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Rodríguez-Serrano LM, Chávez-Hernández ME. Role of the CB2 Cannabinoid Receptor in the Regulation of Food Intake: A Systematic Review. Int J Mol Sci 2023; 24:17516. [PMID: 38139344 PMCID: PMC10743788 DOI: 10.3390/ijms242417516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/01/2023] [Accepted: 12/11/2023] [Indexed: 12/24/2023] Open
Abstract
The CB2 cannabinoid receptor has been found in brain areas that are part of the reward system and has been shown to play a role in food intake regulation. Herein, we conducted a systematic review of studies assessing the role of the CB2 receptor in food intake regulation. Records from the PubMed, Scopus, and EBSCO databases were screened, resulting in 13 studies that were used in the present systematic review, following the PRISMA guidelines. A risk of bias assessment was carried out using the tool of the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE). The studies analyzed used two main strategies: (1) the intraperitoneal or intracerebroventricular administration of a CB2 agonist/antagonist; and (2) depletion of CB2 receptors via knockout in mice. Both strategies are useful in identifying the role of the CB2 receptor in food intake in standard and palatable diets. The conclusions derived from animal models showed that CB2 receptors are necessary for modulating food intake and mediating energy balance.
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Affiliation(s)
- Luis Miguel Rodríguez-Serrano
- Facultad de Psicología, Universidad Anáhuac México, Universidad Anáhuac Avenue #46, Lomas Anáhuac, Huixquilucan 52786, Mexico;
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Haller J. Anxiety Modulation by Cannabinoids-The Role of Stress Responses and Coping. Int J Mol Sci 2023; 24:15777. [PMID: 37958761 PMCID: PMC10650718 DOI: 10.3390/ijms242115777] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 10/25/2023] [Accepted: 10/27/2023] [Indexed: 11/15/2023] Open
Abstract
Endocannabinoids were implicated in a variety of pathological conditions including anxiety and are considered promising new targets for anxiolytic drug development. The optimism concerning the potentials of this system for anxiolysis is probably justified. However, the complexity of the mechanisms affected by endocannabinoids, and discrepant findings obtained with various experimental approaches makes the interpretation of research results difficult. Here, we review the anxiety-related effects of the three main interventions used to study the endocannabinoid system: pharmacological agents active at endocannabinoid-binding sites present on both the cell membrane and in the cytoplasm, genetic manipulations targeting cannabinoid receptors, and function-enhancers represented by inhibitors of endocannabinoid degradation and transport. Binding-site ligands provide inconsistent findings probably because they activate a multitude of mechanisms concomitantly. More robust findings were obtained with genetic manipulations and particularly with function enhancers, which heighten ongoing endocannabinoid activation rather than affecting all mechanisms indiscriminately. The enhancement of ongoing activity appears to ameliorate stress-induced anxiety without consistent effects on anxiety in general. Limited evidence suggests that this effect is achieved by promoting active coping styles in critical situations. These findings suggest that the functional enhancement of endocannabinoid signaling is a promising drug development target for stress-related anxiety disorders.
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Affiliation(s)
- József Haller
- Drug Research Institute, 1137 Budapest, Hungary;
- Department of Criminal Psychology, University of Public Service, 1082 Budapest, Hungary
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Rathod SS, Agrawal YO, Nakhate KT, Meeran MFN, Ojha S, Goyal SN. Neuroinflammation in the Central Nervous System: Exploring the Evolving Influence of Endocannabinoid System. Biomedicines 2023; 11:2642. [PMID: 37893016 PMCID: PMC10604915 DOI: 10.3390/biomedicines11102642] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 09/20/2023] [Accepted: 09/21/2023] [Indexed: 10/29/2023] Open
Abstract
Neuroinflammation is a complex biological process that typically originates as a protective response in the brain. This inflammatory process is triggered by the release of pro-inflammatory substances like cytokines, prostaglandins, and reactive oxygen and nitrogen species from stimulated endothelial and glial cells, including those with pro-inflammatory functions, in the outer regions. While neuronal inflammation is common in various central nervous system disorders, the specific inflammatory pathways linked with different immune-mediated cell types and the various factors influencing the blood-brain barrier significantly contribute to disease-specific characteristics. The endocannabinoid system consists of cannabinoid receptors, endogenous cannabinoids, and enzymes responsible for synthesizing and metabolizing endocannabinoids. The primary cannabinoid receptor is CB1, predominantly found in specific brain regions such as the brainstem, cerebellum, hippocampus, and cortex. The presence of CB2 receptors in certain brain components, like cultured cerebellar granular cells, Purkinje fibers, and microglia, as well as in the areas like the cerebral cortex, hippocampus, and cerebellum is also evidenced by immunoblotting assays, radioligand binding, and autoradiography studies. Both CB1 and CB2 cannabinoid receptors exhibit noteworthy physiological responses and possess diverse neuromodulatory capabilities. This review primarily aims to outline the distribution of CB1 and CB2 receptors across different brain regions and explore their potential roles in regulating neuroinflammatory processes.
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Affiliation(s)
- Sumit S. Rathod
- Shri Vile Parle Kelavani Mandal’s Institute of Pharmacy, Dhule 424001, Maharashtra, India; (S.S.R.); (Y.O.A.); (K.T.N.)
- Department of Pharmacy, R. C. Patel Institute of Pharmaceutical Education and Research, Shirpur 425405, Maharashtra, India
| | - Yogeeta O. Agrawal
- Shri Vile Parle Kelavani Mandal’s Institute of Pharmacy, Dhule 424001, Maharashtra, India; (S.S.R.); (Y.O.A.); (K.T.N.)
| | - Kartik T. Nakhate
- Shri Vile Parle Kelavani Mandal’s Institute of Pharmacy, Dhule 424001, Maharashtra, India; (S.S.R.); (Y.O.A.); (K.T.N.)
| | - M. F. Nagoor Meeran
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, Abu Dhabi P.O. Box 15551, United Arab Emirates;
| | - Shreesh Ojha
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, Abu Dhabi P.O. Box 15551, United Arab Emirates;
| | - Sameer N. Goyal
- Shri Vile Parle Kelavani Mandal’s Institute of Pharmacy, Dhule 424001, Maharashtra, India; (S.S.R.); (Y.O.A.); (K.T.N.)
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Bourdy R, Befort K. The Role of the Endocannabinoid System in Binge Eating Disorder. Int J Mol Sci 2023; 24:ijms24119574. [PMID: 37298525 DOI: 10.3390/ijms24119574] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 05/23/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023] Open
Abstract
Eating disorders are multifactorial disorders that involve maladaptive feeding behaviors. Binge eating disorder (BED), the most prevalent of these in both men and women, is characterized by recurrent episodes of eating large amounts of food in a short period of time, with a subjective loss of control over eating behavior. BED modulates the brain reward circuit in humans and animal models, which involves the dynamic regulation of the dopamine circuitry. The endocannabinoid system plays a major role in the regulation of food intake, both centrally and in the periphery. Pharmacological approaches together with research using genetically modified animals have strongly highlighted a predominant role of the endocannabinoid system in feeding behaviors, with the specific modulation of addictive-like eating behaviors. The purpose of the present review is to summarize our current knowledge on the neurobiology of BED in humans and animal models and to highlight the specific role of the endocannabinoid system in the development and maintenance of BED. A proposed model for a better understanding of the underlying mechanisms involving the endocannabinoid system is discussed. Future research will be necessary to develop more specific treatment strategies to reduce BED symptoms.
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Affiliation(s)
- Romain Bourdy
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), Université de Strasbourg, UMR7364, CNRS, 12 Rue Goethe, 67000 Strasbourg, France
| | - Katia Befort
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), Université de Strasbourg, UMR7364, CNRS, 12 Rue Goethe, 67000 Strasbourg, France
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Li S, Huang Y, Yu L, Ji X, Wu J. Impact of the Cannabinoid System in Alzheimer's Disease. Curr Neuropharmacol 2023; 21:715-726. [PMID: 35105293 PMCID: PMC10207907 DOI: 10.2174/1570159x20666220201091006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/11/2022] [Accepted: 01/26/2022] [Indexed: 02/05/2023] Open
Abstract
Cannabinoids are compounds isolated from cannabis and are also widely present in both nervous and immune systems of animals. In recent years, with in-depth research on cannabinoids, their clinical medicinal value has been evaluated, and many exciting achievements have been continuously accumulating, especially in the field of neurodegenerative disease. Alzheimer's disease is the most common type of neurodegenerative disease that causes dementia and has become a global health problem that seriously impacts human health today. In this review, we discuss the therapeutic potential of cannabinoids for the treatment of Alzheimer's disease. How cannabinoids act on different endocannabinoid receptor subtypes to regulate Alzheimer's disease and the roles of the endocannabinoid system in Alzheimer's disease are outlined, and the underlying mechanisms are discussed. Finally, we summarize the most relevant opportunities of cannabinoid pharmacology related to Alzheimer's disease and discuss the potential usefulness of cannabinoids in the clinical treatment of Alzheimer's disease.
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Affiliation(s)
- Shuangtao Li
- Shantou University Medical College, Brain Function and Disease Laboratory, Shantou, #22 Road Xinling, Guangdong 515041, China
| | - Yuanbing Huang
- Department of Neurology, Yunfu People’s Hospital, Yunfu, Guangdong 527300, China
| | - Lijun Yu
- Shantou University Medical College, Brain Function and Disease Laboratory, Shantou, #22 Road Xinling, Guangdong 515041, China
| | - Xiaoyu Ji
- Department of Neurology, Yunfu People’s Hospital, Yunfu, Guangdong 527300, China
| | - Jie Wu
- Shantou University Medical College, Brain Function and Disease Laboratory, Shantou, #22 Road Xinling, Guangdong 515041, China
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Ji X, Zeng Y, Wu J. The CB 2 Receptor as a Novel Therapeutic Target for Epilepsy Treatment. Int J Mol Sci 2021; 22:ijms22168961. [PMID: 34445666 PMCID: PMC8396521 DOI: 10.3390/ijms22168961] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/02/2021] [Accepted: 08/10/2021] [Indexed: 02/05/2023] Open
Abstract
Epilepsy is characterized by repeated spontaneous bursts of neuronal hyperactivity and high synchronization in the central nervous system. It seriously affects the quality of life of epileptic patients, and nearly 30% of individuals are refractory to treatment of antiseizure drugs. Therefore, there is an urgent need to develop new drugs to manage and control refractory epilepsy. Cannabinoid ligands, including selective cannabinoid receptor subtype (CB1 or CB2 receptor) ligands and non-selective cannabinoid (synthetic and endogenous) ligands, may serve as novel candidates for this need. Cannabinoid appears to regulate seizure activity in the brain through the activation of CB1 and CB2 cannabinoid receptors (CB1R and CB2R). An abundant series of cannabinoid analogues have been tested in various animal models, including the rat pilocarpine model of acquired epilepsy, a pentylenetetrazol model of myoclonic seizures in mice, and a penicillin-induced model of epileptiform activity in the rats. The accumulating lines of evidence show that cannabinoid ligands exhibit significant benefits to control seizure activity in different epileptic models. In this review, we summarize the relationship between brain CB2 receptors and seizures and emphasize the potential mechanisms of their therapeutic effects involving the influences of neurons, astrocytes, and microglia cells. The unique features of CB2Rs, such as lower expression levels under physiological conditions and high inducibility under epileptic conditions, make it an important target for future research on drug-resistant epilepsy.
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Affiliation(s)
- Xiaoyu Ji
- Brain Function and Disease Laboratory, Shantou University Medical College, Xin-Ling Road #22, Shantou 515041, China;
| | - Yang Zeng
- Medical Education Assessment and Research Center, Shantou University Medical College, Xin-Ling Road #22, Shantou 515041, China;
| | - Jie Wu
- Brain Function and Disease Laboratory, Shantou University Medical College, Xin-Ling Road #22, Shantou 515041, China;
- Correspondence: or
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Qi X, Liu C, Li G, Al-Alfe D, Paurazas S, Askar M, Yang D, Zhou Z. Evaluation of Cannabinoids on the Odonto/Osteogenesis in Human Dental Pulp Cells In Vitro. J Endod 2021; 47:444-450. [PMID: 33352148 DOI: 10.1016/j.joen.2020.12.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/28/2020] [Accepted: 12/12/2020] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Cannabinoids possess anti-inflammatory, analgesic, and osteogenic effects in different cell types and tissues. The null hypothesis is delta-9-tetrahydrocannabinol (THC) might induce dental tissue repair and regeneration. The aim of this study was to investigate the effect of THC on human dental pulp cell (HDPC) viability and biomineralization as well as the molecular mechanism of THC-induced odonto/osteogenic differentiation of HDPCs. METHODS The toxicity of THC on HDPCs was determined by 3-(4,5-dimethylthiazolyl-2-yl)-2,5-diphenyltetrazolium bromide assay. The odonto/osteogenic differentiation marker genes of HDPCs were assessed by real-time polymerase chain reaction with or without THC treatment. HDPC biomineralization was examined by collagen synthesis and calcium nodule deposition. The molecular mechanism of THC on HDPCs was investigated by examining the mitogen-activated protein kinase (MAPK) signaling pathway via blocking cannabinoid receptor type 1 or 2 receptors. RESULTS We found that THC had no inhibition of HDPC vitality in the testing concentration (0-100 μmol/L). THC showed biphasic effects on HDPC proliferation. At a low dose (<5 μmol/L), THC considerably increased HDPC cell division. HDPC proliferation reduced with higher THC concentrations (>5 μmol/L). The expression of odonto/osteogenic marker genes were up-regulated in the presence of cannabinoids. These were confirmed by increased collagen synthesis and mineralized calcium nodule formation in the cannabinoid group. The effect of THC-induced odonto/osteogenesis occurred via MAPK signaling. CONCLUSIONS THC was biocompatible to HDPCs by promoting their mitogenic division in a biphasic pattern depending on the concentration. THC induced HDPC odonto/osteogenic differentiation through the activation of MAPK mediated by CB1 and CB2 receptors. Cannabinoids may play an important role in the HDPC regeneration process and potentially be used as a pulp-capping agent.
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Affiliation(s)
- Xia Qi
- Graduate Periodontics, School of Dentistry, University of Detroit Mercy, Detroit, Michigan; Department of Periodontics, School and Hospital of Stomatology, Hebei Medical University and Hebei Key Laboratory of Stomatology, Shijiazhuang, Hebei, China
| | - Chunyan Liu
- Graduate Periodontics, School of Dentistry, University of Detroit Mercy, Detroit, Michigan; Department of Orthodontics, School and Hospital of Stomatology, Hebei Medical University and Hebei Key Laboratory of Stomatology, Shijiazhuang, Hebei, China
| | - Guohua Li
- Graduate Periodontics, School of Dentistry, University of Detroit Mercy, Detroit, Michigan
| | - Dalia Al-Alfe
- Graduate Endodontics, School of Dentistry, University of Detroit Mercy, Detroit, Michigan
| | - Susan Paurazas
- Graduate Endodontics, School of Dentistry, University of Detroit Mercy, Detroit, Michigan
| | - Mazin Askar
- Graduate Endodontics, School of Dentistry, University of Detroit Mercy, Detroit, Michigan
| | - Dongru Yang
- Department of Periodontics, School and Hospital of Stomatology, Hebei Medical University and Hebei Key Laboratory of Stomatology, Shijiazhuang, Hebei, China; Graduate Periodontics, School of Dentistry, University of Detroit Mercy, Detroit, Michigan.
| | - Zheng Zhou
- Graduate Periodontics, School of Dentistry, University of Detroit Mercy, Detroit, Michigan.
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Influence of Cannabinoid Receptor Deficiency on Parameters Involved in Blood Glucose Regulation in Mice. Int J Mol Sci 2020; 21:ijms21093168. [PMID: 32365865 PMCID: PMC7246639 DOI: 10.3390/ijms21093168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/20/2020] [Accepted: 04/26/2020] [Indexed: 02/07/2023] Open
Abstract
Cannabinoids are known to influence hormone secretion of pancreatic islets via G protein-coupled cannabinoid receptor type 1 and 2 (CB1 and CB2). The present study was designed to further investigate the impact of cannabinoid receptors on the parameters involved in insulin secretion and blood glucose recognition. To this end, CB1 and CB2 receptor knockout mice (10–12 week old, both sexes) were characterised at basal state and compared to wild-type mice. The elimination of cannabinoid receptor signalling resulted in alterations of blood glucose concentrations, body weights and insulin levels. Changes were dependent on the deleted receptor type and on the sex. Analyses at mRNA and protein levels provided evidence for the impact of cannabinoid receptor deficiency on the glucose sensing apparatus in the pancreas. Both receptor knockout mouse lines showed decreased mRNA and protein amounts of glucose transporters Glut1 and Glut2, combined with alterations in immunostaining. In addition, pancreatic glucokinase expression was elevated and immunohistochemical labelling was modified in the pancreatic islets. Taken together, CB1 and CB2 signalling pathways seem to influence glucose sensing in β-cells by affecting glucose transporters and glucokinase. These alterations were more pronounced in CB2 knockout mice, resulting in higher blood glucose and lower plasma insulin levels.
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Ma Z, Gao F, Larsen B, Gao M, Luo Z, Chen D, Ma X, Qiu S, Zhou Y, Xie J, Xi ZX, Wu J. Mechanisms of cannabinoid CB 2 receptor-mediated reduction of dopamine neuronal excitability in mouse ventral tegmental area. EBioMedicine 2019; 42:225-237. [PMID: 30952618 PMCID: PMC6491419 DOI: 10.1016/j.ebiom.2019.03.040] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/24/2019] [Accepted: 03/14/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND We have recently reported that activation of cannabinoid type 2 receptors (CB2Rs) reduces dopamine (DA) neuron excitability in mouse ventral tegmental area (VTA). Here, we elucidate the underlying mechanisms. METHODS Patch-clamp recordings were performed in mouse VTA slices and dissociated single VTA DA neurons. FINDINGS Using cell-attached recording in VTA slices, bath-application of CB2R agonists (JWH133 or five other CB2R agonists) significantly reduced VTA DA neuron action potential (AP) firing rate. Under the patch-clamp whole-cell recording model, JWH133 (10 μM) mildly reduced the frequency of miniature excitatory postsynaptic currents (mEPSCs) but not miniature inhibitory postsynaptic currents (mIPSCs). JWH133 also did not alter evoked EPSCs or IPSCs. In freshly dissociated VTA DA neurons, JWH133 reduced AP firing rate, delayed AP initiation and enhanced AP after-hyperpolarization. In voltage-clamp recordings, JWH133 (1 μM) enhanced M-type K+ currents and this effect was absent in CB2-/- mice and abolished by co-administration of a selective CB2R antagonist (10 μM, AM630). CB2R-mediated inhibition in VTA DA neuron firing can be mimicked by M-current opener (10 μM retigabine) and blocked by M-current blocker (30 μM XE991). In addition, enhancement of neuronal cAMP by forskolin (10 μM) reduced M-current and increased DA neuron firing rate. Finally, pharmacological block of synaptic transmission by NBQX (10 μM), D-APV (50 μM) and picrotoxin (100 μM) in VTA slices failed to prevent CB2R-mediated inhibition, while intracellular infusion of guanosine 5'-O-2-thiodiphosphate (600 μM, GDP-β-S) through recording electrode to block postsynaptic G-protein function prevented JWH133-induced reduction in AP firing. INTERPRETATION Our results suggest that CB2Rs modulate VTA DA neuron excitability mainly through an intrinsic mechanism, including a CB2R-mediated reduction of intracellular cAMP, and in turn enhancement of M-type K+ currents. FUND: This research was supported by the Barrow Neuroscience Foundation, the BNI-BMS Seed Fund, and CNSF (81771437).
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Affiliation(s)
- Zegang Ma
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao 266071, China; Department of Neurobiology, St. Joseph's Hospital and Medical Center, Barrow Neurological Institute, Phoenix, AZ 85013, USA
| | - Fenfei Gao
- Department of Pharmacology, Shantou University Medical College, Shantou, Guangdong 210854, China; Department of Neurobiology, St. Joseph's Hospital and Medical Center, Barrow Neurological Institute, Phoenix, AZ 85013, USA
| | - Brett Larsen
- Department of Neurobiology, St. Joseph's Hospital and Medical Center, Barrow Neurological Institute, Phoenix, AZ 85013, USA; Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, AZ 85004, USA
| | - Ming Gao
- Department of Neurobiology, St. Joseph's Hospital and Medical Center, Barrow Neurological Institute, Phoenix, AZ 85013, USA
| | - Zhihua Luo
- Department of Pharmacology, Shantou University Medical College, Shantou, Guangdong 210854, China
| | - Dejie Chen
- Department of Neurobiology, St. Joseph's Hospital and Medical Center, Barrow Neurological Institute, Phoenix, AZ 85013, USA; Department of Neurology, Yunfu People's Hospital, Yunfu, Guangdong 527300, China
| | - Xiaokuang Ma
- Department of Neurobiology, St. Joseph's Hospital and Medical Center, Barrow Neurological Institute, Phoenix, AZ 85013, USA; Department of Pharmacology, Shantou University Medical College, Shantou, Guangdong 210854, China; Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, AZ 85004, USA
| | - Shenfeng Qiu
- Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, AZ 85004, USA
| | - Yu Zhou
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao 266071, China
| | - Junxia Xie
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao 266071, China
| | - Zheng-Xiong Xi
- Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD 21224, USA
| | - Jie Wu
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao 266071, China; Department of Neurobiology, St. Joseph's Hospital and Medical Center, Barrow Neurological Institute, Phoenix, AZ 85013, USA; Department of Pharmacology, Shantou University Medical College, Shantou, Guangdong 210854, China; Department of Neurology, Yunfu People's Hospital, Yunfu, Guangdong 527300, China.
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Zhang HY, Shen H, Jordan CJ, Liu QR, Gardner EL, Bonci A, Xi ZX. CB 2 receptor antibody signal specificity: correlations with the use of partial CB 2-knockout mice and anti-rat CB 2 receptor antibodies. Acta Pharmacol Sin 2019; 40:398-409. [PMID: 29967455 DOI: 10.1038/s41401-018-0037-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 05/02/2018] [Indexed: 12/13/2022] Open
Abstract
Cannabinoid CB1 receptors are highly expressed in the brain and functionally modulate presynaptic neurotransmitter release, while cannabinoid CB2 receptors (CB2Rs) were initially identified in the spleen and regarded as peripheral cannabinoid receptors. Recently, growing evidence indicates the presence of functional CB2Rs in the brain. However, this finding is disputed because of the specificity of CB2R antibody signals. We used two strains of currently available partial CB2-knockout (CB2-KO) mice as controls, four anti-rat or anti-mouse CB2R antibodies, and mRNA quantification to further address this issue. Western blot assays using the four antibodies detected a CB2R-like band at ~40 kD in both the brain and spleen. Notably, more bands were detected in the brain than in the spleen, and specific immune peptides blocked band detection. Immunohistochemical assays also detected CB2-like immunostaining in mouse midbrain dopamine neurons. CB2R deletion in CB2-KO mice may reduce or leave CB2R-like immunoreactivity unaltered depending on antibody epitope. Antibodies with epitopes at the receptor-deleted region detected a significant reduction in CB2R band density and immunostaining in N-terminal-deleted Deltagen and C-terminal-deleted Zimmer strain CB2-KO mice. Other antibodies with epitopes at the predicted receptor-undeleted regions detected similar band densities and immunostaining in wild-type and CB2-KO mice. Quantitative RT-PCR assays detected CB2 mRNA expression using probes that targeted upstream or downstream gene sequences but not the probe that targeted the gene-deleted sequence in Deltagen or Zimmer CB2-KO mice. These findings suggest that none of the tested four polyclonal antibodies are highly mouse CB2R-specific. Non-specific binding may be related to the expression of mutant or truncated CB2R-like proteins in partial CB2-KO mice and the use of anti-rat CB2 antibodies because the epitopes are different between rat and mouse CB2Rs.
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Filippini HF, Scalzilli PA, Costa KM, Freitas RDS, Campos MM. Activation of trigeminal ganglion satellite glial cells in CFA-induced tooth pulp pain in rats. PLoS One 2018; 13:e0207411. [PMID: 30419075 PMCID: PMC6231674 DOI: 10.1371/journal.pone.0207411] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 10/30/2018] [Indexed: 02/07/2023] Open
Abstract
This study further investigated the mechanisms underlying the rat model of tooth pulp inflammatory pain elicited by complete Freund's adjuvant (CFA), in comparison to other pulpitis models. Pulps of the left maxillary first molars were accessed. In the CFA group, the pulps were exposed, and CFA application was followed by dental sealing. In the open group, the pulps were left exposed to the oral cavity. For the closed group, the pulps were exposed, and the teeth were immediately sealed. Naïve rats were used as negative controls. Several parameters were evaluated at 1, 2, 3 and 8 days. There was no statistical significant difference among the groups when body weight variation, food or water consumption were compared. Analysis of serum cytokines (IL-1β, TNF or IL-6) or differential blood cell counts did not reveal any evidence of systemic inflammation. The CFA group displayed a significant reduction in the locomotor activity (at 1 and 3 days), associated with an increased activation of satellite glial cells in the ipsilateral trigeminal ganglion (TG; for up to 8 days). Amygdala astrocyte activation was unaffected in any experimental groups. We provide novel evidence indicating that CFA-induced pulp inflammation impaired the locomotor activity, with persistent activation of ipsilateral TG satellite cells surrounding sensory neurons, without any evidence of systemic inflammation or amygdala astrogliosis.
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Affiliation(s)
- Helena F. Filippini
- Programa de Pós-graduação em Odontologia, Escola de Ciências da Saúde, PUCRS, Porto Alegre, RS, Brasil
| | - Paulo A. Scalzilli
- Laboratório de Patologia, Escola de Ciência da Saúde, PUCRS, Porto Alegre, RS, Brasil
- Centro de Pesquisa em Toxicologia e Farmacologia, Escola de Ciências da Saúde, PUCRS, Porto Alegre, RS, Brasil
| | - Kesiane M. Costa
- Programa de Pós-graduação em Medicina e Ciências da Saúde, Escola de Medicina, PUCRS, Porto Alegre, RS, Brasil
| | - Raquel D. S. Freitas
- Centro de Pesquisa em Toxicologia e Farmacologia, Escola de Ciências da Saúde, PUCRS, Porto Alegre, RS, Brasil
- Programa de Pós-graduação em Medicina e Ciências da Saúde, Escola de Medicina, PUCRS, Porto Alegre, RS, Brasil
| | - Maria M. Campos
- Programa de Pós-graduação em Odontologia, Escola de Ciências da Saúde, PUCRS, Porto Alegre, RS, Brasil
- Laboratório de Patologia, Escola de Ciência da Saúde, PUCRS, Porto Alegre, RS, Brasil
- Centro de Pesquisa em Toxicologia e Farmacologia, Escola de Ciências da Saúde, PUCRS, Porto Alegre, RS, Brasil
- Programa de Pós-graduação em Medicina e Ciências da Saúde, Escola de Medicina, PUCRS, Porto Alegre, RS, Brasil
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12
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Chen DJ, Gao M, Gao FF, Su QX, Wu J. Brain cannabinoid receptor 2: expression, function and modulation. Acta Pharmacol Sin 2017; 38:312-316. [PMID: 28065934 PMCID: PMC5342669 DOI: 10.1038/aps.2016.149] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 10/18/2016] [Indexed: 02/06/2023] Open
Abstract
Cannabis sativa (marijuana) is a fibrous flowering plant that produces an abundant variety of molecules, some with psychoactive effects. At least 4% of the world's adult population uses cannabis annually, making it one of the most frequently used illicit drugs in the world. The psychoactive effects of cannabis are mediated primarily through cannabinoid receptor (CBR) subtypes. The prevailing view is that CB1Rs are mainly expressed in the central neurons, whereas CB2Rs are predominantly expressed in peripheral immune cells. However, this traditional view has been challenged by emerging strong evidence that shows CB2Rs are moderately expressed and function in specific brain areas. New evidence has demonstrated that brain CB2Rs modulate animal drug-seeking behaviors, suggesting that these receptors may exist in brain regions that regulate drug addiction. Recently, we further confirmed that functional CB2Rs are expressed in mouse ventral tegmental area (VTA) dopamine (DA) neurons and that the activation of VTA CB2Rs reduces neuronal excitability and cocaine-seeking behavior. In addition, CB2R-mediated modulation of hippocampal CA3 neuronal excitability and network synchronization has been reported. Here, we briefly summarize recent lines of evidence showing how CB2Rs modulate function and pathophysiology in the CNS.
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Affiliation(s)
- De-jie Chen
- Department of Neurology, Yunfu People's Hospital, Yunfu 527300, China
- Department of Neurobiology, Barrow Neurological Institute, St Joseph's Hospital and Medical Center, Phoenix, AZ 85013–4409, USA
| | - Ming Gao
- Department of Neurobiology, Barrow Neurological Institute, St Joseph's Hospital and Medical Center, Phoenix, AZ 85013–4409, USA
| | - Fen-fei Gao
- Department of Neurobiology, Barrow Neurological Institute, St Joseph's Hospital and Medical Center, Phoenix, AZ 85013–4409, USA
- Department of Pharmacology, Shantou University Medical College, Shantou 515041, China
| | - Quan-xi Su
- Department of Neurology, Yunfu People's Hospital, Yunfu 527300, China
| | - Jie Wu
- Department of Neurology, Yunfu People's Hospital, Yunfu 527300, China
- Department of Neurobiology, Barrow Neurological Institute, St Joseph's Hospital and Medical Center, Phoenix, AZ 85013–4409, USA
- Department of Pharmacology, Shantou University Medical College, Shantou 515041, China
- E-mail
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13
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Temporal dynamics of anxiety phenotypes in a dental pulp injury model. Mol Pain 2015; 11:40. [PMID: 26122003 PMCID: PMC4487070 DOI: 10.1186/s12990-015-0040-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 06/11/2015] [Indexed: 11/16/2022] Open
Abstract
Background Accumulating clinical and preclinical evidence indicates that chronic pain is often comorbid with persistent low mood and anxiety. However, the mechanisms underlying pain-induced anxiety, such as its causality, temporal progression, and relevant neural networks are poorly understood, impeding the development of efficacious therapeutic approaches. Results Here, we have identified the sequential emergence of anxiety phenotypes in mice subjected to dental pulp injury (DPI), a prototypical model of orofacial pain that correlates with human toothache. Compared with sham controls, mice subjected to DPI by mechanically exposing the pulp to the oral environment exhibited significant signs of anxiogenic effects, specifically, altered behaviors on the elevated plus maze (EPM), novelty-suppressed feeding (NSF) tests at 1 but not 3 days after the surgery. Notably, at 7 and 14 days, the DPI mice again avoided the open arm, center area, and novelty environment in the EPM, open field, and NSF tests, respectively. In particular, DPI-induced social phobia and increased repetitive grooming did not occur until 14 days after surgery, suggesting that DPI-induced social anxiety requires a long time. Moreover, oral administration of an anti-inflammatory drug, ibuprofen, or an analgesic agent, ProTx-II, which is a selective inhibitor of NaV1.7 sodium channels, both significantly alleviated DPI-induced avoidance in mice. Finally, to investigate the underlying central mechanisms, we pharmacologically blocked a popular form of synaptic plasticity with a GluA2-derived peptide, long-term depression, as that treatment significantly prevented the development of anxiety phenotype upon DPI. Conclusions Together, these results suggest a temporally progressive causal relationship between orofacial pain and anxiety, calling for more in-depth mechanistic studies on concomitant pain and anxiety disorders.
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14
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Zhang HY, Gao M, Liu QR, Bi GH, Li X, Yang HJ, Gardner EL, Wu J, Xi ZX. Cannabinoid CB2 receptors modulate midbrain dopamine neuronal activity and dopamine-related behavior in mice. Proc Natl Acad Sci U S A 2014; 111:E5007-15. [PMID: 25368177 PMCID: PMC4246322 DOI: 10.1073/pnas.1413210111] [Citation(s) in RCA: 257] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cannabinoid CB2 receptors (CB2Rs) have been recently reported to modulate brain dopamine (DA)-related behaviors; however, the cellular mechanisms underlying these actions are unclear. Here we report that CB2Rs are expressed in ventral tegmental area (VTA) DA neurons and functionally modulate DA neuronal excitability and DA-related behavior. In situ hybridization and immunohistochemical assays detected CB2 mRNA and CB2R immunostaining in VTA DA neurons. Electrophysiological studies demonstrated that activation of CB2Rs by JWH133 or other CB2R agonists inhibited VTA DA neuronal firing in vivo and ex vivo, whereas microinjections of JWH133 into the VTA inhibited cocaine self-administration. Importantly, all of the above findings observed in WT or CB1(-/-) mice are blocked by CB2R antagonist and absent in CB2(-/-) mice. These data suggest that CB2R-mediated reduction of VTA DA neuronal activity may underlie JWH133's modulation of DA-regulated behaviors.
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MESH Headings
- Action Potentials/drug effects
- Animals
- Appetitive Behavior/drug effects
- Appetitive Behavior/physiology
- Cannabinoids/administration & dosage
- Cannabinoids/pharmacology
- Cocaine/administration & dosage
- Cocaine-Related Disorders/physiopathology
- Dopamine/physiology
- Dopaminergic Neurons/drug effects
- Dopaminergic Neurons/metabolism
- Dopaminergic Neurons/physiology
- Feeding Behavior/drug effects
- Indoles/pharmacology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microinjections
- Nerve Tissue Proteins/agonists
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/physiology
- Neuroglia/metabolism
- RNA, Messenger/analysis
- Receptor, Cannabinoid, CB1/deficiency
- Receptor, Cannabinoid, CB2/agonists
- Receptor, Cannabinoid, CB2/antagonists & inhibitors
- Receptor, Cannabinoid, CB2/deficiency
- Receptor, Cannabinoid, CB2/genetics
- Receptor, Cannabinoid, CB2/physiology
- Reward
- Self Administration
- Spleen/cytology
- Spleen/metabolism
- Ventral Tegmental Area/drug effects
- Ventral Tegmental Area/physiology
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Affiliation(s)
- Hai-Ying Zhang
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD 21224
| | - Ming Gao
- Divisions of Neurology and Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013
| | - Qing-Rong Liu
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD 21224
| | - Guo-Hua Bi
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD 21224
| | - Xia Li
- Department of Psychiatry, School of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Hong-Ju Yang
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD 21224
| | - Eliot L Gardner
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD 21224
| | - Jie Wu
- Divisions of Neurology and Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013; Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, AZ 85004; and Department of Physiology, Shantou University Medical College, Shantou, Guangdong 210854, China
| | - Zheng-Xiong Xi
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD 21224;
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15
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Wenzel JM, Cheer JF. Endocannabinoid-dependent modulation of phasic dopamine signaling encodes external and internal reward-predictive cues. Front Psychiatry 2014; 5:118. [PMID: 25225488 PMCID: PMC4150350 DOI: 10.3389/fpsyt.2014.00118] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 08/13/2014] [Indexed: 11/13/2022] Open
Abstract
The mesolimbic dopamine (DA) system plays an integral role in incentive motivation and reward seeking and a growing body of evidence identifies signal transduction at cannabinoid receptors as a critical modulator of this system. Indeed, administration of exogenous cannabinoids results in burst firing of DA neurons of the ventral tegmental area and increases extracellular DA in the nucleus accumbens (NAcc). Implementation of fast-scan cyclic voltammetry (FSCV) confirms the ability of cannabinoids to augment DA within the NAcc on a subsecond timescale. The use of FSCV along with newly developed highly selective pharmacological compounds advances our understanding of how cannabinoids influence DA transmission and highlights a role for endocannabinoid-modulated subsecond DAergic activation in the incentive motivational properties of not only external, but also internal reward-predictive cues. For example, our laboratory has recently demonstrated that in mice responding under a fixed-interval (FI) schedule for food reinforcement, fluctuations in NAcc DA signal the principal cue predictive of reinforcer availability - time. That is, as the interval progresses, NAcc DA levels decline leading to accelerated food seeking and the resulting characteristic FI scallop pattern of responding. Importantly, administration of WIN 55,212-2, a synthetic cannabinoid agonist, or JZL184, an indirect cannabinoid agonist, increases DA levels during the interval and disrupts this pattern of responding. Along with a wealth of other reports, these results illustrate the role of cannabinoid receptor activation in the regulation of DA transmission and the control of temporally guided reward seeking. The current review will explore the striatal beat frequency model of interval timing as it pertains to cannabinoid signaling and propose a neurocircuitry through which this system modulates interoceptive time cues.
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Affiliation(s)
- Jennifer M Wenzel
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine , Baltimore, MD , USA
| | - Joseph F Cheer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine , Baltimore, MD , USA ; Department of Psychiatry, University of Maryland School of Medicine , Baltimore, MD , USA
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Pryce CR, Klaus F. Translating the evidence for gene association with depression into mouse models of depression-relevant behaviour: current limitations and future potential. Neurosci Biobehav Rev 2013; 37:1380-402. [PMID: 23680698 DOI: 10.1016/j.neubiorev.2013.05.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 04/15/2013] [Accepted: 05/03/2013] [Indexed: 12/11/2022]
Abstract
Depression is characterised by high prevalence and complex, heterogeneous psychopathology. At the level of aetio-pathology, considerable research effort has been invested to identify specific gene polymorphisms associated with increased depression prevalence. Genome-wide association studies have not identified any risk polymorphisms, and candidate gene case-control studies have identified a small number of risk polymorphisms. It is increasingly recognised that interaction between genotype and environmental factors (G×E), notably stressful life events, is the more realistic unit of depression aetio-pathology, with G×E evidence described for a small number of risk polymorphisms. An important complementary approach has been to describe genes exhibiting brain region-specific expression changes in depression. Mouse models of depression informed by the human evidence allow for the study of causality, but to-date have also yielded limited insights into depression aetio-pathology. This review of the translational evidence integrates human and mouse research approaches and evidence. It also makes specific recommendations in terms of how future research in human and mouse should be designed in order to deliver evidence for depression aetio-pathology and thereby to inform the development of novel and improved antidepressant treatments.
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Affiliation(s)
- Christopher R Pryce
- Preclinical Laboratory for Translational Research into Affective Disorders (PLaTRAD), Department of Psychiatry, Psychotherapy & Psychosomatics, Zurich University Hospital for Psychiatry, August Forel-Strasse 7, CH-8008 Zurich, Switzerland; Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland; Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
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Involvement of the opioid and cannabinoid systems in pain control: new insights from knockout studies. Eur J Pharmacol 2013; 716:142-57. [PMID: 23523475 DOI: 10.1016/j.ejphar.2013.01.077] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 01/24/2013] [Accepted: 01/29/2013] [Indexed: 12/20/2022]
Abstract
The endogenous opioid and cannabinoid systems are involved in the physiological inhibitory control of pain and are of particular interest for the development of therapeutic approaches for pain management. The involvement of these endogenous systems in pain control has been studied from decades by the use of compounds with different affinities for each cannabinoid and opioid receptor or for the different enzymes involved in endocannabinoid and endogenous opioid metabolism. However, the selectivity of these pharmacological tools in vivo has represented an important limitation for these studies. The generation of genetically modified mice with selective mutations in specific components of the endocannabinoid and endogenous opioid system has provided important advances in the identification of the specific contribution of each component of these endogenous systems in the perception of noxious stimuli and the development of pathological pain states. Different lines of constitutive and conditional knockout mice deficient in specific cannabinoid and opioid receptors, specific precursors of the endogenous opioid peptides and the main enzymes involved in endocannabinoid and endogenous opioid degradation are now available. These knockout mice have also been used to evaluate the contribution of each component of the endocannabinoid and opioid system in the antinociceptive effects of cannabinoid and opioid agonists, including those currently used to treat pain in humans. This review summarizes the main advances provided in the last 15 years by the use of these genetic tools in the knowledge of the physiological control of pain and the pharmacology of cannabinoid and opioid compounds for pain management.
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