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Gyetvai B, Simonyi A, Oros M, Saito M, Smiley J, Vadász C. mGluR7 genetics and alcohol: intersection yields clues for addiction. Neurochem Res 2011; 36:1087-100. [PMID: 21448595 DOI: 10.1007/s11064-011-0452-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/16/2011] [Indexed: 12/19/2022]
Abstract
Development of addiction to alcohol or other substances can be attributed in part to exposure-dependent modifications at synaptic efficacy leading to an organism which functions at an altered homeostatic setpoint. Genetic factors may also influence setpoints and the stability of the homeostatic system of an organism. Quantitative genetic analysis of voluntary alcohol drinking, and mapping of the involved genes in the quasi-congenic Recombinant QTL Introgression strain system, identified Eac2 as a Quantitative Trait Locus (QTL) on mouse chromosome 6 which explained 18% of the variance with an effect size of 2.09 g/kg/day alcohol consumption, and Grm7 as a quantitative trait gene underlying Eac2 [Vadasz et al. in Neurochem Res 32:1099-1112, 100, Genomics 90:690-702, 102]. In earlier studies, the product of Grm7 mGluR7, a G protein-coupled receptor, has been implicated in stress systems [Mitsukawa et al. in Proc Natl Acad Sci USA 102:18712-18717, 63], anxiety-like behaviors [Cryan et al. in Eur J Neurosci 17:2409-2417, 14], memory [Holscher et al. in Learn Mem 12:450-455, 26], and psychiatric disorders (e.g., [Mick et al. in Am J Med Genet B Neuropsychiatr Genet 147B:1412-1418, 61; Ohtsuki et al. in Schizophr Res 101:9-16, 72; Pergadia et al. in Paper presented at the 38th Annual Meeting of the Behavior Genetics Association, Louisville, Kentucky, USA, 76]. Here, in experiments with mice, we show that (1) Grm7 knockout mice express increased alcohol consumption, (2) sub-congenic, and congenic mice carrying a Grm7 variant characterized by higher Grm7 mRNA drink less alcohol, and show a tendency for higher circadian dark phase motor activity in a wheel running paradigm, respectively, and (3) there are significant genetic differences in Grm7 mRNA abundance in the mouse brain between congenic and background mice identifying brain areas whose function is implicated in addiction related processes. We hypothesize that metabotropic glutamate receptors may function as regulators of homeostasis, and Grm7 (mGluR7) is involved in multiple processes (including stress, circadian activity, reward control, memory, etc.) which interact with substance use and the development of addiction. In conclusion, we suggest that mGluR7 is a significant new therapeutic target in addiction and related neurobehavioral disorders.
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Affiliation(s)
- Beatrix Gyetvai
- Laboratory of Neurobehavior Genetics, Nathan S Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
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302
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Yamamoto K, Vernier P. The evolution of dopamine systems in chordates. Front Neuroanat 2011; 5:21. [PMID: 21483723 PMCID: PMC3070214 DOI: 10.3389/fnana.2011.00021] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 03/15/2011] [Indexed: 12/24/2022] Open
Abstract
Dopamine (DA) neurotransmission in the central nervous system (CNS) is found throughout chordates, and its emergence predates the divergence of chordates. Many of the molecular components of DA systems, such as biosynthetic enzymes, transporters, and receptors, are shared with those of other monoamine systems, suggesting the common origin of these systems. In the mammalian CNS, the DA neurotransmitter systems are diversified and serve for visual and olfactory perception, sensory–motor programming, motivation, memory, emotion, and endocrine regulations. Some of the functions are conserved among different vertebrate groups, while others are not, and this is reflected in the anatomical aspects of DA systems in the forebrain and midbrain. Recent findings concerning a second tyrosine hydroxylase gene (TH2) revealed new populations of DA-synthesizing cells, as evidenced in the periventricular hypothalamic zones of teleost fish. It is likely that the ancestor of vertebrates possessed TH2 DA-synthesizing cells, and the TH2 gene has been lost secondarily in placental mammals. All the vertebrates possess DA cells in the olfactory bulb, retina, and in the diencephalon. Midbrain DA cells are abundant in amniotes while absent in some groups, e.g., teleosts. Studies of protochordate DA cells suggest that the diencephalic DA cells were present before the divergence of the chordate lineage. In contrast, the midbrain cell populations have probably emerged in the vertebrate lineage following the development of the midbrain–hindbrain boundary. The functional flexibility of the DA systems, and the evolvability provided by duplication of the corresponding genes permitted a large diversification of these systems. These features were instrumental in the adaptation of brain functions to the very variable way of life of vertebrates.
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Affiliation(s)
- Kei Yamamoto
- Neurobiology and Development (UPR3294), Institute of Neurobiology Alfred Fessard, CNRS Gif-sur-Yvette, France
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303
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Schulte T, Mũller-Oehring EM, Pfefferbaum A, Sullivan EV. Neurocircuitry of emotion and cognition in alcoholism: contributions from white matter fiber tractography. DIALOGUES IN CLINICAL NEUROSCIENCE 2011. [PMID: 21319499 PMCID: PMC3181985 DOI: 10.31887/dcns.2010.12.4/tschulte] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chronic alcoholism is characterized by impaired control over emotionally motivated actions towards alcohol use. Neuropathologically, it is associated with widespread brain structural compromise marked by gray matter shrinkage, ventricular enlargement, and white matter degradation. The extent to which cortical damage itself or cortical disconnection by white matter fiber pathway disruption contribute to deficits in emotion, cognition, and behavior can be investigated with in vivo structural neuroimaging and diffusion tensor imaging (DTI)-based quantitative fiber tracking. Tractography in alcoholism has revealed abnormalities in selective white matter fiber bundles involving limbic fiber tracts (fornix and cingulum) that connect cortico-limbic-striatal nodes of emotion and reward circuits. Studies documenting brain-behavior relationships support the role of alcoholism-related white matter fiber degradation as a substrate of clinical impairment. An understanding of the role of cortico-limbic fiber degradation in emotional dysregulation in alcoholism is now emerging.
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Affiliation(s)
- Tilman Schulte
- Neuroscience Program, SRI International, Menlo Park, California, USA
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304
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Aberrant learning and memory in addiction. Neurobiol Learn Mem 2011; 96:609-23. [PMID: 21376820 DOI: 10.1016/j.nlm.2011.02.014] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 02/01/2011] [Accepted: 02/22/2011] [Indexed: 12/26/2022]
Abstract
Over the past several years, drug addiction has increasingly been accepted to be a disease of the brain as opposed to simply being due to a lack of willpower or personality flaw. Exposure to addictive substances has been shown to create enduring changes in brain structure and function that are thought to underlie the transition to addiction. Specific genetic and environmental vulnerability factors also influence the impact of drugs of abuse on the brain and can enhance the likelihood of becoming an addict. Long-lasting alterations in brain function have been found in neural circuits that are known to be responsible for normal appetitive learning and memory processes and it has been hypothesized that drugs of abuse enhance positive learning and memory about the drug while inhibiting learning about the negative consequences of drug use. Therefore, the addict's behavior becomes increasingly directed towards obtaining and using drugs of abuse, while at the same time developing a poorer ability to stop using, even when the drug is less rewarding or interferes with functioning in other facets of life. In this review we will discuss the clinical evidence that addicted individuals have altered learning and memory and describe the possible neural substrates of this dysfunction. In addition, we will explore the pre-clinical evidence that drugs of abuse cause a progressive disorder of learning and memory, review the molecular and neurobiological changes that may underlie this disorder, determine the genetic and environmental factors that may increase vulnerability to addiction, and suggest potential strategies for treating addiction through manipulations of learning and memory.
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305
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Proctor WR, Dobelis P, Moritz AT, Wu PH. Chronic nicotine treatment differentially modifies acute nicotine and alcohol actions on GABA(A) and glutamate receptors in hippocampal brain slices. Br J Pharmacol 2011; 162:1351-63. [PMID: 21133888 PMCID: PMC3058167 DOI: 10.1111/j.1476-5381.2010.01141.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 11/02/2010] [Accepted: 11/04/2010] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND AND PURPOSE Tobacco and alcohol are often co-abused producing interactive effects in the brain. Although nicotine enhances memory while ethanol impairs it, variable cognitive changes have been reported from concomitant use. This study was designed to determine how nicotine and alcohol interact at synaptic sites to modulate neuronal processes. EXPERIMENTAL APPROACH Acute effects of nicotine, ethanol, and both drugs on synaptic excitatory glutamatergic and inhibitory GABAergic transmission were measured using whole-cell recording in hippocampal CA1 pyramidal neurons from brain slices of mice on control or nicotine-containing diets. KEY RESULTS Acute nicotine (50 nM) enhanced both GABAergic and glutamatergic synaptic transmission; potentiated GABA(A) receptor currents via activation of α7* and α4β2* nAChRs, and increased N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor currents through α7* receptors. While ethanol (80 mM) also increased GABA(A) currents, it inhibited NMDA currents. Although ethanol had no effect on AMPA currents, it blocked nicotine-induced increases in NMDA and AMPA currents. Following chronic nicotine treatment, acute nicotine or ethanol did not affect NMDA currents, while the effects of GABAergic responses were not altered. CONCLUSIONS AND IMPLICATIONS Acute ethanol ingestion selectively attenuated nicotine enhancement of excitatory glutamatergic NMDA and AMPA receptor function, suggesting an overall reduction in excitatory output from the hippocampus. It also indicated that ethanol could decrease the beneficial effects of nicotine on memory performance. In addition, chronic nicotine treatment produced tolerance to the effects of nicotine and cross-tolerance to the effects of ethanol on glutamatergic activity, leading to a potential increase in the use of these drugs.
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306
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Xu L, Scheenen WJJM, Leshan RL, Patterson CM, Elias CF, Bouwhuis S, Roubos EW, Myers MG, Kozicz T. Leptin signaling modulates the activity of urocortin 1 neurons in the mouse nonpreganglionic Edinger-Westphal nucleus. Endocrinology 2011; 152:979-88. [PMID: 21209012 PMCID: PMC3040051 DOI: 10.1210/en.2010-1143] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A recent study systematically characterized the distribution of the long form of the leptin receptor (LepRb) in the mouse brain and showed substantial LepRb mRNA expression in the nonpreganglionic Edinger-Westphal nucleus (npEW) in the rostroventral part of the midbrain. This nucleus hosts the majority of urocortin 1 (Ucn1) neurons in the rodent brain, and because Ucn1 is a potent satiety hormone and electrical lesioning of the npEW strongly decreases food intake, we have hypothesized a role of npEW-Ucn1 neurons in leptin-controlled food intake. Here, we show by immunohistochemistry that npEW-Ucn1 neurons in the mouse contain LepRb and respond to leptin administration with induction of the Janus kinase 2-signal transducer and activator of transcription 3 pathway, both in vivo and in vitro. Furthermore, systemic leptin administration increases the Ucn1 content of the npEW significantly, whereas in mice that lack LepRb (db/db mice), the npEW contains considerably reduced amount of Ucn1. Finally, we reveal by patch clamping of midbrain Ucn1 neurons that leptin administration reduces the electrical firing activity of the Ucn1 neurons. In conclusion, we provide ample evidence for leptin actions that go beyond leptin's well-known targets in the hypothalamus and propose that leptin can directly influence the activity of the midbrain Ucn1 neurons.
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Affiliation(s)
- Lu Xu
- Department of Cellular Animal Physiology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, 6500 GL Nijmegen, The Netherlands
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307
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Kim YB, Matthews M, Moghaddam B. Putative γ-aminobutyric acid neurons in the ventral tegmental area have a similar pattern of plasticity as dopamine neurons during appetitive and aversive learning. Eur J Neurosci 2011; 32:1564-72. [PMID: 21040517 DOI: 10.1111/j.1460-9568.2010.07371.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Dopamine influences affective, motor and cognitive processing, and multiple forms of learning and memory. This multifaceted functionality, which operates across long temporal windows, is broader than the narrow and temporally constrained role often ascribed to dopamine neurons as reward prediction error detectors. Given the modulatory nature of dopamine neurotransmission, that dopamine release is activated by both aversive and appetitive stimuli, and that dopamine receptors are often localized extrasynaptically, a role for dopamine in transmitting precise error signals has been questioned. Here we recorded from ventral tegmental area (VTA) neurons, while exposing rats to novel stimuli that were predictive of an appetitive or aversive outcome in the same behavioral session. The VTA contains dopamine and -aminobutyric acid (GABA) neurons that project to striatal and cortical regions and are strongly implicated in learning and affective processing. The response of VTA neurons, regardless of whether they had putative dopamine or GABA waveforms, transformed flexibly as animals learned to associate novel stimuli from different sensory modalities to appetitive or aversive outcomes. Learning the appetitive association led to larger excitatory VTA responses, whereas acquiring the aversive association led to a biphasic response of brief excitation followed by sustained inhibition. These responses shifted rapidly as outcome contingencies changed. These data suggest that VTA neurons interface sensory information with representational memory of aversive and appetitive events. This pattern of plasticity was not selective for putative dopamine neurons and generalized to other cells, suggesting that the temporally precise information transfer from the VTA may be mediated by faster acting GABA neurons.
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Affiliation(s)
- Yun-Bok Kim
- Department of Neuroscience, University of Pittsburgh, A210 Langley Hall, Pittsburgh, PA 15260, USA
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308
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Strickler AG, Soares D. Comparative genetics of the central nervous system in epigean and hypogean Astyanax mexicanus. Genetica 2011; 139:383-91. [PMID: 21318738 DOI: 10.1007/s10709-011-9557-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 01/27/2011] [Indexed: 02/02/2023]
Abstract
The extreme environment of subterranean caves presents an adaptive challenge to troglobitic organisms. The mechanisms by which natural selection modify an ancestral surface neural circuit to produce a novel subterranean behavior remain a mystery. To address this question, we performed cross species microarray experiments to compare differences in gene expression levels in the adult brain of the teleost Astyanax mexicanus. This species provides a unique opportunity for comparative genetic studies as it consists of extant epigean (surface) and hypogean (cave) conspecifics. Microarray experiments herein revealed significant changes in transcription levels of seventeen genes, several of which are important for behaviors involved in metabolic management. We focused on genes central to three neurotransmission and neuromodulation networks: the endocannabinoid system (Cannabinoid receptor CB1), the dopaminergic system (Tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein) and the glutamatergic system (glutamate receptor AMPA 2a). All three genes were upregulated in the hypogean form of A. mexicanus compared to the epigean form, indicating that behavioral differences in the hypogean form of the species could be due to alterations in expression levels of several key genes. This information provides insights into the complex relationships among environmental factors, genetics, nervous systems and adaptive behavior, and can subsequently help us understand how these interactions affect behavior in other biological systems.
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309
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Alteration of synaptic plasticity in rat dorsal striatum induced by chronic ethanol intake and withdrawal via ERK pathway. Acta Pharmacol Sin 2011; 32:175-81. [PMID: 21293469 DOI: 10.1038/aps.2010.199] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIM The dorsal striatum has been proposed to contribute to the formation of drug-seeking behaviors, leading to excessive and compulsive drug usage, such as addiction. The current study aimed to investigate the involvement of extracellular signal-regulated kinase (ERK) pathway in the modification of striatal synaptic plasticity. METHODS Ethanol was administered to rats in drinking water at concentration of 6% (v/v) for 30 days. Rats were sacrificed on day 10, 20, or 30 during ethanol intake or on withdrawal day 1, 3, or 7 following 30-d ethanol intake. The striata were removed either for electrophysiological recording or for protein immuno-blot analysis. Extracellular recording technique was used to record population spikes (PS) induced by high-frequency stimulation (HFS) in the dorsolateral striatum (DLS). RESULTS Corticostriatal long-term depression (LTD) was determined to be dependent upon ERK signaling. Chronic ethanol intake (CEI) attenuated ERK phosphorylation and LTD induction, whereas withdrawal for one day (W1D) potentiated ERK phosphorylation and LTD induction. These results showed that the impact of chronic ethanol intake and withdrawal on corticostriatal synaptic plasticity was associated with ethanol's effect on ERK phosphorylation. In particular, pharmacological inhibition of ERK hyper-phosphorylation by U0126 prevented LTD induction in the DLS and attenuated ethanol withdrawal syndrome as well. CONCLUSION In rat DLS, chronic ethanol intake and withdrawal altered LTD induction via ERK signaling pathway. Ethanol withdrawal syndrome is mediated, at least partly, by ERK hyper-phosphorylation in the DLS.
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310
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Transcription and protein synthesis inhibitors reduce the induction of behavioural sensitization to a single morphine exposure and regulate Hsp70 expression in the mouse nucleus accumbens. Int J Neuropsychopharmacol 2011; 14:107-21. [PMID: 20519062 DOI: 10.1017/s146114571000057x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
New protein synthesis has been implicated as necessary for long-lasting changes in neuronal function. Behavioural sensitization to a single exposure to addictive drugs is a form of neuroplasticity, but little is known about the importance of new protein synthesis in the underlying mechanism. This study was designed to investigate the effects of the transcription inhibitor actinomycin D (AD) and the protein synthesis inhibitor cycloheximide (CHX) on induction of behavioural sensitization to a single morphine exposure in mice. In combination with behavioural experiments, changes in gene and protein expression in the mouse nucleus accumbens (NAc) were analysed by RT-PCR array and Western blot respectively. Behavioural sensitization was evident in mice pretreated only once with morphine at the doses of 20 and 40 mg/kg, but not 5 and 10 mg/kg. Mice pretreated with morphine (20 mg/kg) and challenged with a lower dose (5 mg/kg) after a period of 4-21 d washout showed sensitized locomotion. At the doses that did not affect locomotion in mice, AD or CHX significantly suppressed hyperactivity induced by acute treatment, but not challenge with morphine, and blocked induction of behavioural sensitization to a single morphine exposure in a dose-related manner. The results from RT-PCR array and Western blot indicated that the changes of Hsp70 expression in the NAc of mice were associated with behavioural sensitization induced by a single morphine exposure. Together, these findings suggest that induction of behavioural sensitization to a single morphine exposure requires new protein synthesis, potentially involving Hsp70 expression in the NAc of mice.
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311
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Mu P, Panksepp J, Schlüter O, Dong Y, Dong Y. Exposure to cocaine alters dynorphin-mediated regulation of excitatory synaptic transmission in nucleus accumbens neurons. Biol Psychiatry 2011; 69:228-35. [PMID: 21030009 PMCID: PMC3790254 DOI: 10.1016/j.biopsych.2010.09.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 08/23/2010] [Accepted: 09/08/2010] [Indexed: 10/18/2022]
Abstract
BACKGROUND Dysregulation of excitatory synaptic input to nucleus accumbens (NAc) medium spiny neurons (MSNs) underlies a key pathophysiology of drug addiction and addiction-associated emotional and motivational alterations. Dynorphin peptides, which exhibit higher affinity to κ type opioid receptors, are upregulated within the NAc upon exposure to cocaine administration, and the increased dynorphin-signaling in the NAc has been critically implicated in negative mood observed in cocaine- or stress-exposed animals. Despite such apparent behavioral significance of the NAc dynorphins, the understanding of how dynorphins regulate excitatory synaptic transmission in the NAc remains incomplete. METHODS We used electrophysiological recording in brain slices to examine the effects of dynorphins on excitatory synaptic transmission in the NAc. RESULTS We focused on two key dynorphins, dynorphin A and B. Our current results show that dynorphin A and B differentially regulated excitatory postsynaptic currents (EPSCs) in NAc MSNs. Whereas perfusions of both dynorphin A and B to NAc slices decreased EPSCs in MSNs, the effect of dynorphin A but not dynorphin B was completely reversed by the κ receptor-selective antagonist nor-binaltorphimine. These results implicate κ receptor-independent mechanisms in dynorphin B-mediated synaptic effects in the NAc. Furthermore, repeated exposure to cocaine (15 mg/kg/day via intraperitoneal injection for 5 days, with 1, 2, or 14 days withdrawal) completely abolished dynorphin A-mediated modulation of EPSCs in NAc MSNs, whereas the effect of dynorphin B remained largely unchanged. CONCLUSIONS Given the quantitatively higher abundance of dynorphin B in the NAc, our present results suggest that the dynorphin B-mediated, κ receptor-independent pathways predominate in the overall effect of dynorphins in cocaine-pretreated animals and potentially in cocaine-induced alterations in mood.
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Affiliation(s)
- Ping Mu
- Program in Neuroscience, Washington State University, Pullman, WA 99164-6520
| | - Jaak Panksepp
- Program in Neuroscience, Washington State University, Pullman, WA 99164-6520
| | - Oliver Schlüter
- Department of Molecular Neurobiology, European Neuroscience Institute, Grisebachstr. 5, 37077 Göttingen, Germany
| | - Yan Dong
- Program in Neuroscience, Washington State University, Pullman, WA 99164-6520
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312
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Pascoli V, Besnard A, Hervé D, Pagès C, Heck N, Girault JA, Caboche J, Vanhoutte P. Cyclic adenosine monophosphate-independent tyrosine phosphorylation of NR2B mediates cocaine-induced extracellular signal-regulated kinase activation. Biol Psychiatry 2011; 69:218-27. [PMID: 21055728 DOI: 10.1016/j.biopsych.2010.08.031] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 08/11/2010] [Accepted: 08/30/2010] [Indexed: 10/18/2022]
Abstract
BACKGROUND Activation of the extracellular signal-regulated kinase (ERK) in the striatum is crucial for long-term behavioral alterations induced by drugs of abuse. In response to cocaine, ERK phosphorylation (i.e., activation) is restricted to medium-sized spiny neurons expressing dopamine D1 receptor (D1R) and depends on a concomitant stimulation of D1R and glutamate N-methyl-D-aspartate receptor (NMDAR). However, the mechanisms responsible for this activation, especially the respective contribution of D1R and NMDAR, remain unknown. METHODS We studied striatal neurons in culture stimulated with D1R agonist and/or glutamate and wild-type or genetically modified mice treated with cocaine. Biochemical, immunohistochemical, and imaging studies were performed. Mice were also subjected to behavioral experiments. RESULTS Stimulation of D1R cannot activate ERK by itself but potentiates glutamate-mediated calcium influx through NMDAR that is responsible for ERK activation. Potentiation of NMDAR by D1R depends on a cyclic adenosine monophosphate-independent signaling pathway, which involves tyrosine phosphorylation of the NR2B subunit of NMDAR by Src family kinases. We also demonstrate that the D1R/Src family kinases/NR2B pathway is responsible for ERK activation by cocaine in vivo. Inhibition of this pathway abrogates cocaine-induced locomotor sensitization and conditioned place preference. CONCLUSIONS Our results show that potentiation of NR2B-containing NMDAR by D1R is necessary and sufficient to trigger cocaine-induced ERK activation. They highlight a new cyclic adenosine monophosphate-independent pathway responsible for the integration of dopamine and glutamate signals by the ERK cascade in the striatum and for long-term behavioral alterations induced by cocaine.
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Affiliation(s)
- Vincent Pascoli
- Centre National de la Recherché Scientifique Unité Mixte de Recherche, Paris, France
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313
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Piri M, Zarrindast M. Nitric oxide in the ventral tegmental area is involved in retrieval of inhibitory avoidance memory by nicotine. Neuroscience 2011; 175:154-61. [DOI: 10.1016/j.neuroscience.2010.11.059] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 11/29/2010] [Accepted: 11/30/2010] [Indexed: 11/25/2022]
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314
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Pastor V, Host L, Zwiller J, Bernabeu R. Histone deacetylase inhibition decreases preference without affecting aversion for nicotine. J Neurochem 2011; 116:636-45. [PMID: 21166804 DOI: 10.1111/j.1471-4159.2010.07149.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Epigenetic mechanisms have recently been shown to be involved in the long-term effects of drugs of abuse. A well described epigenetic mechanism modulating transcriptional activity consists in the binding to DNA of methyl-CpG binding proteins, such as MeCP2, recruiting histone deacetylases (HDACs). Nicotine causes long-term changes in the brain, but little is known concerning the mechanisms involved in nicotine-preference. Using a nicotine-conditioned place preference protocol, we demonstrate here that the histone deacetylase inhibitor phenylbutyrate was able to dramatically reduce the preference for nicotine, without altering the aversive properties of the drug. We measured immunohistochemically the acetylation of lysine-9 of histone H3, and the expression of phosphorylated cAMP-response element-binding protein, HDAC2 and methyl-CpG-binding protein 2 in the striatum and prefrontal cortex of rats displaying nicotine-preference or aversion and treated with phenylbutyrate. We show that, at the dose administered, the inhibitor was effective in inhibiting HDAC activity. The data suggest that phosphorylated cAMP-response element-binding protein participates in the establishment of conditioned place preference, but not in the reduction of nicotine-preference in response to phenylbutyrate. Moreover, striatal expression of HDAC2 in response to phenylbutyrate mirrored the behavioral effects of the inhibitor, suggesting that HDAC2 is involved in promoting synaptic plasticity underlying the preference for nicotine.
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Affiliation(s)
- Veronica Pastor
- Departamento de Fisiología e Instituto de Biología Celular, Universidad de Buenos Aires, Buenos Aires, Argentina
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315
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Response to methadone maintenance treatment is associated with the MYOCD and GRM6 genes. Mol Diagn Ther 2011; 14:171-8. [PMID: 20560679 DOI: 10.1007/bf03256370] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND There is increasing interest in the pharmacogenetic basis for explaining differences between patients in treatment outcome among methadone-treated subjects. Most studies have focused on genetic polymorphisms related to methadone pharmacokinetics and, to a lesser extent, those genes implicated in the pharmacodynamics of methadone. OBJECTIVE This study aimed to investigate the associations between response to methadone maintenance treatment (MMT) and polymorphisms in genes coding for the OPRM1 opioid receptor, the metabotropic glutamate receptors GRM6 and GRM8, the nuclear receptor NR4A2, the photolyase enzyme cryptochrome 1 (CRY1), and the transcription factor myocardin (MYOCD), which have previously been associated with the risk of opioid dependence disorder. METHODS The study used an association, case-control design, conducted in the setting of an MMT program in a drug abuse outpatient center in Barcelona, Spain. We recruited 169 opioid-dependent patients (diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders [4th Edition] criteria) receiving MMT. The inclusion criteria included Caucasian ethnicity, being enrolled in MMT for at least 6 months, and receiving a stable methadone dose for the previous 2 months. The exclusion criteria included language-related barriers, severe cognitive impairment, or any medical disorder that would interfere with the research assessments. Single nucleotide polymorphism (SNP) variants in several candidate genes and regions were genotyped: MYOCD (rs1714984), GRM8 (rs1034576), CRY1 (rs1861591), GRM6 (rs953741), OPRM1 (rs1074287), NR4A2 (rs1405735), and the intergenic variants rs965972 (1q31.2) and rs1867898 (2q21.2). MMT response status was assessed by the number of opioid-positive controls detected by random urinalysis in the previous 2 months. We used the chi-squared test and p-value for the allele frequencies of the eight SNPs in responders versus nonresponders, and multivariate logistic regression analyses to examine associations between genotypes in the responder and ronresponder groups under codominant, dominant, and recessive models of inheritance. RESULTS A final sample of 116 opioid-dependent patients were included and classified as methadone responders (n = 83) and nonresponders (n = 33), according to illicit opioid use detection in random urinalysis. The responders and nonresponders showed similar demographic and clinical characteristics. All SNPs were in Hardy-Weinberg equilibrium. Subjects carrying the AA genotype at rs1861591 (CRY1; Chr 12: 105941056 G>A) had a higher risk of being nonresponders (odds ratio [OR] = 2.99; 95% CI 1.14, 7.85; p = 0.035), although this difference disappeared with multiple testing corrections. Patients carrying the A allele at rs1714984 (MYOCD; Chr 17: 12558425 G>A) had an increased risk of being nonresponders only if they were also carriers of the AG genotype at rs953741 (GRM6; Chr5: 178262451 A>G) [OR = 10.83; 95% CI 2.52, 46.66; p = 0.006]. CONCLUSIONS A positive association was observed between response to methadone and two variants in the genes MYOCD and GRM6. A pharmacogenetic epistatic effect between SNPs in MYOCD and GRM6 appears to modulate inter-individual variations in MMT response.
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Ondracek JM, Willuhn I, Steiner H, West AR. Interactions between Procedural Learning and Cocaine Exposure Alter Spontaneous and Cortically Evoked Spike Activity in the Dorsal Striatum. Front Neurosci 2011; 4:206. [PMID: 21228909 PMCID: PMC3017361 DOI: 10.3389/fnins.2010.00206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Accepted: 12/15/2010] [Indexed: 11/13/2022] Open
Abstract
We have previously shown that cocaine enhances gene regulation in the sensorimotor striatum associated with procedural learning in a running-wheel paradigm. Here we assessed whether cocaine produces enduring modifications of learning-related changes in striatal neuron activity, using single-unit recordings in anesthetized rats 1 day after the wheel training. Spontaneous and cortically evoked spike activity was compared between groups treated with cocaine or vehicle immediately prior to the running-wheel training or placement in a locked wheel (control conditions). We found that wheel training in vehicle-treated rats increased the average firing rate of spontaneously active neurons without changing the relative proportion of active to quiescent cells. In contrast, in rats trained under the influence of cocaine, the proportion of spontaneously firing to quiescent cells was significantly greater than in vehicle-treated, trained rats. However, this effect was associated with a lower average firing rate in these spontaneously active cells, suggesting that training under the influence of cocaine recruited additional low-firing cells. Measures of cortically evoked activity revealed a second interaction between cocaine treatment and wheel training, namely, a cocaine-induced decrease in spike onset latency in control rats (locked wheel). This facilitatory effect of cocaine was abolished when rats trained in the running wheel during cocaine action. These findings highlight important interactions between cocaine and procedural learning, which act to modify population firing activity and the responsiveness of striatal neurons to excitatory inputs. Moreover, these effects were found 24 h after the training and last drug exposure indicating that cocaine exposure during the learning phase triggers long-lasting changes in synaptic plasticity in the dorsal striatum. Such changes may contribute to the transition from recreational to habitual or compulsive drug taking behavior.
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Affiliation(s)
- Janie M Ondracek
- Department of Cellular and Molecular Pharmacology, The Chicago Medical School/Rosalind Franklin University of Medicine and Science North Chicago, IL, USA
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317
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Moussawi K, Zhou W, Shen H, Reichel CM, See RE, Carr DB, Kalivas PW. Reversing cocaine-induced synaptic potentiation provides enduring protection from relapse. Proc Natl Acad Sci U S A 2011; 108:385-90. [PMID: 21173236 PMCID: PMC3017187 DOI: 10.1073/pnas.1011265108] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cocaine addiction remains without an effective pharmacotherapy and is characterized by an inability of addicts to inhibit relapse to drug use. Vulnerability to relapse arises from an enduring impairment in cognitive control of motivated behavior, manifested in part by dysregulated synaptic potentiation and extracellular glutamate homeostasis in the projection from the prefrontal cortex to the nucleus accumbens. Here we show in rats trained to self-administer cocaine that the enduring cocaine-induced changes in synaptic potentiation and glutamate homeostasis are mechanistically linked through group II metabotropic glutamate receptor signaling. The enduring cocaine-induced changes in measures of cortico-accumbens synaptic and glial transmission were restored to predrug parameters for at least 2 wk after discontinuing chronic treatment with the cystine prodrug, N-acetylcysteine. N-acetylcysteine produced these changes by inducing an enduring restoration of nonsynaptic glutamatergic tone onto metabotropic glutamate receptors. The long-lasting pharmacological restoration of cocaine-induced glutamatergic adaptations by chronic N-acetylcysteine also caused enduring inhibition of cocaine-seeking in an animal model of relapse. These data mechanistically link nonsynaptic glutamate to cocaine-induced adaptations in excitatory transmission and demonstrate a mechanism to chronically restore prefrontal to accumbens transmission and thereby inhibit relapse in an animal model.
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Affiliation(s)
| | - Wenhua Zhou
- Departments of Neurosciences and
- Laboratory of Behavioral Neuroscience, Ningbo Addiction Research and Treatment Center, Ningbo University, Ningbo 315000, People's Republic of China
| | | | | | | | | | - Peter W. Kalivas
- Departments of Neurosciences and
- Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC 29425; and
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318
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Brennan CH, Parmar A, Kily LK, Ananthathevan A, Doshi A, Patel S. Conditioned Place Preference Models of Drug Dependence and Relapse to Drug Seeking: Studies with Nicotine and Ethanol. NEUROMETHODS 2011. [DOI: 10.1007/978-1-60761-922-2_7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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319
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Veeneman MMJ, Boleij H, Broekhoven MH, Snoeren EMS, Guitart Masip M, Cousijn J, Spooren W, Vanderschuren LJMJ. Dissociable roles of mGlu5 and dopamine receptors in the rewarding and sensitizing properties of morphine and cocaine. Psychopharmacology (Berl) 2011; 214:863-76. [PMID: 21120457 PMCID: PMC3063544 DOI: 10.1007/s00213-010-2095-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 11/03/2010] [Indexed: 02/07/2023]
Abstract
RATIONALE Drugs of abuse are initially used because of their rewarding properties. As a result of repeated drug exposure, sensitization to certain behavioral effects of drugs occurs, which may facilitate the development of addiction. Recent studies have implicated the metabotropic glutamate receptor 5 (mGlu5 receptor) in drug reward, but its role in sensitization is unclear. Stimulation of dopamine receptors plays an important role in drug reward, but not in the sensitizing properties of cocaine and morphine. OBJECTIVE This study aims to evaluate the role of mGlu5 and dopamine receptors in the development of cocaine- and morphine-induced conditioned place preference (CPP) and psychomotor sensitization. MATERIALS AND METHODS Rats were treated with the mGlu5 receptor antagonist MTEP (0, 1, 3, and 10 mg/kg, i.p.) or the dopamine receptor antagonist α-flupenthixol (0, 0.125, 0.25, and 0.5 mg/kg, i.p.) during place conditioning with either morphine (3 mg/kg, s.c.) or cocaine (15 mg/kg, i.p.). Furthermore, MTEP (1 mg/kg, i.p.) or α-flupenthixol (0.5 mg/kg, i.p.) was co-administered during cocaine (30 mg/kg, i.p.) or morphine (3.0 mg/kg, s.c.) pretreatment and psychomotor sensitization was tested 3 weeks post-treatment. RESULTS MTEP attenuated the development of morphine- but not cocaine-induced CPP. In contrast, MTEP suppressed the development of cocaine- but not morphine-induced psychomotor sensitization. α-Flupenthixol blocked the development of both cocaine- and morphine-induced CPP but did not affect the development of sensitization to either drug. CONCLUSION Dopamine receptor stimulation mediates cocaine and morphine reward but not sensitization. In contrast, the role of mGlu5 receptors in reward and sensitization is drug-specific.
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Affiliation(s)
- M. M. J. Veeneman
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - H. Boleij
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - M. H. Broekhoven
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - E. M. S. Snoeren
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - M. Guitart Masip
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - J. Cousijn
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - W. Spooren
- F. Hoffmann-La Roche, CNS-DTA, Translational Medicine, Basel, Switzerland
| | - L. J. M. J. Vanderschuren
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands ,Department of Animals in Science and Society, Division of Behavioural Neuroscience, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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320
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Morphine induces AMPA receptor internalization in primary hippocampal neurons via calcineurin-dependent dephosphorylation of GluR1 subunits. J Neurosci 2010; 30:15304-16. [PMID: 21068335 DOI: 10.1523/jneurosci.4255-10.2010] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Chronic morphine treatment resulting in the alteration of postsynaptic levels of AMPA receptors, thereby modulating synaptic strength, has been reported. However, the mechanism underlying such drug-induced synaptic modification has not been resolved. By monitoring the GluR1 trafficking in primary hippocampal neurons using the pHluorin-GluR1 imaging and biotinylation studies, we observed that prolonged morphine exposure significantly induced loss of synaptic and extrasynaptic GluR1 by internalization. The morphine-induced GluR1 endocytosis was independent of neural network activities or NMDA receptor activities, as neither blocking the sodium channels with tetrodotoxin nor NMDA receptors with dl-APV altered the effects of morphine. Instead, morphine-induced GluR1 endocytosis is attributed to a change in the phosphorylation state of the GluR1 at Ser(845) as morphine significantly decreased the dephosphorylation of GluR1 at this site. Such changes in Ser(845) phosphorylation required morphine-induced activation of calcineurin, based on the observations that a calcineurin inhibitor, FK506, completely abrogated the dephosphorylation, and morphine treatment led to an increase in calcineurin enzymatic activity, even in the presence of dl-APV. Importantly, pretreatment with FK506 and overexpression of the GluR1 mutants, S845D (phospho-mimic) or S845A (phospho-blocking) attenuated the morphine-induced GluR1 endocytosis. Therefore, the calcineurin-mediated GluR1-S845 dephosphorylation is critical for the morphine-induced changes in the postsynaptic AMPA receptor level. Together, these findings reveal a novel molecular mechanism for opioid-induced neuronal adaptation and/or synaptic impairment.
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321
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Ma YY, Yu P, Guo CY, Cui CL. Effects of ifenprodil on morphine-induced conditioned place preference and spatial learning and memory in rats. Neurochem Res 2010; 36:383-91. [PMID: 21152977 DOI: 10.1007/s11064-010-0342-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/19/2010] [Indexed: 11/29/2022]
Abstract
Drug addiction, as well as learning and memory, share common mechanisms in terms of neural circuits and intracellular signaling pathways. In the present study, the role of N-methyl-D-aspartate (NMDA) receptors, particularly those containing NR2B subunits, in morphine-induced conditioned place preference (CPP) and Morris water maze (MWM) learning and memory task was investigated. CPP was used as a paradigm for assessing the rewarding effect of morphine, and MWM was used to measure spatial learning and memory in male Sprague-Dawley rats. We found that ifenprodil, an antagonist highly selective for NR2B-containing NMDA receptors, dose-dependently blocked the development, maintenance and reinstatement of morphine-induced CPP, without evident impairment of the acquisition and retrieval of spatial memory in the MWM task. However, the consolidation of spatial memory was disrupted by a high dose (10 mg/kg) of ifenprodil. These results clearly demonstrate that NR2B-containing NMDA receptors are actively involved in addiction memory induced by morphine conditioning, but not in the acquisition and retrieval of spatial learning and memory. In conclusion, NR2B-containing NMDA receptors can be considered potential targets for the treatment of opiate addiction.
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Affiliation(s)
- Yao-Ying Ma
- Neuroscience Research Institute, Department of Neurobiology, School of Basic Medical Sciences, Peking University, 38 Xueyuan Road, 100083, Beijing, People's Republic of China
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322
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Comparative neuroscience of stimulant-induced memory dysfunction: role for neurogenesis in the adult hippocampus. Behav Pharmacol 2010; 21:379-93. [PMID: 20700045 DOI: 10.1097/fbp.0b013e32833e16b6] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The discovery that the addictive drugs impair neurogenesis in the adult hippocampus has prompted the elaboration of new biological hypotheses to explain addiction and drug-induced cognitive dysfunction. Considerable evidence now implicates the process of adult neurogenesis in at least some critical components of hippocampal-dependent memory function. In experimental models, psychomotor stimulant drugs produce alterations in the rate of birth, survival, maturation and functional integration of adult-born hippocampal neurons. Thus some of the deleterious consequences of drug abuse on memory could result from the neurotoxic actions of drugs on adult hippocampal neurogenesis. In this review, we will first summarize preclinical and clinical literature on the disruptive effects of drugs such as cocaine and ecstasy in the areas of learning, memory and attention. We will also summarize data that document the widespread effects of stimulant drugs on progenitor activity and precursor incorporation in the adult dentate gyrus. Finally, we will examine evidence that supports the involvement of hippocampal neurogenesis in specific aspects of learning and memory function and we will consider critically the hypothesis that some of the negative consequences of drug abuse on cognition might be ascribed to deficits in adult hippocampal neurogenesis. Evidence suggests that stimulant abuse impacts negatively on at least four areas of memory/cognitive function that may be influenced by adult hippocampal neurogenesis: contextual memory, spatial memory, working memory and cognitive flexibility.
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323
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Role for mammalian target of rapamycin complex 1 signaling in neuroadaptations underlying alcohol-related disorders. Proc Natl Acad Sci U S A 2010; 107:20093-8. [PMID: 21041654 DOI: 10.1073/pnas.1005554107] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Alcohol addiction is a chronically relapsing disorder that includes certain maladaptive learning and memory. The serine and threonine kinase complex, mammalian target of rapamycin complex 1 (mTORC1), has been implicated in synaptic plasticity, learning, and memory by controlling protein translation. Here we show that administration of alcohol and excessive voluntary consumption of alcohol induce the activation of the mTORC1-mediated signaling pathway in the nucleus accumbens (NAc) of rodents. We further show that the protein expression levels of GluR1 and Homer, two synaptic proteins whose translation has been shown to be modulated by mTORC1, are up-regulated in the NAc of rodents with a history of excessive alcohol consumption. In addition, our results document that the Food and Drug Administration-approved inhibitor of mTORC1, rapamycin, decreases expression of alcohol-induced locomotor sensitization and place preference, as well as excessive alcohol intake and seeking in preclinical rodent models of alcohol abuse. Together, our results suggest that mTORC1 within the NAc is a contributor to molecular mechanisms underlying alcohol-drinking behaviors. Furthermore, despite its massive health and socioeconomic impact worldwide, pharmacotherapies for alcohol abuse and addiction remain limited. Our data therefore put forward the possibility that targeting the mTORC1 signaling cascade is an innovative and valuable strategy for the treatment of alcohol use and abuse disorders.
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324
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Liu F, Jiang H, Zhong W, Wu X, Luo J. Changes in ensemble activity of hippocampus CA1 neurons induced by chronic morphine administration in freely behaving mice. Neuroscience 2010; 171:747-59. [PMID: 20888400 DOI: 10.1016/j.neuroscience.2010.09.052] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 09/08/2010] [Accepted: 09/17/2010] [Indexed: 11/24/2022]
Abstract
The hippocampus plays an important role in the formation of new memories and spatial navigation. Recently, growing evidence supports the view that it is also involved in addiction to opiates and other drugs. Theoretical and experimental studies suggest that hippocampal neural-network oscillations at specific frequencies and unit firing patterns reflect information of learning and memory encoding. Here, using multichannel recordings from the hippocampal CA1 area in behaving mice, we investigated the phase correlations between the theta (4-10 Hz) and gamma (40-100 Hz) oscillations, and the timing of spikes modulated by these oscillations. Local field potentials and single unit recordings in the CA1 area of mice receiving chronic morphine treatment revealed that the power of the theta rhythm was strongly increased; at the same time, the theta frequency during different behavioral states shifted markedly, and the characteristic coupling of theta and gamma oscillations was altered. Surprisingly, though the gamma oscillation frequency changed, the power of gamma lacking theta did not. Moreover, the timing of pyramidal cell spikes relative to the theta rhythm and the timing of interneuron spikes relative to the gamma rhythm changed during chronic morphine administration. Furthermore, these responses were impaired by a selective D1/D5 receptor antagonist intra-hippocampus injection. These results indicate that chronic morphine administration induced the changes of ensemble activity in the CA1 area, and these changes were dependent on local dopamine receptor activation.
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Affiliation(s)
- F Liu
- Department of Neurobiology, Institute of Neuroscience, Zhejiang University School of Medicine, 388 Yu Hang Tang Road, Hangzhou 310058, PR China
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325
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Abstract
Drug addiction is marked by continued drug-seeking behavior despite deleterious consequences and a heightened propensity to relapse not withstanding long, drug-free periods. The enduring nature of addiction has been hypothesized to arise from perturbations in intracellular signaling, gene expression, and brain circuitry induced by substance abuse. Ameliorating some of these aberrations should abate behavioral and neurochemical markers associated with an 'addiction phenotype'. This review summarizes data showing that protein expression and signaling through the nonreceptor activator of G-protein signaling 3 (AGS3) are altered by commonly abused substances in rat and in in-vitro addiction models. AGS3 structure and function are unrelated to the more broadly studied regulator of G-protein signaling family. Thus, the unique role of AGS3 is the focus of this review. Intriguingly, AGS3 protein changes persist into drug abstinence. Accordingly, studies probing the role of AGS3 in the neurochemistry of drug-seeking behavior and relapse are studied in detail. To illuminate this study, AGS3 structure, cellular localization, and function are covered so that an idealized AGS3-targeted pharmacotherapy can be proposed.
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Affiliation(s)
- Michael Scott Bowers
- Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA.
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326
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Van den Oever MC, Lubbers BR, Goriounova NA, Li KW, Van der Schors RC, Loos M, Riga D, Wiskerke J, Binnekade R, Stegeman M, Schoffelmeer ANM, Mansvelder HD, Smit AB, De Vries TJ, Spijker S. Extracellular matrix plasticity and GABAergic inhibition of prefrontal cortex pyramidal cells facilitates relapse to heroin seeking. Neuropsychopharmacology 2010; 35:2120-33. [PMID: 20592718 PMCID: PMC3055295 DOI: 10.1038/npp.2010.90] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Successful treatment of drug addiction is hampered by high relapse rates during periods of abstinence. Neuroadaptation in the medial prefrontal cortex (mPFC) is thought to have a crucial role in vulnerability to relapse to drug seeking, but the molecular and cellular mechanisms remain largely unknown. To identify protein changes that contribute to relapse susceptibility, we investigated synaptic membrane fractions from the mPFC of rats that underwent 21 days of forced abstinence following heroin self-administration. Quantitative proteomics revealed that long-term abstinence from heroin self-administration was associated with reduced levels of extracellular matrix (ECM) proteins. After extinction of heroin self-administration, downregulation of ECM proteins was also present in the mPFC, as well as nucleus accumbens (NAc), and these adaptations were partially restored following cue-induced reinstatement of heroin seeking. In the mPFC, these ECM proteins are condensed in the perineuronal nets that exclusively surround GABAergic interneurons, indicating that ECM adaptation might alter the activity of GABAergic interneurons. In support of this, we observed an increase in the inhibitory GABAergic synaptic inputs received by the mPFC pyramidal cells after the re-exposure to heroin-conditioned cues. Recovering levels of ECM constituents by metalloproteinase inhibitor treatment (FN-439; i.c.v.) prior to a reinstatement test attenuated subsequent heroin seeking, suggesting that the reduced synaptic ECM levels during heroin abstinence enhanced sensitivity to respond to heroin-conditioned cues. We provide evidence for a novel neuroadaptive mechanism, in which heroin self-administration-induced adaptation of the ECM increased relapse vulnerability, potentially by augmenting the responsivity of mPFC GABAergic interneurons to heroin-associated stimuli.
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Affiliation(s)
- Michel C Van den Oever
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, VU University Amsterdam, The Netherlands.
| | - Bart R Lubbers
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - Natalia A Goriounova
- Department of Integrative Neurophysiology, Center for Neurogenomics & Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - Ka W Li
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - Roel C Van der Schors
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - Maarten Loos
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - Danai Riga
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - Joost Wiskerke
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - Rob Binnekade
- Department of Anatomy and Neurosciences, VU Medical Center, Amsterdam, The Netherlands
| | - M Stegeman
- Department of Anatomy and Neurosciences, VU Medical Center, Amsterdam, The Netherlands
| | | | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics & Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - August B Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
| | - Taco J De Vries
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands,Department of Anatomy and Neurosciences, VU Medical Center, Amsterdam, The Netherlands
| | - Sabine Spijker
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, VU University Amsterdam, Amsterdam, The Netherlands
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327
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Liu Y, von Deneen KM, Kobeissy FH, Gold MS. Food addiction and obesity: evidence from bench to bedside. J Psychoactive Drugs 2010; 42:133-45. [PMID: 20648909 DOI: 10.1080/02791072.2010.10400686] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Obesity has become a major health problem and epidemic. However, much of the current debate has been fractious and etiologies of obesity have been attributed to eating behavior or fast food, personality issues, depression, addiction, or genetics. One of the interesting new hypotheses for epidemic obesity is food addiction, which is associated with both substance-related disorder and eating disorder. Accumulating evidences have shown that there are many shared neural and hormonal pathways as well as distinct differences that may help researchers find why certain individuals overeat and become obese. Functional neuroimaging studies have further revealed that good or great smelling, looking, tasting, and reinforcing food has characteristics similar to that of drugs of abuse. Many of the brain changes reported for hedonic eating and obesity are also seen in various forms of addictions. Most importantly, overeating and obesity may have an acquired drive like drug addiction with respect to motivation and incentive; craving, wanting, and liking occur after early and repeated exposures to stimuli. The acquired drive for great food and relative weakness of the satiety signal would cause an imbalance between the drive and hunger/reward centers in the brain and their regulation.
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Affiliation(s)
- Yijun Liu
- Division of Global Tobacco, Alcohol, Obesity & Health Research, University of Florida, Department of Psychiatry and McKnight Brain Institute, PO Box 100256, Gainesville, FL 32610-0256, USA.
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328
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Gastambide F, Lepousez G, Viollet C, Loudes C, Epelbaum J, Guillou JL. Cooperation between hippocampal somatostatin receptor subtypes 4 and 2: functional relevance in interactive memory systems. Hippocampus 2010; 20:745-57. [PMID: 19623609 DOI: 10.1002/hipo.20680] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The hippocampal somatostatin (sst) receptor subtype 4 (sst(4)) modulates memory formation by diminishing hippocampus-based spatial function while enhancing striatum-dependent behaviors. sst(4)-mediated regulations on neuronal activity in the hippocampus appear to depend on both competitive and cooperative interactions with sst receptor subtype 2 (sst(2)). Here, we investigated whether interactions with sst(2) receptors are required for sst(4)-mediated effects on hippocampus-dependent spatial memory and striatum-dependent cued memory in a water maze paradigm. Competition was assessed in mice by intrahippocampal injections of the sst(4) agonist L-803,087 alone or combined with sst(2) agonists (L-779,976 or octreotide). Effects of L-803,087 were also tested in sst(2) knockout mice to assess for receptor cooperation. Finally, sst(2a) and sst(4) localizations within hippocampal subregions were analyzed by immunohistochemistry and expression levels of sst(2a) and sst(2b) were quantified by real-time qPCR. Hippocampal injections of L-803,087 impaired spatial memory but enhanced cued memory. The latter effect was lost not only in sst(2) knockout mice but also in the presence of sst(2) agonists, whereas the former effect remained unaffected by sst(2) agonists or gene deletion. Octreotide and L-779,976 did not yield memory effects but reduced swim velocity throughout the acquisition trials suggesting that stimulation of sst(2) affected motivation and/or anxiety. sst(2a) and sst(4) were respectively detected in the dentate gyrus (DG) and the CA1 subfield suggesting that their functional interactions are not mediated by direct receptor coupling. Hippocampus sst(2a) expression was 36-fold higher than sst(2b). Possible neural mechanisms and functional significances for interaction between memory systems in relationship with stress-induced changes in hippocampal functions are discussed.
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Affiliation(s)
- François Gastambide
- Centre de Neurosciences Intégratives et Cognitives, Université de Bordeaux, Talence, France
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AMPA receptor synaptic plasticity induced by psychostimulants: the past, present, and therapeutic future. Neuron 2010; 67:11-24. [PMID: 20624588 DOI: 10.1016/j.neuron.2010.06.004] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/20/2010] [Indexed: 11/20/2022]
Abstract
Experience-dependent plasticity at excitatory synapses of the mesocorticolimbic system is a fundamental brain mechanism that enables adaptation to an ever-changing environment. These synaptic responses are critical for the planning and execution of adaptive behaviors that maximize survival. The mesocorticolimbic system mediates procurement of positive reinforcers such as food and sex; however, drugs of abuse resculpt this crucial circuitry to promote compulsive drug-seeking behavior. This review will discuss the long-term changes in glutamatergic neurotransmission that occur within the mesolimbic system following cocaine exposure. In addition, we will examine how these long-lasting neuroadaptations may drive the pathology of psychostimulant addiction. Finally, we review clinical trials that highlight antagonists at excitatory AMPA receptors as promising targets against cocaine abuse.
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330
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Bebawy D, Marquez P, Samboul S, Parikh D, Hamid A, Lutfy K. Orphanin FQ/nociceptin not only blocks but also reverses behavioral adaptive changes induced by repeated cocaine in mice. Biol Psychiatry 2010; 68:223-30. [PMID: 20359694 PMCID: PMC2896563 DOI: 10.1016/j.biopsych.2010.02.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2009] [Revised: 02/02/2010] [Accepted: 02/09/2010] [Indexed: 01/04/2023]
Abstract
BACKGROUND Orphanin FQ/nociceptin (OFQ/N), the endogenous ligand of the opioid receptor-like (ORL1) receptor, blocks cocaine sensitization in rats. In this study, we tested whether OFQ/N would block sensitization to the motor stimulatory and conditioned rewarding actions of cocaine in mice. We also examined whether OFQ/N, given to cocaine-sensitized mice, would reverse the sensitized response and whether it would prevent the amplified sensitized response induced by a second cocaine-sensitizing regimen in sensitized mice. METHODS ORL1 knockout and wild-type mice were treated with saline or OFQ/N before saline or cocaine on Days 1-3 and tested for sensitization on Day 8. Additionally, wild-type mice were treated similarly but tested for the conditioned rewarding action of cocaine, in which mice were tested for place preference before and after single conditioning with cocaine. Furthermore, mice were rendered sensitized, treated with saline or OFQ/N before saline or cocaine on Days 13-15, and received cocaine on Day 20 to test whether OFQ/N would reverse sensitization or block the amplified sensitized response induced by a second cocaine-sensitizing regimen in sensitized mice. RESULTS OFQ/N blocked cocaine-induced psychomotor sensitization in wild-type but not knockout mice. It also blocked sensitization to the conditioned rewarding action of cocaine and reversed a preexisting locomotor sensitized response. Furthermore, OFQ/N prevented the amplified sensitized response that developed following a second cocaine sensitizing regimen given to sensitized mice. CONCLUSIONS These results illustrate that OFQ/N not only blocks but also reverses maladaptive behavioral changes induced by repeated cocaine treatment in mice.
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Affiliation(s)
- David Bebawy
- Dept. of Pharm. Sci., Col of Pharmacy, Western Univ. of Health Sci., Pomona, CA 91766
| | - Paul Marquez
- Dept. of Pharm. Sci., Col of Pharmacy, Western Univ. of Health Sci., Pomona, CA 91766
| | - Seroje Samboul
- Dept. of Pharm. Sci., Col of Pharmacy, Western Univ. of Health Sci., Pomona, CA 91766
| | - Drupad Parikh
- Dept. of Pharm. Sci., Col of Pharmacy, Western Univ. of Health Sci., Pomona, CA 91766
| | - Abdul Hamid
- Dept. of Endocrinology, Charles Drew Univ. of Medicine; Los Angeles, CA, 90059, USA
| | - Kabirullah Lutfy
- Dept. of Pharm. Sci., Col of Pharmacy, Western Univ. of Health Sci., Pomona, CA 91766
- Dept. of Endocrinology, Charles Drew Univ. of Medicine; Los Angeles, CA, 90059, USA
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331
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Persistent gene expression changes in ventral tegmental area of adolescent but not adult rats in response to chronic nicotine. Neuroscience 2010; 170:503-13. [PMID: 20633606 DOI: 10.1016/j.neuroscience.2010.06.071] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 06/18/2010] [Accepted: 06/25/2010] [Indexed: 01/20/2023]
Abstract
Because adolescent brains are undergoing extensive developmental changes, they may be uniquely sensitive to effects of addictive drugs like nicotine. We exposed adolescent and adult rats to nicotine infusion for two weeks, and then used whole genome microarray analysis to determine effects on gene expression in the ventral tegmental area. We examined brains immediately after two weeks of nicotine or saline, and also four weeks after termination of nicotine exposure. After identifying genes with a significant agextreatment interaction, we employed template matching to find specific patterns of expression across age and treatment. Of those genes that were transiently regulated (up- or down-regulated immediately following the end of nicotine treatment, but back to saline baseline 30 days later), two-thirds were specific to adult animals, while only 30% were specific to adolescents and 4% were shared across the two ages. In contrast, significant genes that were persistently regulated (altered following nicotine treatment and still altered 30 days later) were more likely (59%) to be adolescent, with only 32% in adults and 8% shared. The greatest number of significant genes was late-regulated (no change immediately after nicotine, but regulated 30 days later). Again, most were in adolescents (54%), compared to adults (10%) or shared (36%). Pathway analysis revealed that adolescent-specific genes were over-represented in several biological functions and canonical pathways, including nervous system development and function and long-term potentiation. Furthermore, adolescent-specific genes formed extensive interaction networks, unlike those specific for adults or shared. This age-specific expression pattern may relate to the heightened vulnerability of adolescents to the effects of addictive drugs. In particular, the propensity of adolescents to show persistent alterations in gene expression corresponds to the persistence of drug dependence among smokers who began their habit as adolescents. These findings support a model whereby adolescent brains are uniquely vulnerable to long-term changes in gene expression in the brain's reward pathway caused by early exposure to nicotine.
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332
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Grucza RA, Johnson EO, Krueger RF, Breslau N, Saccone NL, Chen LS, Derringer J, Agrawal A, Lynskey M, Bierut LJ. Incorporating age at onset of smoking into genetic models for nicotine dependence: evidence for interaction with multiple genes. Addict Biol 2010; 15:346-57. [PMID: 20624154 DOI: 10.1111/j.1369-1600.2010.00220.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Nicotine dependence is moderately heritable, but identified genetic associations explain only modest portions of this heritability. We analyzed 3369 SNPs from 349 candidate genes and investigated whether incorporation of SNP-by-environment interaction into association analyses might bolster gene discovery efforts and prediction of nicotine dependence. Specifically, we incorporated the interaction between allele count and age at onset of regular smoking (AOS) into association analyses of nicotine dependence. Subjects were from the Collaborative Genetic Study of Nicotine Dependence and included 797 cases ascertained for Fagerström nicotine dependence and 811 non-nicotine-dependent smokers as controls, all of European descent. Compared with main effect models, SNP x AOS interaction models resulted in higher numbers of nominally significant tests, increased predictive utility at individual SNPs and higher predictive utility in a multi-locus model. Some SNPs previously documented in main effect analyses exhibited improved fits in the joint analysis, including rs16969968 from CHRNA5 and rs2314379 from MAP3K4. CHRNA5 exhibited larger effects in later-onset smokers, in contrast with a previous report that suggested the opposite interaction (Weiss et al. 2008). However, a number of SNPs that did not emerge in main effect analyses were among the strongest findings in the interaction analyses. These include SNPs located in GRIN2B (P = 1.5 x 10(-5)), which encodes a subunit of the N-methyl-D-aspartate receptor channel, a key molecule in mediating age-dependent synaptic plasticity. Incorporation of logically chosen interaction parameters, such as AOS, into genetic models of substance use disorders may increase the degree of explained phenotypic variation and constitutes a promising avenue for gene discovery.
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Affiliation(s)
- Richard A Grucza
- Department of Psychiatry, Washington University School of Medicine, 660 South Euclid Ave., St Louis, MO 63110, USA.
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The mGluR5 antagonist MTEP dissociates the acquisition of predictive and incentive motivational properties of reward-paired stimuli in mice. Neuropsychopharmacology 2010; 35:1807-17. [PMID: 20375996 PMCID: PMC3055484 DOI: 10.1038/npp.2010.48] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An environmental stimulus paired with reward (a conditioned stimulus; CS) can acquire predictive properties that signal reward availability and may also acquire incentive motivational properties that enable the CS to influence appetitive behaviors. The neural mechanisms involved in the acquisition and expression of these CS properties are not fully understood. The metabotropic glutamate receptor, mGluR5, contributes to synaptic plasticity underlying learning and memory processes. We examined the role of mGluR5 in the acquisition and expression of learning that enables a CS to predict reward (goal-tracking) and acquire incentive properties (conditioned reinforcement). Mice were injected with vehicle or the mGluR5 antagonist, MTEP (3 or 10 mg/kg), before each Pavlovian conditioning session in which a stimulus (CS+) was paired with food delivery. Subsequently, in the absence of the primary food reward, we determined whether the CS+ could reinforce a novel instrumental response (conditioned reinforcement) and direct behavior toward the place of reward delivery (goal-tracking). MTEP did not affect performance during the conditioning phase, or the ability of the CS+ to elicit a goal-tracking response. In contrast, 10 mg/kg MTEP given before each conditioning session prevented the subsequent expression of conditioned reinforcement. This dose of MTEP did not affect conditioned reinforcement when administered before the test, in mice that had received vehicle before conditioning sessions. Thus, mGluR5 has a critical role in the acquisition of incentive properties by a CS, but is not required for the expression of incentive learning, or for the CS to acquire predictive properties that signal reward availability.
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334
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Hammer SB, Ruby CL, Brager AJ, Prosser RA, Glass JD. Environmental modulation of alcohol intake in hamsters: effects of wheel running and constant light exposure. Alcohol Clin Exp Res 2010; 34:1651-8. [PMID: 20569242 DOI: 10.1111/j.1530-0277.2010.01251.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND Alcohol abuse leads to marked disruptions of circadian rhythms, and these disturbances in themselves can increase the drive to drink. Circadian clock timing is regulated by light, as well as by nonphotic influences such as food, social interactions, and wheel running. We previously reported that alcohol markedly disrupts photic and nonphotic modes of circadian rhythm regulation in Syrian hamsters. As an extension of this work, we characterize the hedonic interrelationship between wheel running and ethanol (EtOH) intake and the effects of environmental circadian disruption (long-term exposure to constant light [LL]) on the drive to drink. METHODS First, we tested the effect of wheel running on chronic free-choice consumption of a 20% (v/v) EtOH solution and water. Second, the effect of this alcohol drinking on wheel running in alcohol-naive animals was investigated. Third, we assessed the influence of LL, known to suppress locomotor activity and cause circadian rhythm disruption, on EtOH consumption and wheel-running behavior. RESULTS Inhibitory effects of wheel running on EtOH intake and vice versa were observed. Exposure to LL, while not affecting EtOH intake, induced rhythm splitting in 75% of the animals. Notably, the splitting phenotype was associated with lower levels of EtOH consumption and preference prior to, and throughout, the period of LL exposure. CONCLUSIONS These results are evidence that exercise may offer an efficacious clinical approach to reducing EtOH intake. Also, predisposition for light-induced (or other) forms of circadian disruption may modulate the drive to drink.
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Affiliation(s)
- Steven B Hammer
- Department of Biological Sciences, Kent State University, Kent, Ohio 44242, USA
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335
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Touzani K, Bodnar RJ, Sclafani A. Neuropharmacology of learned flavor preferences. Pharmacol Biochem Behav 2010; 97:55-62. [PMID: 20600253 DOI: 10.1016/j.pbb.2010.06.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 05/27/2010] [Accepted: 06/10/2010] [Indexed: 11/16/2022]
Abstract
Innate and learned flavor preferences influence food and fluid choices in animals. Two primary forms of learned preferences involve flavor-flavor and flavor-nutrient associations in which a particular flavor element (e.g., odor) is paired with an innately preferred flavor element (e.g., sweet taste) or with a positive post-oral nutrient consequence. This review summarizes recent findings related to the neurochemical basis of learned flavor preferences. Systemic and central injections of dopamine receptor antagonists implicate brain dopamine signaling in both flavor-flavor and flavor-nutrient conditioning by the taste and post-oral effects of sugars. Dopamine signaling in the nucleus accumbens, amygdala and lateral hypothalamus is involved in one or both forms of conditioning and selective effects are produced by D1-like and D2-like receptor antagonism. Opioid receptor antagonism, despite its suppressive action on sugar intake and reward, has little effect on the acquisition or expression of flavor preferences conditioned by the sweet taste or post-oral actions of sugars. Other studies indicate that flavor preference conditioning by sugars is differentially influenced by glutamate receptor antagonism, cannabinoid receptor antagonism and benzodiazepine receptor activation.
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Affiliation(s)
- Khalid Touzani
- Department of Psychology, Brooklyn College, City University of New York, NY 11210, USA
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336
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McPherson CS, Lawrence AJ. The nuclear transcription factor CREB: involvement in addiction, deletion models and looking forward. Curr Neuropharmacol 2010; 5:202-12. [PMID: 19305803 PMCID: PMC2656817 DOI: 10.2174/157015907781695937] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2006] [Revised: 03/16/2007] [Accepted: 03/29/2007] [Indexed: 01/26/2023] Open
Abstract
Addiction involves complex physiological processes, and is characterised not only by broad phenotypic and behavioural traits, but also by ongoing molecular and cellular adaptations. In recent years, increasingly effective and novel techniques have been developed to unravel the molecular implications of addiction. Increasing evidence has supported a contribution of the nuclear transcription factor CREB in the development of addiction, both in contribution to phenotype and expression in brain regions critical to various aspects of drug-seeking behaviour and drug reward. Abstracting from this, models have exploited these data by removing the CREB gene from the developing or developed mouse, to crucially determine its impact upon addiction-related processes. More recent models, however, hold greater promise in unveiling the contribution of CREB to disorders such as addiction.
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Affiliation(s)
- Cameron S McPherson
- Brain Injury and Repair Group, Howard Florey Institute, University of Melbourne, Parkville, Victoria 3010, Australia
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337
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Addictive nicotine alters local circuit inhibition during the induction of in vivo hippocampal synaptic potentiation. J Neurosci 2010; 30:6443-53. [PMID: 20445070 DOI: 10.1523/jneurosci.0458-10.2010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The drug addiction process shares many commonalities with normal learning and memory. Addictive drugs subvert normal synaptic plasticity mechanisms, and the consequent synaptic changes underlie long-lasting modifications in behavior that accrue during the progression from drug use to addiction. Supporting this hypothesis, it was recently shown that nicotine administered to freely moving mice induces long-term synaptic potentiation of the perforant path connection to granule cells of the dentate gyrus. The perforant path carries place and spatial information that links the environment to drug taking. An example of that association is the nicotine-induced synaptic potentiation of the perforant path that was found to underlie nicotine-conditioned place preference. The present study examines the influence of nicotine over local GABAergic inhibition within the dentate gyrus during the drug-induced synaptic potentiation. In vivo recordings from freely moving mice suggested that both feedforward and feedback inhibition onto granules cells were diminished by nicotine during the induction of synaptic potentiation. In vitro brain slice studies indicated that nicotine altered local circuit inhibition within the dentate gyrus leading to disinhibition of granule cells. These changes in local inhibition contributed to nicotine-induced in vivo synaptic potentiation, thus, likely contributed to drug-associated memories. Through this learning process, environmental features become cues that motivate conditioned drug-seeking and drug-taking behaviors.
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338
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Frohmader KS, Pitchers KK, Balfour ME, Coolen LM. Mixing pleasures: review of the effects of drugs on sex behavior in humans and animal models. Horm Behav 2010; 58:149-62. [PMID: 20004662 DOI: 10.1016/j.yhbeh.2009.11.009] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2009] [Revised: 11/17/2009] [Accepted: 11/24/2009] [Indexed: 02/04/2023]
Abstract
Drugs of abuse act on the brain circuits mediating motivation and reward associated with natural behaviors. There is ample evidence that drugs of abuse impact male and female sexual behavior. First, the current review discusses the effect of drugs of abuse on sexual motivation and performance in male and female humans. In particular, we discuss the effects of commonly abused drugs including psychostimulants, opiates, marijuana/THC, and alcohol. In general, drug use affects sexual motivation, arousal, and performance and is commonly associated with increased sexual risk behaviors. Second, studies on effects of systemic administration of drugs of abuse on sexual behavior in animals are reviewed. These studies analyze the effects on sexual performance and motivation but do not investigate the effects of drugs on risk-taking behavior, creating a disconnect between human and animal studies. For this reason, we discuss two studies that focus on the effects of alcohol and methamphetamine on inhibition of maladaptive sex-seeking behaviors in rodents. Third, this review discusses potential brain areas where drugs of abuse may be exerting their effect on sexual behavior with a focus on the mesolimbic system as the site of action. Finally, we discuss recent studies that have brought to light that sexual experience in turn can affect drug responsiveness, including a sensitized locomotor response to amphetamine in female and male rodents as well as enhanced drug reward in male rats.
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Affiliation(s)
- Karla S Frohmader
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
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339
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Bonevski B, Paul C, Lorraine P, Lecathelinais C. Spending, Shopping and Saving: Ex-Smokers' Perceptions About Material Gains Following Quitting. J Smok Cessat 2010. [DOI: 10.1375/jsc.5.1.77] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
AbstractObjective:To measure (a) the perceived amount of money saved by ex-smokers after quitting, (b) changes in shopping behaviours and (c) alternative uses of the money saved.Design:A 2006 computer-assisted telephone interview survey of smoking-related behaviours and attitudes in New South Wales, Australia.Main outcome measures:Participants (N= 147) who had quit smoking in the previous 12 months answered items regarding personal expenditure on tobacco smoking.Results:Most (51%) ex-smokers reported spending up to $40 per week on cigarettes when they smoked. Fifty-six per cent of lower socioeconomic status (SES) ex-smokers reported spending over $40 per week on cigarettes compared to 40% of those from higher socioeconomic areas. Almost a third (28%) of respondents reported shopping more or shopping at different locations since quitting. The three highest alternative items purchased since quitting were food (19%). other things not listed (13%) and clothing (10%); however, most respondents reported not changing their spending habits (54%).Conclusion:This study indicates that tobacco is a high-cost product with smokers spending approximately 5% of average weekly income on cigarettes. Those living in lower SES areas report spending more on cigarettes than those in higher SES areas. The majority of quitters could not identify any change in spending or saving as a result of quitting. However, changes in shopping behaviours were noted. It may be useful for quitters to quarantine their cigarette money to increase the salience and power of financial benefit as an incentive to maintain quitting.
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340
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Flatscher-Bader T, Harrison E, Matsumoto I, Wilce PA. Genes associated with alcohol abuse and tobacco smoking in the human nucleus accumbens and ventral tegmental area. Alcohol Clin Exp Res 2010; 34:1291-302. [PMID: 20477762 DOI: 10.1111/j.1530-0277.2010.01207.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND The incidence of alcohol and tobacco co-abuse is as high as 80%. The molecular mechanism underlying this comorbidity is virtually unknown, but interactions between these drugs have important implications for the development of and recovery from drug dependence. METHODS We investigated the effects of chronic tobacco and alcohol abuse and the interaction of the 2 behaviors on global gene expression in the human nucleus accumbens using cDNA microarrays and 20 alcoholic and control cases, with and without smoking comorbidity. Changes in gene expression were established by factorial ANOVA. Unsupervised hierarchical clustering was utilized to probe the strength of the data sets. Applying real-time PCR differential expression of candidate genes was confirmed in the nucleus accumbens and explored further in a second core region of the mesolimbic system, the ventral tegmental area. RESULTS Subjecting the data sets derived from microarray gene expression screening to unsupervised hierarchical clustering tied the cases into distinct groups. When considering all alcohol-responsive genes, alcoholics were separated from nonalcoholics with the exception of 1 control case. All smokers were distinguished from nonsmokers based on similarity in expression of smoking-sensitive genes. In the nucleus accumbens, alcohol-responsive genes were associated with transcription, lipid metabolism, and signaling. Smoking-sensitive genes were predominantly assigned to functional groups concerned with RNA processing and the endoplasmic reticulum. Both drugs influenced the expression of genes involved in matrix remodeling, proliferation, and cell morphogenesis. Additionally, a gene set encoding proteins involved in the canonical pathway "regulation of the actin cytoskeleton" was induced in response to alcohol and tobacco co-abuse and included. Alcohol abuse elevated the expression of candidate genes in this pathway in the nucleus accumbens and ventral tegmental area, while smoking comorbidity blunted this induction in the ventral tegmental area. CONCLUSIONS The region-specific modulation of alcohol-sensitive gene expression by smoking may have important consequences for alcohol-induced aberrations within the mesolimbic dopaminergic system.
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341
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Jones JL, Day JJ, Aragona BJ, Wheeler RA, Wightman RM, Carelli RM. Basolateral amygdala modulates terminal dopamine release in the nucleus accumbens and conditioned responding. Biol Psychiatry 2010; 67:737-44. [PMID: 20044074 PMCID: PMC2849914 DOI: 10.1016/j.biopsych.2009.11.006] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Revised: 11/06/2009] [Accepted: 11/07/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND Dopamine signaling in the nucleus accumbens (NAc) is essential for goal-directed behaviors and primarily arises from burst firing of ventral tegmental area neurons. However, the role of associative neural substrates such as the basolateral amygdala (BLA) in regulating phasic dopamine release in the NAc, particularly during reward seeking, remains unknown. METHODS Male Sprague-Dawley rats learned to discriminate two cues: a discriminative stimulus (DS) that predicted sucrose reinforcement contingent upon a lever press and a nonassociated stimulus (NS) that predicted a second lever never reinforced with sucrose. Following training, a test session was completed in which NAc dopamine was measured using fast-scan cyclic voltammetry in conjunction with inactivation of the ipsilateral BLA (gamma-aminobutyric acid agonists; baclofen/muscimol) to determine the contribution of BLA activity to dopamine release in the NAc core during the task. RESULTS Under vehicle conditions, DS and NS presentation elicited dopamine release within the NAc core. The DS evoked significantly more dopamine than the NS. Inactivation of the BLA selectively attenuated the magnitude of DS-evoked dopamine release, concurrent with an attenuation of DS-evoked conditioned approaches. Other behavioral responses (e.g., lever pressing) and dopamine release concomitant with those events were unaltered by BLA inactivation. Furthermore, neither ventral tegmental area electrically stimulated dopamine release nor the probability of high concentration dopamine release events was altered following BLA inactivation. CONCLUSIONS These results demonstrate that the BLA terminally modulates dopamine signals within the NAc core under specific, behaviorally relevant conditions, illustrating a functional mechanism by which the BLA selectively facilitates responding to motivationally salient environmental stimuli.
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Affiliation(s)
- Joshua L. Jones
- Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Jeremy J. Day
- Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Brandon J. Aragona
- Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Robert A. Wheeler
- Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - R. Mark Wightman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599,Neuroscience Center University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Regina M. Carelli
- Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599,Neuroscience Center University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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342
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Schmidt HD, Pierce RC. Cocaine-induced neuroadaptations in glutamate transmission: potential therapeutic targets for craving and addiction. Ann N Y Acad Sci 2010; 1187:35-75. [PMID: 20201846 DOI: 10.1111/j.1749-6632.2009.05144.x] [Citation(s) in RCA: 164] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A growing body of evidence indicates that repeated exposure to cocaine leads to profound changes in glutamate transmission in limbic nuclei, particularly the nucleus accumbens. This review focuses on preclinical studies of cocaine-induced behavioral plasticity, including behavioral sensitization, self-administration, and the reinstatement of cocaine seeking. Behavioral, pharmacological, neurochemical, electrophysiological, biochemical, and molecular biological changes associated with cocaine-induced plasticity in glutamate systems are reviewed. The ultimate goal of these lines of research is to identify novel targets for the development of therapies for cocaine craving and addiction. Therefore, we also outline the progress and prospects of glutamate modulators for the treatment of cocaine addiction.
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Affiliation(s)
- Heath D Schmidt
- Department of Psychiatry, Center for Neurobiology and Behavior, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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343
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Olive MF. Cognitive effects of Group I metabotropic glutamate receptor ligands in the context of drug addiction. Eur J Pharmacol 2010; 639:47-58. [PMID: 20371237 DOI: 10.1016/j.ejphar.2010.01.029] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 01/14/2010] [Accepted: 01/20/2010] [Indexed: 01/03/2023]
Abstract
Glutamate plays a pivotal role in regulating drug self-administration and drug-seeking behavior, and the past decade has witnessed a substantial surge of interest in the role of Group I metabotropic glutamate receptors (mGlu(1) and mGlu(5) receptors) in mediating these behaviors. As will be reviewed here, Group I mGlu receptors are involved in normal and drug-induced synaptic plasticity, drug reward, reinforcement and relapse-like behaviors, and addiction-related cognitive processes such as maladaptive learning and memory, behavioral inflexibility, and extinction learning. Animal models of addiction have revealed that antagonists of Group I mGlu receptors, particularly the mGlu(5) receptor, reduce self-administration of virtually all drugs of abuse. Since inhibitors of mGlu5 receptor function have now entered clinical trials for other medical conditions and appear to be well-tolerated, a key question that remains unanswered is - what changes in cognition are produced by these compounds that result in reduced drug intake and drug-seeking behavior? Finally, in contrast to mGlu(5) receptor antagonists, recent studies have indicated that positive allosteric modulation of mGlu(5) receptors actually enhances synaptic plasticity and improves various aspects of cognition, including spatial learning, behavioral flexibility, and extinction of drug-seeking behavior. Thus, while inhibition of Group I mGlu receptor function may reduce drug reward, reinforcement, and relapse-related behaviors, positive allosteric modulation of the mGlu5 receptor subtype may actually enhance cognition and potentially reverse some of the cognitive deficits associated with chronic drug use.
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Affiliation(s)
- M Foster Olive
- Center for Drug and Alcohol Programs, Department of Psychiatry, Medical University of South Carolina, 67 President Street, MSC 861, Charleston, SC 29425, USA.
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344
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Frohmader KS, Wiskerke J, Wise RA, Lehman MN, Coolen LM. Methamphetamine acts on subpopulations of neurons regulating sexual behavior in male rats. Neuroscience 2010; 166:771-84. [PMID: 20045448 PMCID: PMC2837118 DOI: 10.1016/j.neuroscience.2009.12.070] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 12/22/2009] [Accepted: 12/28/2009] [Indexed: 01/27/2023]
Abstract
Methamphetamine (Meth) is a highly addictive stimulant. Meth abuse is commonly associated with the practice of sexual risk behavior and increased prevalence of Human Immunodeficiency Virus and Meth users report heightened sexual desire, arousal, and sexual pleasure. The biological basis for this drug-sex nexus is unknown. The current study demonstrates that Meth administration in male rats activates neurons in brain regions of the mesolimbic system that are involved in the regulation of sexual behavior. Specifically, Meth and mating co-activate cells in the nucleus accumbens core and shell, basolateral amygdala, and anterior cingulate cortex. These findings illustrate that in contrast to current belief drugs of abuse can activate the same cells as a natural reinforcer, that is sexual behavior, and in turn may influence compulsive seeking of this natural reward.
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Affiliation(s)
- K S Frohmader
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada, N6A 5C1
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345
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Fattore L, Melis M, Fadda P, Pistis M, Fratta W. The endocannabinoid system and nondrug rewarding behaviours. Exp Neurol 2010; 224:23-36. [PMID: 20353776 DOI: 10.1016/j.expneurol.2010.03.020] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Rewarding behaviours such as sexual activity, eating, nursing, parenting, social interactions, and play activity are conserved strongly in evolution, and they are essential for development and survival. All of these behaviours are enjoyable and represent pleasant experiences with a high reward value. Remarkably, rewarding behaviours activate the same brain circuits that mediate the positive reinforcing effects of drugs of abuse and of other forms of addiction, such as gambling and food addiction. Given the involvement of the endocannabinoid system in a variety of physiological functions of the nervous system, it is not surprising that it takes part in the complex machinery that regulates gratification and perception of pleasure. In this review, we focus first on the role of the endocannabinoid system in the modulation of neural activity and synaptic functions in brain regions that are involved in natural and nonnatural rewards (namely, the ventral tegmental area, striatum, amygdala, and prefrontal cortex). Then, we examine the role of the endocannabinoid system in modulating behaviours that directly or indirectly activate these brain reward pathways. More specifically, current knowledge of the effects of the pharmacological manipulation of the endocannabinoid system on natural (eating, sexual behaviour, parenting, and social play) and pathological (gambling) rewarding behaviours is summarised and discussed.
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Affiliation(s)
- Liana Fattore
- CNR Neuroscience Institute - Cagliari, Cittadella Universitaria di Monserrato, Italy
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346
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Nakano T, Doi T, Yoshimoto J, Doya K. A kinetic model of dopamine- and calcium-dependent striatal synaptic plasticity. PLoS Comput Biol 2010; 6:e1000670. [PMID: 20169176 PMCID: PMC2820521 DOI: 10.1371/journal.pcbi.1000670] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Accepted: 01/07/2010] [Indexed: 11/28/2022] Open
Abstract
Corticostriatal synapse plasticity of medium spiny neurons is regulated by glutamate input from the cortex and dopamine input from the substantia nigra. While cortical stimulation alone results in long-term depression (LTD), the combination with dopamine switches LTD to long-term potentiation (LTP), which is known as dopamine-dependent plasticity. LTP is also induced by cortical stimulation in magnesium-free solution, which leads to massive calcium influx through NMDA-type receptors and is regarded as calcium-dependent plasticity. Signaling cascades in the corticostriatal spines are currently under investigation. However, because of the existence of multiple excitatory and inhibitory pathways with loops, the mechanisms regulating the two types of plasticity remain poorly understood. A signaling pathway model of spines that express D1-type dopamine receptors was constructed to analyze the dynamic mechanisms of dopamine- and calcium-dependent plasticity. The model incorporated all major signaling molecules, including dopamine- and cyclic AMP-regulated phosphoprotein with a molecular weight of 32 kDa (DARPP32), as well as AMPA receptor trafficking in the post-synaptic membrane. Simulations with dopamine and calcium inputs reproduced dopamine- and calcium-dependent plasticity. Further in silico experiments revealed that the positive feedback loop consisted of protein kinase A (PKA), protein phosphatase 2A (PP2A), and the phosphorylation site at threonine 75 of DARPP-32 (Thr75) served as the major switch for inducing LTD and LTP. Calcium input modulated this loop through the PP2B (phosphatase 2B)-CK1 (casein kinase 1)-Cdk5 (cyclin-dependent kinase 5)-Thr75 pathway and PP2A, whereas calcium and dopamine input activated the loop via PKA activation by cyclic AMP (cAMP). The positive feedback loop displayed robust bi-stable responses following changes in the reaction parameters. Increased basal dopamine levels disrupted this dopamine-dependent plasticity. The present model elucidated the mechanisms involved in bidirectional regulation of corticostriatal synapses and will allow for further exploration into causes and therapies for dysfunctions such as drug addiction. Recent brain imaging and neurophysiological studies suggest that the striatum, the start of the basal ganglia circuit, plays a major role in value-based decision making and behavioral disorders such as drug addiction. The plasticity of synaptic input from the cerebral cortex to output neurons of the striatum, which are medium spiny neurons, depends on interactions between glutamate input from the cortex and dopaminergic input from the midbrain. It also links sensory and cognitive states in the cortex with reward-oriented action outputs. The mechanisms involved in molecular cascades that transmit glutamate and dopamine inputs to changes in postsynaptic glutamate receptors are very complex and it is difficult to intuitively understand the mechanism. Therefore, a biochemical network model was constructed, and computer simulations were performed. The model reproduced dopamine-dependent and calcium-dependent forms of long-term depression (LTD) and potentiation (LTP) of corticostriatal synapses. Further in silico experiments revealed that a positive feedback loop formed by proteins, the protein specifically expressed in the striatum, served as the major switch for inducing LTD and LTP. This model could allow us to understand dynamic constraints in reward-dependent learning, as well as causes and therapies of dopamine-related disorders such as drug addiction.
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Affiliation(s)
- Takashi Nakano
- Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Japan
- Okinawa Institute of Science and Technology, Uruma, Japan
| | | | - Junichiro Yoshimoto
- Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Japan
- Okinawa Institute of Science and Technology, Uruma, Japan
| | - Kenji Doya
- Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Japan
- Okinawa Institute of Science and Technology, Uruma, Japan
- * E-mail:
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347
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Kryger R, Wilce PA. The effects of alcoholism on the human basolateral amygdala. Neuroscience 2010; 167:361-71. [PMID: 20153402 DOI: 10.1016/j.neuroscience.2010.01.061] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 01/29/2010] [Accepted: 01/29/2010] [Indexed: 10/19/2022]
Abstract
Alcohol affects gene expression in several brain regions. The amygdala is a key structure in the brain's emotional system and in recent years the crucial importance of the amygdala in drug-seeking and relapse has been increasingly recognized. In this study gene expression screening was used to identify genes involved in alcoholism in the human basolateral amygdala of male patients. The results show that alcoholism affects a broad range of genes and many systems including genes involved in synaptic transmission, neurotransmitter transport, structural plasticity, metabolism, energy production, transcription and RNA processing and the circadian cycle. In particular, genes involved in the glutamate system were affected in the alcoholic patients. In the amygdala the glutamate system is involved in the acquisition, consolidation, expression and extinction of associative learning, which is a vital part of addiction, and in alcohol abusers it is associated with withdrawal anxiety and neurodegeneration. Downregulation of the excitatory amino acid transporters GLAST, GLT-1 and the AMPA glutamate receptor 2 (GluR2) revealed by the microarray were confirmed by Western blots. The decreased expression of GLAST, GLT-1 and GluR2 in the alcoholic patients may increase glutamate tone and activity in the basolateral amygdala and this may contribute to neurodegeneration as well as the expression of associative memories and anxiety which underlie continued drug-seeking and chronic relapse.
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Affiliation(s)
- R Kryger
- School of Chemistry & Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia.
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348
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Wright JW, Harding JW. Contributions of matrix metalloproteinases to neural plasticity, habituation, associative learning and drug addiction. Neural Plast 2010; 2009:579382. [PMID: 20169175 PMCID: PMC2821634 DOI: 10.1155/2009/579382] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 11/22/2009] [Accepted: 12/15/2009] [Indexed: 12/13/2022] Open
Abstract
The premise of this paper is that increased expression of matrix metalloproteinases (MMPs) permits the reconfiguration of synaptic connections (i.e., neural plasticity) by degrading cell adhesion molecules (CAMs) designed to provide stability to those extracellular matrix (ECM) proteins that form scaffolding supporting neurons and glia. It is presumed that while these ECM proteins are weakened, and/or detached, synaptic connections can form resulting in new neural pathways. Tissue inhibitors of metalloproteinases (TIMPs) are designed to deactivate MMPs permitting the reestablishment of CAMs, thus returning the system to a reasonably fixed state. This review considers available findings concerning the roles of MMPs and TIMPs in reorganizing ECM proteins thus facilitating the neural plasticity underlying long-term potentiation (LTP), habituation, and associative learning. We conclude with a consideration of the influence of these phenomena on drug addiction, given that these same processes may be instrumental in the formation of addiction and subsequent relapse. However, our knowledge concerning the precise spatial and temporal relationships among the mechanisms of neural plasticity, habituation, associative learning, and memory consolidation is far from complete and the possibility that these phenomena mediate drug addiction is a new direction of research.
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Affiliation(s)
- John W Wright
- Department of Psychology, Washington State University, Pullman, WA 99164-4820, USA.
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349
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Frascella J, Potenza MN, Brown LL, Childress AR. Shared brain vulnerabilities open the way for nonsubstance addictions: carving addiction at a new joint? Ann N Y Acad Sci 2010; 1187:294-315. [PMID: 20201859 PMCID: PMC3671907 DOI: 10.1111/j.1749-6632.2009.05420.x] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
For more than half a century, since the beginning of formal diagnostics, our psychiatric nosology has compartmentalized the compulsive pursuit of substance (e.g., alcohol, cocaine, heroin, nicotine) from nonsubstance (e.g., gambling, food, sex) rewards. Emerging brain, behavioral, and genetic findings challenge this diagnostic boundary, pointing to shared vulnerabilities underlying the pathological pursuit of substance and nonsubstance rewards. Working groups for the fifth revision of the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-V), are thus considering whether the nosologic boundaries of addiction should be redrawn to include nonsubstance disorders, such as gambling. This review discusses how neurobiological data from problem gambling, obesity, and "normal" states of attachment (romantic infatuation, sexual attraction, maternal bonds) may help us in the task of carving addictions "at a new joint." Diagnostic recarving may have a positive effect on addiction research, stimulating discovery of "crossover" pharmacotherapies with benefit for both substance and nonsubstance addictions.
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Affiliation(s)
- Joseph Frascella
- Division of Clinical Neuroscience and Behavioral Research, National Institute on Drug Abuse, Rockville, Maryland, USA
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350
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Nai Q, Li S, Wang SH, Liu J, Lee FJS, Frankland PW, Liu F. Uncoupling the D1-N-methyl-D-aspartate (NMDA) receptor complex promotes NMDA-dependent long-term potentiation and working memory. Biol Psychiatry 2010; 67:246-54. [PMID: 19846062 DOI: 10.1016/j.biopsych.2009.08.011] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Revised: 08/04/2009] [Accepted: 08/04/2009] [Indexed: 01/17/2023]
Abstract
BACKGROUND Although dopamine D1 receptors are involved in working memory, how D1 receptors contribute to this process remains unclear. Numerous studies have shown that D1 receptors have extensive functional interaction with N-methyl-D-aspartate (NMDA) receptor. Our group previously demonstrated that D1 receptors were able to regulate NMDA receptor functions through direct protein-protein interactions involving the carboxyl terminals of D1 receptors and NMDA receptor NR1a and NR2A subunits respectively. In this study, we explored the effects of the D1-NR1 interaction on NMDA receptor-dependent long-term potentiation (LTP) and working memory by using the TAT-conjugated interfering peptide (TAT-D1-t2). METHODS Miniature excitatory postsynaptic currents are recorded in rat hippocampal primary cultures. Coimmunoprecipitation and calcium/calmodulin-dependent protein kinase II (CaMKII) activity are measured in hippocampal slices and hippocampal neurons under the specified experimental conditions, respectively. Working memory was assessed using a delayed match-to-place protocol in the Morris Water Maze following administration of the TAT-D1-t2 peptide. RESULTS Electrophysiology experiments showed that activation of D1 receptor upregulates NMDA receptor-mediated LTP in a CaMKII-dependent manner. Furthermore, D1 receptor agonist stimulation promotes the NR1-CaMKII coupling and enhances the CaMKII activity; and the D1 receptor-mediated effects can be blocked by the application of the TAT-D1-t2 peptide. Interestingly, animals injected with TAT-D1-t2 peptide exhibited significantly impaired working memory. CONCLUSIONS Our study showed a critical role of NMDA-D1 direct protein-protein interaction in NMDA receptor-mediated LTP and working memory and implicated the involvement of CaMKII in this process.
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Affiliation(s)
- Qiang Nai
- Department of Neuroscience, Centre for Addiction and Mental Health, Clarke Division, Toronto, ON M5T 1R8, Canada
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