Establishment Of Brainstem Ischemia Reperfusion Model In Rat: Changes Of Pathologic And Blood Flow Of Brainstem After Brainstem Ischemia Reperfusion

Objective: The establishment of the brainstem ischemia reperfusion model ismeaningful to the research of pathology, pathophysiology and pharmacology ofinjure of brainstem ischemia and reperfusion. At present, there are few reportsabout this model in China and abroad. The past studies about brainstem ischemiaonly focused on pathophysiology, electrophysiology and biochemistry ofbrainstem continual ischemia, and focused on large animals such as dogs,cats andmonkeys. Comparing with these animals, rats have many advantages, so wechoose rats to establish the brainstem ischemic reperfusion model, earlier changesof pathology were observed and effects on blood flow after brainstem ischemicreperfusion were investigated.Method: Male wistar rats were divided into ischemic reperfusion group,ischemia group and sham-operative group. Two minisize artery clips clamped thebasilar artery(BA) on both the first no-ramus section and the second no-ramussection, and after sometime open the BA to establish the brainstem ischemiareperfusion model; ischemia group were clamped also but no opening; andsham-operative group only discovered BA. Neural symptoms were observed afterBA occlusion. Coverage and degree of ischemia were defined with TTC stain. Thevalue of blood flow was measured with the technique of laser-Doppler before BAocclusion, respectively at 0.5h,1h,1.5h,2h,,3h and after reperfusion 10min,30min,60min. animals were killed respectively at 0.5h,1h,2h,3h,6h after BAocclusion and 1h after reperfusion, tissues of brainstem were got and observedwith light microscope.Result: After two-point occlusions of basilar artery neural symptoms appeared. They were irregular breathing, convulsion, singultus, dilation of pupils, bluntnessof light reflex, nystagmus, extremities paralysis and stupor. The coverage ofischemia mainly located in pons and part of superior medulla stained with TTC.Local blood flows on brainstem decreased significantly after two -pointocclusions of basilar artery; but local blood flows after reperfusion were differwith the baseline value, the value of 2h and 3h clamping was lower than baselinevalue, and the value of 0.Sh,1h and 1.5h clamping was higher than baseline value.Light microscope: 0.5h after occlusion had no ischemic tissue, after reperfusionobvious hemorrhage of blood vessel were also observed; lh after occlusion had noischemic tissue also, but surround of vessel stain light, after reperfusion occurredobvious vessel expanding and hemorrhage of blood vessel; 2h after occlusionnormal tissue define with the ischemic tissue, neurnal nuclear stain deepen, cellbody shrinkage, Nissl body decrease; after reperfusion ischemic range occurredobvious hemorrhage and red blood cell filling in vessel; 3h after occlusion, some,degenerated necrotic foci, myelin sheath disappearance, after reperfusion all theseexhibitions were lighten, hemorrhage of blood vessel were also observed. 6h afterocclusion, ischemic range increased obviously, myelin sheath disappearance moresevere, at the center of ischemic tissue neuronal nuclear karyopyknosis, cell bodymiss and lysis were observed,at edge of ischemic tissue cell body shrinkage andNissl body decrease, after reperfusion all these exhibitions were more severe,occur leucocytes soakage,hemorrhage and myelin sheath disappearance.Conclusion:①The symptoms of the loss of nervous function induced bytwo-points clamp of basilar artery were irregular breathing, convulsion, singultus,dilation of pupils, bluntness of light reflex, nystagmus, extremities paralysis andstupor. They are similar to the symptoms due to brainstem infarction in clinicalpatients. This model simulates some course of clinical pathology.②After reperfusion, all these symptoms of the loss of nervous function have no obviouschanges.③Observed results of pathology showed that ultra-early changes ofpathological due to the brainstem ischemic reperfusion was correlative to the timeof occlusion.④Compared with before occlusion, local blood flow of brainstemdecreased significantly after basilar artery occlusion, it suggests that the result ofbasilar artery occlusion is reliable, after basilar artery reperfusion, local bloodflow of brainstem decreased significantly, but hypo- perfusion and hyper-perfusion occur, it suggests that blood vessel auto-adjust function suffered.⑤Advantages of this model: the cerebral vessels of rats is similar to mankind's, theoperation is relatively simple, the position of ischemia is constant, animals are noteasily to die, replication is good and cost is low. The model is suitable to studypathology and pathophysiology of acute brainstem ischemia and reperfusion.