Fig. 2

Optic nerve and soma degeneration in C3ar1^−/− and C3ar1^+/+ mice. a Degeneration in PPD-stained optic nerve cross-sections was evaluated based on the presence of axon loss, degenerating axons, and scarring. Examples of degenerating axons (arrow) and glial scarring (asterisk) are indicated. Optic nerve damage in each nerve was classified as ‘no or early’ (NOE), ‘moderate’ (MOD), and ‘severe’ (SEV; see the ‘Methods’ section). Similar signs of degeneration were observed in C3ar1^−/− and C3ar1^+/+ mice. b Distribution of optic nerve damage by genotype and age. At 10.5 months of age (mos.), a significantly lower percentage of eyes in C3ar1^−/− mice had identifiable glaucomatous degeneration (MOD or SEV damage level; N = 110; P < 0.0001). At 12.5 mos, there was no longer a difference in the incidence of optic nerve degeneration between genotypes (N = 110; P = 0.59). c, d As axonal and somal degeneration of RGCs can be uncoupled by some mutations [40], RGC layer cells were assessed in Nissl stained retinal flat mounts from mice with and without optic nerve degeneration (SEV and NOE, respectively). Genotype had no effect on RGC degeneration in relation to axon loss. The number of RGC layer cells in eyes with healthy optic nerves was similar in C3ar1^−/− and C3ar1^+/+ mice. Loss of RGC layer cells in eyes with severe optic nerve damage was independent of C3ar1 genotype. e Mean PERG amplitudes were determined in the eyes of young (3 mos.), normotensive and older (10 mos.), ocular hypertensive mice. At 10 months of age, a majority of standard DBA/2J mice do not have significant optic nerve degeneration. C3ar1 deficiency had no influence on mean PERG amplitude at ages before or after they were affected by ocular hypertension. Boxes define the 75th and 25th percentiles and their middle line indicates the median value. Scale bars: 50 μm