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Blood glutamine synthetase signaling in alcohol use disorder and racial disparity. Transl Psychiatry 2022; 12:71. [PMID: 35194024 PMCID: PMC8863875 DOI: 10.1038/s41398-022-01837-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 01/31/2022] [Accepted: 02/02/2022] [Indexed: 01/01/2023] Open
Abstract
As of 2018, 14.4 million adults ages 18 and older in the U.S had alcohol use disorder (AUD). However, only about 8% of adults who had AUD in the past year received treatment. Surveys have also shown racial disparities regarding AUD treatments. Thus, it is imperative to identify racial disparities in AUD patients, as it may indicate a specific underlying pathophysiology in an AUD subpopulation. To identify racial disparity in AUD, we enrolled 64 cohorts, including 26 AUD participants and 38 healthy controls, from Northwest Louisiana using community-based enrollment. Then, we used psychometric scales to assess alcohol drinking patterns and measured blood metabolites change using LC-MS/MS. Alcohol-related scales from the questionnaires did not differ between the Caucasian AUD participants and African-American AUD participants. From blood metabolomics analyses, we identified that 6 amino acids were significantly different by AUD status and or race. Interestingly, Caucasian AUD participants had a higher glutamate metabolism mediated by glutamine synthetase (GS). The correlation between blood glutamate/glutamine ratio and GS activity was only significant in the Caucasian AUD group whereas no changes were observed in African-American AUD group or controls. Taken together, our findings from this sample population demonstrate that blood GS is a potential biomarker associated with Caucasian AUD, which is an important step towards the application of a new pharmacological treatment for AUD.
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Shnitko TA, Taylor SC, Stringfield SJ, Zandy SL, Cofresí RU, Doherty JM, Lynch WB, Boettiger CA, Gonzales RA, Robinson DL. Acute phenylalanine/tyrosine depletion of phasic dopamine in the rat brain. Psychopharmacology (Berl) 2016; 233:2045-2054. [PMID: 26944052 PMCID: PMC4864125 DOI: 10.1007/s00213-016-4259-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 02/17/2016] [Indexed: 12/26/2022]
Abstract
RATIONALE Dopamine plays a critical role in striatal and cortical function, and depletion of the dopamine precursors phenylalanine and tyrosine is used in humans to temporarily reduce dopamine and probe the role of dopamine in behavior. This method has been shown to alter addiction-related behaviors and cognitive functioning presumably by reducing dopamine transmission, but it is unclear what specific aspects of dopamine transmission are altered. OBJECTIVES We performed this study to confirm that administration of an amino acid mixture omitting phenylalanine and tyrosine (Phe/Tyr[-]) reduces tyrosine tissue content in the prefrontal cortex (PFC) and nucleus accumbens (NAc), and to test the hypothesis that Phe/Tyr[-] administration reduces phasic dopamine release in the NAc. METHODS Rats were injected with a Phe/Tyr[-] amino acid mixture, a control amino acid mixture, or saline. High-performance liquid chromatography was used to determine the concentration of tyrosine, dopamine, or norepinephrine in tissue punches from the PFC and ventral striatum. In a separate group of rats, phasic dopamine release was measured with fast-scan cyclic voltammetry in the NAc core after injection with either the Phe/Tyr[-] mixture or the control amino acid solution. RESULTS Phe/Tyr[-] reduced tyrosine content in the PFC and NAc, but dopamine and norepinephrine tissue content were not reduced. Moreover, Phe/Tyr[-] decreased the frequency of dopamine transients, but not their amplitude, in freely moving rats. CONCLUSIONS These results indicate that depletion of tyrosine via Phe/Tyr[-] decreases phasic dopamine transmission, providing insight into the mechanism by which this method modifies dopamine-dependent behaviors in human imaging studies.
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Affiliation(s)
- Tatiana A. Shnitko
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, NC, USA
| | - Sarah C. Taylor
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, NC, USA
| | - Sierra J. Stringfield
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, NC, USA,Neurobiology Curriculum, University of North Carolina, Chapel Hill, NC, USA
| | - Shannon L. Zandy
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX, USA
| | - Roberto U. Cofresí
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX, USA
| | - James M. Doherty
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX, USA
| | - William B. Lynch
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, NC, USA
| | - Charlotte A. Boettiger
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, NC, USA,Neurobiology Curriculum, University of North Carolina, Chapel Hill, NC, USA,Department of Psychology and Neuroscience, University of North Carolina, Chapel Hill, NC, USA
| | - Rueben A. Gonzales
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX, USA
| | - Donita L. Robinson
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, NC, USA,Neurobiology Curriculum, University of North Carolina, Chapel Hill, NC, USA,Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA
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Dopamine Depletion Reduces Food-Related Reward Activity Independent of BMI. Neuropsychopharmacology 2016; 41:1551-9. [PMID: 26450814 PMCID: PMC4832016 DOI: 10.1038/npp.2015.313] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/02/2015] [Accepted: 09/21/2015] [Indexed: 01/09/2023]
Abstract
Reward sensitivity and possible alterations in the dopaminergic-reward system are associated with obesity. We therefore aimed to investigate the influence of dopamine depletion on food-reward processing. We investigated 34 female subjects in a randomized placebo-controlled, within-subject design (body mass index (BMI)=27.0 kg/m(2) ±4.79 SD; age=28 years ±4.97 SD) using an acute phenylalanine/tyrosine depletion drink representing dopamine depletion and a balanced amino acid drink as the control condition. Brain activity was measured with functional magnetic resonance imaging during a 'wanting' and 'liking' rating of food items. Eating behavior-related traits and states were assessed on the basis of questionnaires. Dopamine depletion resulted in reduced activation in the striatum and higher activation in the superior frontal gyrus independent of BMI. Brain activity during the wanting task activated a more distributed network than during the liking task. This network included gustatory, memory, visual, reward, and frontal regions. An interaction effect of dopamine depletion and the wanting/liking task was observed in the hippocampus. The interaction with the covariate BMI was significant in motor and control regions but not in the striatum. Our results support the notion of altered brain activity in the reward and prefrontal network with blunted dopaminergic action during food-reward processing. This effect is, however, independent of BMI, which contradicts the reward-deficiency hypothesis. This hints to the hypothesis suggesting a different or more complex mechanism underlying the dopaminergic reward function in obesity.
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Barrett SP, Jemcov A, Darredeau C. Patterns and Effects of Alcohol and Psychostimulant Co-administration: a Brief Review of Pharmacological Considerations and Subjective Responses. CURRENT ADDICTION REPORTS 2016. [DOI: 10.1007/s40429-016-0080-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Robinson MJF, Fischer AM, Ahuja A, Lesser EN, Maniates H. Roles of "Wanting" and "Liking" in Motivating Behavior: Gambling, Food, and Drug Addictions. Curr Top Behav Neurosci 2016; 27:105-136. [PMID: 26407959 DOI: 10.1007/7854_2015_387] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The motivation to seek out and consume rewards has evolutionarily been driven by the urge to fulfill physiological needs. However in a modern society dominated more by plenty than scarcity, we tend to think of motivation as fueled by the search for pleasure. Here, we argue that two separate but interconnected subcortical and unconscious processes direct motivation: "wanting" and "liking." These two psychological and neuronal processes and their related brain structures typically work together, but can become dissociated, particularly in cases of addiction. In drug addiction, for example, repeated consumption of addictive drugs sensitizes the mesolimbic dopamine system, the primary component of the "wanting" system, resulting in excessive "wanting" for drugs and their cues. This sensitizing process is long-lasting and occurs independently of the "liking" system, which typically remains unchanged or may develop a blunted pleasure response to the drug. The result is excessive drug-taking despite minimal pleasure and intense cue-triggered craving that may promote relapse long after detoxification. Here, we describe the roles of "liking" and "wanting" in general motivation and review recent evidence for a dissociation of "liking" and "wanting" in drug addiction, known as the incentive sensitization theory (Robinson and Berridge 1993). We also make the case that sensitization of the "wanting" system and the resulting dissociation of "liking" and "wanting" occurs in both gambling disorder and food addiction.
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Affiliation(s)
- M J F Robinson
- Department of Psychology, Wesleyan University, 207 High Street, Judd Hall, Middletown, CT, 06459, USA.
| | - A M Fischer
- Department of Psychology, Wesleyan University, 207 High Street, Judd Hall, Middletown, CT, 06459, USA
| | - A Ahuja
- Department of Psychology, Wesleyan University, 207 High Street, Judd Hall, Middletown, CT, 06459, USA
| | - E N Lesser
- Department of Psychology, Wesleyan University, 207 High Street, Judd Hall, Middletown, CT, 06459, USA
| | - H Maniates
- Department of Psychology, Wesleyan University, 207 High Street, Judd Hall, Middletown, CT, 06459, USA
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6
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Stimulant and motivational effects of alcohol: Lessons from rodent and primate models. Pharmacol Biochem Behav 2014; 122:37-52. [DOI: 10.1016/j.pbb.2014.03.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 02/17/2014] [Accepted: 03/06/2014] [Indexed: 11/22/2022]
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Bjork JM, Grant SJ, Chen G, Hommer DW. Dietary tyrosine/phenylalanine depletion effects on behavioral and brain signatures of human motivational processing. Neuropsychopharmacology 2014; 39:595-604. [PMID: 23995581 PMCID: PMC3895237 DOI: 10.1038/npp.2013.232] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 08/26/2013] [Accepted: 08/27/2013] [Indexed: 11/09/2022]
Abstract
Dopamine (DA) neurotransmission is critical for motivational processing. We assessed whether disruption of DA synthesis in healthy controls using an amino-acid beverage devoid of catecholamine precursors (tyrosine-phenylalanine depletion (TPD)) would blunt recruitment of the nucleus accumbens (NAcc) by rewards. Sixteen controls ingested each of a tyr/phe-depleting beverage (DEP) or a tyr/phe-balanced (BAL) control beverage in two laboratory visits. Five hours after consumption of each drink, subjects underwent functional magnetic resonance imaging while they viewed anticipatory cues to respond to a target to either win money or avoid losing money. TPD did not exert main effects on mood or on task behavior, but affected brain activation. In right NAcc, TPD blunted activation by anticipation of high rewards. In left NAcc, recruitment anticipating high rewards was modulated by individual differences in mood change across the DEP drink day, where subjects whose mood worsened following TPD (relative to within-day mood change under BAL conditions) also showed lower activation under DEP conditions relative to BAL conditions. Exploratory analysis indicated that TPD qualitatively blunted the voxel-wise spatial extent of suprathreshold activation by reward anticipation. Finally, loss outcomes activated anterior insula under DEP conditions but not under BAL conditions. These data indicate that: (1) dietary depletion of catacholamine precursors will blunt dopaminergic mesolimbic activity, and (2) in controls, synthetic pathways of this neurocircuitry maintain sufficient buffering capacity to resist an effect on motivated behavior. Additional studies are needed to determine if clinical populations would show similar resistance to behavioral effects of TPD.
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Affiliation(s)
- James M Bjork
- Division of Clinical Neuroscience and Behavioral Research, National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, USA,Division of Clinical Neuroscience and Behavioral Research, National Institute on Drug Abuse, National Institutes of Health, 6001 Executive Boulevard, Room 3163, Bethesda, MD 20892, USA, Tel: +1 301 443 3209, Fax: +1 301 443 6814, E-mail:
| | - Steven J Grant
- Division of Clinical Neuroscience and Behavioral Research, National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, USA
| | - Gang Chen
- Scientific and Statistical Computing Core, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Daniel W Hommer
- Laboratory of Clinical and Translational Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
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Setiawan E, Pihl RO, Dagher A, Schlagintweit H, Casey KF, Benkelfat C, Leyton M. Differential Striatal Dopamine Responses Following Oral Alcohol in Individuals at Varying Risk for Dependence. Alcohol Clin Exp Res 2013; 38:126-34. [DOI: 10.1111/acer.12218] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 05/15/2013] [Indexed: 11/26/2022]
Affiliation(s)
- Elaine Setiawan
- Department of Psychiatry; McGill University; Montréal Québec Canada
- Department of Neurology and Neurosurgery; McGill University; Montréal Québec Canada
| | - Robert O. Pihl
- Department of Psychiatry; McGill University; Montréal Québec Canada
- Department of Psychology; McGill University; Montréal Québec Canada
| | - Alain Dagher
- Department of Neurology and Neurosurgery; McGill University; Montréal Québec Canada
| | | | - Kevin F. Casey
- Department of Psychiatry; McGill University; Montréal Québec Canada
- Department of Neurology and Neurosurgery; McGill University; Montréal Québec Canada
| | - Chawki Benkelfat
- Department of Psychiatry; McGill University; Montréal Québec Canada
- Department of Neurology and Neurosurgery; McGill University; Montréal Québec Canada
| | - Marco Leyton
- Department of Psychiatry; McGill University; Montréal Québec Canada
- Department of Neurology and Neurosurgery; McGill University; Montréal Québec Canada
- Department of Psychology; McGill University; Montréal Québec Canada
- Center for Studies in Behavioral Neurobiology; Concordia University; Montréal Québec Canada
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Acute oral administration of a tyrosine and phenylalanine-free amino acid mixture reduces exercise capacity in the heat. Eur J Appl Physiol 2013; 113:1511-22. [DOI: 10.1007/s00421-012-2577-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Accepted: 12/21/2012] [Indexed: 01/09/2023]
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10
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Sun HQ, Liu Y, Li P, Bao YP, Sheng LX, Zhang RL, Cao YJ, Di XL, Yang FD, Wang F, Luo YX, Lu L. Effects of acute combined serotonin and dopamine depletion on cue-induced drinking intention/desire and cognitive function in patients with alcohol dependence. Drug Alcohol Depend 2012; 124:200-6. [PMID: 22325080 DOI: 10.1016/j.drugalcdep.2012.01.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2011] [Revised: 12/31/2011] [Accepted: 01/01/2012] [Indexed: 12/22/2022]
Abstract
BACKGROUND Alcohol cues can precipitate the desire to drink and cause relapse in recovering alcohol-dependent patients. Serotonin and dopamine may play a role in alcohol cue-induced craving. Acute combined tryptophan (Trp), tyrosine (Tyr), and phenylalanine (Phe) depletion (CMD) in the diet attenuates the synthesis of serotonin and dopamine in the human brain. However, no study of the effects of acute CMD has been previously conducted. Therefore, we investigated whether the attenuation of serotonin and dopamine synthesis changes cue-induced alcohol craving in recently abstinent alcoholics. METHODS In this double-blind, randomized, placebo-controlled, crossover design, 12 male patients who met the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, criteria for alcohol dependence were divided into two conditions: (1) monoamine depletion (i.e., consumption of a concentrated amino acid beverage that resulted in a rapid and significant decrease in plasma-free Tyr/Phe/Trp) and (2) balanced condition (i.e., consumption of a similar beverage that contained Tyr/Phe/Trp). The participants were scheduled for two experimental sessions, with an interval of ≥7 days. The cue-induced craving test session was conducted 6h after each amino acid beverage administration. Drinking urge, blood pressure, heart rate, working memory, and attention/psychomotor performance were assessed before and after administration. RESULTS Compared with the balanced condition, the monoamine depletion condition significantly increased drinking intention/desire and diastolic blood pressure. Cognitive performance was not different between the two conditions. CONCLUSIONS Acute combined serotonin and dopamine depletion may increase drinking intention/desire and diastolic blood pressure without influencing cognitive function.
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Affiliation(s)
- Hong-Qiang Sun
- National Institute on Drug Dependence, Peking University, Beijing 100191, China.
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Liggins J, Pihl RO, Benkelfat C, Leyton M. The dopamine augmenter L-DOPA does not affect positive mood in healthy human volunteers. PLoS One 2012; 7:e28370. [PMID: 22238577 PMCID: PMC3251561 DOI: 10.1371/journal.pone.0028370] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 11/07/2011] [Indexed: 11/25/2022] Open
Abstract
Dopamine neurotransmission influences approach toward rewards and reward-related cues. The best cited interpretation of this effect proposes that dopamine mediates the pleasure that commonly accompanies reward. This hypothesis has received support in some animal models and a few studies in humans. However, direct assessments of the effect of transiently increasing dopamine neurotransmission have been largely limited to the use of psychostimulant drugs, which elevate brain levels of multiple neurotransmitters in addition to dopamine. In the present study we tested the effect of more selectively elevating dopamine neurotransmission, as produced by administration of the immediate dopamine precursor, L-DOPA (0, 100/25, 200/50 mg, Sinemet), in healthy human volunteers. Neither dose altered positive mood. The results suggest that dopamine neurotransmission does not directly influence positive mood in humans.
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Affiliation(s)
- John Liggins
- Department of Psychiatry, McGill University, Montréal, Québec, Canada
| | - Robert O. Pihl
- Department of Psychiatry, McGill University, Montréal, Québec, Canada
| | - Chawki Benkelfat
- Department of Psychiatry, McGill University, Montréal, Québec, Canada
| | - Marco Leyton
- Department of Psychiatry, McGill University, Montréal, Québec, Canada
- * E-mail:
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Venugopalan VV, Casey KF, O'Hara C, O'Loughlin J, Benkelfat C, Fellows LK, Leyton M. Acute phenylalanine/tyrosine depletion reduces motivation to smoke cigarettes across stages of addiction. Neuropsychopharmacology 2011; 36:2469-76. [PMID: 21775977 PMCID: PMC3194074 DOI: 10.1038/npp.2011.135] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The neurobiology of tobacco use is poorly understood, possibly in part because the relevant mechanisms might differ depending on past nicotine exposure and degree of addiction. In the present study we investigated whether these factors might affect the role of dopamine (DA). Using the acute phenylalanine/tyrosine depletion method (APTD), DA synthesis was transiently decreased in three groups of abstinent smokers (n=47): (1) early low-frequency smokers, who had smoked a maximum of five cigarettes per day for less than one year, (2) stable low-frequency smokers smoking at the same level as early low-frequency smokers for at least 3 years, and (3) stable high-frequency smokers, who smoked a minimum of 10 or more cigarettes per day for at least 5 years. Motivation to obtain tobacco was measured using a progressive ratio breakpoint schedule for nicotine-containing and de-nicotinized cigarettes. Compared with a nutritionally balanced control mixture, APTD decreased the self-administration of nicotine-containing cigarettes, and this occurred in all three groups of smokers. The results suggest that DA influenced the willingness to sustain effort for nicotine reward, and this was seen in participants at all three levels of cigarette addiction. In the transition from sporadic to addicted use, the role of DA in the motivation to seek drug may change less than previously proposed.
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Vasconcelos SMM, Sales GTM, Lima NM, Soares PM, Pereira EC, Fonteles MMF, Sousa FCFD, Viana GSDB. Determination of amino acid levels in the rat striatum, after administration of ethanol alone and associated with ketamine, a glutamatergic antagonist. Neurosci Lett 2008; 444:48-51. [PMID: 18706482 DOI: 10.1016/j.neulet.2008.08.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 08/03/2008] [Accepted: 08/04/2008] [Indexed: 10/21/2022]
Abstract
The main goal of this study was to determine the amino acids (glutamate, aspartate, glutamine and tyrosine) levels in the rat striatum, after ethanol administration alone and/or associated with ketamine. In protocol 1 (Et+ketamine-1), ethanol was administered to male Wistar rats until the 7th day, and at the next day the group received only ketamine (25mg/kg, i.p.) up to the 14th day. In protocol 2 (Et+ketamine-2), ethanol was also administered up to the 7th day, and was associated with ketamine from the 8th up to the 14th day. In other groups, animals were treated daily with ethanol (4 g/kg, p.o.), for 7 or 14 days or ketamine daily for 7 days. Controls were administered with distilled water for 7 days. Results showed that, in protocol 1, aspartate (ASP) levels increased after ketamine administration, as compared to the controls. This effect was inhibited in the group Et+ketamine-1. Ethanol (7 days) increased glutamate (GLU) levels, as compared to control, and this effect did not differ significantly from that observed in the ketamine group. When ketamine was administered after the ethanol withdrawal (protocol 1), no alterations in those amino acid concentrations were seen, as compared to the control and ketamine groups. A tendency for increasing GLU levels was observed, after administration of ethanol (14 days) or ketamine alone or associated (protocol 2), when compared to control values. In protocol 2, TYR levels decreased as related to controls and to the 14-day ethanol-treated group. We can assume that ketamine presents only an antagonist effect, in animals pretreated with ethanol, followed by ketamine administered from the 8th day on. This is due to the fact that NMDA receptors are already sensitized, leading to a decrease in these receptors functions and consequently to ASP and GLU releases.
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Affiliation(s)
- Silvânia Maria Mendes Vasconcelos
- Department of Physiology and Pharmacology, Federal University of Ceará, Rua Cel. Nunes de Melo 1127, CEP 60431-270, Fortaleza, Brazil.
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Barrett SP, Pihl RO, Benkelfat C, Brunelle C, Young SN, Leyton M. The role of dopamine in alcohol self-administration in humans: individual differences. Eur Neuropsychopharmacol 2008; 18:439-47. [PMID: 18367384 DOI: 10.1016/j.euroneuro.2008.01.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Revised: 01/08/2008] [Accepted: 01/22/2008] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To clarify dopamine's role in alcohol self-administration in a heterogeneous sample of drinkers using acute phenylalanine/tyrosine depletion (APTD). METHODS Sixteen men with variable drinking histories were characterized on their ethanol-induced cardiac response, a marker previously proposed to index dopamine system reactivity and vulnerability to alcohol abuse. During separate sessions participants were administered (i) a nutritionally balanced (BAL) amino acid (AA) mixture, (ii) a mixture lacking the dopamine precursors, phenylalanine and tyrosine, and (iii) APTD followed by the dopamine precursor, L-DOPA. Five hours after AA administration, participants could earn units of alcohol using a progressive ratio breakpoint task. RESULTS Alcohol self-administration was reduced in the APTD and APTD+L-DOPA conditions relative to the BAL condition. In both cases the changes were predicted by ethanol-induced cardiac change. CONCLUSIONS The motivation to drink is likely regulated by more than one neurobiological mechanism. Individual differences in cardiac responsivity to ethanol might provide a peripheral marker of responsiveness to pharmacological manipulations of dopamine.
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Affiliation(s)
- Sean P Barrett
- Psychology Department, McGill University, 1033 Pine Avenue West, Montreal, Quebec, Canada
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15
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Ellis KA, Mehta MA, Naga Venkatesha Murthy P, McTavish SF, Nathan PJ, Grasby PM. Tyrosine depletion alters cortical and limbic blood flow but does not modulate spatial working memory performance or task-related blood flow in humans. Hum Brain Mapp 2008; 28:1136-49. [PMID: 17290373 PMCID: PMC6871381 DOI: 10.1002/hbm.20339] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dopamine appears critical in regulating spatial working memory (SWM) within the PFC of non-human primates; however findings in humans are less clear. Recent studies of the effects of global depletion of dopamine via acute tyrosine/phenylalanine depletion (TPD) on SWM task performance have yielded inconsistent results, which may be partly related to task differences. These previous studies do not address whether TPD can directly impair PFC functioning. The current study investigated the effects of TPD on (1) regional cerebral blood flow (rCBF) during a SWM n-back task using H(2) (15)O Positron Emission Tomography (PET), and (2) behavioural performance on three different SWM tasks. Ten healthy males were scanned twice: once following a placebo (balanced) amino acid mixture and once following an equivalent mixture deficient in tyrosine/phenylalanine (TPD condition). Participants completed two additional delayed-response tasks to examine whether differences in response demands influenced TPD effects on performance. TPD resulted in widespread increases in rCBF, with maximum increases in the region of the parahippocampal gyrus bilaterally, left inferior frontal gyrus, and the putamen. TPD related rCBF reductions were observed in the medial frontal gyrus bilaterally, right inferior temporal gyrus and the pons. Despite widespread changes in blood flow following TPD, no specific effects on SWM neural networks or task performance were observed. The use of three different SWM tasks suggests that task differences are unlikely to account for the lack of effects observed. These findings question the capacity of TPD to consistently modulate dopamine function and SWM neural networks in humans.
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Affiliation(s)
- Kathryn A. Ellis
- Brain Sciences Institute, Swinburne University of Technology, Melbourne, Australia
- Academic Unit for Psychiatry of Old Age, Department of Psychiatry, University of Melbourne, Melbourne, Australia
| | - Mitul A. Mehta
- PET Psychiatry, Medical Research Council Clinical Sciences Centre (of the Faculty of Medicine, Imperial College London), Hammersmith Hospital, London, United Kingdom
- Division of Neuroscience and Psychological Medicine (of the Faculty of Medicine, Imperial College London), Hammersmith Hospital, London, United Kingdom
- Centre for Neuroimaging Sciences, Institute of Psychiatry, King's College, London, United Kingdom
| | - P.J. Naga Venkatesha Murthy
- PET Psychiatry, Medical Research Council Clinical Sciences Centre (of the Faculty of Medicine, Imperial College London), Hammersmith Hospital, London, United Kingdom
- Division of Neuroscience and Psychological Medicine (of the Faculty of Medicine, Imperial College London), Hammersmith Hospital, London, United Kingdom
| | - Sarah F.B. McTavish
- Department of Psychiatry (of the University of Oxford), Warneford Hospital, Oxford, United Kingdom
| | - Pradeep J. Nathan
- School of Psychology, Psychiatry and Psychological Medicine (SPPPM), Monash University, Melbourne, Australia
| | - Paul M. Grasby
- PET Psychiatry, Medical Research Council Clinical Sciences Centre (of the Faculty of Medicine, Imperial College London), Hammersmith Hospital, London, United Kingdom
- Division of Neuroscience and Psychological Medicine (of the Faculty of Medicine, Imperial College London), Hammersmith Hospital, London, United Kingdom
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Abstract
In animal models considerable evidence suggests that increased motivation to seek and ingest drugs of abuse are related to conditioned and sensitized activations of the mesolimbic dopamine (DA) system. Direct evidence for these phenomena in humans, though, is sparse. However, recent studies support the following. First, the acute administration of drugs of abuse across pharmacological classes increases extracellular DA levels within the human ventral striatum. Second, individual differences in the magnitude of this response correlate with rewarding effects of the drugs and the personality trait of novelty seeking. Third, transiently diminishing DA transmission in humans decreases drug craving, the propensity to preferentially respond to reward-paired stimuli, and the ability to sustain responding for future drug reward. Finally, very recent studies suggest that repeated exposure to stimulant drugs, either on the street or in the laboratory, can lead to conditioned and sensitized behavioral responses and DA release. In contrast to these findings, though, in individuals with a long history of substance abuse, drug-induced DA release is decreased. This diminished DA release could reflect two different phenomena. First, it is possible that drug withdrawal related decrements in DA cell function persist longer than previously suspected. Second, drug-paired stimuli may gain marked conditioned control over the release of DA and the expression of sensitization leading to reduced DA release when drug-related cues are absent. Based on these observations a two-factor hypothesis of the role of DA in drug abuse is proposed. In the presence of drug cues, conditioned and sensitized DA release would occur leading to focused drug-seeking behavior. In comparison, in the absence of drug-related stimuli DA function would be reduced, diminishing the ability of individuals to sustain goal-directed behavior and long-term objectives. This conditioned control of the expression of sensitized DA release could aggravate susceptibility to relapse, narrow the range of interests and perturb decision-making, accounting for a wide range of addiction related phenomena.
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Affiliation(s)
- Marco Leyton
- Department of Psychiatry, McGill University, 1033 Pine Avenue West, Montreal, Quebec, CANADA H3A 1A1.
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17
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Munafò MR, Mannie ZN, Cowen PJ, Harmer CJ, McTavish SB. Effects of acute tyrosine depletion on subjective craving and selective processing of smoking-related cues in abstinent cigarette smokers. J Psychopharmacol 2007; 21:805-14. [PMID: 17715209 DOI: 10.1177/0269881107077216] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We investigated the impact of the administration of a tyrosine-depleting amino acid mixture compared to a balanced mixture on measures of mood, craving and selective processing of smoking-related cues in healthy cigarette smokers instructed to abstain from smoking for 12 h prior to, and during, the experiment. A modified stroop task was used to index selective processing of smoking-related cues. We observed evidence for an increase in subjective craving among males, and an attenuation of the selective processing of smoking-related cues compared to control cues among females, in the tyrosine-depleting condition compared to the balanced condition. No effects of mixture were observed on measures of subjective mood. These results tentatively support for the role of dopaminergic neurotransmission in mediating the response of cigarette smokers to smoking-related cues. In addition, these results also provide further evidence for sex differences in the factors that maintain cigarette smoking, in particular with respect to conditioned reinforcement of smoking behaviour, and suggest that the relationship between subjective craving and selective processing of smoking-related cues may differ in males and females.
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Affiliation(s)
- Marcus R Munafò
- Department of Experimental Psychology, University of Bristol, Bristol, UK.
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18
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Casey KF, Benkelfat C, Young SN, Leyton M. Lack of effect of acute dopamine precursor depletion in nicotine-dependent smokers. Eur Neuropsychopharmacol 2006; 16:512-20. [PMID: 16545549 DOI: 10.1016/j.euroneuro.2006.02.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Revised: 01/26/2006] [Accepted: 02/02/2006] [Indexed: 11/18/2022]
Abstract
RATIONALE Nicotine increases dopamine (DA) release but its role in nicotine dependence remains unclear. OBJECTIVE To assess the role of DA in nicotine craving and self-administration using acute phenylalanine/tyrosine depletion (APTD). METHODS Fifteen nicotine-dependent men ingested, a minimum of 3days apart, a nutritionally balanced amino acid (AA) mixture (BAL), a mixture deficient in the catecholamine precursors, phenylalanine and tyrosine, and APTD followed by the immediate DA precursor, L-DOPA. Beginning 3h after ingestion of the AA mixture, subjects smoked 4 cigarettes. Craving, mood, and other aspects of subjective state were assessed with self-report scales. Smoking puff topography was measured with a computerized flowmeter. RESULTS APTD did not change smoking puff topography, cigarette craving, or subjective effects of smoking. CONCLUSIONS The findings suggest that in nicotine-dependent smokers craving for cigarettes, subjective effects of nicotine, and the self-administration of freely available cigarettes are largely unrelated to acute changes in DA neurotransmission.
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Affiliation(s)
- Kevin F Casey
- Department of Psychiatry, McGill University, 1033 Pine Avenue West, Montreal, Quebec, Canada H3A 1A1
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19
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Leyton M, Casey KF, Delaney JS, Kolivakis T, Benkelfat C. Cocaine craving, euphoria, and self-administration: a preliminary study of the effect of catecholamine precursor depletion. Behav Neurosci 2006; 119:1619-27. [PMID: 16420164 DOI: 10.1037/0735-7044.119.6.1619] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The authors used the acute phenylalanine-tyrosine depletion (APTD) method to test the effect of transient catecholamine precursor depletion on cocaine craving, euphoria, and self-administration. Eight nondependent, nontreatment-seeking cocaine users self-administered 3 doses of cocaine (0.6, 1.5, 3.0 mg/kg, taken intranasally) following ingestion of (a) a nutritionally balanced amino acid mixture, (b) APTD, and (c) APTD followed by L-dopa/carbidopa (2x100 mg/25 mg). APTD decreased both cue and cocaine-induced drug craving but not euphoria or self-administration. APTD+L-dopa also decreased drug craving, possibly reflecting the ability of L-dopa to transiently decrease dopamine cell firing. Together, these preliminary results suggest that the craving elicited by cocaine and cocaine cues is related to changes in catecholamine neurotransmission. Euphoria and the self-administration of freely available drugs by regular users, in comparison, might be better accounted for by other mechanisms.
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Affiliation(s)
- Marco Leyton
- McGill University, Department of Psychiatry, Montreal, PQ, Canada.
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20
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Leyton M, Dagher A, Boileau I, Casey K, Baker GB, Diksic M, Gunn R, Young SN, Benkelfat C. Decreasing amphetamine-induced dopamine release by acute phenylalanine/tyrosine depletion: A PET/[11C]raclopride study in healthy men. Neuropsychopharmacology 2004; 29:427-32. [PMID: 14583741 DOI: 10.1038/sj.npp.1300328] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Acute phenylalanine/tyrosine depletion (APTD) has been proposed as a new method to decrease catecholamine neurotransmission safely, rapidly, and transiently. Validation studies in animals are encouraging, but direct evidence in human brain is lacking. In the present study, we tested the hypothesis that APTD would reduce stimulated dopamine (DA) release, as assessed by positron emission tomography (PET) and changes in [(11)C]raclopride binding potential (BP), a measure of DA D2/D3 receptor availability. Eight healthy men received two PET scans, both following d-amphetamine, 0.3 mg/kg, p.o., an oral dose known to decrease [(11)C]raclopride BP in ventral striatum. On the morning before each scan, subjects ingested, in counter-balanced order, an amino-acid mixture deficient in the catecholamine precursors, phenylalanine, and tyrosine, or a nutritionally balanced mixture. Brain parametric images were generated by calculating [(11)C]raclopride BP at each voxel. BP values were extracted from the t-map (threshold: t=4.2, equivalent to p<0.05, Bonferroni corrected) and a priori identified regions of interest from each individual's coregistered magnetic resonance images. Both receptor parametric mapping and region of interest analyses indicated that [(11)C]raclopride binding was significantly different on the two test days in the ventral striatum (peak t=6.31; x=-25, y=-8, and z=0.1). In the t-map defined cluster, [(11)C]raclopride BP values were 11.8+/-11.9% higher during the APTD session (p<0.05). The reduction in d-amphetamine-induced DA release exhibited a linear association with the reduction in plasma tyrosine levels (r=-0.82, p<0.05). Together, the results provide the first direct evidence that APTD decreases stimulated DA release in human brain. APTD may be a suitable new tool for human neuropsychopharmacology research.
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Affiliation(s)
- Marco Leyton
- Department of Psychiatry, McGill University, Montréal, Québec, Canada.
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21
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Abstract
A number of techniques temporarily lower the functioning of monoamines: acute tryptophan depletion (ATD), alpha-methyl-para-tyrosine (AMPT) and acute phenylalanine/tyrosine depletion (APTD). This paper reviews the results of monoamine depletion studies in humans for the period 1966 until December 2002. The evidence suggests that all three interventions are specific, in terms of their short-term effects on one or two neurotransmitter systems, rather than on brain protein metabolism in general. The AMPT procedure is somewhat less specific, affecting both the dopamine and norepinephrine systems. The behavioral effects of ATD and AMPT are remarkably similar. Neither procedure has an immediate effect on the symptoms of depressed patients; however, both induce transient depressive symptoms in some remitted depressed patients. The magnitude of the effects, response rate and quality of response are also comparable. APTD has not been studied in recovered major depressive patients. Despite the similarities, the effects are distinctive in that ATD affects a subgroup of recently remitted patients treated with serotonergic medications, whereas AMPT affects recently remitted patients treated with noradrenergic medications. The evidence also suggests that ATD and APTD affect different cognitive functions, in particular different memory systems. Few studies investigated cognitive effects of the procedures in patients. Patients who are in remission for longer may also be vulnerable to ATD and AMPT, but the relationship with prior treatment is much weaker. For these patients, individual vulnerability markers are the more important determinants of depressive response, making these techniques potentially useful models of vulnerability to depression.
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Affiliation(s)
- L Booij
- Department of Psychology, Leiden University, Leiden 2333 AK, The Netherlands.
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22
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Young SN, Leyton M. The role of serotonin in human mood and social interaction. Insight from altered tryptophan levels. Pharmacol Biochem Behav 2002; 71:857-65. [PMID: 11888576 DOI: 10.1016/s0091-3057(01)00670-0] [Citation(s) in RCA: 230] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Alterations in brain tryptophan levels cause changes in brain serotonin synthesis, and this has been used to study the implication of altered serotonin levels in humans. In the acute tryptophan depletion (ATD) technique, subjects ingest a mixture of amino acids devoid of tryptophan. This results in a transient decline in tissue tryptophan and in brain serotonin. ATD can result in lower mood and increase in irritability or aggressive responding. The magnitude of the effect varies greatly depending on the susceptibility of the subject to lowered mood or aggressivity. Unlike ATD, tryptophan can be given chronically. Tryptophan is an antidepressant in mild to moderate depression and a small body of data suggests that it can also decrease aggression. Preliminary data indicate that tryptophan also increases dominant behavior during social interactions. Overall, studies manipulating tryptophan levels support the idea that low serotonin can predispose subjects to mood and impulse control disorders. Higher levels of serotonin may help to promote more constructive social interactions by decreasing aggression and increasing dominance.
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Affiliation(s)
- Simon N Young
- Department of Psychiatry, McGill University, 1033 Pine Avenue West, H3A 1A1, Montréal, Québec, Canada.
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Grevet EH, Tietzmann MR, Shansis FM, Hastenpflugl C, Santana LC, Forster L, Kapczinskil F, Izquierdo I. Behavioural effects of acute phenylalanine and tyrosine depletion in healthy male volunteers. J Psychopharmacol 2002; 16:51-5. [PMID: 11949772 DOI: 10.1177/026988110201600103] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Acute phenylalanine and tyrosine depletion (APTD) studies have been used to assess the role of the cathecholaminergic system in various aspects of human behaviour. In this study we conducted a randomized, double-blind, controlled and cross-over comparison to evaluate the effects of APTD on memory, attention and mood in normal subjects. Twelve healthy male volunteers were included in this study. The subjects ingested a nutritionally balanced mixture (B) or a similar mixture deficient in phenylalanine and tyrosine (PT-). Before and 5 h after ingestion of the drink, volunteers underwent tests on mood, memory and attention. Results of the memory tests showed that PT- mixture impaired word recall as measured in Rey's test (p = 0.016). The assessment of changes in mood showed that the balanced mixture improved scores of as alertness (VAMS factor I, p = 0.037) and the PT- mixture induces an opposite effect, increased scores of anxiety (Profiles of Mental State composed-anxious dimension, p = 0.022). These results suggest that tyrosine plasma levels and cathecholamines may be important factors in regulating mood and memory.
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Affiliation(s)
- Eugenio H Grevet
- Departamento de Psiquiatria, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul e Hospital de Clinicas de Porto Alegre, Brazil.
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