n-3 Polyunsaturated Fatty Acids Reduce Neonatal Hypoxic/Ischemic Brain Injury by Promoting Phosphatidylserine Formation and Akt Signaling

Wenting Zhang, MD, PhD;Jia Liu, MD;Xiaoming Hu, MD, PhD;Peiying Li, MD, PhD;Rehana K. Leak, PhD;Yanqin Gao, PhD;Jun Chen, MD

Background and Purpose—Omega-3 polyunsaturated fatty acids (n-3PUFAs) attenuate neonatal hypoxic/ischemic (H/I) brain damage, but the underlying mechanisms are not fully understood. This study tested the hypothesis thatn-3PUFAs enhance Akt-dependent prosurvival signaling by promoting the biosynthesis of phosphatidylserine in neuronal cell membranes.

Methods—Dietaryn-3PUFA supplementation was initiated on the second day of pregnancy in dams. H/I was induced in 7-day-old rat pups by ipsilateral common carotid artery occlusion followed by hypoxia (8% oxygen for 2.5 hours). Neurological outcomes, brain tissue loss, cell death, and the activation of signaling events were assessed after H/I. The effects ofn-3PUFAs (docosahexaenoic acid and eicosapentaenoic acid) on oxygen-glucose deprivation–induced cell death and the underlying mechanism of protection were also examined in primary cortical neuron cultures.

Results—n-3PUFAs reduced brain tissue loss at 7 days after H/I and improved neurological outcomes, whereas inhibition of PI3K/Akt signaling by LY294002 partially abrogated this neuroprotective effect. Docosahexaenoic acid/eicosapentaenoic acid also prevented ischemic neuronal death through the Akt prosurvival pathway in vitro. Furthermore, docosahexaenoic acid/eicosapentaenoic acid increased the production of phosphatidylserine, the major membrane-bound phospholipids, after ischemia both in vitro and in vivo. A reduction in membrane phosphatidylserine by shRNA-mediated knockdown of phosphatidylserine synthetase-1 attenuated Akt activation and neuronal survival after docosahexaenoic acid/eicosapentaenoic acid treatment in the oxygen-glucose deprivation model.

Conclusions—n-3PUFAs robustly protect against H/I-induced brain damage in neonates by activating Akt prosurvival pathway in compromised neurons. In addition,n-3PUFAs promote the formation of membrane phosphatidylserine, thereby promoting Akt activity and improving cellular survival.

Stroke.2015;46:2943-2950