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Quintanilla ME, Israel Y. Role of Metabolism on Alcohol Preference, Addiction, and Treatment. Curr Top Behav Neurosci 2023. [PMID: 37221350 DOI: 10.1007/7854_2023_422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Studies presented in this chapter show that: (1) in the brain, ethanol is metabolized by catalase to acetaldehyde, which condenses with dopamine forming salsolinol; (2) acetaldehyde-derived salsolinol increases the release of dopamine mediating, via opioid receptors, the reinforcing effects of ethanol during the acquisition of ethanol consumption, while (3) brain acetaldehyde does not influence the maintenance of chronic ethanol intake, it is suggested that a learned cue-induced hyperglutamatergic system takes precedence over the dopaminergic system. However, (4) following a prolonged ethanol deprivation, the generation of acetaldehyde in the brain again plays a role, contributing to the increase in ethanol intake observed during ethanol re-access, called the alcohol deprivation effect (ADE), a model of relapse behavior; (5) naltrexone inhibits the high ethanol intake seen in the ADE condition, suggesting that acetaldehyde-derived salsolinol via opioid receptors also contributes to the relapse-like drinking behavior. The reader is referred to glutamate-mediated mechanisms that trigger the cue-associated alcohol-seeking and that also contribute to triggering relapse.
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Affiliation(s)
- María Elena Quintanilla
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile.
| | - Yedy Israel
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile
- Centro de Medicina Regenerativa, ICM Clinica Alemana-Universidad de Desarrollo, Santiago, Chile
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2
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Holbrook OT, Molligoda B, Bushell KN, Gobrogge KL. Behavioral consequences of the downstream products of ethanol metabolism involved in alcohol use disorder. Neurosci Biobehav Rev 2021; 133:104501. [PMID: 34942269 DOI: 10.1016/j.neubiorev.2021.12.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 12/08/2021] [Accepted: 12/12/2021] [Indexed: 01/04/2023]
Abstract
Research concerning Alcohol Use Disorder (AUD) has previously focused primarily on either the behavioral or chemical consequences experienced following ethanol intake, but these areas of research have rarely been considered in tandem. Compared with other drugs of abuse, ethanol has been shown to have a unique metabolic pathway once it enters the body, which leads to the formation of downstream metabolites which can go on to form biologically active products. These metabolites can mediate a variety of behavioral responses that are commonly observed with AUD, such as ethanol intake, reinforcement, and vulnerability to relapse. The following review considers the preclinical and chemical research implicating these downstream products in AUD and proposes a chemobehavioral model of AUD.
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Affiliation(s)
- Otto T Holbrook
- Program in Neuroscience, Boston University, Boston, MA, 02215-2425, USA.
| | - Brandon Molligoda
- Program in Neuroscience, Boston University, Boston, MA, 02215-2425, USA.
| | - Kristen N Bushell
- Program in Neuroscience, Boston University, Boston, MA, 02215-2425, USA
| | - Kyle L Gobrogge
- Program in Neuroscience, Boston University, Boston, MA, 02215-2425, USA
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3
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Bassareo V, Frau R, Maccioni R, Caboni P, Manis C, Peana AT, Migheli R, Porru S, Acquas E. Ethanol-Dependent Synthesis of Salsolinol in the Posterior Ventral Tegmental Area as Key Mechanism of Ethanol's Action on Mesolimbic Dopamine. Front Neurosci 2021; 15:675061. [PMID: 34262429 PMCID: PMC8273231 DOI: 10.3389/fnins.2021.675061] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/18/2021] [Indexed: 12/16/2022] Open
Abstract
Abnormal consumption of ethanol, the ingredient responsible for alcoholic drinks' addictive liability, causes millions of deaths yearly. Ethanol's addictive potential is triggered through activation, by a still unknown mechanism, of the mesolimbic dopamine (DA) system, part of a key motivation circuit, DA neurons in the posterior ventral tegmental area (pVTA) projecting to the ipsilateral nucleus accumbens shell (AcbSh). The present in vivo brain microdialysis study, in dually-implanted rats with one probe in the pVTA and another in the ipsilateral or contralateral AcbSh, demonstrates this mechanism. As a consequence of the oral administration of a pharmacologically relevant dose of ethanol, we simultaneously detect a) in the pVTA, a substance, 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (salsolinol), untraceable under control conditions, product of condensation between DA and ethanol's first by-product, acetaldehyde; and b) in the AcbSh, a significant increase of DA release. Moreover, such newly generated salsolinol in the pVTA is responsible for increasing AcbSh DA release via μ opioid receptor (μOR) stimulation. In fact, inhibition of salsolinol's generation in the pVTA or blockade of pVTA μORs prevents ethanol-increased ipsilateral, but not contralateral, AcbSh DA release. This evidence discloses the long-sought key mechanism of ethanol's addictive potential and suggests the grounds for developing preventive and therapeutic strategies against abnormal consumption.
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Affiliation(s)
- Valentina Bassareo
- Center of Excellence for the Study of Neurobiology of Addiction, University of Cagliari, Cagliari, Italy.,Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - Roberto Frau
- Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - Riccardo Maccioni
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Pierluigi Caboni
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Cristina Manis
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Alessandra T Peana
- Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy
| | - Rossana Migheli
- Department of Experimental Medical and Surgical Sciences, University of Sassari, Sassari, Italy
| | - Simona Porru
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Elio Acquas
- Center of Excellence for the Study of Neurobiology of Addiction, University of Cagliari, Cagliari, Italy.,Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
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Lorente JD, Cuitavi J, Campos-Jurado Y, Hipólito L. Pain-induced alterations in the dynorphinergic system within the mesocorticolimbic pathway: Implication for alcohol addiction. J Neurosci Res 2020; 100:165-182. [PMID: 32770601 DOI: 10.1002/jnr.24703] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 06/08/2020] [Accepted: 07/09/2020] [Indexed: 12/13/2022]
Abstract
Latest studies have revealed that pain negatively impacts on reward processing and motivation leading to negative affective states and stress. These states not only reduce quality of life of patients by increasing the appearance of psychiatric comorbidities, but also have an important impact on vulnerability to drug abuse, including alcohol. In fact, clinical, epidemiological but also preclinical studies have revealed that the presence of pain is closely related to alcohol use disorders (AUDs). All this evidence suggests that pain is a factor that increases the risk of suffering AUD, predicting heavy drinking behavior and relapse drinking in those patients with a previous history of AUD. The negative consequences of chronic pain and its impact on stress and AUD are likely mediated by alterations in the central nervous system, especially in the stress and reward systems. Therefore, pain and stress impact on dopaminergic mesolimbic pathway can lead to an increase in drug abuse liability. In this mini review we analyze the interaction between pain, stress, and alcohol addiction, and how dynamic changes in the kappa opioid system might play a crucial role in the development of compulsive alcohol drinking in chronic pain patients.
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Affiliation(s)
- Jesús David Lorente
- Department of Pharmacy and Pharmaceutical Technology and Parasitology, University of València, Burjassot, Spain
| | - Javier Cuitavi
- Department of Pharmacy and Pharmaceutical Technology and Parasitology, University of València, Burjassot, Spain
| | - Yolanda Campos-Jurado
- Department of Pharmacy and Pharmaceutical Technology and Parasitology, University of València, Burjassot, Spain
| | - Lucía Hipólito
- Department of Pharmacy and Pharmaceutical Technology and Parasitology, University of València, Burjassot, Spain
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Campos-Jurado Y, Martí-Prats L, Morón JA, Polache A, Granero L, Hipólito L. Dose-dependent induction of CPP or CPA by intra-pVTA ethanol: Role of mu opioid receptors and effects on NMDA receptors. Prog Neuropsychopharmacol Biol Psychiatry 2020; 100:109875. [PMID: 31978422 PMCID: PMC7096259 DOI: 10.1016/j.pnpbp.2020.109875] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 01/16/2020] [Accepted: 01/21/2020] [Indexed: 12/16/2022]
Abstract
The neurobiological mechanisms underlying alcohol motivational properties are still not fully understood, however, the mu-opioid receptors (MORs) have been evidenced as central elements in the manifestation of the alcohol reinforcing properties. Drug-associated environmental stimuli can trigger alcohol relapse and promote alcohol consumption whereby N-methyl-d-aspartate (NMDA) receptors play a pivotal role. Here we sought to demonstrate, for the first time, that ethanol induces conditioned place preference or aversion (CPP or CPA) when administered locally into the ventral tegmental area (VTA) and the associated role of MORs. We further analyzed the changes in the expression and mRNA levels of GluN1 and GluN2A subunits in designated brain areas. The expression of CPP or CPA was characterized following intra-VTA ethanol administration and we showed that either reinforcing (CPP) or aversive (CPA) properties are dependent on the dose administered (ranging here from 35 to 300 nmol). Furthermore, the critical contribution of local MORs in the acquisition of CPP was revealed by a selective antagonist, namely β-Funaltrexamine. Finally, modifications of the expression of NMDA receptor subunits in the Nucleus Accumbens (NAc) and Hippocampus after ethanol-induced CPP were analyzed at the proteomic and transcriptomic levels by western blot and In Situ Hybridation RNAscope techniques, respectively. Results showed that the mRNA levels of GluN2A but not GluN1 in NAc are higher after ethanol CPP. These novel results pave the way for further characterisation of the mechanisms by which ethanol motivational properties are associated with learned environmental cues.
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Affiliation(s)
- Yolanda Campos-Jurado
- Department of Pharmacy and Pharmaceutical Tech. and Parasit., University of València, Spain
| | - Lucía Martí-Prats
- Department of Pharmacy and Pharmaceutical Tech. and Parasit., University of València, Spain
| | - Jose A Morón
- Department of Anesthesiology, Washington University Pain Center, Washington University in St. Louis, School of Medicine, St. Louis, MO 63110, USA; Department of Neuroscience, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Ana Polache
- Department of Pharmacy and Pharmaceutical Tech. and Parasit., University of València, Spain
| | - Luis Granero
- Department of Pharmacy and Pharmaceutical Tech. and Parasit., University of València, Spain
| | - Lucía Hipólito
- Department of Pharmacy and Pharmaceutical Tech. and Parasit., University of València, Spain.
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Peana AT, Bassareo V, Acquas E. Not Just from Ethanol. Tetrahydroisoquinolinic (TIQ) Derivatives: from Neurotoxicity to Neuroprotection. Neurotox Res 2019; 36:653-668. [DOI: 10.1007/s12640-019-00051-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 03/29/2019] [Accepted: 04/21/2019] [Indexed: 12/12/2022]
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The new kisspeptin derivative - kissorphin (KSO) - attenuates acute hyperlocomotion and sensitization induced by ethanol and morphine in mice. Alcohol 2017; 64:45-53. [PMID: 28965655 DOI: 10.1016/j.alcohol.2017.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 04/10/2017] [Accepted: 04/24/2017] [Indexed: 12/25/2022]
Abstract
Kissorphin (KSO) is a new peptide derived from kisspeptin-10. This peptide possesses neuropeptide FF (NPFF)-like biological activity in vitro; NPFF, in many cases, inhibits opioid and ethanol effects in rodents. Therefore, the current study explored the influence of KSO on acute ethanol- and morphine-induced hyperactivity, and on the development and expression of locomotor sensitization induced by these drugs. In the present study, sensitization to locomotor effects was induced by repeated exposure to ethanol (2.4 g/kg, intraperitoneally [i.p.], 1 × 4 days) or morphine (10 mg/kg, subcutaneously [s.c.], 1 × 7 days). We found that KSO (1-10 nmol/300 μL, intravenously [i.v.]) did not have an impact on locomotor activity of naïve mice. However, it reduced both acute ethanol- (10 nmol/300 μL) and morphine-induced hyperactivity (3 and 10 nmol/300 μL). Pretreatment of animals with KSO (10 nmol/300 μL), before every ethanol or morphine injection during development of sensitization or before the ethanol or morphine challenge, attenuated the development, as well as the expression of locomotor sensitization to both substances. Moreover, prior administration of the NPFF receptor antagonist RF9 (10 nmol/300 μL, i.v.) inhibited the ability of KSO (10 nmol/300 μL) to reduce the expression of ethanol and morphine sensitization. KSO given alone, at all used doses, did not influence the motor coordination measured via the rotarod test. The results from this study show that KSO effectively attenuated acute and repeated effects of ethanol and morphine. Thus, KSO possesses NPFF-like anti-opioid activity in these behavioral studies.
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Kurnik-Łucka M, Panula P, Bugajski A, Gil K. Salsolinol: an Unintelligible and Double-Faced Molecule-Lessons Learned from In Vivo and In Vitro Experiments. Neurotox Res 2017; 33:485-514. [PMID: 29063289 PMCID: PMC5766726 DOI: 10.1007/s12640-017-9818-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 08/19/2017] [Accepted: 09/08/2017] [Indexed: 12/29/2022]
Abstract
Salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline) is a tetrahydroisoquinoline derivative whose presence in humans was first detected in the urine of Parkinsonian patients on l-DOPA (l-dihydroxyphenylalanine) medication. Thus far, multiple hypotheses regarding its physiological/pathophysiological roles have been proposed, especially related to Parkinson’s disease or alcohol addiction. The aim of this review was to outline studies related to salsolinol, with special focus on in vivo and in vitro experimental models. To begin with, the chemical structure of salsolinol together with its biochemical implications and the role in neurotransmission are discussed. Numerous experimental studies are summarized in tables and the most relevant ones are stressed. Finally, the ability of salsolinol to cross the blood–brain barrier and its possible double-faced neurobiological potential are reviewed.
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Affiliation(s)
- Magdalena Kurnik-Łucka
- Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 30-121, Krakow, Poland.
| | - Pertti Panula
- Department of Anatomy and Neuroscience Centre, University of Helsinki, Helsinki, Finland
| | - Andrzej Bugajski
- Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 30-121, Krakow, Poland
| | - Krzysztof Gil
- Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 30-121, Krakow, Poland
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Peana AT, Pintus FA, Bennardini F, Rocchitta G, Bazzu G, Serra PA, Porru S, Rosas M, Acquas E. Is catalase involved in the effects of systemic and pVTA administration of 4-methylpyrazole on ethanol self-administration? Alcohol 2017; 63:61-73. [PMID: 28847383 DOI: 10.1016/j.alcohol.2017.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 01/31/2017] [Accepted: 04/03/2017] [Indexed: 12/31/2022]
Abstract
The oxidative metabolism of ethanol into acetaldehyde involves several enzymes, including alcohol dehydrogenase (ADH) and catalase-hydrogen peroxide (H2O2). In this regard, while it is well known that 4-methylpyrazole (4-MP) acts by inhibiting ADH in the liver, little attention has been placed on its ability to interfere with fatty acid oxidation-mediated generation of H2O2, a mechanism that may indirectly affect catalase whose enzymatic activity requires H2O2. The aim of our investigation was twofold: 1) to evaluate the effect of systemic (i.p. [intraperitoneal]) and local (into the posterior ventral tegmental area, pVTA) administration of 4-MP on oral ethanol self-administration, and 2) to assess ex vivo whether or not systemic 4-MP affects liver and brain H2O2 availability. The results show that systemic 4-MP reduced ethanol but not acetaldehyde or saccharin self-administration, and decreased the ethanol deprivation effect. Moreover, local intra-pVTA administration of 4-MP reduced ethanol but not saccharin self-administration. In addition, although unable to affect basal catalase activity, systemic administration of 4-MP decreased H2O2 availability both in liver and in brain. Overall, these results indicate that 4-MP interferes with ethanol self-administration and suggest that its behavioral effects could be due to a decline in catalase-H2O2 system activity as a result of a reduction of H2O2 availability, thus highlighting the role of central catalase-mediated metabolism of ethanol and further supporting the key role of acetaldehyde in the reinforcing properties of ethanol.
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Peana AT, Sánchez-Catalán MJ, Hipólito L, Rosas M, Porru S, Bennardini F, Romualdi P, Caputi FF, Candeletti S, Polache A, Granero L, Acquas E. Mystic Acetaldehyde: The Never-Ending Story on Alcoholism. Front Behav Neurosci 2017; 11:81. [PMID: 28553209 PMCID: PMC5425597 DOI: 10.3389/fnbeh.2017.00081] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 04/18/2017] [Indexed: 12/12/2022] Open
Abstract
After decades of uncertainties and drawbacks, the study on the role and significance of acetaldehyde in the effects of ethanol seemed to have found its main paths. Accordingly, the effects of acetaldehyde, after its systemic or central administration and as obtained following ethanol metabolism, looked as they were extensively characterized. However, almost 5 years after this research appeared at its highest momentum, the investigations on this topic have been revitalized on at least three main directions: (1) the role and the behavioral significance of acetaldehyde in different phases of ethanol self-administration and in voluntary ethanol consumption; (2) the distinction, in the central effects of ethanol, between those arising from its non-metabolized fraction and those attributable to ethanol-derived acetaldehyde; and (3) the role of the acetaldehyde-dopamine condensation product, salsolinol. The present review article aims at presenting and discussing prospectively the most recent data accumulated following these three research pathways on this never-ending story in order to offer the most up-to-date synoptic critical view on such still unresolved and exciting topic.
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Affiliation(s)
| | - María J. Sánchez-Catalán
- Department of Pharmacy, Pharmaceutical Technology and Parasitology, University of ValenciaValència, Spain
| | - Lucia Hipólito
- Department of Pharmacy, Pharmaceutical Technology and Parasitology, University of ValenciaValència, Spain
| | - Michela Rosas
- Department of Life and Environmental Sciences, University of CagliariCagliari, Italy
| | - Simona Porru
- Department of Life and Environmental Sciences, University of CagliariCagliari, Italy
| | | | - Patrizia Romualdi
- Department of Pharmacy and Biotechnology, University of BolognaBologna, Italy
| | - Francesca F. Caputi
- Department of Pharmacy and Biotechnology, University of BolognaBologna, Italy
| | - Sanzio Candeletti
- Department of Pharmacy and Biotechnology, University of BolognaBologna, Italy
| | - Ana Polache
- Department of Pharmacy, Pharmaceutical Technology and Parasitology, University of ValenciaValència, Spain
| | - Luis Granero
- Department of Pharmacy, Pharmaceutical Technology and Parasitology, University of ValenciaValència, Spain
| | - Elio Acquas
- Department of Life and Environmental Sciences, University of CagliariCagliari, Italy
- Centre of Excellence on Neurobiology of Addiction, University of CagliariCagliari, Italy
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Israel Y, Karahanian E, Ezquer F, Morales P, Ezquer M, Rivera-Meza M, Herrera-Marschitz M, Quintanilla ME. Acquisition, Maintenance and Relapse-Like Alcohol Drinking: Lessons from the UChB Rat Line. Front Behav Neurosci 2017; 11:57. [PMID: 28420969 PMCID: PMC5378819 DOI: 10.3389/fnbeh.2017.00057] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 03/20/2017] [Indexed: 12/31/2022] Open
Abstract
This review article addresses the biological factors that influence: (i) the acquisition of alcohol intake; (ii) the maintenance of chronic alcohol intake; and (iii) alcohol relapse-like drinking behavior in animals bred for their high-ethanol intake. Data from several rat strains/lines strongly suggest that catalase-mediated brain oxidation of ethanol into acetaldehyde is an absolute requirement (up 80%–95%) for rats to display ethanol’s reinforcing effects and to initiate chronic ethanol intake. Acetaldehyde binds non-enzymatically to dopamine forming salsolinol, a compound that is self-administered. In UChB rats, salsolinol: (a) generates marked sensitization to the motivational effects of ethanol; and (b) strongly promotes binge-like drinking. The specificity of salsolinol actions is shown by the finding that only the R-salsolinol enantiomer but not S-salsolinol accounted for the latter effects. Inhibition of brain acetaldehyde synthesis does not influence the maintenance of chronic ethanol intake. However, a prolonged ethanol withdrawal partly returns the requirement for acetaldehyde synthesis/levels both on chronic ethanol intake and on alcohol relapse-like drinking. Chronic ethanol intake, involving the action of lipopolysaccharide diffusing from the gut, and likely oxygen radical generated upon catechol/salsolinol oxidation, leads to oxidative stress and neuro-inflammation, known to potentiate each other. Data show that the administration of N-acetyl cysteine (NAC) a strong antioxidant inhibits chronic ethanol maintenance by 60%–70%, without inhibiting its initial intake. Intra-cerebroventricular administration of mesenchymal stem cells (MSCs), known to release anti-inflammatory cytokines, to elevate superoxide dismutase levels and to reverse ethanol-induced hippocampal injury and cognitive deficits, also inhibited chronic ethanol maintenance; further, relapse-like ethanol drinking was inhibited up to 85% for 40 days following intracerebral stem cell administration. Thus: (i) ethanol must be metabolized intracerebrally into acetaldehyde, and further into salsolinol, which appear responsible for promoting the acquisition of the early reinforcing effects of ethanol; (ii) acetaldehyde is not responsible for the maintenance of chronic ethanol intake, while other mechanisms are indicated; (iii) the systemic administration of NAC, a strong antioxidant markedly inhibits the maintenance of chronic ethanol intake; and (iv) the intra-cerebroventricular administration of anti-inflammatory and antioxidant MSCs inhibit both the maintenance of chronic ethanol intake and relapse-like drinking.
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Affiliation(s)
- Yedy Israel
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Sciences, University of ChileSantiago, Chile
| | - Eduardo Karahanian
- Center for Biomedical Research, Universidad Autónoma de ChileSantiago, Chile
| | - Fernando Ezquer
- Centro de Medicina Regenerativa, Facultad de Medicina Clínica Alemana-Universidad del DesarrolloSantiago, Chile
| | - Paola Morales
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Sciences, University of ChileSantiago, Chile
| | - Marcelo Ezquer
- Centro de Medicina Regenerativa, Facultad de Medicina Clínica Alemana-Universidad del DesarrolloSantiago, Chile
| | - Mario Rivera-Meza
- Department of Pharmacological and Toxicological Chemistry, Faculty of Chemical and Pharmaceutical Sciences, University of ChileSantiago, Chile
| | - Mario Herrera-Marschitz
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Sciences, University of ChileSantiago, Chile
| | - María E Quintanilla
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Sciences, University of ChileSantiago, Chile
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Sánchez-Catalán MJ, Orrico A, Hipólito L, Zornoza T, Polache A, Lanuza E, Martínez-García F, Granero L, Agustín-Pavón C. Glutamate and Opioid Antagonists Modulate Dopamine Levels Evoked by Innately Attractive Male Chemosignals in the Nucleus Accumbens of Female Rats. Front Neuroanat 2017; 11:8. [PMID: 28280461 PMCID: PMC5322247 DOI: 10.3389/fnana.2017.00008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 02/09/2017] [Indexed: 12/04/2022] Open
Abstract
Sexual chemosignals detected by vomeronasal and olfactory systems mediate intersexual attraction in rodents, and act as a natural reinforcer to them. The mesolimbic pathway processes natural rewards, and the nucleus accumbens receives olfactory information via glutamatergic projections from the amygdala. Thus, the aim of this study was to investigate the involvement of the mesolimbic pathway in the attraction toward sexual chemosignals. Our data show that female rats with no previous experience with males or their chemosignals display an innate preference for male-soiled bedding. Focal administration of the opioid antagonist β-funaltrexamine into the posterior ventral tegmental area does not affect preference for male chemosignals. Nevertheless, exposure to male-soiled bedding elicits an increase in dopamine efflux in the nucleus accumbens shell and core, measured by microdialysis. Infusion of the opioid antagonist naltrexone in the accumbens core does not significantly affect dopamine efflux during exposure to male chemosignals, although it enhances dopamine levels 40 min after withdrawal of the stimuli. By contrast, infusion of the glutamate antagonist kynurenic acid in the accumbens shell inhibits the release of dopamine and reduces the time that females spend investigating male-soiled bedding. These data are in agreement with previous reports in male rats showing that exposure to opposite-sex odors elicits dopamine release in the accumbens, and with data in female mice showing that the behavioral preference for male chemosignals is not affected by opioidergic antagonists. We hypothesize that glutamatergic projections from the amygdala into the accumbens might be important to modulate the neurochemical and behavioral responses elicited by sexual chemosignals in rats.
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Affiliation(s)
- María-José Sánchez-Catalán
- Departament de Farmàcia, Tecnologia Farmacèutica i Parasitologia, Universitat de València València, Spain
| | - Alejandro Orrico
- Departament de Farmàcia, Tecnologia Farmacèutica i Parasitologia, Universitat de València València, Spain
| | - Lucía Hipólito
- Departament de Farmàcia, Tecnologia Farmacèutica i Parasitologia, Universitat de València València, Spain
| | - Teodoro Zornoza
- Departament de Farmàcia, Tecnologia Farmacèutica i Parasitologia, Universitat de València València, Spain
| | - Ana Polache
- Departament de Farmàcia, Tecnologia Farmacèutica i Parasitologia, Universitat de València València, Spain
| | - Enrique Lanuza
- Departament de Biologia Cel⋅lular, Biologia Funcional i Antropologia Física, Universitat de València València, Spain
| | | | - Luis Granero
- Departament de Farmàcia, Tecnologia Farmacèutica i Parasitologia, Universitat de València València, Spain
| | - Carmen Agustín-Pavón
- Departament de Biologia Cel⋅lular, Biologia Funcional i Antropologia Física, Universitat de València València, Spain
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Berríos-Cárcamo P, Quintanilla ME, Herrera-Marschitz M, Vasiliou V, Zapata-Torres G, Rivera-Meza M. Racemic Salsolinol and its Enantiomers Act as Agonists of the μ-Opioid Receptor by Activating the Gi Protein-Adenylate Cyclase Pathway. Front Behav Neurosci 2017; 10:253. [PMID: 28167903 PMCID: PMC5253357 DOI: 10.3389/fnbeh.2016.00253] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 12/28/2016] [Indexed: 01/07/2023] Open
Abstract
Background: Several studies have shown that the ethanol-derived metabolite salsolinol (SAL) can activate the mesolimbic system, suggesting that SAL is the active molecule mediating the rewarding effects of ethanol. In vitro and in vivo studies suggest that SAL exerts its action on neuron excitability through a mechanism involving opioid neurotransmission. However, there is no direct pharmacologic evidence showing that SAL activates opioid receptors. Methods: The ability of racemic (R/S)-SAL, and its stereoisomers (R)-SAL and (S)-SAL, to activate the μ-opioid receptor was tested in cell-based (light-emitting) receptor assays. To further characterizing the interaction of SAL stereoisomers with the μ-opioid receptor, a molecular docking study was performed using the crystal structure of the μ-opioid receptor. Results: This study shows that SAL activates the μ-opioid receptor by the classical G protein-adenylate cyclase pathway with an half-maximal effective concentration (EC50) of 2 × 10−5 M. The agonist action of SAL was fully blocked by the μ-opioid antagonist naltrexone. The EC50 for the purified stereoisomers (R)-SAL and (S)-SAL were 6 × 10−4 M and 9 × 10−6 M respectively. It was found that the action of racemic SAL on the μ-opioid receptor did not promote the recruitment of β-arrestin. Molecular docking studies showed that the interaction of (R)- and (S)-SAL with the μ-opioid receptor is similar to that predicted for the agonist morphine. Conclusions: It is shown that (R)-SAL and (S)-SAL are agonists of the μ-opioid receptor. (S)-SAL is a more potent agonist than the (R)-SAL stereoisomer. In silico analysis predicts a morphine-like interaction between (R)- and (S)-SAL with the μ-opioid receptor. These results suggest that an opioid action of SAL or its enantiomers is involved in the rewarding effects of ethanol.
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Affiliation(s)
- Pablo Berríos-Cárcamo
- Program of Molecular and Clinical Pharmacology, Faculty of Medicine, Institute of Biomedical Sciences, University of ChileSantiago, Chile; Department of Environmental Health Sciences, Yale School of Public HealthNew Haven, CT, USA
| | - María E Quintanilla
- Program of Molecular and Clinical Pharmacology, Faculty of Medicine, Institute of Biomedical Sciences, University of Chile Santiago, Chile
| | - Mario Herrera-Marschitz
- Program of Molecular and Clinical Pharmacology, Faculty of Medicine, Institute of Biomedical Sciences, University of Chile Santiago, Chile
| | - Vasilis Vasiliou
- Department of Environmental Health Sciences, Yale School of Public Health New Haven, CT, USA
| | - Gerald Zapata-Torres
- Department of Analytical and Inorganic Chemistry, Faculty of Chemical and Pharmaceutical Sciences, University of Chile Santiago, Chile
| | - Mario Rivera-Meza
- Department of Pharmacological and Toxicological Chemistry, Faculty of Chemical and Pharmaceutical Sciences, University of Chile Santiago, Chile
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Peana AT, Rosas M, Porru S, Acquas E. From Ethanol to Salsolinol: Role of Ethanol Metabolites in the Effects of Ethanol. J Exp Neurosci 2016; 10:137-146. [PMID: 27891052 PMCID: PMC5117487 DOI: 10.4137/jen.s25099] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 10/13/2016] [Accepted: 11/03/2016] [Indexed: 12/29/2022] Open
Abstract
In spite of the global reputation of ethanol as the psychopharmacologically active ingredient of alcoholic drinks, the neurobiological basis of the central effects of ethanol still presents some dark sides due to a number of unanswered questions related to both its precise mechanism of action and its metabolism. Accordingly, ethanol represents the interesting example of a compound whose actions cannot be explained as simply due to the involvement of a single receptor/neurotransmitter, a scenario further complicated by the robust evidence that two main metabolites, acetaldehyde and salsolinol, exert many effects similar to those of their parent compound. The present review recapitulates, in a perspective manner, the major and most recent advances that in the last decades boosted a significant growth in the understanding on the role of ethanol metabolism, in particular, in the neurobiological basis of its central effects.
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Affiliation(s)
- Alessandra T Peana
- Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy
| | - Michela Rosas
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Simona Porru
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Elio Acquas
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy.; Centre of Excellence on Neurobiology of Addiction, University of Cagliari, Cagliari, Italy
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15
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Quintanilla ME, Rivera-Meza M, Berríos-Cárcamo P, Cassels BK, Herrera-Marschitz M, Israel Y. (R)-Salsolinol, a product of ethanol metabolism, stereospecifically induces behavioral sensitization and leads to excessive alcohol intake. Addict Biol 2016; 21:1063-1071. [PMID: 26032572 DOI: 10.1111/adb.12268] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ethanol is oxidized in the brain to acetaldehyde, which can condense with dopamine to generate (R/S)-salsolinol [(RS)-SAL]. Racemic salsolinol [(RS)-SAL] is self-infused by rats into the posterior ventral tegmental area (VTA) at significantly lower concentrations than those of acetaldehyde, suggesting that (RS)-SAL is a most active product of ethanol metabolism. Early studies showed that repeated intraperitoneal or intra-VTA administration of (RS)-SAL (10 mg/kg) induced conditioned place preference, led to locomotor sensitization and increased voluntary ethanol consumption. In the present study, we separated the (R)- and (S)-enantiomers from a commercial (RS)-SAL using a high-performance liquid chromatography with electrochemical detection system fitted with a β-cyclodextrin-modified column. We injected (R)-SAL or (S)-SAL (30 pmol/1.0 μl) into the VTA of naïve UChB rats bred as alcohol drinkers to study whether one or both SAL enantiomers are responsible for the motivated behavioral effects, sensitization and increase in voluntary ethanol intake. The present results show that repeated administration of (R)-SAL leads to (1) conditioned place preference; (2) locomotor sensitization; and (3) marked increases in binge-like ethanol intake. Conversely, (S)-SAL did not influence any of these parameters. Overall, data indicate that (R)-SAL stereospecifically induces motivational effects, behavioral sensitization and increases ethanol intake.
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Affiliation(s)
- María Elena Quintanilla
- Molecular and Clinical Pharmacology Program; Institute of Biomedical Sciences; University of Chile; Chile
| | - Mario Rivera-Meza
- Molecular and Clinical Pharmacology Program; Institute of Biomedical Sciences; University of Chile; Chile
- Millennium Institute BNI; Faculty of Medicine; University of Chile; Chile
| | - Pablo Berríos-Cárcamo
- Molecular and Clinical Pharmacology Program; Institute of Biomedical Sciences; University of Chile; Chile
| | - Bruce K. Cassels
- Department of Chemistry; Faculty of Sciences; University of Chile; Chile
| | - Mario Herrera-Marschitz
- Molecular and Clinical Pharmacology Program; Institute of Biomedical Sciences; University of Chile; Chile
- Millennium Institute BNI; Faculty of Medicine; University of Chile; Chile
| | - Yedy Israel
- Molecular and Clinical Pharmacology Program; Institute of Biomedical Sciences; University of Chile; Chile
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16
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Martí-Prats L, Orrico A, Polache A, Granero L. Dual motor responses elicited by ethanol in the posterior VTA: Consequences of the blockade of μ-opioid receptors. J Psychopharmacol 2015. [PMID: 26216379 DOI: 10.1177/0269881115598337] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A recent hypothesis, based on electrophysiological and behavioural findings, suggests that ethanol simultaneously exerts opposed effects on the activity of dopamine (DA) neurons in the ventral tegmental area (VTA) through two parallel mechanisms, one promoting and the other reducing the GABA release onto VTA DA neurons. In this sense, the activating effects are mediated by salsolinol, a metabolite of ethanol, acting on the μ-opioid receptors (MORs) located in VTA GABA neurons. The inhibitory effects are, however, triggered by the non-metabolized fraction of ethanol which would cause the GABAA receptors-mediated inhibition of VTA DA neurons. Since both trends tend to offset each other, only the use of appropriate pharmacological tools allows analysis of this phenomenon in depth. Herein, we present new behavioural findings supporting this hypothesis. Motor activity was evaluated in rats after intra-VTA administration of ethanol 35 nmol, an apparently ineffective dose, 24 h after the irreversible blockade of MORs in the VTA with β-FNA. Our results showed that this pre-treatment turned the initially ineffective ethanol dose into a depressant one, confirming that the activating effect of ethanol can be selectively suppressed without affecting the depressant effects mediated by the non-biotransformed fraction of ethanol.
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Affiliation(s)
- Lucía Martí-Prats
- Departament de Farmàcia i Tecnologia Farmacèutica, Facultat de Farmàcia, Universitat de València, Burjassot, Spain
| | - Alejandro Orrico
- Departament de Farmàcia i Tecnologia Farmacèutica, Facultat de Farmàcia, Universitat de València, Burjassot, Spain
| | - Ana Polache
- Departament de Farmàcia i Tecnologia Farmacèutica, Facultat de Farmàcia, Universitat de València, Burjassot, Spain
| | - Luis Granero
- Departament de Farmàcia i Tecnologia Farmacèutica, Facultat de Farmàcia, Universitat de València, Burjassot, Spain
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17
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Israel Y, Quintanilla ME, Karahanian E, Rivera-Meza M, Herrera-Marschitz M. The "first hit" toward alcohol reinforcement: role of ethanol metabolites. Alcohol Clin Exp Res 2015; 39:776-86. [PMID: 25828063 DOI: 10.1111/acer.12709] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 02/22/2015] [Indexed: 12/20/2022]
Abstract
This review analyzes literature that describes the behavioral effects of 2 metabolites of ethanol (EtOH): acetaldehyde and salsolinol (a condensation product of acetaldehyde and dopamine) generated in the brain. These metabolites are self-administered into specific brain areas by animals, showing strong reinforcing effects. A wealth of evidence shows that EtOH, a drug consumed to attain millimolar concentrations, generates brain metabolites that are reinforcing at micromolar and nanomolar concentrations. Salsolinol administration leads to marked increases in voluntary EtOH intake, an effect inhibited by mu-opioid receptor blockers. In animals that have ingested EtOH chronically, the maintenance of alcohol intake is no longer influenced by EtOH metabolites, as intake is taken over by other brain systems. However, after EtOH withdrawal brain acetaldehyde has a major role in promoting binge-like drinking in the condition known as the "alcohol deprivation effect"; a condition seen in animals that have ingested alcohol chronically, are deprived of EtOH for extended periods, and are allowed EtOH re-access. The review also analyzes the behavioral effects of acetate, a metabolite that enters the brain and is responsible for motor incoordination at low doses of EtOH. Also discussed are the paradoxical effects of systemic acetaldehyde. Overall, evidence strongly suggests that brain-generated EtOH metabolites play a major role in the early ("first-hit") development of alcohol reinforcement and in the generation of relapse-like drinking.
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Affiliation(s)
- Yedy Israel
- Program of Molecular and Clinical Pharmacology, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile
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18
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Melis M, Carboni E, Caboni P, Acquas E. Key role of salsolinol in ethanol actions on dopamine neuronal activity of the posterior ventral tegmental area. Addict Biol 2015; 20:182-93. [PMID: 24103023 DOI: 10.1111/adb.12097] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ethanol excites dopamine (DA) neurons in the posterior ventral tegmental area (pVTA). This effect is responsible for ethanol's motivational properties and may contribute to alcoholism. Evidence indicates that catalase-mediated conversion of ethanol into acetaldehyde in pVTA plays a critical role in this effect. Acetaldehyde, in the presence of DA, condensates with it to generate salsolinol. Salsolinol, when administered in pVTA, excites pVTA DA cells, elicits DA transmission in nucleus accumbens and sustains its self-administration in pVTA. Here we show, by using ex vivo electrophysiology, that ethanol and acetaldehyde, but not salsolinol, failed to stimulate pVTA DA cell activity in mice administered α-methyl-p-tyrosine, a DA biosynthesis inhibitor that reduces somatodendritic DA release. This effect was specific for ethanol and acetaldehyde since morphine, similarly to salsolinol, was able to excite pVTA DA cells in α-methyl-p-tyrosine-treated mice. However, when DA was bath applied in slices from α-methyl-p-tyrosine-treated mice, ethanol-induced excitation of pVTA DA neurons was restored. This effect requires ethanol oxidation into acetaldehyde given that, when H2 O2 -catalase system was impaired by either 3-amino-1,2,4-triazole or in vivo administration of α-lipoic acid, ethanol did not enhance DA cell activity. Finally, high performance liquid chromatography-tandem mass spectrometry analysis of bath medium detected salsolinol only after co-application of ethanol and DA in α-methyl-p-tyrosine-treated mice. These results demonstrate the relationship between ethanol and salsolinol effects on pVTA DA neurons, help to untangle the mechanism(s) of action of ethanol in this area and contribute to an exciting research avenue prosperous of theoretical and practical consequences.
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Affiliation(s)
- Miriam Melis
- Department of Biomedical Sciences; University of Cagliari; Cagliari Italy
| | - Ezio Carboni
- Department of Biomedical Sciences; University of Cagliari; Cagliari Italy
- Centre of Excellence on Neurobiology of Addiction; University of Cagliari; Cagliari Italy
- INN-National Institute of Neuroscience; University of Cagliari; Cagliari Italy
| | - Pierluigi Caboni
- Department of Life and Environmental Sciences; University of Cagliari; Cagliari Italy
| | - Elio Acquas
- Department of Life and Environmental Sciences; University of Cagliari; Cagliari Italy
- Centre of Excellence on Neurobiology of Addiction; University of Cagliari; Cagliari Italy
- INN-National Institute of Neuroscience; University of Cagliari; Cagliari Italy
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19
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Sanchez-Catalan MJ, Kaufling J, Georges F, Veinante P, Barrot M. The antero-posterior heterogeneity of the ventral tegmental area. Neuroscience 2014; 282:198-216. [PMID: 25241061 DOI: 10.1016/j.neuroscience.2014.09.025] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/09/2014] [Accepted: 09/10/2014] [Indexed: 11/16/2022]
Abstract
The ventral tegmental area (VTA) is a brain region processing salient sensory and emotional information, controlling motivated behaviors, natural or drug-related reward, reward-related learning, mood, and participating in their associated psychopathologies. Mostly studied for its dopamine neurons, the VTA also includes functionally important GABA and glutamate cell populations. Behavioral evidence supports the presence of functional differences between the anterior VTA (aVTA) and the posterior VTA (pVTA), which is the topic of this review. This antero-posterior heterogeneity concerns locomotor activity, conditioned place preference and intracranial self-administration, and can be seen in response to ethanol, acetaldehyde, salsolinol, opioids including morphine, cholinergic agonists including nicotine, cocaine, cannabinoids and after local manipulation of GABA and serotonin receptors. It has also been observed after viral-mediated manipulation of GluR1, phospholipase Cγ (PLCγ) and cAMP response element binding protein (CREB) expression, with impact on reward and aversion-related responses, on anxiety and depression-related behaviors and on pain sensitivity. In this review, the substrates potentially underlying these aVTA/pVTA differences are discussed, including the VTA sub-nuclei and the heterogeneity in connectivity, cell types and molecular characteristics. We also review the role of the tail of the VTA (tVTA), or rostromedial tegmental nucleus (RMTg), which may also participate to the observed antero-posterior heterogeneity of the VTA. This region, partly located within the pVTA, is an inhibitory control center for dopamine activity. It controls VTA and substantia nigra dopamine cells, thus exerting a major influence on basal ganglia functions. This review highlights the need for a more comprehensive analysis of VTA heterogeneity.
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Affiliation(s)
- M J Sanchez-Catalan
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Strasbourg, France; Université de Strasbourg, Strasbourg, France
| | - J Kaufling
- Centre National de la Recherche Scientifique, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France; Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France
| | - F Georges
- Centre National de la Recherche Scientifique, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France; Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France
| | - P Veinante
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Strasbourg, France; Université de Strasbourg, Strasbourg, France
| | - M Barrot
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Strasbourg, France; Université de Strasbourg, Strasbourg, France.
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20
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Quintanilla ME, Rivera-Meza M, Berrios-Cárcamo PA, Bustamante D, Buscaglia M, Morales P, Karahanian E, Herrera-Marschitz M, Israel Y. Salsolinol, free of isosalsolinol, exerts ethanol-like motivational/sensitization effects leading to increases in ethanol intake. Alcohol 2014; 48:551-9. [PMID: 25086835 DOI: 10.1016/j.alcohol.2014.07.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Salsolinol is formed non-enzymatically when ethanol-derived acetaldehyde binds to dopamine, yielding 2 distinct products, i.e., salsolinol and isosalsolinol. Early animal studies, revealing that salsolinol promotes alcohol consumption and recent evidence that animals will readily self-administer salsolinol into the posterior ventral tegmental area (p-VTA) together with the finding that salsolinol is able to induce conditioned place preference and to increase locomotor activity, have outlined a role of salsolinol in the behavioral and neurobiological actions of ethanol. Until recently, the only commercially available salsolinol was a mixture containing 85% salsolinol and 10-15% isosalsolinol. The possibility thus exists that either salsolinol or isosalsolinol explains the reinforcing properties of ethanol. We report here that a newly available salsolinol is free of isosalsolinol. Thus, salsolinol, free of isosalsolinol, was injected intracerebrally (30 pmol/0.2 μL, into the ventral tegmental area [VTA]) or intraperitoneally (i.p.) (10 mg/kg) to naïve rats bred as alcohol drinkers to study salsolinol's motivational effects and its role on voluntary ethanol intake. Salsolinol produced conditioned place preference and increased locomotor activity, whether injected intra-VTA or intraperitoneally. Following systemic (i.p.) administration of 10 mg/kg salsolinol, this molecule was detected in vivo by microdialysis of neostriatum, reaching an estimated concentration of 100 nM in the dialyzate. These results indicate that systemically administered salsolinol is able to cross the blood-brain barrier (BBB). Repeated administration of salsolinol sensitized rats to the locomotor activity and led to increases in voluntary ethanol consumption, which was prevented by intra-VTA pretreatment with naltrexone.
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Affiliation(s)
- María Elena Quintanilla
- Molecular and Clinical Pharmacology Program, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile.
| | - Mario Rivera-Meza
- Molecular and Clinical Pharmacology Program, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Pablo A Berrios-Cárcamo
- Molecular and Clinical Pharmacology Program, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Diego Bustamante
- Molecular and Clinical Pharmacology Program, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Marianne Buscaglia
- Molecular and Clinical Pharmacology Program, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Paola Morales
- Molecular and Clinical Pharmacology Program, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Eduardo Karahanian
- Molecular and Clinical Pharmacology Program, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Mario Herrera-Marschitz
- Molecular and Clinical Pharmacology Program, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Yedy Israel
- Molecular and Clinical Pharmacology Program, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
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Opposite motor responses elicited by ethanol in the posterior VTA: The role of acetaldehyde and the non-metabolized fraction of ethanol. Neuropharmacology 2013; 72:204-14. [DOI: 10.1016/j.neuropharm.2013.04.047] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/27/2013] [Accepted: 04/19/2013] [Indexed: 11/18/2022]
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22
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Deehan GA, Hauser SR, Wilden JA, Truitt WA, Rodd ZA. Elucidating the biological basis for the reinforcing actions of alcohol in the mesolimbic dopamine system: the role of active metabolites of alcohol. Front Behav Neurosci 2013; 7:104. [PMID: 23986666 PMCID: PMC3750600 DOI: 10.3389/fnbeh.2013.00104] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 07/27/2013] [Indexed: 11/13/2022] Open
Abstract
The development of successful pharmacotherapeutics for the treatment of alcoholism is predicated upon understanding the biological action of alcohol. A limitation of the alcohol research field has been examining the effects of alcohol only and ignoring the multiple biological active metabolites of alcohol. The concept that alcohol is a "pro-drug" is not new. Alcohol is readily metabolized to acetaldehyde within the brain. Acetaldehyde is a highly reactive compound that forms a number of condensation products, including salsolinol and iso-salsolinol (acetaldehyde and dopamine). Recent experiments have established that numerous metabolites of alcohol have direct CNS action, and could, in part or whole, mediate the reinforcing actions of alcohol within the mesolimbic dopamine system. The mesolimbic dopamine system originates in the ventral tegmental area (VTA) and projects to forebrain regions that include the nucleus accumbens (Acb) and the medial prefrontal cortex (mPFC) and is thought to be the neurocircuitry governing the rewarding properties of drugs of abuse. Within this neurocircuitry there is convincing evidence that; (1) biologically active metabolites of alcohol can directly or indirectly increase the activity of VTA dopamine neurons, (2) alcohol and alcohol metabolites are reinforcing within the mesolimbic dopamine system, (3) inhibiting the alcohol metabolic pathway inhibits the biological consequences of alcohol exposure, (4) alcohol consumption can be reduced by inhibiting/attenuating the alcohol metabolic pathway in the mesolimbic dopamine system, (5) alcohol metabolites can alter neurochemical levels within the mesolimbic dopamine system, and (6) alcohol interacts with alcohol metabolites to enhance the actions of both compounds. The data indicate that there is a positive relationship between alcohol and alcohol metabolites in regulating the biological consequences of consuming alcohol and the potential of alcohol use escalating to alcoholism.
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Affiliation(s)
- Gerald A Deehan
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University, School of Medicine Indianapolis, IN, USA
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23
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Font L, Luján MÁ, Pastor R. Involvement of the endogenous opioid system in the psychopharmacological actions of ethanol: the role of acetaldehyde. Front Behav Neurosci 2013; 7:93. [PMID: 23914161 PMCID: PMC3728478 DOI: 10.3389/fnbeh.2013.00093] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 07/10/2013] [Indexed: 12/13/2022] Open
Abstract
Significant evidence implicates the endogenous opioid system (EOS) (opioid peptides and receptors) in the mechanisms underlying the psychopharmacological effects of ethanol. Ethanol modulates opioidergic signaling and function at different levels, including biosynthesis, release, and degradation of opioid peptides, as well as binding of endogenous ligands to opioid receptors. The role of β-endorphin and µ-opioid receptors (OR) have been suggested to be of particular importance in mediating some of the behavioral effects of ethanol, including psychomotor stimulation and sensitization, consumption and conditioned place preference (CPP). Ethanol increases the release of β-endorphin from the hypothalamic arcuate nucleus (NArc), which can modulate activity of other neurotransmitter systems such as mesolimbic dopamine (DA). The precise mechanism by which ethanol induces a release of β-endorphin, thereby inducing behavioral responses, remains to be elucidated. The present review summarizes accumulative data suggesting that the first metabolite of ethanol, the psychoactive compound acetaldehyde, could participate in such mechanism. Two lines of research involving acetaldehyde are reviewed: (1) implications of the formation of acetaldehyde in brain areas such as the NArc, with high expression of ethanol metabolizing enzymes and presence of cell bodies of endorphinic neurons and (2) the formation of condensation products between DA and acetaldehyde such as salsolinol, which exerts its actions via OR.
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Affiliation(s)
- Laura Font
- Area de Psicobiología, Universitat Jaume I Castellón, Spain
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Peana AT, Acquas E. Behavioral and biochemical evidence of the role of acetaldehyde in the motivational effects of ethanol. Front Behav Neurosci 2013; 7:86. [PMID: 23874276 PMCID: PMC3710953 DOI: 10.3389/fnbeh.2013.00086] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 06/27/2013] [Indexed: 11/13/2022] Open
Abstract
Since Chevens' report, in the early 50's that his patients under treatment with the aldehyde dehydrogenase inhibitor, antabuse, could experience beneficial effects when drinking small volumes of alcoholic beverages, the role of acetaldehyde (ACD) in the effects of ethanol has been thoroughly investigated on pre-clinical grounds. Thus, after more than 25 years of intense research, a large number of studies have been published on the motivational properties of ACD itself as well as on the role that ethanol-derived ACD plays in the effects of ethanol. Accordingly, in particular with respect to the motivational properties of ethanol, these studies were developed following two main strategies: on one hand, were aimed to challenge the suggestion that also ACD may exert motivational properties on its own, while, on the other, with the aid of enzymatic manipulations or ACD inactivation, were aimed to test the hypothesis that ethanol-derived ACD might have a role in ethanol motivational effects. Furthermore, recent evidence significantly contributed to highlight, as possible mechanisms of action of ACD, its ability to commit either dopaminergic and opioidergic transmission as well as to activate the Extracellular signal Regulated Kinase cascade transduction pathway in reward-related brain structures. In conclusion, and despite the observation that ACD seems also to have inherited the elusive nature of its parent compound, the behavioral and biochemical evidence reviewed points to ACD as a neuroactive molecule able, on its own and as ethanol metabolite, to exert motivational effects.
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Affiliation(s)
- Alessandra T Peana
- Department of Chemistry and Pharmacy, University of Sassari Sassari, Italy
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25
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Buse J, Schoenefeld K, Münchau A, Roessner V. Neuromodulation in Tourette syndrome: Dopamine and beyond. Neurosci Biobehav Rev 2013; 37:1069-84. [DOI: 10.1016/j.neubiorev.2012.10.004] [Citation(s) in RCA: 136] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 09/28/2012] [Accepted: 10/08/2012] [Indexed: 01/11/2023]
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26
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Polache A, Granero L. Salsolinol and ethanol-derived excitation of dopamine mesolimbic neurons: new insights. Front Behav Neurosci 2013; 7:74. [PMID: 23805085 PMCID: PMC3691577 DOI: 10.3389/fnbeh.2013.00074] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 06/05/2013] [Indexed: 11/25/2022] Open
Affiliation(s)
- Ana Polache
- Departament de Farmàcia i Tecnología Farmacéutica, Universitat de València Burjassot, Spain
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March SM, Abate P, Molina JC. Acetaldehyde involvement in ethanol's postabsortive effects during early ontogeny. Front Behav Neurosci 2013; 7:70. [PMID: 23801947 PMCID: PMC3685812 DOI: 10.3389/fnbeh.2013.00070] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 06/01/2013] [Indexed: 11/29/2022] Open
Abstract
Clinical and biomedical studies sustains the notion that early ontogeny is a vulnerable window to the impact of alcohol. Experiences with the drug during these stages increase latter disposition to prefer, use or abuse ethanol. This period of enhanced sensitivity to ethanol is accompanied by a high rate of activity in the central catalase system, which metabolizes ethanol in the brain. Acetaldehyde (ACD), the first oxidation product of ethanol, has been found to share many neurobehavioral effects with the drug. Cumulative evidence supports this notion in models employing adults. Nevertheless very few studies have been conducted to analyze the role of ACD in ethanol postabsorptive effects, in newborns or infant rats. In this work we review recent experimental literature that syndicates ACD as a mediator agent of reinforcing aspects of ethanol, during early ontogenetic stages. We also show a meta-analytical correlational approach that proposes how differences in the activity of brain catalase across ontogeny, could be modulating patterns of ethanol consumption.
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Affiliation(s)
- Samanta M March
- Laboratorio de Alcohol, Ontogenia y Desarrollo, Instituto de Investigación Médica Mercedes y Martín Ferreyra Córdoba, Argentina ; Department de Psicología, Facultad de Psicología, Universidad Nacional de Córdoba Córdoba, Argentina
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Xie G, Krnjević K, Ye JH. Salsolinol modulation of dopamine neurons. Front Behav Neurosci 2013; 7:52. [PMID: 23745110 PMCID: PMC3662897 DOI: 10.3389/fnbeh.2013.00052] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 05/07/2013] [Indexed: 11/25/2022] Open
Abstract
Salsolinol, a tetrahydroisoquinoline present in the human and rat brains, is the condensation product of dopamine and acetaldehyde, the first metabolite of ethanol. Previous evidence obtained in vivo links salsolinol with the mesolimbic dopaminergic (DA) system: salsolinol is self-administered into the posterior of the ventral tegmental area (pVTA) of rats; intra-VTA administration of salsolinol induces a strong conditional place preference and increases dopamine release in the nucleus accumbens (NAc). However, the underlying neuronal mechanisms are unclear. Here we present an overview of some of the recent research on this topic. Electrophysiological studies reveal that DA neurons in the pVTA are a target of salsolinol. In acute brain slices from rats, salsolinol increases the excitability and accelerates the ongoing firing of dopamine neurons in the pVTA. Intriguingly, this action of salsolinol involves multiple pre- and post-synaptic mechanisms, including: (1) depolarizing dopamine neurons; (2) by activating μ opioid receptors on the GABAergic inputs to dopamine neurons – which decreases GABAergic activity – dopamine neurons are disinhibited; and (3) enhancing presynaptic glutamatergic transmission onto dopamine neurons via activation of dopamine type 1 receptors, probably situated on the glutamatergic terminals. These novel mechanisms may contribute to the rewarding/reinforcing properties of salsolinol observed in vivo.
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Affiliation(s)
- Guiqin Xie
- Department of Anesthesiology, Pharmacology, and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey Newark, NJ, USA ; Department of Physiology, Nanjing Medical University Nanjing, China
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Cocaine- and amphetamine-regulated transcript peptide (CART) in the central nucleus of amygdala potentiates behavioral and hormonal responses of the rat exposed to its predator. Behav Brain Res 2013; 243:129-37. [DOI: 10.1016/j.bbr.2012.12.058] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 12/28/2012] [Accepted: 12/31/2012] [Indexed: 11/23/2022]
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Deehan GA, Engleman EA, Ding ZM, McBride WJ, Rodd ZA. Microinjections of acetaldehyde or salsolinol into the posterior ventral tegmental area increase dopamine release in the nucleus accumbens shell. Alcohol Clin Exp Res 2012; 37:722-9. [PMID: 23278868 DOI: 10.1111/acer.12034] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 08/28/2012] [Indexed: 11/29/2022]
Abstract
BACKGROUND Published findings indicate that acetaldehyde (ACD; the first metabolite of ethanol [EtOH]) and salsolinol (SAL; formed through the nonenzymatic condensation of ACD and dopamine [DA]) can be formed following EtOH consumption. Both ACD and SAL exhibit reinforcing properties within the posterior ventral tegmental area (pVTA) and both exhibit an inverted "U-shaped" dose-response curve. The current study was undertaken to examine the dose-response effects of microinjections of ACD or SAL into the pVTA on DA efflux in the nucleus accumbens shell (AcbSh). METHODS For the first experiment, separate groups of male Wistar rats received pulse microinjections of artificial cerebrospinal fluid (aCSF) or 12-, 23-, or 90-μM ACD into the pVTA, while extracellular DA levels were concurrently measured in the AcbSh. The second experiment was similarly conducted, except rats were given microinjections of aCSF or 0.03-, 0.3-, 1.0-, or 3.0-μM SAL, while extracellular levels of DA were measured in the AcbSh. RESULTS Both ACD and SAL produced a dose-dependent inverted "U-shaped" response on DA release in the AcbSh, with 23-μM ACD (200% baseline) and 0.3-μM SAL (300% baseline) producing maximal peak responses with higher concentrations of ACD (90 μM) and SAL (3.0 μM) producing significantly lower DA efflux. CONCLUSIONS The findings from the current study indicate that local application of intermediate concentrations of ACD and SAL stimulated DA neurons in the pVTA, whereas higher concentrations may be having secondary effects within the pVTA that inhibit DA neuronal activity. The present results parallel the studies on the reinforcing effects of ACD and SAL in the pVTA and support the idea that the reinforcing effects of ACD and SAL within the pVTA are mediated by activating DA neurons.
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Affiliation(s)
- Gerald A Deehan
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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Correa M, Salamone JD, Segovia KN, Pardo M, Longoni R, Spina L, Peana AT, Vinci S, Acquas E. Piecing together the puzzle of acetaldehyde as a neuroactive agent. Neurosci Biobehav Rev 2012; 36:404-30. [DOI: 10.1016/j.neubiorev.2011.07.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 07/14/2011] [Accepted: 07/21/2011] [Indexed: 10/17/2022]
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Xie G, Hipólito L, Zuo W, Polache A, Granero L, Krnjevic K, Ye JH. Salsolinol stimulates dopamine neurons in slices of posterior ventral tegmental area indirectly by activating μ-opioid receptors. J Pharmacol Exp Ther 2011; 341:43-50. [PMID: 22209890 DOI: 10.1124/jpet.111.186833] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Previous studies in vivo have shown that salsolinol, the condensation product of acetaldehyde and dopamine, has properties that may contribute to alcohol abuse. Although opioid receptors, especially the μ-opioid receptors (MORs), may be involved, the cellular mechanisms mediating the effects of salsolinol have not been fully explored. In the current study, we used whole-cell patch-clamp recordings to examine the effects of salsolinol on dopamine neurons of the ventral tegmental area (VTA) in acute brain slices from Sprague-Dawley rats. Salsolinol (0.01-1 μM) dose-dependently and reversibly increased the ongoing firing of dopamine neurons; this effect was blocked by naltrexone, an antagonist of MORs, and gabazine, an antagonist of GABA(A) receptors. We further showed that salsolinol reduced the frequency without altering the amplitude of spontaneous GABA(A) receptor-mediated inhibitory postsynaptic currents in dopamine neurons. The salsolinol-induced reduction was blocked by both naltrexone and [D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin, an agonist of MORs. Thus, salsolinol excites VTA-dopamine neurons indirectly by activating MORs, which inhibit GABA neurons in the VTA. This form of disinhibition seems to be a novel mechanism underlying the effects of salsolinol.
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Affiliation(s)
- Guiqin Xie
- Department of Anesthesiology, Pharmacology, and Physiology, UMDNJ, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA
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Abstract
This paper is the thirty-third consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2010 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, USA.
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Hipólito L, Sánchez-Catalán MJ, Martí-Prats L, Granero L, Polache A. Revisiting the controversial role of salsolinol in the neurobiological effects of ethanol: old and new vistas. Neurosci Biobehav Rev 2011; 36:362-78. [PMID: 21802444 DOI: 10.1016/j.neubiorev.2011.07.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 07/12/2011] [Accepted: 07/14/2011] [Indexed: 10/18/2022]
Abstract
The possible involvement of salsolinol (Sal), an endogenous condensation product of ACD (the first metabolite of ethanol) and dopamine, in the neurochemical basis underlying ethanol action has been repeatedly suggested although it has not been unequivocally established, still being a controversial matter of debate. The main goal of this review is to evaluate the presumed contribution of Sal to ethanol effects summarizing the reported data since the discovery in the 1970s of Sal formation in vitro during ethanol metabolism until the more recent studies characterizing its behavioral and neurochemical effects. Towards this end, we first analyze the production and detection of Sal, in different brain areas, in basal conditions and after alcohol consumption, highlighting its presence in regions especially relevant in regulating ethanol-drinking behaviour and the importance of the newly developed methods to differentiate both enantiomers of Sal which could help to explain some previous negative findings. Afterwards, we review the behavioral and neurochemical studies. Finally, we present and discuss the previous and current enunciated mechanisms of action of Sal in the CNS.
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Affiliation(s)
- Lucía Hipólito
- Departament de Farmàcia i Tecnologia Farmacèutica, Universitat de València, Avda Vicente Andrés Estellés s/n, 46100 Burjassot, Spain
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Hipólito L, Martí-Prats L, Sánchez-Catalán MJ, Polache A, Granero L. Induction of conditioned place preference and dopamine release by salsolinol in posterior VTA of rats: involvement of μ-opioid receptors. Neurochem Int 2011; 59:559-62. [PMID: 21693150 DOI: 10.1016/j.neuint.2011.04.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 04/19/2011] [Accepted: 04/21/2011] [Indexed: 11/30/2022]
Abstract
Salsolinol (Sal), locally administered into the posterior VTA (pVTA) of rats, produces psychomotor responses and reinforcing effects, probably, through the activation of μ-opioid receptors (MORs). The neurochemical correlates of these phenomena are, however, practically unknown. In this paper, we explore the neurochemical events and the mechanisms involved in these behaviors. To do that, we test the ability of Sal, directly microinjected into the pVTA, to induce conditioned place preference (CPP) and to increase dopamine levels in the nucleus accumbens shell. Bilateral injections of 30 pmol of Sal induced a strong CPP (rats spent around 70% of the total test time), a result that could be explained by the fact that Sal microinjected into the pVTA increased DA levels in the ipsilateral accumbens up to 141% of baseline. The local pretreatment with β-FNA, an antagonist of MORs, prevented this increase, supporting our hypothesis on the involvement of MORs in the Sal-derived effects.
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Affiliation(s)
- Lucía Hipólito
- Departament de Farmàcia i Tecnología Farmacèutica, Universitat de València, Avda Vicente Andrés Estellés s/n, 46100 Burjassot, Spain
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Martí-Prats L, Sánchez-Catalán MJ, Hipólito L, Orrico A, Zornoza T, Polache A, Granero L. Systemic administration of D-penicillamine prevents the locomotor activation after intra-VTA ethanol administration in rats. Neurosci Lett 2010; 483:143-7. [PMID: 20691754 DOI: 10.1016/j.neulet.2010.07.081] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 07/26/2010] [Accepted: 07/27/2010] [Indexed: 11/25/2022]
Abstract
Although recently published studies seem to confirm the important role displayed by acetaldehyde (ACH), the main metabolite of ethanol, in the behavioral effects of ethanol, the origin of ACH is still a matter of debate. While some authors confer more importance to the central (brain metabolism) origin of ACH, others indicate that the hepatic origin could be more relevant. In this study we have addressed this topic using an experimental approach that combines local microinjections of ethanol into the ventral tegmental area (VTA) (which guarantees the brain origin of the ACH) to induce motor activation in rats together with systemic administration (i.p.) of several doses (0, 12.5, 25 and 50 mg/kg) of D-penicillamine (DP), a sequestering agent of ACH with contrasted efficiency to abolish the behavioral effects of the drug. Our results clearly show that DP prevented in a dose-dependent manner the motor activation induced by intra-VTA ethanol, being the 50 mg/kg dose the most efficient. DP per se did not affect the basal activity of the rats. In order to determine the specificity of the DP action, we also studied the effects of DP 50 mg/kg on the DAMGO-induced motor activation after the intra-VTA administration of this mu-opioid receptors agonist. DP did not significantly modify the motor activation induced by DAMGO thus confirming the specificity of the DP effects. Our results clearly suggest that the brain-derived ACH is necessary to manifest the activating effects resulting from ethanol administration.
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Affiliation(s)
- Lucía Martí-Prats
- Departament de Farmàcia i Tecnologia Farmacèutica, Universitat de València, Spain
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