Naringenin Exerts A Neuroprotective Effect Via The NOD2/RIP2/NF-κB Signaling Pathway In A Neonatal HIE Rat Model

Objective:To explore the protective effects and mechanism of naringin on hypoxic ischemic brain injury in neonatal rats.Methods:1.Seven-day old（P10）rat pups underwent right common carotid artery ligation followed by 2.5 h of hypoxia as previously described by Rice-Vannucci.40 seven-day neonatal Sprague-Dawley（SD）rat pups were randomly divided into sham operation group and hypoxic-ischemic brain damage group（HIBD group）.Time-course expression levels of endogenous NOD2 protein involved in naringin’s protective effects were measured using western blot.2.96 seven-day neonatal SD rats were randomly divided into sham operation group,HIBD group,HIBD with low-dose naringenin group（50mg·kg-1,NG-L）and HIBD with high-dose naringenin group（100 mg·kg-1,NG-H）.Neurobehavior studies,HE staining and brain water content were measured at 48h after HIE.The expressions of NOD2、RIP2 and NF-κB were detected by western blot.The expresstion of TNF-αand IL-1βexpression were measured using Enzyme linked immunosorbent assay.3.40 seven-day neonatal SD rats were randomly divided into sham operation group,HIBD group,MDP group,MDP with naringenin group（MDP+NG）and naringenin group（NG）.The expressions of NOD2,RIP2 and NF-Κb was performed by western blot at 48h after HIE.Results:1 Time course results showed that the expression of NOD2 protein were significantly upregulated after HIE,peaking at 24 h post HIE and then decreased by 48h and 72 h.2Neurobehavioral studies showed that HIE induced a significant delay in development and resulted in cognitive and motor function deficits at 48h after HIE.The cognitive and motor function deficits had been had significantly reduced by naringenin（NG-L and NG-H）treatment（P<0.05）at 48 h post HIE.The pathological damage and the water content of brain tissues was markedly decreased by naringenin（NG-L and NG-H）treatment（P<0.05）.Western blot results revealed that the down-regulation of the expression of NOD2,RIP2 and NF-κB by naringenin（NG-L and NG-H）treatment（P<0.05）.The content of TNF-αand IL-1βin brain tissue were lower than HIBD group（P<0.05）.3 All downstream target proteins,NOD2,RIP2 and NF-κB showed to increase in HIBD group when compared to sham,and treatment group further increased their expression levels（P<0.05）at 48h after HIE.However,MDP effectively decreased expression of NOD2,RIP2and NF-κB at 48 h after treatment（P<0.05）.Conclusion:Naringin(50 mg·kg^-1,100 mg·kg^-1)decreased HIE-induced inflammation and improved neurobehavioral outcomes and the pathological damage which may be mediated by the NOD2/RIP2/NF-κB signaling pathway after HIE.