Genome-wide DNA Microarray Analysis Unravels Rapid Changes in the Transcriptome of MK-801 treated Rat Brain

N-Methyl-D-aspartate receptors (NMDAr), widely located around the central nervous system, are known to be involved in behavioral disorders. Dizocilpine (commonly referred to as MK-801) is a well known non-competitive NMDAr antagonist. We treated rats with intraperitoneal injection [0.08 (low-dose) and 0.16 (high-dose) mg/kg] of MK-801. In one experiment, 40 min after NaCl (vehicle control) and MK-801 (0.08 mg/kg) injection, electrocorticogram (ECoG) signals were analyzed. In the second experiment, 40 min post-injection, the whole brain of each animal was rapidly removed and separated into amyglada, cerebral cortex, hippocampus, hypothalamus, midbrain and ventral striatum) on ice, followed by analysis using a 4x44K DNA microarray chip. Spectral analysis revealed that a single systemic injection of MK-801 significantly and selectively augmented the power of baseline (30-80 Hz) frequency oscillations. DNA microarray analysis showed the largest number (up- and down- regulations) of gene expressions in the cerebral cortex (378), midbrain (376), hippocampus (375), ventral striatum (353), amygdala (301), and hypothalamus (201) under low-dose of MK-801. Under high-dose, ventral striatum (811) showed the largest number of gene expression changes. Gene expression changes were functionally categorized to reveal expression of genes and function varies with each brain region. MK-801 increases the synchrony of baseline oscillations, causing very early changes in gene expressions in rat brain after acute MK-801 treatment, a first report. The overall goal of the present study was to identify gene expression patterns along rat chromosomes in different brain regions after a single injection of MK-801, which exerts a longer acute effect than ketamine on ongoing brain activities. Two approaches were taken, first electrophysiological and send molecular analysis, where the brain of MK-801-treated rats was subjected to a genome-wide transcriptome mapping analysis (~4400 genes) in the cerebral cortex, midbrain, hippocampus, ventral striatum, amygdala, and hypothalamus regions.