The Role And Mechanism Of Rivaroxaban On Hemorrhagic Transformation In A Diabetes Ischemic Stroke Model

Background and purpose: Stroke includes ischemic stroke and hemorrhagic stroke,and ischemic stroke accounts for over 80% of all strokes,with high morbidity and mortality.Atrial fibrillation(AF)is a well accepted high-risk factor of ischemic stroke,which may cause large artery occlusion and severe infarct volume.In order to prevent cardiogenic cerebral embolism,AF patients are often recommended to take anticoagulants.Management of acute ischemic stroke in diabetes patients with a novel anticoagulant is challenging because of a putative increased risk of intracerebral hemorrhage.Ischmic stroke in diabetes leads to large infarct volume and high risk of hemorrhagic transformation(HT).Previous studies have revealed that Warfarin leads to severe HT in normal stroke rats,while no increased HT risk is found in novel anticoagulants treated rats.In this article,we evaluated whether the safety of Rivaroxaban maintains in diabetic experimental stroke rats.Methods: A.Diabetes was induced intraperitoneally by 60 mg/kg streptozotocin(STZ)in 100 male Spraque-Dawley(SD)rats.Animals with fasting blood glucose(FBG)concentrations above 16.8 mmol/L were considered diabetic 3 days after injection.B.Ninety-six SD rats were randomly divided into four groups:(1)the Normal group: normal rats underwent transient middle cerebral artery occlusion(t MCAO)for 1 h and reperfusion;(2)the Diabetic Control group: Diabetic rat model was eatablished according to the protocol above.Four weeks later diabetic rats underwent 1 h t MCAO;(3)the Rivaroxaban group: Diabetic rat model was eatablished according to the protocol above.Four weeks later the rats were pretreated orally with 30 mg/kg Rivaroxaban and then underwent 1 h t MCAO;(4)the Diabetic Sham group: diabetic rats had the same operation procedure done but with only superficial filament insertion into proximal internal carotid artery.After 24 h reperfusion,infarct volumes were determined from 2,3,5-triphenyltetrazoliumchloride stained brain sections and functional scores were assessed.HT was quantified using a macroscopic hemorrhage score.Blood-brain barrier(BBB)permeability was measured by Evans Blue spectrophotometry.Markers for the tight junction at the ischemic lesion were examined by Western Blot,and matrix metalloproteinase-9(MMP-9)activity was measured by gelatin zymography.Results: A.FBG before STZ injection was 5.17±0.55 mmol/L and 3 days after STZ injection was 26.48±3.72 mmol/L.No diabetic rat died 4 weeks after STZ injection and FBG was 27.12±4.26 mmol/L.B.Diabetic rats showed an increased infarct volume(34.48±6.90% vs 17.67±1.76%,respectively,P=0.04)24 h after t MCAO than normal rats.No HT was found in Normal group while the incidence of HT in Diabetic Control group was 66.67%(8/12)and median HT score was 1.5(quartile:0-2.75,P<0.0001).Infarct volumes(38.07±8.11%,P=0.74)and functional outcomes(2.75±0.18 versus 2.64±0.20 for Bederson scale score,P=0.70;and 7.42±0.42 versus7.93±0.29 for Garcia scale score,P=0.31)did not differ between the Rivaroxaban group and the Diabetic Control group.No significant increase in HT scores(median1.5,quartile: 0-3,P=0.88)under Rivaroxaban treatment could be found 24 h after t MCAO.BBB permeability in the Diabetic Control group was 15.67±3.36 μg/mg,and in the Rivaroxaban group was 16.00±3.18 μg/mg.No significant difference existed(P=0.94).C.Compared with the Diabetic Sham group(0.53±0.04),occludin expression was significantly lower in the Diabetic Control group(0.39±0.02,P=0.01),and MMP-9 activity was significantly higher(0.41±0.03 vs 1.61±0.04,repectively,P<0.0001).In the Rivaroxaban group,occludin expression did not further decrease(0.34±0.03,P=0.19)and MMP-9 activity did not further increase(1.77±0.09,P=0.14).Conclusion: A.Intraperitoneal STZ injection is a successful method to establish diabetic rat model.B.Diabetes will increase the severity of infarct volume and HT.Rivaroxaban treatment will not affect infarct volume,HT and neurological outcome in diabetes.C.Ischemic stroke in diabetes induces severe BBB permeability;including decreasing occludin expression and increasing MMP-9 activity.Our data suggest that Rivaroxaban has fewer effects on postischemic BBB permeability,indicating the possibility that Rivaroxaban is a safer anticoagulant for the diabetic stroke population.