Experimental Study On Intraluminal Thread Approach In Making Focal Cerebral Ischemia Preconditioning Model In Rabbits

Partâ… Setting up intraluminal thread approach in making focal cerebral ischemia preconditioning model in rabbitsObjective:To investigate how to improve the stability and reproducibility of intraluminal thread approach in making focal cerebral isehemia/reperfusion preconditioning model in rabbits:Material and methods:Thirty-five rabbits were randomly divided into three groups:A,B and C.Control group(Group A,n=5)was sham-operated.Ischemia group(Group B,n=10),focal cerebral ischemia/reperfusion model was made under DSA by inserting a wire into MCA through lCA and CCA directly and pulling it out 4 hours later.The method of preconditioning group C(Group C,n=20)is similar to that of B.The wire was inserted into the initiation of MCA,which was pulled out 15 minutes later and pushed in another 15 minutes later,3 times repeatly.At last,the wire was inserted into the initiation of MCA and pulled out 4 hours later.Neurological deficit score,TTC and H-E staining were used to evaluate the effectiveness of models.Results:The course and bifurcation of ICA could be displayed clearly on the angiography.Eight in ten of group B(eighty percent)and twelve in twenty of group C(sixty percent)were successful models.White areas of TTC matched the infarction areas,but the infarction volumes of group C were less than B.Conclusion:This method can be adopted to set up a stable and feasible model of focal cerebral ischemia preconditioning.Partâ…¡Evaluating of intraluminal thread approach in making focal cerebral ischemia preconditioning model in rabbits on MRIObjective:To successively observe the signal changes in the rabbit models of unilateral middle cerebral artery occlusion within 72 hours after ischemia preconditioning with T₁WI,T₂WI,DWI,PWI,and to access the value of MRI in evaluating brain ischemia injury.Material and methods:New Zealand rabbits were randomly divided into three groups:A,B and C.Control group(Group A,n=5)was sham-operated.Ischemia group(Group B,n=10/11),focal cerebral ischemia/ reperfusion model was made by inserting a wire into MCA through ICA and CCA directly and pulling it out 4 hours later.The method of preconditioning group C(Group C,n=10/14)is similar to that of B.The wire was inserted into the initiation of MCA,which was pulled out 15 minutes later and pushed in another 15 minutes later,3 times repeatly.At last,the wire was inserted into the initiation of MCA and pulled out 4 hours later.Successful rabbits were examined by T₂WI,T₂WI_,DWI at 3h,6h,9h,12h,24h,72h;another each five of group B and C were examined by PWI at 6.5h.After MRI examination,each was performed TTC and H-E staining.Results:(1)In group B and C,the infarction areas showed abnormality high signal intensity on DWI and relatively high signal intensity on PWI 3h after MCAO,whereas the areas of relatively high signal intensity on PWI were larger than that on DWI,and the mismatch regions were indicated penumbra.(2)Abnormality high signal was occurred on T₂WI 4h after MCAO.At last,the high signal areas matched the results of TTC.(3)The volumes on DWI of group C were smaller than B,after 8h, the rising tendency of group C was slower than B.(4)On PWI,the signal of group B and C had not obvious difference.(5)No abnormality was found in contral group.Conelusion:(1)Infarction areas of TTC matching with the high signal areas on T₂WI suggests ischemia preconditioning can produce neuroprotective effect.(2)On DWI,after 8h,the rising tendency of group C being slower than B of DWI suggests ischemia preconditioning can produce neuroprotective effect.(3)Ischemia preconditioning has no relation with blood flow possibly.