Figure 5. Spatiotemporal characteristics of Nε-(3-formyl-3,4-dehydropiperidino)lysine (FDP-lysine) accumulation in diabetic Müller cells. A and B: Representative confocal images of FDP-lysine immunoreactivity in retinal sections from non-diabetic rats 1 and 4 months post injection of citrate buffer. C-F: Immunohistochemisty for FDP-lysine in retinal sections from STZ-diabetic rats 1, 2, 3, and 4 months after the induction of diabetes. The intensity of FDP-lysine staining initially increased in the end feet of Müller cells at the ILM after 2 months of diabetes (D, arrows) and subsequently spread throughout their inner processes extending from the ILM to the INL (E, F, arrows). G: Summary data revealed that FDP-lysine immunoreactivity was significantly increased in diabetic retina in regions of the ILM–GCL and IPL, 2 and 3 months following the onset of diabetes, respectively. There was no significant difference in FDP-lysine in the outer retina at any time point between the nondiabetic and diabetic groups. The scale bars refer to 50 μm.