Docosahexaenoic acid, but not eicosapentaenoic acid, improves septic shock-induced arterial dysfunction in rats

INTRODUCTION: Long chain n-3 fatty acid supplementation may modulate septic shock-induced host response to pathogen-induced sepsis. The composition of lipid emulsions for parenteral nutrition however remains a real challenge in intensive care, depending on their fatty acid content. Because they have not been assessed yet, we aimed at determining the respective effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) during septic shock-induced vascular dysfunction. METHODS: In a peritonitis-induced septic shock model, rats were infused with EPA, DHA, an EPA/DHA mixture or 5% dextrose (D5) during 22 hours. From H18, rats were resuscitated and monitored during 4 hours. At H22, plasma, aorta and mesenteric resistance arteries were collected to perform ex vivo experiments. RESULTS: We have shown that septic rats needed an active resuscitation with fluid challenge and norepinephrine treatment, while SHAM rats did not. In septic rats, norepinephrine requirements were significantly decreased in DHA and EPA/DHA groups (10.6±12.0 and 3.7±8.0 μg/kg/min respectively versus 17.4±19.3 μg/kg/min in D5 group, p<0.05) and DHA infusion significantly improved contractile response to phenylephrine through nitric oxide pathway inhibition. DHA moreover significantly reduced vascular oxidative stress and nitric oxide production, phosphorylated IκB expression and vasodilative prostaglandin production. DHA also significantly decreased polyunsaturated fatty acid pro-inflammatory mediators and significantly increased several anti-inflammatory metabolites. CONCLUSIONS: DHA infusion in septic rats improved hemodynamic dysfunction through decreased vascular oxidative stress and inflammation, while EPA infusion did not have beneficial effects.