Figure 4.

Behavior of SAMP8-p75 ^{exonIII−/−}. SAMP8 anxiety decreases with p75^NTR deletion. (A) Representative images of the different open field measurements. (B) Open-field test. Percentage of the time spent in the center in the open field test. SAMP8 mice (blue and orange) are more anxiogenic than SAMR1 mice (green bar), however, SAMP8-p75 ^{exonIII−/−} partially decreases the anxiety levels. (C) Y-maze test. SAMP8-p75 ^{exonIII−/−} has a loss of spatial memory with age. Percentage of SAB (spontaneous alternation behavior) measured with the number of correct triplets divided by the total triplets. A difference from SAMP8-p75^exonIII+/+ mice, SAMP8-p75^{exonIII−/−} loses episodic memory with age. (D) Novel-object recognition. The deletion of p75 in the SAMP8 mice has no effect on long-term memory. Percentage of time spent on the novel object. SAMP8 background showed a loss in long-term memory at 6 months compared to SAMR1 mice. SAMR1 6 months N = 5, SAMP8-p75^exonIII+/+ 2 months N = 22, SAMP8-p75^{exonIII−/−} 2 months N = 8, SAMP8-p75^exonIII+/+ 6 months N = 24, SAMP8-p75^{exonIII−/−} 6 months N = 8. Two-way ANOVA followed by Tukey’s post-hoc test, *p < 0.05, **p < 0.01, ***p < 0.001. (E) Levels of acetylcholine analyzed by HPLC and normalized per mg of tissue. N = 3. Two-way ANOVA followed by Tukey’s post-hoc test, **p < 0.01.