The Nucleus Accumbens Shell and Central Nucleus of the Amygdala of Alcohol-Preferring Rats Following Binge-Drinking

The objective of this study was to determine changes in gene expression within the extended amygdala following binge-like drinking by alcohol-preferring (P) rats. Adult male P rats were given 1-hr access to 15 and 30% ethanol (EtOH) three times daily for 8 weeks. Rats (n = 10/time point for EtOH and n = 6/time point for water) were killed by decapitation 1, 6 and 24 hr after the last drinking episode. Brains were extracted and rapidly frozen in isopentane in dry ice. RNA was prepared from individual micropunch samples of the nucleus accumbens shell (ACB-sh) and central nucleus of the amygada (CeA); microarray analyses were conducted with Affymetrix Rat 230.2 chips. EtOH intakes were 1.5-2 g/kg/session. Because too few genes changed at the individual time points, an overall effect, comparing the water and EtOH groups, was determined. In the ACB-sh and CeA, there were 276 and 402 probe sets for named genes, respectively, that were different between the two groups. There were 1.5- to 3.5- fold more genes up-regulated than down-regulated in both regions, with most differences between 1.1- to 1.2-fold. Although there were several significant Biological Processes categories in common between the 2 regions (e.g., synaptic transmission, neurite development), there were few genes in common between the two regions that differed between the EtOH and water groups. Overall, the results suggest that chronic binge-like alcohol drinking by P rats produces changes in the expression of genes that could alter neuronal function by different mechanisms in the ACB-sh and CeA.

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McBride WJ, Kimpel MW, Schultz JA, McClintick JN, Edenberg HJ, Bell RL