Figure 3

Abnormal behaviors in knock-in mice. Enhanced anxiety in both SL and DSL knock-in lines, but the memory impairments only in DSL mice starting at middle age. A. SL and DSL travels shorter distance on the open arms than wild type mice in elevated plus maze, indicating enhanced anxiety in these knock-in mice starting at young age. B. During the first 3 minutes when these mice were introduced to a new environment 24 hours after receiving a mild foot shock, both SL and DSL knock-in mice had higher percentage of time freezing in both young and middle aged group. C-J. Spatial learning and memory assays by Morris water maze (MWM). DSL exhibited normal learning and memory abilities when they are young (4-month old) (C & D). But the middle-aged group were slow in reaching the hidden platform during learning (E) and showed memory deficits at elderly age (12-month old) (F), in comparison with age and sex matched wild type control (WT). After additional day of training for DSL to learn the hidden platform tests, the platform was switched from Quadrant 3 (Q3) to Quadrant 4 (Q4) the following week to test reverse learning (G and H). DSL mice lagged behind WT in learning the new position on Day 11 and 12 (G), and in forming the new memory about the hidden platform on Day 10 and 11 (H). In comparison with DSL, SL mice behaved normally in spatial learning and memory at the same aged period (12-month old) (I & J). 10 ~ 18 male mice were used for each genotype at each age group. All mice used were novice to these behavior assays. NS, not significant; *P < 0.05, **P < 0.01, ***P<0.001.