Fig. 5

Systemic human C-peptide supplementation inhibits HGM-induced vascular leakage and neurodegeneration in the retinas of HGM mice. After insulin-supplemented diabetic mice (HGM) were subcutaneously implanted twice with K8 polypeptide (HGM + K8) or K9-C-peptide (HGM + K9-C-peptide) depots twice for total 4 weeks, vascular leakage, expression of glial fibrillary acidic protein (GFAP) and glutamate aspartate transporter (GLAST), and neuro-apoptosis were analyzed by immunofluorescence or Western blotting in mouse retinas. A Visualization of vascular leakage by fluorescence angiography using FITC-dextran in the whole-mounted retinas of C57BL/6 and TGase2-null (Tgm2.^−/−) mice. Scale bar, 50 µm. B Visualization of GFAP and GLAST expression (red) with nuclear counterstaining using DAPI (blue) in retinal sections. Scale bar, 50 µm. Quantification of GFAP (C) and GLAST (D) expression based on fluorescence intensity (n = 6). E GFAP and GLAST expression was analyzed by Western blotting. F Visualization of TUNEL-positive cells (green) with nuclear counterstaining (blue). Scale bar, 50 µm. G Quantification of apoptotic cells (n = 6). Statistical significance was determined by one-way ANOVA with Holm-Sidak’s multiple comparisons test. NS, non-significant. ***P < 0.001