Reduced axonal transport in optic nerve of mice transgenic for human mutant P301S tau increases neuronal susceptibility to injury.

<p>Retinal ganglion cell (RGC) survival was quantified following a mild unilateral excitotoxic injury of the left eye (LE) by counting NeuN-positive nuclei in the RGC layer of the whole-mounted retina of 1, 3 and 5 month old mice (A–D). Percentage RGC loss was calculated by comparing the number of surviving RGCs in injured retinas to that of the uninjured right eye (RE). Representative images of NeuN-positive nuclei in injured P301S tau transgenic (A) and C57/Bl6 (C) retinas from 5 month old animals, compared to uninjured contralateral retinas (B and D), are shown as an example. Statistical analysis revealed a significant increase in RGC death following mild excitotoxic injury in P301S tau transgenic retinas, compared to C57/Bl6 control retinas (E), at both 3 months and 5 months of age; however no difference in RGC excitotoxic death was found at 1 month of age between control and transgenic retinas. N-methyl-D-aspartic acid (NMDA) was used as the excitotoxin. Scale bar, 100 µm.