Effects of simvastatin on heat hock protein 70 after spinal cord ischemia reperfusion injury

Objective To investigate the protective effect of simvastatin on spinal cord ischemia/reperfusion injury through the observation of the changes of heat shock protein 70 (Hsp70).Methods 24healthy adult Tibet mini-pigs of either sex,weighted 20-30 kg,were randomly divided into three groups (n =8),including sham operation group (group C),ischemia/reperfusion group (group I/R) and simvastatin experimental group (group Sim).In group I/R and Sim,the models of spinal cord ischemia/reperfusion were established by the occlusion of thoracic aorta and subclavian artery (70 min).The accessory hemiazygos vein was isolated and the distal end was ligated.In group I/R,1000 ml lactated ringer solution were pumped into the vein and the rate was 860 ml/h during the ischemia time.In group Sim,1000 ml simvastatin solution were pumped into the vein and the dose was 0.25 mg/kg during the ischemia time.Feed the swines of the experimental group simvastatin tablets 80 mg/d,orally for 30 days.After the operation,the motor function scores were recorded at 6,24,48 h (see Taylor motor function scoring system).All eight swines of each group were killed at 30 days after reperfusion,taking the L2-L5 and sacral spinal cord as quickly as possible.The hematoxylin and eosin (HE) staining method and the NISSLE staining method were adopted to observe the morphological changes of neurons and the immunohistochemical method was adopted to detect the changes of Hsp70.Results In group Sim,the 24,48 h motor function scores (3.2 ± 0.3,3.6 ± 0.2 respectively) after operation were significantly higher than that in group I/R (2.2 ±0.4,2.8 ± 0.4 respectively) (P ＜ 0.05).Compared with group I/R,the morphology of neurons in group Sim had a slight damage and higher expression changes of Hsp70 can be found in group Sim (P ＜ 0.05).Conclusion Simvastatin has a significant protective effect on the spinal cord ischemia reperfusion injury and the potential mechanism may be related to the up-regulation of Hsp70. Key words: Simvastatin;  Spinal cord;  Ischemia/reperfusion injury;  Heat shock protein 70; Protection