Modulation of endogenous antioxidant enzymes by nitric oxide in rat C6 glial cells

J Neurochem. 1997 May;68(5):1896-903. doi: 10.1046/j.1471-4159.1997.68051896.x.


To understand the possible mechanism of nitric oxide (NO)-mediated cytotoxicity, we investigated the effect of NO on the endogenous antioxidant enzymes (AOEs) catalase, glutathione peroxidase (GPX), and CuZn- and Mn-superoxide dismutases (SODs) in rat C6 glial cells under conditions in which these cells expressed oligodendrocyte-like properties as evidenced by the expression of 2',3'-cyclic-nucleotide 3'-phosphohydrolase. The 24-h treatment with S-nitroso-N-acetylpenicillamine (SNAP), a NO donor, decreased the activities and the protein levels of catalase, GPX, and Mn-SOD in a dose-dependent manner. Alternatively, the activity and the protein level of CuZn-SOD were increased. 2-Phenyl-4,4, 5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), a NO scavenger, blocked the effect of SNAP. Moreover, the treatment of C6 cells with sodium nitroprusside, another NO donor, or with a combination of lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma), which induce excessive production of NO, also significantly modulated the AOE activities in a manner similar to that seen with SNAP treatment. The compounds/enzymes that inhibit the production of NO (e.g., N-nitro-L-arginine methyl ester hydrochloride, arginase, and PTIO) blocked the effects of LPS and IFN-gamma on the activities of AOEs. Treatment with SNAP and a combination of LPS and IFN-gamma also modulated the mRNA levels of AOEs, parallel to the changes in their protein levels and activities, except for Mn-SOD where the combination of LPS and IFN-gamma markedly stimulated the mRNA expression. In spite of the stimulation of mRNA level, LPS and IFN-gamma significantly inhibited the activity of Mn-SOD within the first 24 h of incubation; however, Mn-SOD activity gradually increased with the increase in time of incubation. These results suggest that alterations in the status of AOEs by NO may be the basis of NO-induced cytotoxicity in disease states associated with excessive NO production.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 2',3'-Cyclic-Nucleotide Phosphodiesterases / metabolism
  • Animals
  • Cell Line
  • Drug Combinations
  • Enzyme Inhibitors / pharmacology
  • Interferon-gamma / pharmacology
  • Lipopolysaccharides / pharmacology
  • Neuroglia / drug effects
  • Neuroglia / enzymology*
  • Nitric Oxide / biosynthesis
  • Nitric Oxide / pharmacology*
  • Oxidoreductases / genetics
  • Oxidoreductases / metabolism*
  • Penicillamine / analogs & derivatives
  • Penicillamine / pharmacology
  • RNA, Messenger / metabolism
  • Rats
  • S-Nitroso-N-Acetylpenicillamine
  • Superoxide Dismutase / metabolism


  • Drug Combinations
  • Enzyme Inhibitors
  • Lipopolysaccharides
  • RNA, Messenger
  • Nitric Oxide
  • S-Nitroso-N-Acetylpenicillamine
  • Interferon-gamma
  • Oxidoreductases
  • Superoxide Dismutase
  • 2',3'-Cyclic-Nucleotide Phosphodiesterases
  • Penicillamine