Figure 4. Co-localization of Nε-(3-formyl-3,4-dehydropiperidino)lysine (FDP-lysine) and glial fibrillary acidic protein (GFAP) in the diabetic retina. Retinal sections from nondiabetic (NonDb) and diabetic (Db) rats were labeled with 4',6-diamidino-2-phenylindole (DAPI) nuclear stain (A and E), GFAP (B and F), and FDP-lysine (C and G). In the nondiabetic retina, GFAP immunoreactivity was selectively localized to astrocytes at the inner retinal surface. In diabetes, Müller cells acquired prominent GFAP immunoreactivity within their end feet at the vitreoretinal border and throughout their radial processes spanning from the inner to the outer limiting membranes. D and H: In merged images, FDP-lysine was found to co-localize strongly with GFAP in the retina of diabetic but not nondiabetic rats. The scale bars indicate 50 μm.