Vitamin A deficiency modifies the daily expression of antioxidant enzymes in hippocampus.

NAVIGATORE FONZO, LORENA; BONOMI M.R.; GIMÉNEZ MS; ANZULOVICH A.C.

Rosario, Santa Fe

Congreso; XLII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2006

SAIB

Vitamin A deficiency is known to lead to oxidative stress and some evidence points out retinoids as regulators of clock genes activity through retinoid nuclear receptors (RARs and RXRs). Our objective was to investigate the effect of vitamin A deficiency on the circadian expression of antioxidant enzymes in the hippocampus of Wistar rats fed during 3 months with a vitamin A-deficient diet. Plasma and liver retinol concentration were determined by HPLC. Total RNA from hippocampus was extracted using the Trizol reagent (Invitrogen). Transcript levels of RARa, RXRb, CAT, SOD and GPx were determined by RT-PCR and normalized to beta-actin as endogenous control. Relative quantification by Real-time PCR using SYBR Green I dye was performed to measure the mRNA levels of RARa and RXRb. Subclinical plasma retinol concentration and negligible liver retinol stores confirmed the vitamin A deficiency. Significant lower mRNA levels of  RXRb, CAT and GPx were observed in the hipocampus of vitamin A-deficient compared to control and vitamin A-recovered rats. Vitamin A deficiency modified the daily rhythmicity in the expression of CAT and GPx. Those changes might occur as a consequence of a reduced availability of RXR. Establishing a role for vitamin A in the circadian regulation of antioxidant environment in the hippocampus might contribute to get an improved cognitive daily performance.