Microglial cells in culture express a prominent glutathione system for thedefense against reactive oxygen species

To obtain information on the glutathione metabolism of microglial cells, th e content of glutathione and activities of enzymes involved in the defense against peroxides were determined for microglia-rich cultures from rat brai n. These cultures contain approximately 90% microglia cells as determined b y immunocytochemical staining for glial markers, by the phagocytosis activi ty of the cells and by the production of superoxide after stimulation of th e cells with phorbolester. For these cultures, a glutathione content of 41. 2 +/- 11.2 nmol/mg protein and a specific activity of glutathione reductase of 15.2 +/- 3.2 nmol/(min x mg protein) were determined. These values are significantly higher than those found for astroglial or neuronal cultures. In addition, with 68.7 +/- 23.5 nmol/(min x mg protein), the specific activ ity of glutathione peroxidase in microglial cultures was 78% higher than in cultured neurons. The specific catalase activity of microglial cultures wa s less than 40% that of astroglial or neuronal cultures. Microglial culture s contain only marginal amounts of oxidized glutathione. However, on applic ation of oxidative stress by incubation of microglial cultures with hydroge n peroxide or with the superoxide-producing hypoxanthine/xanthine oxidase s ystem, cellular glutathione was rapid ty oxidized. These results demonstrat e that microglial cells have a prominent glutathione system, which is likel y to reflect the necessity for self-protection against reactive oxygen spec ies when produced by these or surrounding brain cells. Copyright (C) 2000 S . Karger AG, Basel.