Comparison of Differences in Gene Expression in the Ventral Tegmental Area of 5 Pairs of Rat Lines Selectively Bred for High or Low Alcohol Consumption

The objective of this study was to determine common innate differences in gene expression in the ventral tegmental area (VTA) among the selectively bred (a) alcohol-preferring (P) vs. alcohol-non-preferring (NP) rats: (b) high-alcohol-drinking (HAD) vs. low-alcohol-drinking (LAD) rats (both replicates); (c) ALKO alcohol (AA) vs. nonalcohol (ANA) rats; and (d) Sardinian alcohol-preferring (sP) vs. alcohol-nonpreferring (sNP) rats. There were between 350 and 1400 unique named genes that were significantly different between the individual line-pairs. Gene Ontology (GO) and Ingenuity Pathways analyses indicated significant categories and networks in common for up to 3 line-pairs, but not for all 5 line-pairs; there were few genes in common between any of the line-pairs in these categories and networks. The overall ANOVAs of the combined data for the 5 line-pairs indicated over 1300 significant differences in expression of named genes. Ingenuity analysis revealed (a) several significant networks with clusters of genes associated with App, Egfr, Ccnd1, Itga2b, Rxra and Vcl; and (b) changes in genes within networks associated with dopamine, the glutamate synapse, Nfkb signaling, IL pathways and integrin. There were 22 genes that were significantly different in the overall ANOVA and were significantly different (in the direction) in at least 3 line-pairs, e.g., Crebl2, Gsta4, Itga9 & Itg2. In conclusion, the findings suggest that (a) different innate mechanisms may be contributing to vulnerability to high alcohol drinking behavior among the selectively bred lines, and (b) small contributions in expression of multiple genes within certain transmitter systems and intracellular signaling pathways may contribute to the disparate alcohol drinking characteristics of the 5 line-pairs.

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McBride WJ, Kimpel MW, McClintick JN, Ding ZM, Hyytia P, Colombo G, Edenberg HJ, Lumeng L, Bell RL