Catalase activity and rhythmic patterns in mouse brain, kidney and liver.

To protect tissues from damaging effects of reactive oxygen species (ROS), organisms possess enzymatic and non-enzymatic antioxidant systems. Cytosolic-enzyme catalase (CAT) is a component of the antioxidant defence system that reduces hydrogen peroxide (H(2)O(2)) to water (H(2)O). The aim of this study was to assess the variation of antioxidant enzyme CAT activity in brain, kidney and liver of adult male mice according to tissue-specific and temporal patterns within a 24-h period (12:12 L/D). The CAT activity was assayed at 4-h intervals. The Cosinor test programme was used to detect and confirm the best corresponding rhythm. In liver, the circadian rhythm of CAT was associated with ultradian components. The prominent circadian rhythm (with a period tau=24 h) showed a peak located at the middle of the dark phase, more precisely congruent with 17 HALO (Hours After Light Onset). In kidney, only a circadian rhythm of CAT was validated with a peak time located at congruent with 17 HALO. However, in brain, the time pattern of CAT activity showed two peak times at congruent with 1 and congruent with 17 HALO, illustrating the existence of an ultradian rhythm (with a period tau=12 h). The results showed significant organ differences with the highest activity in liver, compared with kidney (-89%) and brain (-98%). This might be related to several factors such as their respective physiological function, the risk of exposure to oxidative damage and the balance between synthesis and degradation of proteins during "normal metabolism". Moreover, CAT activity revealed differences in time-related changes across a 24-h period that were more obvious in peak levels between the three tissues.