Changes in gene expression within the extended amygdala following binge-like alcohol drinking by adolescent alcohol-preferring (P) rats

Abstract

The objective of this study was to determine changes in gene expression within the extended amygdala following binge-like alcohol drinking by male adolescent alcohol-preferring (P) rats. Starting at 28 days of age, P rats were given concurrent access to 15 and 30% ethanol for 3 one-h sessions/day for 5 consecutive days/week for 3 weeks. Rats were killed by decapitation 3 h after the first ethanol access session on the 15th day of drinking. RNA was prepared from micropunch samples of the nucleus accumbens shell (Acb-sh) and central nucleus of the amygdala (CeA). Ethanol intakes were 2.5-3.0 g/kg/session. There were 154 and 182 unique named genes that significantly differed (FDR=0.2) between the water and ethanol group in the Acb-sh and CeA, respectively. Gene Ontology (GO) analyses indicated that adolescent binge drinking produced changes in biological processes involved with cell proliferation and regulation of cellular structure in the Acb-sh, and in neuron projection and positive regulation of cellular organization in the CeA. Ingenuity Pathway Analysis indicated that, in the Acb-sh, there were several major intracellular signaling pathways (e.g., cAMP-mediated and protein kinase A signaling pathways) altered by adolescent drinking, with 3-fold more genes up-regulated than down-regulated in the alcohol group. The cAMP-mediated signaling system was also up-regulated in the CeA of the alcohol group. Weighted gene co-expression network analysis indicated significant G-protein coupled receptor signaling and transmembrane receptor protein kinase signaling categories in the Acb-sh and CeA, respectively. Overall, the results of this study indicated that binge-like alcohol drinking by adolescent P rats is differentially altering the expression of genes in the Acb-sh and CeA, some of which are involved in intracellular signaling pathways and may produce changes in neuronal function.

Keywords: Adolescent binge drinking; Alcohol-preferring rat; Central nucleus of the amygdala; Gene expression; Nucleus accumbens-shell.

Fig. 1

Ethanol intakes (g/kg) by peri-adolescent P rats averaged over each 5-day period for each of the three one-h periods with concurrent access to 15 and 30% ethanol (with water freely available) during the dark cycle. Ethanol was given 5 consecutive days each week over the 15 days of access. The average total per day for the 3 one-h sessions is also shown. Data are the means ± SEM; n = 10).