TEMPORAL PATTERNS OF ANTIOXIDANT ENZYMES EXPRESSION AND ACTVITY ARE MODIFIED IN THE HIPPOCAMPUS OF AGED RATS

LACOSTE, MARÍA GABRIELA; PONCE, IVANA TAMARA; DELGADO, SILVIA MARCELA; ANZULOVICH, ANA CECILIA

San Luis

Congreso; XXX Reunión Anual de la Sociedad de Biología de Cuyo; 2012

Hippocampus plays a key role in memory and learning and is especially susceptible to oxidative stress. Particularly, aging is associated to increased oxidative stress and altered antioxidant defenses. The objective of this study was to investigate whether endogenous rhythms of catalase (CAT) and glutathione peroxidase (GPx) expression and activity as well as GSH levels are modified in the hippocampus of aged rat. Holtzman rats from control (3-months old) and aged (22-months old) groups were maintained under 12h-dark:12h-dark conditions, during 10 days before the experiment. CAT and GPx mRNA and enzymatic activity were determined by RT-PCR and kinetic assays, respectively, in hippocampi isolated every 4 h during a 24h period. Regulatory regions of CAT and GPx genes were scanned for putative clock-responsive sites. GSH levels were measured by colorimetric assay. E-box (CANNTG) sites were found on regulatory regions of GPx and CAT genes. Antioxidant enzymes expression and activity vary significantly in a 24h period under constant darkness conditions, in the rat hippocampus. We also observed circadian variation of GSH levels. Aging phase shifts CAT and GPx mRNA and activity and modified GSH levels. Modifying 24h-patterns of antioxidant defenses would impair the circadian oscillation of cellular redox state and the endogenous clock activity, in the hippocampus of aged individuals.