Figure 3
Bexarotene fails to produce an effect on context-dependent or CS-dependent freezing behavior in APP swe /PS1 Δ E9 mice. Percent of time spent freezing was measured to quantify long term fear memory. (A) In the training session, APP swe /PS1 Δ E9 mice receiving bexarotene treatment demonstrated similar levels of context-dependent freezing compared to their vehicle-treated counterparts [F(7,44)=3.905, p=0.002; Tukey: male nontg p=1.000, male tg p=0.182, female nontg p=0.999, female tg p=1.000]. In the context-dependent testing session, no significant differences were detected among any of the groups [F(7,44)=1.794, p=0.113]. (B) Analysis of CS-dependent fear responses show no significant effect of bexarotene on freezing behavior in APP swe /PS1 Δ E9 male or female mice. A significant gender difference was detected between males and females in both non-transgenic and APP swe /PS1 Δ E9 animals treated with vehicle [main effect of gender F(1,15)=23.506, p<0.0005; main effect of genotype F(1,15)=1.898, p=0.189, no significant interaction; females [M=42.006,SD=17.65] show lower levels of freezing than males [M=76.260,SD=10.50]. These gender-related differences were not observed in mice treated with bexarotene [males M=48.79, SD=20.71; females M=54.55, SD=21.48; main effect of sex F(1,27)=0.630, p=0.434; main effect of genotype F(1,27)=1.388,p=0.249; no significant interaction]. The condition of equality of variances was not met for this test. For all parts, error bars represent standard deviation. N-values females: nontg-veh=4, AP-veh=7, nontg-bex=8, AP-bex=13. N-values males: nontg-veh=4, AP-veh=4, nontg-bex=6, AP-bex=5.