Abstract TP250: N-3 Fatty Acid Diglyceride Emulsions As A Novel Acute Treatment For Ischemic Brain Injury

Introduction: Omega-3 (n-3) fatty acids (FAs), specifically docohexaenoic acid (DHA) and eicosapentaenoic acid (EPA), act as bioactive unsaturated lipids with pleiotropic effects, affording neuroprotection in ischemic brain injury. Hypothesis: We reported that n-3 FAs injected acutely as triglyceride (TG) emulsions provide neuroprotection after ischemic brain injury. We now questioned whether novel lipid emulsions made from n-3 diglycerides (DG) would improve the delivery and effectiveness of n-3 FAs in brain after injury. Methods: We evaluated in vitro interactions of DG (DG-DHA) vs TG (TG-DHA) in phosphatidylcholine (PC) bilayer liposomes, as a model membrane system, by NMR spectroscopy. We compared the in vitro kinetics of DG vs TG hydrolysis by lipoprotein lipase. We investigated the neuroprotective effects of DG emulsions in a Vannucci murine model of hypoxic-ischemic (HI) brain injury. Results: NMR spectra of PC liposomes incubated with DG-DHA showed an additional peak, adjacent to the phospholipid carbonyl region, indicating a higher incorporation into PC bilayers and a narrower peak at almost the same position in a more fluid phase. In contrast, spectra of liposomes incubated with TG-DHA showed narrow peaks well-separated from PC resonances, representing phase-separated oil droplets. In lipolysis assays, DG emulsions had more efficient hydrolysis than TGs. Neonatal mice treated with DG-EPA, DG-DHA, or the combination of both (DG-DHA+EPA) after HI injury showed up to 3X better reduction in infarct volumes compared to TGs (p<0.05). Conclusions: Our data demonstrate that DG molecules incorporate in membrane bilayers more efficiently than TG. We postulate that the faster hydrolysis of DGs contributes to higher neuroprotection compared with TGs. Our findings indicate that n-3 DG emulsions represent a novel and much more efficient modality than n-3 TG for improving ischemic brain injury outcomes.