The Effects Of Selective Cerebral Ultra-profound Hypothermia On Cytoskeletal Protein In Monkeys After Occlusion Of Cerebral Blood Flow Under Different Time Limits

[Objective]To understand the influence to the cytoskeleton of neuron and glia cell by studying the expression of cytoskeletons proteinβ-tubulin,MAP-2,Vimentin and GFAP in experimental monkeys with occluding bilateral internal carotid arteries for 60 min under selective cerebral ultra-profound hypothermia after occlusion of cerebral blood flow under different time limits(0,10,15 and 20min),determine the limit time of monkey brain ischemia resuscitation under common temperature.[Methods]15 healthy adult rhesus monkeys,male,randomly were divided into 4 groups:0min group(resuscitation of 0min of bilateral internal carotid arteries blockage group,n=4),10min group(resuscitation of 10min of bilateral internal carotid arteries blockage group,n=4),15min group(resuscitation of 15min of bilateral internal carotid arteries blockage group,n=4),20min group(resuscitation of 20min of bilateral internal carotid arteries blockage group,n=3).A catheter was inserted into right internal carotid artery(ICA) to infuse 4℃cooling Ringer's liquid,two catheters were distally and proximally inserted into internal jugular vein (IJV) to extract the hypothermic diluted blood for ultrafiltration and then perfuse the warm blood into the right venae cava inferior after rewarming.Then left ICA and IJV was clamped,4℃cooling Ringer's liquid was perfused into the right ICA after ischemia at common temperature to induce the brain to cool less 16℃.After 60 minutes,Perfusion was stopped.MRI scans were obtained during preoperative and postoperative course and changes of hemodynamics were measured.The monkeys' brain was immediately removed soon after death in operation,and so did it in Long-term survival monkeys after we executed the monkeys 4 weeks after operation. Immunohistochemical technique was used to detect the level ofβ-tubulin,MAP-2,Vimentin and GFAP protein expression in the 0 min group,the 10 min group,15 min group and the 20 min group,respectively.[Results]All of the monkeys in resuscitation of 0min,10min of bilateral internal carotid arteries blockage group(n=8)lived up till they were executed.Pre and post the operation the hemodynamical parameters were steady,MRI scans were normal after operation and the function of neurological deficient scale was normal.2 long-term surviving,1 severe disable,1 died in 15min of bilateral carotid artery blockage group (n=4).All monkeys of 20 min hypothermia group were not resuscitation after perfusion and died.The level ofβ-tubulin and MAP-2 protein expression was significantly lower in 15min group and 20min group than other groups But Vimentin and GFAP on the contrary.[Conclusions](1)Selective brain ultra-profound hypothermia(14.3-16℃) may achieved by half internal carotid artery cold irritating in rhesus monkey.(2)It is safe for resuscitation in 0min,10 min brain ischemia and it is normal to the hemodynamical parameters,brain and nervous function.Ultra-profound hypothermia has obvious neuroprotection.(3)It is possible for resuscitation in 15 min brain ischemia,but result in high death and disability.Resuscitation of 20min of bilateral carotid artery blockage was invalid.Due to irreversibility brain-damage,Tubulin and MAP-2 were disaggregated;glia cell was hyperplastic and hypertrophied and increase the expression of GFAP and Vimentin protein.(4)The gold time of resuscitation for brain ischemia is probably in 10min.Life can be saved in 15min hypothermia group, but may result in different degree neurological deficits and high disability and death rate,so resuscitation is at comparative stake.