Establishing A Rat Model Of SSS Thrombosis Via Suture-Occluded Method And Analyzing Changes After Recanalization

Part? Establishing a rat model of SSS thrombosis via suture-occluded methodObjective:To establish a new CVST model by suture-occluded method,verify the stability and reliability of this model,and explore the pathogenesis,development and related pathophysiological mechanism of CVST.Methods:84 SD rats were randomized into 2 groups:sham group(n=42)and CVST group(n=42).In this study,based on the design principle of the MCAO model,the SSS thrombosis model was constructed by inserting a self-made suture-occluded from SSS front to inside.There is a certain individual difference in the SSS diameter of rats.The suture-occluded is made according to the data obtained by measuring the SSS multiple times(the length is about 1cm and the diameter is about 1.2 mm).The CVST model was established by inserting suture through SSS front to inside,and then the cerebral surface blood flow changes before and after thread insertion were evaluated by Laser speckle blood flow imaging system.The postoperative cerebral vascular morphology and blood flow changes were monitored by MRA tracking.The vascular morphology was further evaluated by combining gross manifestations and microscopic observation,and the pathological changes of CVST were observed by HE staining.Results:In this part,CVST models were successfully constructed by blocking SSS with suture-occluded.The blood flow in SSS basically disappeared after suture insertion,and the blood flow in BV and CAP decreased significantly compared with pre-operation.SSS was in a continuous occlusion condition post-operation,while blood flow in the straight sinus was increased.At the 7th day post-operation,new small blood vessels appeared in the parasinus brain tissue,and the number of these vessels increased at the 14th day post-operation.The microscopical results showed that venous congestion dilatation occurred on the surface of the brain,and anastomotic access was established between these veins.Conclusion:The SSS thrombosis model establishment with suture-occluded method has many advantages,such as easy to operate,good stability,could accurately control the ischemic time and location,and could verify the collateral circulation secondary to CYST.Part ? Changes of blood flow after recanalization of the superior sagittal sinus in CVST ratsObjective:To observe the changes of blood flow and related pathophysiological changes after recanalization of occlusive in CVST rats.Methods:42 suture-occluded CVST rats were randomly grouped according to different detection methods.HE staining(n=16),gross manifestations(n=16),LSI(n=4),MRI(n=6).Pull out suture-occluded after 6 h SSS occlusion,witch simulate mechanical thrombectomy in clinical application,evaluate changes of blood flow on the brain surface before and after recanalization with the laser speckle blood flow imaging system,and monitor the cerebral vascular morphology and blood flow changes after recanalization with MRA tracking,combined with the general performance and the microscopic observation to further assess the vascular morphology,observed the pathological changes of brain tissue after recanalization by HE stainingResults:The blood flow in all SSS and part of BV rats was improved after pulling out suture-occluded,but could not completely restored immediately.As time goes on,the recanalization rate of SSS gradually increased,but it remained stable after reaching a certain level.After pulling out suture-occluded,the blood flow in MCA branches and brain surface CAP increased compared with that before SSS block.There was no obvious change of blood flow in the straight sinus and no obvious dilatation of blood vessels on the surface of brain.HE staining showed that brain tissue had no obvious edema,and no necrosis of neurons and glial cells was found.Conclusion:Rapid recanalization after SSS occlusion could significantly accelerate recovery without ischemia reperfusion injury.Early mechanical thrombectomy is a safe and effective treatment for patients with CVST.Part ? Observation of brain tissue damage secondary to SSS thrombosis in ratsObjective:To investigate the pathophysiological mechanism of brain tissue damage secondary to SSS thrombosis in ratsMethods:183 rats were randomly divided into groups:sham group(n=61),CYST group(n=61)and recanalization group(n=61).The changes of cerebral edema in CVST rats were observed using 7.0T magnetic resonance scanning,T2WI and DWI sequence tracking,and the ADC value was quantified,thus could identify the types of cerebral edema.Ultrastructural changes of tightly connected BBB were observed by transmission electron microscopy,and the expressions of claudin-5 and ZO-1 and their concentrations in serum were detected by ELISAResults:After model was established,the extent and degree of edema peaked on 3rd days after surgery,and then gradually decreased.The ADC value decreased firstly and then increased,but there was no significant change,and it decreased significantly only on the 3rd day post-operation.On the 3rd day post-operation,the local high signal shadow appeared on DWI,and then subsided.No obvious abnormal changes were observed on T2WI.The closely connected endothelial cells started dehisced partially on the 3rd day,and the expression level of claudin-5 was significantly reduced at this time,and the claudin-5 concentration in serum reached the highest level on the 3rd day and then gradually recovered after the 7th day.There was no significant change in the expression of ZO-1 between vascular endothelial cells or the ZO-1 concentration in the serum.The rats in the recanalization group showed no obvious changes in brain edema and no destruction on the tight connection,and the claudin-5 and ZO-1 concentrations in serum showed no significant changes.Conclusion:In the SSS thrombosis model of rats,mild cerebral vasogenic edema was the main manifestation,and reversible cytotoxic edema was observed in the early stage.BBB is destroyed at the early stage and then gradually recovered,and the claudin-5 concentration in serum changes synchronously with vasogenic edema and BBB destruction in the time course.Removing the venous sinus occlusion as soon as possible could significantly accelerate the disease recovery,and reduce brain edema,BBB damage and other injuries.