Comparison of the overall differences (when the time-course data are combined) in gene expression found in the ACB-shell of P rats between the ethanol and water groups in the present study versus differences in gene expression found in the ACB between inbred P rats operant responding for ethanol versus water or saccharin (Rodd et al., 2008) indicated there were only 10 genes in common between the two studies. There was increased expression of 8 genes (i.e., Cd99, Cox6a1, Cst3, Ftl1, Fau, Bat5, Mt3, Sepw1), with only Snta1 and Thap7 having reduced expression levels. Five of the 8 genes that had higher expression levels are involved in cellular stress response, which may be the result of chronic exposure to high blood levels of alcohol. The relatively low number of changed genes that were in common between the operant study (Rodd et al., 2008) and the present study supports the idea that conditioning, learning and motor activity factors associated with operant ethanol self-administration play an important role in gene expression within the ACB. In addition, operant ethanol self-administration may be activating different
