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Naoi M, Maruyama W, Inaba-Hasegawa K. Revelation in the neuroprotective functions of rasagiline and selegiline: the induction of distinct genes by different mechanisms. Expert Rev Neurother 2014; 13:671-84. [PMID: 23739004 DOI: 10.1586/ern.13.60] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In Parkinson's disease, cell death of dopamine neurons in the substantia nigra progresses and neuroprotective therapy is required to halt neuronal loss. In cellular and animal models, selegiline [(-)deprenyl] and rasagiline, inhibitors of type B monoamine oxidase (MAO)-B, protect neuronal cells from programmed cell death. In this paper, the authors review their recent results on the molecular mechanisms by which MAO inhibitors prevent the cell death through the induction of antiapoptotic, prosurvival genes. MAO-A mediates the induction of antiapoptotic bcl-2 and mao-a itself by rasagiline, whereas a different mechanism is associated with selegiline. Rasagiline and selegiline preferentially increase GDNF and BDNF in nonhuman primates and Parkinsonian patients, respectively. Enhanced neurotrophic factors might be applicable to monitor the neurorescuing activity of neuroprotection.
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Affiliation(s)
- Makoto Naoi
- Department of Health and Nutrition, Faculty of Psychological and Physical Science, Aichi Gakuin University, Nisshin, Aichi, Japan.
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2
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Inaba-Hasegawa K, Akao Y, Maruyama W, Naoi M. Rasagiline and selegiline, inhibitors of type B monoamine oxidase, induce type A monoamine oxidase in human SH-SY5Y cells. J Neural Transm (Vienna) 2012; 120:435-44. [PMID: 22968599 DOI: 10.1007/s00702-012-0899-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2012] [Accepted: 09/03/2012] [Indexed: 02/03/2023]
Abstract
Type B monoamine oxidase (MAO-B) is proposed to be involved in the pathogenesis of neurodegenerative disorders, such as Parkinson's disease, through oxidative stress and synthesis of neurotoxins. MAO-B inhibitors, rasagiline and selegiline [(-)deprenyl], protect neuronal cells by direct intervention in mitochondrial death signaling and induction of pro-survival Bcl-2 and neurotrophic factors. Recently, type A MAO (MAO-A) was found to mediate the induction of anti-apoptotic Bcl-2 by rasagiline, whereas MAO-A increases in neuronal death and also serves as a target of neurotoxins. These controversial results suggest that MAO-A may play a decisive role in neuronal survival and death. This paper reports that rasagiline and selegiline increased the mRNA, protein and catalytic activity of MAO-A in SH-SY5Y cells. Silencing MAO-A expression with small interfering (si)RNA suppressed rasagiline-dependent MAO-A expression, but MAO-B overexpression in SH-SY5Y cells did not affect, suggesting that MAO-A, not MAO-B, might be associated with MAO-A upregulation. Rasagiline reduced R1, a MAO-A specific repressor, but selegiline did not. Mithramycin-A, an inhibitor of Sp1 binding, and actinomycin-D, a transcriptional inhibitor, reduced the rasagiline-dependent upregulation of MAO-A mRNA, indicating that rasagiline induced MAO-A transcriptionally through R1-Sp1 pathway, whereas selegiline by another non-defined pathway. These results are discussed in relation to the role of MAO-A and these MAO-B inhibitors in neuronal death and neuroprotection.
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Affiliation(s)
- Keiko Inaba-Hasegawa
- Department of Neurosciences, Gifu International Institute of Biotechnology, Kakamigahara, Gifu, Japan
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3
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Seidl SE, Potashkin JA. The promise of neuroprotective agents in Parkinson's disease. Front Neurol 2011; 2:68. [PMID: 22125548 PMCID: PMC3221408 DOI: 10.3389/fneur.2011.00068] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 10/21/2011] [Indexed: 02/04/2023] Open
Abstract
Parkinson’s disease (PD) is characterized by loss of dopamine neurons in the substantia nigra of the brain. Since there are limited treatment options for PD, neuroprotective agents are currently being tested as a means to slow disease progression. Agents targeting oxidative stress, mitochondrial dysfunction, and inflammation are prime candidates for neuroprotection. This review identifies Rasagiline, Minocycline, and creatine, as the most promising neuroprotective agents for PD, and they are all currently in phase III trials. Other agents possessing protective characteristics in delaying PD include stimulants, vitamins, supplements, and other drugs. Additionally, combination therapies also show benefits in slowing PD progression. The identification of neuroprotective agents for PD provides us with therapeutic opportunities for modifying the course of disease progression and, perhaps, reducing the risk of onset when preclinical biomarkers become available.
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Affiliation(s)
- Stacey E Seidl
- Department of Biological Sciences, DePaul University Chicago, IL, USA
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4
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Borman PJ, Chatfield MJ, Crowley EL, Eckers C, Elder DP, Francey SW, Laures AMF, Wolff JC. Development, validation and transfer into a factory environment of a liquid chromatography tandem mass spectrometry assay for the highly neurotoxic impurity FMTP (4-(4-fluorophenyl)-1-methyl-1,2,3,6-tetrahydropyridine) in paroxetine active pharmaceutical ingredient (API). J Pharm Biomed Anal 2008; 48:1082-9. [DOI: 10.1016/j.jpba.2008.08.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 08/13/2008] [Accepted: 08/18/2008] [Indexed: 10/21/2022]
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Naoi M, Maruyama W, Akao Y, Yi H, Yamaoka Y. Involvement of type A monoamine oxidase in neurodegeneration: regulation of mitochondrial signaling leading to cell death or neuroprotection. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 2006:67-77. [PMID: 17447417 DOI: 10.1007/978-3-211-33328-0_8] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In neurodegenerative diseases, including Parkinson's and Alzheimer's diseases, apoptosis is a common type of cell death, and mitochondria emerge as the major organelle to initiate death cascade. Monoamine oxidase (MAO) in the mitochondrial outer membrane produces hydrogen peroxide by oxidation of monoamine substrates, and induces oxidative stress resulting in neuronal degeneration. On the other hand, a series of inhibitors of type B MAO (MAO-B) protect neurons from cell death. These results suggest that MAO may be involved in the cell death process initiated in mitochondria. However, the direct involvement of MAO in the apoptotic signaling has been scarcely reported. In this paper, we present our recent results on the role of MAO in activating and regulating cell death processing in mitochondria. Type A MAO (MAO-A) was found to bind an endogenous dopaminergic neurotoxin, N-methyl(R)salsolinol, and induce apoptosis in dopaminergic SH-SY5Y cells containing only MAO-A. To examine the intervention of MAO-B in apoptotic process, human MAO-B cDNA was transfected to SH-SY5Y cells, but the sensitivity to N-methyl(R)salsolinol was not affected, even though the activity and protein of MAO-B were expressed markedly. MAO-B oxidized dopamine with production of hydrogen peroxide, whereas in control cells expressing only MAO-A, dopamine autoxidation produced superoxide and dopamine-quinone, and induced mitochondrial permeability transition and apoptosis. Rasagiline and other MAO-B inhibitors prevent the activation of apoptotic cascade and induce prosurvival genes, such as bcl-2 and glial cell line-derived neurotrophic factor, in MAO-A-containing cells. These results demonstrate a novel function of MAO-A in the induction and regulation of apoptosis. Future studies will clarify more detailed mechanism behind regulation of mitochondrial death signaling by MAO-A, and bring out new strategies to cure or ameliorate the decline of neurons in neurodegenerative disorders.
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Affiliation(s)
- M Naoi
- Department of Neurosciences, Gifu International Institute of Biotechnology, Kakamigahara, Gifu, Japan.
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6
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Mauceli G, Busceti CI, Pellegrini A, Soldani P, Lenzi P, Paparelli A, Fornai F. Overexpression of -Synuclein following Methamphetamine: Is It Good or Bad? Ann N Y Acad Sci 2006; 1074:191-7. [PMID: 17105917 DOI: 10.1196/annals.1369.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
alpha-Synuclein is a presynaptic protein involved in various degenerative disorders now defined as synucleinopathies. These include neurological diseases that share a few pathological features consisting of aggregates of both normal and altered alpha-synuclein within specific neuronal populations and/or glial cells. The prototype of synucleinopathies is represented by Parkinson's disease (PD) in which alpha-synuclein is identified as a constant component of neuronal pale eosinophilic inclusions: "the Lewy Bodies." In the present article, we discuss the potential significance of amphetamine-induced overexpression of alpha-synuclein in light of clinical findings showing neurodegeneration following overexpression of alpha-synuclein and recent experimental studies that measured increased expression of alpha-synuclein following amphetamine derivatives.
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Affiliation(s)
- Giuseppe Mauceli
- Department of Human Morphology and Applied Biology, University of Pisa, Via Roma, 55, I-56126 Pisa, Italy.
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7
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González-Polo RA, Soler G, Alonso JC, Rodríguez-Martín A, Fuentes JM. MPP(+) causes inhibition of cellular energy supply in cerebellar granule cells. Neurotoxicology 2003; 24:219-25. [PMID: 12606294 DOI: 10.1016/s0161-813x(02)00164-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A significant loss in ATP levels was found in cerebellar granule cells with 1-methyl-4-phenylpyridinium. Exposure of cerebellar granule cells to low concentrations of 1-methyl-4-phenylpyridinium (100 microM) resulted in a time and dose-dependent decreases in ATP levels and cell death. This neurotoxin caused inhibition of the enzymatic activity of NADH-dehydrogenase of mitochondrial complex I and consequent impairment of mitochondrial electronic transport with a reduction in the depletion of cytosolic NAD(+) levels. Activation of lactate dehydrogenase activity (detected by the increase of the lactate in the culture medium) partially reduced this depletion. Addition of glucose but not pyruvate to the culture medium protected 1-methyl-4-phenylpyridinium-induced cell death. These results suggest the 1-methyl-4-phenylpyridinium causes impairment of cellular energy metabolism with a major dependence on glycolysis as a source of energy. This fact could also explain the partial neuroprotection observed by glucose.
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Affiliation(s)
- Rosa A González-Polo
- Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
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8
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Lee Y, Ling KQ, Lu X, Silverman RB, Shepard EM, Dooley DM, Sayre LM. 3-pyrrolines are mechanism-based inactivators of the quinone-dependent amine oxidases but only substrates of the flavin-dependent amine oxidases. J Am Chem Soc 2002; 124:12135-43. [PMID: 12371853 DOI: 10.1021/ja0205434] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We previously reported that 3-pyrroline and 3-phenyl-3-pyrroline effect a time-dependent inactivation of the copper-containing quinone-dependent amine oxidase from bovine plasma (BPAO) (Lee et al. J. Am. Chem. Soc. 1996, 118, 7241-7242). Quinone cofactor model studies suggested a mechanism involving stoichiometric turnover to a stable pyrrolylated cofactor. Full details of the model studies are now reported along with data on the inhibition of BPAO by a family of 3-aryl-3-pyrrolines (aryl = substituted phenyl, 1-naphthyl, 2-naphthyl), with the 4-methoxy-3-nitrophenyl analogue being the most potent. At the same time, the parent 3-phenyl analogue is a pure substrate for the flavin-dependent mitochondrial monoamine oxidase B from bovine liver. Spectroscopic studies (including resonance Raman) on BPAO inactivated by the 4-methoxy-3-nitrophenyl analogue are consistent with covalent derivatization of the 2,4,5-trihydroxyphenylalanine quinone (TPQ) cofactor. The distinction of a class of compounds acting as an inactivator of one amine oxidase family and a pure substrate of another amine oxidase family represents a unique lead to the development of selective inhibitors of the mammalian copper-containing amine oxidases.
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Affiliation(s)
- Younghee Lee
- Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106, USA
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9
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González-Polo RA, Mora A, Clemente N, Sabio G, Centeno F, Soler G, Fuentes JM. Mechanisms of MPP(+) incorporation into cerebellar granule cells. Brain Res Bull 2001; 56:119-23. [PMID: 11704348 DOI: 10.1016/s0361-9230(01)00610-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Exposure of cerebellar granule cells to 1-methyl-4-phenylpiridinium (MPP(+)) results in cell death. We have studied the implication of various membrane transporter systems on MPP(+) neurotoxicity, including the dopamine transporter system (DAT) and cationic amino acid transporters (CAT). We have showed a partial protection against MPP(+) toxicity when the dopamine transporter is inhibited by 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]4-(3-phenylpropyl)piperazinedihydrochloride (GBR-12909). However, almost full protection is only achieved by the simultaneous addition of GBR-12909 and cationic amino acids. These results suggest two ways system of MPP(+) entrance into cerebellar granule cells: the DAT with high activity and the CAT with low activity. We also demonstrated that 5,7-dichlorokynurenic acid (MK-801) failed to protect against MPP(+) exposure, evidencing that N-methyl-D-aspartate (NMDA) receptor is not involved in the MPP(+)-induced cell death.
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MESH Headings
- 1-Methyl-4-phenylpyridinium/metabolism
- 1-Methyl-4-phenylpyridinium/toxicity
- Amino Acid Transport Systems, Basic/drug effects
- Amino Acid Transport Systems, Basic/metabolism
- Amino Acids, Basic/metabolism
- Animals
- Animals, Newborn
- Apoptosis/drug effects
- Apoptosis/physiology
- Carrier Proteins/drug effects
- Carrier Proteins/metabolism
- Cells, Cultured/drug effects
- Cells, Cultured/metabolism
- Cerebellar Cortex/drug effects
- Cerebellar Cortex/metabolism
- Dopamine/metabolism
- Dopamine Plasma Membrane Transport Proteins
- Dopamine Uptake Inhibitors/pharmacology
- Dose-Response Relationship, Drug
- Drug Interactions/physiology
- Excitatory Amino Acid Antagonists/pharmacology
- Female
- Herbicides/metabolism
- Herbicides/toxicity
- MPTP Poisoning/metabolism
- MPTP Poisoning/physiopathology
- Male
- Membrane Glycoproteins
- Membrane Transport Proteins/drug effects
- Membrane Transport Proteins/metabolism
- Nerve Tissue Proteins
- Neurons/drug effects
- Neurons/metabolism
- Neurotoxins/metabolism
- Neurotoxins/toxicity
- Piperazines/pharmacology
- Rats
- Rats, Wistar
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/drug effects
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Affiliation(s)
- R A González-Polo
- Depto. Bioquímica y Biología Molecular y Genética, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
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10
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Storch A, Ludolph AC, Schwarz J. HEK-293 cells expressing the human dopamine transporter are susceptible to low concentrations of 1-methyl-4-phenylpyridine (MPP+) via impairment of energy metabolism. Neurochem Int 1999; 35:393-403. [PMID: 10517700 DOI: 10.1016/s0197-0186(99)00083-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Selective dopaminergic neurotoxicity induced by 1-methyl-4-phenylpyridine (MPP+) is believed to be due to the transmembrane uptake by the dopamine transporter and subsequent inhibition of mitochondrial complex I and/or production of free radicals. However, little is known about the molecular sequence of intracellular events leading to cell death induced by low concentrations of MPP+. Here we stably express the human dopamine transporter (hDAT) in human embryonic kidney HEK-293 cells to correlate cytotoxicity and indices of cellular energy metabolism after exposure to low concentrations of MPP+. The permanent ektopic expression of hDAT in HEK-293 cells confers time and dose-dependent cytotoxicity at nanomolar concentrations of MPP+ with an IC50 value of 740 nM after 48 h. MPP+ initially induces a fast increase of cellular NADH content within the first 6 h, followed by a slow reduction of intracellular ATP (IC50 value of 690 nM after 48 h) as well as reduction of intracellular ATP/ADP ratio. These changes of cellular energy metabolism precede reduction of cell viability. The toxic effects of MPP+ are blocked by the hDAT inhibitor GBR12909 with EC50 values of 110 and 60 nM for cytotoxicity and ATP depletion, respectively. Antioxidants such as D-alpha-tocopherol and ascorbic acid do not have significant protective effects against MPP+ toxicity. This study shows that HEK-293 cells expressing the hDAT gene are highly sensitive to MPP+ due to (i) transmembrane uptake of MPP+ by the dopamine transporter, (ii) cellular energy depletion, probably caused by inhibition of mitochondrial complex I activity and (iii) that the toxicity is independent from the presence of antioxidants. This cell system may serve as a screening system for endogenous and exogenous compounds with similar effects compared to MPP+ as well as protective agents.
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Affiliation(s)
- A Storch
- Department of Neurology, University of Ulm Medical School, Germany.
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11
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Rojas P, Klaassen CD. Metallothionein-I and -II knock-out mice are not more sensitive than control mice to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine neurotoxicity. Neurosci Lett 1999; 273:113-6. [PMID: 10505629 DOI: 10.1016/s0304-3940(99)00651-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Oxidative stress, resulting from either excess generation or reduced scavenging of free radicals, has been proposed to play a role in damaging striatal neurons in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxicity. Metallothionein (MT) is a scavenger of oxygen-derived free radicals and it has been suggested that MT protects against oxidative damage in the central nervous system. In the present study we compared MT-I and -II null mice (MT-null) and the parental strain with intact metallothionein genes (control mice) to determine whether the absence of MT protein alters MPTP neurotoxicity. Control and MT-null mice were treated with MPTP at different doses (30, 40 and 50 mg/kg, i.p.) for 11 days. Seven days after the last dose, brains were removed and dopamine (DA) and homovanillic acid (HVA) contents were analyzed in striatum and midbrain by high pressure liquid chromatography (HPLC). Striatal DA content in MPTP-treated control mice was reduced by 53, 74 and 84% after 30, 40 and 50 mg/kg, respectively. Similar decreases were observed in MT-null mice treated with MPTP. MT-null mice were not more sensitive than control mice to MPTP neurotoxicity. The data suggest that MT-I and -II proteins do not play a role in protecting against MPTP neurotoxicity.
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Affiliation(s)
- P Rojas
- Center for Environmental and Occupational Health, Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City 66160-7417, USA
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12
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Mabic S, Castagnoli N. Assessment of structural requirements for the monoamine oxidase-B-catalyzed oxidation of 1,4-disubstituted-1,2,3,6-tetrahydropyridine derivatives related to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. J Med Chem 1996; 39:3694-700. [PMID: 8809158 DOI: 10.1021/jm9603882] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The monoamine oxidase B (MAO-B) substrate properties and distance measurements along the N1-C4 axis of 38 1,4-disubstituted-1,2,3,6-tetrahydropyridine derivatives, including seven newly synthesized MPTP analogs, were used to define the maximum size that can be accommodated by the MAO-B active site. Only those compounds measuring less than 12 A displayed significant MAO-B substrate properties. The behavior of various 4-substituted-1-cyclopropyltetrahydropyridine analogs also is discussed in terms of this N1-C4 distance parameter in an effort to understand factors which contribute to their substrate vs inactivator properties. We conclude that this distance parameter will predict the majority of substrates vs nonsubstrates with this class of compound.
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Affiliation(s)
- S Mabic
- Department of Chemistry, Virginia Tech, Blacksburg 24061, USA
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13
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Akaneya Y, Takahashi M, Hatanaka H. Selective acid vulnerability of dopaminergic neurons and its recovery by brain-derived neurotrophic factor. Brain Res 1995; 704:175-83. [PMID: 8788912 DOI: 10.1016/0006-8993(95)01110-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Among the pathogenetic phenomena of Parkinson's disease, the character of the selective degeneration of nigrostriatal system with severe gliosis is not fully understood. Here, we have shown that dopaminergic neurons may be exclusively sensitive to elevated acidity elicited after the addition of glial mitogenic factors such as epidermal growth factor and basic fibroblast growth factor or after the direct treatment with hydrochloric acid. The acid sensitivity was specific to dopaminergic neurons. The neurons other than dopaminergic neurons in culture from the ventral mesencephalon were not sensitive to acidity and the neurons from several brain areas were the same as above, except for the hippocampal neurons which had slight acid vulnerability. Choline acetyltransferase assay studies demonstrated that the cholinergic neuronal population in the septum and corpus striatum had no acid sensitivity. The vulnerability of dopaminergic neurons either elicited by glial mitogenic factor or derived from the direct acid exposure was inhibited by the addition of brain-derived neurotrophic factor (BDNF), but not by neurotrophin-3 or nerve growth factor. These findings suggest that dopaminergic neurons have selective acid vulnerability on which BDNF has a pronounced protective effect.
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Affiliation(s)
- Y Akaneya
- Department of Neurology, Kinki University School of Medicine, Osaka, Japan
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14
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Akaneya Y, Takahashi M, Hatanaka H. Survival of and 1-methyl-4-phenylpyridinium (MPP+) neurotoxicity against dopaminergic neurons in coculture of rat mesencephalon with their target or non-target regions. Neurosci Res 1995. [DOI: 10.1016/0168-0102(95)90013-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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15
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Akaneya Y, Takahashi M, Hatanaka H. Involvement of free radicals in MPP+ neurotoxicity against rat dopaminergic neurons in culture. Neurosci Lett 1995; 193:53-6. [PMID: 7566666 DOI: 10.1016/0304-3940(95)11668-m] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To examine the mechanisms of the neurotoxicity of 1-methyl-4-phenylpyridinium (MPP+) against dopaminergic neurons, ventral mesencephalic cells from embryonic rats were cultured and exposed to MPP+ with various antioxidants or glutamate receptor antagonists to investigate the participation of free radicals and glutamate, respectively. Such antioxidants as vitamin E, vitamin C, coenzyme Q10, and catalase, but neither allopurinol nor superoxide dismutase, alleviated the MPP(+) -induced death of dopaminergic neurons, while glutamate receptor antagonists did not alter MPP+ neurotoxicity. These findings suggest the participation of free radicals, particularly hydroxyl radicals rather than superoxides, in the process of dopaminergic neuronal death evoked by MPP+.
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Affiliation(s)
- Y Akaneya
- Department of Neurology, Kinki University School of Medicine, Osaka, Japan
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16
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Basic Biochemical Approaches in Neurotoxicology. Neurotoxicology 1995. [DOI: 10.1016/b978-012168055-8/50026-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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17
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Ali SF, David SN, Newport GD, Cadet JL, Slikker W. MPTP-induced oxidative stress and neurotoxicity are age-dependent: evidence from measures of reactive oxygen species and striatal dopamine levels. Synapse 1994; 18:27-34. [PMID: 7825121 DOI: 10.1002/syn.890180105] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes marked depletion of dopamine (DA) levels and reduction in the activity of tyrosine hydroxylase (TH) in the nigrostriatal DA pathway. In the brain, the enzyme monoamine oxidase B converts MPTP to 1-methyl-4-phenylpyridinium (MPP+) which enters DA terminals via DA uptake sites. Within the DA terminals, MPP+ blocks the mitochondrial complex I and causes ATP depletion. This is thought to be the main cause of MPTP-induced terminal degeneration. In addition, reactive oxygen species (ROS) generated after blockade of the complex I as well as those generated due to DA oxidation may participate in MPTP-induced dopaminotoxicity. The present study sought to determine if a single injection of a large dose of MPTP generates ROS. We also sought to determine if these changes as well as changes in DA levels were correlated and age-dependent. Toward that end, we have used C57/B6N male mice that were 22 days or 12 months old. These animals were injected with a single dose of MPTP (40 mg/kg, ip). Animals were sacrificed at various times after drug administration. MPTP produced no significant increase in ROS nor decreases in DA or HVA concentrations in the striatum of the younger mice. However, DOPAC concentrations were significantly decreased from 15-120 min after drug administration. In the older mice, MPTP caused significant increases in ROS from the beginning to the end of the study period. DA concentrations were decreased from 60 min onward. DOPAC concentrations were decreased significantly after 15-120 min while HVA concentrations were significantly increased after 60 and 120 min.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S F Ali
- Neurochemistry Laboratory, National Center for Toxicological Research, Jefferson, Arkansas 72079
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18
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Seyfried CA, Adam G. Studies on the interaction of roxindole with brain monoamine oxidases and dopaminergic neurones in vitro and in vivo. PHARMACOLOGY & TOXICOLOGY 1994; 74:314-20. [PMID: 7937563 DOI: 10.1111/j.1600-0773.1994.tb01366.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Roxindole, a structurally novel psychotropic indolylbutyl-4-phenyltetrahydropyridine, was studied with respect to the formation of potentially neurotoxic pyridinium metabolites in comparison to MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine). In contrast to MPTP, roxindole failed to serve as a substrate for monoamine oxidases (MAO) from mouse, monkey and human brain in vitro. Accordingly, neither the putative MAO-oxidation product of roxindole (ROX+) nor MPP+ (1-methyl-4-phenylpyridinium ion) was detected in mouse striatum after high subcutaneous doses of roxindole in spite of the presence of approximately 6 micrograms of roxindole per g of striatum in these animals. After multiple subcutaneous treatments with 95.2 mg/kg roxindole, no long-term striatal dopamine depletions were observed in contrast to MPTP. Furthermore, unlike MPP+, ROX+ did not induce release of previously accumulated 3H-dopamine in mouse striatal slices indicating that ROX+ cannot utilize the dopamine uptake carrier to enter neurones. ROX+ at doses up to 100 mg/kg subcutaneously failed to alter striatal biogenic amine levels and gross behaviour of mice. Thus, no MPTP-like neurotoxic metabolites are formed from roxindole in vivo and neurotoxic effects of ROX+, even if formed in minute amounts by some MAO-independent pathway, are highly unlikely.
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Affiliation(s)
- C A Seyfried
- Department of CNS Research, E. Merck, Darmstadt, Germany
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19
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Temlett JA, Landsberg JP, Watt F, Grime GW. Increased iron in the substantia nigra compacta of the MPTP-lesioned hemiparkinsonian African green monkey: evidence from proton microprobe elemental microanalysis. J Neurochem 1994; 62:134-46. [PMID: 8263513 DOI: 10.1046/j.1471-4159.1994.62010134.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The association of free radicals and particularly free iron in the pathogenesis of idiopathic Parkinson's disease and MPTP-induced parkinsonism remains controversial. Whereas the actual cause of dopamine cell death in the substantia nigra compacta (SNc) remains unknown, disturbances in lipid peroxidation and subsequent mitochondrial and cell membrane disruption has been demonstrated. In a genetically susceptible host, abnormal elimination of oxygen and trace metal free radicals may further damage dopamine cells. Using a unilaterally MPTP-treated African Green monkey, which showed obvious contralateral hemiparkinsonism, the total free iron concentration was measured. Iron, Fe2+ and Fe3+, but not other trace elements, was significantly elevated in the SNc compared with the opposite unlesioned side, which was similar to separate control animals. Iron content in the SNc, periaqueductal gray area, and crus cerebri was 228-270 ppm. Normal control SNc was 285 (+/- 59) ppm, whereas iron levels of 532 (+/- 151) ppm were found in the MPTP-lesioned SNc. These animals were drug naive and not on long-term levodopa maintenance. Proton microprobe elemental analysis was matched against adjacent immunocytochemically stained tissue slices to ensure the cells studied were in the SNc. Iron was found not only in the degenerating dopamine cells themselves but also in the surrounding matrix and glial cells. Whether free iron that is not bound to neuromelanin is responsible for dopamine cell death as suggested by these experiments remains to be proved.
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Affiliation(s)
- J A Temlett
- Department of Medicine, University of the Witwatersrand Medical School, Johannesburg, South Africa
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20
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21
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Konradi C, Ozelius L, Breakefield XO. Highly polymorphic (GT)n repeat sequence in intron II of the human MAOB gene. Genomics 1992; 12:176-7. [PMID: 1733859 DOI: 10.1016/0888-7543(92)90426-s] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- C Konradi
- Department of Neurobiology, Massachusetts General Hospital, Charlestown 02129
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22
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Jenner P. Oxidative stress as a cause of Parkinson's disease. ACTA NEUROLOGICA SCANDINAVICA. SUPPLEMENTUM 1991; 136:6-15. [PMID: 1801537 DOI: 10.1111/j.1600-0404.1991.tb05013.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The cause of dopamine cell death in Parkinson's disease remains unknown. Present interest centres on the possible involvement of a toxin mediated mechanism such as that produced, by MPTP. In post-mortem studies there is evidence in the substantia nigra for an on-going toxic process involving increased lipid peroxidation, altered iron metabolism and impairment of mitochondrial function at the level of complex I. Although the precise relationship between these biochemical changes is not known, present evidence points to oxidative stress as an important factor contributing to neuronal loss. Altered mitochondrial function and increased iron levels may not initiate Parkinson's disease but rather act to accelerate cell death. Future strategies for the treatment of Parkinson's disease should be aimed at preventing oxidative stress and stopping or slowing the progression of the underlying pathology.
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Affiliation(s)
- P Jenner
- Parkinson's Disease Society Experimental Research Laboratories, King's College, London, UK
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23
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Efange SM, Boudreau RJ. Molecular determinants in the bioactivation of the dopaminergic neurotoxin N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). J Comput Aided Mol Des 1991; 5:405-17. [PMID: 1685185 DOI: 10.1007/bf00125661] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Nineteen analogs of the dopaminergic neurotoxin N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) have been used as probes to study the structural parameters that influence MAO-catalyzed oxidation. In this study, the efficiency of enzyme-catalyzed substrate oxidation was found to be unrelated to parameters such as the ionization potential, dipole moment, net atomic charge at C5 and the dihedral angle between the phenyl ring and the tetrahydropyridine moiety. Conformational analysis revealed that substitution at the C2' position of MPTP yields atropisomers. It is suggested that one of these atropisomers would be either inactive or substantially less active than the other. Therefore, the relative oxidative efficiency and toxicity of these compounds reported earlier may have been significantly underestimated. Based on the conformational analysis and other data, a rudimentary model of the MAO substrate site has been developed which partially explains the substrate specificities of MAO A and MAO B. Each substrate binding site can be divided into two regions, (a) an amine-binding pocket (for the tetrahydropyridine moiety), and (b) a 'bulky substituent' region (for the phenyl group and its substituents). The length of the substrate binding site (measured along the long axis of MPTP) is approximately 8.5 A, and the width of the 'amine-binding' pocket is approximately 2.5 A (from C3 to C5). The 'bulky substituent' region contains a central area for binding the phenyl group of MPTP. This central area is flanked by two hydrophobic pockets, P2' and P3'. In MAO A, the pocket P2'-A is oriented 45-135 degrees relative to the plane of the tetrahydropyridine moiety, with a radius of 3.1 A from C2' of the phenyl ring. The radius of a similar but smaller pocket, P2'-B, in MAO B, is approximately 2.7 A. In MAO B, the pocket P3'-B (radius 2.36 A from C3') is larger than a similar pocket P3'-A (radius 1.70 A from C3') in MAO A. The foregoing characterization suggests that differences in the size and topography of both of the substituent pockets play an important role in determining the substrate specificities of these two isozymes.
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MESH Headings
- 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine/analogs & derivatives
- 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine/chemistry
- 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine/pharmacokinetics
- Binding Sites
- Biotransformation
- Computer Simulation
- Dopamine Agents/chemistry
- Dopamine Agents/pharmacokinetics
- Models, Molecular
- Molecular Conformation
- Molecular Probes
- Molecular Structure
- Monoamine Oxidase/metabolism
- Neurotoxins/chemistry
- Neurotoxins/pharmacokinetics
- Oxidation-Reduction
- Substrate Specificity
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Affiliation(s)
- S M Efange
- Department of Radiology, University of Minnesota, Minneapolis 55455
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24
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Wilson JS, Shearer DT, Adelakun AK, Carpentier RG. Mechanisms of the inotropic actions of MPTP and MPP+ on isolated atria of rat. Toxicol Appl Pharmacol 1991; 111:49-57. [PMID: 1949035 DOI: 10.1016/0041-008x(91)90133-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Besides having toxic actions, MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and MPP+ (1-methyl-4-phenyl-pyridinium ion) produce the release of catecholamines in the peripheral and central nervous systems. This paper reports on the effects of MPTP and MPP+ on isolated left atria of rats and their mechanisms. MPP+ and MPTP produced a concentration-dependent positive inotropic effect. This action was blocked by propranolol and nomifensine; however, inhibition of monoamine oxidase had no effect on the response. In atria from reserpinized rats, the positive inotropic effect of MPTP was also blocked and a negative inotropic effect was unmasked which continued to increase in magnitude during wash. The negative inotropic effect was markedly reduced by superoxide dismutase and catalase. These results indicate that MPTP and MPP+ produce a catecholamine-mediated positive inotropic effect that is not MAO-dependent, unlike the toxic actions of MPTP. These results also suggest that MPTP may directly damage cardiac muscle by generating free radicals which might explain why high doses of MPTP are lethal to animals.
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Affiliation(s)
- J S Wilson
- Department of Anatomy, College of Medicine, Howard University, Washington, D.C. 20059
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25
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Jiménez-Jiménez FJ, Tabernero C, Mena MA, García de Yébenes J, García de Yébenes MJ, Casarejos MJ, Pardo B, García-Agundez JA, Benítez J, Martínez A. Acute effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in a model of rat designated a poor metabolizer of debrisoquine. J Neurochem 1991; 57:81-7. [PMID: 1711101 DOI: 10.1111/j.1471-4159.1991.tb02102.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The relationship between oxidative polymorphisms and the cause of Parkinson's disease is controversial. The drug 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which induces parkinsonism in humans and in some animal models, is metabolized by cytochrome P450 db1 isozyme (the same enzymatic system implicated in 4-hydroxylation of debrisoquine). In this study, we treated females of three rat species, which differ in their ability to hydroxylate debrisoquine, with MPTP (three doses of 30 mg/kg s.c. at 12-h intervals), and we measured their motor activity and brain monoamine levels. Female dark-adapted rats (poor metabolizers of debrisoquine) showed a more pronounced and more maintained reduction of their motor activity after treatment with MPTP. MPTP-treated, dark-adapted rats also had a depletion of noradrenaline in the diencephalon and a depletion of dopamine and serotonine and their respective metabolites in the limbic system when compared with the other two species. These results suggest that oxidative polymorphism of debrisoquine plays a role in the acute effects of MPTP.
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26
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Nilsson K, Hallberg A, Pileblad E, Tunek A. Investigation of the possible dopaminergic toxicity of 1-methyl-3-phenyl-1,2,3,6-tetrahydropyridine, an isomer to the neurotoxin MPTP. PHARMACOLOGY & TOXICOLOGY 1991; 69:38-42. [PMID: 1682909 DOI: 10.1111/j.1600-0773.1991.tb00406.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1-Methyl-3-phenyl-1,2,3,6-tetrahydropyridine (M-3-PTP) is an analogue to the Parkinson-producing dopaminergic toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), M-3-PTP, and simple analogues thereof, are versatile intermediates in organic synthesis. The present study was undertaken to investigate the possible dopaminergic toxicity of M-3-PTP. Male albino mice were injected with 50 mg/kg of either MPTP or M-3-PTP and dopamine (DA) and its metabolites were determined 2 hr and 7 days after the administration. Two hr after MPTP profound acute changes in brain DA metabolism were found, i.e. an approximately 50% reduction in the concentration of DA together with a 10-fold increase in the level of 3-methoxytyramine. Seven days after MPTP, DA and metabolites were markedly reduced which is consistent with a degeneration of the dopaminergic neurones. In contrast M-3-PTP produced no acute or long-term alterations in the concentrations of DA and its metabolites in mouse brain. Furthermore, in vitro experiments show that M-3-PTP does not inhibit monoamine oxidase B. Thus, the present data show that M-3-PTP is devoid of dopaminergic toxicity in mouse brain and is not likely to produce Parkinson's disease in humans. The lack of toxicity is probably explained by the low affinity of M-3-PTP for monoamino oxidase B.
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Affiliation(s)
- K Nilsson
- Department of Organic Pharmaceutical Chemistry, Uppsala Biomedical Center, Uppsala University, Sweden
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27
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Abstract
Oxygen free radicals, any chemical moiety containing an oxygen atom with an unpaired electron in the outer orbital shell, are generated during many normal biochemical reactions in living tissue. The unpaired electron makes these compounds highly reactive and they can initiate disruptive peroxidation reactions with various substrates important to the survival of cells such as proteins, lipids and nucleic acids. A fairly complex defense system has evolved to protect living tissue from free radicals and to minimize the damage they might cause. Neurons are especially vulnerable to free radical attack and impaired defenses or exposure to excess free radicals can lead to neuronal death. Free radicals contribute to neuronal loss in cerebral ischemia and hemorrhage and may be involved in the degeneration of neurons in epilepsy, schizophrenia, tardive dyskinesia, normal aging, Parkinson's Disease and Alzheimer's Disease. The development of drugs that limit or prevent the attack of free radicals on neurons would be an important advance in the treatment of these conditions.
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Affiliation(s)
- J A Jesberger
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, Canada
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28
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Gershon MD, Sherman DL, Pintar JE. Type-specific localization of monoamine oxidase in the enteric nervous system: relationship to 5-hydroxytryptamine, neuropeptides, and sympathetic nerves. J Comp Neurol 1990; 301:191-213. [PMID: 2124589 DOI: 10.1002/cne.903010205] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The localization in the guinea pig enteric nervous system (ENS) of monoamine oxidase (MAO) types A and B was investigated at the light and electron microscopic levels. Immunocytochemistry was used to visualize the enzyme protein and histochemistry was employed to study catalytic activity. Type specificity was achieved in histochemical studies by using deprenyl (0.5 microM) to inhibit MAO-B or clorgyline (0.1 microM) to inhibit MAO-A. The distribution of MAO-B immunoreactivity in the ENS corresponded to that of the sites of MAO activity found histochemically to be inhibited by deprenyl, but not clorgyline. MAO-B was observed to be the primary type of MAO found in the intrinsic elements of the ENS and was located in subsets of neurons in both submucosal and myenteric plexuses. MAO-B was not demonstrated immunocytochemically or histochemically in enteric glia, nor, at the light microscopic level, was there significant MAO-B activity or immunoreactivity in serotonin (5-HT)-immunoreactive neuronal cell bodies. In the submucosal plexus about 50% of the neurons expressed MAO-B; these neurons also contained neuropeptide y (NPY) and/or calcitonin gene related peptide (CGRP), but not substance P or vasoactive intestinal polypeptide (VIP). About 10% of myenteric neurons were intensely reactive for MAO-B; again MAO-B was co-localized with NPY and/or CGRP. In contrast to intrinsic neurons, extrinsic CGRP-immunoreactive nerve fibers contained no demonstrable MAO activity or immunoreactivity. Moreover, the sympathetic innervation, identified as varicose axons that degenerated after administration of 6-hydroxydopamine, contained abundant MAO-A, but no MAO-B activity or immunoreactivity. It is concluded that MAO-B is characteristic of a subset of intrinsic enteric neurons, while MAO-A is confined to the sympathetic innervation, which is extrinsic. At the electron microscopic level individual cells varied greatly in their degree of immuno- or cytochemically demonstrable MAO-B, which was most concentrated on the outer membranes of mitochondria. MAO-B immunoreactivity (but not cytochemical activity) was found on mitochondria in some serotoninergic perikarya identified by the simultaneous radioautographic detection of the uptake of 3H-5-HT. Mitochondria in most serotoninergic axon terminals displayed both MAO-B activity and immunoreactivity. Neurons receiving serotoninergic synapses often, but not invariably, contained MAO-B. Inhibition of neither MAO-B nor MAO-A appeared to slow the disappearance of 3H-5-HT loaded into enteric neurons significantly, even when intraneuronal storage of 5-HT was inhibited with tetrabenazine.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- M D Gershon
- Department of Anatomy and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York 10032
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29
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Deutch AY, Elsworth JD, Roth RH, Goldstein M, Deutsch AY. 3-Acetylpyridine results in degeneration of the extrapyramidal and cerebellar motor systems: loss of the dorsolateral striatal dopamine innervation. Brain Res 1990; 527:96-102. [PMID: 2126479 DOI: 10.1016/0006-8993(90)91065-o] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
3-Acetylpyridine (3-AP) administration to rats results in degeneration of the dopamine (DA) innervation of the striatum as well as degeneration of the olivocerebellar system. We now report that administration of this pyridine neurotoxin results in a decrease in striatal DA concentration which is restricted to the dorsolateral aspects of the caudatoputamen. 3-AP treatment did not alter DA levels in the ventromedial striatum, the nucleus accumbens, or the anteromedial prefrontal cortex. Both 3-AP and another pyridine neurotoxin, 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP), potently inhibited in vitro MAOB activity and in contrast weakly inhibited MAOA activity. However, in vitro inhibition of MAOB by the selective inhibitor deprenyl did not prevent or attenuate 3-AP-induced striatal DA depletion. These data indicate that 3-AP administration to rats not only results in degeneration of the olivocerebellar system, but also effects degeneration of the DA innervation of the dorsolateral striatum, the striatal sector thought to subserve motoric and sensorimotor function. 3-AP-induced nigrostriatal degeneration differs from that elicited by MPTP in that the former is not prevented by deprenyl pretreatment. The 3-AP-induced degeneration of both extrapyramidal and cerebellar motor systems may offer insight into the mechanisms involved in degeneration of the two motor systems in certain strains of rodents (such as the Weaver mutant mouse), and suggests that the sequelae of administration of this pyridine may serve as a useful model for olivopontocerebellar atrophy-associated parkinsonism.
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Affiliation(s)
- A Y Deutch
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510
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30
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Michel PP, Hefti F. Toxicity of 6-hydroxydopamine and dopamine for dopaminergic neurons in culture. J Neurosci Res 1990; 26:428-35. [PMID: 1977925 DOI: 10.1002/jnr.490260405] [Citation(s) in RCA: 259] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Toxicity of 6-hydroxydopamine (6-OHDA) and dopamine were studied in cultures of dissociated fetal rat mesencephalic cells. To assess survival and function of dopaminergic cells we quantified the number of tyrosine hydroxylase-positive cells and measured dopamine uptake. Non-dopaminergic cells were monitored by counting the number of cells visible with phase-contrast microscopy and measuring GABA uptake. 6-OHDA, in contrast to MPP+, which selectively destroyed dopaminergic neurons, was found to be a non-selective neurotoxin in this culture system. Between 10 and 100 microM, dopaminergic and non-dopaminergic cells were destroyed. At concentrations higher than 100 microM, i.e., concentrations frequently used to lesion catecholaminergic neurons in vivo, 6-OHDA resulted in structural fixation and loss of viability of dopaminergic and non-dopaminergic cells. Dopamine produced the same actions at slightly higher concentrations. One hundred to 300 microM was toxic for all cell types, and concentrations above 300 microM resulted in fixation. The findings suggest that 6-OHDA cannot be considered a selective toxin for catecholaminergic neurons in vitro. The demonstrated toxicity of dopamine tends to support speculations that processes related to dopamine metabolism may play a role in the pathogenesis of Parkinson's disease.
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Affiliation(s)
- P P Michel
- Department of Neurology, University of Miami
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31
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Michel PP, Dandapani BK, Efange SM, Hefti F. Potential environmental neurotoxins related to 1-methyl-4-phenylpyridinium: selective toxicity of 1-methyl-4-(4'-acetamidophenyl)-pyridinium and 1-methyl-4-cyclohexylpyridinium for dopaminergic neurons in culture. Exp Neurol 1990; 108:141-50. [PMID: 2335192 DOI: 10.1016/0014-4886(90)90021-j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mesencephalic cells in culture were exposed to various compounds which we hypothesized to be selective toxins for dopaminergic neurons. The culture system was previously shown suitable for assessing selective dopaminergic neurotoxicity, since 1-methyl-4-phenyl-pyridinium (MPP+), the active metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridinium, destroyed dopaminergic neurons without affecting other cells. Some compounds tested were selected to fulfill two criteria believed to underly the selective dopaminergic neurotoxicity of MPP+, i.e., to be a potential substrate for the uptake carrier for dopamine and to possess a strong delocalized positive charge to inhibit the mitochondrial respiratory system. Other compounds were chosen on the basis of clinical or anecdotal evidence linking them to Parkinson's disease. Among the tested compounds two pyridinium analogs, 1-methyl-4-(4'-acetamidophenyl)pyridinium (MACPP+) and 1-methyl-4-cyclohexylpyridinium (MCP+) were found to be selectively toxic toward dopaminergic neurons. Incubation of cultures with both MACPP+ and MCP+ produced a dramatic reduction in the number of tyrosine hydroxylase-positive cells and the uptake of [3H]dopamine without reducing the number of cells visualized by phase-contrast microscopy or the uptake of [3H]aminobutyric acid. Besides MACPP+ and MCP+ none of the tested compounds exhibited any selective dopaminergic neurotoxicity. Together with earlier findings, these data suggest that the structural requirements are rather strict for a chemical to be a selective dopaminergic neurotoxin and make it unlikely that there is a wide spectrum of environmental dopaminergic toxins.
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Affiliation(s)
- P P Michel
- Andrus Gerontology Center, University of Southern California, Los Angeles 90089
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32
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Michel PP, Dandapani BK, Knusel B, Sanchez-Ramos J, Hefti F. Toxicity of 1-methyl-4-phenylpyridinium for rat dopaminergic neurons in culture: selectivity and irreversibility. J Neurochem 1990; 54:1102-9. [PMID: 1968953 DOI: 10.1111/j.1471-4159.1990.tb01935.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cultures of dissociated embryonic rat mesencephalic cells were exposed to 10 microM 1-methyl-4-phenylpyridinium (MPP+), a concentration shown earlier to result in loss of greater than 85% of tyrosine hydroxylase (TH)-positive neurons without affecting the total number of cells observed by phase-contrast microscopy. To characterize better the selectivity of the toxic action of MPP+, other parameters were measured reflecting survival and function of dopaminergic or nondopaminergic neurons. Exposure of cultures to 10 microM MPP+ for 48 h reduced TH activity to 11% of control values without reducing protein levels. [3H]Dopamine uptake was reduced to less than 4% of control values, whereas the uptake of gamma-[3H]aminobutyric acid ([3H]GABA) was not affected in these cultures. This same treatment failed to reduce the number of cholinergic cells visualized in septal cultures and did not affect either choline acetyltransferase activity or high-affinity choline uptake. To assess for possible recovery of dopaminergic neurons, cultures were exposed to 10, 1.0, or 0.1 microM MPP+ for 48 h and then kept for up to 6 days in MPP(+)-free medium. After exposure to 10 microM MPP+, the number of TH-positive neurons, their neurite density, TH activity, and [3H]dopamine uptake remained at constant, reduced levels throughout the period of observation after termination of exposure, whereas GABA uptake remained normal. Treatment with lower concentrations of MPP+, i.e., 1.0 and 0.1 microM, induced less pronounced dopaminergic toxic effects. However, no recovery was seen after posttreatment incubation in toxin-free medium. These findings provide evidence that MPP+ treatment results in highly selective and irreversible toxicity for cultured dopaminergic neurons.
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Affiliation(s)
- P P Michel
- Department of Neurology, University of Miami, Florida
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Benitez J, Ladero JM, Jimenez-Jimenez FJ, Martinez C, Puerto AM, Valdivielso MJ, Llerena A, Cobaleda J, Muñoz JJ. Oxidative polymorphism of debrisoquine in Parkinson's disease. J Neurol Neurosurg Psychiatry 1990; 53:289-92. [PMID: 2341841 PMCID: PMC1014165 DOI: 10.1136/jnnp.53.4.289] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Oxidative phenotype and metabolic ratio (MR) of debrisoquine (DBQ) have been determined in 87 patients with Parkinson's disease and in 556 healthy control subjects. Three patients (3.45%) and 34 control subjects (6.12%), having an MR greater than 12.6, were classified as poor metabolisers (PM) of DBQ (ns). The distribution of MR values in the 84 Parkinsonian patients classified as extensive metabolisers (EM) showed a less efficient oxidative rate when compared with controls of the same phenotype (p less than 0.001). This difference may be due to enzymatic inhibition caused by drug treatment in 40 of these patients. As in patients not taking any drug known to inhibit the oxidation of DBQ, distribution of MR values was not different from that in controls. A negative correlation (r = -0.36, p less than 0.02) was found between MR of DBQ and age at onset of disease in patients free of drugs known to interact with DBQ metabolism. A higher rate of DBQ oxidation could be a genetic factor that delays the clinical onset of Parkinson's disease in predisposed people.
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Affiliation(s)
- J Benitez
- Department of Pharmacology, University of Extremadura, Badajoz, Spain
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34
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Barnes NM, Cheng CH, Costall B, Naylor RJ. The relative abilities of MPTP and MPP+ to compete with [3H]dopamine for the rat and marmoset striatal dopamine uptake site. Biochem Pharmacol 1990; 39:809-11. [PMID: 2306287 DOI: 10.1016/0006-2952(90)90166-i] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- N M Barnes
- Postgraduate Studies in Pharmacology, School of Pharmacy, University of Bradford, West Yorkshire, U.K
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35
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Snyder JW, Kyle ME, Ferraro TN. L-carnitine delays the killing of cultured hepatocytes by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Arch Biochem Biophys 1990; 276:132-8. [PMID: 2297220 DOI: 10.1016/0003-9861(90)90019-u] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The role of fatty acid metabolism in chemical-dependent cell injury is poorly understood. Addition of L-carnitine to the incubation medium of cultured hepatocytes delayed cell killing initiated by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Protection by L-carnitine was stereospecific and observed as late as 1 h following addition of MPTP. D-Carnitine, but not iodoacetate, reversed the L-carnitine effect. Monoamine oxidase A and B activities, MPTP/N-methyl-4-phenyl-pyridinium levels, and MPTP-dependent loss of mitochondrial membrane potential measured by release of [3H]triphenylmethylphosphonium were not altered by addition of L-carnitine. Significant changes in MPTP-induced depletion of total cellular ATP did not occur with excess L-carnitine. Although the mechanism of cytoprotection exerted by L-carnitine remains unresolved, the data suggest that L-carnitine does not significantly alter: (i) mitochondrial-dependent bioactivation of MPTP; (ii) MPTP-dependent loss of mitochondrial membrane potential; or (iii) MPTP-mediated depletion of total cellular ATP content. We conclude that alterations of fatty acid metabolism may contribute to the toxic consequences of exposure to MPTP. Moreover, the lack of L-carnitine-mediated cytoprotection of monolayers incubated with 4-phenylpyridine or potassium cyanide suggests: (i) a link between fatty acid metabolism and mitochondrial membrane-mediated, bioactivation-dependent cell killing; and (ii) that inhibition of NADH dehydrogenase may not totally explain the mechanism of MPTP cytotoxicity.
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MESH Headings
- 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine/analysis
- 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine/pharmacology
- 1-Methyl-4-phenylpyridinium/analysis
- Adenosine Triphosphate/metabolism
- Animals
- Carnitine/pharmacology
- Cell Survival/drug effects
- Cells, Cultured
- Kinetics
- Liver/cytology
- Liver/drug effects
- Liver/metabolism
- Male
- Membrane Potentials
- Mitochondria, Liver/metabolism
- Mitochondria, Liver/physiology
- Monoamine Oxidase/metabolism
- Phenylephrine/pharmacology
- Potassium Cyanide/pharmacology
- Rats
- Rats, Inbred Strains
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Affiliation(s)
- J W Snyder
- Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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36
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Abstract
Monoamine oxidase (EC 1.4.3.4) and aldehyde dehydrogenase (EC 1.2.1.3) activities were compared in the liver mitochondria of male and female rats. Monoamine oxidase activity using benzylamine as a substrate was significantly higher in males as compared with females: 1.45 versus 0.74 mumols/mg mitochondrial protein/hr, respectively. Monoamine oxidase activity using tyramine as a substrate and aldehyde dehydrogenase activity were the same in males and females. Monoamine oxidase-tyramine and aldehyde dehydrogenase activities did not vary with the different phases of the estrous cycle in the female but the activity of monoamine oxidase-benzylamine did; rats in the proestrous phase had the highest activity and those in the estrous phase had the lowest.
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Affiliation(s)
- S C Turan
- Center of Alcohol Studies, Rutgers University, Piscataway, NJ 08855-0969
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37
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Turan SC, Shah P, Pietruszko R. Inactivation of aldehyde dehydrogenase in intact rat liver mitochondria by dopamine. Alcohol 1989; 6:455-60. [PMID: 2597348 DOI: 10.1016/0741-8329(89)90051-7] [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: 01/01/2023]
Abstract
Aldehyde dehydrogenase (EC 1.2.1.3) within isolated rat liver mitochondria was inactivated by incubation with dopamine. Concurrent with this inactivation, incorporation of radioactivity from 14C-labelled dopamine into three mitochondrial matrix proteins (subunit mol.wt. = 120,000; 54,000; 20,000 daltons) occurred. The 54,000 mol.wt. protein also interacted with antihuman mitochondrial aldehyde dehydrogenase antibody. Inactivation of aldehyde dehydrogenase by dopamine occurred more readily in females than in males. Use of monoamine oxidase (EC 1.4.3.4) inhibitors (deprenyl and clorgyline) partially protected against inactivation. Monoamine oxidase catalyzed conversion of to 3,4-dihydroxyphenylacetaldehyde only partially accounted for aldehyde dehydrogenase activity loss.
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Affiliation(s)
- S C Turan
- Center of Alcohol Studies, Rutgers University, Piscataway, NJ 08855-0969
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38
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Scriba GK, Borchardt RT. Metabolism of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) by bovine brain microvessel endothelial cells. Brain Res 1989; 501:175-8. [PMID: 2804693 DOI: 10.1016/0006-8993(89)91039-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Incubation of bovine brain microvessel endothelial cell monolayers with the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine led to the monoamine oxidase (MAO)-mediated formation of the oxidative metabolites 1-methyl-4-phenyl-2,3-dihydropyridine and 1-methyl-4-phenylpyridine (MPP+). The flux of low nanomolar concentrations of [3H]MPP+ across endothelial cell monolayers appeared to be restricted, probably due to the oxidation by MAO. [3H]MPP+ did not significantly cross endothelial cell monolayers.
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Affiliation(s)
- G K Scriba
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Kansas, Lawrence 66045
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39
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Lyles GA, Marshall CM, Flucker CJ. Comparative ex vivo inhibitory effects of (E)-2-(3,4-dimethoxyphenyl)-3-fluoroallylamine (MDL 72145) on amine oxidase activities in the rat. Biochem Pharmacol 1989; 38:2937-40. [PMID: 2775316 DOI: 10.1016/0006-2952(89)90456-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- G A Lyles
- Department of Pharmacology and Clinical Pharmacology University of Dundee Ninewells Hospital and Medical School, U.K
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40
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Deutch AY, Rosin DL, Goldstein M, Roth RH. 3-Acetylpyridine-induced degeneration of the nigrostriatal dopamine system: an animal model of olivopontocerebellar atrophy-associated parkinsonism. Exp Neurol 1989; 105:1-9. [PMID: 2568269 DOI: 10.1016/0014-4886(89)90166-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The effects of 3-acetylpyridine (3-AP) administration to rats on the mesotelencephalic dopamine system were assessed. A single 3-AP injection resulted in biochemical and immunohistochemical evidence of degeneration of the nigrostriatal dopamine system. Six weeks after 3-AP treatment decreases in both striatal dopamine content and the activity of the catecholamine biosynthetic enzyme tyrosine hydroxylase were observed. Immunohistochemical examination suggested a decreased density of striatal tyrosine hydroxylase-immunoreactive fibers and revealed the emergence of a distinctly patchy organization of the dopamine innervation to the dorsolateral striatum. While 3-AP administration resulted in biochemical and anatomical data consistent with the degeneration of nigrostriatal dopamine fibers, no significant changes in dopamine content or the density or pattern of tyrosine hydroxylase-immunoreactive fibers in the anteromedial prefrontal cortex or nucleus accumbens were seen. These data suggest that 3-AP administration may result in a relatively specific degeneration of the nigrostriatal dopamine system. Since 3-AP causes both a profound loss of the climbing fiber input to the cerebellum derived from the inferior olivary nucleus, and the degeneration of nigrostriatal dopamine neurons, 3-AP administration may provide a useful model of olivopontocerebellar atrophy-associated parkinsonism. Moreover, the differences in the neurotoxicity caused by 3-AP and that elicited by another pyridine which causes striatal dopamine depletion (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, MPTP) may offer important insights into the mechanisms of both species- and site-specific pyridine neurotoxins.
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Affiliation(s)
- A Y Deutch
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06508
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41
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Communications. Br J Pharmacol 1989. [DOI: 10.1111/j.1476-5381.1989.tb16851.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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42
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Abstract
The primary pathological change in Parkinson's disease is the destruction of dopamine containing cells in the zona compacta of substantia nigra. The cause of nigral cell death and the underlying mechanism remains elusive. However, the discovery of the selective nigral neurotoxin MPTP and its ability to inhibit mitochondrial energy metabolism via its metabolite MPP+ and to generate superoxide radicals suggests processes by which nigral cell death might occur. Recent postmortem evidence in brain tissue from patients dying with Parkinson's disease also suggests the occurrence of some on-going toxic mechanism. This may be a free radical process stimulated by an excess of iron within substantia nigra coupled to a generalised decrease in brain ferritin content. These data suggest altered iron handling occurs in Parkinson's disease which may lead to the generation of toxic oxygen species such as superoxide radicals. There is also evidence for an inhibition of mitochondrial function in the substantia nigra in patients with Parkinson's disease. So there may be a close association between the actions of the synthetic neurotoxin MPTP and the underlying cause of idiopathic Parkinson's disease.
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Affiliation(s)
- P Jenner
- Parkinson's Disease Society Research Centre, University Department of Neurology, London UK
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43
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COMMUNICATION. Br J Pharmacol 1989. [DOI: 10.1111/j.1476-5381.1989.tb16582.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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44
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45
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Hadjiconstantinou M, Neff NH. Treatment with GM1 ganglioside restores striatal dopamine in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mouse. J Neurochem 1988; 51:1190-6. [PMID: 3262149 DOI: 10.1111/j.1471-4159.1988.tb03086.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 30 mg/kg i.p. daily for 7 days, was administered to mice. This dosage regimen resulted in an approximately 50% reduction of striatal dopamine (DA) level. Chronic administration of GM1 ganglioside (II3NeuAc-GgOse Cer), beginning between 1 to 4 days after terminating MPTP dosing, resulted in partial restoration of the striatal DA level. From dose- and time-response studies, it appeared that 30 mg/kg i.p. of GM1 administered daily for approximately 23 days resulted in an approximately 80% restoration of the DA level and complete restoration of the 3,4-dihydroxyphenylacetic acid (DOPAC) content. This dosage of GM1 also restored the turnover rate of DA in the striatum to near normal. Discontinuing GM1 treatment resulted in a fall of DA and DOPAC levels to values found in mice treated with MPTP alone. There was no evidence for regeneration of nerve terminal amine reuptake in the GM1-treated mice as evaluated by DA uptake into synaptosomes. Our biochemical findings in animals suggest that early GM1 ganglioside treatment of individuals with degenerative diseases of dopaminergic nigrostriatal neurons might be fruitful.
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Affiliation(s)
- M Hadjiconstantinou
- Department of Pharmacology, Ohio State University College of Medicine, Columbus 43210-1239
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46
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Sanchez-Ramos JR, Michel P, Weiner WJ, Hefti F. Selective destruction of cultured dopaminergic neurons from fetal rat mesencephalon by 1-methyl-4-phenylpyridinium: cytochemical and morphological evidence. J Neurochem 1988; 50:1934-44. [PMID: 2897430 DOI: 10.1111/j.1471-4159.1988.tb02500.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Dopaminergic neurons in cultures of dissociated cells from fetal rat mesencephalon were exposed to the principal metabolite of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 1-methyl-4-phenyl-pyridinium ion (MPP+), and several of its structural analogues. At concentrations between 0.01 and 0.1 microM, MPP+ inhibited catecholamine accumulation as visualized by cytofluorescence. Between 0.1 and 10.0 microM, MPP+ resulted in disappearance of tyrosine hydroxylase immunoreactivity without affecting other cells in the cultures. At concentrations higher than 10 microM, MPP+ was toxic to all cells present in the cultures. The effect of low concentrations of MPP+ on catecholamine cytofluorescence of the dopaminergic neurons was partially reversible. The intermediate concentrations produced irreversible structural changes of tyrosine hydroxylase-positive cells, resulting in complete disappearance of these neurons. The morphological changes were specific to the dopaminergic neurons and were not evident in other cells viewed with phase contrast microscopy. Of the structural analogues tested, the 1-ethyl analogue of MPP+ was effective in selectively destroying dopaminergic neurons in our culture system. The antioxidants L-acetyl-carnitine, beta-carotene, and alpha-tocopherol failed to protect against MPP+ neurotoxicity when co-incubated with the toxin.
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Affiliation(s)
- J R Sanchez-Ramos
- Department of Neurology, University of Miami School of Medicine, Florida
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47
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Janssens de Varebeke P, Cavalier R, David-Remacle M, Youdim MB. Formation of the neurotransmitter glycine from the anticonvulsant milacemide is mediated by brain monoamine oxidase B. J Neurochem 1988; 50:1011-6. [PMID: 3346666 DOI: 10.1111/j.1471-4159.1988.tb10566.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Milacemide (2-n-pentylaminoacetamide) is a secondary monoamine that in the brain is converted to glycinamide and glycine. This oxidative reaction was suspected to involve the reaction of monoamine oxidase (MAO). Using mitochondrial preparations from tissues that contain MAO-A and -B (rat brain and liver), MAO-A (human placenta), and MAO-B (human platelet and bovine adrenal chromaffin cell), it has been established that mitochondria containing MAO-B rather than MAO-A oxidize (H2O2 production and glycinamide formation) milacemide. The apparent Km (30-90 microM) for milacemide oxidation by mitochondrial MAO-B preparations is significantly lower than that for milacemide oxidation by mitochondrial MAO-A (approximately 1,300 microM). In vitro MAO-B (l-deprenyl and AGN 1135) rather than MAO-A (clorgyline) selectively inhibited the oxidation of milacemide. These in vitro data are matched by ex vivo experiments where milacemide oxidation was compared to oxidation of serotonin (MAO-A) and beta-phenylethylamine (MAO-B) by brain mitochondria prepared from rats pretreated with clorgyline (0.5-10 mg/kg) and l-deprenyl (0.5-10 mg/kg). Furthermore, in vivo experiment demonstrated that l-deprenyl selectively increased the urinary excretion of [14C]milacemide and the total radioactivity with a concomitant decrease of [14C]glycinamide. Such changes were not observed after clorgyline treatment, but were evident only at doses beyond clorgyline selectivity. The present data therefore demonstrate that milacemide is a substrate for brain MAO-B, and its conversion to glycinamide, further transformed to the inhibitory neurotransmitter, glycine, mediated by this enzyme may contribute to its pharmacological activities.
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Affiliation(s)
- P Janssens de Varebeke
- Searle European Development Centre, Continental Pharma Inc., Mont-Saint-Guibert, Belgium
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48
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Bhatti AR, Burdon J, Williams AC, Pall HS, Ramsden DB. Synthesis and nuclear magnetic resonance spectroscopic, mass spectroscopic, and plasma amine oxidase inhibitory properties of analogues of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. J Neurochem 1988; 50:1097-104. [PMID: 3258016 DOI: 10.1111/j.1471-4159.1988.tb10578.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Seventeen analogues of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine were synthesized using three reaction pathways: condensation of phenols with 1-methyl-4-piperidone, reaction of Grignard reagents with 1-methyl-4-piperidone followed by dehydration of the product, and aminomethylation of olefins. The identity of the products of synthesis was established by nuclear magnetic resonance spectroscopy, mass spectroscopy, and elemental analysis. Thirteen analogues were shown to inhibit the oxidation of benzylamine by bovine plasma amine oxidase. Increasing the length of the aliphatic chain of N-substituted analogues resulted in increased inhibition. In 4-phenyl-substituted analogues, both the position and electronic character of the substituent group affected the degree of inhibition.
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Affiliation(s)
- A R Bhatti
- Department of Medicine, University of Birmingham, Queen Elizabeth Hospital, England
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49
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Sirinathsinghji DJ, Heavens RP, McBride CS. Dopamine-releasing action of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridine (MPP+) in the neostriatum of the rat as demonstrated in vivo by the push-pull perfusion technique: dependence on sodium but not calcium ions. Brain Res 1988; 443:101-16. [PMID: 3258784 DOI: 10.1016/0006-8993(88)91603-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This study examined the effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its metabolite, 1-methyl-4-phenylpyridine (MPP+) on the levels of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) in push-pull perfusates of the striatum in chloral hydrate-anaesthetized rats. In control animals the levels of DA and DOPAC remained stable for at least 6 h and responded rapidly to a depolarizing stimulus of 25 mM K+. This K+-induced DA release was Ca2+-dependent since no stimulation was observed when the striatal sites were perfused with high K+ in a Ca2+-free medium containing 2 mM EGTA thus verifying that the striatal sites were functionally active. MPTP (0.025 and 0.05 microgram/microliter) stimulated DA release and inhibited DOPAC output in a dose-related manner. MPP+ (0.01, 0.025 and 0.05 microgram/microliter) produced a more robust dose-dependent increase in DA levels in the perfusates; however, the level of suppression of DOPAC was similar to that in response to MPTP. The effect of MPP+ on DA release was attenuated by 10(-6) M benztropine, the DA re-uptake blocker and completely inhibited by 10 micrograms/kg i.p. benztropine and 10(-4) M ouabain, the Na+, K+-ATPase (Na pump) inhibitor. However, although these substances prevented the MPP+-induced release of DA, the levels of DOPAC in the perfusates did not recover and remained completely suppressed suggesting that MPP+ may inhibit extraneuronal rather than intraneuronal monoamine oxidase (MAO). Perfusion of the striatal sites with a Ca2+-free medium containing 2 mM EGTA did not prevent the MPP+-induced DA release indicating that MPP+ does not release DA from the striatal DA terminals by the Ca2+-dependent process of exocytosis. The responses of DA and DOPAC to 25 mM K+ were markedly suppressed in animals treated with MPTP and MPP+, these effects being most severe with the highest dose of MPP+. Moreover, this suppression of the K+-induced responses persisted in animals perfused with MPP+ in the presence of benztropine or ouabain, thus suggesting that MPP+ may have potent deleterious membrane effects. These studies have provided the first direct in vivo demonstration of the action of MPTP and MPP+ and the neuropharmacological basis of this action on DA metabolism in the rat striatum. The results show that the elevated levels of DA in the striatal perfusates are due to a direct action of MPTP and MPP+ on the nigrostriatal DA terminals and cannot be fully accounted for solely by their inhibition of MAO activity and/or inhibition of DA re-uptake.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D J Sirinathsinghji
- Department of Neuroendocrinology, AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, U.K
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50
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Kalaria RN, Harik SI. Differential postnatal development of monoamine oxidases A and B in the blood-brain barrier of the rat. J Neurochem 1987; 49:1589-94. [PMID: 3117975 DOI: 10.1111/j.1471-4159.1987.tb01031.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We studied the monoamine metabolizing mitochondrial enzyme, monoamine oxidase (MAO), in cerebral microvessels obtained from postnatally developing rats by measuring the specific binding of [3H]pargyline, an irreversible inhibitor of MAO, and the rate of oxidation of three known MAO substrates: benzylamine, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, and tryptamine. MAO activity increased postnatally, with the greatest increase occurring in the second week and reaching a peak at 3 weeks of age. A concomitant increase in MAO of the cerebral cortex also occurred, but was several-fold less than that of cerebral microvessels. Using clorgyline and deprenyl, relatively specific inhibitors of MAO-A and MAO-B, we showed that cerebral microvessels contain both forms of MAO at all ages, but there was a major preponderance in the postnatal development of MAO-B. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses of rat microvessels after [3H]pargyline binding also showed two distinct bands of radioactivity at all ages. These two bands corresponded to molecular weights of approximately 65,000 for MAO-A and approximately 60,000 for MAO-B. SDS-PAGE results of brain microvessels obtained from 1-, 14-, and 42-day-old rats confirm the differential postnatal development of MAO-B in rat brain microvessels.
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Affiliation(s)
- R N Kalaria
- Department of Neurology, University Hospitals of Cleveland, OH 44106
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