Effect of selective brain hypothermia on SUMOylation of cerebral cortex during cerebral ischemia-reperfusion in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of selective brain hypothermia on small ubiquitin-like modifier (SUMO)ylation of cerebral cortex during cerebral ischemia-reperfusion (I/R) in rats.Methods A total of 120 healthy clean-grade male Sprague-Dawley rats,aged 8 weeks,weighing 200-250 g,were divided into 4 groups (n=30 each) by a random number table method:sham operation group (group S),group I/R,selective brain hypothermia group (group H) and 37 ℃ normal saline group (group N).Rats were anesthetized with 10％ chloral hydrate 3 ml/kg.Cerebral ischemia was induced by middle cerebral artery occlusion using a nylon thread with rounded tip inserted into the right internal carotid artery and advanced cranially until resistance was met.The right middle cerebral artery was occluded for 2 h followed by reperfusion in group I/R.10-13 ℃ normal saline was infused at the rate of 100 ml · kg-1 · h-1 for 20 min starting from the time point immediately after removing the nylon thread in group H.37 ℃ normal saline was infused instead at the same rate for 20 min in N group.The neurological deficit were assessed and scored at 6,24 and 48 h after reperfusion.The cerebral cortex on ischemic side was then removed for determination of cell apoptosis (by TUNEL) and expression of SUMO sepcific proteases 3 (SENP3) and SUMO2/3-conjugated protein (by Western blot).The apoptotic rate was calculated.Results Compared with group S,the neurological deficit score and apoptosis rate were significantly increased,and the expression of SUMO2/3-conjugated protein was up-regulated at each time point after reperfusion in the other three groups (P＜0.05),and the expression of SENP3 was significantly up-regulated in I/R and N groups and down-regulated in group H (P＜0.01).Compared with group I/R,the neurological deficit score and apoptosis rate were significantly decreased,the expression of SUMO2/3-conjugated protein was up-regulated,and the expression of SENP3 was down-regulated in group H (P＜0.05).Conclusion The mechanism by which selective brain hypothermia reduces cerebral I/R injury is related to enhancing SUMOylation of cerebral cortex in rats.