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Kurnik-Łucka M, Latacz G, Bucki A, Rivera-Meza M, Khan N, Konwar J, Skowron K, Kołaczkowski M, Gil K. Neuroprotective Activity of Enantiomers of Salsolinol and N-Methyl-( R)-salsolinol: In Vitro and In Silico Studies. ACS OMEGA 2023; 8:38566-38576. [PMID: 37867702 PMCID: PMC10586258 DOI: 10.1021/acsomega.3c05527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/21/2023] [Indexed: 10/24/2023]
Abstract
Salsolinol (1-methyl-1,2,3,4-tetrahydroisoquinoline-6,7-diol) is a close structural analogue of dopamine with an asymmetric center at the C1 position, and its presence in vivo, both in humans and rodents, has already been proven. Yet, given the fact that salsolinol colocalizes with dopamine-rich regions and was first detected in the urine of Parkinson's disease patients, its direct role in the process of neurodegeneration has been proposed. Here, we report that R and S enantiomers of salsolinol, which we purified from commercially available racemic mixture by means of high-performance liquid chromatography, exhibited neuroprotective properties (at the concentration of 50 μM) toward the human dopaminergic SH-SY5Y neuroblastoma cell line. Furthermore, within the study, we observed no toxic effect of N-methyl-(R)-salsolinol on SH-SY5Y neuroblastoma cells up to the concentration of 750 μM, either. Additionally, our molecular docking analysis showed that enantiomers of salsolinol should exhibit a distinct ability to interact with dopamine D2 receptors. Thus, we postulate that our results highlight the need to acknowledge salsolinol as an active dopamine metabolite and to further explore the neuroregulatory role of enantiomers of salsolinol.
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Affiliation(s)
- Magdalena Kurnik-Łucka
- Department
of Pathophysiology, Jagiellonian University
Medical College, 31-008 Krakow, Poland
| | - Gniewomir Latacz
- Department
of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, 31-008 Krakow, Poland
| | - Adam Bucki
- Department
of Medicinal Chemistry, Jagiellonian University
Medical College, 31-008 Krakow, Poland
| | - Mario Rivera-Meza
- Laboratory
of Experimental Pharmacology, Faculty of Chemical Sciences and Pharmaceutical
Sciences, University of Chile, 8380494 Santiago, Chile
| | - Nadia Khan
- Department
of Pathophysiology, Jagiellonian University
Medical College, 31-008 Krakow, Poland
- Department
of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, 31-008 Krakow, Poland
| | - Jahnobi Konwar
- Department
of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, 31-008 Krakow, Poland
| | - Kamil Skowron
- Department
of Pathophysiology, Jagiellonian University
Medical College, 31-008 Krakow, Poland
| | - Marcin Kołaczkowski
- Department
of Medicinal Chemistry, Jagiellonian University
Medical College, 31-008 Krakow, Poland
| | - Krzysztof Gil
- Department
of Pathophysiology, Jagiellonian University
Medical College, 31-008 Krakow, Poland
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Stereoselectivity in the Membrane Transport of Phenylethylamine Derivatives by Human Monoamine Transporters and Organic Cation Transporters 1, 2, and 3. Biomolecules 2022; 12:biom12101507. [PMID: 36291716 PMCID: PMC9599461 DOI: 10.3390/biom12101507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 10/12/2022] [Accepted: 10/13/2022] [Indexed: 11/24/2022] Open
Abstract
Stereoselectivity is well known and very pronounced in drug metabolism and receptor binding. However, much less is known about stereoselectivity in drug membrane transport. Here, we characterized the stereoselective cell uptake of chiral phenylethylamine derivatives by human monoamine transporters (NET, DAT, and SERT) and organic cation transporters (OCT1, OCT2, and OCT3). Stereoselectivity differed extensively between closely related transporters. High-affinity monoamine transporters (MATs) showed up to 2.4-fold stereoselective uptake of norepinephrine and epinephrine as well as of numerous analogs. While NET and DAT preferentially transported (S)-norepinephrine, SERT preferred the (R)-enantiomer. In contrast, NET and DAT showed higher transport for (R)-epinephrine and SERT for (S)-epinephrine. Generally, MAT stereoselectivity was lower than expected from their high affinity to several catecholamines and from the high stereoselectivity of some inhibitors used as antidepressants. Additionally, the OCTs differed strongly in their stereoselectivity. While OCT1 showed almost no stereoselective uptake, OCT2 was characterized by a roughly 2-fold preference for most (R)-enantiomers of the phenylethylamines. In contrast, OCT3 transported norphenylephrine and phenylephrine with 3.9-fold and 3.3-fold preference for their (R)-enantiomers, respectively, while the para-hydroxylated octopamine and synephrine showed no stereoselective OCT3 transport. Altogether, our data demonstrate that stereoselectivity is highly transporter-to-substrate specific and highly diverse even between homologous transporters.
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DNA Dyes-Highly Sensitive Reporters of Cell Quantification: Comparison with Other Cell Quantification Methods. Molecules 2021; 26:molecules26185515. [PMID: 34576986 PMCID: PMC8465179 DOI: 10.3390/molecules26185515] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 12/25/2022] Open
Abstract
Cell quantification is widely used both in basic and applied research. A typical example of its use is drug discovery research. Presently, plenty of methods for cell quantification are available. In this review, the basic techniques used for cell quantification, with a special emphasis on techniques based on fluorescent DNA dyes, are described. The main aim of this review is to guide readers through the possibilities of cell quantification with various methods and to show the strengths and weaknesses of these methods, especially with respect to their sensitivity, accuracy, and length. As these methods are frequently accompanied by an analysis of cell proliferation and cell viability, some of these approaches are also described.
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Voon SM, Ng KY, Chye SM, Ling APK, Voon KGL, Yap YJ, Koh RY. The Mechanism of Action of Salsolinol in Brain: Implications in Parkinson's Disease. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2021; 19:725-740. [PMID: 32881676 DOI: 10.2174/1871527319666200902134129] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 07/26/2020] [Accepted: 07/29/2020] [Indexed: 11/22/2022]
Abstract
1-Methyl-1,2,3,4-tetrahydroisoquinoline-6,7-diol, commonly known as salsolinol, is a compound derived from dopamine. It was first discovered in 1973 and has gained attention for its role in Parkinson's disease. Salsolinol and its derivatives were claimed to play a role in the pathogenesis of Parkinson's disease as a neurotoxin that induces apoptosis of dopaminergic neurons due to its structural similarity to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its ability to induce Parkinsonism. In this article, we discussed the biosynthesis, distribution and blood-brain barrier permeability of salsolinol. The roles of salsolinol in a healthy brain, particularly the interactions with enzymes, hormone and catecholamine, were reviewed. Finally, we discussed the involvement of salsolinol and its derivatives in the pathogenesis of Parkinson's disease.
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Affiliation(s)
- Shee Man Voon
- Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Kuala Lumpur, Malaysia
| | - Khuen Yen Ng
- School of Pharmacy, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Soi Moi Chye
- Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Kuala Lumpur, Malaysia
| | - Anna Pick Kiong Ling
- Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Kuala Lumpur, Malaysia
| | - Kenny Gah Leong Voon
- Pathology Division, School of Medicine, International Medical University, Kuala Lumpur, Malaysia
| | - Yiing Jye Yap
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Rhun Yian Koh
- Division of Applied Biomedical Science and Biotechnology, School of Health Sciences, International Medical University, Kuala Lumpur, Malaysia
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Cui L, Wang X, Sun B, Xia T, Hu S. Predictive Metabolomic Signatures for Safety Assessment of Metal Oxide Nanoparticles. ACS NANO 2019; 13:13065-13082. [PMID: 31682760 DOI: 10.1021/acsnano.9b05793] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The widespread use of metal oxide nanoparticles (MOx NPs) poses a risk of exposure that may lead to adverse health effects on humans. Even though a number of toxicological methodologies are available for assessing nanotoxicity, the effect of MOx NPs on cell metabolism in vitro and in vivo remains largely unknown, especially under the exposure to low-dose or supposedly low-toxicity MOx NPs. In this study, liquid chromatography-mass spectrometry (LC-MS) based metabolomics was used to reveal significantly altered metabolites and metabolic pathways in human bronchial epithelial cells exposed to four different types of MOx NPs (ZnO, SiO2, TiO2, and CeO2) at both high (25 μg/mL) and low (12.5 μg/mL) doses. We demonstrated that high-dose ZnO NPs caused severe cytotoxicity with altered metabolism of amino acids, nucleotides, nucleosides, tricarboxylic acid cycle, lipids, inflammation/redox, and fatty acid oxidation, as well as the elevation of toxic and DNA damage related metabolites. Fewer metabolomic alterations were induced by low-dose ZnO NPs. However, most metabolites significantly altered by high-dose ZnO NPs were also slightly changed by low-dose ZnO NPs. On the other hand, the cells exposed to SiO2, TiO2, and CeO2 NPs at either high or low dose displayed low cytotoxicity with similar metabolomic alterations, although each type of NPs induced distinct changes of certain metabolites. These three NPs significantly affected the metabolic pathways of sphingosine-1-phosphate, fatty acid oxidation, folate cycle, inflammation/redox, and lipid metabolism. In addition, dose-dependent effects were observed for a number of metabolites significantly altered by respective MOx NPs. Representative metabolites of the significantly altered metabolic pathways were successfully validated in vitro using enzymatic assays. More importantly, these representative metabolites were further validated in a mouse model after lung exposure to respective NPs, indicating that in vitro metabolomic findings may be used to effectively predict the toxicological effects in vivo. Despite functional assay results demonstrating that the changes in cellular functions were largely reflected by the metabolomic alterations, LC-MS-based metabolomics was sensitive enough to detect the subtle metabolomic changes when functional cellular assays showed no significant difference. Collectively, our studies have unveiled potential metabolic mechanisms of MOx NP-induced nanotoxicity in lung epithelial cells and demonstrated the sensitivity and feasibility of using metabolomic signatures to understand and predict nanotoxicity in vivo.
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Affiliation(s)
- Li Cui
- School of Dentistry and Jonsson Comprehensive Cancer Center , University of California , Los Angeles , California 90095 , United States
| | - Xiang Wang
- Division of NanoMedicine, Department of Medicine, California NanoSystems Institute , University of California , Los Angeles , California 90095 , United States
| | - Bingbing Sun
- State Key Laboratory of Fine Chemicals, School of Chemical Engineering , Dalian University of Technology , 2 Linggong Road , 116024 , Dalian , China
| | - Tian Xia
- Division of NanoMedicine, Department of Medicine, California NanoSystems Institute , University of California , Los Angeles , California 90095 , United States
| | - Shen Hu
- School of Dentistry and Jonsson Comprehensive Cancer Center , University of California , Los Angeles , California 90095 , United States
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6
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Kurnik-Łucka M, Panula P, Bugajski A, Gil K. Salsolinol: an Unintelligible and Double-Faced Molecule-Lessons Learned from In Vivo and In Vitro Experiments. Neurotox Res 2017; 33:485-514. [PMID: 29063289 PMCID: PMC5766726 DOI: 10.1007/s12640-017-9818-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 08/19/2017] [Accepted: 09/08/2017] [Indexed: 12/29/2022]
Abstract
Salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline) is a tetrahydroisoquinoline derivative whose presence in humans was first detected in the urine of Parkinsonian patients on l-DOPA (l-dihydroxyphenylalanine) medication. Thus far, multiple hypotheses regarding its physiological/pathophysiological roles have been proposed, especially related to Parkinson’s disease or alcohol addiction. The aim of this review was to outline studies related to salsolinol, with special focus on in vivo and in vitro experimental models. To begin with, the chemical structure of salsolinol together with its biochemical implications and the role in neurotransmission are discussed. Numerous experimental studies are summarized in tables and the most relevant ones are stressed. Finally, the ability of salsolinol to cross the blood–brain barrier and its possible double-faced neurobiological potential are reviewed.
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Affiliation(s)
- Magdalena Kurnik-Łucka
- Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 30-121, Krakow, Poland.
| | - Pertti Panula
- Department of Anatomy and Neuroscience Centre, University of Helsinki, Helsinki, Finland
| | - Andrzej Bugajski
- Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 30-121, Krakow, Poland
| | - Krzysztof Gil
- Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 30-121, Krakow, Poland
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Rampersad SN. Multiple applications of Alamar Blue as an indicator of metabolic function and cellular health in cell viability bioassays. SENSORS (BASEL, SWITZERLAND) 2012; 12:12347-60. [PMID: 23112716 PMCID: PMC3478843 DOI: 10.3390/s120912347] [Citation(s) in RCA: 611] [Impact Index Per Article: 50.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 08/21/2012] [Accepted: 08/31/2012] [Indexed: 02/07/2023]
Abstract
Accurate prediction of the adverse effects of test compounds on living systems, detection of toxic thresholds, and expansion of experimental data sets to include multiple toxicity end-point analysis are required for any robust screening regime. Alamar Blue is an important redox indicator that is used to evaluate metabolic function and cellular health. The Alamar Blue bioassay has been utilized over the past 50 years to assess cell viability and cytotoxicity in a range of biological and environmental systems and in a number of cell types including bacteria, yeast, fungi, protozoa and cultured mammalian and piscine cells. It offers several advantages over other metabolic indicators and other cytotoxicity assays. However, as with any bioassay, suitability must be determined for each application and cell model. This review seeks to highlight many of the important considerations involved in assay use and design in addition to the potential pitfalls.
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Affiliation(s)
- Sephra N Rampersad
- Department of Life Sciences, The University of the West Indies, West Indies, St Augustine, Trinidad and Tobago.
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8
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Posser T, de Paula MT, Franco JL, Leal RB, da Rocha JBT. Diphenyl diselenide induces apoptotic cell death and modulates ERK1/2 phosphorylation in human neuroblastoma SH-SY5Y cells. Arch Toxicol 2010; 85:645-51. [PMID: 20924558 DOI: 10.1007/s00204-010-0602-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Accepted: 09/22/2010] [Indexed: 01/06/2023]
Abstract
Diphenyl diselenide (PhSe)(2) is a synthetic organoselenium compound displaying glutathione peroxidase-like activity. Protective and antioxidant potential of (PhSe)(2) have been extensively investigated in in vivo and in vitro studies. In spite of this, there is a lack of studies addressed to the investigation of potential cytotoxic effect and signaling pathways modulated by this compound. Herein, we aimed to analyze the effects of 24-h treatment with (PhSe)(2) on cell viability and a possible modulation of signaling pathways in human neuroblastoma cell line SH-SY5Y. For this purpose, cells were incubated with (PhSe)(2) (0.3-30 μM) for 24 h and cell viability, apoptotic cell death and modulation of MAPKs (ERK1/2 and p38(MAPK)), and PKC substrates phosphorylation was determined. (PhSe)(2) treatment significantly decreased cell viability and increased the number of apoptotic cells with induction of PARP cleavage. An increase in ERK1/2 phosphorylation was observed at (PhSe)(2) 3 μM. In contrast, higher concentrations of the chalcogenide inhibited ERK1/2, p38(MAPK) and PKC substrate phosphorylation. Pre-treatment with ERK1/2 inhibitor, U0126, increased cell susceptibility to (PhSe)(2). Together, these data indicate a cytotoxic potential of (PhSe)(2) in a neuronal cell line, which appears to be mediated by the ERK1/2 pathway.
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Affiliation(s)
- Thaís Posser
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, 97105-900, Brazil.
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9
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Roles of db-cAMP, IBMX and RA in aspects of neural differentiation of cord blood derived mesenchymal-like stem cells. PLoS One 2010; 5:e9398. [PMID: 20195526 PMCID: PMC2827567 DOI: 10.1371/journal.pone.0009398] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Accepted: 02/04/2010] [Indexed: 02/01/2023] Open
Abstract
Mesenchymal stem cells (MSCs) have multilineage differentiation potential which includes cell lineages of the central nervous system; hence MSCs might be useful in the treatment of neurodegenerative diseases such as Parkinson's disease. Although mesenchymal stem cells have been shown to differentiate into the neural lineage, there is still little knowledge about the underlying mechanisms of differentiation particularly towards specialized neurons such as dopaminergic neurons. Here, we show that MSCs derived from human umbilical cord blood (MSChUCBs) are capable of expressing tyrosine hydroxylase (TH) and Nurr1, markers typically associated with DA neurons. We also found differential phosphorylation of TH isoforms indicating the presence of post-translational mechanisms possibly activating and modifying TH in MSChUCB. Furthermore, functional dissection of components in the differentiation medium revealed that dibutyryl-cAMP (db-cAMP), 3-isobutyl-1-methylxanthine (IBMX) and retinoic acid (RA) are involved in the regulation of Nurr1 and Neurofilament-L expression as well as in the differential phosphorylation of TH. We also demonstrate a possible inhibitory role of the protein kinase A signaling pathway in the phosphorylation of specific TH isoforms.
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The influence of acute and chronic administration of 1,2-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline on the function of the nigrostriatal dopaminergic system in rats. Neuroscience 2008; 156:973-86. [DOI: 10.1016/j.neuroscience.2008.08.050] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 08/07/2008] [Accepted: 08/23/2008] [Indexed: 11/23/2022]
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Vilariño N, Nicolaou KC, Frederick MO, Cagide E, Alfonso C, Alonso E, Vieytes MR, Botana LM. Azaspiracid substituent at C1 is relevant to in vitro toxicity. Chem Res Toxicol 2008; 21:1823-31. [PMID: 18707138 DOI: 10.1021/tx800165c] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The azaspiracids are a group of marine toxins recently described that currently includes 20 analogues. Not much is known about their mechanism of action, although effects on some cellular functions have been found in vitro. We used the reported effects on cell viability, actin cytoskeleton, and caspase activation to study the structure-activity relationship of AZA-1 and AZA-2 and the role of the carboxylic acid moiety in toxicity. AZA-1, AZA-2, and the synthetic AZA-2-methyl ester (AZA-2-ME), where the C1 carboxylic acid moiety of AZA-2 was esterified to the corresponding methyl ester moiety, induced a reduction of cell viability in neuroblastoma and hepatocyte cell lines with similar potency and kinetics. Interestingly, the mast cell line HMC-1 was resistant to AZA-induced cytotoxicity. Actin cytoskeleton alterations and caspase activation appeared after treatment with AZA-1, AZA-2, AZA-2-ME, and biotin-AZA-2 (AZA-2 labeled with biotin at C1) in neuroblastoma cells with similar qualitative, quantitative, and kinetics characteristics. Irreversibility of AZA effects on the actin cytoskeleton and cell morphology after short incubations with the toxin were common to AZA-1, AZA-2, and AZA-2-ME; however, 10-fold higher concentrations of biotin-AZA-2 were needed for irreversible effects. AZA-2-ME was rapidly metabolized in the cell to AZA-2, while transformation of biotin-AZA-2 into AZA-2 was less efficient, which explains the different potency in short exposure times. The moiety present at C1 is related to AZA toxicity in vitro. However, the presence of a methyl moiety at C8 is irrelevant to AZA toxicity since AZA-1 and AZA-2 were equipotent regardless of the readout effect.
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Affiliation(s)
- Natalia Vilariño
- Departamento de Farmacologia, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain
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12
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Luchetti S, di Michele F, Romeo E, Brusa L, Bernardi G, Cummings BJ, Longone P. Comparative non-radioactive RT-PCR assay: An approach to study the neurosteroids biosynthetic pathway in humans. J Neurosci Methods 2006; 153:290-8. [PMID: 16378642 DOI: 10.1016/j.jneumeth.2005.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2005] [Revised: 11/10/2005] [Accepted: 11/10/2005] [Indexed: 10/25/2022]
Abstract
Polymerase chain reaction (PCR) is a powerful tool for qualitative evaluation of nucleic acid expression. PCR has been widely applied to measure DNA and RNA messages expression. Neurosteroids synthesized in the nervous system are potent modulators of synaptic activity and have been implicated in several neuropsychiatric disorders. To examine the possibility of an altered expression of the neurosteroidogenic metabolic enzymes in neurological diseases (like Parkinson's disease, PD) we developed a comparative non-radioactive RT-PCR assay to detect the mRNA levels of the peripheral benzodiazepine receptor, the 5alpha-reductase type 1 and 3alpha-hydroxysteroid-oxidoreductase type 1 and 2 in lymphocytes obtained from PD patients. The results were compared with that obtained from simultaneous quantification of progesterone, 5alpha-dihydroprogesterone and 3alpha,5alpha-tetrahydroprogesterone in the plasma and cerebro-spinal fluid of the same individuals using a gas chromatography mass spectrometry (GC/MS) technique. We found a significant decrease of the rate-limiting enzyme 5alpha-R1 along with a significant decrease in plasma and CSF of the 3alpha,5alpha-tetrahydroprogesterone and of the 5alpha-dihydroprogesterone. Comparative RT-PCR assay, along with complimentary techniques (i.e. GC/MS), has the sensitivity, selectivity and dynamic range to allow specific and reliable quantization of the enzymes involved in the neurosteroids pathway and represent a valuable tool to assess their expression in human neuropsychiatric conditions.
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Gardner JL, Doi AM, Pham RT, Huisden CM, Gallagher EP. Ontogenic differences in human liver 4-hydroxynonenal detoxification are associated with in vitro injury to fetal hematopoietic stem cells. Toxicol Appl Pharmacol 2003; 191:95-106. [PMID: 12946646 DOI: 10.1016/s0041-008x(03)00220-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
4-hydroxynonenal (4HNE) is a highly mutagenic and cytotoxic alpha,beta-unsaturated aldehyde that can be produced in utero during transplacental exposure to prooxidant compounds. Cellular protection against 4HNE injury is provided by alcohol dehydrogenases (ADH), aldehyde reductases (ALRD), aldehyde dehydrogenases (ALDH), and glutathione S-transferases (GST). In the present study, we examined the comparative detoxification of 4HNE by aldehyde-metabolizing enzymes in a panel of adult and second-trimester prenatal liver tissues and report the toxicological ramifications of ontogenic 4HNE detoxification in vitro. The initial rates of 4HNE oxidation and reduction were two- to fivefold lower in prenatal liver subcellular fractions as compared to adult liver, and the rates of GST conjugation of 4HNE were not detectable in either prenatal or adult cytosolic fractions. GSH-affinity purification of hepatic cytosol yielded detectable and roughly equivalent rates of GST-4HNE conjugation for the two age groups. Consistent with the inefficient oxidative and reductive metabolism of 4HNE in prenatal liver, cytosolic fractions prepared from prenatal liver exhibited a decreased ability to protect against 4HNE-protein adduct formation relative to adults. Prenatal liver hematopoietic stem cells (HSC), which constitute a significant percentage of prenatal liver cell populations, exhibited ALDH activities toward 4HNE, but little reductive or conjugative capacity toward 4HNE through ALRD, ADH, and GST. Cultured HSC exposed to 5 microM 4HNE exhibited a loss in viability and readily formed one or more high molecular weight 4HNE-protein adduct(s). Collectively, our results indicate that second trimester prenatal liver has a lower ability to detoxify 4HNE relative to adults, and that the inefficient detoxification of 4HNE underlies an increased susceptibility to 4HNE injury in sensitive prenatal hepatic cell targets.
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Affiliation(s)
- James L Gardner
- Department of Physiological Sciences, Center for Environmental and Human Toxicology, P.O. Box 110885, University of Florida, Gainesville, FL 32611, USA
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Naoi M, Maruyama W, Akao Y, Yi H. Dopamine-derived endogenous N-methyl-(R)-salsolinol: its role in Parkinson's disease. Neurotoxicol Teratol 2002; 24:579-91. [PMID: 12200189 DOI: 10.1016/s0892-0362(02)00211-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A dopamine-derived alkaloid, N-methyl-(R)-salsolinol [NM(R)Sal], enantioselectively occurs in human brains and accumulates in the nigrostriatal system. It increases in the cerebrospinal fluid (CSF) of parkinsonian patients and the activity of a neutral (R)-salsolinol [(R)Sal] N-methyltransferase, a key enzyme in the biosynthesis of this toxin, increases in the lymphocytes from parkinsonian patients, suggesting its involvement in the pathogenesis of Parkinson's disease (PD). The studies of animal and cellular models of PD proved that this isoquinoline is selectively cytotoxic to dopamine neurons. Using human dopaminergic SH-SY5Y cells, NM(R)Sal induces apoptosis by the activation of the apoptotic cascade initiated in mitochondria. In this article, we review the recent advance in proving our hypothesis that the dopamine-derived neurotoxin causes the selective depletion of dopamine neurons in PD.
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Affiliation(s)
- Makoto Naoi
- Department of Brain Sciences, Institute of Applied Biochemistry, Yagi Memorial Park, Mitake, 505-0116 Gifu, Japan.
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15
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Surh YJ, Jung YJ, Jang JH, Lee JS, Yoon HR. Iron enhancement of oxidative DNA damage and neuronal cell death induced by salsolinol. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2002; 65:473-488. [PMID: 11936226 DOI: 10.1080/15287390252808127] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A group of naturally occurring isoquinoline alkaloids have been detected in certain regions of mammalian brain. One such compound is salsolinol (SAL; 1-methyl-6, 7-dihydroxy-1,2,3,4-tetrahydroisoquinoline). This endogenous isoquinoline derivative has been considered to be implicated in the pathophysiology of chronic alcoholism and Parkinsonism. The present study deals with the DNA strand scission induced by SAL in the presence of iron. Incubation of phiX174 DNA with SAL and ferric ion led to conversion of the supercoiled DNA to open circular and linear forms, which was inhibited by the iron chelator deferoxamine, catalase, and scavengers of reactive oxygen species. SAL in combination with Fe(III) also produced 8-hydroxydeoxyguanosine in calf thymus DNA. Exposure of PC12 cells to SAL produced concentration-dependent reduction in viability, which was exacerbated by iron and ameliorated by deferoxamine.
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Affiliation(s)
- Young-Joon Surh
- Laboratory of Biochemistry and Molecular Toxicology, College of Pharmacy, Seoul National University, South Korea.
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Storch A, Ott S, Hwang YI, Ortmann R, Hein A, Frenzel S, Matsubara K, Ohta S, Wolf HU, Schwarz J. Selective dopaminergic neurotoxicity of isoquinoline derivatives related to Parkinson's disease: studies using heterologous expression systems of the dopamine transporter. Biochem Pharmacol 2002; 63:909-20. [PMID: 11911843 DOI: 10.1016/s0006-2952(01)00922-4] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Endogenous isoquinoline (IQ) derivatives structurally related to the selective dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its active metabolite 1-methyl-4-phenylpyridine (MPP(+)) may contribute to dopaminergic neurodegeneration in Parkinson's disease. We addressed the importance of the DAT molecule for selective dopaminergic toxicity by testing the differential cytotoxicity of 22 neutral and quaternary compounds from three classes of isoquinoline derivatives (3, IQs; 4,3,4-dihydroisoquinolines and 15, 1,2,3,4-tetrahydroisoquinolines) as well as MPP(+) in non-neuronal and neuronal heterologous expression systems of the DAT gene (human embryonic kidney HEK-293 and mouse neuroblastoma Neuro-2A cells, respectively). Cell death was estimated using the MTT assay and the Trypan blue exclusion method. Nine isoquinolines and MPP(+) showed general cytotoxicity in both parental cell lines after 72hr with half-maximal toxic concentrations (TC(50) values) in the micromolar range. The rank order of toxic potency was: papaverine>salsolinol=tetrahydropapaveroline=1-benzyl-TIQ=norsalsolinol>tetrahydropapaverine>2[N]-methyl-salsolinol>2[N]-methyl-norsalsolinol>2[N]-Me-IQ(+)=MPP(+). Besides MPP(+), only the 2[N]-methylated compounds 2[N]-methyl-IQ(+), 2[N]-methyl-norsalsolinol and 2[N]-methyl-salsolinol showed enhanced cytotoxicity in both DAT expressing cell lines with 2- to 14-fold reduction of TC(50) values compared to parental cell lines. The rank order of selectivity in both cell systems was: MPP(+)>>2[N]-Me-IQ(+)>2[N]-methyl-norsalsolinol=2[N]-methyl-salsolinol. Our results suggest that 2[N]-methylated isoquinoline derivatives structurally related to MPTP/MPP(+) are selectively toxic to dopaminergic cells via uptake by the DAT, and therefore may play a role in the pathogenesis of Parkinson's disease.
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Affiliation(s)
- Alexander Storch
- Department of Neurology, University of Ulm Medical School, Oberer Eselsberg 45, 89081, Ulm, Germany.
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18
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Jung YJ, Youn JY, Ryu JC, Surh YJ. Salsolinol, a naturally occurring tetrahydroisoquinoline alkaloid, induces DNA damage and chromosomal aberrations in cultured Chinese hamster lung fibroblast cells. Mutat Res 2001; 474:25-33. [PMID: 11239960 DOI: 10.1016/s0027-5107(00)00156-1] [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: 10/18/2022]
Abstract
Salsolinol (SAL) is a tetrahydroisoquinoline neurotoxin that has been speculated to contribute to pathophysiology of Parkinson's disease and chronic alcoholism. The compound is also found in certain beverages and food stuffs, including soy sauce, beer and bananas. Despite potential human exposure to SAL and its endogenous formation, little is known about the genotoxic or carcinogenic potential of this substance. In the present investigation, SAL induced DNA damage in cultured Chinese hamster lung (CHL) fibroblasts as assessed by single cell gel electrophoresis (Comet). CHL cells treated with SAL also exhibited higher frequencies of chromosomal aberrations than did vehicle-treated controls. Our recent study has revealed that SAL in combination with Cu(II) causes the strand scission in phiX174 supercoiled DNA [Neurosci. Lett. 238 (1997) 95]. In line with this notion, addition of cupric ion potentiated the DNA damaging and clastogenic activity of SAL. Antioxidant vitamins, such as Vitamin C and Vitamin E, and reduced glutathione inhibited clastogenicity of SAL, suggesting the involvement of reactive oxygen species (ROS) in SAL-induced DNA damage and genotoxicity in CHL cells.
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Affiliation(s)
- Y J Jung
- College of Pharmacy, Seoul National University, Shinlim-dong, Kwanak-gu, 151-742, Seoul, South Korea
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19
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Storch A, Kaftan A, Burkhardt K, Schwarz J. 1-Methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (salsolinol) is toxic to dopaminergic neuroblastoma SH-SY5Y cells via impairment of cellular energy metabolism. Brain Res 2000; 855:67-75. [PMID: 10650131 DOI: 10.1016/s0006-8993(99)02272-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The endogenous neurotoxin 1-methyl-6,7-dihydroxy-1,2,3, 4-tetrahydroisoquinoline (salsolinol), which is structurally similar to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), has been reported to inhibit mitochondrial complex I (NADH-Q reductase) activity as does the MPTP metabolite 1-methyl-4-phenylpyridinium ion (MPP(+)). However, the mechanism of salsolinol leading to neuronal cell death is still unknown. Thus, we correlated indices of cellular energy production and cell viability in human dopaminergic neuroblastoma SH-SY5Y cells after exposure to salsolinol and compared these results with data obtained with MPP(+). Both toxins induce time and dose-dependent decrease in cell survival with IC(50) values of 34 microM and 94 microM after 72 h for salsolinol and MPP(+), respectively. Furthermore, salsolinol and MPP(+) produce a decrease of intracellular net ATP content with IC(50) values of 62 microM and 66 microM after 48 h, respectively. In contrast to MPP(+), salsolinol does not induce an increase of intracellular net NADH content. In addition, enhancing glycolysis by adding D-glucose to the culture medium protects the cells against MPP(+) but not salsolinol induced cellular ATP depletion and cytotoxicity. These results suggest that cell death induced by salsolinol is due to impairment of cellular energy supply, caused in particular by inhibition of mitochondrial complex II (succinate-Q reductase), but not complex I.
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Affiliation(s)
- A Storch
- Department of Neurology, University of Ulm Medical School, Oberer Eselsberg 45, 89081, Ulm, Germany.
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20
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Kostrzewa RM. Review of apoptosis vs. necrosis of substantia nigra pars compacta in Parkinson's disease. Neurotox Res 2000; 2:239-50. [PMID: 16787844 DOI: 10.1007/bf03033797] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The discovery that melanized neurons of the pars compacta of substantia nigra (pcSN) degenerate in the midbrain of human Parkinsonians is nearly a century old, but only in this decade have we gained insights into mechanisms underlying this neuronal loss. Although it had long been assumed that pcSN neurons underwent necrosis, recent (1) in vitro studies on isolated neurons, (2) in vivo studies in animals treated with neurotoxins, and (3) postmortem study of human Parkinsonian brain provide strong evidence that pcSN cells may be lost more from apoptosis (i.e., cell suicide) than from necrosis. This paper gives some historical perspective, but focuses primarily on mechanisms involved in both necrosis and apoptosis of neurons, primarily dopaminergic, and reviews the recent literature relating to apoptosis and apoptotic factors now identified in neurons undergoing neurotoxin-induced death and in postmortem human Parkinsonian brain. The weight of evidence in favor of apoptosis and apoptotic factors in these neurons, provides us with tools needed to develop anti-apoptotic factors that can be targeted to proteins on genes, so that it may be possible to decelerate or prevent the progressive neuronal cell loss in human Parkinsonians or in humans with other neurodegenerative disorders.
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Affiliation(s)
- R M Kostrzewa
- Department of Pharmacology, Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA.
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21
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Abstract
Dopamine neurons in the substantia nigra of human brain are selectively vulnerable and the number decline by aging at 5-10% per decade. Enzymatic and non-enzymatic oxidation of dopamine generates reactive oxygen species, which induces apoptotic cell death in dopamine neurons. Parkinson's disease (PD) is also caused by selective cell death of dopamine neurons in this brain region. The pathogenesis of Parkinson's disease remains to be an enigma, but it was found that an endogenous MPTP-like neurotoxin, 1(R), 2(N)-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline [N-methyl(R)salsolinol, NM(R)Sal], may be one of the pathogenic agents of PD. NM(R)Sal increases in cerebrospinal fluid from untreated parkinsonian patients, and two enzymes, a (R)salsolinol synthase and a neutral N-methyltransferase, synthesize this neurotoxin in the nigro-striatum. The activity of a neutral N-methyltransferase is significantly higher in lymphocytes from parkinsonian patients than in control. The mechanism of cell death by this toxin was proved to be by the induction of apoptosis, by use of dopaminergic SH-SY5Y cells. The apoptosis was suppressed by anti-oxidants, suggesting that the generation of reactive oxygen species may initiate cellular death process. These results indicate that in aging and PD oxidative stress induces degeneration of dopamine neurons, and the antioxidant therapy may delay the decline of dopamine neurons in the brain.
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Affiliation(s)
- M Naoi
- Department of Brain Sciences, Institute of Applied Biochemistry, Mitake, Gifu, Japan.
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22
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Tieu K, Zuo D, Yu P. Differential effects of staurosporine and retinoic acid on the vulnerability of the SH-SY5Y neuroblastoma cells: Involvement of Bcl-2 and p53 proteins. J Neurosci Res 1999. [DOI: 10.1002/(sici)1097-4547(19991101)58:3<426::aid-jnr8>3.0.co;2-f] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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23
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Nappi AJ, Vass E, Collins MA. Contrasting effects of catecholic and O-methylated tetrahydroisoquinolines on hydroxyl radical production. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1434:64-73. [PMID: 10556560 DOI: 10.1016/s0167-4838(99)00175-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Tetrahydroisoquinolines (TIQs) are intraneuronal, catecholamine-derived alkaloids that have been implicated in the etiology of Parkinson's disease and in alcohol related disorders. The in vitro production of the cytotoxic hydroxyl radical (*OH) was recorded during the autoxidation of salsolinol (SAL) and salsolinol-1-carboxylic acid (SAL-1C), but not when these two catecholic TIQs were oxidized by tyrosinase. Significantly higher levels of the radical were produced when these catecholic TIQs were incubated with *OH generating complexes, or with chelated iron. In contrast, mono-O-methylated TIQs such as salsoline (SLN) and salsoline-1-carboxylic acid (SLN-1C) did not generate *OH during autoxidation or when incubated with chelated iron or tyrosinase. Radical production by *OH-generating complexes was reduced in the presence of O-methylated TIQs. The neurotoxicity of TIQs may result from their propensity to autoxidize and generate reactive quinoids and ensuing oxygen radicals. The functional significance of the replacement of a hydroxyl group attached to C-7 of SAL or SAL-1C with a methoxyl group remains to be determined. This single structural modification may prevent mono-O-methylated TIQs from participating in catalytic redox cycling reactions that would otherwise augment *OH production. If true, then O-methylation and other cellular mechanisms that circumvent the autoxidation of catecholamine-derived TIQs may reduce the likelihood of these substances forming cytotoxic quinoids and influencing endogenous *OH-generating reactions.
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Affiliation(s)
- A J Nappi
- Department of Biology, Loyola University Chicago, Chicago, IL 60626, USA.
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24
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Dual fluorescence of the isoquinolinium cation in methanol: time-resolved emission spectra and semiempirical calculations. Chem Phys 1999. [DOI: 10.1016/s0301-0104(98)00403-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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25
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McNaught KS, Carrupt PA, Altomare C, Cellamare S, Carotti A, Testa B, Jenner P, Marsden CD. Isoquinoline derivatives as endogenous neurotoxins in the aetiology of Parkinson's disease. Biochem Pharmacol 1998; 56:921-33. [PMID: 9776302 DOI: 10.1016/s0006-2952(98)00142-7] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The cause of neurodegeneration in Parkinson's disease (PD) remains unknown. However, isoquinoline derivatives structurally related to the selective dopaminergic toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its active metabolite, 1-methyl-4-phenylpyridinim (MPP+), have emerged as candidate endogenous neurotoxins causing nigral cell death in Parkinson's disease. Isoquinoline derivatives are widely distributed in the environment, being present in many plants and foodstuffs, and readily cross the blood-brain barrier. These compounds occur naturally in human brain where they are synthesized by non-enzymatic condensation of biogenic amines (e.g. catecholamines and phenylethylamine) with aldehydes, and are metabolized by cytochrome P450s and N-methyltransferases. In addition, isoquinoline derivatives are oxidized by monoamine oxidases to produce isoquinolinium cations with the concomitant generation of reactive oxygen species. Neutral and quaternary isoquinoline derivatives accumulate in dopaminergic nerve terminals via the dopamine re-uptake system, for which they have moderate to poor affinity as substrates. Several isoquinoline derivatives are selective and more potent inhibitors of NADH ubiquinone reductase (complex I) and alpha-ketoglutarate dehydrogenase activity in mitochondrial fragments than MPP+, and lipophilicity appears to be important for complex I inhibition by isoquinoline derivatives. However, compared with MPP+, isoquinoline derivatives are selective but less potent inhibitors of NADH-linked respiration in intact mitochondria, and this appears to be a consequence of their rate-limiting ability to cross mitochondrial membranes. Although both active and passive processes are involved in the accumulation of isoquinoline derivatives in mitochondria, inhibition of respiration is determined by steric rather than electrostatic properties. Compared with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine or MPP+, isoquinoline derivatives show selective but relatively weak toxicity to dopamine-containing cells in culture and following systemic or intracerebral administration to experimental animals, which appears to be a consequence of poor sequestration of isoquinoline derivatives by mitochondria and by dopamine-containing neurones. In conclusion, the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-like cytotoxic characteristics of isoquinoline derivatives and the endogenous/environmental presence of these compounds make it conceivable that high concentrations of and/or prolonged exposure to isoquinoline derivatives might cause neurodegeneration and Parkinson's disease in humans.
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Affiliation(s)
- K S McNaught
- Neurodegenerative Disease Research Centre, Biomedical Sciences Division, King's College, London, UK
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26
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Wormser U, Raibstein I, Kritzler JS, Nyska A. High-molecular weight serum cytotoxic factor in rats treated with triphenyl phosphite: an approach for biological monitoring. J Pharmacol Toxicol Methods 1998; 39:241-3. [PMID: 9845304 DOI: 10.1016/s1056-8719(98)00018-5] [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: 11/25/2022]
Affiliation(s)
- U Wormser
- Department of Pharmacology, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Israel.
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27
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Naoi M, Maruyama W, Matsubara K, Hashizume Y. A neutral N-methyltransferase activity in the striatum determines the level of an endogenous MPP+-like neurotoxin, 1,2-dimethyl-6,7-dihydroxyisoquinolinium ion, in the substantia nigra of human brains. Neurosci Lett 1997; 235:81-4. [PMID: 9389601 DOI: 10.1016/s0304-3940(97)00723-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
An endogenous MPTP-like dopaminergic neurotoxin, N-methyl(R)salsolinol, increases in the parkinsonian cerebrospinal fluid and accumulates in the human nigro-striatum. An N-methyltransferase specific for (R)salsolinol was found in human brain with optimal pH at 7.0 and 8.5. The correlation of the enzyme activity with the level of N-methyl(R)salsolinol and its oxidation product, 1,2-dimethyl-6,7-dihydroxyisoquinolinium ion was examined in the brain regions. Neutral N-methyltransferase activity in the striatum was found to correlate with the level of the endogenous MPP+-like isoquinolinium ion in the substantia nigra (P < 0.001). Considering that this neutral N-methyltransferase activity increases in parkinsonian lymphocytes, the enzyme may be an endogenous factor in the pathogenesis of Parkinson's disease.
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Affiliation(s)
- M Naoi
- Department of Biosciences, Nagoya Institute of Technology, Japan.
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28
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Abstract
Parkinson's disease is thought to be caused by some unknown endogenous or exogenous factors interacting with genetic dispositions. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is an exogenous neurotoxin producing parkinsonism in humans, monkeys and various animals as the result of monoamine oxidase type B (MAO-B)-catalyzed conversion of it to the 1-methyl-4-phenyl-pyridinium ion (MPP+), which selectively kills the nigrostriatal dopaminergic neurons. Various isoquinoline derivatives were found in the brain of patients with Parkinson's disease. Isoquinoline derivatives have neurochemical properties similar to those of MPTP and they are considered to be the endogenous neurotoxins which cause Parkinson's disease. Among them, tetrahydroisoquinoline (TIQ), 1-benzyl-TIQ, and (R)-1,2-dimethyl-5,6-dihydroxy-TIQ [(R)-N-methyl-salsolinol)] have the most potent neurotoxicity. TIQs, like MPTP, may be activated via N-methylation by N-methyltransferase and oxidation by MAO. TIQs as well as MPP+ inhibit complex I of the electron transport system in mitochondria, thereby reducing ATP formation and producing oxygen radicals. Although the properties of TIQs are similar to those of MPTP, the neurotoxicity of TIQs is weaker than that of MPTP. Since Parkinson's disease is a slowly progressing neurodegenerative disease, long term neurotoxic effects of IQs remain to be further examined in primates.
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Affiliation(s)
- T Nagatsu
- Institute for Comprehensive Medical Science, School of Medicine, Fujita Health University, Toyoake, Aichi, Japan.
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29
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Castagnoli N, Rimoldi JM, Bloomquist J, Castagnoli KP. Potential metabolic bioactivation pathways involving cyclic tertiary amines and azaarenes. Chem Res Toxicol 1997; 10:924-40. [PMID: 9305573 DOI: 10.1021/tx970096j] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A major theme explored in this review is the MAO-and cytochrome P450-catalyzed alpha-carbon oxidations of selected cyclic tertiary amines to give iminium metabolites that undergo further chemical modifications to form known or potentially toxic products. The most dramatic illustration of this type of bioactivation process is the conversion of the parkinsonian-inducing neurotoxin MPTP (23) by brain MAO-B to the iminium (dihydropyridinium) metabolite 24 which is oxidized further to the pyridinium species MPP+ (25). The selective destruction of nigrostriatal neurons by MPP+ is dependent on a unique sequence of events (transport into the nerve terminals by the dopamine transporter, localization in the inner mitochondrial membrane by electromotive forces, and inhibition of complex I of the mitochondrial electron transport chain) that, fortunately, are unlikely to be encountered with many substances. A second example of a well-documented metabolic bioactivation sequence involves the highly toxic pyrrolizidine alkaloids (102). These compounds undergo cytochrome P450-catalyzed alpha-carbon oxidation which converts the 3-pyrrolinyl moiety present in the parent alkaloids into a pyrrolyl-containing metabolite (105). The presence of labile functional groups results in the spontaneous conversion of 105 to reactive electrophilic products (106 and 108) that undergo Michael addition reactions with nucleophiles on biomacromolecules leading to a variety of toxic outcomes. Less clearly defined are the potential contributions to neurodegenerative processes that may be mediated by low-level, long term exposure to less potent toxins. Examples of potential proneurotoxins are the endogenously formed tetrahydroisoquinolines (such as 40-50) and tetrahydro-beta-carbolines (such as 54) that may be biotransformed to neurotoxic isoquinolinium (such as 51) and beta-carbolinium (such as 52) species in the brain. A similar argument can be made for 4-piperidinols (compounds that are at the same oxidation state as the tetrahydropyridines) which may be metabolized via iminium intermediates to amino enols that spontaneously convert to dihydropyridinium species and hence to pyridinium metabolites (67-->68-->69-->70-->71, Scheme 10). This type of reaction sequence has been well documented with the parkinsonian-inducing neuroleptic agent haloperidol (72) which is metabolized in humans, baboons, and rodents to the pyridinium species HPP+ (75), a potent inhibitor of mitochondrial respiration. Finally, an appreciation of the alpha-carbon oxidations of fully reduced azacycles such as (S)-nicotine (61) and phencyclidine (82) to chemically reactive metabolites that form covalent adducts with proteins, including the enzymes that are responsible for their formation, may prove of toxicological importance when attempting to account for the effects of chronic abuse of these potent drugs.1
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Affiliation(s)
- N Castagnoli
- Department of Chemistry and Entomology, Virginia Tech, Blacksburg 24061-0212, USA.
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