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Söderpalm B, Ericson M. Alcohol and the dopamine system. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2024; 175:21-73. [PMID: 38555117 DOI: 10.1016/bs.irn.2024.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
The mesolimbic dopamine pathway plays a major role in drug reinforcement and is likely involved also in the development of drug addiction. Ethanol, like most addictive drugs, acutely activates the mesolimbic dopamine system and releases dopamine, and ethanol-associated stimuli also appear to trigger dopamine release. In addition, chronic exposure to ethanol reduces the baseline function of the mesolimbic dopamine system. The molecular mechanisms underlying ethanol´s interaction with this system remain, however, to be unveiled. Here research on the actions of ethanol in the mesolimbic dopamine system, focusing on the involvement of cystein-loop ligand-gated ion channels, opiate receptors, gastric peptides and acetaldehyde is briefly reviewed. In summary, a great complexity as regards ethanol´s mechanism(s) of action along the mesolimbic dopamine system has been revealed. Consequently, several new targets and possibilities for pharmacotherapies for alcohol use disorder have emerged.
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Affiliation(s)
- Bo Söderpalm
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Department of Addiction and Dependency, Sahlgrenska University Hospital, Gothenburg, Sweden.
| | - Mia Ericson
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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2
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Mulloy SM, Aback EM, Gao R, Engel S, Pawaskar K, Win C, Moua A, Hillukka L, Lee AM. Subregion and sex differences in ethanol activation of cholinergic and glutamatergic cells in the mesopontine tegmentum. Sci Rep 2024; 14:46. [PMID: 38168499 PMCID: PMC10762073 DOI: 10.1038/s41598-023-50526-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 12/20/2023] [Indexed: 01/05/2024] Open
Abstract
Ethanol engages cholinergic signaling and elicits endogenous acetylcholine release. Acetylcholine input to the midbrain originates from the mesopontine tegmentum (MPT), which is composed of the laterodorsal tegmentum (LDT) and the pedunculopontine tegmental nucleus (PPN). We investigated the effect of acute and chronic ethanol administration on cholinergic and glutamatergic neuron activation in the PPN and LDT in male and female mice. We show that ethanol activates neurons of the PPN and not the LDT in male mice. Chronic 15 daily injections of 2 g/kg ethanol induced Fos expression in cholinergic and glutamatergic PPN neurons in male mice, whereas ethanol did not increase cholinergic and glutamatergic neuronal activation in the LDT. A single acute 4 g/kg injection, but not a single 2 g/kg injection, induced cholinergic neuron activation in the male PPN but not the LDT. In contrast, acute or chronic ethanol at either dose or duration had no effect on the activation of cholinergic or glutamatergic neurons in the MPT of female mice. Female mice had higher baseline level of activation in cholinergic neurons compared with males. We also found a population of co-labeled cholinergic and glutamatergic neurons in the PPN and LDT which were highly active in the saline- and ethanol-treated groups in both sexes. These findings illustrate the complex differential effects of ethanol across dose, time point, MPT subregion and sex.
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Affiliation(s)
- S M Mulloy
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - E M Aback
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - R Gao
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - S Engel
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - K Pawaskar
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - C Win
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - A Moua
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - L Hillukka
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - A M Lee
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA.
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Mulloy SM, Aback EM, Gao R, Engel S, Pawaskar K, Win C, Moua A, Hillukka L, Lee AM. Subregion and sex differences in ethanol activation of cholinergic and glutamatergic cells in the mesopontine tegmentum. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.08.566053. [PMID: 38014248 PMCID: PMC10680559 DOI: 10.1101/2023.11.08.566053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Ethanol engages cholinergic signaling and elicits endogenous acetylcholine release. Acetylcholine input to the midbrain originates from the mesopontine tegmentum (MPT), which is composed of the laterodorsal tegmentum (LDT) and the pedunculopontine tegmental nucleus (PPN). We investigated the effect of acute and chronic ethanol administration on cholinergic and glutamatergic neuron activation in the PPN and LDT in male and female mice. We show that ethanol selectively activates neurons of the PPN and not the LDT in male mice. Acute 4.0 g/kg and chronic 15 daily injections of 2.0 g/kg i.p. ethanol induced Fos expression in cholinergic and glutamatergic PPN neurons in male mice, whereas cholinergic and glutamatergic neurons of the LDT were unresponsive. In contrast, acute or chronic ethanol at either dose or duration had no effect on the activation of cholinergic or glutamatergic neurons in the MPT of female mice. Female mice had higher level of baseline activation in cholinergic neurons compared with males. We also found a population of co-labeled cholinergic and glutamatergic neurons in the PPN and LDT which were highly active in the saline- and ethanol-treated groups in both sexes. These findings illustrate the complex differential effects of ethanol across dose, time point, MPT subregion and sex.
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Affiliation(s)
- S M Mulloy
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - E M Aback
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - R Gao
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - S Engel
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - K Pawaskar
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - C Win
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - A Moua
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - L Hillukka
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - A M Lee
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, USA
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
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4
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Wadsworth HA, Anderson EQ, Williams BM, Ronström JW, Moen JK, Lee AM, McIntosh JM, Wu J, Yorgason JT, Steffensen SC. Role of α6-Nicotinic Receptors in Alcohol-Induced GABAergic Synaptic Transmission and Plasticity to Cholinergic Interneurons in the Nucleus Accumbens. Mol Neurobiol 2023; 60:3113-3129. [PMID: 36802012 PMCID: PMC10690621 DOI: 10.1007/s12035-023-03263-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 02/03/2023] [Indexed: 02/21/2023]
Abstract
The prevailing view is that enhancement of dopamine (DA) transmission in the mesolimbic system, consisting of DA neurons in the ventral tegmental area (VTA) that project to the nucleus accumbens (NAc), underlies the reward properties of ethanol (EtOH) and nicotine (NIC). We have shown previously that EtOH and NIC modulation of DA release in the NAc is mediated by α6-containing nicotinic acetylcholine receptors (α6*-nAChRs), that α6*-nAChRs mediate low-dose EtOH effects on VTA GABA neurons and EtOH preference, and that α6*-nAChRs may be a molecular target for low-dose EtOH. However, the most sensitive target for reward-relevant EtOH modulation of mesolimbic DA transmission and the involvement of α6*-nAChRs in the mesolimbic DA reward system remains to be elucidated. The aim of this study was to evaluate EtOH effects on GABAergic modulation of VTA GABA neurons and VTA GABAergic input to cholinergic interneurons (CINs) in the NAc. Low-dose EtOH enhanced GABAergic input to VTA GABA neurons that was blocked by knockdown of α6*-nAChRs. Knockdown was achieved either by α6-miRNA injected into the VTA of VGAT-Cre/GAD67-GFP mice or by superfusion of the α-conotoxin MII[H9A;L15A] (MII). Superfusion of MII blocked EtOH inhibition of mIPSCs in NAc CINs. Concomitantly, EtOH enhanced CIN firing rate, which was blocked by knockdown of α6*-nAChRs with α6-miRNA injected into the VTA of VGAT-Cre/GAD67-GFP mice. The firing rate of CINs was not enhanced by EtOH in EtOH-dependent mice, and low-frequency stimulation (LFS; 1 Hz, 240 pulses) caused inhibitory long-term depression at this synapse (VTA-NAc CIN-iLTD) which was blocked by knockdown of α6*-nAChR and MII. Ethanol inhibition of CIN-mediated evoked DA release in the NAc was blocked by MII. Taken together, these findings suggest that α6*-nAChRs in the VTA-NAc pathway are sensitive to low-dose EtOH and play a role in plasticity associated with chronic EtOH.
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Affiliation(s)
- Hillary A Wadsworth
- Department of Psychology and Neuroscience, Brigham Young University, 1050 KMBL, Provo, UT, 84602, USA
| | - Elizabeth Q Anderson
- Department of Psychology and Neuroscience, Brigham Young University, 1050 KMBL, Provo, UT, 84602, USA
| | - Benjamin M Williams
- Department of Psychology and Neuroscience, Brigham Young University, 1050 KMBL, Provo, UT, 84602, USA
| | - Joakim W Ronström
- Department of Psychology and Neuroscience, Brigham Young University, 1050 KMBL, Provo, UT, 84602, USA
| | - Janna K Moen
- Department of Pharmacology, Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Anna M Lee
- Department of Pharmacology, Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
| | - J Michael McIntosh
- School of Biological Sciences and Department of Psychiatry, University of Utah, Salt Lake City, UT, 84108, USA
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, UT, 84148, USA
| | - Jie Wu
- Brain Function and Disease Laboratory, Shantou University Medical College, Shantou, 515041, Guangdong, China
| | - Jordan T Yorgason
- Department of Psychology and Neuroscience, Brigham Young University, 1050 KMBL, Provo, UT, 84602, USA
| | - Scott C Steffensen
- Department of Psychology and Neuroscience, Brigham Young University, 1050 KMBL, Provo, UT, 84602, USA.
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Maddux JM, Gonzales L, Kregar NP. β2* nicotinic acetylcholine receptor subtypes mediate nicotine-induced enhancement of Pavlovian conditioned responding to an alcohol cue. Front Behav Neurosci 2022; 16:1004368. [PMCID: PMC9596985 DOI: 10.3389/fnbeh.2022.1004368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 09/21/2022] [Indexed: 11/13/2022] Open
Abstract
Nicotine enhances Pavlovian conditioned responses to reward-associated cues. We investigated through which nicotinic acetylcholine receptor (nAChR) subtypes nicotine acts to produce this behavioral effect to an alcohol-associated cue. Male Long-Evans rats with freely available food and water were first accustomed to drinking 15% ethanol in their home cages using an intermittent access, two-bottle choice procedure. Then the rats were given 15 Pavlovian conditioning sessions in which a 15-s audiovisual conditioned stimulus (CS) predicted the delivery of 0.2 ml of ethanol, the unconditioned stimulus (US). Each session contained 12 CS-US trials. A control group received explicitly unpaired presentations of the CS and US. We measured Pavlovian conditioned approach to the site of US delivery during presentations of the CS, accounting for pre-CS baseline activity. Before each conditioning session, rats were injected subcutaneously with nicotine (0.4 mg/kg) or saline (1 ml/kg). During nAChR antagonist test sessions, rats were first injected systemically with the β2*-selective nAChR antagonist dihydro-beta-erythroidine (DHβE; 3 mg/kg) or the α7-selective nAChR antagonist methyllycaconitine (MLA; 6 mg/kg), followed by their assigned nicotine or saline injection before assessing their conditioned response to the alcohol-associated cue. Consistent with previous reports, nicotine enhanced the Pavlovian conditioned response to the alcohol-paired cue. DHβE attenuated this enhancement, whereas MLA did not. These results suggest that nicotine acts via β2*, but not α7, nAChRs to amplify Pavlovian conditioned responding to an alcohol cue. These findings contribute to a growing literature that identifies nAChRs as potential targets for pharmacological treatment of co-morbid alcohol and tobacco use disorders.
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Affiliation(s)
- Jean-Marie Maddux
- Department of Psychology, Lake Forest College, Lake Forest, IL, United States
- Neuroscience Program, Lake Forest College, Lake Forest, IL, United States
- *Correspondence: Jean-Marie Maddux
| | - Leslie Gonzales
- Department of Psychology, Lake Forest College, Lake Forest, IL, United States
- Neuroscience Program, Lake Forest College, Lake Forest, IL, United States
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Decker S, Davis G, Vahora I, Vukovic A, Patel P, Suryanarayanan A. Desformylflustrabromine (dFBr), a positive allosteric modulator of α4β2 nicotinic acetylcholine receptors decreases voluntary ethanol consumption and preference in male and female Sprague-Dawley rats. PLoS One 2022; 17:e0273715. [PMID: 36084045 PMCID: PMC9462806 DOI: 10.1371/journal.pone.0273715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 08/11/2022] [Indexed: 11/19/2022] Open
Abstract
Alcohol use disorder is a medical condition that impacts millions of individuals worldwide. Although there are a few pharmacotherapeutic options for alcohol-dependent individuals; there is a need for the development of novel and more effective therapeutic approaches. Alcohol and nicotine are commonly co-abused, and there is evidence that neuronal nicotinic acetylcholine receptors (nAChRs) play a role in both alcohol and nicotine dependence. Desformylflustrabromine (dFBr), a positive allosteric modulator of the α4β2 nAChRs has been shown to reduce nicotine intake, compulsive-like behavior and neuropathic pain in animal models. dFBr has also been previously shown to cross the blood-brain-barrier. We have recently shown that dFBr can attenuate the response to an acute, hypnotic dose of ethanol, via β2 nAchR. Here, we have investigated the effect of dFBr in modulating ethanol consumption using the intermittent access two-bottle choice (IA2BC) model of voluntary ethanol consumption in male and female Sprague Dawley rats. We show that dFBr selectively reduced ethanol but not sucrose consumption in the IA2BC model. Furthermore, dFBr decreased preference for ethanol in both male and female rats. No rebound increase in ethanol intake was observed after the washout period after dFBr treatment. The ability of dFBr to decrease ethanol consumption, along with its previously demonstrated ability to decrease nicotine self-administration in rodents, suggest that dFBr is an attractive therapeutic candidate to target both nicotine and alcohol abuse.
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Affiliation(s)
- Steven Decker
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, United States of America
| | - Gregory Davis
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, United States of America
| | - Imran Vahora
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, United States of America
| | - Alen Vukovic
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, United States of America
| | - Parth Patel
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, United States of America
| | - Asha Suryanarayanan
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, United States of America
- * E-mail:
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Gupta S, Mukhopadhyay S, Mitra A. Therapeutic potential of GHSR-1A antagonism in alcohol dependence, a review. Life Sci 2022; 291:120316. [PMID: 35016882 DOI: 10.1016/j.lfs.2022.120316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 01/05/2022] [Accepted: 01/05/2022] [Indexed: 11/28/2022]
Abstract
Growth hormone secretagogue receptor type 1A (GHSR-1A) is a functional receptor of orexigenic peptide ghrelin and is highly expressed in mesolimbic dopaminergic systems that regulate incentive value of artificial reward in substance abuse. Interestingly, GHSR-1A has also shown ligand-independent constitutive activity. Alcohol use disorder (AUD) is one of the growing concerns worldwide as it involves complex neuro-psycho-endocrinological interactions. Positive correlation of acylated ghrelin and alcohol-induced human brain response in the right and left ventral striatum are evident. In the last decade, the beneficial effects of ghrelin receptor (GHSR-1A) antagonism to suppress artificial reward circuitries and induce self-control for alcohol consumption have drawn significant attention from researchers. In this updated review, we summarize the available recent preclinical, clinical, and experimental data to discuss functional, molecular actions of central ghrelin-GHSR-1A signaling in different craving levels for alcohol as well as to promote "GHSR-1A antagonism" as one of the potential therapies in early abstinence.
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Affiliation(s)
- Shreyasi Gupta
- Department of Zoology, Triveni Devi Bhalotia College, Raniganj, Paschim Bardhaman 713 347, West Bengal, India
| | - Sanchari Mukhopadhyay
- Department of Psychiatry, National Institute of Mental Health and Neurosciences, Hombegowda Nagar, Bengaluru 560029, India
| | - Arkadeep Mitra
- Department of Zoology, City College, 102/1, Raja Rammohan Sarani, Kolkata 700 009, West Bengal, India.
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Carreño D, Lotfipour S. Sex- and genotype-dependent nicotine plus cue-primed reinstatement is enhanced in adolescent Sprague Dawley rats containing the human CHRNA6 3'-UTR polymorphism (rs2304297). Front Psychiatry 2022; 13:1064211. [PMID: 36704741 PMCID: PMC9872558 DOI: 10.3389/fpsyt.2022.1064211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 12/21/2022] [Indexed: 01/11/2023] Open
Abstract
RATIONALE Large-scale human candidate gene studies have indicated that a genetic variant (rs2304297) in the alpha(α)6 nicotinic acetylcholine receptor (nAChR) subunit, encoded by the CHRNA6 gene, may play a key role in adolescent nicotine addictive behavior. We hypothesized that the polymorphism selectively enhances nicotine + cue-primed reinstatement, but not nicotine- or cue-reinstatement in α6 GG (risk) vs. α6 CC (non-risk) allele carriers, without having baseline effects on natural rewards. METHODS Using CRISPR-Cas9 genomic engineering, we developed a humanized rat line with the human gene variant of the CHRNA6 3'-UTR C 123 G polymorphism in Sprague-Dawley rats. Genetically modified adolescent male and female rats were food trained under a fixed-ratio (FR)1 schedule of reinforcement and progressively increased to FR5. Animals were implanted with catheters and began nicotine self-administration (15 μg/kg/infusion) at FR5. Upon reaching stable responding, reinforced behavior was extinguished by removal of drug and cues. Reinstatement testing began for cue only, nicotine only, and nicotine + cue in a Latin Square Design. Animals were returned to extinction conditions for 2 days minimum between testing. RESULTS For natural food rewards, nicotine self-administration, progressive ratio, and extinction, adolescent male and female (α6 GG and α6 CC ) rats exhibited equivalent behaviors. Male α6 GG rats show enhanced nicotine + cue-primed reinstatement when compared with male α6 CC rats. This genotype effect on reinstatement was not seen in female rats. CONCLUSION Our findings support the in vivo functional role of the human CHRNA6 3'-UTR SNP genetic variant in sex-dependently enhancing nicotine seeking behavior in adolescent rats. Overall, the findings support clinical and preclinical data highlighting a role of α6 nAChRs mediating sex heterogeneity in substance use and related phenotypes.
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Affiliation(s)
- Diana Carreño
- Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, United States
| | - Shahrdad Lotfipour
- Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, United States.,Department of Pathology and Laboratory Medicine, University of California, Irvine, Irvine, CA, United States.,Department of Emergency Medicine, University of California, Irvine, Irvine, CA, United States
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DeCristofano L, Decker S, Schulte MK, Suryanarayanan A. Desformylflustrabromine (dFBr), a positive allosteric modulator of the α 4β 2 nicotinic receptor modulates the hypnotic response to ethanol. Alcohol 2021; 93:35-44. [PMID: 33652092 DOI: 10.1016/j.alcohol.2021.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/01/2021] [Accepted: 02/22/2021] [Indexed: 12/17/2022]
Abstract
BACKGROUND Binge drinking can increase an individual's risk of developing alcohol use disorder (AUD). Ethanol targets multiple neurotransmitter systems; however, not much is known about its effects on the cholinergic system. Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels, the heteromeric α4β2 nAChR being a commonly expressed subtype. Desformylflustrabromine (dFBr), a positive allosteric modulator (PAM), increases the efficacy of α4β2 nAChR in vitro and has previously been shown to have translational potential. In this study, we investigated whether dFBr modulates the hypnotic response to ethanol. METHODS Ethanol-induced loss of righting reflex (LORR) duration was measured in the presence and absence of dFBr. The β2 nAChR selective antagonist dihydro-β-erythroidine (DHβE) was used to study the involvement of the β2 subunit. Additionally, we used a crosslinking-based western blot assay to estimate changes in total versus intracellular α4 nAChR protein in thalamic tissue of rats treated with vehicle, dFBr, ethanol, or ethanol and dFBr. Lastly, using Xenopus oocyte two-electrode voltage clamp (TEVC) studies, we determined the effects of ethanol and dFBr on α4β2 nAChR. RESULTS Pretreatment with 6 mg/kg dFBr reduced ethanol-induced LORR duration as compared to rats treated with ethanol alone. LORR studies with DHβE suggest that dFBr reduced ethanol-induced LORR duration via the β2 nAChR subunit. Crosslinking-based western analyses revealed that ethanol caused early increases in total and presumably surface thalamic α4 nAChR subunit protein levels. This ethanol-induced α4 nAChR upregulation was significantly reduced in rats pretreated with 6 mg/kg dFBr. In TEVC studies, ethanol potentiated ACh-induced currents in α4β2 nAChR, while it slightly reduced dFBr potentiation of maximal ACh currents. CONCLUSIONS Our results suggest that thalamic nAChRs containing the α4 subunit are rapidly upregulated by a single intoxicating dose of ethanol. Furthermore, dFBr, an α4β2 nAChR-selective PAM, significantly attenuates the hypnotic response to ethanol via actions on β2 nAChR. Overall, these results indicate that dFBr represents an option to reverse ethanol intoxication.
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10
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Neurobiology of reward-related learning. Neurosci Biobehav Rev 2021; 124:224-234. [PMID: 33581225 DOI: 10.1016/j.neubiorev.2021.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 11/23/2022]
Abstract
A major goal in psychology is to understand how environmental stimuli associated with primary rewards come to function as conditioned stimuli, acquiring the capacity to elicit similar responses to those elicited by primary rewards. Our neurobiological model is predicated on the Hebbian idea that concurrent synaptic activity on the primary reward neural substrate-proposed to be ventral tegmental area (VTA) dopamine (DA) neurons-strengthens the synapses involved. We propose that VTA DA neurons receive both a strong unconditioned stimulus signal (acetylcholine stimulation of DA cells) from the primary reward capable of unconditionally activating DA cells and a weak stimulus signal (glutamate stimulation of DA cells) from the neutral stimulus. Through joint stimulation the weak signal is potentiated and capable of activating the VTA DA cells, eliciting a conditioned response. The learning occurs when this joint stimulation initiates intracellular second-messenger cascades resulting in enhanced glutamate-DA synapses. In this review we present evidence that led us to propose this model and the most recent evidence supporting it.
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11
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Tabbara RI, Rahbarnia A, Lê AD, Fletcher PJ. The pharmacological stressor yohimbine, but not U50,488, increases responding for conditioned reinforcers paired with ethanol or sucrose. Psychopharmacology (Berl) 2020; 237:3689-3702. [PMID: 32840668 DOI: 10.1007/s00213-020-05647-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/18/2020] [Indexed: 12/19/2022]
Abstract
RATIONALE Environmental stimuli paired with alcohol can function as conditioned reinforcers (CRfs) and trigger relapse to alcohol-seeking. In animal models, pharmacological stressors can enhance alcohol consumption and reinstate alcohol-seeking, but it is unknown whether stress can potentiate the conditioned reinforcing properties of alcohol-paired stimuli. OBJECTIVES We examined whether the pharmacological stressors, the α-2 adrenoreceptor antagonist yohimbine (vehicle, 1.25, 2.5 mg/kg; IP) and the K-opioid receptor agonist U50,488 (vehicle, 1.25, 2.5 mg/kg; SC), increase responding for conditioned reinforcement, and if their effects interact with the nature of the reward (alcohol vs. sucrose). We subsequently examined the effects of yohimbine (vehicle, 1.25, 2.5 mg/kg; IP) on responding for sensory reinforcement. METHODS Male Long-Evans underwent Pavlovian conditioning, wherein a tone-light conditioned stimulus (CS) was repeatedly paired with 12% EtOH or 21.7% sucrose. Next, tests of responding for a CRf were conducted. Responding on the CRf lever delivered the CS, whereas responding on the other lever had no consequences. In a separate cohort of rats, the effects of yohimbine on responding just for the sensory reinforcer were examined. RESULTS Both doses of yohimbine, but not U50,488, increased responding for conditioned reinforcement. This enhancement occurred independently of the nature of the reward used during Pavlovian conditioning. Yohimbine-enhanced responding for a CRf was reproducible and stable over five tests; it even persisted when the CS was omitted. Both doses of yohimbine also increased responding for sensory reinforcement. CONCLUSIONS Yohimbine increases operant responding for a variety of sensory and conditioned reinforcers. This enhancement may be independent of its stress-like effects.
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Affiliation(s)
- Rayane I Tabbara
- Section of Biopsychology, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada. .,Department of Psychology, University of Toronto, Toronto, ON, Canada.
| | - Arya Rahbarnia
- Section of Biopsychology, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.,Department of Psychology, University of Toronto, Toronto, ON, Canada
| | - Anh D Lê
- Neurobiology of Alcohol Laboratory, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.,Department of Psychiatry, University of Toronto, Toronto, ON, Canada.,Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
| | - Paul J Fletcher
- Section of Biopsychology, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.,Department of Psychology, University of Toronto, Toronto, ON, Canada.,Department of Psychiatry, University of Toronto, Toronto, ON, Canada
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12
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Spontaneous Ultrasonic Vocalization Transmission in Adult, Male Long-Evans Rats Is Age-Dependent and Sensitive to EtOH Modulation. Brain Sci 2020; 10:brainsci10110890. [PMID: 33266373 PMCID: PMC7700419 DOI: 10.3390/brainsci10110890] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 01/01/2023] Open
Abstract
Ultrasonic vocalizations (USVs) are well-established markers of motivational and emotional status. Recent work from our lab has provided novel evidence for a role of USVs in models of ethanol (EtOH) use. For instance, USV acoustic characteristics can be used to accurately discriminate between rats selectively bred for high EtOH intake (e.g., alcohol-preferring (P) and high-alcohol-drinking (HAD)) versus EtOH-avoiding (e.g., alcohol-non-preferring (NP) and low-alcohol-drinking (LAD)) strains, as well as differentiate between male and female rats. In the present study we sought to explore the effect of age and alcohol availability on spontaneously emitted 50–55 kHz frequency modulated (FM) and 22–28 kHz USVs in adult, male Long–Evans rats. With the hypothesis that age and alcohol experience influence spontaneous USV emissions, we examined USV data collected across a 24-week intermittent EtOH access experiment in male Long–Evans rats. USV counts and acoustic characteristic (i.e., mean frequency, duration, bandwidth and power) data revealed distinct age-dependent phenotypes in both 50–55 kHz FM and 22–28 kHz USV transmission patterns that were modulated by EtOH exposure. These results highlight the influence of age and EtOH experience on the unique emotional phenotypes of male Long–Evans rats.
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Söderpalm B, Danielsson K, Bejczy A, Adermark L, Ericson M. Combined administration of varenicline and bupropion produces additive effects on accumbal dopamine and abolishes the alcohol deprivation effect in rats. Addict Biol 2020; 25:e12807. [PMID: 31293045 DOI: 10.1111/adb.12807] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 04/15/2019] [Accepted: 06/07/2019] [Indexed: 01/08/2023]
Abstract
Alcohol use disorder (AUD) is detrimental to health and causes preterm death. Unfortunately, available pharmacological and nonpharmacological treatments have small effect sizes, and improved treatments are needed. Smoking and AUD share heritability and are pharmacologically associated, since drug-induced dopamine (DA) output in nucleus accumbens (nAc) involves nicotinic acetylcholine receptors (nAChRs) in both cases. Smoking therapy agents, such as the partial nAChR agonist varenicline or the DA/noradrenaline transporter inhibitor bupropion, could potentially also be used for AUD. To investigate this hypothesis, the effects of varenicline, bupropion, or a combination of the two on nAc DA levels, ethanol intake, and the alcohol deprivation effect (ADE) were examined. In vivo microdialysis showed that varenicline (1.5 mg/kg) and bupropion (2.5, 5, or 10 mg/kg) elevated nAc DA levels and that the combination produced additive effects. Five days treatment with varenicline, bupropion, or the combination did not suppress ethanol consumption, as compared with vehicle-treated control. However, combined administration of varenicline and bupropion completely blocked the ADE when readministering ethanol following 14 days of abstinence. Since ADE is considered highly predictive for the clinical outcome in man, our data suggest that the combination of varenicline and bupropion could be a promising treatment for AUD.
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Affiliation(s)
- Bo Söderpalm
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of Gothenburg Gothenburg Sweden
- BeroendeklinikenSahlgrenska University Hospital Gothenburg Sweden
| | - Klara Danielsson
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of Gothenburg Gothenburg Sweden
| | - Andrea Bejczy
- BeroendeklinikenSahlgrenska University Hospital Gothenburg Sweden
| | - Louise Adermark
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of Gothenburg Gothenburg Sweden
| | - Mia Ericson
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of Gothenburg Gothenburg Sweden
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Valyear MD, Glovaci I, Zaari A, Lahlou S, Trujillo-Pisanty I, Andrew Chapman C, Chaudhri N. Dissociable mesolimbic dopamine circuits control responding triggered by alcohol-predictive discrete cues and contexts. Nat Commun 2020; 11:3764. [PMID: 32724058 PMCID: PMC7534644 DOI: 10.1038/s41467-020-17543-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 07/06/2020] [Indexed: 01/01/2023] Open
Abstract
Context can influence reactions to environmental cues and this elemental process has implications for substance use disorder. Using an animal model, we show that an alcohol-associated context elevates entry into a fluid port triggered by a conditioned stimulus (CS) that predicted alcohol (CS-triggered alcohol-seeking). This effect persists across multiple sessions and, after it diminishes in extinction, the alcohol context retains the capacity to augment reinstatement. Systemically administered eticlopride and chemogenetic inhibition of ventral tegmental area (VTA) dopamine neurons reduce CS-triggered alcohol-seeking. Chemogenetically silencing VTA dopamine terminals in the nucleus accumbens (NAc) core reduces CS-triggered alcohol-seeking, irrespective of context, whereas silencing VTA dopamine terminals in the NAc shell selectively reduces the elevation of CS-triggered alcohol-seeking in an alcohol context. This dissociation reveals new roles for divergent mesolimbic dopamine circuits in the control of responding to a discrete cue for alcohol and in the amplification of this behaviour in an alcohol context.
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Affiliation(s)
- Milan D Valyear
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, QC, Canada
| | - Iulia Glovaci
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, QC, Canada
| | - Audrey Zaari
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, QC, Canada
| | - Soraya Lahlou
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, QC, Canada
| | - Ivan Trujillo-Pisanty
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, QC, Canada
| | - C Andrew Chapman
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, QC, Canada
| | - Nadia Chaudhri
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, QC, Canada.
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Vallöf D, Kalafateli AL, Jerlhag E. Brain region-specific neuromedin U signalling regulates alcohol-related behaviours and food intake in rodents. Addict Biol 2020; 25:e12764. [PMID: 31069918 PMCID: PMC7187236 DOI: 10.1111/adb.12764] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 03/26/2019] [Accepted: 03/27/2019] [Indexed: 12/21/2022]
Abstract
Albeit neuromedin U (NMU) attenuates alcohol‐mediated behaviours, its mechanisms of action are poorly defined. Providing that the behavioural effects of alcohol are processed within the nucleus accumbens (NAc) shell, anterior ventral tegmental area (aVTA), and laterodorsal tegmental area (LDTg), we assessed the involvement of NMU signalling in the aforementioned areas on alcohol‐mediated behaviours in rodents. We further examined the expression of NMU and NMU receptor 2 (NMUR2) in NAc and the dorsal striatum of high compared with low alcohol‐consuming rats, as this area is of importance in the maintenance of alcohol use disorder (AUD). Finally, we investigated the involvement of NAc shell, aVTA and LDTg in the consumption of chow and palatable peanut butter, to expand the link between NMU and reward‐related behaviours. We demonstrated here, that NMU into the NAc shell, but not aVTA or LDTg, blocked the ability of acute alcohol to cause locomotor stimulation and to induce memory retrieval of alcohol reward, as well as reduced peanut butter in mice. In addition, NMU into NAc shell decreased alcohol intake in rats. On a molecular level, we found increased NMU and decreased NMUR2 expression in the dorsal striatum in high compared with low alcohol‐consuming rats. Both aVTA and LDTg, rather than NAc shell, were identified as novel sites of action for NMU's anorexigenic properties in mice based on NMU's ability to selectively reduce chow intake when injected to these areas. Collectively, these data indicate that NMU signalling in different brain areas selectively modulates different behaviours.
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Affiliation(s)
- Daniel Vallöf
- Institute of Neuroscience and Physiology, Department of PharmacologyThe Sahlgrenska Academy at the University of Gothenburg Gothenburg Sweden
| | - Aimilia Lydia Kalafateli
- Institute of Neuroscience and Physiology, Department of PharmacologyThe Sahlgrenska Academy at the University of Gothenburg Gothenburg Sweden
| | - Elisabet Jerlhag
- Institute of Neuroscience and Physiology, Department of PharmacologyThe Sahlgrenska Academy at the University of Gothenburg Gothenburg Sweden
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16
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Quiroz G, Sotomayor-Zárate R, González-Gutierrez JP, Vizcarra F, Moraga F, Bermudez I, Reyes-Parada M, Quintanilla ME, Lagos D, Rivera-Meza M, Iturriaga-Vásquez P. UFR2709, a Nicotinic Acetylcholine Receptor Antagonist, Decreases Ethanol Intake in Alcohol-Preferring Rats. Front Pharmacol 2019; 10:1429. [PMID: 31849674 PMCID: PMC6901503 DOI: 10.3389/fphar.2019.01429] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 11/08/2019] [Indexed: 12/18/2022] Open
Abstract
Brain nicotinic acetylcholine receptors (nAChRs), a heterogeneous family of pentameric acetylcholine-gated cation channels, have been suggested as molecular targets for the treatment of alcohol abuse and dependence. Here, we examined the effect of the competitive nAChR antagonist UFR2709 on the alcohol consumption of high-alcohol-drinking UChB rats. UChB rats were given free access to ethanol for 24-h periods in a two-bottle free choice paradigm and their ethanol and water intake were measured. The animals were i.p. injected daily for 17 days with a 10, 5, 2.5, or 1 mg/kg dose of UFR2709. Potential confounding motor effects of UFR2709 were assessed by examining the locomotor activity of animals administered the highest dose of UR2709 tested (10 mg/kg i.p.). UFR2709 reduced ethanol consumption and ethanol preference and increased water consumption in a dose-dependent manner. The most effective dose of UFR2709 was 2.5 mg/kg, which induced a 56% reduction in alcohol consumption. Administration of UFR2709 did not affect the weight or locomotor activity of the rats, suggesting that its effects on alcohol consumption and preference were mediated by specific nAChRs.
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Affiliation(s)
- Gabriel Quiroz
- Programa de Doctorado en Farmacología, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Ramón Sotomayor-Zárate
- Laboratorio de Neuroquímica y Neurofarmacología, Centro de Neurobiología y Fisiopatología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | | | - Franco Vizcarra
- Laboratorio de Síntesis Orgánica y Farmacología Molecular, Departamento de Ciencias Químicas y Recursos Naturales, Facultad de Ingeniería y Ciencias, Universidad de la Frontera, Temuco, Chile
| | - Felipe Moraga
- Laboratorio de Síntesis Orgánica y Farmacología Molecular, Departamento de Ciencias Químicas y Recursos Naturales, Facultad de Ingeniería y Ciencias, Universidad de la Frontera, Temuco, Chile
| | - Isabel Bermudez
- Deptartment of Biological & Medical Sciences, Faculty of Health & Life Sciences, Oxford Brookes University, Oxford, United Kingdom
| | - Miguel Reyes-Parada
- Centro de Investigación Biomédica y Aplicada (CIBAP), Escuela de Medicina, Facultad de Ciencias Médicas, Universidad de Santiago de Chile, Santiago, Chile.,Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - María Elena Quintanilla
- Programa de Farmacología Molecular y Clínica, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Diego Lagos
- Departamento de Química Farmacológica y Toxicológica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Mario Rivera-Meza
- Departamento de Química Farmacológica y Toxicológica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Patricio Iturriaga-Vásquez
- Laboratorio de Síntesis Orgánica y Farmacología Molecular, Departamento de Ciencias Químicas y Recursos Naturales, Facultad de Ingeniería y Ciencias, Universidad de la Frontera, Temuco, Chile.,Center of Excellence in Biotechnology Research Applied to the Environment, Universidad de La Frontera, Temuco, Chile
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17
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Mangan D, McNabola N, Clark EH, Bermudez I, Wonnacott S, Southern JM. Ethyl-for-methyl substitution enhances the subtype specificity of mecamylamine analogues. Org Biomol Chem 2019; 17:9892-9905. [PMID: 31713564 DOI: 10.1039/c9ob01993f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis of novel mecamylamine analogues is described in which one, two or three of the methyl groups of mecamylamine have been systematically replaced with ethyl groups. Assessment of the compounds highlights that simple ethyl for methyl changes changes to the parent structure can dramatically enhance activity and selectivity towards either the α4β2 (at the expense of α3β4) or the α3β4 (at the expense of α4β2) nicotinic acetylcholine receptor sub-type as compared to the parent compound.
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Affiliation(s)
- David Mangan
- Trinity Biomedical Sciences Institute, School of Chemistry, The University of Dublin, Trinity College, Dublin 2, Ireland.
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18
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Lamb R, Ginsburg BC, Greig A, Schindler CW. Effects of rat strain and method of inducing ethanol drinking on Pavlovian-Instrumental-Transfer with ethanol-paired conditioned stimuli. Alcohol 2019; 79:47-57. [PMID: 30641121 DOI: 10.1016/j.alcohol.2019.01.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 01/04/2019] [Accepted: 01/07/2019] [Indexed: 12/21/2022]
Abstract
Ethanol-paired conditioned stimuli (CSs) are widely thought to invigorate ethanol responding, and thus, precipitate relapse to drinking. However, preclinical studies investigating this issue using Pavlovian-Instrumental-Transfer (PIT) procedures have had mixed results, with some studies finding PIT while others did not. The studies failing to show PIT used Lewis rats and induced ethanol drinking using a post-prandial drinking procedure. The present experiments examined whether either of these two variables influenced the magnitude of PIT observed. In the first experiment, ethanol drinking in Lewis rats was induced using either sucrose fading or post-prandial drinking. In the second experiment, ethanol drinking was induced using post-prandial drinking in either Long-Evans Hooded or Lewis rats. In both experiments, rats were trained to respond for ethanol under a random interval schedule. Subsequently with the lever removed, 2-min light presentations were paired with ethanol deliveries. Finally, with the lever returned, the effect of light presentations on responding was tested while responding was in extinction. Light presentations similarly affected responding in Lewis rats regardless of the method of drinking induction. Likewise, light presentations similarly affected responding in both Lewis and Long-Evans Hooded rats. Neither ethanol induction method nor rat strain affected the magnitude of PIT observed, and thus, neither likely explains previous failures to observe PIT with ethanol-maintained behavior.
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19
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Nunes EJ, Bitner L, Hughley SM, Small KM, Walton SN, Rupprecht LE, Addy NA. Cholinergic Receptor Blockade in the VTA Attenuates Cue-Induced Cocaine-Seeking and Reverses the Anxiogenic Effects of Forced Abstinence. Neuroscience 2019; 413:252-263. [PMID: 31271832 DOI: 10.1016/j.neuroscience.2019.06.028] [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: 03/07/2019] [Revised: 05/31/2019] [Accepted: 06/19/2019] [Indexed: 02/08/2023]
Abstract
Drug relapse after periods of abstinence is a common feature of substance abuse. Moreover, anxiety and other mood disorders are often co-morbid with substance abuse. Cholinergic receptors in the ventral tegmental area (VTA) are known to mediate drug-seeking and anxiety-related behavior in rodent models. However, it is unclear if overlapping VTA cholinergic mechanisms mediate drug relapse and anxiety-related behaviors associated with drug abstinence. We examined the effects of VTA cholinergic receptor blockade on cue-induced cocaine seeking and anxiety during cocaine abstinence. Male Sprague-Dawley rats were trained to self-administer intravenous cocaine (~0.5 mg/kg/infusion, FR1 schedule) for 10 days, followed by 14 days of forced abstinence. VTA infusion of the non-selective nicotinic acetylcholine receptor antagonist mecamylamine (0, 10, and 30 μg/side) or the non-selective muscarinic receptor antagonist scopolamine (0, 2.4 and 24 μg /side) significantly decreased cue-induced cocaine seeking. In cocaine naïve rats, VTA mecamylamine or scopolamine also led to dose-dependent increases in open arm time in the elevated plus maze (EPM). In contrast, rats that received I.V. cocaine, compared to received I.V. saline rats, displayed an anxiogenic response on day 14 of abstinence as reflected by decreased open arm time in the EPM. Furthermore, low doses of VTA mecamylamine (10 μg /side) or scopolamine (2.4 μg /side), that did not alter EPM behavior in cocaine naive rats, were sufficient to reverse the anxiogenic effects of cocaine abstinence. Together, these data point to an overlapping role of VTA cholinergic mechanisms to regulate relapse and mood disorder-related responses during cocaine abstinence.
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Affiliation(s)
- Eric J Nunes
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511, USA
| | - Lillian Bitner
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511, USA
| | - Shannon M Hughley
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511, USA
| | - Keri M Small
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511, USA
| | - Sofia N Walton
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511, USA
| | - Laura E Rupprecht
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511, USA
| | - Nii A Addy
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511, USA; Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06511, USA; Interdepartmental Neuroscience Program, Yale University, New Haven, CT 06511, USA.
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20
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Brain region specific glucagon-like peptide-1 receptors regulate alcohol-induced behaviors in rodents. Psychoneuroendocrinology 2019; 103:284-295. [PMID: 30771711 DOI: 10.1016/j.psyneuen.2019.02.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 02/04/2019] [Accepted: 02/06/2019] [Indexed: 01/03/2023]
Abstract
Glucagon-like peptide 1 (GLP-1), an incretin hormone that reduces food intake, was recently established as a novel regulator of alcohol-mediated behaviors. Clinically available analogues pass freely into the brain, but the mechanisms underlying GLP-1-modulated alcohol reward remains largely unclear. GLP-1 receptors (GLP-1R) are expressed throughout the nuclei of importance for acute and chronic effects of alcohol, such as the laterodorsal tegmental area (LDTg), the ventral tegmental area (VTA) and the nucleus accumbens (NAc). We therefore evaluated the effects of bilateral infusion of the GLP-1R agonist exendin-4 (Ex4) into NAc shell, anterior (aVTA), posterior (pVTA) or LDTg on the acute alcohol-induced locomotor stimulation and memory of alcohol reward in the conditioned place preference (CPP) model in mice, as well as on alcohol intake in rats consuming high amounts of alcohol for 12 weeks. Ex4 into the NAc shell blocks alcohol-induced locomotor stimulation and memory of alcohol reward as well as decreases alcohol intake. The GLP-1R expression in NAc is elevated in high compared to low alcohol-consuming rats. On the contrary, GLP-1R activation in the aVTA does not modulate alcohol-induced behaviors. Ex4 into the pVTA prevents alcohol-induced locomotor simulation, but does neither modulate CPP-dependent alcohol memory nor alcohol intake. Intra-LDTg-Ex4 attenuates alcohol-induced locomotor stimulation and reduces alcohol intake, but does not affect memory of alcohol reward. Collectively, these data provide additional knowledge of the functional role of GLP-1R in reward-related areas for alcohol-mediated behaviors and further support GLP-1R as a potential treatment target for alcohol use disorder.
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Gao F, Chen D, Ma X, Sudweeks S, Yorgason JT, Gao M, Turner D, Eaton JB, McIntosh JM, Lukas RJ, Whiteaker P, Chang Y, Steffensen SC, Wu J. Alpha6-containing nicotinic acetylcholine receptor is a highly sensitive target of alcohol. Neuropharmacology 2019; 149:45-54. [PMID: 30710570 PMCID: PMC7323585 DOI: 10.1016/j.neuropharm.2019.01.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 01/01/2019] [Accepted: 01/17/2019] [Indexed: 02/05/2023]
Abstract
Alcohol use disorder (AUD) is a serious public health problem that results in tremendous social, legal and medical costs to society. Unlike other addictive drugs, there is no specific molecular target for ethanol (EtOH). Here, we report a novel molecular target that mediates EtOH effects at concentrations below those that cause legally-defined inebriation. Using patch-clamp recording of human α6*-nicotinic acetylcholine receptor (α6*-nAChR) function when heterologously expressed in SH-EP1 human epithelial cells, we found that 0.1-5 mM EtOH significantly enhances α6*-nAChR-mediated currents with effects that are dependent on both EtOH and nicotine concentrations. EtOH exposure increased both whole-cell current rising slope and decay constants. This EtOH modulation was selective for α6*-nAChRs since it did not affect α3β4-, α4β2-, or α7-nAChRs. In addition, 5 mM EtOH also increased the frequency and amplitude of dopaminergic neuron transients in mouse brain nucleus accumbens slices, that were blocked by the α6*-nAChR antagonist, α-conotoxin MII, suggesting a role for native α6*-nAChRs in low-dose EtOH effects. Collectively, our data suggest that α6*-nAChRs are sensitive targets mediating low-dose EtOH effects through a positive allosteric mechanism, which provides new insight into mechanisms involved in pharmacologically-relevant alcohol effects contributing to AUD.
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Affiliation(s)
- Fenfei Gao
- Department of Pharmacology, Shantou University Medical College, Shantou, Guangdong, 51504, China; Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Dejie Chen
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA; Department of Neurology, Yunfu People's Hospital, Yunfu, Guangdong, 527300, China
| | - Xiaokuang Ma
- Department of Pharmacology, Shantou University Medical College, Shantou, Guangdong, 51504, China; Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Sterling Sudweeks
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT, 84602, USA
| | - Jordan T Yorgason
- Department of Psychology and Neuroscience, Brigham Young University, Provo, UT, 84602, USA
| | - Ming Gao
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Dharshaun Turner
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Jason Brek Eaton
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - J Michael McIntosh
- George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, UT, USA 84108, USA
| | - Ronald J Lukas
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Paul Whiteaker
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Yongchang Chang
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Scott C Steffensen
- Department of Psychology and Neuroscience, Brigham Young University, Provo, UT, 84602, USA
| | - Jie Wu
- Department of Pharmacology, Shantou University Medical College, Shantou, Guangdong, 51504, China; Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA; Department of Neurology, Yunfu People's Hospital, Yunfu, Guangdong, 527300, China.
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22
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Spanos M, Xie X, Gras-Najjar J, White SC, Sombers LA. NMDA Receptor-Dependent Cholinergic Modulation of Mesolimbic Dopamine Cell Bodies: Neurochemical and Behavioral Studies. ACS Chem Neurosci 2019; 10:1497-1505. [PMID: 30412381 DOI: 10.1021/acschemneuro.8b00492] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Substance abuse disorders are devastating, costly, and difficult to treat. Identifying the neurochemical mechanisms underlying reinforcement promises to provide critical information in the development of effective treatments. Several lines of evidence suggest that striatal dopamine (DA) release serves as a teaching signal in reinforcement learning, and that shifts in DA release from the primary reward to reward-predicting stimuli play a critical role in the self-administration of both natural and non-natural rewards. However, far less is known about the reinforcing effects of motivationally neutral sensory stimuli, or how these signals can facilitate self-administration behavior. Thus, we trained rats ( n = 7) to perform a visual stimulus-induced instrumental task, which involved lever pressing for activation of a stimulus light. We then microinfused vehicle (phosphate buffered saline), carbachol (acetylcholine receptor agonist), or carbachol in the presence of an N-methyl-d-aspartate (NMDA) receptor-specific drug (NMDA itself, or the antagonist, AP5) into the ventral tegmental area (VTA). This enabled us to directly evaluate how chemical modulation of dopamine cell bodies affects the instrumental behavior, as well as the nature of extracellular dopamine transients recorded in the nucleus accumbens shell (NAc shell) using fast-scan cyclic voltammetry (FSCV). Intra-VTA infusion of carbachol enhanced the magnitude and frequency of dopamine transients in the NAc shell and potentiated active lever responding without altering inactive lever responding, as compared to infusion of vehicle. Coinfusion of carbachol with AP5 abolished dopamine transients recorded in the NAc and attenuated active lever responding without altering inactive lever responding. Finally, coadministration of carbachol and NMDA into the VTA restored both lever pressing and dopaminergic signals recorded in the striatum. Together, these results suggest that acetylcholine and glutamate synergistically act at dopamine cells in the VTA to modulate VTA-NAc shell dopaminergic output, and this underlies motivation to lever press for a motivationally neutral visual stimulus.
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Affiliation(s)
- Marina Spanos
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Xiaohu Xie
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Julie Gras-Najjar
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Stephanie C. White
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Leslie A. Sombers
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
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Wolter M, Huff E, Speigel T, Winters BD, Leri F. Cocaine, nicotine, and their conditioned contexts enhance consolidation of object memory in rats. ACTA ACUST UNITED AC 2019; 26:46-55. [PMID: 30651377 PMCID: PMC6340119 DOI: 10.1101/lm.048579.118] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 12/18/2018] [Indexed: 12/28/2022]
Abstract
To test the hypothesis that drugs of abuse and their conditioned stimuli (CSs) enhance memory consolidation, the effects of post-training exposure to cocaine and nicotine were compared to the effects of post-training exposure to contextual stimuli that were paired with the effects of these drugs. Using the object recognition (OR) task, it was first demonstrated that both 10 and 20 mg/kg cocaine, and 0.2 and 0.4 mg/kg nicotine, enhanced recognition memory when administered immediately after, but not 6 h after the sample phase. To establish the drug CSs, rats were confined for 2 h in a chamber (the CS+) after injections of 20 mg/kg cocaine, or 0.4 mg/kg nicotine, and in another chamber (the CS−) after injections of vehicle. This was repeated over 10 d (5 drug/CS+ and 5 vehicle/CS− pairings in total). At the end of this conditioning period, when tested in a drug-free state, rats displayed conditioned hyperactivity in the CS+ relative to the CS−. More important, immediate, but not delayed, post-sample exposure to the cocaine CS+, or nicotine CS+, enhanced OR memory. Therefore, this study reports for the first time that contextual stimuli paired with cocaine and nicotine, like the drugs themselves, have the ability to enhance memory consolidation.
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Affiliation(s)
- Michael Wolter
- Department of Psychology and Collaborative Program in Neuroscience, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Ethan Huff
- Department of Psychology and Collaborative Program in Neuroscience, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Talia Speigel
- Department of Psychology and Collaborative Program in Neuroscience, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Boyer D Winters
- Department of Psychology and Collaborative Program in Neuroscience, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Francesco Leri
- Department of Psychology and Collaborative Program in Neuroscience, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Jerlhag E. Gut-brain axis and addictive disorders: A review with focus on alcohol and drugs of abuse. Pharmacol Ther 2018; 196:1-14. [PMID: 30439457 DOI: 10.1016/j.pharmthera.2018.11.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Due to the limited efficacy of existing medications for addictive disorders including alcohol use disorder (AUD), the need for additional medications is substantial. Potential new medications for addiction can be identified through investigation of the neurochemical substrates mediating the ability of drugs of abuse such as alcohol to activate the mesolimbic dopamine system. Interestingly, recent studies implicate neuropeptides of the gut-brain axis as modulators of reward and addiction processes. The present review therefore summarizes the current studies investigating the ability of the gut-brain peptides ghrelin, glucagon-like peptide-1 (GLP-1), amylin and neuromedin U (NMU) to modulate alcohol- and drug-related behaviors in rodents and humans. Extensive literature demonstrates that ghrelin, the only known orexigenic neuropeptide to date, enhances reward as well as the intake of alcohol, and other drugs of abuse, while ghrelin receptor antagonism has the opposite effects. On the other hand, the anorexigenic peptides GLP-1, amylin and NMU independently inhibits reward from alcohol and drugs of abuse in rodents. Collectively, these rodent and human studies imply that central ghrelin, GLP-1, amylin and NMU signaling may contribute to addiction processes. Therefore, the need for randomized clinical trials investigating the effects of agents targeting these aforementioned systems on drug/alcohol use is substantial.
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Affiliation(s)
- Elisabet Jerlhag
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
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Quiroz G, Guerra-Díaz N, Iturriaga-Vásquez P, Rivera-Meza M, Quintanilla ME, Sotomayor-Zárate R. Erysodine, a competitive antagonist at neuronal nicotinic acetylcholine receptors, decreases ethanol consumption in alcohol-preferring UChB rats. Behav Brain Res 2018; 349:169-176. [PMID: 29704599 DOI: 10.1016/j.bbr.2018.04.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 04/20/2018] [Accepted: 04/23/2018] [Indexed: 12/20/2022]
Abstract
Alcohol abuse is a worldwide health problem with high economic costs to health systems. Emerging evidence suggests that modulation of brain nicotinic acetylcholine receptors (nAChRs) may be a therapeutic target for alcohol dependence. In this work, we assess the effectiveness of four doses of erysodine (1.5, 2.0, 4.0 or 8.0 mg/kg/day, i.p.), a competitive antagonist of nAChRs, on voluntary ethanol consumption behavior in alcohol-preferring UChB rats, administered during three consecutive days. Results show that erysodine administration produces a dose-dependent reduction in ethanol consumption respect to saline injection (control group). The highest doses of erysodine (4 and 8 mg/kg) reduce (45 and 66%, respectively) the ethanol intake during treatment period and first day of post-treatment compared to control group. While, the lowest doses of erysodine (1.5 and 2 mg/kg) only reduce ethanol intake during one day of treatment period. These effective reductions in ethanol intake were 23 and 29% for 1.5 and 2 mg/kg erysodine, respectively. Locomotor activity induced by a high dose of erysodine (10 mg/kg) was similar to those observed with saline injection in control rats, showing that the reduction in ethanol intake was not produced by hypolocomotor effect induced by erysodine. This is the first report showing that erysodine reduces ethanol intake in UChB rats in a dose-dependent manner. Our results highlight the role of nAChRs in the reward effects of ethanol and its modulation as a potentially effective pharmacological alternative for alcohol dependence treatment.
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Affiliation(s)
- Gabriel Quiroz
- Programa de Doctorado en Farmacología, Universidad de Chile, Santiago, Chile
| | - Nicolás Guerra-Díaz
- Programa de Doctorado en Química, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Patricio Iturriaga-Vásquez
- Laboratorio de Farmacoquímica, Departamento de Ciencias Químicas y Recursos Naturales, Facultad de Ingeniería y Ciencias, Universidad de la Frontera, Temuco, Chile
| | - Mario Rivera-Meza
- Departamento de Química Farmacológica y Toxicológica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - María Elena Quintanilla
- Programa de Farmacología Molecular y Clínica, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
| | - Ramón Sotomayor-Zárate
- Laboratorio de Neuroquímica y Neurofarmacología, CENFI, Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.
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Ho AL, Salib AMN, Pendharkar AV, Sussman ES, Giardino WJ, Halpern CH. The nucleus accumbens and alcoholism: a target for deep brain stimulation. Neurosurg Focus 2018; 45:E12. [DOI: 10.3171/2018.5.focus18157] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Alcohol use disorder (AUD) is a difficult to treat condition with a significant global public health and cost burden. The nucleus accumbens (NAc) has been implicated in AUD and identified as an ideal target for deep brain stimulation (DBS). There are promising preclinical animal studies of DBS for alcohol consumption as well as some initial human clinical studies that have shown some promise at reducing alcohol-related cravings and, in some instances, achieving long-term abstinence. In this review, the authors discuss the evidence and concepts supporting the role of the NAc in AUD, summarize the findings from published NAc DBS studies in animal models and humans, and consider the challenges and propose future directions for neuromodulation of the NAc for the treatment of AUD.
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Affiliation(s)
| | - Anne-Mary N. Salib
- Departments of 1Neurosurgery and
- 2Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California
| | | | | | - William J. Giardino
- 2Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California
| | - Casey H. Halpern
- Departments of 1Neurosurgery and
- 2Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California
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Nucleus Accumbens Microcircuit Underlying D2-MSN-Driven Increase in Motivation. eNeuro 2018; 5:eN-NWR-0386-17. [PMID: 29780881 PMCID: PMC5957524 DOI: 10.1523/eneuro.0386-18.2018] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 02/23/2018] [Accepted: 02/28/2018] [Indexed: 01/11/2023] Open
Abstract
The nucleus accumbens (NAc) plays a central role in reinforcement and motivation. Around 95% of the NAc neurons are medium spiny neurons (MSNs), divided into those expressing dopamine receptor D1 (D1R) or dopamine receptor D2 (D2R). Optogenetic activation of D2-MSNs increased motivation, whereas inhibition of these neurons produced the opposite effect. Yet, it is still unclear how activation of D2-MSNs affects other local neurons/interneurons or input terminals and how this contributes for motivation enhancement. To answer this question, in this work we combined optogenetic modulation of D2-MSNs with in loco pharmacological delivery of specific neurotransmitter antagonists in rats. First, we showed that optogenetic activation of D2-MSNs increases motivation in a progressive ratio (PR) task. We demonstrated that this behavioral effect relies on cholinergic-dependent modulation of dopaminergic signalling of ventral tegmental area (VTA) terminals, which requires D1R and D2R signalling in the NAc. D2-MSN optogenetic activation decreased ventral pallidum (VP) activity, reducing the inhibitory tone to VTA, leading to increased dopaminergic activity. Importantly, optogenetic activation of D2-MSN terminals in the VP was sufficient to recapitulate the motivation enhancement. In summary, our data suggests that optogenetic stimulation of NAc D2-MSNs indirectly modulates VTA dopaminergic activity, contributing for increased motivation. Moreover, both types of dopamine receptors signalling in the NAc are required in order to produce the positive behavioral effects.
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Touchette JC, Maertens JJ, Mason MM, O'Rourke KY, Lee AM. The nicotinic receptor drug sazetidine-A reduces alcohol consumption in mice without affecting concurrent nicotine consumption. Neuropharmacology 2018; 133:63-74. [PMID: 29355641 PMCID: PMC5858984 DOI: 10.1016/j.neuropharm.2018.01.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 01/09/2018] [Accepted: 01/13/2018] [Indexed: 01/01/2023]
Abstract
Alcohol and nicotine addiction are frequently co-morbid. The nicotinic acetylcholine receptors (nAChRs) are critical for both alcohol and nicotine addiction mechanisms, since nAChR drugs that reduce nicotine consumption have been shown to also reduce alcohol consumption. Sazetidine-A, a pre-clinical nAChR drug with agonist and desensitizing effects at α4β2 and α7 nAChRs, has been reported to reduce alcohol consumption and nicotine self-administration in rats when administered at high doses. However, this effect has not been replicated in mice. In this study, we examined the effect of sazetidine-A on alcohol and nicotine consumption in male and female mice utilizing voluntary oral consumption procedures previously developed in our lab. We found that sazetidine-A (1 mg/kg, i.p) reduced overnight alcohol consumption, but did not affect nicotine consumption when presented either alone or concurrently with alcohol. Sazetidine-A did not reduce water or saccharin consumption at any dose tested. In a chronic co-consumption experiment in which either alcohol or nicotine was re-introduced after one week of forced abstinence, sazetidine-A attenuated post-abstinence consumption of alcohol but not nicotine. Sazetidine-A also significantly reduced alcohol consumption in an acute, binge drinking-in-the-dark procedure. Finally, we tested the effect of sazetidine-A on alcohol withdrawal, and found that sazetidine-A significantly reduced handling-induced convulsions during alcohol withdrawal. Collectively, these data suggest a novel role for the nAChR targets of sazetidine-A in specifically mediating alcohol consumption, separate from the involvement of nAChRs in mediating nicotine consumption. Delineation of this pathway may provide insight into novel therapies for the treatment of alcohol use disorders.
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Affiliation(s)
| | - Jamie J Maertens
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Margaret M Mason
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Kyu Y O'Rourke
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Anna M Lee
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA.
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Klenowski PM, Tapper AR. Molecular, Neuronal, and Behavioral Effects of Ethanol and Nicotine Interactions. Handb Exp Pharmacol 2018; 248:187-212. [PMID: 29423839 DOI: 10.1007/164_2017_89] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Söderpalm B, Lidö HH, Ericson M. The Glycine Receptor-A Functionally Important Primary Brain Target of Ethanol. Alcohol Clin Exp Res 2017; 41:1816-1830. [PMID: 28833225 DOI: 10.1111/acer.13483] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 08/15/2017] [Indexed: 12/27/2022]
Abstract
Identification of ethanol's (EtOH) primary molecular brain targets and determination of their functional role is an ongoing, important quest. Pentameric ligand-gated ion channels, that is, the nicotinic acetylcholine receptor, the γ-aminobutyric acid type A receptor, the 5-hydroxytryptamine3 , and the glycine receptor (GlyR), are such targets. Here, aspects of the structure and function of these receptors and EtOH's interaction with them are briefly reviewed, with special emphasis on the GlyR and the importance of this receptor and its ligands for EtOH pharmacology. It is suggested that GlyRs are involved in (i) the dopamine-activating effect of EtOH, (ii) regulating EtOH intake, and (iii) the relapse preventing effect of acamprosate. Exploration of the GlyR subtypes involved and efforts to develop subtype specific agonists or antagonists may offer new pharmacotherapies for alcohol use disorders.
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Affiliation(s)
- Bo Söderpalm
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Helga H Lidö
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Mia Ericson
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
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Effects of varenicline on alcohol cue reactivity in heavy drinkers. Psychopharmacology (Berl) 2017; 234:2737-2745. [PMID: 28600734 PMCID: PMC5709183 DOI: 10.1007/s00213-017-4667-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/30/2017] [Indexed: 12/31/2022]
Abstract
RATIONALE Clinical trials and human laboratory studies have established that varenicline can reduce rates of alcohol use among heavy drinkers. Less is known about the mechanisms by which varenicline has this effect on drinking behavior. Reactivity to alcohol cues is often cited as the primary cause of relapse among those being treated for alcohol use disorder, and several front-line treatments for alcohol use disorder work, at least in part, by minimizing cue-induced alcohol craving. OBJECTIVE The current double-blind, placebo-controlled human laboratory study tested the effects of varenicline on alcohol cue reactivity in a group of heavy-drinking adult smokers and nonsmokers. METHODS As part of a larger series of sequential human laboratory experiments testing the effects of varenicline on drinking outcomes, participants were assigned (between-participant) to receive either active varenicline (2 mg/day) or placebo. Following a titration period, participants (n = 77) attended a laboratory session during which they were exposed to alcohol and neutral cues using a standard cue reactivity paradigm. RESULTS Alcohol cue exposure increased craving for alcohol in both medication groups. However, participants receiving varenicline showed a smaller increase in alcohol craving compared to participants receiving placebo. The medication effect did not differ between smokers and nonsmokers. Among smokers, alcohol cue exposure also increased tobacco craving. Varenicline did not attenuate this effect. CONCLUSIONS Results support the use of varenicline for reducing alcohol use in heavy drinkers and identify a potential mechanism by which varenicline reduces drinking. Varenicline continues to show promise as a pharmacological treatment for alcohol use disorder.
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Alcohol-seeking and relapse: A focus on incentive salience and contextual conditioning. Behav Processes 2017; 141:26-32. [DOI: 10.1016/j.beproc.2017.04.019] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/27/2017] [Accepted: 04/28/2017] [Indexed: 01/05/2023]
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Varenicline Reduces Context-Induced Relapse to Alcohol-Seeking through Actions in the Nucleus Accumbens. Neuropsychopharmacology 2017; 42:1037-1048. [PMID: 27834390 PMCID: PMC5506798 DOI: 10.1038/npp.2016.254] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 10/31/2016] [Accepted: 11/02/2016] [Indexed: 11/08/2022]
Abstract
Varenicline, a pharmacotherapy for tobacco addiction, reduces alcohol consumption in humans and rodents. The therapeutic potential of varenicline would escalate if it also diminished conditioned responses elicited by alcohol-predictive cues, which can precipitate relapse in abstinent individuals. We investigated this application, along with the underlying neural substrates, using a robust preclinical assay in which relapse to alcohol-seeking was triggered by re-exposure to an alcohol-associated environmental context. Male, Long-Evans rats received Pavlovian conditioning sessions in which one auditory conditioned stimulus (CS+) was paired with 15% ethanol and a second conditioned stimulus (CS-) was not. Ethanol was delivered into a port for oral consumption and port entries triggered by each CS were recorded. Extinction was then conducted in a different context where the CS+ and CS- were presented without ethanol. To stimulate relapse, both cues were subsequently presented without ethanol in the prior conditioning context. Systemic varenicline (0, 0.5 or 2.5 mg/kg; intraperitoneal) blocked context-induced relapse to alcohol-seeking without affecting the ability to make a port entry. It also reduced context-induced relapse to sucrose-seeking, but only at the 2.5 mg/kg dose. Neuropharmacological studies showed that context-induced relapse to alcohol-seeking was attenuated by bilateral microinfusion of varenicline (0.3 μl/side) into the nucleus accumbens (NAc; 0 or 3.5 μg), but not the ventral tegmental area (0, 2 or 4 μg). These data show for the first time that varenicline reduces relapse triggered by contexts that predict alcohol, and suggest that nicotinic acetylcholine receptors in the NAc are critical for this effect.
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Nicotine-induced enhancement of Pavlovian alcohol-seeking behavior in rats. Psychopharmacology (Berl) 2017; 234:727-738. [PMID: 28011981 DOI: 10.1007/s00213-016-4508-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 12/09/2016] [Indexed: 01/02/2023]
Abstract
RATIONALE Nicotine enhances responding elicited by Pavlovian cues that predict positive outcomes. OBJECTIVES We tested the hypothesis that nicotine acting at nicotinic acetylcholine receptors (nAChRs) would augment Pavlovian alcohol-seeking. METHODS Male, Long-Evans rats with unrestricted access to food and water were acclimated to drinking 15% ethanol in their home cages and then given Pavlovian conditioning sessions in which each trial of a 15-s conditioned stimulus (CS, 12 trials/session) was paired with 0.2 ml of ethanol (unconditioned stimulus, US, 2.4 ml/session). Entries into a port where ethanol was delivered were used to assess conditioning. Control groups received explicitly unpaired trials of the CS and US. In experiment 1, systemic injections of saline (1 ml/kg) or nicotine (0.4 mg/kg, freebase) were administered before each session. In experiments 2 and 3, an identical regimen of saline or nicotine injections was administered before the start of Pavlovian conditioning sessions. RESULTS All paired groups acquired conditioned port-entry responding to the CS, indicative of Pavlovian alcohol-seeking, whereas unpaired control group did not. Pre-session nicotine injections increased CS port-entries relative to saline, only in the paired group. This nicotine-induced enhancement of Pavlovian alcohol-seeking was blocked by pre-treatment with the nAChR antagonist mecamylamine. Prior exposure to nicotine did not influence the subsequent acquisition of Pavlovian alcohol-seeking. CONCLUSIONS These findings highlight for the first time that nicotine acting at nAChRs augments Pavlovian alcohol-seeking, specifically in non-restricted rats. Individuals who smoke and drink may thus be particularly susceptible to alcohol cues that could trigger further drinking.
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Mangan D, McNabola N, Clark EH, Bermudez I, Wonnacott S, Southern JM. A new synthesis and preliminary evaluation of some analogues of mecamylamine - a compound with anti-addiction properties. Org Biomol Chem 2016; 14:10787-10798. [PMID: 27812593 DOI: 10.1039/c6ob01974a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new synthesis of mecamylamine - a known anti-hypertensive drug with anti-addictive properties is described. The new route allowed access to two novel analogues whose activity at two nicotinic acetylcholine receptor subtypes was assessed.
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Affiliation(s)
- David Mangan
- Trinity Biomedical Sciences Institute, School of Chemistry, The University of Dublin, Trinity College, Dublin 2, Ireland.
| | - Neasa McNabola
- Trinity Biomedical Sciences Institute, School of Chemistry, The University of Dublin, Trinity College, Dublin 2, Ireland.
| | - Emily H Clark
- Department of Biology & Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - Isabel Bermudez
- School of Life Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Susan Wonnacott
- Department of Biology & Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - J Mike Southern
- Trinity Biomedical Sciences Institute, School of Chemistry, The University of Dublin, Trinity College, Dublin 2, Ireland.
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Srisontiyakul J, Kastman HE, Krstew EV, Govitrapong P, Lawrence AJ. The Nicotinic α6-Subunit Selective Antagonist bPiDI Reduces Alcohol Self-Administration in Alcohol-Preferring Rats. Neurochem Res 2016; 41:3206-3214. [PMID: 27573375 DOI: 10.1007/s11064-016-2045-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 08/22/2016] [Accepted: 08/24/2016] [Indexed: 10/21/2022]
Abstract
Cigarettes and alcohol are the most abused substances in the world and are commonly co-abused. Nicotine primarily acts in the brain on nicotinic acetylcholine receptors (nAChR), which are also a target for alcohol. The alpha6 subunit of nAChR is expressed almost exclusively in the brain reward system and may modulate the rewarding properties of alcohol and nicotine. Recently, N,N-decane-1,10-diyl-bis-3-picolinium diiodide (bPiDI) was synthesized as a selective, brain penetrant α6 subunit antagonist that reduces nicotine self-administration. The current study aimed to examine the effects of bPiDI on alcohol self-administration in inbred alcohol-preferring (iP) rats. Adult, male iP rats were trained to self-administer alcohol or sucrose. Once stable responding was achieved, rats were injected with bPiDI (1, 3 mg/kg, i.p.) and tested for self-administration under fixed and progressive ratio schedules of reinforcement. They subsequently underwent extinction, in which no rewards or cues were presented in the operant chambers. Then, they were injected with bPiDI prior to testing for cue-induced reinstatement of reward seeking. bPiDI (3 mg/kg) significantly reduced alcohol self-administration in both fixed and progressive ratios without any effects on sucrose self-administration or locomotor activity. In contrast, bPiDI (3 mg/kg) did not inhibit cue-induced reinstatement of either alcohol or sucrose seeking. The results support the involvement of α6 containing nAChR in reinforcing effects of alcohol, but not relapse to alcohol-seeking, without any impact on responding for a natural reward or general activity. bPiDI may be a potential lead molecule for a therapeutic strategy to limit nicotine and alcohol consumption.
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Affiliation(s)
- Jirawoot Srisontiyakul
- Research Center for Neuroscience, Institute of Molecular Biosciences, Mahidol University, Salaya, Nakhon Pathom, Thailand
| | - Hanna E Kastman
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Royal Parade, Parkville, VIC, 3052, Australia
| | - Elena V Krstew
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Royal Parade, Parkville, VIC, 3052, Australia
| | - Piyarat Govitrapong
- Research Center for Neuroscience, Institute of Molecular Biosciences, Mahidol University, Salaya, Nakhon Pathom, Thailand.,Center for Neuroscience and Department of Pharmacology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Andrew J Lawrence
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Royal Parade, Parkville, VIC, 3052, Australia. .,Florey Department of Neuroscience, University of Melbourne, Parkville, VIC, Australia.
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37
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Roche DJO, Ray LA, Yardley MM, King AC. Current insights into the mechanisms and development of treatments for heavy drinking cigarette smokers. CURRENT ADDICTION REPORTS 2016; 3:125-137. [PMID: 27162709 PMCID: PMC4859339 DOI: 10.1007/s40429-016-0081-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
There is a strong association between cigarette smoking and alcohol use at the epidemiological, behavioral, and molecular levels, and this co-use creates substantial impediments to smoking cessation among smokers who are also heavy drinkers. Compared with individuals who only smoke, those who both drink and smoke heavily experience more severe health consequences and have greater difficulty in quitting smoking. During smoking abstinence, greater alcohol use is associated with decreased odds of smoking cessation, and smokers are substantially more likely to experience a smoking lapse during drinking episodes. As heavy drinking smokers are less responsive to the currently available pharmacological treatments, this subgroup of high-risk substance users possesses a unique clinical profile and treatment needs. Thus, treatment development for heavy drinking smokers represents a significant and understudied research area within the field of smoking cessation. This review will briefly describe findings from epidemiological, behavioral, and molecular studies illustrating alcohol and tobacco co-use and identify how the behavioral and neurobiological mechanisms underlying the interaction of alcohol and nicotine may inform the development of targeted treatments for this unique population of smokers.
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Affiliation(s)
- Daniel J O Roche
- University of California, Los Angeles, Department of Psychology, Los Angeles, CA, 90095, USA
| | - Lara A Ray
- University of California, Los Angeles, Department of Psychology, Los Angeles, CA, 90095, USA; University of California, Los Angeles, Department of Psychiatry and Biobehavioral Sciences, Los Angeles, CA, 90095, USA
| | - Megan M Yardley
- University of California, Los Angeles, Department of Psychology, Los Angeles, CA, 90095, USA
| | - Andrea C King
- University of Chicago, Department of Psychiatry and Behavioral Neuroscience, Chicago, IL 60637, USA
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Addy NA, Nunes EJ, Wickham RJ. Muscarinic, but not nicotinic, acetylcholine receptor blockade in the ventral tegmental area attenuates cue-induced sucrose-seeking. Behav Brain Res 2015; 291:372-376. [PMID: 26026787 PMCID: PMC4497829 DOI: 10.1016/j.bbr.2015.05.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 05/02/2015] [Accepted: 05/22/2015] [Indexed: 11/20/2022]
Abstract
The mesolimbic dopamine (DA) system is known to play a role in cue-mediated reward-seeking for natural rewards and drugs of abuse. Specifically, cholinergic and glutamatergic receptors in the ventral tegmental area (VTA) have been shown to regulate cue-induced drug-seeking. However, the potential role of these VTA receptors in regulating cue-induced reward seeking for natural rewards is unknown. Here, we examined whether blockade of VTA acetylcholine receptors (AChRs) and N-methyl-d-aspartate receptors (NMDARs) would alter cue-induced sucrose seeking in male Sprague-Dawley rats. Subjects underwent 10 days of sucrose self-administration training (fixed ratio 1 schedule) followed by 7 days of forced abstinence. On withdrawal day 7, rats received bilateral VTA infusion of vehicle, the muscarinic AChR antagonist scopolamine (2.4 or 24 μg/side), the nicotinic AChR antagonist mecamylamine (3 or 30 μg/side), or the NMDAR antagonist AP-5 (0.1 or 1 μg/side) immediately prior to examination of cue-induced sucrose-seeking. Scopolamine infusion led to robust attenuation, but did not completely block, sucrose-seeking behavior. In contrast, VTA administration of mecamylamine or AP-5 did not alter cue-induced sucrose-seeking. Together, the data suggest that VTA muscarinic AChRs, but not nicotinic AChRs nor NMDARs, facilitate the ability of food-associated cues to drive seeking behavior for a food reward.
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Affiliation(s)
- Nii A Addy
- Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT 06511, USA; Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06511, USA; Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06511, USA.
| | - Eric J Nunes
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06511, USA
| | - Robert J Wickham
- Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT 06511, USA
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Wickham RJ, Solecki WB, Nunes EJ, Addy NA. Distinct effects of ventral tegmental area NMDA and acetylcholine receptor blockade on conditioned reinforcement produced by food-associated cues. Neuroscience 2015; 301:384-94. [PMID: 26093048 PMCID: PMC4510872 DOI: 10.1016/j.neuroscience.2015.06.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 06/10/2015] [Accepted: 06/11/2015] [Indexed: 02/08/2023]
Abstract
Stimuli paired with rewards acquire reinforcing properties to promote reward-seeking behavior. Previous work supports the role of ventral tegmental area (VTA) nicotinic acetylcholine receptors (nAChRs) in mediating conditioned reinforcement elicited by drug-associated cues. However, it is not known whether these cholinergic mechanisms are specific to drug-associated cues or whether VTA cholinergic mechanisms also underlie the ability of cues paired with natural rewards to act as conditioned reinforcers. Burst firing of VTA dopamine (DA) neurons and the subsequent phasic DA release in the nucleus accumbens (NAc) plays an important role in cue-mediated behavior and in the ability of cues to acquire reinforcing properties. In the VTA, both AChRs and N-methyl-d-aspartate receptors (NMDARs) regulate DA burst firing and phasic DA release. Here, we tested the role of VTA nAChRs, muscarinic AChRs (mAChRs), and NMDARs in the conditioned reinforcement elicited by a food-associated, natural reward cue. Subjects received 10 consecutive days of Pavlovian conditioning training where lever extension served as a predictive cue for food availability. On day 11, rats received bilateral VTA infusion of saline, AP-5 (0.1 or 1μg), mecamylamine (MEC: 3 or 30μg) or scopolamine (SCOP: 3 or 66.7μg) immediately prior to the conditioned reinforcement test. During the test, nosepoking into the active (conditioned reinforced, CR) noseport produced a lever cue while nosepoking on the inactive (non-conditioned reinforced, NCR) noseport had no consequence. AP-5 robustly attenuated conditioned reinforcement and blocked discrimination between CR and NCR noseports at the 1-μg dose. MEC infusion decreased responding for both CR and NCR while 66.7-μg SCOP disrupted the subject's ability to discriminate between CR and NCR. Together, our data suggest that VTA NMDARs and mAChRs, but not nAChRs, play a role in the ability of natural reward-associated cues to act as conditioned reinforcers.
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Affiliation(s)
- R J Wickham
- Interdepartmental Neuroscience Program, Yale Graduate School of Arts and Sciences, New Haven, CT 06520, USA
| | - W B Solecki
- Interdepartmental Neuroscience Program, Yale Graduate School of Arts and Sciences, New Haven, CT 06520, USA
| | - E J Nunes
- Interdepartmental Neuroscience Program, Yale Graduate School of Arts and Sciences, New Haven, CT 06520, USA
| | - N A Addy
- Interdepartmental Neuroscience Program, Yale Graduate School of Arts and Sciences, New Haven, CT 06520, USA; Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511, USA; Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT 06511, USA.
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Engle SE, McIntosh JM, Drenan RM. Nicotine and ethanol cooperate to enhance ventral tegmental area AMPA receptor function via α6-containing nicotinic receptors. Neuropharmacology 2014; 91:13-22. [PMID: 25484253 DOI: 10.1016/j.neuropharm.2014.11.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 11/11/2014] [Accepted: 11/22/2014] [Indexed: 01/16/2023]
Abstract
Nicotine + ethanol co-exposure results in additive and/or synergistic effects in the ventral tegmental area (VTA) to nucleus accumbens (NAc) dopamine (DA) pathway, but the mechanisms supporting this are unclear. We tested the hypothesis that nAChRs containing α6 subunits (α6* nAChRs) are involved in the response to nicotine + ethanol co-exposure. Exposing VTA slices from C57BL/6 WT animals to drinking-relevant concentrations of ethanol causes a marked enhancement of α-amino-3-hydroxy-5-methyl-isoxazolepropionic acid (AMPA) receptor (AMPAR) function in VTA neurons. This effect was sensitive to α-conotoxin MII (an α6β2* nAChR antagonist), suggesting that α6* nAChR function is required. In mice expressing hypersensitive α6* nAChRs (α6L9S mice), we found that lower concentrations (relative to C57BL/6 WT) of ethanol were sufficient to enhance AMPAR function in VTA neurons. Exposure of live C57BL/6 WT mice to ethanol also produced AMPAR functional enhancement in VTA neurons, and studies in α6L9S mice strongly suggest a role for α6* nAChRs in this response. We then asked whether nicotine and ethanol cooperate to enhance VTA AMPAR function. We identified low concentrations of nicotine and ethanol that were capable of strongly enhancing VTA AMPAR function when co-applied to slices, but that did not enhance AMPAR function when applied alone. This effect was sensitive to both varenicline (an α4β2* and α6β2* nAChR partial agonist) and α-conotoxin MII. Finally, nicotine + ethanol co-exposure also enhanced AMPAR function in VTA neurons from α6L9S mice. Together, these data identify α6* nAChRs as important players in the response to nicotine + ethanol co-exposure in VTA neurons.
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Affiliation(s)
- Staci E Engle
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
| | - J Michael McIntosh
- George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, UT 84148, USA; Departments of Psychiatry and Biology, University of Utah, Salt Lake City, UT 84148, USA
| | - Ryan M Drenan
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA.
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Hauser SR, Deehan GA, Toalston JE, Bell RL, McBride WJ, Rodd ZA. Enhanced alcohol-seeking behavior by nicotine in the posterior ventral tegmental area of female alcohol-preferring (P) rats: modulation by serotonin-3 and nicotinic cholinergic receptors. Psychopharmacology (Berl) 2014; 231:3745-55. [PMID: 24599396 PMCID: PMC4516288 DOI: 10.1007/s00213-014-3508-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 02/12/2014] [Indexed: 12/13/2022]
Abstract
RATIONALE Alcohol and nicotine co-use can reciprocally promote self-administration and drug-craving/drug-seeking behaviors. To date, the neurocircuitry in which nicotine influences ethanol (EtOH) seeking has not been elucidated. Clinical and preclinical research has suggested that the activation of the mesolimbic dopamine system is involved in the promotion of drug seeking. Alcohol, nicotine, and serotonin-3 (5-HT3) receptors interact within the posterior ventral tegmental area (pVTA) to regulate drug reward. Recently, our laboratory has reported that systemic administration of nicotine can promote context-induced EtOH seeking. OBJECTIVES The goals of the current study were to (1) determine if microinjections of pharmacologically relevant levels of nicotine into the pVTA would enhance EtOH seeking, (2) determine if coadministration of nicotinic cholinergic receptor antagonist (nACh) or 5-HT3 receptor antagonists would block the ability of nicotine microinjected into the pVTA to promote EtOH seeking, and (3) determine if 5-HT3 receptors in the pVTA can modulate EtOH seeking. RESULTS Nicotine (100 and 200 μM) microinjected into the pVTA enhanced EtOH seeking. Coinfusion with 200 μM mecamylamine (nACh antagonist) or 100 and 200 μM zacopride (5-HT3 receptor antagonist) blocked the observed nicotine enhancement of EtOH seeking. The data also indicated that microinjection of 1 μM CPBG (5-HT3 receptor agonist) promotes context-induced EtOH seeking; conversely, microinjection of 100 and 200 μM zacopride alone reduced context-induced EtOH seeking. CONCLUSIONS Overall, the results show that nicotine-enhanced EtOH-seeking behavior is modulated by 5-HT3 and nACh receptors within the pVTA and that the 5-HT3 receptor system within pVTA may be a potential pharmacological target to inhibit EtOH-seeking behaviors.
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Affiliation(s)
- Sheketha R Hauser
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, 791 Union Drive, Indianapolis, IN, 46202-4887, USA,
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Raabe RC, Mathies LD, Davies AG, Bettinger JC. The omega-3 fatty acid eicosapentaenoic acid is required for normal alcohol response behaviors in C. elegans. PLoS One 2014; 9:e105999. [PMID: 25162400 PMCID: PMC4146551 DOI: 10.1371/journal.pone.0105999] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 08/01/2014] [Indexed: 12/18/2022] Open
Abstract
Alcohol addiction is a widespread societal problem, for which there are few treatments. There are significant genetic and environmental influences on abuse liability, and understanding these factors will be important for the identification of susceptible individuals and the development of effective pharmacotherapies. In humans, the level of response to alcohol is strongly predictive of subsequent alcohol abuse. Level of response is a combination of counteracting responses to alcohol, the level of sensitivity to the drug and the degree to which tolerance develops during the drug exposure, called acute functional tolerance. We use the simple and well-characterized nervous system of Caenorhabditis elegans to model the acute behavioral effects of ethanol to identify genetic and environmental factors that influence level of response to ethanol. Given the strong molecular conservation between the neurobiological machinery of worms and humans, cellular-level effects of ethanol are likely to be conserved. Increasingly, variation in long-chain polyunsaturated fatty acid levels has been implicated in complex neurobiological phenotypes in humans, and we recently found that fatty acid levels modify ethanol responses in worms. Here, we report that 1) eicosapentaenoic acid, an omega-3 polyunsaturated fatty acid, is required for the development of acute functional tolerance, 2) dietary supplementation of eicosapentaenoic acid is sufficient for acute tolerance, and 3) dietary eicosapentaenoic acid can alter the wild-type response to ethanol. These results suggest that genetic variation influencing long-chain polyunsaturated fatty acid levels may be important abuse liability loci, and that dietary polyunsaturated fatty acids may be an important environmental modulator of the behavioral response to ethanol.
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Affiliation(s)
- Richard C. Raabe
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Laura D. Mathies
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Andrew G. Davies
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, United States of America
- VCU-Alcohol Research Center, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Jill C. Bettinger
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, United States of America
- VCU-Alcohol Research Center, Virginia Commonwealth University, Richmond, Virginia, United States of America
- * E-mail:
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Adermark L, Söderpalm B, Burkhardt JM. Brain region specific modulation of ethanol-induced depression of GABAergic neurons in the brain reward system by the nicotine receptor antagonist mecamylamine. Alcohol 2014; 48:455-61. [PMID: 24961541 DOI: 10.1016/j.alcohol.2014.06.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The mechanisms underlying ethanol-induced activation of the mesolimbic dopamine system are not fully understood, but increased extracellular dopamine in the nucleus accumbens (nAc) has been shown to involve nicotinic acetylcholine receptors (nAChRs). Basal activity of dopaminergic neurons in the ventral tegmental area (VTA) is under the influence of GABAergic neurotransmission, and the aim of this study was to characterize the involvement of nAChRs in mediating acute ethanol effects on GABAergic activity in subregions of the brain reward system. Multi-electrode in vivo recordings were made in the VTA and nAc of awake and behaving C57BL6/J mice receiving intraperitoneal injections of saline or ethanol (2.0 g/kg), combined with, or without, pre-injection of the non-competitive nAChR antagonist mecamylamine (1.0 mg/kg). Ethanol significantly decreased the activity of quinpirole-insensitive slow-spiking and fast-spiking units in both the VTA and the nAc as compared to saline injection. Pre-treatment with mecamylamine inhibited the rate-inhibiting properties of ethanol in the VTA, but not in the nAc. The data presented here show that ethanol depresses the activity of quinpirole-insensitive, putative GABAergic neurons, in the mesolimbic dopamine system of mice, and that nAChRs contribute to this modulation. This finding, taken together with previous microdialysis studies, supports an involvement of GABAergic neurons and nAChRs in ethanol's interaction with the mesolimbic dopamine system.
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Brunzell DH, McIntosh JM, Papke RL. Diverse strategies targeting α7 homomeric and α6β2* heteromeric nicotinic acetylcholine receptors for smoking cessation. Ann N Y Acad Sci 2014; 1327:27-45. [PMID: 24730978 DOI: 10.1111/nyas.12421] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Preclinical studies suggest that a diversity of nicotinic acetylcholine receptors (nAChRs) with different sensitivities to nicotine may contribute to tobacco addiction. Using rodent intravenous nicotine self-administration as a preclinical model with good predictive validity for therapeutic efficacy for tobacco cessation, investigators have identified heteromeric α6β2* and homomeric α7 nAChRs as promising novel therapeutic targets to promote smoking abstinence (*denotes possible assembly with other subunits). The data suggest that diverse strategies that target these subclasses of nAChRs, namely inhibition of α6β2* nAChRs and stimulation of α7 nAChRs, will support tobacco cessation. α6β2* nAChRs, members of the high-affinity family of β2* nAChRs, function similarly to α4β2* nAChRs, the primary target of the FDA-approved drug varenicline, but have a much more selective neuroanatomical pattern of expression in catecholaminergic nuclei. Although activation of β2* nAChRs facilitates nicotine self-administration, stimulation of α7 nAChRs appears to negatively modulate both nicotine reinforcement and β2* nAChR function in the mesolimbic dopamine system. Although challenges and caveats must be considered in the development of therapeutics that target these nAChR subpopulations, an accumulation of data suggests that α7 nAChR agonists, partial agonists, or positive allosteric modulators and α6β2* nAChR antagonists, partial agonists, or negative allosteric modulators may prove to be effective therapeutics for tobacco cessation.
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Affiliation(s)
- Darlene H Brunzell
- Department of Pharmacology and Toxicology, Interdisciplinary Neuroscience Program and Institute for Drug and Alcohol Studies, Virginia Commonwealth University School of Medicine, Richmond, Virginia
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Wu J, Gao M, Taylor DH. Neuronal nicotinic acetylcholine receptors are important targets for alcohol reward and dependence. Acta Pharmacol Sin 2014; 35:311-5. [PMID: 24464050 DOI: 10.1038/aps.2013.181] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 12/18/2013] [Indexed: 01/01/2023] Open
Abstract
Neuronal nicotinic acetylcholine receptors are important targets for alcohol reward and dependence. Alcoholism is a serious public health problem and has been identified as the third major cause of preventable mortality in the world. Worldwide, about 2 billion people consume alcohol, with 76.3 million having diagnosable alcohol use disorders. Alcohol is currently responsible for the death of 4% of adults worldwide (about 2.5 million deaths each year), and this number will be significantly increased by 2020 unless effective action is taken. Alcohol is the most commonly abused substance by humans. Ethanol (EtOH) is the intoxicating agent in alcoholic drinks that can lead to abuse and dependence. Although it has been extensively studied, the mechanisms of alcohol reward and dependence are still poorly understood. The major reason is that, unlike other addictive drugs (eg, morphine, cocaine or nicotine) that have specific molecular targets, EtOH affects much wider neuronal functions. These functions include phospholipid membranes, various ion channels and receptors, synaptic and network functions, and intracellular signaling molecules. The major targets in the brain that mediate EtOH's effects remain unclear. This knowledge gap results in a therapeutic barrier in the treatment of alcoholism. Interestingly, alcohol and nicotine are often co-abused, which suggests that neuronal nicotinic acetylcholine receptors (nAChRs), the molecular targets for nicotine, may also contribute to alcohol's abusive properties. Here, we briefly summarize recent lines of evidence showing how EtOH modulates nAChRs in the mesolimbic pathway, which provides a perspective that nAChRs are important targets mediating alcohol abuse.
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Engel JA, Jerlhag E. Role of appetite-regulating peptides in the pathophysiology of addiction: implications for pharmacotherapy. CNS Drugs 2014; 28:875-86. [PMID: 24958205 PMCID: PMC4181507 DOI: 10.1007/s40263-014-0178-y] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Food intake and appetite are regulated by various circulating hormones including ghrelin and glucagon-like-peptide 1 (GLP-1). Ghrelin, mainly released from the stomach, increases food intake, induces appetite, enhances adiposity as well as releases growth hormone. Hypothalamic "ghrelin receptors" (GHS-R1A) have a critical role in food intake regulation, but GHS-R1A are also expressed in reward related areas. GLP-1 is produced in the intestinal mucosa as well as in the hindbrain in response to nutrient ingestion. This gut-brain hormone reduces food intake as well as regulates glucose homeostasis, foremost via GLP-1 receptors in hypothalamus and brain stem. However, GLP-1 receptors are expressed in areas intimately associated with reward regulation. Given that regulation of food and drug intake share common neurobiological substrates, the possibility that ghrelin and GLP-1 play an important role in reward regulation should be considered. Indeed, this leading article describes that the orexigenic peptide ghrelin activates the cholinergic-dopaminergic reward link, an important part of the reward systems in the brain associated with reinforcement and thereby increases the incentive salience for motivated behaviors via this system. We also review the role of ghrelin signaling for reward induced by alcohol and addictive drugs from a preclinical, clinical and human genetic perspective. In addition, the recent findings showing that GLP-1 controls reward induced by alcohol, amphetamine, cocaine and nicotine in rodents are overviewed herein. Finally, the role of several other appetite regulatory hormones for reward and addiction is briefly discussed. Collectively, these data suggest that ghrelin and GLP-1 receptors may be novel targets for development of pharmacological treatments of alcohol and drug dependence.
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Affiliation(s)
- Jörgen A. Engel
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, POB 431, 405 30 Gothenburg, Sweden
| | - Elisabet Jerlhag
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, POB 431, 405 30 Gothenburg, Sweden
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Jerlhag E, Engel JA. Local infusion of low, but not high, doses of alcohol into the anterior ventral tegmental area causes release of accumbal dopamine. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ojpsych.2014.41008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Wang Y, Lee JW, Oh G, Grady SR, McIntosh JM, Brunzell DH, Cannon JR, Drenan RM. Enhanced synthesis and release of dopamine in transgenic mice with gain-of-function α6* nAChRs. J Neurochem 2013; 129:315-27. [PMID: 24266758 DOI: 10.1111/jnc.12616] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 11/19/2013] [Accepted: 11/19/2013] [Indexed: 12/21/2022]
Abstract
α6β2* nicotinic acetylcholine receptors (nAChRs)s in the ventral tegmental area to nucleus accumbens (NAc) pathway are implicated in the response to nicotine, and recent work suggests these receptors play a role in the rewarding action of ethanol. Here, we studied mice expressing gain-of-function α6β2* nAChRs (α6L9'S mice) that are hypersensitive to nicotine and endogenous acetylcholine. Evoked extracellular dopamine (DA) levels were enhanced in α6L9'S NAc slices compared to control, non-transgenic (non-Tg) slices. Extracellular DA levels in both non-Tg and α6L9'S slices were further enhanced in the presence of GBR12909, suggesting intact DA transporter function in both mouse strains. Ongoing α6β2* nAChR activation by acetylcholine plays a role in enhancing DA levels, as α-conotoxin MII completely abolished evoked DA release in α6L9'S slices and decreased spontaneous DA release from striatal synaptosomes. In HPLC experiments, α6L9'S NAc tissue contained significantly more DA, 3,4-dihydroxyphenylacetic acid, and homovanillic acid compared to non-Tg NAc tissue. Serotonin (5-HT), 5-hydroxyindoleacetic acid, and norepinephrine (NE) were unchanged in α6L9'S compared to non-Tg tissue. Western blot analysis revealed increased tyrosine hydroxylase expression in α6L9'S NAc. Overall, these results show that enhanced α6β2* nAChR activity in NAc can stimulate DA production and lead to increased extracellular DA levels.
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Affiliation(s)
- Yuexiang Wang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
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50
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Quick SL, Olausson P, Addy NA, Taylor JR. Repeated nicotine exposure during adolescence alters reward-related learning in male and female rats. Behav Brain Res 2013; 261:171-6. [PMID: 24333376 DOI: 10.1016/j.bbr.2013.12.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 11/08/2013] [Accepted: 12/02/2013] [Indexed: 11/26/2022]
Abstract
RATIONALE Repeated nicotine exposure causes neuroadaptations in limbic cortico-striatal circuits involved in learning and motivation. Such alterations are relevant to addiction because they are suggested to mediate the ability of smoking-associated stimuli to control behavior and to enhance nicotine-seeking and -taking behaviors. Female smokers report higher cue reactivity relative to their male counter parts, yet little is known about putative gender-specific effects of adolescent nicotine exposure on reward-related learning. Prior repeated nicotine exposure in adult male rats enhances Pavlovian approach behavior and conditioned reinforcement. OBJECTIVE Given that smoking is typically initiated during adolescence, here we assessed the extent to which adolescent nicotine exposure impacts Pavlovian approach and conditioned reinforcement in male and female rats. METHODS Rats were injected with nicotine on postnatal days 31-45 prior to training on Pavlovian approach behavior starting on day 51. They were trained to associate a conditioned stimulus (CS), illumination of a magazine light, and tone, with an unconditioned stimulus (US), the delivery of water, for 10-daily sessions, and then were tested on the acquisition of responding with conditioned reinforcement. RESULTS Adolescent nicotine exposure selectively increased approach to the magazine during the CS in males but decreased approach to the magazine during the CS in female rats. Vehicle-exposed female rats, however, showed greater magazine approach during the CS than did male control rats. Prior nicotine exposure also enhanced conditioned reinforcement in both male and female rats. CONCLUSIONS Repeated exposure to nicotine during adolescence had opposite effects on Pavlovian approach behavior in male and female rats but enhanced acquisition of a new response with conditioned reinforcement. Novel information on how nicotine exposure influences reward-related learning during adolescence may increase our understanding of neurobiological mechanisms involved in the initiation of smoking behavior.
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Affiliation(s)
- Stacey L Quick
- Department of Psychiatry Laboratory of Molecular Psychiatry, Yale University Ribicoff Research Facilities CMHC, 34 Park St New Haven, CT 06519, United States
| | - Peter Olausson
- Department of Psychiatry Laboratory of Molecular Psychiatry, Yale University Ribicoff Research Facilities CMHC, 34 Park St New Haven, CT 06519, United States
| | - Nii A Addy
- Department of Psychiatry Laboratory of Molecular Psychiatry, Yale University Ribicoff Research Facilities CMHC, 34 Park St New Haven, CT 06519, United States
| | - Jane R Taylor
- Department of Psychiatry Laboratory of Molecular Psychiatry, Yale University Ribicoff Research Facilities CMHC, 34 Park St New Haven, CT 06519, United States.
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