Abstract: AIM:To investigate the relationship between cerebroprotection of pinocembrin and epoxyeicosatrienoic acids(EETs) and their regulating enzyme soluble epoxide hydrolase(sEH).METHODS:Rats underwent middle cerebral artery occlusion(MCAO) to mimic permanent focal ischemia,and pinocembrin was administrated via tail vein injection at 10 min,4 h,8 h and 23 h after MCAO.After 24 MCAO,rats were re-anesthetized,and the blood and brain were harvested and analyzed.RESULTS:Pinocembrin displayed significant protective effects on MCAO rats indicated by reduced neurological deficits and infarct volume.Importantly,co-administration of 0.2 mg·kg-1 14,15-EEZE,a putative selective EET antagonist,weakened the beneficial effects of pinocembrin.14,15-EET levels in the blood and brain of rats after 24 h MCAO were elevated in the presence of pinocembrin.In an assay for hydrolase activity,pinocembrin significantly lowered brain sEH activity of MCAO rats and inhibited recombinant human sEH activity in a concentration-dependent manner(IC50,2.58 μmol·L-1).In addition,Western blot and immunohistochemistry analysis showed that pinocembrin at doses of 10 mg·kg-1 and 30 mg·kg-1 significantly down-regulated sEH protein in rat brain,especially the hippocampus CA1 region of MCAO rats.CONCLUSION:Inhibiting sEH and then increasing the potency of EETs may be one of the mechanisms through which pinocembrin provides cerebral protection.