Figure 1.

SST increases survival and decreases apoptosis and caspase-8 activation induced by hyperglycemia in 661W photoreceptors and retinal explants. The 661W cells were cultured under basal conditions (B) or in medium supplemented with 55 mM glucose (HG) during 24 or 48 h in the absence or presence of 10⁻⁶ M somatostatin (SST). A: Analysis of cellular survival measured with crystal violet staining. B: Analysis of the percentage of apoptotic (hypodiploid) cells with iodine propidium staining with flow cytometry. Results are means ± standard error of the mean (SEM; n = 5 independent experiments performed in triplicate). C: 661W cells were cultured under basal conditions (B) or with medium supplemented with 55 mM glucose (HG) during 24 h in the absence or presence of 10⁻⁶ M SST. The activation of caspase-8 was expressed by the ratio of the 35-kDa active fragment/65-kDa proform that was analyzed with western blot. β-actin was used as a loading control. A representative experiment out of three is shown. The graph corresponds to the quantification and statistical analysis of data corresponding to three independent experiments performed in duplicate. D: Retinal explants were prepared from the C57BL/6 mice and treated with basal medium (B) or medium supplemented with 55 mM glucose (HG) during 24 or 48 h in the presence or absence of SST (10⁻⁶ M). Caspase-8 enzymatic activity was analyzed with the fluorometric method. Results are means ± SEM (n=5 independent retinas per condition); *p<0.05 versus basal or †p<0.05 versus HG condition at each time.