Methylmercury-induced reactive oxygen species formation in neonatal cerebral astrocytic cultures is attenuated by antioxidants

Gouri Shanker, Michael Aschner

Research output: Contribution to journalArticle

119 Scopus citations

Abstract

Excessive generation of reactive oxygen species (ROS) has been suggested as a causal factor in various neurodegenerative disorders, such as Parkinson's disease and Alzheimer's disease [Brain Res. 830 (1999) 10-15; Biochem. J. 310 (1995) 83-90; Free Radic. Biol. Med. 27 (1999) 612-616]. The present work examined the role of ROS in the neurotoxicity of methylmercury (MeHg). ROS formation in primary astrocytic cultures of neonatal rat cerebral cortex was monitored by 2′,7′-dichlorodihydrofluorescein diacetate (H2DCF-DA) fluorescence. MeHg, at 10 and 20 μM caused a significant increase in ROS formation (10 μM, P<0.01; 20 μM, P<0.001). Additional studies established the effectiveness of antioxidants/free radical scavengers in attenuating the MeHg-stimulated ROS formation in the following rank-order: (1) Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), a non-thiol containing antioxidant, (2) n-propyl gallate (PG), a free radical scavenger, (3) superoxide dismutase (SOD), an antioxidant enzyme that dismutates superoxide anion radical, (4) α-phenyl-tert-butyl nitrone (PBN), a lipophilic hydroxyl radical spin trapping agent. A significant inhibition of MeHg-induced ROS generation was also noted in astrocytes preincubated (3 h) with arachidonyl trifluoromethyl ketone (AACOCF3, 20 μM, P<0.05), a specific inhibitor of cytosolic phospholipase A2 (cPLA2). Conversely, pretreatment (24 h) with 100 μM buthionine-L-sulfoxamine [BSO, a glutathione (GSH) synthesis inhibitor], significantly increased (P<0.05) ROS formation in MeHg treated astrocytes compared to controls. Combined, these studies invoke ROS as potent mediators of MeHg cytotoxicity and support the hypothesis that excessive ROS generation, at least in part, plays an important role in MeHg-induced neurotoxicity.

Original languageEnglish (US)
Pages (from-to)85-91
Number of pages7
JournalMolecular Brain Research
Volume110
Issue number1
DOIs
StatePublished - Jan 31 2003
Externally publishedYes

Keywords

  • Antioxidants
  • Astrocytes
  • In vitro
  • Methylmercury
  • Rat
  • Reactive oxygen species

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience

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