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Patton MS, Sheats SH, Siclair AN, Mathur BN. Alcohol potentiates multiple GABAergic inputs to dorsal striatum fast-spiking interneurons. Neuropharmacology 2023; 232:109527. [PMID: 37011784 PMCID: PMC10122715 DOI: 10.1016/j.neuropharm.2023.109527] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 03/16/2023] [Accepted: 03/28/2023] [Indexed: 04/04/2023]
Abstract
Parvalbumin-expressing dorsal striatal fast-spiking interneurons, comprising ∼1% of the total dorsal striatal neuronal population, are necessary for the expression of compulsive-like ethanol consumption mice. Fast-spiking interneurons are driven to fire by glutamatergic inputs derived primarily from the cortex. However, these neurons also receive substantial GABAergic input from two sources: the globus pallidus and the reticular nucleus of the thalamus. How ethanol modulates inhibitory input onto fast-spiking neurons is unclear and, more broadly, alcohol effects on GABAergic synaptic transmission onto GABAergic interneurons are understudied. Examining this, we found that acute bath application of ethanol (50 mM) potentiated GABAergic transmission from both the globus pallidus and the reticular nucleus of the thalamus onto fast-spiking interneurons in mouse of both sexes. This ethanol-induced potentiation required postsynaptic calcium and was not accompanied by a sustained change in presynaptic GABA release probability. Examining whether this ethanol effect persisted following chronic intermittent ethanol exposure, we found attenuated acute-ethanol potentiation of GABAergic transmission from both the globus pallidus and the reticular nucleus of the thalamus onto striatal fast-spiking interneurons. These data underscore the impact of ethanol on GABAergic signaling in the dorsal striatum and support the notion that ethanol may disinhibit the dorsolateral striatum.
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Affiliation(s)
- Michael S Patton
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Samuel H Sheats
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Allison N Siclair
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Brian N Mathur
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
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2
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Sánchez-Zavaleta R, Ávalos-Fuentes JA, González-Hernández AV, Recillas-Morales S, Paz-Bermúdez FJ, Leyva-Gómez G, Cortés H, Florán B. Presynaptic nigral GPR55 receptors stimulate [ 3 H]-GABA release through [ 3 H]-cAMP production and PKA activation and promote motor behavior. Synapse 2022; 76:e22246. [PMID: 35831708 DOI: 10.1002/syn.22246] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 05/16/2022] [Accepted: 07/05/2022] [Indexed: 11/09/2022]
Abstract
Striatal medium-sized spiny neurons express mRNA and protein of GPR55 receptors that stimulate neurotransmitter release; thus, GPR55 could be sent to nigral striatal projections, where it might modulate GABA release and motor behavior. Here we study the presence of GPR55 receptors at striato-nigral terminals, their modulation of GABA release, their signaling pathway, and their effect on motor activity. By double immunohistochemistry, we found the colocation of GPR55 protein and substance P in the dorsal striatum. In slices of the rat substantia nigra, the GPR55 agonists LPI and O-1602 stimulated [3 H]-GABA release induced by high K+ depolarization in a dose-dependent manner. The antagonists CID16020046 and cannabidiol prevented agonist stimulation in a dose-dependent way. The effect of GPR55 on nigral [3 H]-GABA release was prevented by lesion of the striatum with kainic acid, which was accompanied by a decrement of GPR55 protein in nigral synaptosomes, indicating the presynaptic location of receptors. The depletion of internal Ca2+ stores with thapsigargin did not prevent the effect of LPI on [3 H]-GABA release, but the remotion or chelation of external calcium did. Blockade of Gi, Gs, PLC, PKC, or dopamine D1 receptor signaling proteins did not prevent the effect of GPR55 on release. However, the activation of GPR55 stimulated [3 H]-cAMP accumulation and PKA activity. Intranigral unilateral injection of LPI induces contralateral turning. This turning was prevented by CID16020046, cannabidiol, and bicuculline but not by SCH 23390. Our data indicate that presynaptic GPR55 receptors stimulate [3 H]-GABA release at striato-nigral terminals through [3 H]-cAMP production and stimulate motor behavior. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Rodolfo Sánchez-Zavaleta
- Departamento de Fisiología, Biofísica y Neurociencias. Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México
| | - José Arturo Ávalos-Fuentes
- Departamento de Fisiología, Biofísica y Neurociencias. Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México
| | - Antonio Valentín González-Hernández
- Departamento de Fisiología, Biofísica y Neurociencias. Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México
| | | | - Francisco Javier Paz-Bermúdez
- Departamento de Fisiología, Biofísica y Neurociencias. Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México
| | - Gerardo Leyva-Gómez
- Departamento de Farmacia, Facultad de Química, Universidad Nacional Autónoma de México, Mexico
| | - Hernán Cortés
- Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra, Ciudad de México, México
| | - Benjamín Florán
- Departamento de Fisiología, Biofísica y Neurociencias. Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México
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Abstract
PURPOSE A growing body of evidence has implicated the endocannabinoid (eCB) system in the acute, chronic, and withdrawal effects of alcohol/ethanol on synaptic function. These eCB-mediated synaptic effects may contribute to the development of alcohol use disorder (AUD). Alcohol exposure causes neurobiological alterations similar to those elicited by chronic cannabinoid (CB) exposure. Like alcohol, cannabinoids alter many central processes, such as cognition, locomotion, synaptic transmission, and neurotransmitter release. There is a strong need to elucidate the effects of ethanol on the eCB system in different brain regions to understand the role of eCB signaling in AUD. SEARCH METHODS For the scope of this review, preclinical studies were identified through queries of the PubMed database. SEARCH RESULTS This search yielded 459 articles. Clinical studies and papers irrelevant to the topic of this review were excluded. DISCUSSION AND CONCLUSIONS The endocannabinoid system includes, but is not limited to, cannabinoid receptors 1 (CB1), among the most abundantly expressed neuronal receptors in the brain; cannabinoid receptors 2 (CB2); and endogenously formed CB1 ligands, including arachidonoylethanolamide (AEA; anandamide), and 2-arachidonoylglycerol (2-AG). The development of specific CB1 agonists, such as WIN 55,212-2 (WIN), and antagonists, such as SR 141716A (rimonabant), provide powerful pharmacological tools for eCB research. Alcohol exposure has brain region-specific effects on the eCB system, including altering the synthesis of endocannabinoids (e.g., AEA, 2-AG), the synthesis of their precursors, and the density and coupling efficacy of CB1. These alcohol-induced alterations of the eCB system have subsequent effects on synaptic function including neuronal excitability and postsynaptic conductance. This review will provide a comprehensive evaluation of the current literature on the synaptic interactions of alcohol exposure and eCB signaling systems, with an emphasis on molecular and physiological synaptic effects of alcohol on the eCB system. A limited volume of studies has focused on the underlying interactions of alcohol and the eCB system at the synaptic level in the brain. Thus, the data on synaptic interactions are sparse, and future research addressing these interactions is much needed.
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Affiliation(s)
- Sarah A Wolfe
- Department of Molecular Medicine, Scripps Research Institute, La Jolla, California
| | - Valentina Vozella
- Department of Molecular Medicine, Scripps Research Institute, La Jolla, California
| | - Marisa Roberto
- Department of Molecular Medicine, Scripps Research Institute, La Jolla, California
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Gakare SG, Varghese SS, Patni PP, Wagh SA, Ugale RR. Prevention of glutamate excitotoxicity in lateral habenula alleviates ethanol withdrawal-induced somatic and behavioral effects in ethanol dependent mice. Behav Brain Res 2022; 416:113557. [PMID: 34453973 DOI: 10.1016/j.bbr.2021.113557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 08/23/2021] [Accepted: 08/23/2021] [Indexed: 12/22/2022]
Abstract
Ethanol withdrawal commonly leads to anxiety-related disorder, a central factor toward negative reinforcement leading to relapse. The lateral habenula (LHb), an epithalamic nucleus, has emerged to be critical for both reward and aversion processing. Recent studies have also implicated the hyperactivity of LHb, adding to the emergence of negative emotional states during withdrawal from addictive drugs. Herein, we have studied the effects of glutamate transporter inhibitor (PDC), GluN2B-containing NMDAR antagonist (Ro25-6981), and intracellular calcium chelator (BAPTA-AM) injection in LHb on ethanol withdrawal symptoms. We found that ethanol 4 g/kg 20 % w/v intragastric (i.g.) for 10 days followed by 24 h of withdrawal showed a significant increase in somatic signs characterized by vocalization, shaking, and scratching. It also increased locomotor activity and anxiety-like behavior, collectively showing expression of ethanol withdrawal symptoms. The intra-LHb administration of PDC (0.5 ng) worsened the effect of ethanol withdrawal, whereas Ro25-6981 (2 and 4 ng) and BAPTA-AM (6.5 and 13 ng) significantly reversed ethanol withdrawal-induced behavior evident by a decrease in somatic signs, locomotor activity, and anxiety-like behavior. Further, pretreatment of Ro25-6981 and BAPTA-AM reduced the neuronal loss, whereas PDC increased it compared to the vehicle-treated group, as evidenced by NeuN staining. Altogether, our results suggest that increased glutamate, GluN2B activation, and likely calcium increase indicative of glutamate excitotoxicity-induced neuronal loss in LHb possibly endorse the emergence of ethanol withdrawal symptoms, while their inhibition might help in alleviating the ethanol withdrawal symptoms.
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Affiliation(s)
- Sukanya G Gakare
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440 033, India
| | - Shejin S Varghese
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440 033, India
| | - Paras P Patni
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440 033, India
| | - Samruddhi A Wagh
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440 033, India
| | - Rajesh R Ugale
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440 033, India.
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Li Q, Klein RC, Moore SD. Multiple sources of internal calcium stores mediate ethanol-induced presynaptic inhibitory GABA release in the central nucleus of the amygdala in mice. Psychopharmacology (Berl) 2020; 237:3303-3314. [PMID: 32705289 PMCID: PMC7644111 DOI: 10.1007/s00213-020-05613-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 07/17/2020] [Indexed: 11/27/2022]
Abstract
RATIONALE Ethanol can enhance GABA release in various brain regions via presynaptic mechanisms. However, the presynaptic action of ethanol on inhibitory GABA release is still not well understood. OBJECTIVES Since calcium is required for neurotransmitter release from presynaptic terminals, the purpose of this study was to investigate the role of both internal and external calcium signaling in ethanol-induced enhancement of GABA release within the central amygdala nucleus (CeA) in acute brain slice preparations. METHODS Whole-cell patch clamp electrophysiology was used to record miniature GABAA receptor-mediated inhibitory postsynaptic currents (mIPSCs) from CeA neurons. Ethanol-enhanced mIPSCs were recorded in the presence of antagonists that regulate internal and external calcium-mediated processes. RESULTS Bath-applied ethanol dose-dependently increased the mean frequency of mIPSCs without altering mIPSC amplitude. Ethanol-induced increases in mIPSC frequency were antagonized by dantrolene, 2-APB, and the endoplasmic reticulum calcium pump (SERCA) antagonists thapsigargin and cyclopiazonic acid (CPA). Blocking calcium release from mitochondria or via exocytosis with ruthenium red also attenuated mIPSCs while frequency was not altered in the presence of a non-selective calcium channel blocker cadmium. The L-type calcium blocker nifedipine, but not its analogue nimodipine, blocked ethanol-induced enhancement in CeA neurons. CONCLUSIONS These results demonstrate ethanol-induced presynaptic release of GABA is mediated by internal calcium stores and by disrupting neurotransmitter exocytosis within the CeA, a critical brain area involved in drugs of abuse and alcohol addiction.
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Affiliation(s)
- Qiang Li
- Addictions Division, Department of Psychiatry, Duke University Medical Center, Durham, NC, 27705, USA
- VISN 6 MIRECC, Durham VA Medical Center, Durham, NC, 27705, USA
| | - Rebecca C Klein
- Addictions Division, Department of Psychiatry, Duke University Medical Center, Durham, NC, 27705, USA
- VISN 6 MIRECC, Durham VA Medical Center, Durham, NC, 27705, USA
| | - Scott D Moore
- Addictions Division, Department of Psychiatry, Duke University Medical Center, Durham, NC, 27705, USA.
- VISN 6 MIRECC, Durham VA Medical Center, Durham, NC, 27705, USA.
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Scarnati MS, Boreland AJ, Joel M, Hart RP, Pang ZP. Differential sensitivity of human neurons carrying μ opioid receptor (MOR) N40D variants in response to ethanol. Alcohol 2020; 87:97-109. [PMID: 32561311 PMCID: PMC7958146 DOI: 10.1016/j.alcohol.2020.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 05/15/2020] [Accepted: 05/25/2020] [Indexed: 12/11/2022]
Abstract
The acute and chronic effects of alcohol on the brain and behavior are linked to alterations in inhibitory synaptic transmission. Alcohol's most consistent effect at the synaptic level is probably a facilitation of γ-aminobutyric acid (GABA) release, as seen from several rodent studies. The impact of alcohol on GABAergic neurotransmission in human neurons is unknown, due to a lack of a suitable experimental model. Human neurons can also be used to model effects of genetic variants linked with alcohol use disorders (AUDs). The A118G single nucleotide polymorphism (SNP rs1799971) of the OPRM1 gene encoding the N40D (D40 minor allele) mu-opioid receptor (MOR) variant has been linked with individuals who have an AUD. However, while N40D is clearly associated with other drugs of abuse, involvement with AUDs is controversial. In this study, we employed Ascl1-and Dlx2-induced inhibitory neuronal cells (AD-iNs) generated from human iPS cell lines carrying N40D variants, and investigated the impact of ethanol acutely and chronically on GABAergic synaptic transmission. We found that N40 AD-iNs display a stronger facilitation (versus D40) of spontaneous and miniature inhibitory postsynaptic current frequency in response to acute ethanol application. Quantitative immunocytochemistry of Synapsin 1+ synaptic puncta revealed a similar synapse number between N40 and D40 iNs, suggesting an ethanol modulation of presynaptic GABA release without affecting synapse density. Interestingly, D40 iNs exposed to chronic intermittent ethanol application caused a significant increase in mIPSC frequency, with only a modest enhancement observed in N40 iNs. These data suggest that the MOR genotype may confer differential sensitivity to synaptic output, which depends on ethanol exposure time and concentration for AD-iNs and may help explain alcohol dependence in individuals who carry the MOR D40 SNPs. Furthermore, this study supports the use of human neuronal cells carrying risk-associated genetic variants linked to disease, as in vitro models to assay the synaptic actions of alcohol on human neuronal cells.
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Affiliation(s)
- Matthew S Scarnati
- Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA; Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Andrew J Boreland
- Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA; Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Marisa Joel
- Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA; Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, 08854, USA
| | - Ronald P Hart
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, 08854, USA; Human Genetics Institute of New Jersey, Piscataway, NJ, 08854, USA
| | - Zhiping P Pang
- Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA; Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, 08901, USA.
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7
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Pignataro L. Alcohol protects the CNS by activating HSF1 and inducing the heat shock proteins. Neurosci Lett 2019; 713:134507. [PMID: 31541723 DOI: 10.1016/j.neulet.2019.134507] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 09/13/2019] [Accepted: 09/18/2019] [Indexed: 12/15/2022]
Abstract
Although alcohol abuse and dependence have profound negative health consequences, emerging evidence suggests that exposure to low/moderate concentrations of ethanol protects multiple organs and systems. In the CNS, moderate drinking decreases the risk of dementia and Alzheimer's disease. This neuroprotection correlates with an increased expression of the heat shock proteins (HSPs). Multiple epidemiological studies revealed an inverse association between ethanol intoxication and traumatic brain injury mortality. In this case, ethanol-induced HSPs limit the inflammatory immune response diminishing cell death and improving the neurobehavioural outcome. Ethanol also protects the brain against ischemic injuries via the HSPs. In our laboratory, we demonstrated that ethanol increased the expression of several HSP genes in neurons and astrocytes by activating the transcription factor, heat shock factor 1 (HSF1). HSF1 induces HSPs that target misfolded proteins for refolding or degradation, increasing the survival chances of the cells. These data indicate that ethanol neuroprotection is mediated by the activation HSF1 and the induction of HSPs.
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Affiliation(s)
- Leonardo Pignataro
- Columbia University, Department of Anesthesiology, 622 West 168th St., PH 511, New York, NY, 10032, USA; College of Staten Island - City University of New York, 2800 Victory Blvd., Building 1A - 101, Staten Island, NY, 10314, USA.
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8
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Abstract
Ethanol produces intoxication through actions on numerous molecular and cellular targets. Adaptations involving these and other targets contribute to chronic drug actions that underlie continued and problematic drinking. Among the mechanisms involved in these ethanol actions are alterations in presynaptic mechanisms of synaptic transmission, including presynaptic protein function and excitation-secretion coupling. At synapses in the central nervous system (CNS), excitation-secretion coupling involves ion channel activation followed by vesicle fusion and neurotransmitter release. These mechanisms are altered by presynaptic neurotransmitter receptors and prominently by G protein-coupled receptors (GPCRs). Studies over the last 20-25 years have revealed that acute ethanol exposure alters neurotransmitter secretion, with especially robust effects on synapses that use the neurotransmitter gamma-aminobutyric acid (GABA). Intracellular signaling pathways involving second messengers such as cyclic AMP and calcium are implicated in these acute ethanol actions. Ethanol-induced release of neuropeptides and small molecule neurotransmitters that act on presynaptic GPCRs also contribute to presynaptic potentiation at synapses in the amygdala and hippocampus and inhibition of GABA release in the striatum. Prolonged exposure to ethanol alters neurotransmitter release at many CNS GABAergic and glutamatergic synapses, and changes in GPCR function are implicated in many of these neuroadaptations. These presynaptic neuroadaptations appear to involve compensation for acute drug effects at some synapses, but "allostatic" effects that result in long-term resetting of synaptic efficacy occur at others. Current investigations are determining how presynaptic neuroadaptations contribute to behavioral changes at different stages of alcohol drinking, with increasing focus on circuit adaptations underlying these behaviors. This chapter will discuss the acute and chronic presynaptic effects of ethanol in the CNS, as well as some of the consequences of these effects in amygdala and corticostriatal circuits that are related to excessive seeking/drinking and ethanol abuse.
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Affiliation(s)
- David M Lovinger
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA.
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Endocannabinoid System and Alcohol Abuse Disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1162:89-127. [PMID: 31332736 DOI: 10.1007/978-3-030-21737-2_6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Δ9-tetrahydrocannabinol (Δ9-THC), the primary active component in Cannabis sativa preparations such as hashish and marijuana, signals by binding to cell surface receptors. Two types of receptors have been cloned and characterized as cannabinoid (CB) receptors. CB1 receptors (CB1R) are ubiquitously present in the central nervous system (CNS) and are present in both inhibitory interneurons and excitatory neurons at the presynaptic terminal. CB2 receptors (CB2R) are demonstrated in microglial cells, astrocytes, and several neuron subpopulations and are present in both pre- and postsynaptic terminals. The majority of studies on these receptors have been conducted in the past two and half decades after the identification of the molecular constituents of the endocannabinoid (eCB) system that started with the characterization of CB1R. Subsequently, the seminal discovery was made, which suggested that alcohol (ethanol) alters the eCB system, thus establishing the contribution of the eCB system in the motivation to consume ethanol. Several preclinical studies have provided evidence that CB1R significantly contributes to the motivational and reinforcing properties of ethanol and that the chronic consumption of ethanol alters eCB transmitters and CB1R expression in the brain nuclei associated with addiction pathways. Additionally, recent seminal studies have further established the role of the eCB system in the development of ethanol-induced developmental disorders, such as fetal alcohol spectrum disorders (FASD). These results are augmented by in vitro and ex vivo studies, showing that acute and chronic treatment with ethanol produces physiologically relevant alterations in the function of the eCB system during development and in the adult stage. This chapter provides a current and comprehensive review of the literature concerning the role of the eCB system in alcohol abuse disorders (AUD).
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10
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Jijón-Lorenzo R, Caballero-Florán IH, Recillas-Morales S, Cortés H, Avalos-Fuentes JA, Paz-Bermúdez FJ, Erlij D, Florán B. Presynaptic Dopamine D2 Receptors Modulate [ 3H]GABA Release at StriatoPallidal Terminals via Activation of PLC → IP3 → Calcineurin and Inhibition of AC → cAMP → PKA Signaling Cascades. Neuroscience 2017; 372:74-86. [PMID: 29292080 DOI: 10.1016/j.neuroscience.2017.12.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 12/14/2017] [Accepted: 12/23/2017] [Indexed: 01/11/2023]
Abstract
Striatal dopamine D2 receptors activate the PLC → IP3 → Calcineurin-signaling pathway to modulate the neural excitability of En+ Medium-sized Spiny GABAergic neurons (MSN) through the regulation of L-type Ca2+ channels. Presynaptic dopaminergic D2 receptors modulate GABA release at striatopallidal terminals through L-type Ca2+ channels as well, but their signaling pathway is still undetermined. Since D2 receptors are Gi/o-coupled and negatively modulate adenylyl cyclase (AC), we investigated whether presynaptic D2 receptors modulate GABA release through the same signaling cascade that controls excitability in the striatum or by the inhibition of AC and decreased PKA activity. Activation of D2 receptors stimulated formation of [3H]IP1 and decreased Forskolin-stimulated [3H]cAMP accumulation in synaptosomes from rat Globus Pallidus. D2 receptor activation with Quinpirole in the presence of L 745,870 decreased, in a dose-dependent manner, K+-induced [3H]GABA release in pallidal slices. The effect was prevented by the pharmacological blockade of Gi/o βγ subunit effects with Gallein, PLC with U 73122, IP3 receptor activation with 4-APB, Calcineurin with FK506. In addition, when release was stimulated with Forskolin to activate AC, D2 receptors also decreased K+-induced [3H]GABA release, an effect occluded with the effect of the blockade of PKA with H89 or stimulation of release with the cAMP analog 8-Br-cAMP. These data indicate that D2 receptors modulate [3H]GABA release at striatopallidal terminals by activating the PLC → IP3 → Calcineurin-signaling cascade, the same one that modulates excitability in soma. Additionally, D2 receptors inhibit release when AC is active. Both mechanisms appear to converge to regulate the activity of presynaptic L-type Ca2+ channels.
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Affiliation(s)
- Rafael Jijón-Lorenzo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico
| | - Isaac Hiram Caballero-Florán
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico
| | | | - Hernán Cortés
- Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra, Ciudad de México, Mexico
| | - José Arturo Avalos-Fuentes
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico
| | - Francisco Javier Paz-Bermúdez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico
| | - David Erlij
- Department of Physiology, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA
| | - Benjamín Florán
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico.
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Abrahao KP, Salinas AG, Lovinger DM. Alcohol and the Brain: Neuronal Molecular Targets, Synapses, and Circuits. Neuron 2017; 96:1223-1238. [PMID: 29268093 PMCID: PMC6566861 DOI: 10.1016/j.neuron.2017.10.032] [Citation(s) in RCA: 247] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/30/2017] [Accepted: 10/27/2017] [Indexed: 12/13/2022]
Abstract
Ethanol is one of the most commonly abused drugs. Although environmental and genetic factors contribute to the etiology of alcohol use disorders, it is ethanol's actions in the brain that explain (1) acute ethanol-related behavioral changes, such as stimulant followed by depressant effects, and (2) chronic changes in behavior, including escalated use, tolerance, compulsive seeking, and dependence. Our knowledge of ethanol use and abuse thus relies on understanding its effects on the brain. Scientists have employed both bottom-up and top-down approaches, building from molecular targets to behavioral analyses and vice versa, respectively. This review highlights current progress in the field, focusing on recent and emerging molecular, cellular, and circuit effects of the drug that impact ethanol-related behaviors. The focus of the field is now on pinpointing which molecular effects in specific neurons within a brain region contribute to behavioral changes across the course of acute and chronic ethanol exposure.
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Affiliation(s)
- Karina P Abrahao
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - Armando G Salinas
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - David M Lovinger
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA.
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12
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Broad-spectrum protein kinase inhibition by the staurosporine analog KT-5720 reverses ethanol withdrawal-associated loss of NeuN/Fox-3. Alcohol 2017; 64:37-43. [PMID: 28965654 DOI: 10.1016/j.alcohol.2017.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 05/24/2017] [Accepted: 05/25/2017] [Indexed: 11/22/2022]
Abstract
Chronic, intermittent ethanol (CIE) exposure is known to produce neuroadaptive alterations in excitatory neurotransmission that contribute to the development of dependence. Although activation of protein kinases (e.g., cyclic AMP [cAMP]-dependent protein kinase) is implicated in the synaptic trafficking of these receptors following CIE exposure, the functional consequences of these effects are yet to be fully understood. The present study sought to delineate the influence of protein kinase in regulating cytotoxicity following CIE exposure, as well as to examine the relative roles of ethanol exposure and ethanol withdrawal (EWD) in promoting these effects. Rat hippocampal explants were exposed to a developmental model of CIE with or without co-application of broad-spectrum protein kinase inhibitor KT-5720 (1 μM) either during ethanol exposure or EWD. Hippocampal cytotoxicity was assessed via immunofluorescence (IF) of neuron-specific nuclear protein (NeuN) with thionine staining of Nissl bodies to confirm IF findings. Concomitant application of ethanol and KT-5720 restored the loss of NeuN/Fox-3 IF in pyramidal CA1 and granule DG cell layers produced by CIE, but there was no restoration in CA3. Application of KT-5720 during EWD failed to significantly alter levels of NeuN IF, implying that ethanol exposure activates protein kinases that, in part, mediate the effects of EWD. KT-5720 application during EWD also restored thionine staining in CA1, suggesting kinase regulation of both neurons and non-neuronal cells. These data demonstrate that CIE exposure alters protein kinase activity to promote ethanol withdrawal-associated loss of NeuN/Fox-3 and highlight the influence of kinase signaling on distinct cell types in the developing hippocampus.
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13
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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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14
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Carter JM, Landin JD, Gigante ED, Rieger SP, Diaz MR, Werner DF. Inhibitors of Calcium-Activated Anion Channels Modulate Hypnotic Ethanol Responses in Adult Sprague Dawley Rats. Alcohol Clin Exp Res 2016; 40:301-8. [PMID: 26842249 DOI: 10.1111/acer.12957] [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: 03/13/2015] [Accepted: 11/02/2015] [Indexed: 11/26/2022]
Abstract
BACKGROUND Ethanol is widely known for its depressant effects; however, the underlying neurobiological mechanisms are not clear. Calcium-activated anion channels (CAACs) contribute to extracellular chloride levels and thus may be involved in regulating inhibitory mechanisms within the central nervous system. Therefore, we hypothesized that CAACs influence ethanol behavioral sensitivity by altering CAAC expression. METHODS We assessed the role of CAACs in ethanol-induced loss of righting reflex (LORR) and locomotor activity using intracerebroventricular infusions of several nonselective CAAC blockers. CAAC expression was determined after ethanol exposure. RESULTS Ethanol-induced LORR (4.0 g/kg, intraperitoneally [i.p.]) was significantly attenuated by all 4 CAAC blockers. Blocking CAACs did not impact ethanol's low-dose (1.5 g/kg, i.p.) locomotor-impairing effects. Biochemical analysis of CAAC protein expression revealed that cortical Bestrophin1 (Best1) and Tweety1 levels were reduced as early as 30 minutes following a single ethanol injection (3.5 g/kg, intraperitoneally [i.p.]) and remained decreased 24 hours later in P2 fractions. Cortical Best1 levels were also reduced following 1.5 g/kg. However, CAAC expression was unaltered in the striatum following a single ethanol exposure. Ethanol did not affect Tweety2 levels in either brain region. CONCLUSIONS These results suggest that CAACs are a major target of ethanol in vivo, and the regulation of these channels contributes to select behavioral actions of ethanol.
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Affiliation(s)
- Jenna M Carter
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, New York
| | - Justine D Landin
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, New York
| | - Eduardo D Gigante
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, New York.,Department of Health and Human Services, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland
| | - Samuel P Rieger
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, New York
| | - Marvin R Diaz
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, New York
| | - David F Werner
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, New York
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15
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Ethanol modulates facial stimulation-evoked outward currents in cerebellar Purkinje cells in vivo in mice. Sci Rep 2016; 6:30857. [PMID: 27489024 PMCID: PMC4973232 DOI: 10.1038/srep30857] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 07/08/2016] [Indexed: 11/16/2022] Open
Abstract
Acute ethanol overdose can induce dysfunction of cerebellar motor regulation and cerebellar ataxia. In this study, we investigated the effect of ethanol on facial stimulation-evoked inhibitory synaptic responses in cerebellar Purkinje cells (PCs) in urethane-anesthetized mice, using in vivo patch-clamp recordings. Under voltage-clamp conditions, ethanol (300 mM) decreased the amplitude, half-width, rise time and decay time of facial stimulation-evoked outward currents in PCs. The ethanol-induced inhibition of facial stimulation-evoked outward currents was dose-dependent, with an IC50 of 148.5 mM. Notably, the ethanol-induced inhibition of facial stimulation-evoked outward currents were significantly abrogated by cannabinoid receptor 1 (CB1) antagonists, AM251 and O-2050, as well as by the CB1 agonist WIN55212-2. Moreover, the ethanol-induced inhibition of facial stimulation-evoked outward currents was prevented by cerebellar surface perfusion of the PKA inhibitors H-89 and Rp-cAMP, but not by intracellular administration of the PKA inhibitor PKI. Our present results indicate that ethanol inhibits the facial stimulation-evoked outward currents by activating presynaptic CB1 receptors via the PKA signaling pathway. These findings suggest that ethanol overdose impairs sensory information processing, at least in part, by inhibiting GABA release from molecular layer interneurons onto PCs.
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16
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Effect of ruthenium red, a ryanodine receptor antagonist in experimental diabetes induced vascular endothelial dysfunction and associated dementia in rats. Physiol Behav 2016; 164:140-50. [PMID: 27262216 DOI: 10.1016/j.physbeh.2016.05.052] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 05/29/2016] [Accepted: 05/31/2016] [Indexed: 12/14/2022]
Abstract
Diabetes mellitus is considered as a main risk factor for vascular dementia. In the past, we have reported the induction of vascular dementia by experimental diabetes. This study investigates the efficacy of a ruthenium red, a ryanodine receptor antagonist and pioglitazone in the pharmacological interdiction of pancreatectomy diabetes (PaD) induced vascular endothelial dysfunction and subsequent vascular dementia in rats. Attentional set shifting and Morris water-maze test were used for assessment of learning and memory. Vascular endothelial function, blood brain barrier permeability, serum glucose, serum nitrite/nitrate, oxidative stress (viz. aortic superoxide anion, brain thiobarbituric acid reactive species and brain glutathione), brain calcium and inflammation (myeloperoxidase) were also estimated. PaD rats have shown impairment of endothelial function, blood brain barrier permeability, learning and memory along with an increase in brain inflammation, oxidative stress and calcium. Administration of ruthenium red and pioglitazone has significantly attenuated PaD induced impairment of learning, memory, blood brain barrier permeability, endothelial function and biochemical parameters. It may be concluded that ruthenium red, a ryanodine receptor antagonist and pioglitazone, a PPAR-γ agonist may be considered as potent pharmacological agent for the management of PaD induced endothelial dysfunction and subsequent vascular dementia. Ryanodine receptor may be explored further for their possible benefits in vascular dementia.
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17
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Reynolds AR, Saunders MA, Prendergast MA. Ethanol Stimulates Endoplasmic Reticulum Inositol Triphosphate and Sigma Receptors to Promote Withdrawal-Associated Loss of Neuron-Specific Nuclear Protein/Fox-3. Alcohol Clin Exp Res 2016; 40:1454-61. [PMID: 27177604 DOI: 10.1111/acer.13097] [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: 01/14/2016] [Accepted: 04/01/2016] [Indexed: 02/02/2023]
Abstract
BACKGROUND Prior studies demonstrate that ethanol (EtOH) exposure induces the release of intracellular calcium (CA(2+) ) in modulation of γ-aminobutyric acid-ergic tone and produces concomitant alterations in sigma (σ)-1 protein expression that may contribute to the development EtOH dependence. However, the influence of CA(2+) released from endoplasmic reticulum (ER)-bound inositol triphosphate (IP3) and σ-1 receptors in regulating hippocampal function has yet to be delineated. METHODS Rat hippocampal explants were subjected to chronic intermittent EtOH (CIE) exposure with or without the addition of IP3 inhibitor xestospongin C (0 to 0.5 μM) or σ-1 receptor antagonist BD-1047 (0 to 80 μM). Hippocampal viability was assessed via immunohistochemical labeling of neuron-specific nuclear protein (NeuN)/Fox-3 in CA1, CA3, and dentate gyrus (DG) subregions. RESULTS Exposure to CIE produced consistent and significant decreases of NeuN/Fox-3 in each primary cell layer of the hippocampal formation. Co-exposure to xestospongin reversed these effects in the CA1 subregion and significantly attenuated these effects in the CA3 and DG regions. Xestospongin application also significantly increased NeuN/Fox-3 immunofluorescence in EtOH-naïve hippocampi. Co-exposure to 20 μM BD-1047 also reversed the loss of NeuN/Fox-3 during CIE exposure in each hippocampal cell layer, whereas exposure to 80 μM BD-1047 did not alter NeuN/Fox-3 in EtOH-treated hippocampi. By contrast, 80 μM BD-1047 application significantly increased NeuN/Fox-3 immunofluorescence in EtOH-naïve hippocampi in each subregion. CONCLUSIONS These data suggest that EtOH stimulates ER IP3 and σ-1 receptors to promote hippocampal loss of NeuN/Fox-3 during CIE.
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Affiliation(s)
- Anna R Reynolds
- Department of Behavioral Science, University of Kentucky, Lexington, Kentucky
| | - Meredith A Saunders
- Department of Psychology, University of Kentucky, Lexington, Kentucky.,Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky
| | - Mark A Prendergast
- Department of Psychology, University of Kentucky, Lexington, Kentucky.,Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky
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18
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Valenzuela CF, Jotty K. Mini-Review: Effects of Ethanol on GABAA Receptor-Mediated Neurotransmission in the Cerebellar Cortex--Recent Advances. THE CEREBELLUM 2016; 14:438-46. [PMID: 25575727 DOI: 10.1007/s12311-014-0639-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Studies from several laboratories have shown that ethanol impairs cerebellar function, in part, by altering GABAergic transmission. Here, we discuss recent advances in our understanding of the acute effects of ethanol on GABA(A) receptor-mediated neurotransmission at cerebellar cortical circuits, mainly focusing on electrophysiological studies with slices from laboratory animals. These studies have shown that acute ethanol exposure increases GABA release at molecular layer interneuron-to-Purkinje cell synapses and also at reciprocal synapses between molecular layer interneurons. In granule cells, studies with rat cerebellar slices have consistently shown that acute ethanol exposure both potentiates tonic currents mediated by extrasynaptic GABA(A) receptors and also increases the frequency of spontaneous inhibitory postsynaptic currents mediated by synaptic GABA(A) receptors. These effects have been also documented in some granule cells from mice and nonhuman primates. Currently, there are two distinct models on how ethanol produces these effects. In one model, ethanol primarily acts by directly potentiating extrasynaptic GABA(A) receptors, including a population that excites granule cell axons and stimulates glutamate release onto Golgi cells. In the other model, ethanol acts indirectly by increasing spontaneous Golgi cell firing via inhibition of the Na(+)/K(+) ATPase, a quinidine-sensitive K(+) channel, and neuronal nitric oxide synthase. It was also demonstrated that a direct inhibitory effect of ethanol on tonic currents can be unmasked under conditions of low protein kinase C activity. In the last section, we briefly discuss studies on the chronic effect of ethanol on cerebellar GABA(A) receptor-mediated transmission and highlight potential areas where future research is needed.
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Affiliation(s)
- C Fernando Valenzuela
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM, 87131, USA,
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19
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Korpi ER, den Hollander B, Farooq U, Vashchinkina E, Rajkumar R, Nutt DJ, Hyytiä P, Dawe GS. Mechanisms of Action and Persistent Neuroplasticity by Drugs of Abuse. Pharmacol Rev 2015; 67:872-1004. [DOI: 10.1124/pr.115.010967] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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20
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Baliño P, Ledesma JC, Aragon CMG. Role of CA2+/calmodulin on ethanol neurobehavioral effects. Psychopharmacology (Berl) 2014; 231:4611-21. [PMID: 24853690 DOI: 10.1007/s00213-014-3610-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Accepted: 04/29/2014] [Indexed: 01/13/2023]
Abstract
RATIONALE The cAMP-dependent protein kinase A (PKA) signaling transduction pathway has been shown to play an important role in the modulation of several ethanol-induced behaviors. Different studies have demonstrated intracellular calcium (Ca(2+))-dependent activation of the PKA cascade after ethanol administration. Thus, the cAMP cascade mediator Ca(2+)-dependent calmodulin (CaM) has been strongly implicated in the central effects of ethanol. OBJECTIVES In this study, we assessed the role of the CaM inhibitor W7 on ethanol-induced stimulation, ethanol intake, and ethanol-induced activation of PKA. METHODS Swiss mice were pretreated with W7 (0-10 mg/kg) 30 min before ethanol (0-3.75 g/kg) administration. Immediately, animals were placed during 20 min in an open-field chamber. Ethanol (10 %, v/v) intake in 2 h was assessed using a limited access paradigm. Experiments with caffeine (0-15 mg/kg), cocaine (0-4 mg/kg), and saccharine (0.1 %, w/v) were designed to compare their results to those obtained with ethanol. Western blot was assayed 45 min after ethanol administration. RESULTS Results showed that pretreatment with W7, reduced selectively in a dose-dependent fashion ethanol-induced locomotor stimulation and ethanol intake. The ethanol-induced activation of PKA was also prevented by W7 administration. CONCLUSIONS These results demonstrate that CaM inhibition resulted in a selective reduction of ethanol-stimulating effects and ethanol intake. The PKA activation induced by ethanol was blocked after the CaM blockade with W7. These results provide further evidence of the key role of cellular Ca(2+)-dependent pathways on the central effects of ethanol.
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Affiliation(s)
- Pablo Baliño
- Área de Psicobiología, Universtitat Jaume I, Avda. Sos Baynat s/n, 12071, Castellón, Spain,
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21
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Characterization of activity-dependent changes in flavoprotein fluorescence in cerebellar slices from juvenile rats. Neurosci Lett 2014; 584:17-22. [PMID: 25301569 DOI: 10.1016/j.neulet.2014.09.052] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/17/2014] [Accepted: 09/29/2014] [Indexed: 01/30/2023]
Abstract
Flavoprotein autofluorescence signals attributed to neuronal metabolism have been used to assess synaptic function. Here, we characterized flavoprotein autofluorescence responses in the molecular layer of rat cerebellar slices. High frequency stimulation elicited a transient fluorescence increase (peak phase) that was followed by a longer-lasting fluorescence decrease (valley phase). The peak phase was restricted to the molecular layer, whereas the valley phase extended into the Purkinje cell layer and a portion of the granule cell layer. Responses were abolished by either the Na(+) channel antagonist, tetrodotoxin, or a combination of the AMPA receptor antagonists, NBQX and GIKI-53655, and were also reduced by a flavoprotein inhibitor (diphenyleneiodonium). These findings are consistent with responses being mediated by an increase in mitochondrial activity triggered by increased energy demands evoked by AMPA receptor-mediated synaptic transmission. The GABAA receptor antagonist picrotoxin did not significantly influence evoked responses. Likewise, exogenous application of ethanol, at concentrations known to increase GABAA receptor-mediated synaptic transmission at Purkinje cells, did not modify peak responses. These observations indicate that flavoprotein autofluorescence imaging could be useful to assess the coupling between glutamatergic synaptic transmission and neuronal metabolism in cerebellar slices.
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22
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Cui SB, Cui BR, Liu H, Wu MC, Xu YH, Bian JH, Chu CP, Qiu DL. Effects of ethanol on sensory stimulus-evoked responses in the cerebellar molecular layer in vivo in mice. Neurosci Lett 2014; 577:112-6. [PMID: 24861511 DOI: 10.1016/j.neulet.2014.05.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2014] [Revised: 05/06/2014] [Accepted: 05/13/2014] [Indexed: 11/20/2022]
Abstract
Overdose intake of ethanol can impair cerebellar cortical neurons to integrate and transfer external information, resulting in a dysfunction of cerebellar motor regulation or cerebellar ataxia. However, the mechanisms underlying ethanol-impaired transfer of sensory information from cerebellar cortical molecular layer neurons remain unclear. In the present study, we investigated the effects of ethanol on sensory stimulation-evoked responses in the cerebellar molecular layer of urethane-anesthetized mice, by electrophysiological and pharmacological methods. Our results demonstrated that air-puff stimulation (30 ms, 50-60 psi) of the ipsilateral whisker-pad evoked field potential responses in the molecular layer of the cerebellar cortex folium Crus II, which expressed a negative component (N1) followed by a gamma-aminobutyric acid receptor A (GABAA)-mediated positive component (P1). Cerebellar surface perfusion of ethanol between 2 and 5mM did not change the latency of the evoked responses and the amplitude of N1, but enhanced the amplitude and the area under the curve of P1. Interestingly, high concentrations (>20mM) of ethanol induced a significantly decrease in the amplitude and area under the curve of P1. Furthermore, high concentration ethanol (300 mM) significantly decreased the rise in tau and tau decay value of P1, whereas low concentration ethanol (2-5mM) significantly increased these values of P1. Inhibition of GABAA receptor activity reversed P1 and also abolished the effects of ethanol on sensory stimulation-evoked responses. These results indicated that ethanol induced a bidirectional effect on the sensory stimulation-evoked GABAergic responses in the cerebellar cortical molecular layer, suggesting that acute alcohol intake impacted the sensory information processing of cerebellar cortex.
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Affiliation(s)
- Song-Biao Cui
- Department of Neurology, Affiliated Hospital of Yanbian University, Yanji City 133002, Jilin Province, China
| | - Bai-Ri Cui
- Cellular Function Research Center, Yanbian University, Yanji City 133002, Jilin Province, China
| | - Heng Liu
- Cellular Function Research Center, Yanbian University, Yanji City 133002, Jilin Province, China
| | - Mao-Cheng Wu
- Cellular Function Research Center, Yanbian University, Yanji City 133002, Jilin Province, China
| | - Yin-Hua Xu
- Department of Neurology, Affiliated Hospital of Yanbian University, Yanji City 133002, Jilin Province, China
| | - Jin-Hua Bian
- Cellular Function Research Center, Yanbian University, Yanji City 133002, Jilin Province, China
| | - Chun-Ping Chu
- Cellular Function Research Center, Yanbian University, Yanji City 133002, Jilin Province, China.
| | - De-Lai Qiu
- Cellular Function Research Center, Yanbian University, Yanji City 133002, Jilin Province, China.
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The environmental neurotoxicant PCB 95 promotes synaptogenesis via ryanodine receptor-dependent miR132 upregulation. J Neurosci 2014; 34:717-25. [PMID: 24431430 DOI: 10.1523/jneurosci.2884-13.2014] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Non-dioxin-like (NDL) polychlorinated biphenyls (PCBs) are widespread environmental contaminants linked to neuropsychological dysfunction in children. NDL PCBs increase spontaneous Ca(2+) oscillations in neurons by stabilizing ryanodine receptor (RyR) calcium release channels in the open configuration, which results in CREB-dependent dendritic outgrowth. In this study, we address the question of whether activation of CREB by NDL PCBs also triggers dendritic spine formation. Nanomolar concentrations of PCB 95, a NDL congener with potent RyR activity, significantly increased spine density and the frequency of miniature EPSCs in primary dissociated rat hippocampal cultures coincident with upregulation of miR132. Inhibition of RyR, CREB, or miR132 as well as expression of a mutant p250GAP cDNA construct that is not suppressed by miR132 blocked PCB 95 effects on spines and miniature EPSCs. PCB 95 also induced spine formation via RyR- and miR132-dependent mechanisms in hippocampal slice cultures. These data demonstrate a novel mechanism of PCB developmental neurotoxicity whereby RyR sensitization modulates spine formation and synaptogenesis via CREB-mediated miR132 upregulation, which in turn suppresses the translation of p250GAP, a negative regulator of synaptogenesis. In light of recent evidence implicating miR132 dysregulation in Rett syndrome and schizophrenia, these findings identify NDL PCBs as potential environmental risk factors for neurodevelopmental disorders.
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Mariqueo TA, Agurto A, Muñoz B, San Martin L, Coronado C, Fernández-Pérez EJ, Murath P, Sánchez A, Homanics GE, Aguayo LG. Effects of ethanol on glycinergic synaptic currents in mouse spinal cord neurons. J Neurophysiol 2014; 111:1940-8. [PMID: 24572089 DOI: 10.1152/jn.00789.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Ethanol increased the frequency of miniature glycinergic currents [miniature inhibitory postsynaptic currents (mIPSCs)] in cultured spinal neurons. This effect was dependent on intracellular calcium augmentation, since preincubation with BAPTA (an intracellular calcium chelator) or thapsigargin [a sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) pump inhibitor] significantly attenuated this effect. Similarly, U73122 (a phospholipase C inhibitor) or 2-aminoethoxydiphenyl borate [2-APB, an inositol 1,4,5-trisphosphate (IP₃) receptor (IP3R) inhibitor] reduced this effect. Block of ethanol action was also achieved after preincubation with Rp-cAMPS, inhibitor of the adenylate cyclase (AC)/PKA signaling pathway. These data suggest that there is a convergence at the level of IP₃R that accounts for presynaptic ethanol effects. At the postsynaptic level, ethanol increased the decay time constant of mIPSCs in a group of neurons (30 ± 10% above control, n = 13/26 cells). On the other hand, the currents activated by exogenously applied glycine were consistently potentiated (55 ± 10% above control, n = 11/12 cells), which suggests that ethanol modulates synaptic and nonsynaptic glycine receptors (GlyRs) in a different fashion. Supporting the role of G protein modulation on ethanol responses, we found that a nonhydrolyzable GTP analog [guanosine 5'-O-(3-thiotriphosphate) (GTPγS)] increased the decay time constant in ∼50% of the neurons (28 ± 12%, n = 11/19 cells) but potentiated the glycine-activated Cl(-) current in most of the neurons examined (83 ± 29%, n = 7/9 cells). In addition, confocal microscopy showed that α1-containing GlyRs colocalized with Gβ and Piccolo (a presynaptic cytomatrix protein) in ∼40% of synaptic receptor clusters, suggesting that colocalization of Gβγ and GlyRs might account for the difference in ethanol sensitivity at the postsynaptic level.
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Affiliation(s)
- Trinidad A Mariqueo
- Department of Physiology-Laboratory of Neurophysiology, University of Concepción, Concepción, Chile; PhD Program in Pharmacology, University of Chile, Santiago, Chile; and
| | - Adolfo Agurto
- Department of Physiology-Laboratory of Neurophysiology, University of Concepción, Concepción, Chile
| | - Braulio Muñoz
- Department of Physiology-Laboratory of Neurophysiology, University of Concepción, Concepción, Chile
| | - Loreto San Martin
- Department of Physiology-Laboratory of Neurophysiology, University of Concepción, Concepción, Chile
| | - Cesar Coronado
- Department of Physiology-Laboratory of Neurophysiology, University of Concepción, Concepción, Chile
| | | | - Pablo Murath
- Department of Physiology-Laboratory of Neurophysiology, University of Concepción, Concepción, Chile
| | - Andrea Sánchez
- Department of Physiology-Laboratory of Neurophysiology, University of Concepción, Concepción, Chile
| | - Gregg E Homanics
- Department of Anesthesiology and Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Luis G Aguayo
- Department of Physiology-Laboratory of Neurophysiology, University of Concepción, Concepción, Chile;
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Gmaz JM, McKay BE. Toluene decreases Purkinje cell output by enhancing inhibitory synaptic transmission in the cerebellar cortex. Neurosci Lett 2014; 560:1-6. [PMID: 24345417 DOI: 10.1016/j.neulet.2013.12.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 12/07/2013] [Accepted: 12/09/2013] [Indexed: 11/29/2022]
Abstract
Toluene belongs to a class of psychoactive drugs known as inhalants. Found in common household products such as adhesives, paint products, and aerosols, toluene is inhaled for its intoxicating and euphoric properties. Additionally, exposure to toluene disrupts motor behaviors in a manner consistent with impairments to cerebellar function. Previous work has suggested a role of GABA in mediating toluene's neurobehavioral effects, but how this manifests in the cerebellar cortex is not yet understood. In the present study, we examined the effects of toluene on cerebellar Purkinje cell action potential output and inhibitory synaptic transmission onto Purkinje cells using patch clamp electrophysiology in acute rat cerebellar slices. Toluene (1mM) reduced the frequency of Purkinje cell action potential output without affecting input resistance. Furthermore, toluene dose-dependently enhanced inhibitory synaptic transmission onto Purkinje cells, increasing the amplitude and frequency of inhibitory postsynaptic currents; no change in the frequency of action potentials from molecular layer interneurons was noted. The observed decreases in Purkinje cell action potential output could contribute to toluene-evoked impairments in cerebellar and motor functions.
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Affiliation(s)
- Jimmie M Gmaz
- Department of Psychology, Wilfrid Laurier University, Waterloo, ON N2L 3C5, Canada
| | - Bruce E McKay
- Department of Psychology, Wilfrid Laurier University, Waterloo, ON N2L 3C5, Canada.
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26
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Wu G, Liu H, Jin J, Hong L, Lan Y, Chu CP, Qiu DL. Ethanol attenuates sensory stimulus-evoked responses in cerebellar granule cells via activation of GABA(A) receptors in vivo in mice. Neurosci Lett 2014; 561:107-11. [PMID: 24388841 DOI: 10.1016/j.neulet.2013.12.049] [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] [Received: 08/26/2013] [Revised: 12/19/2013] [Accepted: 12/21/2013] [Indexed: 10/25/2022]
Abstract
Acute alcohol intoxication affects cerebellar motor regulation possibly by altering the transfer and integration of external information in cerebellar cortical neurons, resulting in a dysfunction of cerebellar motor regulation or a cerebellar atexia. However, the synaptic mechanisms of ethanol induced impairments of sensory information processing in cerebellar cortical neurons are not fully understand. In the present study, we used electrophysiological and pharmacological methods to study the effects of ethanol on the sensory stimulation-evoked responses in cerebellar granule cells (GCs) in vivo in urethane anesthetized mice. Air-puff stimulation of the ipsilateral whisker-pad evoked stimulus-on (P1) and stimulus-off responses (P2) in GCs of cerebellar Crus II. Cerebellar surface perfusion of ethanol did not alter the onset latency of the sensory stimulation-evoked responses, but reversible reduced the amplitude of P1 and P2. The ethanol-induced reduction of the GCs sensory responses was concentration-dependent. In the presence of ethanol, the mean half-width, area under curve, rise Tau and decay Tau of P1 were significantly decreased. Blockade of gamma-aminobutyric acid type A (GABA(A)) receptors activity induced an increase in amplitude of P1, and abolished the ethanol induced inhibition of the GCs sensory responses. These results indicate that ethanol inhibits the tactile evoked responses in cerebellar GCs through enhancement of GABA(A) receptors activity.
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Affiliation(s)
- Guang Wu
- Department of Neurology, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province, China
| | - Heng Liu
- Cellular Function Research Center, Yanbian University, Yanji City, Jilin Province, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province, China
| | - Juan Jin
- Department of Neurology, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province, China
| | - Lan Hong
- Cellular Function Research Center, Yanbian University, Yanji City, Jilin Province, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province, China
| | - Yan Lan
- Cellular Function Research Center, Yanbian University, Yanji City, Jilin Province, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province, China
| | - Chun-Ping Chu
- Cellular Function Research Center, Yanbian University, Yanji City, Jilin Province, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province, China.
| | - De-Lai Qiu
- Cellular Function Research Center, Yanbian University, Yanji City, Jilin Province, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province, China.
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Varodayan FP, Harrison NL. HSF1 transcriptional activity mediates alcohol induction of Vamp2 expression and GABA release. Front Integr Neurosci 2013; 7:89. [PMID: 24376402 PMCID: PMC3858671 DOI: 10.3389/fnint.2013.00089] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 11/20/2013] [Indexed: 01/08/2023] Open
Abstract
Many central synapses are highly sensitive to alcohol, and it is now accepted that short-term alterations in synaptic function may lead to longer-term changes in circuit function. The regulation of postsynaptic receptors by alcohol has been well studied, but the mechanisms underlying the effects of alcohol on the presynaptic terminal are relatively unexplored. To identify a pathway by which alcohol regulates neurotransmitter release, we recently investigated the mechanism by which ethanol induces Vamp2, but not Vamp1, in mouse primary cortical cultures. These two genes encode isoforms of synaptobrevin, a vesicular soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein required for synaptic vesicle fusion. We found that alcohol activates the transcription factor heat shock factor 1 (HSF1) to induce Vamp2 expression, while Vamp1 mRNA levels remain unaffected. As the Vamp2 gene encodes a SNARE protein, we then investigated whether ethanol exposure and HSF1 transcriptional activity alter neurotransmitter release using electrophysiology. We found that alcohol increased the frequency of γ-aminobutyric acid (GABA)-mediated miniature IPSCs via HSF1, but had no effect on mEPSCs. Overall, these data indicate that alcohol induces HSF1 transcriptional activity to trigger a specific coordinated adaptation in GABAergic presynaptic terminals. This mechanism could explain some of the changes in synaptic function that occur soon after alcohol exposure, and may underlie some of the more enduring effects of chronic alcohol intake on local circuit function.
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Affiliation(s)
- Florence P Varodayan
- Department of Neuroscience, Columbia University New York City, NY, USA ; Department of Anesthesiology, Columbia University New York City, NY, USA
| | - Neil L Harrison
- Department of Anesthesiology, Columbia University New York City, NY, USA ; Department of Pharmacology, Columbia University New York City, NY, USA
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Baliño P, Ledesma JC, Aragon CMG. In vivo study of ethanol-activated brain protein kinase A: manipulations of Ca2+ distribution and flux. Alcohol Clin Exp Res 2013; 38:629-40. [PMID: 24117724 DOI: 10.1111/acer.12289] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 08/21/2013] [Indexed: 01/19/2023]
Abstract
BACKGROUND The cAMP-dependent protein kinase (PKA) signaling transduction pathway has been shown to play an important role in the modulation of several ethanol (EtOH)-induced behavioral actions. In vivo, short-term exposure to EtOH up-regulates the cAMP-signaling cascade. Interestingly, different Ca(2+) -dependent cAMP-PKA cascade mediators play a critical role in the neurobehavioral response to EtOH, being of special relevance to the Ca(2+) -dependent adenylyl cyclases 1 and 8. We hypothesize an intracellular PKA activation elicited by EtOH administration, which may be regulated by a Ca(2+) -dependent mechanism as an early cellular response. Thus, the present work aims to explore the role of Ca(2+) (internal and external) on the EtOH-activated PKA cascade. METHODS Swiss male mice received an intraperitoneal injection of EtOH (0 or 4 g/kg), and brains were dissected following a temporal pattern (7, 15, 30, 45, 90, or 120 minutes). Either the enzymatic PKA activity or its fingerprint was analyzed on different brain areas (cortex, hypothalamus, hippocampus, and striatum). To explore the role of Ca(2+) on the EtOH-activated PKA cascade, mice were pretreated with diltiazem (0 or 20 mg/kg), dantrolene (0 or 5 mg/kg), or 3,7-Dimethyl-1-(2-propynyl)xanthine (0 or 1 mg/kg) 30 minutes before EtOH (4 g/kg) administration. After 45 minutes of EtOH administration, brains were removed and dissected to measure the PKA activity or its fingerprint. RESULTS Results from these experiments showed an EtOH-dependent activation of PKA in different brain areas. Manipulations involving a disruption of intracellular Ca(2+) release from the endoplasmic reticulum resulted in a decreased EtOH-induced activation of PKA. On the contrary, extracellular-to-cytoplasm Ca(2+) manipulations did not prevent the PKA activation by EtOH. CONCLUSIONS Altogether, these results show the critical role of stored Ca(2+) as an intracellular mediator of different neurobiological actions of EtOH and provide further evidence of a possible new target for EtOH within the central nervous system.
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Affiliation(s)
- Pablo Baliño
- Area de Psicobiologia, Universitat Jaume I, Castellón, Spain
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Pignataro L, Varodayan FP, Tannenholz LE, Protiva P, Harrison NL. Brief alcohol exposure alters transcription in astrocytes via the heat shock pathway. Brain Behav 2013; 3:114-33. [PMID: 23533150 PMCID: PMC3607153 DOI: 10.1002/brb3.125] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 12/23/2012] [Accepted: 01/07/2013] [Indexed: 12/17/2022] Open
Abstract
Astrocytes are critical for maintaining homeostasis in the central nervous system (CNS), and also participate in the genomic response of the brain to drugs of abuse, including alcohol. In this study, we investigated ethanol regulation of gene expression in astrocytes. A microarray screen revealed that a brief exposure of cortical astrocytes to ethanol increased the expression of a large number of genes. Among the alcohol-responsive genes (ARGs) are glial-specific immune response genes, as well as genes involved in the regulation of transcription, cell proliferation, and differentiation, and genes of the cytoskeleton and extracellular matrix. Genes involved in metabolism were also upregulated by alcohol exposure, including genes associated with oxidoreductase activity, insulin-like growth factor signaling, acetyl-CoA, and lipid metabolism. Previous microarray studies performed on ethanol-treated hepatocyte cultures and mouse liver tissue revealed the induction of almost identical classes of genes to those identified in our microarray experiments, suggesting that alcohol induces similar signaling mechanisms in the brain and liver. We found that acute ethanol exposure activated heat shock factor 1 (HSF1) in astrocytes, as demonstrated by the translocation of this transcription factor to the nucleus and the induction of a family of known HSF1-dependent genes, the heat shock proteins (Hsps). Transfection of a constitutively transcriptionally active Hsf1 construct into astrocytes induced many of the ARGs identified in our microarray study supporting the hypothesis that HSF1 transcriptional activity, as part of the heat shock cascade, may mediate the ethanol induction of these genes. These data indicate that acute ethanol exposure alters gene expression in astrocytes, in part via the activation of HSF1 and the heat shock cascade.
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Affiliation(s)
- Leonardo Pignataro
- Department of Anesthesiology The College of Physicians and Surgeons, Columbia University 630 West 168th St., New York, NY, 10032
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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. This chapter reviews the literature describing these acute and chronic synaptic effects of EtOH and their relevance for synaptic transmission, plasticity, and behavior.
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Affiliation(s)
- David M Lovinger
- Laboratory for Integrative Neuroscience, NIAAA, 5625 Fishers Lane, Room TS-13A, Rockville, MD 20852, USA.
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Ferrari LF, Levine E, Levine JD. Independent contributions of alcohol and stress axis hormones to painful peripheral neuropathy. Neuroscience 2012; 228:409-17. [PMID: 23128028 DOI: 10.1016/j.neuroscience.2012.10.052] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 10/24/2012] [Accepted: 10/26/2012] [Indexed: 11/19/2022]
Abstract
Painful small-fiber peripheral neuropathy is a debilitating complication of chronic alcohol abuse. Evidence from previous studies suggests that neuroendocrine mechanisms, in combination with other, as yet unidentified actions of alcohol, are required to produce this neuropathic pain syndrome. In addition to neurotoxic effects of alcohol, in the setting of alcohol abuse neuroendocrine stress axes release glucocorticoids and catecholamines. Since receptors for these stress hormones are located on nociceptors, at which they can act to cause neuronal dysfunction, we tested the hypothesis that alcohol and stress hormones act on the nociceptor, independently, to produce neuropathic pain. We used a rat model, which allows the distinction of the effects of alcohol from those produced by neuroendocrine stress axis mediators. We now demonstrate that topical application of alcohol and exposure to unpredictable sound stress, each alone, has no effect on the nociceptive threshold. However, when animals that had previous exposure to alcohol were subsequently exposed to stress, they rapidly developed mechanical hyperalgesia. Conversely, sound stress followed by topical alcohol exposure also produced mechanical hyperalgesia. The contribution of stress hormones was prevented by spinal intrathecal administration of oligodeoxynucleotides antisense to β(2)-adrenergic or glucocorticoid receptor mRNA, which attenuates receptor level in nociceptors, as well as by adrenal medullectomy. These experiments establish an independent role of alcohol and stress hormones on the primary afferent nociceptor in the induction of painful peripheral neuropathy.
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Affiliation(s)
- L F Ferrari
- Departments of Medicine and Oral Surgery, Division of Neuroscience, University of California at San Francisco, 521 Parnassus Avenue, San Francisco, CA 94143-0440, USA
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Tarragon E, Baliño P, Aragon CMG. Dantrolene blockade of ryanodine receptor impairs ethanol-induced behavioral stimulation, ethanol intake and loss of righting reflex. Behav Brain Res 2012; 233:554-62. [PMID: 22677274 DOI: 10.1016/j.bbr.2012.05.046] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 05/22/2012] [Accepted: 05/26/2012] [Indexed: 12/21/2022]
Abstract
Calcium has been characterized as one of the most ubiquitous, universal and versatile intracellular signals. Among other substances with the ability to alter intracellular calcium levels, ethanol has been described as particularly relevant because of its social and economic impact. Ethanol effects on calcium distribution and flux in vitro have been widely studied, showing that acute ethanol administration can modulate intracellular calcium concentrations in a dose dependent manner. Intracellular calcium released from the endoplasmic reticulum plays a determinant role in several cellular processes. In this study, we aim to assess the effect of dantrolene, a ryanodine receptor antagonist, on three different ethanol-elicited behaviors: locomotor activity, loss of righting reflex and ethanol intake. Mice were challenged with an injection of dantrolene (0-5 mg/kg, i.p.) 30 min before ethanol (0-4 g/kg, i.p.) administration. Animals were immediately placed in an open field cylinder to monitor distance travelled horizontally or in a V-shaped trough to measure righting reflex recovery time. For ethanol intake, dantrolene (0-5mg/kg, i.p.) was administered 30 min before ethanol (20%, v/v) exposure, following a drinking in the dark paradigm. Our results showed that dantrolene selectively reduces ethanol-induced stimulation, loss of righting reflex, and ethanol intake in a dose dependent manner. Together, these data suggest that intracellular calcium released from the endoplasmic reticulum may play a critical role in behavioral effects caused by ethanol, and point to a calcium-dependent pathway as a possible cellular mechanism of action for ethanol.
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Affiliation(s)
- Ernesto Tarragon
- Area de Psicobiologia, Universitat Jaume I, 12071 Castellón, Spain
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Pava MJ, Woodward JJ. A review of the interactions between alcohol and the endocannabinoid system: implications for alcohol dependence and future directions for research. Alcohol 2012; 46:185-204. [PMID: 22459871 PMCID: PMC3327810 DOI: 10.1016/j.alcohol.2012.01.002] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 01/10/2012] [Accepted: 01/26/2012] [Indexed: 12/17/2022]
Abstract
Over the past fifty years a significant body of evidence has been compiled suggesting an interaction between the endocannabinoid (EC) system and alcohol dependence. However, much of this work has been conducted only in the past two decades following the elucidation of the molecular constituents of the EC system that began with the serendipitous discovery of the cannabinoid 1 receptor (CB1). Since then, novel pharmacological and genetic tools have enabled researchers to manipulate select components of the EC system, to determine their contribution to the motivation to consume ethanol. From these preclinical studies, it is evident that CB1 contributes the motivational and reinforcing properties of ethanol, and chronic consumption of ethanol alters EC transmitter levels and CB1 expression in brain nuclei associated with addiction pathways. These results are augmented by in vitro and ex vivo studies showing that acute and chronic treatment with ethanol produces physiologically relevant alterations in the function of the EC system. This report provides a current and comprehensive review of the literature regarding the interactions between ethanol and the EC system. We begin be reviewing the studies published prior to the discovery of the EC system that compared the behavioral and physiological effects of cannabinoids with ethanol in addition to cross-tolerance between these drugs. Next, a brief overview of the molecular constituents of the EC system is provided as context for the subsequent review of more recent studies examining the interaction of ethanol with the EC system. These results are compiled into a summary providing a scheme for the known changes to the components of the EC system in different stages of alcohol dependence. Finally, future directions for research are discussed.
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Affiliation(s)
- Matthew J. Pava
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29403, USA
- Charleston Alcohol Research Center, Medical University of South Carolina, Charleston, SC 29403, USA
| | - John J. Woodward
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29403, USA
- Charleston Alcohol Research Center, Medical University of South Carolina, Charleston, SC 29403, USA
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Wakita M, Shin MC, Iwata S, Nonaka K, Akaike N. Effects of ethanol on GABA(A) receptors in GABAergic and glutamatergic presynaptic nerve terminals. J Pharmacol Exp Ther 2012; 341:809-19. [PMID: 22434676 DOI: 10.1124/jpet.111.189126] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Ethanol (EtOH) has a number of behavioral effects, including intoxication, amnesia, and/or sedation, that are thought to relate to the activation of GABA(A) receptors. However, GABA(A) receptors at different cellular locations have different sensitivities to EtOH. The present study used the "synaptic bouton" preparation where we could stimulate nerve endings on mechanically dissociated single rat hippocampal CA1 and CA3 pyramidal neurons and investigate the effects of EtOH on presynaptic and postsynaptic GABA(A) receptors. Low concentrations of EtOH (10 mM) had no effect on postsynaptic GABA(A) and glutamate receptors or voltage-dependent Na(+) and Ca(2+) channels. Higher concentrations (≥100 mM) could significantly inhibit these current responses. EtOH at 10 mM had no direct effect on inhibitory postsynaptic currents (IPSCs) and excitatory postsynaptic currents (EPSCs) evoked by focal stimulation of single boutons [evoked IPSCs (eIPSCs) and evoked EPSCs (eEPSCs)]. However, coapplication of 10 mM EtOH with muscimol decreased the amplitude of eIPSCs and eEPSCs and increased their paired-pulse ratio. The effects on eEPSCs were reversed by bicuculline. Coapplication of muscimol and EtOH significantly increased the frequency of spontaneous IPSCs and EPSCs. The EtOH effects on the postsynaptic responses and eEPSCs were similar in neurons from neonatal and mature rats. These results revealed that low concentrations of EtOH can potentiate the activation of presynaptic GABA(A) receptors to inhibit evoked GABA and glutamate release. These results indicate a high sensitivity of presynaptic GABA(A) receptor to EtOH, which needs to be accounted for when considering the cellular mechanisms of EtOH's physiological responses.
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Affiliation(s)
- Masahito Wakita
- Research Division for Life Sciences, Kumamoto Health Science University, 325 Izumimachi, Kumamoto, 861-5598, Japan
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Intracellular calcium chelation with BAPTA-AM modulates ethanol-induced behavioral effects in mice. Exp Neurol 2012; 234:446-53. [PMID: 22306018 DOI: 10.1016/j.expneurol.2012.01.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 01/11/2012] [Accepted: 01/16/2012] [Indexed: 11/23/2022]
Abstract
Calcium (Ca(2+)) has been characterized as one of the most ubiquitous, universal and versatile intracellular signaling molecules responsible for controlling numerous cellular processes. Ethanol-induced effects on Ca(2+) distribution and flux have been widely studied in vitro, showing that acute ethanol administration can modulate intracellular Ca(2+) concentrations in a dose dependent manner. In vivo, the relationship between Ca(2+) manipulation and the corresponding ethanol-induced behavioral effects have focused on Ca(2+) flux through voltage-gated Ca(2+) channels. The present study investigated the role of inward Ca(2+) currents in ethanol-induced psychomotor effects (stimulation and sedation) and ethanol intake. We studied the effects of the fast Ca(2+) chelator, BAPTA-AM, on ethanol-induced locomotor activity and the sedative effects of ethanol. Swiss (RjOrl) mice were pretreated with BAPTA-AM (0-10 mg/kg) 30 min before an ethanol (0-4 g/kg) challenge. Our results revealed that pretreatment with BAPTA-AM prevented locomotor stimulation produced by ethanol without altering basal locomotion. In contrast, BAPTA-AM reversed ethanol-induced hypnotic effects. In a second set of experiments, we investigated the effects of intracellular Ca(2+) chelation on ethanol intake. Following a drinking-in-the-dark methodology, male C57BL/6J mice were offered 20% v/v ethanol, tap water, or 0.1% sweetened water. The results of these experiments revealed that BAPTA-AM pretreatment (0-5 mg/kg) reduced ethanol consumption in a dose-dependent manner while leaving water and sweetened water intake unaffected. Our findings support the role of inward Ca(2+) currents in mediating different behavioral responses induced by ethanol. Our results are discussed together with data indicating that ethanol appears to be more sensitive to intracellular Ca(2+) manipulations than other psychoactive drugs.
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Wadleigh A, Valenzuela CF. Ethanol increases GABAergic transmission and excitability in cerebellar molecular layer interneurons from GAD67-GFP knock-in mice. Alcohol Alcohol 2011; 47:1-8. [PMID: 22080831 DOI: 10.1093/alcalc/agr147] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
AIMS This study assessed the acute effect of ethanol on GABAergic transmission at molecular layer interneurons (MLIs; i.e. basket and stellate cells) in the cerebellar cortex. The actions of ethanol on spontaneous firing of these pacemaker neurons were also measured. METHODS Transgenic mice (glutamic acid-decarboxylase 67-green fluorescent protein knock-in mice) that express green fluorescence protein in GABAergic interneurons were used to aid in the identification of MLIs. Parasagittal cerebellar slices were prepared and whole-cell patch-clamp electrophysiological techniques were used to measure GABA(A) receptor-mediated spontaneous and miniature inhibitory postsynaptic currents (sIPSCs and mIPSCs). Loose-seal cell-attached recordings were used to measure spontaneous action potential firing. RESULTS Stellate cells received spontaneous GABAergic input in the form of a mixture of action potential-dependent events (sIPSCs) and quantal events (mIPSCs); ethanol increased sIPSC frequency to a greater extent than mIPSC frequency. Ethanol increased spontaneous action potential firing of MLIs, which could explain the increase in sIPSC frequency in stellate cells. Basket cells received GABAergic input in the form of quantal events only. Ethanol significantly increased the frequency of these events, which may be mediated by a different type of interneuron (perhaps, the Lugaro cell) or Purkinje cell collaterals. CONCLUSIONS Ethanol exposure differentially increases GABA release at stellate cell vs. basket cell-to-Purkinje cell synapses. This effect may contribute to the abnormalities in cerebellar function associated with alcohol intoxication.
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Affiliation(s)
- Aya Wadleigh
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, USA
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Gruol DL, Nelson TE, Hao C, Michael S, Vukojevic V, Ming Y, Terenius L. Ethanol alters opioid regulation of Ca(2+) influx through L-type Ca(2+) channels in PC12 cells. Alcohol Clin Exp Res 2011; 36:443-56. [PMID: 22014285 DOI: 10.1111/j.1530-0277.2011.01631.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Studies at the behavioral and synaptic level show that effects of ethanol on the central nervous system can involve the opioid signaling system. These interactions may alter the function of a common downstream target. In this study, we examined Ca(2+) channel function as a potential downstream target of interactions between ethanol and μ or κ opioid receptor signaling. METHODS The studies were carried out in a model system, undifferentiated PC12 cells transfected with μ or κ opioid receptors. The PC12 cells express L-type Ca(2+) channels, which were activated by K(+) depolarization. Ca(2+) imaging was used to measure relative Ca(2+) flux during K(+) depolarization and the modulation of Ca(2+) flux by opioids and ethanol. RESULTS Ethanol, μ receptor activation, and κ receptor activation all reduced the amplitude of the Ca(2+) signal produced by K(+) depolarization. Pretreatment with ethanol or combined treatment with ethanol and μ or κ receptor agonists caused a reduction in the amplitude of the Ca(2+) signal that was comparable to or smaller than that observed for the individual drugs alone, indicating an interaction by the drugs at a downstream target (or targets) that limited the modulation of Ca(2+) flux through L-type Ca(2+) channels. CONCLUSIONS These studies provide evidence for a cellular mechanism that could play an important role in ethanol regulation of synaptic transmission and behavior through interactions with the opioid signaling.
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Affiliation(s)
- Donna L Gruol
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, La Jolla, California 92037, USA
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Kelm MK, Criswell HE, Breese GR. Ethanol-enhanced GABA release: a focus on G protein-coupled receptors. BRAIN RESEARCH REVIEWS 2011; 65:113-23. [PMID: 20837058 PMCID: PMC3005894 DOI: 10.1016/j.brainresrev.2010.09.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 09/01/2010] [Accepted: 09/02/2010] [Indexed: 12/20/2022]
Abstract
While research on the actions of ethanol at the GABAergic synapse has focused on postsynaptic mechanisms, recent data have demonstrated that ethanol also facilitates GABA release from presynaptic terminals in many, but not all, brain regions. The ability of ethanol to increase GABA release can be regulated by different G protein-coupled receptors (GPCRs), such as the cannabinoid-1 receptor, corticotropin-releasing factor 1 receptor, GABA(B) receptor, and the 5-hydroxytryptamine 2C receptor. The intracellular messengers linked to these GPCRs, including the calcium that is released from internal stores, also play a role in ethanol-enhanced GABA release. Hypotheses are proposed to explain how ethanol interacts with the GPCR pathways to increase GABA release and how this interaction contributes to the brain region specificity of ethanol-enhanced GABA release. Defining the mechanism of ethanol-facilitated GABA release will further our understanding of the GABAergic profile of ethanol and increase our knowledge of how GABAergic neurotransmission may contribute to the intoxicating effects of alcohol and to alcohol dependence.
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Affiliation(s)
- M Katherine Kelm
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, NC 27599-7178, USA.
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Ethanol modulation of synaptic plasticity. Neuropharmacology 2010; 61:1097-108. [PMID: 21195719 DOI: 10.1016/j.neuropharm.2010.12.028] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 12/10/2010] [Accepted: 12/22/2010] [Indexed: 12/19/2022]
Abstract
Synaptic plasticity in the most general terms represents the flexibility of neurotransmission in response to neuronal activity. Synaptic plasticity is essential both for the moment-by-moment modulation of neural activity in response to dynamic environmental cues and for long-term learning and memory formation. These temporal characteristics are served by an array of pre- and post-synaptic mechanisms that are frequently modulated by ethanol exposure. This modulation likely makes significant contributions to both alcohol abuse and dependence. In this review, I discuss the modulation of both short-term and long-term synaptic plasticity in the context of specific ethanol-sensitive cellular substrates. A general discussion of the available preclinical, animal-model based neurophysiology literature provides a comparison between results from in vitro and in vivo studies. Finally, in the context of alcohol abuse and dependence, the review proposes potential behavioral contributions by ethanol modulation of plasticity.
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Medina KL, Nagel BJ, Tapert SF. Abnormal cerebellar morphometry in abstinent adolescent marijuana users. Psychiatry Res 2010; 182:152-9. [PMID: 20413277 PMCID: PMC2866789 DOI: 10.1016/j.pscychresns.2009.12.004] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Revised: 12/29/2009] [Accepted: 12/31/2009] [Indexed: 10/19/2022]
Abstract
Functional neuroimaging data from adults have, in general, revealed frontocerebellar dysfunction associated with acute and chronic marijuana (MJ) use. The goal of this study was to characterize cerebellar volume in adolescent chronic MJ users following 1 month of monitored abstinence. Participants were MJ users (n=16) and controls (n=16) aged 16-18 years. Extensive exclusionary criteria included history of psychiatric or neurologic disorders. Drug use history, neuropsychological data, and structural brain scans were collected after 28 days of monitored abstinence. Trained research staff defined cerebellar volumes (including three cerebellar vermis lobes and both cerebellar hemispheres) on high-resolution T1-weighted magnetic resonance images. Adolescent MJ users demonstrated significantly larger inferior posterior (lobules VIII-X) vermis volume than controls, above and beyond effects of lifetime alcohol and other drug use, gender, and intracranial volume. Larger vermis volumes were associated with poorer executive functioning. Following 1 month of abstinence, adolescent MJ users had significantly larger posterior cerebellar vermis volumes than non-using controls. These greater volumes are suggested to be pathological based on linkage to poorer executive functioning. Longitudinal studies are needed to examine typical cerebellar development during adolescence and the influence of marijuana use.
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Affiliation(s)
| | - Bonnie J. Nagel
- Department of Psychiatry, Oregon Health and Science University, Portland, Oregon
| | - Susan F. Tapert
- Department of Psychiatry, University of California, San Diego, California
,VA San Diego Healthcare System, San Diego, California
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41
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Kelm MK, Weinberg RJ, Criswell HE, Breese GR. The PLC/IP 3 R/PKC pathway is required for ethanol-enhanced GABA release. Neuropharmacology 2010; 58:1179-86. [PMID: 20206640 DOI: 10.1016/j.neuropharm.2010.02.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 02/23/2010] [Accepted: 02/24/2010] [Indexed: 12/31/2022]
Abstract
Research on the actions of ethanol at the GABAergic synapse has traditionally focused on postsynaptic mechanisms, but recent data demonstrate that ethanol also increases both evoked and spontaneous GABA release in many brain regions. Using whole-cell voltage-clamp recordings, we previously showed that ethanol increases spontaneous GABA release at the rat interneuron-Purkinje cell synapse. This presynaptic ethanol effect is dependent on calcium release from internal stores, possibly through activation of inositol 1,4,5-trisphosphate receptors (IP(3)Rs). After confirming that ethanol targets vesicular GABA release, in the present study we used electron microscopic immunohistochemistry to demonstrate that IP(3)Rs are located in presynaptic terminals of cerebellar interneurons. Activation of IP(3)Rs requires binding of IP(3), generated through activation of phospholipase C (PLC). We find that the PLC antagonist edelfosine prevents ethanol from increasing spontaneous GABA release. Diacylglycerol generated by PLC and calcium released by activation of the IP(3)R activate protein kinase C (PKC). Ethanol-enhanced GABA release was blocked by two PKC antagonists, chelerythrine and calphostin C. When a membrane impermeable PKC antagonist, PKC (19-36), was delivered intracellularly to the postsynaptic neuron, ethanol continued to increase spontaneous GABA release. Overall, these results suggest that activation of the PLC/IP(3)R/PKC pathway is necessary for ethanol to increase spontaneous GABA release from presynaptic terminals onto Purkinje cells.
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Affiliation(s)
- M Katherine Kelm
- Department of Pharmacology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7365, USA.
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42
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Neuroprotection of ethanol against ischemia/reperfusion-induced brain injury through decreasing c-Jun N-terminal kinase 3 (JNK3) activation by enhancing GABA release. Neuroscience 2010; 167:1125-37. [PMID: 20219637 DOI: 10.1016/j.neuroscience.2010.02.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2009] [Revised: 01/30/2010] [Accepted: 02/09/2010] [Indexed: 01/05/2023]
Abstract
Our latest study indicated that ethanol could attenuate cerebral ischemia/reperfusion-induced brain injury through activating Ionotropic glutamate receptors Kainate Family (Gluk1)-kainate (KA) receptors and gamma-aminobutyric acid (GABA) receptors. However, the possible mechanism of the neuroprotective effects of ethanol remains unclear. In this study we report that ethanol shows neuroprotective effects against ischemic brain injury through enhancing GABA release and then decreasing c-Jun N-terminal kinase 3 (JNK3) activation. Electrophysiologic recording indicated that ethanol enhances GABA release from presynaptic neurons and the released GABA subsequently inhibits the KA receptor-mediated whole-cell currents. Moreover, our data show that ethanol can inhibit the increased assembly of the Gluk2-PSD-95-MLK3 (postsynaptic density protein-95, PSD-95 and mixed-lineage kinase 3, MLK3) module induced by cerebral ischemia and the activation of the MLK3-MKK4/7-JNK (mitogen-activated protein kinase kinase 4/7, MKK4/7) cascade. Pretreatment of the GABA(A) receptor antagonist bicuculline and antagonist of VGCC (a broad-spectrum blocker of the voltage-gated calcium channel [VGCC]) Chromic (CdCl(2)) can demolish the neuroprotective effects of ethanol. The results suggest that during ischemia-reperfusion, ethanol may activate presynaptic Gluk1-KA and facilitate Ca(2+)-dependent GABA release. The released GABA activates postsynaptic GABA(A) receptors, which suppress the ischemic depolarization and decrease the association of signaling module Gluk2-PSD-95-MLK3 induced by the activation of postsynaptic Gluk2-KA receptors. There is a raised possibility that ethanol inhibiting the JNK3 apoptotic pathway (MLK3/MKK4/7/JNK3/c-Jun/Fas-L) performs a neuroprotective function against ischemic brain injury.
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43
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Pessah IN, Cherednichenko G, Lein PJ. Minding the calcium store: Ryanodine receptor activation as a convergent mechanism of PCB toxicity. Pharmacol Ther 2010; 125:260-85. [PMID: 19931307 PMCID: PMC2823855 DOI: 10.1016/j.pharmthera.2009.10.009] [Citation(s) in RCA: 172] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 10/30/2009] [Indexed: 11/24/2022]
Abstract
Chronic low-level polychlorinated biphenyl (PCB) exposures remain a significant public health concern since results from epidemiological studies indicate that PCB burden is associated with immune system dysfunction, cardiovascular disease, and impairment of the developing nervous system. Of these various adverse health effects, developmental neurotoxicity has emerged as a particularly vulnerable endpoint in PCB toxicity. Arguably the most pervasive biological effects of PCBs could be mediated by their ability to alter the spatial and temporal fidelity of Ca2+ signals through one or more receptor-mediated processes. This review will focus on our current knowledge of the structure and function of ryanodine receptors (RyRs) in muscle and nerve cells and how PCBs and related non-coplanar structures alter these functions. The molecular and cellular mechanisms by which non-coplanar PCBs and related structures alter local and global Ca2+ signaling properties and the possible short and long-term consequences of these perturbations on neurodevelopment and neurodegeneration are reviewed.
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Affiliation(s)
- Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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44
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Abstract
There is no specialized alcohol addiction area in the brain; rather, alcohol acts on a wide range of excitatory and inhibitory nervous networks to modulate neurotransmitters actions by binding with and altering the function of specific proteins. With no hemato-encephalic barrier for alcohol, its actions are strongly related to the amount of intake. Heavy alcohol intake is associated with both structural and functional changes in the central nervous system with long-term neuronal adaptive changes contributing to the phenomena of tolerance and withdrawal. The effects of alcohol on the function of neuronal networks are heterogeneous. Because ethanol affects neural activity in some brain sites but is without effect in others, its actions are analyzed in terms of integrated connectivities in the functional circuitry of neuronal networks, which are of particular interest because of the cognitive interactions discussed in the manuscripts contributing to this review. Recent molecular data are reviewed as a support for the other contributions dealing with cognitive disturbances related to alcohol acute and addicted consumption.
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Affiliation(s)
- Claude Tomberg
- Brain Research Unit, Faculty of Medicine and CENOLI, Free University of Brussels, Belgium
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45
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Valenzuela CF, Lindquist B, Zamudio-Bulcock PA. A Review of Synaptic Plasticity at Purkinje Neurons with a Focus on Ethanol-Induced Cerebellar Dysfunction. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2010; 91:339-72. [DOI: 10.1016/s0074-7742(10)91011-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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46
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Ke JB, Chen W, Yang XL, Wang Z. Characterization of spontaneous inhibitory postsynaptic currents in cultured rat retinal amacrine cells. Neuroscience 2010; 165:395-407. [DOI: 10.1016/j.neuroscience.2009.10.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 10/04/2009] [Indexed: 11/29/2022]
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47
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Fleming RL, Manis PB, Morrow AL. The effects of acute and chronic ethanol exposure on presynaptic and postsynaptic gamma-aminobutyric acid (GABA) neurotransmission in cultured cortical and hippocampal neurons. Alcohol 2009; 43:603-18. [PMID: 20004338 DOI: 10.1016/j.alcohol.2009.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 10/07/2009] [Accepted: 10/07/2009] [Indexed: 01/04/2023]
Abstract
Decades after ethanol was first described as a gamma-aminobutyric acid (GABA) mimetic, the precise mechanisms that produce the acute effects of ethanol and the physiological adaptations that underlie ethanol tolerance and dependence remain unclear. Although a substantial body of evidence suggests that ethanol acts on GABAergic neurotransmission to enhance inhibition in the central nervous system, the precise mechanisms underlying the physiological effects of both acute and chronic ethanol exposure are still under investigation. We have used in vitro ethanol exposure followed by recording of miniature inhibitory postsynaptic currents (mIPSCs) to determine whether acute or chronic ethanol exposure directly alters synaptic GABA(A) receptor (GABA(A)R) function or GABA release in cultured cortical and hippocampal neurons. Acute ethanol exposure slightly increased the duration of mIPSCs in hippocampal neurons but did not alter mIPSC kinetics in cortical neurons. Acute ethanol exposure did not change mIPSC frequency in either hippocampal or cortical neurons. One day of chronic ethanol exposure produced a transient decrease in mIPSC duration in cortical neurons but did not alter mIPSC kinetics in hippocampal neurons. Chronic ethanol exposure did not change mIPSC frequency in either hippocampal or cortical neurons. Chronic ethanol exposure also did not produce substantial cross-tolerance to a benzodiazepine in either hippocampal or cortical neurons. The results suggest that ethanol exposure in vitro has limited effects on synaptic GABA(A)R function and action potential-independent GABA release in cultured neurons and that ethanol exposure in cultured cortical and hippocampal neurons may not reproduce all the effects that occur in vivo and in acute brain slices.
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48
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Hirono M, Yamada M, Obata K. Ethanol enhances both action potential-dependent and action potential-independent GABAergic transmission onto cerebellar Purkinje cells. Neuropharmacology 2009; 57:109-20. [PMID: 19426745 DOI: 10.1016/j.neuropharm.2009.04.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 04/14/2009] [Accepted: 04/22/2009] [Indexed: 11/19/2022]
Abstract
Ethanol (EtOH) modulates synaptic efficacy in various brain areas, including the cerebellum, which plays a role in motor coordination. Previous studies have shown that EtOH enhances tonic inhibition of cerebellar granule cells, which is one of the possible reasons for the alcohol-induced motor impairment. However, the effects of EtOH on molecular layer interneurons (MLIs) in the mouse cerebellum have remained unknown. Here we found that MLIs were depolarized by EtOH through enhancement of hyperpolarization-activated cationic currents (I(h)). Under physiological conditions, a low EtOH concentration (3-50 mM) caused a small increase in the firing rate of MLIs, whereas, in the presence of blockers for ionotropic glutamate and GABA receptors, EtOH (>or=10 mM) robustly enhanced MLI firing, suggesting that synaptic inputs, which seem to serve as the phasic inhibition, could suppress the EtOH-mediated excitation of MLIs and Purkinje cells (PCs). Even in the absence of synaptic blockers, a high EtOH concentration (100 mM) markedly increased the firing rate of MLIs to enhance GABAergic transmission. Furthermore, 100 mM EtOH-facilitated miniature IPSCs via a mechanism that depended on intracellular cyclic AMP, voltage-dependent Ca(2+) channels, and intracellular Ca(2+) stores, but was independent of I(h) or PKA. The two distinct effects of a high EtOH concentration (>or=100 mM), however, failed to attenuate the EtOH-induced strong depolarization of MLIs. These results suggest that acute exposure to a low EtOH concentration (<or=50 mM) enhanced GABAergic synaptic transmission, which suppressed the EtOH-evoked excitation of MLIs and PCs, thereby maintaining precise synaptic integration of PCs.
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Affiliation(s)
- Moritoshi Hirono
- Yamada Research Unit, RIKEN Brain Science Institute, Wako, Saitama, Japan.
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49
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Qi SH, Liu Y, Wang WW, Wang M, Zhang GY. Neuroprotection of ethanol against cerebral ischemia/reperfusion induced brain injury through GABA receptor activation. Brain Res 2009; 1276:151-8. [PMID: 19406109 DOI: 10.1016/j.brainres.2009.04.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 04/17/2009] [Accepted: 04/18/2009] [Indexed: 01/14/2023]
Abstract
In this study we investigated whether ethanol could play neuroprotective effects against ischemic brain injury and the related mechanism. Cresyl violet staining results demonstrated that moderate dose of ethanol administered intracerebroventricularly (i.c.v.) had neuroprotective effect against ischemia-reperfusion induced neuronal cell death. Ethanol also inhibited the phosphorylation of JNK3 induced by cerebral ischemia-reperfusion. Three separate drugs, NS3763 (the selective antagonist of GluR5), GluR5 antisense oligodeoxynucleotides (AS-ODNs) and Bicuculline (an antagonist of GABA receptors), were found to inhibit the neuroprotective effect of ethanol. Moreover, the GABA receptor agonist muscimol could attenuate the JNK3 phosphorylation. Taken together, the results suggest that during ischemia-reperfusion ethanol may activate presynaptic GluR5-KA and postsynaptic GABA receptors continuously, and the activation of GABA receptors inhibits the JNK3 signal pathway. The results show a novel potential mechanism underlying ethanol protective effects.
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Affiliation(s)
- Su-Hua Qi
- Research Center for Biochemistry and Molecular Biology and Provincial Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical College, Xuzhou 221002, PR China
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50
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Theile JW, Morikawa H, Gonzales RA, Morrisett RA. Role of 5-hydroxytryptamine2C receptors in Ca2+-dependent ethanol potentiation of GABA release onto ventral tegmental area dopamine neurons. J Pharmacol Exp Ther 2009; 329:625-33. [PMID: 19225162 DOI: 10.1124/jpet.108.147793] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of ventral tegmental area (VTA)-dopaminergic (DA) neurons by ethanol has been implicated in the rewarding and reinforcing actions of ethanol. GABAergic transmission is thought to play an important role in regulating the activity of DA neurons. We have reported previously that ethanol enhances GABA release onto VTA-DA neurons in a brain slice preparation. Because intraterminal Ca(2+) levels regulate neurotransmitter release, we investigated the roles of Ca(2+)-dependent mechanisms in ethanol-induced enhancement of GABA release. Acute ethanol enhanced miniature inhibitory postsynaptic current (mIPSC) frequency in the presence of the nonspecific voltage-gated Ca(2+) channel inhibitor, cadmium chloride, even though basal mIPSC frequency was reduced by cadmium. Conversely, the inositol-1,4,5-triphosphate receptor inhibitor, 2-aminoethoxydiphenylborane, and the sarco/endoplasmic reticulum Ca(2+) ATPase pump inhibitor, cyclopiazonic acid, eliminated the ethanol enhancement of mIPSC frequency. Recent studies suggest that the G protein-coupled receptor, 5-hydroxytryptamine (5-HT)(2C), may modulate GABA release in the VTA. Thus, we also investigated the role of 5-HT(2C) receptors in ethanol enhancement of GABAergic transmission. Application of 5-HT and the 5-HT(2C) receptor agonist, Ro-60-0175 [(alphaS)-6-chloro-5-fluoro-alpha-methyl-1H-indole-1-ethanamine fumarate], alone enhanced mIPSC frequency of which the latter was abolished by the 5-HT(2C) receptor antagonist, SB200646 [N-(1-methyl-5-indoyl)-N-(3-pyridyl)urea hydrochloride], and substantially diminished by cyclopiazonic acid. Furthermore, SB200646 abolished the ethanol-induced increase in mIPSC frequency and had no effect on basal mIPSC frequency. These observations suggest that an increase in Ca(2+) release from intracellular stores via 5-HT(2C) receptor activation is involved in the ethanol-induced enhancement of GABA release onto VTA-DA neurons.
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Affiliation(s)
- Jonathan W Theile
- Cell and Molecular Biology, College of Pharmacy, University of Texas, Austin, TX 78712-0125, USA.
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