Fig. 9

Aging Reduces the Neuroprotective Capacity of Wld^S+/+. A IOP of aged WT (circles) and Wld^S+/+ (squares) mice before (day 0) and after (days ≥1) a single unilateral injection of microbeads (blue symbols) or equivalent volume of saline (beige symbols). Microbeads elevated IOP by 29.5% in aged WT (19.45 ± 1.5 vs. 15.01 ± 1.3 mmHg, p < 0.001) and 29.7% in Wld^S+/+ eyes compared to saline-injected eyes (19.23 ± 1.6 vs. 14.82 ± 1.3 mmHg, p < 0.001). B, C Example coronal sections (top) of the SC after intravitreal injection of CTB-488 (green) into saline- and microbead eyes of aged WT (B) and Wld^S+/+ mice (C). Transport deficits are indicated by dashed lines. Retinotopic maps (bottom) recreated from SC sections with optic disc indicated by white filled circles. Scale bar = 500 μm. D Quantification of anterograde axon transport to the SC. Data from young (1.5–2.5 months old) animals are replotted from Fig. 8C for comparison. We did not detect a difference in the percent of intact transport to the SCs corresponding to saline eyes of young vs. aged WT and Wld^S+/+ animals (p = 0.60). For aged animals, IOP elevation decreased transport in WT (p < 0.001) and Wld^S+/+ mice (p = 0.03) when compared to respective saline eyes. Axon transport of aged Wld^S+/+ microbead-injected eyes was greater than that observed in SC of aged WT microbead eyes (p = 0.001). E Quantification of Δ spatial acuity. Data for young animals replotted from Fig. 8D for comparison. Spatial acuity linearly diminishes over the duration of IOP elevation in aged WT (R² = 0.74, p = 0.0064) and Wld^S+/+ mice (R² = 0.81, p = 0.0058). Statistics: Student’s t-test (A), Kruskal-Wallis test, Dunn’s post hoc (D) Linear mixed model (E), Linear regression (E). Multiple comparison significance indicators: * Young WT vs. Young Wld^S+/+; ^# Aged WT vs. Young Wld^S+/+; ^ Young Wld^S+/+ vs. Aged Wld^S+/+ (E). Data presented = mean ± SEM