Figure 2. Immunohistochemical staining for 4-hydroxy-2-nonenal (HNE), 4-hydroxyhexenal (HHE), and malondialdehyde (MDA) modified proteins (green fluorescence) in transverse cryosections of retina from nondiabetic (NonDb) and diabetic (Db) rats of 4 months disease duration. Propidium iodide was used to counterstain cell nuclei (red fluorescence). In nondiabetic retina, weak diffuse immunoreactivity for each of these advanced lipoxidation end products (ALEs) was detected, although stronger cytoplasmic staining for 4-HHE and MDA-modified proteins was observed for a small number of cells located within the ganglion cell layer (GCL) and at the outer border of the inner nuclear layer (INL; arrows). Immunolabelled sections from diabetic rats appeared similar to those of nondiabetic rats. When quantified, no significant differences in the intensity of staining for 4-HNE, 4-HHE, and MDA modified proteins was apparent between retinas from the nondiabetic and diabetic animals.