Fig. 1

Ocular hypertension promotes early RGC dendrite retraction and synapse loss. A Schematic of magnetic microbeads injection into the mouse anterior chamber to induce ocular hypertension (OHT). B This procedure results in gradual increase of intraocular pressure (IOP) leading to RGC soma and axon loss (ANOVA with Tukey’s multiple comparison post-hoc test, ***p < 0.001, N = 10–14 mice/group). C, D Quantitative analysis demonstrates a statistically significant loss of RGC soma and axons at 3 weeks after microbeads injection (ANOVA with Tukey’s multiple comparison post-hoc test, n.s. = not significant, ***p < 0.001, N = 5–14 mice per group). (E) YFP-positive RGC with a clearly identifiable axon (arrowhead) were selected for dendritic arbor imaging and 3D reconstruction. F, G Representative examples of RGC dendritic arbors from non-injured (sham) and glaucomatous retinas at 2 weeks after induction of OHT. H-K Quantitative analysis of dendritic parameters reveals a substantial reduction in dendritic area, length, number of branches, and complexity (Sholl analysis) in OHT retinas (blue) relative to sham controls (white) (Student’s t-test, **p < 0.01, ***p < 0.001, N = 6 mice/group, n = 40–51 RGC/group Table 1). L-N Glutamatergic synapses are visualized in the inner plexiform layer (IPL) on retinal cross-sections using immunolabeling against PSD95 (green) and VGLUT1 (red), post- and pre-synaptic markers, respectively. OHT injury (2 weeks) induces a pronounced loss of both VGLUT1 and PSD95 expression in the IPL. O High magnification of inset in (N) shows VGLUT1 and PSD95 puncta in the IPL at the level of the OFF sublamina in OHT and sham retinas. P Quantitative analysis of pre- and postsynaptic co-localized voxels, which measured the three-dimensional volume occupied by both VGLUT1 and PSD95 in the IPL, confirms that OHT promotes a striking loss of synapses (Student’s t-test, ***p < 0.001, N = 4 mice/group). Values are expressed as the mean ± S.E.M