Day-night cycle of lipid peroxidation in rat cerebral cortex and their relationship to the glutathione cycle and superoxide dismutase activity.

Lipoperoxidation, glutathione cycle components and superoxide dismutase activity show a day-night rhythm in the cerebral cortex of the rat. The highest lipoperoxidative activity is observed during the night (20.00-04.00 h). The enhancement in lipoperoxidation occurs concurrently with a decrease in glutathione peroxidase activity, an increase in superoxide dismutase activity and an increase in the double bonds in the brain cortex lipid fraction. The changes described in this paper seem to be related to a succession of light and dark periods, or to fasting and feeding periods. We propose that those fluctuations could act as a physiological oscillator with an important role in modulating the membrane properties of the nerve cell.