of Pharmacy, Biochemistry Lab, University of Genoa, Genova, Italy
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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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Edwards A, Abizaid A. Driving the need to feed: Insight into the collaborative interaction between ghrelin and endocannabinoid systems in modulating brain reward systems. Neurosci Biobehav Rev 2016; 66:33-53. [PMID: 27136126 DOI: 10.1016/j.neubiorev.2016.03.032] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 03/08/2016] [Accepted: 03/31/2016] [Indexed: 01/29/2023]
Abstract
Independent stimulation of either the ghrelin or endocannabinoid system promotes food intake and increases adiposity. Given the similar distribution of their receptors in feeding associated brain regions and organs involved in metabolism, it is not surprising that evidence of their interaction and its importance in modulating energy balance has emerged. This review documents the relationship between ghrelin and endocannabinoid systems within the periphery and hypothalamus (HYP) before presenting evidence suggesting that these two systems likewise work collaboratively within the ventral tegmental area (VTA) to modulate non-homeostatic feeding. Mechanisms, consistent with current evidence and local infrastructure within the VTA, will be proposed.
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Affiliation(s)
- Alexander Edwards
- Department of Neuroscience, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
| | - Alfonso Abizaid
- Department of Neuroscience, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
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Signorello MG, Leoncini G. Regulation of cAMP Intracellular Levels in Human Platelets Stimulated by 2-Arachidonoylglycerol. J Cell Biochem 2015; 117:1240-9. [PMID: 26460717 DOI: 10.1002/jcb.25408] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 10/09/2015] [Indexed: 11/08/2022]
Abstract
We demonstrated that in human platelets the endocannabinoid 2-arachidonoylglycerol (2-AG) decreased dose- and time-dependently cAMP intracellular levels. No effect on cAMP decrease induced by 2-AG was observed in the presence of the adenylate cyclase inhibitor SQ22536 as well in platelets pretreated with the thromboxane A2 receptor antagonist, SQ29548 or with aspirin, inhibitor of arachidonic acid metabolism through the cyclooxygenase pathway. An almost complete recovering of cAMP level was measured in platelets pretreated with the specific inhibitor of phosphodiesterase (PDE) 3A, milrinone. In platelets pretreated with LY294002 or MK2206, inhibitors of PI3K/AKT pathway, and with U73122, inhibitor of phospholipase C pathway, only a partial prevention was shown. cAMP intracellular level depends on synthesis by adenylate cyclase and hydrolysis by PDEs. In 2-AG-stimulated platelets adenylate cyclase activity seems to be unchanged. In contrast PDEs appear to be involved. In particular PDE3A was specifically activated, as milrinone reversed cAMP reduction by 2-AG. 2-AG enhanced PDE3A activity through its phosphorylation. The PI3K/AKT pathway and PKC participate to this PDE3A phosphorylation/activation mechanism as it was greatly inhibited by platelet pretreatment with LY294002, MK2206, U73122, or the PKC specific inhibitor GF109203X. Taken together these data suggest that 2-AG potentiates its power of platelet agonist reducing cAMP intracellular level.
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Affiliation(s)
- Maria Grazia Signorello
- Department of Pharmacy, Biochemistry Lab, University of Genoa, Viale Benedetto XV 3, 16132, Genova, Italy
| | - Giuliana Leoncini
- Department of Pharmacy, Biochemistry Lab, University of Genoa, Viale Benedetto XV 3, 16132, Genova, Italy
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Acyltransferases and transacylases that determine the fatty acid composition of glycerolipids and the metabolism of bioactive lipid mediators in mammalian cells and model organisms. Prog Lipid Res 2014; 53:18-81. [DOI: 10.1016/j.plipres.2013.10.001] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 07/20/2013] [Accepted: 10/01/2013] [Indexed: 12/21/2022]
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Yamashita A, Oka S, Tanikawa T, Hayashi Y, Nemoto-Sasaki Y, Sugiura T. The actions and metabolism of lysophosphatidylinositol, an endogenous agonist for GPR55. Prostaglandins Other Lipid Mediat 2013; 107:103-16. [PMID: 23714700 DOI: 10.1016/j.prostaglandins.2013.05.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 05/14/2013] [Accepted: 05/14/2013] [Indexed: 12/12/2022]
Abstract
Lysophosphatidylinositol (LPI) is a subspecies of lysophospholipid and is assumed to be not only a degradation product of phosphatidylinositol (PI), but also a bioactive lysophospholipid mediator. However, not much attention has been directed toward LPI compared to lysophosphatidic acid (LPA), since the receptor for LPI has not been identified. During screening for an agonist for the orphan G protein coupled receptor GPR55, we identified LPI, 2-arachidonoyl LPI in particular, as an agonist for GPR55. Our efforts to identify an LPI receptor facilitated research on LPI as a lipid messenger. In addition, we also found that DDHD1, previously identified as phosphatidic acid-preferring phospholipase A1, was one of the synthesizing enzymes of 2-arachidonoyl LPI. Here, we summarized the background for discovering the LPI receptor, and the actions/metabolism of LPI. We also referred to the biosynthesis of PI, a 1-stearoyl-2-arachidonoyl species, since the molecule is the precursor of 2-arachidonoyl LPI. Furthermore, we discussed physiological and/or pathophysiological processes involving LPI and GPR55, including the relevance of LPI-GPR55 and cannabinoids, since GPR55 was previously postulated to be another cannabinoid receptor. Although there is no doubt that GPR55 is the LPI receptor, we should re-consider whether or not GPR55 is in fact another cannabinoid receptor.
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Affiliation(s)
- Atsushi Yamashita
- Faculty of Pharma-Sciences, Teikyo University, Kaga 2-11-1, Itabashi-Ku, Tokyo 173-8605, Japan.
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Paudel KS, Chen J, Stinchcomb AL. LC–MS Method for the Pharmacokinetic Evaluation of 2-Arachidonoyl Glycerol in Small Volume Plasma Samples. Chromatographia 2009. [DOI: 10.1365/s10337-009-1413-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Carney ST, Lloyd ML, MacKinnon SE, Newton DC, Jones JD, Howlett AC, Norford DC. Cannabinoid regulation of nitric oxide synthase I (nNOS) in neuronal cells. J Neuroimmune Pharmacol 2009; 4:338-49. [PMID: 19365734 PMCID: PMC2719736 DOI: 10.1007/s11481-009-9153-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Accepted: 03/18/2009] [Indexed: 02/02/2023]
Abstract
In our previous studies, CB1 cannabinoid receptor agonists stimulated production of cyclic GMP and translocation of nitric oxide (NO)-sensitive guanylyl cyclase in neuronal cells (Jones et al., Neuropharmacology 54:23–30, 2008). The purpose of these studies was to elucidate the signal transduction of cannabinoid-mediated neuronal nitric oxide synthase (nNOS) activation in neuronal cells. Cannabinoid agonists CP55940 (2-[(1S,2R,5S)-5-hydroxy-2-(3-hydroxypropyl) cyclohexyl]-5-(2-methyloctan-2-yl)phenol), WIN55212-2 (R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthalenyl)methanone mesylate), and the metabolically stable analog of anandamide, (R)-(+)-methanandamide stimulated NO production in N18TG2 cells over a 20-min period. Rimonabant (N-(piperidin-lyl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-H-pyrazole-3-carboxamide), a CB1 receptor antagonist, partially or completely curtailed cannabinoid-mediated NO production. Inhibition of NOS activity (NG-nitro-l-arginine) or signaling via Gi/o protein (pertussis toxin) significantly limited NO production by cannabinoid agonists. Ca2+ mobilization was not detected in N18TG2 cells after cannabinoid treatment using Fluo-4 AM fluorescence. Cannabinoid-mediated NO production was attributed to nNOS activation since endothelial NOS and inducible NOS protein and mRNA were not detected in N18TG2 cells. Bands of 160 and 155 kDa were detected on Western blot analysis of cytosolic and membrane fractions of N18TG2 cells, using a nNOS antibody. Chronic treatment of N18TG2 cells with cannabinoid agonists downregulated nNOS protein and mRNA as detected using Western blot analysis and real-time polymerase chain reaction, respectively. Cannabinoid agonists stimulated NO production via signaling through CB1 receptors, leading to activation of Gi/o protein and enhanced nNOS activity. The findings of these studies provide information related to cannabinoid-mediated NO signal transduction in neuronal cells, which has important implications in the ongoing elucidation of the endocannabinoid system in the nervous system.
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Affiliation(s)
- Skyla T. Carney
- Neuroscience of Drug Abuse Research Program, Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, 700 George Street, Durham, NC 27707 USA
| | - Michael L. Lloyd
- Neuroscience of Drug Abuse Research Program, Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, 700 George Street, Durham, NC 27707 USA
| | - Shanta E. MacKinnon
- Neuroscience of Drug Abuse Research Program, Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, 700 George Street, Durham, NC 27707 USA
| | - Doshandra C. Newton
- Neuroscience of Drug Abuse Research Program, Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, 700 George Street, Durham, NC 27707 USA
| | - Jenelle D. Jones
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, NC 27157 USA
| | - Allyn C. Howlett
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, NC 27157 USA
| | - Derek C. Norford
- Neuroscience of Drug Abuse Research Program, Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, 700 George Street, Durham, NC 27707 USA
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Abstract
2-Arachidonoylglycerol is an arachidonic acid-containing monoacylglycerol isolated from the rat brain and canine gut as an endogenous ligand for the cannabinoid receptors (CB1 and CB2). 2-Arachidonoylglycerol binds to both the CB1 receptor, abundantly expressed in the nervous system, and the CB2 receptor, mainly expressed in the immune system, with high affinity, and exhibits a variety of cannabimimetic activities. Notably, anandamide, another endogenous ligand for the cannabinoid receptors, acts as a partial agonist at these cannabinoid receptors, whereas 2-arachidonoylglycerol acts as a full agonist. The results of structure-activity relationship experiments strongly suggested that 2-arachidonoylglycerol rather than anandamide is the true natural ligand for both the CB1 and the CB2 receptors. Evidence is gradually accumulating which shows that 2-arachidonoylglycerol plays physiologically and pathophysiologically essential roles in various mammalian tissues and cells.
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Affiliation(s)
- Takayuki Sugiura
- Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa, Japan.
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Baldassarri S, Bertoni A, Bagarotti A, Sarasso C, Zanfa M, Catani MV, Avigliano L, Maccarrone M, Torti M, Sinigaglia F. The endocannabinoid 2-arachidonoylglycerol activates human platelets through non-CB1/CB2 receptors. J Thromb Haemost 2008; 6:1772-9. [PMID: 18647220 DOI: 10.1111/j.1538-7836.2008.03093.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
BACKGROUND The endocannabinoid 2-arachidonoylglycerol (2-AG) is an endogenous lipid that acts through the activation of G-protein-coupled cannabinoid receptors and plays essential roles in many physiological contexts. In the cardiovascular system 2-AG is generated by both activated endothelial cells and platelets, and participates in the regulation of inflammation and thrombosis. Although human platelets actively metabolize endocannabinoids, 2-AG also binds to platelet surface and leads to cell activation. OBJECTIVE To investigate the biological consequence of 2-AG interactions with human platelets and to clarify the role of cannabinoid receptors. METHODS Gel-filtered platelets were stimulated with 2-AG in the presence or absence of various inhibitors. Platelet aggregation and secretion were measured in a lumiaggregometer. Calcium ion movements were measured in FURA-2 loaded platelets. Thromboxane A(2) (TxA(2)) generation was evaluated as Thromboxane B(2) accumulation with a commercial EIA assay. RESULTS 2-AG induced platelet shape change, aggregation and secretion with a dose-dependent mechanism that required engagement of platelet TxA(2) receptors. 2-AG caused also cytosolic calcium increase; however, it was totally dependent on availability of TxA(2). Indeed 2-AG was able to induce a robust generation of TxA(2) through the cyclooxygenase pathway. Treatment of platelets with inhibitors of monoacylglycerol lipase and fatty acid amide hydrolase did not affect the activation induced by 2-AG. Moreover, neither CB(1) and CB(2) proteins nor CB(1)/CB(2) mRNAs were detected in platelets. CONCLUSIONS 2-AG can be considered a new physiologic platelet agonist able to induce full platelet activation and aggregation with a non-CB(1)/CB(2) receptor-mediated mechanism.
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Affiliation(s)
- S Baldassarri
- Department of Clinical and Experimental Medicine, University of Eastern Piedmont, Novara, Italy
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Jones JD, Carney ST, Vrana KE, Norford DC, Howlett AC. Cannabinoid receptor-mediated translocation of NO-sensitive guanylyl cyclase and production of cyclic GMP in neuronal cells. Neuropharmacology 2007; 54:23-30. [PMID: 17707868 PMCID: PMC3170565 DOI: 10.1016/j.neuropharm.2007.06.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Revised: 06/16/2007] [Accepted: 06/25/2007] [Indexed: 11/25/2022]
Abstract
Cannabinoid agonists regulate NO and cyclic AMP production in N18TG2 neuroblastoma cells, leading to the hypothesis that neuronal cyclic GMP production could be regulated by CB(1) cannabinoid receptors. NO (nitric oxide)-sensitive guanylyl cyclase (GC) is a heterodimeric cytosolic protein that mediates the down-stream effects of NO. Genes of proteins in the cyclic GMP pathway (alpha(1), alpha(2), and beta(1) subunits of NO-sensitive GC and PKG1, but not PKG2) were expressed in N18TG2 cells, as was the CB(1) but not the CB(2) cannabinoid receptor. Stimulation of N18TG2 cells by cannabinoid agonists CP55940 and WIN55212-2 increased cyclic GMP levels in an ODQ-sensitive manner. GC-beta(1) in membrane fractions was increased after 5 or 20 min stimulation, and was significantly depleted in the cytosol by 1h. The cytosolic pool of GC-beta(1) was replenished after 48 h of continued cannabinoid drug treatment. Translocation of GC-beta(1) from the cytosol was blocked by the CB(1) antagonist rimonabant (SR141716) and by the Gi/o inactivator pertussis toxin, indicating that the CB(1) receptor and Gi/o proteins are required for translocation. Long-term treatment with rimonabant or pertussis toxin reduced the amount of GC-beta(1) in the cytosolic pool. We conclude that CB(1) receptors stimulate cyclic GMP production and that intracellular translocation of GC from cytosol to the membranes is intrinsic to the mechanism and may be a tonically active or endocannabinoid-regulated process.
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Affiliation(s)
- Jenelle D. Jones
- Neuroscience of Drug Abuse Research Program, Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, U.S.A
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, NC 27517, U.S.A
| | - Skyla T. Carney
- Neuroscience of Drug Abuse Research Program, Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, U.S.A
| | - Kent E. Vrana
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, NC 27517, U.S.A
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, U.S.A
| | - Derek C. Norford
- Neuroscience of Drug Abuse Research Program, Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, U.S.A
| | - Allyn C. Howlett
- Neuroscience of Drug Abuse Research Program, Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, U.S.A
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, NC 27517, U.S.A
- Corresponding Author. Tel.: +1 336 716 8545; fax +1 336 716 8501, (A.C. Howlett), Wake Forest University Health Sciences, Medical Center Blvd., Winston-Salem, NC 27157 U.S.A
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Oka S, Arai S, Waku K, Tokumura A, Sugiura T. Depolarization-induced Rapid Generation of 2-Arachidonoylglycerol, an Endogenous Cannabinoid Receptor Ligand, in Rat Brain Synaptosomes. ACTA ACUST UNITED AC 2007; 141:687-97. [PMID: 17339228 DOI: 10.1093/jb/mvm070] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
2-arachidonoylglycerol (2-AG) is an endogenous ligand for the cannabinoid receptors with a variety of potent biological activities. In this study, we first examined the effects of potassium-induced depolarization on the level of 2-AG in rat brain synaptosomes. We found that a significant amount of 2-AG was generated in the synaptosomes following depolarization. Notably, depolarization did not affect the levels of other molecular species of monoacylglycerols. Furthermore, the level of anandamide was very low and did not change markedly following depolarization. It thus appeared that the depolarization-induced accelerated generation is a unique feature of 2-AG. We obtained evidence that phospholipase C is involved in the generation of 2-AG in depolarized synaptosomes: U73122, a phospholipase C inhibitor, markedly reduced the depolarization-induced generation of 2-AG, and the level of diacylglycerol was rapidly elevated following depolarization. A significant amount of 2-AG was released from synaptosomes upon depolarization. Interestingly, treatment of the synaptosomes with SR141716A, a CB1 receptor antagonist, augmented the release of glutamate from depolarized synaptosomes. These results strongly suggest that the endogenous ligand for the cannabinoid receptors, i.e. 2-AG, generated through increased phospholipid metabolism upon depolarization, plays an important role in attenuating glutamate release from the synaptic terminals by acting on the CB1 receptor.
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Affiliation(s)
- Saori Oka
- Faculty of Pharmaceutical Sciences, Teikyo University, Sagamihara, Kanagawa 199-0195 Japan
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Rosenberger TA, Farooqui AA, Horrocks LA. Bovine brain diacylglycerol lipase: substrate specificity and activation by cyclic AMP-dependent protein kinase. Lipids 2007; 42:187-95. [PMID: 17393225 DOI: 10.1007/s11745-007-3019-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Accepted: 01/03/2007] [Indexed: 02/02/2023]
Abstract
Diacylglycerol lipase (EC 3.1.1.3) was purified from bovine brain microsomes using multiple column chromatographic techniques. The purified enzyme migrates as a single band on SDS-PAGE and has an apparent molecular weight of 27 kDa. Substrate specificity experiments using mixed molecular species of 1,2-diacyl-sn-glycerols indicate that low concentrations of Ca(2+) and Mg(2+) have no direct effect on enzymic activity and 1,2-diacyl-sn-glycerols are the preferred substrate over 1,3-diacyl-sn-glycerols. The enzyme hydrolyzes stearate in preference to palmitate from the sn-1 position of 1,2-diacyl-sn-glycerols. 1-O-Alkyl-2-acyl-sn-glycerols are not a substrate for the purified enzyme. The native enzyme had a V (max) value of 616 nmol/min mg protein. Phosphorylation by cAMP-dependent protein kinase resulted in a threefold increase in catalytic throughput (V (max) = 1,900 nmol/min mg protein). The substrate specificity and catalytic properties of the bovine brain diacylglycerol lipase suggest that diacylglycerol lipase may regulate protein kinase C activity and 2-arachidonoyl-sn-glycerol levels by rapidly altering the intracellular concentration of diacylglycerols.
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Affiliation(s)
- Thad A Rosenberger
- Department of Pharmacology, Physiology, and Therapeutics, University of North Dakota, School of Medicine and Health Sciences, 501 North Columbia Road, Grand Forks, ND 58203, USA.
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Drolet B, Simard C, Poirier P. Impact of weight-loss medications on the cardiovascular system: focus on current and future anti-obesity drugs. Am J Cardiovasc Drugs 2007; 7:273-88. [PMID: 17696568 DOI: 10.2165/00129784-200707040-00005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Overweight and obesity have been rising dramatically worldwide and are associated with numerous co-morbidities such as cardiovascular disease (CVD), type 2 diabetes mellitus, hypertension, certain cancers, and sleep apnea. In fact, obesity is an independent risk factor for CVD and CVD risks have also been documented in obese children. The majority of overweight and obese patients who achieve a significant short-term weight loss do not maintain their lower bodyweight in the long term. This may be due to a lack of intensive counseling and support from a facilitating environment including dedicated healthcare professionals such as nutritionists, kinesiologists, and behavior specialists. As a result, there has been a considerable focus on the role of adjunctive therapy such as pharmacotherapy for long-term weight loss and weight maintenance. Beyond an unfavorable risk factor profile, overweight and obesity also impact upon heart structure and function. Since the beginning, the quest for weight loss drugs has encountered warnings from regulatory agencies and the withdrawal from the market of efficient but unsafe medications. Fenfluramine was withdrawn from the market because of unacceptable pulmonary and cardiac adverse effects. Nevertheless, there is extensive research directed at the development of new anti-obesity compounds. The effect of these molecules on CVD risk factors has been studied and reported but information regarding their impact on the cardiovascular system is sparse. Thus, instead of looking at the benefit of weight loss on metabolism and risk factor management, this article discusses the impact of weight loss medications on the cardiovascular system. The potential interaction of available and potential new weight loss drugs with heart function and structure is reviewed.
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Affiliation(s)
- Benoit Drolet
- Institut Universitaire de Cardiologie et de Pneumologie, Laval Hospital, Quebec City, Quebec, Canada
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17
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Suhara Y, Oka S, Kittaka A, Takayama H, Waku K, Sugiura T. Synthesis and biological evaluation of several structural analogs of 2-arachidonoylglycerol, an endogenous cannabinoid receptor ligand. Bioorg Med Chem 2007; 15:854-67. [PMID: 17110113 DOI: 10.1016/j.bmc.2006.10.049] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Revised: 10/19/2006] [Accepted: 10/20/2006] [Indexed: 11/24/2022]
Abstract
2-Arachidonoylglycerol (2-AG (1)) is an endogenous ligand for the cannabinoid receptors (CB1 and CB2). There is growing evidence that 2-arachidonoylglycerol plays important physiological and pathophysiological roles in various mammalian tissues and cells, though the details remain to be clarified. In this study, we synthesized several remarkable analogs of 2-arachidonoylglycerol, closely related in chemical structure to 2-arachidonoylglycerol: an analog containing an isomer of arachidonic acid with migrated olefins (2-AGA118 (3)), an analog containing a one-carbon shortened fatty acyl moiety (2-AGA113 (4)), an analog containing an one-carbon elongated fatty acyl moiety (2-AGA114 (5)), a hydroxy group-containing analog (2-AGA105 (6)), a ketone group-containing analog (2-AGA109 (7)), and a methylene-linked analog (2-AGA104 (8)). We evaluated their biological activities as cannabinoid receptor agonists using NG108-15 cells which express the CB1 receptor and HL-60 cells which express the CB2 receptor. Notably, these structural analogs of 2-arachidonoylglycerol exhibited only weak agonistic activities toward either the CB1 receptor or the CB2 receptor, which is in good contrast to 2-arachidonoylglycerol which acted as a full agonist at these cannabinoid receptors. These results clearly indicate that the structure of 2-arachidonoylglycerol is strictly recognized by the cannabinoid receptors (CB1 and CB2) and provide further evidence that the cannabinoid receptors are primarily the intrinsic receptors for 2-arachidonoylglycerol.
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Affiliation(s)
- Yoshitomo Suhara
- Department of Pharmaceutical Chemistry, Faculty of Pharmcaceutical Sciences, Teikyo University, Sagamihara, Kanagawa 199-0195, Japan
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18
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Oz M. Receptor-independent actions of cannabinoids on cell membranes: Focus on endocannabinoids. Pharmacol Ther 2006; 111:114-44. [PMID: 16584786 DOI: 10.1016/j.pharmthera.2005.09.009] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Accepted: 09/30/2005] [Indexed: 01/08/2023]
Abstract
Cannabinoids are a structurally diverse group of mostly lipophilic molecules that bind to cannabinoid receptors. In fact, endogenous cannabinoids (endocannabinoids) are a class of signaling lipids consisting of amides and esters of long-chain polyunsaturated fatty acids. They are synthesized from lipid precursors in plasma membranes via Ca(2+) or G-protein-dependent processes and exhibit cannabinoid-like actions by binding to cannabinoid receptors. However, endocannabinoids can produce effects that are not mediated by these receptors. In pharmacologically relevant concentrations, endocannabinoids modulate the functional properties of voltage-gated ion channels including Ca(2+) channels, Na(+) channels, various types of K(+) channels, and ligand-gated ion channels such as serotonin type 3, nicotinic acetylcholine, and glycine receptors. In addition, modulatory effects of endocannabinoids on other ion-transporting membrane proteins such as transient potential receptor-class channels, gap junctions and transporters for neurotransmitters have also been demonstrated. Furthermore, functional properties of G-protein-coupled receptors for different types of neurotransmitters and neuropeptides are altered by direct actions of endocannabinoids. Although the mechanisms of these effects are currently not clear, it is likely that these direct actions of endocannabinoids are due to their lipophilic structures. These findings indicate that additional molecular targets for endocannabinoids exist and that these targets may represent novel sites for cannabinoids to alter either the excitability of the neurons or the response of the neuronal systems. This review focuses on the results of recent studies indicating that beyond their receptor-mediated effects, endocannabinoids alter the functions of ion channels and other integral membrane proteins directly.
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Affiliation(s)
- Murat Oz
- National Institute on Drug Abuse, NIH/DHHS, Intramural Research Program, Cellular Neurobiology Branch, 5500 Nathan Shock Drive, Baltimore MD, 21224, USA.
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19
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Abstract
Marijuana has been used as a traditional medicine and a pleasure-inducing drug for thousands of years around the world, especially in Asia. Delta(9)-tetrahydrocannabinol, major psychoactive component of marijuana, has been shown to interact with specific cannabinoid receptors, thereby eliciting a variety of pharmacological responses in experimental animals and human. In 1990, the gene encoding a cannabinoid receptor (CB1) was cloned. This prompted the search for endogenous ligands. In 1992, N-arachidonoylethanolamine (anandamide) was isolated from pig brain as an endogenous ligand, and in 1995, 2-arachidonoylglycerol was isolated from rat brain and canine gut as another endogenous ligand. Both anandamide and 2-arachidonoylglycerol exhibit various cannabimimetic activities. The results of structure-activity relationship experiments, however, revealed that 2-arachidonoylglycerol, but not anandamide, is the intrinsic natural ligand for the cannabinoid receptor. 2-arachidonoylglycerol is a degradation product of inositol phospholipids that links the function of the cannabinoid receptors with the enhanced inositol phospholipid turnover in stimulated tissues and cells. The possible physiological roles of cannabinoid receptors and 2-arachidonoylglycerol in various mammalian tissues such as those of the nervous and inflammatory cells are demonstrated. Furthermore, the future development of therapeutic drugs coming from this endocannabinoid system are discussed.
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Affiliation(s)
- Keizo Waku
- Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa, Japan.
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20
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Abstract
The cannabinoid receptor family currently includes two types: CB1, characterized in neuronal cells and brain, and CB2, characterized in immune cells and tissues. CB1 and CB2 receptors are members of the superfamily of seven-transmembrane-spanning (7-TM) receptors, having a protein structure defined by an array of seven membrane-spanning helices with intervening intracellular loops and a C-terminal domain that can associate with G proteins. Cannabinoid receptors are associated with G proteins of the Gi/o family (Gi1, 2 and 3, and Go1 and 2). Signal transduction via Gi inhibits adenylyl cyclase in most tissues and cells, although signaling via Gs stimulates adenylyl cyclase in some experimental models. Evidence exists for cannabinoid receptor-mediated Ca2+ fluxes and stimulation of phospholipases A and C. Stimulation of CB1 and CB2 cannabinoid receptors leads to phosphorylation and activation of p42/p44 mitogen-activated protein kinase (MAPK), p38 MAPK and Jun N-terminal kinase (JNK) as signaling pathways to regulate nuclear transcription factors. The CB1 receptor regulates K+ and Ca2+ ion channels, probably via Go. Ion channel regulation serves as an important component of neurotransmission modulation by endogenous cannabinoid compounds released in response to neuronal depolarization. Cannabinoid receptor signaling via G proteins results from interactions with the second, third and fourth intracellular loops of the receptor. Desensitization of signal transduction pathways that couple through the G proteins probably entails phosphorylation of critical amino acid residues on these intracellular surfaces.
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Affiliation(s)
- A C Howlett
- Neuroscience/Drug Abuse Research Program, 208 JLC-BBRI, North Carolina Central University, 700 George Street, Durham, NC 27707, USA.
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21
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Demuth DG, Gkoumassi E, Dröge MJ, Dekkers BGJ, Esselink HJ, van Ree RM, Parsons ME, Zaagsma J, Molleman A, Nelemans SA. Arachidonic acid mediates non-capacitative calcium entry evoked by CB1-cannabinoid receptor activation in DDT1 MF-2 smooth muscle cells. J Cell Physiol 2005; 205:58-67. [PMID: 15887237 DOI: 10.1002/jcp.20390] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cannabinoid CB1-receptor stimulation in DDT1 MF-2 smooth muscle cells induces a rise in [Ca2+]i, which is dependent on extracellular Ca2+ and modulated by thapsigargin-sensitive stores, suggesting capacitative Ca2+ entry (CCE), and by MAP kinase. Non-capacitative Ca2+ entry (NCCE) stimulated by arachidonic acid (AA) partly mediates histamine H1-receptor-evoked increases in [Ca2+]i in DDT1 MF-2 cells. In the current study, both Ca2+ entry mechanisms and a possible link between MAP kinase activation and increasing [Ca2+]i were investigated. In the whole-cell patch clamp configuration, the CB-receptor agonist CP 55, 940 evoked a transient, Ca2+-dependent K+ current, which was not blocked by the inhibitors of CCE, 2-APB, and SKF 96365. AA, but not its metabolites, evoked a transient outward current and inhibited the response to CP 55,940 in a concentration-dependent manner. CP 55,940 induced a concentration-dependent release of AA, which was inhibited by the CB1 antagonist SR 141716. The non-selective Ca2+ channel blockers La3+ and Gd3+ inhibited the CP 55,940-induced current at concentrations that had no effect on thapsigargin-evoked CCE. La3+ also inhibited the AA-induced current. CP 55,940-induced AA release was abolished by Gd3+ and by phospholipase A2 inhibition using quinacrine; this compound also inhibited the outward current. The CP 55,940-induced AA release was strongly reduced by the MAP kinase inhibitor PD 98059. The data suggest that in DDT1 MF-2 cells, AA is an integral component of the CB1 receptor signaling pathway, upstream of NCCE and, via PLA2, downstream of MAP kinase.
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Affiliation(s)
- Dirk G Demuth
- School of Life Sciences, Faculty of Health and Human Sciences, University of Hertfordshire, Hatfield, Hertfordshire, United Kingdom
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22
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Abstract
After their discovery, the two known cannabinoid receptors, CB(1) and CB(2), have been the focus of research into the cellular signalling mechanisms of cannabinoids. The initial assessment, mainly derived from expression studies, was that cannabinoids, via G(i/o) proteins, negatively modulate cyclic AMP levels, and activate inward rectifying K(+) channels. Recent findings have complicated this assessment on different levels: (1) cannabinoids include a wide range of compounds with varying profiles of affinity and efficacy at the known CB receptors, and these profiles do not necessarily match their biological activity; (2) CB receptors appear to be intrinsically active and possibly coupled to more than one type of G protein; (3) CB receptor signalling mechanisms are diverse and dependent on the system studied; (4) cannabinoids have other targets than CB receptors. The aim of this mini review is to discuss the current literature regarding CB receptor signalling pathways. These include regulation of adenylyl cyclase, MAP kinase, intracellular Ca(2+), and ion channels. In addition, actions of cannabinoids that are not mediated by CB(1) or CB(2) receptors are discussed.
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Affiliation(s)
- Dirk G Demuth
- School of Life Sciences, University of Hertfordshire, CP Snow Building, Hatfield, Herts, UK
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Di Marzo V, De Petrocellis L, Bisogno T. Endocannabinoids Part I: molecular basis of endocannabinoid formation, action and inactivation and development of selective inhibitors. Expert Opin Ther Targets 2005; 5:241-65. [PMID: 15992179 DOI: 10.1517/14728222.5.2.241] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The discovery of specific receptors for Delta9-tetrahydrocannabinol, the major psychoactive component of marijuana, opened new horizons for the possible therapeutic exploitation of Cannabis sativa and the cannabinoids. Endogenous ligands of cannabinoid receptors, the 'endocannabinoids', were found and the molecular mechanisms underlying their biological effects and the regulation of their levels are now being identified. Cause/effect relationships between alterations of cannabinoid receptor/endocannabinoid levels in tissues and the symptoms of various pathological states are starting to be revealed. These studies may open the way to the possible use of substances that manipulate endocannabinoid levels and actions, such as inhibitors of the biosynthesis and inactivation and receptor antagonists, as cannabinoid-based therapeutic agents with little or no psychotropic side effect, thus potentially fulfilling an ambition nurtured for almost two centuries.
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Affiliation(s)
- V Di Marzo
- Istituto per la Chimica di Molecole di Interesse Biologico, Consiglio Nazionale delle Ricerche, Via Toiano 6, 80072, Arco Felice (NA), Italy.
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24
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Abstract
CB(1) receptor cellular signal transduction is dependent on the expression of G proteins to which the receptor couples, the potential for precoupling of particular G proteins to the receptors either by scaffolding mechanisms or colocalization in lipid raft domains, and the effector mechanisms that these transducer molecules regulate. This discourse will evaluate studies of efficacy for CB(1) receptor-Gi/o activation at the molecular level. Evidence for brain regional differences in CB(1) receptor signal transduction efficacy and agonist selectivity for G proteins will be summarized. The possibility that CB(1) receptors interact with Gs or Gq will be evaluated, and questions with regard to the constitutive activity and G protein sequestration will be posed.
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Affiliation(s)
- Allyn C Howlett
- Neuroscience of Drug Abuse Research Program, Biomedical/Biotechnology Research Institute, 700 George Street, North Carolina Central University, Durham, NC 27707, USA.
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25
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Evans RM, Scott RH, Ross RA. Multiple actions of anandamide on neonatal rat cultured sensory neurones. Br J Pharmacol 2004; 141:1223-33. [PMID: 15023857 PMCID: PMC1574891 DOI: 10.1038/sj.bjp.0705723] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. We have investigated the effects of the endocannabinoid anandamide (AEA) on neuronal excitability and vanilloid TRPV1 receptors in neonatal rat cultured dorsal root ganglion neurones. 2. Using whole-cell patch-clamp electrophysiology, we found that AEA inhibits high-voltage-activated Ca(2+) currents by 33+/-9% (five out of eight neurones) in the absence of the CB(1) receptor antagonist SR141716A (100 nM) and by 32+/-6% (seven out of 10 neurones) in the presence of SR141716A. 3. Fura-2 fluorescence Ca(2+) imaging revealed that AEA produced distinct effects on Ca(2+) transients produced by depolarisation evoked by 30 mM KCl. In a population of neurones of larger somal area (372+/-20 microM(2)), it significantly enhanced Ca(2+) transients (80.26+/-13.12% at 1 microM), an effect that persists after pertussis toxin pretreatment. In a population of neurones of smaller somal area (279+/-18 microM(2)), AEA significantly inhibits Ca(2+) transients (30.75+/-3.54% at 1 microM), an effect that is abolished by PTX pretreatment. 4. Extracellular application of 100 nM AEA failed to evoke TRPV1 receptor inward currents in seven out of eight neurones that responded to capsaicin (1 microM), with a mean inward current of -0.94+/-0.21 nA. In contrast, intracellular application of 100 nM AEA elicited robust inward currents in approximately 62% of neurones, the mean population response was -0.85+/-0.21 nA. When AEA was applied to the intracellular environment with capsazepine (1 microM), the mean population inward current was -0.01+/-0.01 nA. Under control conditions, mean population current fluctuations of -0.09+/-0.05 nA were observed.
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MESH Headings
- Animals
- Animals, Newborn
- Arachidonic Acids/pharmacology
- Calcium Channels/drug effects
- Calcium Channels/physiology
- Calcium Signaling/drug effects
- Calcium Signaling/physiology
- Capsaicin/analogs & derivatives
- Capsaicin/pharmacology
- Cells, Cultured
- Drug Synergism
- Endocannabinoids
- Fura-2/chemistry
- Ganglia, Spinal/cytology
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/physiology
- Neurons, Afferent/drug effects
- Pertussis Toxin/pharmacology
- Piperidines/pharmacology
- Polyunsaturated Alkamides
- Potassium Chloride/pharmacology
- Pyrazoles/pharmacology
- Rats
- Receptor, Cannabinoid, CB1/drug effects
- Receptor, Cannabinoid, CB1/physiology
- Receptors, Drug/antagonists & inhibitors
- Receptors, Drug/drug effects
- Rimonabant
- TRPV Cation Channels
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Affiliation(s)
- Rhian M Evans
- Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland
| | - Roderick H Scott
- Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland
| | - Ruth A Ross
- Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland
- Author for correspondence:
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26
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Mukhopadhyay S, Shim JY, Assi AA, Norford D, Howlett AC. CB(1) cannabinoid receptor-G protein association: a possible mechanism for differential signaling. Chem Phys Lipids 2002; 121:91-109. [PMID: 12505694 DOI: 10.1016/s0009-3084(02)00153-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Effects of cannabinoid compounds on neurons are predominantly mediated by the CB(1) cannabinoid receptor. Onset of signaling cascades in response to cannabimimetic drugs is triggered by the interaction of the cannabinoid receptor with G(i/o) proteins. Much work has been done to delineate the cannabinoid agonist-induced downstream signaling events; however, it remains to define the molecular basis of cannabinoid receptor-G protein interactions that stimulate these signaling pathways. In this review, we discuss several signal transduction pathways, focusing on studies that demonstrate the efficacy of CB(1) receptor agonists through G protein mediated pathways.
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Affiliation(s)
- Somnath Mukhopadhyay
- Neuroscience and Drug Abuse Research Program, J L Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, 700 George Street, Durham, NC 27707, USA
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27
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Schmid HHO, Schmid PC, Berdyshev EV. Cell signaling by endocannabinoids and their congeners: questions of selectivity and other challenges. Chem Phys Lipids 2002; 121:111-34. [PMID: 12505695 DOI: 10.1016/s0009-3084(02)00157-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The major endocannabinoids, anandamide (N-arachidonoylethanolamide, 20:4n-6 N-acylethanolamine) and 2-arachidonoylglycerol (2-AG) are structurally and functionally similar, but they are produced by different metabolic pathways and their levels must therefore be regulated by different mechanisms. Both endocannabinoids are accompanied by cannabinoid receptor-inactive, saturated and mono- or di-unsaturated congeners which can influence their metabolism and function. Here we review published data on the presence and production of anandamide and 2-AG and their congeners in mammalian cells and discuss this information in terms of their proposed signaling functions.
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Affiliation(s)
- Harald H O Schmid
- The Hormel Institute, University of Minnesota, 801-16th Avenue N E, Austin, MN 55912, USA.
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28
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Abstract
Cannabinoid receptors were named because they have affinity for the agonist delta9-tetrahydrocannabinol (delta9-THC), a ligand found in organic extracts from Cannabis sativa. The two types of cannabinoid receptors, CB1 and CB2. are G protein coupled receptors that are coupled through the Gi/o family of proteins to signal transduction mechanisms that include inhibition of adenylyl cyclase, activation of mitogen-activated protein kinase, regulation of calcium and potassium channels (CB1 only), and other signal transduction pathways. A class of the eicosanoid ligands are relevant to lipid-mediated cellular signaling because they serve as endogenous agonists for cannabinoid receptors, and are thus referred to as endocannabinoids. Those compounds identified to date include the eicosanoids arachidonoylethanolamide (anandamide), 2-arachidonoylglycerol and 2-arachidonylglyceryl ether (noladin ether). Several excellent reviews on endocannabinoids and their synthesis, metabolism and function have appeared in recent years. This paper will describe the biological activities, pharmacology, and signal transduction mechanisms for the cannabinoid receptors, with particular emphasis on the responses to the eicosanoid ligands.
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Affiliation(s)
- Allyn C Howlett
- Julius L Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham 27707, USA.
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29
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Kojima SI, Sugiura T, Waku K, Kamikawa Y. Contractile response to a cannabimimetic eicosanoid, 2-arachidonoylglycerol, of longitudinal smooth muscle from the guinea-pig distal colon in vitro. Eur J Pharmacol 2002; 444:203-7. [PMID: 12063081 DOI: 10.1016/s0014-2999(02)01650-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The effect of 2-arachidonoylglycerol, a cannabimimetic eicosanoid, was studied on mucosa-free longitudinal muscle strips isolated from the guinea-pig distal colon. In the presence of indomethacin (3 microM) and N(G)-nitro-L-arginine (100 microM), 2-arachidonoylglycerol (10 nM-10 microM) produced concentration-dependent and tetrodotoxin (1 microM)-sensitive contractions of the longitudinal muscle strips. The contractions were markedly attenuated in the presence of atropine (0.2 microM), and partially by hexamethonium (100 microM) pretreatment. The response to 2-arachidonoylglycerol was mimicked with N-arachidonoylethanolamine (anandamide, 0.1-30 microM), another cannabimimetic eicosanoid, but the cannabinoid CB(1)/CB(2) receptor agonist, R-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3,-de]-1,4-benzoxazin-6-yl]-1-naphthalenylmethanone (WIN55,212-2) (0.1-10 microM), and the vanilloid receptor agonist, (all Z)-(4-hydroxyphenyl)-5,8,11,14-eicosatetraenamide (AM 404) (10-30 microM), were without effect. The cannabinoid CB(1) receptor antagonist, N-piperidino-5-(4-chlorophenyl)-l-(2,4-dichlorophenyl)-4-methyl-3-pyrazole-caroxamide (SR141716A) (1 microM), the cannabinoid CB(2) receptor antagonist, [N-[1S]-endo-1,3,3-trimethyl bicyclo [2.2.1] heptan-2-yl]-5-(4-chloro-3-methylphenyl)-l-(4-methylbenzyl)-pyrazole-3-carboxamide (SR144528) (1 microM), and the vanilloid receptor antagonist, capsazepine (10 microM), did not shift the concentration-response curve for 2-arachidonoylglycerol to the right. The contractile action of 2-arachidonoylglycerol was also partially attenuated in the presence of nordihydroguaiaretic acid (10 microM), a lipoxygenase inhibitor. These results indicate that 2-arachidonoylglycerol produces contraction of longitudinal muscle of the guinea-pig distal colon via mainly stimulation of myenteric cholinergic neurones, and that neither cannabinoid CB(1)/CB(2) receptors nor vanilloid receptors contributed to the response. The present results suggest the possibility that lipoxygenase metabolites may also contribute, at least in part, to the contractile action of 2-arachidonoylglycerol.
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Affiliation(s)
- Shu-ichi Kojima
- Department of Pharmacology, Dokkyo University School of Medicine, Mibu, Tochigi 321-0293, Japan.
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30
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McAllister SD, Glass M. CB(1) and CB(2) receptor-mediated signalling: a focus on endocannabinoids. Prostaglandins Leukot Essent Fatty Acids 2002; 66:161-71. [PMID: 12052033 DOI: 10.1054/plef.2001.0344] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The discovery that the major psychoactive component of marijuana activated two G-protein coupled receptors prompted the search for the endogenous cannabinoid ligands now termed endocannabinoids. To date three putative ligands have been isolated, all consisting of arachidonic acid linked to a polar head group. Both synthetic and endogenous cannabinoids have been the focus of extensive study over the past few years. The signalling events produced by endocannabinoids as compared with Delta(9) -THC and synthetic cannabinoids contain many similarities. However, as research focuses more on endogenous ligands the divergence between these classes of compounds grows. This review focuses upon the developments in endocannabinoid signal transduction from receptor-mediated activation of common G-protein linked effector pathways through downstream regulation of gene transcription.
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Affiliation(s)
- Sean D McAllister
- Forbes Norris ALS Research Center, California Pacific Medical Centre, 2351 Clay Street, Suite 416, San Francisco, CA 94115, USA
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31
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Sugiura T, Kobayashi Y, Oka S, Waku K. Biosynthesis and degradation of anandamide and 2-arachidonoylglycerol and their possible physiological significance. Prostaglandins Leukot Essent Fatty Acids 2002; 66:173-92. [PMID: 12052034 DOI: 10.1054/plef.2001.0356] [Citation(s) in RCA: 243] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
N -arachidonoylethanolamine (anandamide) was the first endogenous cannabinoid receptor ligand to be discovered. Dual synthetic pathways for anandamide have been proposed. One is the formation from free arachidonic acid and ethanolamine, and the other is the formation from N -arachidonoyl phosphatidylethanolamine (PE) through the action of a phosphodiesterase. These pathways, however, do not appear to be able to generate a large amount of anandamide, at least under physiological conditions. The generation of anandamide from free arachidonic acid and ethanolamine is catalyzed by a degrading enzyme anandamide amidohydrolase/fatty acid amide hydrolase operating in reverse and requires large amounts of substrates. As for the second pathway, arachidonic acids esterified at the 1-position of glycerophospholipids, which are mostly esterified at the 2-position, are utilized for the formation of N -arachidonoyl PE, a stored precursor form of anandamide. In fact, the actual levels of anandamide in various tissues are generally low except in a few cases. 2-Arachidonoylglycerol (2-AG) was the second endogenous cannabinoid receptor ligand to be discovered. 2-AG is a degradation product of arachidonic acid-containing glycerophospholipids such as inositol phospholipids. Several investigators have demonstrated that 2-AG is produced in a variety of tissues and cells upon stimulation. 2-AG acts as a full agonist at the cannabinoid receptors (CB1 and CB2). Evidence is gradually accumulating and indicates that 2-AG is the most efficacious endogenous natural ligand for the cannabinoid receptors. In this review, we summarize the tissue levels, biosynthesis, degradation and possible physiological significance of two endogenous cannabimimetic molecules, anandamide and 2-AG.
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Affiliation(s)
- T Sugiura
- Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Tsukui-gun, Kanagawa 199-0195, Japan.
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Nogueron MI, Porgilsson B, Schneider WE, Stucky CL, Hillard CJ. Cannabinoid receptor agonists inhibit depolarization-induced calcium influx in cerebellar granule neurons. J Neurochem 2001; 79:371-81. [PMID: 11677265 DOI: 10.1046/j.1471-4159.2001.00567.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neuronal cannabinoid receptors (CB(1)) are coupled to inhibition of voltage-sensitive Ca(2+) channels (VSCCs) in several cell types. The purpose of these studies was to characterize the interaction between endogenous CB(1) receptors and VSCCs in cerebellar granule neurons (CGN). Ca(2+) transients were evoked by KCl-induced depolarization and imaged using fura-2. The CB(1) receptor agonists CP55940, Win 55212-2 and N-arachidonylethanolamine (anandamide) produced concentration-related decreases in peak amplitude of the Ca(2+) response and total Ca(2+) influx. Pre-treatment of CGN with pertussis toxin abolished agonist-mediated inhibition. The inhibitory effect of Win 55212-2 on Ca(2+) influx was additive with inhibition produced by omega-agatoxin IVA and nifedipine but not with omega-conotoxin GVIA, indicating that N-type VSCCs are the primary effector. Paradoxically, the CB(1) receptor antagonist, SR141716, also inhibited KCl-induced Ca(2+) influx into CGN in a concentration-related manner. SR141716 inhibition was pertussis toxin-insensitive and was not additive with the inhibition produced by Win 55212-2. Confocal imaging of CGN in primary culture demonstrate a high density of CB(1) receptor expression on CGN plasma membranes, including the neuritic processes. These data demonstrate that the CB(1) receptor is highly expressed by CGN and agonists serve as potent and efficacious inhibitory modulators of Ca(2+) influx through N-type VSCC.
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Affiliation(s)
- M I Nogueron
- Department of Pharmacology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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33
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Sugiura T, Yoshinaga N, Waku K. Rapid generation of 2-arachidonoylglycerol, an endogenous cannabinoid receptor ligand, in rat brain after decapitation. Neurosci Lett 2001; 297:175-8. [PMID: 11137756 DOI: 10.1016/s0304-3940(00)01691-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rat brain, frozen in liquid nitrogen immediately after decapitation, contains a substantial amount of 2-arachidonoylglycerol (0.34 nmol/g tissue), an endogenous cannabinoid receptor ligand. The level of 2-arachidonoylglycerol in the brain was rapidly augmented after decapitation, the peak being noted 30 s after decapitation (1.54 nmol/g tissue). Noticeably, there are two phases during the increase in the levels of 2-arachidonoylglycerol: a rapid transient increase and a subsequent gradual sustained increase, suggesting that at least two separate mechanisms are involved in the generation of 2-arachidonoylglycerol in the decapitated brain. Gradual sustained formation was also observed for other monoacylglycerols, (e.g. 2-palmitoylglycerol plus 2-oleoylglycerol and 2-cis-vaccenoylglycerol). Thus, it is important to minimize post-mortem changes to estimate the exact tissue levels of 2-arachidonoylglycerol as well as other monoacylglycerols in the brain.
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Affiliation(s)
- T Sugiura
- Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Tsukui-gun, 199-0195, Kanagawa, Japan.
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34
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Abstract
2-Arachidonoylglycerol (2-AG) is a unique molecular species of monoacylglycerol isolated from rat brain and canine gut as an endogenous cannabinoid receptor ligand (Sugiura, T., Kondo, S., Sukagawa, A., Nakane, S., Shinoda, A., Itoh, K., Yamashita, A., Waku, K., 1995. 2-Arachidonoylglycerol: a possible endogenous cannabinoid receptor ligand in brain. Biochem. Biophys. Res. Commun. 215, 89-97; Mechoulam, R., Ben-Shabat, S., Hanus, L., Ligumsky, M., Kaminski, N. E., Schatz, A.R., Gopher, A., Almog, S., Martin, B.R., Compton, D.R., Pertwee, R.G., Giffin, G., Bayewitch, M., Brag, J., Vogel, Z., 1995. Identification of an endogenous 2-monoglyceride, present in canine gut, that binds to cannabinoid receptors. Biochem. Pharmacol. 50, 83-90). 2-AG binds to the cannabinoid receptors (CB1 and CB2) and exhibits a variety of cannabimimetic activities in vitro and in vivo. Recently, we found that 2-AG induces Ca(2+) transients in NG108-15 cells, which express the CB1 receptor, and in HL-60 cells, which express the CB2 receptor, through a cannabinoid receptor- and Gi/Go-dependent mechanism. Based on the results of structure-activity relationship experiments, we concluded that 2-AG but not anandamide is the natural ligand for both the CB1 and the CB2 receptors and both receptors are primarily 2-AG receptors. Evidences are gradually accumulating that 2-AG is a physiologically essential molecule, although further detailed studies appear to be necessary to determine relative importance of 2-AG and anandamide in various animal tissues. In this review, we described mainly our previous and current experimental results, as well as those of others, concerning the tissue levels, bioactions and metabolism of 2-AG.
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Affiliation(s)
- T Sugiura
- Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Tsukui-gun, 199-0195, Kanagawa, Japan.
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35
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Abstract
Anandamide (arachidonylethanolamide) and 2-arachidonoylglycerol mediate many of their actions via either CB(1) or CB(2) cannabinoid receptor subtypes. These agonist-receptor interactions result in activation of G proteins, particularly those of the G(i/o) family. Signal transduction pathways that are regulated by these G proteins include inhibition of adenylyl cyclase, regulation of ion currents (inhibition of voltage-gated L, N and P/Q Ca(2+)-currents; activation of K(+) currents); activation of focal adhesion kinase (FAK), mitogen activated protein kinase (MAPK) and induction of immediate early genes; and stimulation of nitric oxide synthase (NOS). Other effects of anandamide and/or 2-arachidonoylglycerol that are not mediated via cannabinoid receptors include inhibition of L-type Ca(2+) channels, stimulation of VR(1) vanilloid receptors, transient changes in intracellular Ca(2+), and disruption of gap junction function. Cardiovascular regulation by anandamide appears to occur by a variety of receptor-mediated and non-receptor-mediated mechanisms. This review will describe and evaluate each of these signal transduction pathways and mechanisms.
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Affiliation(s)
- A C Howlett
- Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, 1402 South Grand Blvd, St. Louis, MO 63104, USA.
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36
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Stefano GB, Bilfinger TV, Rialas CM, Deutsch DG. 2-arachidonyl-glycerol stimulates nitric oxide release from human immune and vascular tissues and invertebrate immunocytes by cannabinoid receptor 1. Pharmacol Res 2000; 42:317-22. [PMID: 10987990 DOI: 10.1006/phrs.2000.0702] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The pharmacological physiological effects of the endogenous cannabinomimetic (endocannabinoid) anandamide have been well characterized. Another endocannabinoid, 2-arachidonoyl-glycerol (2-AG), has been less-widely studied. 2-AG occurs in vertebrate and invertebrate tissues and binds to both cannabinoid receptors (CB1 and CB2). In the current study, 2-AG was found to cause human monocytes and immunocytes from Mytilus edulis to become round and immobile, which may correlate with decreased production of cytokines and adhesion molecules, i.e. an immunosuppressive response. In addition, exposure of these cells to 2-AG results in nitric oxide (NO) release, which is blocked by the nitric oxide synthase inhibitor, l-NAME and a CB1 antagonist, but not by a CB2 antagonist. The results obtained in the human vascular system were similar to those obtained in immune cells. Treatment of human saphenous veins and atria with 2-AG stimulated basal NO release, which was antagonized by l-NAME and a CB1 antagonist. Taken together these results indicate that 2-AG exerts immune and vascular actions similar to those observed with anandamide.
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Affiliation(s)
- G B Stefano
- Multidisciplinary Center for the Study of Aging, Neuroscience Research Institute, State University of New York, College at Old Westbury, Old Westbury, NY 11568, USA.
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Mechoulam R, Hanus L, Fride E. Towards cannabinoid drugs--revisited. PROGRESS IN MEDICINAL CHEMISTRY 2000; 35:199-243. [PMID: 10795402 DOI: 10.1016/s0079-6468(08)70037-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- R Mechoulam
- Brettler Medical Research Center, Faculty of Medicine, Hebrew University of Jerusalem, Ein Kerem, Israel
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38
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Sugiura T, Yoshinaga N, Kondo S, Waku K, Ishima Y. Generation of 2-arachidonoylglycerol, an endogenous cannabinoid receptor ligand, in picrotoxinin-administered rat brain. Biochem Biophys Res Commun 2000; 271:654-8. [PMID: 10814517 DOI: 10.1006/bbrc.2000.2686] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The levels of 2-arachidonoylglycerol, an endogenous cannabinoid receptor ligand, and other molecular species of monoacylglycerols in rat brain were examined. In this study, we sacrificed the animals in liquid nitrogen to minimize postmortem changes. We found that rat brain contains 0.23 nmol/g tissue of 2-arachidonoylglycerol, which accounts for 10.5% of the total monoacylglycerol present in this tissue. We next investigated the level of 2-arachidonoylglycerol after in vivo stimulation with picrotoxinin. We found that the level of 2-arachidonoylglycerol was elevated markedly in picrotoxinin-administered rat brain (4- to 6-fold over the control level). Changes in the levels of other molecular species were relatively small or negligible. Several cannabimimetic molecules as well as Delta(9)-tetrahydrocannabinol are known to depress neurotransmission and to exert anticonvulsant activities; endogenous 2-arachidonoylglycerol produced during neural excitation may play a regulatory role in calming the enhanced synaptic transmission.
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Affiliation(s)
- T Sugiura
- Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa, 199-0195, Japan
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39
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Schaaf O, Dettner K. Polyunsaturated monoglycerides and a pregnadiene in defensive glands of the water beetle Agabus affinis. Lipids 2000; 35:543-50. [PMID: 10907789 DOI: 10.1007/s11745-000-554-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
In addition to the C21 steroid 15alpha-hydroxypregna-4,6-dien-3,20-dione, four 1- or 2-acylated polyunsaturated monoglycerides, 1- or 2-(cis-5,8,11,14-eicosatetraenoyl)-glycerol and 1- or 2-(cis-5,8,11,14,17-eicosapentaenoyl)glycerol were identified as constituents of the prothoracic defensive gland secretion of the dytiscid beetle Agabus affinis by gas chromatography-mass spectrometry of trimethylsilylated gland extracts. In a feeding assay with minnows, synthetic samples of the two 2-acylated monoglycerides showed only a weak activity as a feeding deterrent. For that reason, other possible functions of the monoglycerides are discussed, such as roles as emulsifiers of cannabimimetics.
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Affiliation(s)
- O Schaaf
- University of Bayreuth, Department of Animal Ecology II, Germany
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40
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Hillard CJ. Biochemistry and pharmacology of the endocannabinoids arachidonylethanolamide and 2-arachidonylglycerol. Prostaglandins Other Lipid Mediat 2000; 61:3-18. [PMID: 10785538 DOI: 10.1016/s0090-6980(00)00051-4] [Citation(s) in RCA: 190] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The purpose of this review is to discuss the cellular synthesis and inactivation of two putative endogenous ligands of the cannabinoid receptor, N-arachidonylethanolamine (AEA) and 2-arachidonylglycerol (2-AG). Both ligands are synthesized by neurons and brain tissue in response to increased intracellular calcium concentrations. Both ligands are substrates for fatty acid amide hydrolase (FAAH). Both AEA and 2-AG bind to the neuronal form of the cannabinoid receptor (CB1). AEA binds the receptor with moderate affinity and has the characteristics of a partial agonist, whereas, 2-AG binds with low affinity but exhibits full efficacy. Two possible physiological roles of the endocannabinoids and the CB1 receptor are discussed: the regulation of gestation and the regulation of gastrointestinal motility.
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Affiliation(s)
- C J Hillard
- Department of Pharmacology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, USA.
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41
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Di Marzo V, Bisogno T, De Petrocellis L, Melck D, Orlando P, Wagner JA, Kunos G. Biosynthesis and inactivation of the endocannabinoid 2-arachidonoylglycerol in circulating and tumoral macrophages. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 264:258-67. [PMID: 10447696 DOI: 10.1046/j.1432-1327.1999.00631.x] [Citation(s) in RCA: 243] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The stimulus-induced biosynthesis of the endocannabinoid 2-arachidonoylglycerol (2-AG) in intact mouse J774 macrophages and the inactivation of 2-AG by the same cells or by rat circulating macrophages was studied. By using gas chromatography-mass spectrometry, we found that ionomycin (5 microM) and lipopolysaccharide (LPS, 200 microg x mL-1) cause a 24-fold and 2.5-fold stimulation of 2-AG levels in J774 cells, respectively, thus providing unprecedented evidence that this cannabimimetic metabolite can be synthesized by macrophages. In J774 cells, LPS also induced a 7.8-fold increase of the levels of the other endocannabinoid, anandamide, and, in rat circulating macrophages, an almost twofold increase of 2-AG levels. Extracellular [3H]2-AG was cleared from the medium of intact J774 macrophages (t1/2 = 19-28 min) and esterified to phospholipids, diacylglycerols and triglycerides or hydrolyzed to [3H]arachidonic acid and glycerol. These catabolic processes were attenuated differentially by various enzyme inhibitors. Rat circulating macrophages were shown to contain enzymatic activities for the hydrolysis of 2-AG, including: (a) fatty acid amide hydrolase (FAAH), the enzyme responsible for anandamide breakdown and previously shown to catalyse also 2-AG hydrolysis, and (b) a 2-AG hydrolase activity different from FAAH and down-regulated by LPS. High levels of FAAH mRNA were found in circulating macrophages but not platelets, which, however, contain a 2-AG hydrolase. Both platelets and macrophages were shown to express the mRNA for the CB1 cannabinoid receptor. A macrophage 2-AG hydrolase with apparent Km = 110 microM and Vmax = 7.9 nmol x min-1 x (mg protein)-1 was partially characterized in J774 cells and found to exhibit an optimal pH of 6-7 and little or no sensitivity to typical FAAH inhibitors. These findings demonstrate for the first time that macrophages participate in the homeostasis of the hypotensive and immunomodulatory endocannabinoid 2-AG through metabolic mechanisms that are subject to regulation.
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Affiliation(s)
- V Di Marzo
- Istituto per la Chimica di Molecole di Interesse Biologico, CNR, Napoli, Italy
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42
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Hansen HS, Moesgaard B, Hansen HH, Schousboe A, Petersen G. Formation of N-acyl-phosphatidylethanolamine and N-acylethanolamine (including anandamide) during glutamate-induced neurotoxicity. Lipids 1999; 34 Suppl:S327-30. [PMID: 10419193 DOI: 10.1007/bf02562333] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
N-Acyl-phosphatidylethanolamine (NAPE) is present in very small amounts in mammalian tissues (less than 0.1% of total phospholipids). However, NAPE as well as its degradation product, N-acylethanolamine (NAE), can be formed in certain neuronal tissues in response to increased [Ca2+]i. A high [Ca2+]i will activate the NAPE-forming N-acyltransferase using the sn-1 acyl group of a donor phospholipid as substrate in the transfer reaction. This membrane-bound enzyme seems to have no substrate specificity with respect to transfer of acyl groups; thus the fatty acids in the N-acyl group of NAPE are mainly 16:0 and 18:1, corresponding to the fatty acids in the sn-1 acyl group of the donor phospholipids. The NAPE-hydrolyzing phospholipase D also seems not to be acyl-group specific. In mouse neocortical neurons in primary culture, formation of NAPE and NAE is stimulated by glutamate via activation of the N-methyl-D-aspartate-receptor. Both NAPE and, to a lesser extent, NAE accumulate in a linear fashion for many hours while at the same time the neurons are dying. Likewise, in neurons prelabeled with 14C-arachidonic acid, 14C-arachidonic acid-labeled NAPE, and anandamide (= N-arachidonoylethanolamine) are accumulating. The formation of NAPE and NAE may represent a cytoprotective response in relation to various forms of neurotoxicity.
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Affiliation(s)
- H S Hansen
- Department of Pharmacology, The Royal Danish School of Pharmacy, Copenhagen.
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43
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Fimiani C, Mattocks D, Cavani F, Salzet M, Deutsch DG, Pryor S, Bilfinger TV, Stefano GB. Morphine and anandamide stimulate intracellular calcium transients in human arterial endothelial cells: coupling to nitric oxide release. Cell Signal 1999; 11:189-93. [PMID: 10353693 DOI: 10.1016/s0898-6568(98)00060-6] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Both morphine and anandamide significantly stimulated cultured endothelial intracellular calcium level increases in a concentration-dependent manner in cells pre-loaded with fura 2/AM. Morphine is more potent than anandamide (approximately 275 vs. 135 nM [Ca]i), and the [Ca]i for both ligands was blocked by prior exposure of the cells to their respective receptor antagonist, i.e., naloxone and SR 171416A. Various opioid peptides did not exhibit this ability, indicating a morphine-mu3-mediated process. In comparing the sequence of events concerning morphine's and anandamide's action in stimulating both [Ca]i and nitric oxide production in endothelial cells, we found that the first event precedes the second by 40+/-8 sec. The opiate and cannabinoid stimulation of [Ca]i was attenuated in cells leeched of calcium, strongly suggesting that intracellular calcium levels regulate cNOS activity.
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Affiliation(s)
- C Fimiani
- Multidisciplinary Center for the Study of Aging, Neuroscience Research Institute, State University of New York at Old Westbury, 11568-0210, USA
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44
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Goparaju SK, Ueda N, Taniguchi K, Yamamoto S. Enzymes of porcine brain hydrolyzing 2-arachidonoylglycerol, an endogenous ligand of cannabinoid receptors. Biochem Pharmacol 1999; 57:417-23. [PMID: 9933030 DOI: 10.1016/s0006-2952(98)00314-1] [Citation(s) in RCA: 175] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Anandamide and 2-arachidonoylglycerol (2-AG) are two endogenous ligands for the cannabinoid receptors, and their cannabimimetic activities are lost when they are hydrolyzed enzymatically. Cytosol and particulate fractions of porcine brain exhibited a high 2-AG hydrolyzing activity of 100 nmol/min/mg protein. Most of the activity could be attributed to a monoacylglycerol lipase-like enzyme that did not hydrolyze anandamide. It was separated by hydroxyapatite chromatography from anandamide amidohydrolase, which is also capable of hydrolyzing 2-AG as well as anandamide. Thus, porcine brain has at least two enzymes capable of hydrolyzing 2-AG. The 2-AG hydrolase activities of both the cytosolic and particulate enzymes were irreversibly and time-dependently inhibited by methyl arachidonyl fluorophosphonate with IC50 values as low as 2-3 nM.
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Affiliation(s)
- S K Goparaju
- Department of Biochemistry, Tokushima University, School of Medicine, Japan
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45
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Sugiura T, Kodaka T, Nakane S, Miyashita T, Kondo S, Suhara Y, Takayama H, Waku K, Seki C, Baba N, Ishima Y. Evidence that the cannabinoid CB1 receptor is a 2-arachidonoylglycerol receptor. Structure-activity relationship of 2-arachidonoylglycerol, ether-linked analogues, and related compounds. J Biol Chem 1999; 274:2794-801. [PMID: 9915812 DOI: 10.1074/jbc.274.5.2794] [Citation(s) in RCA: 232] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
An endogenous cannabimimetic molecule, 2-arachidonoylglycerol, induces a rapid, transient increase in intracellular free Ca2+ concentrations in NG108-15 cells through a cannabinoid CB1 receptor-dependent mechanism. We examined the activities of 24 relevant compounds (2-arachidonoylglycerol, its structural analogues, and several synthetic cannabinoids). We found that 2-arachidonoylglycerol is the most potent compound examined so far: its activity was detectable from as low as 0.3 nM, and the maximal response induced by 2-arachidonoylglycerol exceeded the responses induced by others. Activities of HU-210 and CP55940, potent cannabinoid receptor agonists, were also detectable from as low as 0.3 nM, whereas the maximal responses induced by these compounds were low compared with 2-arachidonoylglycerol. Anandamide was also found to act as a partial agonist in this assay system. We confirmed that free arachidonic acid failed to elicit a response. Furthermore, we found that a metabolically stable ether-linked analogue of 2-arachidonoylglycerol possesses appreciable agonistic activity, although its activity was apparently lower than that of 2-arachidonoylglycerol. We also confirmed that pretreating cells with various cannabinoid receptor agonists nullified the response induced by 2-arachidonoylglycerol, whereas pretreating cells with other neurotransmitters or neuromodulators did not affect the response. These results strongly suggested that the cannabinoid CB1 receptor is originally a 2-arachidonoylglycerol receptor, and 2-arachidonoylglycerol is the intrinsic physiological ligand for the cannabinoid CB1 receptor.
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Affiliation(s)
- T Sugiura
- Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa 199-0195, Japan
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46
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Abstract
In 1992 the discovery of the first endogenous ligand of cannabinoid receptors, anandamide, provided conclusive support to the hypothesis that an "endogenous cannabinoid regulatory system" exists in mammalian nervous tissue. Anandamide (N-arachidonoyl-ethanolamine) was the first of a series of long-chain fatty acid derivatives, including two other polyunsaturated N-acylethanolamines and 2-arachidonoyl-glycerol, found to exert cannabimimetic properties in either central or peripheral tissues. Here we review the current knowledge on the biochemical bases of the formation and inactivation of endogenous cannabinoid ligands as well as of their interaction with cannabinoid receptor subtypes.
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Affiliation(s)
- V Di Marzo
- Istituto per la Chimica di Molecole di Interesse Biologico, CNR, Naples, Italy
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47
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Di Marzo V, Melck D, Bisogno T, De Petrocellis L. Endocannabinoids: endogenous cannabinoid receptor ligands with neuromodulatory action. Trends Neurosci 1998; 21:521-8. [PMID: 9881850 DOI: 10.1016/s0166-2236(98)01283-1] [Citation(s) in RCA: 481] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The existence of an endogenous cannabinoid system was demonstrated conclusively with the discovery of endogenous brain constituents capable of activating the cannabinoid receptors functionally. These compounds are synthesized by neuronal cells and inactivated through re-uptake and enzymatic hydrolysis by both neurons and astrocytes. In analogy with the endorphins they can be referred to as endocannabinoids. Apart from the identification of their metabolic pathways, research carried out in the past six years has focused on the possible cellular and molecular targets for the actions of endocannabinoids. These studies have confirmed a similarity between the endocannabinoids and the psychoactive substance in marijuana, delta9(-)-tetrahydrocannabinol, and have suggested a role for endocannabinoids in the modulation of neurotransmitter action and release.
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Affiliation(s)
- V Di Marzo
- Istituto per la Chimica di Molecole di Interesse Biologico, CNR, Napoli, Italy
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48
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Di Marzo V. 'Endocannabinoids' and other fatty acid derivatives with cannabimimetic properties: biochemistry and possible physiopathological relevance. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1392:153-75. [PMID: 9630590 DOI: 10.1016/s0005-2760(98)00042-3] [Citation(s) in RCA: 249] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The only endogenous substances isolated and characterised so far that are capable of mimicking the pharmacological actions of the active principle of marijuana, (-)-Delta9-tetrahydrocannabinol, are amides and esters of fatty acids. Some of these compounds, like anandamide (N-arachidonoylethanolamine) and 2-arachidonoylglycerol, act as true 'endogenous cannabinoids' by binding and functionally activating one or both cannabinoid receptor subtypes present on nervous and peripheral cell membranes. The metabolic pathways and molecular mode of actions of these metabolites, as well as their possible implication in physiopathological responses, are reviewed here.
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Affiliation(s)
- V Di Marzo
- Istituto per la Chimica di Molecole di Interesse Biologico1, C.N.R., Via Toiano 6, 80072 Arco Felice, Naples, Italy.
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49
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Kondo S, Kondo H, Nakane S, Kodaka T, Tokumura A, Waku K, Sugiura T. 2-Arachidonoylglycerol, an endogenous cannabinoid receptor agonist: identification as one of the major species of monoacylglycerols in various rat tissues, and evidence for its generation through CA2+-dependent and -independent mechanisms. FEBS Lett 1998; 429:152-6. [PMID: 9650580 DOI: 10.1016/s0014-5793(98)00581-x] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The molecular species compositions of monoacylglycerols obtained from various rat tissues were examined by reverse-phase high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) analyses. We confirmed that 2-arachidonoylglycerol, an endogenous cannabinoid receptor agonist, is one of the most abundant molecular species of monoacylglycerols in the brain. Substantial amounts of 2-arachidonoylglycerol were also found in the liver, spleen, lung and kidney, but the levels were considerably lower than that in the brain. We found that a small amount of 2-arachidonoylglycerol was generated in a brain homogenate during incubation in the absence of Ca2+. Importantly, the generation of 2-arachidonoylglycerol was markedly augmented in the presence of Ca2+, suggesting that Ca2+ plays a key role in regulation of the generation of 2-arachidonoylglycerol in this tissue.
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Affiliation(s)
- S Kondo
- Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa, Japan
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Sugiura T, Kodaka T, Nakane S, Kishimoto S, Kondo S, Waku K. Detection of an endogenous cannabimimetic molecule, 2-arachidonoylglycerol, and cannabinoid CB1 receptor mRNA in human vascular cells: is 2-arachidonoylglycerol a possible vasomodulator? Biochem Biophys Res Commun 1998; 243:838-43. [PMID: 9501013 DOI: 10.1006/bbrc.1998.8187] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human vascular endothelial cells were found to generate and release 2-arachidonoylglycerol, an endogenous cannabinoid receptor ligand, upon stimulation with thrombin or A23187. We confirmed that vascular smooth muscle cells as well as endothelial cells possess cannabinoid CB1 receptor mRNA. 2-Arachidonoylglycerol, generated in vascular tissues, may play an important role in modulating vascular tone through acting on the cannabinoid CB1 receptor expressed on vascular smooth muscle cells, endothelial cells as well as peripheral nerve terminals.
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MESH Headings
- Aorta
- Arachidonic Acid/metabolism
- Arachidonic Acids
- Calcimycin/pharmacology
- Cells, Cultured
- Diglycerides/metabolism
- Endocannabinoids
- Endothelium, Vascular/chemistry
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Glycerides/analysis
- Glycerides/metabolism
- Glycerides/pharmacology
- Humans
- Kinetics
- Muscle, Smooth, Vascular/chemistry
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- RNA, Messenger/analysis
- Receptors, Cannabinoid
- Receptors, Drug/drug effects
- Receptors, Drug/genetics
- Receptors, Drug/physiology
- Thrombin/pharmacology
- Tritium
- Umbilical Veins
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Affiliation(s)
- T Sugiura
- Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa, Japan
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