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Markova TZ, Ciampa CJ, Parent JH, LaPoint MR, D'Esposito M, Jagust WJ, Berry AS. Poorer aging trajectories are associated with elevated serotonin synthesis capacity. Mol Psychiatry 2023; 28:4390-4398. [PMID: 37460847 PMCID: PMC10792105 DOI: 10.1038/s41380-023-02177-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 06/28/2023] [Accepted: 06/30/2023] [Indexed: 01/18/2024]
Abstract
The dorsal raphe nucleus (DRN) is one of the earliest targets of Alzheimer's disease-related tau pathology and is a major source of brain serotonin. We used [18F]Fluoro-m-tyrosine ([18F]FMT) PET imaging to measure serotonin synthesis capacity in the DRN in 111 healthy adults (18-85 years-old). Similar to reports in catecholamine systems, we found elevated serotonin synthesis capacity in older adults relative to young. To establish the structural and functional context within which serotonin synthesis capacity is elevated in aging, we examined relationships among DRN [18F]FMT net tracer influx (Ki) and longitudinal changes in cortical thickness using magnetic resonance imaging, longitudinal changes in self-reported depression symptoms, and AD-related tau and β-amyloid (Aβ) pathology using cross-sectional [18F]Flortaucipir and [11C]Pittsburgh compound-B PET respectively. Together, our findings point to elevated DRN [18F]FMT Ki as a marker of poorer aging trajectories. Older adults with highest serotonin synthesis capacity showed greatest temporal lobe cortical atrophy. Cortical atrophy was associated with increasing depression symptoms over time, and these effects appeared to be strongest in individuals with highest serotonin synthesis capacity. We did not find direct relationships between serotonin synthesis capacity and AD-related pathology. Exploratory analyses revealed nuanced effects of sex within the older adult group. Older adult females showed the highest DRN synthesis capacity and exhibited the strongest relationships between entorhinal cortex tau pathology and increasing depression symptoms. Together these findings reveal PET measurement of the serotonin system to be a promising marker of aging trajectories relevant to both AD and affective changes in older age.
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Affiliation(s)
| | | | | | - Molly R LaPoint
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Mark D'Esposito
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
| | - William J Jagust
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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2
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Trace amine-associated receptor 1 (TAAR1): Potential application in mood disorders: A systematic review. Neurosci Biobehav Rev 2021; 131:192-210. [PMID: 34537265 DOI: 10.1016/j.neubiorev.2021.09.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 09/07/2021] [Accepted: 09/12/2021] [Indexed: 12/29/2022]
Abstract
There is a need for innovation with respect to therapeutics in psychiatry. Available evidence indicates that the trace amine-associated receptor 1 (TAAR1) agonist SEP-363856 is promising, as it improves measures of cognitive and reward function in schizophrenia. Hedonic and cognitive impairments are transdiagnostic and constitute major burdens in mood disorders. Herein, we systematically review the behavioural and genetic literature documenting the role of TAAR1 in reward and cognitive function, and propose a mechanistic model of TAAR1's functions in the brain. Notably, TAAR1 activity confers antidepressant-like effects, enhances attention and response inhibition, and reduces compulsive reward seeking without impairing normal function. Further characterization of the responsible mechanisms suggests ion-homeostatic, metabolic, neurotrophic, and anti-inflammatory enhancements in the limbic system. Multiple lines of evidence establish the viability of TAAR1 as a biological target for the treatment of mood disorders. Furthermore, the evidence suggests a role for TAAR1 in reward and cognitive function, which is attributed to a cascade of events that are relevant to the cellular integrity and function of the central nervous system.
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Wang K, Ren Q, Shen XL, Li B, Du J, Yu XD, Du ZQ. Molecular characterization and expression analysis of dopa decarboxylase involved in the antibacterial innate immunity of the freshwater crayfish, Procambarus clarkii. FISH & SHELLFISH IMMUNOLOGY 2019; 91:19-28. [PMID: 31077848 DOI: 10.1016/j.fsi.2019.05.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/27/2019] [Accepted: 05/07/2019] [Indexed: 06/09/2023]
Abstract
Dopa decarboxylase (DDC) is responsible for the synthesis of dopamine, which acts as an important modulator in the nervous systems of vertebrates and invertebrates. Recent studies have indicated that DDC also plays crucial roles in the insect innate immune system. However, the functions of DDC in immunomodulation in crustaceans have not been thoroughly elucidated to date. In this study, a new full-length cDNA of the DDC protein was identified from red swamp crayfish, Procambarus clarkii (named Pc-ddc). The ORF of Pc-ddc encoded 474 amino acids, which possessed a 377-amino-acid domain. Pc-ddc was expressed at a relatively high level in the hemocytes and gills of crayfish. This protein was expressed at a relatively low level in the hepatopancreas and intestine. The expression level of Pc-ddc was clearly upregulated in hemocytes, hepatopancreas, gills, and intestine tissues after challenge with S. aureus or E. ictaluri. The results of the enzyme catalysis assay showed that the enzyme catalysis activity of rPc-DDC was 35 ± 2.8 ng h-1 mg-1 (n = 3). In addition, the results of the mimetic crayfish hemocytes encapsulation assay showed that the encapsulation rate of beads coated with rPc-DDC was clearly increased. The results of the bacterial binding assay showed that rPc-DDC strongly binds to S. aureus and E. ictaluri. Finally, when Pc-ddc was knocked down, the number of surviving crayfish clearly decreased after S. aureus or E. ictaluri was injected. All of these results indicate that Pc-DDC is an important immunomodulating enzyme in the neuroendocrine-immune (NEI) system of crayfish.
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Affiliation(s)
- Kai Wang
- School of Life Science and Technology, Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia Autonomous Region, 014010, China
| | - Qian Ren
- Co-Innovation Center for Marine Bio-Industry Technology of Jiangsu Province, Lianyungang, 222005, China; College of Marine Science and Engineering, Nanjing Normal University, Nanjing, 210046, China
| | - Xiu-Li Shen
- Library, Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia Autonomous Region, 014010, China
| | - Bo Li
- School of Life Science and Technology, Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia Autonomous Region, 014010, China
| | - Jie Du
- School of Life Science and Technology, Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia Autonomous Region, 014010, China
| | - Xiao-Dong Yu
- School of Life Science and Technology, Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia Autonomous Region, 014010, China
| | - Zhi-Qiang Du
- School of Life Science and Technology, Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia Autonomous Region, 014010, China.
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Abstract
Trace amines are endogenous compounds classically regarded as comprising β-phenylethyalmine, p-tyramine, tryptamine, p-octopamine, and some of their metabolites. They are also abundant in common foodstuffs and can be produced and degraded by the constitutive microbiota. The ability to use trace amines has arisen at least twice during evolution, with distinct receptor families present in invertebrates and vertebrates. The term "trace amine" was coined to reflect the low tissue levels in mammals; however, invertebrates have relatively high levels where they function like mammalian adrenergic systems, involved in "fight-or-flight" responses. Vertebrates express a family of receptors termed trace amine-associated receptors (TAARs). Humans possess six functional isoforms (TAAR1, TAAR2, TAAR5, TAAR6, TAAR8, and TAAR9), whereas some fish species express over 100. With the exception of TAAR1, TAARs are expressed in olfactory epithelium neurons, where they detect diverse ethological signals including predators, spoiled food, migratory cues, and pheromones. Outside the olfactory system, TAAR1 is the most thoroughly studied and has both central and peripheral roles. In the brain, TAAR1 acts as a rheostat of dopaminergic, glutamatergic, and serotonergic neurotransmission and has been identified as a novel therapeutic target for schizophrenia, depression, and addiction. In the periphery, TAAR1 regulates nutrient-induced hormone secretion, suggesting its potential as a novel therapeutic target for diabetes and obesity. TAAR1 may also regulate immune responses by regulating leukocyte differentiation and activation. This article provides a comprehensive review of the current state of knowledge of the evolution, physiologic functions, pharmacology, molecular mechanisms, and therapeutic potential of trace amines and their receptors in vertebrates and invertebrates.
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Affiliation(s)
- Raul R Gainetdinov
- Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia (R.R.G.); Skolkovo Institute of Science and Technology (Skoltech), Moscow, Russia (R.R.G.); Neuroscience, Ophthalmology, and Rare Diseases Discovery and Translational Area, pRED, Roche Innovation Centre Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland (M.C.H.); and Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada (M.D.B.)
| | - Marius C Hoener
- Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia (R.R.G.); Skolkovo Institute of Science and Technology (Skoltech), Moscow, Russia (R.R.G.); Neuroscience, Ophthalmology, and Rare Diseases Discovery and Translational Area, pRED, Roche Innovation Centre Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland (M.C.H.); and Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada (M.D.B.)
| | - Mark D Berry
- Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia (R.R.G.); Skolkovo Institute of Science and Technology (Skoltech), Moscow, Russia (R.R.G.); Neuroscience, Ophthalmology, and Rare Diseases Discovery and Translational Area, pRED, Roche Innovation Centre Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland (M.C.H.); and Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada (M.D.B.)
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Johnson M, Salvatore M, Maiolo S, Bobrovskaya L. Tyrosine hydroxylase as a sentinel for central and peripheral tissue responses in Parkinson’s progression: Evidence from clinical studies and neurotoxin models. Prog Neurobiol 2018; 165-167:1-25. [DOI: 10.1016/j.pneurobio.2018.01.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 12/07/2017] [Accepted: 01/10/2018] [Indexed: 12/25/2022]
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Brodnik ZD, Double M, España RA, Jaskiw GE. L-Tyrosine availability affects basal and stimulated catecholamine indices in prefrontal cortex and striatum of the rat. Neuropharmacology 2017; 123:159-174. [PMID: 28571714 DOI: 10.1016/j.neuropharm.2017.05.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/22/2017] [Accepted: 05/26/2017] [Indexed: 12/15/2022]
Abstract
We previously found that L-tyrosine (L-TYR) but not D-TYR administered by reverse dialysis elevated catecholamine synthesis in vivo in medial prefrontal cortex (MPFC) and striatum of the rat (Brodnik et al., 2012). We now report L-TYR effects on extracellular levels of catecholamines and their metabolites. In MPFC, reverse dialysis of L-TYR elevated in vivo levels of dihydroxyphenylacetic acid (DOPAC) (L-TYR 250-1000 μM), homovanillic acid (HVA) (L-TYR 1000 μM) and 3-methoxy-4-hydroxyphenylglycol (MHPG) (L-TYR 500-1000 μM). In striatum L-TYR 250 μM elevated DOPAC. We also examined L-TYR effects on extracellular dopamine (DA) and norepinephrine (NE) levels during two 30 min pulses (P2 and P1) of K+ (37.5 mM) separated by t = 2.0 h. L-TYR significantly elevated the ratio P2/P1 for DA (L-TYR 125 μM) and NE (L-TYR 125-250 μM) in MPFC but lowered P2/P1 for DA (L-TYR 250 μM) in striatum. Finally, we measured DA levels in brain slices using ex-vivo voltammetry. Perfusion with L-TYR (12.5-50 μM) dose-dependently elevated stimulated DA levels in striatum. In all the above studies, D-TYR had no effect. We conclude that acute increases within the physiological range of L-TYR levels can increase catecholamine metabolism and efflux in MPFC and striatum. Chronically, such repeated increases in L-TYR availability could induce adaptive changes in catecholamine transmission while amplifying the metabolic cost of catecholamine synthesis and degradation. This has implications for neuropsychiatric conditions in which neurotoxicity and/or disordered L-TYR transport have been implicated.
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Affiliation(s)
- Zachary D Brodnik
- Drexel University College of Medicine, Department of Neurobiology and Anatomy, 2900 W. Queen Lane, Philadelphia, PA 19129, United States
| | - Manda Double
- Medical Research Service, Louis Stokes Cleveland DVAMC, 10701 East Blvd., Cleveland, OH 44106, United States
| | - Rodrigo A España
- Drexel University College of Medicine, Department of Neurobiology and Anatomy, 2900 W. Queen Lane, Philadelphia, PA 19129, United States
| | - George E Jaskiw
- Medical Research Service, Louis Stokes Cleveland DVAMC, 10701 East Blvd., Cleveland, OH 44106, United States; Dept. of Psychiatry, Case Western University Medical Center at W.O. Walker 10524 Euclid Ave, Cleveland, OH 44133, United States.
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Kim E, Howes OD, Veronese M, Beck K, Seo S, Park JW, Lee JS, Lee YS, Kwon JS. Presynaptic Dopamine Capacity in Patients with Treatment-Resistant Schizophrenia Taking Clozapine: An [ 18F]DOPA PET Study. Neuropsychopharmacology 2017; 42:941-950. [PMID: 27857125 PMCID: PMC5312074 DOI: 10.1038/npp.2016.258] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Revised: 11/09/2016] [Accepted: 11/11/2016] [Indexed: 01/20/2023]
Abstract
Some patients with schizophrenia show poor response to first-line antipsychotic treatments and this is termed treatment-resistant schizophrenia. The differential response to first-line antipsychotic drugs may reflect a different underlying neurobiology. Indeed, a previous study found dopamine synthesis capacity was significantly lower in patients with treatment-resistant schizophrenia. However, in this study, the treatment-resistant patients were highly symptomatic, whereas the responsive patients showed no or minimal symptoms. The study could not distinguish whether this was a trait effect or reflected the difference in symptom levels. Thus, we aimed to test whether dopaminergic function is altered in patients with a history of treatment resistance to first-line drugs relative to treatment responders when both groups are matched for symptom severity levels by recruiting treatment-resistant patients currently showed low symptom severity with the clozapine treatment. Healthy controls (n=12), patients treated with clozapine (n=12) who had not responded to first-line antipsychotics, and patients who had responded to first-line antipsychotics (n=12) were recruited. Participants were matched for age and sex and symptomatic severity level in patient groups. Participants' dopamine synthesis capacity was measured by using [18F]DOPA PET. We found that patients treated with clozapine show lower dopamine synthesis capacity than patients who have responded to first-line treatment (Cohen's d=0.9191 (whole striatum), 0.7781 (associative striatum), 1.0344 (limbic striatum), and 1.0189 (sensorimotor striatum) in line with the hypothesis that the dopaminergic function is linked to treatment response. This suggests that a different neurobiology may underlie treatment-resistant schizophrenia and that dopamine synthesis capacity may be a useful biomarker to predict treatment responsiveness.
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Affiliation(s)
- Euitae Kim
- Department of Neuropsychiatry, Seoul National University Bundang Hospital, Gyeonggi-do, Korea
| | - Oliver D Howes
- Psychiatric Imaging, Medical Research Council Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, London, UK,Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Mattia Veronese
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Katherine Beck
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Seongho Seo
- Department of Brain & Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Korea,Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Jin Woo Park
- Department of Psychiatry, Seoul National University College of Medicine, Seoul, Korea
| | - Jae Sung Lee
- Department of Brain & Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Korea,Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Yun-Sang Lee
- Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Jun Soo Kwon
- Department of Brain & Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Korea,Department of Psychiatry, Seoul National University College of Medicine, Seoul, Korea,Department of Psychiatry, Seoul National University College of Medicine and Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, 28 Yeongon-dong, Chongno-gu, Seoul 110-744, Korea, Tel: +82 2 2072 2972, Fax: +82 2 747 9063, E-mail:
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Li J, Meltzer HY. A genetic locus in 7p12.2 associated with treatment resistant schizophrenia. Schizophr Res 2014; 159:333-9. [PMID: 25223841 DOI: 10.1016/j.schres.2014.08.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 08/20/2014] [Accepted: 08/23/2014] [Indexed: 11/29/2022]
Abstract
Approximately 30% of patients with schizophrenia are treatment resistant (TRS), i.e. have persistent psychotic symptoms despite adequate trials of at least two antipsychotic drugs (APDs). Most TRS patients are candidates for clozapine treatment which is underutilized because of its side effects and difficulty in identifying TRS. We conducted a genome-wide association study (GWAS) of 79 TRS and 95 non-treatment resistant (NTRS) Caucasian schizophrenia patients to identify possible biomarkers for TRS, which might also provide insight into the pathobiology of TRS. The single nucleotide polymorphism, rs2237457, located in 7p12.2, a region reported to have imprinted inheritance, was found to have the lowest p value in an allelic association test (unadjusted p = 5.53 × 10(-6)). Haploview disclosed a 30 kb block flanking this SNP within GRB10, 70 kb upstream of l-dopa decarboxylase (DDC), an enzyme which is rate-limiting in the synthesis of trace amines and neurotransmitters implicated in schizophrenia and the action of APDs. This SNP or haplotype was identified as an exclusive cis-acting eQTL for DDC in human dorsolateral prefrontal cortex by BrainCloud®. A replication sample genotyped for this SNP produced a weaker result, but in the same direction. After combining the two samples, rs2237457 remained significantly associated with TRS (unadjusted p = 5.66 × 10(-7) in recessive mode; 9.42 × 10(-5) in allelic association). If replicated in an independent sample, rs2237457 may provide a biomarker to identify a significant proportion of Caucasian TRS. The results implicate trace amines and their synthesis in the pathophysiology of TRS.
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Affiliation(s)
- Jiang Li
- Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, United States
| | - Herbert Y Meltzer
- Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, United States.
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Presynaptic regulation of extracellular dopamine levels in the medial prefrontal cortex and striatum during tyrosine depletion. Psychopharmacology (Berl) 2013; 227:363-71. [PMID: 23371490 DOI: 10.1007/s00213-013-2977-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 12/21/2012] [Indexed: 10/27/2022]
Abstract
RATIONALE Available neurochemical probes that lower brain dopamine (DA) levels in man are limited by their tolerability and efficacy. For instance, the acute lowering of brain tyrosine is well tolerated, but only modestly lowers brain DA levels. Modification of tyrosine depletion to robustly lower DA levels would provide a superior research probe. OBJECTIVES The objective of this study was to determine whether the subthreshold stimulation of presynaptic DA receptors would potentiate tyrosine depletion-induced effects on extracellular DA levels in the medial prefrontal cortex (MPFC) and striatum of the rat. METHODS We administered quinpirole, a predominantly DA type 2 (D2R) receptor agonist, into the MPFC and striatum by reverse dialysis. A tyrosine- and phenylalanine-free neutral amino acid mixture [NAA(-)] IP was used to lower brain tyrosine levels. DA levels in the microdialysate were measured by HPLC with electrochemical detection. RESULTS Quinpirole dose-dependently lowered DA levels in MPFC as well as in the striatum. NAA(-) alone transiently lowered DA levels (80 % baseline) in the striatum, but had no effect in MPFC. The co-administration of NAA(-) and a subthreshold concentration of quinpirole (6.25 nM) lowered DA levels (50 % baseline) in both the MPFC and striatum. This effect was blocked by the mixed D2R/D3R antagonist haloperidol at IP doses that on their own did not affect DA levels (10.0 nmol/kg in the MPFC and 0.10 nmol/kg in the striatum). CONCLUSIONS Pharmacological stimulation of inhibitory D2R receptors during tyrosine depletion markedly lowers the extracellular DA levels in the MPFC and striatum. The data suggest that combining tyrosine depletion with a low dose of a DA agonist should robustly lower brain regional DA levels in man.
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Brodnik Z, Bongiovanni R, Double M, Jaskiw GE. Increased tyrosine availability increases brain regional DOPA levels in vivo. Neurochem Int 2012; 61:1001-6. [DOI: 10.1016/j.neuint.2012.07.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 06/30/2012] [Accepted: 07/13/2012] [Indexed: 10/28/2022]
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Tsai SJ, Chao CY, Yin MC. Preventive and therapeutic effects of caffeic acid against inflammatory injury in striatum of MPTP-treated mice. Eur J Pharmacol 2011; 670:441-7. [DOI: 10.1016/j.ejphar.2011.09.171] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2011] [Revised: 09/14/2011] [Accepted: 09/16/2011] [Indexed: 10/17/2022]
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King JM, Muthian G, Mackey V, Smith M, Charlton C. L-Dihydroxyphenylalanine modulates the steady-state expression of mouse striatal tyrosine hydroxylase, aromatic L-amino acid decarboxylase, dopamine and its metabolites in an MPTP mouse model of Parkinson's disease. Life Sci 2011; 89:638-43. [PMID: 21871902 DOI: 10.1016/j.lfs.2011.08.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 07/13/2011] [Accepted: 07/27/2011] [Indexed: 10/17/2022]
Abstract
AIMS l-3,4-Dihydroxyphenylalanine (L-DOPA) is the most effective symptomatic treatment for Parkinson's disease (PD), but PD patients usually experience a successful response to L-DOPA therapy followed by a progressive loss of response. L-DOPA efficacy relies on its decarboxylation by aromatic l-amino acid decarboxylase (AAAD) to form dopamine (DA). So exogenous L-DOPA drives the reaction and AAAD becomes the rate limiting enzyme in the supply of DA. In turn, exogenous L-DOPA regulates the expression and activity of AAAD as well as the synthesis of DA and its metabolites, changes that may be linked to the efficacy and side-effects of L-DOPA. MAIN METHODS One-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse PD model was utilized to study the effects of L-DOPA on the steady-state level and activity of AAAD, tyrosine hydroxylase (TH), DA and the metabolites of DA. The MPTP and control mice were treated twice daily with PBS or with 100mg/kg of L-DOPA for 14days and the expression and activity of AAAD, the expression of TH and the levels of DA and its metabolites were determined 24h after L-DOPA or PBS treatment, when exogenous L-DOPA is eliminated. KEY FINDINGS In the MPTP model, L-DOPA reduced the steady-state expression and the activity of striatal AAAD by 52% and 50%, respectively, DA and metabolites were also significantly decreased. SIGNIFICANCE The outcome shows that while L-DOPA replenishes striatal DA it also down-regulates AAAD and the steady-state synthesis and metabolic capability of the dopaminergic system. These findings are important in the precipitation of L-DOPA induced side effects and the management of L-DOPA therapy.
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Affiliation(s)
- Jennifer M King
- Department of Neuroscience and Pharmacology, 1005 Dr. D.B. Todd Jr. Blvd. Meharry Medical College, Nashville, TN 37208, USA
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Duchemin AM, Neff NH, Hadjiconstantinou M. Aromatic l-amino acid decarboxylase phosphorylation and activation by PKGIαin vitro. J Neurochem 2010; 114:542-52. [DOI: 10.1111/j.1471-4159.2010.06784.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Increased expression of VMAT2 in dopaminergic neurons during nicotine withdrawal. Neurosci Lett 2009; 467:182-6. [PMID: 19835933 DOI: 10.1016/j.neulet.2009.10.038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 10/02/2009] [Accepted: 10/08/2009] [Indexed: 11/21/2022]
Abstract
Evidence suggests that the vesicular monoamine transporter-2 (VMAT2) is regulated in striatum and dopamine (DA) may play a role in its regulation. DA is an important mediator of the behavioral actions of nicotine, and dopaminergic neurotransmission is altered following nicotine administration. We investigated the effect of nicotine withdrawal on the expression of VMAT2 in the midbrain DA neurons in animals dependent to nicotine. Mice were injected with nicotine free base 2mg/kg, sc, four times daily for 14 days and killed 12-72h after drug discontinuation. VMAT2 protein was increased in the striatum of nicotine-treated mice in a time-dependent fashion at all times studied. Furthermore, in situ hybridization studies demonstrated that VMAT2 mRNA was elevated in the substantia nigra pars compacta and ventral tegmental area, indicating enhanced gene expression and subsequent protein synthesis. Tissue DA content and synthesis were unaltered in the striatum of nicotine-treated mice at the times studied. However, basal DA release was decreased at 12 and 24h after nicotine discontinuation which coincided with the elevated levels of VMAT2 protein. VMAT2 up-regulation might be a compensatory mechanism to restore and maintain synaptic transmission in dopaminergic midbrain neurons during nicotine withdrawal.
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Vieira-Coelho MA, Serrão MP, Afonso J, Pinto CE, Moura E. Catecholamine synthesis and metabolism in the central nervous system of mice lacking alpha-adrenoceptor subtypes. Br J Pharmacol 2009; 158:726-37. [PMID: 19703163 DOI: 10.1111/j.1476-5381.2009.00375.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE This study investigates the role of alpha(2)-adrenoceptor subtypes, alpha(2A), alpha(2B) and alpha(2C), on catecholamine synthesis and catabolism in the central nervous system of mice. EXPERIMENTAL APPROACH Activities of the main catecholamine synthetic and catabolic enzymes were determined in whole brains obtained from alpha(2A)-, alpha(2B)- and alpha(2C)-adrenoceptor knockout (KO) and C56Bl\7 wild-type (WT) mice. KEY RESULTS Although no significant differences were found in tyrosine hydroxylase activity and expression, brain tissue levels of 3,4-dihydroxyphenylalanine were threefold higher in alpha(2A)- and alpha(2C)-adrenoceptor KO mice. Brain tissue levels of dopamine and noradrenaline were significantly higher in alpha(2A) and alpha(2C)KOs compared with WT [WT: 2.8 +/- 0.5, 1.1 +/- 0.1; alpha(2A)KO: 6.9 +/- 0.7, 1.9 +/- 0.1; alpha(2B)KO: 2.3 +/- 0.2, 1.0 +/- 0.1; alpha(2C)KO: 4.6 +/- 0.8, 1.5 +/- 0.2 nmol.(g tissue)(-1), for dopamine and noradrenaline respectively]. Aromatic L-amino acid decarboxylase activity was significantly higher in alpha(2A) and alpha(2C)KO [WT: 40 +/- 1; alpha(2A): 77 +/- 2; alpha(2B): 40 +/- 1; alpha(2C): 50 +/- 1, maximum velocity (V(max)) in nmol.(mg protein)(-1).h(-1)], but no significant differences were found in dopamine beta-hydroxylase. Of the catabolic enzymes, catechol-O-methyltransferase enzyme activity was significantly higher in all three alpha(2)KO mice [WT: 2.0 +/- 0.0; alpha(2A): 2.4 +/- 0.1; alpha(2B): 2.2 +/- 0.0; alpha(2C): 2.2 +/- 0.0 nmol.(mg protein)(-1).h(-1)], but no significant differences were found in monoamine oxidase activity between all alpha(2)KOs and WT mice. CONCLUSIONS AND IMPLICATIONS In mouse brain, deletion of alpha(2A)- or alpha(2C)-adrenoceptors increased cerebral aromatic L-amino acid decarboxylase activity and catecholamine tissue levels. Deletion of any alpha(2)-adrenoceptor subtypes resulted in increased activity of catechol-O-methyltransferase. Higher 3,4-dihydroxyphenylalanine tissue levels in alpha(2A) and alpha(2C)KO mice could be explained by increased 3,4-dihydroxyphenylalanine transport.
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Affiliation(s)
- M A Vieira-Coelho
- Institute of Pharmacology and Therapeutics, University of Porto, Porto, Portugal
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Allen GFG, Land JM, Heales SJR. A new perspective on the treatment of aromatic L-amino acid decarboxylase deficiency. Mol Genet Metab 2009; 97:6-14. [PMID: 19231266 DOI: 10.1016/j.ymgme.2009.01.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 01/16/2009] [Accepted: 01/16/2009] [Indexed: 11/26/2022]
Abstract
The final step in production of the neurotransmitters dopamine and serotonin is catalyzed by aromatic l-amino acid decarboxylase (AADC). AADC deficiency is a debilitating genetic condition that results in a deficit in these neurotransmitters, and manifests in infancy as a severe movement disorder with developmental delay. Response to current treatments is often disappointing. We have reviewed the literature to look for improvements to the current treatment strategy and also for new directions for AADC deficiency treatment. There may be differences in the mode of action, side-effect risk and effectiveness between different dopamine agonists and monoamine oxidase inhibitors currently used for AADC deficiency treatment. The range of these drugs used requires re-evaluation as some may have greater efficacy than others. Pyridoxal 5'-phosphate, the AADC cofactor may stabilize AADC and could increase AADC activity. Pyridoxal 5'-phosphate could have advantages as a treatment instead of pyridoxine. Atypical neuroleptics and peripheral AADC inhibitors both increase AADC activity in vivo and could be a future direction for AADC deficiency treatment and related conditions. Parkinson's disease gene therapy to deliver and express the human AADC gene in striatum is being tested in humans. Consequently gene therapy for AADC deficiency could be a realistic aim however an animal model of AADC deficiency is important for further progression.
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Affiliation(s)
- George F G Allen
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square House, Queen Square, London WC1N 3BG, UK.
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Hadjiconstantinou M, Neff NH. Enhancing aromatic L-amino acid decarboxylase activity: implications for L-DOPA treatment in Parkinson's disease. CNS Neurosci Ther 2009; 14:340-51. [PMID: 19040557 DOI: 10.1111/j.1755-5949.2008.00058.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Aromatic L-amino acid decarboxylase (AAAD) is an essential enzyme for the formation of catecholamines, indolamines, and trace amines. Moreover, it is a required enzyme for converting L-DOPA to dopamine when treating patients with Parkinson's disease (PD). There is now substantial evidence that the activity of AAAD in striatum is regulated by activation and induction, and second messengers play a role. Enzyme activity can be modulated by drugs acting on a number of neurotransmitter receptors including dopamine (D1-4), glutamate (NMDA), serotonin (5-HT(1A), 5-HT(2A)) and nicotinic acetylcholine receptors. Generally, antagonists enhance AAAD activity; while, agonists may diminish it. Enhancement of AAAD activity is functional, as the formation of dopamine from exogenous L-DOPA mirrors activity. Following a lesion of nigrostriatal dopaminergic neurons, AAAD in striatum responds more robustly to pharmacological manipulations, and this is true for the decarboxylation of exogenous L-DOPA as well. We review the evidence for parallel modulation of AAAD activity and L-DOPA decarboxylation and propose that this knowledge can be exploited to optimize the formation of dopamine from exogenous L-DOPA. This information can be used as a blue print for the design of novel L-DOPA treatment adjuvants to benefit patients with PD.
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Affiliation(s)
- Maria Hadjiconstantinou
- Division of Molecular Neuropsychopharmacology, Department of Psychiatry, College of Medicine, Ohio State University, Columbus, OH 43210, USA
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