Figure 1.
Reduced OPL width in aging DBA/2J mice.
(A) The extension of the total outer plexiform layer (OPL; 1) and the synaptic OPL (2) was measured in vertical retinal sections stained with DAPI (blue) and an antibody against RIBEYE (green). (B) The synaptic OPL/total OPL ratio did not change in 2 to 10 months old C57BL/6 control mice, but significantly decreased in the age-matched DBA/2J mice (*** p<0.001). ONL, outer nuclear layer; INL, inner nuclear layer. Scale bar: 2 µm.
Figure 2.
Altered photoreceptor synaptic ribbons in aging DBA/2J mice.
(A–D) Representative examples of regions of the OPL of C57BL/6 (A,C) and DBA/2J retinae (B,D) double labeled for RIBEYE (green) and Bassoon (magenta). The boxes indicate the selected rod photoreceptor ribbons, which are shown at higher magnification. Whereas in the C57BL/6 retinae the rod photoreceptor ribbons displayed their typical horseshoe shape (A,C), the photoreceptor ribbons in the DBA/2J retinae lost their compact appearance as indicated by RIBEYE staining (B,D). This is most obvious in 10 months old DBA/2J mice (D). (E,F) Quantification of the number of horseshoe-shaped Bassoon (E) and RIBEYE (F) stainings in 500 µm2 OPL areas. Whereas the number of horseshoe-shaped Bassoon stainings did not change with age in DBA/2J and C57BL/6 control mice, the number of horseshoe-shaped RIBEYE stainings significantly decreased in aging DBA/2J mice (*** p<0.001). Scale bars: 2 µm (for A–D) and 1 µm (for inserts).
Figure 3.
Rod photoreceptor synaptic ribbons disintegrate in aging DBA/2J mice.
Synaptic ribbon profiles were classified as rod-shaped (A), club-shaped (B), and spherical-shaped (C). (D) Number of ribbon shapes in retinae of 2, 6, and 10 months old DBA/2J and C57BL/6 control mice. In the C57BL/6 control retinae the majority of the rod photoreceptor synaptic ribbon profiles was rod-shaped at all ages. In the DBA/2J retinae the number of rod-shaped ribbon profiles decreased and the number of spherical-shaped ribbon profiles increased with age. Scale bar: 0.2 µm (for A–C).
Figure 4.
No changes in retinal structure and neuronal morphologies in aging DBA/2J mice.
Double labelings with antibodies against Calbindin (green) and Calretinin (magenta) (A,B) or against CaBP5 (green) and VGluT1 (magenta) (C,D) show no obvious differences in retinal structure and neuronal morphologies between aging DBA/2J and C57BL/6 control mice. Retinal layers are indicated (OS, outer segments; IS, inner segments; ONL, outer nuclear layer; OPL, outer plexiform layer; INL, inner nuclear layer; IPL, inner plexiform layer; GCL, ganglion cell layer). Scale bar: 20 µm.
Figure 5.
C1qA and C1qC gene expression is upregulated in photoreceptor cells of aging DBA/2J mice.
(A) Agarose gels showing PCR fragments that represent the gene expression of C1qA, C1qB and C1qC in the retinae of 2 and 6 months old DBA/2J and C57BL/6 control mice. (B) The expression of C1qA, C1qB and C1qC in photoreceptor cells of 2, 6, and 10 months old DBA/2J mice and age-matched C57BL/6 control mice was compared with PCR. For each age, cDNA obtained from three animals was subjected to triplicate PCR amplifications (n = 9). Statistically significant differences are indicated by asterisks (* p<0.05; ** p<0.01).
Table 1.
Changes of C1q transcript levels.