Figure 2.

Analysis of data obtained by using an open field (OF). In the OF, the distance that 3-, 6- or 9-month-old mice traveled was determined (a–c). At an age of 3 months, no obvious differences are seen in this behavior (a). In 6-month-old mice, there is a significant differences between the −/+,Cre+ and −fl,Cre+ mice. In general, there is a tendency for the −/+, Cre+ mice to travel further than the other mice and for the −/fl,Cre+ mice to travel less than the other mice (b). At an age of 9 months, this behavior is more evident, especially concerning the −/+,Cre+ mice., which travel significantly longer distances than the other mice (c). In the OF, resting times were also determined in different groups of 3-, 6- or 9-month-old mice (d–f). No difference in resting behavior is seen in the young adult mice (3 months of age; (d)). The six-month-old mice differ in that the −/fl,Cre+ mice display significantly longer resting times than the −/+,Cre+ mice (e). The analysis of the older (9-month-old) mice reveals that the −/+,Cre+ mice have shorter resting times than the others, while the −/fl,Cre+ mice have the longest resting times (f). A further parameter analyzed concerns the rearing behavior. At an age of three months, the −/+,Cre+ mice differ significantly in their behavior when compared to the +/+,Cre+ and −/fl,Cre+ mice (g). At an age of 6 months, the −/fl,Cre+ mice differ significantly in this type of behavior from all other groups analyzed by displaying reduced rearing behavior (h). At an age of 9 months, the −/fl,Cre+ mice still differ significantly from all other mouse lines examined, except for the fl/fl,Cre+ mice that show comparable behavior (i). * p ≤ 0.05, ** p ≤ 0.01 and *** p ≤ 0.001.