We describe the RNA integrity (28S/18S ratio) and the messenger RNA (mRNA) expression of genes encoding glyceraldehyde 3-phosphate dehydrogenase (GAPDH), microtubule-associated serine/threonine kinase 2 (Mast2), and beta-actin in cortical brain slices incubated for up to 24h in Ringer's solution and Dulbecco's modified Eagle's medium (DMEM) at 25 and 37 degrees C. Our data reveal an optimal temporal working window between 1 and 6h when slices are incubated in Ringer's solution at 25 degrees C that allows experiments related to gene expression dynamics to be performed more suitably than those carried out at 37 degrees C. In addition, we show that reference gene expression may be modified in dynamic experiments and may compromise studies of gene expression.