Résumé
BACKGROUND: Studies have demonstrated that intermittent high glucose can have a more severe impact on vascular endothelial function in comparison with persistent hyperglycemia.OBJECTIVE: To investigate the effect of intermittent high glucose on the proliferation and apoptosis of endothelial progenitor cells (EPCs) from human peripheral blood in vitro as well as the production of malondialdehyde (MDA) and antioxidant. METHODS: Total mononuclear cells were isolated from human peripheral blood by Ficoll density gradient centrifugation and then the cells were placed on fibronectin-coated culture dishes. After 7 days of culture, the adherent cells were identified as EPCs by laser scanning confocal microscope. The cells were synchronized and then stimulated with glucose 5.5 mmol/L (normal control group), 20 mmol/L (constant high glucose group), and 5.5/20 mmol/L (intermittent high glucose group, 5.5 and 20 mmol/L glucose culture solution was changed every 8 hours) for 72 hours. EPCs proliferation and apoptosis was measured by MTT assay and flow cytometry, respectively. The content of MDA and the activity of superoxide dismutase (SOD) in culture solution were detected with colorimetry.RESULTS AND CONCLUSION: After EPCs were exposed to constant high glucose (20 mmol/L) and intermittent high glucose (5.5/20 mmol/L) for 72 hours, proliferated cells were significantly reduced and the apoptosis rate was significantly increased compared with those exposed to normal glucose (P < 0.01). Furthermore, there was a significant increase in MDA contents as well as a significant reduce in SOD activities in the constant high glucose and intermittent high glucose group (P < 0.01), especially in the latter group. These findings indicated that both intermittent high glucose and constant glucose could inhibit the proliferation and promote the apoptosis of EPCs; however, intermittent high glucose appears to worsen the effects on EPCs. This is maybe due to the increased oxidative stress.
Résumé
Objective To detect the expression of vascular endotheilal growth factor (VEGF), stromal cell-derived factor-1α (SDF-1α), and its receptor CXCR-4 in the retinopathy of diabetic rats, and to explore the relationship between those factors and diabetic-retinopathy(DR). Methods Diabetes was induced in 40 rats with a single intraperitional injection of streptozotocin(STZ). Experimental rats were randomly divided into M1 (diabetic for 1 month), M3 (diabetic for 3 months), and M5 (diabetic for 5 months) groups, and another 10 rats served as a normal control group (NC). Retinal vascular status was observed by transmission electron microscope. After retinal stretched preparation, VEGF, SDF-1α and CXCR-4 immunohistochemistry were done. Retinal VEGF, SDF-1α, and CXCR-4 mRNA were detected by semi-quantitative RT-PCR. Protein expression was measured by Western blot. Results Under transmission electron microscope, change in vascular status was found in M1 to M5 groups, but not in the NC group. The changes became increasingly serious with the prolongation of the disease. By immunohistochemistry, we found the expression of VEGF, SDF-1α, and CXCR-4 on the retina increased gradually. It increased after injecting STZ for 1 month and increased significantly after 5 months.VEGF, SDF-1α, and CXCR-4 mRNA expression increased obviously after injecting STZ for 1 month and increased significantly after 5 months. Western blot showed that protein of VEGF, SDF-1α, and CXCR-4 had no change after injecting STZ for 1 month. It began to increase in the M3 group and increased most in the M5 group. Conclusion The expression of VEGF, SDF-1α, and CXCR-4 on the retina in retinopathy of diabetic rats increases gradually with the prolongation of the disease. It is an important factor for diabetic retinopathy.