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Geisler CE, Décarie-Spain L, Loh MK, Trumbauer W, Gaisinsky J, Klug ME, Pelletier C, Davis JF, Schmidt HD, Roitman MF, Kanoski SE, Hayes MR. Amylin Modulates a Ventral Tegmental Area-to-Medial Prefrontal Cortex Circuit to Suppress Food Intake and Impulsive Food-Directed Behavior. Biol Psychiatry 2024; 95:938-950. [PMID: 37517705 DOI: 10.1016/j.biopsych.2023.07.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 06/23/2023] [Accepted: 07/10/2023] [Indexed: 08/01/2023]
Abstract
BACKGROUND A better understanding of the neural mechanisms regulating impaired satiety to palatable foods is essential to treat hyperphagia linked with obesity. The satiation hormone amylin signals centrally at multiple nuclei including the ventral tegmental area (VTA). VTA-to-medial prefrontal cortex (mPFC) projections encode food reward information to influence behaviors including impulsivity. We hypothesized that modulation of VTA-to-mPFC neurons underlies amylin-mediated decreases in palatable food-motivated behaviors. METHODS We used a variety of pharmacological, behavioral, genetic, and viral approaches (n = 4-16/experiment) to investigate the anatomical and functional circuitry of amylin-controlled VTA-to-mPFC signaling in rats. RESULTS To first establish that VTA amylin receptor (calcitonin receptor) activation can modulate mPFC activity, we showed that intra-VTA amylin decreased food-evoked mPFC cFos. VTA amylin delivery also attenuated food-directed impulsive behavior, implicating VTA amylin signaling as a regulator of mPFC functions. Palatable food activates VTA dopamine and mPFC neurons. Accordingly, dopamine receptor agonism in the mPFC blocked the hypophagic effect of intra-VTA amylin, and VTA amylin injection reduced food-evoked phasic dopamine levels in the mPFC, supporting the idea that VTA calcitonin receptor activation decreases dopamine release in the mPFC. Surprisingly, calcitonin receptor expression was not found on VTA-to-mPFC projecting neurons but was instead found on GABAergic (gamma-aminobutyric acidergic) interneurons in the VTA that provide monosynaptic inputs to this pathway. Blocking intra-VTA GABA signaling, through GABA receptor antagonists and DREADD (designer receptor exclusively activated by designer drugs)-mediated GABAergic neuronal silencing, attenuated intra-VTA amylin-induced hypophagia. CONCLUSIONS These results indicate that VTA amylin signaling stimulates GABA-mediated inhibition of dopaminergic projections to the mPFC to mitigate impulsive consumption of palatable foods.
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Affiliation(s)
- Caroline E Geisler
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Léa Décarie-Spain
- Department of Biological Sciences, Human and Evolutionary Biology Section, University of Southern California, Los Angeles, California
| | - Maxine K Loh
- Department of Psychology, University of Illinois at Chicago, Chicago, Illinois
| | - Wolf Trumbauer
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jane Gaisinsky
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Molly E Klug
- Department of Biological Sciences, Human and Evolutionary Biology Section, University of Southern California, Los Angeles, California
| | - Caitlyn Pelletier
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jon F Davis
- Novo Nordisk Research Center Seattle, Seattle, Washington
| | - Heath D Schmidt
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Mitchell F Roitman
- Department of Psychology, University of Illinois at Chicago, Chicago, Illinois
| | - Scott E Kanoski
- Department of Biological Sciences, Human and Evolutionary Biology Section, University of Southern California, Los Angeles, California
| | - Matthew R Hayes
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, Pennsylvania.
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Kim Y, Jeon SJ, Gonzales EL, Shin D, Remonde CG, Ahn T, Shin CY. Pirenperone relieves the symptoms of fragile X syndrome in Fmr1 knockout mice. Sci Rep 2022; 12:20966. [PMID: 36470953 PMCID: PMC9723111 DOI: 10.1038/s41598-022-25582-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022] Open
Abstract
Fragile X syndrome (FXS) is a neurodevelopmental disorder that is caused by the loss of Fragile X-linked mental retardation protein (FMRP), an RNA binding protein that can bind and recognize different RNA structures and regulate the target mRNAs' translation involved in neuronal synaptic plasticity. Perturbations of this gene expression network have been related to abnormal behavioral symptoms such as hyperactivity, and impulsivity. Considering the roles of FMRP in the modulation of mRNA translation, we investigated the differentially expressed genes which might be targeted to revert to normal and ameliorate behavioral symptoms. Gene expression data was analyzed and used the connectivity map (CMap) to understand the changes in gene expression in FXS and predict the effective drug candidates. We analyzed the GSE7329 dataset that had 15 control and 8 FXS patients' lymphoblastoid samples. Among 924 genes, 42 genes were selected as signatures for CMap analysis, and 24 associated drugs were found. Pirenperone was selected as a potential drug candidate for FXS for its possible antipsychotic effect. Treatment of pirenperone increased the expression level of Fmr1 gene. Moreover, pirenperone rescued the behavioral deficits in Fmr1 KO mice including hyperactivity, spatial memory, and impulsivity. These results suggest that pirenperone is a new drug candidate for FXS, which should be verified in future studies.
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Affiliation(s)
- Yujeong Kim
- grid.258676.80000 0004 0532 8339Department of Pharmacology and Department of Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul, 05029 Republic of Korea
| | - Se Jin Jeon
- grid.412357.60000 0004 0533 2063Department of Integrative Biotechnology, College of Science and Technology, Sahmyook University, Seoul, 01795 Republic of Korea
| | - Edson Luck Gonzales
- grid.258676.80000 0004 0532 8339Department of Pharmacology and Department of Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul, 05029 Republic of Korea
| | - Dongpil Shin
- grid.258676.80000 0004 0532 8339Department of Pharmacology and Department of Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul, 05029 Republic of Korea
| | - Chilly Gay Remonde
- grid.258676.80000 0004 0532 8339Department of Pharmacology and Department of Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul, 05029 Republic of Korea
| | - TaeJin Ahn
- grid.411957.f0000 0004 0647 2543Department of Life Science, Handong Global University, Nehemiah 36, Handong-ro 558, Pohang, 37554 Republic of Korea
| | - Chan Young Shin
- grid.258676.80000 0004 0532 8339Department of Pharmacology and Department of Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul, 05029 Republic of Korea
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Jiang K, Liu X, Su R. Contrasting effects of DOI and lisuride on impulsive decision-making in delay discounting task. Psychopharmacology (Berl) 2022; 239:3551-3565. [PMID: 36107207 DOI: 10.1007/s00213-022-06229-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 08/28/2022] [Indexed: 11/25/2022]
Abstract
RATIONALE The 5-HT2A receptor is the major target of classic hallucinogens. Both DOI (2,5-dimethoxy-4-iodoamphetamine) and lisuride act at 5-HT2A receptors, and lisuride shares comparable affinity with DOI and acts as a partial agonist at 5-HT2A receptors. However, not like DOI, lisuride lacks hallucinogenic properties. Impulsive decision-making refers to the preference for an immediate small reinforcer (SR) over a delayed large reinforcer (LR). OBJECTIVES The current study aims to compare the effects of DOI and lisuride on impulsive decision-making and further to investigate the possible receptor mechanisms responsible for the actions of the two drugs. METHODS Impulsive decision-making was evaluated in male Sprague-Dawley rats by the percentage of choice for the LR in delay discounting task (DDT). Delay to the LR changed in an ascending order (0, 4, 8, 16, and 32 s) across one session. RESULTS DOI (0.5 and 1.0 mg/kg) increased impulsive decision-making, and the effects of DOI (1.0 mg/kg) were blocked by the 5-HT2A receptor antagonist ketanserin (1.0 mg/kg) rather than the 5-HT2C receptor antagonist SB-242084 (1.0 mg/kg). Contrarily, lisuride (0.1, 0.3, and 0.5 mg/kg) decreased impulsive decision-making. The effects of lisuride (0.3 mg/kg) were not antagonized by ketanserin (1.0 mg/kg), selective 5-HT1A antagonist WAY-100635 (1.0 mg/kg), or selective dopamine D4 receptor antagonist L-745870 (1.0 mg/kg) but were attenuated by the selective dopamine D2/D3 receptor antagonist tiapride (40 mg/kg). CONCLUSIONS DOI and lisuride have contrasting effects on impulsive decision-making via distinct receptors. DOI-induced increase of impulsivity is mediated by the 5-HT2A receptor, while lisuride-induced inhibition of impulsivity is regulated by the dopamine D2/D3 receptor.
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Affiliation(s)
- Kaili Jiang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Xiaoyan Liu
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China.
| | - Ruibin Su
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China.
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Girotti M, Carreno FR, Morilak DA. Role of Orbitofrontal Cortex and Differential Effects of Acute and Chronic Stress on Motor Impulsivity Measured With 1-Choice Serial Reaction Time Test in Male Rats. Int J Neuropsychopharmacol 2022; 25:1026-1036. [PMID: 36087292 PMCID: PMC9743967 DOI: 10.1093/ijnp/pyac062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 09/08/2022] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Deficits in motor impulsivity, that is, the inability to inhibit a prepotent response, are frequently observed in psychiatric conditions. Several studies suggest that stress often correlates with higher impulsivity. Among the brain areas affected by stress, the orbitofrontal cortex (OFC) is notable because of its role in impulse control. OFC subregions with unique afferent and efferent circuitry play distinct roles in impulse control, yet it is not clear what OFC subregions are engaged during motor impulsivity tasks. METHODS In this study we used a rodent test of motor impulsivity, the 1-choice serial reaction time test, to explore activation of OFC subregions either during a well-learned motor impulsivity task or in a challenge task with a longer wait time that increases premature responding. We also examined the effects of acute inescapable stress, chronic intermittent cold stress and chronic unpredictable stress on motor impulsivity. RESULTS Fos expression increased in the lateral OFC and agranular insular cortex during performance in both the mastered and challenge conditions. In the ventral OFC, Fos expression increased only during challenge, and within the medial OFC, Fos was not induced in either condition. Inescapable stress produced a transient effect on premature responses in the mastered task, whereas chronic intermittent cold stress and chronic unpredictable stress altered premature responses in both conditions in ways specific to each stressor. CONCLUSIONS These results suggest that different OFC subregions have different roles in motor impulse control, and the effects of stress vary depending on the nature and duration of the stressor.
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Affiliation(s)
- Milena Girotti
- Correspondence: Milena Girotti, PhD, Department of Pharmacology, Mail Code 7764, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA ()
| | - Flavia R Carreno
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - David A Morilak
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA,South Texas Veterans Health Care System, San Antonio, TX, USA
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Abbott MS, Seaman RW, Doyle MR, Maguire DR, Rice KC, Collins GT. Interactions between impulsivity and MDPV self-administration in rats. Addict Biol 2022; 27:e13168. [PMID: 35470552 PMCID: PMC9425731 DOI: 10.1111/adb.13168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 12/21/2021] [Accepted: 03/08/2022] [Indexed: 11/28/2022]
Abstract
Synthetic cathinones, such as 3,4-methylenedioxypyrovalerone (MDPV), are recreational drugs of abuse often identified in 'bath salts' preparations. Humans report compulsive patterns of bath salts use, and previous work suggests that a subset of rats develop unusually high levels of MDPV self-administration. This study aims to test the hypothesis that high levels of impulsivity (e.g., inability to withhold responding for a sucrose reward) will predispose rats to high levels of MDPV self-administration relative to rats with lower levels of impulsivity. The 1-choice serial reaction time task (1-CSRTT) was used to assess impulsivity (i.e., premature responding) in 10 female and 10 male Sprague Dawley rats. Rats were then allowed to self-administer 0.032 mg/kg/inf MDPV or 0.32 mg/kg/inf cocaine, after which full dose-response curves for MDPV (0.001-0.1 mg/kg/inf) or cocaine (0.01-1 mg/kg/inf) were generated under a FR5 schedule of reinforcement. After a history of self-administering MDPV or cocaine, impulsivity was reassessed under the 1-CSRTT, prior to evaluating the acute effects of MDPV (0.032-0.32 mg/kg) or cocaine (0.1-1 mg/kg) on impulsivity. Level of impulsivity was not correlated with subsequent levels of either MDPV or cocaine self-administration, and level of drug self-administration was also not correlated with subsequent levels of impulsivity, although acute administration of MDPV and cocaine did increase premature responding. In failing to find direct relationships between either impulsivity and subsequent drug-taking behaviour, or drug-taking behaviour and subsequent assessments of impulsivity, these findings highlight the complexity inherent in the associations between impulsive behaviour and drug-taking behaviour in both animal models and humans.
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Affiliation(s)
- Megan S. Abbott
- Department of Pharmacology The University of Texas Health Science Center at San Antonio San Antonio Texas USA
| | - Robert W. Seaman
- Department of Pharmacology The University of Texas Health Science Center at San Antonio San Antonio Texas USA
- South Texas Veterans Health Care System San Antonio Texas USA
| | - Michelle R. Doyle
- Department of Pharmacology The University of Texas Health Science Center at San Antonio San Antonio Texas USA
- South Texas Veterans Health Care System San Antonio Texas USA
| | - David R. Maguire
- Department of Pharmacology The University of Texas Health Science Center at San Antonio San Antonio Texas USA
| | - Kenner C. Rice
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch NIDA and NIAAA Bethesda Maryland USA
| | - Gregory T. Collins
- Department of Pharmacology The University of Texas Health Science Center at San Antonio San Antonio Texas USA
- South Texas Veterans Health Care System San Antonio Texas USA
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Fletcher PJ, Li Z, Ji X, Higgins GA, Funk D, Lê A. Effects of pimavanserin and lorcaserin on alcohol self-administration and reinstatement in male and female rats. Neuropharmacology 2022; 215:109150. [DOI: 10.1016/j.neuropharm.2022.109150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 04/25/2022] [Accepted: 05/23/2022] [Indexed: 11/27/2022]
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Schetz D, Schetz A, Kocić I. A retrospective analysis of the "Neverending Trip" after administration of a potent full agonist of 5-HT2A receptor - 25I-NBOMe. Biomed Pharmacother 2022; 146:112295. [PMID: 34980551 DOI: 10.1016/j.biopha.2021.112295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 09/30/2021] [Accepted: 10/05/2021] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND 5-HT2A receptor (e.g. 25I-NBOMe) agonists not only pose risks of acute intoxication but also long-term effects and significant adverse reactions, e.g. hallucinogen persisting perception disorder (HPPD), derealization, and depersonalization. AIMS We evaluated the risk associated with single and repeated use of 25I-NBOMe. We aimed to identify factors that may increase the risk of HPPD, increase its severity and determine the time when the first symptoms appear. Herein, we report the first extensive evaluation of 25I-NBOMe-induced HPPD. METHOD We assessed all reports (58) collected by The Pomeranian Pharmacovigilance Centre (PPC) from 2013 to 2020. RESULTS The study included a total of 58 reports of adverse reactions caused by 25I-NBOMe. In the case of 15 reports (in patients aged 19-26 years), symptoms persisted many months after the discontinuation of 25I-NBOMe. The most common were: pseudohallucinations, bizarre delusions, derealizations and in some cases development or worsening of depression has been diagnosed. HPPD-like symptoms were most common in patients who took the drug regularly (i.e., several times a month). The risk of HPPD-like symptoms is higher in patients who have severe visual pseudohallucinations, severe bizarre delusions, derealization and/or depersonalization onset immediately after taking the drug. Recurrence of HPPD symptoms may be provoked by many factors, however, there is some cases there is no apparent reason. HPPD after 25I-NBOMe use can last from 2 months up to 2 years. In some patients, pharmacological treatment was necessary due to 25I-NBOMe-induced HPPD and depression. CONCLUSIONS The study showed long-lasting effects after 25I-NBOMe administration and allowed for the determination of HPPD risk factors.
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Affiliation(s)
- Daria Schetz
- Department of Pharmacology, Medical University of Gdańsk, Poland.
| | - Adriana Schetz
- Institute of Philosophy and Cognitive Science, University of Szczecin, Poland
| | - Ivan Kocić
- Department of Pharmacology, Medical University of Gdańsk, Poland
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Tschetter KE, Callahan LB, Flynn SA, Rahman S, Beresford TP, Ronan PJ. Early life stress and susceptibility to addiction in adolescence. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2021; 161:277-302. [PMID: 34801172 DOI: 10.1016/bs.irn.2021.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Early life stress (ELS) is a risk factor for developing a host of psychiatric disorders. Adolescence is a particularly vulnerable period for the onset of these disorders and substance use disorders (SUDs). Here we discuss ELS and its effects in adolescence, especially SUDs, and their correlates with molecular changes to signaling systems in reward and stress neurocircuits. Using a maternal separation (MS) model of neonatal ELS, we studied a range of behaviors that comprise a "drug-seeking" phenotype. We then investigated potential mechanisms underlying the development of this phenotype. Corticotropin releasing factor (CRF) and serotonin (5-HT) are widely believed to be involved in "stress-induced" disorders, including addiction. Here, we show that ELS leads to the development of a drug-seeking phenotype indicative of increased susceptibility to addiction and concomitant sex-dependent upregulation of CRF and 5-HT system components throughout extended brain reward/stress neurocircuits.
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Affiliation(s)
- K E Tschetter
- Research Service, Sioux Falls VA Healthcare System, Sioux Falls, SD, United States; Department of Psychiatry and Basic Biomedical Sciences, University of South Dakota Sanford School of Medicine, Sioux Falls, SD, United States; Division of Basic Biomedical Sciences, University of South Dakota Sanford School of Medicine, Sioux Falls, SD, United States
| | - L B Callahan
- Research Service, Sioux Falls VA Healthcare System, Sioux Falls, SD, United States; Department of Psychiatry and Basic Biomedical Sciences, University of South Dakota Sanford School of Medicine, Sioux Falls, SD, United States; Division of Basic Biomedical Sciences, University of South Dakota Sanford School of Medicine, Sioux Falls, SD, United States
| | - S A Flynn
- Department of Psychiatry and Basic Biomedical Sciences, University of South Dakota Sanford School of Medicine, Sioux Falls, SD, United States
| | - S Rahman
- Department of Pharmaceutical Sciences, South Dakota State University, Brookings, SD, United States
| | - T P Beresford
- Laboratory for Clinical and Translational Research in Psychiatry, Rocky Mountain Regional, VA Medical Center, Aurora, CO, United States; Department of Psychiatry, University of Colorado School of Medicine, Aurora, CO, United States
| | - P J Ronan
- Research Service, Sioux Falls VA Healthcare System, Sioux Falls, SD, United States; Department of Psychiatry and Basic Biomedical Sciences, University of South Dakota Sanford School of Medicine, Sioux Falls, SD, United States; Division of Basic Biomedical Sciences, University of South Dakota Sanford School of Medicine, Sioux Falls, SD, United States; Laboratory for Clinical and Translational Research in Psychiatry, Rocky Mountain Regional, VA Medical Center, Aurora, CO, United States.
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Suchting R, Green CE, de Dios C, Vincent J, Moeller FG, Lane SD, Schmitz JM. Citalopram for treatment of cocaine use disorder: A Bayesian drop-the-loser randomized clinical trial. Drug Alcohol Depend 2021; 228:109054. [PMID: 34600245 PMCID: PMC8595787 DOI: 10.1016/j.drugalcdep.2021.109054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 09/08/2021] [Accepted: 09/09/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Medication development research for cocaine use disorder (CUD) has been a longstanding goal in addiction research, but has not resulted in an FDA-approved treatment. Rising cocaine use rates underscore the need for efficient adaptive designs. This study compared differences between two doses of the selective serotonin reuptake inhibitor (SSRI) citalopram (versus placebo) on duration of cocaine abstinence and applied adaptive decision rules to select the 'best efficacy' dose. METHODS A double-blind, placebo-controlled, randomized Bayesian drop-the-loser (DTL) trial with three arms compared placebo to citalopram 20 mg and 40 mg. Adults (N = 107) with CUD attended thrice-weekly clinic visits for 9 weeks. The primary outcome was longest duration of abstinence (LDA), based on continuous cocaine-negative urine drug screens (UDS). The secondary outcome was probability of cocaine-negative UDS during treatment. A planned interim analysis performed at approximately 50% of recruitment dropped the least-effective active medication. Bayesian inference was used for all analyses with a pre-specified posterior probability (PP) threshold PP ≥ 95% considered statistically reliable evidence RESULTS: Citalopram 40 mg satisfied interim efficacy criteria and was retained for the second half of the trial. For LDA, analyses indicated PP = 82% and PP = 65% of benefit for 40 mg and 20 mg, respectively (each relative to placebo). The odds of having cocaine-negative UDS decreased in all groups over 9 weeks but remained higher for 40 mg (PP = 97.4%) CONCLUSIONS: Neither dose met the 95% PP threshold for the primary outcome; however, 40 mg provided moderate-to-strong evidence for positive effects on LDA and cocaine-negative UDS. The 40 mg dose was declared the "winner" in this DTL trial.
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Affiliation(s)
- Robert Suchting
- Faillace Department of Psychiatry and Behavioral Sciences, UTHealth McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA.
| | - Charles E. Green
- Department of Pediatrics – Center for Clinical Research and Evidence-Based Medicine, UTHealth McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA,MD Anderson – UTHealth Graduate School of Biomedical Sciences, Program in Neuroscience, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Constanza de Dios
- Faillace Department of Psychiatry and Behavioral Sciences, UTHealth McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Jessica Vincent
- Faillace Department of Psychiatry and Behavioral Sciences, UTHealth McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA
| | | | - Scott D. Lane
- Faillace Department of Psychiatry and Behavioral Sciences, UTHealth McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Joy M. Schmitz
- Faillace Department of Psychiatry and Behavioral Sciences, UTHealth McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA
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Madden JT, Reyna NC, Goranson EV, Gonzalez TA, Zavala AR, Pentkowski NS. Blocking serotonin 2A (5-HT 2A) receptors attenuates the acquisition of methamphetamine-induced conditioned place preference in adult female rats. Behav Brain Res 2021; 415:113521. [PMID: 34391796 DOI: 10.1016/j.bbr.2021.113521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/29/2021] [Accepted: 08/09/2021] [Indexed: 11/19/2022]
Abstract
Methamphetamine withdrawal can induce intense cravings leading to relapse. Contexts/cues paired with chronic methamphetamine use develop incentive motivational properties, promoting future drug-seeking and taking behavior. Research has shown that, in adult male rats, the selective 5-HT2A receptor antagonist M100907 attenuates the acquisition of methamphetamine-induced conditioned place preference (CPP), a measure that examines conditioned associations between the rewarding properties of drugs and contexts. However, these findings have not been extended to adult female rats. The present study investigated the effects of M100907 on the acquisition of methamphetamine-CPP in adult female rats. During conditioning, rats were administered M100907 (0, 0.025, 0.25 mg/kg, i.p.) 15 min before methamphetamine (1 mg/kg, i.p.) and then placed into their initially non-preferred chamber for 30 min, or administered saline and placed into their initially preferred chamber for 30 min. Conditioning sessions were separated by four hours. Following four days of conditioning, the effects of M100907 on the acquisition of methamphetamine-CPP were assessed during a 15 min drug-free test trial. Pretreatment with M100907 dose-dependently attenuated the acquisition of methamphetamine-induced CPP. Blocking 5-HT2A receptors with a low dose of the selective antagonist M100907 attenuated the rewarding effects of methamphetamine in adult female rats. These data provide further evidence that the 5-HT2A receptor subtype is involved in the behavioral effects of methamphetamine.
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Affiliation(s)
- John T Madden
- Department of Psychology, University of New Mexico, Albuquerque, NM, USA
| | - Nicole C Reyna
- Department of Psychology, University of New Mexico, Albuquerque, NM, USA
| | - Emerald V Goranson
- Department of Psychology, University of New Mexico, Albuquerque, NM, USA
| | - Tiffany A Gonzalez
- Department of Psychology, California State University, Long Beach, Long Beach, CA, USA
| | - Arturo R Zavala
- Department of Psychology, California State University, Long Beach, Long Beach, CA, USA
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Madden JT, Reyna NC, Pentkowski NS. Antagonizing serotonin 2A (5-HT 2A) receptors attenuates methamphetamine-induced reward and blocks methamphetamine-induced anxiety-like behaviors in adult male rats. Drug Alcohol Depend 2020; 215:108178. [PMID: 32739601 DOI: 10.1016/j.drugalcdep.2020.108178] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 06/04/2020] [Accepted: 07/01/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND Methamphetamine is a highly addictive and abused psychostimulant. Symptoms of methamphetamine withdrawal including drug craving and anxiety that can drive relapse. Currently, there is no FDA approved treatment for methamphetamine use disorder, highlighting the need for research examining the neural mechanisms underlying psychostimulant-induced behaviors. Research indicates that the 5-HT2A receptor antagonist M100907 attenuates several psychostimulant-induced behaviors, including conditioned place preference (CPP). However, these findings have not been extended to methamphetamine. The present study investigated the effects of M100907 on acquisition of methamphetamine-CPP and methamphetamine-induced anxiety-like behavior. METHODS Adult male rats were tested across eight consecutive days. Prior to methamphetamine administration (0 or 1 mg/kg, i.p.), rats were pretreated with their assigned dose of M100907 (0, 0.0025 .025 or 0.25 mg/kg, i.p.) and were placed into their initially non-preferred chamber. After four methamphetamine conditioning sessions, the effects of M100907 on methamphetamine-induced CPP were assessed. Following CPP testing, rats were screened for anxiety-like behaviors in the elevated plus-maze. RESULTS Pretreatment with M100907 attenuated methamphetamine-induced CPP without producing any observable rewarding or aversive effects in methamphetamine naïve rats. Additionally, M100907 blocked methamphetamine-induced increases in anxiety-like behavior and attenuated some indices of anxiety in methamphetamine naïve rats. CONCLUSIONS Results suggest that blocking 5-HT2A receptors with the selective antagonist M100907 attenuates the rewarding effects of methamphetamine and does not produce any rewarding or aversive effects alone. Further, M100907 pretreatment blocked the anxiety-inducing effects of methamphetamine. Collectively, these data suggest that the 5-HT2A receptor subtype represents a novel target for treating methamphetamine use disorder.
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Affiliation(s)
- John T Madden
- Department of Psychology, University of New Mexico, Albuquerque, New Mexico, USA
| | - Nicole C Reyna
- Department of Psychology, University of New Mexico, Albuquerque, New Mexico, USA
| | - Nathan S Pentkowski
- Department of Psychology, University of New Mexico, Albuquerque, New Mexico, USA.
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The synthetic cathinone 3,4-methylenedioxypyrovalerone increases impulsive action in rats. Behav Pharmacol 2020; 31:309-321. [DOI: 10.1097/fbp.0000000000000548] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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13
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Sholler DJ, Merritt CR, Davis-Reyes BD, Golovko G, Anastasio NC, Cunningham KA. Inherent Motor Impulsivity Associates with Specific Gene Targets in the Rat Medial Prefrontal Cortex. Neuroscience 2020; 435:161-173. [PMID: 32240784 DOI: 10.1016/j.neuroscience.2020.03.045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 03/22/2020] [Accepted: 03/26/2020] [Indexed: 01/23/2023]
Abstract
High impulsivity characterizes a myriad of neuropsychiatric diseases, and identifying targets for neuropharmacological intervention to reduce impulsivity could reveal transdiagnostic treatment strategies. Motor impulsivity (impulsive action) reflects in part the failure of "top-down" executive control by the medial prefrontal cortex (mPFC). The present study profiled the complete set of mRNA molecules expressed from genes (transcriptome) in the mPFC of male, outbred rats stably expressing high (HI) or low (LI) motor impulsivity based upon premature responses in the 1-choice serial reaction time (1-CSRT) task. RNA-sequencing identified expression of 18 genes that was higher in the mPFC of HI vs. LI rats. Functional gene enrichment revealed that biological processes related to calcium homeostasis and G protein-coupled receptor (GPCR) signaling pathways, particularly glutamatergic, were overrepresented in the mPFC of HI vs. LI rats. Transcription factor enrichment identified mothers against decapentaplegic homolog 4 (SMAD4) and RE1 silencing transcription factor (REST) as overrepresented in the mPFC of HI rats relative to LI rats, while in silico analysis predicted a conserved SMAD binding site within the voltage-gated calcium channel subunit alpha1 E (CACNA1E) promoter region. qRT-PCR analyses confirmed that mRNA expression of CACNA1E, as well as expression of leucyl and cystinyl aminopeptidase (LNPEP), were higher in the mPFC of HI vs. LI rats. These outcomes establish a transcriptomic landscape in the mPFC that is related to individual differences in motor impulsivity and propose novel gene targets for future impulsivity research.
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Affiliation(s)
- Dennis J Sholler
- Center for Addiction Research, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA; Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Christina R Merritt
- Center for Addiction Research, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA; Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Brionna D Davis-Reyes
- Center for Addiction Research, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - George Golovko
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Noelle C Anastasio
- Center for Addiction Research, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA; Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Kathryn A Cunningham
- Center for Addiction Research, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA; Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.
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Land MA, Ramesh D, Miller AL, Pyles RB, Cunningham KA, Moeller FG, Anastasio NC. Methylation Patterns of the HTR2A Associate With Relapse-Related Behaviors in Cocaine-Dependent Participants. Front Psychiatry 2020; 11:532. [PMID: 32587535 PMCID: PMC7299072 DOI: 10.3389/fpsyt.2020.00532] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 05/22/2020] [Indexed: 11/16/2022] Open
Abstract
Relapse during abstinence in cocaine use disorder (CUD) is often hastened by high impulsivity (predisposition toward rapid unplanned reactions to stimuli without regard to negative consequences) and high cue reactivity (e.g., attentional bias towards drug reward stimuli). A deeper understanding of the degree to which individual biological differences predict or promote problematic behaviors may afford opportunities for clinical refinement and optimization of CUD diagnostics and/or therapies. Preclinical evidence implicates serotonin (5-HT) neurotransmission through the 5-HT2A receptor (5-HT2AR) as a driver of individual differences in these relapse-related behaviors. Regulation of 5-HT2AR function occurs through many mechanisms, including DNA methylation of the HTR2A gene, an epigenetic modification linked with the memory of gene-environment interactions. In the present study, we tested the hypothesis that methylation of the HTR2A may associate with relapse-related behavioral vulnerability in cocaine-dependent participants versus healthy controls. Impulsivity was assessed by self-report (Barratt Impulsiveness Scale; BIS-11) and the delay discounting task, while levels of cue reactivity were determined by performance in the cocaine-word Stroop task. Genomic DNA was extracted from lymphocytes and the bisulfite-treated DNA was subjected to pyrosequencing to determine degree of methylation at four cytosine residues of the HTR2A promoter (-1439, -1420, -1224, -253). We found that the percent methylation at site -1224 after correction for age trended towards a positive correlation with total BIS-11 scores in cocaine users, but not healthy controls. Percent methylation at site -1420 negatively correlated with rates of delay discounting in healthy controls, but not cocaine users. Lastly, the percent methylation at site -253 positively correlated with attentional bias toward cocaine-associated cues. DNA methylation at these cytosine residues of the HTR2A promoter may be differentially associated with impulsivity or cocaine-associated environmental cues. Taken together, these data suggest that methylation of the HTR2A may contribute to individual differences in relapse-related behaviors in CUD.
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Affiliation(s)
- Michelle A Land
- Center for Addiction Research, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States
| | - Divya Ramesh
- Department of Psychiatry and Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, VA, United States
| | - Aaron L Miller
- Department of Pediatrics, University of Texas Medical Branch, Galveston, TX, United States
| | - Richard B Pyles
- Department of Pediatrics, University of Texas Medical Branch, Galveston, TX, United States
| | - Kathryn A Cunningham
- Center for Addiction Research, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States
| | - F Gerard Moeller
- Department of Psychiatry and Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, VA, United States
| | - Noelle C Anastasio
- Center for Addiction Research, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States
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Davis-Reyes BD, Campbell VM, Land MA, Chapman HL, Stafford SJ, Anastasio NC. Profile of cortical N-methyl-D-aspartate receptor subunit expression associates with inherent motor impulsivity in rats. Biochem Pharmacol 2019; 168:204-213. [PMID: 31295463 PMCID: PMC6733662 DOI: 10.1016/j.bcp.2019.07.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/07/2019] [Indexed: 01/01/2023]
Abstract
Impulsivity is a multifaceted behavioral manifestation with implications in several neuropsychiatric disorders. Glutamate neurotransmission through the N-methyl-D-aspartate receptors (NMDARs) in the medial prefrontal cortex (mPFC), an important brain region in decision-making and goal-directed behaviors, plays a key role in motor impulsivity. We discovered that inherent motor impulsivity predicted responsiveness to D-cycloserine (DCS), a partial NMDAR agonist, which prompted the hypothesis that inherent motor impulsivity is associated with the pattern of expression of cortical NMDAR subunits (GluN1, GluN2A, GluN2B), specifically the protein levels and synaptosomal trafficking of the NMDAR subunits. Outbred male Sprague-Dawley rats were identified as high (HI) or low (LI) impulsive using the one-choice serial reaction time task. Following phenotypic identification, mPFC synaptosomal protein was extracted from HI and LI rats to assess the expression pattern of the NMDAR subunits. Synaptosomal trafficking and stabilization for the GluN2 subunits were investigated by co-immunoprecipitation for postsynaptic density 95 (PSD95) and synapse associated protein 102 (SAP102). HI rats had lower mPFC GluN1 and GluN2A, but higher GluN2B and pGluN2B synaptosomal protein expression versus LI rats. Further, higher GluN2B:PSD95 and GluN2B:SAP102 protein:protein interactions were detected in HI versus LI rats. Thus, the mPFC NMDAR subunit expression pattern and/or synaptosomal trafficking associates with high inherent motor impulsivity. Increased understanding of the complex regulation of NMDAR balance within the mPFC as it relates to inherent motor impulsivity may lead to a better understanding of risk factors for impulse-control disorders.
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Affiliation(s)
- Brionna D Davis-Reyes
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Veronica M Campbell
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Michelle A Land
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Holly L Chapman
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Susan J Stafford
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Noelle C Anastasio
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA.
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16
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Anastasio NC, Stutz SJ, Price AE, Davis-Reyes BD, Sholler DJ, Ferguson SM, Neumaier JF, Moeller FG, Hommel JD, Cunningham KA. Convergent neural connectivity in motor impulsivity and high-fat food binge-like eating in male Sprague-Dawley rats. Neuropsychopharmacology 2019; 44:1752-1761. [PMID: 31003231 PMCID: PMC6785029 DOI: 10.1038/s41386-019-0394-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 04/05/2019] [Accepted: 04/13/2019] [Indexed: 12/27/2022]
Abstract
Food intake is essential for survival, but maladaptive patterns of intake, possibly encoded by a preexisting vulnerability coupled with the influence of environmental variables, can modify the reward value of food. Impulsivity, a predisposition toward rapid unplanned reactions to stimuli, is one of the multifaceted determinants underlying the etiology of dysregulated eating and its evolving pathogenesis. The medial prefrontal cortex (mPFC) is a major neural director of reward-driven behavior and impulsivity. Compromised signaling between the mPFC and nucleus accumbens shell (NAcSh) is thought to underlie the cognitive inability to withhold prepotent responses (motor impulsivity) and binge intake of high-fat food (HFF) seen in binge eating disorder. To explore the relationship between motor impulsivity and binge-like eating in rodents, we identified high (HI) and low impulsive (LI) rats in the 1-choice serial reaction time task and employed a rat model of binge-like eating behavior. HFF binge rats consumed significantly greater calories relative to control rats maintained on continual access to standard food or HFF. HI rats repeatedly exhibited significantly higher bingeing on HFF vs. LI rats. Next, we employed dual viral vector chemogenetic technology which allows for the targeted and isolated modulation of ventral mPFC (vmPFC) neurons that project to the NAcSh. Chemogenetic activation of the vmPFC to NAcSh pathway significantly suppressed motor impulsivity and binge-like intake for high-fat food. Thus, inherent motor impulsivity and binge-like eating are linked and the vmPFC to NAcSh pathway serves as a 'brake' over both behaviors.
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Affiliation(s)
- Noelle C. Anastasio
- 0000 0001 1547 9964grid.176731.5Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX USA
| | - Sonja J. Stutz
- 0000 0001 1547 9964grid.176731.5Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX USA
| | - Amanda E. Price
- 0000 0001 1547 9964grid.176731.5Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX USA
| | - Brionna D. Davis-Reyes
- 0000 0001 1547 9964grid.176731.5Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX USA
| | - Dennis J. Sholler
- 0000 0001 1547 9964grid.176731.5Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX USA
| | - Susan M. Ferguson
- 0000 0000 9026 4165grid.240741.4Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA USA ,0000000122986657grid.34477.33Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA USA
| | - John F. Neumaier
- 0000000122986657grid.34477.33Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA USA
| | - F. Gerard Moeller
- 0000 0004 0458 8737grid.224260.0Department of Psychiatry and Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, VA USA
| | - Jonathan D. Hommel
- 0000 0001 1547 9964grid.176731.5Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX USA
| | - Kathryn A. Cunningham
- 0000 0001 1547 9964grid.176731.5Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX USA
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Simmler LD, Blakely RD. The SERT Met172 Mouse: An Engineered Model To Elucidate the Contributions of Serotonin Signaling to Cocaine Action. ACS Chem Neurosci 2019; 10:3053-3060. [PMID: 30817127 DOI: 10.1021/acschemneuro.9b00005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Cocaine abuse and addiction remain highly prevalent and, unfortunately, poorly treated. It is well-known that essential aspects of cocaine's addictive actions involve the drug's ability to block the presynaptic dopamine (DA) transporter (DAT), thereby elevating extracellular levels of DA in brain circuits that subserve reward, reinforcement, and habit. Less well appreciated are the multiple DA-independent actions of cocaine, activities that we and others believe contribute key pieces to the puzzle of cocaine addiction, treatment, and relapse. In particular, a significant body of work points to altered serotonin (5-HT) signaling as one such component, not surprising given that, relative to DAT, cocaine acts as potently to block the 5-HT transporter (SERT) as to block DAT, and thereby elevates extracellular 5-HT levels throughout the brain when reward-eliciting DA elevations occur. To elucidate the contribution of SERT antagonism to the actions of cocaine, we engineered a mouse model that significantly reduces cocaine potency at SERT without disrupting the expression or function of SERT in vivo. In this short Perspective, we review the rationale for development of the SERT Met172 model, the studies that document the pharmacological impact of the Ile172Met substitution in vitro and in vivo, and our findings with the model that demonstrate serotonergic contributions to the genetic, physiological, and behavioral actions of cocaine.
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Affiliation(s)
- Linda D. Simmler
- Department of Basic Neurosciences, University of Geneva, Rue Michel-Servet 1, 1206 Geneva, Switzerland
| | - Randy D. Blakely
- Department of Biomedical Science, Charles E. Schmidt College of Medicine and Brain Institute, Florida Atlantic University, Jupiter, Florida 33458, United States
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Sholler DJ, Stutz SJ, Fox RG, Boone EL, Wang Q, Rice KC, Moeller FG, Anastasio NC, Cunningham KA. The 5-HT 2A Receptor (5-HT 2AR) Regulates Impulsive Action and Cocaine Cue Reactivity in Male Sprague-Dawley Rats. J Pharmacol Exp Ther 2019; 368:41-49. [PMID: 30373886 PMCID: PMC6290084 DOI: 10.1124/jpet.118.251199] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 10/25/2018] [Indexed: 01/25/2023] Open
Abstract
Impulsivity and the attentional orienting response to cocaine-associated cues (cue reactivity) promote relapse in cocaine-use disorder (CUD). A time-dependent escalation of cue reactivity (incubation) occurs during extended, forced abstinence from cocaine self-administration in rats. The investigational serotonin (5-HT) 5-HT2A receptor (5-HT2AR) antagonist/inverse agonist M100907 suppresses impulsive action, or the inability to withhold premature responses, and cocaine-seeking behaviors. The present preclinical study was designed to establish the potential for repurposing the Food and Drug Administration-approved selective 5-HT2AR antagonist/inverse agonist pimavanserin as a therapeutic agent to forestall relapse vulnerability in CUD. In male Sprague-Dawley rats, pimavanserin suppressed impulsive action (premature responses) measured in the 1-choice serial reaction time (1-CSRT) task, similarly to M100907. We also used the 1-CSRT task to establish baseline levels of impulsive action before cocaine self-administration and evaluation of cue reactivity (lever presses reinforced by the discrete cue complex previously paired with cocaine delivery). We observed an incubation of cocaine cue reactivity between day 1 and day 30 of forced abstinence from cocaine self-administration. Baseline levels of impulsive action predicted incubated levels of cocaine cue reactivity in late abstinence. We also found that baseline impulsive action predicted the effectiveness of pimavanserin to suppress incubated cue reactivity in late abstinence from cocaine self-administration at doses that were ineffective in early abstinence. These data suggest that integration of clinical measures of impulsive action may inform refined, personalized pharmacotherapeutic intervention for the treatment of relapse vulnerability in CUD.
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Affiliation(s)
- Dennis J Sholler
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (D.J.S., S.J.S., R.G.F., N.C.A., K.A.C.); Department of Statistical Sciences and Operations Research, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (E.L.B., Q.W.); Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Bethesda, Maryland (K.C.R.); and Department of Psychiatry, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (F.G.M.)
| | - Sonja J Stutz
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (D.J.S., S.J.S., R.G.F., N.C.A., K.A.C.); Department of Statistical Sciences and Operations Research, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (E.L.B., Q.W.); Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Bethesda, Maryland (K.C.R.); and Department of Psychiatry, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (F.G.M.)
| | - Robert G Fox
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (D.J.S., S.J.S., R.G.F., N.C.A., K.A.C.); Department of Statistical Sciences and Operations Research, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (E.L.B., Q.W.); Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Bethesda, Maryland (K.C.R.); and Department of Psychiatry, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (F.G.M.)
| | - Edward L Boone
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (D.J.S., S.J.S., R.G.F., N.C.A., K.A.C.); Department of Statistical Sciences and Operations Research, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (E.L.B., Q.W.); Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Bethesda, Maryland (K.C.R.); and Department of Psychiatry, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (F.G.M.)
| | - Qin Wang
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (D.J.S., S.J.S., R.G.F., N.C.A., K.A.C.); Department of Statistical Sciences and Operations Research, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (E.L.B., Q.W.); Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Bethesda, Maryland (K.C.R.); and Department of Psychiatry, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (F.G.M.)
| | - Kenner C Rice
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (D.J.S., S.J.S., R.G.F., N.C.A., K.A.C.); Department of Statistical Sciences and Operations Research, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (E.L.B., Q.W.); Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Bethesda, Maryland (K.C.R.); and Department of Psychiatry, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (F.G.M.)
| | - F Gerard Moeller
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (D.J.S., S.J.S., R.G.F., N.C.A., K.A.C.); Department of Statistical Sciences and Operations Research, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (E.L.B., Q.W.); Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Bethesda, Maryland (K.C.R.); and Department of Psychiatry, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (F.G.M.)
| | - Noelle C Anastasio
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (D.J.S., S.J.S., R.G.F., N.C.A., K.A.C.); Department of Statistical Sciences and Operations Research, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (E.L.B., Q.W.); Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Bethesda, Maryland (K.C.R.); and Department of Psychiatry, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (F.G.M.)
| | - Kathryn A Cunningham
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (D.J.S., S.J.S., R.G.F., N.C.A., K.A.C.); Department of Statistical Sciences and Operations Research, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (E.L.B., Q.W.); Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Bethesda, Maryland (K.C.R.); and Department of Psychiatry, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia (F.G.M.)
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Price AE, Brehm VD, Hommel JD, Anastasio NC, Cunningham KA. Pimavanserin and Lorcaserin Attenuate Measures of Binge Eating in Male Sprague-Dawley Rats. Front Pharmacol 2018; 9:1424. [PMID: 30581386 PMCID: PMC6293203 DOI: 10.3389/fphar.2018.01424] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 11/19/2018] [Indexed: 01/08/2023] Open
Abstract
Binge eating disorder (BED) is characterized by dysregulated feeding and reward-related processes, and treatment is often challenged by limited therapeutic options. The serotonin (5-HT) 5-HT2A receptor (5-HT2AR) and 5-HT2CR are implicated in both feeding-related and reward-related behaviors and are thus poised to regulate BED-related behaviors. The purpose of this study was to assess the efficacy of the FDA-approved medications pimavanserin, a 5-HT2AR antagonist/inverse agonist, and lorcaserin, a 5-HT2CR agonist, in a rodent model of binge eating. The effects of pimavanserin (0.3–3.0 mg/kg), lorcaserin (0.25–1.0 mg/kg), and the lowest effective dose of pimavanserin (0.3 mg/kg) plus lorcaserin (1.0 mg/kg) were tested in a high-fat food (HFF) intermittent access binge eating model in adult male Sprague-Dawley rats (n = 64). We assessed three measures related to binge eating – binge episode occurrence, binge intake, and weight gain associated with HFF access. Pimavanserin decreased binge intake and weight gain associated with HFF access, but did not prevent binge episode occurrence. Lorcaserin decreased binge intake, but did not prevent binge episode occurrence or weight gain associated with HFF access. Combined pimavanserin plus lorcaserin prevented binge episode occurrence in addition to decreasing binge intake and weight gain associated with HFF access. These preclinical findings in male rats suggest that pimavanserin and lorcaserin may be effective in treating patients with BED. Our studies further indicate that administration of one or both drugs may be more effective in certain sub-populations of patients with BED because of the unique profile each treatment elicits. These data support future assessment in clinical populations with BED.
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Affiliation(s)
- Amanda E Price
- Center for Addiction Research, University of Texas Medical Branch, Galveston, TX, United States
| | - Victoria D Brehm
- Center for Addiction Research, University of Texas Medical Branch, Galveston, TX, United States
| | - Jonathan D Hommel
- Center for Addiction Research, University of Texas Medical Branch, Galveston, TX, United States.,Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States
| | - Noelle C Anastasio
- Center for Addiction Research, University of Texas Medical Branch, Galveston, TX, United States.,Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States
| | - Kathryn A Cunningham
- Center for Addiction Research, University of Texas Medical Branch, Galveston, TX, United States.,Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, United States
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20
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Soto CA, Shashack MJ, Fox RG, Bubar MJ, Rice KC, Watson CS, Cunningham KA, Gilbertson SR, Anastasio NC. Novel Bivalent 5-HT 2A Receptor Antagonists Exhibit High Affinity and Potency in Vitro and Efficacy in Vivo. ACS Chem Neurosci 2018; 9:514-521. [PMID: 29111677 DOI: 10.1021/acschemneuro.7b00309] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The 5-HT2A receptor (5-HT2AR) plays an important role in various neuropsychiatric disorders, including substance use disorder and schizophrenia. Homodimerization of this receptor has been suggested, but tools that allow direct assessment of the relevance of the 5-HT2AR:5-HT2AR homodimer in these disorders are necessary. We chemically modified the selective 5-HT2AR antagonist M100907 to synthesize a series of homobivalent ligands connected by ethylene glycol linkers of varying lengths that may be useful tools for probing 5-HT2AR:5-HT2AR homodimer function. We tested these molecules for 5-HT2AR antagonist activity in a cell line stably expressing the functional 5-HT2AR and quantified a downstream signaling target, activation (phosphorylation) of extracellular regulated kinases 1/2 (ERK1/2), in comparison to in vivo efficacy of altering spontaneous or cocaine-evoked locomotor activity in rats. All of the synthetic compounds inhibited 5-HT-mediated phosphorylation of ERK1/2 in the cellular signaling assay; the potency of the bivalent ligands varied as a function of linker length, with the intermediate linker lengths being the most potent. The Ki values for the binding of bivalent ligands to 5-HT2AR were only slightly lower than the values for the parent (+)-M100907 compound, but significant selectivity for 5-HT2AR over 5-HT2BR or 5-HT2CR binding was retained. In addition, the 11-atom-linked bivalent 5-HT2AR antagonist (2 mg/kg, intraperitoneally) demonstrated efficacy on par with that of (+)-M100907 in inhibiting cocaine-evoked hyperactivity. As we develop further strategies for ligand-evoked receptor assembly and analyses of diverse signaling and functional roles, these novel homobivalent 5-HT2AR antagonist ligands will serve as useful in vitro and in vivo probes of 5-HT2AR structure and function.
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Affiliation(s)
| | | | | | | | - Kenner C. Rice
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Bethesda, Maryland 20892, United States
| | | | | | - Scott R. Gilbertson
- Department of Chemistry, University of Houston, Houston, Texas 77004, United States
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21
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Barlow RL, Dalley JW, Pekcec A. Differences in trait impulsivity do not bias the response to pharmacological drug challenge in the rat five-choice serial reaction time task. Psychopharmacology (Berl) 2018; 235:1199-1209. [PMID: 29374304 PMCID: PMC5869891 DOI: 10.1007/s00213-018-4836-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 01/15/2018] [Indexed: 11/27/2022]
Abstract
RATIONALE Maladaptive impulsivity is symptomatic of several neuropsychiatric disorders including schizophrenia, attention-deficit hyperactivity disorder (ADHD), and substance abuse disorders; paradigms designed to assess the underlying neurobiology of this behavior are essential for the discovery of novel therapeutic agents. Various models may be used to assess impulsivity as measured by the five-choice serial reaction time task (5-CSRTT), including variable inter-trial interval (ITI) sessions, the selection of extreme high and low impulsivity phenotypes from a large outbred population of rats, as well as pharmacological challenges. OBJECTIVES The aim of this study is to evaluate if pharmacological challenge models for impulsivity are biased by underlying differences in impulsivity phenotype. METHODS Extreme high and low impulsivity phenotypes were selected in the 5-CSRTT, and dose-dependent effects of various pharmacological challenges, namely MK-801, yohimbine, and cocaine, were evaluated on task performance, specifically accuracy and premature responses. RESULTS All three compounds increased premature responding, while a decrease in attentional performance occurred following MK-801 and yohimbine administration. No differences in drug-induced impulsivity between rats selected for high or low impulsivity or in parameters indicative of attentional performance could be determined. CONCLUSIONS Our findings indicate that different pharmacological challenges increase impulsivity on the 5-CSRTT, with modest effects on attention. These effects were not influenced by underlying differences in impulsivity phenotype, which is an important prerequisite to reliably use these challenge models to screen and profile compounds with putative anti-impulsive characteristics.
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Affiliation(s)
- Rebecca L Barlow
- Boehringer Ingelheim Pharma GmbH & Co. KG, Division Research Germany, Birkendorfer Strasse 65, 88397, Biberach an der Riss, Germany
| | - Jeffrey W Dalley
- Department of Psychology, University of Cambridge, Downing St, Cambridge, CB2 3EB, UK
- Department of Psychiatry, University of Cambridge, Downing Street, Cambridge, CB2 2QQ, UK
| | - Anton Pekcec
- Boehringer Ingelheim Pharma GmbH & Co. KG, Division Research Germany, Birkendorfer Strasse 65, 88397, Biberach an der Riss, Germany.
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22
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Weafer J, Gray JC, Hernandez K, Palmer AA, MacKillop J, de Wit H. Hierarchical investigation of genetic influences on response inhibition in healthy young adults. Exp Clin Psychopharmacol 2017; 25:512-520. [PMID: 29251981 PMCID: PMC5737791 DOI: 10.1037/pha0000156] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Poor inhibitory control is a known risk factor for substance use disorders, making it a priority to identify the determinants of these deficits. The aim of the current study was to identify genetic associations with inhibitory control using the stop signal task in a large sample (n = 934) of healthy young adults of European ancestry. We genotyped the subjects genome-wide and then used a hierarchical approach in which we tested seven a priori single nucleotide polymorphisms (SNPs) previously associated with stop signal task performance, approximately 9,000 SNPs designated as high-value addiction (HVA) markers by the SmokeScreen array, and approximately five million genotyped and imputed SNPs, followed by a gene-based association analysis using the resultant p values. A priori SNP analyses revealed nominally significant associations between response inhibition and one locus in HTR2A (rs6313; p = .04, dominance model, uncorrected) in the same direction as prior findings. A nominally significant association was also found in one locus in ANKK1 (rs1800497; p = .03, uncorrected), although in the opposite direction of previous reports. After accounting for multiple comparisons, the HVA, genome-wide, and gene-based analyses yielded no significant findings. This study implicates variation in serotonergic and dopaminergic genes while underscoring the difficulty of detecting the influence of individual SNPs, even when biological information is used to prioritize testing. Although such small effect sizes suggest limited utility of individual SNPs in predicting risk for addiction or other impulse control disorders, they may nonetheless shed light on complex biological processes underlying poor inhibitory control. (PsycINFO Database Record
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Affiliation(s)
- Jessica Weafer
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago
| | - Joshua C. Gray
- Department of Psychology, University of Georgia,Department of Psychiatry and Human Behavior, Brown University
| | | | - Abraham A. Palmer
- Department of Psychiatry, University of California, San Diego,Institute for Genomic Medicine, University of California, San Diego
| | - James MacKillop
- Peter Boris Centre for Addictions Research, McMaster University,Homewood Research Institute, Homewood Health Centre
| | - Harriet de Wit
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago,Corresponding author: Harriet de Wit, Department of Psychiatry and Behavioral Neuroscience, MC 3077, University of Chicago, 5841 S. Maryland Ave., Chicago, IL 60637, Phone: 773-702-1537, Fax: 773-834-7698,
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23
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Schenk S, Aronsen D. Contribution of Impulsivity and Serotonin Receptor Neuroadaptations to the Development of an MDMA ('Ecstasy') Substance Use Disorder. Curr Top Behav Neurosci 2017; 34:17-32. [PMID: 26718587 DOI: 10.1007/7854_2015_421] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
As is the case with other drugs of abuse, a proportion of ecstasy users develop symptoms consistent with a substance use disorder (SUD). In this paper, we propose that the pharmacology of MDMA, the primary psychoactive component of ecstasy tablets, changes markedly with repeated exposure and that neuroadaptations in dopamine and serotonin brain systems underlie the shift from MDMA use to MDMA misuse in susceptible subjects. Data from both the human and laboratory animal literature are synthesized to support the idea that (1) MDMA becomes a less efficacious serotonin releaser and a more efficacious dopamine releaser with the development of behaviour consistent with an SUD and (2) that upregulated serotonin receptor mechanisms contribute to the development of the MDMA SUD via dysregulated inhibitory control associated with the trait of impulsivity.
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Affiliation(s)
- Susan Schenk
- School of Psychology, Victoria University of Wellington, Wellington, New Zealand.
| | - Dane Aronsen
- School of Psychology, Victoria University of Wellington, Wellington, New Zealand
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24
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Serafine KM, Rice KC, France CP. Characterization of the discriminative stimulus effects of lorcaserin in rats. J Exp Anal Behav 2016; 106:107-16. [PMID: 27640338 DOI: 10.1002/jeab.222] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 08/24/2016] [Accepted: 08/24/2016] [Indexed: 11/10/2022]
Abstract
Lorcaserin is approved by the Food and Drug Administration for treating obesity and is under consideration for treating substance use disorders; it has agonist properties at serotonin (5-HT)2C receptors and might also have agonist properties at other 5-HT receptor subtypes. This study used drug discrimination to investigate the mechanism(s) of action of lorcaserin. Male Sprague-Dawley rats discriminated 0.56 mg/kg i.p. lorcaserin from saline while responding under a fixed-ratio 5 schedule for food. Lorcaserin (0.178-1.0 mg/kg) dose-dependently increased lorcaserin-lever responding. The 5-HT2C receptor agonist mCPP and the 5-HT2A receptor agonist DOM each occasioned greater than 90% lorcaserin-lever responding in seven of eight rats. The 5-HT1A receptor agonist 8-OH-DPAT occasioned greater than 90% lorcaserin-lever responding in four of seven rats. The 5-HT2C receptor selective antagonist SB 242084 attenuated lorcaserin-lever responding in all eight rats and the 5-HT2A receptor selective antagonist MDL 100907 attenuated lorcaserin-lever responding in six of seven rats. These results suggest that, in addition to agonist properties at 5-HT2C receptors, lorcaserin also has agonist properties at 5-HT2A and 5-HT1A receptors. Because some drugs with 5-HT2A receptor agonist properties are abused, it is important to fully characterize the behavioral effects of lorcaserin while considering its potential for treating substance use disorders.
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Affiliation(s)
- Katherine M Serafine
- Departments of Pharmacology, University of Texas Health Science Center at San Antonio, TEXAS
| | - Kenner C Rice
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland
| | - Charles P France
- Departments of Pharmacology, University of Texas Health Science Center at San Antonio, TEXAS. .,Departments of Psychiatry, University of Texas Health Science Center at San Antonio, TEXAS.
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25
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Aznar S, Hervig MES. The 5-HT2A serotonin receptor in executive function: Implications for neuropsychiatric and neurodegenerative diseases. Neurosci Biobehav Rev 2016; 64:63-82. [DOI: 10.1016/j.neubiorev.2016.02.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 11/05/2015] [Accepted: 02/08/2016] [Indexed: 02/07/2023]
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26
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Halberstadt AL, Sindhunata IS, Scheffers K, Flynn AD, Sharp RF, Geyer MA, Young JW. Effect of 5-HT2A and 5-HT2C receptors on temporal discrimination by mice. Neuropharmacology 2016; 107:364-375. [PMID: 27020041 DOI: 10.1016/j.neuropharm.2016.03.038] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 03/10/2016] [Accepted: 03/23/2016] [Indexed: 11/25/2022]
Abstract
Timing deficits are observed in patients with schizophrenia. Serotonergic hallucinogens can also alter the subjective experience of time. Characterizing the mechanism through which the serotonergic system regulates timing will increase our understanding of the linkage between serotonin (5-HT) and schizophrenia, and will provide insight into the mechanism of action of hallucinogens. We investigated whether interval timing in mice is altered by hallucinogens and other 5-HT2 receptor ligands. C57BL/6J mice were trained to perform a discrete-trials temporal discrimination task. In the discrete-trials task, mice were presented with two levers after a variable interval. Responding on lever A was reinforced if the interval was <6.5 s, and responding on lever B was reinforced if the interval was >6.5 s. A 2-parameter logistic function was fitted to the proportional choice for lever B (%B responding), yielding estimates of the indifference point (T50) and the Weber fraction (a measure of timing precision). The 5-HT2A antagonist M100907 increased T50, whereas the 5-HT2C antagonist SB-242,084 reduced T50. The results indicate that 5-HT2A and 5-HT2C receptors have countervailing effects on the speed of the internal pacemaker. The hallucinogen 2,5-dimethoxy-4-iodoamphetamine (DOI; 3 mg/kg IP), a 5-HT2 agonist, flattened the response curve at long stimulus intervals and shifted it to the right, causing both T50 and the Weber fraction to increase. The effect of DOI was antagonized by M100907 (0.03 mg/kg SC) but was unaffected by SB-242,084 (0.1 mg/kg SC). Similar to DOI, the selective 5-HT2A agonist 25CN-NBOH (6 mg/kg SC) reduced %B responding at long stimulus intervals, and increased T50 and the Weber fraction. These results demonstrate that hallucinogens alter temporal perception in mice, effects that are mediated by the 5-HT2A receptor. It appears that 5-HT regulates temporal perception, suggesting that altered serotonergic signaling may contribute to the timing deficits observed in schizophrenia and other psychiatric disorders.
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Affiliation(s)
- Adam L Halberstadt
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States; Research Service, VA San Diego Healthcare System, San Diego, CA, United States.
| | - Ivan S Sindhunata
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Kees Scheffers
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Aaron D Flynn
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Richard F Sharp
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Mark A Geyer
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States; Research Service, VA San Diego Healthcare System, San Diego, CA, United States
| | - Jared W Young
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States; Research Service, VA San Diego Healthcare System, San Diego, CA, United States
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27
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Hamilton KR, Littlefield AK, Anastasio NC, Cunningham KA, Fink LHL, Wing VC, Mathias CW, Lane SD, Schütz CG, Swann AC, Lejuez CW, Clark L, Moeller FG, Potenza MN. Rapid-response impulsivity: definitions, measurement issues, and clinical implications. Personal Disord 2016; 6:168-181. [PMID: 25867840 DOI: 10.1037/per0000100] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Impulsivity is a multifaceted construct that is a core feature of multiple psychiatric conditions and personality disorders. However, progress in understanding and treating impulsivity is limited by a lack of precision and consistency in its definition and assessment. Rapid-response impulsivity (RRI) represents a tendency toward immediate action that occurs with diminished forethought and is out of context with the present demands of the environment. Experts from the International Society for Research on Impulsivity (InSRI) met to discuss and evaluate RRI measures in terms of reliability, sensitivity, and validity, with the goal of helping researchers and clinicians make informed decisions about the use and interpretation of findings from RRI measures. Their recommendations are described in this article. Commonly used clinical and preclinical RRI tasks are described, and considerations are provided to guide task selection. Tasks measuring two conceptually and neurobiologically distinct types of RRI, "refraining from action initiation" (RAI) and "stopping an ongoing action" (SOA) are described. RAI and SOA tasks capture distinct aspects of RRI that may relate to distinct clinical outcomes. The InSRI group recommends that (a) selection of RRI measures should be informed by careful consideration of the strengths, limitations, and practical considerations of the available measures; (b) researchers use both RAI and SOA tasks in RRI studies to allow for direct comparison of RRI types and examination of their associations with clinically relevant measures; and (c) similar considerations be made for human and nonhuman studies in an effort to harmonize and integrate preclinical and clinical research.
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Affiliation(s)
- Kristen R Hamilton
- Department of Psychology, Maryland Neuroimaging Center, Center for Addictions, Personality, and Emotion Research, University of Maryland
| | | | - Noelle C Anastasio
- Center for Addiction Research, Department of Pharmacology and Toxicology, University of Texas Medical Branch
| | - Kathryn A Cunningham
- Center for Addiction Research, Department of Pharmacology and Toxicology, University of Texas Medical Branch
| | - Latham H L Fink
- Center for Addiction Research, University of Texas Medical Branch
| | - Victoria C Wing
- Schizophrenia Division, Complex Mental Illness, Centre for Addiction and Mental Health
| | - Charles W Mathias
- Department of Psychiatry, Division of Neurobehavioral Research, University of Texas Health Science Center at San Antonio
| | - Scott D Lane
- Department of Psychiatry and Behavioral Sciences, University of Texas at Houston Medical School
| | | | - Alan C Swann
- Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine
| | - C W Lejuez
- Department of Psychology, Maryland Neuroimaging Center, Center for Addictions, Personality, and Emotion Research, University of Maryland
| | - Luke Clark
- Centre for Gambling Research at UBC, Department of Psychology, University of British Columbia
| | - F Gerard Moeller
- Department of Psychiatry, Virginia Commonwealth University School of Medicine
| | - Marc N Potenza
- Department of Psychiatry, Yale University School of Medicine
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28
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Adolescent methylphenidate treatment differentially alters adult impulsivity and hyperactivity in the Spontaneously Hypertensive Rat model of ADHD. Pharmacol Biochem Behav 2015; 141:66-77. [PMID: 26657171 DOI: 10.1016/j.pbb.2015.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 09/30/2015] [Accepted: 12/01/2015] [Indexed: 12/30/2022]
Abstract
Impulsivity and hyperactivity are two facets of attention deficit/hyperactivity disorder (ADHD). Impulsivity is expressed as reduced response inhibition capacity, an executive control mechanism that prevents premature execution of an intermittently reinforced behavior. During methylphenidate treatment, impulsivity and hyperactivity are decreased in adolescents with ADHD, but there is little information concerning levels of impulsivity and hyperactivity in adulthood after adolescent methylphenidate treatment is discontinued. The current study evaluated impulsivity, hyperactivity as well as cocaine sensitization during adulthood after adolescent methylphenidate treatment was discontinued in the Spontaneously Hypertensive Rat (SHR) model of ADHD. Treatments consisted of oral methylphenidate (1.5mg/kg) or water vehicle provided Monday-Friday from postnatal days 28-55. During adulthood, impulsivity was measured in SHR and control strains (Wistar Kyoto and Wistar rats) using differential reinforcement of low rate (DRL) schedules. Locomotor activity and cocaine sensitization were measured using the open-field assay. Adult SHR exhibited decreased efficiency of reinforcement under the DRL30 schedule and greater levels of locomotor activity and cocaine sensitization compared to control strains. Compared to vehicle, methylphenidate treatment during adolescence reduced hyperactivity in adult SHR, maintained the lower efficiency of reinforcement, and increased burst responding under DRL30. Cocaine sensitization was not altered following adolescent methylphenidate in adult SHR. In conclusion, adolescent treatment with methylphenidate followed by discontinuation in adulthood had a positive benefit by reducing hyperactivity in adult SHR rats; however, increased burst responding under DRL compared to SHR given vehicle, i.e., elevated impulsivity, constituted an adverse consequence associated with increased risk for cocaine abuse liability.
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29
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Serafine KM, Rice KC, France CP. Directly Observable Behavioral Effects of Lorcaserin in Rats. J Pharmacol Exp Ther 2015; 355:381-5. [PMID: 26384326 PMCID: PMC4658489 DOI: 10.1124/jpet.115.228148] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 09/10/2015] [Indexed: 11/22/2022] Open
Abstract
(1R)-8-chloro-1-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine (lorcaserin) is approved by the United States Food and Drug Administration for treating obesity, and its therapeutic effects are thought to result from agonist activity at serotonin (5-HT)2C receptors. Lorcaserin has affinity for other 5-HT receptor subtypes, although its activity at those subtypes is not fully described. The current study compared the behavioral effects of lorcaserin (0.0032-32.0 mg/kg) to the effects of other 5-HT receptor selective agonists in rats (n = 8). The 5-HT2C receptor selective agonist 1-(3-chlorophenyl)piperazine (mCPP, 0.032-1.0 mg/kg) and lorcaserin induced yawning which was attenuated by the 5-HT2C receptor selective antagonist 6-chloro-5-methyl-N-(6-[(2-methylpyridin-3-yl)oxy]pydidin-3-yl)indoline-1-carboxamide (1.0 mg/kg). The 5-HT2A receptor selective agonist 2,5-dimethoxy-4-methylamphetamine (0.1-3.2 mg/kg) induced head twitching, which was attenuated by the 5-HT2A receptor selective antagonist R-(+)-2,3-dimethoxyphenyl-1-[2-(4-piperidine)-methanol] (MDL 100907, 0.01 mg/kg), lorcaserin (3.2 mg/kg), and mCPP (3.2 mg/kg). In rats pretreated with MDL 100907 (1.0 mg/kg), lorcaserin also induced head twitching. At larger doses, lorcaserin produced forepaw treading, which was attenuated by the 5-HT1A receptor selective antagonist N-(2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl)-N-(2-pyridyl)cyclohexanecarboxamide (0.178 mg/kg). While the behavioral effects of lorcaserin in rats are consistent with it having agonist activity at 5-HT2C receptors, these data suggest that at larger doses it also has agonist activity at 5-HT2A and possibly 5-HT1A receptors. Mounting evidence suggests that 5-HT2C receptor agonists might be effective for treating drug abuse. A more complete description of the activity of lorcaserin at 5-HT receptor subtypes will facilitate a better understanding of the mechanisms that mediate its therapeutic effects.
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MESH Headings
- DOM 2,5-Dimethoxy-4-Methylamphetamine/pharmacology
- 8-Hydroxy-2-(di-n-propylamino)tetralin/pharmacology
- Amphetamines/pharmacology
- Animals
- Anti-Obesity Agents/pharmacology
- Behavior, Animal/drug effects
- Benzazepines/pharmacology
- Dose-Response Relationship, Drug
- Head Movements/drug effects
- Male
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT1A/drug effects
- Receptor, Serotonin, 5-HT2A/drug effects
- Receptor, Serotonin, 5-HT2C/drug effects
- Serotonin 5-HT2 Receptor Agonists/pharmacology
- Serotonin 5-HT2 Receptor Antagonists/pharmacology
- Serotonin Antagonists/pharmacology
- Serotonin Receptor Agonists/pharmacology
- Yawning/drug effects
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Affiliation(s)
- Katherine M Serafine
- Departments of Pharmacology (K.M.S., C.P.F.) and Psychiatry (C.P.F.), University of Texas Health Science Center at San Antonio, San Antonio, Texas and Chemical Biology Research Laboratory, Department of Health and Human Services, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland (K.C.R.)
| | - Kenner C Rice
- Departments of Pharmacology (K.M.S., C.P.F.) and Psychiatry (C.P.F.), University of Texas Health Science Center at San Antonio, San Antonio, Texas and Chemical Biology Research Laboratory, Department of Health and Human Services, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland (K.C.R.)
| | - Charles P France
- Departments of Pharmacology (K.M.S., C.P.F.) and Psychiatry (C.P.F.), University of Texas Health Science Center at San Antonio, San Antonio, Texas and Chemical Biology Research Laboratory, Department of Health and Human Services, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland (K.C.R.)
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30
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Anastasio NC, Stutz SJ, Fink LHL, Swinford-Jackson SE, Sears RM, DiLeone RJ, Rice KC, Moeller FG, Cunningham KA. Serotonin (5-HT) 5-HT2A Receptor (5-HT2AR):5-HT2CR Imbalance in Medial Prefrontal Cortex Associates with Motor Impulsivity. ACS Chem Neurosci 2015; 6:1248-58. [PMID: 26120876 DOI: 10.1021/acschemneuro.5b00094] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A feature of multiple neuropsychiatric disorders is motor impulsivity. Recent studies have implicated serotonin (5-HT) systems in medial prefrontal cortex (mPFC) in mediating individual differences in motor impulsivity, notably the 5-HT2AR receptor (5-HT2AR) and 5-HT2CR. We investigated the hypothesis that differences in the ratio of 5-HT2AR:5-HT2CR protein expression in mPFC would predict the individual level of motor impulsivity and that the engineered loss of the 5-HT2CR would result in high motor impulsivity concomitant with elevated 5-HT2AR expression and pharmacological sensitivity to the selective 5-HT2AR antagonist M100907. High and low impulsive rats were identified in a 1-choice serial reaction time task. Native protein levels of the 5-HT2AR and the 5-HT2CR predicted the intensity of motor impulsivity and the 5-HT2AR:5-HT2CR ratio in mPFC positively correlated with levels of premature responses in individual outbred rats. The possibility that the 5-HT2AR and 5-HT2CR act in concert to control motor impulsivity is supported by the observation that high phenotypic motor impulsivity associated with a diminished mPFC synaptosomal 5-HT2AR:5-HT2CR protein:protein interaction. Knockdown of mPFC 5-HT2CR resulted in increased motor impulsivity and triggered a functional disruption of the local 5-HT2AR:5-HT2CR balance as evidenced by a compensatory upregulation of 5-HT2AR protein expression and a leftward shift in the potency of M100907 to suppress impulsive behavior. We infer that there is an interactive relationship between the mPFC 5-HT2AR and 5-HT2CR, and that a 5-HT2AR:5-HT2CR imbalance may be a functionally relevant mechanism underlying motor impulsivity.
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Affiliation(s)
| | | | | | | | - Robert M. Sears
- Department
of Psychiatry, Yale University, New Haven, Connecticut 06520, United States
| | - Ralph J. DiLeone
- Department
of Psychiatry, Yale University, New Haven, Connecticut 06520, United States
| | - Kenner C. Rice
- Chemical
Biology Research Branch, National Institute on Drug Abuse, DHHS/NIH/NIDA, Bethesda, Maryland 20892, United States
| | - F. Gerard Moeller
- Department
of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298, United States
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31
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Individual Differences in Impulsive Action Reflect Variation in the Cortical Serotonin 5-HT2A Receptor System. Neuropsychopharmacology 2015; 40:1957-68. [PMID: 25666313 PMCID: PMC4839520 DOI: 10.1038/npp.2015.46] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 01/05/2015] [Accepted: 01/26/2015] [Indexed: 11/08/2022]
Abstract
Impulsivity is an important feature of multiple neuropsychiatric disorders, and individual variation in the degree of inherent impulsivity could play a role in the generation or exacerbation of problematic behaviors. Serotonin (5-HT) actions at the 5-HT2AR receptor (5-HT2AR) promote and 5-HT2AR antagonists suppress impulsive action (the inability to withhold premature responses; motor impulsivity) upon systemic administration or microinfusion directly into the medial prefrontal cortex (mPFC), a node in the corticostriatal circuit that is thought to play a role in the regulation of impulsive action. We hypothesized that the functional capacity of the 5-HT2AR, which is governed by its expression, localization, and protein/protein interactions (eg, postsynaptic density 95 (PSD95)), may drive the predisposition to inherent impulsive action. Stable high-impulsive (HI) and low-impulsive (LI) phenotypes were identified from an outbred rodent population with the 1-choice serial reaction time (1-CSRT) task. HI rats exhibited a greater head-twitch response following administration of the preferential 5-HT2AR agonist 2,5-dimethoxy-4-iodoamphetamine (DOI) and were more sensitive to the effects of the selective 5-HT2AR antagonist M100907 to suppress impulsive action relative to LI rats. A positive correlation was observed between levels of premature responses and 5-HT2AR binding density in frontal cortex ([(3)H]-ketanserin radioligand binding). Elevated mPFC 5-HT2AR protein expression concomitant with augmented association of the 5-HT2AR with PSD95 differentiated HI from LI rats. The observed differential sensitivity of HI and LI rats to 5-HT2AR ligands and associated distinct 5-HT2AR protein profiles provide evidence that spontaneously occurring individual differences in impulsive action reflect variation in the cortical 5-HT2AR system.
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Howell LL, Cunningham KA. Serotonin 5-HT2 receptor interactions with dopamine function: implications for therapeutics in cocaine use disorder. Pharmacol Rev 2015; 67:176-97. [PMID: 25505168 DOI: 10.1124/pr.114.009514] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cocaine exhibits prominent abuse liability, and chronic abuse can result in cocaine use disorder with significant morbidity. Major advances have been made in delineating neurobiological mechanisms of cocaine abuse; however, effective medications to treat cocaine use disorder remain to be discovered. The present review will focus on the role of serotonin (5-HT; 5-hydroxytryptamine) neurotransmission in the neuropharmacology of cocaine and related abused stimulants. Extensive research suggests that the primary contribution of 5-HT to cocaine addiction is a consequence of interactions with dopamine (DA) neurotransmission. The literature on the neurobiological and behavioral effects of cocaine is well developed, so the focus of the review will be on cocaine with inferences made about other monoamine uptake inhibitors and releasers based on mechanistic considerations. 5-HT receptors are widely expressed throughout the brain, and several different 5-HT receptor subtypes have been implicated in mediating the effects of endogenous 5-HT on DA. However, the 5-HT2A and 5-HT2C receptors in particular have been implicated as likely candidates for mediating the influence of 5-HT in cocaine abuse as well as to traits (e.g., impulsivity) that contribute to the development of cocaine use disorder and relapse in humans. Lastly, new approaches are proposed to guide targeted development of serotonergic ligands for the treatment of cocaine use disorder.
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Affiliation(s)
- Leonard L Howell
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia (L.L.H.); and Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (K.A.C.)
| | - Kathryn A Cunningham
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia (L.L.H.); and Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas (K.A.C.)
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Ma L, Steinberg JL, Cunningham KA, Lane SD, Bjork JM, Neelakantan H, Price AE, Narayana PA, Kosten TR, Bechara A, Moeller FG. Inhibitory behavioral control: A stochastic dynamic causal modeling study comparing cocaine dependent subjects and controls. NEUROIMAGE-CLINICAL 2015; 7:837-47. [PMID: 26082893 PMCID: PMC4459041 DOI: 10.1016/j.nicl.2015.03.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 03/02/2015] [Accepted: 03/19/2015] [Indexed: 01/08/2023]
Abstract
Cocaine dependence is associated with increased impulsivity in humans. Both cocaine dependence and impulsive behavior are under the regulatory control of cortico-striatal networks. One behavioral laboratory measure of impulsivity is response inhibition (ability to withhold a prepotent response) in which altered patterns of regional brain activation during executive tasks in service of normal performance are frequently found in cocaine dependent (CD) subjects studied with functional magnetic resonance imaging (fMRI). However, little is known about aberrations in specific directional neuronal connectivity in CD subjects. The present study employed fMRI-based dynamic causal modeling (DCM) to study the effective (directional) neuronal connectivity associated with response inhibition in CD subjects, elicited under performance of a Go/NoGo task with two levels of NoGo difficulty (Easy and Hard). The performance on the Go/NoGo task was not significantly different between CD subjects and controls. The DCM analysis revealed that prefrontal–striatal connectivity was modulated (influenced) during the NoGo conditions for both groups. The effective connectivity from left (L) anterior cingulate cortex (ACC) to L caudate was similarly modulated during the Easy NoGo condition for both groups. During the Hard NoGo condition in controls, the effective connectivity from right (R) dorsolateral prefrontal cortex (DLPFC) to L caudate became more positive, and the effective connectivity from R ventrolateral prefrontal cortex (VLPFC) to L caudate became more negative. In CD subjects, the effective connectivity from L ACC to L caudate became more negative during the Hard NoGo conditions. These results indicate that during Hard NoGo trials in CD subjects, the ACC rather than DLPFC or VLPFC influenced caudate during response inhibition. Dynamic causal modeling was used to study response inhibition in cocaine dependence. A Go/NoGo task with two levels of NoGo difficulty (Easy and Hard) was used. Patients and controls used anterior cingulate cortex to control caudate during Easy NoGo. Controls used dorsolateral/ventrolateral prefrontal cortex to control caudate during Hard NoGo. Patients continued using anterior cingulate cortex to control caudate during Hard NoGo.
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Affiliation(s)
- Liangsuo Ma
- Institute for Drug and Alcohol Studies, Virginia Commonwealth University (VCU), Richmond, VA, USA ; Department of Radiology, VCU, Richmond, VA, USA
| | - Joel L Steinberg
- Institute for Drug and Alcohol Studies, Virginia Commonwealth University (VCU), Richmond, VA, USA ; Department of Psychiatry, VCU, Richmond, VA, USA
| | - Kathryn A Cunningham
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Scott D Lane
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center, Houston (UTHSC-H), USA
| | - James M Bjork
- Institute for Drug and Alcohol Studies, Virginia Commonwealth University (VCU), Richmond, VA, USA ; Department of Psychiatry, VCU, Richmond, VA, USA
| | - Harshini Neelakantan
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Amanda E Price
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Ponnada A Narayana
- Department of Diagnostic and Interventional Imaging, UTHSC-H, Houston, TX, USA
| | - Thomas R Kosten
- Department of Psychiatry and Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Antoine Bechara
- Brain and Creativity Institute and Department of Psychology, University of Southern California, Los Angeles, CA, USA
| | - F Gerard Moeller
- Institute for Drug and Alcohol Studies, Virginia Commonwealth University (VCU), Richmond, VA, USA ; Department of Psychiatry, VCU, Richmond, VA, USA ; Department of Pharmacology and Toxicology, Richmond, VCU, VA 23219, USA
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Voon V, Dalley JW. Translatable and Back-Translatable Measurement of Impulsivity and Compulsivity: Convergent and Divergent Processes. Curr Top Behav Neurosci 2015; 28:53-91. [PMID: 27418067 DOI: 10.1007/7854_2015_5013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Impulsivity and compulsivity have emerged as important dimensional constructs that challenge traditional psychiatric classification systems. Both are present in normal healthy populations where the need to act quickly and repeatedly without hesitation can be highly advantageous. However, when excessively expressed, impulsive and compulsive behavior can lead to adverse consequences and spectrum disorders exemplified by attention-deficit/hyperactivity disorder (ADHD), obsessive compulsive disorder (OCD), autism, and drug addiction. Impulsive individuals have difficulty in deferring gratification and are inclined to 'jump the gun' and respond prematurely before sufficient information is gathered. Compulsivity involves repetitive behavior often motivated by the need to reduce or prevent anxiety, thus leading to the maladaptive perseveration of behavior. Defined in this way, impulsivity and compulsivity could be viewed as separate entities or 'traits' but overwhelming evidence indicates that both may be present in the same disorder, either concurrently or even separately at different time points. Herein we discuss the neural and cognitive heterogeneity of impulsive and compulsive endophenotypes. These constructs map onto distinct fronto-striatal neural and neurochemical structures interacting both at nodal convergent points and as opponent processes highlighting both the heterogeneity and the commonalities of function. We focus on discoveries made using both translational research methodologies and studies exclusively in humans, and implications for treatment intervention in disorders in which impulsive and compulsive symptoms prevail. We emphasize the relevance of these constructs for understanding dimensional psychiatry.
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Affiliation(s)
- Valerie Voon
- Behavioral and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK.
- Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, CB2 2QQ, UK.
- Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, UK.
| | - Jeffrey W Dalley
- Behavioral and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK
- Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, CB2 2QQ, UK
- Department of Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB, UK
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Voon V. Models of Impulsivity with a Focus on Waiting Impulsivity: Translational Potential for Neuropsychiatric Disorders. CURRENT ADDICTION REPORTS 2014; 1:281-288. [PMID: 25346881 PMCID: PMC4201744 DOI: 10.1007/s40429-014-0036-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Waiting impulsivity, also known as premature or anticipatory responding, is well established in preclinical studies through the 5-Choice Serial Reaction Time (5-CSRT) task. Waiting impulsivity is important in disorders of addiction. Preclinical studies suggest a role both as a predictor, and as a consequence, in disorders of addiction. Here we discuss the relationship between the preclinical 5-CSRT and translational fidelity in newly developed translational tasks. Preclinical and clinical literature relevant to premature responding and disorders of addiction are reviewed. Understanding which processes are critical to premature responding is important in understanding the nature of premature responding. Premature responding may also have overlaps with motivational processes, proactive response inhibition, tonic inhibitory processes, and delay discounting.
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Affiliation(s)
- Valerie Voon
- Department of Psychiatry, University of Cambridge, Cambridge, CB2 0QQ UK ; Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK ; Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, UK
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Jentsch JD, Ashenhurst JR, Cervantes MC, Groman SM, James AS, Pennington ZT. Dissecting impulsivity and its relationships to drug addictions. Ann N Y Acad Sci 2014; 1327:1-26. [PMID: 24654857 DOI: 10.1111/nyas.12388] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Addictions are often characterized as forms of impulsive behavior. That said, it is often noted that impulsivity is a multidimensional construct, spanning several psychological domains. This review describes the relationship between varieties of impulsivity and addiction-related behaviors, the nature of the causal relationship between the two, and the underlying neurobiological mechanisms that promote impulsive behaviors. We conclude that the available data strongly support the notion that impulsivity is both a risk factor for, and a consequence of, drug and alcohol consumption. While the evidence indicating that subtypes of impulsive behavior are uniquely informative--either biologically or with respect to their relationships to addictions--is convincing, multiple lines of study link distinct subtypes of impulsivity to low dopamine D2 receptor function and perturbed serotonergic transmission, revealing shared mechanisms between the subtypes. Therefore, a common biological framework involving monoaminergic transmitters in key frontostriatal circuits may link multiple forms of impulsivity to drug self-administration and addiction-related behaviors. Further dissection of these relationships is needed before the next phase of genetic and genomic discovery will be able to reveal the biological sources of the vulnerability for addiction indexed by impulsivity.
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Affiliation(s)
- J David Jentsch
- Department of Psychology, University of California Los Angeles, Los Angeles, California
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Cunningham KA, Anastasio NC. Serotonin at the nexus of impulsivity and cue reactivity in cocaine addiction. Neuropharmacology 2014; 76 Pt B:460-78. [PMID: 23850573 PMCID: PMC4090081 DOI: 10.1016/j.neuropharm.2013.06.030] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 06/24/2013] [Accepted: 06/28/2013] [Indexed: 01/07/2023]
Abstract
Cocaine abuse and addiction remain great challenges on the public health agendas in the U.S. and the world. Increasingly sophisticated perspectives on addiction to cocaine and other drugs of abuse have evolved with concerted research efforts over the last 30 years. Relapse remains a particularly powerful clinical problem as, even upon termination of drug use and initiation of abstinence, the recidivism rates can be very high. The cycling course of cocaine intake, abstinence and relapse is tied to a multitude of behavioral and cognitive processes including impulsivity (a predisposition toward rapid unplanned reactions to stimuli without regard to the negative consequences), and cocaine cue reactivity (responsivity to cocaine-associated stimuli) cited as two key phenotypes that contribute to relapse vulnerability even years into recovery. Preclinical studies suggest that serotonin (5-hydroxytryptamine; 5-HT) neurotransmission in key neural circuits may contribute to these interlocked phenotypes well as the altered neurobiological states evoked by cocaine that precipitate relapse events. As such, 5-HT is an important target in the quest to understand the neurobiology of relapse-predictive phenotypes, to successfully treat this complex disorder and improve diagnostic and prognostic capabilities. This review emphasizes the role of 5-HT and its receptor proteins in key addiction phenotypes and the implications of current findings to the future of therapeutics in addiction. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.
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Affiliation(s)
- Kathryn A Cunningham
- Center for Addiction Research, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA.
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Functional status of the serotonin 5-HT2C receptor (5-HT2CR) drives interlocked phenotypes that precipitate relapse-like behaviors in cocaine dependence. Neuropsychopharmacology 2014; 39:370-82. [PMID: 23939424 PMCID: PMC3970795 DOI: 10.1038/npp.2013.199] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 08/02/2013] [Accepted: 08/03/2013] [Indexed: 11/08/2022]
Abstract
Relapse vulnerability in cocaine dependence is rooted in genetic and environmental determinants, and propelled by both impulsivity and the responsivity to cocaine-linked cues ('cue reactivity'). The serotonin (5-hydroxytryptamine, 5-HT) 5-HT2C receptor (5-HT2CR) within the medial prefrontal cortex (mPFC) is uniquely poised to serve as a strategic nexus to mechanistically control these behaviors. The 5-HT2CR functional capacity is regulated by a number of factors including availability of active membrane receptor pools, the composition of the 5-HT2CR macromolecular protein complex, and editing of the 5-HT2CR pre-mRNA. The one-choice serial reaction time (1-CSRT) task was used to identify impulsive action phenotypes in an outbred rat population before cocaine self-administration and assessment of cue reactivity in the form of lever presses reinforced by the cocaine-associated discrete cue complex during forced abstinence. The 1-CSRT task reliably and reproducibly identified high impulsive (HI) and low impulsive (LI) action phenotypes; HI action predicted high cue reactivity. Lower cortical 5-HT2CR membrane protein levels concomitant with higher levels of 5-HT2CR:postsynaptic density 95 complex distinguished HI rats from LI rats. The frequency of edited 5-HT2CR mRNA variants was elevated with the prediction that the protein population in HI rats favors those isoforms linked to reduced signaling capacity. Genetic loss of the mPFC 5-HT2CR induced aggregate impulsive action/cue reactivity, suggesting that depressed cortical 5-HT2CR tone confers vulnerability to these interlocked behaviors. Thus, impulsive action and cue reactivity appear to neuromechanistically overlap in rodents, with the 5-HT2CR functional status acting as a neural rheostat to regulate, in part, the intersection between these vulnerability behaviors.
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Peptide inhibitors disrupt the serotonin 5-HT2C receptor interaction with phosphatase and tensin homolog to allosterically modulate cellular signaling and behavior. J Neurosci 2013; 33:1615-30. [PMID: 23345234 DOI: 10.1523/jneurosci.2656-12.2013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Serotonin (5-hydroxytryptamine; 5-HT) signaling through the 5-HT(2C) receptor (5-HT(2C)R) is essential in normal physiology, whereas aberrant 5-HT(2C)R function is thought to contribute to the pathogenesis of multiple neural disorders. The 5-HT(2C)R interacts with specific protein partners, but the impact of such interactions on 5-HT(2C)R function is poorly understood. Here, we report convergent cellular and behavioral data that the interaction between the 5-HT(2C)R and protein phosphatase and tensin homolog (PTEN) serves as a regulatory mechanism to control 5-HT(2C)R-mediated biology but not that of the closely homologous 5-HT(2A)R. A peptide derived from the third intracellular loop of the human 5-HT(2C)R [3L4F (third loop, fourth fragment)] disrupted the association, allosterically augmented 5-HT(2C)R-mediated signaling in live cells, and acted as a positive allosteric modulator in rats in vivo. We identified the critical residues within an 8 aa fragment of the 3L4F peptide that maintained efficacy (within the picomolar range) in live cells similar to that of the 3L4F peptide. Last, molecular modeling identified key structural features and potential interaction sites of the active 3L4F peptides against PTEN. These compelling data demonstrate the specificity and importance of this protein assembly in cellular events and behaviors mediated by 5-HT(2C)R signaling and provide a chemical guidepost to the future development of drug-like peptide or small-molecule inhibitors as neuroprobes to study 5-HT(2C)R allostery and therapeutics for 5-HT(2C)R-mediated disorders.
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Cunningham KA, Anastasio NC, Fox RG, Stutz SJ, Bubar MJ, Swinford SE, Watson CS, Gilbertson SR, Rice KC, Rosenzweig-Lipson S, Moeller FG. Synergism between a serotonin 5-HT2A receptor (5-HT2AR) antagonist and 5-HT2CR agonist suggests new pharmacotherapeutics for cocaine addiction. ACS Chem Neurosci 2013; 4:110-21. [PMID: 23336050 DOI: 10.1021/cn300072u] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Accepted: 08/11/2012] [Indexed: 11/30/2022] Open
Abstract
Relapse to cocaine dependence, even after extended abstinence, involves a number of liability factors including impulsivity (predisposition toward rapid, unplanned reactions to stimuli without regard to negative consequences) and cue reactivity (sensitivity to cues associated with cocaine-taking which can promote cocaine-seeking). These factors have been mechanistically linked to serotonin (5-hydroxytryptamine, 5-HT) signaling through the 5-HT(2A) receptor (5-HT(2A)R) and 5-HT(2C)R; either a selective 5-HT(2A)R antagonist or a 5-HT(2C)R agonist suppresses impulsivity and cocaine-seeking in preclinical models. We conducted proof-of-concept analyses to evaluate whether a combination of 5-HT(2A)R antagonist plus 5-HT(2C)R agonist would have synergistic effects over these liability factors for relapse as measured in a 1-choice serial reaction time task and cocaine self-administration/reinstatement assay. Combined administration of a dose of the selective 5-HT(2A)R antagonist M100907 plus the 5-HT(2C)R agonist WAY163909, each ineffective alone, synergistically suppressed cocaine-induced hyperactivity, inherent and cocaine-evoked impulsive action, as well as cue- and cocaine-primed reinstatement of cocaine-seeking behavior. The identification of synergism between a 5-HT(2A)R antagonist plus a 5-HT(2C)R agonist to attenuate these factors important in relapse indicates the promise of a bifunctional ligand as an anti-addiction pharmacotherapeutic, setting the stage to develop new ligands with improved efficacy, potency, selectivity, and in vivo profiles over the individual molecules.
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Affiliation(s)
| | | | | | | | | | | | | | - Scott R. Gilbertson
- Department of Chemistry, University of Houston, Houston, Texas, , United States
| | - Kenner C. Rice
- Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland, , United States
| | | | - F. Gerard Moeller
- Center for Neurobehavioral Research
on Addictions, Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center Houston,
Houston, Texas, , United States
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Herin DV, Bubar MJ, Seitz PK, Thomas ML, Hillman GR, Tarasenko YI, Wu P, Cunningham KA. Elevated Expression of Serotonin 5-HT(2A) Receptors in the Rat Ventral Tegmental Area Enhances Vulnerability to the Behavioral Effects of Cocaine. Front Psychiatry 2013; 4:2. [PMID: 23390419 PMCID: PMC3565455 DOI: 10.3389/fpsyt.2013.00002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Accepted: 01/07/2013] [Indexed: 01/23/2023] Open
Abstract
The dopamine mesocorticoaccumbens pathway which originates in the ventral tegmental area (VTA) and projects to the nucleus accumbens and prefrontal cortex is a circuit important in mediating the actions of psychostimulants. The function of this circuit is modulated by the actions of serotonin (5-HT) at 5-HT(2A) receptors (5-HT(2A)R) localized to the VTA. In the present study, we tested the hypothesis that virally mediated overexpression of 5-HT(2A)R in the VTA would increase cocaine-evoked locomotor activity in the absence of alterations in basal locomotor activity. A plasmid containing the gene for the 5-HT(2A)R linked to a synthetic marker peptide (Flag) was created and the construct was packaged in an adeno-associated virus vector (rAAV-5-HT(2A)R-Flag). This viral vector (2 μl; 10(9-10) transducing units/ml) was unilaterally infused into the VTA of male rats, while control animals received an intra-VTA infusion of Ringer's solution. Virus-pretreated rats exhibited normal spontaneous locomotor activity measured in a modified open-field apparatus at 7, 14, and 21 days following infusion. After an injection of cocaine (15 mg/kg, ip), both horizontal hyperactivity and rearing were significantly enhanced in virus-treated rats (p < 0.05). Immunohistochemical analysis confirmed expression of Flag and overexpression of the 5-HT(2A)R protein. These data indicate that the vulnerability of adult male rats to hyperactivity induced by cocaine is enhanced following increased levels of expression of the 5-HT(2A)R in the VTA and suggest that the 5-HT(2A)R receptor in the VTA plays a role in regulation of responsiveness to cocaine.
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Affiliation(s)
- David V Herin
- Center for Addiction Research, University of Texas Medical Branch Galveston, TX, USA ; Department of Pharmacology and Toxicology, University of Texas Medical Branch Galveston, TX, USA
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van Wel JHP, Kuypers KPC, Theunissen EL, Bosker WM, Bakker K, Ramaekers JG. Effects of acute MDMA intoxication on mood and impulsivity: role of the 5-HT2 and 5-HT1 receptors. PLoS One 2012; 7:e40187. [PMID: 22808116 PMCID: PMC3393729 DOI: 10.1371/journal.pone.0040187] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 06/02/2012] [Indexed: 11/24/2022] Open
Abstract
MDMA induces positive mood and increases impulse control during intoxication, but only a few studies on the neuropharmacological mechanisms underlying these processes have been conducted. It was hypothesized that pretreatment with 5-HT1 and 5-HT2 receptor blockers would prevent MDMA effects on mood and impulsivity. Subjects (N = 17) participated in a double-blind, placebo controlled, within-subject design involving 6 experimental conditions consisting of pretreatment (T1) and treatment (T2). T1 preceded T2 by 30 minutes. T1–T2 combinations were: placebo-placebo, 20 mg pindolol-placebo, 50 mg ketanserin-placebo, placebo-75 mg MDMA, 20 mg pindolol-75 mg MDMA and 50 mg ketanserin-75 g MDMA. Subjects completed a Profile of Mood States (POMS) questionnaire and several impulsivity tasks (Stop signal task, Matching familiar figures task, Cue dependent reversal learning task) at 1.5 hrs post-treatment. MDMA alone increased both positive (vigor, arousal, friendliness, elation, positive mood) and negative affect (anxiety, confusion) as assessed by the POMS questionnaire. MDMA also increased stop reaction time in the Stop signal task and reaction time in the Matching familiar figures task. Pretreatment with ketanserin blocked MDMA effects on positive affect, but not negative affect. Ketanserin did not influence the effects of MDMA on impulsivity. Pindolol did not interact with MDMA on any of the measures. In conclusion, 5-HT2 receptors mediate positive moods induced by MDMA but not negative moods or impulsivity. 5-HT1 receptors do not appear to be involved in MDMA effects on mood and impulse control.
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Affiliation(s)
- Janelle H P van Wel
- Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, the Netherlands.
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Wallis D, Hill DS, Mendez IA, Abbott LC, Finnell RH, Wellman PJ, Setlow B. Initial characterization of mice null for Lphn3, a gene implicated in ADHD and addiction. Brain Res 2012; 1463:85-92. [PMID: 22575564 DOI: 10.1016/j.brainres.2012.04.053] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 04/26/2012] [Accepted: 04/28/2012] [Indexed: 02/05/2023]
Abstract
The LPHN3 gene has been associated with both attention deficit-hyperactivity disorder (ADHD) and addiction, suggesting that it may play a role in the etiology of these disorders. Unfortunately, almost nothing is known about the normal functions of this gene, which has hampered understanding of its potential pathogenic role. To begin to characterize such normal functions, we utilized a gene-trap embryonic stem cell line to generate mice mutant for the Lphn3 gene. We evaluated differential gene expression in whole mouse brain between mutant and wild type male littermates at postnatal day 0 using TaqMan gene expression assays. Most notably, we found changes in dopamine and serotonin receptors and transporters (Dat1, Drd4, 5Htt, 5Ht2a), changes in neurotransmitter metabolism genes (Th, Gad1), as well as changes in neural developmental genes (Nurr, Ncam). When mice were examined at 4-6 weeks of age, null mutants showed increased levels of dopamine and serotonin in the dorsal striatum. Finally, null mutant mice had a hyperactive phenotype in the open field test, independent of sex, and were more sensitive to the locomotor stimulant effects of cocaine. Considered together, these results suggest that Lphn3 plays a role in development and/or regulation of monoamine signaling. Given the central role for monoamines in ADHD and addiction, it seems likely that the influence of LPHN3 genotype on these disorders is mediated through alterations in monoamine signaling.
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Affiliation(s)
- Deeann Wallis
- Department of Biochemistry and Biophysics, Texas A&M University, College Station 77843-3474, USA.
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Selective serotonin 5-HT(2C) receptor activation suppresses the reinforcing efficacy of cocaine and sucrose but differentially affects the incentive-salience value of cocaine- vs. sucrose-associated cues. Neuropharmacology 2011; 61:513-23. [PMID: 21575646 DOI: 10.1016/j.neuropharm.2011.04.034] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 04/26/2011] [Accepted: 04/29/2011] [Indexed: 11/22/2022]
Abstract
Serotonin (5-HT) controls affective and motivational aspects of palatable food and drug reward and the 5-HT(2C) receptor (5-HT(2C)R) has emerged as a key regulator in this regard. We have evaluated the efficacy of a selective 5-HT(2C)R agonist, WAY 163909, in cocaine and sucrose self-administration and reinstatement assays employing parallel experimental designs in free-fed rats. WAY 163909 dose-dependently reduced the reinforcing efficacy of cocaine (ID(50) = 1.19 mg/kg) and sucrose (ID(50) = 0.7 mg/kg) as well as reinstatement (ID(50) = 0.5 mg/kg) elicited by exposure to cocaine-associated contextual cues, but not sucrose-associated contextual cues. The ID(50) of WAY 163909 predicted to decrease the reinforcing efficacy of cocaine or sucrose as well as reinstatement upon exposure to cocaine-associated cues was ∼5-12-fold lower than that predicted to suppress horizontal ambulation (ID(50) = 5.89 mg/kg) and ∼2-5-fold lower than that predicted to suppress vertical activity (ID(50) = 2.3 mg/kg). Thus, selective stimulation of the 5-HT(2C)R decreases the reinforcing efficacy of cocaine and sucrose in freely-fed rats, but differentially alters the incentive-salience value of cocaine- vs. sucrose-associated cues at doses that do not impair locomotor activity. Future research is needed to tease apart the precise contribution of 5-HT(2C)R neurocircuitry in reward and motivation and the learning and memory processes that carry the encoding for associations between environmental cues and consumption of rewarding stimuli. A more complete preclinical evaluation of these questions will ultimately allow educated proof-of-concept trials to test the efficacy of selective 5-HT(2C)R agonists as adjunctive therapy in chronic health maladies including obesity, eating disorders and drug addiction.
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