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. 2012 Oct 1;22(1):96–109. doi: 10.1093/hmg/dds406

Figure 4.

Figure 4.

F1 hybrid Mecp2+/− mice have altered social behavior, and impaired contextual fear memory and passive avoidance learning. At 12 weeks of life, FVB.129F1 Mecp2+/− and wild-type littermate mice spend more time investigating a novel mouse compared with a novel object. However, FVB.129F1 Mecp2+/− spend less time investigating a novel mouse, and investigate a novel object similarly compared with wild-type animals (A). In contrast, 129.B6F1 Mecp2+/− mice show no preference for a novel object or mouse, whereas wild-type littermates spend more time investigating a novel mouse compared with a novel object. Across genotypes, no difference is observed in the time spent investigating a novel mouse (C). Similar to the findings at 12 weeks of life, at 22 weeks of life FVB.129F1 Mecp2+/− and wild-type littermate mice spend more time investigating a novel mouse compared with a novel object, and FVB.129F1 Mecp2+/− mice spend less time investigating a novel mouse. No difference was observed in the time spent investigating a novel object (B). Similarly, 129.B6F1 Mecp2+/− and wild-type littermate mice spend more time investigating a novel mouse compared with a novel object. However, 129.B6F1 Mecp2+/− mice spend less time investigating both the novel mouse and the novel object (D), due to reduced motor activity in the three-chamber apparatus (Supplementary Material, Fig. S4). Mecp2+/− mice of both F1 hybrid backgrounds compared with wild-type littermates freeze less in a test for contextual fear memory but not cued fear memory (E and F). In the passive avoidance learning task, no differences among genotypes were observed for the latency to enter the dark compartment during the training phase (G and H). However, during the test phase, Mecp2+/− mice of both F1 hybrid backgrounds compared with their respective littermates showed a decrease in the latency to enter the dark compartment (G and H). *P < 0.05; **P < 0.001; ns, not significant.