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Muddapu VRJ, Vijayakumar K, Ramakrishnan K, Chakravarthy VS. A Multi-Scale Computational Model of Levodopa-Induced Toxicity in Parkinson's Disease. Front Neurosci 2022; 16:797127. [PMID: 35516806 PMCID: PMC9063169 DOI: 10.3389/fnins.2022.797127] [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: 10/18/2021] [Accepted: 03/15/2022] [Indexed: 01/08/2023] Open
Abstract
Parkinson's disease (PD) is caused by the progressive loss of dopaminergic cells in substantia nigra pars compacta (SNc). The root cause of this cell loss in PD is still not decisively elucidated. A recent line of thinking has traced the cause of PD neurodegeneration to metabolic deficiency. Levodopa (L-DOPA), a precursor of dopamine, used as a symptom-relieving treatment for PD, leads to positive and negative outcomes. Several researchers inferred that L-DOPA might be harmful to SNc cells due to oxidative stress. The role of L-DOPA in the course of the PD pathogenesis is still debatable. We hypothesize that energy deficiency can lead to L-DOPA-induced toxicity in two ways: by promoting dopamine-induced oxidative stress and by exacerbating excitotoxicity in SNc. We present a systems-level computational model of SNc-striatum, which will help us understand the mechanism behind neurodegeneration postulated above and provide insights into developing disease-modifying therapeutics. It was observed that SNc terminals are more vulnerable to energy deficiency than SNc somas. During L-DOPA therapy, it was observed that higher L-DOPA dosage results in increased loss of terminals in SNc. It was also observed that co-administration of L-DOPA and glutathione (antioxidant) evades L-DOPA-induced toxicity in SNc neurons. Our proposed model of the SNc-striatum system is the first of its kind, where SNc neurons were modeled at a biophysical level, and striatal neurons were modeled at a spiking level. We show that our proposed model was able to capture L-DOPA-induced toxicity in SNc, caused by energy deficiency.
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Affiliation(s)
| | - Karthik Vijayakumar
- Department of Biotechnology, Rajalakshmi Engineering College, Chennai, India
| | | | - V. Srinivasa Chakravarthy
- Department of Biotechnology, Bhupat and Jyothi Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, India
- *Correspondence: V. Srinivasa Chakravarthy
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2
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Cho HU, Kim S, Sim J, Yang S, An H, Nam MH, Jang DP, Lee CJ. Redefining differential roles of MAO-A in dopamine degradation and MAO-B in tonic GABA synthesis. Exp Mol Med 2021; 53:1148-1158. [PMID: 34244591 PMCID: PMC8333267 DOI: 10.1038/s12276-021-00646-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 12/21/2022] Open
Abstract
Monoamine oxidase (MAO) is believed to mediate the degradation of monoamine neurotransmitters, including dopamine, in the brain. Between the two types of MAO, MAO-B has been believed to be involved in dopamine degradation, which supports the idea that the therapeutic efficacy of MAO-B inhibitors in Parkinson's disease can be attributed to an increase in extracellular dopamine concentration. However, this belief has been controversial. Here, by utilizing in vivo phasic and basal electrochemical monitoring of extracellular dopamine with fast-scan cyclic voltammetry and multiple-cyclic square wave voltammetry and ex vivo fluorescence imaging of dopamine with GRABDA2m, we demonstrate that MAO-A, but not MAO-B, mainly contributes to striatal dopamine degradation. In contrast, our whole-cell patch-clamp results demonstrated that MAO-B, but not MAO-A, was responsible for astrocytic GABA-mediated tonic inhibitory currents in the rat striatum. We conclude that, in contrast to the traditional belief, MAO-A and MAO-B have profoundly different roles: MAO-A regulates dopamine levels, whereas MAO-B controls tonic GABA levels.
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Affiliation(s)
- Hyun-U Cho
- Department of Biomedical Engineering, Hanyang University, Seoul, Korea
| | - Sunpil Kim
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Korea
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, Korea
| | - Jeongeun Sim
- Department of Biomedical Engineering, Hanyang University, Seoul, Korea
| | - Seulkee Yang
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea
| | - Heeyoung An
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Korea
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, Korea
| | - Min-Ho Nam
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea.
- Department of KHU-KIST Convergence Science and Technology, Kyung Hee University, Seoul, Korea.
| | - Dong-Pyo Jang
- Department of Biomedical Engineering, Hanyang University, Seoul, Korea.
| | - C Justin Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Korea.
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, Korea.
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3
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Rusheen AE, Gee TA, Jang DP, Blaha CD, Bennet KE, Lee KH, Heien ML, Oh Y. Evaluation of electrochemical methods for tonic dopamine detection in vivo. Trends Analyt Chem 2020; 132:116049. [PMID: 33597790 PMCID: PMC7885180 DOI: 10.1016/j.trac.2020.116049] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Dysfunction in dopaminergic neuronal systems underlie a number of neurologic and psychiatric disorders such as Parkinson's disease, drug addiction, and schizophrenia. Dopamine systems communicate via two mechanisms, a fast "phasic" release (sub-second to second) that is related to salient stimuli and a slower "tonic" release (minutes to hours) that regulates receptor tone. Alterations in tonic levels are thought to be more critically important in enabling normal motor, cognitive, and motivational functions, and dysregulation in tonic dopamine levels are associated with neuropsychiatric disorders. Therefore, development of neurochemical recording techniques that enable rapid, selective, and quantitative measurements of changes in tonic extracellular levels are essential in determining the role of dopamine in both normal and disease states. Here, we review state-of-the-art advanced analytical techniques for in vivo detection of tonic levels, with special focus on electrochemical techniques for detection in humans.
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Affiliation(s)
- Aaron E. Rusheen
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, 55905, United States
- Medical Scientist Training Program, Mayo Clinic, Rochester, MN, 55905, United States
| | - Taylor A. Gee
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, United States
| | - Dong P. Jang
- Department of Biomedical Engineering, Hanyang University, Seoul, 04763, Republic of Korea
| | - Charles D. Blaha
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, 55905, United States
| | - Kevin E. Bennet
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, 55905, United States
- Division of Engineering, Mayo Clinic, Rochester, MN, 55905, United States
| | - Kendall H. Lee
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, 55905, United States
- Department of Biomedical Engineering, Mayo Clinic, Rochester, MN, 55905, United States
| | - Michael L. Heien
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, United States
| | - Yoonbae Oh
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, 55905, United States
- Department of Biomedical Engineering, Mayo Clinic, Rochester, MN, 55905, United States
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4
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Urakubo H, Yagishita S, Kasai H, Ishii S. Signaling models for dopamine-dependent temporal contiguity in striatal synaptic plasticity. PLoS Comput Biol 2020; 16:e1008078. [PMID: 32701987 PMCID: PMC7402527 DOI: 10.1371/journal.pcbi.1008078] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 08/04/2020] [Accepted: 06/19/2020] [Indexed: 02/06/2023] Open
Abstract
Animals remember temporal links between their actions and subsequent rewards. We previously discovered a synaptic mechanism underlying such reward learning in D1 receptor (D1R)-expressing spiny projection neurons (D1 SPN) of the striatum. Dopamine (DA) bursts promote dendritic spine enlargement in a time window of only a few seconds after paired pre- and post-synaptic spiking (pre-post pairing), which is termed as reinforcement plasticity (RP). The previous study has also identified underlying signaling pathways; however, it still remains unclear how the signaling dynamics results in RP. In the present study, we first developed a computational model of signaling dynamics of D1 SPNs. The D1 RP model successfully reproduced experimentally observed protein kinase A (PKA) activity, including its critical time window. In this model, adenylate cyclase type 1 (AC1) in the spines/thin dendrites played a pivotal role as a coincidence detector against pre-post pairing and DA burst. In particular, pre-post pairing (Ca2+ signal) stimulated AC1 with a delay, and the Ca2+-stimulated AC1 was activated by the DA burst for the asymmetric time window. Moreover, the smallness of the spines/thin dendrites is crucial to the short time window for the PKA activity. We then developed a RP model for D2 SPNs, which also predicted the critical time window for RP that depended on the timing of pre-post pairing and phasic DA dip. AC1 worked for the coincidence detector in the D2 RP model as well. We further simulated the signaling pathway leading to Ca2+/calmodulin-dependent protein kinase II (CaMKII) activation and clarified the role of the downstream molecules of AC1 as the integrators that turn transient input signals into persistent spine enlargement. Finally, we discuss how such timing windows guide animals' reward learning.
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Affiliation(s)
- Hidetoshi Urakubo
- Integrated Systems Biology Laboratory, Department of Systems Science, Graduate School of Informatics, Kyoto University, Sakyo-ku, Kyoto, Japan
- * E-mail:
| | - Sho Yagishita
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
- International Research Center for Neurointelligence (WPI-IRCN), University of Tokyo Institutes for Advanced Study (UTIAS), Tokyo, Japan
| | - Haruo Kasai
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
- International Research Center for Neurointelligence (WPI-IRCN), University of Tokyo Institutes for Advanced Study (UTIAS), Tokyo, Japan
| | - Shin Ishii
- Integrated Systems Biology Laboratory, Department of Systems Science, Graduate School of Informatics, Kyoto University, Sakyo-ku, Kyoto, Japan
- International Research Center for Neurointelligence (WPI-IRCN), University of Tokyo Institutes for Advanced Study (UTIAS), Tokyo, Japan
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Perelmuter JT, Wilson AB, Sisneros JA, Forlano PM. Forebrain Dopamine System Regulates Inner Ear Auditory Sensitivity to Socially Relevant Acoustic Signals. Curr Biol 2019; 29:2190-2198.e3. [PMID: 31204161 DOI: 10.1016/j.cub.2019.05.055] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 04/13/2019] [Accepted: 05/20/2019] [Indexed: 01/11/2023]
Abstract
Dopamine is integral to attentional and motivational processes, but studies are largely restricted to the central nervous system. In mammals [1, 2] and fishes [3, 4], central dopaminergic neurons project to the inner ear and could modulate acoustic signals at the earliest stages of processing. Studies in rodents show dopamine inhibits cochlear afferent neurons and protects against noise-induced acoustic injury [5-10]. However, other functions for inner ear dopamine have not been investigated, and the effect of dopamine on peripheral auditory processing in non-mammalians remains unknown [11, 12]. Insights could be gained by studies conducted in the context of intraspecific acoustic communication. We present evidence from a vocal fish linking reproductive-state-dependent changes in auditory sensitivity with seasonal changes in the dopaminergic efferent system in the saccule, their primary organ of hearing. Plainfin midshipman (Porichthys notatus) migrate from deep-water winter habitats to the intertidal zone in the summer to breed. Nesting males produce nocturnal vocalizations to attract females [13]. Both sexes undergo seasonal enhancement of hearing sensitivity at the level of the hair cell [14-16], increasing the likelihood of detecting conspecific signals [17, 18]. Importantly, reproductive females concurrently have reduced dopaminergic input to the saccule [19]. Here, we show that dopamine decreases saccule auditory sensitivity via a D2-like receptor. Saccule D2a receptor expression is reduced in the summer and correlates with sensitivity within and across seasons. We propose that reproductive-state-dependent changes to the dopaminergic efferent system provide a release of inhibition in the saccule, enhancing peripheral encoding of social-acoustic signals.
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Affiliation(s)
- Jonathan T Perelmuter
- Psychology Subprogram in Behavioral & Cognitive Neuroscience, The Graduate Center, City University of New York, 365 5(th) Avenue, New York, NY 10016, USA; Biology Department, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA.
| | - Anthony B Wilson
- Biology Department, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA; Biology Subprogram in Ecology, Evolutionary Biology and Behavior, The Graduate Center, City University of New York, 365 5(th) Avenue, New York, NY 10016, USA
| | - Joseph A Sisneros
- Psychology Department, University of Washington, Guthrie Hall, Seattle, WA 98195, USA
| | - Paul M Forlano
- Psychology Subprogram in Behavioral & Cognitive Neuroscience, The Graduate Center, City University of New York, 365 5(th) Avenue, New York, NY 10016, USA; Biology Department, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA; Biology Subprogram in Neuroscience, The Graduate Center, City University of New York, 365 5(th) Avenue, New York, NY 10016, USA; Biology Subprogram in Ecology, Evolutionary Biology and Behavior, The Graduate Center, City University of New York, 365 5(th) Avenue, New York, NY 10016, USA.
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Yapo C, Nair AG, Clement L, Castro LR, Hellgren Kotaleski J, Vincent P. Detection of phasic dopamine by D1 and D2 striatal medium spiny neurons. J Physiol 2017; 595:7451-7475. [PMID: 28782235 PMCID: PMC5730852 DOI: 10.1113/jp274475] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 07/10/2017] [Indexed: 12/15/2022] Open
Abstract
KEY POINTS Brief dopamine events are critical actors of reward-mediated learning in the striatum; the intracellular cAMP-protein kinase A (PKA) response of striatal medium spiny neurons to such events was studied dynamically using a combination of biosensor imaging in mouse brain slices and in silico simulations. Both D1 and D2 medium spiny neurons can sense brief dopamine transients in the sub-micromolar range. While dopamine transients profoundly change cAMP levels in both types of medium spiny neurons, the PKA-dependent phosphorylation level remains unaffected in D2 neurons. At the level of PKA-dependent phosphorylation, D2 unresponsiveness depends on protein phosphatase-1 (PP1) inhibition by DARPP-32. Simulations suggest that D2 medium spiny neurons could detect transient dips in dopamine level. ABSTRACT The phasic release of dopamine in the striatum determines various aspects of reward and action selection, but the dynamics of the dopamine effect on intracellular signalling remains poorly understood. We used genetically encoded FRET biosensors in striatal brain slices to quantify the effect of transient dopamine on cAMP or PKA-dependent phosphorylation levels, and computational modelling to further explore the dynamics of this signalling pathway. Medium-sized spiny neurons (MSNs), which express either D1 or D2 dopamine receptors, responded to dopamine by an increase or a decrease in cAMP, respectively. Transient dopamine showed similar sub-micromolar efficacies on cAMP in both D1 and D2 MSNs, thus challenging the commonly accepted notion that dopamine efficacy is much higher on D2 than on D1 receptors. However, in D2 MSNs, the large decrease in cAMP level triggered by transient dopamine did not translate to a decrease in PKA-dependent phosphorylation level, owing to the efficient inhibition of protein phosphatase 1 by DARPP-32. Simulations further suggested that D2 MSNs can also operate in a 'tone-sensing' mode, allowing them to detect transient dips in basal dopamine. Overall, our results show that D2 MSNs may sense much more complex patterns of dopamine than previously thought.
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Affiliation(s)
- Cedric Yapo
- CNRS, UMR8256 “Biological Adaptation and Ageing”Institut de Biologie Paris‐Seine (IBPS)F‐75005ParisFrance
- Université Pierre et Marie Curie (UPMC, Paris 6)Sorbonne UniversitésF‐75005ParisFrance
| | - Anu G. Nair
- Science for Life Laboratory, School of Computer Science and CommunicationKTH Royal Institute of Technology10044StockholmSweden
- National Centre for Biological SciencesTata Institute of Fundamental ResearchBangalore560065KarnatakaIndia
- Manipal UniversityManipal576104KarnatakaIndia
| | - Lorna Clement
- CNRS, UMR8256 “Biological Adaptation and Ageing”Institut de Biologie Paris‐Seine (IBPS)F‐75005ParisFrance
| | - Liliana R. Castro
- CNRS, UMR8256 “Biological Adaptation and Ageing”Institut de Biologie Paris‐Seine (IBPS)F‐75005ParisFrance
- Université Pierre et Marie Curie (UPMC, Paris 6)Sorbonne UniversitésF‐75005ParisFrance
| | - Jeanette Hellgren Kotaleski
- Science for Life Laboratory, School of Computer Science and CommunicationKTH Royal Institute of Technology10044StockholmSweden
- Department of NeuroscienceKarolinska Institutet17177SolnaSweden
| | - Pierre Vincent
- CNRS, UMR8256 “Biological Adaptation and Ageing”Institut de Biologie Paris‐Seine (IBPS)F‐75005ParisFrance
- Université Pierre et Marie Curie (UPMC, Paris 6)Sorbonne UniversitésF‐75005ParisFrance
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7
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Bucher ES, Wightman RM. Electrochemical Analysis of Neurotransmitters. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2015; 8:239-61. [PMID: 25939038 PMCID: PMC4728736 DOI: 10.1146/annurev-anchem-071114-040426] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Chemical signaling through the release of neurotransmitters into the extracellular space is the primary means of communication between neurons. More than four decades ago, Ralph Adams and his colleagues realized the utility of electrochemical methods for the study of easily oxidizable neurotransmitters, such as dopamine, norepinephrine, and serotonin and their metabolites. Today, electrochemical techniques are frequently coupled to microelectrodes to enable spatially resolved recordings of rapid neurotransmitter dynamics in a variety of biological preparations spanning from single cells to the intact brain of behaving animals. In this review, we provide a basic overview of the principles underlying constant-potential amperometry and fast-scan cyclic voltammetry, the most commonly employed electrochemical techniques, and the general application of these methods to the study of neurotransmission. We thereafter discuss several recent developments in sensor design and experimental methodology that are challenging the current limitations defining the application of electrochemical methods to neurotransmitter measurements.
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Maex R, Grinevich VP, Grinevich V, Budygin E, Bencherif M, Gutkin B. Understanding the role α7 nicotinic receptors play in dopamine efflux in nucleus accumbens. ACS Chem Neurosci 2014; 5:1032-40. [PMID: 25147933 PMCID: PMC4198061 DOI: 10.1021/cn500126t] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
![]()
Neuronal nicotinic acetylcholine
receptors (NNRs) of the α7
subtype have been shown to contribute to the release of dopamine in
the nucleus accumbens. The site of action and the underlying mechanism,
however, are unclear. Here we applied a circuit modeling approach,
supported by electrochemical in vivo recordings, to clarify this issue.
Modeling revealed two potential mechanisms for the drop in accumbal
dopamine efflux evoked by the selective α7 partial agonist TC-7020.
TC-7020 could desensitize α7 NNRs located predominantly on dopamine
neurons or glutamatergic afferents to them or, alternatively, activate
α7 NNRs located on the glutamatergic afferents to GABAergic
interneurons in the ventral tegmental area. Only the model based on
desensitization, however, was able to explain the neutralizing effect
of coapplied PNU-120596, a positive allosteric modulator. According
to our results, the most likely sites of action are the preterminal
α7 NNRs controlling glutamate release from cortical afferents
to the nucleus accumbens. These findings offer a rationale for the
further investigation of α7 NNR agonists as therapy for diseases
associated with enhanced mesolimbic dopaminergic tone, such as schizophrenia
and addiction.
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Affiliation(s)
- Reinoud Maex
- Department
of Cognitive Sciences, École Normale Supérieure, Paris 75005, France
| | - Vladimir P. Grinevich
- Targacept Inc., Winston-Salem, North Carolina 27101, United States
- Wake Forest School of Medicine, Winston-Salem, North Carolina 27157, United States
| | - Valentina Grinevich
- Wake Forest School of Medicine, Winston-Salem, North Carolina 27157, United States
| | - Evgeny Budygin
- Wake Forest School of Medicine, Winston-Salem, North Carolina 27157, United States
- St. Petersburg State University, St. Petersburg 199034, Russia
| | | | - Boris Gutkin
- Department
of Cognitive Sciences, École Normale Supérieure, Paris 75005, France
- Center
for Cognition and Decision Making, National Research University Higher School of Economics, Moscow 101000, Russia
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Spanos M, Gras-Najjar J, Letchworth JM, Sanford AL, Toups JV, Sombers LA. Quantitation of hydrogen peroxide fluctuations and their modulation of dopamine dynamics in the rat dorsal striatum using fast-scan cyclic voltammetry. ACS Chem Neurosci 2013; 4:782-9. [PMID: 23556461 DOI: 10.1021/cn4000499] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The dopaminergic neurons of the nigrostriatal dopamine (DA) projection from the substantia nigra to the dorsal striatum become dysfunctional and slowly degenerate in Parkinson's disease, a neurodegenerative disorder that afflicts more than one million Americans. There is no specific known cause for idiopathic Parkinson's disease; however, multiple lines of evidence implicate oxidative stress as an underlying factor in both the initiation and progression of the disease. This involves the enhanced generation of reactive oxygen species, including hydrogen peroxide (H2O2), whose role in complex biological processes is not well understood. Using fast-scan cyclic voltammetry at bare carbon-fiber microelectrodes, we have simultaneously monitored and quantified H2O2 and DA fluctuations in intact striatal tissue under basal conditions and in response to the initiation of oxidative stress. Furthermore, we have assessed the effect of acute increases in local H2O2 concentration on both electrically evoked DA release and basal DA levels. Increases in endogenous H2O2 in the dorsal striatum attenuated electrically evoked DA release, and also decreased basal DA levels in this brain region. These novel results will help to disambiguate the chemical mechanisms underlying the progression of neurodegenerative disease states, such as Parkinson's disease, that involve oxidative stress.
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Affiliation(s)
- Marina Spanos
- Chemistry Department, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Julie Gras-Najjar
- Chemistry Department, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Jeremy M. Letchworth
- Chemistry Department, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Audrey L. Sanford
- Chemistry Department, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - J. Vincent Toups
- Chemistry Department, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Leslie A. Sombers
- Chemistry Department, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
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10
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Zuo PL, Yao W, Sun L, Kuo ST, Li Q, Wang SR, Dou HQ, Xu HD, Zhang CX, Kang XJ, Zhou Z, Zhang B. Impulse-dependent extracellular resting dopamine concentration in rat striatum in vivo. Neurochem Int 2012; 62:50-7. [PMID: 23159778 DOI: 10.1016/j.neuint.2012.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 10/11/2012] [Accepted: 11/07/2012] [Indexed: 11/29/2022]
Abstract
The ambient resting dopamine (DA) concentration in brain regulates cognition and motivation. Despite its importance, resting DA level in vivo remains elusive. Here, by high-frequency stimulation of the medial forebrain bundle and immediately following the stimulus-induced DA overflow, we recorded a DA "undershoot" which is a temporal reduction of DA concentration to a level below the baseline. Based on the DA undershoot, we predicted a resting DA concentration of ∼73nM in rat striatum in vivo. Simulation studies suggested that removing basal DA by DAT during the post-stimulation inhibition of tonic DA release caused the DA undershoot, and the resting concentration of DA modulated the kinetics of the evoked DA transient. The DA undershoot was eliminated by either blocking D2 receptors with haloperidol or blocking the DA transporter (DAT) with cocaine. Therefore, the impulse-dependent resting DA concentration is in the tens of nanomolar range and is modulated by the presynaptic D2 receptors and the DAT in vivo.
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Affiliation(s)
- Pan-Li Zuo
- State Key Laboratory of Biomembrane and Membrane Biotechnology and the Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing 100871, China
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11
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Owesson-White CA, Roitman MF, Sombers LA, Belle AM, Keithley RB, Peele JL, Carelli RM, Wightman RM. Sources contributing to the average extracellular concentration of dopamine in the nucleus accumbens. J Neurochem 2012; 121:252-62. [PMID: 22296263 PMCID: PMC3323736 DOI: 10.1111/j.1471-4159.2012.07677.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mesolimbic dopamine neurons fire in both tonic and phasic modes resulting in detectable extracellular levels of dopamine in the nucleus accumbens (NAc). In the past, different techniques have targeted dopamine levels in the NAc to establish a basal concentration. In this study, we used in vivo fast scan cyclic voltammetry (FSCV) in the NAc of awake, freely moving rats. The experiments were primarily designed to capture changes in dopamine caused by phasic firing - that is, the measurement of dopamine 'transients'. These FSCV measurements revealed for the first time that spontaneous dopamine transients constitute a major component of extracellular dopamine levels in the NAc. A series of experiments were designed to probe regulation of extracellular dopamine. Lidocaine was infused into the ventral tegmental area, the site of dopamine cell bodies, to arrest neuronal firing. While there was virtually no instantaneous change in dopamine concentration, longer sampling revealed a decrease in dopamine transients and a time-averaged decrease in the extracellular level. Dopamine transporter inhibition using intravenous GBR12909 injections increased extracellular dopamine levels changing both frequency and size of dopamine transients in the NAc. To further unmask the mechanics governing extracellular dopamine levels we used intravenous injection of the vesicular monoamine transporter (VMAT2) inhibitor, tetrabenazine, to deplete dopamine storage and increase cytoplasmic dopamine in the nerve terminals. Tetrabenazine almost abolished phasic dopamine release but increased extracellular dopamine to ∼500 nM, presumably by inducing reverse transport by dopamine transporter (DAT). Taken together, data presented here show that average extracellular dopamine in the NAc is low (20-30 nM) and largely arises from phasic dopamine transients.
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Affiliation(s)
- CA Owesson-White
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - MF Roitman
- Department of Psychology, University of Illinois at Chicago, Chicago, Illinois 60607, USA
| | - LA Sombers
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - AM Belle
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - RB Keithley
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - JL Peele
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - RM Carelli
- Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - RM Wightman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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12
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Wallace LJ, Traeger JS. Dopac distribution and regulation in striatal dopaminergic varicosities and extracellular space. Synapse 2011; 66:160-73. [PMID: 21987292 DOI: 10.1002/syn.20996] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 09/24/2011] [Indexed: 11/06/2022]
Abstract
DOPAC, the major intermediate metabolite of dopamine, is found in the cytosolic compartment of dopaminergic terminals/varicosities and in the extracellular space. It has been proposed that extracellular DOPAC is derived from newly synthesized dopamine rather than from dopamine in the signaling pool. On the basis of literature data supporting such a concept, we hypothesize a DOPAC synthesis/secretory complex producing extracellular DOPAC and use a computational simulation model of dopaminergic varicosities to estimate the distribution of DOPAC between cytosolic and extracellular compartments, amount of newly synthesized dopamine entering the DOPAC synthesis/secretory complex, and potential regulatory processes in the complex. Results suggest that about two-thirds of DOPAC is in the extracellular space. Approximately one-third of newly synthesized dopamine is immediately processed to DOPAC, which is then secreted into extracellular space. Extracellular DOPAC concentration is approximately 300 times higher than extracellular dopamine, and cytosolic DOPAC is ∼18-fold higher than cytosolic dopamine. We suggest that the high levels of extracellular DOPAC coupled with evidence for its production from newly synthesized dopamine imply the existence of an as yet undiscovered regulatory/signaling role for DOPAC.
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Affiliation(s)
- Lane J Wallace
- Division of Pharmacology, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA.
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13
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Ito HT, Schuman EM. Functional division of hippocampal area CA1 via modulatory gating of entorhinal cortical inputs. Hippocampus 2011; 22:372-87. [PMID: 21240920 DOI: 10.1002/hipo.20909] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2010] [Indexed: 11/11/2022]
Abstract
The hippocampus receives two streams of information, spatial and nonspatial, via major afferent inputs from the medial (MEC) and lateral entorhinal cortexes (LEC). The MEC and LEC projections in the temporoammonic pathway are topographically organized along the transverse-axis of area CA1. The potential for functional segregation of area CA1, however, remains relatively unexplored. Here, we demonstrated differential novelty-induced c-Fos expression along the transverse-axis of area CA1 corresponding to topographic projections of MEC and LEC inputs. We found that, while novel place exposure induced a uniform c-Fos expression along the transverse-axis of area CA1, novel object exposure primarily activated the distal half of CA1 neurons. In hippocampal slices, we observed distinct presynaptic properties between LEC and MEC terminals, and application of either DA or NE produced a largely selective influence on one set of inputs (LEC). Finally, we demonstrated that differential c-Fos expression along the transverse axis of area CA1 was largely abolished by an antagonist of neuromodulatory receptors, clozapine. Our results suggest that neuromodulators can control topographic TA projections allowing the hippocampus to differentially encode new information along the transverse axis of area CA1.
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Affiliation(s)
- Hiroshi T Ito
- Division of Biology, Caltech/HHMI, Pasadena, California, USA
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14
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Abstract
Tonic and phasic dopamine release is implicated in learning, motivation, and motor functions. However, the relationship between spike patterns in dopaminergic neurons, the extracellular concentration of dopamine, and activation of dopamine receptors remains unresolved. In the present study, we develop a computational model of dopamine signaling that give insight into the relationship between the dynamics of release and occupancy of D(1) and D(2) receptors. The model is derived from first principles using experimental data. It has no free parameters and offers unbiased estimation of the boundaries of dopaminergic volume transmission. Bursts primarily increase occupancy of D(1) receptors, whereas pauses translate into low occupancy of D(1) and D(2) receptors. Phasic firing patterns, composed of bursts and pauses, reduce the average D(2) receptor occupancy and increase average D(1) receptor occupancy compared with equivalent tonic firing. Receptor occupancy is crucially dependent on synchrony and the balance between tonic and phasic firing modes. Our results provide quantitative insight in the dynamics of volume transmission and complement experimental data obtained with electrophysiology, positron emission tomography, microdialysis, amperometry, and voltammetry.
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15
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Vizi ES, Fekete A, Karoly R, Mike A. Non-synaptic receptors and transporters involved in brain functions and targets of drug treatment. Br J Pharmacol 2010; 160:785-809. [PMID: 20136842 DOI: 10.1111/j.1476-5381.2009.00624.x] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Beyond direct synaptic communication, neurons are able to talk to each other without making synapses. They are able to send chemical messages by means of diffusion to target cells via the extracellular space, provided that the target neurons are equipped with high-affinity receptors. While synaptic transmission is responsible for the 'what' of brain function, the 'how' of brain function (mood, attention, level of arousal, general excitability, etc.) is mainly controlled non-synaptically using the extracellular space as communication channel. It is principally the 'how' that can be modulated by medicine. In this paper, we discuss different forms of non-synaptic transmission, localized spillover of synaptic transmitters, local presynaptic modulation and tonic influence of ambient transmitter levels on the activity of vast neuronal populations. We consider different aspects of non-synaptic transmission, such as synaptic-extrasynaptic receptor trafficking, neuron-glia communication and retrograde signalling. We review structural and functional aspects of non-synaptic transmission, including (i) anatomical arrangement of non-synaptic release sites, receptors and transporters, (ii) intravesicular, intra- and extracellular concentrations of neurotransmitters, as well as the spatiotemporal pattern of transmitter diffusion. We propose that an effective general strategy for efficient pharmacological intervention could include the identification of specific non-synaptic targets and the subsequent development of selective pharmacological tools to influence them.
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Affiliation(s)
- E S Vizi
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.
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16
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Lin Y, Zhang Z, Zhao L, Wang X, Yu P, Su L, Mao L. A non-oxidative electrochemical approach to online measurements of dopamine release through laccase-catalyzed oxidation and intramolecular cyclization of dopamine. Biosens Bioelectron 2010; 25:1350-5. [DOI: 10.1016/j.bios.2009.10.028] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2009] [Revised: 10/17/2009] [Accepted: 10/20/2009] [Indexed: 10/20/2022]
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