Activation of the AMP-Activated Protein Kinase by Eicosapentaenoic Acid (EPA, 20:5 n-3) Improves Endothelial Function In Vivo

Yong Wu,Yunzhou Dong,Shuangxi Wang,Ping Song,Cheng Zhang,Ming-Hui Zou,Benoit Viollet,Yu Huang

doi:10.1371/journal.pone.0035508

Abstract

The aim of the present study was to test the hypothesis that the cardiovascular-protective effects of eicosapentaenoic acid (EPA) may be due, in part, to its ability to stimulate the AMP-activated protein kinase (AMPK)-induced endothelial nitric oxide synthase (eNOS) activation. The role of AMPK in EPA-induced eNOS phosphorylation was investigated in bovine aortic endothelial cells (BAEC), in mice deficient of either AMPKα1 or AMPKα2, in eNOS knockout (KO) mice, or in Apo-E/AMPKα1 dual KO mice. EPA-treatment of BAEC increased both AMPK-Thr172 phosphorylation and AMPK activity, which was accompanied by increased eNOS phosphorylation, NO release, and upregulation of mitochondrial uncoupling protein-2 (UCP-2). Pharmacologic or genetic inhibition of AMPK abolished EPA-enhanced NO release and eNOS phosphorylation in HUVEC. This effect of EPA was absent in the aortas isolated from either eNOS KO mice or AMPKα1 KO mice fed a high-fat, high-cholesterol (HFHC) diet. EPA via upregulation of UCP-2 activates AMPKα1 resulting in increased eNOS phosphorylation and consequent improvement of endothelial function in vivo.

Highlights

Eicosapentaenoic acid (20:5Delta (5,8,11,14,17); v-3: eicosapentaenoic acid (EPA)) is an v-3 polyunsaturated fatty acid (PUFA), which is abundant in fish oils
EPA induces AMPK phosphorylation and activation To investigate whether EPA activates AMPK in endothelial cells, confluent bovine aortic endothelial cells (BAEC) or Human umbilical vein endothelial cells (HUVEC) were treated with varying concentrations of EPA for 2 to 24 h
AMPK is activated by a rise in AMP and a decrease in ATP, both of which occur by inhibiting ATP production or accelerating ATP consumption [14]

Summary

Introduction

Eicosapentaenoic acid (20:5Delta (5,8,11,14,17); v-3: EPA) is an v-3 polyunsaturated fatty acid (PUFA), which is abundant in fish oils. The precise mechanism by which fish oils inhibit atherosclerosis is still unclear, but it may relate to the modulation of lipid metabolism [3], improvement of vascular endothelial function [4], enhancement of vascular reactivity and compliance [5], reduction of cytokine production [6], and inhibition of inflammatory processes [7]. Long term oral administration of EPA may stimulate NO production, and increased NO levels likely inhibit enhanced cardiac sympathetic activity in these animals [9]. Accumulating evidence shows that v-3 PUFA can regulate NOS activity and increase NO synthesis in endothelial cells and vascular smooth muscle cells [12,13]. The mechanisms underlying v-3 PUFA-enhanced NO release remain poorly understood

Objectives

Methods

Results

Conclusion