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Lord MN, Noble EE. Hypothalamic cannabinoid signaling: Consequences for eating behavior. Pharmacol Res Perspect 2024; 12:e1251. [PMID: 39155548 PMCID: PMC11331011 DOI: 10.1002/prp2.1251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 06/27/2024] [Accepted: 07/02/2024] [Indexed: 08/20/2024] Open
Abstract
In parallel to the legalization of cannabis for both medicinal and recreational purposes, cannabinoid use has steadily increased over the last decade in the United States. Cannabinoids, such as tetrahydrocannabinol and anandamide, bind to the central cannabinoid-1 (CB1) receptor to impact several physiological processes relevant for body weight regulation, including appetite and energy expenditure. The hypothalamus integrates peripheral signals related to energy balance, houses several nuclei that orchestrate eating, and expresses the CB1 receptor. Herein we review literature to date concerning cannabinergic action in the hypothalamus with a specific focus on eating behaviors. We highlight hypothalamic areas wherein researchers have focused their attention, including the lateral, arcuate, paraventricular, and ventromedial hypothalamic nuclei, and interactions with the hormone leptin. This review serves as a comprehensive analysis of what is known about cannabinoid signaling in the hypothalamus, highlights gaps in the literature, and suggests future directions.
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Affiliation(s)
- Magen N. Lord
- Department of Nutritional SciencesUniversity of GeorgiaAthensGeorgiaUSA
| | - Emily E. Noble
- Department of Nutritional SciencesUniversity of GeorgiaAthensGeorgiaUSA
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Ronja N, Kölle P. [Obesity in dogs - A review of underlying reasons]. TIERAERZTLICHE PRAXIS AUSGABE KLEINTIERE HEIMTIERE 2021; 49:284-293. [PMID: 34425607 DOI: 10.1055/a-1548-2293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Obesity does not merely represent a human problem but is also recognized as an immense health threat in domestic animals. However, this disease is frequently not recognized by the pet owner. Current studies assume that up to 60 % of domestic dogs are overweight or significantly obese with various reasons existing for this development. Not only the feeding management contributes to the development of obesity but also genetics, age and gender as well as specific primary diseases add to the individual's weight gain. Addtionally, medical treatment and the owner-pet-relationship may increase the risk for obesity. In order to treat obesity in a qualified manner or ideally to prevent this from developing in the first place, a profound knowledge concerning the underlying causes is essential. The present article provides a review of the most important impact factors thus adding to the body of information allowing for the acquisition of such expertise.
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Affiliation(s)
- Nitsch Ronja
- Medizinische Kleintierklinik, Tierärztliche Fakultät der Ludwig-Maximilians-Universität München
| | - Petra Kölle
- Medizinische Kleintierklinik, Tierärztliche Fakultät der Ludwig-Maximilians-Universität München
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D'Addario C, Zaplatic E, Giunti E, Pucci M, Micioni Di Bonaventura MV, Scherma M, Dainese E, Maccarrone M, Nilsson IA, Cifani C, Fadda P. Epigenetic regulation of the cannabinoid receptor CB1 in an activity-based rat model of anorexia nervosa. Int J Eat Disord 2020; 53:432-446. [PMID: 32275093 DOI: 10.1002/eat.23271] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 03/16/2020] [Accepted: 03/16/2020] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Both environmental and genetic factors are known to contribute to the development of anorexia nervosa (AN), but the exact etiology remains poorly understood. Herein, we studied the transcriptional regulation of the endocannabinoid system, an interesting target for body weight maintenance and the control of food intake and energy balance. METHOD We used two well-characterized animal models of AN: (a) the activity-based anorexia (ABA) model in which rats, housed with running wheels and subjected to daily food restriction, show reductions in body weight and increase in physical activity; (b) the genetic anx/anx mouse displaying the core features of AN: low food intake and emaciation. RESULTS Among the evaluated endocannabinoid system components, we observed a selective and significant down-regulation of the gene encoding for the type 1 cannabinoid receptor (Cnr1) in ABA rats' hypothalamus and nucleus accumbens and, in the latter area, a consistent, significant and correlated increase in DNA methylation at the gene promoter. No changes were evident in the anx/anx mice except for a down-regulation of Cnr1, in the prefrontal cortex. DISCUSSION Our findings support a possible role for Cnr1 in the ABA animal model of AN. In particular, its regulation in the nucleus accumbens appears to be triggered by environmental cues due to the consistent epigenetic modulation of the promoter. These data warrant further studies on Cnr1 regulation as a possible target for treatment of AN.
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Affiliation(s)
- Claudio D'Addario
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy.,Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Elizabeta Zaplatic
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy
| | - Elisa Giunti
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, Cagliari, Italy
| | - Mariangela Pucci
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy
| | | | - Maria Scherma
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, Cagliari, Italy
| | - Enrico Dainese
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy
| | - Mauro Maccarrone
- Department of Medicine, Campus Bio-Medico University of Rome, Rome, Italy.,Lipid Neurochemistry Unit, Santa Lucia Foundation IRCCS, Rome, Italy
| | - Ida A Nilsson
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.,Center for Molecular Medicine, Karolinska Hospital, Stockholm, Sweden
| | - Carlo Cifani
- School of Pharmacy, Pharmacology Unit, University of Camerino, Camerino, Italy
| | - Paola Fadda
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, Cagliari, Italy.,CNR Institute of Neuroscience - Cagliari, National Research Council, Cagliari, Italy
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Just add water: cannabinoid discrimination in a water T-maze with FAAH(-/-) and FAAH(+/+) mice. Behav Pharmacol 2017; 27:479-84. [PMID: 27385208 DOI: 10.1097/fbp.0000000000000228] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Incomplete overlap in the discriminative stimulus effects of Δ-tetrahydrocannabinol (THC) and the endocannabinoids, anandamide (AEA) and 2-arachidonoylglycerol has been reported in food-reinforced tasks. The aim of this study was to examine cannabinoid discriminative stimulus effects in a nonappetitive procedure. Adult male mice lacking the gene for AEA's major metabolic enzyme, fatty acid amide hydrolase (FAAH), and FAAH mice were trained to discriminate THC or AEA in a water T-maze, in which the response was swimming to an escape platform on the injection-appropriate side. JZL184, a monoacylglycerol lipase inhibitor, was also tested. FAAH mice showed faster acquisition than FAAH mice. THC and AEA fully substituted, with only minor cross-procedure potency variations. Incomplete substitution of JZL184 was observed in THC-trained FAAH mice in the water-maze task, as contrasted with full substitution in a food-reinforced nose-poke procedure. Stress-induced changes in AEA and/or 2-arachidonoylglycerol concentrations in the brain may have mediated this attenuation. JZL184 also partially substituted in AEA-trained FAAH mice in the water maze, suggesting incomplete overlap in the stimulus effects of AEA and JZL184. Through the use of a novel water-maze procedure, the present study supports the work of previous behavioral pharmacologists in showing the robustness of the discrimination paradigm.
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Simon V, Cota D. MECHANISMS IN ENDOCRINOLOGY: Endocannabinoids and metabolism: past, present and future. Eur J Endocrinol 2017; 176:R309-R324. [PMID: 28246151 DOI: 10.1530/eje-16-1044] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/10/2017] [Accepted: 02/27/2017] [Indexed: 12/14/2022]
Abstract
The endocannabinoid system (ECS), including cannabinoid type 1 and type 2 receptors (CB1R and CB2R), endogenous ligands called endocannabinoids and their related enzymatic machinery, is known to have a role in the regulation of energy balance. Past information generated on the ECS, mainly focused on the involvement of this system in the central nervous system regulation of food intake, while at the same time clinical studies pointed out the therapeutic efficacy of brain penetrant CB1R antagonists like rimonabant for obesity and metabolic disorders. Rimonabant was removed from the market in 2009 and its obituary written due to its psychiatric side effects. However, in the meanwhile a number of investigations had started to highlight the roles of the peripheral ECS in the regulation of metabolism, bringing up new hope that the ECS might still represent target for treatment. Accordingly, peripherally restricted CB1R antagonists or inverse agonists have shown to effectively reduce body weight, adiposity, insulin resistance and dyslipidemia in obese animal models. Very recent investigations have further expanded the possible toolbox for the modulation of the ECS, by demonstrating the existence of endogenous allosteric inhibitors of CB1R, the characterization of the structure of the human CB1R, and the likely involvement of CB2R in metabolic disorders. Here we give an overview of these findings, discussing what the future may hold in the context of strategies targeting the ECS in metabolic disease.
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MESH Headings
- Allosteric Regulation/drug effects
- Animals
- Anti-Obesity Agents/adverse effects
- Anti-Obesity Agents/pharmacology
- Anti-Obesity Agents/therapeutic use
- Cannabinoid Receptor Antagonists/adverse effects
- Cannabinoid Receptor Antagonists/pharmacology
- Cannabinoid Receptor Antagonists/therapeutic use
- Drug Inverse Agonism
- Endocannabinoids/metabolism
- Energy Intake/drug effects
- Energy Metabolism/drug effects
- Humans
- Models, Biological
- Obesity/drug therapy
- Obesity/metabolism
- Receptor, Cannabinoid, CB1/agonists
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB2/agonists
- Receptor, Cannabinoid, CB2/antagonists & inhibitors
- Receptor, Cannabinoid, CB2/metabolism
- Signal Transduction/drug effects
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Affiliation(s)
- Vincent Simon
- INSERM and University of BordeauxNeurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U1215, Bordeaux, France
| | - Daniela Cota
- INSERM and University of BordeauxNeurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U1215, Bordeaux, France
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6
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Argueta DA, DiPatrizio NV. Peripheral endocannabinoid signaling controls hyperphagia in western diet-induced obesity. Physiol Behav 2017; 171:32-39. [PMID: 28065722 DOI: 10.1016/j.physbeh.2016.12.044] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 12/16/2016] [Accepted: 12/20/2016] [Indexed: 01/07/2023]
Abstract
The endocannabinoid system in the brain and periphery plays a major role in controlling food intake and energy balance. We reported that tasting dietary fats was met with increased levels of the endocannabinoids, 2-arachidonoyl-sn-glycerol (2-AG) and anandamide, in the rat upper small intestine, and pharmacological inhibition of this local signaling event dose-dependently blocked sham feeding of fats. We now investigated the contribution of peripheral endocannabinoid signaling in hyperphagia associated with chronic consumption of a western-style diet in mice ([WD] i.e., high fat and sucrose). Feeding patterns were assessed in male C57BL/6Tac mice maintained for 60days on WD or a standard rodent chow (SD), and the role for peripheral endocannabinoid signaling at CB1Rs in controlling food intake was investigated via pharmacological interventions. In addition, levels of the endocannabinoids, 2-AG and anandamide, in the upper small intestine and circulation of mice were analyzed via liquid chromatography coupled to tandem mass spectrometry to evaluate diet-related changes in endocannabinoid signaling and the potential impact on food intake. Mice fed WD for 60days exhibited large increases in body weight, daily caloric intake, average meal size, and rate of feeding when compared to control mice fed SD. Inhibiting peripheral CB1Rs with the peripherally-restricted neutral cannabinoid CB1 receptor antagonist, AM6545 (10mg/kg), significantly reduced intake of WD during a 6h test, but failed to modify intake of SD in mice. AM6545 normalized intake of WD, average meal size, and rate of feeding to levels found in SD control mice. These results suggest that endogenous activity at peripheral CB1Rs in WD mice is critical for driving hyperphagia. In support of this hypothesis, levels of 2-AG and anandamide in both, jejunum mucosa and plasma, of ad-libitum fed WD mice increased when compared to SC mice. Furthermore, expression of genes for primary components of the endocannabinoid system (i.e., cannabinoid receptors, and endocannabinoid biosynthetic and degradative enzymes) was dysregulated in WD mice when compared to SC mice. Our results suggest that hyperphagia associated with WD-induced obesity is driven by enhanced endocannabinoid signaling at peripheral CB1Rs.
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Affiliation(s)
| | - Nicholas V DiPatrizio
- University of California Riverside, Riverside, CA, USA; School of Medicine, Riverside, CA, USA; Division of Biomedical Sciences, Riverside, CA, USA.
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DiPatrizio NV, Piomelli D. The thrifty lipids: endocannabinoids and the neural control of energy conservation. Trends Neurosci 2012; 35:403-11. [PMID: 22622030 DOI: 10.1016/j.tins.2012.04.006] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 04/14/2012] [Accepted: 04/17/2012] [Indexed: 10/28/2022]
Abstract
The 'thrifty gene hypothesis' posits that evolution preferentially selects physiological mechanisms that optimize energy storage to increase survival under alternating conditions of abundance and scarcity of food. Recent experiments suggest that endocannabinoids - a class of lipid-derived mediators that activate cannabinoid receptors in many cells of the body - are key agents of energy conservation. The new evidence indicates that these compounds increase energy intake and decrease energy expenditure by controlling the activity of peripheral and central neural pathways involved in the sensing and hedonic processing of sweet and fatty foods, as well as in the storage of their energy content for future use.
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Affiliation(s)
- Nicholas V DiPatrizio
- Departments of Pharmacology, University of California, Irvine, School of Medicine, Irvine, CA, USA
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8
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Pittman DW, McGinnis MR, Richardson LM, Miller EJ, Alimohamed ML, Baird JP. Multiple processes underlie benzodiazepine-mediated increases in the consumption of accepted and avoided stimuli. Chem Senses 2012; 37:431-44. [PMID: 22248457 DOI: 10.1093/chemse/bjr125] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Hyperphagia is a reported side effect of anxiolytic benzodiazepines such as chlordiazepoxide (CDP). Prior research has focused primarily on the ingestive responses to sweet or solid foods. We examined CDP effects on licking for normally accepted and avoided taste solutions across a range of concentrations. The effect of CDP (10 mg/kg) versus saline on the licking patterns of water-restricted rats for water and 3 concentrations of sucrose, saccharin, NaCl, monosodium glutamate (MSG), citric acid, and quinine (Q-HCl) solutions was evaluated during 1 h tests. CDP increased meal size for all tastants except citric acid. Analysis of licking microstructure revealed 3 dissociable effects of CDP. CDP affected oromotor coordination as indicated by a uniform increase in the modal interlick interval for all stimuli. CDP increased meal size as indicated by shorter pauses during consumption of water, MSG, and weaker saccharin concentrations, and by fewer long interlick intervals (250-2000 ms) for normally avoided tastants. CDP also increased meal size by increasing burst size, burst duration, and the initial rate of licking for most solutions, suggesting increased hedonic taste evaluation. CDP did not affect variables associated with postingestive feedback such as meal duration or number of bursts, and the results also suggest that CDP did not enhance the perceived taste intensity. We hypothesize that the reduction of pause duration is consistent with an increased motivation to sample the stimulus that synergizes with changes in taste-mediated responsiveness to some but not all stimuli to yield increases in the consumption of both normally accepted and avoided taste stimuli.
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Affiliation(s)
- D W Pittman
- Department of Psychology, Wofford College, 429 N. Church Street, Spartanburg, SC 29303, USA.
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Wu Q, Palmiter RD. GABAergic signaling by AgRP neurons prevents anorexia via a melanocortin-independent mechanism. Eur J Pharmacol 2011; 660:21-7. [PMID: 21211531 DOI: 10.1016/j.ejphar.2010.10.110] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 09/30/2010] [Accepted: 10/12/2010] [Indexed: 11/25/2022]
Abstract
The hypothalamic arcuate nucleus contains two anatomically and functionally distinct populations of neurons-the agouti-related peptide (AgRP)- and pro-opiomelanocortin (POMC)-expressing neurons that integrate various nutritional, hormonal, and neuronal signals to regulate food intake and energy expenditure, and thereby help achieve energy homeostasis. AgRP neurons, also co-release neuropeptide Y (NPY) and γ-aminobutyric acid (GABA) to promote feeding and inhibit metabolism through at least three possible mechanisms: (1) suppression of the melanocortin signaling system through competitive binding of AgRP with the melanocortin 4 receptors; (2) NPY-mediated inhibition of post-synaptic neurons that reside in hypothalamic nuclei; (3) GABAergic inhibition of POMC neurons in their post-synaptic targets including the parabrachial nucleus (PBN), a brainstem structure that relays gustatory and visceral sensory information. Acute ablation of AgRP neurons in adult mice by the action of diphtheria toxin (DT) results in precipitous reduction of food intake, and eventually leads to starvation within 6days of DT treatment. Chronic delivery of bretazenil, a GABA(A) receptor partial agonist, into the PBN is sufficient to restore feeding and body weight when AgRP neurons are ablated, whereas chronic blockade of melanocortin 4 receptor signaling is inadequate. This review summarizes the physiological roles of a neural circuitry regulated by AgRP neurons in control of feeding behavior with particular emphasis of the GABA output to the parabrachial nucleus. We also describe a compensatory mechanism that is gradually engaged after ablation of AgRP neurons that allows mice to continue eating without them.
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Affiliation(s)
- Qi Wu
- Howard Hughes Medical Institute and Departments of Biochemistry, University of Washington, Seattle, WA 98195, USA.
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10
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Thomas BF. Neuroanatomical basis for therapeutic applications of cannabinoid receptor 1 antagonists. Drug Dev Res 2009. [DOI: 10.1002/ddr.20333] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Sink KS, Segovia KN, Nunes EJ, Collins LE, Vemuri VK, Thakur G, Makriyannis A, Salamone JD. Intracerebroventricular administration of cannabinoid CB1 receptor antagonists AM251 and AM4113 fails to alter food-reinforced behavior in rats. Psychopharmacology (Berl) 2009; 206:223-32. [PMID: 19588124 PMCID: PMC4425366 DOI: 10.1007/s00213-009-1602-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Accepted: 06/19/2009] [Indexed: 10/20/2022]
Abstract
RATIONALE Drugs that interfere with cannabinoid CB1 transmission suppress food-motivated behaviors and may be useful as appetite suppressants, but there is uncertainty about the locus of action for the feeding-suppression effects of these drugs. OBJECTIVE The present work was conducted to determine if two drugs that interfere with cannabinoid receptor transmission, AM251 and AM4113, have effects on food-reinforced behavior after administration into the lateral ventricle (intracerebroventricular (ICV)). RESULTS Although systemic administration of both drugs can suppress food-reinforced behavior, neither AM251 (40, 80, and 160 microg) nor AM4113 (60, 120, and 240 microg) administered at various times prior to testing produced any suppression of food-reinforced operant responding on a fixed-ratio 5 schedule. Because the modulation of locomotion by drugs that act on CB1 receptors is hypothesized to be a forebrain effect, these drugs also were assessed for their ability to reverse the locomotor suppression produced by the CB1 agonist AM411. ICV administration of either AM251 or AM4113 reversed the locomotor suppression induced by the CB1 agonist AM411 in the same dose range that failed to produce any effects on feeding. CONCLUSIONS This indicates that both AM4113 and AM251, when administered ICV, can interact with forebrain CB1 receptors and are efficacious on forebrain-mediated functions unrelated to feeding. These results suggest that CB1 neutral antagonists or inverse agonists may not be affecting food-reinforced behavior via interactions with forebrain CB1 receptors located in nucleus accumbens or hypothalamus and that lower brainstem or peripheral receptors may be involved.
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Affiliation(s)
- K. S. Sink
- Department of Psychology, University of Connecticut, Storrs, CT 06269-1020, USA,Yerkes National Primate Center and the Center for Behavioral Neuroscience, Emory University, 954 Gatewood Drive, Atlanta, GA 30329, USA
| | - K. N. Segovia
- Department of Psychology, University of Connecticut, Storrs, CT 06269-1020, USA
| | - E. J. Nunes
- Department of Psychology, University of Connecticut, Storrs, CT 06269-1020, USA
| | - L. E. Collins
- Department of Psychology, University of Connecticut, Storrs, CT 06269-1020, USA
| | - V. K. Vemuri
- Center for Drug Discovery, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - G. Thakur
- Center for Drug Discovery, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - A. Makriyannis
- Center for Drug Discovery, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - J. D. Salamone
- Department of Psychology, University of Connecticut, Storrs, CT 06269-1020, USA
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DiPatrizio NV, Simansky KJ. Activating parabrachial cannabinoid CB1 receptors selectively stimulates feeding of palatable foods in rats. J Neurosci 2008; 28:9702-9. [PMID: 18815256 PMCID: PMC2725524 DOI: 10.1523/jneurosci.1171-08.2008] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 07/11/2008] [Accepted: 08/17/2008] [Indexed: 11/21/2022] Open
Abstract
The endocannabinoid system is emerging as an integral component in central and peripheral regulation of feeding and energy balance. Our investigation analyzed behavioral roles for cannabinoid mechanisms of the pontine parabrachial nucleus (PBN) in modulating intake of presumably palatable foods containing fat and/or sugar. The PBN serves to gate neurotransmission associated with, but not limited to, the gustatory properties of food. Immunofluorescence and in vitro [(35)S]GTPgammaS autoradiography of rat tissue sections containing the PBN revealed the presence of cannabinoid receptors and their functional capability to couple to their G-proteins after incubation with the endocannabinoid 2-arachidonoyl glycerol (2-AG). The selective cannabinoid 1 receptor (CB(1)R) antagonist AM251 [N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide] prevented the response, demonstrating CB(1)R mediation of 2-AG-induced coupling. Microinfusions of 2-AG into the PBN in behaving rats robustly stimulated feeding of pellets high in content of fat and sucrose (HFS), pure sucrose, and pure fat (Crisco), during the first 30 min after infusion. In contrast, 2-AG failed to increase consumption of standard chow, even when the feeding regimen was manipulated to match baseline intakes of HFS. Orexigenic responses to 2-AG were attenuated by AM251, again indicating CB(1)R mediation of 2-AG actions. Furthermore, responses were regionally specific, because 2-AG failed to alter intake when infused into sites approximately 500 mum caudal to infusions that successfully stimulated feeding. Our data suggest that hedonically positive sensory properties of food enable endocannabinoids at PBN CB(1)Rs to initiate increases in eating, and, more generally, these pathways may serve a larger role in brain functions controlling behavioral responses for natural reward.
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MESH Headings
- Analysis of Variance
- Animals
- Arachidonic Acids/pharmacology
- Autoradiography/methods
- Behavior, Animal/drug effects
- Cannabinoid Receptor Modulators/pharmacology
- Conditioning, Operant/drug effects
- Conditioning, Operant/physiology
- Eating/drug effects
- Endocannabinoids
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Food Preferences/drug effects
- Food Preferences/physiology
- Glycerides/pharmacology
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Male
- Narcotic Antagonists/pharmacology
- Peptides/pharmacology
- Piperidines/pharmacology
- Pons/drug effects
- Pons/metabolism
- Pyrazoles/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Cannabinoid, CB1/agonists
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/physiology
- Receptors, Opioid, mu/metabolism
- Sulfur Isotopes/metabolism
- Time Factors
- Xanthines/pharmacology
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Affiliation(s)
- Nicholas V. DiPatrizio
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102
| | - Kenny J. Simansky
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102
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Dipatrizio NV, Simansky KJ. Inhibiting parabrachial fatty acid amide hydrolase activity selectively increases the intake of palatable food via cannabinoid CB1 receptors. Am J Physiol Regul Integr Comp Physiol 2008; 295:R1409-14. [PMID: 18768763 DOI: 10.1152/ajpregu.90484.2008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
These studies investigated feeding responses to indirect activation of parabrachial cannabinoid CB1 receptors. Arachidonoyl serotonin (AA5HT), an inhibitor of the endocannabinoid degradative enzyme, fatty acid amide hydrolase (FAAH), was infused into the parabrachial nucleus of male Sprague-Dawley rats, and intakes of high-fat/sucrose pellets and standard rodent chow were subsequently evaluated under various feeding schedules. FAAH blockade stimulated the intake of high-fat/sucrose pellets that were presented daily for 4 h during the light period, with compensatory decreases in the consumption of standard chow during the ensuing 20 h. These diet-selective changes were repeated on the next day, indicating a shift in feeding toward the more palatable diet that lasted for 48 h after a single infusion. The cannabinoid CB1 receptor antagonist, AM251, blocked the orexigenic actions of AA5HT, implicating CB1 receptors in mediating the feeding responses to FAAH inactivation. When the feeding schedule was reversed, AA5HT produced nominal increases in the consumption of standard chow for the 4-h access period, but substantial increases in the intake of high-fat/sucrose during the following 20-h interval. When presented with only high-fat/sucrose diet for 24 h, AA5HT increased 24-h food intake. In contrast, when given 24-h access only to standard chow, AA5HT failed to affect intake. Therefore, indirectly activating parabrachial CB1 receptors by blocking the degradation of native ligands selectively stimulates the intake of palatable food, with differential actions on total energy intake depending upon the feeding schedule. Our results support a role for parabrachial cannabinoid mechanisms in providing physiological regulation to neural substrates modulating feeding, energy balance, and behavioral responses for natural reward.
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Affiliation(s)
- Nicholas V Dipatrizio
- Drexel Univ. Coll. of Medicine, Dept. of Pharmacology and Physiology, 245 N. 15th St., MS#488, Philadelphia, PA 19102, USA
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Ryberg E, Larsson N, Sjögren S, Hjorth S, Hermansson NO, Leonova J, Elebring T, Nilsson K, Drmota T, Greasley PJ. The orphan receptor GPR55 is a novel cannabinoid receptor. Br J Pharmacol 2007; 152:1092-101. [PMID: 17876302 PMCID: PMC2095107 DOI: 10.1038/sj.bjp.0707460] [Citation(s) in RCA: 1129] [Impact Index Per Article: 66.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND The endocannabinoid system functions through two well characterized receptor systems, the CB1 and CB2 receptors. Work by a number of groups in recent years has provided evidence that the system is more complicated and additional receptor types should exist to explain ligand activity in a number of physiological processes. EXPERIMENTAL APPROACH Cells transfected with the human cDNA for GPR55 were tested for their ability to bind and to mediate GTPgammaS binding by cannabinoid ligands. Using an antibody and peptide blocking approach, the nature of the G-protein coupling was determined and further demonstrated by measuring activity of downstream signalling pathways. KEY RESULTS We demonstrate that GPR55 binds to and is activated by the cannabinoid ligand CP55940. In addition endocannabinoids including anandamide and virodhamine activate GTPgammaS binding via GPR55 with nM potencies. Ligands such as cannabidiol and abnormal cannabidiol which exhibit no CB1 or CB2 activity and are believed to function at a novel cannabinoid receptor, also showed activity at GPR55. GPR55 couples to Galpha13 and can mediate activation of rhoA, cdc42 and rac1. CONCLUSIONS These data suggest that GPR55 is a novel cannabinoid receptor, and its ligand profile with respect to CB1 and CB2 described here will permit delineation of its physiological function(s).
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Affiliation(s)
- E Ryberg
- Department of Lead Generation, AstraZeneca R&D Mölndal, Sweden
| | - N Larsson
- Department of Lead Generation, AstraZeneca R&D Mölndal, Sweden
| | - S Sjögren
- Department of Medical Sciences, AstraZeneca R&D Mölndal, Sweden
| | - S Hjorth
- Department of Integrative PharmacologyAstraZeneca R&D Mölndal, Sweden
| | - N-O Hermansson
- Department of Lead Generation, AstraZeneca R&D Mölndal, Sweden
| | - J Leonova
- Department of Lead Generation, AstraZeneca R&D Mölndal, Sweden
| | - T Elebring
- Department of Medicinal Chemistry, AstraZeneca R&D Mölndal, Sweden
| | - K Nilsson
- Department of Medicinal Chemistry, AstraZeneca R&D Mölndal, Sweden
| | - T Drmota
- Department of Lead Generation, AstraZeneca R&D Mölndal, Sweden
| | - P J Greasley
- Department of Lead Generation, AstraZeneca R&D Mölndal, Sweden
- Author for correspondence:
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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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O'Hare E, Kim EM, Tierney KJ. An operant determination of the behavioral mechanism of benzodiazepine enhancement of food intake. Psychopharmacology (Berl) 2006; 187:138-42. [PMID: 16715256 DOI: 10.1007/s00213-006-0412-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 04/10/2006] [Indexed: 10/24/2022]
Abstract
RATIONALE A recent review paper by Cooper (Appetite 44:133-150, 2005) has pointed out that a role for benzodiazepines as appetite stimulants has been largely overlooked. Cooper's review cited several studies that suggested the putative mechanism of enhancement of food intake after benzodiazepine administration might involve increasing the perceived pleasantness of food (palatability). OBJECTIVES The present study examined the behavioral mechanism of increased food intake after benzodiazepine administration. MATERIALS AND METHODS The cyclic-ratio operant schedule has been proposed as a useful behavioral assay for differentiating palatability from regulatory effects on food intake (Ettinger and Staddon, Physiol Behav 29:455-458, 1982 and Behav Neurosci 97:639-653, 1983). The current study employed the cyclic-ratio schedule to determine whether the effects on food intake of chlordiazepoxide (CDP) (5.0 mg/kg), sodium pentobarbital (5.0 mg/kg), and picrotoxin (1.0 mg/kg) were mediated through palatability or regulatory processes. RESULTS The results of this study show that both the benzodiazepine CDP and the barbiturate sodium pentobarbital increased food intake in a manner similar to increasing the palatability of the ingestant, and picrotoxin decreased food intake in a manner similar to decreasing the palatability of the ingestant. CONCLUSIONS These results suggest that the food intake enhancement properties of benzodiazepines are mediated through a mechanism affecting perceived palatability.
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Affiliation(s)
- E O'Hare
- School of Psychology, University of Ulster, Shore Road, Newtownabbey, Co. Antrim, BT37 0QB, Northern Ireland, UK.
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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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18
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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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19
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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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21
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Cooper SJ. Palatability-dependent appetite and benzodiazepines: new directions from the pharmacology of GABA(A) receptor subtypes. Appetite 2005; 44:133-50. [PMID: 15808888 DOI: 10.1016/j.appet.2005.01.003] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2004] [Revised: 12/08/2004] [Accepted: 01/20/2005] [Indexed: 01/22/2023]
Abstract
This paper updates an early review on benzodiazepine-enhanced food intake, published in the first issue of Appetite, and describes the considerable advances since then in the pharmacology of benzodiazepines, their sites and mechanisms of action, and in understanding the psychological processes leading to the increase in food consumption. A great diversity of benzodiazepine receptor ligands have been developed, many of which affect food intake. Agonists can be divided into full agonists (which produce the full spectrum of benzodiazepine effects) and partial agonists (which are more selective in their effects). In addition, inverse agonists have been identified, with high affinity for benzodiazepine receptors but having negative efficacy: these drugs exhibit anorectic properties. Benzodiazepine receptors are part of GABA(A) receptor complexes, and ligands thereby modulate inhibitory neurotransmission in the brain. Molecular approaches have identified a palette of receptor subunits from which GABA(A) receptors are assembled. In all likelihood, benzodiazepine-induced hyperphagia is mediated by the alpha2/alpha3 subtype not the alpha1 subtype. Novel alpha2/alpha3 selective compounds will test this hypothesis. A probable site of action in the caudal brainstem for benzodiazepines is the parabrachial nucleus. Behavioural evidence strongly indicates that a primary action of benzodiazepines is to enhance the positive hedonic evaluation (palatability) of tastes and foodstuffs. This generates the increased food intake and instrumental responding for food rewards. Therapeutic applications may derive from the actions of benzodiazepine agonists and inverse agonists on food procurement and ingestion.
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Affiliation(s)
- Steven J Cooper
- Kissileff Laboratory for the Study of Human Ingestive Behaviour, School of Psychology, University of Liverpool, Liverpool L69 7ZA, UK.
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Cooper SJ. Endocannabinoids and food consumption: comparisons with benzodiazepine and opioid palatability-dependent appetite. Eur J Pharmacol 2005; 500:37-49. [PMID: 15464019 DOI: 10.1016/j.ejphar.2004.07.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/01/2004] [Indexed: 01/22/2023]
Abstract
The endocannabinoid system consists of several endogenous lipids, including anandamide and 2-arachidonoyl-glycerol (2-AG), and constitute a retrograde signalling system, which modulates neurotransmitter release and synaptic plasticity. Specific brain-type cannabinoid receptors (CB(1)) are widely distributed in the central nervous system, and are localized presynaptically. Mounting evidence, reviewed here, indicates that cannabinoids can act to increase food consumption, and cannabinoid CB(1) receptor antagonists/inverse agonists reduce food intake and suppress operant responding for food rewards. Hence, endocannabinoids provide the first example of a retrograde signalling system, which is strongly implicated in the control of food intake. Benzodiazepine and opioid palatability-dependent appetite are well-established processes supported by several sources of convergent evidence; they provide pharmacological benchmarks against which to evaluate the endocannabinoids. To date, evidence that endocannabinoids specifically modulate palatability as an affective evaluative process is insufficient and not compelling. Endocannabinoids may have important clinical utility in the treatment of human obesity and forms of eating disorders.
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Affiliation(s)
- Steven J Cooper
- Kissileff Laboratory for the Study of Human Ingestive Behaviour, School of Psychology, University of Liverpool, Liverpool L69 7ZA, UK.
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23
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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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Cota D, Marsicano G, Lutz B, Vicennati V, Stalla GK, Pasquali R, Pagotto U. Endogenous cannabinoid system as a modulator of food intake. Int J Obes (Lond) 2003; 27:289-301. [PMID: 12629555 DOI: 10.1038/sj.ijo.0802250] [Citation(s) in RCA: 205] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ability of Cannabis sativa (marijuana) to increase hunger has been noticed for centuries, although intensive research on its molecular mode of action started only after the characterization of its main psychoactive component Delta(9)-tetrahydrocannabinol in the late 1960s. Despite the public concern related to the abuse of marijuana and its derivatives, scientific studies have pointed to the therapeutic potentials of cannabinoid compounds and have highlighted their ability to stimulate appetite, especially for sweet and palatable food. Later, the discovery of specific receptors and their endogenous ligands (endocannabinoids) suggested the existence of an endogenous cannabinoid system, providing a physiological basis for biological effects induced by marijuana and other cannabinoids. Epidemiological reports describing the appetite-stimulating properties of cannabinoids and the recent insights into the molecular mechanisms underlying cannabinoid action have proposed a central role of the cannabinoid system in obesity. The aim of this review is to provide an extensive overview on the role of this neuromodulatory system in feeding behavior by summarizing the most relevant data obtained from human and animal studies and by elucidating the interactions of the cannabinoid system with the most important neuronal networks and metabolic pathways involved in the control of food intake. Finally, a critical evaluation of future potential therapeutical applications of cannabinoid antagonists in the therapy of obesity and eating disorders will be discussed.
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Affiliation(s)
- D Cota
- Neuroendocrinology Group, Max-Planck-Institute of Psychiatry, Munich, Germany
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25
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Koch JE, Matthews SM. Delta9-tetrahydrocannabinol stimulates palatable food intake in Lewis rats: effects of peripheral and central administration. Nutr Neurosci 2002; 4:179-87. [PMID: 11842887 DOI: 10.1080/1028415x.2001.11747361] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
To further study effects of delta9-tetrahydrocannabinol (THC) on food intake, male Lewis rats were maintained on rat chow and, on testing days, presented with chocolate cake batter (CCB) for 4h in addition to chow. Chow intake was not affected by THC administration in either experiment. In experiment 1 (n = 13) THC was administered intraperitoneally, and low doses produced increases in CCB intake for up to 1 h while the highest dose significantly decreased CCB intake over this same time period. In experiment 2 (n = 10) THC was injected intracerebroventricularly. Doses of 2.5, 10 and 25 microg significantly increased CCB intake for up to 1 h while stimulatory effects following 5 microg lasted up to 2h. Overall THC produced short-term increases in palatable food intake following both peripheral and central administration. Intraperitoneal administration resulted in an "inverted U" dose-response curve at all time points, while all central doses resulted in increased intake early in the time course and the hyperphagic effects were of greater duration than those following peripheral administration.
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Affiliation(s)
- J E Koch
- Department of Psychology, University of Wisconsin, Oshkosh 54901, USA.
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26
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Rahminiwati M, Nishimura M. Effects of delta 9-tetrahydrocannabinol and diazepam on feeding behavior in mice. J Vet Med Sci 1999; 61:351-5. [PMID: 10342284 DOI: 10.1292/jvms.61.351] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study examined effects of diazepam (DZP) alone or in combination with delta 9-tetrahydrocannabinol (THC) on feeding behavior as well as body weight in male ddY strain mice at 5 weeks of age. Because we saw no hyperphagic effect of DZP with or without THC in mice, we explored the hyperphagia elicitable by DZP. THC [2 (THC2) or 4 (THC4) mg/kg/day s.c.] was given daily for 7 days. For the last day the mice were starved and injected i.p. with DZP (2 mg/kg) 10 min prior to a food or maze test. Controls received vehicle injections. Feeding behavior was measured after giving food for 2 hr. THC4 significantly reduced body weight gain. DZP, with or without THC, induced hyperphagia. THC4 alone also induced hyperphagia that was not significantly affected by DZP. Time taken to find food was extended by DZP and further with THC. Both DZP and THC can therefore interact on food ingestion but synergize on food seeking in mice through different mechanisms.
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Affiliation(s)
- M Rahminiwati
- Department of Pharmacology, University of Obihiro School of Veterinary Medicine, Hokkaido, Japan
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Abstract
This article discusses the role of the lateral hypothalamic area (LHA) in feeding and drinking and draws on data obtained from lesion and stimulation studies and neurochemical and electrophysiological manipulations of the area. The LHA is involved in catecholaminergic and serotonergic feeding systems and plays a role in circadian feeding, sex differences in feeding and spontaneous activity. This article discusses the LHA regarding dietary self-selection, responses to high-protein diets, amino acid imbalances, liquid and cafeteria diets, placentophagia, "stress eating," finickiness, diet texture, consistency and taste, aversion learning, olfaction and the effects of post-operative period manipulations by hormonal and other means. Glucose-sensitive neurons have been identified in the LHA and their manipulation by insulin and 2-deoxy-D-glucose is discussed. The effects on feeding of numerous transmitters, hormones and appetite depressants are described, as is the role of the LHA in salivation, lacrimation, gastric motility and secretion, and sensorimotor deficits. The LHA is also illuminated as regards temperature and feeding, circumventricular organs and thirst and electrolyte dynamics. A discussion of its role in the ischymetric hypothesis as an integrative Gestalt concept concludes the review.
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Affiliation(s)
- L L Bernardis
- Neurovisceral-Neuroendocrine Laboratory, Veterans Administration Medical Center Buffalo, NY, USA
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Naruse T, Asami T, Koizumi Y. Effects of naloxone and picrotoxin on diazepam- or pentobarbital-induced hyperphagia in nondeprived rats. Pharmacol Biochem Behav 1988; 31:709-11. [PMID: 3251254 DOI: 10.1016/0091-3057(88)90252-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Diazepam and pentobarbital administered intravenously increased food intake in a dose-dependent manner in nondeprived rats. Low doses of naloxone inhibited diazepam-induced feeding, but did not inhibit pentobarbital-induced feeding. On the other hand, picrotoxin inhibited feeding induced by both drugs. These findings suggest that diazepam-induced hyperphagia is related to endogenous opioid mechanisms, but pentobarbital-induced hyperphagia is not. Hyperphagia induced by both drugs may be related to GABAergic neurons.
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Affiliation(s)
- T Naruse
- Central Research Laboratories, Banyu Pharmaceutical Co. Ltd., Tokyo, Japan
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Polc P. Electrophysiology of benzodiazepine receptor ligands: multiple mechanisms and sites of action. Prog Neurobiol 1988; 31:349-423. [PMID: 2851856 DOI: 10.1016/0301-0082(88)90014-7] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Electrophysiology of BZR ligands has been reviewed from different points of view. A great effort was made to critically discuss the arguments for and against the temporarily leading hypothesis of the mechanism of action of BZR ligands, the GABA hypothesis. As has been discussed at length in the present article, an impressive body of electrophysiological and biochemical evidence suggests an enhancement of GABAergic inhibition in CNS as a mechanism of action of BZR agonists. Biochemical data even indicate a physical coupling between GABA recognition sites and BZR which, together with the effector site build-up by Cl- channels, form a supramolecular GABAA/BZR complex. By binding to a specific site on this complex, BZR agonists allosterically increase and BZR inverse agonists decrease the gating of GABA-linked Cl- channels, whereas BZR antagonists bind to the same site without an appreciable intrinsic activity and block the binding and action of both agonists as well as inverse agonists. While this model is supported by many electrophysiological experiments performed with BZR ligands in higher nanomolar and lower micromolar concentrations, it does not explain much controversial data from animal behavior and, more importantly, is not in line with electrophysiological effects obtained with low nanomolar BZ concentrations. The latter actions of BZR ligands in brain slices occur within a concentration range compatible with concentrations of BZ observed in CSF fluid, which would be expected to be found in the biophase (receptor level) during anxiolytic therapy in man. Enhanced K+ conductance seems to be a suitable candidate for this effect of BZR ligands. This direct action on neuronal membrane properties may underlie the many electrophysiological observations with extremely low systemic doses of BZR ligands in vivo which demonstrated a depressant effect on spontaneous neuronal firing in various CNS regions. Skeletomuscular spasticity and epilepsy are two neurological disorders, where both the enhanced GABAergic inhibition and increased K+ conductance may contribute to the therapeutic effect of BZR agonists, since electrophysiological and behavioral studies strongly support GABA-dependent as well as GABA-independent action of BZR ligands elicited by low to intermediate doses of BZ necessary to evoke anticonvulsant and muscle relaxant effects. Somewhat higher doses of BZR ligands, inducing sedation and sleep, lead perhaps to the only pharmacologically relevant CNS concentrations (ca. 1 microM) which might be due entirely to increased GABAergic inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)
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Kamatchi GL, Chandra D, Rajasekaran M, Rao KM, Venkatadri N, Bapna JS. Antagonism of diazepam hyperphagia by propranolol in rats. Drug Dev Res 1988. [DOI: 10.1002/ddr.430130405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Benzodiazepines such as chlordiazepoxide (CDP) promote feeding in a number of species. This effect has been interpreted generally to be an indirect consequence of benzodiazepine anti-anxiety action, although some have questioned whether it might not reflect instead a direct action upon the reinforcing properties of foods. The present study employed a behavioral measure that can discriminate between these possibilities: palatability-dependent consummatory actions elicited in rats by tastes. The results suggest that chlordiazepoxide enhances the positive palatability of tastes selectively while having little or no effect on aversive palatability. The net effect is to make tastes more reinforcing following CDP administration.
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Cooper SJ, Estall LB. Behavioural pharmacology of food, water and salt intake in relation to drug actions at benzodiazepine receptors. Neurosci Biobehav Rev 1985; 9:5-19. [PMID: 2579357 DOI: 10.1016/0149-7634(85)90028-4] [Citation(s) in RCA: 112] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Drugs which are agonists at benzodiazepine receptors produce many interesting behavioural effects, and amongst these are the stimulation of food, water and salt intake. This review examines the evidence for benzodiazepine effects on these forms of ingestion, and makes tentative proposals about their modes of action. The recent advent of putative benzodiazepine antagonists and inverse agonists provides important new pharmacological tools for the analysis of factors which control ingestion. Preliminary data on examples of such drugs are considered. Anorectic effects of inverse agonists are described. It is clear, though, that the categorization of a drug in one test situation may not apply to another. For example, the compound Ro15-1788 appears as a specific antagonist in one test, a partial agonist in another, and apparently lacks effect in a third. We are not yet sufficiently forward in our understanding of drug actions at benzodiazepine receptors, and their interactions with particular test circumstances, to predict and account for divergent effects of this kind.
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Abstract
Animal models for the study of anxiolytic agents are reviewed and evaluated according to pharmacological and behavioral criteria. Although there are important exceptions, in general, most early animal models have not provided a reliable basis for identifying compounds with potential anxiolytic action, or for delineating the mechanisms of anxiolytic drug action. The possibility that phylogenetically 'prepared' forms of defensive learning might serve as a basis for the study of anxiolytic agents is introduced.
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Abstract
There is considerable consistency in the experimental literature showing that non-sedating doses of benzodiazepines can enhance the consumption of food, water and salt solutions. It is of great interest, therefore, that in a previous report low dose treatments with diazepam were found to significantly suppress the level of consumption of a palatable 0.005 M sodium saccharin solution in nondeprived male rats. The present study was designed to elucidate the behavioral characteristics of the inhibitory action of low dose diazepam treatments. Food consumption and general activity measures were chosen for analysis to examine the possibilities that low dose diazepam treatments might suppress ingestive behavior in a general way, or that the treatments might affect nonconsummatory responses including components of spontaneous motor activity. The results of two experiments succeeded in locating a highly specific inhibitory effect produced by 100 micrograms/kg diazepam. First, food consumption was not inhibited. Instead, 1.0 mg/kg diazepam produced significant elevations in food intake in both food-deprived and nondeprived animals. Second, vertical activity (rearing) and fine body movements were unaffected over the dose-range 0.1-3.0 mg/kg diazepam. Hence, low dose treatments with diazepam did not produce a generalised nonspecific behavioral depression. However, 100 micrograms/mg diazepam significantly inhibited coarse activity (measured automatically) and the corresponding ambulation measure (recorded by direct observation). The effect was present throughout a 1 hr test period and did not interact with the declining baseline level of activity. The results therefore confirm the presence of low dose diazepam-induced behavioral inhibition in quite a different context from the saccharin solution consumption study.(ABSTRACT TRUNCATED AT 250 WORDS)
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Cooper SJ. Minireview. Benzodiazepine-opiate antagonist interactions in relation to feeding and drinking behavior. Life Sci 1983; 32:1043-51. [PMID: 6338330 DOI: 10.1016/0024-3205(83)90108-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Benzodiazepines reliably produce overconsumption of food and fluids. Opiate antagonists, naloxone and naltrexone, block the benzodiazepine-induced hyperphagia and hyperdipsia at low doses. Hence, activation of endogenous opioid mechanisms may be closely involved in the benzodiazepine facilitatory effects on ingestional behavior. Evidence is reviewed that opiate antagonists diminish feeding and drinking responses, and may enhance satiety processes in feeding and drinking, in addition to selectively diminishing the palatability of attractive foods and fluids. It is proposed that a single mechanism of action of the opiate antagonists would be sufficient to account for both effects on feeding and drinking. Biochemical data confirm that acute benzodiazepine treatment in vivo is associated with a naloxone-reversible release of striatal enkephalin. It is possible therefore that there is a close association between the behavioral and biochemical data, which both show that acute benzodiazepine effects are reversed by opiate antagonists. The implied relationship between benzodiazepine and endogenous opioid mechanisms may be relevant to the question of concurrent opiate-benzodiazepine abuse.
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Cooper SJ. GABA and endorphin mechanisms in relation to the effects of benzodiazepines on feeding and drinking. Prog Neuropsychopharmacol Biol Psychiatry 1983; 7:495-503. [PMID: 6141600 DOI: 10.1016/0278-5846(83)90016-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Behavioural actions of benzodiazepines have a number of significant characteristics. Anxiolytic effects are demonstrable both clinically and experimentally; in addition, there is excellent evidence for a reinforcing effect of these compounds, and a direct involvement in ingestional responses. This review focusses on the effects of benzodiazepines on the latter feeding and drinking responses. A necessary mediator of benzodiazepine action in the central nervous system appears to be the facilitation of inhibitory GABAergic neurotransmission. It follows, therefore, that behavioural consequences of benzodiazepine action may depend crucially on enhanced GABAergic activity in the brain. Evidence for some involvement of GABAergic mechanisms in the control of feeding and drinking responses is reviewed. Only a few data are so far available to link benzodiazepines effects on ingestional behaviour directly to GABAergic transmission. A major current theme in the psychopharmacology of feeding and drinking behaviour is the possible involvement of endogenous opioid peptides. There is a strong suggestion in the experimental data that there are links between benzodiazepine and endorphinergic mechanisms in relation to ingestional responses. A promising future line of approach appears to be a delineation of benzodiazepine-GABA-endorphin interrelations in the control of food and water consumption.
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Abstract
Marijuana, long used for the euphoria which results, recently has been found to stimulate hunger in humans but in several laboratory animals cannabinoids decrease food intake. Sheep, relatively more sensitive to chemicals that affect food intake, were injected IV with the d-and l-isomers of tetrahydrocannabinol and with a 9-aza-cannabinol) 9-AC) (8-(1,2-dimethylheptyl)-5,5-dimethyl-5H-[1]benzopyranol[3,4]pyridin-10-01, HCL) and feeding behavior was monitored. In the first 30 min, food intake was increased by the l-isomer and by 9-AC but not affected by d-delta 9-THC. After 24 h, feed intake was decreased by at least one dose of d-and l-delta 9-THC and 9-AC. The l-but not d-isomer was active at very low doses compared with doses used in many laboratory animals.
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