Fig. 4.

MIMIR shows that axonal transport of mitochondria is more vulnerable to the glaucoma model in old mice than in adult mice. (A) A representative image showing MIMIR in an old OHT mouse (Movie S15). (Scale bar, 10 μm.) (B–D) In old OHT mice, we observed significant decreases in the number of mitochondria transported in axons (B) and in anterograde (C) and retrograde (D) transport as compared with adult OHT mice; *P < 0.0001. (E) The capacity to resist stresses in RGCs (solid blue line) is estimated by age-related changes in the duty cycle in Fig. 3J. Our results regarding the total organization of mitochondrial transport (Fig. 3N and SI Appendix, Fig. S11) suggest that the energy demand by homeostasis (green dotted line) does not exceed the capacity to resist stresses even in the RGCs of old mice. However, our results regarding the vulnerability of the axonal transport of mitochondria to the glaucoma model in old mice (B–D) suggest that the lower increase in energy demand resulting from stresses such as elevated intraocular pressure (orange dotted line) leads to metabolic dysfunction of RGCs in old mice (asterisk) as compared with adult mice (red dotted line and double asterisk). The two-tailed Mann–Whitney test was used to calculate P values in B–D. The results are shown as mean ± SEM. The sample size (n) for each group is given in SI Appendix, Table S1.