Figure 6.

Caffeine protects against OIR by A_2AR-dependent and -independent mechanisms. A) Room air or OIR mouse retinas [with or without caffeine treatment (1 g/L)] were harvested on P17 for quantitative PCR analysis of the A_2AR mRNA expression in retinas. Chronic caffeine (Caf) treatment increased A_2AR mRNA expression in retinas of normal and OIR mice. **P < 0.01, ***P < 0.001; 2-way ANOVA, Bonferroni post hoc test (n = 6–11/ mice). B) Retinal vasculature was visualized by whole-mount isolectin B4 staining at P12 of OIR. Avascular area is shown by red dotted line. Scale bar, 500 μm. C) Avascular area (%) was quantified as a percentage of the whole retinal surface. *P < 0.05; ***P < 0.001, 2-way ANOVA, Bonferroni post hoc test (n = 16–22/group). D) Retinal vasculature was visualized by whole-mount isolectin B4 staining at P17 of OIR. Avascular area is shown by red dotted line. Neovascularization tufts are indicated by purple line. Scale bar, 500 μm. E) Avascular area (%) was quantified as a percentage of the whole retinal surface. ***P < 0.001, 2-way ANOVA, Bonferroni post hoc test (n = 14–16/group). F) The neovascularization tuft area (%) was quantified as a percentage of whole retinal area. Caffeine treatment (1 g/L) or A_2AR KO decreased avascular areas, and combined caffeine and A_2AR-KO treatment produced a synergistic effect and completely reversed OIR pathology. ***P < 0.001; 2-way ANOVA, Bonferroni post hoc test (n = 12–16/group).