Involvement of JNK signal transduction pathway in endothelial cell apoptosis induced by intermittent high glucose

Abstract

To evaluate the effect of intermittent high glucose on the apoptosis of human umbilical vein endothelial cells (HUVECs) and its mechanism. Intermittent high glucose and constant high glucose were applied to HUVEC-12 for 7 days. Flow cytometer and fluorescent staining with Hoechst 33258 were used to detect apoptosis of HUVEC-12. The superoxide dismutase (SOD) activity and the content of malonaldehyde (MDA) in culture solution were detected with colorimetry, and the changes of p-JNK level were examined by Western blot. The apoptosis rate was obviously higher in the intermittent high glucose group than that in the constant high glucose group (P < 0.05). The SOD activity was significantly lower in the intermittent high glucose group (P < 0.05), but MDA level was higher than those of constant high glucose(P < 0.05). SP600125, the inhibitor of JNK, decreased the apoptosis rate induced by intermittent high glucose (P < 0.05). Antioxidant (Vitamin C) inhibited the p-JNK, decreased the apoptosis rate (P < 0.05). Intermittent high glucose is easier to worsen the proapoptotic effects on HUVECs than that of constant high glucose, which may account for the increased oxidative stress, and then activates JNK signal transduction pathway.