CIRCADIAN VARIATION OF ANTIOXIDANT ENZYMES AND TBARS IN HIPPOCAMPUS OF VITAMIN A-DEFICIENT RATS

NAVIGATORE FONZO, LS; DELGADO, SM; BONOMI, MR; REZZA, IG; GIMENEZ, MS; ANZULOVICH, AC

MAR DEL PLATA,BS AS

Congreso; XLIII REUNION ANUAL DE SAIB; 2007

SAIB

High levels of oxidative stress and alterations in the antioxidant defense system lead to a deficit in cognitive function. Circadian expression of GPx and CAT has been reported in different tissues. Our objective was to investigate the daily variation in protein levels and activity of GPx and CAT and lipoperoxidation in the hippocampus of control, vitamin A-deficient and vitamin A-recovered rats. GPx and CAT protein levels were determined by Western blots. Their activities were measured following Flohe& Gunzler (1984) and Aebi (1984), respectively. MDA levels following Droper and Hadley (1990). We observed a rhythmic variation in the antioxidant enzymes protein levels and activities, consistent with the circadian mRNA expression. Serum and hippocampus MDA levels showed also a daily variation. Vitamin A deficiency modified the circadian pattern of GPx and CAT and phase shifted the daily variation of lipoperoxidation. Refeeding vitamin A-deficient rats with 15 days of control diet, led to a partial recovering of antioxidant enzymes activities and MDA levels. Daily variation in the activity of the antioxidant defense system suggest that its components are under biological clock-control and retinoids might have a role in the circadian regulation of cellular redox state and consequently of memory and learning. This work was 80% supported by NIH Res.Grant R01-TW006974 funded by the FIC,USA.