Conditioned place preference (CPP) is often used as a measure of drug reward, and we asked if the hybrids differed in ethanol-induced CPP (Tzschentke 1998). Analysis of test day data indicates that both saline- and LPS-pretreated groups of mice develop a similar ethanol-induced CPP, indicating a similar sensitivity to the rewarding properties of ethanol (Fig. 9A). Saline groups did not exhibit a floor type preference on the test day (data not shown). The data were analyzed by two-way ANOVA {group (GRID + and GRID−) × pretreatment (saline and LPS)}. There was no group × pretreatment interaction and no main effect of pre-treatment was seen. However, there was a main effect of group [F(1, 36) = 17.2, p < .001]. Both pretreated groups of mice spent more time on the floor when it was paired with ethanol injections (GRID + group), and both groups spent less time on the floor when it was paired with saline (GRID-group). Mean activity during each 5-min ethanol (CS+) and saline (CS−) conditioning trial are depicted in Fig. 9B. Activity on saline trials was decreased across
