Fig. 5

Correlation of α2AP levels in the brain and spatial working memory between young and old mice. a and b The levels of α2AP and plasmin relative to those of GAPDH in the hippocampus and cerebral cortex of young and old C57BL/6J mice were determined by Western blotting (young mice: 12–16 weeks of age, old mice: > 25 months of age). The band intensity was measured using the NIH ImageJ software program and normalized to that of GAPDH. The values were divided by the mean of the normalized intensity of young mice. The bar graphs represent the mean ± SE (arbitrary units: A.U., young mice: n = 8, old mice: n = 9). Statistical significance was evaluated using Student’s t-test. **P < 0.01. c and d The relative intensity of α2AP to GAPDH and the scores of the Y-maze test were analyzed by Pearson’s correlation test. Correlation was evaluated using contribution rate (r²): values of r² > 0.16 were considered to indicate a correlation. The values of young mice and old mice were presented with a blank rhombus and filled rhombus, respectively