Redox-Sensitive Induction of Src/PI3-kinase/Akt and MAPKs Pathways Activate eNOS in Response to EPA:DHA 6:1

Abstract

AimsOmega-3 fatty acid products containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have vasoprotective effects, in part, by stimulating the endothelial formation of nitric oxide (NO). This study determined the role of the EPA:DHA ratio and amount, and characterized the mechanism leading to endothelial NO synthase (eNOS) activation.Methods and ResultsEPA:DHA 6∶1 and 9∶1 caused significantly greater endothelium-dependent relaxations in porcine coronary artery rings than EPA:DHA 3∶1, 1∶1, 1∶3, 1∶6, 1∶9, EPA and DHA alone, and EPA:DHA 6∶1 with a reduced EPA + DHA amount, which were inhibited by an eNOS inhibitor. Relaxations to EPA:DHA 6∶1 were insensitive to cyclooxygenase inhibition, and reduced by inhibitors of either oxidative stress, Src kinase, PI3-kinase, p38 MAPK, MEK, or JNK. EPA:DHA 6∶1 induced phosphorylation of Src, Akt, p38 MAPK, ERK, JNK and eNOS; these effects were inhibited by MnTMPyP. EPA:DHA 6∶1 induced the endothelial formation of ROS in coronary artery sections as assessed by dihydroethidium, and of superoxide anions and hydrogen peroxide in cultured endothelial cells as assessed by electron spin resonance with the spin probe CMH, and the Amplex Red based assay, respectively.ConclusionOmega-3 fatty acids cause endothelium-dependent NO-mediated relaxations in coronary artery rings, which are dependent on the EPA:DHA ratio and amount, and involve an intracellular activation of the redox-sensitive PI3-kinase/Akt and MAPKs pathways to activate eNOS.

Docosahexaenoic acid reversed atherosclerotic changes in human endothelial cells induced by palmitic acid in vitro

“…Commensurate with these statements, one could hypothesize that the reduction of proinflammatory cytokines and prostaglandin may participate in therapeutic effects of DHA during atherosclerotic changes of ECs 28,29. Our study further demonstrated that Pal could increase the expression of eNOS and PTX3 genes, causing nitro-oxidative or nitrosative stress 32,33. Docosahexaenoic acid had potential to increase the NO level, which is thought to be essential in vasodilation and endothelial haemostasis and protection 30,31.…”

“…It is thought that this gene participates in the regulation of circulation. Addition of DHA to Pal-treated cells decreased the levels of IL-6 and PGE 2 to near control levels (Figures 2 and 5 32,33 With the data obtained from real-time PCR, exposure of Pal-treated HUVECs to DHA modulated, but not significantly, the expression levels of all 3 genes-eNOS, iNOS, and PTX3 genes-to near control levels. The mRNA level of FGA, playing a role in the regulation of blood pressure, was also found to decrease following the treatment of atherosclerotic ECs with DHA.…”

“…30,31 Our study further demonstrated that Pal could increase the expression of eNOS and PTX3 genes, causing nitro-oxidative or nitrosative stress. 32,33 It was previously stated that eNOS activation was initiated by omega-3 fatty acids like DHA by engaging Src/PI3kinase/Akt and MAPK signalling pathways. The activation of these pathways, in turn, leads to eNOS phosphorylation at the activator site serine 1177 residue.…”

An Intravenous Bolus of Epa

“…probably also their quality (32,33). Many of the effects of marine Omega-3 fatty acids would require intakes above 1 g/day (30).…”

“…In our study, we have used a ratio of EPA:DHA of 6:1 based on previous data on coronary artery rings showing that the ability of Omega-3 to stimulate the endothelial formation of NO⋅ depends on the EPA:DHA formulation ratio and amount (33). Finally, the purity of the EPA and DHA used here is guaranteed by the manufacturer to be of more than 95%, which is exceptional compared to the Omega-3 used in most studies.…”