title: Subtoxic concentration of manganese synergistically potentiates 1-methyl-4-phenylpyridinium-induced neurotoxicity in PC12 cells.
abstract: Endogenous or exogenous substances that are toxic to dopaminergic cells have been proposed as possible cause of idiopathic Parkinson's disease (PD). 1-Methyl-4-phenylpyridinium (MPP(+)) and manganese are dopaminergic neurotoxins causing a parkinsonism-like syndrome. Here, we studied the possible synergistic reaction between these two neurotoxins using rat PC12 pheochromocytoma cells. MPP(+) induced a delayed neurotoxicity in PC12 cells. Although low concentration of manganese did not cause cell damage, it markedly enhanced MPP(+)-induced neurotoxicity with characteristics of apoptosis, such as DNA laddering and activation of caspase-3. To understand the mechanism of enhancement of subtoxic concentration of manganese on MPP(+)-induced neurotoxicity, we investigated the reactive oxygen species (ROS) generation using a molecular probe, 2',7'-dichlorofluorescein diacetate. Although subtoxic concentration of manganese alone did not induce ROS increase, it significantly enhanced the ROS generation induced by MPP(+). We also determined the intracellular MPP(+) content. A time- and concentration-dependent increase of MPP(+) levels was found in PC12 cells treated with MPP(+). The accumulation of MPP(+) by PC12 cells was not affected by manganese. Taken together, these studies suggest that co-treatment with MPP(+) and manganese may induce synergistic neurotoxicity in PC12 cells and that subtoxic concentration of manganese may potentiate the effect of MPP(+) by an ROS-dependent pathway.
authors.affiliation: Department of Pharmacology, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Ren-Gang
authors.initials: RG
authors.lastname: Wang
authors.forename: Xing-Zu
authors.initials: XZ
authors.lastname: Zhu
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D008345:Manganese / Q000008:administration & dosage*; D009498:Neurotoxins / Q000494:pharmacology*; D009994:Osmolar Concentration; D016716:PC12 Cells; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D009498:Neurotoxins; D017382:Reactive Oxygen Species; D008345:Manganese; D015655:1-Methyl-4-phenylpyridinium