GSH REDUCTASE EXPRESSION IS CIRCADIAN IN THE HIPPOCAMPUS AND DAMPENED IN THE VITAMIN A DEFICIENCY

NAVIGATORE FONZO LS; DELGADO SM; GIMÉNEZ MS; ANZULOVICH AC

Potrero de los Funes, San Luis

Congreso; 47th. Annual meeting SAIB; 2011

SAIB

Reduced glutathione (GSH) is the major endogenous antioxidantproduced by cells and is critical for the maintenance of the redoxpotential in the brain. Our objectives were to investigate whetherGSH reductase (GR) displays a circadian expression pattern in therat hippocampus and to evaluate to which extent vitamin Adeficiency (VAD) could modify temporal patterns of clock, RARsand GR expression. Holtzman rats weaned at 21 d of age wereimmediately assigned to either a vitamin A-free diet (DE group) orthe same diet containing 4000 IU of vitamin A/Kg diet (CO group)during 3 months. Both groups were maintained under 12h-Light:12h-Dark or 12h-Dark:12h-Dark conditions during 10 daysbefore the experiment. Hippocampi were taken every 4 h. GRtranscript levels were determined by RT-PCR. RARa, RARß,BMAL1 and PER1 protein levels were determined byimmunoblotting. We found mRNA levels of GR display a circadianpattern in the rat hippocampus peaking at the middle of the night(P<0.01). RARa, RARß, BMAL1 and PER1 also exhibitedcircadian rhythmicity (P< 0.05, P<0.01) in this brain area. VADdampened the oscillating GR expression and phase shifted rhythmsof clock and RARs proteins.Thus, VAD might affect the circadianexpression of GR and consequently, the availability of GSH at agiven time during the day, probably, by altering the circadianpatterns of key clock and RARs proteins.