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Bucher ML, Dunn AR, Bradner JM, Egerton KS, Burkett JP, Johnson MA, Miller GW. Synaptic vesicle glycoprotein 2C enhances vesicular storage of dopamine and counters dopaminergic toxicity. Eur J Neurosci 2024; 59:2483-2501. [PMID: 38532289 DOI: 10.1111/ejn.16311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 02/14/2024] [Accepted: 02/22/2024] [Indexed: 03/28/2024]
Abstract
Dopaminergic neurons of the substantia nigra exist in a persistent state of vulnerability resulting from high baseline oxidative stress, high-energy demand, and broad unmyelinated axonal arborisations. Impairments in the storage of dopamine compound this stress because of cytosolic reactions that transform the vital neurotransmitter into an endogenous neurotoxicant, and this toxicity is thought to contribute to the dopamine neuron degeneration that occurs Parkinson's disease. We have previously identified synaptic vesicle glycoprotein 2C (SV2C) as a modifier of vesicular dopamine function, demonstrating that genetic ablation of SV2C in mice results in decreased dopamine content and evoked dopamine release in the striatum. Here, we adapted a previously published in vitro assay utilising false fluorescent neurotransmitter 206 (FFN206) to visualise how SV2C regulates vesicular dopamine dynamics and determined that SV2C promotes the uptake and retention of FFN206 within vesicles. In addition, we present data indicating that SV2C enhances the retention of dopamine in the vesicular compartment with radiolabelled dopamine in vesicles isolated from immortalised cells and from mouse brain. Further, we demonstrate that SV2C enhances the ability of vesicles to store the neurotoxicant 1-methyl-4-phenylpyridinium (MPP+) and that genetic ablation of SV2C results in enhanced 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced vulnerability in mice. Together, these findings suggest that SV2C functions to enhance vesicular storage of dopamine and neurotoxicants and helps maintain the integrity of dopaminergic neurons.
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Affiliation(s)
- Meghan L Bucher
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA
| | - Amy R Dunn
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- The Jackson Laboratory, Bar Harbor, Maine, USA
| | - Joshua M Bradner
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- AbbVie CRC, Cambridge, Massachusetts, USA
| | - Kristen Stout Egerton
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- School of Education and Health Sciences, North Central College, Naperville, Illinois, USA
| | - James P Burkett
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, Ohio, USA
| | - Michelle A Johnson
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- College of Arts and Sciences, Oberlin College, Oberlin, Ohio, USA
| | - Gary W Miller
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
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Bucher ML, Dunn AR, Bradner JM, Egerton KS, Burkett JP, Johnson MA, Miller GW. Synaptic vesicle glycoprotein 2C enhances vesicular storage of dopamine and counters dopaminergic toxicity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.26.546143. [PMID: 37425736 PMCID: PMC10326994 DOI: 10.1101/2023.06.26.546143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Dopaminergic neurons of the substantia nigra exist in a persistent state of vulnerability resulting from high baseline oxidative stress, high energy demand, and broad unmyelinated axonal arborizations. Impairments in the storage of dopamine compound this stress due to cytosolic reactions that transform the vital neurotransmitter into an endogenous neurotoxicant, and this toxicity is thought to contribute to the dopamine neuron degeneration that occurs Parkinson's disease. We have previously identified synaptic vesicle glycoprotein 2C (SV2C) as a modifier of vesicular dopamine function, demonstrating that genetic ablation of SV2C in mice results in decreased dopamine content and evoked dopamine release in the striatum. Here, we adapted a previously published in vitro assay utilizing false fluorescent neurotransmitter 206 (FFN206) to visualize how SV2C regulates vesicular dopamine dynamics and determined that SV2C promotes the uptake and retention of FFN206 within vesicles. In addition, we present data indicating that SV2C enhances the retention of dopamine in the vesicular compartment with radiolabeled dopamine in vesicles isolated from immortalized cells and from mouse brain. Further, we demonstrate that SV2C enhances the ability of vesicles to store the neurotoxicant 1-methyl-4-phenylpyridinium (MPP+) and that genetic ablation of SV2C results in enhanced 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced vulnerability in mice. Together, these findings suggest that SV2C functions to enhance vesicular storage of dopamine and neurotoxicants, and helps maintain the integrity of dopaminergic neurons.
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Affiliation(s)
- Meghan L Bucher
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
| | - Amy R Dunn
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Joshua M Bradner
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Kristen Stout Egerton
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - James P Burkett
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Michelle A Johnson
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Gary W Miller
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
- Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10031, USA
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Pifl C, Reither H, Attems J, Zecca L. Dopamine and vesicular monoamine transport loss supports incidental Lewy body disease as preclinical idiopathic Parkinson. NPJ Parkinsons Dis 2023; 9:89. [PMID: 37322038 DOI: 10.1038/s41531-023-00514-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 04/27/2023] [Indexed: 06/17/2023] Open
Abstract
Incidental Lewy body disease (ILBD) is a neuropathological diagnosis of brains with Lewy bodies without clinical neuropsychiatric symptoms. Dopaminergic deficits suggest a relationship to preclinical Parkinson's disease (PD). We now report a subregional pattern of striatal dopamine loss in ILBD cases, with dopamine found significantly decreased in the putamen (-52%) and only to a lower extent in the caudate (-38%, not statistically significant); this is similar to the pattern in idiopathic PD in various neurochemical and in vivo imaging studies. We aimed to find out if our recently reported impaired storage of dopamine in striatal synaptic vesicles prepared from striatal tissue of cases with idiopathic PD might be an early or even causative event. We undertook parallel measurements of [3H]dopamine uptake and vesicular monoamine transporter (VMAT)2 binding sites by the specific label [3H]dihydrotetrabenazine on vesicular preparation from caudate and putamen in ILBD. Neither specific uptake of dopamine and binding of [3H]dihydrotetrabenazine, nor mean values of the calculated ratios of dopamine uptake and VMAT2 binding, a measure of uptake rate per transport site, were significantly different between ILBD and controls. ATP-dependence of [3H]dopamine uptake revealed significantly higher rates in putamen than in caudate at saturating concentrations of ATP in controls, a subregional difference lost in ILBD. Our findings support a loss of the normally higher VMAT2 activity in putamen as a contributing factor to the higher susceptibility of the putamen to dopamine depletion in idiopathic PD. Moreover, we suggest ILBD postmortem tissue as a valuable source for testing hypotheses on processes in idiopathic PD.
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Affiliation(s)
- Christian Pifl
- Center for Brain Research, Medical University of Vienna, Vienna, Austria.
| | - Harald Reither
- Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Johannes Attems
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Luigi Zecca
- Institute of Biomedical Technologies, National Research Council of Italy, Segrate, Milan, Italy
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Interactions of dopamine, iron, and alpha-synuclein linked to dopaminergic neuron vulnerability in Parkinson's disease and neurodegeneration with brain iron accumulation disorders. Neurobiol Dis 2022; 175:105920. [DOI: 10.1016/j.nbd.2022.105920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 10/21/2022] [Accepted: 11/04/2022] [Indexed: 11/08/2022] Open
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Pirooznia SK, Rosenthal LS, Dawson VL, Dawson TM. Parkinson Disease: Translating Insights from Molecular Mechanisms to Neuroprotection. Pharmacol Rev 2021; 73:33-97. [PMID: 34663684 DOI: 10.1124/pharmrev.120.000189] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Parkinson disease (PD) used to be considered a nongenetic condition. However, the identification of several autosomal dominant and recessive mutations linked to monogenic PD has changed this view. Clinically manifest PD is then thought to occur through a complex interplay between genetic mutations, many of which have incomplete penetrance, and environmental factors, both neuroprotective and increasing susceptibility, which variably interact to reach a threshold over which PD becomes clinically manifested. Functional studies of PD gene products have identified many cellular and molecular pathways, providing crucial insights into the nature and causes of PD. PD originates from multiple causes and a range of pathogenic processes at play, ultimately culminating in nigral dopaminergic loss and motor dysfunction. An in-depth understanding of these complex and possibly convergent pathways will pave the way for therapeutic approaches to alleviate the disease symptoms and neuroprotective strategies to prevent disease manifestations. This review is aimed at providing a comprehensive understanding of advances made in PD research based on leveraging genetic insights into the pathogenesis of PD. It further discusses novel perspectives to facilitate identification of critical molecular pathways that are central to neurodegeneration that hold the potential to develop neuroprotective and/or neurorestorative therapeutic strategies for PD. SIGNIFICANCE STATEMENT: A comprehensive review of PD pathophysiology is provided on the complex interplay of genetic and environmental factors and biologic processes that contribute to PD pathogenesis. This knowledge identifies new targets that could be leveraged into disease-modifying therapies to prevent or slow neurodegeneration in PD.
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Affiliation(s)
- Sheila K Pirooznia
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering (S.K.P., V.L.D., T.M.D.), Departments of Neurology (S.K.P., L.S.R., V.L.D., T.M.D.), Departments of Physiology (V.L.D.), Solomon H. Snyder Department of Neuroscience (V.L.D., T.M.D.), Department of Pharmacology and Molecular Sciences (T.M.D.), Johns Hopkins University School of Medicine, Baltimore, Maryland; Adrienne Helis Malvin Medical Research Foundation, New Orleans, Louisiana (S.K.P., V.L.D., T.M.D.); and Diana Helis Henry Medical Research Foundation, New Orleans, Louisiana (S.K.P., V.L.D., T.M.D.)
| | - Liana S Rosenthal
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering (S.K.P., V.L.D., T.M.D.), Departments of Neurology (S.K.P., L.S.R., V.L.D., T.M.D.), Departments of Physiology (V.L.D.), Solomon H. Snyder Department of Neuroscience (V.L.D., T.M.D.), Department of Pharmacology and Molecular Sciences (T.M.D.), Johns Hopkins University School of Medicine, Baltimore, Maryland; Adrienne Helis Malvin Medical Research Foundation, New Orleans, Louisiana (S.K.P., V.L.D., T.M.D.); and Diana Helis Henry Medical Research Foundation, New Orleans, Louisiana (S.K.P., V.L.D., T.M.D.)
| | - Valina L Dawson
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering (S.K.P., V.L.D., T.M.D.), Departments of Neurology (S.K.P., L.S.R., V.L.D., T.M.D.), Departments of Physiology (V.L.D.), Solomon H. Snyder Department of Neuroscience (V.L.D., T.M.D.), Department of Pharmacology and Molecular Sciences (T.M.D.), Johns Hopkins University School of Medicine, Baltimore, Maryland; Adrienne Helis Malvin Medical Research Foundation, New Orleans, Louisiana (S.K.P., V.L.D., T.M.D.); and Diana Helis Henry Medical Research Foundation, New Orleans, Louisiana (S.K.P., V.L.D., T.M.D.)
| | - Ted M Dawson
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering (S.K.P., V.L.D., T.M.D.), Departments of Neurology (S.K.P., L.S.R., V.L.D., T.M.D.), Departments of Physiology (V.L.D.), Solomon H. Snyder Department of Neuroscience (V.L.D., T.M.D.), Department of Pharmacology and Molecular Sciences (T.M.D.), Johns Hopkins University School of Medicine, Baltimore, Maryland; Adrienne Helis Malvin Medical Research Foundation, New Orleans, Louisiana (S.K.P., V.L.D., T.M.D.); and Diana Helis Henry Medical Research Foundation, New Orleans, Louisiana (S.K.P., V.L.D., T.M.D.)
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Therapeutic potential of mangiferin in the treatment of various neuropsychiatric and neurodegenerative disorders. Neurochem Int 2020; 143:104939. [PMID: 33346032 DOI: 10.1016/j.neuint.2020.104939] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 11/02/2020] [Accepted: 12/12/2020] [Indexed: 12/19/2022]
Abstract
Xanthones are important chemical class of bioactive products that confers therapeutic benefits. Of several xanthones, mangiferin is known to be distributed widely across several fruits, vegetables and medicinal plants. Mangiferin has been shown to exert neuroprotective effects in both in-vitro and in-vivo models. Mangiferin attenuates cerebral infarction, cerebral edema, lipid peroxidation (MDA), neuronal damage, etc. Mangiferin further potentiate levels of endogenous antioxidants to confer protection against the oxidative stress inside the neurons. Mangiferin is involved in the regulation of various signaling pathways that influences the production and levels of proinflammatory cytokines in brain. Mangiferin cosunteracted the neurotoxic effect of amyloid-beta, MPTP, rotenone, 6-OHDA etc and confer protection to neurons. These evidence suggested that the mangiferin may be a potential therapeutic strategy for the treatment of various neurological disorders. The present review demonstrated the pharmacodynamics-pharmacokinetics of mangiferin and neurotherapeutic potential in several neurological disorders with underlying mechanisms.
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Post MR, Lieberman OJ, Mosharov EV. Can Interactions Between α-Synuclein, Dopamine and Calcium Explain Selective Neurodegeneration in Parkinson's Disease? Front Neurosci 2018; 12:161. [PMID: 29593491 PMCID: PMC5861202 DOI: 10.3389/fnins.2018.00161] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 02/27/2018] [Indexed: 12/11/2022] Open
Abstract
Several lines of evidence place alpha-synuclein (aSyn) at the center of Parkinson's disease (PD) etiology, but it is still unclear why overexpression or mutated forms of this protein affect some neuronal populations more than others. Susceptible neuronal populations in PD, dopaminergic neurons of the substantia nigra pars compacta (SNpc) and the locus coeruleus (LC), are distinguished by relatively high cytoplasmic concentrations of dopamine and calcium ions. Here we review the evidence for the multi-hit hypothesis of neurodegeneration, including recent papers that demonstrate synergistic interactions between aSyn, calcium ions and dopamine that may lead to imbalanced protein turnover and selective susceptibility of these neurons. We conclude that decreasing the levels of any one of these toxicity mediators can be beneficial for the survival of SNpc and LC neurons, providing multiple opportunities for targeted drug interventions aimed at modifying the course of PD.
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Affiliation(s)
- Michael R Post
- Departments of Psychiatry and Neurology, New York State Psychiatric Institute, Columbia University Medical Center, New York, NY, United States
| | - Ori J Lieberman
- Departments of Psychiatry and Neurology, New York State Psychiatric Institute, Columbia University Medical Center, New York, NY, United States
| | - Eugene V Mosharov
- Departments of Psychiatry and Neurology, New York State Psychiatric Institute, Columbia University Medical Center, New York, NY, United States
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Choi SJ, Panhelainen A, Schmitz Y, Larsen KE, Kanter E, Wu M, Sulzer D, Mosharov EV. Changes in neuronal dopamine homeostasis following 1-methyl-4-phenylpyridinium (MPP+) exposure. J Biol Chem 2015; 290:6799-809. [PMID: 25596531 DOI: 10.1074/jbc.m114.631556] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
1-Methyl-4-phenylpyridinium (MPP(+)), the active metabolite of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, selectively kills dopaminergic neurons in vivo and in vitro via a variety of toxic mechanisms, including mitochondrial dysfunction, generation of peroxynitrite, induction of apoptosis, and oxidative stress due to disruption of vesicular dopamine (DA) storage. To investigate the effects of acute MPP(+) exposure on neuronal DA homeostasis, we measured stimulation-dependent DA release and non-exocytotic DA efflux from mouse striatal slices and extracellular, intracellular, and cytosolic DA (DAcyt) levels in cultured mouse ventral midbrain neurons. In acute striatal slices, MPP(+) exposure gradually decreased stimulation-dependent DA release, followed by massive DA efflux that was dependent on MPP(+) concentration, temperature, and DA uptake transporter activity. Similarly, in mouse midbrain neuronal cultures, MPP(+) depleted vesicular DA storage accompanied by an elevation of cytosolic and extracellular DA levels. In neuronal cell bodies, increased DAcyt was not due to transmitter leakage from synaptic vesicles but rather to competitive MPP(+)-dependent inhibition of monoamine oxidase activity. Accordingly, monoamine oxidase blockers pargyline and l-deprenyl had no effect on DAcyt levels in MPP(+)-treated cells and produced only a moderate effect on the survival of dopaminergic neurons treated with the toxin. In contrast, depletion of intracellular DA by blocking neurotransmitter synthesis resulted in ∼30% reduction of MPP(+)-mediated toxicity, whereas overexpression of VMAT2 completely rescued dopaminergic neurons. These results demonstrate the utility of comprehensive analysis of DA metabolism using various electrochemical methods and reveal the complexity of the effects of MPP(+) on neuronal DA homeostasis and neurotoxicity.
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Affiliation(s)
| | - Anne Panhelainen
- the Institute of Biotechnology, University of Helsinki, 00014 University of Helsinki, Finland
| | | | | | | | - Min Wu
- From the Departments of Neurology
| | - David Sulzer
- From the Departments of Neurology, Psychiatry, and Pharmacology, Columbia University Medical Center, New York, New York 10032 and
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Mosharov EV, Borgkvist A, Sulzer D. Presynaptic effects of levodopa and their possible role in dyskinesia. Mov Disord 2014; 30:45-53. [PMID: 25450307 DOI: 10.1002/mds.26103] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 10/28/2014] [Accepted: 11/01/2014] [Indexed: 12/25/2022] Open
Abstract
Levodopa replacement therapy has long provided the most effective treatment for Parkinson's disease (PD). We review how this dopamine (DA) precursor enhances dopaminergic transmission by providing a greater sphere of neurotransmitter influence as a result of the confluence of increased quantal size and decreased DA reuptake, as well as loading DA as a false transmitter into surviving serotonin neuron synaptic vesicles. We further review literature on how presynaptic dysregulation of DA release after l-dopa might trigger dyskinesias in PD patients.
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Affiliation(s)
- Eugene V Mosharov
- Departments of Neurology, Columbia University Medical Center, New York, New York, USA
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11
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Pifl C, Rajput A, Reither H, Blesa J, Cavada C, Obeso JA, Rajput AH, Hornykiewicz O. Is Parkinson's disease a vesicular dopamine storage disorder? Evidence from a study in isolated synaptic vesicles of human and nonhuman primate striatum. J Neurosci 2014; 34:8210-8. [PMID: 24920625 PMCID: PMC6608236 DOI: 10.1523/jneurosci.5456-13.2014] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 05/06/2014] [Accepted: 05/07/2014] [Indexed: 12/21/2022] Open
Abstract
The cause of degeneration of nigrostriatal dopamine (DA) neurons in idiopathic Parkinson's disease (PD) is still unknown. Intraneuronally, DA is largely confined to synaptic vesicles where it is protected from metabolic breakdown. In the cytoplasm, however, free DA can give rise to formation of cytotoxic free radicals. Normally, the concentration of cytoplasmic DA is kept at a minimum by continuous pumping activity of the vesicular monoamine transporter (VMAT)2. Defects in handling of cytosolic DA by VMAT2 increase levels of DA-generated oxy radicals ultimately resulting in degeneration of DAergic neurons. Here, we isolated for the first time, DA storage vesicles from the striatum of six autopsied brains of PD patients and four controls and measured several indices of vesicular DA storage mechanisms. We found that (1) vesicular uptake of DA and binding of the VMAT2-selective label [(3)H]dihydrotetrabenazine were profoundly reduced in PD by 87-90% and 71-80%, respectively; (2) after correcting for DA nerve terminal loss, DA uptake per VMAT2 transport site was significantly reduced in PD caudate and putamen by 53 and 55%, respectively; (3) the VMAT2 transport defect appeared specific for PD as it was not present in Macaca fascicularis (7 MPTP and 8 controls) with similar degree of MPTP-induced nigrostriatal neurodegeneration; and (4) DA efflux studies and measurements of acidification in the vesicular preparations suggest that the DA storage impairment was localized at the VMAT2 protein itself. We propose that this VMAT2 defect may be an early abnormality promoting mechanisms leading to nigrostriatal DA neuron death in PD.
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Affiliation(s)
- Christian Pifl
- Center for Brain Research, Medical University of Vienna, A-1090 Vienna, Austria,
| | - Alex Rajput
- Movement Disorders Program Saskatchewan, Royal University Hospital, University of Saskatchewan, Saskatoon, Saskatchewan, SK S7N OW8, Canada
| | - Harald Reither
- Center for Brain Research, Medical University of Vienna, A-1090 Vienna, Austria
| | - Javier Blesa
- Movement Disorders Group, Neurosciences Division, CIMA, and Department of Neurology and Neurosurgery, Clinica Universidad de Navarra, E31008 Pamplona, Spain, and
| | - Carmen Cavada
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, E28049 Madrid, Spain
| | - José A Obeso
- Movement Disorders Group, Neurosciences Division, CIMA, and Department of Neurology and Neurosurgery, Clinica Universidad de Navarra, E31008 Pamplona, Spain, and
| | - Ali H Rajput
- Movement Disorders Program Saskatchewan, Royal University Hospital, University of Saskatchewan, Saskatoon, Saskatchewan, SK S7N OW8, Canada
| | - Oleh Hornykiewicz
- Center for Brain Research, Medical University of Vienna, A-1090 Vienna, Austria
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Dardiotis E, Xiromerisiou G, Hadjichristodoulou C, Tsatsakis AM, Wilks MF, Hadjigeorgiou GM. The interplay between environmental and genetic factors in Parkinson's disease susceptibility: The evidence for pesticides. Toxicology 2013; 307:17-23. [DOI: 10.1016/j.tox.2012.12.016] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Revised: 12/23/2012] [Accepted: 12/25/2012] [Indexed: 11/29/2022]
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Wang CP, Sung WH, Wang CC, Tsai PY. Early recognition of pelvic floor dyssynergia and colorectal assessment in Parkinson's disease associated with bowel dysfunction. Colorectal Dis 2013; 15:e130-7. [PMID: 23320499 DOI: 10.1111/codi.12105] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Accepted: 10/14/2012] [Indexed: 12/14/2022]
Abstract
AIM Slow colonic transit time (CTT) and pelvic floor dyssynergia (PFD) are major contributors to constipation in patients with Parkinson's disease (PD). However, no symptom survey yet exists that effectively differentiates the contributing aetiologies. The significance of individual pelvic floor musculature behaviours and their relationship with colorectal dysmotility in constipated patients with PD are still controversial and need further clarification. We aimed to investigate how differentiated constipation-related symptoms of PD patients with constipation may identify constipation groupings and to register the pathophysiological features of the pelvic musculature. METHOD Our subjects undertook CTT, defaecography and the Knowles-Eccersley-Scott Symptom questionnaire. The pathological aetiologies were categorized as group 1 (slow CTT) and/or group 2 (puborectalis syndrome) and/or group 3 (pubococcygeus syndrome), in accordance with the CTT and defaecography results. RESULTS Constipation-related symptoms such as incomplete evacuation and defaecation difficulty yielded high post-test probabilities (81% and 88%, respectively) in groups 3 and 2, but a low post-test probability in group 1 (58%). Changes in the anorectal angle and perineum descent during straining were significantly correlated with CTT (r = 0.57 and r = 0.61, respectively) and with each other (r = 0.82). CONCLUSION Our findings that neural control of the puborectalis and pubococcygeus, along with colorectal peristalsis, were in a similar state of degeneration is key information that should assist physicians to instigate more effective management for colonic dysmotility or PFD.
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Affiliation(s)
- C-P Wang
- Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan
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14
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Mosharov EV, Sulzer D. Convergence of multiple hits that could underlie Parkinson’s disease. FUTURE NEUROLOGY 2009. [DOI: 10.2217/fnl.09.40] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
| | - David Sulzer
- Department of Neurology, Columbia University, NY, USA
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Ritz BR, Manthripragada AD, Costello S, Lincoln SJ, Farrer MJ, Cockburn M, Bronstein J. Dopamine transporter genetic variants and pesticides in Parkinson's disease. ENVIRONMENTAL HEALTH PERSPECTIVES 2009; 117:964-9. [PMID: 19590691 PMCID: PMC2702414 DOI: 10.1289/ehp.0800277] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Accepted: 02/22/2009] [Indexed: 05/20/2023]
Abstract
BACKGROUND Research suggests that independent and joint effects of genetic variability in the dopamine transporter (DAT) locus and pesticides may influence Parkinson's disease (PD) risk. METHODS In 324 incident PD patients and 334 population controls from our rural California case-control study, we genotyped rs2652510, rs2550956 (for the DAT 5' clades), and the 3' variable number of tandem repeats (VNTR). Using geographic information system methods, we determined residential exposure to agricultural maneb and paraquat applications. We also collected occupational pesticide use data. Employing logistic regression, we calculated odds ratios (ORs) for clade diplotypes, VNTR genotype, and number of susceptibility (A clade and 9-repeat) alleles and assessed susceptibility allele-pesticide interactions. RESULTS PD risk was increased separately in DAT A clade diplotype carriers [AA vs. BB: OR = 1.66; 95% confidence interval (CI), 1.08-2.57] and 3' VNTR 9/9 carriers (9/9 vs. 10/10: OR = 1.8; 95% CI, 0.96-3.57), and our data suggest a gene dosing effect. Importantly, high exposure to paraquat and maneb in carriers of one susceptibility allele increased PD risk 3-fold (OR = 2.99; 95% CI, 0.88-10.2), and in carriers of two or more alleles more than 4-fold (OR = 4.53; 95% CI, 1.70-12.1). We obtained similar results for occupational pesticide measures. DISCUSSION Using two independent pesticide measures, we a) replicated previously reported gene-environment interactions between DAT genetic variants and occupational pesticide exposure in men and b) overcame previous limitations of nonspecific pesticide measures and potential recall bias by employing state records and computer models to estimate residential pesticide exposure. CONCLUSION Our results suggest that DAT genetic variability and pesticide exposure interact to increase PD risk.
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Affiliation(s)
- Beate R Ritz
- Department of Epidemiology, Center for Occupational and Environmental Health, UCLA School of Public Health, University of California at Los Angeles, Los Angeles, California 90095-1772, USA.
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16
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Mosharov EV, Larsen KE, Kanter E, Phillips KA, Wilson K, Schmitz Y, Krantz DE, Kobayashi K, Edwards RH, Sulzer D. Interplay between cytosolic dopamine, calcium, and alpha-synuclein causes selective death of substantia nigra neurons. Neuron 2009; 62:218-29. [PMID: 19409267 DOI: 10.1016/j.neuron.2009.01.033] [Citation(s) in RCA: 397] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 01/19/2009] [Accepted: 01/24/2009] [Indexed: 11/19/2022]
Abstract
The basis for selective death of specific neuronal populations in neurodegenerative diseases remains unclear. Parkinson's disease (PD) is a synucleinopathy characterized by a preferential loss of dopaminergic neurons in the substantia nigra (SN), whereas neurons of the ventral tegmental area (VTA) are spared. Using intracellular patch electrochemistry to directly measure cytosolic dopamine (DA(cyt)) in cultured midbrain neurons, we confirm that elevated DA(cyt) and its metabolites are neurotoxic and that genetic and pharmacological interventions that decrease DA(cyt) provide neuroprotection. L-DOPA increased DA(cyt) in SN neurons to levels 2- to 3-fold higher than in VTA neurons, a response dependent on dihydropyridine-sensitive Ca2+ channels, resulting in greater susceptibility of SN neurons to L-DOPA-induced neurotoxicity. DA(cyt) was not altered by alpha-synuclein deletion, although dopaminergic neurons lacking alpha-synuclein were resistant to L-DOPA-induced cell death. Thus, an interaction between Ca2+, DA(cyt), and alpha-synuclein may underlie the susceptibility of SN neurons in PD, suggesting multiple therapeutic targets.
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Affiliation(s)
- Eugene V Mosharov
- Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA
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17
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Pifl C, Wolf A, Rebernik P, Reither H, Berger ML. Zinc regulates the dopamine transporter in a membrane potential and chloride dependent manner. Neuropharmacology 2008; 56:531-40. [PMID: 19000913 DOI: 10.1016/j.neuropharm.2008.10.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 10/13/2008] [Accepted: 10/14/2008] [Indexed: 11/28/2022]
Abstract
The dopamine transporter (DAT), a membrane protein specifically expressed by dopaminergic neurons and mediating the action of psychostimulants and dopaminergic neurotoxins, is regulated by Zn(2+) which directly interacts with the protein. Herein, we report a host-cell-specific direction of the Zn(2+) effect on wild type DAT. Whereas low mumolar Zn(2+) decreased dopamine uptake by DAT expressing HEK293 cells, it stimulated uptake by DAT expressing SK-N-MC cells. Inhibition or stimulation was lost in a DAT construct without the binding site for Zn(2+). Also reverse transport was differentially affected by Zn(2+), dependent on whether the DAT was expressed in HEK293 or SK-N-MC cells. Pre-treatment of DAT expressing cells with phorbol-12-myristate-13-acetate, an activator of protein kinase C, attenuated the inhibitory effect of Zn(2+) on uptake in HEK293 cells and increased the stimulatory effect in SK-N-MC cells. Patch-clamp experiments under non-voltage-clamped conditions revealed a significantly higher membrane potential of HEK293 than SK-N-MC cells and a reduced membrane potential after phorbol ester treatment. Lowering chloride in the uptake buffer switched the stimulatory effect of Zn(2+) in SK-N-MC cells to an inhibitory, whereas high potassium depolarization of HEK293 cells switched the inhibitory effect of Zn(2+) to a stimulatory one. This study represents the first evidence that DAT regulation by Zn(2+) is profoundly modulated by the membrane potential and chloride.
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Affiliation(s)
- Christian Pifl
- Center for Brain Research, Medical University of Vienna, Spitalgasse 4, A-1090 Vienna, Austria.
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18
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González-Hernández T, Barroso-Chinea P, De La Cruz Muros I, Del Mar Pérez-Delgado M, Rodríguez M. Expression of dopamine and vesicular monoamine transporters and differential vulnerability of mesostriatal dopaminergic neurons. J Comp Neurol 2004; 479:198-215. [PMID: 15452855 DOI: 10.1002/cne.20323] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Numerous studies suggest that the dopamine transporter (DAT), responsible for dopamine reuptake, may act as a vulnerability factor in the pathogenesis of Parkinson's disease (PD) and the vesicular monoamine transporter (VMAT2), responsible for its vesicular storage, as a neuroprotective factor. However, the relevance of each on the differential vulnerability of midbrain DA cells remains unknown. Here we studied the relationship between the expression pattern (mRNA and protein) of both transporters and the differential vulnerability of midbrain DA cells in a model of PD (intracerebroventricular injection of 6-OHDA in rats) and in monkey and human midbrain. Our results revealed that the expression patterns for VMAT2 mRNA and protein and DAT mRNA are similar, with the highest levels in the rostromedial region of substantia nigra (SNrm), followed by the caudoventral region of SN (SNcv), the ventral tegmental area and pigmented parabrabraquial nucleus (VTA/PBP), and finally the linear and interfascicular nuclei (Li/IF). In contrast, the expression of DAT protein in rats, monkeys, and humans followed a caudoventrolateral-to-rostrodorsomedial decreasing gradient (SNcv > SNrm > VTA/PBP > Li/IF), matching the degeneration profile observed after intracerebroventricular injection of 6-OHDA and in PD. In addition, DAT blockade made all midbrain DA cells equally resistant to 6-OHDA. These data indicate that DAT protein levels, but not DAT mRNA levels, are closely related to the differential vulnerability of midbrain DA cells and that this relationship is unaffected by the relative levels of VMAT2. Furthermore, the difference between DAT mRNA and protein profiles suggests internuclear differences in its posttransductional regulation.
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Affiliation(s)
- Tomás González-Hernández
- Departamento de Anatomía, Facultad de Medicina, Universidad de La Laguna, La Laguna, Tenerife 38320, Spain.
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19
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Tillerson JL, Miller GW. Grid performance test to measure behavioral impairment in the MPTP-treated-mouse model of parkinsonism. J Neurosci Methods 2003; 123:189-200. [PMID: 12606067 DOI: 10.1016/s0165-0270(02)00360-6] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Behavioral impairments in mice following administration of the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) require large depletions in striatal dopamine content and are often transient. In this paper, we describe a simple and inexpensive test that measures long-term behavioral deficits in mice treated with moderate doses of MPTP. These measures are significantly correlated with the loss of striatal dopamine and immunoreactivity of the dopamine transporter, vesicular monoamine transporter and tyrosine hydroxylase. In addition, behavioral impairments on the measures were reversed following L-DOPA administration. Employment of this test will allow for more efficacious use of mice in PD research, as well as provide more sensitive measures of behavioral improvement following potential therapeutic or neuroprotective interventions.
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20
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Methamphetamine-induced degeneration of dopaminergic neurons involves autophagy and upregulation of dopamine synthesis. J Neurosci 2002. [PMID: 12388602 DOI: 10.1523/jneurosci.22-20-08951.2002] [Citation(s) in RCA: 236] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Methamphetamine (METH) selectively injures the neurites of dopamine (DA) neurons, generally without inducing cell death. It has been proposed that METH-induced redistribution of DA from the vesicular storage pool to the cytoplasm, where DA can oxidize to produce quinones and additional reactive oxygen species, may account for this selective neurotoxicity. To test this hypothesis, we used mice heterozygous (+/-) or homozygous (-/-) for the brain vesicular monoamine uptake transporter VMAT2, which mediates the accumulation of cytosolic DA into synaptic vesicles. In postnatal ventral midbrain neuronal cultures derived from these mice, METH-induced degeneration of DA neurites and accumulation of oxyradicals, including metabolites of oxidized DA, varied inversely with VMAT2 expression. METH administration also promoted the synthesis of DA via upregulation of tyrosine hydroxylase activity, resulting in an elevation of cytosolic DA even in the absence of vesicular sequestration. Electron microscopy and fluorescent labeling confirmed that METH promoted the formation of autophagic granules, particularly in neuronal varicosities and, ultimately, within cell bodies of dopaminergic neurons. Therefore, we propose that METH neurotoxicity results from the induction of a specific cellular pathway that is activated when DA cannot be effectively sequestered in synaptic vesicles, thereby producing oxyradical stress, autophagy, and neurite degeneration.
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Klimek V, Schenck JE, Han H, Stockmeier CA, Ordway GA. Dopaminergic abnormalities in amygdaloid nuclei in major depression: a postmortem study. Biol Psychiatry 2002; 52:740-8. [PMID: 12372665 DOI: 10.1016/s0006-3223(02)01383-5] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND A deficiency of mesolimbic dopamine (DA) is a leading candidate for the etiology of certain symptoms of depression (e.g., anhedonia and loss of motivation). Here we show amounts of dopaminergic proteins in the amygdala, a key brain structure involved in the integration of emotions and stress, in subjects with major depression and in psychiatrically normal control subjects. METHODS The specific binding of [(125)I]RTI 55 to the DA transporter, [(3)H]SCH 23390 to the D1 receptor and [(125)I]epidepride to D2/D3 receptors were measured in the right amygdaloid complex in postmortem brains from 11 subjects with major depression and 11 matched control subjects. RESULTS The binding of [(125)I]RTI 55 to DA transporter was significantly lower in the basal and central amygdaloid nuclei, whereas the binding of [(125)I]epidepride to D2/D3 receptors was significantly higher in the basal, central, and lateral amygdaloid nuclei in major depression compared with control subjects. No difference in the binding of [(3)H]SCH 23390 to D1 receptors was observed. CONCLUSIONS Given that DA depletion in rats can induce a reduction in the DA transporter and an upregulation of D2/D3 receptors, our data are consistent with the hypothesis that major depression is associated with a deficiency of mesolimbic DA.
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Affiliation(s)
- Violetta Klimek
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson 39216, USA
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22
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Dryhurst G. Are dopamine, norepinephrine, and serotonin precursors of biologically reactive intermediates involved in the pathogenesis of neurodegenerative brain disorders? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2002; 500:373-96. [PMID: 11764972 DOI: 10.1007/978-1-4615-0667-6_61] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Affiliation(s)
- G Dryhurst
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman 73019, USA
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23
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Zheng S, Chou AH, Jimenez AL, Khodadadi O, Son S, Melega WP, Howard BD. The fetal and neonatal brain protein neuronatin protects PC12 cells against certain types of toxic insult. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2002; 136:101-10. [PMID: 12101027 DOI: 10.1016/s0165-3806(02)00348-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The protein neuronatin is expressed in the nervous system of the fetus and neonate at a much higher level than in the adult. Its function is unknown. As a result of variable splicing, neuronatin mRNA exists in two forms, alpha and beta. Wild type PC12 cells express neuronatin-alpha. We have isolated a PC12 variant, called 1.9, that retains many of the neuron-like properties of wild type PC12 cells, but it does not express neuronatin and it exhibits markedly increased sensitivity to the toxic effects of nigericin, rotenone and valinomycin. Pretreatment of the 1.9 cells with alpha-methyltyrosine, which inhibits dopamine synthesis, had little effect on the cells' sensitivity to nigericin, rotenone or valinomycin indicating that dopamine-induced oxidative stress was not involved in the toxicity of these compounds. However, flattened cell subvariants of the 1.9 cells, which do not have any neuron-specific characteristics, did not exhibit increased sensitivity to nigericin indicating that some neuronal characteristic of the 1.9 cells contributed to the toxicity of nigericin. After the neuronatin-beta gene was transfected into and expressed in the 1.9 cells, they regained wild type PC12 levels of resistance to nigericin, rotenone and valinomycin. These studies suggest that the function of neuronatin during development could be to protect developing cells from toxic insult occurring during that period.
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Affiliation(s)
- Shuang Zheng
- Department of Biological Chemistry, School of Medicine, University of California, Los Angeles, 650 Charles Young Drive, Los Angeles, CA 90095, USA
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24
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Takatsu H, Wada H, Maekawa N, Takemura M, Saito K, Fujiwara H. Significant reduction of 125 I-meta-iodobenzylguanidine accumulation directly caused by 1-methyl-4-phenyl-1,2,3,6-tetrahydroxypyridine, a toxic agent for inducing experimental Parkinson's disease. Nucl Med Commun 2002; 23:161-6. [PMID: 11891470 DOI: 10.1097/00006231-200202000-00008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A significant reduction of cardiac 123I-meta-iodobenzylguanidine (MIBG) accumulation has been reported in patients with idiopathic Parkinson's disease. However, it is unclear whether this reduction in cardiac sympathetic nerve is caused primarily or secondarily to the degeneration of sympathetic nerve centres which occurs in Parkinson's disease. Therefore, we examined neuronal 125I-MIBG accumulation in mice hearts of an experimental Parkinson's disease model and in sympathetic cells without any neuronal innervation. Cardiac accumulation of 125I-MIBG was determined 4h after intravenous injection of 125I-MIBG in mice pretreated with 1-methyl-4-phenyl-1,2,3,6-tetrahydroxypyridine (MPTP), an inducer of Parkinson's disease. In an in vitro study, uptake of 125I-MIBG was determined in a cultured pheochromocytoma cell line (PC-12), which was pretreated with MPTP. MPTP reduced MIBG accumulation mainly in its neuronal component of mice hearts, suggesting that MPTP impairs cardiac sympathetic nerves to uptake MIBG. Application of MPTP also caused near-complete blockade of 125I-MIBG accumulation in PC-12 cells. In the experimental PD models, it was shown that neuronal accumulation of MIBG was impaired by the direct action of MPTP to the sympathetic cells. These findings support the idea that cardiac sympathetic nerves are primarily impaired in Parkinson's disease despite the presence or absence of systemic autonomic failure.
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Affiliation(s)
- H Takatsu
- First Department of Internal Medicine, Gifu Municipal Hospital, Japan.
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25
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Abstract
The release of neurotransmitter from neurons represents one of the pivotal events in synaptic transmission. Neurotransmitters are released from synaptic vesicles in presynaptic neurons in response to neural activity, diffuse across the synaptic cleft, and bind specific receptors in order to bring about changes in postsynaptic neurons. Some of the molecular processes that govern neurotransmitter release are now becoming better understood. The steps involved can be broken down into two partially overlapping presynaptic cycles, the neurotransmitter cycle and the synaptic vesicle cycle. The neurotransmitter cycle involves transmitter biosynthesis, storage, reuptake, and degradation. The synaptic vesicle cycle involves targeting to the nerve terminal, docking, fusion, endocytosis, and recycling. Biochemical and structural studies have yielded important insight into our understanding of each of these two cycles. Further, both pharmacological and genetic interference with either of these cycles results in profound alterations in synaptic transmission and behavior, demonstrating the crucial role of neurotransmitter release.
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Affiliation(s)
- E A Fon
- Centre for Neuronal Survival, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec H3A 2B4, Canada.
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26
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Tejerizo-López L, Sánchez-Sánchez M, Tejerizo-García A, García-Robles M, Leiva A, Morán E, Corredera F, Pérez-Escanilla J, Benavente J. Enfermedad de Parkinson y embarazo. CLINICA E INVESTIGACION EN GINECOLOGIA Y OBSTETRICIA 2001. [DOI: 10.1016/s0210-573x(01)77125-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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27
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Bywood PT, Johnson SM. Differential vulnerabilities of substantia nigra catecholamine neurons to excitatory amino acid-induced degeneration in rat midbrain slices. Exp Neurol 2000; 162:180-8. [PMID: 10716898 DOI: 10.1006/exnr.2000.7310] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although differential vulnerability in different regions of the central nervous system is a characteristic feature of neurodegenerative disorders in vivo, its cellular basis is not well understood. In the present study we investigated whether catecholamine neurons in different regions of the substantia nigra (SN) are differentially vulnerable to excitatory amino acid-induced damage in a midbrain slice preparation. Rats were anesthetized by halothane inhalation and killed, the brain was rapidly removed, and 300-microm-thick midbrain slices were cut horizontally on a vibratome. The slices were incubated at 35 degrees C for 2 h in saline buffer containing either kainic acid (KA) or N-methyl-d-aspartate (NMDA) (10-50 microM). They were then fixed and cut into 30-microm sections that were coplanar with the horizontal slice. Individual catecholamine neurons were identified in these thin sections using an antibody to tyrosine hydroxylase coupled to diaminobenzidine. Catecholaminergic neurons in the dorsal and ventral tiers of the SN were readily identified by reference to an atlas of the distribution of catecholamine neurons in the horizontal plane. Using dendritic degeneration as a sensitive index of damage, and submaximal concentrations of KA and NMDA, we found that catecholamine neurons in the dorsal tier were more vulnerable than those in the ventral tier. For example, KA (10 microM) caused a significant reduction in the proportion of neurons with dendrites in the dorsal tier (from 60 to 34%) without altering the dendritic arbor of ventral tier neurons. After treatment with 50 microM KA, only 11% of dorsal tier neurons retained any dendrites while 45% of ventral tier neurons retained their dendrites. These differences were statistically significant (P<0.001). A similar differential vulnerability was apparent in slices treated with NMDA; neurons in the dorsal tier lost dendrites before detectable damage in the ventral tier. An understanding of the comparative anatomical, neurochemical, and physiological properties of vulnerable (dorsal tier) and resistant (ventral tier) catecholamine neurons in rat SN may provide significant insights into the mechanisms and treatment of neurodegenerative disorders involving catecholamine neurons.
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Affiliation(s)
- P T Bywood
- Department of Clinical Pharmacology, Flinders University of South Australia, Adelaide, 5001, Australia
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28
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Abstract
The plasma membrane dopamine transporter (DAT) and the vesicular monoamine transporter (VMAT2) are essential for normal dopamine neurotransmission. DAT terminates the actions of dopamine by rapidly removing dopamine from the synapse, whereas VMAT2 loads cytoplasmic dopamine into vesicles for storage and subsequent release. Recent data suggest that perturbation of the tightly regulated balance between these two transporters predisposes the neurone to damage by a variety of insults. Most notable is the selective degeneration of DAT- and VMAT2-expressing dopamine nerve terminals in the striatum thought to underlie Parkinson's disease. DAT and VMAT2 expression can predict the selective vulnerability of neuronal populations, which suggests that therapeutic strategies aimed at altering DAT and VMAT2 function could have significant benefits in a variety of disorders.
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Affiliation(s)
- G W Miller
- College of Pharmacy, University of Texas, Austin, TX 78712, USA.
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29
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Miller GW, Erickson JD, Perez JT, Penland SN, Mash DC, Rye DB, Levey AI. Immunochemical analysis of vesicular monoamine transporter (VMAT2) protein in Parkinson's disease. Exp Neurol 1999; 156:138-48. [PMID: 10192785 DOI: 10.1006/exnr.1998.7008] [Citation(s) in RCA: 153] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The vesicular monoamine transporter (VMAT2) has been suggested to be an excellent marker of presynaptic dopaminergic nerve terminals in the striatum of Parkinson's disease patients based on its high level of expression and insensitivity to drugs used to treat the disease. Previous in vivo imaging and postmortem binding studies have detected a loss in striatal VMAT2 binding in Parkinson's diseased (PD) brain; however, these techniques have poor spatial resolution and may suffer from nonspecific binding of some ligands. In this study, we use novel polyclonal antibodies to distinct regions of human VMAT2 to quantify and localize the protein. Western blot analysis demonstrated marked reductions in VMAT2 immunoreactivity in putamen, caudate, and nucleus accumbens of PD brain compared to control cases. Immunohistochemistry revealed VMAT2 immunoreactive fibers and puncta that were dense throughout the striatum of control brains, but which were drastically reduced in putamen of PD brains. In PD brains the caudate showed a significant degree of sparing along the border of the lateral ventricle and the nucleus accumbens was relatively preserved. The distribution of VMAT2 in striatum and its loss in PD paralleled that of the dopamine transporter (DAT), a phenotypic marker of dopamine neurons. Thus, immunochemical analysis of VMAT2 protein provides novel and sensitive means for localizing and quantifying VMAT2 protein and nigrostriatal dopamine terminals in PD. Furthermore, the relative expression of VMAT2 compared to that of DAT may predict the differential vulnerability of dopamine neurons in PD.
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Affiliation(s)
- G W Miller
- Department of Neurology, Emory University School of Medicine, Atlanta, Georgia, 30322, USA
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30
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Willis GL, Armstrong SM. Orphan neurones and amine excess: the functional neuropathology of Parkinsonism and neuropsychiatric disease. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 1998; 27:177-242. [PMID: 9729369 DOI: 10.1016/s0165-0173(98)00013-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The aetiology and treatment of Parkinsonism is currently conceptualised within a dopamine (DA) deficiency-repletion framework. Loss of striatal DA is thought to cause motor impairment of which tremor, bradykinaesia and rigidity are prominent features. Repletion of deficient DA should at least minimise parkinsonian signs and symptoms. In Section 2, based on extensive pre-clinical and clinical findings, the instability of this approach to Parkinsonism is scrutinised as the existing negative findings challenging the DA deficiency hypothesis are reviewed and reinterpreted. In Section 3 it is suggested that Parkinsonism is due to a DA excess far from the striatum in the area of the posterior lateral hypothalamus (PLH) and the substantia nigra (SN). This unique area, around the diencephalon/mesencephalon border (DCMCB), is packed with many ascending and descending fibres which undergo functional transformation during degeneration, collectively labelled 'orphan neurones'. These malformed cells remain functional resulting in pathological release of transmitter and perpetual neurotoxicity. Orphan neurone formation is commonly observed in the PLH of animals and in man exhibiting Parkinsonism. The mechanism by which orphan neurones impair motor function is analogous to that seen in the diseased human heart. From this perspective, to conceptualise orphan neurones at the DCMCB as 'Time bombs in the brain' is neither fanciful nor unrealistic [E.M. Stricker, M.J. Zigmond, Comments on effects of nigro-striatal dopamine lesions, Appetite 5 (1984) 266-267] as the DA excess phenomenon demands a different therapeutic approach for the management of Parkinsonism. In Section 4 the focus is on this novel concept of treatment strategies by concentrating on non-invasive, pharmacological and surgical modification of functional orphan neurones as they affect adjacent systems. The Orphan neurone/DA excess hypothesis permits a more comprehensive and defendable interpretation of the interrelationship between Parkinsonism and schizophrenia and other related disorders.
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Affiliation(s)
- G L Willis
- The Bronowski Institute of Behavioural Neuroscience, Coliban Medical Centre, Kyneton, Victoria 3444, Australia
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31
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Vaccari A, Saba PL, Mocci I, Ruiu S. Is increased neurotoxicity a burden of the ageing brain? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1997; 429:221-34. [PMID: 9413577 DOI: 10.1007/978-1-4757-9551-6_16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- A Vaccari
- Department of Neuroscience B. Brodie, Neurotoxicology Unit, Cagliari, Italy
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32
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Liu Y, Edwards RH. Differential localization of vesicular acetylcholine and monoamine transporters in PC12 cells but not CHO cells. J Cell Biol 1997; 139:907-16. [PMID: 9362509 PMCID: PMC2139959 DOI: 10.1083/jcb.139.4.907] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Previous studies have indicated that neuro-endocrine cells store monoamines and acetylcholine (ACh) in different secretory vesicles, suggesting that the transport proteins responsible for packaging these neurotransmitters sort to distinct vesicular compartments. Molecular cloning has recently demonstrated that the vesicular transporters for monoamines and ACh show strong sequence similarity, and studies of the vesicular monoamine transporters (VMATs) indicate preferential localization to large dense core vesicles (LDCVs) rather than synaptic-like microvesicles (SLMVs) in rat pheochromocytoma PC12 cells. We now report the localization of the closely related vesicular ACh transporter (VAChT). In PC12 cells, VAChT differs from the VMATs by immunofluorescence and fractionates almost exclusively to SLMVs and endosomes by equilibrium sedimentation. Immunoisolation further demonstrates colocalization with synaptophysin on SLMVs as well as other compartments. However, small amounts of VAChT also occur on LDCVs. Thus, VAChT differs in localization from the VMATs, which sort predominantly to LDCVs. In addition, we demonstrate ACh transport activity in stable PC12 transformants overexpressing VAChT. Since previous work has suggested that VAChT expression confers little if any transport activity in non-neural cells, we also determined its localization in transfected CHO fibroblasts. In CHO cells, VAChT localizes to the same endosomal compartment as the VMATs by immunofluorescence, density gradient fractionation, and immunoisolation with an antibody to the transferrin receptor. We have also detected ACh transport activity in the transfected CHO cells, indicating that localization to SLMVs is not required for function. In summary, VAChT differs in localization from the VMATs in PC12 cells but not CHO cells.
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Affiliation(s)
- Y Liu
- Department of Neurology, University of California at San Francisco School of Medicine, San Francisco, California 94143, USA
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33
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The dopamine transporter: comparative ultrastructure of dopaminergic axons in limbic and motor compartments of the nucleus accumbens. J Neurosci 1997. [PMID: 9278525 DOI: 10.1523/jneurosci.17-18-06899.1997] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The dopamine transporter (DAT) regulates extracellular dopamine concentrations, transports neurotoxins, and acts as a substrate for cocaine reinforcement. These functions are known to differ in the limbic-associated shell and motor-associated core compartments of the nucleus accumbens (NAc). Previous studies have shown differential expression of DAT in the NAc shell and core but were limited in resolution to the regional level. Thus, it is not known whether there are differences in the amount, subcellular localization, or plasmalemmal targeting of DAT within individual dopaminergic axons in the two regions. We used high-resolution electron microscopic immunocytochemistry to investigate these possibilities. We show that in both the shell and core, DAT immunogold labeling is present in tyrosine hydroxylase-immunoreactive varicose axons that form symmetric synapses. Within these labeled axons, most DAT gold particles are located on extrasynaptic plasma membranes, but some are associated with intracellular membranes. Dopaminergic axons in the shell contain lower mean densities of both total DAT gold particles (per square micron) and plasmalemmal DAT gold particles (per micron) than those in the core. Within labeled axons in the NAc shell and core, however, there are no detectable differences in the subcellullar distribution of DAT or the percentage of total DAT gold particles that are located on plasma membranes. These studies are the first to examine and compare the subcellular localization of DAT in the NAc shell and core. As a result, they identify intrinsic, cell-specific differences in the expression of DAT within dopaminergic axons in these functionally distinct striatal compartments.
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Lu W, Wolf ME. Expression of dopamine transporter and vesicular monoamine transporter 2 mRNAs in rat midbrain after repeated amphetamine administration. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1997; 49:137-48. [PMID: 9387873 DOI: 10.1016/s0169-328x(97)00136-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The dopamine transporter (DAT) in pre-synaptic membranes and the vesicular monoamine transporter 2 (VMAT2) in membranes of synaptic vesicles are involved in mediating the acute effects of amphetamine on dopamine transmission. Therefore, using a quantitative method of in situ hybridization and computerized image analysis, the expression of DAT and VMAT2 mRNAs was examined in rats treated for 5 days with amphetamine and killed 3 or 14 days after the last injection. We examined ventral tegmental area (VTA), substantia nigra (SN) and the transitional zone between VTA and SN. Each of these regions was further subdivided into rostral, intermediate and caudal portions. In control rats, autoradiographs revealed a gradient of both DAT and VMAT2 mRNA levels, decreasing gradually from rostral to caudal rat midbrain. After 3 days of withdrawal, a significant increase in DAT mRNA levels was found in rostral portions of VTA (117.9 + 5.8% of control group), SN (116.5 + 4.5%) and the transitional zone (119.6 + 5.6%) and in the intermediate portion of SN (113.5 + 4.3%). VMAT2 mRNA was significantly increased only in rostral and intermediate portions of the transitional zone (120.9 + 4.8 and 113.6 + 4.1%). After 14 days of withdrawal, there was a trend towards increased DAT mRNA levels in intermediate-caudal portions of midbrain, but a statistically significant increase was observed only in the intermediate portion of VTA (120.2 + 7.9%). No changes in VMAT2 mRNA levels were found. Thus, repeated amphetamine administration exerts modest and regionally selective effects on DAT and VMAT2 mRNA expression in subpopulations of midbrain dopamine neurons.
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Affiliation(s)
- W Lu
- Department of Neuroscience, Finch University of Health Science/Chicago Medical School, North Chicago, IL 60064, USA
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35
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Abstract
The vesicular monoamine transporter is a specific presynaptic protein involved in the transport of monoamines from the cytosol to storage vesicles of monoaminergic nerve terminals. Recently, radioligands for this transporter have been developed and utilized for in vivo positron emission tomographic (PET) imaging of monoaminergic nerve terminals in the human brain. In this review, the characteristics of vesicular transport and storage that provided the impetus for development of these radioligands are presented and discussed.
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Affiliation(s)
- M R Kilbourn
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor 48109, USA
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36
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Jaber M, Jones S, Giros B, Caron MG. The dopamine transporter: a crucial component regulating dopamine transmission. Mov Disord 1997; 12:629-33. [PMID: 9380041 DOI: 10.1002/mds.870120502] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The dopamine system is implicated in the control of locomotion, cognition, and endocrine function. The relative contribution of the various dopamine-related components is not well established mainly because drugs that target the dopaminergic system often lack selectivity. The in vivo gene inactivation procedure, or knockout, enables the creation of new strains of mice lacking a specific gene. This technique has been applied recently to inactivate the expression of the plasma membrane dopamine transporter. Here we summarize the main findings obtained with these transgenic mice carrying this "genetic defect," leading to a better understanding of the relative contribution of the dopamine transporter regarding locomotor activity, regulation of the expression of peptides under the control of dopaminergic activity, and responses to various drugs targeting the dopamine system. Our results establish not only the central importance of the transporter as the key element controlling dopamine levels in the brain, but also its role as an obligatory target for the behavioral and biochemical action of amphetamine and cocaine. In addition, the genetically altered mice offer a unique model to test the specificity and selectivity of dopamine transporter-acting drugs and may provide important new concepts related to the clinical and social implications of conditions such as Parkinson's disease, schizophrenia, and drug addiction.
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Affiliation(s)
- M Jaber
- Howard Hughes Medical Institute Laboratories, Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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37
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Immunogold localization of the dopamine transporter: an ultrastructural study of the rat ventral tegmental area. J Neurosci 1997. [PMID: 9204909 DOI: 10.1523/jneurosci.17-14-05255.1997] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The dopamine transporter (DAT) plays an important role in the plasmalemmal reuptake of dopamine and, thus, in the termination of normal dopaminergic neurotransmission. DAT is also a major binding site for cocaine and other stimulants, the psychoactive effects of which are associated primarily with the inhibition of dopamine reuptake within mesocorticolimbic dopaminergic neurons. We used electron microscopy with an anti-peptide antiserum directed against the N-terminal domain of DAT to determine the subcellular localization of this transporter in the rat ventral tegmental area (VTA), the region that contains the cell bodies and dendrites of these dopaminergic neurons. We show that in the VTA, almost 95% of the DAT immunogold-labeled profiles are neuronal perikarya and dendrites, and the remainder are unmyelinated axons. Within perikarya and large proximal dendrites, almost all of the DAT immunogold particles are associated with intracellular membranes, including saccules of Golgi and cytoplasmic tubulovesicles. In contrast, within medium- to small-diameter dendrites and unmyelinated axons, most of the DAT gold particles are located on plasma membranes. In dually labeled tissue, peroxidase reaction product for the catecholamine-synthesizing enzyme tyrosine hydroxylase is present in DAT-immunoreactive profiles. These findings suggest that intermediate and distal dendrites are both the primary sites of dopamine reuptake and the principal targets of cocaine and related psychostimulants within dopaminergic neurons in the VTA.
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38
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Immunogold localization of the dopamine transporter: an ultrastructural study of the rat ventral tegmental area. J Neurosci 1997. [PMID: 9151720 DOI: 10.1523/jneurosci.17-11-04037.1997] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The dopamine transporter (DAT) plays an important role in the plasmalemmal reuptake of dopamine and, thus, in the termination of normal dopaminergic neurotransmission. DAT is also a major binding site for cocaine and other stimulants, the psychoactive effects of which are associated primarily with the inhibition of dopamine reuptake within mesocorticolimbic dopaminergic neurons. We used electron microscopy with an anti-peptide antiserum directed against the N-terminal domain of DAT to determine the subcellular localization of this transporter in the rat ventral tegmental area (VTA), the region that contains the cell bodies and dendrites of these dopaminergic neurons. We show that in the VTA, almost 95% of the DAT immunogold-labeled profiles are neuronal perikarya and dendrites, and the remainder are unmyelinated axons. Within perikarya and large proximal dendrites, almost all of the DAT immunogold particles are associated with intracellular membranes, including saccules of Golgi and cytoplasmic tubulovesicles. In contrast, within medium- to small-diameter dendrites and unmyelinated axons, most of the DAT gold particles are located on plasma membranes. In dually labeled tissue, peroxidase reaction product for the catecholamine-synthesizing enzyme tyrosine hydroxylase is present in DAT-immunoreactive profiles. These findings suggest that intermediate and distal dendrites are both the primary sites of dopamine reuptake and the principal targets of cocaine and related psychostimulants within dopaminergic neurons in the VTA.
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39
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Abstract
Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem of vertebrates. Glycine is accumulated into synaptic vesicles by a proton-coupled transport system and released to the synaptic cleft after depolarization of the presynaptic terminal. The inhibitory action of glycine is mediated by pentameric glycine receptors (GlyR) that belong to the ligand-gated ion channel superfamily. The synaptic action of glycine is terminated by two sodium- and chloride-coupled transporters, GLYT1 and GLYT2, located in the glial plasma membrane and in the presynaptic terminals, respectively. Dysfunction of inhibitory glycinergic neurotransmission is associated with several forms of inherited mammalian myoclonus. In addition, glycine could participate in excitatory neurotransmission by modulating the activity of the NMDA subtype of glutamate receptor. In this article, we discuss recent progress in our understanding of the molecular mechanisms that underlie the physiology and pathology of glycinergic neurotransmission.
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Affiliation(s)
- F Zafra
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Universidad Autónoma de Madrid, Spain
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40
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Nirenberg MJ, Chan J, Liu Y, Edwards RH, Pickel VM. Vesicular monoamine transporter-2: immunogold localization in striatal axons and terminals. Synapse 1997; 26:194-8. [PMID: 9131778 DOI: 10.1002/(sici)1098-2396(199706)26:2<194::aid-syn10>3.0.co;2-y] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The vesicular monoamine transporter-2 (VMAT2) mediates the reserpine-sensitive neuronal uptake of monoamines into vesicles and other intracellular organelles. Accordingly, this transporter is expressed at high levels in regions that contain a dense monoamine innervation, such as the rat dorsolateral striatum. We used ultrastructural immunocytochemistry in this region to show that immunogold labeling for VMAT2 is present in varicose axonal processes, many of which also contain the catecholamine-synthesizing enzyme tyrosine-hydroxylase. Within these mainly dopaminergic processes, VMAT2 was associated with small synaptic vesicles (SSVs) and more rarely with large dense-core vesicles or tubulovesicles. These findings suggest that SSVs are the major organelles involved in the storage and release of dopamine in the dorsolateral striatum.
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Affiliation(s)
- M J Nirenberg
- Department of Neurology and Neuroscience, Cornell University Medical College, New York, New York 10021, USA.
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41
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Ultrastructural localization of the vesicular monoamine transporter-2 in midbrain dopaminergic neurons: potential sites for somatodendritic storage and release of dopamine. J Neurosci 1996. [PMID: 8753875 DOI: 10.1523/jneurosci.16-13-04135.1996] [Citation(s) in RCA: 166] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Midbrain dopaminergic neurons are known to release dopamine from somata and/or dendrites located in the substantia nigra (SN) and the ventral tegmental area (VTA). There is considerable controversy, however, about the subcellular sites for somatodendritic dopamine storage in these regions. In the present study, we used dual-labeling electron microscopic immunocytochemistry to localize the vesicular monoamine transporter-2 (VMAT2), a novel marker for sites of intracellular monoamine storage, within identified dopaminergic (tyrosine hydroxylase-containing) neurons in the rat SN and VTA. In dopaminergic perikarya, immunogold labeling for VMAT2 was localized to the Golgi apparatus, tubulovesicles that resembled smooth endoplasmic reticulum (SER), and the limiting membranes of multivesicular bodies. In dopaminergic dendrites, VMAT2 was extensively localized to tubulovesicles that resembled saccules of SER, and less frequently localized to isolated small synaptic vesicles (SSVs) or large dense-core vesicles (DCVs). In rare cases, VMAT2-immunoreactive SSVs were clustered within the cytoplasm of an SN or a VTA dendrite. Dopaminergic dendrites in the VTA contained a significantly higher number of immunogold particles for VMAT2 per unit than those in the SN. Together, these observations support the proposal that dopamine is stored in and may be released from dendritic SSVs and DCVs, but suggest that the SER is the major site of dopamine storage within midbrain dopaminergic neurons. In addition, they provide new evidence that dopaminergic dendrites in the VTA may have greater potential for reserpine-sensitive storage and release of dopamine than those in the SN.
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42
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Kilbourn M, Frey K. Striatal concentrations of vesicular monoamine transporters are identical in MPTP-sensitive (C57BL/6) and -insensitive (CD-1) mouse strains. Eur J Pharmacol 1996; 307:227-32. [PMID: 8832225 DOI: 10.1016/0014-2999(96)00252-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Sensitivity to the neurotoxic actions of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) varies greatly among strains of mice. The numbers of vesicular monoamine transporters was examined in various brain regions of MPTP-sensitive (C57BL/6) and MPTP-insensitive (CD-1) mouse strains. In vivo radioligand binding to the vesicular monoamine transporter was studied using [11C]methoxytetrabenazine, and in vitro Bmax values determined using [3H]dihydrotetrabenazine autoradiography. Using either technique, no significant differences between the two strains were seen in the striatal binding of these radioligands to the vesicular monoamine transporter. The in vivo binding of radioligands to this transporter in the striatum was also not gender dependent. The relative resistance of CD-1 mice to the neurotoxic effects of peripheral MPTP administration thus does not appear to be a result of enhanced protection by higher levels of vesicular storage in dopaminergic neurons of the striatum.
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Affiliation(s)
- M Kilbourn
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor 48109, USA
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43
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Ansari AA, Sundstrom JB. TRANSPLANTATION OF FETAL TISSUES. Immunol Allergy Clin North Am 1996. [DOI: 10.1016/s0889-8561(05)70250-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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44
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TRANSPLANTATION OF FETAL TISSUES. Radiol Clin North Am 1996. [DOI: 10.1016/s0033-8389(22)00215-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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45
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Nirenberg MJ, Liu Y, Peter D, Edwards RH, Pickel VM. The vesicular monoamine transporter 2 is present in small synaptic vesicles and preferentially localizes to large dense core vesicles in rat solitary tract nuclei. Proc Natl Acad Sci U S A 1995; 92:8773-7. [PMID: 7568015 PMCID: PMC41049 DOI: 10.1073/pnas.92.19.8773] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
In central neurons, monamine neurotransmitters are taken up and stored within two distinct classes of regulated secretory vesicles: small synaptic vesicles and large dense core vesicles (DCVs). Biochemical and pharmacological evidence has shown that this uptake is mediated by specific vesicular monamine transporters (VMATs). Recent molecular cloning techniques have identified the vesicular monoamine transporter (VMAT2) that is expressed in brain. This transporter determines the sites of intracellular storage of monoamines and has been implicated in both the modulation of normal monoaminergic neurotransmission and the pathogenesis of related neuropsychiatric disease. We used an antiserum against VMAT2 to examine its ultrastructural distribution in rat solitary tract nuclei, a region that contains a dense and heterogeneous population of monoaminergic neurons. We find that both immunoperoxidase and immunogold labeling for VMAT2 localize to DCVs and small synaptic vesicles in axon terminals, the trans-Golgi network of neuronal perikarya, tubulovesicles of smooth endoplasmic reticulum, and potential sites of vesicular membrane recycling. In axon terminals, immunogold labeling for VMAT2 was preferentially associated with DCVs at sites distant from typical synaptic junctions. The results provide direct evidence that a single VMAT is expressed in two morphologically distinct types of regulated secretory vesicles in central monoaminergic neurons.
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Affiliation(s)
- M J Nirenberg
- Department of Neurology and Neuroscience, Cornell University Medical College, New York, NY 10021, USA
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46
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Heo JH, Kim DG, Bahng HR, Kim JS. Dimethylthiourea prevents MPTP-induced decrease in [3H]dopamine uptake in rat striatal slices. Brain Res 1995; 671:321-4. [PMID: 7743223 DOI: 10.1016/0006-8993(94)01373-p] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To determine whether oxygen free radicals are involved in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity, the effect of dimethylthiourea (DMTU), an effective hydroxyl radical scavenger, on MPTP-induced changes of [3H]dopamine uptake was investigated in rat striatal slices. The uptake of [3H]dopamine was decreased by MPTP treatment, and DMTU prevented the MPTP-induced decrease of [3H]dopamine uptake in a dose-dependent manner. The highest dose of DMTU used in this study completely prevented the MPTP-induced decrease of [3H]dopamine uptake. These results indicate that free radicals play a major role in the pathogenetic mechanism of MPTP-induced neurotoxicity.
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Affiliation(s)
- J H Heo
- Department of Neurology, Yonsei University College of Medicine, Seoul, South Korea
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47
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Vieregge P. Genetic factors in the etiology of idiopathic Parkinson's disease. JOURNAL OF NEURAL TRANSMISSION. PARKINSON'S DISEASE AND DEMENTIA SECTION 1994; 8:1-37. [PMID: 7893371 DOI: 10.1007/bf02250916] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Overshadowed by a vigorous search for an environmentally-derived toxin that would be possibly relevant for the pathogenesis of idiopathic Parkinson's disease (PD), genetic factors have largely been neglected for this condition during the last two decades. Recent descriptions of kindreds over three or more generations with several family members affected have renewed the interest in genetics of PD. Concurring with this, diagnostic concepts and pathologic criteria for PD and for idiopathic Lewy-body (LB) disease have been reevaluated such that LB-proven parkinsonism is sufficiently differentiated from familial parkinsonism without LB pathology. Surveys on genetic epidemiology in PD have confirmed the 19th century's notion that 10 to 15% of PD index cases report a further family member with PD. These figures were, however, substantiated on a statistical basis only in single surveys when comparisons were made with the numbers of PD relatives in control index cases. Twin studies did not reveal a higher rate of concordance within monozygotic pairs than in dizygotic pairs. Tests of striatal 18-F-Dopa uptake in clinically unaffected mono- and dizygotic co-twins did not alter the ratio between the concordance rates. Though not excluded by the twin studies, multifactorial (or polygenic) inheritance as well as mitochondrial inheritance are at present less likely to cover most of the inheritance pattern in familial LB parkinsonism. Instead, autosomal dominant inheritance with reduced penetrance is the most probable inheritance pattern for most of the reported pedigrees. Molecular genetic investigations have to consider the biochemical basis of the age- and region-specific pathology of PD. The first analyses of linkage and allelic associations gave inconclusive results in sporadic and familial PD. The hunt for metabolic factors that link geno- and phenotype expression in PD will continue.
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Affiliation(s)
- P Vieregge
- Department of Neurology, Medical University, Lübeck, Federal Republic of Germany
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