Effect of Eicosapentaenoic Acid on Glucose-Induced Diacylglycerol Synthesis in Cultured Bovine Aortic Endothelial Cells

Abstract

Hyperglycemia has been postulated to increase diacylglycerol (DAG) level through de novo synthesis pathway and subsequently activate protein kinase C (PKC) in vascular cells, possibly leading to vascular dysfunction associated with diabetes. In this study, we examined the effect of eicosapentaenoic acid (EPA) on high glucose-induced increase in DAG level in cultured aortic endothelial cells (ECs). In ECs, total DAG level was significantly increased in the cells cultured with high glucose levels (400 mg/dl) compared with the cells with normal glucose levels (100 mg/dl). The addition of EPA completely prevented high glucose-induced increase in total DAG level. In contrast, other common fatty acids such as palmitate and oleate significantly stimulated DAG syntheisis, although arachidonate did not affect it. High glucose level significantly stimulated the incorporation of3H-palmitate into DAG, while it did not affect the incorporation of3H-arachidonate into DAG. The addition of EPA completely prevented the high glucose-induced increase in3H-palmitate incorporation into DAG, while it did not affect the3H-arachidonate incorporation. These findings suggest that EPA can prevent high glucose induced-increase in DAG level in ECs, probably by specifically inhibiting de novo synthesis at the step of acylation. EPA may be one of the candidates for clinical agents normalizing activation of DAG-PKC pathway in diabetic vascular tissues and preventing vascular complications associated with diabetes.