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Abstract
Ethanol (EtOH) has effects on numerous cellular molecular targets, and alterations in synaptic function are prominent among these effects. Acute exposure to EtOH activates or inhibits the function of proteins involved in synaptic transmission, while chronic exposure often produces opposing and/or compensatory/homeostatic effects on the expression, localization, and function of these proteins. Interactions between different neurotransmitters (e.g., neuropeptide effects on release of small molecule transmitters) can also influence both acute and chronic EtOH actions. Studies in intact animals indicate that the proteins affected by EtOH also play roles in the neural actions of the drug, including acute intoxication, tolerance, dependence, and the seeking and drinking of EtOH. The present chapter is an update of our previous Lovinger and Roberto (Curr Top Behav Neurosci 13:31-86, 2013) chapter and reviews the literature describing these acute and chronic synaptic effects of EtOH with a focus on adult animals and their relevance for synaptic transmission, plasticity, and behavior.
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Affiliation(s)
- David M Lovinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism (NIAAA), Rockville, MD, USA
| | - Marisa Roberto
- Molecular Medicine Department, Scripps Research Institute, La Jolla, CA, USA.
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2
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Peoples RW, Ren H. Effects of ethanol on GluN1/GluN2A and GluN1/GluN2B NMDA receptor-ion channel gating kinetics. Alcohol Clin Exp Res 2022; 46:2203-2213. [PMID: 36305341 PMCID: PMC9771960 DOI: 10.1111/acer.14965] [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: 03/07/2022] [Revised: 10/20/2022] [Accepted: 10/24/2022] [Indexed: 02/01/2023]
Abstract
BACKGROUND The N-methyl-D-aspartate receptor (NMDAR) is a major molecular target of alcohol action in the central nervous system, yet many aspects of alcohol's modulation of the activity of this ion channel remain unclear. We and others have shown that ethanol inhibition of NMDAR involves alterations in gating, especially a reduction in mean open time. However, a full description of ethanol's effects on NMDAR kinetics, including fitting them to a kinetic model, has not been reported. METHODS To determine ethanol's effects on NMDAR kinetics, we used steady-state single-channel recording in outside-out patches from HEK-293 cells transfected with recombinant GluN1/GluN2A or GluN1/GluN2B NMDAR subunits. Very low glutamate concentrations were used to isolate individual activations of the receptor. RESULTS In both subunit types, ethanol, at approximate whole-cell IC50 values (156 mM, GluN2A; 150 mM, GluN2B), reduced open probability (po ) by approximately 50% and decreased mean open time without changing the frequency of opening. Open and shut time distributions exhibited two and five components, respectively; ethanol selectively decreased the time constant and relative proportion of the longer open time component. In the GluN2A subunit, ethanol increased the time constants of all but the longest shut time components, whereas in the GluN2B subunit, shut times were unchanged by ethanol. Fitting of bursts of openings (representing individual activations of the receptor) to the gating portion of a kinetic model revealed that ethanol altered two rates: the rate associated with activation of the GluN2A or GluN2B subunit, and the rate associated with the closing of the longer of the two open states. CONCLUSIONS These results demonstrate that ethanol selectively alters individual kinetic rates and thus appears to selectively affect distinct conformational transitions involved in NMDAR gating.
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Affiliation(s)
- Robert W Peoples
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Hong Ren
- Biobank, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Filarowska-Jurko J, Komsta L, Smaga I, Surowka P, Marszalek-Grabska M, Grochecki P, Nizio D, Filip M, Kotlinska JH. Maternal Separation Alters Ethanol Drinking and Reversal Learning Processes in Adolescent Rats: The Impact of Sex and Glycine Transporter Type 1 (GlyT1) Inhibitor. Int J Mol Sci 2022; 23:5350. [PMID: 35628160 PMCID: PMC9141364 DOI: 10.3390/ijms23105350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 05/07/2022] [Accepted: 05/09/2022] [Indexed: 11/16/2022] Open
Abstract
Adverse early life experiences are associated with an enhanced risk for mental and physical health problems, including substance abuse. Despite clinical evidence, the mechanisms underlying these relationships are not fully understood. Maternal separation (MS) is a commonly used animal model of early neglect. The aim of the current study is to determine whether the N-methyl-D-aspartate receptor (NMDAR)/glycine sites are involved in vulnerability to alcohol consumption (two-bottle choice paradigm) and reversal learning deficits (Barnes maze task) in adolescent rats subjected to the MS procedure and whether these effects are sex dependent. By using ELISA, we evaluated MS-induced changes in the NMDAR subunits (GluN1, GluN2A, GluN2B) expression, especially in the glycine-binding subunit, GluN1, in the prefrontal cortex (PFC) and ventral striatum (vSTR) of male/female rats. Next, we investigated whether Org 24598, a glycine transporter 1 (GlyT1) inhibitor, was able to modify ethanol drinking in adolescent and adult male/female rats with prior MS experience and reversal learning in the Barnes maze task. Our findings revealed that adolescent MS female rats consumed more alcohol which may be associated with a substantial increase in GluN1 subunit of NMDAR in the PFC and vSTR. Org 24598 decreased ethanol intake in both sexes with a more pronounced decrease in ethanol consumption in adolescent female rats. Furthermore, MS showed deficits in reversal learning in both sexes. Org 24598 ameliorated reversal learning deficits, and this effect was reversed by the NMDAR/glycine site inhibitor, L-701,324. Collectively, our results suggest that NMDAR/glycine sites might be targeted in the treatment of alcohol abuse in adolescents with early MS, especially females.
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Affiliation(s)
- Joanna Filarowska-Jurko
- Department of Pharmacology and Pharmacodynamics, Medical University, Chodzki 4A, 20-093 Lublin, Poland; (J.F.-J.); (P.G.)
| | - Lukasz Komsta
- Department of Medicinal Chemistry, Medical University, Jaczewskiego 4, 20-090 Lublin, Poland;
| | - Irena Smaga
- Department of Drug Addiction Pharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, 31-324 Krakow, Poland; (I.S.); (P.S.); (M.F.)
| | - Paulina Surowka
- Department of Drug Addiction Pharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, 31-324 Krakow, Poland; (I.S.); (P.S.); (M.F.)
| | - Marta Marszalek-Grabska
- Department of Experimental and Clinical Pharmacology, Medical University, Jaczewskiego 8b, 20-090 Lublin, Poland;
| | - Pawel Grochecki
- Department of Pharmacology and Pharmacodynamics, Medical University, Chodzki 4A, 20-093 Lublin, Poland; (J.F.-J.); (P.G.)
| | - Dorota Nizio
- Experimental Medicine Center, Medical University, Jaczewskiego 8, 20-090 Lublin, Poland;
| | - Malgorzata Filip
- Department of Drug Addiction Pharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, 31-324 Krakow, Poland; (I.S.); (P.S.); (M.F.)
| | - Jolanta H. Kotlinska
- Department of Pharmacology and Pharmacodynamics, Medical University, Chodzki 4A, 20-093 Lublin, Poland; (J.F.-J.); (P.G.)
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Sawchuk SD, Reid HMO, Neale KJ, Shin J, Christie BR. Effects of Ethanol on Synaptic Plasticity and NMDA Currents in the Juvenile Rat Dentate Gyrus. Brain Plast 2020; 6:123-136. [PMID: 33680851 PMCID: PMC7903019 DOI: 10.3233/bpl-200110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Background and Objectives: We examined how acute ethanol (EtOH) exposure affects long term depression (LTD) in the dentate gyrus (DG) of the hippocampus in juvenile rats. EtOH is thought to directly modulate n-methyl-D-aspartate receptor (NMDAr) currents, which are believed important for LTD induction. LTD in turn is believed to play an important developmental role in the hippocampus by facilitating synaptic pruning. Methods: Hippocampal slices (350μm) were obtained at post-natal day (PND) 14, 21, or 28. Field EPSPs (excitatory post-synaptic potential) or whole-cell EPSCs (excitatory post-synaptic conductance) were recorded from the DG (dentate gyrus) in response to medial perforant path activation. Low-frequency stimulation (LFS; 900 pulses; 120 s pulse) was used to induce LTD. Results: Whole-cell recordings indicated that EtOH exposure at 50mM did not significantly impact ensemble NMDAr EPSCs in slices obtained from animals in the PND14 or 21 groups, but it reliably produced a modest inhibition in the PND28 group. Increasing the concentration to 100 mM resulted in a modest inhibition of NMDAr EPSCs in all three groups. LTD induction and maintenance was equivalent in magnitude in all three age groups in control conditions, however, and surprisingly, NMDA antagonist AP5 only reliably blocked LTD in the PND21 and 28 age groups. The application of 50 mM EtOH attenuated LTD in all three age groups, however increasing the concentration to 100 mM did not reliably inhibit LTD. Conclusions: These results indicate that the effect of EtOH on NMDAr-EPSCs recorded from DGCs is both age and concentration dependent in juveniles. Low concentrations of EtOH can attenuate, but did not block LTD in the DG. The effects of EtOH on LTD do not align well with it’s effects on NNMDA receptors.
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Affiliation(s)
- Scott D Sawchuk
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Hannah M O Reid
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Katie J Neale
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - James Shin
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Brian R Christie
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada.,Department of Psychology, University of British Columbia, Vancouver, BC, Canada.,Island Medical Program and Department of Cellular and Physiological Sciences, University of British Columbia, Victoria, BC, Canada
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Léger C, Dupré N, Laquerrière A, Lecointre M, Dumanoir M, Janin F, Hauchecorne M, Fabre M, Jégou S, Frébourg T, Cleren C, Leroux P, Marcorelles P, Brasse-Lagnel C, Marret S, Marguet F, Gonzalez BJ. In utero alcohol exposure exacerbates endothelial protease activity from pial microvessels and impairs GABA interneuron positioning. Neurobiol Dis 2020; 145:105074. [PMID: 32890773 DOI: 10.1016/j.nbd.2020.105074] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 08/28/2020] [Accepted: 08/31/2020] [Indexed: 02/06/2023] Open
Abstract
In utero alcohol exposure can induce severe neurodevelopmental disabilities leading to long-term behavioral deficits. Because alcohol induces brain defects, many studies have focused on nervous cells. However, recent reports have shown that alcohol markedly affects cortical angiogenesis in both animal models and infants with fetal alcohol spectrum disorder (FASD). In addition, the vascular system is known to contribute to controlling gamma-aminobutyric acid (GABA)ergic interneuron migration in the developing neocortex. Thus, alcohol-induced vascular dysfunction may contribute to the neurodevelopmental defects in FASD. The present study aimed at investigating the effects of alcohol on endothelial activity of pial microvessels. Ex vivo experiments on cortical slices from mouse neonates revealed that in endothelial cells from pial microvessels acute alcohol exposure inhibits both glutamate-induced calcium mobilization and activities of matrix metalloproteinase-9 (MMP-9) and tissue plasminogen activator (tPA). The inhibitory effect of alcohol on glutamate-induced MMP-9 activity was abrogated in tPA-knockout and Grin1flox/VeCadcre mice suggesting that alcohol interacts through the endothelial NMDAR/tPA/MMP-9 vascular pathway. Contrasting with the effects from acute alcohol exposure, in mouse neonates exposed to alcohol in utero during the last gestational week, glutamate exacerbated both calcium mobilization and endothelial protease activities from pial microvessels. This alcohol-induced vascular dysfunction was associated with strong overexpression of the N-methyl-d-aspartate receptor subunit GluN1 and mispositioning of the Gad67-GFP interneurons that normally populate the superficial cortical layers. By comparing several human control fetuses with a fetus chronically exposed to alcohol revealed that alcohol exposure led to mispositioning of the calretinin-positive interneurons, whose density was decreased in the superficial cortical layers II-III and increased in deepest layers. This study provides the first mechanistic and functional evidence that alcohol impairs glutamate-regulated activity of pial microvessels. Endothelial dysfunction is characterized by altered metalloproteinase activity and interneuron mispositioning, which was also observed in a fetus with fetal alcohol syndrome. These data suggest that alcohol-induced endothelial dysfunction may contribute in ectopic cortical GABAergic interneurons, that has previously been described in infants with FASD.
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Affiliation(s)
- Cécile Léger
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Nicolas Dupré
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Annie Laquerrière
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Maryline Lecointre
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Marion Dumanoir
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - François Janin
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Michelle Hauchecorne
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Maëlle Fabre
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Sylvie Jégou
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Thierry Frébourg
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Carine Cleren
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Philippe Leroux
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | | | - Carole Brasse-Lagnel
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Stéphane Marret
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Florent Marguet
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Bruno J Gonzalez
- Normandie Univ, UNIROUEN, INSERM U1245 and Rouen University Hospital, Department of Neonatal Paediatrics and Intensive Care, F 76000, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.
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Clozapine, nimodipine and endosulfan differentially suppress behavioral defects caused by gain-of-function mutations in a two-pore domain K + channel (UNC-58). Neurosci Res 2020; 170:41-49. [PMID: 32681854 DOI: 10.1016/j.neures.2020.07.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 07/07/2020] [Accepted: 07/13/2020] [Indexed: 11/20/2022]
Abstract
Two-pore domain K+ channels (K2Ps) regulate the resting membrane potential in excitable cells and determine ease of depolarization. Gain-of-function (gf) mutations in one of these channels (unc-58) in C. elegans switch it to a Na+ conductance channel and cause tremors, paralysis and other defects. We hypothesized that it should be possible to identify drugs that corrected these defects in unc-58(gf) mutant animals by blocking or modulating the over-active channels. We examined dispersal of animals on food because the absence of effective forward locomotion is the most obvious defect. In addition, we quantified egg release over 24 h. Starting with a known inhibitor of mammalian K2Ps and directed structure-based screening, we evaluated numerous drugs in these assays. Loratadine, which inhibits human KCNK18, significantly improved movement as did methiothepin. We confirmed that endosulfan, a GABA-A receptor antagonist, corrected locomotion in the unc-58(gf) strains. Based on structural similarities to other hits, we found that clozapine, loxapine and amoxapine potently suppressed abnormal phenotypes. Curiously, nimodipine, a Ca++-channel blocker, dramatically improved movement and egg laying in unc-58(e665), but not unc-58(n495) animals. Molecular modeling provided initial insights into a possible basis for this difference based on the location of the e665 and n495 mutations. This research may lead to identification of novel K2P modulators and potential leads for drug discovery.
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Chronic alcohol disrupts hypothalamic responses to stress by modifying CRF and NMDA receptor function. Neuropharmacology 2020; 167:107991. [PMID: 32059962 DOI: 10.1016/j.neuropharm.2020.107991] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 01/07/2020] [Accepted: 02/05/2020] [Indexed: 01/23/2023]
Abstract
The chronic inability of alcoholics to effectively cope with relapse-inducing stressors has been linked to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and corticotropin-releasing factor (CRF) signaling. However, the cellular mechanisms responsible for this dysregulation are yet to be identified. After exposure of male Sprague Dawley rats to chronic intermittent ethanol (CIE; 5-6 g/kg orally for 35 doses over 50 days) or water, followed by 40-60 days of protracted withdrawal, we investigated CIE effects on glutamatergic synaptic transmission, stress-induced plasticity, CRF- and ethanol-induced NMDAR inhibition using electrophysiological recordings in parvocellular neurosecretory cells (PNCs) of the paraventricular nucleus. We also assessed CIE effects on hypothalamic mRNA expression of CRF-related genes using real-time polymerase chain reaction, and on HPA axis function by measuring stress-induced increases in plasma adrenocorticotropic hormone, corticosterone, and self-grooming. In control rats, ethanol-mediated inhibition of NMDARs was prevented by CRF1 receptor (CRFR1) blockade with antalarmin, while CRF/CRFR1-mediated NMDAR blockade was prevented by intracellularly-applied inhibitor of phosphatases PP1/PP2A, okadaic acid, but not the selective striatal-enriched tyrosine protein phosphatase inhibitor, TC-2153. CIE exposure increased GluN2B subunit-dependent NMDAR function of PNCs. This was associated with the loss of both ethanol- and CRF-mediated NMDAR inhibition, and loss of stress-induced short-term potentiation of glutamatergic synaptic inputs, which could be reversed by intracellular blockade of NMDARs with MK801. CIE exposure also blunted the hormonal and self-grooming behavioral responses to repeated restraint stress. These findings suggest a cellular mechanism whereby chronic alcohol dysregulates the hormonal and behavioral responses to repetitive stressors by increasing NMDAR function and decreasing CRFR1 function.
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Bandiera S, Almeida FB, Hansen AW, Pulcinelli RR, Caletti G, de Paula LF, Nin MS, Fontella FU, Almeida RF, Tannhauser Barros HM, Gomez R. Combined use of alcohol and cigarette increases locomotion and glutamate levels in the cerebrospinal fluid without changes on GABAA or NMDA receptor subunit mRNA expression in the hippocampus of rats. Behav Brain Res 2020; 380:112444. [DOI: 10.1016/j.bbr.2019.112444] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 11/18/2019] [Accepted: 12/18/2019] [Indexed: 10/25/2022]
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Wu M, Katti P, Zhao Y, Peoples RW. Positions in the N-methyl-D-aspartate Receptor GluN2C Subunit M3 and M4 Domains Regulate Alcohol Sensitivity and Receptor Kinetics. Alcohol Clin Exp Res 2019; 43:1180-1190. [PMID: 30964201 PMCID: PMC6551259 DOI: 10.1111/acer.14042] [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: 12/20/2018] [Accepted: 04/02/2019] [Indexed: 11/30/2022]
Abstract
BACKGROUND Alcohol alters synaptic transmission in the brain. The N-methyl-D-aspartate (NMDA) receptor (NMDAR), a subtype of glutamate-gated ion channel, is an important synaptic target of alcohol in the brain. We and others have previously identified 4 alcohol-sensitive positions in the third and fourth membrane-associated (M) domains, designated M31-2 and M41-2 , of the GluN1, GluN2A, and GluN2B NMDAR subunits. In the present study, we tested whether the corresponding positions in the GluN2C subunit also regulate alcohol sensitivity and ion channel gating. METHODS We performed alanine- and tryptophan-scanning mutagenesis in the GluN2C subunit followed by expression in HEK 293 cells and electrophysiological patch-clamp recording. RESULTS Alanine substitution at the M31 (F634) and M41-2 (M821 and M823) positions did not alter ethanol (EtOH) sensitivity, whereas substitution of alanine at the M32 position (F635) yielded nonfunctional receptors. Tryptophan substitution at the M31-2 positions did not change EtOH sensitivity, whereas tryptophan substitution at the M41 position increased, and at the M42 position decreased, EtOH sensitivity. The increased EtOH sensitivity of the tryptophan mutant at M41 is in marked contrast to previous results observed in the GluN2A and GluN2B subunits. In addition, this mutant exhibited increased desensitization, but to a much lesser extent compared to the corresponding mutations in GluN2A and GluN2B. A series of mutations at M41 altered EtOH sensitivity, glutamate potency, and desensitization. Seven amino acid substitutions (of 15 tested) at this position yielded nonfunctional receptors. Among the remaining mutants at M41 , EtOH sensitivity was not significantly correlated with hydrophobicity, molecular volume, or polarity of the substituent, or with glutamate EC50 values, but was correlated with maximal steady-state-to-peak current ratio, a measure of desensitization. CONCLUSIONS The identity and characteristics of alcohol-sensitive positions in the GluN2C subunit differ from those previously reported for GluN2A and GluN2B subunits, despite the high homology among these subunits.
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Affiliation(s)
- Man Wu
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201-1881
- Present address: Department of Neuroscience, University of Pittsburgh, 461 Crawford Hall, Pittsburgh, PA 15260
| | | | - Yulin Zhao
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201-1881
- Present address: Laboratory of Membrane Excitability and Disease, Mount Sinai School of Medicine, 1425 Madison Avenue, ICAHN 9-26, 28, New York, NY 10029
| | - Robert W. Peoples
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201-1881
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Noori HR, Mücksch C, Urbassek HM. Ethanol-induced conformational fluctuations of NMDA receptors. Mol Phys 2019. [DOI: 10.1080/00268976.2018.1504135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Hamid R. Noori
- Neuronal Convergence Group, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- Courant Institute for Mathematical Sciences, New York University, New York, NY, USA
- Physics Department and Research Center OPTIMAS, University of Kaiserslautern, Kaiserslautern, Germany
| | - Christian Mücksch
- Physics Department and Research Center OPTIMAS, University of Kaiserslautern, Kaiserslautern, Germany
| | - Herbert M. Urbassek
- Physics Department and Research Center OPTIMAS, University of Kaiserslautern, Kaiserslautern, Germany
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Wolfe SA, Farris SP, Mayfield JE, Heaney CF, Erickson EK, Harris RA, Mayfield RD, Raab-Graham KF. Ethanol and a rapid-acting antidepressant produce overlapping changes in exon expression in the synaptic transcriptome. Neuropharmacology 2018; 146:289-299. [PMID: 30419244 DOI: 10.1016/j.neuropharm.2018.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 10/03/2018] [Accepted: 11/07/2018] [Indexed: 01/02/2023]
Abstract
Alcohol use disorder (AUD) and major depressive disorder (MDD) are prevalent, debilitating, and highly comorbid disorders. The molecular changes that underlie their comorbidity are beginning to emerge. For example, recent evidence showed that acute ethanol exposure produces rapid antidepressant-like biochemical and behavioral responses. Both ethanol and fast-acting antidepressants block N-methyl-D-aspartate receptor (NMDAR) activity, leading to synaptic changes and long-lasting antidepressant-like behavioral effects. We used RNA sequencing to analyze changes in the synaptic transcriptome after acute treatment with ethanol or the NMDAR antagonist, Ro 25-6981. Ethanol and Ro 25-6981 induced differential, independent changes in gene expression. In contrast with gene-level expression, ethanol and Ro 25-6981 produced overlapping changes in exons, as measured by analysis of differentially expressed exons (DEEs). A prominent overlap in genes with DEEs indicated that changes in exon usage were important for both ethanol and Ro 25-6981 action. Structural modeling provided evidence that ethanol-induced exon expression in the NMDAR1 amino-terminal domain could induce conformational changes and thus alter NMDAR function. These findings suggest that the rapid antidepressant effects of ethanol and NMDAR antagonists reported previously may depend on synaptic exon usage rather than gene expression.
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Affiliation(s)
- Sarah A Wolfe
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, 92037, United States
| | - Sean P Farris
- Waggoner Center for Alcohol and Addiction Research, Department of Neuroscience, University of Texas at Austin, 2500 Speedway, Austin, TX, 78712, United States
| | - Joshua E Mayfield
- Department of Molecular Biosciences, University of Texas at Austin, 2500 Speedway, Austin, TX, 78712, United States
| | - Chelcie F Heaney
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC, 27157-1083, United States
| | - Emma K Erickson
- Waggoner Center for Alcohol and Addiction Research, Department of Neuroscience, University of Texas at Austin, 2500 Speedway, Austin, TX, 78712, United States
| | - R Adron Harris
- Waggoner Center for Alcohol and Addiction Research, Department of Neuroscience, University of Texas at Austin, 2500 Speedway, Austin, TX, 78712, United States
| | - R Dayne Mayfield
- Waggoner Center for Alcohol and Addiction Research, Department of Neuroscience, University of Texas at Austin, 2500 Speedway, Austin, TX, 78712, United States
| | - Kimberly F Raab-Graham
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC, 27157-1083, United States.
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Chen J, Ma Y, Fan R, Yang Z, Li MD. Implication of Genes for the N-Methyl-D-Aspartate (NMDA) Receptor in Substance Addictions. Mol Neurobiol 2018; 55:7567-7578. [PMID: 29429049 DOI: 10.1007/s12035-018-0877-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 01/07/2018] [Indexed: 12/17/2022]
Abstract
Drug dependence is a chronic brain disease with harmful consequences for both individual users and society. Glutamate is a primary excitatory neurotransmitter in the brain, and both in vivo and in vitro experiments have implicated N-methyl-D-aspartate (NMDA) receptor, a glutamate receptor, as an element in various types of addiction. Recent findings from genetics-based approaches such as genome-wide linkage, candidate gene association, genome-wide association (GWA), and next-generation sequencing have demonstrated the significant association of NMDA receptor subunit genes such as GluN3A, GluN2B, and GluN2A with various addiction-related phenotypes. Of these genes, GluN3A has been the most studied, and it has been revealed to play crucial roles in the etiology of addictions. In this communication, we provide an updated view of the genetic effects of NMDA receptor subunit genes and their functions in the etiology of addictions based on the findings from investigation of both common and rare variants as well as SNP-SNP interactions. To better understand the molecular mechanisms underlying addiction-related behaviors and to promote the development of specific medicines for the prevention and treatment of addictions, current efforts aim not only to identify more causal variants in NMDA receptor subunits by using large independent samples but also to reveal the molecular functions of these variants in addictions.
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Affiliation(s)
- Jiali Chen
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China
| | - Yunlong Ma
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China
| | - Rongli Fan
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhongli Yang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China.
| | - Ming D Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China. .,Research Center for Air Pollution and Health, Zhejiang University, Hangzhou, China. .,Institute of NeuroImmune Pharmacology, Seton Hall University, South Orange, NJ, USA.
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13
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Naassila M, Pierrefiche O. GluN2B Subunit of the NMDA Receptor: The Keystone of the Effects of Alcohol During Neurodevelopment. Neurochem Res 2018; 44:78-88. [DOI: 10.1007/s11064-017-2462-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/18/2017] [Accepted: 12/26/2017] [Indexed: 12/18/2022]
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14
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Roberto M, Varodayan FP. Synaptic targets: Chronic alcohol actions. Neuropharmacology 2017; 122:85-99. [PMID: 28108359 DOI: 10.1016/j.neuropharm.2017.01.013] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 12/23/2016] [Accepted: 01/14/2017] [Indexed: 01/02/2023]
Abstract
Alcohol acts on numerous cellular and molecular targets to regulate neuronal communication within the brain. Chronic alcohol exposure and acute withdrawal generate prominent neuroadaptations at synapses, including compensatory effects on the expression, localization and function of synaptic proteins, channels and receptors. The present article reviews the literature describing the synaptic effects of chronic alcohol exposure and their relevance for synaptic transmission in the central nervous system. This review is not meant to be comprehensive, but rather to highlight the effects that have been observed most consistently and that are thought to contribute to the development of alcohol dependence and the negative aspects of withdrawal. Specifically, we will focus on the major excitatory and inhibitory neurotransmitters in the brain, glutamate and GABA, respectively, and how their neuroadaptations after chronic alcohol exposure contributes to alcohol reinforcement, dependence and withdrawal. This article is part of the Special Issue entitled "Alcoholism".
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15
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Ren H, Zhao Y, Wu M, Dwyer DS, Peoples RW. Two adjacent phenylalanines in the NMDA receptor GluN2A subunit M3 domain interactively regulate alcohol sensitivity and ion channel gating. Neuropharmacology 2016; 114:20-33. [PMID: 27876530 DOI: 10.1016/j.neuropharm.2016.11.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 11/11/2016] [Accepted: 11/16/2016] [Indexed: 10/20/2022]
Abstract
The N-methyl-d-aspartate (NMDA) receptor is a key target of ethanol action in the central nervous system. Alcohol inhibition of NMDA receptor function involves small clusters of residues in the third and fourth membrane-associated (M) domains. Previous results from this laboratory have shown that two adjacent positions in the M3 domain, F636 and F637, can powerfully regulate alcohol sensitivity and ion channel gating. In this study, we report that these positions interact with one another in the regulation of both NMDA receptor gating and alcohol action. Using dual mutant cycle analysis, we detected interactions among various substitution mutants at these positions with respect to regulation of glutamate EC50, steady-state to peak current ratios (Iss:Ip), mean open time, and ethanol IC50. This interaction apparently involves a balancing of forces on the M3 helix, such that the disruption of function due to a substitution at one position can be reversed by a similar substitution at the other position. For example, tryptophan substitution at F636 or F637 increased or decreased channel mean open time, respectively, but tryptophan substitution at both positions did not alter open time. Interestingly, the effects of a number of mutations on receptor kinetics and ethanol sensitivity appeared to depend upon subtle structural differences, such as those between the isomeric amino acids leucine and isoleucine, as they could not be explained on the basis of sidechain molecular volume or hydrophilicity.
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Affiliation(s)
- Hong Ren
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | - Yulin Zhao
- Laboratory of Membrane Excitability and Disease Mount Sinai School of Medicine, 1425 Madison Avenue, ICAHN 9-26, 28, New York, NY 10029, United States.
| | - Man Wu
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States.
| | - Donard S Dwyer
- Department of Psychiatry, Louisiana State University Health Sciences Center, Shreveport, LA, United States.
| | - Robert W Peoples
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201-1881, United States.
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16
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Smothers CT, Woodward JJ. Differential effects of TM4 tryptophan mutations on inhibition of N-methyl-d-aspartate receptors by ethanol and toluene. Alcohol 2016; 56:15-19. [PMID: 27814790 DOI: 10.1016/j.alcohol.2016.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 09/23/2016] [Accepted: 10/01/2016] [Indexed: 10/20/2022]
Abstract
The voluntary use and abuse of alcohol and inhalants is a recognized health problem throughout the world. Previous studies have shown that these agents affect brain function in a variety of ways including direct inhibition of key ion channels that regulate neuronal excitability. Among these, the N-methyl-d-aspartate (NMDA) receptor is particularly important given its key role in glutamatergic synaptic transmission, neuronal plasticity and learning and memory. Previous studies from this laboratory and others have identified key residues within transmembrane (TM) domains of the NMDA receptor that appear to regulate its sensitivity to alcohol and anesthetics. In this study, we extend these findings and examine the role of a TM4 residue in modulating sensitivity of recombinant NMDA receptors to ethanol and toluene. HEK293 cells were transfected with GluN1-1a and either wild-type or tryptophan-substituted GluN2(A-D) subunits and whole-cell currents were recorded using patch-clamp electrophysiology in the absence or presence of ethanol or toluene. Both ethanol (100 mM) and toluene (1 or 3 mM) reversibly inhibited glutamate-activated currents from wild-type NMDARs with GluN2B containing receptors showing heightened sensitivity to either agent. Substitution of tryptophan (W) at positions 825, 826, 823 or 850 in the TM4 domain of GluN2A, GluN2B, GluN2C or GluN2D subunits; respectively, significantly reduced the degree of inhibition by ethanol. In contrast, toluene inhibition of glutamate-activated currents in cells expressing the TM4-W mutants was not different from that of the wild-type controls. These data suggest that despite similarities in their action on NMDARs, ethanol and toluene may act at different sites to reduce ion flux through NMDA receptors.
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17
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Abstract
Excellent reviews on central N-methyl-D-aspartate receptor (NMDAR) signaling and function in cardiovascular regulating neuronal pools have been reported. However, much less attention has been given to NMDAR function in peripheral tissues, particularly the heart and vasculature, although a very recent review discusses such function in the kidney. In this short review, we discuss the NMDAR expression and complexity of its function in cardiovascular tissues. In conscious (contrary to anesthetized) rats, activation of the peripheral NMDAR triggers cardiovascular oxidative stress through the PI3K-ERK1/2-NO signaling pathway, which ultimately leads to elevation in blood pressure. Evidence also implicates Ca release, in the peripheral NMDAR-mediated pressor response. Despite evidence of circulating potent ligands (eg, D-aspartate and L-aspartate, L-homocysteic acid, and quinolinic acid) and also their coagonist (eg, glycine or D-serine), the physiological role of peripheral cardiovascular NMDAR remains elusive. Nonetheless, the cardiovascular relevance of the peripheral NMDAR might become apparent when its signaling is altered by drugs, such as alcohol, which interact with the NMDAR or its downstream signaling mechanisms.
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Affiliation(s)
- Marie A. McGee
- Oak Ridge Institute for Science and Education, Research Triangle Park, NC
| | - Abdel A. Abdel-Rahman
- Department of Pharmacology, Brody School of Medicine, East Carolina University, Greenville, NC 27834
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18
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Arout CA, Perrino AC, Ralevski E, Acampora G, Koretski J, Limoncelli D, Newcomb J, Petrakis IL. Effect of Intravenous Ethanol on Capsaicin-Induced Hyperalgesia in Human Subjects. Alcohol Clin Exp Res 2016; 40:1425-9. [PMID: 27218476 DOI: 10.1111/acer.13095] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 04/04/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND The objective of this study was to assess ethanol's (EtOH's) effects on capsaicin-induced hyperalgesia in healthy participants. Specifically, we investigated the change in area of capsaicin-induced hyperalgesia following 3 interventions: intravenous EtOH at 2 targeted breath alcohol concentrations (BrAC), or placebo. METHODS Eighteen participants participated in 3 test days in a randomized order. Each test day, participants received an intradermal capsaicin injection on the volar surface of the forearm, followed by either infusion of high concentration EtOH (targeted BrAC = 0.100 g/dl), low concentration EtOH (targeted BrAC = 0.040 g/dl), or placebo. The area of hyperalgesia was determined by von Frey technique at 2 time points, prior to EtOH infusion, and again when target BrAC was reached. The primary outcome was the percent change in the area of capsaicin-induced hyperalgesia. Additional outcome measures included the visual analogue scale of mood states (VAS), which was administered at each time point. RESULTS There was a marked 30% reduction in the area of capsaicin-induced hyperalgesia with infusion of a high concentration of EtOH (p < 0.05). Low concentration EtOH produced a 10% reduction in hyperalgesia area, although this finding did not reach significance. Further, participants reported significant feelings of euphoria and drowsiness at high concentrations of EtOH (p < 0.05), as measured by the VAS. CONCLUSIONS In a human model examining pain phenomena related to central sensitization, this study is the first to demonstrate that capsaicin-induced hyperalgesia is markedly attenuated by EtOH. The capsaicin experimental pain paradigm employed provides a novel approach to evaluate EtOH's effects on pain processing. The antihyperalgesic effects of EtOH observed have important clinical implications for the converging fields of substance abuse and pain medicine and may inform why patients with chronic pain often report alcohol use as a form of self-medication.
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Affiliation(s)
- Caroline A Arout
- Department of Psychiatry, Center for Translational Neuroscience of Alcoholism and VA Alcohol Research Center, Yale University School of Medicine, West Haven, Connecticut
| | - Albert C Perrino
- Department of Anesthesiology, VA Connecticut Healthcare System, Yale University School of Medicine, West Haven, Connecticut
| | - Elizabeth Ralevski
- Department of Psychiatry, Center for Translational Neuroscience of Alcoholism and VA Alcohol Research Center, Yale University School of Medicine, West Haven, Connecticut
| | - Gregory Acampora
- Department of Psychiatry, Massachusetts General Hospital, Harvard Center for Addiction Medicine, Boston, Massachusetts
| | - Julia Koretski
- Department of Psychiatry, Center for Translational Neuroscience of Alcoholism and VA Alcohol Research Center, Yale University School of Medicine, West Haven, Connecticut
| | - Diana Limoncelli
- Department of Psychiatry, Center for Translational Neuroscience of Alcoholism and VA Alcohol Research Center, Yale University School of Medicine, West Haven, Connecticut
| | - Jenelle Newcomb
- Department of Psychiatry, Center for Translational Neuroscience of Alcoholism and VA Alcohol Research Center, Yale University School of Medicine, West Haven, Connecticut
| | - Ismene L Petrakis
- Department of Psychiatry, Center for Translational Neuroscience of Alcoholism and VA Alcohol Research Center, Yale University School of Medicine, West Haven, Connecticut
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19
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Zhao Y, Ren H, Peoples RW. Intersubunit interactions at putative sites of ethanol action in the M3 and M4 domains of the NMDA receptor GluN1 and GluN2B subunits. Br J Pharmacol 2016; 173:1950-65. [PMID: 27010645 DOI: 10.1111/bph.13487] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 02/09/2016] [Accepted: 03/04/2016] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND AND PURPOSE The NMDA receptor is an important target of alcohol action in the brain. Recent studies in this laboratory have demonstrated that alcohol-sensitive positions in the intersubunit interfaces of the M3 and M4 domains of GluN1 and GluN2A subunits interact with respect to ethanol sensitivity and receptor kinetics and that alcohol-sensitive positions in the M domains of GluN2A and GluN2B subunits differ. In this study, we tested for interactions among alcohol-sensitive positions at the M domain intersubunit interfaces in GluN1/GluN2B NMDA receptors. EXPERIMENTAL APPROACH We used whole-cell patch-clamp recording in tsA201 cells expressing tryptophan substitution mutants at ethanol-sensitive positions in the GluN1 and GluN2B NMDA receptor subunits to test for interactions among positions. KEY RESULTS Six pairs of positions in GluN1/GluN2B significantly interacted to regulate ethanol inhibition: Gly(638) /Met(824) , Gly(638) /Leu(825) , Phe(639) /Leu(825) , Phe(639) /Gly(826) , Met(818) /Phe(637) and Val(820) /Phe(637) . Tryptophan substitution at Met(824) or Leu(825) in GluN2B did not alter ethanol sensitivity but interacted with positions in the GluN1 M3 domain to regulate ethanol action, whereas tryptophan substitution at Gly(638) , which is the cognate of an ethanol-sensitive position in GluN2A, did not alter ethanol sensitivity or interact with positions in GluN1. Two and three pairs of positions interacted to regulate glutamate steady-state and peak current EC50 , respectively, and one pair interacted with respect to macroscopic desensitization. CONCLUSIONS Despite highly-conserved M domain sequences and similar ethanol sensitivity in the GluN2A and GluN2B subunits, the manner in which these subunits interact with the GluN1 subunit to regulate ethanol sensitivity and receptor kinetics differs.
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Affiliation(s)
- Y Zhao
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - H Ren
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - R W Peoples
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
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20
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McClintick JN, McBride WJ, Bell RL, Ding ZM, Liu Y, Xuei X, Edenberg HJ. Gene Expression Changes in Glutamate and GABA-A Receptors, Neuropeptides, Ion Channels, and Cholesterol Synthesis in the Periaqueductal Gray Following Binge-Like Alcohol Drinking by Adolescent Alcohol-Preferring (P) Rats. Alcohol Clin Exp Res 2016; 40:955-68. [PMID: 27061086 DOI: 10.1111/acer.13056] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 02/28/2016] [Indexed: 12/31/2022]
Abstract
BACKGROUND Binge drinking of alcohol during adolescence is a serious public health concern with long-term consequences, including increased pain, fear, and anxiety. The periaqueductal gray (PAG) is involved in processing pain, fear, and anxiety. The effects of adolescent binge drinking on gene expression in this region have yet to be studied. METHODS Male adolescent alcohol-preferring (P) rats were exposed to repeated binge drinking (three 1-hour sessions/d during the dark/cycle, 5 days/wk for 3 weeks starting at 28 days of age; ethanol intakes of 2.5 to 3 g/kg/session). We used RNA sequencing to assess the effects of ethanol intake on gene expression. RESULTS Ethanol significantly altered the expression of 1,670 of the 12,123 detected genes: 877 (53%) decreased. In the glutamate system, 23 genes were found to be altered, including reduction in 7 of 10 genes for metabotropic and NMDA receptors. Subunit changes in the NMDA receptor may make it less sensitive to ethanol. Changes in GABAA genes would most likely increase the ability of the PAG to produce tonic inhibition. Five serotonin receptor genes, 6 acetylcholine receptor genes, and 4 glycine receptor genes showed decreased expression in the alcohol-drinking rats. Opioid genes (e.g., Oprk1, Oprm1) and genes for neuropeptides linked to anxiety and panic behaviors (e.g., Npy1r) had mostly decreased expression. Genes for 27 potassium, 10 sodium, and 5 calcium ion channels were found to be differentially expressed. Nine genes in the cholesterol synthesis pathway had decreased expression, including Hmgcr, encoding the rate-limiting enzyme. Genes involved in the production of myelin also had decreased expression. CONCLUSIONS The results demonstrate that binge alcohol drinking during adolescence produces developmental changes in the expression of key genes within the PAG; many of these changes point to increased susceptibility to pain, fear, and anxiety, which could contribute to excessive drinking to relieve these negative effects.
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Affiliation(s)
- Jeanette N McClintick
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana.,Center for Medical Genomics, Indiana University School of Medicine, Indianapolis, Indiana
| | - William J McBride
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, Indiana
| | - Richard L Bell
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, Indiana
| | - Zheng-Ming Ding
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, Indiana
| | - Yunlong Liu
- Department of Medical & Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana
| | - Xiaoling Xuei
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana.,Center for Medical Genomics, Indiana University School of Medicine, Indianapolis, Indiana
| | - Howard J Edenberg
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana.,Center for Medical Genomics, Indiana University School of Medicine, Indianapolis, Indiana.,Department of Medical & Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana
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Disruption of S2-M4 linker coupling reveals novel subunit-specific contributions to N-methyl-d-aspartate receptor function and ethanol sensitivity. Neuropharmacology 2015; 105:96-105. [PMID: 26577016 DOI: 10.1016/j.neuropharm.2015.11.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 11/03/2015] [Accepted: 11/06/2015] [Indexed: 01/12/2023]
Abstract
The N-methyl-d-aspartate (NMDA) receptor is a glutamatergic ion channel and is a known site of ethanol action. Evidence suggests that ethanol inhibits NMDA receptor activity by reducing channel open probability and mean open time potentially via interaction with specific residues within the transmembrane (M) domains 3 and 4 of GluN subunits. Recent models of NMDAR function demonstrate that extracellular residues near the M domains are key regulators of gating, suggesting that they may contribute to ethanol sensitivity. To test this, we substituted cysteines at key positions in GluN1 and GluN2 M3-S2 and S2-M4 regions previously shown to affect channel open probability and mean open time similar to ethanol treatment. Although crosslinking of these domains was predicted to restrict linker domain movement and occlude ethanol inhibition, only intra-GluN1 M1:M4 linker-crosslinked receptors showed a decrease in ethanol sensitivity. For the converse experiment, we expressed NMDARs with glycine substitutions in the S2-M4 domain of GluN subunits to enhance M4 flexibility and recorded currents in response to ethanol. Glycine substitution in the GluN1 S2-M4 region significantly decreased glutamate potency of GluN1(A804G)/GluN2A receptors, while GluN1(A804G)/GluN2B receptors exhibited no change in glutamate sensitivity. In contrast, GluN1/GluN2B(S811G) receptors showed a 10-fold increase in glutamate potency while GluN1/GluN2A(S810G) receptors showed no change. Surprisingly, while S2-M4 glycine substitutions modulated ethanol sensitivity, this was observed only in receptors that did not display a change in agonist potency. Overall, these results suggest that S2-M4 linkers strongly influence receptor function and modestly impact ethanol efficacy in a subunit- and receptor subtype-dependent manner.
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