Abstract: ObjectiveTo study the effect of green tea polyphenols(GTPs)on metabolic syndrome-related vascular hyperpermeability in rats.MethodsMale Wistar rats were randomly divided into 5 groups:normal control,high fat diet control,low,moderate,and high dose GTPs(100,200,400 mg/kg·bw·d)treated groups.GTPs intervention were applied when the body weight of the rats were up to 180 g.After 30 weeks,the permeability of aortic artery were measured with Evans blue injection method.The nitric oxide(NO)levels in the serum,the activity of inducible nitric oxide synthase (iNOS)and ehdothelial nitric oxide synthase(eNOS)was measured with commercial kit.The aortic artery of the rats were harvested and frozen slides were prepared.The reactive oxygen species(ROS)levels were tested by dihydroethidium(DHE)fluorescent probe.ResultsThe vascular permeability of the high fat diet group(0.19±0.006μg/mg)was significantly higher than that of the control group(0.16±0.007μg/mg).GTPs treatment downregulated the vascular permeability(0.16±0.004,0.14±0.010,and 0.15±0.010μg/mg,respectively)compared with that of the high fat diet group.The ROS level in GTPs treated groups was significantly lower than that of high fat diet group.Compared with the high fat diet group,GTPs upregulated eNOS activity and downregulated iNOS activity.ConclusionGTPs treatment has protective effects on metabolic syndrome related vascular hyperpermeability in rats.The mechanism might be related to the alleviation of oxidative damage.