Cultured rat and human astrocytes and rat neurones were shown to release reduced glutathione (GSH). In addition, GSH oxidation was retarded by the concomitant release of a factor from the cells. One possibility is that this factor is extracellular superoxide dismutase (SOD). In support of this, the factor was found to bind heparin, have a molecular mass estimated to be between 50 and 100 kDa, and CuZn-type SOD protein and cyanide sensitive enzyme activity were demonstrated in the cell-conditioned medium. In addition, supplementation of native medium with exogenous CuZn-type SOD suppressed GSH oxidation. We propose that preservation of released GSH is essential to allow for maximal up-regulation of GSH metabolism in neurones. Furthermore, cytokine stimulation of astrocytes increased release of the extracellular SOD, and enhanced stability of GSH. This may be a protective strategy occurring in vivo under conditions of oxidative stress, and suggests that SOD mimetics may be of therapeutic use.
- Cell culture
- Neuroprotective factor
- Oxidative stress
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience