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Campbell RR, Lobo MK. Neurobiological mechanisms underlying psychostimulant use. Curr Opin Neurobiol 2023; 83:102786. [PMID: 37776675 DOI: 10.1016/j.conb.2023.102786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/01/2023] [Accepted: 09/01/2023] [Indexed: 10/02/2023]
Abstract
Rates of individuals struggling with psychostimulant use disorder (PSUD), defined as chronic use of psychostimulants despite negative consequences, are growing rapidly over the last few decades. However, there are no current pharmacotherapeutics to aid individuals in maintaining drug abstinence. Identifying the underlying neurobiological mechanisms that promote persistent craving and taking of psychostimulants is critical to creating novel pharmacological treatments for PSUD. Psychostimulant use dysregulates processes within the brain that are responsible for decision-making, reward, and memory formation to drive future drug-seeking. Here, we describe novel findings and theories on how psychostimulants impact mechanisms related to transcription, mitochondrial function, and synaptic plasticity within the reward system to drive drug-seeking. We also highlight work examining how psychostimulants impact neural networks through rewiring circuitry to drive addiction-related behaviors. Overall, this review aims to feature the latest progress in understanding the biological basis of PSUD and promising mechanisms for PSUD pharmacotherapeutics.
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Affiliation(s)
- Rianne R Campbell
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA. https://twitter.com/RianneThoughts
| | - Mary Kay Lobo
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA.
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2
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Caffino L, Mottarlini F, Targa G, Verheij MMM, Fumagalli F, Homberg JR. Responsivity of serotonin transporter knockout rats to short and long access to cocaine: modulation of the glutamate signaling in the nucleus accumbens shell. Br J Pharmacol 2022; 179:3727-3739. [PMID: 35174489 PMCID: PMC9310702 DOI: 10.1111/bph.15823] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 02/01/2022] [Accepted: 02/04/2022] [Indexed: 11/28/2022] Open
Abstract
Background and Purpose It has been well established that glutamate in the nucleus accumbens (NAc) plays a critical role in the motivation to take drugs of abuse. We have previously demonstrated that rats with ablation of the serotonin transporter (SERT−/− rats) show increased cocaine intake reminiscent of compulsivity. Experimental Approach By comparing SERT−/− to SERT+/+ rats, we investigated whether SERT deletion influences glutamate homeostasis under control conditions as well as after short access (ShA: 1 h per session) or long access (LgA: 6 h per session) to cocaine self‐administration. Rats were killed at 24 h after the last self‐administration session for ex vivo molecular analyses of the main determinants of the glutamate system, including transporters (vesicular and glial), receptors (main post‐synaptic subunits of NMDA and AMPA receptors together with the metabotropic subunit mGLUR5), and scaffolding proteins (SAP102, SAP97, and GRIP) in the NAc shell (sNAc) Key Results In cocaine‐naive animals, SERT deletion was associated with changes indicative for a reduction in glutamate signalling. ShA and LgA exposure led to a further dysregulation of the glutamatergic synapse. Conclusion SERT deletion may render the glutamatergic synapses of the NAc shell more responsive to both ShA and LgA intake of cocaine.
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Affiliation(s)
- Lucia Caffino
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Italy
| | - Francesca Mottarlini
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Italy
| | - Giorgia Targa
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Italy
| | - Michel M M Verheij
- Department of Cognitive Neuroscience, division of Molecular Neurogenetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, the Netherlands
| | - Fabio Fumagalli
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Italy
| | - Judith R Homberg
- Department of Cognitive Neuroscience, division of Molecular Neurogenetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, the Netherlands
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Hodebourg R, Kalivas PW, Kruyer A. Extrasynaptic therapeutic targets in substance use and stress disorders. Trends Pharmacol Sci 2022; 43:56-68. [PMID: 34753604 PMCID: PMC8688303 DOI: 10.1016/j.tips.2021.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 10/05/2021] [Accepted: 10/08/2021] [Indexed: 01/03/2023]
Abstract
Treatments for substance use and stress disorders are based on ameliorating behavioral symptoms, not on reversing the synaptic pathology that has the potential to cure disorders. This failing arises in part from a research focus on how pre- and postsynaptic physiology is changed even though key neuropathology exists in the perisynaptic neuropil that homeostatically regulates synaptic transmission. We explore recent findings from the substance use and stress disorder literature pointing to a key role for perisynaptic astroglia and signaling in the extracellular matrix (ECM) in regulating synaptic pathology. We conclude that drugs and stress initiate long-lasting changes in brain synapses via enduring neuroadaptations in astroglia and the ECM, and that modulating extrasynaptic regulators may be therapeutically useful.
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Affiliation(s)
- Ritchy Hodebourg
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29464, USA
| | - Peter W Kalivas
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29464, USA.
| | - Anna Kruyer
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29464, USA
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4
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Abstract
Astroglia are key regulators of synaptic function, playing central roles in homeostatic ion buffering, energy dynamics, transmitter uptake, maintenance of neurotransmitter pools, and regulation of synaptic plasticity through release of neuroactive chemicals. Given the myriad of crucial homeostatic and signaling functions attributed to astrocytes and the variety of neurotransmitter receptors expressed by astroglia, they serve as prime cellular candidates for establishing maladaptive synaptic plasticity following drug exposure. Initial studies on astroglia and addiction have placed drug-mediated disruptions in the homeostatic regulation of glutamate as a central aspect of relapse vulnerability. However, the generation of sophisticated tools to study and manipulate astroglia have proven that the interaction between addictive substances, astroglia, and relapse-relevant synaptic plasticity extends far beyond the homeostatic regulation of glutamate. Here we present astroglial systems impacted by drug exposure and discuss how changes in astroglial biology contribute to addiction biology.
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5
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Cocaine use disorder: A look at metabotropic glutamate receptors and glutamate transporters. Pharmacol Ther 2021; 221:107797. [DOI: 10.1016/j.pharmthera.2020.107797] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 11/04/2020] [Indexed: 01/08/2023]
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Caffino L, Mottarlini F, Targa G, Verheij MMM, Homberg J, Fumagalli F. Long access to cocaine self-administration dysregulates the glutamate synapse in the nucleus accumbens core of serotonin transporter knockout rats. Br J Pharmacol 2021; 179:4254-4264. [PMID: 33880773 PMCID: PMC9544393 DOI: 10.1111/bph.15496] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/15/2021] [Accepted: 04/08/2021] [Indexed: 12/22/2022] Open
Abstract
Background and Purpose It is well established that the nucleus accumbens and glutamate play a critical role in the motivation to take drugs of abuse. We have previously demonstrated that rats with ablation of the serotonin (5‐HT) transporter (SERT−/− rats) show increased cocaine intake reminiscent of compulsivity. Experimental Approach By comparing SERT−/− to SERT+/+ rats, we set out to explore whether SERT deletion influences glutamate neurotransmission under control conditions as well as after short access (1 h/session) or long access (6 h/session) to cocaine self‐administration. Key Results Rats were killed at 24 h after the final self‐administration session for ex vivo molecular analyses of the glutamate system (vesicular and glial transporters, post‐synaptic subunits of NMDA and AMPA receptors and their related scaffolding proteins). Such analyses were undertaken in the nucleus accumbens core. In cocaine‐naïve animals, SERT deletion evoked widespread abnormalities in markers of glutamatergic neurotransmission that, overall, indicate a reduction of glutamate signalling. These results suggest that 5‐HT is pivotal for the maintenance of accumbal glutamate homeostasis. We also found that SERT deletion altered glutamate homeostasis mainly after long access, but not short access, to cocaine. Conclusion and Implications Our findings reveal that SERT deletion may sensitize the glutamatergic synapses of the nucleus accumbens core to the long access but not short access, intake of cocaine. LINKED ARTICLES This article is part of a themed issue on New discoveries and perspectives in mental and pain disorders. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.17/issuetoc
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Affiliation(s)
- Lucia Caffino
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Francesca Mottarlini
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Giorgia Targa
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Michel M M Verheij
- Department of Cognitive Neuroscience, Division of Molecular Neurogenetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Judith Homberg
- Department of Cognitive Neuroscience, Division of Molecular Neurogenetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Fabio Fumagalli
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
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7
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Angoa-Pérez M, Kuhn DM. Evidence for Modulation of Substance Use Disorders by the Gut Microbiome: Hidden in Plain Sight. Pharmacol Rev 2021; 73:571-596. [PMID: 33597276 PMCID: PMC7896134 DOI: 10.1124/pharmrev.120.000144] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The gut microbiome modulates neurochemical function and behavior and has been implicated in numerous central nervous system (CNS) diseases, including developmental, neurodegenerative, and psychiatric disorders. Substance use disorders (SUDs) remain a serious threat to the public well-being, yet gut microbiome involvement in drug abuse has received very little attention. Studies of the mechanisms underlying SUDs have naturally focused on CNS reward circuits. However, a significant body of research has accumulated over the past decade that has unwittingly provided strong support for gut microbiome participation in drug reward. β-Lactam antibiotics have been employed to increase glutamate transporter expression to reverse relapse-induced release of glutamate. Sodium butyrate has been used as a histone deacetylase inhibitor to prevent drug-induced epigenetic alterations. High-fat diets have been used to alter drug reward because of the extensive overlap of the circuitry mediating them. This review article casts these approaches in a different light and makes a compelling case for gut microbiome modulation of SUDs. Few factors alter the structure and composition of the gut microbiome more than antibiotics and a high-fat diet, and butyrate is an endogenous product of bacterial fermentation. Drugs such as cocaine, alcohol, opiates, and psychostimulants also modify the gut microbiome. Therefore, their effects must be viewed on a complex background of cotreatment-induced dysbiosis. Consideration of the gut microbiome in SUDs should have the beneficial effects of expanding the understanding of SUDs and aiding in the design of new therapies based on opposing the effects of abused drugs on the host's commensal bacterial community. SIGNIFICANCE STATEMENT: Proposed mechanisms underlying substance use disorders fail to acknowledge the impact of drugs of abuse on the gut microbiome. β-Lactam antibiotics, sodium butyrate, and high-fat diets are used to modify drug seeking and reward, overlooking the notable capacity of these treatments to alter the gut microbiome. This review aims to stimulate research on substance abuse-gut microbiome interactions by illustrating how drugs of abuse share with antibiotics, sodium butyrate, and fat-laden diets the ability to modify the host microbial community.
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Affiliation(s)
- Mariana Angoa-Pérez
- Research and Development Service, John D. Dingell VA Medical Center, and Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan
| | - Donald M Kuhn
- Research and Development Service, John D. Dingell VA Medical Center, and Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan
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Bechard AR, Logan CN, Mesa J, Padovan-Hernandez Y, Blount H, Hodges VL, Knackstedt LA. Role of prefrontal cortex projections to the nucleus accumbens core in mediating the effects of ceftriaxone on cue-induced cocaine seeking. Addict Biol 2021; 26:e12928. [PMID: 32558119 PMCID: PMC7746580 DOI: 10.1111/adb.12928] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 04/11/2020] [Accepted: 05/14/2020] [Indexed: 01/16/2023]
Abstract
Ceftriaxone is an antibiotic that reliably attenuates the reinstatement of cocaine seeking after extinction while preventing the nucleus accumbens (NA) core glutamate efflux that drives reinstatement. However, when rats undergo abstinence without extinction, ceftriaxone attenuates context-primed cocaine seeking but NA core glutamate efflux still increases. Here, we sought to determine if the same would occur when cocaine seeking is prompted by both context and discrete cues (cue-induced seeking) after cocaine abstinence. Male rats self-administered intravenous cocaine accompanied by drug-associated cues (light + tone) for 2 h/day for 14 days. Rats then experienced abstinence with daily handling but no extinction training for 2 weeks. Ceftriaxone (200 mg/kg IP) or vehicle was administered during the last 6 days of abstinence. During a cue-induced cocaine seeking test, microdialysis procedures were conducted. Rats were perfused at the end of the test for later Fos analysis. A separate cohort of rats was infused with the retrograde tracer cholera toxin B in the NA core and underwent the same self-administration and relapse procedures. Ceftriaxone increased baseline glutamate and attenuated both cue-induced cocaine seeking and NA core glutamate efflux during this test. Ceftriaxone reduced Fos expression in regions sending projections to the NA core (prefrontal cortex, basolateral amygdala, ventral tegmental area) and specifically reduced Fos in prelimbic cortex and not infralimbic cortex neurons projecting to the NA core. Thus, when cocaine seeking is induced by drug-associated cues, ceftriaxone is able to attenuate relapse by preventing NA core glutamate efflux, likely through reducing activity in prelimbic NA core-projecting neurons.
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Affiliation(s)
| | - Carly N. Logan
- Department of Psychology, University of Florida, Gainesville, FL 32611
- Center for Addiction Research and Education, University of Florida, Gainesville, FL 32611
| | - Javier Mesa
- Department of Psychology, University of Florida, Gainesville, FL 32611
- Center for Addiction Research and Education, University of Florida, Gainesville, FL 32611
| | - Yasmin Padovan-Hernandez
- Department of Psychology, University of Florida, Gainesville, FL 32611
- Center for Addiction Research and Education, University of Florida, Gainesville, FL 32611
| | - Harrison Blount
- Department of Psychology, University of Florida, Gainesville, FL 32611
| | | | - Lori A. Knackstedt
- Department of Psychology, University of Florida, Gainesville, FL 32611
- Center for Addiction Research and Education, University of Florida, Gainesville, FL 32611
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Smaga I, Gawlińska K, Frankowska M, Wydra K, Sadakierska-Chudy A, Suder A, Piechota M, Filip M. Extinction Training after Cocaine Self-Administration Influences the Epigenetic and Genetic Machinery Responsible for Glutamatergic Transporter Gene Expression in Male Rat Brain. Neuroscience 2020; 451:99-110. [PMID: 33065231 DOI: 10.1016/j.neuroscience.2020.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/29/2020] [Accepted: 10/01/2020] [Indexed: 12/27/2022]
Abstract
Glutamate is a key excitatory neurotransmitter in the central nervous system. The balance of glutamatergic transporter proteins allows long-term maintenance of glutamate homeostasis in the brain, which is impaired during cocaine use disorder. The aim of this study was to investigate changes in the gene expression of SLC1A2 (encoding GLT-1), and SLC7A11 (encoding xCT), in rat brain structures after short-term (3 days) and long-term (10 days) extinction training using microarray analysis and quantitative real-time PCR. Furthermore, we analyzed the expression of genes encoding transcription factors, i.e., NFKB1 and NFKB2 (encoding NF-κB), PAX6, (encoding Pax6), and NFE2L2 (encoding Nrf2), to verify the correlation between changes in glutamatergic transporters and changes in their transcriptional factors and microRNAs (miRNAs; miR-124a, miR-543-3p and miR-342-3p) and confirm the epigenetic mechanism. We found reduced GLT-1 transcript and mRNA level in the prefrontal cortex (PFCTX) and dorsal striatum (DSTR) in rats that had previously self-administered cocaine after 3 days of extinction training, which was associated with downregulation of PAX6 (transcript and mRNA) and NFKB2 (mRNA) level in the PFCTX and with upregulation of miR-543-3p and miR-342-3p in the DSTR. The xCT mRNA level was reduced in the PFCTX and DSTR, and NFE2L2 transcript level in the PFCTX was decreased on the 3rd day of extinction training. In conclusion, 3-day drug-free period modulates GLT-1 and xCT gene expression through genetic and epigenetic mechanisms, and such changes in expression seem to be potential molecular targets for developing a treatment for cocaine-seeking behavior.
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Affiliation(s)
- Irena Smaga
- Maj Institute of Pharmacology Polish Academy of Sciences, Department of Drug Addiction Pharmacology, Smętna 12, PL 31-343 Kraków, Poland.
| | - Kinga Gawlińska
- Maj Institute of Pharmacology Polish Academy of Sciences, Department of Drug Addiction Pharmacology, Smętna 12, PL 31-343 Kraków, Poland
| | - Małgorzata Frankowska
- Maj Institute of Pharmacology Polish Academy of Sciences, Department of Drug Addiction Pharmacology, Smętna 12, PL 31-343 Kraków, Poland
| | - Karolina Wydra
- Maj Institute of Pharmacology Polish Academy of Sciences, Department of Drug Addiction Pharmacology, Smętna 12, PL 31-343 Kraków, Poland
| | - Anna Sadakierska-Chudy
- Maj Institute of Pharmacology Polish Academy of Sciences, Department of Drug Addiction Pharmacology, Smętna 12, PL 31-343 Kraków, Poland
| | - Agata Suder
- Maj Institute of Pharmacology Polish Academy of Sciences, Department of Drug Addiction Pharmacology, Smętna 12, PL 31-343 Kraków, Poland
| | - Marcin Piechota
- Maj Institute of Pharmacology Polish Academy of Sciences, Department of Molecular Neuropharmacology, Smętna 12, 31-343 Kraków, Poland
| | - Małgorzata Filip
- Maj Institute of Pharmacology Polish Academy of Sciences, Department of Drug Addiction Pharmacology, Smętna 12, PL 31-343 Kraków, Poland
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Namba MD, Kupchik YM, Spencer SM, Garcia‐Keller C, Goenaga JG, Powell GL, Vicino IA, Hogue IB, Gipson CD. Accumbens neuroimmune signaling and dysregulation of astrocytic glutamate transport underlie conditioned nicotine-seeking behavior. Addict Biol 2020; 25:e12797. [PMID: 31330570 PMCID: PMC7323912 DOI: 10.1111/adb.12797] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 05/18/2019] [Accepted: 05/23/2019] [Indexed: 12/16/2022]
Abstract
Nicotine self-administration is associated with decreased expression of the glial glutamate transporter (GLT-1) and the cystine-glutamate exchange protein xCT within the nucleus accumbens core (NAcore). N-acetylcysteine (NAC) has been shown to restore these proteins in a rodent model of drug addiction and relapse. However, the specific molecular mechanisms driving its inhibitory effects on cue-induced nicotine reinstatement are unknown. Here, we confirm that extinction of nicotine-seeking behavior is associated with impaired NAcore GLT-1 function and expression and demonstrates that reinstatement of nicotine seeking rapidly enhances membrane fraction GLT-1 expression. Extinction and cue-induced reinstatement of nicotine seeking was also associated with increased tumor necrosis factor alpha (TNFα) and decreased glial fibrillary acidic protein (GFAP) expression in the NAcore. NAC treatment (100 mg/kg/day, i.p., for 5 d) inhibited cue-induced nicotine seeking and suppressed AMPA to NMDA current ratios, suggesting that NAC reduces NAcore postsynaptic excitability. In separate experiments, rats received NAC and an antisense vivo-morpholino to selectively suppress GLT-1 expression in the NAcore during extinction and were subsequently tested for cue-induced reinstatement of nicotine seeking. NAC treatment rescued NAcore GLT-1 expression and attenuated cue-induced nicotine seeking, which was blocked by GLT-1 antisense. NAC also reduced TNFα expression in the NAcore. Viral manipulation of the NF-κB pathway, which is downstream of TNFα, revealed that cue-induced nicotine seeking is regulated by NF-κB pathway signaling in the NAcore independent of GLT-1 expression. Ultimately, these results are the first to show that immunomodulatory mechanisms may regulate known nicotine-induced alterations in glutamatergic plasticity that mediate cue-induced nicotine-seeking behavior.
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Affiliation(s)
- Mark D. Namba
- Department of PsychologyArizona State University Tempe AZ USA
| | - Yonatan M. Kupchik
- Department of Medical NeurobiologyHebrew University of Jerusalem Jerusalem Israel
| | - Sade M. Spencer
- Department of PharmacologyUniversity of Minnesota Minneapolis MN USA
| | | | | | - Gregory L. Powell
- Department of PsychologyArizona State University Tempe AZ USA
- School of Life SciencesArizona State University Tempe AZ USA
| | - Ian A. Vicino
- School of Life SciencesArizona State University Tempe AZ USA
- Center for Immunotherapy, Vaccines, and Virotherapy, Biodesign InstituteArizona State University Tempe AZ USA
| | - Ian B. Hogue
- School of Life SciencesArizona State University Tempe AZ USA
- Center for Immunotherapy, Vaccines, and Virotherapy, Biodesign InstituteArizona State University Tempe AZ USA
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Stennett BA, Knackstedt LA. A Rat Model of Cocaine-Alcohol Polysubstance Use Reveals Altered Cocaine Seeking and Glutamate Levels in the Nucleus Accumbens. Front Neurosci 2020; 14:877. [PMID: 32982672 PMCID: PMC7488193 DOI: 10.3389/fnins.2020.00877] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/28/2020] [Indexed: 12/30/2022] Open
Abstract
Preclinical models of cocaine use disorder are widely utilized to identify neuroadaptations underlying cocaine seeking and to screen medications to reduce seeking. However, while the majority of cocaine users engage in poly-substance use (PSU), a minority of preclinical studies employ PSU models. We previously reported that when rats consume alcohol after daily intravenous cocaine self-administration, nucleus accumbens (NA) core basal glutamate levels are reduced below those of rats that consumed only cocaine, and do not increase during cue + cocaine-primed reinstatement of cocaine-seeking. Here we used the same model of sequential cocaine and alcohol self-administration to test the hypothesis that a similar pattern of glutamate changes would be observed in the NA core prior to and during a cocaine-primed reinstatement test. Rats underwent intravenous cocaine self-administration followed by access to unsweetened alcohol in the home cage for 12 days. Rats underwent a minimum of 12 daily extinction sessions prior to a cocaine-primed reinstatement test conducted during microdialysis procedures. Contrary to our previous work using the same model, here we found that access to alcohol increased cocaine intake and increased responding during early extinction training. We found that as in our previous work, cocaine + alcohol-consuming rats displayed basal glutamate levels below those of rats that self-administered only cocaine. During the cocaine-primed reinstatement test, rats that consumed only cocaine displayed increased glutamate efflux in the NA core while those that consumed cocaine + alcohol did not. These results indicate that preclinical models of PSU should be utilized to develop experimental therapeutics for the reduction of cocaine seeking.
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Affiliation(s)
- Bethany A. Stennett
- Psychology Department, University of Florida, Gainesville, FL, United States
- Center for Addiction Research, University of Florida, Gainesville, FL, United States
| | - Lori A. Knackstedt
- Psychology Department, University of Florida, Gainesville, FL, United States
- Center for Addiction Research, University of Florida, Gainesville, FL, United States
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12
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Logan CN, Bechard AR, Hamor PU, Wu L, Schwendt M, Knackstedt LA. Ceftriaxone and mGlu2/3 interactions in the nucleus accumbens core affect the reinstatement of cocaine-seeking in male and female rats. Psychopharmacology (Berl) 2020; 237:2007-2018. [PMID: 32382781 PMCID: PMC8587483 DOI: 10.1007/s00213-020-05514-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 03/26/2020] [Indexed: 11/25/2022]
Abstract
RATIONALE The beta-lactam antibiotic ceftriaxone reliably attenuates the reinstatement of cocaine seeking. While the restoration of nucleus accumbens core (NA core) GLT-1 expression is necessary for ceftriaxone to attenuate reinstatement, AAV-mediated GLT-1 overexpression is not sufficient to attenuate reinstatement and does not prevent glutamate efflux during reinstatement. AIMS Here, we test the hypothesis that ceftriaxone attenuates reinstatement through interactions with glutamate autoreceptors mGlu2 and mGlu3 in the NA core. METHODS Male and female rats self-administered cocaine for 12 days followed by 2-3 weeks of extinction training. During the last 6-10 days of extinction, rats received ceftriaxone (200 mg/kg IP) or vehicle. In experiment 1, rats were killed, and NA core tissue was biotinylated for assessment of total and surface expression of mGlu2 and mGlu3 via western blotting. In experiment 2, we tested the hypothesis that mGlu2/3 signaling is necessary for ceftriaxone to attenuate cue- and cocaine-primed reinstatement by administering bilateral intra-NA core infusion of mGlu2/3 antagonist LY341495 or vehicle immediately prior to reinstatement testing. RESULTS mGlu2 expression was reduced by cocaine and restored by ceftriaxone. There were no effects of cocaine or ceftriaxone on mGlu3 expression. We observed no effects of estrus on expression of either protein. The antagonism of mGlu2/3 in the NA core during both cue- and cocaine-primed reinstatement tests prevented ceftriaxone from attenuating reinstatement. CONCLUSIONS These results indicate that ceftriaxone's effects depend on mGlu2/3 function and possibly mGlu2 receptor expression. Future work will test this hypothesis by manipulating mGlu2 expression in pathways that project to the NA core.
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Affiliation(s)
- Carly N Logan
- Department of Psychology, University of Florida, 114 Psychology, 945 Center Dr, Gainesville, FL, 32611-2250, USA
- Center for Addiction Research and Education, University of Florida, Gainesville, FL, USA
| | - Allison R Bechard
- Department of Psychology, University of Florida, 114 Psychology, 945 Center Dr, Gainesville, FL, 32611-2250, USA
| | - Peter U Hamor
- Department of Psychology, University of Florida, 114 Psychology, 945 Center Dr, Gainesville, FL, 32611-2250, USA
- Center for Addiction Research and Education, University of Florida, Gainesville, FL, USA
| | - Lizhen Wu
- Department of Psychology, University of Florida, 114 Psychology, 945 Center Dr, Gainesville, FL, 32611-2250, USA
| | - Marek Schwendt
- Department of Psychology, University of Florida, 114 Psychology, 945 Center Dr, Gainesville, FL, 32611-2250, USA
- Center for Addiction Research and Education, University of Florida, Gainesville, FL, USA
| | - Lori A Knackstedt
- Department of Psychology, University of Florida, 114 Psychology, 945 Center Dr, Gainesville, FL, 32611-2250, USA.
- Center for Addiction Research and Education, University of Florida, Gainesville, FL, USA.
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Wang D, Zhang J, Bai Y, Zheng X, Alizamini MM, Shang W, Yang Q, Li M, Li Y, Sui N. Melanin-concentrating hormone in rat nucleus accumbens or lateral hypothalamus differentially impacts morphine and food seeking behaviors. J Psychopharmacol 2020; 34:478-489. [PMID: 31909693 DOI: 10.1177/0269881119895521] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Identifying neural substrates that are differentially affected by drugs of abuse and natural rewards is key to finding a target for an efficacious treatment for substance abuse. Melanin-concentrating hormone is a polypeptide with an inhibitory effect on the mesolimbic dopamine system. Here we test the hypothesis that melanin-concentrating hormone in the lateral hypothalamus and nucleus accumbens shell is differentially involved in the regulation of morphine and food-rewarded behaviors. METHODS Male Sprague-Dawley rats were trained with morphine (5.0 mg/kg, subcutaneously) or food pellets (standard chow, 10-14 g) to induce a conditioned place preference, immediately followed by extinction training. Melanin-concentrating hormone (1.0 µg/side) or saline was infused into the nucleus accumbens shell or lateral hypothalamus before the reinstatement primed by morphine or food, and locomotor activity was simultaneously monitored. As the comparison, melanin-concentrating hormone was also microinjected into the nucleus accumbens shell or lateral hypothalamus before the expression of food or morphine-induced conditioned place preference. RESULTS Microinfusion of melanin-concentrating hormone into the nucleus accumbens shell (but not into the lateral hypothalamus) prevented the reinstatement of morphine conditioned place preference but had no effect on the reinstatement of food conditioned place preference. In contrast, microinfusion of melanin-concentrating hormone into the lateral hypothalamus (but not in the nucleus accumbens shell) inhibited the reinstatement of food conditioned place preference but had no effect on the reinstatement of morphine conditioned place preference. CONCLUSIONS These results suggest a clear double dissociation of melanin-concentrating hormone in morphine/food rewarding behaviors and melanin-concentrating hormone in the nucleus accumbens shell. Melanin-concentrating hormone could be a potential target for therapeutic intervention for morphine abuse without affecting natural rewards.
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Affiliation(s)
- Dongmei Wang
- CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.,Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Jianjun Zhang
- CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.,Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Yunjing Bai
- CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.,Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Xigeng Zheng
- CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.,Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Mirmohammadali M Alizamini
- CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.,Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Wen Shang
- CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.,Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Qingxiong Yang
- School of Karst Science, Guizhou Normal University/State Engineering Technology Institute for Karst Desertification Control, Guiyang, China
| | - Ming Li
- Department of Psychology, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Yonghui Li
- CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.,Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Nan Sui
- CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.,Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
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14
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Stennett BA, Padovan-Hernandez Y, Knackstedt LA. Sequential cocaine-alcohol self-administration produces adaptations in rat nucleus accumbens core glutamate homeostasis that are distinct from those produced by cocaine self-administration alone. Neuropsychopharmacology 2020; 45:441-450. [PMID: 31266052 PMCID: PMC6969168 DOI: 10.1038/s41386-019-0452-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 06/07/2019] [Accepted: 06/21/2019] [Indexed: 12/13/2022]
Abstract
There are currently no FDA-approved medications to reduce cocaine relapse. The majority of preclinical studies aimed at identifying the neurobiology underlying relapse involve the self-administration of cocaine alone, whereas many, if not a majority, of cocaine users engage in polysubstance use. Here we developed a rat model of sequential cocaine and alcohol self-administration to test the hypothesis that this combination produces distinct neuroadaptations relative to those produced by cocaine alone. Male rats underwent intravenous cocaine self-administration (2 h/day) followed by 6 h access to unsweetened alcohol (20% v/v) for 12 days. After extinction training, we assessed surface expression of the glutamate transporter GLT-1 and glutamate efflux in the nucleus accumbens (NA) core during the reinstatement of cocaine-seeking. We also tested the ability of ceftriaxone to attenuate the reinstatement of cocaine-seeking and assessed reinstatement-induced Fos expression in several regions critical for reinstatement. Alcohol consumption did not alter cocaine intake, nor did access to cocaine alter alcohol consumption. However, we noted significant changes in glutamate homeostasis in the NA core of cocaine + alcohol rats relative to rats consuming cocaine alone, such as increased surface GLT-1 expression and a lack of increase in glutamate efflux during reinstatement of cocaine-seeking. A history of cocaine + alcohol also altered patterns of reinstatement-induced Fos expression. These changes likely account for the inability of ceftriaxone to attenuate cocaine relapse in cocaine + alcohol rats, while it does so in rats consuming only cocaine. As such glutamate neuroadaptations are targeted by medications to reduce cocaine relapse, preclinical models should consider polysubstance use.
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Affiliation(s)
- Bethany A Stennett
- Psychology Department, University of Florida, Gainesville, FL, USA
- Center for Addiction Research, University of Florida, Gainesville, FL, USA
| | - Yasmin Padovan-Hernandez
- Psychology Department, University of Florida, Gainesville, FL, USA
- Center for Addiction Research, University of Florida, Gainesville, FL, USA
| | - Lori A Knackstedt
- Psychology Department, University of Florida, Gainesville, FL, USA.
- Center for Addiction Research, University of Florida, Gainesville, FL, USA.
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15
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Siemsen BM, Reichel CM, Leong KC, Garcia-Keller C, Gipson CD, Spencer S, McFaddin JA, Hooker KN, Kalivas PW, Scofield MD. Effects of Methamphetamine Self-Administration and Extinction on Astrocyte Structure and Function in the Nucleus Accumbens Core. Neuroscience 2019; 406:528-541. [PMID: 30926546 PMCID: PMC6545487 DOI: 10.1016/j.neuroscience.2019.03.040] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 03/15/2019] [Accepted: 03/19/2019] [Indexed: 01/01/2023]
Abstract
Astrocytes provide support for neurons, regulate metabolic processes, and influence neuronal communication in a variety of ways, including through the homeostatic regulation of glutamate. Following 2-h cocaine or methamphetamine self-administration (SA) and extinction, rodents display decreased levels of basal glutamate in the nucleus accumbens core (NAcore), which transitions to elevated glutamate levels during drug seeking. We hypothesized that, like cocaine, this glutamate 'overflow' during methamphetamine seeking arises via decreased expression of the astroglial glutamate transporter GLT-1, and withdrawal of perisynaptic astroglial processes (PAPs) from synapses. As expected, methamphetamine self-administration and extinction decreased the level of contact made by PAPs in the NAcore, yet did not impact glutamate uptake, GLT-1 expression, or the general structural characteristics of astrocytes. Interestingly, systemic administration of N-acetylcysteine (NAC), a drug that both upregulates GLT-1 and promotes glial-glutamate release, reduced cued methamphetamine seeking. In order to test the impact of astrocyte activation and the induction of glial glutamate release within the NAcore, we employed astrocyte-specific expression of designer receptors exclusively activated by designer drugs (DREADDs). We show here that acute activation of Gq-coupled DREADDs in this region inhibited cued methamphetamine seeking. Taken together, these data indicate that cued methamphetamine seeking following two-hour SA is not mediated by deficient glutamate clearance in the NAcore, yet can be inhibited by engaging NAcore astrocytes.
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Affiliation(s)
- B M Siemsen
- Department of Anesthesiology and Perioperative Medicine, Medical University of South Carolina, Charleston, SC, USA; Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - C M Reichel
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - K C Leong
- Department of Psychology, Trinity University, San Antonio, TX, USA
| | - C Garcia-Keller
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - C D Gipson
- Department of Psychology, Arizona State University, Tempe, AZ, USA
| | - S Spencer
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - J A McFaddin
- Department of Anesthesiology and Perioperative Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - K N Hooker
- Department of Anesthesiology and Perioperative Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - P W Kalivas
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - M D Scofield
- Department of Anesthesiology and Perioperative Medicine, Medical University of South Carolina, Charleston, SC, USA; Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.
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16
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Bechard AR, Hamor PU, Wu L, Schwendt M, Knackstedt LA. The effects of clavulanic acid and amoxicillin on cue-primed reinstatement of cocaine seeking. Behav Neurosci 2019; 133:247-254. [PMID: 30714803 DOI: 10.1037/bne0000297] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Research using the cocaine self-administration and reinstatement animal model of relapse finds that the beta-lactam antibiotic, ceftriaxone, attenuates cocaine-primed reinstatement of cocaine seeking and upregulates two proteins that regulate glutamate release and reuptake (xCT and GLT-1, respectively) in the nucleus accumbens core (NAc). We tested three compounds with beta-lactam rings for their ability to attenuate cue-primed reinstatement and increase GLT-1 and xCT expression in the NAc and prefrontal cortex (PFC). Rats self-administered intravenous cocaine for 1 hr/day for 7 days then 6 hrs/day for 10 days. Cue-primed reinstatement tests began after 8-9 days of extinction training. Rats received oral vehicle, clavulanic acid (CA), amoxicillin (AMX), or CA + AMX (Augmentin; AUG) for 5 days prior to testing. Only AMX-treated rats demonstrated a reduction of cocaine-seeking that trended toward significance, warranting future investigation of a wider range of doses. In the NAc, GLT-1a expression was reduced in vehicle-treated rats relative to cocaine-naïve controls and was not restored by AMX or AUG. CA-treated rats reinstated more than vehicle-treated rats and exhibited GLT-1a and xCT expression intermediate between cocaine-naïve controls and vehicle-treated cocaine rats. In agreement with our previous work, cocaine did not decrease PFC GLT-1a expression. Cocaine reduced xCT expression in the PFC that was unchanged by any of the three compounds. These results indicate that AMX may be another beta-lactam that attenuates cocaine relapse. Furthermore, the upregulation of both GLT-1 and xCT in the NAc may be needed to attenuate cocaine seeking. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
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Affiliation(s)
| | | | - Lizhen Wu
- Department of Psychology, University of Florida
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17
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Powell GL, Leyrer‐Jackson JM, Goenaga J, Namba MD, Piña J, Spencer S, Stankeviciute N, Schwartz D, Allen NP, Del Franco AP, McClure EA, Olive MF, Gipson CD. Chronic treatment with N-acetylcysteine decreases extinction responding and reduces cue-induced nicotine-seeking. Physiol Rep 2019; 7:e13958. [PMID: 30632301 PMCID: PMC6328917 DOI: 10.14814/phy2.13958] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 11/25/2018] [Accepted: 12/03/2018] [Indexed: 12/20/2022] Open
Abstract
N-acetylcysteine (NAC), a promising glutamatergic therapeutic agent, has shown some clinical efficacy in reducing nicotine use in humans and has been shown to reverse drug-induced changes in glutamatergic neurophysiology. In rats, nicotine-seeking behavior is associated with alterations in glutamatergic plasticity within the nucleus accumbens core (NAcore). Specifically, cue-induced nicotine-seeking is associated with rapid, transient synaptic plasticity (t-SP) in glutamatergic synapses on NAcore medium spiny neurons. The goal of the present study was to determine if NAC reduces nicotine-seeking behavior and reverses reinstatement-associated NAcore glutamatergic alterations. Rats were extinguished from nicotine self-administration, followed by subchronic NAC administration (0 or 100 mg/kg/d) for 4 days prior to cue-induced reinstatement. NAcore synaptic potentiation was measured via dendritic spine morphology and mRNA and protein of relevant glutamatergic genes were quantified. Nicotine-seeking behavior was not reduced by subchronic NAC treatment. Also, NAcore transcript and protein expression of multiple glutamatergic genes, as well as spine morphological measures, were unaffected by subchronic NAC. Finally, chronic NAC treatment (15 days total) during extinction and prior to reinstatement significantly decreased extinction responding and reduced reinstatement of nicotine-seeking compared to vehicle. Together, these results suggest that chronic NAC treatment is necessary for its therapeutic efficacy as a treatment strategy for nicotine addiction and relapse.
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Affiliation(s)
- Gregory L. Powell
- Department of PsychologyArizona State UniversityTempeArizona
- School of Life SciencesArizona State UniversityTempeArizona
| | | | | | - Mark D. Namba
- Department of PsychologyArizona State UniversityTempeArizona
| | - Jose Piña
- Department of PsychologyArizona State UniversityTempeArizona
| | - Sade Spencer
- Department of NeuroscienceMedical University of South CarolinaCharlestonSC
| | | | - Danielle Schwartz
- Department of NeuroscienceMedical University of South CarolinaCharlestonSC
| | - Nicholas P. Allen
- School of Dental MedicineLake Erie College of Osteopathic MedicineBradentonFlorida
| | | | - Erin A. McClure
- Department of PsychiatryMedical University of South CarolinaCharlestonSouth Carolina
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18
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Schwendt M, Shallcross J, Hadad NA, Namba MD, Hiller H, Wu L, Krause EG, Knackstedt LA. A novel rat model of comorbid PTSD and addiction reveals intersections between stress susceptibility and enhanced cocaine seeking with a role for mGlu5 receptors. Transl Psychiatry 2018; 8:209. [PMID: 30291225 PMCID: PMC6173705 DOI: 10.1038/s41398-018-0265-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 08/22/2018] [Accepted: 09/10/2018] [Indexed: 12/12/2022] Open
Abstract
PTSD is highly comorbid with cocaine use disorder (CUD), and cocaine users with PTSD + CUD are more resistant to treatment. Here we sought to develop a rat model of PTSD + CUD in order to identify the neurobiological changes underlying such comorbidity and screen potential medications for reducing cocaine seeking in the PTSD population. We utilized a predator scent stress model of PTSD, wherein rats received a single exposure to the fox pheromone 2,5-dihydro-2,4,5-trimethylthiazoline (TMT). One week after TMT exposure, stress-susceptible (susceptible), intermediate, and resilient phenotypes were detected and were consistent with behavioral, corticosterone, and gene expression profiles 3 weeks post TMT. We assessed phenotypic differences in cocaine self-administration, extinction, and cue-primed reinstatement. Susceptible rats exhibited deficits in extinction learning and increased cue-primed reinstatement that was not prevented by Ceftriaxone, an antibiotic that consistently attenuates the reinstatement of cocaine seeking. TMT-exposed resilient rats displayed increased mGlu5 gene expression in the amygdala and medial prefrontal cortex and did not display the enhanced cocaine seeking observed in susceptible rats. Combined treatment with the mGlu5 positive allosteric modulator 3-Cyano-N-(1,3-diphenyl-1 H-pyrazol-5-yl)benzamide (CDPPB), fear extinction, and ceftriaxone prevented the reinstatement of cocaine seeking in susceptible rats with fear extinction an important mediating condition. These results highlight the need for animal models of PTSD to consider stress-responsivity, as only a subset of trauma-exposed individuals develop PTSD and these individuals likely exhibit distinct neurobiological changes compared with trauma-exposed populations who are resilient to stress. This work further identifies glutamate homeostasis and mGlu5 as a target for treating relapse in comorbid PTSD-cocaine addiction.
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Affiliation(s)
- Marek Schwendt
- Psychology Department, University of Florida, Gainesville, FL, 32611, USA. .,Center for Addiction Research and Education, University of Florida, Gainesville, FL, 32610, USA.
| | - John Shallcross
- 0000 0004 1936 8091grid.15276.37Psychology Department, University of Florida, Gainesville, FL 32611 USA
| | - Natalie A. Hadad
- 0000 0004 1936 8091grid.15276.37Psychology Department, University of Florida, Gainesville, FL 32611 USA
| | - Mark D. Namba
- 0000 0004 1936 8091grid.15276.37Psychology Department, University of Florida, Gainesville, FL 32611 USA
| | - Helmut Hiller
- 0000 0004 1936 8091grid.15276.37Department of Pharmacodynamics, University of Florida, Gainesville, FL 32610 USA
| | - Lizhen Wu
- 0000 0004 1936 8091grid.15276.37Psychology Department, University of Florida, Gainesville, FL 32611 USA
| | - Eric G. Krause
- 0000 0004 1936 8091grid.15276.37Department of Pharmacodynamics, University of Florida, Gainesville, FL 32610 USA
| | - Lori A. Knackstedt
- 0000 0004 1936 8091grid.15276.37Psychology Department, University of Florida, Gainesville, FL 32611 USA ,0000 0004 1936 8091grid.15276.37Center for Addiction Research and Education, University of Florida, Gainesville, FL 32610 USA
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19
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Pál B. Involvement of extrasynaptic glutamate in physiological and pathophysiological changes of neuronal excitability. Cell Mol Life Sci 2018; 75:2917-2949. [PMID: 29766217 PMCID: PMC11105518 DOI: 10.1007/s00018-018-2837-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/27/2018] [Accepted: 05/07/2018] [Indexed: 12/14/2022]
Abstract
Glutamate is the most abundant neurotransmitter of the central nervous system, as the majority of neurons use glutamate as neurotransmitter. It is also well known that this neurotransmitter is not restricted to synaptic clefts, but found in the extrasynaptic regions as ambient glutamate. Extrasynaptic glutamate originates from spillover of synaptic release, as well as from astrocytes and microglia. Its concentration is magnitudes lower than in the synaptic cleft, but receptors responding to it have higher affinity for it. Extrasynaptic glutamate receptors can be found in neuronal somatodendritic location, on astroglia, oligodendrocytes or microglia. Activation of them leads to changes of neuronal excitability with different amplitude and kinetics. Extrasynaptic glutamate is taken up by neurons and astrocytes mostly via EAAT transporters, and astrocytes, in turn metabolize it to glutamine. Extrasynaptic glutamate is involved in several physiological phenomena of the central nervous system. It regulates neuronal excitability and synaptic strength by involving astroglia; contributing to learning and memory formation, neurosecretory and neuromodulatory mechanisms, as well as sleep homeostasis.The extrasynaptic glutamatergic system is affected in several brain pathologies related to excitotoxicity, neurodegeneration or neuroinflammation. Being present in dementias, neurodegenerative and neuropsychiatric diseases or tumor invasion in a seemingly uniform way, the system possibly provides a common component of their pathogenesis. Although parts of the system are extensively discussed by several recent reviews, in this review I attempt to summarize physiological actions of the extrasynaptic glutamate on neuronal excitability and provide a brief insight to its pathology for basic understanding of the topic.
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Affiliation(s)
- Balázs Pál
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, Debrecen, 4012, Hungary.
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