Influence of light-dark cycle alteration on free radical level in rat cns.

The experiment analysed the evolution of several redox parameters caused by light-dark cycle alteration in different rat brain segments: cortex, brain stem, diencephalon. Continuous light (L:L) enhanced SOD, CAT, GPX and GSH levels to different extents in the various central nervous system regions investigated, depending on the entrainment period: 24 h, 48 h, 72 h, 7 days. Continuous darkness (D:D -24 h, 48 h, 72 h, 7 days) generally diminished SOD, CAT and GSH values, but increased GPX at 48 h and CAT at 72 h. MDA levels were higher in D:D, too. After 7 days L:L or D:D redox indices tended to reach the normal range again. Redox system spatio-temporal versatility and complementarity suggested the existence of a possible biochemical radical cell clock gear.