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Sagheddu C, Cancedda E, Bagheri F, Kalaba P, Muntoni AL, Lubec J, Lubec G, Sanna F, Pistis M. The Atypical Dopamine Transporter Inhibitor CE-158 Enhances Dopamine Neurotransmission in the Prefrontal Cortex of Male Rats: A Behavioral, Electrophysiological, and Microdialysis Study. Int J Neuropsychopharmacol 2023; 26:784-795. [PMID: 37725477 PMCID: PMC10674083 DOI: 10.1093/ijnp/pyad056] [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: 06/24/2023] [Accepted: 09/17/2023] [Indexed: 09/21/2023] Open
Abstract
BACKGROUND Dopamine plays a key role in several physiological functions such as motor control, learning and memory, and motivation and reward. The atypical dopamine transporter inhibitor S,S stereoisomer of 5-(((S)-((S)-(3-bromophenyl)(phenyl)methyl)sulfinyl)methyl)thiazole (CE-158) has been recently reported to promote behavioral flexibility and restore learning and memory in aged rats. METHODS Adult male rats were i.p. administered for 1 or 10 days with CE-158 at the dose of 1 or 10 mg/kg and tested for extracellular dopamine in the medial prefrontal cortex by means of intracerebral microdialysis and single unit cell recording in the same brain area. Moreover, the effects of acute and chronic CE-158 on exploratory behavior, locomotor activity, prepulse inhibition, working memory, and behavioral flexibility were also investigated. RESULTS CE-158 dose-dependently potentiated dopamine neurotransmission in the medial prefrontal cortex as assessed by intracerebral microdialysis. Moreover, repeated exposure to CE-158 at 1 mg/kg was sufficient to increase the number of active pyramidal neurons and their firing frequency in the same brain area. In addition, CE-158 at the dose of 10 mg/kg stimulates exploratory behavior to the same extent after acute or chronic treatment. Noteworthy, the chronic treatment at both doses did not induce any behavioral alterations suggestive of abuse potential (e.g., motor behavioral sensitization) or pro-psychotic-like effects such as disruption of sensorimotor gating or impairments in working memory and behavioral flexibility as measured by prepulse inhibition and Y maze. CONCLUSIONS Altogether, these findings confirm CE-158 as a promising pro-cognitive agent and contribute to assessing its preclinical safety profile in a chronic administration regimen for further translational testing.
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Affiliation(s)
- Claudia Sagheddu
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria di Monserrato, Monserrato, Cagliari, Italy
| | - Enzo Cancedda
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria di Monserrato, Monserrato, Cagliari, Italy
| | - Farshid Bagheri
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria di Monserrato, Monserrato, Cagliari, Italy
| | - Predrag Kalaba
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Anna Lisa Muntoni
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, Cittadella Universitaria di Monserrato, Monserrato, Cagliari, Italy
| | - Jana Lubec
- Programme for Proteomics, Paracelsus Medical University, Salzburg, Austria
| | - Gert Lubec
- Programme for Proteomics, Paracelsus Medical University, Salzburg, Austria
| | - Fabrizio Sanna
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria di Monserrato, Monserrato, Cagliari, Italy
| | - Marco Pistis
- Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, University of Cagliari, Cittadella Universitaria di Monserrato, Monserrato, Cagliari, Italy
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, Cittadella Universitaria di Monserrato, Monserrato, Cagliari, Italy
- Unit of Clinical Pharmacology, University Hospital, Cagliari, Italy
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Wang J, Chen Y, Zhang H. Electrophysiological Evidence of Enhanced Processing of Novel Pornographic Images in Individuals With Tendencies Toward Problematic Internet Pornography Use. Front Hum Neurosci 2022; 16:897536. [PMID: 35814959 PMCID: PMC9259837 DOI: 10.3389/fnhum.2022.897536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 06/08/2022] [Indexed: 11/24/2022] Open
Abstract
Novelty seeking is regarded as a core feature in substance use disorders. However, few studies thus far have investigated this feature in problematic Internet pornography use (PIPU). The main aim of the present study was to examine group differences in electrophysiological activity associated with novelty processing in participants with high tendencies toward PIPU vs. low tendencies using event-related potentials (ERPs). Twenty-seven participants with high tendencies toward PIPU and 25 with low tendencies toward PIPU completed a modified three-stimulus oddball task while electroencephalogram (EEG) was recorded. Participants were instructed to detect neutral target stimuli from distracting stimuli. The distracting stimuli contained a familiar sexual stimulus and a set of novel sexual stimuli. The novel-familiar difference waves were calculated to identify specific group difference in novelty effect. While both groups demonstrated a sustained novelty effect in the late positive potential (LPP) within the 500–800 ms time windows, the novelty effect was greater in the high tendencies toward PIPU group than in the low tendencies toward PIPU group. This result suggests that individuals with high tendencies toward PIPU allocate more attentional resources for novelty processing. Enhanced brain responding to novel sexual stimuli may facilitate pornographic consumption and play an essential role in the development and maintenance of PIPU.
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Tsai TY, Wang TY, Tseng HH, Chen KC, Chiu CJ, Chen PS, Yang YK. Correlation between loneliness, personality traits, and treatment outcomes in patients with methamphetamine use disorder. Sci Rep 2022; 12:8629. [PMID: 35606379 PMCID: PMC9126870 DOI: 10.1038/s41598-022-11901-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 04/22/2022] [Indexed: 11/21/2022] Open
Abstract
The aim of this study was to investigate whether loneliness and personality traits correlate with the treatment outcome of methamphetamine use disorder. In this 1-year longitudinal study, a total 106 participants (98 males, 8 females), with a mean age 36.3 ± 9.6 years were enrolled. We measured UCLA Loneliness Scale and Tridimensional Personality Questionnaire at baseline, while craving level at baseline, week 12, 24, 36, and 48. Urinary methamphetamine tests were given 17 times. For the evaluation of the data, multiple linear regression and generalized linear mixed models were used. The baseline results showed lower levels of the harm avoidance trait and higher levels of loneliness were significantly associated with higher craving levels (p=0.04 and 0.04). Moreover, loneliness was not only positively associated with craving levels (B=0.05, p<0.01) but with urinary methamphetamine positive results (B= 0.08, p=0.03) during one-year treatment. The findings suggested that loneliness was associated with poor methamphetamine treatment outcome (greater craving levels and higher proportion of positive methamphetamine urine tests) and lower harm avoidance traits are associated with higher craving levels.
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Kaplan G, Xu H, Abreu K, Feng J. DNA Epigenetics in Addiction Susceptibility. Front Genet 2022; 13:806685. [PMID: 35145550 PMCID: PMC8821887 DOI: 10.3389/fgene.2022.806685] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 01/06/2022] [Indexed: 12/22/2022] Open
Abstract
Addiction is a chronically relapsing neuropsychiatric disease that occurs in some, but not all, individuals who use substances of abuse. Relatively little is known about the mechanisms which contribute to individual differences in susceptibility to addiction. Neural gene expression regulation underlies the pathogenesis of addiction, which is mediated by epigenetic mechanisms, such as DNA modifications. A growing body of work has demonstrated distinct DNA epigenetic signatures in brain reward regions that may be associated with addiction susceptibility. Furthermore, factors that influence addiction susceptibility are also known to have a DNA epigenetic basis. In the present review, we discuss the notion that addiction susceptibility has an underlying DNA epigenetic basis. We focus on major phenotypes of addiction susceptibility and review evidence of cell type-specific, time dependent, and sex biased effects of drug use. We highlight the role of DNA epigenetics in these diverse processes and propose its contribution to addiction susceptibility differences. Given the prevalence and lack of effective treatments for addiction, elucidating the DNA epigenetic mechanism of addiction vulnerability may represent an expeditious approach to relieving the addiction disease burden.
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Foster SL, Lustberg DJ, Harbin NH, Bramlett SN, Hepler JR, Weinshenker D. RGS14 modulates locomotor behavior and ERK signaling induced by environmental novelty and cocaine within discrete limbic structures. Psychopharmacology (Berl) 2021; 238:2755-2773. [PMID: 34184126 PMCID: PMC8455459 DOI: 10.1007/s00213-021-05892-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 06/01/2021] [Indexed: 12/14/2022]
Abstract
RATIONALE In rodents, exposure to novel environments or psychostimulants promotes locomotion. Indeed, locomotor reactivity to novelty strongly predicts behavioral responses to psychostimulants in animal models of addiction. RGS14 is a plasticity-restricting protein with unique functional domains that enable it to suppress ERK-dependent signaling as well as regulate G protein activity. Although recent studies show that RGS14 is expressed in multiple limbic regions implicated in psychostimulant- and novelty-induced hyperlocomotion, its function has been examined mostly in the context of hippocampal physiology and memory. OBJECTIVE We investigated whether RGS14 modulates novelty- and cocaine-induced locomotion (NIL and CIL, respectively) and neuronal activity. METHODS We assessed Rgs14 knockout (RGS14 KO) mice and wild-type (WT) littermate controls using NIL and CIL behavioral tests, followed by quantification of c-fos and phosphorylated ERK (pERK) induction in limbic regions that normally express RGS14. RESULTS RGS14 KO mice were less active than WT controls in the NIL test, driven by avoidance of the center of the novel environment. By contrast, RGS14 KO mice demonstrated augmented peripheral locomotion in the CIL test conducted in either a familiar or novel environment. RGS14 KO mice exhibited increased thigmotaxis, as well as greater c-fos and pERK induction in the central amygdala and dorsal hippocampus, when cocaine and novelty were paired. CONCLUSIONS RGS14 KO mice exhibited anti-correlated locomotor responses to novelty and cocaine, but displayed increased thigmotaxis in response to either stimuli which was augmented by their combination. Our findings also suggest RGS14 may reduce neuronal activity in limbic subregions by inhibiting ERK-dependent signaling.
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Affiliation(s)
- Stephanie L. Foster
- Emory University School of Medicine, Department of Human Genetics, Atlanta, GA 30322
| | - Daniel J. Lustberg
- Emory University School of Medicine, Department of Human Genetics, Atlanta, GA 30322
| | - Nicholas H. Harbin
- Emory University School of Medicine, Department of Pharmacology and Chemical Biology, Atlanta, GA 30322
| | - Sara N. Bramlett
- Emory University School of Medicine, Department of Pharmacology and Chemical Biology, Atlanta, GA 30322
| | - John R. Hepler
- Emory University School of Medicine, Department of Pharmacology and Chemical Biology, Atlanta, GA 30322,Correspondence to: David Weinshenker, Ph.D., Department of Human Genetics, Emory University School of Medicine, 615 Michael St., Whitehead 301, Atlanta, GA 30322, ; John R. Hepler, Ph.D., Department of Pharmacology and Chemical Biology, Emory University School of Medicine, 1510 Clifton Rd., Atlanta, GA 30322,
| | - David Weinshenker
- , Department of Human Genetics, Emory University School of Medicine, 615 Michael St., Whitehead 301, Atlanta, GA, 30322, USA.
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Ferrer-Pérez C, Reguilón MD, Miñarro J, Rodríguez-Arias M. Oxytocin Signaling as a Target to Block Social Defeat-Induced Increases in Drug Abuse Reward. Int J Mol Sci 2021; 22:ijms22052372. [PMID: 33673448 PMCID: PMC7956822 DOI: 10.3390/ijms22052372] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/21/2021] [Accepted: 02/23/2021] [Indexed: 12/15/2022] Open
Abstract
There is huge scientific interest in the neuropeptide oxytocin (OXT) due to its putative capacity to modulate a wide spectrum of physiological and cognitive processes including motivation, learning, emotion, and the stress response. The present review seeks to increase the understanding of the role of OXT in an individual’s vulnerability or resilience with regard to developing a substance use disorder. It places specific attention on the role of social stress as a risk factor of addiction, and explores the hypothesis that OXT constitutes a homeostatic response to stress that buffers against its negative impact. For this purpose, the review summarizes preclinical and clinical literature regarding the effects of OXT in different stages of the addiction cycle. The current literature affirms that a well-functioning oxytocinergic system has protective effects such as the modulation of the initial response to drugs of abuse, the attenuation of the development of dependence, the blunting of drug reinstatement and a general anti-stress effect. However, this system is dysregulated if there is continuous drug use or chronic exposure to stress. In this context, OXT is emerging as a promising pharmacotherapy to restore its natural beneficial effects in the organism and to help rebalance the functions of the addicted brain.
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Affiliation(s)
- Carmen Ferrer-Pérez
- Department of Psychology and Sociology, University of Zaragoza, C/Ciudad Escolar s/n, 44003 Teruel, Spain;
| | - Marina D. Reguilón
- Unit of Research Psychobiology of Drug Dependence, Department of Psychobiology, Facultad de Psicología, Universitat de Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain; (M.D.R.); (J.M.)
| | - José Miñarro
- Unit of Research Psychobiology of Drug Dependence, Department of Psychobiology, Facultad de Psicología, Universitat de Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain; (M.D.R.); (J.M.)
| | - Marta Rodríguez-Arias
- Unit of Research Psychobiology of Drug Dependence, Department of Psychobiology, Facultad de Psicología, Universitat de Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain; (M.D.R.); (J.M.)
- Correspondence:
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Karino G, Senoo A, Kunikata T, Kamei Y, Yamanouchi H, Nakamura S, Shukuya M, Colman RJ, Koshiba M. Inexpensive Home Infrared Living/Environment Sensor with Regional Thermal Information for Infant Physical and Psychological Development. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17186844. [PMID: 32961676 PMCID: PMC7559736 DOI: 10.3390/ijerph17186844] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 09/12/2020] [Accepted: 09/15/2020] [Indexed: 12/24/2022]
Abstract
The use of home-based image sensors for biological and environmental monitoring provides novel insight into health and development but it is difficult to evaluate people during their normal activities in their home. Therefore, we developed a low-cost infrared (IR) technology-based motion, location, temperature and thermal environment detection system that can be used non-invasively for long-term studies in the home environment. We tested this technology along with the associated analysis algorithm to visualize the effects of parental care and thermal environment on developmental state change in a non-human primate model, the common marmoset (Callithrix jacchus). To validate this system, we first compared it to a manual analysis technique and we then assessed the development of circadian rhythms in common marmosets from postnatal day 15–45. The semi-automatically tracked biological indices of locomotion velocity (BV) and body surface temperature (BT) and the potential psychological index of place preference toward the door (BD), showed age-dependent shifts in circadian phase patterns. Although environmental variables appeared to affect circadian rhythm development, principal component analysis and signal superimposing imaging methods revealed a novel phasic pattern of BD-BT correlation day/night switching in animals older than postnatal day 38 (approximately equivalent to one year of age in humans). The origin of this switch was related to earlier development of body temperature (BT) rhythms and alteration of psychological behavior rhythms (BD) around earlier feeding times. We propose that this cost-effective, inclusive sensing and analytic technique has value for understanding developmental care conditions for which continual home non-invasive monitoring would be beneficial and further suggest the potential to adapt this technique for use in humans.
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Affiliation(s)
- Genta Karino
- Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan; (G.K.); (A.S.); (S.N.)
- Department of Pediatrics, Saitama Medical University, Saitama 350-0495, Japan; (T.K.); (H.Y.)
- Research Fellow of the Japan Society for the Promotion of Science, Tokyo 102-0083, Japan
| | - Aya Senoo
- Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan; (G.K.); (A.S.); (S.N.)
| | - Tetsuya Kunikata
- Department of Pediatrics, Saitama Medical University, Saitama 350-0495, Japan; (T.K.); (H.Y.)
| | - Yoshimasa Kamei
- Department of Obstetrics and Gynecology, Saitama Medical University, Saitama 350-0495, Japan;
| | - Hideo Yamanouchi
- Department of Pediatrics, Saitama Medical University, Saitama 350-0495, Japan; (T.K.); (H.Y.)
| | - Shun Nakamura
- Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan; (G.K.); (A.S.); (S.N.)
| | - Masanori Shukuya
- Faculty of Environmental Studies Department of Restoration Ecology and Built Environment, Tokyo City University, Kanagawa 224-8551, Japan;
| | - Ricki J. Colman
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53715, USA
- Department of Cell & Regenerative Biology, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53705, USA
- Correspondence: (R.J.C.); (M.K.)
| | - Mamiko Koshiba
- Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan; (G.K.); (A.S.); (S.N.)
- Department of Pediatrics, Saitama Medical University, Saitama 350-0495, Japan; (T.K.); (H.Y.)
- Graduate School of Science and Technology for Innovation, Yamaguchi University, Yamaguchi 755-8611, Japan
- Graduate School of Information Sciences, Tohoku University, Sendai 980-8579, Japan
- Correspondence: (R.J.C.); (M.K.)
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Ramsay DS, Kaiyala KJ, Woods SC. Individual differences in biological regulation: Predicting vulnerability to drug addiction, obesity, and other dysregulatory disorders. Exp Clin Psychopharmacol 2020; 28:388-403. [PMID: 32338936 PMCID: PMC8389185 DOI: 10.1037/pha0000371] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Physiological regulation is so fundamental to survival that natural selection has greatly favored the evolution of robust regulatory systems that use both reactive and preemptive responses to mitigate the disruptive impact of biological and environmental challenges on physiological function. In good health, robust regulatory systems provide little insight into the typically hidden complex array of sensor-effector interactions that accomplish successful regulation. Numerous health disorders have been traced to defective regulatory mechanisms, and generations of scientists have worked to discover ways to correct these defects and restore normal physiological function. Despite progress, numerous chronic health disorders remain resistant to treatment, and indeed for some disorders the incidence is increasing. We propose that an individual's susceptibility to acquire certain persistent dysregulatory disorders can be traced to interindividual variation in how that individual's regulatory system responds to challenges. Preexisting reliable individual differences among regulatory systems are typically unrecognized until appropriate regulatory challenges (e.g., exposure to a drug of abuse) lead to dysregulation (e.g., drug addiction). Specific characteristics of an individual's regulatory responsiveness may include etiological factors that participate in the acquisition, escalation and maintenance of health disorders characterized by dysregulation. By appropriately challenging a healthy individual's regulatory systems to identify its underlying characteristics, it is possible to ascertain whether an individual has an elevated risk for acquiring a dysregulated health condition and thereby enable strategies designed to prevent, rather than treat, the condition. This model is applied to drug addiction, and in addition we relate this approach to other dysregulated conditions such as obesity. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
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Affiliation(s)
- Douglas S. Ramsay
- Department of Oral Health Sciences, University of Washington
- Department of Orthodontics, University of Washington
- Department of Pediatric Dentistry, University of Washington
| | - Karl J. Kaiyala
- Department of Oral Health Sciences, University of Washington
| | - Stephen C. Woods
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati Medical Center
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Río-Martínez L, Marquez-Arrico JE, Prat G, Adan A. Temperament and Character Profile and Its Clinical Correlates in Male Patients with Dual Schizophrenia. J Clin Med 2020; 9:jcm9061876. [PMID: 32560099 PMCID: PMC7356598 DOI: 10.3390/jcm9061876] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/07/2020] [Accepted: 06/12/2020] [Indexed: 02/07/2023] Open
Abstract
Personality traits are relevant in understanding substance use disorders (SUD) and schizophrenia (SZ), but few works have also included patients with dual schizophrenia (SZ+) and personality traits. We explored personality profile in a sample of 165 male patients under treatment, using the Temperament and Character Inventory-Revised. The participants were assigned to three groups of 55 patients each, according to previous diagnosis: SUD, SZ- and SZ+ (without/with SUD). We analyzed their clinical characteristics, relating them to personality dimensions. The SUD and SZ+ groups scored higher than SZ- in Novelty/Sensation Seeking. SZ- and SZ+ presented higher Harm Avoidance and lower Persistence than the SUD group. SZ+ patients showed the lowest levels of Self-directedness, while SZ- and SZ+ had higher scores in Self-transcendence than the SUD group. Several clinical characteristics were associated with personality dimensions depending on diagnosis, and remarkably so for psychiatric symptoms in the SZ- and SZ+ groups. The three groups had a maladaptive personality profile compared to general population. Our results point to different profiles for SUD versus SZ, while both profiles appear combined in the SZ+ group, with extreme scores in some traits. Thus, considering personality endophenotypes in SZ+ could help in designing individualized interventions for this group.
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Affiliation(s)
- Laura Río-Martínez
- Department of Clinical Psychology and Psychobiology, School of Psychology, University of Barcelona, Passeig de la Vall d’Hebrón 171, 08035 Barcelona, Spain; (L.R.-M.); (J.E.M.-A.); (G.P.)
- Institute of Neurosciences, University of Barcelona, 08035 Barcelona, Spain
| | - Julia E. Marquez-Arrico
- Department of Clinical Psychology and Psychobiology, School of Psychology, University of Barcelona, Passeig de la Vall d’Hebrón 171, 08035 Barcelona, Spain; (L.R.-M.); (J.E.M.-A.); (G.P.)
| | - Gemma Prat
- Department of Clinical Psychology and Psychobiology, School of Psychology, University of Barcelona, Passeig de la Vall d’Hebrón 171, 08035 Barcelona, Spain; (L.R.-M.); (J.E.M.-A.); (G.P.)
| | - Ana Adan
- Department of Clinical Psychology and Psychobiology, School of Psychology, University of Barcelona, Passeig de la Vall d’Hebrón 171, 08035 Barcelona, Spain; (L.R.-M.); (J.E.M.-A.); (G.P.)
- Institute of Neurosciences, University of Barcelona, 08035 Barcelona, Spain
- Correspondence: ; Tel.: +34-9331-25060
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Khaksari M, Nakhaei P, Khastar H, Bakhtazad A, Rahimi K, Garmabi B. Circadian fluctuation in curiosity is a risk factor for morphine preference. BIOL RHYTHM RES 2020. [DOI: 10.1080/09291016.2020.1719682] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Mehdi Khaksari
- Addiction Research Center, Shahroud University of Medical Sciences, Shahroud, Iran
| | - Parham Nakhaei
- Student Research Committee, School of Medicine, Shahroud University of Medical Sciences, Shahroud, Iran
| | - Hosein Khastar
- School of Medicine, Shahroud University of Medical Sciences, Shahroud, Iran
| | - Atefeh Bakhtazad
- Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Kasra Rahimi
- Student Research Committee, School of Medicine, Shahroud University of Medical Sciences, Shahroud, Iran
| | - Behzad Garmabi
- School of Medicine, Shahroud University of Medical Sciences, Shahroud, Iran
- Study and Treatment of Circadian Rhythms Research Center, Shahroud University of Medical Sciences, Shahroud, Iran
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Kuhn BN, Kalivas PW, Bobadilla AC. Understanding Addiction Using Animal Models. Front Behav Neurosci 2019; 13:262. [PMID: 31849622 PMCID: PMC6895146 DOI: 10.3389/fnbeh.2019.00262] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 11/15/2019] [Indexed: 12/13/2022] Open
Abstract
Drug addiction is a neuropsychiatric disorder with grave personal consequences that has an extraordinary global economic impact. Despite decades of research, the options available to treat addiction are often ineffective because our rudimentary understanding of drug-induced pathology in brain circuits and synaptic physiology inhibits the rational design of successful therapies. This understanding will arise first from animal models of addiction where experimentation at the level of circuits and molecular biology is possible. We will review the most common preclinical models of addictive behavior and discuss the advantages and disadvantages of each. This includes non-contingent models in which animals are passively exposed to rewarding substances, as well as widely used contingent models such as drug self-administration and relapse. For the latter, we elaborate on the different ways of mimicking craving and relapse, which include using acute stress, drug administration or exposure to cues and contexts previously paired with drug self-administration. We further describe paradigms where drug-taking is challenged by alternative rewards, such as appetitive foods or social interaction. In an attempt to better model the individual vulnerability to drug abuse that characterizes human addiction, the field has also established preclinical paradigms in which drug-induced behaviors are ranked by various criteria of drug use in the presence of negative consequences. Separation of more vulnerable animals according to these criteria, along with other innate predispositions including goal- or sign-tracking, sensation-seeking behavior or impulsivity, has established individual genetic susceptibilities to developing drug addiction and relapse vulnerability. We further examine current models of behavioral addictions such as gambling, a disorder included in the DSM-5, and exercise, mentioned in the DSM-5 but not included yet due to insufficient peer-reviewed evidence. Finally, after reviewing the face validity of the aforementioned models, we consider the most common standardized tests used by pharmaceutical companies to assess the addictive potential of a drug during clinical trials.
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Affiliation(s)
- Brittany N Kuhn
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, United States
| | - Peter W Kalivas
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, United States
| | - Ana-Clara Bobadilla
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, United States
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12
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Modelling Differential Vulnerability to Substance Use Disorder in Rodents: Neurobiological Mechanisms. Handb Exp Pharmacol 2019; 258:203-230. [PMID: 31707470 DOI: 10.1007/164_2019_300] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Despite the prevalence of drug use within society, only a subset of individuals actively taking addictive drugs lose control over their intake and develop compulsive drug-seeking and intake that typifies substance use disorder (SUD). Although research in this field continues to be an important and dynamic discipline, the specific neuroadaptations that drive compulsive behaviour in humans addicted to drugs and the neurobiological mechanisms that underlie an individual's innate susceptibility to SUD remain surprisingly poorly understood. Nonetheless, it is clear from research within the clinical domain that some behavioural traits are recurrently co-expressed in individuals with SUD, thereby inviting the hypothesis that certain behavioural endophenotypes may be predictive, or at least act in some way, to modify an individual's probability for developing this disorder. The analysis of such endophenotypes and their catalytic relationship to the expression of addiction-related behaviours has been greatly augmented by experimental approaches in rodents that attempt to capture diagnostically relevant aspects of this progressive brain disorder. This work has evolved from an early focus on aberrant drug reinforcement mechanisms to a now much richer account of the putatively impaired cognitive control processes that ultimately determine individual trajectories to compulsive drug-related behaviours. In this chapter we discuss the utility of experimental approaches in rodents designed to elucidate the neurobiological and genetic underpinnings of so-called risk traits and how these innate vulnerabilities collectively contribute to the pathogenesis of SUD.
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Rodríguez-Ortega E, Cubero I. Environmental Enrichment Modulates Drug Addiction and Binge-Like Consumption of Highly Rewarding Substances: A Role for Anxiety and Compulsivity Brain Systems? Front Behav Neurosci 2018; 12:295. [PMID: 30555310 PMCID: PMC6281824 DOI: 10.3389/fnbeh.2018.00295] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 11/15/2018] [Indexed: 01/09/2023] Open
Abstract
Drug addiction is a chronic disorder comprising components of both impulsivity and compulsivity in the so called “addiction cycle” which develops over time from early non-dependent, repetitive, binge-consumption to later post-dependent compulsive consumption. Thus, frequent binge-like intake is a typical pattern of excessive drug intake characteristic of the pre-dependent phase of the addiction cycle, which represent an important risk factor to develop addiction in vulnerable individuals. In this framework, it is of paramount interest to further understand the earliest stage of the addiction cycle so novel approaches would emerge aimed to control repetitive episodes of binge-consumption in non-dependent subjects, protecting vulnerable individuals from transition to dependence. Environmental enrichment (EE) is a preclinical animal model in which animals are housed under novel, social enriched conditions, which allows exercising and provides sensory and cognitive stimulation. EE promotes important improvements for a variety of cognitive processes and clear therapeutic and protective effects preventing ethanol (EtOH) and drug addiction as well. Interestingly, recent observations suggest that EE might additionally modulate binge-like intake of highly palatable caloric substances, including EtOH, which suggests the ability of EE to regulate consumption during the initial stage of the addiction cycle. We have proposed that EE protective and therapeutic effects on binge-consumption of palatable substances might primarily be mediated by the modulatory control that EE exerts on anxiety and impulsivity/compulsivity traits, which are all risk factors favoring transition to drug addiction.
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Affiliation(s)
| | - Inmaculada Cubero
- Departamento de Psicología, Universidad de Almería, Almería, Spain.,Centro de Evaluación y Rehabilitación Neuropsicológica (CERNEP), Universidad de Almería, Almería, Spain
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Rodríguez-Ortega E, de la Fuente L, de Amo E, Cubero I. Environmental Enrichment During Adolescence Acts as a Protective and Therapeutic Tool for Ethanol Binge-Drinking, Anxiety-Like, Novelty Seeking and Compulsive-Like Behaviors in C57BL/6J Mice During Adulthood. Front Behav Neurosci 2018; 12:177. [PMID: 30177875 PMCID: PMC6110170 DOI: 10.3389/fnbeh.2018.00177] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 07/30/2018] [Indexed: 12/21/2022] Open
Abstract
Repetitive drug/ethanol (EtOH) binge-like consumption during pre-addictive stages favors a transition to addiction in vulnerable organisms. Experimental evidence points to the therapeutic and preventive effects of environmental enrichment (EE) on drug and EtOH addiction; however, little is known regarding EE modulation of binge-like consumption in non-dependent organisms. Here, we explore the impact of early EE on binge-like EtOH consumption: (1) we test whether early EE exposure prevents binge-like EtOH intake (20% v/v) in adult mice under an intermittent drinking in the dark (iDID) schedule; (2) we evaluate the therapeutic effects of EE housing conditions on binge-like EtOH consumption in adult animals; and (3) we compare novelty-seeking and compulsive-like behaviors, and anxiety-like behavior, as measured by the Hole Board (HB) and Elevated Plus Maze (EPM) tests, respectively, in adult EE/standard environment (SE) animals. Adolescent (postnatal day 28; PND28) mice were randomly allocated to two housing conditions (4 animals/cage): EE or SE. At PND67 all the animals were exposed to a schedule of EtOH binge-like iDID. On PND92 half of the animals in each environmental condition (EE and SE) were randomly allocated to two subgroups in a crossover design, where environmental conditions were kept similar to those previously experienced or switched, finally leading to four experimental conditions: EE-EE, EE-SE, SE-SE, and SE-EE. EtOH binge-like consumption continued until PND140, when EPM and HB tests were finally conducted. The main observations were: (1) EE-reared mice showed lower EtOH binge-like intake than SE-reared mice during adulthood, which supports a protective role for EE. (2) when adult EtOH drinking SE-reared mice were switched to EE conditions, a reduction in EtOH binge-like consumption was observed, suggesting a therapeutic role for EE; however, losing EE during adulthood triggered a progressive increase in EtOH binge-like intake. Moreover, (3) EE-housed adult animals with long-term exposure to EtOH binge-drinking showed lower anxiety-like, compulsive-like, and novelty-seeking behaviors than SE-housed mice, irrespective of the specific housing conditions during adolescence. We discuss the primary impact of EE on anxiety-like neurobehavioral brain systems through which it secondarily modulates EtOH binge-like drinking.
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Affiliation(s)
| | | | - Enedina de Amo
- Departmento de Psicología, Universidad de Almería, Almería, Spain
| | - Inmaculada Cubero
- Departmento de Psicología, Universidad de Almería, Almería, Spain.,CERNEP, Universidad de Almería, Almería, Spain
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15
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Leurquin-Sterk G, Ceccarini J, Crunelle CL, Weerasekera A, de Laat B, Himmelreich U, Bormans G, Van Laere K. Cerebral dopaminergic and glutamatergic transmission relate to different subjective responses of acute alcohol intake: an in vivo multimodal imaging study. Addict Biol 2018; 23:931-944. [PMID: 28884874 DOI: 10.1111/adb.12542] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 06/14/2017] [Accepted: 07/03/2017] [Indexed: 12/21/2022]
Abstract
Converging preclinical evidence links extrastriatal dopamine release and glutamatergic transmission via the metabotropic glutamate receptor 5 (mGluR5) to the rewarding properties of alcohol. To date, human evidence is lacking on how and where in the brain these processes occur. Mesocorticolimbic dopamine release upon intravenous alcohol administration and mGluR5 availability were measured in 11 moderate social drinkers by single-session [18 F]fallypride and [18 F]FPEB positron emission tomography, respectively. Additionally, baseline and postalcohol glutamate and glutamine levels in the anterior cingulate cortex (ACC) were measured by using proton-magnetic resonance spectroscopy. To investigate differences in reward domains linked to both neurotransmitters, regional imaging data were related to subjective alcohol responses. Alcohol induced significant [18 F]fallypride displacement in the prefrontal cortex (PFC), temporal and parietal cortices and thalamus (P < 0.05, corrected for multiple comparisons). Dopamine release in the ACC and orbitofrontal and ventromedial PFCs were correlated with subjective 'liking' and 'wanting' effects (P < 0.05). In contrast, baseline mGluR5 availability was positively correlated with the 'high' effect of alcohol in dorsolateral, ventrolateral and ventromedial PFCs and in the medial temporal lobe, thalamus and caudate nucleus (P < 0.05). Although neither proton-magnetic resonance spectroscopy glutamate nor glutamine levels were affected by alcohol, baseline ACC glutamate levels were negatively associated with the alcohol 'liking' effect (P < 0.003). These data reveal new mechanistic understanding and differential neurobiological underpinnings of the effects of acute alcohol consumption on human behavior. Specifically, prefrontal dopamine release may encode alcohol 'liking' and 'wanting' effects in specific areas underlying value processing and motivation, whereas mGluR5 availability in distinct prefrontal-temporal-subcortical regions is more related to the alcohol 'high' effect.
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Affiliation(s)
- Gil Leurquin-Sterk
- Department of Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology; University Hospitals Leuven; Belgium
| | - Jenny Ceccarini
- Department of Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology; University Hospitals Leuven; Belgium
| | - Cleo Lina Crunelle
- Toxicological Center, University of Antwerp, Department of Psychiatry; University Hospital Brussels; Belgium
| | | | - Bart de Laat
- Department of Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology; University Hospitals Leuven; Belgium
- MoSAIC, Molecular Small Animal Imaging Center; Belgium
| | - Uwe Himmelreich
- Department of Imaging and Pathology; Biomedical MRI/MoSAIC; Belgium
| | | | - Koen Van Laere
- Department of Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology; University Hospitals Leuven; Belgium
- MoSAIC, Molecular Small Animal Imaging Center; Belgium
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16
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Pastor V, Pallarés ME, Antonelli MC. Prenatal stress increases adult vulnerability to cocaine reward without affecting pubertal anxiety or novelty response. Behav Brain Res 2018; 339:186-194. [DOI: 10.1016/j.bbr.2017.11.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/26/2017] [Accepted: 11/26/2017] [Indexed: 12/22/2022]
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Egervari G, Ciccocioppo R, Jentsch JD, Hurd YL. Shaping vulnerability to addiction - the contribution of behavior, neural circuits and molecular mechanisms. Neurosci Biobehav Rev 2018; 85:117-125. [PMID: 28571877 PMCID: PMC5708151 DOI: 10.1016/j.neubiorev.2017.05.019] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 05/11/2017] [Accepted: 05/22/2017] [Indexed: 12/11/2022]
Abstract
Substance use disorders continue to impose increasing medical, financial and emotional burdens on society in the form of morbidity and overdose, family disintegration, loss of employment and crime, while advances in prevention and treatment options remain limited. Importantly, not all individuals exposed to abused substances effectively develop the disease. Genetic factors play a significant role in determining addiction vulnerability and interactions between innate predisposition, environmental factors and personal experiences are also critical. Thus, understanding individual differences that contribute to the initiation of substance use as well as on long-term maladaptations driving compulsive drug use and relapse propensity is of critical importance to reduce this devastating disorder. In this paper, we discuss current topics in the field of addiction regarding individual vulnerability related to behavioral endophenotypes, neural circuits, as well as genetics and epigenetic mechanisms. Expanded knowledge of these factors is of importance to improve and personalize prevention and treatment interventions in the future.
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Affiliation(s)
- Gabor Egervari
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 10029 New York, NY, USA; Department of Neuroscience, Icahn School of Medicine at Mount Sinai, 10029 New York, NY, USA
| | - Roberto Ciccocioppo
- School of Pharmacy, Pharmacology Unit, University of Camerino, 62032 Camerino, Italy
| | - J David Jentsch
- Department of Psychology, Binghamton University, 13902 Binghamton, NY, USA
| | - Yasmin L Hurd
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 10029 New York, NY, USA; Department of Neuroscience, Icahn School of Medicine at Mount Sinai, 10029 New York, NY, USA.
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Abstract
An increasing emphasis has been placed on the development and use of animal models of addiction that capture defining features of human drug addiction, including escalation/binge drug use, enhanced motivation for the drug, preference for the drug over other reward options, use despite negative consequences, and enhanced drug-seeking/relapse vulnerability. The need to examine behavior in both males and females has also become apparent given evidence demonstrating that the addiction process occurs differently in males and females. This review discusses the procedures that are used to model features of addiction in animals, as well as factors that influence their development. Individual differences are also discussed, with a particular focus on sex differences. While no one procedure consistently produces all characteristics, different models have been developed to focus on certain characteristics. A history of escalating/binge patterns of use appears to be critical for producing other features characteristic of addiction, including an enhanced motivation for the drug, enhanced drug seeking, and use despite negative consequences. These characteristics tend to emerge over abstinence, and appear to increase rather than decrease in magnitude over time. In females, these characteristics develop sooner during abstinence and/or following less drug exposure as compared to males, and for psychostimulant addiction, may require estradiol. Although preference for the drug over other reward options has been demonstrated in non-human primates, it has been more difficult to establish in rats. Future research is needed to define the parameters that optimally induce each of these features of addiction in the majority of animals. Such models are essential for advancing our understanding of human drug addiction and its treatment in men and women.
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Affiliation(s)
- Wendy J Lynch
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA 22904, USA.
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Liang CS, Ho PS, Yen CH, Chen CY, Kuo SC, Huang CC, Yeh YW, Ma KH, Huang SY. The relationship between the striatal dopamine transporter and novelty seeking and cognitive flexibility in opioid dependence. Prog Neuropsychopharmacol Biol Psychiatry 2017; 74:36-42. [PMID: 27940252 DOI: 10.1016/j.pnpbp.2016.12.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Revised: 11/18/2016] [Accepted: 12/05/2016] [Indexed: 12/31/2022]
Abstract
Novelty seeking (NS) is a core personality trait that primes the susceptibility to drug addiction. Striatal dopamine activity contributes to cognitive flexibility, an important cognitive strategy to inhibit impulsivity and compulsive drug-seeking behavior. Evidence supports the association between dopamine and NS. Opioid-dependent patients show higher levels of NS, and repeated opioid exposure can cause cognitive deficits including poor cognitive flexibility and impaired impulse control. However, in opioid-dependent patients, the link between NS, striatal dopamine activity, and cognitive flexibility is still unclear. We recruited 22 opioid-dependent individuals and 30 age- and sex-matched healthy controls. Single-photon emission computed tomography with [99mTc]TRODAT-1 as a ligand was used to measure the striatal dopamine transporter (DAT) availability. The Trail Making Test (TMT) was performed to assess cognitive flexibility. Cloninger's Tridimensional Personality Questionnaire (TPQ) was used to measure NS. We found that in opioid-dependent patients, the striatal DAT availability was lower and negatively associated with TMT Part B÷Part A. Moreover, an inverted-U shape significantly matched the scores of NS as a function of the striatal DAT availability, with maximum NS potential in the midrange of the DAT availability. An extra sum-of-squares F test was conducted, indicating that a quadratic model fitted the association between the DAT and NS better than a linear model did. In brief, in opioid-dependent patients, the striatal DAT availability is nonlinearly linked to NS and linearly linked to cognitive flexibility. The role of the striatal DAT in the transition from controlled to compulsive opioid use warrants further research.
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Affiliation(s)
- Chih-Sung Liang
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Beitou Branch, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Pei-Shen Ho
- Department of Psychiatry, Beitou Branch, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Che-Hung Yen
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Neurology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Chun-Yen Chen
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Shin-Chang Kuo
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Chang-Chih Huang
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Taipei Branch, Buddhist Tzu Chi General Hospital, Taipei, Taiwan, ROC
| | - Yi-Wei Yeh
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Kuo-Hsing Ma
- Department of anatomy and biology, National Defense Medical Center, Taipei, Taiwan, ROC
| | - San-Yuan Huang
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
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20
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Role of dopamine neurotransmission in the long-term effects of repeated social defeat on the conditioned rewarding effects of cocaine. Prog Neuropsychopharmacol Biol Psychiatry 2016; 71:144-54. [PMID: 27476156 DOI: 10.1016/j.pnpbp.2016.07.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 06/27/2016] [Accepted: 07/23/2016] [Indexed: 02/06/2023]
Abstract
Numerous studies report that social defeat stress alters dopamine (DA) neurotransmission in several areas of the brain. Alterations of the mesolimbic dopaminergic pathway are believed to be responsible for the increased vulnerability to drug use observed as a result of social stress. In the present study, we evaluated the influence of DA receptors on the long-term effect of repeated social defeat (RSD) on the conditioned rewarding and reinstating effects of cocaine. For this purpose, the D1R antagonist SCH 23390 and the D1R antagonist raclopride were administered 30min before each social defeat and a cocaine-induced CPP procedure was initiated three weeks later. The expression of the D1R and D2R was also measured in the cortex and hippocampus throughout the entire procedure. Mice exposed to RSD showed an increase in the conditioned rewarding effects of cocaine that was blocked by both DA receptors antagonists when a subthreshold dose of cocaine was employed. However, while the vulnerability to reinstatement of the preference induced by 25mg/kg cocaine-induced CPP was abolished by the D1R antagonist, it was practically unaffected by raclopride. Increases in D2R receptor levels were observed in the cortex of defeated animals after the first and fourth social defeats and in the hippocampus 3weeks later. Nevertheless, D1R receptor levels in the hippocampus decreased only after the last social defeat. Our results confirm that RSD enhances the conditioned rewarding effects of cocaine and that both DA receptors are involved in this enduring effect of social stress.
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