Early-life adverse experience including stress can affect the shaping of neuronal circuits during postnatal development and cause long-lasting influences on neural functions. Maternal separation (MS), an animal model of early-life stress, has effects on behavior and emotion and increases the risk of development of psychiatric disorders in adult life. The extended amygdala including the nucleus of accumbens (Acb) and the bed nucleus of stria terminalis (BNST), modulates fear and anxiety. However, the effects of MS on these brain regions have not been studied well in animal model. Here, to investigate changes of gene expression profile induced by MS, brain tissues punched out from Acb and BNST were subjected to DNA microarray analysis by using Mouse Genome 430 2.0 Array GeneChip set (Affimetrix) containing 45,101 probes. The microarray data revealed that 27.9% and 24.1% of all entities showed significant expression changes (fold change, <0.5 and >2.0) in Acb and BNST of MS group. Particularly, we observed a significant increase in the expression of several neurotransmitter-related genes including serotonin 1A receptor and corticotropin-releasing hormone and decrease in dopamine receptors and diacylglycerol lipase alpha, especially in Acb. These data suggest that MS stress during developmental stage alters gene expression of several neuro-transmitter including dopamine and endocannabinoid signaling molecules in the extended amygdala region, implying abnormalities in motivation and/or emotional deficit often seen in childhood abuse. We are currently focusing the endocannbinoid system which mediates anxiety and fear responses and conducting the histological and cell biological studies in MS model.