Fig. 2

In-depth analysis of morphological and functional changes of retinal neurons in db/db mice. A Left, representative micrograph of a DAPI-staining of the retina of 9-month-old diabetic and control mice. Right, quantification of DAPI-positive nuclei in the three nuclear layers of the retina does not reveal major cell loss even in 9-month-old db/db mice. Scan field: 68 µm × 200 µm. B Left, calretinin immunolabeling delineates ganglion and displaced amacrine cells in the ganglion cell layer (GCL) and amacrine cells in the inner nuclear layer (INL). Representative micrographs of retinae from 9-month-old diabetic and control mice are shown. Right, the number of calretinin-positive cells per scan field of the GCL and INL is plotted. Scan field: 200 µm × 200 µm. C Left, cone photoreceptors including their outer segments are visualized by a cone-arrestin staining for which representative results are presented from 9-month-old animals. Scale bar, 20 µm. Right, the number of cones and the length of their outer segments (OS) was assessed in retinae from both genotypes. Unpaired t-test: *p < 0.05. D Top, representative micrograph of PDE6B immunoreactivity in rod OS in retinal sections from 9-month-old diabetic and control mice. Bottom, the rod OS length of retinae from db/db and control animals was measured. E Electroretinogram (ERG) recordings were performed on 6-month-old animals. Scotopic rod-specific b-wave, photopic cone-specific b-wave and mixed rod-cone–specific a- and b-wave were measured and quantified at 0,001 cd/ms, 30 cd/ms and 3 cd/ms, respectively. Right, representative ERG traces. Bars represent mean values ± SEM. N = 10 control animals and n = 11 db/db mice analysed. Unpaired t-test: *p < 0.05. A–D Scale bars, 20 µm. Bars represent mean ± SEM and data from 4 animals per age and genotype are shown, except for 9-month-old db/db mice where only 3 biological replicates were analysed. IPL inner plexiform layer, OPL outer plexiform layer, ONL outer nuclear layer, OS, outer segments