ATLA::Alternatives to Laboratory Animals

Volume 27, Number 3

The effects of oxidative stress in in vitro cultured astroglial cells.

ATLA 27, 351-357, May/June 1999

Casper Møller Frederiksen and Jørgen Clausen

Department of Life Sciences and Chemistry, Roskilde University, 4000 Roskilde, Denmark

SUMMARY

It has been suggested that glial cells in the central nervous system might function as a buffer and protect neurons and synapses. Associated with such a function, glial cells might be affected in degenerative diseases, for example, Alzheimer's disease and Parkinson's disease, due to generation of free-radicals. Free-radicals might be generated during the metabolic transformation of xenobiotics. The purpose of the present study was to determine whether a xenobiotic (in this case, paraquat), is metabolised in glial cells during the generation of free-radicals. Furthermore, this study determined whether free-radicals can induce DNA fragmentation and whether this fragmentation can be repaired. The data produced indicated that astroglial cells contain P450-reductase which transforms paraquat into a pyridium free-radical. In turn, this causes a dose-dependent DNA fragmentation, as determined by using single-cell gel electrophoresis. The dose-dependent effect was valid up to 80 µM paraquat. The oxidative stress induced in the astroglial cells was also associated with a maximum 15% increase in the anti-oxidative enzyme, glutathione peroxidase. After exposure to 40 µM paraquat, followed by growth of the cells in a paraquat-free medium, DNA repair was shown to be rather slow, and was only obvious two hours after exposure to paraquat. This might be related the shuttle in which paraquat/P450-reductase is implicated, which causes a protracted generation of free-radicals. The data are discussed in relation to the available literature.

Keywords: astroglial cell cultivation, free-radicals, P450-reductase, paraquat, DNA fragmentation, DNA repair, single-cell gel electrophoresis, comet assay, glutathione peroxidase