Fig. 6

Tau is depleted from RGC axons in transgenic optic nerves. a-c Optic nerve cross sections colabeled with tau and NF-H display high levels of tau in RGC axons in 3-month-old wild-type (WT) mice. d-f Higher magnification images demonstrate co-localization of tau in NF-H-positive RGC axons. g-l In contrast, optic nerves from age-matched 3xTg animals show marked reduction of tau, which was not due to axonal loss as co-staining with NF-H confirmed an abundance of RGC axons. m-x Tau expression in 3xTg optic nerve axons was much reduced in older mice (6 months) as demonstrated by the marked loss of tau labeling in the optic nerve sections despite robust NF-H staining (n = 5/group). Scale bars: a–c, g-i, m-o, s-u = 10 μm (1000× magnification); d-f, j-l, p-r, v-x = 4 μm (2000× magnification). y, z Western blot analysis of tau expression in optic nerve protein homogenates from 3- and 6-month-old mice confirmed the loss of axonal tau in transgenic animals relative to controls (3-month-old 3xTg: n = 6, 3-month-old WT: n = 9, 6-month-old 3xTg: n = 4, 6-month-old WT: n = 4, Student’s t test, * = p < 0.05, n.s.: not significant p > 0.05). Vertical lines represent non-consecutive samples from the same gel