The Omega-3 Polyunsaturated Fatty Acids In The Neonatal Rat Brain Ischemia And Hypoxia Injury Mechanism

Neonatal hypoxic/ischemic (H/I) encephalopathy is an important clinical problem associated with acute morbidity and permernant mortality in infants and children. Despite of extensive researches on hypoxia/ischemia, no effective strategy is available for the prevention and treatment of this disease. OMEGA-3 polyunsaturated fatty acids (n-3 PUFAs) highly enriched in brain are a family of unsaturated fatty acids that are essential for the anatomical, biochemical and biological integrity of the brain. Docosahexaenoic acid, one of the most important members, demonstrated neuroprotective effect in adult brain suffered from focal cerebral ischemia. However, the underlying mechanism is still under investigation. We therefore examined the effect, as well as the potential mechanism of n-3 PUFAs in neonatal hypoxic/ischemic brain damage.Female rats were given diet supplemented with or without n-3 PUFAs enriched fish oil from the seccond day of pregnancy to 14 days after parturition. H/I was induced in seven-days old neonates by unilateral carotid artery ligation followed by 2.5 hours of hypoxia. Tissue loss analysis was performed by cresyl-violet staining on fixed brain slices at indicated time points. Neurological function was respectively assessed at 2 to 5 days for short-term performance and 2 to 5 weeks for long-term outcomes after H/I by using gait testing, righting reflex, grid walking and Morris water maze, respectively. Cortical lipid profile was performed on 14 days old neonates from different group. Animals were sacrificed 0 to 24 hours for detecting protein expression, DNA damage and cell death. Real-time PCR was performed at 24 hours after H/I to analysis the expression of inflammatory factors, and inflammatory response of microglia was also detected within 7 days after H/I. In addition, primary neurons and microglia cell line were resprectively used to investigate the effect of n-3 PUFAs on OGD and LPS induced cell damage in vitro.In our study, n-3 PUFAs-enriched fish oil supplementation significantly elevated cerebral n-3 PUFAs content, which also prevented decrease of n-3 PUFAs post H/I. n-3 PUFAs significantly alleviated H/I-induced brain damage and neurological deficits, and protected against oxygen-glucose deprivation-induced neuronal death. Perinatal n-3 PUFAs supplementation was attributed to enhance phosphorylation of Akt in neurons. Meanwhile, n-3 PUFAs exerted an anti-inflammatory effect in microglia, both in in vivo model of H/I and in in vitro microglial cultures subjected to inflammatory stimuli, by inhibiting NF-κB activation and subsequent release of inflammatory mediators, which was beneficial to preserve the neuronal survival.Taken together, our results suggested that perinatal administration of n-3 PUFAs increased the cortical concentration of n-3 PUFAs and exhibited the prolonged protection in H/I. n-3 PUFAs confers potent neuroprotection against neonatal H/I brain injury via, at least partially, enhancing the activation of PI3-K/Akt pathway and suppressing microglial-mediated inflammatory response. Thus, n-3 PUFAs is a potential novel therapeutic agent for neonatal H/I brain injury.