ENDOGENOUS RHYTHM OF TrkB RECEPTOR EXPRESSION IN THE HIPPOCAMPUS IS MODIFIED BY A VITAMIN A-FREE DIET

NAVIGATORE FONZO LS; GOLINI RS; DELGADO SM; ANZULOVICH AC

Mendoza

Congreso; XXXI REUNION CIENTIFICA ANUAL DE LA SOC. DE BIOL. DE CUYO; 2013

Brain-derived neurotrophic factor (BDNF) bound to its receptor TrkB, is essential for the induction and maintenance of potentiation and long term memory. Retinoic acid, a vitamin A derivative, regulates phenomena related to cognitive function by activating nuclear receptors, RARs and RXRs. Our objectives were: to investigate whether TrkB and RXRαreceptors display endogenous circadian expression in the rat hippocampus, to analyze the circadian variation of glutathione (GSH) levels and to evaluate the effect of a vitamin A-depleted diet on those temporal patterns. Holtzman rats received a diet containing 4000 IU of vitamin A/Kg diet (Control), or the same diet devoided of vitamin A (VitaminAdeficient, VAD, group), during 3 months. Rats were maintained under constant darkness conditions during 10 days before the experiment. Hippocampus samples were isolated every 4 h during a 24h period. Circadian rhythms of TrkB and RXRαmRNA were determined by RT-PCR and BMAL1 and PER1 proteins by immunoblotting, GSH levels by a kinetic assay. E-box, and E-box like sites were found on regulatory region of TrkB gene, which display an endogenously-controlled circadian expression in the rat hippocampus. Vitamin A deficiency (VAD) modified those temporal profiles, as well as, the rhythmic profile of GSH, probably, by altering the circadian patterns of key clock factors and/or retinoic acid receptors.