DEVELOPMENTAL EXPRESSION OF THE TRANSCRIPTION FACTOR ZIF268 IN RAT-BRAIN

Changes in the distribution pattern of mRNA encoding the zif268 transc ription factor (also referred to as NGFI-A, Krox-24 or EGR-1) were inv estigated by in situ hybridization histochemistry during postnatal rat brain development. Marked changes in zif268 expression patterns were seen in particular in the cerebral cortex and the hippocampal formatio n during the first 3 wk. In the Ist postnatal week, zif268 mRNA levels were highest in the corpus striatum and the piriform cortex. In the n eocortex, expression rose sharply in the sensorymotor area between pos tnatal days (PNDs) 10 and 12. In the frontal and occipital cortex, in contrast, an increase in zif268 mRNA levels was first seen on PND 14. After PND 17, levels decreased in the sensorymotor and the frontal cor tex but remained high in the occipital and the piriform cortex. In the hippocampus, an initially uniform increase in expression during the 2 nd week was followed by a marked dissociation in expression levels bet ween CA1, with continuously high expression levels on the one hand, an d CA3, CA4 and the dentate gyrus, with a strong decline of expression during the 3rd week, on the other hand. Our results indicate that zif2 68 expression displays a highly dynamic expression pattern during plas tic adaptations of different cerebral subregions during postnatal deve lopment, suggesting a possible involvement in gene regulatory processe s during these phases.