BDNF AND TRKB MESSENGER-RNAS OSCILLATE IN RAT-BRAIN DURING THE LIGHT-DARK CYCLE

In this study, we investigated whether in basal conditions the differe nt functional states occurring during a 24-h cycle are reflected by th e expression of brain-derived neurotrophic factor (BDNF) and its recep tor, trkB, in rat cerebral cortex and hippocampus. Using semiquantitat ive RT-PCR assay, the levels of both BDNF and trkB mRNAs were found to undergo significant variation in a 24-h period. The strongest variati on was detected in the hippocampus, where the ratio between maximum an d minimum levels was about 3.5 and 17.5 for BDNF and trkB, respectivel y. These findings provide the first evidence that, in the absence of a ny experimental manipulation, the expression of a neurotrophin and its receptor undergoes diurnal oscillation, possibly related to the physi ological variations of the activity level. (C) 1998 Elsevier Science B .V. All rights reserved.