In the 8th week, rats (in this single cohort) were killed by decapitation 1, 6 or 24 hr (n = 10/time point for ethanol groups; n = 6/time point for water groups) after the first drinking episode of the day; the brains were quickly removed and frozen in isopentane in dry ice. Rats were habituated to the guillotine during the 7th week. The 1-hr time point was chosen to measure expression levels when high in vivo concentrations of ethanol were present. The 6-hr time point was selected to detect gene expression changes as a result of episodic drinking but without alcohol being present. The 24-hr time point was selected to (a) determine the effects of chronic exposure to alcohol, and (b) allow comparison with other 24-hr time point data (Bell et al., 2009; Rodd et al., 2008).
