1
|
Zhao Z, Covelo A, Couderc Y, Mitra A, Varilh M, Wu Y, Jacky D, Fayad R, Cannich A, Bellocchio L, Marsicano G, Beyeler A. Cannabinoids regulate an insula circuit controlling water intake. Curr Biol 2024; 34:1918-1929.e5. [PMID: 38636514 DOI: 10.1016/j.cub.2024.03.053] [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: 03/11/2022] [Revised: 02/29/2024] [Accepted: 03/25/2024] [Indexed: 04/20/2024]
Abstract
The insular cortex, or insula, is a large brain region involved in the detection of thirst and the regulation of water intake. However, our understanding of the topographical, circuit, and molecular mechanisms for controlling water intake within the insula remains parcellated. We found that type-1 cannabinoid (CB1) receptors in the insular cortex cells participate in the regulation of water intake and deconstructed the circuit mechanisms of this control. Topographically, we revealed that the activity of excitatory neurons in both the anterior insula (aIC) and posterior insula (pIC) increases in response to water intake, yet only the specific removal of CB1 receptors in the pIC decreases water intake. Interestingly, we found that CB1 receptors are highly expressed in insula projections to the basolateral amygdala (BLA), while undetectable in the neighboring central part of the amygdala. Thus, we recorded the neurons of the aIC or pIC targeting the BLA (aIC-BLA and pIC-BLA) and found that they decreased their activity upon water drinking. Additionally, chemogenetic activation of pIC-BLA projection neurons decreased water intake. Finally, we uncovered CB1-dependent short-term synaptic plasticity (depolarization-induced suppression of excitation [DSE]) selectively in pIC-BLA, compared with aIC-BLA synapses. Altogether, our results support a model where CB1 receptor signaling promotes water intake by inhibiting the pIC-BLA pathway, thereby contributing to the fine top-down control of thirst responses.
Collapse
Affiliation(s)
- Zhe Zhao
- INSERM 1215, Neurocentre Magendie, University of Bordeaux, 146 rue Léo Saignat, 33000 Bordeaux, France; Max Planck Florida Institute for Neuroscience, 1 Max Planck Way, Jupiter, FL 33458, USA
| | - Ana Covelo
- INSERM 1215, Neurocentre Magendie, University of Bordeaux, 146 rue Léo Saignat, 33000 Bordeaux, France
| | - Yoni Couderc
- INSERM 1215, Neurocentre Magendie, University of Bordeaux, 146 rue Léo Saignat, 33000 Bordeaux, France
| | - Arojit Mitra
- INSERM 1215, Neurocentre Magendie, University of Bordeaux, 146 rue Léo Saignat, 33000 Bordeaux, France
| | - Marjorie Varilh
- INSERM 1215, Neurocentre Magendie, University of Bordeaux, 146 rue Léo Saignat, 33000 Bordeaux, France
| | - Yifan Wu
- INSERM 1215, Neurocentre Magendie, University of Bordeaux, 146 rue Léo Saignat, 33000 Bordeaux, France
| | - Débora Jacky
- INSERM 1215, Neurocentre Magendie, University of Bordeaux, 146 rue Léo Saignat, 33000 Bordeaux, France
| | - Rim Fayad
- INSERM 1215, Neurocentre Magendie, University of Bordeaux, 146 rue Léo Saignat, 33000 Bordeaux, France
| | - Astrid Cannich
- INSERM 1215, Neurocentre Magendie, University of Bordeaux, 146 rue Léo Saignat, 33000 Bordeaux, France
| | - Luigi Bellocchio
- INSERM 1215, Neurocentre Magendie, University of Bordeaux, 146 rue Léo Saignat, 33000 Bordeaux, France
| | - Giovanni Marsicano
- INSERM 1215, Neurocentre Magendie, University of Bordeaux, 146 rue Léo Saignat, 33000 Bordeaux, France.
| | - Anna Beyeler
- INSERM 1215, Neurocentre Magendie, University of Bordeaux, 146 rue Léo Saignat, 33000 Bordeaux, France.
| |
Collapse
|
2
|
Abstract
PURPOSE A growing body of evidence has implicated the endocannabinoid (eCB) system in the acute, chronic, and withdrawal effects of alcohol/ethanol on synaptic function. These eCB-mediated synaptic effects may contribute to the development of alcohol use disorder (AUD). Alcohol exposure causes neurobiological alterations similar to those elicited by chronic cannabinoid (CB) exposure. Like alcohol, cannabinoids alter many central processes, such as cognition, locomotion, synaptic transmission, and neurotransmitter release. There is a strong need to elucidate the effects of ethanol on the eCB system in different brain regions to understand the role of eCB signaling in AUD. SEARCH METHODS For the scope of this review, preclinical studies were identified through queries of the PubMed database. SEARCH RESULTS This search yielded 459 articles. Clinical studies and papers irrelevant to the topic of this review were excluded. DISCUSSION AND CONCLUSIONS The endocannabinoid system includes, but is not limited to, cannabinoid receptors 1 (CB1), among the most abundantly expressed neuronal receptors in the brain; cannabinoid receptors 2 (CB2); and endogenously formed CB1 ligands, including arachidonoylethanolamide (AEA; anandamide), and 2-arachidonoylglycerol (2-AG). The development of specific CB1 agonists, such as WIN 55,212-2 (WIN), and antagonists, such as SR 141716A (rimonabant), provide powerful pharmacological tools for eCB research. Alcohol exposure has brain region-specific effects on the eCB system, including altering the synthesis of endocannabinoids (e.g., AEA, 2-AG), the synthesis of their precursors, and the density and coupling efficacy of CB1. These alcohol-induced alterations of the eCB system have subsequent effects on synaptic function including neuronal excitability and postsynaptic conductance. This review will provide a comprehensive evaluation of the current literature on the synaptic interactions of alcohol exposure and eCB signaling systems, with an emphasis on molecular and physiological synaptic effects of alcohol on the eCB system. A limited volume of studies has focused on the underlying interactions of alcohol and the eCB system at the synaptic level in the brain. Thus, the data on synaptic interactions are sparse, and future research addressing these interactions is much needed.
Collapse
Affiliation(s)
- Sarah A Wolfe
- Department of Molecular Medicine, Scripps Research Institute, La Jolla, California
| | - Valentina Vozella
- Department of Molecular Medicine, Scripps Research Institute, La Jolla, California
| | - Marisa Roberto
- Department of Molecular Medicine, Scripps Research Institute, La Jolla, California
| |
Collapse
|
3
|
Stielper ZF, Fucich EA, Middleton JW, Hillard CJ, Edwards S, Molina PE, Gilpin NW. Traumatic Brain Injury and Alcohol Drinking Alter Basolateral Amygdala Endocannabinoids in Female Rats. J Neurotrauma 2020; 38:422-434. [PMID: 32838651 DOI: 10.1089/neu.2020.7175] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Traumatic brain injury (TBI) affects approximately 3 million Americans yearly and increases vulnerability to developing psychiatric comorbidities. Alcohol use disorder (AUD) is the most prevalent psychiatric diagnosis preceding injury and TBI may increase subsequent alcohol use. The basolateral amygdala (BLA) is a limbic structure commonly affected by TBI that is implicated in anxiety and AUD. Endocannabinoids (eCBs) regulate synaptic activity in the BLA, and BLA eCB modulation alters anxiety-like behavior and stress reactivity. Previous work from our laboratories showed that systemic eCB degradation inhibition ameliorates TBI-induced increases in anxiety-like behavior and motivation to respond for alcohol in male rats. Here, we used a lateral fluid percussion model to test moderate TBI effects on anxiety-like behavior, alcohol drinking, and eCB levels and cell signaling in BLA, as well as the effect of alcohol drinking on anxiety-like behavior and the BLA eCB system, in female rats. Our results show that TBI does not promote escalation of operant alcohol self-administration or increase anxiety-like behavior in female rats. In the BLA, TBI and alcohol drinking alter tissue amounts of 2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (anandamide; AEA) 1 h post-injury, and 2-AG levels remain low 11 days post-injury. Eleven days after injury, BLA pyramidal neurons were hyperexcitable, but measures of synaptic transmission and eCB signaling were unchanged. These data show that TBI impacts BLA 2-AG tissue levels, that this effect is modified by alcohol drinking, and also that TBI increases BLA cell excitability.
Collapse
Affiliation(s)
- Zachary F Stielper
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.,Alcohol and Drug Abuse Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Elizabeth A Fucich
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.,Alcohol and Drug Abuse Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.,Neuroscience Program, Tulane University, New Orleans, Louisiana, USA
| | - Jason W Middleton
- Alcohol and Drug Abuse Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.,Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Cecilia J Hillard
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Scott Edwards
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.,Alcohol and Drug Abuse Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Patricia E Molina
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.,Alcohol and Drug Abuse Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Nicholas W Gilpin
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.,Alcohol and Drug Abuse Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.,Southeast Louisiana VA Healthcare System, New Orleans, Louisiana, USA
| |
Collapse
|
4
|
Scarnati MS, Boreland AJ, Joel M, Hart RP, Pang ZP. Differential sensitivity of human neurons carrying μ opioid receptor (MOR) N40D variants in response to ethanol. Alcohol 2020; 87:97-109. [PMID: 32561311 PMCID: PMC7958146 DOI: 10.1016/j.alcohol.2020.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 05/15/2020] [Accepted: 05/25/2020] [Indexed: 12/11/2022]
Abstract
The acute and chronic effects of alcohol on the brain and behavior are linked to alterations in inhibitory synaptic transmission. Alcohol's most consistent effect at the synaptic level is probably a facilitation of γ-aminobutyric acid (GABA) release, as seen from several rodent studies. The impact of alcohol on GABAergic neurotransmission in human neurons is unknown, due to a lack of a suitable experimental model. Human neurons can also be used to model effects of genetic variants linked with alcohol use disorders (AUDs). The A118G single nucleotide polymorphism (SNP rs1799971) of the OPRM1 gene encoding the N40D (D40 minor allele) mu-opioid receptor (MOR) variant has been linked with individuals who have an AUD. However, while N40D is clearly associated with other drugs of abuse, involvement with AUDs is controversial. In this study, we employed Ascl1-and Dlx2-induced inhibitory neuronal cells (AD-iNs) generated from human iPS cell lines carrying N40D variants, and investigated the impact of ethanol acutely and chronically on GABAergic synaptic transmission. We found that N40 AD-iNs display a stronger facilitation (versus D40) of spontaneous and miniature inhibitory postsynaptic current frequency in response to acute ethanol application. Quantitative immunocytochemistry of Synapsin 1+ synaptic puncta revealed a similar synapse number between N40 and D40 iNs, suggesting an ethanol modulation of presynaptic GABA release without affecting synapse density. Interestingly, D40 iNs exposed to chronic intermittent ethanol application caused a significant increase in mIPSC frequency, with only a modest enhancement observed in N40 iNs. These data suggest that the MOR genotype may confer differential sensitivity to synaptic output, which depends on ethanol exposure time and concentration for AD-iNs and may help explain alcohol dependence in individuals who carry the MOR D40 SNPs. Furthermore, this study supports the use of human neuronal cells carrying risk-associated genetic variants linked to disease, as in vitro models to assay the synaptic actions of alcohol on human neuronal cells.
Collapse
Affiliation(s)
- Matthew S Scarnati
- Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA; Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Andrew J Boreland
- Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA; Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Marisa Joel
- Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA; Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, 08854, USA
| | - Ronald P Hart
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, 08854, USA; Human Genetics Institute of New Jersey, Piscataway, NJ, 08854, USA
| | - Zhiping P Pang
- Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA; Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA.
| |
Collapse
|
5
|
Kunos G. Interactions Between Alcohol and the Endocannabinoid System. Alcohol Clin Exp Res 2020; 44:790-805. [PMID: 32056226 DOI: 10.1111/acer.14306] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 02/05/2020] [Indexed: 12/12/2022]
Abstract
Endocannabinoids are lipid mediators that interact with the same cannabinoid receptors that recognize Δ9 -tetrahydrocannabinol (THC), the psychoactive constituent of marijuana, to induce similar effects in the brain and periphery. Alcohol and THC are both addictive substances whose acute use elicits rewarding effects that can lead to chronic and compulsive use via engaging similar signaling pathways in the brain. In the liver, both alcohol and endocannabinoids activate lipogenic gene expression leading to fatty liver disease. This review focuses on evidence accumulated over the last 2 decades to indicate that both the addictive neural effects of ethanol and its organ toxic effects in the liver and elsewhere are mediated, to a large extent, by endocannabinoids signaling via cannabinoid-1 receptors (CB1 R). The therapeutic potential of CB1 R blockade globally or in peripheral tissues only is also discussed.
Collapse
Affiliation(s)
- George Kunos
- From the, Division of Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland
| |
Collapse
|
6
|
Peñasco S, Rico-Barrio I, Puente N, Fontaine CJ, Ramos A, Reguero L, Gerrikagoitia I, de Fonseca FR, Suarez J, Barrondo S, Aretxabala X, García Del Caño G, Sallés J, Elezgarai I, Nahirney PC, Christie BR, Grandes P. Intermittent ethanol exposure during adolescence impairs cannabinoid type 1 receptor-dependent long-term depression and recognition memory in adult mice. Neuropsychopharmacology 2020; 45:309-318. [PMID: 31569197 PMCID: PMC6901552 DOI: 10.1038/s41386-019-0530-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Revised: 08/23/2019] [Accepted: 09/17/2019] [Indexed: 12/11/2022]
Abstract
Binge drinking is a significant problem in adolescent populations, and because of the reciprocal interactions between ethanol (EtOH) consumption and the endocannabinoid (eCB) system, we sought to determine if adolescent EtOH intake altered the localization and function of the cannabinoid 1 (CB1) receptors in the adult brain. Adolescent mice were exposed to a 4-day-per week drinking in the dark (DID) procedure for a total of 4 weeks and then tested after a 2-week withdrawal period. Field excitatory postsynaptic potentials (fEPSPs), evoked by medial perforant path (MPP) stimulation in the dentate gyrus molecular layer (DGML), were significantly smaller. Furthermore, unlike control animals, CB1 receptor activation did not depress fEPSPs in the EtOH-exposed animals. We also examined a form of excitatory long-term depression that is dependent on CB1 receptors (eCB-eLTD) and found that it was completely lacking in the animals that consumed EtOH during adolescence. Histological analyses indicated that adolescent EtOH intake significantly reduced the CB1 receptor distribution and proportion of immunopositive excitatory synaptic terminals in the medial DGML. Furthermore, there was decreased binding of [35S]guanosine-5*-O-(3-thiotriphosphate) ([35S] GTPγS) and the guanine nucleotide-binding (G) protein Gαi2 subunit in the EtOH-exposed animals. Associated with this, there was a significant increase in monoacylglycerol lipase (MAGL) mRNA and protein in the hippocampus of EtOH-exposed animals. Conversely, deficits in eCB-eLTD and recognition memory could be rescued by inhibiting MAGL with JZL184. These findings indicate that repeated exposure to EtOH during adolescence leads to long-term deficits in CB1 receptor expression, eCB-eLTD, and reduced recognition memory, but that these functional deficits can be restored by treatments that increase endogenous 2-arachidonoylglycerol.
Collapse
Affiliation(s)
- Sara Peñasco
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940, Leioa, Vizcaya, Spain
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Leioa, Vizcaya, Spain
| | - Irantzu Rico-Barrio
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940, Leioa, Vizcaya, Spain
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Leioa, Vizcaya, Spain
| | - Nagore Puente
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940, Leioa, Vizcaya, Spain
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Leioa, Vizcaya, Spain
| | - Christine J Fontaine
- Division of Medical Sciences, University of Victoria, Victoria, BC, V8P 5C2, Canada
| | - Almudena Ramos
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940, Leioa, Vizcaya, Spain
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Leioa, Vizcaya, Spain
| | - Leire Reguero
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940, Leioa, Vizcaya, Spain
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Leioa, Vizcaya, Spain
| | - Inmaculada Gerrikagoitia
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940, Leioa, Vizcaya, Spain
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Leioa, Vizcaya, Spain
| | - Fernando Rodríguez de Fonseca
- Hospital Regional Universitario de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), 29010, Málaga, Spain
| | - Juan Suarez
- Hospital Regional Universitario de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), 29010, Málaga, Spain
| | - Sergio Barrondo
- Department of Pharmacology, Faculty of Pharmacy, University of the Basque Country UPV/EHU, CIBERSAM, Paseo de la Universidad 7, Vitoria-Gasteiz, Alava, 01006, Vitoria-Gasteiz, Spain
| | - Xabier Aretxabala
- Department of Neurosciences, Faculty of Pharmacy, University of the Basque Country UPV/EHU, Paseo de la Universidad 7, 01006, Vitoria-Gasteiz, Araba, Spain
| | - Gontzal García Del Caño
- Department of Neurosciences, Faculty of Pharmacy, University of the Basque Country UPV/EHU, Paseo de la Universidad 7, 01006, Vitoria-Gasteiz, Araba, Spain
| | - Joan Sallés
- Department of Pharmacology, Faculty of Pharmacy, University of the Basque Country UPV/EHU, CIBERSAM, Paseo de la Universidad 7, Vitoria-Gasteiz, Alava, 01006, Vitoria-Gasteiz, Spain
| | - Izaskun Elezgarai
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940, Leioa, Vizcaya, Spain
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Leioa, Vizcaya, Spain
| | - Patrick C Nahirney
- Division of Medical Sciences, University of Victoria, Victoria, BC, V8P 5C2, Canada
| | - Brian R Christie
- Division of Medical Sciences, University of Victoria, Victoria, BC, V8P 5C2, Canada
| | - Pedro Grandes
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, 48940, Leioa, Vizcaya, Spain.
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Leioa, Vizcaya, Spain.
- Division of Medical Sciences, University of Victoria, Victoria, BC, V8P 5C2, Canada.
| |
Collapse
|
7
|
Karoly HC, Mueller RL, Bidwell LC, Hutchison KE. Cannabinoids and the Microbiota-Gut-Brain Axis: Emerging Effects of Cannabidiol and Potential Applications to Alcohol Use Disorders. Alcohol Clin Exp Res 2019; 44:340-353. [PMID: 31803950 DOI: 10.1111/acer.14256] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 11/25/2019] [Indexed: 02/06/2023]
Abstract
The endocannabinoid system (ECS) has emerged in recent years as a potential treatment target for alcohol use disorders (AUD). In particular, the nonpsychoactive cannabinoid cannabidiol (CBD) has shown preclinical promise in ameliorating numerous clinical symptoms of AUD. There are several proposed mechanism(s) through which cannabinoids (and CBD in particular) may confer beneficial effects in the context of AUD. First, CBD may directly impact specific brain mechanisms underlying AUD to influence alcohol consumption and the clinical features of AUD. Second, CBD may influence AUD symptoms through its actions across the digestive, immune, and central nervous systems, collectively known as the microbiota-gut-brain axis (MGBA). Notably, emerging work suggests that alcohol and cannabinoids exert opposing effects on the MGBA. Alcohol is linked to immune dysfunction (e.g., chronic systemic inflammation in the brain and periphery) as well as disturbances in gut microbial species (microbiota) and increased intestinal permeability. These MGBA disruptions have been associated with AUD symptoms such as craving and impaired cognitive control. Conversely, existing preclinical data suggest that cannabinoids may confer beneficial effects on the gastrointestinal and immune system, such as reducing intestinal permeability, regulating gut bacteria, and reducing inflammation. Thus, cannabinoids may exert AUD harm-reduction effects, at least in part, through their beneficial actions across the MGBA. This review will provide a brief introduction to the ECS and the MGBA, discuss the effects of cannabinoids (particularly CBD) and alcohol in the brain, gut, and immune system (i.e., across the MGBA), and put forth a theoretical framework to inform future research questions.
Collapse
Affiliation(s)
- Hollis C Karoly
- Institute of Cognitive Science, University of Colorado Boulder, Boulder, Colorado
| | - Raeghan L Mueller
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado
| | - L Cinnamon Bidwell
- Institute of Cognitive Science, University of Colorado Boulder, Boulder, Colorado.,Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado
| | - Kent E Hutchison
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado
| |
Collapse
|
8
|
Basavarajappa BS, Joshi V, Shivakumar M, Subbanna S. Distinct functions of endogenous cannabinoid system in alcohol abuse disorders. Br J Pharmacol 2019; 176:3085-3109. [PMID: 31265740 DOI: 10.1111/bph.14780] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 06/11/2019] [Accepted: 06/18/2019] [Indexed: 12/20/2022] Open
Abstract
Δ9 -tetrahydrocannabinol, the principal active component in Cannabis sativa extracts such as marijuana, participates in cell signalling by binding to cannabinoid CB1 and CB2 receptors on the cell surface. The CB1 receptors are present in both inhibitory and excitatory presynaptic terminals and the CB2 receptors are found in neuronal subpopulations in addition to microglial cells and astrocytes and are present in both presynaptic and postsynaptic terminals. Subsequent to the discovery of the endocannabinoid (eCB) system, studies have suggested that alcohol alters the eCB system and that this system plays a major role in the motivation to abuse alcohol. Preclinical studies have provided evidence that chronic alcohol consumption modulates eCBs and expression of CB1 receptors in brain addiction circuits. In addition, studies have further established the distinct function of the eCB system in the development of fetal alcohol spectrum disorders. This review provides a recent and comprehensive assessment of the literature related to the function of the eCB system in alcohol abuse disorders.
Collapse
Affiliation(s)
- Balapal S Basavarajappa
- Division of Analytical Psychopharmacology, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA.,New York State Psychiatric Institute, New York, NY, USA.,Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY, USA.,Department of Psychiatry, New York University Langone Medical Center, New York, NY, USA
| | - Vikram Joshi
- Division of Analytical Psychopharmacology, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - Madhu Shivakumar
- Division of Analytical Psychopharmacology, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - Shivakumar Subbanna
- Division of Analytical Psychopharmacology, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| |
Collapse
|
9
|
Abstract
Ethanol produces intoxication through actions on numerous molecular and cellular targets. Adaptations involving these and other targets contribute to chronic drug actions that underlie continued and problematic drinking. Among the mechanisms involved in these ethanol actions are alterations in presynaptic mechanisms of synaptic transmission, including presynaptic protein function and excitation-secretion coupling. At synapses in the central nervous system (CNS), excitation-secretion coupling involves ion channel activation followed by vesicle fusion and neurotransmitter release. These mechanisms are altered by presynaptic neurotransmitter receptors and prominently by G protein-coupled receptors (GPCRs). Studies over the last 20-25 years have revealed that acute ethanol exposure alters neurotransmitter secretion, with especially robust effects on synapses that use the neurotransmitter gamma-aminobutyric acid (GABA). Intracellular signaling pathways involving second messengers such as cyclic AMP and calcium are implicated in these acute ethanol actions. Ethanol-induced release of neuropeptides and small molecule neurotransmitters that act on presynaptic GPCRs also contribute to presynaptic potentiation at synapses in the amygdala and hippocampus and inhibition of GABA release in the striatum. Prolonged exposure to ethanol alters neurotransmitter release at many CNS GABAergic and glutamatergic synapses, and changes in GPCR function are implicated in many of these neuroadaptations. These presynaptic neuroadaptations appear to involve compensation for acute drug effects at some synapses, but "allostatic" effects that result in long-term resetting of synaptic efficacy occur at others. Current investigations are determining how presynaptic neuroadaptations contribute to behavioral changes at different stages of alcohol drinking, with increasing focus on circuit adaptations underlying these behaviors. This chapter will discuss the acute and chronic presynaptic effects of ethanol in the CNS, as well as some of the consequences of these effects in amygdala and corticostriatal circuits that are related to excessive seeking/drinking and ethanol abuse.
Collapse
Affiliation(s)
- David M Lovinger
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA.
| |
Collapse
|
10
|
Rice J, Gu C. Function and Mechanism of Myelin Regulation in Alcohol Abuse and Alcoholism. Bioessays 2019; 41:e1800255. [PMID: 31094014 DOI: 10.1002/bies.201800255] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 03/31/2019] [Indexed: 12/26/2022]
Abstract
Excessive alcohol use has adverse effects on the central nervous system (CNS) and can lead to alcohol use disorders (AUDs). Recent studies have suggested that myelin reductions may directly contribute to CNS dysfunctions associated with AUDs. Myelin consists of compact lipid membranes wrapped around axons to provide electrical insulation and trophic support. Regulation of myelin is considered as a new form of neural plasticity due to its profound impacts on the computation of neural networks. In this review, the authors first discuss experimental evidence showing how alcohol exposure causes demyelination in different brain regions, often accompanied by deficits in cognition and emotion. Next, they discuss postulated molecular and cellular mechanisms underlying alcohol's impact on myelin. It is clear that more extensive investigations are needed in this important but underexplored research field in order to gain a better understanding of the myelin-behavior relationship and to develop new treatment strategies for AUDs.
Collapse
Affiliation(s)
- James Rice
- Department of Biological Chemistry and Pharmacology, The Ohio State University, 1060 Carmack Road, Columbus, OH, 43210, USA
| | - Chen Gu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, 1060 Carmack Road, Columbus, OH, 43210, USA
| |
Collapse
|
11
|
Bonilla-Del Rίo I, Puente N, Peñasco S, Rico I, Gutiérrez-Rodrίguez A, Elezgarai I, Ramos A, Reguero L, Gerrikagoitia I, Christie BR, Nahirney P, Grandes P. Adolescent ethanol intake alters cannabinoid type-1 receptor localization in astrocytes of the adult mouse hippocampus. Addict Biol 2019; 24:182-192. [PMID: 29168269 DOI: 10.1111/adb.12585] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 09/26/2017] [Accepted: 11/06/2017] [Indexed: 01/02/2023]
Abstract
Cannabinoid type-1 (CB1 ) receptors are widely distributed in the brain and play important roles in astrocyte function and the modulation of neuronal synaptic transmission and plasticity. However, it is currently unknown how CB1 receptor expression in astrocytes is affected by long-term exposure to stressors. Here we examined CB1 receptors in astrocytes of ethanol (EtOH)-exposed adolescent mice to determine its effect on CB1 receptor localization and density in adult brain. 4-8-week-old male mice were exposed to 20 percent EtOH over a period of 4 weeks, and receptor localization was examined after 4 weeks in the hippocampal CA1 stratum radiatum by pre-embedding immunoelectron microscopy. Our results revealed a significant reduction in CB1 receptor immunoparticles in astrocytic processes of EtOH-exposed mice when compared with controls (positive astrocyte elements: 21.50 ± 2.80 percent versus 37.22 ± 3.12 percent, respectively), as well as a reduction in particle density (0.24 ± 0.02 versus 0.35 ± 0.02 particles/μm). The majority of CB1 receptor metal particles were in the range of 400-1200 nm from synaptic terminals in both control and EtOH. Altogether, the decrease in the CB1 receptor expression in hippocampal astrocytes of adult mice exposed to EtOH during adolescence reveals a long lasting effect of EtOH on astrocytic CB1 receptors. This deficiency may also have negative consequences for synaptic function.
Collapse
Affiliation(s)
- Itziar Bonilla-Del Rίo
- Department of Neurosciences, Faculty of Medicine and Nursing; University of the Basque Country UPV/EHU; Spain
- Achucarro Basque Center for Neuroscience; Science Park of the UPV/EHU; Spain
| | - Nagore Puente
- Department of Neurosciences, Faculty of Medicine and Nursing; University of the Basque Country UPV/EHU; Spain
- Achucarro Basque Center for Neuroscience; Science Park of the UPV/EHU; Spain
| | - Sara Peñasco
- Department of Neurosciences, Faculty of Medicine and Nursing; University of the Basque Country UPV/EHU; Spain
- Achucarro Basque Center for Neuroscience; Science Park of the UPV/EHU; Spain
| | - Irantzu Rico
- Department of Neurosciences, Faculty of Medicine and Nursing; University of the Basque Country UPV/EHU; Spain
- Achucarro Basque Center for Neuroscience; Science Park of the UPV/EHU; Spain
| | - Ana Gutiérrez-Rodrίguez
- Department of Neurosciences, Faculty of Medicine and Nursing; University of the Basque Country UPV/EHU; Spain
- Achucarro Basque Center for Neuroscience; Science Park of the UPV/EHU; Spain
| | - Izaskun Elezgarai
- Department of Neurosciences, Faculty of Medicine and Nursing; University of the Basque Country UPV/EHU; Spain
- Achucarro Basque Center for Neuroscience; Science Park of the UPV/EHU; Spain
| | - Almudena Ramos
- Department of Neurosciences, Faculty of Medicine and Nursing; University of the Basque Country UPV/EHU; Spain
- Achucarro Basque Center for Neuroscience; Science Park of the UPV/EHU; Spain
| | - Leire Reguero
- Department of Neurosciences, Faculty of Medicine and Nursing; University of the Basque Country UPV/EHU; Spain
- Achucarro Basque Center for Neuroscience; Science Park of the UPV/EHU; Spain
| | - Inmaculada Gerrikagoitia
- Department of Neurosciences, Faculty of Medicine and Nursing; University of the Basque Country UPV/EHU; Spain
- Achucarro Basque Center for Neuroscience; Science Park of the UPV/EHU; Spain
| | | | | | - Pedro Grandes
- Department of Neurosciences, Faculty of Medicine and Nursing; University of the Basque Country UPV/EHU; Spain
- Achucarro Basque Center for Neuroscience; Science Park of the UPV/EHU; Spain
- Division of Medical Sciences; University of Victoria; Canada
| |
Collapse
|
12
|
Abrahao KP, Salinas AG, Lovinger DM. Alcohol and the Brain: Neuronal Molecular Targets, Synapses, and Circuits. Neuron 2017; 96:1223-1238. [PMID: 29268093 PMCID: PMC6566861 DOI: 10.1016/j.neuron.2017.10.032] [Citation(s) in RCA: 259] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/30/2017] [Accepted: 10/27/2017] [Indexed: 12/13/2022]
Abstract
Ethanol is one of the most commonly abused drugs. Although environmental and genetic factors contribute to the etiology of alcohol use disorders, it is ethanol's actions in the brain that explain (1) acute ethanol-related behavioral changes, such as stimulant followed by depressant effects, and (2) chronic changes in behavior, including escalated use, tolerance, compulsive seeking, and dependence. Our knowledge of ethanol use and abuse thus relies on understanding its effects on the brain. Scientists have employed both bottom-up and top-down approaches, building from molecular targets to behavioral analyses and vice versa, respectively. This review highlights current progress in the field, focusing on recent and emerging molecular, cellular, and circuit effects of the drug that impact ethanol-related behaviors. The focus of the field is now on pinpointing which molecular effects in specific neurons within a brain region contribute to behavioral changes across the course of acute and chronic ethanol exposure.
Collapse
Affiliation(s)
- Karina P Abrahao
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - Armando G Salinas
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - David M Lovinger
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA.
| |
Collapse
|
13
|
Varodayan FP, Logrip ML, Roberto M. P/Q-type voltage-gated calcium channels mediate the ethanol and CRF sensitivity of central amygdala GABAergic synapses. Neuropharmacology 2017; 125:197-206. [PMID: 28734867 DOI: 10.1016/j.neuropharm.2017.07.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 07/14/2017] [Accepted: 07/17/2017] [Indexed: 01/09/2023]
Abstract
The central amygdala (CeA) GABAergic system is hypothesized to drive the development of alcohol dependence, due to its pivotal roles in the reinforcing actions of alcohol and the expression of negative emotion, anxiety and stress. Recent work has also identified an important role for the CeA corticotropin-releasing factor (CRF) system in the interaction between anxiety/stress and alcohol dependence. We have previously shown that acute alcohol and CRF each increase action potential-independent GABA release in the CeA via their actions at presynaptic CRF type 1 receptors (CRF1s); however, the shared mechanism employed by these two compounds requires further investigation. Here we report that acute alcohol interacts with the CRF/CRF1 system, such that CRF and alcohol act via presynaptic CRF1s and P/Q-type voltage-gated calcium channels to promote vesicular GABA release and that both compounds occlude the effects of each other at these synapses. Chronic alcohol exposure does not alter P/Q-type voltage-gated calcium channel membrane abundance or this CRF1/P/Q-type voltage-gated calcium channel mechanism of acute alcohol-induced GABA release, indicating that alcohol engages this molecular mechanism at CeA GABAergic synapses throughout the transition to dependence. Thus, P/Q-type voltage-gated calcium channels, like CRF1s, are key regulators of the effects of alcohol on GABAergic signaling in the CeA.
Collapse
Affiliation(s)
- F P Varodayan
- The Scripps Research Institute, Department of Neuroscience, La Jolla, CA 92037, USA.
| | - M L Logrip
- The Scripps Research Institute, Department of Neuroscience, La Jolla, CA 92037, USA
| | - M Roberto
- The Scripps Research Institute, Department of Neuroscience, La Jolla, CA 92037, USA
| |
Collapse
|
14
|
Varodayan FP, Bajo M, Soni N, Luu G, Madamba SG, Schweitzer P, Roberto M. Chronic alcohol exposure disrupts CB 1 regulation of GABAergic transmission in the rat basolateral amygdala. Addict Biol 2017; 22:766-778. [PMID: 26786379 DOI: 10.1111/adb.12369] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 11/18/2015] [Accepted: 12/14/2015] [Indexed: 01/08/2023]
Abstract
The basolateral nucleus of the amygdala (BLA) is critical to the pathophysiology of anxiety-driven alcohol drinking and relapse. The endogenous cannabinoid/type 1 cannabinoid receptor (eCB/CB1 ) system curbs BLA-driven anxiety and stress responses via a retrograde negative feedback system that inhibits neurotransmitter release, and BLA CB1 activation reduces GABA release and drives anxiogenesis. Additionally, decreased amygdala CB1 is observed in abstinent alcoholic patients and ethanol withdrawn rats. Here, we investigated the potential disruption of eCB/CB1 signaling on GABAergic transmission in BLA pyramidal neurons of rats exposed to 2-3 weeks intermittent ethanol. In the naïve rat BLA, the CB1 agonist WIN 55,212-2 (WIN) decreased GABA release, and this effect was prevented by the CB1 antagonist AM251. AM251 alone increased GABA release via a mechanism requiring postsynaptic calcium-dependent activity. This retrograde tonic eCB/CB1 signaling was diminished in chronic ethanol exposed rats, suggesting a functional impairment of the eCB/CB1 system. In contrast, acute ethanol increased GABAergic transmission similarly in naïve and chronic ethanol exposed rats, via both presynaptic and postsynaptic mechanisms. Notably, CB1 activation impaired ethanol's facilitation of GABAergic transmission across both groups, but the AM251-induced and ethanol-induced facilitation of GABA release was additive, suggesting independent presynaptic sites of action. Collectively, the present findings highlight a critical CB1 influence on BLA GABAergic transmission that is dysregulated by chronic ethanol exposure and, thus, may contribute to the alcohol-dependent state.
Collapse
Affiliation(s)
- Florence P. Varodayan
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
| | - Michal Bajo
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
| | - Neeraj Soni
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
- Faculty of Health and Medical Sciences; University of Copenhagen (UCPH); Denmark
| | - George Luu
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
| | - Samuel G. Madamba
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
| | - Paul Schweitzer
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
| | - Marisa Roberto
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
| |
Collapse
|
15
|
Lovinger DM, Alvarez VA. Alcohol and basal ganglia circuitry: Animal models. Neuropharmacology 2017; 122:46-55. [PMID: 28341206 DOI: 10.1016/j.neuropharm.2017.03.023] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 03/16/2017] [Accepted: 03/20/2017] [Indexed: 01/18/2023]
Abstract
Brain circuits that include the cortex and basal ganglia make up the bulk of the forebrain, and influence behaviors related to almost all aspects of affective, cognitive and sensorimotor functions. The learning of new actions as well as association of existing action repertoires with environmental events are key functions of this circuitry. Unfortunately, the cortico-basal ganglia circuitry is also the target for all drugs of abuse, including alcohol. This makes the circuitry susceptible to the actions of chronic alcohol exposure that impairs circuit function in ways that contribute to cognitive dysfunction and drug use disorders. In the present review, we describe the connectivity and functions of the associative, limbic and sensorimotor cortico-basal ganglia circuits. We then review the effects of acute and chronic alcohol exposure on circuit function. Finally, we review studies examining the roles of the different circuits and circuit elements in alcohol use and abuse. We attempt to synthesize information from a variety of studies in laboratory animals and humans to generate hypotheses about how the three circuits interact with each other and with the other brain circuits during exposure to alcohol and during the development of alcohol use disorders. This article is part of the Special Issue entitled "Alcoholism".
Collapse
Affiliation(s)
- David M Lovinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, United States.
| | - Veronica A Alvarez
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, United States
| |
Collapse
|
16
|
Roberto M, Varodayan FP. Synaptic targets: Chronic alcohol actions. Neuropharmacology 2017; 122:85-99. [PMID: 28108359 DOI: 10.1016/j.neuropharm.2017.01.013] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 12/23/2016] [Accepted: 01/14/2017] [Indexed: 01/02/2023]
Abstract
Alcohol acts on numerous cellular and molecular targets to regulate neuronal communication within the brain. Chronic alcohol exposure and acute withdrawal generate prominent neuroadaptations at synapses, including compensatory effects on the expression, localization and function of synaptic proteins, channels and receptors. The present article reviews the literature describing the synaptic effects of chronic alcohol exposure and their relevance for synaptic transmission in the central nervous system. This review is not meant to be comprehensive, but rather to highlight the effects that have been observed most consistently and that are thought to contribute to the development of alcohol dependence and the negative aspects of withdrawal. Specifically, we will focus on the major excitatory and inhibitory neurotransmitters in the brain, glutamate and GABA, respectively, and how their neuroadaptations after chronic alcohol exposure contributes to alcohol reinforcement, dependence and withdrawal. This article is part of the Special Issue entitled "Alcoholism".
Collapse
|
17
|
Johnson KA, Lovinger DM. Presynaptic G Protein-Coupled Receptors: Gatekeepers of Addiction? Front Cell Neurosci 2016; 10:264. [PMID: 27891077 PMCID: PMC5104741 DOI: 10.3389/fncel.2016.00264] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 10/31/2016] [Indexed: 12/21/2022] Open
Abstract
Drug abuse and addiction cause widespread social and public health problems, and the neurobiology underlying drug actions and drug use and abuse is an area of intensive research. Drugs of abuse alter synaptic transmission, and these actions contribute to acute intoxication as well as the chronic effects of abused substances. Transmission at most mammalian synapses involves neurotransmitter activation of two receptor subtypes, ligand-gated ion channels that mediate fast synaptic responses and G protein-coupled receptors (GPCRs) that have slower neuromodulatory actions. The GPCRs represent a large proportion of neurotransmitter receptors involved in almost all facets of nervous system function. In addition, these receptors are targets for many pharmacotherapeutic agents. Drugs of abuse directly or indirectly affect neuromodulation mediated by GPCRs, with important consequences for intoxication, drug taking and responses to prolonged drug exposure, withdrawal and addiction. Among the GPCRs are several subtypes involved in presynaptic inhibition, most of which are coupled to the Gi/o class of G protein. There is increasing evidence that these presynaptic Gi/o-coupled GPCRs have important roles in the actions of drugs of abuse, as well as behaviors related to these drugs. This topic will be reviewed, with particular emphasis on receptors for three neurotransmitters, Dopamine (DA; D1- and D2-like receptors), Endocannabinoids (eCBs; CB1 receptors) and glutamate (group II metabotropic glutamate (mGlu) receptors). The focus is on recent evidence from laboratory animal models (and some evidence in humans) implicating these receptors in the acute and chronic effects of numerous abused drugs, as well as in the control of drug seeking and taking. The ability of drugs targeting these receptors to modify drug seeking behavior has raised the possibility of using compounds targeting these receptors for addiction pharmacotherapy. This topic is also discussed, with emphasis on development of mGlu2 positive allosteric modulators (PAMs).
Collapse
Affiliation(s)
- Kari A. Johnson
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of HealthBethesda, MD, USA
| | - David M. Lovinger
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of HealthBethesda, MD, USA
| |
Collapse
|
18
|
Abstract
The endocannabinoid system (ECS) is abundantly expressed in the brain. This system regulates a plethora of physiological functions and is composed of cannabinoid receptors, their endogenous ligands (endocannabinoids), and the enzymes involved in the metabolism of endocannabinoids. In this review, we highlight the new advances in cannabinoid signaling, focusing on a key component of the ECS, the type-1 cannabinoid receptor (CB
1). In recent years, the development of new imaging and molecular tools has demonstrated that this receptor can be distributed in many cell types (e.g., neuronal or glial cells) and intracellular compartments (e.g., mitochondria). Interestingly, cellular and molecular effects are differentially mediated by CB
1 receptors according to their specific localization (e.g., glutamatergic or GABAergic neurons). Moreover, this receptor is expressed in the periphery, where it can modulate periphery-brain connections. Finally, the better understanding of the CB
1 receptor structure led researchers to propose interesting and new allosteric modulators. Thus, the advances and the new directions of the CB
1 receptor field will provide new insights and better approaches to profit from its interesting therapeutic profile.
Collapse
Affiliation(s)
- Arnau Busquets Garcia
- Endocannabinoids and Neuroadaptation, INSERM U1215 NeuroCentre Magendie, Bordeaux, 33077, France; University of Bordeaux, Bordeaux, France
| | - Edgar Soria-Gomez
- Endocannabinoids and Neuroadaptation, INSERM U1215 NeuroCentre Magendie, Bordeaux, 33077, France; University of Bordeaux, Bordeaux, France
| | - Luigi Bellocchio
- Endocannabinoids and Neuroadaptation, INSERM U1215 NeuroCentre Magendie, Bordeaux, 33077, France; University of Bordeaux, Bordeaux, France
| | - Giovanni Marsicano
- Endocannabinoids and Neuroadaptation, INSERM U1215 NeuroCentre Magendie, Bordeaux, 33077, France; University of Bordeaux, Bordeaux, France
| |
Collapse
|