Fig 1: Spatial memory performance, animal weight, and plasma RBP4 levels. LI scores for individual Y and aged animals (A); plasma RBP4 levels presented as % of Y baseline (B, C); correlation of plasma RBP4 and LI score (D); mean body weights of animals tested. Note that body weight did not differ among the aged rats (E, F); correlation of plasma RBP4 and body weight (G). Results shown as bars with individual animal data plotted. Statistical analysis, unpaired two-tailed Student’s t test (B, E, F), one-way ANOVA, with Tukey’s multiple comparisons test (C), and linear regression (D, G; all animals, gray line; aged animals, black line); **p < 0.01, ***p < 0.001. Y n = 16 and aged n = 32 (AU n = 15, AI n = 17; panel A); Y n = 8 and aged n = 16 (AU n = 8, AI n = 8; panels B–G). Error bars represent SEM.