FIGURE 2. Effects of 7,8-Dihydroxyflavone (7,8-DHF) on Fear Conditioning in Wild-Type Mice^a.

^a Panel A shows results of a dose-response study performed with 7,8-DHF (N=10 in each dose group). The graph shows the average proportion of animals freezing during the first three conditioned stimulus trials (^#p≤0.05 relative to vehicle [control]). Panel B shows the mean total distance and the distance traveled in the center of the open field for 10 minutes with 7,8-DHF or vehicle injected 1 hour before testing; there were no differences between groups. Panel C shows the mean shock reactivity in the startle apparatus during the cue-dependent fear conditioning; there were no differences between groups. Panel D shows the mean percentage of time spent freezing, in three conditioned stimulus trials per group (across the entire 15 conditioned stimuli), in testing for cue-dependent fear memory 24 hours after fear conditioning. Mice that had received 7,8-DHF prior to fear conditioning showed increased freezing. Panel E shows the mean percentage of time spent freezing within-session for each test trial for the first 10 trials of session. Within-session fear differences were particularly pronounced in the first conditioned stimulus trial of the testing session. Panel F shows that the mean total time spent freezing during testing (conditioned stimulus and no-stimulus intertrial periods) was significantly greater in the group of mice that had received 7,8-DHF 1 hour prior to fear conditioning. Error bars in panels B–F indicate standard deviations. In panels D–F, *p<0.05 between 7,8-DHF and vehicle groups.