title: MPP(+) increases the vulnerability to oxidative stress rather than directly mediating oxidative damage in human neuroblastoma cells.
abstract: MPP(+), an active metabolite of MPTP, causes a dopaminergic neuronal degeneration similar to that observed in Parkinson's disease. Current data suggest that MPP(+)-induced cytotoxicity may be mediated by oxygen free radicals. To evaluate this hypothesis, we first investigated whether MPP(+) could cause oxidative stress by producing oxygen free radicals in the SH-SY5Y, human neuroblastoma cell line. MPP(+) was toxic to the cells dose-dependently but did not increase the level of lipid peroxidation at toxic concentrations. Second, we examined the effects of various antioxidants and an inhibitor of nitric oxide synthase (NOS) on the development of MPP(+) cytotoxicity. Pretreatment with antioxidants such as ascorbic acid, Trolox, phenyl-tertiary-butyl-nitrone (PBN), which show protective effects on tert-butyl hydroperoxide (tBOOH) toxicity did not attenuate MPP(+) cytotoxicity. Similarly, the combination of antioxidant enzymes, SOD and catalase (50 U/ml, respectively), did not protect the cells from the toxic action of MPP(+). Also N-nitro-l-arginine methyl ester (NAME), a competitive inhibitor of NOS, and combined incubation with NAME and antioxidant enzymes failed to attenuate MPP(+) cytotoxicity. On the other hand, a sublethal dose of MPP(+) potentiated iron and H(2)O(2)-induced cytotoxicity. These results suggest that oxygen free radicals may not be a primary cause of MPP(+)-induced cell death but that MPP(+) increases the vulnerability of cells to oxidative stress.
authors.affiliation: Department of Pharmacology, College of Medicine, Seoul National University, 28 Yongon-Dong, Chongo-Gu, Seoul, Korea.
authors.forename: H S
authors.initials: HS
authors.lastname: Lee
authors.forename: C W
authors.initials: CW
authors.lastname: Park
authors.forename: Y S
authors.initials: YS
authors.lastname: Kim
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000008:administration & dosage / Q000494:pharmacology* / Q000506:poisoning; D000975:Antioxidants / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D004334:Drug Administration Schedule; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008054:Lipid Peroxides / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009573:Nitrites / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D014407:Tumor Cells, Cultured
chemical_list: D000975:Antioxidants; D004791:Enzyme Inhibitors; D008054:Lipid Peroxides; D009573:Nitrites; D019001:Nitric Oxide Synthase; D015655:1-Methyl-4-phenylpyridinium; D019331:NG-Nitroarginine Methyl Ester