101
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Coopman K, Smith LD, Wright KL, Ward SG. Temporal variation in CB2R levels following T lymphocyte activation: Evidence that cannabinoids modulate CXCL12-induced chemotaxis. Int Immunopharmacol 2007; 7:360-71. [PMID: 17276894 DOI: 10.1016/j.intimp.2006.11.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Revised: 11/20/2006] [Accepted: 11/21/2006] [Indexed: 12/22/2022]
Abstract
Cannabinoids have long been proposed to affect the immune system, especially as one of the cannabinoid receptors, the cannabinoid receptor-2 (CB(2)R) has been found almost exclusively on immune cells. Here, using human in vitro activated peripheral blood-derived T lymphocytes we investigated the long-term changes in cannabinoid receptor protein expression following cellular activation and the effects of cannabinoids on migration. We report that resting T lymphocytes do not detectably express either the cannabinoid receptor-1 (CB(1)R) or CB(2)R at the protein level. However, CB(2)R protein expression is upregulated in a biphasic manner in T lymphocytes following activation by superantigen. The cannabinoids 2-AG and JWH-133 were found to elicit activation of downstream biochemical effectors (as assessed by the phosphorylation of the ERK1/2 MAP kinases). Neither 2-AG nor JWH-133 induced chemotaxis in day 5 activated T lymphocytes, when receptor expression was at its highest. Interestingly, both 2-AG and JWH-133 inhibited CXCL12-induced chemotaxis, suggesting a modulatory role for cannabinoids in activated T lymphocytes.
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Affiliation(s)
- Karen Coopman
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA2 7AY, U.K
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102
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Bifulco M, Grimaldi C, Gazzerro P, Pisanti S, Santoro A. Rimonabant: Just an Antiobesity Drug? Current Evidence on Its Pleiotropic Effects. Mol Pharmacol 2007; 71:1445-56. [PMID: 17327463 DOI: 10.1124/mol.106.033118] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The advent of the highly selective cannabinoid receptor (CB1) antagonist, rimonabant (SR141716; Acomplia) can revolutionize the ability of the clinicians to manage obesity. Large-scale clinical trials have demonstrated that rimonabant therapy can reduce obesity. Although, the precise mechanisms of action of rimonabant have to be further dissected, it is emerging, from both preclinical and clinical research, that not only is rimonabant an antiobesity drug, but also its pleiotropic functions affect a broad range of diseases, from obesity-related comorbidities to drug dependence and cancer. Here we review recent data from the literature and discuss the full pharmacological potential of this drug.
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Affiliation(s)
- Maurizio Bifulco
- Department of Pharmaceutical Sciences, University of Salerno, Fisciano, Salerno, Italy.
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103
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Gorojankina T, Grébert D, Salesse R, Tanfin Z, Caillol M. Study of orexins signal transduction pathways in rat olfactory mucosa and in olfactory sensory neurons-derived cell line Odora: multiple orexin signalling pathways. ACTA ACUST UNITED AC 2007; 141:73-85. [PMID: 17292491 DOI: 10.1016/j.regpep.2006.12.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Revised: 12/04/2006] [Accepted: 12/21/2006] [Indexed: 10/23/2022]
Abstract
Orexins A and B (OxA and OxB) are multifunctional neuropeptides implicated in the regulation of energy metabolism, wakefulness but also in a broad range of motivated behaviours. They signal through two G-protein-coupled receptors: orexin receptor 1 and 2 (Ox1R and Ox2R). The orexins and their receptors are present at all levels of the rat olfactory system: epithelium, bulb, piriform cortex but their signalling mechanisms remain unknown. We have studied orexins signal transduction pathways in the rat olfactory mucosa (OM) and in the Odora cell line derived from olfactory sensory neurons and heterologously expressing Ox1R or Ox2R. We have demonstrated by western blot and RT-PCR that multiple components of adenylyl cyclase (AC) and phospholipase C (PLC) signalling pathways were identical in OM and Odora cells. OxA and OxB induced a weak increase in IP3 in OM; they induced a significant rise in cAMP and IP3 in Odora transfected cells, suggesting the activation of AC and PLC pathways. Both OxA and OxB induced intracellular calcium elevation and transient activation of MAP kinases (ERK42/44) in Odora/Ox1R and Odora/Ox2R cells. These results suggest the existence of multiple orexins signalling pathways in Odora cells and probably in OM, corresponding to different possible roles of these peptides.
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Affiliation(s)
- Tatiana Gorojankina
- Unité de Neurobiologie de l'Olfaction et de la Prise Alimentaire, UMR1197 - INRA - Université Paris 11, Equipe Récepteurs et Communication Chimique, CRJ, Domaine de Vilvert, 78352 Jouy-en-Josas Cedex, France
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104
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Ellis J, Pediani JD, Canals M, Milasta S, Milligan G. Orexin-1 receptor-cannabinoid CB1 receptor heterodimerization results in both ligand-dependent and -independent coordinated alterations of receptor localization and function. J Biol Chem 2006; 281:38812-24. [PMID: 17015451 DOI: 10.1074/jbc.m602494200] [Citation(s) in RCA: 183] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Following inducible expression in HEK293 cells, the human orexin-1 receptor was targeted to the cell surface but became internalized following exposure to the peptide agonist orexin A. By contrast, constitutive expression of the human cannabinoid CB1 receptor resulted in a predominantly punctate, intracellular distribution pattern consistent with spontaneous, agonist-independent internalization. Expression of the orexin-1 receptor in the presence of the CB1 receptor resulted in both receptors displaying the spontaneous internalization phenotype. Single cell fluorescence resonance energy transfer imaging indicated the two receptors were present as heterodimers/oligomers in intracellular vesicles. Addition of the CB1 receptor antagonist SR-141716A to cells expressing only the CB1 receptor resulted in re-localization of the receptor to the cell surface. Although SR-141716A has no significant affinity for the orexin-1 receptor, in cells co-expressing the CB1 receptor, the orexin-1 receptor was also re-localized to the cell surface by treatment with SR-141716A. Treatment of cells co-expressing the orexin-1 and CB1 receptors with the orexin-1 receptor antagonist SB-674042 also resulted in re-localization of both receptors to the cell surface. Treatment with SR-141716A resulted in decreased potency of orexin A to activate the mitogen-activated protein kinases ERK1/2 only in cells co-expressing the two receptors. Treatment with SB-674042 also reduced the potency of a CB1 receptor agonist to phosphorylate ERK1/2 only when the two receptors were co-expressed. These studies introduce an entirely novel pharmacological paradigm, whereby ligands modulate the function of receptors for which they have no significant inherent affinity by acting as regulators of receptor heterodimers.
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MESH Headings
- Base Sequence
- Cell Line
- DNA Primers
- Dimerization
- Humans
- Ligands
- Orexin Receptors
- Pyrrolidines/pharmacology
- Receptor, Cannabinoid, CB1/chemistry
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB1/physiology
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/metabolism
- Receptors, G-Protein-Coupled/physiology
- Receptors, Neuropeptide/antagonists & inhibitors
- Receptors, Neuropeptide/chemistry
- Receptors, Neuropeptide/metabolism
- Receptors, Neuropeptide/physiology
- Thiazoles/pharmacology
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Affiliation(s)
- James Ellis
- Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
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105
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Pacher P, Bátkai S, Kunos G. The endocannabinoid system as an emerging target of pharmacotherapy. Pharmacol Rev 2006; 58:389-462. [PMID: 16968947 PMCID: PMC2241751 DOI: 10.1124/pr.58.3.2] [Citation(s) in RCA: 1473] [Impact Index Per Article: 81.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The recent identification of cannabinoid receptors and their endogenous lipid ligands has triggered an exponential growth of studies exploring the endocannabinoid system and its regulatory functions in health and disease. Such studies have been greatly facilitated by the introduction of selective cannabinoid receptor antagonists and inhibitors of endocannabinoid metabolism and transport, as well as mice deficient in cannabinoid receptors or the endocannabinoid-degrading enzyme fatty acid amidohydrolase. In the past decade, the endocannabinoid system has been implicated in a growing number of physiological functions, both in the central and peripheral nervous systems and in peripheral organs. More importantly, modulating the activity of the endocannabinoid system turned out to hold therapeutic promise in a wide range of disparate diseases and pathological conditions, ranging from mood and anxiety disorders, movement disorders such as Parkinson's and Huntington's disease, neuropathic pain, multiple sclerosis and spinal cord injury, to cancer, atherosclerosis, myocardial infarction, stroke, hypertension, glaucoma, obesity/metabolic syndrome, and osteoporosis, to name just a few. An impediment to the development of cannabinoid medications has been the socially unacceptable psychoactive properties of plant-derived or synthetic agonists, mediated by CB(1) receptors. However, this problem does not arise when the therapeutic aim is achieved by treatment with a CB(1) receptor antagonist, such as in obesity, and may also be absent when the action of endocannabinoids is enhanced indirectly through blocking their metabolism or transport. The use of selective CB(2) receptor agonists, which lack psychoactive properties, could represent another promising avenue for certain conditions. The abuse potential of plant-derived cannabinoids may also be limited through the use of preparations with controlled composition and the careful selection of dose and route of administration. The growing number of preclinical studies and clinical trials with compounds that modulate the endocannabinoid system will probably result in novel therapeutic approaches in a number of diseases for which current treatments do not fully address the patients' need. Here, we provide a comprehensive overview on the current state of knowledge of the endocannabinoid system as a target of pharmacotherapy.
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Affiliation(s)
- Pál Pacher
- Laboratory of Physiological Studies, National Institute of Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Room 2S-24, Bethesda, MD 20892-9413, USA
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106
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Pagotto U, Cervino C, Vicennati V, Marsicano G, Lutz B, Pasquali R. How many sites of action for endocannabinoids to control energy metabolism? Int J Obes (Lond) 2006; 30 Suppl 1:S39-43. [PMID: 16570104 DOI: 10.1038/sj.ijo.0803277] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The promising results obtained by clinical trials using Rimonabant to tackle visceral obesity and related disorders recently promoted a remarkable impulse to carry out detailed investigations into the mechanisms of action of endocannabinoids in regulating food intake and energy metabolism. The endocannabinoid system has been known for many years to play an important role in the modulation of the neuronal pathways mediating the rewarding properties of food. However, in the last few years, with the advanced understanding of the crucial role of the hypothalamic neuronal network in the regulation of appetite, several studies have also directed attention to the orexigenic role of the endocannabinoid system, substantiating the well known appetite stimulating properties of derivatives of Cannabis sativa. Furthermore, the last 2 years have seen a number of relevant publications emphasizing the role of endocannabinoids as significant players in various peripheral metabolic processes. To date, the roles of the endocannabinoid system in influencing energy metabolism have proved to be more complex than was formerly believed. However, the diverse ability to modulate both central and peripheral processes highlights the pivotal involvement of the endocannabinoid system in the control of metabolic processes. This review describes the roles of endocannabinoids and the cannabinoid type 1 receptor (CB1) in the control of energy balance.
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Affiliation(s)
- U Pagotto
- Department of Internal Medicine and Gastroenterology, Endocrinology Unit, Center for Applied Biomedical Research (C.R.B.A.), S. Orsola-Malpighi General Hospital, Bologna, Italy.
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107
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Milligan G. G-protein-coupled receptor heterodimers: pharmacology, function and relevance to drug discovery. Drug Discov Today 2006; 11:541-9. [PMID: 16713906 DOI: 10.1016/j.drudis.2006.04.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Revised: 03/08/2006] [Accepted: 04/04/2006] [Indexed: 11/16/2022]
Abstract
The growing recognition that members of the rhodopsin-like family A G-protein-coupled receptors (GPCRs) exist and function as dimers or higher-order oligomers, and that GPCR hetero-dimers and -oligomers are present in physiological tissues, offers novel opportunities for drug discovery. Differential pharmacology, function and regulation of GPCR hetero-dimers and -oligomers suggest means to selectively target GPCRs in different tissues and hint that the mechanism of function of several pharmacological agents might be different in vivo than anticipated from simple ligand-screening programmes that rely on heterologous expression of a single GPCR.
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Affiliation(s)
- Graeme Milligan
- Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, Scotland, UK.
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108
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Tonstad S. Rimonabant: a cannabinoid receptor blocker for the treatment of metabolic and cardiovascular risk factors. Nutr Metab Cardiovasc Dis 2006; 16:156-162. [PMID: 16487916 DOI: 10.1016/j.numecd.2005.10.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Accepted: 10/26/2005] [Indexed: 10/25/2022]
Abstract
AIMS The endocannabinoid system modulates synaptic neurotransmission centrally and peripherally and is involved in the brain pathways concerned with addiction, central regulation of body weight and adipose tissue function. The system is overactivated in animal models of obesity and nicotine use. This review discusses the role of rimonabant, a cannabinoid receptor 1 blocker, which has undergone Phase III clinical testing, in the treatment of obesity and tobacco dependence. DATA SYNTHESIS Results of Phase III clinical trials have shown that rimonabant has promising efficacy in the treatment of obesity, dyslipidaemia and diabetes associated with obesity, in preventing weight gain following smoking cessation, and possibly in smoking cessation. No critical problems with the tolerance and safety of the compound have appeared in studies to date. CONCLUSION Rimonabant may prove to be a useful aid in the treatment of the most widespread cardiometabolic risk factors.
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Affiliation(s)
- Serena Tonstad
- Department of Preventive Cardiology, Ullevål University Hospital, N-0407 Oslo, Norway.
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109
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Pagotto U, Marsicano G, Cota D, Lutz B, Pasquali R. The emerging role of the endocannabinoid system in endocrine regulation and energy balance. Endocr Rev 2006; 27:73-100. [PMID: 16306385 DOI: 10.1210/er.2005-0009] [Citation(s) in RCA: 586] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
During the last few years, the endocannabinoid system has emerged as a highly relevant topic in the scientific community. Many different regulatory actions have been attributed to endocannabinoids, and their involvement in several pathophysiological conditions is under intense scrutiny. Cannabinoid receptors, named CB1 receptor and CB2 receptor, first discovered as the molecular targets of the psychotropic component of the plant Cannabis sativa, participate in the physiological modulation of many central and peripheral functions. CB2 receptor is mainly expressed in immune cells, whereas CB1 receptor is the most abundant G protein-coupled receptor expressed in the brain. CB1 receptor is expressed in the hypothalamus and the pituitary gland, and its activation is known to modulate all the endocrine hypothalamic-peripheral endocrine axes. An increasing amount of data highlights the role of the system in the stress response by influencing the hypothalamic-pituitary-adrenal axis and in the control of reproduction by modifying gonadotropin release, fertility, and sexual behavior. The ability of the endocannabinoid system to control appetite, food intake, and energy balance has recently received great attention, particularly in the light of the different modes of action underlying these functions. The endocannabinoid system modulates rewarding properties of food by acting at specific mesolimbic areas in the brain. In the hypothalamus, CB1 receptor and endocannabinoids are integrated components of the networks controlling appetite and food intake. Interestingly, the endocannabinoid system was recently shown to control metabolic functions by acting on peripheral tissues, such as adipocytes, hepatocytes, the gastrointestinal tract, and, possibly, skeletal muscle. The relevance of the system is further strenghtened by the notion that drugs interfering with the activity of the endocannabinoid system are considered as promising candidates for the treatment of various diseases, including obesity.
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Affiliation(s)
- Uberto Pagotto
- Endocrinology Unit, Department of Internal Medicine and Gastroenterology, Sant' Orsola-Malpighi Hospital, Bologna, Italy, and Department of Physiological Chemistry, Johannes Gutenberg-University Mainz, Germany.
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110
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Magga J, Bart G, Oker-Blom C, Kukkonen JP, Akerman KEO, Näsman J. Agonist potency differentiates G protein activation and Ca2+ signalling by the orexin receptor type 1. Biochem Pharmacol 2006; 71:827-36. [PMID: 16430869 DOI: 10.1016/j.bcp.2005.12.021] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Revised: 12/09/2005] [Accepted: 12/19/2005] [Indexed: 10/25/2022]
Abstract
The G protein coupling characteristics of a flag epitope-tagged orexin receptor type 1 (OX1R) was investigated in HEK293 cells. Immunoprecipitation of the OX1R and immunoblotting revealed interactions with Gq/G11 proteins as well as with Gs and Gi proteins. Stimulation with orexin-A did not affect the ability of the OX1R to coprecipitate Gq/G11 proteins, but it robustly elevated the intracellular concentration of Ca2+, [Ca2+]i. No changes in cAMP levels could be detected upon receptor stimulation. To get further insight into the functional correlation of G protein activation and Ca2+ signalling, we used baculovirus transduction to express chimeric G proteins, containing the Galphas protein backbone with various Galpha donor sequences (Galphas/x) at the N and C termini, and measured cAMP as functional output. The Galphas/x chimeric proteins with Galpha11(Galphaq) and Galpha16 structure in the C terminus were stimulated by the OX1R. Concentration-response curves with Galphas/16 revealed an agonist potency correlation between G protein activation and the elevation of [Ca2+]i via discharge of intracellular Ca2+ stores, a feature also recognized for the muscarinic M3 receptor. However, in contrast to the M3 receptor, the OX1R elevated [Ca2+]i via influx from extracellular space at about 30-fold lower agonist concentration. The results suggest that the OX1R is linked to influx of Ca2+ through a signal pathway independent of Gq/G11 protein activation.
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Affiliation(s)
- Johanna Magga
- A.I. Virtanen Institute for Molecular Sciences, University of Kuopio, FIN-70211 Kuopio, Finland
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111
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Abstract
The discovery of cannabinoid receptors, together with the development of selective cannabinoid receptor antagonists, has encouraged a resurgence of cannabinoid pharmacology. With the identification of endogenous agonists, such as anandamide, scientists have sought to uncover the biological role of endocannabinoid systems; initially guided by the long-established actions of cannabis and exogenous cannabinoids such as delta9-tetrahydrocannabinol (THC). In particular, considerable research has examined endocannabinoid involvement in appetite, eating behaviour and body weight regulation. It is now confirmed that endocannabinoids, acting at brain CB1 cannabinoid receptors, stimulate appetite and ingestive behaviours, partly through interactions with more established orexigenic and anorexigenic signals. Key structures such as the nucleus accumbens and hypothalamic nuclei are sensitive sites for the hyperphagic actions of these substances, and endocannabinoid activity in these regions varies in relation to nutritional status and feeding expression. Behavioural studies indicate that endocannabinoids increase eating motivation by enhancing the incentive salience and hedonic evaluation of ingesta. Moreover, there is strong evidence of an endocannabinoid role in energy metabolism and fuel storage. Recent developments point to potential clinical benefits of cannabinoid receptor antagonists in the management of obesity, and of agonists in the treatment of other disorders of eating and body weight regulation.
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Affiliation(s)
- T C Kirkham
- School of Psychology, University of Liverpool, Liverpool, England.
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112
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Cota D, Tschöp MH, Horvath TL, Levine AS. Cannabinoids, opioids and eating behavior: the molecular face of hedonism? ACTA ACUST UNITED AC 2005; 51:85-107. [PMID: 16364446 DOI: 10.1016/j.brainresrev.2005.10.004] [Citation(s) in RCA: 266] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2005] [Revised: 10/13/2005] [Accepted: 10/17/2005] [Indexed: 01/07/2023]
Abstract
Obesity represents nowadays one of the most devastating health threats. Published reports even project a decline in life expectancy of US citizens due to the rapidly increasing prevalence of obesity. This alarming increase is intimately linked with recent changes of environment and lifestyle in western countries. In this context, the rewarding or even addictive properties of popular food may represent one of the most serious obstacles to overcome for an effective anti-obesity therapy. Therefore, in addition to molecular networks controlling energy homeostasis, now researchers are starting to define central nervous mechanisms governing hedonic and addictive components of food intake. A recently emerging body of data suggests that the endogenous cannabinoid and opioid systems both represent key circuits responding to the rewarding value of food. This review focuses on the role of these two systems for the homeostatic and hedonic aspects of eating behavior and includes their anatomical and functional interactions. Independent from the degree to which eating can be considered an addiction, cannabinoid and opioid receptor antagonists are promising anti-obesity drugs, since they are targeting both hedonic and homeostatic components of energy balance control.
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Affiliation(s)
- Daniela Cota
- Obesity Research Center, Department of Psychiatry, University of Cincinnati-Genome Research Institute, 2170 E Galbraith Road, Cincinnati, OH 45237, USA.
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113
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Verty ANA, McGregor IS, Mallet PE. Paraventricular hypothalamic CB1 cannabinoid receptors are involved in the feeding stimulatory effects of Δ9-tetrahydrocannabinol. Neuropharmacology 2005; 49:1101-9. [PMID: 16098995 DOI: 10.1016/j.neuropharm.2005.03.025] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2004] [Revised: 03/09/2005] [Accepted: 03/11/2005] [Indexed: 11/22/2022]
Abstract
BACKGROUND/AIMS The paraventricular nucleus of the hypothalamus (PVN) is the target of converging orexigenic and anorexigenic pathways originating from various hypothalamic sites and is, therefore, considered to be the chief site mediating hypothalamic regulation of energy homeostasis. Although a large body of evidence suggests that central CB(1) cannabinoid receptors mediate food intake, it is not clear whether PVN CB(1) receptors are involved in the control of feeding behaviour. The present study therefore examined the effects of intra-PVN administration of Delta(9)-tetrahydrocannabinol (THC) and the cannabinoid receptor antagonist SR 141716 on feeding. METHODS After being habituated to the test environment and injection procedure, sated rats were injected with SR 141716 (0.03-3.0 microg, Experiment 1) alone or in combination with THC (5.0 microg, Experiment 2) into the PVN. Food intake and locomotor activity then were recorded for 120 min. RESULTS Intra-PVN administration of THC produced a significant increase in food intake that was attenuated by SR 141716. Administration of SR 141716 alone did not affect feeding. Locomotor activity was not significantly affected by any drug treatments, suggesting that effects on feeding were not due to a non-specific reduction in motivated behaviour. These findings suggest an important role for PVN cannabinoid signalling in mediating THC-induced feeding behaviour. These results also demonstrate that the blockade of PVN CB(1) receptors alone is insufficient to reduce baseline feeding behaviour under these conditions.
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Affiliation(s)
- Aaron N A Verty
- School of Psychology, University of New England, Armidale, NSW 2351, Australia
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114
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Ammoun S, Lindholm D, Wootz H, Akerman KEO, Kukkonen JP. G-protein-coupled OX1 orexin/hcrtr-1 hypocretin receptors induce caspase-dependent and -independent cell death through p38 mitogen-/stress-activated protein kinase. J Biol Chem 2005; 281:834-42. [PMID: 16282319 DOI: 10.1074/jbc.m508603200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have investigated the signaling of OX(1) receptors to cell death using Chinese hamster ovary cells as a model system. OX(1) receptor stimulation with orexin-A caused a delayed cell death independently of cytosolic Ca(2+) elevation. The classical mitogen-activated protein kinase (MAPK) pathways, ERK and p38, were strongly activated by orexin-A. p38 was essential for induction of cell death, whereas the ERK pathway appeared protective. A pathway often implicated in the p38-mediated cell death, activation of p53, did not mediate the cell death, as there was no stabilization of p53 or increase in p53-dependent transcriptional activity, and dominant-negative p53 constructs did not inhibit cell demise. Under basal conditions, orexin-A-induced cell death was associated with compact chromatin condensation and it required de novo gene transcription and protein synthesis, the classical hallmarks of programmed (apoptotic) cell death. However, though the pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-(O-methyl)fluoromethyl ketone (Z-VAD-fmk) fully inhibited the caspase activity, it did not rescue the cells from orexin-A-induced death. In the presence of Z-VAD-fmk, orexin-A-induced cell death was still dependent on p38 and de novo protein synthesis, but it no longer required gene transcription. Thus, caspase inhibition causes activation of alternative, gene transcription-independent death pathway. In summary, the present study points out mechanisms for orexin receptor-mediated cell death and adds to our general understanding of the role of G-protein-coupled receptor signaling in cell death by suggesting a pathway from G-protein-coupled receptors to cell death via p38 mitogen-/stress-activated protein kinase independent of p53 and caspase activation.
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Affiliation(s)
- Sylwia Ammoun
- Department of Neuroscience, Unit of Physiology, Uppsala University, Sweden
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115
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116
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Jbilo O, Ravinet-Trillou C, Arnone M, Buisson I, Bribes E, Péleraux A, Pénarier G, Soubrié P, Le Fur G, Galiègue S, Casellas P. The CB1 receptor antagonist rimonabant reverses the diet-induced obesity phenotype through the regulation of lipolysis and energy balance. FASEB J 2005; 19:1567-9. [PMID: 16009704 DOI: 10.1096/fj.04-3177fje] [Citation(s) in RCA: 256] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We investigated the molecular events involved in the long-lasting reduction of adipose mass by the selective CB1 antagonist, SR141716. Its effects were assessed at the transcriptional level both in white (WAT) and brown (BAT) adipose tissues in a diet-induced obesity model in mice. Our data clearly indicated that SR141716 reversed the phenotype of obese adipocytes at both macroscopic and genomic levels. First, oral treatment with SR141716 at 10 mg/kg/d for 40 days induced a robust reduction of obesity, as shown by the 50% decrease in adipose mass together with a major restoration of white adipocyte morphology similar to lean animals. Second, we found that the major alterations in gene expression levels induced by obesity in WAT and BAT were mostly reversed in SR141716-treated obese mice. Importantly, the transcriptional patterns of treated obese mice were similar to those obtained in the CB1 receptor knockout mice fed a high-fat regimen and which are resistant to obesity, supporting a CB1 receptor-mediated process. Functional analysis of these modulations indicated that the reduction of adipose mass by the molecule resulted from an enhanced lipolysis through the induction of enzymes of the beta-oxidation and TCA cycle, increased energy expenditure, mainly through futile cycling (calcium and substrate), and a tight regulation of glucose homeostasis. These changes accompanied a significant cellular remodeling and contributed to a reduction of the obesity-related inflammatory status. In addition to a transient reduction of food consumption, increases of both fatty acid oxidation and energy expenditure induced by the molecule summate leading to a sustained weight loss. Altogether, these data strongly indicate that the endocannabinoid system has a major role in the regulation of energy metabolism.
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Affiliation(s)
- Omar Jbilo
- Oncology Research Department, Sanofi-Synthelabo Recherche, Montpellier, France
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117
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Di Marzo V, Matias I. Endocannabinoid control of food intake and energy balance. Nat Neurosci 2005; 8:585-9. [PMID: 15856067 DOI: 10.1038/nn1457] [Citation(s) in RCA: 525] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2005] [Accepted: 02/21/2005] [Indexed: 01/27/2023]
Abstract
Marijuana and its major psychotropic component, Delta(9)-tetrahydrocannabinol, stimulate appetite and increase body weight in wasting syndromes, suggesting that the CB(1) cannabinoid receptor and its endogenous ligands, the endocannabinoids, are involved in controlling energy balance. The endocannabinoid system controls food intake via both central and peripheral mechanisms, and it may also stimulate lipogenesis and fat accumulation. Here we discuss the multifaceted regulation of energy homeostasis by endocannabinoids, together with its applications to the treatment of eating disorders and metabolic syndromes.
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Affiliation(s)
- Vincenzo Di Marzo
- Endocannabinoid Research Group, Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Via Campi Flegrei 34, 80078, Pozzuoli, Naples, Italy.
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118
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Liu YL, Connoley IP, Wilson CA, Stock MJ. Effects of the cannabinoid CB1 receptor antagonist SR141716 on oxygen consumption and soleus muscle glucose uptake in Lep(ob)/Lep(ob) mice. Int J Obes (Lond) 2005; 29:183-7. [PMID: 15558076 DOI: 10.1038/sj.ijo.0802847] [Citation(s) in RCA: 239] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To investigate the effect of SR141716, a selective CB1 receptor antagonist, on energy expenditure and on glucose uptake in isolated soleus muscle of Lep(ob)/Lep(ob) mice. DESIGN Female Lep(ob)/Lep(ob) mice (8-10 weeks old) were treated with SR141716 (10 mg/kg, i.p. once daily) or vehicle for 7 days. MEASUREMENTS Oxygen consumption, daily food and water intake, body weight and glucose uptake in isolated soleus muscle. RESULTS SR141716 (10 mg/kg, i.p. once daily) resulted in a significant reduction of daily food intake (P<0.01) and body weight (P<0.05) 5 days after daily treatment. Body weight continued to be lower for the rest of the treatment period (P<0.05). There was no significant difference in body weight between the pair-fed and vehicle-treated animals. A 7-day treatment with SR141716 (10 mg/kg, i.p. once daily) caused 37% increase in basal oxygen consumption compared to that of vehicle-treated (90 min mean; P<0.01), and a significant 68% increase in glucose uptake in isolated soleus muscle preparations. CONCLUSION It is concluded that SR141716 has a direct effect on energy expenditure suggesting that the antiobesity effect of SR141716 is due to activation of thermogenesis in addition to the initial hypophagia. The increase in soleus muscle glucose uptake with SR141716 treatment may contribute to the improved glycaemia seen in the previous studies.
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Affiliation(s)
- Y L Liu
- Department of Physiology, Basic Medical Sciences, St George's Hospital Medical School, Tooting, London SW17 0RE, UK.
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119
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Julien B, Grenard P, Teixeira-Clerc F, Van Nhieu JT, Li L, Karsak M, Zimmer A, Mallat A, Lotersztajn S. Antifibrogenic role of the cannabinoid receptor CB2 in the liver. Gastroenterology 2005; 128:742-55. [PMID: 15765409 DOI: 10.1053/j.gastro.2004.12.050] [Citation(s) in RCA: 347] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND & AIMS Hepatic myofibroblasts are central for the development of liver fibrosis associated with chronic liver diseases, and blocking their accumulation may prevent fibrogenesis. Cannabinoids are the active components of marijuana and act via 2 G-protein-coupled receptors, CB1 and CB2. Here, we investigated whether liver fibrogenic cells are a target of cannabinoids. METHODS CB2 receptors were characterized in biopsy specimens of normal human liver and active cirrhosis by immunohistochemistry, and in cultures of hepatic stellate cells and hepatic myofibroblasts by reverse-transcription polymerase chain reaction (RT-PCR), immunocytochemistry, and GTPgammaS assays. Functional studies were performed in cultured hepatic myofibroblasts and activated hepatic stellate cells. Carbon tetrachloride-induced liver fibrosis was studied in mice invalidated for CB2 receptors. RESULTS In liver biopsy specimens from patients with active cirrhosis of various etiologies, CB2 receptors were expressed in nonparenchymal cells located within and at the edge of fibrous septa in smooth muscle alpha-actin-positive cells. In contrast, CB2 receptors were not detected in normal human liver. CB2 receptors were also detected in cultured hepatic myofibroblasts and in activated hepatic stellate cells. Their activation triggered potent antifibrogenic effects, namely, growth inhibition and apoptosis. Growth inhibition involved cyclooxygenase-2, and apoptosis resulted from oxidative stress. Finally, mice invalidated for CB2 receptors developed enhanced liver fibrosis following chronic carbon tetrachloride treatment as compared with wild-type mice. CONCLUSIONS These data constitute the first demonstration that CB2 receptors are highly up-regulated in the cirrhotic liver, predominantly in hepatic fibrogenic cells. Moreover, this study also highlights the antifibrogenic role of CB2 receptors during chronic liver injury.
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120
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Kearn CS, Blake-Palmer K, Daniel E, Mackie K, Glass M. Concurrent Stimulation of Cannabinoid CB1 and Dopamine D2 Receptors Enhances Heterodimer Formation: A Mechanism for Receptor Cross-Talk? Mol Pharmacol 2005; 67:1697-704. [PMID: 15710746 DOI: 10.1124/mol.104.006882] [Citation(s) in RCA: 248] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Dopamine and endogenous cannabinoids display complex interactions in the basal ganglia. One possible level of interaction is between CB1 cannabinoid and D2 dopamine receptors. Here, we demonstrate that a regulated association of CB1 and D2 receptors profoundly alters CB1 signaling. This provides the first evidence that CB1/D2 receptor complexes exist, are dynamic, and are agonist-regulated with highest complex levels detected when both receptors are stimulated with subsaturating concentrations of agonist. The consequence of this interaction is a differential preference for signaling through a "nonpreferred" G protein. In this case, D2 receptor activation, simultaneously with CB1 receptor stimulation, results in the receptor complex coupling to G alpha s protein in preference to the expected G alpha i/o proteins. The result of this interaction is an increase in the second messenger cAMP, reversing an initial synergistic inhibition of adenylyl cyclase activity seen at subthreshold concentrations of cannabinoid agonist. Additionally, a pertussis toxin insensitive component in the activation of extracellular signal-regulated kinase (ERK) 1/2 kinases by the cannabinoid agonist CP 55,940 [(1R,3R,4R)-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-4-(3-hydroxypropyl)cyclohexan-1-ol] is revealed in cells stably expressing both CB1 and D2 receptors. Thus, concurrent receptor stimulation promotes a heterooligomeric receptor complex and an apparent shift of CB1 signaling from a pertussis toxin-sensitive inhibition to a partly pertussis toxin-insensitive stimulation of adenylyl cyclase and ERK 1/2 phosphorylation.
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121
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Cani PD, Montoya ML, Neyrinck AM, Delzenne NM, Lambert DM. Potential modulation of plasma ghrelin and glucagon-like peptide-1 by anorexigenic cannabinoid compounds, SR141716A (rimonabant) and oleoylethanolamide. Br J Nutr 2004; 92:757-61. [PMID: 15533263 DOI: 10.1079/bjn20041256] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The CB1 cannabinoid receptor antagonist, N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide (rimonabant; SR141716A), and oleoylethanolamide (OEA) are known to reduce food consumption, by, at least partially, a peripheral regulation of feeding. The effects of systemic SR141716A or OEA (5 mg/kg) administrations on food consumption in 24 h food-deprived and fed rats were investigated. In fasted rats, SR141716A and OEA produced an inhibition in food intake measurable the first 20 min following injection. The increase in ghrelin levels observed in the vehicle-injected rats was abolished in animals receiving OEA and significantly reduced with SR141716A. Neither OEA nor SR141716A modified glucagon-like peptide-1 (7-36) amide portal levels 20 min after the administration. In fed rats, plasma ghrelin levels of SR141716A- and OEA-treated rats were 35% lower as compared with those of the vehicle-injected rats. These results show an influence of cannabinoid agents on circulating ghrelin levels and suggest that their short-term action on appetite seems to be in accordance with the control of secretion of gastrointestinal orexigenic peptides, mainly expressed in the upper part of the gastrointestinal tract.
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Affiliation(s)
- Patrice D Cani
- Unité de Pharmacocinétique, Métabolisme, Nutrition et Toxicologie, Ecole de Pharmacie, Université catholique de Louvain, Brussels, Belgium
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122
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CB2, a paradigm for a novel class of “onco-GPCRs”? Blood 2004. [DOI: 10.1182/blood-2004-05-1799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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123
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Hirasawa M, Schwab Y, Natah S, Hillard CJ, Mackie K, Sharkey KA, Pittman QJ. Dendritically released transmitters cooperate via autocrine and retrograde actions to inhibit afferent excitation in rat brain. J Physiol 2004; 559:611-24. [PMID: 15254151 PMCID: PMC1665137 DOI: 10.1113/jphysiol.2004.066159] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Oxytocin is released from supraoptic magnocellular neurones and is thought to act at presynaptic receptors to inhibit transmitter release. We now show that this effect is mediated by endocannabinoids, but that oxytocin nonetheless plays an important role in endocannabinoid signalling. WIN55,212-2, a cannabinoid receptor agonist, mimicked the action of oxytocin and occluded oxytocin-induced presynaptic inhibition. The cannabinoid action is at the presynaptic terminal as shown by alteration in paired pulse ratio, a reduction in miniature EPSC frequency and immunohistochemical localization of CB1 receptors on presynaptic terminals. AM251, a CB1 receptor antagonist, blocked both the WIN55,212-2 and the oxytocin-induced presynaptic inhibition of EPSCs. Depolarization of postsynaptic magnocellular neurones (which contain fatty acid amide hydrolase, a cannabinoid catabolic enzyme) caused a transient inhibition of EPSCs that could be blocked by both the AM251 and Manning compound, an oxytocin/vasopressin receptor antagonist. This indicates that somatodendritic peptide release and action on previously identified autoreceptors facilitates the release of endocannabinoids that act as mediators of presynaptic inhibition.
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Affiliation(s)
- Michiru Hirasawa
- Calgary Brain Institute, Neuroscience Research Group, Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada T2N 4N1
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124
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Burdyga G, Lal S, Varro A, Dimaline R, Thompson DG, Dockray GJ. Expression of cannabinoid CB1 receptors by vagal afferent neurons is inhibited by cholecystokinin. J Neurosci 2004; 24:2708-15. [PMID: 15028763 PMCID: PMC6729520 DOI: 10.1523/jneurosci.5404-03.2004] [Citation(s) in RCA: 214] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Both inhibitory (satiety) and stimulatory (orexigenic) factors from the gastrointestinal tract regulate food intake. In the case of the satiety hormone cholecystokinin (CCK), these effects are mediated via vagal afferent neurons. We now report that vagal afferent neurons expressing the CCK-1 receptor also express cannabinoid CB1 receptors. Retrograde tracing established that these neurons project to the stomach and duodenum. The expression of CB1 receptors determined by RT-PCR, immunohistochemistry and in situ hybridization in rat nodose ganglia was increased by withdrawal of food for > or =12 hr. After refeeding of fasted rats there was a rapid loss of CB1 receptor expression identified by immunohistochemistry and in situ hybridization. These effects were blocked by administration of the CCK-1 receptor antagonist lorglumide and mimicked by administration of CCK to fasted rats. Because CCK is a satiety factor that acts via the vagus nerve and CB1 agonists stimulate food intake, the data suggest a new mechanism modulating the effect on food intake of satiety signals from the gastrointestinal tract.
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MESH Headings
- Animals
- Cholecystokinin/pharmacology
- Cholecystokinin/physiology
- Culture Techniques
- Duodenum/innervation
- Food Deprivation/physiology
- Hormone Antagonists/pharmacology
- Humans
- Immunohistochemistry
- In Situ Hybridization
- Male
- Nerve Crush
- Neurons, Afferent/metabolism
- Nodose Ganglion/cytology
- Nodose Ganglion/metabolism
- Proglumide/analogs & derivatives
- Proglumide/pharmacology
- Rats
- Rats, Wistar
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB2/biosynthesis
- Receptor, Cannabinoid, CB2/genetics
- Receptor, Cholecystokinin A/antagonists & inhibitors
- Receptor, Cholecystokinin A/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Satiety Response/physiology
- Stomach/innervation
- Vagus Nerve/cytology
- Vagus Nerve/metabolism
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Affiliation(s)
- Galina Burdyga
- Physiological Laboratory, University of Liverpool, Liverpool L69 3BX, United Kingdom
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125
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Avraham Y, Ben-Shushan D, Breuer A, Zolotarev O, Okon A, Fink N, Katz V, Berry EM. Very low doses of Δ8-THC increase food consumption and alter neurotransmitter levels following weight loss. Pharmacol Biochem Behav 2004; 77:675-84. [PMID: 15099912 DOI: 10.1016/j.pbb.2004.01.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2003] [Revised: 08/24/2003] [Accepted: 01/19/2004] [Indexed: 11/22/2022]
Abstract
We have investigated the effect of 0.001 mg/kg delta(8)-tetrahydrocannabinol (THC) on food consumption, cognitive function, and neurotransmitters in mice. Sabra mice were treated with vehicle, THC, or THC+CB1 antagonist (SR141716A). The mice were fed for 2.5 h a day for 9 or 50 days. In the 9-day schedule, THC-treated mice showed a 16% increase in food intake compared with controls (P<.001). This effect was reversed by the antagonist (P<.01). In the long-term schedule a 22% increase in intake (P<.05) was recorded. During the course of the 9- and 50-day experimental protocol, all mice lost about 20% and 10% of their original weight, respectively, to reach approximately the same weights, which were not significantly different between the different treatment groups. In addition, THC caused an increase in activity (P<.05). Cognitive function showed a tendency to improve (P<.06) in the THC-treated mice, which was reversed by the antagonist for Days 4 and 5 of the maze (P<.01, and P<.05, respectively). Significant decreases in dopamine and serotonin (5-HT) levels were found both in the hypothalamus (P<.01) and the hippocampus (P<.01, P<.05), respectively, while norepinephrine (NE) levels showed tendency to increase in both the hypothalamus and hippocampus. Delta(8)-THC increased food intake significantly more (P<.05) than did delta(9)-THC, while performance and activity were similar. Thus, delta(8)-THC (0.001 mg/kg) caused increased food consumption and tendency to improve cognitive function, without cannabimimetic side effects. Hence, a low dose of THC might be a potential therapeutic agent in the treatment of weight disorders.
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Affiliation(s)
- Yosefa Avraham
- Department of Human Nutrition and Metabolism, Hebrew University-Hadassah Medical School, POB 12272, Jerusalem 91120, Israel.
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126
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Massi P, Vaccani A, Rubino T, Parolaro D. Cannabinoids and opioids share cAMP pathway in rat splenocytes. J Neuroimmunol 2004; 145:46-54. [PMID: 14644030 DOI: 10.1016/j.jneuroim.2003.09.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
In the present work we investigated on rat splenocytes long-term interactions between opioid and cannabinoid drugs in terms of a common regulation of cAMP intracellular pathway. Both morphine and the synthetic cannabinoid compound CP-55,940 inhibited in a concentration-dependent manner the intracellular cAMP level in splenocytes stimulated by forskolin. The in vitro combination of submaximal concentrations of the two drugs did not yield any additive effect on the inhibition induced by the two drugs. In splenocytes taken from rats chronically treated with CP-55,940 (0.2 mg/kg i.p., twice a day for 4.5 days) or morphine (5 mg/kg s.c., twice a day for 6.5 days) and in vitro exposed to either CP-55,940 or morphine, it was found a desensitisation and cross-desensitisation to the inhibitory effects on cAMP production induced by the two drugs. Binding experiments on the cannabinoid receptors level in spleen coronal sections after in vivo chronic administration of morphine, revealed that there was no changes in the binding of [H3]-CP-55,940. Thus, these results strengthen the hypothesis of cAMP as part of the common intracellular pathway shared by opiates and cannabinoids at immune cell level.
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Affiliation(s)
- Paola Massi
- Department of Pharmacology, Chemotherapy and Toxicology, University of Milan, Via Vanvitelli 32, 20129 Milan, Italy.
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127
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Abstract
Obesity has been described as a global epidemic. Its increasing prevalence is matched by growing costs, not only to the health of the individual, but also to the medical services required to treat a range of obesity-related diseases. In most instances, obesity is a product of progressively less energetic lifestyles and the over-consumption of readily available, palatable, and highly caloric foods. Past decades have seen massive investment in the search for effective anti-obesity therapies, so far with limited success. An important part of the process of developing new pharmacologic treatments for obesity lies in improving our understanding of the psychologic and physiologic processes that govern appetite and bodyweight regulation. Recent discoveries concerning the endogenous cannabinoids are beginning to give greater insight into these processes. Current research indicates that endocannabinoids may be key to the appetitive and consummatory aspects of eating motivation, possibly mediating the craving for and enjoyment of the most desired, most fattening foods. Additionally, endocannabinoids appear to modulate central and peripheral processes associated with fat and glucose metabolism. Selective cannabinoid receptor antagonists have been shown to suppress the motivation to eat, and preferentially reduce the consumption of palatable, energy-dense foods. Additionally, these agents act to reduce adiposity through metabolic mechanisms that are independent of changes in food intake. Given the current state of evidence, we conclude that the endocannabinoids represent an exciting target for new anti-obesity therapies.
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Affiliation(s)
- Tim C Kirkham
- School of Psychology, The University of Liverpool, Liverpool L69 7ZA, UK.
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128
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Bakker RA, Casarosa P, Timmerman H, Smit MJ, Leurs R. Constitutively active Gq/11-coupled receptors enable signaling by co-expressed G(i/o)-coupled receptors. J Biol Chem 2003; 279:5152-61. [PMID: 14610092 DOI: 10.1074/jbc.m309200200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Co-expression of guanine nucleotide-binding regulatory (G) protein-coupled receptors (GPCRs), such as the G(i/o)-coupled human 5-hydroxytryptamine receptor 1B (5-HT(1B)R), with the G(q/11)-coupled human histamine 1 receptor (H1R) results in an overall increase in agonist-independent signaling, which can be augmented by 5-HT(1B)R agonists and inhibited by a selective inverse 5-HT(1B)R agonist. Interestingly, inverse H1R agonists inhibit constitutively H1R-mediated as well as 5-HT(1B)R agonist-induced signaling in cells co-expressing both receptors. This phenomenon is not solely characteristic of 5-HT(1B)R; it is also evident with muscarinic M2 and adenosine A1 receptors and is mimicked by mastoparan-7, an activator of G(i/o) proteins, or by over-expression of Gbetagamma subunits. Likewise, expression of the G(q/11)-coupled human cytomegalovirus (HCMV)-encoded chemokine receptor US28 unmasks a functional coupling of G(i/o)-coupled CCR1 receptors that is mediated via the constitutive activity of receptor US28. Consequently, constitutively active G(q/11)-coupled receptors, such as the H1R and HCMV-encoded chemokine receptor US28, constitute a regulatory switch for signal transduction by G(i/o)-coupled receptors, which may have profound implications in understanding the role of both constitutive GPCR activity and GPCR cross-talk in physiology as well as in the observed pathophysiology upon HCMV infection.
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MESH Headings
- Animals
- COS Cells
- DNA/chemistry
- DNA, Complementary/metabolism
- Enzyme Activation
- Enzyme-Linked Immunosorbent Assay
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/physiology
- GTP-Binding Protein alpha Subunits, Gq-G11/metabolism
- Genes, Reporter
- Humans
- Inositol Phosphates/metabolism
- Intercellular Signaling Peptides and Proteins
- Ligands
- Models, Biological
- Peptides
- Protein Binding
- Protein Structure, Tertiary
- Receptor, Adenosine A1/metabolism
- Receptor, Muscarinic M2/metabolism
- Receptor, Serotonin, 5-HT1B/chemistry
- Receptor, Serotonin, 5-HT1B/metabolism
- Receptors, G-Protein-Coupled/metabolism
- Signal Transduction
- Transcription, Genetic
- Wasp Venoms/metabolism
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Affiliation(s)
- Remko A Bakker
- Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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129
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Karteris E, Randeva HS. Orexin Receptors and G-Protein Coupling: Evidence for Another “Promiscuous” Seven Transmembrane Domain Receptor. J Pharmacol Sci 2003; 93:126-8. [PMID: 14501163 DOI: 10.1254/jphs.93.126] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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